EPA-R2 73-202
April 1973 Environmental Protection Technology Series
Package Sorption Device
System Study
Office of Research and Monitoring
U.S. Environmental Protection Agency
Washington. D.C. 20460
-------
EPA-R2-73-202
Package Sorption Device
System Study
by
MSA Research Corporation
Division of Mine Safety Appliances Company
Evans City, Pennsylvania 16033
Contract No. EHSD 71-2
Program Element No. 1A2015
EPA Project Officer: D. L. Harmon
Control Systems Laboratory
National Environmental Research Center
Research Triangle Park, North Carolina 27711
Prepared for
OFFICE OF RESEARCH AND MONITORING
U. S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
April 1973
-------
This report has been reviewed by the Environmental Protection Agency
and approved for publication. Approval does not signify that the
contents necessarily reflect the views and policies of the Agency,
nor does mention of trade names or commercial products constitute
endorsement or recommendation for use.
11
-------
ABSTRACT
A Package Sorption Device System Study was undertaken
to achieve the following objectives: (1) identify and
characterize the numerous small but objectionable sources
of gaseous pollutants; (2) develop ranking of sources
according to relative importance; (3) assess the equipment
and technology available for controlling these sources;
(4) investigate the potential and need for development of
new technology and new sorbents; and (5) develop detailed
research and development recommendations to improve exist-
ing devices or develop new control methods. The primary
products of this study are: (1) a handbook on package
sorption device technology; (2) an assessment of the emis-
sions to which this technology may be applicable; and (3)
the R&D recommendations. Emission sources amenable to
control by package sorption devices contribute 15% of the
total organic emissions from all sources and can be divided
into two broad categories: (1) solvent user industries
which emit solvents essentially unchanged and (2) process
industries which generate pollutants by chemical, biological
or thermal reactions. Regenerative activated carbon adsor-
bent systems show promise for the control of pollutants from
these sources, particularly at concentrations below 700 ppm.
At higher concentrations, catalytic and thermal incinerators
are more economical except where the would-be pollutant is a
valuable solvent recoverable by the adsorbent system.
ACKNOWLEDGMENTS
This study was conducted for the Environmental Protection
Agency under Contract EHS-D-71-2 with Mr. D.L. Harmon serving
as project officer.
The study was conducted at MSA Research Corporation,
Evans City, Pennsylvania during the period August 1970 to
March 1973 under the general supervision of Dr. J.W. Mausteller.
The program manager was Dr. A,J. Juhola. Contributions to var-
ious phases of the study were made by Messrs. R.H. Hiltz, S.J.
Rodgers, W.A. Everson, O.W. Milius, R.M. Hunt, B.B. Carr, J.S.
Greer, and T.A. Ciarlariello.
-------
1v
-------
Table of Contents
Page
1. Sources and Emissions 1.1
Introduction 1-1
Information Sources 1-2
Emission Sources 1-6
Listing of Industries 1-6
Categorizing of Industries 1-6
Extent of Emission 1-8
Types of Pollutants 1-13
Listing of Pollutants 1-13
Adsorptive Characteristics 1-13
Identification With Industries 1-14
Conditions of Pollutant Release by Industry 1-20
Effect on Choice of Control System 1-20
Surface Coating Industry 1-24
Degreasing Industry 1-34
Dry Cleaning Industry 1-37
Graphic Arts Industry 1-39
Other Solvent User Industries 1-43
Rubber Products Industry 1-44
Solvent Extraction of Vegetables 1-48
Solvent and Fuel Evaporation From Storage 1-48
Meat Rendering Industry 1-51
Fish Rendering Industry 1-60
Canning Industry 1-61
Restaurants 1-63
Meat Smokehouses 1-64
Coffee Roasting 1-64
Tobacco Curing, Zinc Plating and Tanning 1-65
Control of Pollutants from Incinerators 1-65
Baking and Candy Making Industries 1-66
Other Emission Sources 1-66
2. Environmental Effects 2-1
Introduction 2-1
Evaluation of Pollutant Concentration 2-2
Toxic Effects on Humans 2-5
-------
V1
Contents (continued)
Page
Odor Effects 2-9
Psychological and Physiological Effects 2-9
Ranking of Pollutants According to Odor
Response 2-10
Odor Control 2-13
Toxic Effects of Pollutants on Vegetation 2-14
Damage to Materials 2-16
Smog Forming Potential of Pollutants 2-16
Nature of Smog 2-16
Distribution of Smog Forming Pollutants 2-17
Active Smog Precursors 2-18
Ranking of Smog Precursors 2-18
Effect of Smog on the Environment 2-20
Pollutant Regulatory Laws 2-23
Federal Standards 2-23
Control District Regulations 2-23
3. Research and Development Recommendations 3-1
Introduction 3-1
Sources and Emissions 3-1
Industry Trends 3-2
Carbon Resorb Systems. Present Technology 3-3
Carbon Resorb Systems, New Technology 3-5
Adsorption Theories 3-6
Monitoring Instruments 3-7
Research and Development Programs 3-7
Emission and Source Characterization 3-8
Evaluation of New Carbon Resorb System 3-9
Generation of Adsorption and Regeneration
Data 3-11
Monitoring Instrument Development 3-13
Summary 3-14
-------
vll
Contents (continued)
4. Sorbent Types and Sorption Theories
Sorbent Types
Important Sorbent Properties
Chemically Reactive Adsorbents
Polar Adsorbents
Nonpolar Adsorbents
Molecular Sieves
Effect of Physical Properties on
Adsorption 4-10
Theories of Adsorption 4-18
Forces of Adsorption 4-18
Adsorptive Capacity 4-19
Pore Structure Determination 4-27
Adsorption Thermodynamics 4-31
Dynamic Adsorption Processes 4-44
Adsorption of Vapor Mixtures 4-58
Resistance to Airflow 4-66
Regeneration of Activated Carbons 4-67
5. Theories and Types of Catalysts 5-1
Background 5-1
Terminology 5-1
Development 5-1
Description 5-1
Theoretical Models 5-2
Types 5-2
Geometric 5-2
Electronic 5-3
Boundary Layer 5-3
Crystal Field 5-3
Adsorption 5-3
Description 5-3
Theoretical Principles 5-3
Application 5-4
System Design Theory 5-4
Approaches 5-4
Reaction Rates 5-4
Thermodynamics 5-6
-------
Contents (continued)
Pa^e
Types of Catalysts 5.7
Noble Metals 5.7
Transition Metals 5.7
Methods and Parameters Used to Evaluate
Catalysts 5.7
Package Sorption Systems 6,-j
Introduction 6.^
Basic Functions 6.2
Air Purification Systems, Present Technology 6-4
General Discussion 6.4
Carbon Bed Designs 6-6
Materials of Construction 6-11
Operation of Air Purification Systems 6-13
Solvent Recovery Systems, Present Technology 6-18
General Discussion 6-18
Stationary Bed Systems 6-21
Moving Bed Systems 6-28
Fluidized Bed Systems 6-30
Carbon Resorb Systems, New Technology 6-32
General Discussion 6-32
Gas Regeneration with Incineration 6-35
Gas Regeneration with Secondary
Adsorption 6-38
Gas Regeneration with Condensation and
Recycle 6-40
Two-Stage Stationary Bed System 6-44
Two-Stage Regeneration of Stationary Bed 6-46
Regeneration by Pressure Reduction 6-48
Multistage with Bed Displacement 6-49
"Hypersorption" System 6-52
Rotating Axial-Flow Bed with Vapor Recycle 6-54
Materials of Construction 6-57
Auxiliary Equipment 6-58
Operation of Carbon Resorb System 6-63
Polar Adsorbent Systems 6-71
Impregnated Adsorbent Systems 6-72
-------
1x
Contents (continued)
Page
Catalyst Impregnated Carbon Systems 6-72
Economic Analyses 6-73
General Discussion 6-73
Operating Costs 6-74
Pollution Control Costs 6-78
Adsorbents and Adsorbent Systems1 Manufacturers
and Vendors 6-87
Activated Carbons 6-87
Noncarbon Adsorbents 6-93
Sorption Systems 6-94
7. Catalytic Incineration System 7-1
Basic Functions and Limitations 7-1
Oxidation and Reduction Functions 7-1
Advantages 7-2
Disadvantages 7-3
Potential Applications 7-4
System Design Parameters 7-5
Type of Catalyst 7-6
Type of Pollutant 7-6
Pollutant Concentration 7-9
Operating Temperature 7-11
Residence Time 7-12
Operating Costs 7-15
Equipment 7-15
Depreciation 7-15
Operating Labor 7-15
Maintenance 7-16
Electrical Power 7-16
Fuel 7-16
Auxiliary Equipment 7-16
Ducts and Supports 7-17
Filters and Scrubbers 7-17
Blowers 7-17
Preheaters 7-17
Heat Exchangers 7.18
Monitors and Controls 7-18
-------
Contents (continued)
Care of Incinerator 7-20
Start-up 7-21
Maintenance 7-21
Storage 7-21
Catalytic Equipment Manufacturers 7-21
8. Pollutant Detection 8-1
Introduction 8-1
Methods of Sampling Gases 8-2
Techniques and Instruments for Monitoring 8-4
Introduction 8-4
Methods of Analysis 8-6
Recommended Methods for Specific Classes of
Impurities 8-23
Hydrocarbons 8-23
Oxygen Containing Organic Compounds 8-23
Halogenated Compounds 8-23
Inorganic Oxides 8-23
Odors 8-24
Aromatic Hydrocarbons 8-24
Polynuclear Hydrocarbons 8-24
Appendix A - Glossary A-l
Appendix B - Information Sources on A1r Pollution B-l
Appendix C - Tables of Data C-l
Appendix D - Methods D-l
Method for Calculating Vm D-l
Lower Explosive Limits of Mixtures D-2
Van der Waals1 Constant a D-3
CC14 Test Method ~" D-4
Activated Carbon Regeneration D-7
Appendix E - Sample Calculations E-l
Heat of Adsorption E-l
Free Energy of Adsorption E-3
-------
xi
Contents (continued)
Page
Adsorption Zone E-5
Calculation of Lc at Different Cb/Ci E-8
Calculation of Lz and LC, Klotz Equation E-10
Calculations for Adsorbed-Vapor Profile as
Presented in Figure 4-18 E-12
Calculations for Adsorbed-Vapor Profile as
Presented in Figure 4-19 E-15
Estimate of Secondary Adsorber Size for Gas
Regeneration with Secondary Adsorption
System E-24
Calculations on Carbon-Resorb with Gas Regen-
eration, Condensation and Vapor Recycle E-27
Calculation of Service Times for Multistage
with Displacement of Beds E-31
Appendix F - Literature Cited F-l
Appendix G - Bibliography 6-1
-------
xii
-------
xiii
List of Tables
Table No. Page
1-1 Number of Complaints per Year per
Million Population 1-4
l-II Small Stationary Emission Sources
of Air Pollutants Grouped According
to Preferred Control Device, Esti-
mated Emission Rates 1-7
l-III Rates of Gaseous Pollutant Emissions
from Nine Survey Areas, Pollutant
Emission Rate, Ib/da per 1000 People 1-10
1-IV Amounts of Organic Pollutants Emitted
by Small Stationary Sources Based on
San Francisco Bay Area (1969) Report 1-11
1-V Number of Pollutants Identified with
Each Industry 1-15
1-VI Most Generally Used Nonhalogenated
Solvents 1-17
1-VII Halogenated Solvents Used in Degreasing 1-17
1-VIII Solvents Used in Dry Cleaning 1-18
1-IX Components of Gasoline Vapors 1-18
1-X Pollutants Appearing at Highest Con-
centration from Meat Rendering Oper-
ations 1-19
1-XI Malodorous Pollutants Emitted from
Fish Rendering 1-19
1-XII Pollutant Vapors Emitted from Coffee
Roasting, Tobacco Curing, Meat Smoke-
houses, Tanning and Zinc Plating In-
dustries 1-21
1-XIII Estimated Air Pollutant Emission Rates,
Surface Coating Solvents 1-27
1-XIV Surface-Coating Formulas on an As-
Purchased Basis (Weiss 1967) 1-27
-------
(Tables continued)
Table No. Page
1-XV Gray Epoxy Appliance Primer Form-
ulation 1.28
1-XVI Acryl1c-Epoxy Appliance Enamel
Formulation 1-28
1-XVII Vinyl Lacquer Formulation for
Aluminum Siding 1-29
1-XVIII Base for Furniture Rubbing or Flat
Varnish 1-29
1-XIX Solvent Emissions from Surface Coatings
Operations (Bay Area, 1969) 1-30
1-XX Composition of a Common Lacquer Thinner 1-32
1-XXI Carbon-Resorb System Size, Operating
Conditions, Regenerating Steam Cost
for Control of Spray-Booth Solvent
Emission 1-32
1-XXII Amount of Solvent Emitted by Plastics,
Rubber, Paper Coating and Pharmaceutical
Industries 1-43
1-XXIII Properties of Solvents Emitted from
Natural and SBR Rubber 1-46
1-XXIV Properties of Solvent Emitted from the
Synthetic Rubber Industry 1-47
1-XXV Emission Factors from Synthetic Rubber
Plants Pounds per Ton of Product,
(MacGraw, 1970) 1-49
1-XXVI Concentration of Pollutants in Plant
Air at Various Operating Areas or
Exhaust Vents 1-53
1-XXVII Pollutant Vapors Emitted from Meat
Rendering Processes 1-56
1-XXVIII Most Abundant Pollutants in Vapor Mix-
tures from Crackling, Grease and Tallow
During Rendering 1-58
-------
XV
(Tables continued)
Table No. Page
1-XXIX Pollutant Emissions from F1sh Rendering 1-60
1-XXX Pollutant Emission Factors for Three
Types of Incinerators 1-66
2-1 Federal Ambient Air Quality Standards 2-3
2-II Relative Amounts of Pollutants Emitted
from Various Sources (California 1969) 2-4
2-III Ranking of Pollutants in Decreasing
Order of Toxicity to Humans 2-6
2-IV Ranking of Pollutants in Decreasing
Order of Odor Recognizability 2-11
2-V Odor Interaction in Mixtures 2-13
2-VI Relative Concentrations of the More
Reactive Hydrocarbons That Produce
Biological Response Similar to That
Produced by Ethene 2-15
2-VI I Sources of Smog Forming Pollutants of
High and Low Activities 2-17
2-VIII Pollutants from Small Emission Sources
that Are Active Smog Precursors 2-19
2-IX Pollutant Reactivity Ranking as Smog
Precursors 2-21
2-X Ranking of Organic Pollutants Producing
Eye Irritant and Vegetation Damaging
Smogs (Data from Altshuller, 1966) 2-22
3-1 Summary of One Million Dollar Research
and Development Plan (A) 3-15
3-II Summary of Three Million Dollar Research
and Development Plan (B) 3-16
4-1 Types of Impregnated Adsorbents 4-3
4-II Effect of Pollutant Physical Properties
on Adsorptive Affinity for Silica Gel,
Decreasing Order of Affinity Downward 4-5
-------
(Tables continued)
Table No.
4-III Effect of Pollutant Physical Properties
on Adsorptlve Affinity for Activated
Carbon at 100°F§ Increasing Order of
Affinity Downward 4-6
4-IV Types of Molecular Sieves 4-8
4-V Effect of Molecular Sieve Pore Diameter
on Selective Adsorption of Pollutant
Vapors 4-9
4-VI Physical Properties of Adsorbents,
Surface Areas and Pore Volumes 4-11
4-VII Physical Properties of Adsorbents,
Densities and Mean Pore Diameters 4-11
4-VIII Physical Properties of Activated
Carbons, Densities, Carbon Tetra-
chloride Activities and Surface Areas 4-17
4-IX Adsorption Data and Calculated AH and
k for Butane on Activated Carbon Type BP 4-31
4-X Free Energy Change AF During Adsorption
of Butane on Activated Carbon 4-34
4-XI Entropy Change AS During Adsorption of
Butane on Activated Carbon 4-34
4-XII Variation of AF or ci with Temperature
and Amount u> of Propane Adsorbed on
Type L Carbon 4-35
4-XIII Lc Calculated from Lz Using Equation
4-27 4-53
4-XIV V and Dv for Frequently Encountered
Pollutants and Solvent Vapors 4-57
4-XV Selected Conditions for Adsorption of
a Ternary Solvent Mixture Used in
Spray Coating Operations 4-61
4. XVI Summary of Adsorbed-Vapor Profile Data
of Figure 4-18 4-61
-------
xvi i
(Tables continued)
Table No. Page
4-XVII Summary of Adsorbed-Vapor Profile
Data of Figure 4-19 4-64
4-XVIII Regeneration of Trichloroethene-
Activated Carbon System Based on
Figure 4-21 Profiles 4-75
4-XIX Estimated Operating Capacities and
Steam Requirements for Recovery of
Trichloroethene, 4-Methyl-2-pentanone
and Propanone for a One-Hour Adsorption-
Regeneration Cycle Time, Carbon Equili-
brated at 3000 ppm 4-76
4-XX Estimated Steam Requirements to Regen-
erate Carbons Equilibrated with 4-Methyl-
2-pentanone, Trichloroethene and Propanone
at 10 ppm Influent Concentration and at
Varied Operating Capacities. 212°F Steam
Used 4-77
6-1 Correlation of Pollutant Concentration
with Odor Level, Emission Source, and
Type of Adsorbent System Required 6-3
6-II Effect of Pressure on Adsorptive Capacity
of Carbon for Propanone, 10 ppm Concen-
tration 6-48
6-III Service Time for Pollutant Vapors at
Varied Concentrations in a Two-Stage
System with Displacement of Beds 6-49
6-IV Auxiliary Equipment for Sorbent Type Air
Pollution Control Systems 6-58
6-V Effect of Temperature on Adsorptive
Capacity and Equilibrium Concentration
for 4-Methyl-2-pentanone Adsorbed on
BPL V-Type Carbon 6-68
6-VI Packaged Vapor Adsorption and Recovery
Systems, Approximate Equipment Cost and
Size 6-76
-------
xviii
(Tables continued}
Table No. Page
6-VII Cost Factors for A1r Pollution Control
by Carbon Resorb Systems 6-81
6-VIII Cost Factors for Air Pollution Control
by Catalytic and Thermal Incinerators 6-82
6-IX Effect of Pollutant Molar Volume and
Concentration on Air Cleaning Cost When
No Pollutant Recovery or Disposal Cost
is Considered 6-83
6-X Cost Factors for Air Pollution Control
by Carbon-Resorb Systems at Two Flow
Capacities 6-84
6-XI Effect of Cycle Time on Cost of A1r
Cleaning for 3,800 fta/min Carbon-Resorb
System, 500 ppm Pollutant Concentration
with Steam Regeneration 6-85
6-XII Estimated Operating Cost, Continuous
Recycle Unit Including Solvent Recovery 6-88
6-XIII Estimated Operating Cost, Continuous
Recycle Unit with Concentration of
Pollutant for Subsequent Recovery of
Disposal 6-89
6-XIV Activated Carbon Suitable for Air
Pollution Control Applications 6-90
7-1 Minimum Temperature for Initiating
Catalytic Oxidation and Autolgnition
of Organic Pollutant Vapors in Air,
Degrees Fahrenheit 7-8
7-II Pollutant Concentration Required for
Self-Sustained Catalytic Combustion
at 90% Conversion Level 7-10
7-III Heat Input from Pollutant Combustion at
Varied Concentrations 7-10
7-IV Auxiliary Equipment for Catalytic
Incinerators 7-16
-------
xix
(Tables continued)
Table No. Page
8-1 Classification of Analytical Methods 8-5
8-II Common Analytical Methods Used for
Air Pollutant Detection 8-7
8-III Partial Listing of Gases and Vapors
Detectable in the ppm Range 8-12
C-I Properties of Pollutant Vapors Emitted
from Small Stationary Sources C-l
C-II FlammabiHty Characteristics of Organic
Vapors in Air C-9
D-I Numerical Values for the Constants of
Equation 2 D-8
D-II Numerical Values for the Constants of
Equation 3 D-8
D-III Numerical Values for Constants in
Equation 12 D-ll
E-I Data Used for Calculating AF in Table
4-12 E-3
E-II AF Based on p0 and f0 E-4
-------
XX
-------
xxi
List of Ficures
Figure No. Paqe
<^**'""**"^^l'"*- taMMM
1--1 Degreaser Using Halogenated Hydro-
carbon Vapors 1-35
1-2 Dry Cleaning Machine with Integrated
Carbon Solvent Recovery System.
Courtesy of Vic Mfg. Co. 1-35
1-3 Typical Rates of Odor Emissions and
of Vapor Emissions from a Batch-Type
Rendering Cooker Reducing Inedible
Animal Matter 1-54
4-1 Pore Size Distribution Curves for
Activated Carbons with Cumulative Pore
Volume Calculated Per Unit Carbon Weight
I Darco Carbon, IV Superactivated Coco-
nut, II Type BP Pittsburgh Activated
Carbon, and III Type SXA Union Carbide
Corp. 4-14
4-2 Pore Size Distribution Curves for Acti-
vated Carbons with Cumulative Pore
Volume Calculated Per Unit Carbon Bulk
Volume Basis, I Darco Carbon, IV Super-
activated Coconut, II Type BP Pittsburgh
Activated Carbon, and III Type SXA Union
Carbide Corp. 4-15
4-3 Adsorption Isotherms of Hydrocarbon
Vapors, Amount Adsorbed w at Pressure p
on Type Columbia L Carbon at 100°F, Liquid
Volume of w at Boiling Temperature. 4-21
4-4 Adsorption Isotherms of Butane at Three
Temperatures on Pittsburgh BPL Type Car-
bon, Amount w Adsorbed at Pressure p.
Data from Grant (1962). 4-23
4-5 Isotherms of Water on Activated Carbons
Showing Hysteresis Between Adsorption
and Desorption Branches, I Darco Carbon,
II Typical of Pittsburgh BP or Union
Carbide SXA. 4-24
4-6 Nitrogen Isotherm on Activated Carbon at
-195°C Showing Hysteresis Loop Extending
from p/p0 = 0.5 to 1.0 4-28
-------
xx 1 i
(Figures continued)
Figure No. Page
4-7 Isosteres for Butane on Activated
Carbon, Type BP 4.33
4-8 Variation of Free Energy AF or Polanyi
Potential e-j with Amount of Vapor w
Adsorbed on Activated Carbon, w Measured
per Gram of Vapor and AF and ei per Mol
of Vapor 4-36
4-9 Variation of Free Energy AF or ei, with
Amount of Vapor to Adsorbed on Activated
Carbon, u, AF and CT Measured per Gram
of Vapor 4-38
4-10 Generalized Isotherms for Propane,
Butane and Pentane 4-40
4-11 Generalized Adsorption Curves for Three
Widely Different Types of Activated Carbon 4-41
4-12 Generalized Adsorption Curves Typical of
Activated Carbons Used in Gas Masks and
Solvent Recovery 4-42
4-13 Movement of Vapor Concentration Distri-
bution Curve in Carbon Bed with Increased
Adsorption Time 4-45
4-14 Effluent Concentration Curve of Butane
Vapor from an Activated Carbon Bed as
Function of Time 4-47
4-15 Butane Vapor Distribution in Activated
Carbon Bed at Time when Vapor has Started
to Penetrate Bed 4-49
4-16 Service Time - Bed Length Curve for Ad-
sorption of Butane on Activated Carbon 4-51
4-17 Effect of Gas Velocity, U, on Adsorption-
Zone Length, LZ» for Carbons of Mean
Particle Diameter, Dp, and Vapor Molar
Volume, V, 4 to 10 Mesh * 0.35 cm, 6 to
16 Mesh % 0.24 cm and 12 to 20 Mesh *
0.12 cm. 4-56
-------
XXiii
Figure No.
(Figures continued)
4-18 Adsorbed Vapor Profile in an Activated
Carbon Bed After Steady State is Estab-
lished but with no Coadsorption 4-60
4-19 Adsorbed Vapor Profile in an Activated
Carbon Bed After Steady State is Estab-
lished with Coadsorption 4-63
4-20 Adsorbed-Phase Profile for Trichloro-
ethene at Service Time when Vapor Starts
to Penetrate Bed, BPL V Type Carbon 4-68
4-21 Adsorbed-Phase Profiles for Trichloro-
ethene at Various Stages of Regeneration,
BPL V Type Carbon 4-68
4-22 Amount of Steam Required to Regenerate
BPL V Type Carbon Equilibrated wi.th Tri-
chloroethene at Varied Concentrations 4-71
4-23 Amount of Regenerating Agent Required to
Regenerate BPL V Type Carbon Equilibrated
with Propanone at Varied Concentrations 4-72
4-24 Amount of Regenerating Agent Required to
Regenerate GI Type Carbon Equilibrated
with 4-Methyl-2-Pentanone at 10 and 3000
ppm Concentrations 4-73
6-1 Central Ventilation System Showing Par-
ticulate Filter and Carbon Bed for Air
Purification 6-7
6-2 Multiple Cell Activated Carbon Filter
for Air Purification 6-9
6-3 A Chemical-Biological-Radiological
Filter, Size 12 by 12 by 8 in., Operated
at 48 ft'/min for Small Protective Shel-
ters. Courtesy MSA Co. 6-10
6-4 Pleated Type Carbon Filter for Control
of Radioactive Pollutants, Size 24 by 24
by 11.5 in., Operated at 1000 ft3/min
Flow. Courtesy of MSA Co. 6-10
-------
XXI V
(Figures continued)
Figure No. Page
6-5 Radial Flow Canister Design for Air
Purification Systems. Courtesy of
Connor Engineering Corp. 6-12
6-6 Arrangement of Canisters on a Slanted
Manifold Plate for Medium and Large Air
Purification Systems 6-12
6-7 Self-Contained Canister Type Air Puri-
fier for Small Occupied Spaces. Cour-
tesy of Connor Engineering Corp. 6-12
6-8 Pressure Drop Through Granular Carbon
Beds of Varied Mesh Size Fractions as
Function of Flow Velocity 6-15
6-9 Stationary Bed Carbon Resorb System
with Auxiliaries for Vapor Collection
and Solvent Separation from Steam Con-
densate or Incineration of Pollutant
Vapors 6-20
6-10 Cut-Away Diagram of Solvent Recovery
Adsorber, Showing Vapor-Airflow Pattern
During the Adsorption and Steam Flow
During Desorption. Courtesy of Vic
Manufacturing Company. 6-22
6-11 Stationary Bed Solvent Recovery System
of 3000 ftVmin Flow Capacity for Each
Adsorber. Used for Water Immiscible
Solvents. Courtesy of Vic Manufacturing
Company. 6-22
6-12 Flow Diagram of a Solvent Recovery
System. Courtesy of Vulcan-Cincinnati,
Inc. 6-23
6-13 Solvent Recovery System for Recovery of
Naphtha from a Rubber Products Plant,
12,000 ft3/min Flow Capacity. Courtesy
of Vulcan-Cincinnati, Inc. 6-23
6-14 Small Cabinet-Enclosed Solvent Recovery
Unit, 700 ft3/min Capacity, Steam Regen-
eration. Courtesy of Hoyt Mfg. Corp. 6-27
-------
XXV
(Figures continued)
Figure No. page
6-15 Continuous Rotary Bed, Based on Sutcliffe
Speakman Co., LTD Illustrations, 66
Palmer Ave., Bronxville, N.Y. 6-29
6-16 Fluidized Bed Solvent Recovery System 6-31
6-17 Air Pollution Control System Utilizing
Carbon-Resorb with Gas Regeneration and
Incineration of Desorbed Pollutants
(from Mattia, 1970). 6-37
6-18 Adsorption-Phase Profile After Carbon
Bed Has Been Regenerated, When L is 4
to 8 in., and wr is Residual Capacity. 6-37
6-19 Pollutant Desorption Rate Variation with
Regeneration Time 6-39
6-20 Air Pollution Control System Utilizing
Carbon-Resorb with Gas Regeneration and
Secondary Adsorber for Desorbed Pollutants
(from Mattia, 1970). 6-39
6-21 Air Pollution Control System Utilizing
Carbon-Resorb with Gas Regeneration,
Condensation, and Recycle of Uncondensed
Vapor. 6-42
6-22 Adsorbed-Phase Profiles at the End of
Adsorption and Regeneration for a Gas
Regeneration-Condensation-Recycle Process,
Lt s 21.3 in. 6-45
6-23 Two-Stage Stationary Bed System 6-47
6-24 Stationary Bed with Two-Stage Steam
Regeneration 6-47
6-25 Multistage Pollutant Control System,
Internal Construction of a Two-Stage
System, Courtesy T. Melsheimer Co., Inc. 6-50
6-26 Two-Stage Pollutant Control System,
10,000 ft3/min Capacity, Courtesy T.
Melsheimer Co., Inc. 6-50
-------
xxv i
(Figures continued)
Figure No. Page
6-27 Moving-Bed System for Separation of
Low Molecular-Weight Gases (Berg,
1947) 6-53
6-28 Rotating Axial-Flow Bed, Plan and
Elevation 6-55
6-29 Rotating Axial-Flow Bed, Showing Seal
Detail and Mechanism for Raising and
Lowering Bed 6-55
6-30 Rotating Axial-Flow Bed with Condenser
and Recycle for Uncondensed Vapors,
3,800 ft3/min Airflow Capacity, 6 ft
Bed Diameter 6-56
6-31 Comparative Costs of Pollution Control
with Carbon Resorb, Catalytic Incinera-
tion and Thermal Incineration, 3,800
ft3/min Capacity System, Calculations
Based on 4-Methyl-2-Pentanone and Pro-
panone, 2080 hr/yr Operating Time. 6-79
6-32 Steam Requirement for Regeneration vs
Pollutant Loading and Cycle Time,
Carbon-Resorb System on 4-Methyl-2-
pentanone, 3,800 ft3/min Flow, 2080
hr/yr Operating Time. 6-86
7-1 Basic Catalytic Incinerator Components 7-1
7-2 Effect of Temperature on Catalytic
Combustion of 2-Butanone on Pt/alumina,
4" Depth Honeycomb Bed, 80,000 Space
Velocity and 10% LEL Concentration 7-12
7-3 Effect of Residence Time on Catalytic
Combustion Conversion Efficiency 7-13
7-4 Basic Catalytic Incinerator with Gas
Burner to Supply Preheat 7-19
7-5 Catalytic Incinerator with Heat Ex-
changer to Supply Preheat 7-19
7.6 Catalytic Incinerator with Burner to
Supply Preheat and Secondary Exchanger
to Recover Heat for Process Use 7-19
-------
XXV11
(Figures continued)
Figure No. Page
D-l Static CC14 Test Apparatus D-6
D-2 Logic Diagram for Air-Regeneration D-12
D-3 Logic Diagram for Steam-Regeneration D-14
D-4 Logic Diagram for Steam-Regeneration,
Figure D-3 continued D-15
-------
xxvii i
-------
xx 1x
Introduction
Objectives and Scope of Study
The packaqe sorption device system study was conducted
for the Environmental Protection Agency, under Contract Number
EHS D 71-2, by MSA Research Corporation, Evans City, Pennsyl-
vania. It deals with packaged solid sorption devices for the
control of gaseous air pollutant emissions.
The study had as its primary objectives the preparation
of a handbook on packaged sorption device technology, an
assessment of the emissions to which the technology may be
applicable, and the development of recommendations for future
research and development of packaged sorption devices.
The term "packaged" connotes a size limitation on the
device and thereby, also, on the size of the pollutant emission
source which the device would control. For the purpose of this
study, these sources are referred to as small emission sources
to differentiate them from mobile and other larger stationary
sources.
The term "packaged device" is loosely defined as (1) a
factory assembled device transportable as a unit and/or (2) a
device which can be assembled on site from a few prefabricated
and readily transportable components. Such packaged devices
are characterized by:
1. Smal1 size
2. Simple, easy installation
3. Availability in essentially off-the-shelf form
4. Relatively low maintenance
5. Relatively low cost
In order to match emission volumes from the small
emission sources with potential packaged control devices,
the air handling capacities of various sized activated carbon
solvent recovery systems were used as a measuring guide.
Factory assembled solvent recovery systems that are essentially
off-the-shelf sizes are commercially available up to 10,000
ft3/min airflow capacity. Such a system would have the
approximate overall length and width dimensions of 38 and 12
ft and overall height of 16 ft. Solvent recovery systems up
to 50,000 ftVmin airflow capacity are available that fit the
prefabricated-component definition. Emission sources of over
50,000 ftVmin flow rate and custom built systems to handle
these higher flow rates were considered outside the scope of
this study.
-------
XXX
Although the major emphasis in this study was on sorbent
devices, some necessary but limited investigations were also
conducted on competing devices involving catalytic and thermal
incineration.
Small emission sources, amenable to control by packaged
devices, are exemplified by such sources as (1) small solvent
users - dry cleaners, degreasers, and printing shops and (2)
small processing and service industries - meat and fish render-
ers, coffee roasters, restaurants and bakeries. The general
characteristics of these small sources are: (1) they are
numerous, (2) the emission streams are generally of the order
of 10,000 ft3/min or less, and (3) because of their small
size their polluting effects are generally felt only in local
areas.
To achieve the primary objectives the study involved
effort in three areas:
1. Identify the small emission sources and determine
the nationwide extent and type of gaseous air pollution
from these sources.
2. Evaluate the existing technology of small fixed
bed sorbent and catalytic incineration package devices
for the control of these sources.
3. Assess potential new technology to control pol-
lution from these sources using fixed bed sorbent
devices.
Report Content
The report consists of two parts. Part I is oriented
toward the needs of management personnel in Government and
industry, responsible for planning of future action in pollu-
tion control. Part II is directed more toward the needs of
design engineers, fabricators, and users of control devices.
Part II also contains information directed to the scientists
interested in adsorption.
Part I presents the acquired information on the emission
sources and recommendations for future research and develop-
ment of packaged sorption devices. The information on emission
sources was collected from Government publications (federal and
local), trade journals, monographs, encyclopedias, interviews
with trade associations and plant visits. In this part, the
operating entities that were reported to be major small emis-
sion sources were studied in detail to determine the extent,
-------
xxx i
type, and circumstances of the pollutant emitted from each.
On the basis of this knowledge several evaluations were made.
Industries were ranked according to total amount of pollutants
emitted by each and again according to potential harm to
environment of pollutants emitted by each. Determinations
were also made regarding type of device (sorbent, catalytic
incineration, or thermal incineration) which would be the
most economical one to use to control the pollutant emission
from each major operating entity. As primary objective of
this phase of the study, recommendations are presented for
future study to fill in the information gaps.
Part II, also entitled Package Sorption Device Technology
Handbook, is the most important product of this study. In
this part of the report several aspects of pollution control
technology are considered, with the major emphasis, again, on
the sorbent type systems. A theoretical basis is presented
which permits the prediction of behavior of sorbents for the
variety of pollutants emitted and circumstances of emission
that would be encountered. Various sorbent systems are dis-
cussed with respect to their adaptability to air pollution
control. Some systems are commercially available (activated
carbon solvent recovery systems), some are proposed systems
that have undergone limited pilot plant tests but have not
as yet been reduced to commercial practice, and some are still
in the conceptual stage, appearing sound on theoretical bases.
Economic analyses are presented for the operation of carbon
adsorbent systems, catalytic incinerators, and thermal incin-
erators under several operating circumstances. These results
present a cost level that can be expected for pollution con-
trol and also indicate the operating conditions under which
each of the three competing systems would be the most eco-
nomical to use.
The appendix contains a bibliography pertinent to air
pollution and its control by sorption and incineration.
-------
xx xi 1
-------
xxx iii
Summary and Conclusions
Study Approach
To attain the objectives of the study, a procedure of
action was devised to collect available information on:
(1) small emission sources, (2) environmental effects of
the emitted pollutants, and (3) packaged sorbent and cata-
lytic incineration technology suitable for control of such
sources. The collected information was analyzed and used
to: (1) categorize the emission sources as to volume output
and pollutant type, (2) evaluate the adverse environmental
effects of pollutants from small emission sources and (3)
evaluate the control technology in present use and further
investigate the reed and potential for development of new
sorption system technology.
Information on emissions and control technology was
sought from numerous sources: trade associations, local and
state pollution control agencies, sorption device users and
manufacturers, trade journals, text books, monographs, govern-
ment documents, and vendor sales literature. The methods of
data collection included plant visits to manufacturers and
users of control systems. A questionnaire survey of pollution
control agencies was also used to elicite information to iden-
tify and characterize small sources and their emissions.
Emission Sources Characteristics
Information Search
To fulfill the study objectives regarding emission sources
in the most satisfactory manner, the study required detailed
information on: (1) identity of small emission sources, (2)
amount of pollutant emitted at each source, (3) concentration
of pollutants in each emission gas stream, and (4) types of
pollutants emitted in each gas stream. During the processing
of data from the various information sources, it became
apparent that emission data in the desired detail was not
available. The questionnaire, which was sent on a trial basis
to nine large pollution control districts, was expected to tap
a rich source of detailed information of the required type.
However, the response to the questionnaire was incomplete
because of general lack of data of the type requested. The few
agencies which do collect detailed emission data are not
sufficiently staffed or funded to allow compilation of avail-
able data for the numerous requests they receive. The
agencies in the State of California, in particular, have
collected extensive data but would not provide it in any form
other than formal reports and publications. Because of this
-------
XXXIV
problem, the study was of necessity developed from more
approximate data as presented in the control district
formal reports, trade association journals, and special
reports. Information on types of pollutants were extracted
from process descriptions as presented in text books, mono-
graphs and encyclopedias.
Extent of Small Sources Emissions
Based on survey figures given in formal reports from
nine large air pollution control districts, - California
South Coast Basin, San Francisco Bay Area, San Diego Bay
Area, Delaware Valley, Denver, Hamilton County in Ohio, St.
Louis, Washington (D.C.), and Jacksonville in Florida, -
the estimated average rates of various types of gaseous
emissions during the years 1968 to 1970 were:
Sources and type Average rate, Ib/da per 1000 people
All sources organic
vapors (includes
motor vehicle fuel
and exhaust emis-
sions) 800
Industrial processes
organic vapors 100
The combined population of the survey areas was about
27 million, or over 13% of the total U.S. population. These
are also the areas of greater population density; hence, the
emission rates given are characteristic of areas where pollu-
tion problems are most acute and controls are most needed.
The 100 Ib/da of industrial process organic vapors
virtually comprise emissions from small emission sources.
This rate, however, is not typical of all control districts;
it is based on such widely varying rates as 20 Ib/da for
Denver to 156 Ib/da for San Francisco Bay Area. To these
rate figures should be added the emissions from an important
small emission source, the petroleum distillate marketing
chain, which did not appear in the industrial process emission
rate figures. An average distillate emission rate for the
nine districts could not be determined, but it is expected to
be substantial because the average for the three California
districts was 60 Ib/da per 1000 people. Because of the
variations in emission rates from area to area and lack of
complete data for all areas, it was not possible to determine
the proportion of emissions from small sources relative to
-------
XXXV
organic vapors from all sources
portion is 15% with the balance
vehicles.
with exactness. The
being primarily from
estimated
motor
Small Emission Sources Identity and Ranking
Over fifty industries were considered in the study but
for many of them comprehensive information permitting deter-
mination of their contribution to total organic emissions from
small sources was lacking. The best guide in this respect was
the California control districts which were the only ones to
present any extensive breakdown of industrial processes into
specific industries. On the basis of their data, 22 industries
were identified as important small emission sources because of
quantity of pollutants emitted or because of intense adverse
effects of their pollutants on the environment. The emissions
from them are predominantly organic except for the zinc plating
operations which emit only NH3 and HC1. Rubber products and
domestic incineration also emit S02 and the rendering indus-
tries, H2S.
Industry
Surface coating
Degreasing
Dry cleaning
Graphic arts
Plastic products
Rubber products
Adhesives production
Paper coating
Vegetable oil extraction
Organic liquid marketing
and storage
fuel
nonfuel
Meat rendering
Fish rendering
Canning
Food serving
Coffee roasting
Tobacco curing
Tanning
Meat smoke treatment
Domestic incineration
Zinc plating
Emission rate, '
Ib/da per 1000 people
96
20
10
3
30
5.1
0.25
1.6
0.02
140
-------
xxxvi
Baking 0,04
Candy making -
(1) For some industries (as for instance canninq) no
rate figures were given, but are recognized as pollutant
emission sources of importance.
The industries comprising the small emission sources
were classified into two groups: (1) the solvent user
industries, the first ten in the list, and (2) the process
industries, the last twelve in the list, which generate
pollutants through thermal, chemical, or biological pro-
cesses. The solvent user industries clearly emit a larger
volume of pollutants (solvents) than the process industries,
except for domestic incineration. Domestic incineration was
permitted in the San Francisco Bay Area at the time of the
survey, but the general trend in the country is to ban all
domestic incineration, and dispose of solid refuse by means
which do not pollute the atmosphere.
The surface coating industry, the largest solvent
emitter, is comprised of many small operating units. Of
these,the industrial spray booths are the most numerous and
are responsible for 45% of the surface coating emissions.
Emissions from ovens and dryers used to cure the coatings
contribute 17% of the total. Nonindustrial means such as
outdoor painting contribute 36%.
the
e.
ate
The next largest organic vapor emitting industry is th
industry indicated as organic liquid marketing and storage.
This includes, as the major entity, the petroleum dlstillat
distribution and marketing chain where the largest vapor
losses occur from gasoline marketing.
The other solvent user industries drop off considerably
in emitted volumes.
Type of Pollutants
The chemical species of pollutants emitted from solvent
user industries and process industries are quite different.
Solvent emissions from the degreasing and dry cleaning indus-
tries are predominantly the chlorinated solvents, - trichloro-
ethene, tetrachloroethene, trifluorotrichloroethane - the
three most commonly used ones. Solvent emissions from other
users are: hydrocarbons (aromatic,olefinic, naphthenic and
aliphatic), alcohols, ketones, ethers, glycol ethers, esters,
-------
xxxvi i
and nitroparaffines. In these industries the nature of the
emission is quite predictable from the solvent blends entering
the process except where high temperature drying or baking
operations are carried out. In these cases the pollutant mix-
ture may also contain decomposition products of drying oils,
resins, and high boiling solvents.
Pollutant emissions from the process industries are
predominantly decomposition products of materials entering
the process. The chemical species found in the emissions
from various thermal processes are predominantly aldehydes,
organic acids, amines and sulfides.
Conditions of Pollution Emission
In addition to pollutant type, the conditions of pollution
emission such as concentration, total gas flow, gas temperature,
humidity, and particulate matter in the gas stream also vary
between emission sources and must be known before the source
can be characterized and the type and size of control system
best suited for its control determined. Recovery value of
the pollutant is an additional factor that has an important
bearing on the selection of control system. To obtain the
necessary information on operating conditions and determine
the best suited control system, an in-depth study was done on
each of the 22 industries as listed.
For pollutants of low recovery value, the favorable
conditions for control by incineration are, high concentration
and/or elevated temperature. Emissions from coffee roasting
and meat smokehouses occur under these conditions. For
pollutants of high recovery value, carbon adsorbent systems
are highly economical to operate when the concentration is
high and gas temperature is moderate. Emissions from most
of the solvent user industries occur under these conditions.
Environmental Effects
Pollutants produce effects in the environment through
various means that make life unpleasant or difficult. Most
important is the toxic effect which can produce discomfort,
illness and lower the performance efficiency of humans and
animals. Pollutants can cause serious damage to vegetation.
Other effects are damage to property through corrosion,
discoloration and soiling, A nuisance effect which arouses
the most immediate complaint is the bad odor response to
many pollutants. Some pollutants, although not directly
damaging to the environment, react with nitric oxides with
the aid of the sun's radiation to produce smog which obscures
visibility and produces discomfort and illness since it con-
tains oxidants that are toxic.
-------
xxxvi ii
The pollutants emitted by the solvent user industries
are not highly toxic nor malodorous (except for I^S from
rubber products), but about 20% of them are smog precursors.
Their damage to the environment is primarily by this route.
Smog precursors have been identified with branched chain
ketones, substituted aromatics and hydrocarbons containing
unsaturated bonds. Aldehydes are also smog precursors but
are rarely used as solvents. Los Angeles County Air Control
District recognized this factor as a major cause of air
pollution and issued Rule 66 which drastically limits the
use of smog active solvents.
Compared to solvent emissions, the pollutant emissions
from process industries are more toxic, malodorous and
corrosive. The latter emissions also contain a large portion
of aldehydes and olefinic compounds and thereby also con-
tribute to smog formation. Because of the small quantity of
pollutants emitted, the threat to the environment by the
process industries is considerably less than that from the
solvent user industries.
Packaged Air Pollution Control Devices
Information Sources
Most of the information that proved of value in this
area was obtained from technical reports in scientific
society and trade journals, from monographs, sales literature,
and discussion with technical representatives of manufacturers
of devices, catalysts and sorbents. Information was sought
and found on theoretical aspects of adsorption and catalytic
combustion, types of available devices, their potential appli-
cations to small emission sources, their operations and main-
tenance, and their operating costs.
Characteristics of Pollution Control Devices
Sorbents - The scope of this study included all types of
sorbent systems that would be adaptable for air pollution
control. There are three types of sorbents in use for various
purposes; namely, chemisorbents, polar adsorbents, and non-
polar adsorbents. Chemisorbents and polar adsorbents are not
generally applicable to control of gaseous pollutants under
the conditions of their release from small emission sources.
Chemisorbents would have very limited application; they are
highly selective since sorption is determined by highly
reactive functional groups 1n the pollutant molecule. Polar
adsorbents, of which silica gel, activated alumina, and mole-
cular sieves are the best known examples, are effective for
dehumidifying organic gases. Since pollutant-air mixtures
-------
xxx ix
invariably contain moisture, polar adsorbents, because of
their affinity for moisture, would not be effective for
pollution control for any practical length of time. The
nonpolar activated carbons preferentially adsorb organic
vapors, the type of vapors emitted from small emission
sources. Further study thereby narrowed almost exclusively
to sorption control devices using activated carbons.
Activated Carbon Adsorbent Systems - Activated carbon
adsorbent systems, as presently manufactured for industrial
and commercial uses, are oriented toward "air purification"
and "solvent recovery". In either system the solvent or
pollutant and air mixture is passed into the granular acti-
vated carbon bed wherein the adsorbable gas or vapor is
retained by the carbon and the purified air passes through.
When the carbon has reached its capacity to retain vapor,
the gas mixture flow is stopped or diverted to a system
containing fresh carbon.
Air Purification Systems - Air purification is carried
out in a closed system, i.e., the carbon purified air is
recirculated into the occupied space. Make-up air from
outdoors is added to the recirculating airstream to maintain
C02 and moisture concentrations at acceptable levels.
The carbon beds in air purification systems are thin;
depths of 0.5 to 3.0 in. are in frequent use. Bed areas are
sized to control airflow velocity in the 20 to 60 ft/min
range with most operated at about 40 ft/min. Coarse mesh
carbons of 4 to 6, 4 to 8 and 4 to 10 U.S. sieve number are
used. The thin bed, the relatively low airflow velocity,
and coarse mesh all contribute to low airflow resistances
which are generally below 0.25 in. of H£0 pressure drop.
The service times attained vary from 6 mo, when the odor
concentration is described as heavy, to much longer periods
of up to 2 yr, when odor concentration is described as light.
These are nonregeneratiye systems, i.e., the carbon bed cannot
be readily regenerated in place. At the end of the service
time, the spent carbon beds are removed from the cells and
the carbon is reactivated with high temperature steam at the
carbon manufacturer's plant. In an atmosphere where the
pollutant concentration is higher than 1.0 ppm, the frequency
of carbon bed replacement would greatly increase and the
operating costs would rise to prohibitive levels. When the
concentration is 10 ppm or higher a regenerative type system
becomes a definite economic necessity.
Although these systems have been intended for internal
use, they are well suited for control of emission sources
where pollutant concentrations are low but need to be con-
trolled because of highly malodorous or toxic emissions.
-------
Solvent Recovery Systems - In solvent recovery systems
the spent carbon is regenerated within the system with low
temperature (212°F) steam. The solvent is separated from
the steam by condensation and decantation or distillation.
Profitable solvent recovery is possible when the solvent is
relatively high priced and vapor concentrations are high
during the adsorption phase. Profit-loss breakeven concen-
tration for most solvents is near 700 ppm, hence, the interest
in the past has been on solvent vapor concentrations well
above 700 ppm level.
Three types of solvent recovery systems are in use as
differentiated by the manner in which the carbon bed is
maintained or handled during the adsorption and regeneration
phases of the operating cycle. These are:
Fixed bed
Moving bed
Fluidized bed
In the fixed
tained in a verti
downward through
flow velocity at
36 in. A coarse
sieve number, is
practical level.
from 6 to 18 in.
carbon decreases
temperatures are
mended.
bed system the carbon bed is usually con-
cal or horizontal tank with airflow usually
the bed. Bed areas are sized to control air-
near 100 ft/min. Bed depths vary from 12 to
mesh activated carbon, usually 4 to 6 U.S.
used to maintain airflow resistance at a
The pressure drop through the bed can vary
of H20. Because the adsorptive capacity of
with increase in temperature, high inlet air
avoided, temperatures below 130°F are recom-
Other components of the solvent recovery system may
include duct work, a particulate filter, inlet air cooler,
blower, condenser for the solvent-steam mixture, decanter,
distillation column, steam generator, and control instruments.
The cyclic operations of the recovery system are very often
automated with the various valves and other moving parts
motor operated.
The fixed bed system is the least complicated of the
systems available, has the least moving parts and is the most
trouble free. It is also the largest in size per unit air
handling capacity.
In the moving bed system, the carbon may be confined in
a retainer and the retainer moved alternately between the
part of the system where adsorption occurs and the part where
regeneration occurs. In one system that employs this concept,
-------
xli
the carbon is retained in the annular space between two per-
forated cylinders. As the cylinder or "rotary bed" is rotated,
divided sections of the bed pass through an area where the
vapor-laden air is directed radially inward through the bed
ons
vupui-iuuuu u r i 19 uircibcu i a u i a i i y iiiwaiu in i u u^u tue
to carry out the adsorption phase. Simultaneously at a
different area of the rotary bed, previously spent sections
of the bed are regenerated by low pressure steam directed
outward through the bed. On each rotation, all sections of
the rotary bed undergo an adsorption-regeneration cycle.
The advantages of the rotary bed system are: (1) the
system is compact and (2) it utilizes shallower beds than
the fixed bed system and thereby, for a given airflow capacity,
is operated at a lower pressure drop. The disadvantages are
associated with maintenance of the larger number of moving
parts and seals that are necessary to separate the adsorption
and regeneration sections of the system.
In fluidized bed systems, a high upward airflow velocity
(240 ft/min) is maintained through the carbon bed which ex-
pands the bed and produces continuous movement or agitation
of the carbon particles. In the fluidized bed adsorber, the
carbon is caused to flow in a fairly thin layer (4.0 in. deep)
across successively lower horizontal trays that are stacked
vertically. The solvent laden air flows upward through the
trays making contact with the carbon in a countercurrent
manner. The spent carbon, withdrawn from the bottom tray, is
elevated to an overhead tank in which the carbon is moved
downward countercurrent to the flow of low pressure steam to
desorb the solvent and regenerate the carbon for recycle
through the system. The countercurrent contacting of the
fluids and carbon in both phases of the adsorption-regener-
ation cycle offers a more efficient utilization of the carbon
and regenerating steam. Large volumes of air can be stripped
of vapors with a relatively small recovery system and consump-
tion of steam is greatly reduced. An important disadvantage
is the loss of carbon by attrition. This also produces carbon
dust in the exhaust stream which should be filtered out to
avoid air pollution.
The results of this study have shown that modifications
to the present-type solvent recovery systems and changes in
their operating procedures offer some of the more economical
approaches to controlling pollutant emissions, specifically
at concentrations below 700 ppm, down to the 1.0 ppm level
where the air purification system becomes more economical to
operate. To indicate the broader application for the (regen-
erative) solvent recovery type systems they are designated
as carbon resorb systems in this report.
-------
xli i
Carbon Resorb Systems - A controlling factor in the
operation of carbon resorb systems at low concentrations is
the small operating capacity and difficulty of regeneration.
At decreased vapor concentrations the available operating
capacity becomes smaller but the amount of regenerating agent
required becomes larger. If steam is used, the amount re-
quired is so large that it is usually impractical to separate
the vapor from the steam. By using air or inert gas at
elevated temperatures for regeneration the desorbed-vapor
disposal problem is alleviated. The desorbed vapor can now
be incinerated, or readsorbed onto a secondary carbon bed
and recovered by conventional steam regeneration or recovered
by condensation. In each case the auxiliary device for the
disposal operation is small and operable at low cost because
of the high vapor concentration in the regenerating gas
stream.
Incinerators or Afterburners - To place the effectiveness
and economics of carbon resorb systems for pollution control
in proper perspective, a limited evaluation of the competing
systems, - catalytic and thermal incinerators, - was necessary.
Catalytic and thermal (direct-flame) incinerators are
effectively used in many applications to control pollutant
emissions where other means would be less economical. The
use, however, becomes of questionable value when the pollutants
contain halogenated, sulfonated, or nitrated hydrocarbons since
these functional groups are converted to inorganic acids which
may be more harmful than the pollutant in its original form.
The efficiency of each system increases as the operating
temperature and gas residence time are increased. In practice
90% to 98% efficiencies have become acceptable performances
because of various factors which limit the maximum temperature
and residence time. Tor thermal incineration the generally
used furnace temperature range is 1200" to 1500°F and for
catalytic incineration it is 600° to 900°F. The residence
time for both is generally between 0.05 and 0.5 sec.
The factors that are important in determining the
merits of the incinerators relative to carbon resorb systems
for pollution control are the cost of heating the air to the
incineration temperature and the catalyst life. At concen-
trations below 100 ppm, the combustion of the pollutants
contribute very little to heat Input; the major portion of
the heating load is borne by an auxiliary heater. As the
combustible pollutant concentration Increases the supple-
mentary heating requirements decrease. At a specific con-
centration for each pollutant the combustion becomes self-
-------
x 11 i 1
sustaining. The pollutant emission streams often contain
trace amounts of inorganic acids on particulates which can
deactivate the catalyst, making necessary costly catalyst
replacement.
Economic Analyses
Operating costs were estimated for carbon resorb,
catalytic incineration and thermal incineration systems at
pollutant vapor concentrations ranging from 10 to 7,000 ppm.
The results of these analyses are presented graphically in
Figure 6-31 which shows the cost of cleaning air in $/hr per
1000 ft3/min of airflow. At 10, 500 and 4,000 ppm pollutant
concentration levels, the cleaning costs for the three types
of control systems for an influent airstream at 77°F are:
$/hr per 1000 ftVmln
System 10 ppm 500 ppm 4,000 ppm
Carbon resorb 0.65 0.85 0.90
Catalytic incineration 0.95 0.85 0.60
Thermal incineration 1.27 1.10 0.70 to 0.95
As the vapor concentration rises above 500 ppm, more
frequent regenerations are required and the operating cost
of the carbon resorb systems rises. Unless the pollutant
vapor has recovery value, the carbon resorb systems are not
as economical to operate as the incinerators at these higher
concentrations. At concentrations above 4,000 ppm air
cleaning costs with carbon resorb systems increase to the
$0.90/hr per 1000 ft3/min level while the costs with incin-
erators drop to $0.60/hr per 1000 ft3/min level and possibly
lower.
At elevated airstream temperatures and low vapor concen-
trations the incinerators become increasingly more economical
to operate and can approach the operating cost level of the
carbon resorb systems.
Research and Development Recommendation
The results of the review and evaluation of existing,
commercially available package devices for control of
emissions from small sources show that for the areas of air
purification (pollutant concentrations below about 1 ppm)
and solvent recovery (recoverable solvent concentrations
-------
xliv
above 700 ppm) existing adsorbent system technology is
generally adequate and the control devices are available.
Significant short range benefits in emission reduction
could be obtained by accelerated implementation of the
existing adsorbent devices technology, particularly to the
solvent user industries. The problem areas are in the
process industries where research and development is re-
quired to demonstrate the effectiveness of carbon resorb
systems.
The research and development plans recommend work in
four areas: (1) emission and source characterization,
(2) evaluation of new adsorbent systems, (3) generation
of fundamental adsorption data, and (4) monitoring instru-
ment development.
The objective of the emission and source character-
ization is to provide detailed chemical and engineering data
necessary for the selection and design of optimally effective
control systems. Evaluation of new adsorbent systems would
involve laboratory feasibility studies on a potentially
promising system and a final plant scale demonstration in one
of the industries experiencing control problems. Adsorption-
regeneration data useful to the design engineer of adsorbent
systems is lacking; a program to generate this data would
greatly expedite design work. To attain effective performance
from many of the new proposed systems, monitoring and control
instrumentation need to be developed.
-------
Part I
Sources and Emissions, Environmental Effects, and
Research and Development Recommendations
-------
1. Sources and Emissions
Introduction
The systematic Investigation of small pollutant sources
and their emissions required the formulation of certain pre-
liminary selection or screeninq criteria. The general quide-
lines provided at the outset of the proqram simply required
investigation of all potential sources that could be amenable
to control by packaged or off-the-shelf devices. The first
and most important selection criterion was thus one of size
or total emission volume. Analysis of the sizes of typical
sorbent or catalytic oxidation devices placed an upper limit
on total gas volume readily handled as be1ng!of the order of
10,000 scfm. In order to include air purification systems,
where large volumes of air are handled for recirculation to
working or inhabited areas, some consideration has been
given to treatment of air volumes as large as 50,000 scfm.
Above 50,000 scfm, sources are considered to be completely
outside of the scope of the study.
As the study progressed and specific pollutant emissions
were Identified and related to the sources, additional cri-
teria were developed and applied to the candidate sources.
These criteria were based on the physical and chemical char-
acteristics of the pollutants and on the operating parameter
ranges for sorbent or catalytic oxidation systems. These
criteria may be briefly summarized as follows:
Carbon Sorption Systems
(1) Molar volume (Vm) of pollutant 1n the
range from 80 to 190 cm3/mole.
(2) Pollutant concentration in the range
from about 10 ppm to near 25 percent
lower explosive limit (LEL).
(3) Exhaust stream either free of partlcu-
lates or easily filtered.
(4) Exhaust stream moisture content con-
trollable to below saturation, pre-
ferably below 80* RH.
(5) Exhaust stream temperature controllable
to 130°F or below.
-------
1-2
Catalytic Oxidation Systems
(1) Pollutant readily combustible.
(2) Pollutant concentration between
300 ppn and 25% LEL if gas temper-
ature is near ambient,
(3) Pollutant concentration of less
than 300 ppm if exhaust stream can
be heated from 300P to 500°F.
(4) Exhaust stream either free of
particulates or readily filtered.
(5) Exhaust stream free of catalytic
poisons.
Thus, applying these criteria to a wide variety of
potential emission sources resulted in the selection and
classification of small emission sources suitable for more
detailed study.
Information Sources
The major information sources utilized in the study
included the trade magazines, technical literature, reports
of related government contract studies, and data obtained
by letter and interview contact with trade associations and
pollution control agencies. To aid 1n the preliminary
literature search, computerized key work abstract printouts
were obtained from APTIC.
The trade associations and pollution control agencies
contacted and reports of related government contract studies
are listed in Appendix B.
At the outset of the program it was felt that a signif-
icant body of information pertinent to the study resided In
the files of regional, state and municipal pollution control
agencies. Many of these agencies have been involved in
pollutant source inventory studies and control activities
for years and thus should be a rich source of information.
A questionnaire was designed to elicit Information from
these agencies relevant to the Identification and character-
ization of small sources and their emissions. The question-
naire, shown in Appendix B, consisted of two questions with
a form for listing the desired Information. The first
-------
1-3
question asked for a breakdown of the number of citizen com-
plaints received per year by the aqency with a check list of
what were felt to be some of the more common sources with a
cross listing of the type and nature of the complaint (i.e.,
odor type; effect on health, materials and vegetation, etc).
The second question asked for a listing of specific
data on the sizes, rates and types of emissions and concen-
trations of contaminant species for each of the identified
small source categories.
Preliminary contact was made with a number of control
agencies to determine whether they had the type of informa-
tion desired. Only nine agencies so indicated and thus were
sent copies of the questionnaire. These nine were:
Area Population (1969-1970)
San Francisco Bay Area, California 4,100,000
New York, New York 7,800,000
Houston, Texas 1,200,000
Jacksonville, Florida 510,000
Washington, D. C. 800,000
State of Illinois, Springfield, Illinois 11,000,000
Albuquerque, New Mexico 240,000
Pittsburgh, Pennsylvania 510,000
Vancouver, Washington 40,000
26,200,000
Of these nine agencies which were sent questionnaires,
six replies were received. Of these six, three agencies
indicated that they could not supply the desired Information
for various reasons. These were San Francisco Bay Area,
Houston and the State of Illinois.
The Washington, D. C. control office stated that they
did not have sufficient information available to complete
the questionnaire, but they did provide a record of complaints
for 1970 grouped under the general headings of heating plants,
Incinerators, vehicles, open burning and miscellaneous. Lead-
ing the list of complaints, which totaled 1304, was the Incin-
erator source category with 283.
Jacksonville and Albuquerque agencies completed the
first question but were not able to supply relevant infor-
mation for the second. The results of Question 1 are summar-
ized in Table 1-1 for the two areas. To permit combining
of the numbers of the two areas, they are reported on the
per million population basis.
-------
1-4
Table 1-1 Number of Complaints per Year per Million
Population
Dry cleaning
Paint shop
Print shop
Gasoline transfer
Restaurants
Food stores
Small chem. mfq.
Incinerators
Woodwaste burners
Sewaqe plants
Pulp mills
Large chem. mfq.
Shipyards
Miscellaneous
(.
o
o
o
1_
o
73
O
u
o
XJ
ft E O
3 3
O 0> +>
%- r- C
3 O 0»
*- U >
«/>
0>
o.
o
VI
o
o
o
o
o
o
O
o
o
fc.
o
T- >,
C «
f. V
3 01
CO Q
+»
10
**
ft>
er>
c
O
O
O)
c
O
*
Vt
O
«
fc.
O
<-)
CJ
JS
o
W
01
I
-o
01
C
0)
XI
« C
oa
aa
aa
ca a n a en an
aaa
i n 11 I
I ii ii irnnni i n i
iii IT~II ^rgcni irnni i
i ii n n ii iraoii i rni 11i
aaaaaanaa
rroi
-------
1-5
No reply was received from the Pittsburgh-Alleqheny
County A1r Pollution Control Office. However, on a prior
visit to their office, data were obtained on complaints
they had investiqated. These were under headings such as
smoke, open fires, coal deliveries, dust-fly ash, dumps,
fumes-odors, and incinerators. The incinerator complaints
for the first ten months of 1970 totaled 179.
The compilation of public complaints gives some indi-
cation of the types and frequency of noxious emissions,
however, such data may be misleading. For example, a single
source of annoyance may be the cause of all of the complaints
within a municipality relating to that source category. The
manner in which the complaint data are collected and compiled
do not allow analysis of the number and distribution of
Individual sources which are the cause of complaint.
Certain source categories were identified by the
survey which had not been previously considered. Signif-
icant among these are some large sources which, however,
may have small unit operations amenable to control by pack-
aged devices, such as wood waste burners, paper mill opera-
tions and sewage disposal plants. Large chemical complexes
are also often sufficiently fragmented as to be treated as
a group of small sources.
After having contacted a number of local pollution
control agencies, the original conception of the ready
availability of relevant data from these sources was found
to be incorrect. The most general response in the initial
contacts, reinforced by the questionnaire returns, was a
general lack of the type of data required. Additionally,
those few agencies which have made any effort in this
direction are not sufficiently staffed or funded to allow
compilation of available data for the numerous requests
which they receive. The agencies in the State of California
in particular have collected extensive Information but can-
not provide data in any form other than their scheduled
reports and publications.
Most of the activities of pollution control agencies
have been directed toward definition and control of the
major emission sources, with little attention thus far to
those small sources which constitute only a small portion
of the total pollutant emission load. Some relevant Infor-
mation was obtained from published regional inventories,
however, because of the definition of certain small sources
which when lumped together constitute a so-called major
source. Examples of such small sources are the numerous
Individual solvent users (graphic arts, dry cleaning and
-------
1-6
surface coating establishments) which are generally lumped
together as major sources 1n emission Inventories. The de-
tailed treatment of this type of data 1s presented In a
later section of this chapter.
Emission Sources
Listing of Industries
Table l-II lists 22 Industries which, 1n part or 1n their
entirety, are 1ndentif1ed as small, stationary, emission
sources of vapor phase air pollutants. These Industries were
Investigated to varying degrees of depth to determine the
chemical nature of the pollutants, the amounts and concen-
trations of the emissions, and the operating conditions or
circumstances of the emissions. This 11st 1s by no means
complete, but Includes those Industries most frequently men-
tioned 1n surveys conducted 1n various air pollution control
districts. The variety of Industries represented gives a
good Indication of types of pollution problems which will be
encountered for a considerable period of time 1n the future.
Other existing and potential sources of emission are listed
on page 1-67.
The 11st of Industries 1n Table l-II 1s divided Into
two groups on the basis of pollutant control methods. Those
1n the first group have processes amenable to control with
activated carbon adsorption systems, although 1n some cases
operated 1n conjunction with absorption and/or catalytic or
thermal Incineration systems.
Those 1n the second group are not amenable or are eco-
nomically borderline 1n regard to pollutant control by the
carbon adsorption systems. Catalytic and thermal Inciner-
ation systems are more economical 1f the pollutant concen-
tration 1s high, the emitted gas temperature 1s high or the
pollutant mixtures contain low molecular weight pollutants
not controllable by adsorption. In no case 1s the emitted
pollutant of sufficient value to be recovered.
Categorizing of Industries
The first nine Industries 1n the first group are solvent
users wherein the solvent passes through the operations essen-
tlally unchanged and Is ultimately released by one or more of
-------
1-7
Table l-II
Small Stationary Emission Sources of Air
Pollutants Grouped According to Preferred^)
Control Device. Estimated Emission Rates
Industry
Emission rate,
Ib/da per 1000
people exposed
Identification
number
-Preferred Control With Sorbent Devices-
Surface coating
Degreasi ng
Dry cleaning
Graphic arts
Plastics
Rubber products
Adhesives
Paper coatings
Vegetable oils
Organic storage evap,
fuel
nonfuel
Meat rendering
Fish rendering
Canning
Restaurants
Baking
Candy making
96
20
10
3
30
<60
(2)
5.1
0.25
"s
0.04
1
2
3
4
5
6
7
8
9
10
51
52
53
54
58
59
-Preferred Control With Catalytic or Thermal Incineration-
Coffee roasting
Tobacco curing
Tanning
Meat smokehouses
Domestic incinerators
Zinc plating
0.02
140
55
57
60
61
63
65
(1) Based on economic
(2) Rate based on the
petroleum fuel in
analyses
three California
1968
survey areas for
-------
1-8
several means. Because of the solvent volatilities, the
major means of release is by vaporization while some may
be retained by the product produced or retained in sludge
or solid wastes produced by the operation. Unless some
form of control is practiced, the evaporated portion becomes
an atmospheric pollutant. Except 1n the case of industry
start up or where incineration 1s used for pollution control,
the amount of solvent sold per year to each Industry is a
measure of its pollutant emission rate. Some of the solvent
users of combustible solvents, such as the surface coating
and graphic arts, use Incineration; hence, the solvent sales
to them Is an over estimated measure of their pollutant
emission rates.
Industries listed with identification numbers 51 and
larger are chemical or thermal processing Industries. Pol-
lutant vapors are emitted from them as an undesirable by-
product. In these cases direct measurements are required to
determine the pollutant emission rates which, in many cases,
have been difficult.
The Identification numbers associated with the Indus-
tries are used for reference purposes to Identify the pollu-
tant with the industry. Since the 11st does not include all
the present (and also future) potential emission sources,
the numbering system has been designed to allow future In-
sertions into the two broad groups. Those from 1 to 50
Inclusive are the solvent users and those numbered 51 and
above are chemical, thermal, and biological process Indus-
tries.
Extent of Emission
In order to: (1) determine the extent of pollutant
emissions from small sources relative to the extent from all
sources and (2) determine the amount of pollutants emitted
by small sources for quantitative ranking, a review of pub-
lished area emission inventories was conducted. Emission
inventories were obtained of eight metropolitan areas, made
by local or federal pollution control agencies. These in-
ventories have reported, with varying degrees of precision,
the total pollutant emissions from all sources as well as
breakdowns by type and source category. The most complete
and accurate inventory available is that published by the
San Francisco Bay Area APCD. This Inventory gives a rather
detailed breakdown by major pollutant type and Individual
source category, Including a number of categories Identified
as being of pertinence to this study.
-------
1-9
Other inventories available were much less explicit in
their reported emission estimates and, in general, are based
on rapid emission estimating methods rather than actual
surveys.
Table l-III presents the estimated qaseous pollutant
emission rates reduced to pounds per day per thousand persons
(Ib/da per 1000 people) for each of the reported area surveys
Column 2 gives the rates for all sources, stationary and
mobile, and all types; i.e., oxides of sulfur and nitroqen,
carbon monoxide and the rates for organic vapors from ail
sources, namely: petroleum refineries, chemical plants, in-
cinerators, metallurgical plants, organic solvent users,
power plants, agricultural burning and motor vehicles.
Column 4 gives the emission rates of solvents and industrial
organic vapors - those vapors that are of primary concern to
control by the package sorbent systems. The extent of the
latter, relative to pollution from all sources, is given as
percentage in Column 5.
The combined population of the survey areas is about
27 million or over 13% of the total U.S. population. These
are also the areas of greater population density; hence, the
emission rates given are most characteristic of areas where
pollution problems are most acute and controls are needed
most.
Air pollution from all sources and all types is of the
order of 5,000 Ib/da per 1,000 people. About 3,500 Ib, or
70%, of it is carbon monoxide, emitted mostly by motor vehi-
cles. Organic vapors from all sources are emitted at a rate
of the order of 800 Ib/da per 1,000 people. In this case
also, the emissions from motor vehicles constitute about 550
Ib, or 70%, of the total organic emissions. Of the balance,
10% to 15% are emitted by the solvent users and the rest by
the process industries including incineration and evaporation
of organic liquids from storage or during transfer. The
volume of emissions from the process industries is quite
small except where domestic incinerators are in use, as in
the San Francisco Bay Area (1969). The emission rate of
small sources is of the order of 2% of the total emissions
or, as stated above, about 10% to 15% of all organic vapors.
Of the various pollutant inventory surveys conducted
throughout the country, the three California survey areas
(first three in Table l-III) identify the sources to a
greater extent than the others. The emission rates as
given in Table l-II are from a 1969 San Francisco Bay Area
survey, except for the organic storage evaporation. The
Bay Area data are shown in greater detail 1n Table 1-IV.
-------
Table l-III Rates of Gaseous Pollutant Emissions From Nine Survey Areas. Pollutant
Emission Rate. Ib/da per 1000 People
Survey area
South Coast Basin
San Francisco Bay Area
San Diego Bay Area
Delaware Valley
Denver, Colorado
Hamilton County, Ohio
St. Louis Study Area
Washington, D.C. Region
Jacksonville, Florida
Averages
All types,
all
sources
4,000
4,700
3,700
5,700
...
3,900
6,400
6,950
5,000
Organlcs,
all
sources
720
960
630
840
...
480
740
680
1,300
800
Industrial
process
organlcs
117
156
65
44O)
20
45
100
j(3)
2.9
3.3
1.8
...
...
1.2
1.5
2
Reference
Cal. (1968)
Cal. (1968)
Cal. (1968)
Wohlers (1965)
Dobler (1971)
Smith (1970)
McGraw (1968)
Maryland (1970)
Sheehey (1963)
1) Surface coating and dry cleaning solvents only
2) Dry cleaning solvents only
0
_. cleaning solvents
Percentage of Industrial
process organlcs relative to all types
-------
Table 1-IV
Amounts of Organic Pollutants Emitted by Small Stationary Sources Based
on San Francisco Bay Area (1969) Report
Industry
Surface coating
Spray booths
Ovens and dryers
Flowcoaters, dip
tanks & washers
Brushing, rolling,
nonindustri al
spraying
Degreasers
Dry cleaning
Halogenated solvent 1
Stoddard solvent J
Graphic arts, printing
Plastics, resin, putty mfg
Surface coatinq, rubber-
products, pharmaceutical
mfg
Other solvent users, pos-
sibly adhesives, rubber
products, paper coatings,
extraction of vegetable
oils
Total for solvent users
Number of
operating units
2,500
750
270
600
1,050
Tons/day
87.7
34.1
3.9
72.0
197.7
42.8
22.2
9.9
29.4
12.0
25.4
339.4
Lb per day
per 1,000
people
42.8
16.6
1.9
35
Lb per day
per operating
unit
70
91
29
96
21
10.8
5
14
12
165
143
42
-------
Table l-iv (continued)
Number of
Lb per day
per 1,000
Tobacco curing
Baking
Candy manufacture
Smoke houses
Tanning
Breweries & distilleries
Domestic Incinerators
Conical Incinerators
Sulflte pulp mills
Auto-refueling stations
Underground tank
Auto-tank filling
Pipe coating
Asphalt blowing
0.08
1,080,000
279
20,000 24.3
50,000 37.3
15
61.6
0.1
0.04
136
30
0.05
Lb per day
per operating
Industry
Animal rendering
F1sh rendering
Canning
Feed, fish oil & protein
Coffee roasting
Restaurants
operating units
25
78
15,000
Tons /day
0.52
0.04
3.19
peoole
0.25
v » m
» 9
0.02
1.6
unit
42
1.0
0.4
0.52
2.4
1.5
13
-------
1-13
Of all of the small emission sources, the surface coating
industry emission rate is the larqest. Fuel evaporation,
primarily that of gasoline, is the second larqest rate.
In both cases the emissions come from many small operations;
in the latter case it is the automobile filling stations.
The surface coating industry is constituted of various sized
operations, some of the major ones being the lacquer spray
booths in small local shops, and varying in size to larger
ones in the machinery manufacturing plants.
These and other significant small sources are discussed
in detail in later sections of this chapter.
Types of Pollutants
Listing of Pollutants
The number of pollutants emitted from small stationary
sources is expected to exceed 200. Table C-I, in Appendix
C, lists 167 compounds that have been identified with the
22 industries listed in Table l-II. The chemical formula,
the molar volume, Vm, boiling point and lower explosive
limit, LEL, are important properties to be considered in
developing the subject of sorbent technology. In the last
column of the table are the industry Identification numbers.
Adsorptive Characteristics
The pollutants in Table C-I are listed in decreasing
order of Vm, the molar volume at normal boiling point, cal-
culated according to the method of Le Bas (1915), Appendix
D. This order of listing gives a general ranking of the
pollutants in decreasing order of adsorbabilities. The
ranking applies more consistently to adsorbabilities on ac-
tivated carbons than to the polar adsorbents: silica and
alumina gels. Adsorption on the polar adsorbents is highly
selective, being influenced by the polarity or polarizabi11ty
of the molecule as induced by negative groups such as the
halogens, hydroxy and double bonds. Small hydroxy compounds
such as water, inorganic acids and salts are strongly adsorb-
ed, preferentially to organic compounds of much larger molar
volume. On activated carbons the compounds of larger Vm
tend to displace those of smaller Vm, with certainty of dis-
placement increasing as difference in Vm increases. The dis-
placement is not always complete; some coexistance can occur.
On polar adsorbents, the same preferential adsorption occurs
in mixtures of nonpolar organic compounds. Theoretical as-
pects of adsorption are discussed in greater detail 1n Chapter
4.
-------
1-14
Because of the nonselectlv1ty of activated carbons,
except that due to differences 1n Vm, and the low level of
Interference of water with organic vapor adsorption, activated
carbons are used almost exclusively 1n pollutant vapor control
when moisture 1s present 1n the exhaust gas stream.
On activated carbons, those pollutants with small Vm,
listed in the lower end of Table C-I, become increasingly
difficult to control with adsorption systems. Those with
Vm larger than 80 cm3/mol offer no real problem, at least,
in the adsorption phase of the operating cycle, while those
below are variable. Propane, propene, ammonia, methanol
and methanolc add require excessively large carbon beds or
systems operation with very short adsorption-desorptlon
cycle times to effect any pollutant control. Propanone,
ethanolc add, ethanol and dlchloromethane are more amenable
to control with practical sized carbon beds.
With regenerative carbon systems (also designated as
carbon resorb systems), the ease or difficulty of pollutant
desorptlon 1s also an Important factor to be considered.
Those 1n the upper end of Table C-I, with large Vm, are In-
creasingly difficult to desorb with commonly used regenerat-
ing agents and at the relatively low temperatures commonly
used. Regeneration with 212°F steam does not always effect
complete desorptlon of compounds with Vm larger than 190 cm1/
mol, while those with smaller Vm are readily desorbed unless
polymerization occurs. The accumulation of heavy or large
Vm compounds will gradually deactivate the carbon over
successive adsorption-desorptlon cycles, so that ultimately
1t will be necessary to discard the carbon or have 1t re-
activated.
The Vm range 1n which the carbon resorb type system 1s
most effective is from 80 to 190 cm3/mol.
Identification With Industries
The number of pollutants that have been Identified with
each of the 22 Industries Investigated are given 1n Table 1-
V. Not all possible pollutants from each of the sources have
been identified, but the closest approach to complete identl.
flcatlon exists 1n the surface coating, degreaslng, dry
cleaning and graphic arts Industries which, as of 1969, were
the major small stationary emission sources 1n regard to
total emission quantity. The type of emissions from the
other solvent users and also the meat rendering Industry are
well documented. For the other emission sources the Import-
ant and predominant pollutants have been reported, I.e.,
those that will have a bearing on the type of control tech-
nology required.
-------
Table 1-V Number of Pollutants Identified With Each
Industry
1-15
Number per Industry
Industry
1. Surface coating
2. Decreasing
3. Dry cleaning
4. Graphic arts
5. Plastics
6. Rubber products
7. Adheslves
8. Paper coating
9. Vegetable oils ext.
10. Organic storage
evaporation
51. Meat rendering
52. Fish rendering
53. Canning
54. Restaurants
55. Coffee roasting
57. Tobacco curing
58. Baking
59. Candy making
60. Tanning
61. Meat smokehouses
63. Domestic Incineration
65. Zinc plating
Total
64
5
3
82
17
23
38
11
3
10
43
6
5
8
1
2
7
i
1
Number in Vm
over 190 80 to 1
9 50
4
3
11 62
3 11
18
1 28
2 9
3
9
2 28
3
1
1
2
range
90 under 80
5
1
9
3
5
8
1
13
3
4
7
1
2
5
5
1
-------
1-16
The breakdown of the totals into Vm ranges presents
the most important criterion for determining the feasibility
of using a carbon system for pollution control. Most of the
emitted solvents and the pollutants from the meat-rendering
plants are in the 80 to 190 cms/mol yni ranne; hence, they
are amenable to control when adsorption and regeneration are
the controlling factors. Some of the solvents from surface-
coatinq and qraphic-arts operations have Vm larqer than 190
cm3/mol and may not desorb completely durinq reqeneration,
while some have Vm smaller than 80 cm3/mol and may not be
sufficiently adsorbed to make a carbon adsorption system
economically favorable when compared to competing systems.
Pollutants from the thermal processinq industries, such as
the coffee roasting, tobacco curing and smokehouses, tend
to be small molecules with Vm smaller than 80 crnVmol. A
fair portion of those emitted from the meat rendering In-
dustries also falls into this Vm range. Further information
on exact molecular species and the emission source operating
conditions 1s required before a final decision can be made
on type and also size of the control system.
The classes of compounds used and/or emitted by the
various industries follow a pattern. The solvent users,
except for the decreasing and dry cleaning industries, use
the hydrocarbons (aromatic, naphthenic and aliphatic), alco-
hols, ketones, ethers, glycol ethers, esters and nltropar-
afflns. Classes of compounds appearing as pollutants from
the thermal process industries are predominantly aldehydes,
organic acids, amines and sulfides. Chlorinated solvents
are predominantly used 1n the cleaning industries.
The most generally used nonhalogenated solvents are
listed 1n Table 1- VI. In the surface coating and graphic-
arts Industries the solvents are used 1n blends of two to
twelve to obtain the desired viscosity, solvency power,
drying rate and compatibility with the drying oils and
resins. Most frequently, the blends consist of two to four
solvents. The two most frequently appearing solvents 1n
the blends are toluene and xylene. All of these solvents
are recoverable with carbon solvent recovery systems.
In the degreasing industry five halogenated hydro-
carbons are used as listed In Table 1-VII. In 1967, about
9055 of the tonnage of solvent sold for this purpose 1n Los
Angeles County was trlchloroethene and most of the remaining
10*. tetrachloroethene (Walsh, 1967). Most greases dissolve
readily at 188°F 1n trlchloroethene, hence Us wide use.
Tetrachloroethene 1s used when a higher temperature 1s
required. For cleaning of electrical wire colls, motor
components or other temperature-sensitive materials, the
-------
1-17
lower bolHnq solvents are used. Since the application of
Rule 66, the use of tr1chloroethene has been restricted 1n
Los Angeles County because of Its smog forming properties
and 1,1,l-tr1chloroethane 1s now the accepted solvent.
Table 1-VI Most Generally Used Nonhalooenated Solvents
Solvent Vmp cmVmol
Heptane 163
4«Methyl-2-pentanone 141
Hexane 140
Xylene 140
Toluene 118
Cyclohexanone 118
Ethyl acetate 106
Butanone 96
Benzene 95
Propanone 74
Ethanol 61
Table 1-VII Halogenated Solvents Used 1n Degreaslng
Vapor
Solvent Vm. cmVrool temperature. °F
Trlchloroethene 98 188
Tetrachloroethene 116 250
1,1,1-THchloroethane 106 165
1,1.2-Trlchloro-
1,2,2-Trlfluoroethane 120 118
Dlchloromethane 65 104
In the dry cleaning Industry two types of solvents are
in use: the hydrocarbons and halogenated hydrocarbons.
Those most frequently used are listed In Table 1-VIII.
The trend of solvent usage is away from the Stoddard and
140°F solvents to the halogenated hydrocarbons, particularly
the trichloro-trlfluoroethane.
Evaporation of organic vapors from storage tanks and
during transfer occurs 1n many Industrial operations where
volatile reactants or solvents are used. The largest emis-
sion rates occur 1n motor fuel storage and transfer.
-------
1-18
The emission rate of 60 Ib/da per 1,000 neople, given 1n
Table l-II, is an average fiqure for motor fuels in the three
California survey areas during 1968 (California, 1969). The
list in Table 1-IX gives the mol fractions of the compounds
in a typical gasoline vapor mixture.
Table 1-VIII Solvents Used in Dry Cleaning
Solvent VITI, cm 3/mol Boiling range,
°p
Tetrachloroethene
Trlchloroethene
1,1,2-Trlchloro-
1,2,2-tr1fluoroethane
Stoddard -
140°F solvent -i
45.7% paraffin
42.2% naphtha
_12.1% aromatic
46.5% paraffin
41.9% naphtha
11.6% aromatic
116
98
120
185 ave
185 ave
250
188
118
349 to 410
358 to 396
Table l-ix Components of Gasoline Vapors
,.» Boiling
Organic compound Vm, cm'/mol Mol _%* ' point, °F
Hexane
Pentane
2-Methyl butane
1-Pentene
Butane
2-Methyl
1-Butene
Propane
propane
140
118
118
111
96
96
89
74
3.0
2.0
7.7
5.1
17.4
2.9
3.2
0.6
154
97
82
Ca 84
31
14
21
-48
(1) Balance air, 58.1 mo1%
Of the gasoline fractions the propane will not be recover-
able but it Is present at a low concentration; hence, there
will not be a significant economic loss.
-------
1-19
In meat rendering operations, the pollutant vapors
emitted are decomposition products of tallow or fats and
proteins. About 43 compounds have been identified as listed
in Table C-I, Industry No. 51, (IITRI, 1971). The aldehydes
are the most frequent and most abundant class of compounds
emitted, with organic adds, dlols, amines, sulfides making
up the balance. Some of the compounds appearing at the
highest concentrations, 10* to 50% of the total pollutant-
vapor mixtures, are as listed 1n Table 1-X.
Table 1-X Pollutants Appearing at Highest Concentration
From Meat Rendering Operations
Boiling
Pollutant vapor Vm, cmVmol point, °F
Hexanal 141 263
3-Methyl butanal 118 198
Butanoic add 108 327
2-Methyl propenal 89 155
Propanolc add 86 286
All of these vapors give bad odor responses, particularly
the butanoic add. Some of the amines and sulfides which
are more offensive are emitted at lower concentrations.
One of these is dipropyl sulflde.
Five very malodorous decomposition products have been
Identified with the fish rendering Industry; these are
listed 1n Table1-XI with their odor detection thresholds
(Conrad, 1971).
Table 1-XI Malodorous Pollutants Emitted From Fish
Rendering
Odor detection
Pollutant vapor Vm, cm3/mol threshold, ppm
Dimethyl dlsulflde 103 0.0076
Trimethyl amlne 92 0.0002
Ethanethiol 70 0.001
Propenal 67 0.210
Carbon disulfide 66 0.210
-------
1-20
Pollutant vapor concentrations 1n exhaust air are low but,
because of the very low odor detection threshold concen-
trations, the pollutant emissions create an odor problem.
Fish and meat cannlnq and also meat preparation 1n
restaurants emit some of the decomposition products of the
renderlnq operations but of a considerably less malodorous
nature.
The other processing industries - coffee roasting,
tobacco curing, tanning, meat smokehouses and zinc plating -
emit sufficient quantities of low-molecular-weiqht pollutant
vapors to make overall control with sorptlon systems Im-
practical. The reported pollutants for each Industry are
listed in Table 1-XII. Those for coffee roasting and meat
smokehouses were reported as classes of compounds, but
with each class consisting of some of the lowest molecular.
weight members.
Conditions of Pollutant Release by Industry
In the preceding text, the general pattern of types
and amounts of pollutants emitted by the various industries
were examined. In order to select the most economical
pollutant control system, it is necessary to have an under-
standing of the operating conditions under which each com-
peting system is most effective and also to have detailed
information on the operations of the emission source that
affect or determine the type of pollutants and conditions
n^K r?lease- ,Based 0" feasibility and economic studies
number of generalizations have been worked up which estab-
?6 eftect ofP°llutant release conditions on choice of
fonn!TS' T5?SC ^neral1"t1ons are discussed immeS.
duHnn f!l °?1?q' uA1so' the more 1mP°rtant pollutant pro-
ducing industries have been investigated to varying depths
!ro1^thH.ClrCUm;tanCeS °f the P'^t
are also discussed under this section.
a
a
Effect on Choice of Control System
Thermal Incinerators - Thermal Incineration would be
1. The pollutant has no recovery value.
2. The pollutant is combustible and yields no
new pollutants on combustion.
-------
1-21
Table 1-XII Pollutant Vapors Emitted From Coffee Roasting.
Tobacco Curing, Meat Smokehouses, Tanning ana
Zinc Plating Industries
Pollutant vapor
Organlcs
Phenols
Mercaptans
Organic adds
Aldehydes
Asparaglne
Ethanoic acid
Methanol
Methanal
Ammonia
cm Vmol
Coffee roasting*
-Tobacco curing-
140 for hexane
105 for phenol
55 methanethlol
42 methanolc acid
30 methanal
140
64
42
30
ZZ
Resins
Ketones
Phenols
Organic acid
Aldehydes
Methanal
Ammonia
Meat smokehouses'
Tanning*
Zinc plating-
74 for propanone
105 for phenol
42 methanolc
30 methanal
30
22
Ammonia
22
-------
1-22
3. The concentration is between 1,000 ppm and
25% of lower explosive Unit. At this con-
centration range, the gas mixture can be at
the 100°F level.
4. The concentration Is below 700 ppm but gas-
mixture temperature Is relatively high, 1n
the 500° to 700°F range,
5. The gas mixture contains vapors which would
deactivate combustion catalysts,
6. The qas mixture contains considerable amounts
of vapors of Vm larger than 190 cm'/mol, which
cannot be effectively desorbed from carbons, or
that contain considerable amounts of vapors of
Vm smaller than 80 cmj/mol which are very
poorly adsorbed by carbons.
7. The gas mixture contains completely combustible
(to C02 and HgO) particulates. Noncombustlble
partlculates would have to be scrubbed or dry-
filtered out.
8. The moisture content 1s very high.
Catalytic Incinerators - Catalytic Incineration would
be used 1n preference to the competing systems when:
1. The pollutant has no recovery value.
2. The pollutant 1s combustible and yields no new
pollutant on combustion.
3. The concentration 1s between 300 ppm and 2555 of
the lower explosive Hm1t. At this concentration
range, the gas mixture can be at the 100°F level.
4. The concentration 1s below 300 ppm but the gas-
mixture temperature 1s elevated - 1n the 300° to
500°F range.
5. The gas mixture does not contain vapors which
would deactivate combustion catalysts.
6. The gas mixture contains considerable amounts of
vapors of Vm larger than 190 cmj/mol, which cannot
be effectively desorbed from carbons, or contains
considerable amounts of vapors of Vm smaller than
80 cm'/mol, which are very poorly adsorbed by car-
bons.
-------
1-23
7. The gas mixture contains no appreciable amount of
particulates, or contains participates which can
be readily dry-filtered out.
8. The gas mixture 1s relatively dry.
Absorption Systems - Absorption systems using water
spray would be used in preference to the other competing
systems when:
1. The pollutant has no recovery value.
2, The pollutant is soluble in water.
3. The pollutant is poorly adsorbed on carbons;
i.e., Vm less than 80 cm3/mol.
4. The pollutant is biologically degradable.
5. The concentration is below 700 ppm if pollutant
is combustible.
6. The gas mixture contains particulates that are
difficult to dry-filter out.
Carbon Air Purification Systems* - Carbon air purification
systems would be used 1n preference to the other competing
systems when:
1. The pollutant has no recovery value.
2. The pollutant Vm is larger than 80 cm'/mol.
3. The concentration is of the order of 1 ppm or
less.
4. The gas mixture has no appreciable amount of
particulates or has particulates that are
readily filtered.
5. The gas mixture temperature is 130°F or lower.
6. Relative humidity of gas mixture is below
saturation, preferably below 80%.
Carbon Resorb Systems* - With the carbon resorb systems,
the limitations on their use depends to some extent on whether
the pollutant has recovery value. When the pollutant has no
recovery value, the resorb system would be used 1n preference
*See Chapter 6, pages 6-4 and -32 for discussion of these two
systems.
-------
1-24
to competing systems when:
1. The pollutant Vm range 1s 80 to 190 cm'/rnol.
2. The gas mixture has no appreciable amount of
particulates or has partlculates that are
readily filtered.
3. The qas mixture temperature 1s 130°F or lower.
4. The relative humidity of the qas mixture 1s
below saturation, preferably below 80%.
5. The pollutant concentration 1s 1n the range 10
to 700 ppm when pollutant 1s combustible and
yields no new pollutants on combustion.
6. The pollutant concentration 1s 10 ppm or higher
for noncombustlble pollutants or up to 25% of
lower explosive limit for pollutants that yield
new pollutants on combustion.
When the pollutant has recovery value, Items 1 to 4 are
the same as above. Restriction on concentrations are differ-
ent than Items 5 and 6, For recoverable pollutants, the
concentration 1s 10 ppm and higher for the noncombustlble
and up to 25% of lower explosive limit for the combustible.
Surface Coating Industry
The surface coating Industry can be divided Into two
separate entitles: those who manufacture the material and
those who use the material. The manufacturing end of the
business does not appear to be a principle concern to this
study. Most companies are medium to large size with oper-
ations using closed cycle systems so that release of material
to the air 1s extremely small. The exceptions to this gen-
eralization are the emissions from solvent storage and odors
from varnish cookers, Of principal concern are emissions
from the various users of the surface coatings.
Types of Surface Coatings - There are five main types
of surface coatings: namely, paint, enamel, varnish, lacquer
and shellac. Some of the differences are due more to modifi-
cations In formulation to meet use requirements rather than
to basic differences.
Paint Is a highly plgmented drying oil, thinned with
a low solvency power solvent, referred to as a thinner. The
-------
1-25
piqment can be a metallic oxide or a high molecular weight
organic compound and is suspended in the vehicle. The dry-
inq oil is an unsaturated polymer which on exposure to air
oxidizes and polymerizes further to form the resinous pro-
tective film. It is only partially soluble in the thinner.
Mostly natural drying oils are used but the shift is toward
the synthetic type. The formulation is directed to give a
coating that protects the substrate from the weather and
beautifies it, but tends to be low on abrasion resistance.
Painted surfaces also tend to have a dull finish.
Enamels are basically the same as paints except that
synthetic drying oils are used to a larger extent. The
formulation is directed to give a coating of higher abrasion
or wear resistance. Enamel coatings are generally glossy,
smoother, hence easier to wash, but are harder or more
brittle than paint coatings. Resistance to weathering tends
to be lower.
Varnishes are colorless, or tinted with stain or small
amounts of pigment, to maintain a high degree of transparency.
The substrate beauty is enhanced by the coating. A synthetic
drying oil is used, usually an aromatic modified tung oil,
and thinned with a low solvency thinner both with higher
solvency than those used in enamels. An almost complete
solution of the drying oil occurs. The emphasis is on wear
resistance and also weather and light resistance. The attempt
here is to combine all the good qualities of paints and enam-
els and still have a tough resilient and transparent coating.
The above three coating materials after being applied
to the surface, dry and cure by evaporation of the thinner
and by an oxidation-polymerization of the drying oil to form
the resinous film. In contrast to the above, lacquer and
shellac vehicle consists of a resin dissolve in a high sol-
vency power solvent. On application, the drying occurs by
evaporation of the solvent and deposition of the resin-
pigment film. The early lacquers consisted of a cellulose
nitrate resin while the present ones are made with acrylic
resins. Shellac resin is a natural occurring product syn-
thesized in the skin glands of certain insects of India.
Lacquer and shellac coatings have the disadvantage that the
resin film will redissolve.
Methods of Application - There are five methods of
application which are of possible Interest to this study
namely, spraying, roller, dipping, flow coating, and tumbling.
rollpr*nni?^^HSedKm!t!]?ds are nand brushing and also hand
roller application, but these are of limited Interest since
-------
1-26
they are used in out door construction or maintenance jobs
where the job site changes frequently, hence means of vapor
collection are Impractical. The other methods are used 1n
applying Industrial finishes, where continuous operation at
a stationary site makes use of emission control devices
feasible.
Each of the five types of coating materials can be
applied by each of the six methods of application when
appropriate modifications are made to the formulations,
although some coatings are more readily applied by some
methods than others. As an example, lacquer 1s best applied
by spraying.
Each method 1s best suited for certain types of articles
to be coated, as for Instance dip coating for pipes, flow
coating for automobile frames and bed springs, roller coating
for flat sheets or panels, tumbling for small rounded objects
such as buttons and spray coating for large uneven surfaces
such as automobile bodies. For each application the coating
viscosity and drying rate must be carefully controlled by
the solvent or thinner formulation. For Instance, 1n the
dip and flow coating applications the coating should become
fixed to a uniform thickness and not continue to drain toward
the lowest point on the article after being coated.
An essential part of the applications 1s the drying-
curing operation. The drying-curing operation may be with
air at ambient temperature, or 1n ovens with forced heated
air or radiant heat. A1r drying occurs at temperatures below
100°F, hot air drying at 100° to 200°F and baking at 200° to
450°F.
Surface Coating Solvents - Little or no volatlles are
expected to be released from the pigments, drying oils or
resins during applications and during drying unless recom-
mended drying temperatures are exceeded. Baking produces
some odorous decomposition products. The vapor release 1s
essentially the thlnners and solvents used. Table 1-XIII
contains a listing of some of the thlnners and solvents
which have been Identified with the surface coating Industry.
The thlnners are aliphatic hydrocarbons, turpentine, mineral*
spirits VM&P naphtha. They are mainly 1n paints, enamels
and varnishes. The solvents are the aromatlcs, alcohols,
ketones, ethers and esters. They are used to varying degree*
1n enamels and varnishes but mainly 1n lacquer and shellac.
Table 1-XIVshows this breakdown of solvents used In surface
coatings (data selected from Table 112 of Weiss, 1967). in
enamels, varnishes and shellacs, the volatile portion 1s
about 50% and 1n lacquers, about 77% by weight. In brush-on
paints, the volatile content may be lower than 50*.
-------
1-27
Table 1-XIII Estimated Air Pollutant Emission Rates. Surface
Coating Solvents
Pollutant
Emission rate,
lb per day per 1000
pop,
n-Decane
n-Nonane
Stoddard
n-Octane
Turpentine
Xylenes,
Toluene
o, p & m
P 18
17
n-Pentyl acetate
2-Ethoxyethyl acetate
Ethyl acetate
1-Butanol
2-Butanone
2-Methoxy ethanol
1-Propanol
2-Propanol
2-Propanone
Ethanol
26
Table 1-XIV Surface-Coating Formulas on an As-Purchased
Basis (Weiss 1967)
Composition of coating. %
Ester
Type Nonvolatile Hydrocarbons &
coating portion Aliphatic Aromatic Alcohol Ketone Ether
Paint
Enamel
Varnish
Lacquer
Shellac
44
58
50
23
50
56
10
45
7
30
5
30
9
50
22
Many of the coatings are cured or baked at the higher
temperatures (200° to 450°F) 1n which case the resins and
other components can release small amounts of high molecular*
weight vapors.
-------
1-28
To show the general make-up of coating formulations
with respect to solvent content, four have been selected
from data given by Parker (1965) and are presented 1n Tables
1-XV, -XVI*. -XVII and -XVIII. The first three - a primer,
an enamel and a lacquer - are Industrial finishes for appli-
ances, machinery, metal furniture, automobiles, etc. The
varnish formulation 1s for wood furniture, a manufacturing
or repair-shop operation where solvent vapor control 1s
possible.
Table 1-XV Gray Epoxy Appliance Primer Formulation
Material Nonvolatile. % Volatile. %
Rutlle, titanium dioxide 8.0
Lamp black 0.1
Blsphenol A-ep1chlorhydr1n
epoxy resin 24.7
Urea formaldehyde resin 18.7
4-Methyl-2-pentanol
Butanone
Toluene
Xylene
Totals 51.5 48.5
The above primer Is cured by baking 20 minutes at 385*F%
Table 1-XVI Acryl1c-Epoxy Appliance Enamel Formulation
Material Nonvolatile. % Volatile. %
Rutlle, titanium oxide 26.9
Acrylold AT-52 (Rohm & Haas
Company)
50% acrylic resin 19.8
12.5 cellulose acetate 4.9
37.5% xylene 14.8
Epoxy resin
50% blsphenol A type resin 13.2
50% 2-ethoxyethyl acetate 13.2
Raybo 3 ant1s1lk1ng agent 0.1
Xylene
2-Ethoxyethyl acetate
Totals 64.9
The above enamel 1s cured by baking for 30 minutes at
325°F.
-------
1-29
Table 1-XVII Vinyl Lacquer Formulation for Aluminum Siding
Material
Rut He, titanium dioxide
Geon 427, vinyl resin
Geon 433, vinyl resin
Admex, epoxy polymer
Thermolite, tin stabilizer
4-Me thy1-2-pentanone
Xylene
Solvesso 100
Totals
Nonvolatile. % Volatile. %
10.5
11.2
2.8
1.4
0.1
26.0
Solvesso 100 1s 94% aromatic with probable boiling range from
317° to 350°F.
Table 1-XVIII Base for Furniture Rubbing or Flat Varnish
Material Nonvolatile, % Volatile. %
Modified phenolic resin
Z 2 dehydrated castor oil
Liquid olticia oil
Mineral spirits
Totals
30.8
6.1
13.9
50.8
The nonvolatile* of the varnish base are cooked at 510°
and 460°F before being diluted to 50% solids with mineral
spirits. Mineral spirits generally designate the predomi-
nantly paraffinic and naphthenlc solvents of CIQ to C]2 range
with boiling points from 300° to 400°F. To produce a rubbing
varnish from the base, 1t is blended with VMP naphtha, aro-
matic naphtha, lead naphthanate, cobalt naphthanate and an
antiskinning agent, yielding a final product that 1s 57%
volatHes. VMP naphtha solvents (varnish makers and painters)
are Cs to Clo aliphatics, and the aromatic naphthas are 1n
the same high boiling ranges as the mineral spirits.
The primer and enamel may be applied to appliances by
dipping or flow-coating. To reduce the enamel to spray vis-
cosity 1t is diluted further with xylene and 2-ethoxyethyl
acetate.
Pollutant Emission from Surface Coating Industry - The
combined Information of Tables l-II, -IV and -XIV allow
-------
1-30
quantitative estimating on the various types of compounds
being emitted. In Table 1-IV, the brushing, rolling, and
nonlndustrial spraying methods appear to apply to outdoor
applications and the emissions are therefore not controllable.
This reduces the emission rate, of concern to this study,
from 96 to 61 Ib per da per 1000 population. Of the 61 lb,
43 lb are emitted from spray booths which use mostly lacquers
and some enamels. The 43 Ib/da per 1000 population 1s then
a rough estimate of the emission rate of the aromatic, alco-
hol, etc type solvents. Of these solvents, the aromatlcs
constitute about 40% of the total as based on the percentage
figures given 1n Table 1-XIV for lacquers and enamels and
also on a number of industrial finish formulations described
1n Principles of Surface Coating Technology (Parker, 1965).
On the basis of these considerations the emission rates as
given in Table 1-XIII were estimated.
Solvent Emission Control - As of 1969, the surface-
coating industry 1n the California survey areas emitted the
largest quantity of solvents Into the atmosphere. The rates
of emissions from the various surface coating operations as
reported by the 1969 San Francisco Bay Area survey are given
1n Table 1-XIX.
Table 1-XIX
Solvent Emissions from Surface Coatings
Operations (Bay Area, 1969)
Type of
operation
Spraying
Drying
Flow-coating
Dipping
Washing
Brushing
Rol Ung
Nonlndustrial
spraying
Number of
operating
units
2,500
750
270
Lb/da
per
1000 people
42.8
16.6
1.9
35
Lb/da per
operating
unit
70
91
29
Total
96.3
-------
1-31
About one half of total emission volume comes from many spray
booths, with an average rate of 70 Ib/da per operating unit.
These are various shops such as auto body repair shops and
production Hne spray booths for Industrial machinery and
home appliances. Part of the drying oven emissions are from
the lacquer coated products and part from enamel coated pro-
ducts as received from the flow coating, dipping and roller
coating operations, the 35 Ib/da emissions from'brushing and
nonindustrlal spraying are not controllable by adsorption,
leaving 61 Ib/da of the total 96 Ib/da as possibly control-
lable.
The survey of the literature and of the control equip-
ment manufacturers has not brought out evidence of any wide-
spread use of control devices in the surface coating Industry.
Carbon sorbent systems do not appear to be in use for solvent
recovery purposes. Under the prevailing operating procedures,
solvent recovery is not profitable. Where bad odors are
emitted, as from baking ovens, a limited use of "catalytic and
thermal incinerators 1s reported. The reasons for lack of
use of carbon solvent recovery systems vary with type of
surface coating operation.
Spray booths are operated with face velocities of 100 ft/
min and over as required by varied state laws. Spray booths
of sizes to fall within the scope of small emission sources
are commercially available. Booths of front opening area
from 13 to 100 ft2 and operated at 100 to 180 ft/m1n air
face velocity are described in sales literature (Paasche,
1971 and Spray. 1971). Because of over spray of the articles
being coated, particulates consisting of the pigments, drying
oils and resins are released Into the exhaust 'airflow. To
avoid air pollution by a lacquer or enamel mist, either dry
filters or water sprays are used to separate out the mist.
For effective use of a carbon resorb system, the spray
coating particulates and water mist should be completely
removed from the exhaust air. This 1s not always accomplished.
The 100 ft/min and over air velocities tend to keep the sol-
vent concentration low, below the approximate 700 ppm economic
break even point. The use of mixed solvents reduces the car-
bon adsorptive to some extent; I.e., a single organic compound
at a given concentration requires less carbon than a mixture
of several with the same combined concentration. Recovery of
a solvent mixture from the steam condensate, after regener-
ation, 1s more Involved and hence more costly than a single-
compound solvent.
-------
1-32
To determine the nature of air pollution control from a
spray booth using a carbon resorb system, estimates v/ere made
of unit size, total airflow, and cost of regenerating steam,
when total solvent emission rate 1s 70 Ib per 8 hr da and
concentrations are 10, 100, 1,000 and 4,800 ppm. The calcu-
lations were made for an acrylic lacquer thinner of compo-
sition given 1n Table 1-XX.
Table 1-XX Composition of a Common__L.a_cgjje_r_ T_h1_n_n_e_r
Cone of each at
4,800 ppm total
Organic compound Weight, % ppm vol,%
2-Ethoxyethyl acetate 17 480 10.0
Toluene 43 1,740 36.3
Propanone 40 2,570 53.7
The 4,800 ppm 1s 25% LEL for the mixture calculated with an
equation based on Le Chateller's modification of the mixture
law (Le Chatelier, 1891). The equation 1s given 1n Appendix
D.
Because of pressure drop and other considerations, the
linear velocity through carbon resorb system beds 1s varied
from about 20 to 110 ft/m1n. The minimum face velocity for
spray booths is 100 ft/mln; hence the area of the carbon bed
must be sized equal to, or larger than, the spray booth front
opening for a given total airflow. The results of the calcu*
lations are given 1n Table 1-XXI when the airflow is kept at
the 110 ft/nin maximum which then gives the minimum carbon
bed area. The 110 ft/m1n velocity for the spray booth gives
the maximum front opening area. E1oht one-hour cycles are
assumed to recover the 70 Ib/da solvent emitted.
Table 1-XXI Carbon-Resorb System Size, Operating Condi-
4,800
1,000
100
10
(1) See
tlons. Regenerating Steam Cost
for Control
of Spray-Booth Solvent Emission
F,
ft3/m1n
150
700
7,000
70,000
glossary
AP Cost of 212°
A, ft2 W, Ib 1n.H20 $/l
1.3 97 25.6
6.4 194 10.8
63.6 800 4.5
636 3,000- 3.1
5,700
f for definitions of terms
Ib solvent
0.03
0.08
0.24
1.20
F steam
$/da
2
6
17
84
-------
1-33
The results of Table 1-XXI show that at 4,800 ppm the
steam cost 1s low enough (3<£/lb of recovered solvent) so that
the overall recovery operation is profitable, since the
approximate price of the solvent mixture is 10
-------
1-34
Degreasing Industry
Description of Industries - Degreasing is a necessary
step In the preparation of metal fabricated articles for
surface coating, electroplating or other finishing operations
The cleaning operation is done in a packaged unit, termed the*
degreaser, which utilizes an organic solvent as cleaning
medium, Table 1-VII. Depending on the complexity of the
unit, the soiled article may be contacted by immersion in
the hot solvent, by a warm rinse, by liquid spray and conden-
sate. A high degree of cleanliness of the articles is attain-
ed by suspending the (cool) article in the solvent vapor. By
condensation of the vapor the grease, oil or other soil is
dissolved and washed down into the liquid phase (Kearney.
1960).
The basic vapor degreaser consists of a vapor generating
sump containing the solvent and heater, a vapor zone above
the sump and freeboard. A narrow water-cooled jacket around
the upper part of the degreaser sets the maximum height of the
vapor zone. Soiled articles are lowered into the vapor zone
through the open top and freeboard and withdrawn by the same
route when cleaned. Vapor condensate cleaning stops when the
article temperature rises to the vapor temperature. The
spray step aids in the cleaning of irregularly shaped articles
or articles otherwise difficult to clean and is done while the
article is submerged in the vapor zone. The essential feature*
of the degreaser are Illustrated 1n Figure 1-1. *
Size of Decreasing Industry - San Francisco Bay Area
(1969) reported, (Table 1-IV), 600 degreasers In operation
with average emission rate of 143 Ib of solvent per day per
operating unit. The amount emitted per day averaged 21 Ib
per 1000 people. The latter average would apply more to
Industrialized areas and not give a good Indication of nat-
ional average.
Table 8 of ASTM STP 310 Report lists typical appli-
cations of vapor degreasing. The production rates give an
indication of size of degreasing units used 1n Industry.
For degreasing by vapor-spray-vapor system, the smallest
rate reported is 600 Ib/hr of steel spark plugs to remove
machining oil, and the largest is 40,000 Ib/hr of steel
automatic transmission parts to remove machining oil, chips
and shop dirt. For degreasing by the warm Hquld-vapor
system, the smallest rate reported is 500 Ib/hr of magnesium
aircraft castings to remove polyester resins, and the largest
is 12,500 Ib/hr of aluminum tubing to remove drawing lubri-
cants. For degreaslng by the boiling liquid, warm liquid and
vapor system, the smallest is 50 Ib/hr of gold and tin
-------
1-35
r
Frtt boird
Vapor lone
'l| I i-t-l I'll
Basket containing
article*
cleaned
liquid solvent
/
Heater
Vent duct
to carbon
diorbir
Water cooling
jacktt crouna
degrcaser
- Su*ip
Figure 1-1 Degreaser Using Halogenated Hydrocarbon Vapors
C.W
WASHER
EXTRACTOR
AND
TUMBLER
'AMBIENT
MR
(CloHiM
drying)
AMBIENT AIR
yhig carbon bed*)
STEAM
Figure 1-2 Dry Cleaning Machine With Integrated Carbon
Solvent Recovery System. Courtesy of V1c
Manufacturing Company
-------
1-36
plated transistors to remove silicone and light oil, and
the largest is 5,000 Ib/hr of steel stampings to remove chips
and light oil, Most of the materials handling is by conveyor
and some by hoists. In the small operations, such as the
transistor cleaning, the articles are lowered into the de-
greaser manually in wire mesh baskets.
Air Pollution from Degreasers - Solvents escape from
degreasers uncer several circumstances. Degreasers must of
necessity be operated with the top open completely, or
partially oper, or opened at intervals. Most of the vapors
escaped ty this route. Water-cooled condensers or jackets
operated at 68°F can hold the vapor concentration at the
vapor-zone-freeboard boundry to approximately the following
concentrations for three of the most commonly used solvents.
Concentration
Solvent Volume, % ppm
Tetrachloroethene 1.9 19,000
Trichloroethene 7.9 79,000
1,1,1 Trichloroethane 13 130,000
In a very still freeboard atmosphere, a concentration grad-
ient can form with very slow diffusion of vapors out of the
c'egreaser. Vapo movement through the freeboard is greatly
accelerated by air currents passing over an open or partial 1**
open degreaser, by opening and closing of the lid if one 1s
used, and by the movement of the articles in and out of the
degreaser, Movements necessary during spray cleaning create
turbulences whicn accelerate vapor escape. Degreaser man-
ufacturers estimate 0.05 Ib/hr per ft2 of open tank area as
the vapor escape rate. Another potential means of vapor es.
cape is by way of liquid solvent adhering to the articles
being transferred out. This happens when the articles have
not reached the vapor temperature. Also, pockets and
crevices in the articles can carry out solvent. By careful
operating procedures vapor losses can be minimized.
For a degreaser cleaning 40,000 Ib/hr of transmission
parts, the solvent distillation rate 1s 600 gal/hr and
solvent make-up rate Is 2.4 gal/hr (Kearney/1960). Assumln
trichloroethene, the total make-uo or potential pollutant '
emission rate 1s 233 Ib per 8 hr day. The mean calculated
emission rate from San Francisco data is 143 Ib per de
greaser per day. Possible reasons for the difference can
be that the average degreaser of San Francisco Bay Area
would be smaller than the 40,000 Ib/hr unit and some of th.
San Francisco degreasers have solvent recovery systems
-------
1-37
If 1t is assumed that a trichloroethene vapor is
drawn off the (larqest) 40,000 Ib/hr degreaser at a con-
centration of 1,000 ppm, the airflow would be 1,450 ft3/
min. The calculation is:
1,000 ppm x IP'6 x 131 Ib mol wt _ 2.4 gal/hr x 12.7 Ib/gal
391 ft3 mol vol " 60 min/hr
F « 1,450 ft'/min.
The solvent can be profitably recovered under these conditions
by several of the package solvent recovery systems on the
market. Much of the solvent recovery system advertising is
directed toward recovery of trichloroethene.
Emission Control - To control air pollution by way of a
carbon solvent recovery system, slotted ducts are attached
to the top rim of the degreaser as shown in Figure 1-1. The
airflow through the slots can be optimized tot (1) minimize
or avoid creating turbulence in the freeboard, (2) prevent
or minimize escape of solvents past the slotted ducts, and
(3) maintain solvent concentration in airstreams above 700
ppm, the approximate economic breakeven point.
This has been accomplished in a considerable number of
installations. A case in point is a recovery operation re-
ported by Berg (1968) in which 7,300 Ib/wk (183 Ib/hr) of
trichloroethene were recovered with a carbon solvent-recovery
system at 3,000 ftVrnin airflow. The calculated concentration
was 3,000 ppm. The recovery cost was 0.34c/lb of solvent. It
included electricity for controls and exhausters, steam, cool-
ing water, and labor to clean filter bags ahead of the carbon
beds each day. A comparison between operating cost and sol-
vent selling price (11.54/lb) indicates a profitable opera-
tion.
The 2.4 gal/hr (29 Ib/hr) solvent make-un rate reported
above for one of the larger degreasers can be readily con-
trolled by solvent recovery systems of less than 3,000 ft3/
min air-handling capacity. The use of carbon resorb systems
in the degreasing industry represents one of the more straight-
forward and trouble-free applications. For all practical pur-
poses, the logical solution to pollution control in the in-
dustry is the installation of more recovery systems.
Dry Cleaning Industry
Description of Operation - The procedure consists of
charging a weighed amount of clothing into the dry cleaning
-------
1-38
unit, washing by agitation in a solvent bath and rinsing
with clean solvent. On completion of the washing step, the
solvent is drained off and the liquid solvent in the cloth-
Ing is removed by spinning in a centrifuge, termed the ex-
tractor. In the third and final step, the clothing is dried
by means of heating air circulated through a tumbler. The
solvent from the washer is reclaimed for reuse by filtration
and distillation. Table 1-VIII lists the most used solvents.
Size of Dry Cleaning Industry - The dry cleaning indus-
try of the United States is comprised of some 35,000 individ-
ual operations ranginq from the small - grossing less than
$40,000 per year - to large complex operations grossing over
$300,000 per year. At present approximately 7S% of the
plants utilize tetrachloroethene. These tend to be the
smaller operations and account for only 55% of the volume of
clothes cleaned (National Drycleaners Institute interview).
In Los Angeles County (1956), because of fire laws, the newer
smaller commercial and coin operated dry cleaning establish-
ments, which are generally near residential and shopping
areas, use the chlorinated solvents. The larger dry cleaning
establishments in industrial and commercial areas use the
petroleum solvents (Lunche, 1957). About 60% (1957) use
chlorinated hydrocarbons.
The Dry Cleaners' Association estimates that an average
per day load of clothing for small operations, which are the
majority of installations, would be approximately 400 Ib.
They further feel that there are few operations doing in
excess of 800 Ib per day. Based on tetrachloroethene vapor-
recovery figures for Los Angeles County, the estimated daily
clothing load for the average size tetrachloroethene plant
is 570 Ib.
Based on the 35,000 dry cleaners figure, the number of
dry cleaners per 1000 people in the United States is 0.17.
For the San Francisco Bay Area the estimate for 1969 1s 0.26.
Air Pollution From Dry Cleaning - The San Francisco Bay
Area survey (1969) on 1,050 dry cleaning units gave estimates
on the amount of emitted chlorinated solvents at 4.7 Ib/da
per 1,000 people. The combined amount emitted per operating
unit was estimated at 42 Ib/da.
Solvent can escape into the atmosphere under several
circumstances. In the older dry cleaning plants, the washer-
extractor and tumbler (or dryer) are two separate operating
components. When clothes are transferred from one to the
other, solvent vapor is released into the atmosphere. Vapor
released during the tumbler step is passed through a water-
cooled condenser which removes part of the vapors 1n the air-
stream.
-------
1-39
A survey of 60 (of 600) tetrachloroethene-type dry
cleaners in Los Angeles County, 1962, showed that per 1,000
Ib of clothinq cleaning, 10 qal of tetrachloroethene are
required when no carbon adsorbent recovery unit is employed.
When an adsorbent unit is employed, the solvent loss is 3.5
qal or a recovery of 6.5 qal (88 Ib). A 1971 estimate, by
the National Dry Cleaners Institute, for tetrachloroethene
recovery for coin operated machines 1s much smaller. For a
2,000-load cycle of approximately 17,500 Ib of clothing, the
recovered quantity was 25 gal or approximately 1.5 gal per
1 ,000 Ib of clothing.
Emission Control - When a carbon solvent recovery system
is used, it is installed at the discharge of the ventilating
system to collect the vapor laden air from the tumbler and
vents placed near the doors of the washer-extractor, the
tumbler, and the floor near the tumbler. The floor vent
collects solvent released from the clothing when removed from
the tumbler.
In the construction of new dry cleaning machinery the
trend is toward a completely contained machine which includes
an activated carbon solvent recovery system. A flow diagram
of this type of machine is shown in Figure 1-2. In a 14-min
cycle time, the coin operated machine of this make cleans 8
Ib of clothing; and a commercial unit, 25 Ib. One gallon of
1 ,1 ,2-trichloro-l ,2,2-tri f luoroethane is used per pound of
clothinq in the wash phase of the overall cycle. Very little
solvent is lost to the atmosphere.
The effective use of carbon resorb type solvent recovery
systems has been demonstrated in the dry cleaning plants
where halogenated solvents are used. Because of the high
cost of tetrachloroethene, the value of its recovery makes
possible the amortization of the adsorption unit within 1 to
2 yr; hence a financial incentive exists for the prevention
rL r P°llution with the chlorinated solvents. Approximately
50% of these plants have activated carbon recovery units
Plants employing the petroleum type solvents, however, make
ho^n!!mof JJ V?P°r recovery. at least in the United States,
because of the lower cost of these solvents.
Graphic Arts Industry
Size of Industry - This multifaceted industry is
pertinent as an emission source because of solvents or nil«
by the -uch
-------
1-40
The printing activity is concentrated in urban areas,
although distributed throughout the country. About one-half
of all commercial printing is done in four states: New York,
Illinois, Pennsylvania and California (Gadomski, 1970).
Printing Processes - The individual printing processes
which comprise the graphic arts industry include letterpress,
lithographic, gravure and screen process.
In the letterpress process, the printing area of the
printing plate or roller is raised above the nonprinting
area. Ink applied to the raised area is subseguently trans-
ferred to the paper or other substrate to be printed. Books,
newspapers and magazines are printed by this process (Bruno,
1968).
In lithography, the image and nonimage areas are on the
same plane. The image area is grease receptive and water
repellent, while the nonimage area is the reverse. The ink
applied to the image area is transferred to the substrate to
be printed. General commercial literature, books, catalogs,
greeting cards, letterhead business forms, checks, art repro-
ductions and labels are printed by this process.
In the gravure process, the printing area is recessed;
it 1s comprised of wells etched to different depths. The
ink is transferred to the roller surface and excess removed
with a blade. Longrun magazines, newspaper supplements,
preprints for newspapers and plastic laminates are printed
by this process.
In the screen process, a stencil is applied to a silk
or stainless-steel screen to which a thickened paste ink 1s
added, The ink is transferred to the printing surface by
rolling with a squeegee. This process finds application in
printing displays, posters and signs.
When the image is transferred directly from the image
carrier to the paper, it is known as direct printing. When
the image is transferred by an intermediate roller or plate
it is known as offset printing. All screen process and most
letterpress and gravure processes are direct printing. Most
lithographic printing is offset.
When the plates or rollers used in the letterpress pro-
cess are of rubber, the process is known as flexography.
This process is used widely in multicolor printing on a wide
variety of substrates.
-------
1-41
Printing Inks - The three important properties of inks
are drying, printablHty and color. Of greatest concern to
air pollution is the dryinq properties of the ink which can
occur by one or more of seven different physical or chemical
mechanisms; i.e.. absorption, solvent evaporation, resin pre-
cipitation, oxidation, polymerization, cold setting and gela-
tion. The choice of ink is determined by the printing pro-
cess and the substrate to be printed, and the ink composition,
in turn, determines the air pollution potential of the print-
ing process.
Inks used in letterpress and lithographic processes are
referred to as oil inks or paste inks. Most of these inks
dry by means other than solvent evaporation, and those few
that depend to a minor extent on solvent evaporation use sol-
vents in 250° to 350°F boiling range. Liquid body is imparted
to the ink to some extent by liquid reactants such as linseed
oil. The solvents used are mineral oil, high boiling hydro-
carbons 1n the 400°to 530°F boiling range and triethylene
glycols.
Letterpress and lithographic newsprint inks contain
aliphatic hydrocarbon solvents of 425° to 530°F boiling
range. Initial or immediate drying after ink application
occurs by absorption into the paper, with drying completed
In heated ovens. Inks used on folding cartons and Kraft-
liner containers dry by oxidation and'some inks, used 1n
the latter, dry by precipitation. Metal-container inks dry
by curing for 10 min at 300° to 400°F. Polymerization,
oxidation, and crossllnking occur.
Inks used in flexographlc and gravure processes are
referred to as solvent inks and differ from those used in
letterpress and lithography in that they are of very low
viscosity and almost always dry by evaporation of highly
volatile solvents. Those identified with the graphic arts
industry in Table C-I are primarily those used'by the flex-
ography and gravure processes. However, because of the use
of rubber plates and rollers, certain ones of these solvents
cannot be used in the flexographlc process. Toluene and
xylene cannot be used at all; ketones can be used with butyl
rubber, while hydrocarbons can be used with buna rubber.
Alcohols, glycols and low concentrations (25%) of esters are
acceptable. The boiling range of the solvents extends from
147° for methanol to 343°F for 2-butoxy ethanol.
Air Pollution From Graphic Arts - Without pollution
control, volatile solvents are emitted into the atmosphere
from the flexographlc and gravure printing operations during
the ink application and also during subsequent drying. As
-------
1-42
listed in Table C-I, 83 organic solvents have been Identified
with these two printing processes. The emission rate, essen-
tially of these solvents, 1s estimated at 5 Ib/da per 1000
people based on the San Francisco survey. Pollution from
the letterpress and lithographic printing operations will
differ considerably. Very little vapor emission will occur
during the Ink applications but, where high temperature oven
drying is carried out, high boiling solvents will be emitted
accompanied by some decomposition products of the drying oils
and resins. The high boiling solvents emitted have Vm values
considerably 1n excess of 190 cm3/nol and would make carbon
resorb or regenerative systems impractical for solvent re-
covery. The decomposition products add to the regenerative
problem.
Emission Control - The extent of emission control 1n
the various printing plant operations has been investigated
by Gadomskl (1970) through visits to 57 plants distributed
in 10 states, namely: California, Illinois, Wisconsin,
Georgia, Tennessee, Florida, New York, New Jersey, Pennsyl-
vania and Ohio. Of the 57 plants, 40 plants use no solvent
emission control devices. Of the remaining 17 plants 5
different types of devices or methods are used to control
emissions, vOne plant, Involved in metal decorating opera-
tions, uses a deodorizer unit wherein a deodorizing vapor
is fed into the exhaust alrstream. Another plant, also in
metal decorating operations, uses a spray chamber. Seven
plants Involved in metal decorating and lithographic opera-
tions use direct flame afterburners, with and without heat
recovery. Six plants, also in metal decorating and litho-
graphic operations, use catalytic combustion incinerators,
with and without heat recovery. Of the 57 plants, 8 plants
are Involved with gravure operations. Two of them use
activated carbon solvent recovery systems, while the other
six use no control devices. The two using solvent recovery
systems may be classified as large plants, although not all
of the nonusers can be classified as small. The airflow
per press unit is 1n the range 3,000 to 11,000 ft3/m1n, and
air temperatures are about 100°F, a favorable temperature
for adsorption. The airflows from the lithographic and
metal decorating operations are over 300°F and generally 1n
the 400° to 600°F range, temperatures favorable for catalytic
and thermal incineration pollution control.
Duhl (1970) has analyzed the factors affecting economic
recovery of oravure solvents with carbon solvent recovery
systems. For an example calculation, he used an 80 press
installation with total exhaust airstream of 120,000 ft3/m1n
at 100°F with approximate solvent load of 4,400 Ib/hr. The
solvent mixture being utilized was principally the acetate
esters Including, at times, the ethyl, Isopropyl, butyl and
-------
1-43
amyl and, at times, some quantities of ethanol and propanone
along with aliphatic hydrocarbons, toluene and xylene. With
these solvents the concentration was of the order of 3,000
ppm. The system consisted of six Vulcan-Cincinnati Adsorbers
on-stream preceded by a glass fiber filter to remove paper
and dust particles, and a fin tube cooling unit to control
air temperature to approximately 95°F. Economic analysis
showed a recovery of $1,600,000/yr of solvent and payout
time of 1.5 yr for the installation.
One of the large cost items in solvent recovery in
gravure and surface coatings industries, where water soluble
mixed solvents are used is the separation of the solvents
from the steam condensate and from each other. For large
installations where continuous and larger, more efficient,
separation systems can be used the cost decreases consider-
ably. Large Installations can show a profit on solvent re-
covery. This may not be the case with snail installations.
Other Solvent User Industries
The combined solvent emission from the remaining solvent
user Industries is of the order of 32 Ib/da per 1,000 people
based on the San Francisco Bay Area (1969) survey report.
Table 1-XXII gives a partial breakdown of the industries and
estimated emission rates for three groups of industries.
Table 1-XXII Amount of Solvent Emitted by Plastics. Rubber.
Paper Coating and Pharmaceutical Industries
Industry Lb/da per 1,000 people
Plastics, resin, putty mfq. 14
Surface coating, rubber products,
pharmaceutical mfg. 6
Other solvent users, possibly
adhesives, paper coatings,
extraction of vegetable oils
plastic products Jl_2_
Total 32
The solvents used in these industries have been identi-
fied, as listed in Table C-I, and are the same as used in
surface coatings, and flexographlc and gravure printing pro-
cesses. The problems of pollutant control are also quite
similar.
-------
1-44
A number of carbon solvent recovery systems are 1n
successful operation in fiber or synthetic filament pro-
duction (plastics), rubber coatings of gloves, pharmaceuti-
cals, adhesives and paper coatings (Vulcan-Cincinnati, Inc).
Rubber Products Industry
General - Certain raw and synthetic rubber products
processing steps emit uncontrolled organic solvents and
participates into the atmosphere. In addition, pollutants
are emitted in the production of certain types of synthetic
rubber such as butadiene-styrene (SBR). While most of the
rubber products industry consists of large operations such
as tire manufacture, small specialty Items are also produced.
Most rubber products are processed in the same manner except
for changes in compounding recipes and vulcanizing operations,
Product Processing Steps - With a few minor exceptions
the manufacture of rubber products involves: compounding,
mixing, forming and vulcanization. Compounding is the pro-
cess of selecting and weighing the various ingredients re-
quired by the formulation and Involves the selection of
rubber, rubber chemicals, reinforcing pigments and processing
aids. Mixing is the blending of the compounding mixture to
attain dispersion of pigments and production of consecutive
uniform batches. In forming process, rubber is extruded
into the desired shape or calendered (applying sheeted rubber
to a fabric). Rubber cementing is also a forming process in
which rubber stock solvents are mixed to form an adhesive.
Rubber building 1s the combining of stocks of different
composition. Vulcanization (curing) 1s the last major pro-
cessing step. The curing process Involves application of
heat to convert the green dough Into an elastic state.
-------
1-45
Emission Sources from Rubber Products Processing - Most
pollutants are emitted from rubber mills used in the mixing
process and in applications of rubber cements in the forming
step. Particulates (dusts and fumes, oil mists) and odors
are emitted. Mixing emissions vary depending on the size of
the mill, size of batch and composition of the mix. Solvent
vapors are uncontrolled. Large quantities of uncontrolled
organic solvent vapors are also given off in the form of
rubber cements (D'Imperio, 1967).
Rubber Cements - Rubber is more or less soluble in most
aliphatic and aromatic solvents. The cements are made by
mixing stock rubber and solvent together in churns to form a
solution which will flow at 10% concentration (Rogers, 1968).
Cements find application in production of products such as
hospital sheeting, balloon and life raft fabrics, nipples,
gloves and in part of the tire building process.
Emission Types and Properties of Rubber Solvents - The
physical properties of organic solvent vapors emitted from
products processing are given in Tables 1-XXIII and -XXIV.
The processing solvent used varies according to the base
polymer. Solvents such as benzene, toluene and xylene are
used with natural and SBR rubber. Various ketones, etc.,
used with nitrile and neoprene synthetics. The proportion
of solvent used is determined by the solvent power of the
stock, consistency desired and character of the stock.
Synthetic Rubber Processing - The process for producing
most synthetic rubber consists of mixing monomers of buta-
dienestyrene (SBR). Soaps and mercaptans are added and the
mixture polymerized. Oil and carbon black are then added
and the mixture coagulated and precipitated from a latex
emulsion. Rubber particles are dried and baled (MacGraw,
1970).
-------
I
*»
en
Table 1-XXIII Properties of Solvents Emitted from Natural and SBR Rubber
Solvent
Benzene
Naphtha(petroleum
Trichloroethene
Tetrachloroethene
Pentachloroethane
Carbon tetra-
chloride
Toluene
Xylene
Kerosene
Diethyl ether
Gasoline
Chemical
formul a
C6H6
ClHCrCClz
Cl2C:CCCl2
CC14
C2H5OC2H5
caHs to ceH-|4
Density,
Ib/qal
7.36
5.01
12.2
13.5
13.9
13.3
7.24
7.30
5.84
6.68
Mol wt
78
131
166
202
153
92
106
74
Boi 1 inq
ranqe, °F
176
86-140
188
250
324
171
231
291
300-550
94
100-400
LEL,
ppm
14,000
10,000
i~
14,000
10,000
7,000
18,500
14,000
-------
Table 1-XXIV Properties of Solvent Emitted from the Synthetic Rubber Industry
Solvent
2-Butanone
4-Methyl-2-
pentanone
1 ,2-Dichloro-
ethane
Chemical
formula
CUH2CH2C1
Density,
Ib/gal
6.71
Boiling LEL,
Mol wt range, °F pom
72
10.4
98
172-178 20,000
CH3COCH2CH(CH3)2 6.68 100 237-243 14,000
182
62,000
-------
1-48
Emission Sources from Synthetic Rubber - Organic com-
pounds are emitted from reactor and blow-down tanks; odors
are emitted from the drying process.
Emission Types and Properties from Synthetic Rubber -
Emission factors are presented on Table 1-XXV as given by
MacGraw (1970). In the SBR process, gases are recycled, but
some odors are emitted.
Pollutant Emission Control - Rubber mills have exhaust
hoods to remove dusts, fumes and mists from the rolls. The
most common control device is a bag house to remove partic-
ulates. Scrubbers are sometimes used to control oil mists.
There does not appear to be odor control devices. In the
SBR process, gases are recycled back through the process.
It is not known if any kind of air pollution equipment
is used in tire retreading shops since pollutant data and
emission rates are difficult to obtain in this area. It Is
likely that the same organic solvents are used in retreading
as are used 1n other parts of the rubber industry.
Solvent Extraction of Vegetables
Solvent extraction 1s an efficient way to recover oil
from seeds, such as soybean and cotton, and from lemons.
Hexane or heptane is used for the seed extraction where the
process may be continuous in large plants or batch-wise in
the smaller ones (Cowan, 1969). A closed system 1s employed,
keeping vapor emissions very small. A carbon resorb would
be amenable to the recovery of any escaping solvent vapors.
2-Propanol is used in the extraction of lemon pulp in
the plant of Exchange Lemon Products, Corona, California
(Barnebey, 1965). 2-Propanol vapors escaped from the plant
operation in exhaust air at 2,000 ftvmin, 8300 ppm and
120°F. The solvent 1s being recovered for reuse with an
activated carbon resorb system. Because of particulate
matter and small amount of HC1, a liguid scrubber 1s used
to clean the air-solvent mixture before entry into the carbon
bed.
Solvent and Fuel Evaporation From Storane
Another potential emission source 1s the organic vapor
loss from above-ground fixed-roof storage tanks, which are
subject to day-night temperature fluctuations. Almost every
-------
1-49
Table 1-XXV Emission Factors from Synthetic Rubber Plants
Pounds per Ton of Product, (MacGraw, 1970)
Compound Emissions* '
Alkenes
Butadiene 40
Methyl propene 15
Butyne 3
Pentadiene 1
Alkanes
Dimethyl heptane 1
Pentane 2
Ethanenitrile 1
Carbonyls
Propenoic nitrile 17
Propenal 3
(1) Butadiene emission is not continuous and is greatest
after a batch of partially polymerized latex enters
the blowdown tank.
-------
1-50
chemical manufacturing operation has storage tanks for
solvents or reactants, while the petroleum Industry nay be
the largest user of storage facilities. For gasoline storage,
29,000 tanks are reported 1n use 1n the country, v/hich range
in size from 42,000 to 21,000,000 gallon capacity. Gasoline
vapor loss from this source 1n the United States is estimated
at 7.5 Ib/da per 1,000 people. Gasoline evaporative losses
of all types approach 25 Ib/da per 1,000 people, which in-
clude losses from floating roof tanks and during transfer.
In the San Francisco Bay Area (1969), the estimated indus-
trial solvent evaporation rate was 5.1 Ib/da per 1,000
people.
Some calculations were made which indicate that carbon
adsorbent devices are feasible for this application and that
further study is warranted. For a 3,360,000 gal tank, the
estimated evaporation is 71,400 gal/yr, API Bulletin 2518.
The concentration of gasoline vapors in the vent gas during
warm-up is reported to vary from 30% to 5058 by volume. If
the assumptions given below are made, the intake flow during
cooling is about 20 ft'/min and out flow about 40 ftVmin.
Mean ullage 50% of capacity
Cool-down and
warm-up time 8 to 10 hr
Temperature fluctuation
span 25°F
Because of the high vapor concentration, cooling of the car-
bon bed will be necessary. This can be done by pumping a
coolant liouid through colls in the carbon bed. During the
night, when air is being drawn in, the bed could be desorbed
by applying heat by means of the same liquid and colls. Per
adsorption phase of the cvcle the gasoline weight pick-up
will be about 1,200 Ib, requiring from 3,500 to 5,500 Ib of
carbon. The amount of gasoline vented and hence the required
carbon bed size will vary with the ullage and temperature
change span. The main cost items will be the adsorber and
carbon, refrigeration and heating. The amount of gasoline
recovered will be 71,400 gal/yr which at 13^/gal will place
the recovered gasoline value at $9,000/yr. The value of
the recovered gasoline reduces the overall cost of the
pollutlon control .
Gasoline is low molecular weight, containing considerable
amounts of butane and propane, hence the high or near satura-
tion vapor pressures and the need for refrigeration In adsorp^
-------
1-51
tion; see Table 1-IX for compositions. Industrial solvent
and chemical reactions that are of higher molecular weight
will be more amenable to carbon adsorption recovery systems.
Gasoline, other fuel, and solvent vapor losses can
occur during transfer of the liquids between storage tanks
and motor vehicle tanks due to displacement of vapors from
the tank being filled. One method to prevent this type
vapor loss is to Install a vapor line to carry the vapors
from the tank being filled to the tank being emptied. When
this method Is not feasible, the vapors can be recovered by
a carbon resorb type system. Incineration of the escaping
vapors has also been proposed.
Meat Rendering Industry
Description of Industry - Animal matter (offal) not
suitable for food for either humans or pets is converted to
salable products by rendering. Rendering plants are the
major outlets for disposal of waste from slaughter houses,
butcher shops, poultry dressers and other processors. They
also dispose of whole animals that have died naturally or
accidentally. In this respect, the rendering also operates
as a scavenger or solid waste disposal Industry.
The process is thermal and yields as main products a
protelnous meal, suitable as animal feed, and tallow. Bones
are also ground into the process Input feed; hence the pro-
telnous meal 1s enriched with calcium and phosphate.
Based on statistics given by Easton (1969) the meat
and poultry industry has been growing at a rate of 5* per
year since 1963 in dollar volume of business. Since the
meat rendering operations are scavengers for the overall
meat Industry, they of necessity must also expand.
Most rendering plants are old, but some modern plants
have been constructed 1n recent years. The older plants
operate batch processes while the modern ones have converted
to continuous operations such as the Anderson Carver Green-
field (Barr, 1966) or the Dupps Duke systems.
The estimated number of meat rendering plants is
between 800 and 900. Average figures for the older plants
Indicate about 4 cookers per plant, 6 batches of offal pro-
cessed per day and daily processing of about 100,000 Ib,
Norfolk Tallow Company, Chesapeake, Virginia reports a
20,000 Ib/hr processing rate for the continuous-type plant.
-------
1-52
Rendering Processes - The rendering process 1s comprized
of 3 basic steps:
1. Grlnelng
2. Cooking
3. Separation of tallow from protein-bone meal.
The grinding breaks down the offal to a homogeneous
hash which 1s then charged Into the cooker. In the older
plants the cooking 1s a batch process wherein a steam Jack-
eted cooker 1s used. Steam temperatures at 300°F are needed
to digest the bones, hooves, hides and hair, 1n addition to
the meats and fats. Process times range from 1 to 4 hr.
The moisture content of the charge Is Initially 40% to 50%
which, during the heating phase, 1s reduced considerably,
the steam being vented through a condenser.
The exhaust steam contains very odorous gases which are
1n part dissolved 1n the condensate and in part escape through
the condenser 1n gas phase.
The hot digested mixture or slurry from the cooker Is
then discharged over a screen. Most of the melted tallow
passes through, while the solids or cracklings, consisting
of the digested bones and protelnous constituents, are re-
tained. The cracklings are pressed to remove most of the
adhering tallow. At this point the moisture content of the
cracklings 1s below 8% allowing preservation without refrig-
eration. The tallow Is filtered and then dehydrated by
centrlfugatlon, settling or air blowing.
In the Anderson Carver Greenfield system, the Incoming
raw material Is finely ground and mixed with recycled liquid
fat. In the second step, the fluldlzed ground slurry 1s
pumped through a steam heated evaporator operating at 190°
to 210°F and 27 In. of Hg vacuum. The released water vapor
and noncondensable gases are expelled through a water cooled
contact condenser. The dewatered slurry 1s continuously
centrlfuged to remove the major portion of the tallow from
the cracklings and the cracklings are then run through con-
tinuous presses or expellers to reduce the tallow content.
Some materials (blood and feathers) that do not contain
tallow are digested and dewatered 1n batch dry rendering
cookers.
-------
1-53
Pollutant Emission - Odorous pollutants escape from
several locations of the older batch operated plants. Mea-
surements were made by IIT Research Institutes (1971) to
establish a sem1quant1tat1ve assay on the magnitude of
various plant type vapor samples. The estimates are reported
1n micrograms (ug) per liter of plant air in Table 1-XXVI.
In the third column the concentrations have been converted to
volume ppm, assuming a mean molecular weight of 90.
Table 1-XXVI Concentration of Pollutants in Plant Air At
Various Operating Areas or Exhaust Vents
Concentration ranee,
Area or vent ug/1 ppm
Raw pile area 1.9 to 3.8 0.5 to 1.0
Cooker condenser 10.8 to 11.2 2.9 to 3.1
Cooker dump area 3.1 to 5.8 0.8 to 1.6
Press area 4.5 to 8.5 1.2 to 2.3
Press ventilator 27.4 to 50.4 7.4 to 13.7
Grease drying operation 7.7 to 9.6 2.1 to 2.6
Mills, et.al. 1967, reported estimates of odorant
emissions from rendering operations in the Los Anneles area.
From a survey of beef cattle operations (swine, sheep, poul-
try, etc. were not considered in these estimates) and
assumptions of average weights of cattle and inedible refuse
(mainly blood and offal), Mills calculated that plants
handling refuse from 28,000 cattle would emit about 3x10"
odor units per day from offal and about 5x10" odor units per
day from blood. (An odor unit is the number of dilutions
required to dilute the odor Intensity of a unit volume to
Its recognition threshold concentration.)
For a batch rendering process, Mills (1967) reports
total emissions and odorant emissions as a function of time
during processing. Peak odor emissions take place during
the first hour of operation, as shown In Figure 1-3.
The continuous rendering plant is to a considerable
extent a closed system. In a well maintained plant, pollu-
tant vapors could escape into the atmosphere only at a few
locations; i.e., at the raw material receiving bins, evap-
orator condenser, and at the crackling or meal presses.
The latter two emission points can be readily connected to
pollutant control systems. Odors from the receiving bins
are variable depending on the type of material being pro-
-------
1-54
Odor emission rate
Vapor
emission
rate
1 2
Time for one batch, hr
Flaure 1-3 Typical Rates of Odor Emissions and of Vapor
M Emissions from a Batch-Type Rendering Cooker
Reducing Inedible Animal Matter
-------
1-55
cessed, age of the material and ambient temperature.
Identity of Pollutants Emitted - Table 1-XXVII lists
43 pollutant vapors that have been found 1n air samples from
various rendering operations (Straus, 1964; IITRI, 1971).
An analysis of study results conducted by IITRI (1971) give
Indications that the major part of pollutants are concen-
trated in about nine compounds. The study used the tech-
nique of dual column gas chromatography and mass spectro-
graphy. Thirty chemical compounds were identified in syn-
thetic laboratory vapor samples prepared from prepressed
cracklings, finished crackles and press grease solid samples
from the Chicago rendering plants. Those compounds, as
identified by the Kovats Index, that were in excess of 10%
of the total pollutant mixture are listed in groups 1n
Table 1-XXVIII (Kovats, 1964). Of the nine compounds pre-
dominating 1n the vapor mixtures, five were identified,
namely, 2-methyl propenal, 3-methyl butanal, n-hexanal,
propanoic and butanoic acids. Host of the other compounds
were present 1n fractions of a percent. IITRI did not
report any amine or sulflde compounds although they qual-
itatively detected the latter 1n all samples.
Emission Control - The control of pollutant emissions
from rendering plants poses a difficult problem; one that
has not been solved although attempts have been made.
Factors contributing to the difficulty are:
' 1. Low pollutant concentration, hence negligible
fuel value and thereby a disadvantage in
catalytic and thermal incinerations.
2. Extremely low detection levels of many of
the malodorous pollutants, thereby requiring
large decreases 1n concentrations, a task
difficult to accomplish by mere dilution
with additional air.
3. Release of pollutants at low concentration
levels from many locations thereby requiring
ducting or hooding from many locations or
use of plant wide ventilation.
4. High moisture content and particulates in
the exhaust air.
Operating costs have been estimated for the incineration
and carbon adsorbent systems and are reported in detail in
Chapter 6. The results of the estimates are summarized
-------
Table 1-XXVII Pollutant Vapors Emitted from Meat Rendering Processes
en
Pollutant
Oifurfuryl ether
n-Nonanal
n-Octanal
Oipropyl sulfide
n-Octane
Chemical
formula
[C4H3OCH2]20
CH3[CH2l7CHO
CH3[CH2]6CHO
[C3Hs]2S
Mol wt
178
142
128
120
114
Density,
Ib/qal
9.5
6.9
6.8
6.9
5.8
Boiling
ooint, °F
213
367
325
287
257
LEL,
ppm
10,000
n-Heptanal
3-Hethyl butanolc
acid
Triethylamine
n-Heptane
n-Hexanal
2.4-Dimethyl-l-3-
pentadiene
Toluene
Butanoic acid
n-Pentanol
n-Pentanal
2-Methyl tetra
hydrofuran
n-Hexane
3-Methyl butanal
2,3-Dimethyl-l,3-
butadiene
Benzene
?
[C2H5J3N
CH3[CH2]5CH3
CH3[CH2]4CHO
CH2=CH[CH3]CH
C[CH3]2
C6H5CH3
C3H7C02H
Q[CH2]3C,HCH3
CH3[CH2]4CH3
[CH3]2CH2CHO
CH2=CCCH3]C[CH3]
CH2
C6H6
114
86
86
86
82
78
7.1
7.1
5.5
6.7
6.2
7.3
311
102
101
100
100
96
92
88
88
86
7.8
6.1
5.7
6.9
...
7.2
7.9
6.8
6.8
350
192
209
269
V »
231
327
280
218
...
12.000
12,000
...
. . .
14,000
...
10,000
172
156
166
157
176
11,000
25,000
14,000
-------
Table 1-XXVII (continued)
Pollutant
Chemical
formula
1-Butanol
Propanoic acid
Diethyl amine
2-Methyl propanal
n-Pentane
n-Butanal
2-Methyl propenal
Imidazol
Ethanediol
n-Propanol
Trlmethylamine
n-Propanal
Propanone
Propene nitrile
Methanethiol
Ethanol
Ethylamine
Acetaldehyde
Hydrogen sulfide
Ammonia
2-Butanone
Acetic acid
2-Propanol
CH3[CH2]3OH
3
[
CHJ2CHCHO
CH3[CH2]3CH3
CH3[CH2]2CHO
CH2=C[CH3]CHO
C2H5CH20H
[C2H5]3N
C2H5CHO
[CH3]2CO
CH2-CHCN
CH3SH
C2H50H
C2H5NH2
CH3CHO
H2S
NH3
CH3COOH
CH3CHOHCH3
Hoi Wt
74
74
73
72
72
72
71
68
62
60
59
58
58
53
48
46
45
44
34
17
72
60
60
Density,
Ib/qal
6.8
8.3
5.7
6.6
5.2
6.8
6.9
...
9.3
6.7
5.5
6.7
6.6
6.6
7.3
6.6
5.7
6.5
10.8
6.4
7.7
8.7
6.5
Boiling
point, °F
244
286
133
142
97
168
164
492
386
206
39
119
133
172
45
174
63
69
-76
305
244
180
LEL,
ppm
14,000
29.000
18,000
16.000
14,000
14,000
...
...
32,000
21,000
20,000
29,000
30,000
30,000
39,000
33,000
35,000
40,000
43,000
160,000
20,000
40,000
23,000
I
(71
vj
-------
I
tn
00
Table 1-XXVIII Most Abundant Pollutants in Vapor Mixtures from Crackling. Grease
and Tallow Durinq Rendering
Kovats Index Probable chemical Percentaqe
of pollutant Identity of poll. in vapor
885 "
886
887
23
2-methyl propenal 29
20
923 3-methyl butanal 36
994 1_ 11
998 J 53
1077 15
1078
1079
1080
1083
1087 _
46
18
n-hexanal 40
13
30
1142 12
1415 '
1420
1425 _
11
16
19
Description of
pollutant odor
unpleasant
aldehyde
unpleasant
rancid
rancid
rancid
aldehyde
aldehyde, musty
aldehyde, musty
aldehyde, musty
aldehyde, musty
aldehyde, musty
minty, unpleasant
unpleasant
unpleasant
unpleasant
-------
Table 1-XXVIII(continued)
Kovats index
of pollutant
1504
1509
1511
1595
1599
1603 J
Probable chemical
Identity of poll.
propanoic acid
butanoic acid
Percentaqe
in vapor
15
17
26
15
10
23
Description of
pollutant odor
unpleasant, soap
unpleasant, soap
soap
putrid,
putrid,
putrid
rotten
rotten
i
tn
-------
1-60
graphically 1n Figure 6-31. Results taken from Figure 6-31
show that to operate the three systems at the 10 ppm concen-
tration level, as found 1n rendering operations, the costs to
clean the exhaust air would be approximately as follows:
Type control system
Thermal Incineration
Catalytic Incineration
Carbon adsorbent
Cost to clean
$/hr per 1000
exhaust
ftVmln
air,
f low
1.27
0.95
0.52
Although the carbon adsorbent system can be operated at the
lowest cost, there 1s some uncertainty that 1t can effect
complete removal of all pollutants. As reported 1n Table
1-V, 28 of the 43 pollutants have Vm between 80 and 190 cm3/
mol but Included 1n these 28 are the pollutants appearing in
the exhaust alrstream at the highest concentration; see
Table 1-X for Identity of these pollutants. No real problem
1s foreseen 1n the adsorption and desorptlon of the predom1»
nant pollutant vapors. 13 of the 43 pollutants, however,
have Vm less than 80 cm3/mol. Retention of some of them may
be poor so an early penetration at low concentration may
occur. Thermal and catalytic Incinerators also operate at
less than 100% efficiencies. The relative effectiveness of
carbon adsorbent and incineration systems can only be deter*
mined under actual operating conditions.
Fish Rendering Industry
The main pollutants from the fish rendering operations
as reported by Conrad (1971) are as qlven in Table 1-XXIX.
The pollutants are listed downward 1n decreasing order of
concentration and the concentration range 1s 1 to 12 ppb.
Table 1-XXIX Pollutant Emissions From Fish Rendering
Pol lutant Odor threshold, ppb
Dimethyl dlsulflde
Tr1methylam1ne
Ethanethlol
Carbon dlsulflde
Propenal
7.6
0.2
1
210
210
-------
1-61
The odor threshold (Stern, 1968) concentrations of tri-
methylamine and ethanethiol are of such low value that even
on considerable dilution in the atmosphere after leaving
the plant operating area they are still detectable.
Escape of pollutants occurs in several steps of the
process, but one of the larger emission sources is the fish
meal drier, Mills (1963) has reported exhaust airflow rates
and odor concentrations for various fish meal input rates.
To indicate the pollutant emission rate level, the exhaust
gas volume for a drier of 10 ton/hr meal input rate is
18,500 ftVmin and concentration is 1,500 odor units. If
dimethyl dlsulfide is assumed to be the predominant odor
the pollutant concentration is of the order of 10 ppm, but
if the predominant odor 1s that of trimethylamine, the
pollutant concentration is of the order of 0.3 ppm.
The problems of pollution control in the fish rendering
plants are expected to parallel those of the meat rendering
plants. According to Conrad (1971) the public complaints
are directed mainly toward particulate emissions rather than
odors from the plant. Also odors from unloading ships are
subject to more complaints than from the fish processing
plants.
Canning Industry
Vegetable, meat and fish canning Industries have some
odor problems, with the fish canning emitting the most offen-
sive variety while the vegetable canning, the least.
Vegetable Canning - The basic source of odor comes from
the blanching operation which is done as soon as possible
after the vegetables have been removed from the field. This
is done to facilitate preparation procedures such as removal
of skin and to prevent deterioration due to the time lag
between picking and canning. Although odors are emitted
which could be judged objectionable by normal standards,
canning plants are usually located close to the source of
the vegetables in rural areas. The majority of the people
1n the area are employed 1n the industry and thus odor is
accepted as a necessary factor.
Fish Canning - These canneries are located near harbors,
and fish rendering plants are located near the canneries to
process the by-products. Much of the odorous air pollutants
attributed to canneries come from by-product processes Only
choice fish parts are canned for human consumption, the re-
mainder being converted Into by-products such as fish oil
and protein animal feed supplements.
-------
1-62
Canning preserves highly perishable fish foodstuffs.
Hsh are canned by two methods. In the older "wet-fish"
method trimmed fish are cooked directly 1n the can. The
newer method, "pre-cooked process", 1s characterized by cook»
1ng the whole, eviscerated fish, and by hand sorting of
choice parts before canning.
In wet-fish canning, open cans containing the fish are
conveyed through hot exhaust boxes where live steam cooks
the fish. At the discharge end, cans are mechanically up-
ended to decant stick-water (condensed steam, juices, oils),
which is collected and retained for by-product processing.
Cans of drained fish are filled with oil or sauce, sealed
and pressure cooked.
In the precooked process (used for larger fish), whole,
eviscerated fish are put 1n baskets and then live-steam
cooked. After cooking, the fish are cooled and placed on
a conveyor belt where the choice portions are picked by hand.
packed and sealed Into cans, and then sterilized by pressure
cooking. The scraps and stick-water are collected and trans*
ferred to the rendering processes.
A1r pollution from fish canning 1s due to the malodorous
organic compounds carried out with the steam vapors vented
from cookers and 1s also due to nonsoluble and noncondensable
vapors released from the stick-water. To abate the odor
release several control operations are required, the first
of which is the condensing of the steam. This operation
will remove some of the water soluble and condensable vapors.
The remaining vapors, including varying amounts of air, may
then be burned by catalytic or thermal incineration. If
particulates are present, a water spray and demlster are
required prior to the catalytic incinerator. If air en-
tralnment 1s large so that pollutant concentration 1s low,
a carbon resorb system following the water spray and demlster
may be more economical.
The odor vapors have not been identified but their
Identification will, in this case, not be a factor in deter.
mining the effective use of a carbon resorb system. Most of
the compounds 1n the lower part of Table C-I, up to 80 cm3/
mol Vm, would be removed by the water spray because of their
water solubility. Five compounds are not water soluble -
namely: methanethiol, propyne, dichloromethane, carbon
disulfide and ethanethlol - but of these, carbon disulflde
and ethanethlol and all those that are above 80 cm3/mol,
Vm, are adsorbed strongly enough to be removed.
-------
1-63
Meat Canning - The processes Involved 1n meat canning
Involve: (1) cooking of the meat In a sealed kettle, (2)
transfer of meat from the kettle to cans, (3) conveyance
of the cans through an exhaust box and (4) sealing of the
cans.
Odor release occurs when the kettle 1s opened and
during conveyance through the exhaust box. In both cases
the odors are released in the presence of considerable
steam. As in fish canning, condensation of the steam is
the first step in pollution control, followed by Inciner-
ation or adsorption of the Insoluble and noncondensable
gases. The factor determining whether incineration or
adsorption is used is the pollutant concentration.
Restaurants
Based on the San Francisco Bay Area survey (Bay Area
1969), the estimated pollution rate from restaurants is
1.6 Ib/da per 1,000 people or, for 15,000 restaurants, at
a rate of 0.4 Ib/da per average restaurant.
Kitchen odor emissions come from the grill and frver,
vegetable cookers and steam tables. In small operations,
these are all vented through a common duct. In large oper-
ations a separate ventilation system is directed to'frying
and grilling, and emissions from vegetable and steam tables
are controlled by the main ventilation system.
The primary source of odors is from the frying and
grilling operation, but the identities of the pollutants
have not been determined. Qualitatively the pollutant 1n
the restaurant exhaust can be described as oily matter of
a wide range of particle sizes, accompanied by various food
volatiles and decomposition products. The predominant odor
character is oily. Acrolein, a dehydration product of gly-
cerol, is present to some extent in effluent from fat fry-
ing, but it 1s not the predominant odor.
A carbon resorb system can be an effective means for
removing the pollutant vapors from the exhaust to the out-
doors since carbon air purification systems are used in the
dining areas of the restaurants to remove kitchen odors.
The carbon resorb system would have to be well protected
from the oily partlculates by means of dry filters or wet
scrubbing.
-------
1-64
Meat Smokehouses
Control of pollutant emissions from smokehouses appear
to be better controlled by thermal Incineration than by
sorbent systems due to two reasons: (1) the emission con-
tains poorly adsorbed methanal, and (2) the pollutant con-
centration Is generally in the 1100 to 1500 ppm range where
the sorbent system 1s not economically competitive with the
catalytic and thermal incineration systems. The use of ther-
mal incinerators has not, however, been entirely successful
in controlling smokehouse pollutant emissions. Pollutants
identified in the emissions are as follows:
Pollutant Concentration, ppm
Methanal 20 to 40
Higher aldehydes 140 to 180
Formic acid 90 to 175
Methanoic and ethanoic add 460 to 500
Phenols 20 to 30
Ketones 190 to 200
Resins 1000
According to the U.S. Industrial Outlook, 1970, smoked products
are being prepared chemically, hence, smokehouses may be elim-
inated 1n the near future.
Coffee Roasting
Coffee roasting is in the doubtful category. The
effluents are emitted at temperatures in the 500° to 900°F
temperature range and contain both partlculate matter and
vapors, the vapors being the lower molecular weight alde-
hydes, lower molecular weight organic adds, hydrocarbons
and mercaptan at total concentration near 500 ppm. Under
these conditions the estimated control cost with a carbon
resorb system would be over $0.80/hr per 1000 ft3/min of
gas flow. The operation would Involve cooling the gas
stream, partlculate filtration and burning of the desorbed
pollutants. Catalytic Incineration, at 500°F gas tempera-
ture, would cost about $0.80/hr per fts/rnin and about
$0.41 at 900°F gas temperature. Particulates may have to
be filtered from the gas stream at the elevated temperature.
Thermal incineration would cost about $0.97/hr per 1000
ftVmin at 500°F gas temperature and less at 900*F. The
latter would have an advantage in that the partlculates
would also be burned to a large extent If not completely.
-------
1-65
Tobacco Curing, Zinc Plating and Tanning
Tobacco curing, zinc plating and tanning do not appear
controllable with carbon adsorbent systems operated at normal
temperatures, because of the low molecular weight pollutants.
The pollutants emitted by these industries are listed below:
Tobacco curing
Ammoni a
Methanal
Methanol
Acetic add
Asparagine,
[H2NC(0)CH2CH(NH2)
COOH]
Zinc plating
Ammonia
Tanning
Ammonia
Methanal
The ammonia is not controllable with unimpregnated activated
carbon systems. A carbon impregnated with phosphoric acid
will react with the ammonia, but regeneration is expected to
be too expensive. In a dry airstream such as might be the
case with zinc plating, a molecular sieve sorbent system
would be feasible and desorption then done by heating and
returning the ammonia back into the operations. The methanal
and methanol are also poorly adsorbed by activated carbons,
hence, competing systems or methods have been considered.
Some catalysts decompose ammonia to N2 and H2» a possible
answer to zinc plating pollution problem, unless traces of
ammonium chloride or zinc chloride poison the catalyst. A
two catalyst bed would be required for tobacco curing and
tanning; the second being a combustion catalyst to burn
methanal and the other organics.
Control of Pollutants from Incinerators
Most of the refuse in San Francisco was burned in
residential incinerators (Bay Area, 1969). For 1969, the
number of reported residential incinerators was 1,080,000
tons of refuse per day. Also in use were
commercial Incinerators which burned 15
day and 744 multiple chamber commercial
burned 398 tons of refuse per day. There
was a drastic difference in the amount of pollutant" emitted
by each type of incinerator. The reported emission factors,
as given in Table 1-XXX indicate incomplete combustion in
the residential incinerators, resulting in excessive emissions
of organics, particulates and carbon monoxide. The use of
which burned 2,214
305 single chamber
tons of refuse per
incinerators which
-------
1-66
multiple chamber commercial Incinerators for the burning of
all refuse appears to be one of the better solutions to the
Incineration pollution problem. With the latter the organic,
partlculate and CO emissions are reduced to very lov/ levels.
Table 1-XXX Pollutant Emission Factors for Three Types
of Incinerators
Type
Residential
Commercial,
single
chamber
Commercial
multiple
chamber
Emission factor. Ib pollutant/ton refuse
Organic Part. MOx SOX CO
252
90
0.8
24
8
2.5
0.1 1.0 600
1.0 1.0
2.0 1.0
84
0.05
A carbon adsorbent system, to clean up the effluent from
the residential Incinerators would not be practical, because
the adsorbent system would have to be operated at, (1) very
adverse conditions, (2) 1t would not remove CO, and (3) the
desorbed pollutants would have to be disposed of.
Baking and Candy Making Industries
The candy manufacturing and baking 1
concentrations of odors which most people
objectionable. In candy manufacture, the
comes from roasting the cocoa beans. The
the odors are not reported 1n literature.
emission from the baking industry is etha
emissions from these two sources is not a
trol of emissions from the other sources
However, the use of incinerators for thei
have been reported.
Other Emission Sources
The industries listed in Table l-II account for a high
nercentage of the pollutant volume emitted from small sta-
tionary emission sources and also those that are of major
ndustrles emit low
do not find highly
main source of odor-
chemical nature of
The main identifier
nol. Control of odo»»
s urgent as the con-
discussed previously
r successful control%
-------
1-67
concern because of malodorous emissions. Other existing
and potential sources solvent and malodor emissions of lesser
concern are recognized and are listed as follows:
Hospital exhausts
Veterinary laboratories
Cork products
Sewage vents
Perfume manufacture
Soap manufacture
Pesticide manufacturing
Cosmetic manufacturing
Fur processing
Textile finishing
Crematoria
Lagoons
Settling ponds
Stables
Fertilizer manufacture
Sulfite paper mil Is
Pipe coating
Asphalt air-blowing
Pharmaceuticals
Plywood manufacture
Electroplating exhaust
Azo-dye manufacturing
Waste water plants
Breweries
Distilleries
-------
2. Environmental Effects
Introduction
The primary concern over the uncontrolled emission of
air pollutants is their adverse effects on the environment.
These effects range from toxicity to humans, animals and
vegetation to materials damage, soiling and loss of visi-
bility. Of paramount importance are the toxic effects on
humans, resulting in mortality, morbidity, physiological
and pyschological discomfort and impairment of performance
efficiency. Certain pollutants have toxic effects on vegeta-
tion, leadinq to significant economic loss due to retarded
qrov/th, reduced yield, and, in severe instances, complete
crop destruction, Other effects are damaqe to property,
as by corrosion of metals, deterioration and soiling of
architectural and other painted surfaces and discoloring
and soiling of clothing and other personal effects.
Many of the adverse effects of air pollutants can be
assessed in terms of real economic factors, such as health
costs and dollar losses due to crop and materials damaqe.
Other effects can only be evaluated in subjective terms, but
are still significant in terms of esthetic enjoyment of life.
Nontoxic, but odorous emissions arouse perhaps the most
immediate and vigorous public response to pollutant emissions.
Reduction of visibility is a pronounced esthetic effect of
particulate and aerosol emissions and atmospheric interactions
such as photochemical smog formation.
Much has been published concerning the adverse effects
of air pollutants and this study has not attempted to make
a definitive review of the subject. For good general reviews
and related bibliography, reference may be made to the air
quality criteria published by DHEW and EPA for each of the
major classes of air pollutants (reference criteria documents).
This study oresents only a brief review of effects associated
with those pollutant classes identified as beino emitted by
small sources and controllable by packaged devices.
The magnitude of the damage to the environment from ex-
posure to air pollutants is dependent on two factors: the
potential of the pollutants to produce the adverse effects
mentioned above and the concentration of the pollutants 1n
the atmosphere. The evaluation of these two factors, as re-
lated to emissions from small sources, is the purpose of this
chapter.
-------
2-2
Evaluation of Pollutant Concentration
The pollutant concentration that can develop 1n any
area will depend 1n part on the pollutant emission rates at
the various sources and 1n part on the air mass movements
and other meteorological conditions. As indicated by the
numbers given 1n Table l-III, the average emission rate of
all types and from all sources is approximately 5,000 Ib/da
per 1,000 people, with a 130% variation for the nine densely
populated areas referred to. In these, and all areas, the
pollutant concentrations will vary with the prevailing
meteorological conditions. For Los Anqeles County and San
Francisco Bay Area, the meteorological conditions are unfav-
orable for the dilution of pollutants in the inhabited areas.
In some of the other survey areas the meteorological condi-
tions are more favorable, but notso favorable that no effort
1s required to reduce the overall emission rate.
Pollutant dispersion models have been developed which
allow the estimation of pollutant concentrations from point,
line and area emission sources (for example, Martin and
Tikvart, 1968). Considerable Improvement 1s yet required,
however, to allow realistic modeling of urban, Industrialized
areas, particularly where atmospheric Interaction and smog
formation 1s prevalent.
The current best estimates of pollutant concentration
levels required to be protective of human health are those
given 1n the Federal primary and secondary ambient air
quality standards. Table 2-1 gives the standards for six
pollutants as established by the Environmental Protection
Agency (EPA, April 30, 1971). The primary standard is the
pollutant concentration level considered to be protective
of human health, with a safety margin. The secondary
standard is more restrictive 1n regard to SOx and partlc-
ulate concentrations. It 1s protective also of other as-
pects of human welfare, I.e., protection against known or
anticipated effects on soil, water, vegetation, animals and
manufactured materials.
When ambient air tests show higher concentrations than
allowable by the Federal standards, action 1s required to
curb the pollutant emission rates. The Identity of the
pollutant very often also Identifies the specific sources
from which it was emitted. In other cases, the pollutants
cannot be Identified with a specific source, but rather to
a group of sources.
-------
2-3
Table 2-1 Federal Ambient Air Quality Standards
Primary standard Secondary standard
Pollutant v/m3 ppm v/mj ppm ""
Carbon monoxide .
max 8-hr conc.(') 10,000 9 10,000 9
max 1-hr cone. 40,000 35 40,000 35
Sulfur oxides
annual arlth mean. 80 0.03 60 0.02
max 24-hr conc.(l) 365 0.14 260 0.1
max 3-hr conc.O) 1300 0.5
Nitrogen dioxide
annual arlth mean 100 0.05 100 0.05
Photochemical oxidants
max 1-hr conc.U) 160 0.08 160 0.08
Hydrocarbons
max 3-hr cone.v' /
6 to 9 AM 160 0.24 160 0.24
Particulates / .
annual geometric mean 75 60\z)
max 24-hr conc.vU 260 ---- 150
(1) This concentration 1s not to be exceeded more than once
a year.
(2) This number 1s to be used as a guide 1n assessing Im-
plementation of plans to achieve the 24-hr standard.
-------
2-4
Table 2-II. based on the survey results of the three
California air pollution control districts (Table l-III).
chows the relative portions of the main classes of pollut-
an?s which J Jht appear In any control district. In these
survey result?, 84* of the pollutants are emitted from motor
vehicles The amount of pollutants from this source can be
expected to be proportional to the population density. The
pollutants emitted from the stationary sources (15X of total)
will also be Influenced to a considerable degree by the In-
dustrialization of the area.
Table 2-II Relative Amounts of Pollutants Emitted From
Various Sources (California 1969)
Pollutant
CO
S02
NO,
Organic vapors
Source
Motor vehicles
Stationary
Motor vehicles
Stationary
Motor vehicles
Stationary
Motor vehicles
Small emission
Other stationary
The total organic vapor emission 1s 18% of which 12% 1S
om motor vehicles. These are combustion products, hence
11 contain high proportions of aldehydes and organic acids
e 2.5* other-stationary-source emissions are primarily *
J J __. f^ A A ^ 4fe ^ A 4h £ ft*
-------
2-5
It is evident that the orqanic pollutants from motor
vehicles will tend to be widely distributed in proportion to
population density. Pollutants emitted from small sources,
althouqh smaller percentage-wise, can create higher concen-
trations in local areas and produce toxic effects, damage to
property and plants, and nuisance effects because of bad odors
On diluting into the atmosphere these pollutants can combine
with the organic pollutants (and NOx)
to raise the concentration level over
contributing to smog formation.
from the other sources
wider areas, thereby
Toxic Effects on Humans
The potential of a pollutant to produ
on humans can be evaluated by two systems.
the threshold limit value (TLV) and is the
concentration of a substance to which 1t i
nearly all workers can be repeatedly expos
without adverse effects. The other is the
grade number, and consists of five numbers
the severity of symptoms felt when exposed
grade numbers are defined as follows:
ce a toxic effect
One of these is
maximum airborne
s believed that
ed day after day
vapor Irritant-
which Indicate
to a vapor. The
Grade 0 Chemicals that are nonvolatile, or the
vapors which are nonirritatlng to the
eyes and throat.
Grade 1 Chemicals that cause a slight smarting
of the eyes or respiratory system if
present in high concentrations. The
effect 1s temporary.
Grade 2 Chemical vapors that cause moderate
irritation, such that personnel will
find high concentrations unpleasant.
The effect 1s temporary.
Grade 3 Moderately irritating volatile chemicals
such that personnel will not usually
tolerate moderate or high vapor concen-
trations.
Grade 4 Severe eye or throat irritants, vapors
which are capable of causing eye or
lung Injury, and which cannot be toler-
ated even at low concentrations.
Table 2-III lists the
pollutants,
identi
with
red by
number.
-------
2-6
Table 2-III
Ranking of Pollutants in Decreasing Order of
Toxicity to Humans
Pollutant
Propenal
Ethanethiol
Ethanolamine
Methanal
Hydrogen chloride
Methanoic acid
Sulfur dioxide
Nitrogen dioxide
Phenol
Trimethylamine
Tetrachlorome thane
Ethyl ami ne
Ethanoic acid
Methanethiol
Hydrogen sulfide
Carbon disulfide
Propanen1tr1le
2,6-D1methyl-2,5-
heptadien-4-one
3-Octanone
Triethylamlne
4-Methyl -3-penten-2-one
D1ethylam1ne
Benzene
2-Methoxy-ethanol
1-Ni tropropane
2-N1 tropropane
4-Methyl -2-pentanol
Ethanenl trile
2,6-Dimethyl-4-heptanone
Hexyl acetate
2-Butoxy-ethanol
4-Hydroxy-4-methyl-2-
pentanone
1 ,2-Di chlorobenzene
1 Ceiling limit, not to
2 Includes skin adsorptl
3 (NFPA) 1969 ratings
Vapor
TLV, irritant
ppm grade No.
0.1 3
0.5
3 /,% 2
5 2
5 (1) 3
5 3
5 3
5 ,_. 3
5 (2) 3
10 MI 3(3)
10 (2) 3
10
10 Ml 2
10 (1) 2
10 , . 3
20 (2) 2
20 4
25 2
25 l(3j
25 2(3)
25 2
25 3
25 2
?5 (2) 2
4» W b . *
25 1(3)
25 1
25 (2) z(3)
40 1
50 2
50 MI
50 (2)
50 1
50 1
be exceeded
on
Industry
6,52,54
51,52
7
57,60,61,63,65
65
57,61
6,63
63
55,61
51,52
6.7.
51
4,51,55,57,61,63
51,55
51,52
52
6,51
4,7
4 .
51 ,52
1,4
51
1,4,6,7,51
1,4,7
1,4,7
1,4,7
1,4
6
1,4,5,8
4
1.4
4,7
4.7,51
-------
2-7
Table 2-III (continued)
Pol lutant
Cyclohexanol
Cyclohexanone
Cyclohexane
2-Furyl methanol
1 ,2-Di chloroethane
2-Methyl pentyl acetate
Ammonia
Pentyl acetate
^ Pinene
2-Ethoxyethyl acetate
2-Hexanone
4 -Me thy 1-2- pen ta none
Ethyl benzene
Xylene
1 -Pentanol
Tetrachloroethene
1-Butanol
2-Methyl-2-propanol
Trichloroethene
Ni troethane
Nitrome thane
Mineral spirits
2-Methyl-2-butanol
Butyl acetate
2-Butanol
1-Methyl-propyl acetate
Propyl acetate
Tol uene
2-Pentanone
Tetrahydrof uran
1-Propanol
Methyl acetate
Ethanal
2-Ethoxy-ethanol
2-Butanone
Stoddard solvent
Isopropyl acetate
1 ,1 ,1-Tri chloroethane
Ethyl acetate
TLV,
ppm
50
50
50
50
50
50
50
100
100/«x
100(2)
100
100
100
100
100
100
100
100
100
100
100
100
100
150
150
150
200
200
200
200
200
200
200
200
200
200
250
350
400
Vapor
irritant
grade No.
1
3
1
1
2
1(3)
3
1 (3)
0,^,
2(3)
-
2
2
1
3
1
1
2
l(3)
1(3)
1
1
1
1
1
1
/ ** \
2(3)
2(3)
1
1
3
2
1
.
1
2
1
Industry
1,4
1,4,6,7
1,4,7
4
6,7
4
51,57,60,63,
1,4,7
1,4
1,4,5,8
1
1,4,5,6,7,8
1
1,4,5,6,7,8
1,4,51
2,3,6,7
1,4,7
4
2,3,6,7
1.4,7
1,4,7,55
1,4
4
1,4,7
1.4
1
1,4
65
1 ,4,5,6,7,8,51
1,4
7
1,4,7,51
1,4.7
51
4,5,7
1,4,5,6,7,8
3
1.4
2.4
1,4,7,8
.51
-------
2-8
Table 2-III (continued)
Vapor
TLV, Irritant
Pollutant _ _ PP* grade N<>- - Industry - .
Diethyl ether 400 2 1,6,7
2-Prooanol 40° ] 1,4,7,9,51
Hexane 500 0 1,4,6,7,9,10,51
Octane 500 1 1,4,6.10.51
XeplSne 500 1 1,4,5,6,7.9
Dllsopropyl ether 500 2(3) 1,4
Dlchloromethane 500 2^' 2,5,7
Naphthas ^500 1 2
l,l,2-Tr1chloro-l.2,2-
trlfluoroethane 1000 - z,3
Pentane 1000 1 4,6,10,51
2-Methyl-butane 1000 - JO
1,3-Butadlene 1000 2 4,6
Propanone 1000 1.4,5.7.51.61
1000 1 lu.b/
1000 1 1,4,5,7.51,52,58
Propene fOOO ](3) 57
Propyne 400° ] 4
The TLV values are from MCA (1970) and ACGIH (1970) and the
vapor Irritant grade number from Committee on Hazardous
Materials (1970). The last column 1n the table Identifies
the pollutant with the Industry from which 1t was emitted;
see Table l-II for Industry Identification.
The most toxic pollutants, up to 20 ppm TLV, are emitted
predominantly from the processing Industries, namely: the
meat rendering, fish rendering, coffee roasting, tobacco
curing, tanning, meat smokehouses, zinc plating and also
domestic Incinerators. Two solvent user Industries, the
rubber products and adheslves, also emit pollutants in this
TLV range. Several other pollutants of lower toxldty (tr1«
ethylamlne, benzene, 1,2-d1chlorobenzene, ammonia and 1-
pentanol) are also emitted from the process Industry. The
pollutants of lesser toxldty, I.e., with TLV larger than
20 ppm, are predominantly emitted from the solvent user
industries; namely, the surface coating, degreaslng, dry
cleaning, graphic arts, etc.
-------
2-9
The most toxic pollutants are emitted by industries
which, on the per 1,000-population basis for the control dis-
trict, have the lowest emission rates. However, the local
areas under adverse meteorological conditions can experience
toxic effects.
A comparison of the TLV values with the Federal standard
of 0.24 ppm for hydrocarbons indicates a very large safety
factor for the Federal standard in regard to toxicity. The
hydrocarbon standard is based solely on the relationship of
nonmethane hydrocarbon concentration to the resulting photo-
chemical oxidant levels. Correlation of the 6 to 9 AM non-
methane hydrocarbon levels with the peak oxidant levels show
an approximate three to one relationship. Thus, to maintain
a standard of 0.08 ppm oxidant, the nonmethane hydrocarbon
concentration should not exceed 0.24 ppm.
Odor Effects
Psychological and Physiological Effects
Odors may affect humans in different ways depending not
only upon the characteristics of the odor, but also on the
individual and his environment. Odors, per se, are not the
cause of organic diseases or toxic effects. Some highly
toxic gases, such as hydrogen sulfide, are associated with
highly offensive odors, but the dangerous properties do not
come from the odor Itself. In this'case, the odor serves as
a warning of the presence of a harmful gas. Conversely, some
toxic gases may be odorless or have pleasant odors.
Odors can, however, aggravate attacks of asthma and
other allergic conditions which cause loss of appetite,
lowered water consumption, breathing difficulties, nausea,
vomiting and insomia (Sullivan, 1969). Asthmatic attacks can
be triggered by odors from hay, mustard, animal skins, fer-
mentations, paint, sulfur and cooking (Horesh, 1966). Mal-
odorous gases are harmless to the average Individual, but
these gases can set off an allergic attack in sensitized
Sf°ol«;c 5nrfK ( 66) re!1ewed the importance of the role
of odors 1n the management of allergic diseases and reported
that odorous irritants are significant factors in asthma
hay fever, eczema, migraine, rhinitis, allergic crouDtra-
cheitis, dermatitis and gastrointestinal al erSJ AddUlon
al substances incriminated as aggravating a?"ergy- Add^1on.
Include odors from turpentine, dimethyl su
-------
2-10
Ranking of Pollutants According to Odor Response
Odors may be ranked on the basis of detection and
threshold concentration and recognition threshold concen-
tration. The latter method is used by odor investigators
more frequently and values for more odor compounds are
readily available. The more odorous pollutants emitted
from small sources are listed in Table 2-IV according to
increasing recognition threshold concentration, or decreas-
ing odor response. The values for this table were obtained
from Copley (1970) and Leonardos (1969).
The ranking of odorous emissions by recognition thres-
hold concentration provides only a partial measure of the
objectionable nature or perceived effect on human subjects.
The odor quality has significant bearing on the subjective
response or odor perception. Psychological differences in
exposed humans tend to obscure this differentiation, how-
ever, since what is objectionable to one individual may
elicit a different response from another.
Other properties of odorous emissions have been used
for ranking or differentiation. Moncrlef (1968) attempted
to differentiate odors by subject acceptability. Certain
compounds were generally unacceptable: mercaptans, sulfides
and amines. Individual differences tended to limit the
ranking of other compounds.
The human response to odor sensations may be quantita-
tively expressed by the Weber-Fechner law which states that
I - k In c
where I 1s the Intensity of the odorant, k is a constant and
c 1s the odorant concentration. The usual method of utilizing
this expression is by human panel testing of dilution ratios.
The constant 1n the Weber-Fechner expression is a measure of
the pervasiveness of the odorant (Sullivan, 1969). Extremely
pervasive odors are those whose odor Intensity remains un-
changed or shows only slight change (small k values) on di-
lution. The intensity of an odor 1s generally expressed In
'odor units' which gives the number of dilutions required to
reduce the odor to its recognition threshold concentration
level.
Additional factors which limit the characterization of
odors by human response are olfactory fatigue and odorant
mixtures. Olfactory fatigue 1s a well recognized phenomenon
by which odor perception Is lessened or in some instances
completely inhibited by prolonged exposure.
-------
2-n
Table 2-IV
Odor Recoqni zabili ty
Pol lutant
Trimethylamine
Hydrogen sulflde
Butanolc acid
Ethanethiol
Ni trobenzene
Dimethyl sulfide
Dipropyl sulfide
Me thane thiol
Methyl ami ne
Carbon disulfide
Pentyl acetate
Furfural
Propenal
4-Methyl-2-pentanone
Xylene
Dimethyl amine
Sulfur dioxide
Methanal
Butyl acetate
Phenol
1 -Butanol
Ethanoic acid
Nitrogen dioxide
Isobutyl acetate
Tetrachloroethene
2-Pentanone
Butanone
Gasol ine
Propeneni trile
Propyl acetate
Dichloromethane
Tetrachloromethane
2-Ethoxy-ethanol
Ethanol
Mineral spirits
(aliphatic)
Propenol
Tetrahydrofuran
Benzene
Odor
q u a 1 1 ty
fish
cabbage
sour
earthy
shoe polish
vegetable
fish
rotten egg
pears
new bread
burnt, sweet
sweet
fish
cabbage
pungent
hay-like
sweet
vinegar
irritating
...
...
sweet
- -
onion
pears
___
~- -
...
-- -
Recognition
threshold,
ppm
0.0002
0.0004
0.001
0.001
0.004
0.02
0.01
0.02
0.20
0.20
0.1
0,2
0.2
0.5
0.5
0.5
>0.03
1.0
>0.6
1
1
1
1 to 4
4
5
8
10
10
1 to 20
20
21
21
25
10 to 25
30
30
30
3 to 60
Industry
51 ,52
51 ,52
51
51,52
...
« .
51
51 ,55
...
52
1,4,7
6,52,54
1,4,5,6,7,8
1,4,5,6,7,8
« _ M
6,63
57,60,61,63
1.4,7
55,56
1,4,7
4,51 ,55,57,61
63
1,4
2,3,6,7
1,4,6,7
1,4,5,6,7,8
50
6,51
1,4
2,5,7
6,7
4,5,7
1.4,5,7,51,
1 4
1 , "
7
1,4,6.7.51
,51
58
-------
2-12
Table 2-IV (continued)
Pollutant
2-Methyl-l-propanol
2-Propanol
Ethyl acetate
Ammonia
2-Methoxy-ethanol
Isopropyl acetate
Tri chloroethene
2-Propanone
Octane
Heptane
Methanol
Methyl acetate
Dichloromethane
1,1,1-Trichloroe thane
Odor
quality
fragrant
pungent
pears
fragrant
Recognition
threshold,
ppm
40
40
50
47
60
30
20
100
150
220
to
to
80
300
100
200
150 to
400
200
Industry
1,4,7,9,51
1,4,7,8
51,57,60,63
1.4,7
1,4
2,3,6,7
1,4,5,7,51,61
1,4,6,10,51
1,4,5,6,7,9
1,4,7.55,57
1,4,7
2,5.7
2,4
Odor intensities, as measured by human panel response,
vary widely when mixed odors are used. Rosen, et.al. (1962)
investigated the odor perception of mixed odorants and found
that intensities of mixed systems may exhibit a variety of
interactions. Intensities may be additive, counteractive,
synerqistic, or independent. Data on odor interactions of
butanole p-cresol and pyridine are shown in Table 2-V.
The most malodorous pollutants are emitted from the
process industries, primarily the meat and fish rendering.
Many of the odorous pollutants at the top of the list are
also at the top of the list in Table 2-III for their toxicity,
although odor is not the cause of toxicity. Except for
ammonia, methanol, propanone, and methanol, the less mal-
odorous pollutants are emitted from solvent user industries.
Under adverse meteorological conditions, local areas near
rendering, coffee roasting, tobacco curing, tanning and meat
smokehouse operations can experience periods of malodors.
A comparison of the recognition threshold concentrations
in the upper part of Table 2-IV with the Federal standard
of 0,24 ppm for hydrocarbons indicates that standard is not
restrictive enough, assuming the term hydrocarbon refers to
all organic pollutants. A fair number of the pollutants have
recognition threshold concentrations considerably below 0.24
ppm. As mentioned above, the Federal standard is based solely
-------
.2-13
on health effects and does not take odor into consideration.
The A1r Quality Criteria for Hydrocarbons (NAPCA Publication
AP-64, March 1970) concludes that, hydrocarbons, per se, do
not exhibit adverse health effects at the usually occurring
ambient air concentration levels.
Table 2-V Odor Interaction in Mixtures
Fraction of Odor Threshold Concentration at
Which Odor was Perceived
Butanol
0.46
0.37
0.35
0.24
0.18
0.15
0,12
rn ftal
p-Cresol
..
0.14
0.40
0.19
0.21
0.09
0.21
concentration
Pyridine
0.53
0.42
--
0.29
0.21
0.26
0.07
Total*
Mixture
0.99
0.93
0.75
0.72
0.60
0.50
0.40
additive threshold concentrations
Odor Control
Concentration Reduction Methods - Odor control is a
term which nay be used to describe any process which makes
olfactory experiences more acceptable to people. This can
be done by reducing the odor intensity or concentration, or
by odor modification. Concentration reduction by sorption
devices is the main theme of this handbook (Chapters 4 and
6) with additional attention, in decreasing order of impor-
tance, also given to catalytic and thermal Incineration
-------
2-14
(Chapters 5 and 7). Concentration reduction by dilution
with Increased air volumes 1s practiced by many Industries,
but 1t 1s not a satisfactory solution to the problem.
Odo
ceptua
dor Mod_;_f_ 1 ca11 on - It 1s possible to nullify the per-
,., 1 response to a malodorous pollutant by the admixture
of another odorous vapor Into the atmosphere. This 1s com-
monly done by spraying aerosols to control, or mask, mal-
odors coming from cooking, from densely occupied living
quarters, bathrooms, locker rooms, etc. Odor modification
1s also being tried on a larger scale 1n 1~J--'--- -- '
metal decorating operations; see Chapter 1
Control for Graphic Arts Industry.
Industry, as 1n
" under Emission
There 1s no generally accepted physiological mechanism
to explain odor modification. It has been shown that nasal
Inspiration of malodors with masking odors does not prevent
the person from smelling the malodor upon being transferred
to a new environment; hence, the mechanism cannot be attri-
buted to olfactory anesthesia (AIHA, 1960).
The method has some apparent advantages 1n Industrial
applications associated primarily with low Initial equip-
ment costs. It does not counteract toxic, corrosive and
smog-forming potential of the pollutants and 1s therefore
limited 1n Its application.
Toxic Effects of Pollutants on Vegetation
The only (nonsmog) organic pollutant capable of causing
plant damage at low concentrations (less than 1 ppm) 1s
ethene. Other organic pollutants must be present at much
higher concentrations to produce equivalent plant damage.
Concentrations of the order of magnitude required are highly
Improbable from the small emission sources.
Exposure to 0.1 ppm of ethene produces eplnasty (down-
ward bending of leaves and other plant parts). Abeles and
Gahagan (1968) found that 0.1 ppm of ethene produced partial
abscission (shedding of plant parts). This plant response
was also studied with other hydrocarbons. These findings
are combined with those of other Investigators (Crocker,
1935; Zimmerman, 1935; Heck and P1res, 1962 and Burg and
Berg, 1967), and are presented In Table 2-VI. These are the
most active hydrocarbons and, as the results show, they must
be present 1n concentrations of two or more magnitudes higher-
than ethene to produce an equivalent effect.
-------
2-15
Table 2-VI Relative Concentrations of the More Reactive
Hydrocarbons That Produce Biological Response
Similar to That Produced by Ethene
Inhibition of growth
Hydrocarbon Abscission Eplnasty Pea stem Tobacco
Ethene 1 1 1 1
Propene 60 500 100 100
Propyne 1,250 500 2,800 100
1-Butene 100,000+ 500,000 270,000 2,000
1,3-Butad1ene 100,000+ - 5,000,000 ---
The 1norqan1c addle pollutants S02t H2S and N02 have
the capacity to damage vegetation. Concentrations higher
than 0.1 ppm of the sulfur compounds can cause Injury, while
slightly higher concentrations of NOg are required. Sulfur
dioxide 1s emitted from the rubber products and sulflte paper
Industries and domestic Incinerators. Hydrogen sulflde 1s
emitted from the rendering operations and N02 from commercial
Incinerators. The contribution from the small emission
sources compared to the total emission of these pollutants
from other sources (power plants, motor vehicles, etc) 1s
very small. Local effects may occur under unfavorable
meteorological conditions.
Synerglstlc effects of mixed air pollutants can often
result 1n Increased plant damage over that observed for the
single pollutants. Examples of such synerglsm are given by
H1ndaw1 (1971).
Smog products, primarily ozone and peroxyacetyl nitrate
(PAN) are principal contributors to economic crop loss 1n
such affected areas as Southern California.
Excellent descriptions of the types and manifestations
of vegetative response to air polluants are given 1n the
Handbook of Effects Assessment (Lacasse and Moroz, 1969).
-------
2-16
Damage to Materials
Observable corrosive action occurs on unprotected
ferrous metals with S02 at concentrations less than 0.1 ppm.
Nonferrous metals corrode at hiqher concentrations. In both
cases the corrosion rate increases with increased concentra-
tion, temperature and humidity. The presence of particulates
is also a corrosion rate Increasing factor.
Paper and leather are oxidized to sulfates and some
textiles are weakened. Sulfur dioxide and hydronen sulfide
discolor painted surfaces. Dyes are faded by nitrogen di-
oxide.
Clothinq can be soiled by the pervasive odor emitted
from rendering plants. Otherwise, organic pollutants are
not considered as particularly damaging to materials.
The contribution from the small emission sources com-
pared to the emission of these pollutants from other sources
(power plants, motor vehicles, etc) is very small. Their
effects will be felt locally, near the emission sources
under adverse meteorological conditions.
Smog Forming Potential of Pollutants
Nature of Smoo
A haze or mist, which appears to be a combination of
smoke and fog, 1s produced photochemlcally when certain or-
ganic vapors in the atmosphere are exposed to solar radiation
in the presence of nitrogen oxides. The products of the
Photochemical reactions have been identified as oxldant
(ozone), nitrogen dioxide, peroxyacetyl nitrate (PAN), peroxv
ytra (PBzN>» metha"a'. Particulates. aerosol,
Hoic . . , n
H2S04 mist. These substances produce eye irritation, plant
damage, reduced visibility, material damage, Injury to healfh
and a characteristic odor. The H2S04 mis? is evidence thJt *
S02 is also a contributor to smog formation.
These effects are not produced by the primary contam<
nants, but appear after the photochemical oJidaJ'on h
place. All pollutants are not equally active and also
duce different smog effects. For example, the eye rr
smog is not the same as the plant toxicant as evidlnrn
the fact that the half-life of the two IffectI arl d?55
Therefore, it Is important to rate po?lStants accord nj
their role as smog precursors as well as their direct 1r+
or nuisance effects as discussed in the previous text. nt
-------
2-17
Distribution of Smog Forming Pollutants
Smog producing pollutants are ever-present where the
population densities are high because the main source is
motor vehicles. Tab-le 2-VII designates the type, source
and rate of the smog active pollutant emissions as calculated
from the California (1969) survey results. The estimated
emission rates of active organic and NOX pollutants from
motor vehicles are 360 and 200 Ib/da per 1,000 people, re-
spectively, and by far the largest emissions from any source.
Heavy smog can always form where the meteorological condi-
tions are unfavorable for the dispersion of pollutants.
Where appreciable air mass movements occur, the smog thins
out over a larger region. Ultimate disposal of the smog
can be by a slow absorption into vegetation and terrain or
by the rapid scrubbing action of rain.
Table 2-VII Sources of Smog Forming Pollutants of High
and Low Activities
Emission rate,
Type and Ib/da per 1,000 people Percentage
source of HighU) Low of organic
pollutants activity activity pollutants
Organic from 360 46
motor vehicles 160 20
Organic from
solvent users 35 4
and fuel 110 14
marketing
Organic from 20 3
other stationary 100 13
sources
Organic totals 415 370 100
NOX from
motor vehicles 200 --- ---
NOx from
stationary 95 --- ...
sources
(1) High activity refers to all olefins, substituted
aromatics and aldehydes.
-------
2-18
Th(* rate of smog active pollutant emission from the
solvent user industries is low compared to that from motor
vehicles, being only 35 lb/da per 1,000 people. The effects
will also be felt regionally rather than locally because:
(1) a time lapse occurs during which the organic pollutant
mixes in with NOx from other sources, (2) the photochemical
reactions are slow, allowing the air mass movements to carry
the mixtures over a large region before the reactions are
completed, and (3) emissions produced during nondaylight
hours are dispersed and then react during the daylight hours.
A typical polluted atmosphere may have NOx and total
organic pollutant concentrations of the order of 0.5 ppm
for each. Los Angeles (in 1970) defined a day of photo-
chemical smog as one in which the average oxidant level is
0,10 ppm for 1 hour.
Active Smog Precursors
The smog forming potential exhibited by organic pol-
lutants has been related to the pollutant chemical structure
by the investigators 1n the Los Angeles County pollution con-
trol districts. Those classified as highly active are all
of the olefins, substituted aromatics, aldehydes and ketones
having a branched hydrocarbon structure. This method of
classification is the basis for the separation of high ac-
tivity and low activity groups in Table 2-VII. The percentage
of high activity pollutants emitted from motor vehicles (only)
1s 69%, while from the solvent users and other stationary
sources the percentages are 24 and 17, respectively.
Of the 167 pollutants listed in Table C-I (Appendix C),
41 can be classified as being highly active smog precursors.
These are listed in Table 2-VIII with a separation made for
those emitted from the solvent user industries and those
from the process industries. The emissions from the process
industries are small, and hence do not make a significant
contribution to smog formation. Those from the solvent
user industries, and including fuel evaporation, contribute
about 8% of all the active organic pollutants. Of the 20
solvents listed, toluene, xylene and trichloroethene are
emitted at the highest rates; hence, these three solvents
are the main contributors to smog from the small emission
sources, There is a sizable number of lower activity smoq
precursors which make a lesser contribution.
Ranking of Smog Precursors
There are several reactivity classification systems
derived from different sets of data and experimental condi-
tions. Of these, a reactivity scale based primarily on
-------
2-19
product yields and biological effects was proposed by Alt-
shuller (1966) and Levy (1970). Altshuller took into con-
sideration the parameters: ozone or oxidant yield, peroxy-
acetyl nitrate (PAN) yield, methanal yield, aerosol forma-
tion, eye irritation and plant damage. Levy included the
parameters: nitrogen dioxide concentration, oxidant concen-
tration, eye irritation, and methanal concentration. These
were combined into a single system which rated pollutants
from 0 to 3 in increasing order of activity. This system
was further modified by MSA Research Corporation by expand-
ing the numerical span to 0 to 10.
Table 2-VIII
Pollutants From Small Emission Sources That
Are Active Smog Precursors
Pollutants from
user industries
fuel marketing
solvent-
and
2,6-D1methyl-4-heptanone
2,6-Dimethyl-2,5-heptad1en-
4-one
Butyl benzene
oPinene
2-Methyl-2-hexanone
2,4-D1methyl-3-pentanone
Isopropyl benzene
Propyl benzene
4.Hydroxy-4-methyl-2-
pentanone
4-Methyl-2-pentanone
Xylene
Ethyl benzene
oChlorotoluene
4-Methyl-3-penten-2-one
Toluene
3-Methyl-2-butanone
2-Furyl-methanol
1,3-Pentadiene
Trichloroethene
1,3-Butadiene
Process industries
Nonanal
Octanal
Difurfuryl ether
Heptanal
2,4-D1methyl-l,3-pentad1ene
2,3-01methyl-l,3-pentadiene
Hexanal
3-Methyl-butanal
Pentanal
1-Pentene
Phenol
2-Methyl-propanal
Butanal
1-Butene
2-Methyl-propenal
Propanal
Propene
Propenal
Propenoic nitrile
Ethanal
Methanal
-------
2-20
The expanded rating system was used to rank pollutants
from small emission sources; the ranking is presented in
Table 2-IX. Only a limited number of the pollutants could
be ranked because of lack of complete data (data from Levy,
1970). The most active pollutants are predominantly the
ketones having a branched hydrocarbon structure, olefins,
substituted aromatics, and aldehydes, in agreement with the
classification system used by the California investigators.
Three of the most abundantly emitted solvents, xylene, tri-
chloroethene and toluene, are in the upper part of the rank-
ing list. In the degreasing industry, 1,1,1-trichloroethane
with a relative reactivity of one is promoted as a substitute
for trichloroethene with a relative reactivity of 6. Benzene
is quite nonreactive; substitutions producing xylene and tol»
uene greatly increase the reactivity.
Effect of Smog on the Environment
The effect of smog on the environment is observed as
reduction in visibility, eye irritation and damage to vege-
tation. Eye irritation and vegetation damage are two cri-
teria for determining the pollutant reactivity as smog pre-
cursors used in Table 2-IX ranking. Different pollutants do
not produce the same type of smog; some smogs cause more eye
irritation while others cause more plant damage. Table 2-X
lists the classes of organic pollutants in order of decreas-
ing activity to produce eye irritant or vegetation damaging
smogs.
The most active precursors producing eye irritant and
vegetation damaging smogs are xylene, 4-methyl-3-penten-2-
one, 1-pentene, 1-butene and propene emitted mostly from the
solvent user industries and fuel storage evaporation. 01-
olefins such as 2,6-dimethyl-2,5-heptadien-4-one, butadiene,
1,3-pentadiene and 2,4-dimethyl-l,3-pentadienes are only
highly reactive in producing eye irritant smog. Most of the
latter are also emitted from solvent user industries. The
largest contributor, also volume-wise, is xylene.
Epidemiological studies conducted primarily in Los
Angeles and San Francisco have attempted to ascertain the
existence of correlations of respiratory illnesses, eye
irritation, and other health effects with oxidant level.
These have been reviewed in NAPCA Publication No. AP-63
(March 1970). The general conclusions are that the thres-
hold for observable health effects is about 0.15 ppm oxi-
dant. The highest correlation of effect with oxidant con-
centration is found for eye irritation. Excess mortality,
hospital admissions, and respiratory cancer in the general
public have not shown significant correlation with oxidant
levels.
-------
2-21
Table 2-IX Pollutant Reactivity Ranking As Smog Precursors
Relative
reactivity.
Pollutant vapor 0 to 10 scale Industry
4-Methyl-3-penten-2-one 8 1,4
1-Butene 7 10
Propene 7 57
Xylene 7 1,4,5,6,7,8
1-Pentene 7 10
1.4,5,6,7.8
2,3,6.7
4,6
1.4,5,6,7,8,51
4-Methyl-2-pentanone 6
Trichloroethene 6
1 ,3-Butadiene 6
Toluene 6
4-Hydroxy-4-methyl-2-
pentanone 6 4,7
2,6-Dimethyl-4-heptanone 6 1,4,58
2-Ethoxy-ethanol 6 4,5,7
2,6-Dimethyl-2,5-heptad1en-
4-one 6 4,7
1-Methyl-l ,4-epoxybutane 6 4,51
Isopropyl benzene 6 1,10
Ethyl benzene 6 1
Ethene 5
Butyl benzene 4 1
Cyclohexane 4 1.4,7
Cyclohexanone 3 1»4,6,7
Butanone 3 1,4,5,6,7,8,51
Methanol 3 1,4,7,55,57
2-Propanol 3 1,4,7,9,51
Butanol 3 1,4,7
Diethylamine 3 51
Triethylamine 3 51,52
Propanone 2 1,4,5,7,51,61
Ethyl acetate 2 1,4,7,8
Butyl acetate 2 1,4,7
Ethanol 2 1,4,6,10 ,51
Benzene 1 1.4,6,7.51
Nltropropane 1 1.4,7
1.1»1 ,-Trlchloroethane 1 2,4
Pentane 0 4,6,10,51
Propane 0 10,57
-------
2-22
Table 2-IX (continued)
Relative
reactivity,
Pollutant vapor 0 to 10 scale Industry
Propyne 0 4
2-Ethoxy-ethyl acetate 0 1.4,5,8
Ethanedlol 0 4,51
Phenyl acetate 0 1,4,7
l,l,2-Trichloro-2,2,l-
trlfluoroethane 0 2,3
Table 2-X Ranking of Organic Pollutants Producing Eye
Irritant and Vegetation Damaging Smogs
(Data from Altshuller. 1966)
Response on 0 to 10 scale
Compound or Eye Vegetation
compound class Irritation damage
Internally double-
bonded oleflns 4 to 8 10
Dlalkyl and trlalkyl
benzenes 4 to 8 - 5 to 10
1-Alkenes 4 to 8 6 to 8
D1olef1ns 10 0
Ethene 5 + IU
Toluene and other
monoalkyl benzenes 4. . 0 to.3.
Aliphatic aldehydes +vU IVU
Paraffins 0 0
Benzene 0 0
Acetylene 0 0
(1) Effect noted experimentally, but data
Insufficient to quantltate.
Barth, et.al. (1971) report a study which Indicates the
eve Irritation threshold as being about 0.1 ppm oxldant.
time to cause barely perceptible eye Irritation, based on
human panel testing of synthetic smog, 1s four minutes.
-------
2-23
Pollutant Regulatory Laws
Federal Standards
The purpose of the pollutant regulatory laws 1s to con-
trol emission sources so that ambient air in inhabited areas
is not injurious to health, vegetation, or property, nor de-
tracts from enjoyment of life. Acceptable concentration levels
that permit attainment of the above requirements have been es-
tablished by the Environmental Protection Agency (EPA, April
30, 1971) for six types or groups of pollutants; namely, car-
bon monoxide, sulfur oxides, nitrogen dioxide, photochemical
oxidants, hydrocarbons, and particulates. The established
concentration levels are given in Table 3-1. For carbon
monoxide the established level is of the order of 10 ppm,
while for the other gaseous pollutants 1t 1s of the order of
0.1 ppm.
The primary standards, in Table 3-1, are the pollutant-
concentration levels considered to be protective of human
health, with a safety margin. These standards are to be
attained in three years starting April 30, 1971. The sec-
ondary standards are more restrictive in regard to sulfur
dioxide and partlculate concentrations and are to be attained
in 27 additional months. These standards are, however, sub-
ject to changes as more knowledge becomes available on health
and welfare effects.
States were required to adopt and submit plans to the
EPA by Jan. 30, 1972, which will maintain and enforce the
Federal ambient air quality standards 1n each air quality-
control region. The regions have been established by the
EPA and were determined on the basis of population, climate,
topography, and geography.
Control District Regulations
The ambient air quality for a given control district
depends on: (1) the amount and type of pollutants emitted
from the combinations of emission sources, and (2) the pre-
vailing meteorological conditions, topography, and geography.
Since the latter vary, sometimes considerably, from one
district to another, the restrictions to be placed on the
pollutant-emitting Industries should also vary to attain the
desired ambient air quality without being unnecessarily re-
strictive. It is also apparent that, for a given set of
meteorological conditions, Increasingly more restrictive
controls would be required on each source as: (1) the number
of sources increase, (2) the number and quantity of reactive-
pollutant emissions Increase.
-------
2-24
Many states, counties and cities have their own air-
pollution laws in addition to the recent Federal regulations.
These local regulations vary to meet the local requirements,*
although many are patterned after those of Los Angeles County
and San Francisco Bay Area. Any person with a pollution
problem should check the local regulations first.
Of specific interest in the control of pollutants from
small emission sources are Rule 66 of Los Angeles County
and Regulation 3 of San Francisco Bay Area. These two rules
or regulations are similar to each other and are concerned
with control of solvent emissions to reduce smog, which is a
particularly difficult-to-correct problem in these two con-
trol districts. However, the smog problem is already pres-
ent in most high population-density areas; hence, the essence
of Rule 66 and Regulation 3 is applicable elsewhere.
To indicate the general context that regulations in
general may have, pertinent portions of Rule 66 are quoted
below as taken from Rules and Regulations, Los Angeles
County Air Pollution Control District, June 18, 1970.
Rule 66a - A person shall not discharge more than 15
pounds of organic materials into the atmosphere 1n any one
day from any article, machine, equipment or other contrivance
in which any organic solvent or any material containing or-
ganic solvent comes into contact with flame or is baked,
heat-cured or heat-polymerized, in the presence of oxygen,
unless all organic materials discharged from such article,
machine, equipment or other contrivance have been reduced
either by at least 85 per cent overall or to not more than
15 pounds in any one day,
Rule 66b - A person shall not discharge more than 40
pounds of organic material into the atmosphere in any one
day from any article, machine, equipment or other contrivance
used under conditions other than described in section (a),
for employing, applying, evaporating or drying any photo-
chemically reactive solvent, as defined in section (k), or
material containing such solvent, unless all organic mater-
ials discharged from such article, machine, equipment or
other contrivance have been reduced either by at least 85
percent overall or to not more than 40 pounds 1n any one day.
Rule 66k - For the purposes of this rule, a photo-
chemical ly reactive solvent 1s any solvent with an aggregate
of more than 20 percent of Its total volume composed of the
chemical compounds classified below or which exceeds any of
the following individual percentage composition limitations.
-------
2-25
referred to the total volume of solvent:
1. A combination of hydrocarbons, alcohols, alde-
hydes, esters, ethers or ketones having an ole-
finic or cyclo-olefinic type of unsaturation:
5 per cent;
2. A combination of aromatic compounds with eight
or more carbon atoms to the molecule except
ethylbenzene: 8 per cent;
3. A combination of ethylbenzene, ketones having
branched hydrocarbon structures, trichloro-
ethylene or toluene: 20 per cent.
Whenever any orqanic solvent or any constituent of an
orqanic solvent may be classified from its chemical structure
into more than one of the above groups of organic compounds,
it shall be considered as a member of the most reactive chem-
ical group, that is, that group having the least allowable
per cent of the total volume of solvents.
Regulation 3 does not include trichloroethylene or ke-
tones having branched hydrocarbon structures.
-------
3. Research and Development Recommendations
Introduction
Under the provisions of Section 103 of the Clean Air
Act of 1970, the Environmental Protection Agency is required
to establish a national research and development program for
the prevention and control of air pollution. As part of such
a program they shall "conduct, and promote the coordination
and acceleration of, research, investigations, experiments,
training, demonstrations, surveys and studies relating to the
causes, effects, extent, prevention and control of air pollu-
tion". The achievement of these broad requirements dictates
that survey studies such as this package sorption device
study provide problem-solving research and development pro-
grams to aid in future planning for governmental action.
A research and development program has been developed
based on the results of a thorough review and evaluation of
the sources and emissions, as discussed in Chapter 1 of Part
I, and control technology relevant to application of package
sorption devices, as discussed in Chapters 4 and 6 in Part II
of this report. Assessment of these results in terms of pres-
ent and future technology needs, priorities, and costs has
resulted in the formulation of specific and relevant research
and development recommendations.
Sources and Emissions
The results of the review of sources emitting noxious,
toxic or smog forming pollutants in the range of flow rates
amenable to control by package devices showed that the majority
of significant emission sources could be assigned to one of two
broad categories: (1) solvent users and (2) chemical, thermal,
or biological processing industries. Data for characterization
of the individual sources within these two broad categories are
far from complete, but, in terms of those parameters necessary
to the selection and design of package control systems, the
solvent user sources and emission are better defined and under-
stood than are the sources in the second category.
Specific problem areas within the solvent user category
that have been identified are primarily related to those sources
which emit dirty, wet, low solvent concentration gas streams,
such as paint spray booths, or which emit pollutants resulting
from thermal treatment applied at some point in the process.
Most solvent emissions may be readily characterized as to
composition by a knowledge of the composition and physical
properties of the original solvent or solvent mixture used.
-------
3-2
It is primarily when chemical changes occur through thermal
processing, such as baking of coatings, printed products, etc,
that emission characterization is lacking. The thermal treat-
ment causes partial decomposition of resins, drying oils and
also of high boiling solvents to the extent that the effluent
emitted can not be predicted or characterized on the basis of
raw material input to the process. Such solvent process
emissions bear similarities to emissions from sources in the
second broad category of chemical or thermal process industries,
such as rendering of meat, poultry, and seafood wastes and by-
products; canning and other food processing; and coffee roast-
ing. The emissions are undesirable by-products of the process
and are complex mixtures which vary widely according to the
type and conditions of processing. To make the best choice of
type and design of control system to be applied, an analysis
of effluent mixture is necessary to determine the molecular
weight range of the gaseous components and type of particulates,
Industry Trends
Certain industry trends are also apparent from the
review of pollutant sources and emissions. These may be
categorized as (1) solvent changes or reformulation, (2)
phase-out of traditional processes, and (3) increase in
application of control systems.
Solvent usage throughout the country has been markedly
affected by the Los Angeles County Rule 66 and its widespread
incorporation into other local and regional legislation. The
result is a growing trend toward decreasing or eliminating
the active photochemical smog precursors from all types of
solvent usage. New, low reactivity solvent mixtures have
been developed which simulate the desirable solvent properties
of previous reactive systems. Branched aromatics and unsat-
urates are being eliminated or replaced. Where feasible,
water base coatings are substituted for solvent systems. New
coatings and printing processes are being developed around
solventless systems and nonthermal curing operations.
The indictment against trichloroethene as a smog pre-
cursor has resulted in widespread use of alternative de-
greasing and metal cleaning solvents, particularly inhib-
ited 1,1,1-trichloroethane. The expense and difficulty in
controlling degreasing emissions and the availability of
substitute solvents will shortly result in the complete
elimination of trichloroethene as a vapor degreasing solvent.
Certain traditional processes and industries are being
nhased-out or are undergoing significant process modifications.
Notable among these are the widespread elimination of open
-------
3-3
burning or backyard incineration of wastes, the replacement
of meat smokehouses by chemical treatments, and reduction of
leather tanning.
Many metropolitan areas have put into effect bans or
limitations on open burning of household, municipal and
industrial wastes, with significant reductions of total
emissions of organic pollutants. These small sources are not
amenable to control and thus complete elimination with sub-
stitution of alternative waste disposal methods is the only
real solution.
The impact of the accelerating trend toward implemen-
tation of existing control technology is difficult to assess
in quantitative terms, particularly as it relates to the
small emission sources. Some indication may be derived from
the organic emission reduction from all stationary sources
achieved by the stringent controls in effect in the major
metropolitan areas of California. According to the 1969
inventory of emissions for the San Francisco Bay Area, the
organic emissions from stationary sources were only about 47
percent of the potential or uncontrolled emissions. Since
many of the organic emission sources under control are within
the purview of this small source study, it may be seen that
implementation of existing control technology can effect
significant reduction in emissions.
The proposed R&D programs are so oriented that they do
not cover pollution problems that are being corrected by
forces or trends already in effect.
Carbon Resorb Systems, Presejrt Technology
The results of the review and evaluation of existing
commerically available package sorption devices for control
of emissions from small sources show that for the areas of
air purification (pollutant concentrations of about 1 ppm
and lower) and solvent recovery (recoverable solvent con-
centration above about 700 ppm), existing control technology
is generally adequate and control devices are available. Of
the devices used in these two areas, the technology which
forms the basis for the solvent recovery type systems is
more amenable to general gaseous air pollution control than
the air purification technology. In order to apply the sol-
vent recovery type systems to the broader application of air
pollution control, modifications are required to the systems
and to their operation. To indicate the broader applica-
tion, these type systems are referred to in this report as
the carbon resorb systems.
-------
3-4
The carbon resorb systems operate on a cyclic pattern
consisting of an adsorption phase and regeneration phase.
During the adsorption phase the gas stream, containing the
pollutant or solvent vapor, is passed through the (granular)
activated carbon bed, usually, until some small amount of
the vapors start to penetrate the bed. The gas flow is then
stopped or diverted to another previously regenerated bed.
During regeneration, a gaseous regenerating agent at elevated
temperature is passed through the bed to desorb the pollutant
or solvent and restore the carbon to its previous capacity
and permit its reuse in the system.
In solvent recovery operations, low temperature steam
is used as regenerating agent because of several desirable
properties. During regeneration a portion of the steam con-*
denses in the carbon bed and releases considerable heat at
212°F, a temperature at which a great majority of pollutants
of interest desorb readily and a temperature which causes
very little or no damage to the desorbing vapor or the car-
bon. The steam and solvent, being condensable, can be readily
separated from each other by decantation or distillation. 3
Carbon resorb systems can be classified into three type$
depending on the manner in which the carbon bed is handled
during adsorption and regeneration. The most commonly used
system utilizes two fixed beds which are alternated between
the adsorption and regeneration phases of the cycle. The
dual fixed bed systems are the simplest of the systems but
are also the bulkiest. The other two systems, the moving b^d
and fluidized bed, move the carbon countercurrent to the gas
phases in both the adsorption and desorption phases of the
cycle. The countercurrent flows increase the carbon and
usage efficiency, resulting in operating cost reductions, t
disadvantages are the more complex and more costly construction
costs of the moving bed type systems and the carbon attrition
losses in the fluidized bed systems.
Carbon resorb systems have been used in solvent recovery
under conditions which are favorable for profitable recovery
of the solvent. Conditions considered favorable are: (1)
clean airstream devoid of participates or containing partlc*
ulates that are easily filtered out, (2) virtually no vapor*
in the airstream other than that of the solvent being recovSk
ed, (3) airstream at low temperature (130°F or lower), (4\T
low relative humidity (below 80%) and (5) (most important)
vapor concentration over 700 ppm but not over 25% of lower
explosive limit.
Carbon manufacturers and solvent recovery system design
engineers have the technical knowledge to work out problems
-------
3-5
associated with recovery of solvents from relatively clean
airstreams having high vapor concentrations. Solvent-laden
airstreams having these qualities are common in a number of
the solvent user industries; namely, degreasing, dry cleaning,
most surface coating, flexographic and gravure printing,
rubber products and paper coating. The main problem is the
coordination of efforts with process machinery designers and
plant layout men to attain the best integrated system and
thereby the most economical control of air pollution from
these emission sources.
Carbon Resorb Systems. New Technology
When conditions and types of pollutant emissions are not
applicable to solvent recovery type operations, the situation
becomes more complex and, also, competing control systems
such as catalytic and thermal incinerators must be brought into
consideration. When the pollutant has no recovery value but
is combustible and is emitted at concentrations higher than
700 ppm, the incinerator systems are more economical to oper-
ate for air pollution control than the carbon resorb systems.
For a noncombustible pollutant the control is of course limited
to the carbon resorb or absorption type systems. At pollutant
concentrations below 700 ppm the new technology on carbon re-
sorb systems is in competitive position with the incinerator
systems for pollution control.
At progressively lower concentrations the use of steam
as regenerating agent becomes increasingly less suitable
while noncondensable inert gas or air at 200° to 300°F, on
ba.sis of theory, shows economic advantages. At low concen-
trations, large amounts of steam are required to maintain a
practical operating capacity for the carbon and it becomes
impractical to separate the pollutant from the large volume
of steam condensate. Use of steam would convert the air
pollutants to water pollutants.
With noncondensable gas regeneration, several econom-
ically feasible procedures have been worked out on sound
engineering principles for the carbon regeneration and sep-
aration or disposal of desorbed pollutant vapors. When the
pollutant vapor is combustible and has no recovery value, it
becomes economical to dispose of it by catalytic or thermal
incineration. In this application the incinerator need be
about one-tenth of the size that would have been required
to incinerate the air initially. If it is necessary or de-
sirable to recover the desorbed pollutant vapor for reuse
(solvent) or disposal by other means, it can be done by
readsorption on a secondary carbon bed or by condensation
-------
3-6
The secondary adsorber would be small relative to the primary
adsorber and could be readily regenerated by the conventional
steam method. When the pollutant vapor is readily condensable,
it can be partially condensed from the hot regenerating gas
by cooling, with the cool regenerating gas being recycled
through the (other) on-stream carbon bed. These conceptual
designs can be incorporated into the fixed bed, moving bed or
fluidized bed carbon resorb systems.
Economic analyses show that the various above proposed
carbon resorb systems are definitely more economical to operate
than catalytic or thermal incinerators of equivalent air hand-
ling capacities for air at near 77°F initial temperature. At
elevated airstream temperatures the incinerators become in-
creasingly more economical to operate and could equal the
carbon resorb systems in operating costs. There is therefore
a definite area in the air pollution control scheme where the
new carbon resorb systems technology should be seriously con-
sidered.
Adsorption Theories
Two theories related to adsorption dynamics have been
advanced which can greatly facilitate development of the carbon
resorb systems new technology for pollution control. (Chapter
4)
One of these is the Polyani potential theory which can
be used to calculate the adsorptive capacities of carbons
for various homologous series of molecules as function of
temperature, molecular size and concentration.
The other theory involves mass transfer of vapor from
the airstream to carbon and into the pores of the carbon.
On the basis of mass transfer theories Klotz developed an
equation which can be used to calculate the mass transfer zone
or adsorption zone length in the bed. The controlling para-
meters are: air density and viscosity, carbon particle size,
airflow velocity, diffusion coefficient of vapor in air, and
ratio of vapor influent concentration over vapor concentration
within the bed.
The effective use of either equation requires minimal
data on adsorptive capacities and adsorption rates on the
particular carbon and homologous series of the pollutant or
pollutants under consideration. Data that would be useful
for this purpose, particularly from the problem areas of
pollution control, are lacking or are not in a form suitable
for use by the engineer that would do the development and/or
design of the control system.
-------
3-7
Monitoring Instruments
In solvent recovery operations the instrumentation re-
quirements for monitoring are not complex. The solvent, the
rate of emission, and concentration are known to a fair degree
of certainty permitting the installation of optimum size and
design of carbon resorb system for the particular emission
source. The adsorption-regeneration cycles are preset and
automatically controlled at short and equal time intervals.
A comparison of solvent recovery with the solvent input wi11
give a measure of the efficiency of the recovery operations.
Simple instruments such as a manometer and temperature re-
corders are used to determine the time for particulate filter
change and to check the air inlet temperature and temperature
profiles during adsorption and regeneration.
In the problem areas of pollutant control, the emissions
can be quite variable in quantity and type. The adsorption
phase time can therefore vary considerably. Monitoring in-
struments are highly desirable to avoid overrun or large
underrun on the adsorption phase. The instruments for this
purpose should be simple and durable in construction, low
cost, and readily understood and operated by plant operating
personnel.
Chapter 8 describes techniques and instruments that show
suitability for monitoring of pollutant vapor concentrations.
Some have capabilities for identifying pollutant vapors.
Much of the available instrumentation are too expensive and
also require technically trained personnel for their oper-
ation.
Research and Development Programs
Specific programs resulting from the identification of
needs and priorities are described below. Study priority is
based on three relative classifications: high; medium; low.
Estimated cost is based on a nominal $50,000 per man-year
unless unusually high materials or construction costs are in-
volved. For the latter cases, estimated costs of such mater-
ials or construction are added.
The recommended programs are divided into four areas of
study:
Emission and Source Characterization
Evaluation of New Adsorbent Systems
Generation of Adsorption and Regeneration Data
Monitoring Instrument Development
-------
3-8
Emission and Source Characterization
Objective - To provide detailed chemical and engineering
data necessary for the selection and design of optimally effec-
tive control systems.
Approach - Pollutant sources recognized as being partic-
ularly difficult to control due to low (below 700 ppm range)
pollutant concentration, highly odorous nature, presence of
aerosols or particulates, and presence of difficultly adsorbed
species would be investigated in detail. Specific tasks v/ould
include problem emission source selections, field testing of
emissions, engineering evaluation of overall process with
determination of process flows and point sources, and process
modification required to make the most effective use of a
potential control system.
The data obtained on some sources may clearly define the
best choice of system, i.e., catalytic incineration, thermal
incineration, liquid absorption, or carbon resorb. Further
study to determine the best suited type and optimum size of
system may be minimal and done with readily available infor-
mation. It is foreseeable that commercially available carbon
resorb systems may be suitable for some applications. If the
emission and source characterization data do not indicate a
clear choice of competing system and also leaves best choice
of carbon resorb system in doubt, further investigation as
prescribed under the program to Evaluate New Adsorbent Systems
is required.
Priority, Duration, Effort and Cost - This program was
assigned a high priority rating since characterization of the
emission source is absolutely essential before a logical pro-
cedure can be planned for its control.
The number of point sources of emissions is large with
new ones appearing as new products and processes are developed
and old ones phased out as they become obsolete. It is fore-
seeable that many sources will be quite similar, and the
characterization of one will essentially characterize the
others. This pattern will reduce the number of investigations
that need to be made to a limited number of the more critical
ones. It is difficult to assess with any certainty the number
of critical sources existing. The difficulty of character-
ization also varies, but with a well equipped laboratory and
trained personnel the cost per source can vary from $5,000 to
$15,000 each. The characterization would be carried only to
the degree required for control system selection and to estab-
lish design, size, and operating procedure. It is quite
certain that a minimum of 10 sources would require character-
ization and it appears improbable that the number would rise
much above 30.
-------
3-9
Ten sources would require about 3,800 man hours at a
cost of $100,000 to be performed in less than one year.
A more extended program of systematic characterizations
and including possible new sources would increase cost and
time. At some point in time the need for further studies
would diminish and if 30 sources is arbitrarily set as max-
imum the man hour requirement would be 11,400 to be performed
over a five year period at a cost of $300,000.
Evaluation of New Carbon Resorb System
Objective - To evaluate, technically and economically,
potentially promising or incompletely proven carbon resorb
systems and to demonstrate feasibility of the selected system
for control of pollutants emitted from specific sources of
the type studied under Emissions and Source Characterization.
Approach - On the basis of data obtained from the
Emission and Source Characterization study or from other
sources, the first step of the program would be to determine
whether a carbon resorb system should be used, and, if so,
which type. Systems that are of foreseeable interest are
briefly described as follows:
Dual stationary beds for adsorption phase, regen-
eration with hot noncondensable gas, and dis-
posal of desorbed vapors by catalytic or
thermal incineration.
Dual stationary beds for adsorption phase, regen-
eration with hot noncondensable gas, readsorp-
tion of desorbed vapors in small secondary
adsorbed and ultimate recovery of vapors by
conventional steam regeneration.
Dual stationary beds for adsorption phase, regen-
eration with hot noncondensable gas, recovery
of vapors from regeneration gas by condensation.
Alternatives for each of the above three systems
would be the use of moving carbon bed or
fluidized carbon bed.
Polar adsorbent systems (for low molecular weight
polar vapor).
-------
3-10
In order to make the choice of system, some fundamental
adsorption studies may be required (laboratory scale) to
obtain additional data for the calculation of adsorptive
capacities, adsorption zone lengths, carbon bed sizes, service
times, regenerabi1ity, and regeneration gas requirements. On
the basis of all of the acquired information, several models
of carbon resorb systems would be designed that appear techni-
cally and economically attractive. From the theoretical per-
formance of the best model, when compared to performances of
incinerators, a decision is then made whether to continue
further to demonstrate feasibility of the system under test
condi tions.
If a system demonstration is indicated, the second step
would be the construction or assembly of a pilot sized system,
which would be tested in the contractors pilot plant or under
actual conditions in industry. The choice of location would
be determined by several factors. If the operating conditions
can be reproduced in a pilot plant, the pilot plant would be
the preferred location since the tests can be better con-
trolled to yield data that can be treated theoretically.
Spray painting operations would be an example of this type.
A pilot plant location would be preferred when the study
involves vapors in the explosive concentration range, as would
be the case of emissions from gasoline storage. When the vapor
emission conditions cannot be reproduced in the pilot plant, as
would the case with pollutants emitted from a rendering plant,
the preferred location is the plant of the industry emitting
the pollutant.
Priority, Duration, Effort and Cost - This program was
assigned a high priority rating since it involves the basic
objectives of the package sorption study.
About 5,000 man hours over a one year operating time
would be required to test a control system. The estimated
cost would vary between $135,000 and $145,000 when equipment
costs vary between $10,000 and $20,000. Equipment costs at
this level would limit test control systems to airflow
capacities of less than 2,000 ftVmin.
The size of the program depends on the number of system
tests that are deemed necessary to get adequate information
on feasibility of carbon resorb type systems for pollution
control. Four industries that should receive top priority
for control study are: meat rendering, fish rendering, spray
coating and petroleum distillate evaporation. For a limited
study (million dollar total program level), these four should
receive first consideration. It may become necessary to test
more than one design of carbon resorb system at each of the
-------
3-11
emission sites, in which case more than four systems would be
tested. For a four system study at $140,000 each, the total
cost would be $560,000, The systems can be tested simultan-
eously or extended over four years.
Depending on the results of the first four systems
studied, the program may be discontinued or extended to in-
clude other emission sources such as waste water treatment,
soap manufacture, restaurants, baking, plywood manufacture,
azo-dye manufacture, crematoria, hospital exhausts, etc. The
program will ultimately reach a point of diminishing returns
where the results of previous tests are translatable to new
situations and no further testing is economically justifiable.
The point at which further testing is not justifiable is
difficult to determine, but it is believed that at the level
where control systems for 12 or 13 emission sources of varied
types have been tested the point of diminishing returns has
been reached.
For 13 systems at $140,000 each, the total cost would be
$1,820,000.
Generation of Adsorption and Regeneration Data
Objectives - To generate adsorption and regeneration data
in forms readily usable by the carbon resorb systems design
engi neer.
Approach - The recommended research program to obtain
and compile these data would consist of laboratory scale
studies conducted under gas flow rates of the order of 0.1
to 0.4 cubic feet per minute and carbon bed diameters of
one-half to one inch. These conditions are sufficient to
give the necessary data without excessive expenditures in
time or equipment.
Due to the large number of pertinent parameters and their
permutations to be investigated in this proposed program, care-
ful utilization of statistical experimental design procedures
would be employed. The pertinent variables and suggested
levels of experimentation for each variable are shown below:
Variable Levels
Carbon type 2 - significantly different
pore structures (source
of carbon)
-------
3-12
Variable
Levels
Pollutant type
Pollutant concentration
Gas velocity
Bed depth
Mesh size
Temperature
Humidity
3 levels for each homologous
series or chemical group
classification of interest
3 - 10, 100 and 1000 ppm
3 - 20, 60 and 100 ft/min
3 - longer than adsorption
zone
3 - 4 to 6, 6 to 10 and 10
to 30 mesh
3 - 25°, 50° and 100°C
Spot checked only, little
expected effect
Regeneration runs with a noncondensable gas (nitrogen) would
be conducted at two temperatures on carbon beds spent with
various pollutants at the varied concentrations as indicated
above. Also repeated cycles will be carried out. About
forty regenerations are foreseeable.
The product of the study would be tables, graphs, equa-
tions and procedures for calculating adsorptive capacities,
operating capacities, adsorption zone lengths, and regenerating
agent requirements. These results would be further utilized
for estimating carbon bed dimensions, service time, adsorption-
regeneration cycle timing and frequency and for determining
effective disposal techniques for the pollutant.
Priority, Duration. Effort and Cost - This program was
assigned a medium priority rating since the information it
would yield would be used primarily to expedite the progress
in the program to Evaluate New Carbon Resorb Systems. In the
latter program adsorption and regeneration data, if required,
would be experimentally determined specifically for each
pollutant emission source. This procedure would be less
efficient, more costly, and produce Information that would be
limited in regard to general application than if a systematic
study were conducted as proposed here.
-------
3-13
To attain a fairly complete coverage of parameters,
homologous series of compounds, and carbons, the program would
require 15,200 man hours of effort over a 3-yr period. Con-
siderable instrumentation is required since some adsorption
phases of the experiments would be run continuously over ex-
tended periods with continuous monitoring of the effluent gas
stream. The instrument and other equipment costs come to
$20,000. The total cost would be $400,000.
Some phases of the program are more important than others
and the study of some homologous series of compounds are more
pertinent to problem areas in pollutant control than others.
On the basis of priorities in this respect, the three year
overall program can be divided into three one-year programs.
The first year's program, however, would be the least produc-
tive since it includes a considerable lag time for the pur-
chase and installation of the instruments, adsorption and
regeneration systems. It includes 16 weeks equipment instal-
lation period followed by 36 weeks of experimental work and
final report preparation. The nan hours would be 4,500 at a
cost of $130,000, including the $20,000 for instruments and
equipment. A two-year program would be an expansion of the
one-year program with considerably larger portion of the esti-
mated 9,800 man hours assigned to experimental work. The cost,
including instruments and other equipment, would be $265,000.
Monitoring Instrument Development
Objective - To develop effective and relatively inexpen-
sive methods for monitoring the operation of package sorbent
devices.
Approach - Three promising areas of monitoring instrumen-
tation research and development have been preliminarily explored
and recommended for further study. These are:
1. Indicator Tubes - Development of chemical indicator
methods for detecting breakthrough or monitoring of service
life of carbon sorption systems. This area of research and
development would rely heavily on the extensive work already
done in the development and application of selective and
specific indicator tubes for a wide variety of both organic
and inorganic air contaminants.
2. Sorption and Incineration Devices - Development of
monitoring devices applicable to organic contaminant control
by either carbon sorption or incineration systems, based on
the principle of the catalytic CO indicator, widely used
in vehicular tunnels and other areas having significant
potential for hazardous CO concentration build-up. The
-------
3-14
catalyst used in these indicators, Hopcalite, is an
effective oxidation catalyst for not only CO but hydro-
carbons. Thus, the presence of hydrocarbons in the
control system exhaust could be detected by a temperature
increase of an adiabatically operated Hopcalite catalyst
bed. A steadily increasing temperature difference be-
tween the Hopcalite bed and the effluent airstream would
indicate pollutant penetration.
3. Stack-Gas Samplers - Development of a simple
stack sampling device by which, periodically, the control
device users could collect samples to be quantitatively
analyzed at a centrally located analytical laboratory.
Such a device could be similar to those used by industrial
hygienists in collecting work room air samples for sub-
sequent analysis, which use a small carbon canister and
hand pump to collect and retain air contaminants. Alter-
nately, such sampling canisters could be integrally in-
stalled as part of the control system and would be
periodically removed and sent for analysis.
Priority, Duration, Effort and Cost - This program was
assigned a medium priority since the need for the relatively
inexpensive monitoring methods would not arise until operational
control systems have been developed, i.e., results of the pro-
gram to Evaluate New Carbon Resorb Systems.
This study is expected to require 12,500 man hours over
a 2-yr period at a cost of $375,000.
The contract specified the development of two 5-year
programs, Plan A and Plan B, based on assumed total ex-
penditures of $1 million and $5 million, respectively. The
various programs as described above have been grouped into
Plan A of $1 million total expenditure and Plan B of $3
million total expenditure as shown in Tables 3-1 and -II,
respectively. An expanded plan of $5 million was not fore-
seen.
-------
Table 3-1 Summary of One Million Dollar Research and Development Plan (A)
Program
Emissions and Sources
Character!zation
(30 sources at $10,000
each)
Evaluation of New
Adsorbent Systems
(4 systems at $140,000
each)
Generation of Adsorption
and Regeneration Data
Total
Cost,
$
300,000
Time schedule, yr
560,000
130,000
990,000
_L_ 2 3 4 5 Priority
^> high
high
medi urn
t*>
I
en
-------
CO
I
Table 3-II Summary of Three Million Dollar Research and Development Plan (B)
Program
Emissions and Sources
Characterization
(30 sources at $10,000
each)
Evaluation of New Adsorbent
Systems
(13 systems at about
$140,000 each)
Generation of Adsorption
and Regeneration Data
Monitoring Instrument
Development
Total
Cost
$
300,000
1,820,000
400,000
375,000
2,895,000
Time schedule, yr
12345 Priority
-v hi nh
> medium
-------
Part II
Package Sorptlon Device Technology Handbook
-------
Introduction to Part II
This part of the report presents the results of the
investigations and analyses of the packaged systems that are
or could be used for control of air pollutants from those
emission sources discussed in Chapters 1 and 2. Although
this study was primarily concerned with sorbent systems, the
competing systems - catalytic and thermal incinerators - are
also discussed in order to place each system in proper per.
spective in regard to its effectiveness and operating cost.
Chapter 6. Package Sorption Systems, is the most Import*
ant chapter of Part II. In it are discussed (1) the present
sorbent systems technology, (2) the new developments and
proposed systems that show promise for pollutant control and
(3) the operating costs of the various systems. Under present
systems technology, systems are considered that are In wide
commercial usage or have been proven over a number of years
of successful operation. Under new technology, systems are
considered that have appeared very recently in commercial
usage but have not yet acquired wide spread acceptance or
systems that have been engineered on theoretical basis but
have not been tested or tested on a very limited pilot plant
scale.
Since one of the important objectives of the study was
to assess potential new technology to control pollution,
Chapter 6 was written against a theoretical background. A
theoretical understanding of the adsorption and regeneration
processes permits a ready extension of the operational know-
ledge on known systems toward the design of new systems for
control of pollutants emitted under new and more difficult
circumstances. Chapter 4 was written to supply this 1nfor«.
mation in considerable detail. Chapter 5 is a considerably
more condensed review of catalytic combustion theory.
Chapter 7 presents a brief .study of catalytic Inciner-
ation to augment the more extensive study of sorbent systems
When the new systems become(commercial, the need for new
testing and control instrumentation is foreseeable. Chapter 8
describes basic concepts suitable for pollutant identification
and concentration measurements.
-------
4, Sorbent Types and Sorption Theories
Sorbent Types
Important Sorbent Properties
Sorbents differ considerably from each other in their
selectivity, or preferential adsorption, and their adsorptive
capacities. These two factors can vary the suitability of a
sorbent for air pollution control usage, limiting some for
special conditions, while others are generally applicable.
The selectivity and capacity are dependent on four properties
of the sorbent. These are:
1, Chemical constitution of the sorbent, partic-
ularly the surface,
2, Extent of the surface area,
3. Pore size distribution,
4. Particle, or granule, size.
The term "sorbent" includes two types of solids (1) those
that concentrate vapors on the free surface by "adsorption",
and (2) those that concentrate vapors by "absorption", wherein
the vapor molecules penetrate into the mass of the sorbent
solid. Penetration of hydrogen into palladium metal lattice
is an example of the latter. At present, the absorption pro-
cess in solids (to differentiate it from liquid absorption)
does not appear to play any role in the control of pollutant
emissions of the type discussed in Chapters 1 and 2.
On the basis of chemical constitution and pore size dis-
tribution, adsorbents can be grouped into four different types.
They exhibit greatly different selectivities for vapors and
differences in manner of adsorption. The types are:
1. Chemically reactive adsorbents,
2. Polar adsorbents*
3. Nonpolar adsorbents,
4. Molecular sieves.
The differences in adsorptive behavior of the first
three are primarily due to differences in chemical constitu-
tion of the solids, with secondary differences contributed by
-------
4-2
extent of surface area and pore-size distribution. The molec-
ular sieves can be either polar or nonpolar» but their dis-
tinctive adsorptive behavior is due to the small size of the
pores which physically block entry, of oversized molecules.
Chemically Reactive Adsorbents
When adsorption of vapors is accompanied by a chemical
reaction, the process is defined as "chemisorption". It has
a number of well defined characteristics which are enumerated
below:
1. It is highly selective; not all vapors react
with all adsorbents.
2. It tends to be Irreversible.
3. The rate Increases with rise in temperature.
4. The heat of chemisorption is of the same magnitude
as that of chemical reactions, usually over
10 kcal/mole.
5. The process is exothermic.
6. Chemisorption stops when all of the active sites
on the surface have reacted, or the surface is
covered with a unimolecular layer of chemisorbed
vapor.
Examples of chemisorption, which have been intensively
studied by various investigators, are hydrogen on heated
metals, oxygen on heated tungsten, carbon monoxide on iron
catalysts, nitrogen on nickel and iron, and ammonia on alumi-
na (Langmuir, 1912 and 1916; Emmett, 1937; Beeck, 1950; Webb,
1957). Chemisorption of oxygen on carbon is well known. At
higher temperatures, it is one of the steps in carbon acti-
vation; i.e., H20 vapor and C02 react with carbon to form an
oxygen surface complex which later breaks up by releasing CO.
Inorganic acid vapors react readily with transition metal
oxides. When the active metal oxides are used to catalyze
pollutant incineration, chemisorption of add vapors plays an
adverse role by causing catalyst poisoning. Conversely, chem-
isorption on reactive metals is a potential process for purify.
ing air of traces of halogen acids and $03.
Soda lime by itself, or in combination with activated car-
bon is used to chemisorb vapors such as ethanoic acid, ethane-
nitrile, propenenitrlle, 3-chloro-propene, ethenyl propyl
dlsulflde, chlorine, cyanogen, fluorine, hydrogen bromide,
-------
4-3
hydrogen chloride, hydrogen fluoride, and hydrogen sulfide.
Several of these vapors have been identified with the rubber
products and rendering industries.
In the chemically reactive adsorbent
impregnated polar and nonpolar adsorbents
pregnant reacts chemically with the vapor
initial physical adsorption has occurred.
impregnant-adsorbent combinations and the
which the impregnant is reactive.
oroup are also the
wherein the im-
molecule after an
Table 4-1 listed
vapor molecules to
Table 4-1 Types of Impregnated Adsorbents
Impregnant-adsorbent Pollutant vapor
Bromine-carbon
Iodine-carbon
Phosphoric acid-carbon
Potassium permanganate-
activated .alumina
(Purafil)U)
Cupric oxide-carbon
Cupric oxide-pentavalent
chromium on carbon
G-32E-treated activated
carbon(2)
Ammonia-molecular sieves
Copper-activated
alumina (8.4 wt
Sulfur acid-carbon
(20 wt *)
ethene
mercury, radioact. iodine
ammonia
low molecular wt
mercaptans,
organic acids
olefins
carbonyl chloride
(phosgene)
cyanogen chloride
hydrogen cyanide
.carbonyl chloride
sulfur compounds
hydrogen sulfide
carbonyl sulfide
mercaptans from
hydrocarbon gases
carbon dioxide
hydrogen sulfide
mercaptans
.carbon disulfide
sulfur dioxide
thiophenol and
similar compounds
(1) Marbon Chemical Division, Washington, West Virginia
(2) Chemetron Corporation, Catalyst Division,
Louisville, Kentucky
-------
4-4
Polar Adsorbents
When adsorption is not accompanied by chemical bonding,
the active forces are referred to as van der Waal's forces
and are the same as those that bind liquids and solids. This
type of adsorption is also referred to as physical adsorption
and occurs on chemically nonreactive adsorbents having polar
or nonpolar surface properties.
Physical adsorption varies from chemisorption 1n several
respects In that:
1. It is less selective.
2. It is reversible.
3. The heat of adsorption is of the order of 10 kcal/
mole.
4. Adsorption can continue beyond the unimolecular
layer surface coverage.
5. The amount adsorbed decreases with increasing
temperature at a fixed vapor pressure.
Examples of polar adsorbents are silica gel, activated
alumina, fullers earth, bentonite, and the zeolite type of
molecular sieves. Of these, fullers earth and bentonite are
usually used for liquid phase adsorption processes; the other
three are used in gas separation and purification processes.
The chemical make-up of these adsorbents consists of
silicon oxide and/or aluminum oxide groupings which impart a
highly polar character to the surface. Silica gel is essen-
tially pure S10? with less than 0.3% of other metallic oxide
impurities. Activated alumina is over 9Q% pure A^Oj with
other metallic oxides as impurities making up the balance.
Zeolites are alumino-silicate crystalline structures contain-
ing sodium, potassium or calcium cations.
The polarity of the surface has been found to produce
strong affinity to polar vapor molecules or vapor molecules
that are readily polarized, such as olefins. Table 4-II lists
a number of air pollutants in decreasing order of affinity on
silica gel (Trappe, 1940) which shows the effect of physical
properties of the pollutants, particularly the dielectric
constant and dipole moment, on the adsorption affinity. Ex-
cept for a few variances, the affinity decreases with de-
creasing dielectric constant and decreasing dipole moment.
In contrast, the affinity tends to decrease with Increasing
V and van der Waals' constant a_; for definition of van
der Waals1 a, see Appendix D. The latter trend
-------
4-5
Table 4-II Effect of Pollutant
Adsorpti
Order of
Pol lutant
Water
Methanol
Ethanol
1-Propanol
Propanone
Ethyl acetate
Ethyl ether
Tri chloromethane
Di chloromethane
Benzene
Toluene
Tetrachlorome thane
Cyclohexane
Hexane
ve Affinity
Physical Properties on
for silica
Gel Decreasing
Affinity Downward
Dielectric
constant
at 67°F
81.0
31.2
25.8
22.2
21.5
6.1
4.4
5.2
9.1
2.3
2.3
2.2
2.0
1.9
Dipole
moment
x!0ieesu
1.85
1.73
1.70
1.65
2.89
1.74
1.15
1.02
1.54
0.00
0.36
0.00
0.2
0.00
v
cmVmol
18
42
61
84
74
106
106
83
65
95
118
101
118
140
van der
Waals1
a x 103
11
19
24
30
28
41
35
30
36
48
40
43
49
contradicts the concept of active van der Waals1 forces when
dealing with polar adsorbents. Adsorptive affinity on non-
polar adsorbents
sfib'wn in the next
correlate
section.
with van der Waals1 a.as will be
The strong affinity of polar adsorbents for water great-
ly limits their general use in air pollution control, they
are used for drying of various gases; some are listed below:
Ammonia
Argon
Butane
Carbon dioxide
Chlorine
Ethane
Ethene
Freons
Helium
Hydrogen
Hydrogen
Hydrogen
Methane
Nitrogen
chloride
sulfide
Oxygen
Propane
Propene
Sulfur dioxide
When the gas stream is free of water vapor, polar ad-
sorbents are suitable for pollution control involving small
polar molecules such as:
Ammonia
Dichloromethane
Hydrogen chloride
Methanal
Methanol
Sulfur dioxide
Hydrogen sulfide
-------
4-6
In each case the pollutant can be desorbed with a relatively
small amount of water, after which the polar adsorbent can
be dried at elevated temperature and put back Into use.
Nonpolar Adsorbents
Activated carbon 1s the primary example of a nonpolar
adsorbent. Others are possible such as metallic surfaces,
but the surface areas attainable with the latter are too
small to be useful for gas or air purification.
Physical adsorption on nonpolar and polar adsorbents
differ primarily in selectivity, or differences in affinity,
for different molecules, Qji nonpolar adsorbents adso-rptiste
af f 1 n 1 ty increases with molecular size and yjn der WaaJ.5 '
cjjis_iant_j^."*'"In'"TabYe"4"-ni tins Is shoM *w1 tTTTeveTPhydro-
carbons, which are listed downward in increasing order of
adsorptive affinity on activated carbon (based on data of
Ray, 1949). The correlation of Vm with amount adsorbed has
been worked in with the Polanyi potential theory to derive
an equation for calculating the amount of adsorption of var-
ious pollutants at varied vapor pressures and temperatures.
This equation is discussed under the theoretical part of
this chapter.
By impregnating activated carbons, polar adsorbent and
chemically active adsorbent properties can be imparted to
Table 4-III Effect of Pollutant Physical Properties on
Adsorptive Affinity for Activated Carbon
aFlOO"Ft Increasing Order of Affinity Downward
Amount adsorbed
at one atmosphere Vm, van der Waals
Pollutant pressure. cmMiq./q cnrliq./mol a x 103
Methane
Ethyne
Ethene
Ethane
Propene
Propane
Butane
them. Activated carbons generally contain ash, such as S10*,
AlgOa, Fe203, NaOH, KOH and chemisorbed oxygen, all of which
0.03
0.11
0.14
0.20
0.31
0.36
0.43
30
37
44
52
67
74
96
4.5
8.7
8.9
10.7
16.7
17.3
28.8
-------
4-7
impart polar properties. By leaching out the ash followed
by hydrogen reduction, a wholly nonpolar carbon can be ob-
tained. Adsorption of water vapor at low vapor pressures is
very sensitive to the presence of polar impurities. Acti-
vated carbons that have not been specially treated are poor
adsorbents for water and can be desorbed by most of the or-
ganic pollutants emitted from the small sources.
Molecular Sieves
Molecular sieves are available having polar or nonpolar
surface properties. The polar molecular sieves are complex
crystalline structures consisting of basic units or tetra-
hedra of (AT, Si)04. The silicon atom is electrically bal-
anced by the four oxygen atoms of the lattice, but the alumi-
num atom, with a valence of three, is not. For every alumi-
num atom in the lattice, a monovalent (or equivalent) cation
is required to attain electrical balance. The cations used
are Na, K, and Ca.
When first manufactured, the crystalline structure con-
tains water of crystallization, which is removed by heating
to temperatures above 570°F. The removal of the water leaves
a porous solid consisting of a network of cavities inter-
connected by round pores of smaller diameter. The cavity and
pore diameters are uniform; hence, a pore-size distribution
in the usual sense as applied to silica gel, activated alumina
and activated carbon has no significance in molecular sieves.
The manufacturers of polar molecular sieves (Linde.
Davison) designate over four different types of sieves. A
group A has 11.4 A cavity diameter, a 1 to 1 Al to Si ratio
and is designated as simple cubic crystalline structure. A
group X has a 1.0 to 1.25 or 1.5 Al to Si ratio and is desig-
nated as body-centered cubic crystalline structure. By
changes in Al to Si ratio and type of cation, the pore dia-
meter can be varied over the increments 3, 4, 5, 8 and 9 A.
In each case only molecules having critical dimensions small-
er than the nominal pore size can be adsorbed. Table 4-IV
lists the types of Linde molecular sieves and their general
chemical formulas; those of Davison are quite similar. Table
4-V also gives the nominal pore diameters and lists some of
the pollutants that can be selectively adsorbed by each type
of molecular sieve, as determined by the critical dimensions
of the molecule. For a given molecular sieve, those molecules
listed under sieves of larger pore diameter are screened or
°f
-------
4-8
Table 4-IV Types of Molecular Sieves
Type General formula, molar ratios
3A 0.72 Na20 : 0.24 K20 : 1.00 A1203 : 1.92 S102 : 2H20
4A 0.96±0.04Na20 : 1.00 A1203 : 1.92 ± 0.09 Si02 : xH20
5A 0.72 Na20 : 0.24 CaO : 1.00 A1203 : 1.92 S10 : 2H20
10X 0.62 N20 : 0.21 CaO : 1.00 A1203 : 2.48 S102 : xH20
13X 0.83±0.05Na20 : 1.00 A1203 : 2.48 ± 0.03 S102 : xH20
Superimposed on the sieving action of these adsorbents
is the strong affinity for small or highly polar molecules;
see discussion under Polar Adsorbents. As was the case with
silica gel and activated alumina, the strong affinity of
molecular sieves for water greatly limits their uses for
pollution control. In a dry alrstream, the molecular sieves
are more effective for the adsorption of low molecular weight
polar or unsaturated pollutants at low concentrations than
silica gel, activated alumina or activated carbon. Results
presented below, as reported by Gustafson (1961), show this
difference in the adsorption of ethene and ethyne at 77°F
and 20 mm of Hg pressure.
Amount adsorbed. % by weight
Gas 4Tsilica geTactivated carbon'
Ethene 6 1.75 2.5
Ethyne 7 1.5 1.8
The adsorption of low molecular weight saturated hydrocarbons
such as methane and ethane are more strongly adsorbed by car-
bons than by molecular sieves, but too poorly in any case to
be used effectively in pollution control. Activated carbons
will have a much lower equilibrium capacity for organic com-
pounds at low partial pressures than 13X; but at high par-
tial pressures! activated carbon adsorptlve capacity is two
to three times that of 13X. Molecular sieves adsorb NOX
gases at high relative humidities with about 5 wt % pick*
up at concentrations in the 1,000 to 2,000 ppm range (Sun-
daresan, 1967).
Molecular sieves are readily regenerated by passing
water vapor or liquid water through the sieve bed and the ad-
sorbed water.in turn, 1s readily removed by heating the bed
to 570°F.
-------
4-9
Table 4-V Effect of Molecular Sieve Pore Diameter nn
selective Adsorption of Pollutan
Sieve type and Cri
pore diameter, Jl Pollutant DO!
10X
8*
&-
13X
9*
[3A J Ethyne
3A J Carbon monoxide
A A W
4^ Water
Ammonia
[ Hydrogen sulflde
5A_ Ethene
5^ Ethane
Methanol
Ethanol
Methanethiol
Propane
Butane to
L C22H46
Propene
Ethanethlol
1-Butene
2-Butene
1 ,3-Butadiene
Isobutane to
1 s o C22^46
Cyclohexane
Benzene
Toluene
p-Xylene
Tetrachlorome thane
Trichloromethane
m-Xylene
o-Xylene
Triethylamlne
t Vapors
tical diameter of
lutant molecule, A
2.4
2.8
3.2
3.6
3.6
4.2
4.4
4.4
4.4
4.5
4.9
4.9
5.0
5.1
5.1
5.1
5.2
5.6
6.1
6.7
6.7
6.7
6.9
6.9
7.1
7.4
8.4
In recent years (since 1969) developmental work has been
done on carbon molecular sieves. Because of nonpolarity of
the surface, these adsorbents would have no greater affinity
for small polar molecules than for nonpolar molecules Pre-
ferential adsorption for small organic molecules can be ex-
pected in the presence of moisture. Pittsburgh Carbon Com-
pany, Division of Calgon Corporation, has developed a carbon
molecular sieve which shows very little adsorption for tetra-
chloromethane but considerable adsorption for Iodine Th*
pore openings appear to be slit or rectangular shane* nf
critical dimension in the 5.0 to 5.5 X range P
-------
4-10
Because of attractive forces from adjacent and opposite
pore walls, such pollutants as ammonia, hydrogen sulfide and
possibly methanethlol can be expected to be adsorbed more
strongly than on conventional carbon. As with polar molecu-
lar sieves, the sieving action can be utilized for separation
of molecules of differing sizes.
Cooper (1970) describes a platinum-carbon catalyst having
molecular-sieve properties. The platinum is incorporated
into the carbon structure during the molecular sieve prepara-
tion. With these catalytic-carbon sieves, hydrogenatlon of
linear olefins can be carried out because of their penetra-
tion into pores while branched olefins are not hydrogenated.
Effect of Physical Properties on Adsorption
Rhysical Properties - The chemical constitutions of the
adsorbents, as discussed in the previous text, form the basis
for classifying the adsorbents into three types: the chemi-
cally reactive, polar and nonpolar. A fourth type, decided
primarily on pore structure, is the molecular sieve which 1n
chemical constitution can also be classified polar or non-
polar.
The physical properties such as surface area, pore size
distribution, pore volume, granule or particle size and den-
sity determine the adsorptlve capacity, adsorption rate and
resistance to flow of the pollutant-air mixture through the
adsorbent bed. These properties are very frequently pre-
sented in sales literature to indicate the quality of the
adsorbent being sold. Tables 4-VI and -VII Riresjnt ranges
of most of these physicaT"|fn;FpliTtleT^^
EjOBBA gels, acUvmd: aTMinas., ;4MH|ilZcirr^|^^d
molecular sieves. Comparative data for chemicaTTy" reactTve
adsorbents were not available and would not have the same
significance since chemisorptions are very specific.
To further define the adsorptive qualifications, sales
literature presents adsorption isotherms and/or adsorptive
capacity data at varied conditions for various vapors for
which the adsorbents are recommended. For polar adsorbents
and polar molecular sieves, the graphical presentation of
the water adsorption isotherm or adsorptive capacities at
varied relative vapor pressures are usually the first ad-
sorptive capacity data given. For activated carbons the
iodine number is most frequently given if the intended use
is in aqueous phase. When the intended use is in gas phase,
it is the carbon tetrachloride (tetrachloromethane) activity.
The carbon tetrachloride activity is the weight percentage
adsorbed at 40°F and 0.16 relative vapor pressure. Details
of this test are given 1n Appendex D.
-------
Table 4-VI Physical Properties of Adsorbents. Surface Areas and Pore Volumes
Adsorbent
Surface area
Silica gel
Activated alumina
Activated carbon
Molecular sieve
m'/q
750
210
600
to
to
360
1600
520
210 to 320
300 to 560
Pore volume
0.
0.
0.
0.
40
29
80
27
cm*/
to
to
to
q
0.
1.
0.
37 est
20
38
0.
0.
0.
0.
28
29
40
22
cm*
to
to
to
/cm
0
0
0
3
33
42
30
est
Table 4-VII Physical Properties of Adsorbents, Densities and Mean Pore Diameters
Adsorbent
Silica gel
Activated alumina
Activated carbon
Molecular sieve
Bulk density, Particle density, True density,
g/cm3 g/cm3 g/cm3
0.70
0.90 to 1.00
0.35 to 0.50
0.80
1.2
1.5 to 1.7 est.
0.60 to 0.80
1.40
2.20
3.30
2.20
2.3 to 3.3
Mean pore
diameter, A
22
18 to 20,..
15 to 20<]'
3 to 9
-Q
(1) Carbon pore structure consists of two pore size ranges, (1) those over 30 A
diameter termed macrooores, and (2) those less than 30 A diameter termed micro-
pores. The 15 to 20 A mean diameters are for the micropores only; 95% of the
surface area is associated with them.
-------
4-12
Surface Area - In the adsorption process, the pollutant
molecules in the gas phase are attracted to the adsorbent
surface initiating a unimolecular layer of molecules which
can spread until complete surface coverage is achieved. This
is definitely the case with chemisorption. When adsorption
occurs by van der Waals1 forces, multilayers of molecules
can form after completion of the unimolecular layer, or
sooner if other factors are active. Other factors encoun-
tered in porous adsorbents are the attractions of the adjacent
and opposite pore walls when pore diameters are small.
The opposite-wall attraction, or effect, enhances the
adsorption to the degree that molecular packing can occur 1n
the pores, not unlike capillary condensation. The stage at
which molecular packing starts is dependent on (1) relative
sizes of the adsorbed molecule and pore diameter, and (2)
the mutual attraction of the molecules relative to the at-
traction of the molecules to the adsorbent surface. When
the molecular diameter is larger or mutual attraction 1s
strong, molecular packing starts early in the adsorption
process.
The extent of the surface area is then a sole measure
of the adsorptive capacity only when the molecule is small,
has strong affinity to the adsorbent such as water on polar
adsorbents, and the relative vapor pressure is low. At in-
creased relative vapor pressures, multilayer and capillary
condensations can still occur. When the mutual attraction
is greater than the surface attraction, the molecule is
repelled as mercury from carbon. When the mutual attraction
is not too greatly different from the surface attraction,
molecular packing and/or capillary condensation occurs read-
ilyias with carbon tetrachloride and water on carbon. In
the latter case, the pore size distribution determines the
adsorptive capacity of the adsorbent.
The surface areas, as reported in Table 4-VI, are based
on nitrogen adsorption data using the Brunauer, Emmett and
Teller (BET) method (Brunauer 1938). On the per-unit-we1ght
basis, the surface areas of activated carbons are consider-
ably larger than those of the polar adsorbents. Activated
carbons used for vapor adsorption range in area from 1100
to 1600 m2/g, with all types ranging from about 600 to 1600
m2/g. Silica gels and activated alumina range from 800 ma/g
downward to about 200 m2/g.
Adsorbent Porosity - The pore size distribution, mean
pore diameter, surface area and pore volume are parameters
that define the pore structure. In Tables 4-VI and -VII,
the pore volume for each adsorbent was obtained by subtract.
1ng the nonporous, or Impervious volume from the volume of
-------
4-13
the particles. The impervious and particle volumes were ob-
tained from the particle and true densities as given. The
mean pore diameters for silica gel and activated alumina
were calculated assuming a cylinder of volume and surface as
given. The mean micropore diameter range for the activated
carbons was selected from pore size distribution curves
shown in Figures 4-1 and -2.
For the silica gels, activated aluminas and activated
carbons, the mean pore diameters are in the 15 to 22 A range.
Molecules of concern in air pollution range in diameter from
3.6 to over 8.7 A; a partial list of pollutant molecular
diameters is given in Table 4-V. In view of the relatively
small difference betv/een the molecular and pore diameters,
the opposite-wall effects play an important role in the pol-
lutant vapor adsorption process. Adsorptive capacity is
determined by the pore space occupied by the pollutant liquid
volume. The probability of molecular packing decreases with
increasing pore diameter; the largest pore diameters in which
liquid packing can occur at low relative vapor pressures
vary with molecular diameter and0adsorptive affinity, but
would be in the range of 20 to 30 A. Adsorption at high
relative0vapor pressures proceed in the large pores (30 to
100,000 A) by multilayer adsorption and capillary condensa-
tion. Most pollution control problems are, however, con-
cerned with emission rates at low relative vapor pressures;
therefore, the small-pore volume is the prime factor in
determining the adsorbent effectiveness.
Activated Carbon Pore Size Distribution - Because of
the prevalence of moisture in pollutantaTrstreams, the use
of polar adsorbents is very limited in pollution control,
while activated carbons are successfully used in many appli-
cations. In further discussions on adsorbents, the emphasis
is on activated carbons, although much of the information
presented will also be applicable to polar adsorbents.
In Figures 4-1 and -2, pore size distribution curves
are presented for four activated carbons of greatly differ-
ent adsorptive capacities. These four curves essentially
span the gamut of distributions observed in carbons. For
discussion purposes, the pores less than 30 A diameter are
designated as micropores and those that are larger, macro-
pores. Dubinin (1936) has classified pores below 20 A dia-
meter as micropores, those larger than 200 A as macropores
and those between 20 and 200 A as transitional pores.
Curve I is for a granular Darco carbon developed by
Atlas Powder Company for aqueous phase adsorption usaqe.
The open pore structure (i.e., the large macropore volume)
1s highly desirable since it accelerates the liquid phase
-------
I
t*
1.40
1.20 -
3
o
01
s-
o
ex
>
*»
Micropores
Macropores
* 0.40 -
0.20 -
0.00.
30 50 100
500 1000
Pore diameter, A
10,000
100,000
Figure 4-1 Pore Size Distribution Curves For Activated Carbons with
Cumulative Pore Volume Calculated Per Unit Carbon Weight
I Darco Carbon, IV Superactivated Coconut, II Type BP
Pittsburgh Activated Carbon, and III Type SXA Union Carbide
Corp.
-------
0.50
500 1000
Pore diameter, A
Figure 4-2 Pore Size Distribution Curves For Activated Carbons with
Cumulative Pore Volume Calculated Per Unit Carbon Bulk
Volume Basis, I Darco Carbon, IV Superactivated Coconut,
II Type BP Pittsburgh Activated Carbon, and III Type SXA
Union Carbide Corp.
000
i
_-*
tn
-------
4-16
adsorption rate which is generally very slow. The small
micropore volume of 0.18 cm'/g greatly limits the capacity
of this carbon for vapor adsorption; therefore, the carbon
is not competitive with the other carbons represented in the
Figures 4-1 and -2.
Curve IV represents the other extreme in adsorptive
capacity. The micropore volume is 0.73 cm3/g and is approach'
ing the upper limit attainable. This was a highly active
Barnebey Cheney coconut carbon that was further activated
(superactivated) in an attempt to reach the ultimate in
capacity. The yield was very low, less than J^jof.starting
material, which makes its cost of manufacture'e^cesVive."""'
Curve II is for a type BP carbon manufactured by the
Pittsburgh Activated Carbon Company; curve III is for a type
SXA manufactured by the Union Carbide Corporation. These
carbons occupy the middle of the capacity range with micro-
pore volumes of 0.42 and 0.46 cm*/g, respectively. The BP
carbon is used in considerable quantities in military gas
masks and the SXA,in air purification and solvent recovery
systems. These two distribution curves are characteristic
of carbons economically best applicable to air pollution
jcjontrol.
The carbon tetrachloride activity test, which 1s most
frequently used to determine the suitability of a carbon for
vapor adsorption, measures the micropore volume. Under the
test conditions the liquid volume of carbon tetrachloride
adsorbed is very nearly equal to the micropore volume.
Shown below are comparative figures of carbon tetrachloride
test results and micropore volumes of the four carbons:
Carbon tetrachloride activity Micropore
Carbon n/q cm3 liq/g volume. cm3/o
I 0.30 0.20 0.18
II 0.68 0.45 0.42
III 0.73 0.48 0.46
IV 1.20 0.79 0.73
Since the micropore size distributions of different carbons
vary, as illustrated in the Figures 4-1 and -2, the adsorp-
tive capacities of carbons of equal carbon tetrachloride
activity will only agree at one relative vapor pressure for
any vapor. For carbon tetrachloride the point of agreement
is at 0.16 relative vapor pressure. Carbons with smaller
mean micropore diameters will adsorb vapors more strongly
at the lower relative vapor pressures.
-------
4-17
Adsorptlve Capacity of Operating Unit - The various
properties of the adsoroents are reported on the per-unit-
weight basis in the manufacturers' sales 1iterature, although
the adsorbents are used in various operating units on the
fixed volume basis. Unlike the weight basis, the bulk vol-
ume basis would vary with mesh size, mesh size distribution,
particle shape and the method of packing the adsorbent bed.
A comparison of properties on the weight basis is a simpler
and more reliable evaluation of the relative merits of the
different adsorbents.
To determine the true effectiveness of an adsorbent in
actual usage, the various physical and adsorptive proper-
ties need to be recalculated on the per-unit-volume basis
as has been done in Tables 4-VI and -VII. When comparing
the surface area in mz/g with m2/cm3 bulk volume, and pore
volume in cm3/g with cm'/cm3 bulk volume, much of the large
apparent advantage of carbons over polar adsorbents is
greatly reduced. Similarly, the comparison of micropore vol-
umes on the weight basis with those on the bulk volume basis
tends to nullify the large apparent advantage of Carbon IV
over Carbons II and III.
Table 4-VIII shows the effect on carbon tetrachloride
activity and surface area when the values are converted to
bulk volume basis. Less weight of the lighter Type IV car-
bon is required to fill the adsorption operating unit and
thereby maintain cost closer to the other heavier carbons.
Table 4-VIII Physical Properties of Activated Carbons.
Densities. Carbon Tetrachloride Activities
and Surface Areas
Bulk Carbon tetrachloride
density, activity Surface area
Carbon g/cm* g/gg/cm»m*/g ma/cm3
I 0.38 0.30 0.11 580 220
II 0.50 0.68 0.34 1100 550
III 0.45 0.73 0.33 1300 580
IV 0.33 1.20 0.40 1600 530
-------
4-18
Theories of Adsorption
Forces of Adsorption
Van der Waals ' Forces - The forces active in physical
adsorption on polar and nonpolar adsorbents are associated
with van der Waals1 forces as measured by constant a, in the
van der Waals' equation of state; see Appendix D. This
association was first observed by Arrhenius (1912). Various
investigators since then have derived mathematical expres-
sions that offer explanations of the oriains of these forces.
These theories have not lead to useable methods for pre-
determininq the adsorptive affinity from fundamental proper-
ties of the adsorbed vanor and adsorbent surface. Among the
complicating factors are (1) the surface nonuni forml ties ,
(2) contribution of subsurface atoms to the adsorption po-
tential, (3) uncertainty of distance between the adsorbed
molecule and the surface, and (4) opposite-wall effects in
small pores.
Orientation and Induction Effects - To account for the
van der Waals1 attraction between polar molecules, the dipole
moment and the polarizabili ty are regarded as the primary
forces. The first is often referred to as the orientation
effect and was investigated by Keesom (1921); and the second,
investigated by Debye (1920), is referred to as the induction
effect. Lorenz and Lande, in applying the orientation effect
to adsorption, derived an adsorption potential equation on
the assumption that an interaction occurs betweenthe dipo
JUbJL-ifl mirror image of thfi dipoj.fi in a po1ariz_able surfac**.'
Jaquet U9Z5J followed the same line of reasoning but also
included the induction effect. According to Jaquet, the
adsorption potential, Q, at low temperatures is
Ny2 2 Nu*
~*o^T (4-1)
where n « o/(2o)3, a is the polarizabili ty, N is Avogadro's
number, y is the dipole moment and a the distance of adsorbed
molecule to adsorbent surface. At low temperatures where
thermal agitation is small, the dipoles are all oriented
perpendicular to the surface. At high temperatures where
all orientations are equally probable, the adsorption poten-
tial is
The orientation and induction effects do not account for the
adsorption of nonpolar molecules, particularly to nonpolar
surfaces.
-------
4-19
Dispersion Effect - London (1937) attributed the attrac-
tion between nonoolar molecules to fJuctuz
Ky mnme.nta.rv cVanaes in electron ffTstribu
nuciei. The fluctuatina dinoles induce d^
moTecules which then fluctuate in nhase w
.
:ina dinoles caused
on about thP stom^c
ioles in neiahboring
resulting attraction is referred to as the dispersion effect,
and the potential between two molecules of the same type is
approximately expressed by the equation
(4~3)
where h is the Plank's constant and v is the characteristic
frequency of oscillation of the molecule, the same as in the
Sellmier light dispersion equation. For simpler molecules
is almost equal to the ionizatign finerm/: but for larger
molecules, particularly if they contain chromophoric groups,
hv may be considerably different from the ionization poten-
tial.
With reference to Equations 4-1 and -2, the induction
effect, determined by the polarizabil i ty a, is always small,
while the orientation effect varies directly as the dipole
moment u, or as u to the second power. For small polar
molecules the orientation potential is large; but for in-
creasingly larger molecules the dipole moment decreases
rapidly and thereby the orientation potential also decreases.
For most of the organic pollutants of concern, the orienta-
tion potential is essentially zero, The dispersion potential
i s Dominated bv the Dolarizabi 1 i ty . and, because poianz-
a bill ty is pjioF?15i'T^Ty?TToTair^l ume (Vm) , the dj.s^
j u t w i t h
minor variations produced by hv.mis means that small non-
pniar molecules ajis_j^o_£_s_trongly adsorbed bv anv n£^Jt£^S&
cnrbentS DV the van HPT U »»!«' ln>.,-oc Thle« *h«»,»...i«», *«.«>
5n essential agreement with observed adsorptive affinity
variations as presented in Tables 4-II and -III.
Adsorptive Capacity
In the prior text of this chapter, the effects of chemi-
cal constitution of the adsorbent, its pore structure and
the chemical nature and size of the vapor molecule were dis-
cussed relative to the adsorptive affinity. These factors
are considered 1n selecting the type of adsorbent that is
best suited for the particular pollution control problem
under consideration.
One of the parameters that determines the effectiveness
of the selected adsorbent is its adsorptive capacity under
the expected operating conditions. This Information is
-------
4-20
necessary before any sizing estimates can be made for the
sorption unit. In a general sense, the capacity increases
with increased vapor pressure and decreases with increased
temperature.
Methods for plotting adsorption data and adsorption
equations have been developed which: (1) make presentation
of data concise and convenient, (2) permit extrapolation of
data to unmeasured pressures and temperatures, and (3) per-
mit prediction of adsorptive capacities of unmeasured vapors
from few data on those that have been measured, The last
item is of great importance in pollution control work because
of the large number of different vapors of concern that are
emitted under a wide variety of conditions and for which ad-
sorption data are lacking or very meager.
Adsorption Isotherms - Adsorption at constant tempera-
ture is frequently plotted on a linear graph as a function
of vapor pressure or relative partial pressure (p/po). Figure
4-3 shows a family of hydrocarbon isotherms on activated car-
bon plotted in this manner, The amount adsorbed increases
rapidly with increased pressure at the low pressure end of the
isotherm but levels off at the higher pressures. The liquid
volume, 0.43 cm3 liq/g, at 760 mm of Hg pressure for butane
is approaching the micropore volume; hence, the diminished
adsorption is caused by filling up the small pores. At
higher pressures approaching p/po near one, adsorption would
continue with the filling up also of the macropores. This
phase of the adsorption would be accompanied by a considerable
change in shape of the isotherm. Macropore filling can only
occur at temperature below the critical temperature.
Curve III of Figure 4-1 shows the micropore and macro-
pore size distribution of the type of carbon used in adsorp.
tion measurement plotted in Figure 4-3. At 760 mm of Hg
pressure for butane, p/po 0.28.
* Only the very low pressure end of each isotherm in
Figure 4-3 would be of direct interest in pollution control
problems. Pollutant vapor concentrations at the sources of
emission are generally below 1,000 ppm, and combustible
solvent concentration, for safety reasons, is maintained at
or below the 25% lower explosive limit during recovery oper-
ations. Table C-I gives LEL concentrations for pollutants
of concern. The 25% LEL for most organic vapors Is below
13,000 ppm which in pressure units corresponds to 10 mm of
Hg,
When it is necessary to present adsorption data over a
wider pressure range than the single order of magnitude
shown in Figure 4-3, the adsorption data are plotted on a
-------
4-21
0.50
0.40 -
0.30
e
u
0.20 ~
0.10
0.00,
100
200
300 400 500
p, mm of Hg
600
800
Figure 4-3 Adsorption Isotherms of Hydrocarbon Vapors,
Amount Adsorbed w at Pressure p on Type
Columbia L Carbon at 100°F, Liquid Volume
of w at Bollinq Temperature.
-------
4-22
log-log graph as in Figure 4-4. These isotherms also level
off at the higher pressures because of micropore filling at
the 0.50 cm3/g level. In the low pressure region below 10
mm of Hg, which is of interest in pollution control, this
manner of nlotting clearly indicates the adsorptive capaci-
ties.
Isotherms of a different type that are important to
pollutant vapor control are those of water vapor on activated
carbon. The nature of the isotherm gives some insight into
the type of interference the presence of water vapor will
have on the adsorption of organic vapors. Isotherm I of
Figure 4-5 corresponds to pore size distribution Curve I in
Figures 4-1 and -2. Isotherm II is typical for activated
carbons best suited for adsorption of vapors; i.e., of carbon
types represented by Curves II and III in Figures 4-1 and -2.
* The characteristic features of the water adsorption iso-
therm are the pronounced hysteresis of the adsorption and
desorption branches and the rapid increase in amount adsorbed
at p/po above 0.5. At p/po below 0.4 the moisture in a
pollutant airstream will cause very little interference with
the adsorption of most of the pollutants of concern. Moisture
can cause a further decrease of the already poorly adsorbed
organic vapors such as chloromethane, ethane and methane.
Organic vapors of Vm greater than 90 cm3/mol displace water
from the carbon, but at the higher p/po of water the adsorp-
tion rate of organic vapors decreases. In thin carbon beds,
a high water P/PO can cause a premature pollutant vapor
penetration. Moisture interferes less with water soluble
pollutants than with nonsoluble pollutants.
The hysteresis can cause operational problems. If
satisfactory operation is possible at p/po range from 0.5
to 0.7, but the moisture content of the pollutant airstream
should happen to go to higher humidities such as to saturate
the bed, the carbon would have to be dried to p/po of 0.4 or
less before satisfactory operation can be regained.
Equations for Isothermal Adsorption - Various investi-
gators have developed adsorption equations that agree with
data for specific adsorbate-adsorbent systems and over fairly
limited concentrations. These equations are suitable for
interpolation and extrapolation purposes.
An equation found applicable for liquid phase decolor-
izing applications and also frequently checked out on vapor-
phase adsorption data is the Freundlich (1933) equation as
LJ f | vl J t » «^wi ***»»* »»» - _--_ _
given below in logarithmic form.
-------
4-23
1.00
. 0.10
u
0.01
j I
I I .
1 I I
10
-9°F
170°F
p, mm of Hq
100
1 I ' ' ' H
Figure 4-4 Adsorption Isotherms of Butane at Three Tempera
tures on Pittsburgh BPL Type Carbon, Amount u>
Adsorbed at Pressure p. Data From Grant (1962)
-------
4-24
0.60
0.00
Figure 4-5 Isotherms of Water on Activated Carbons Showing
Hysteresis Between Adsorption and Oesorptlon
Branches, I Darco Carbon, II Typical of Pitts-
burgh BP or Union Carbide SXA.
-------
4-25
log u » log k + [1/n] log p (4-4)
Here k and n are constants dependent on molecular structure
of adsorbate, chemical constitution of adsorbent, pore struc-
ture and temperature; k 1s equal to to when p is one.
When the adsorption data obey the equation, a log-log
plot yields a straight line graph. The type of curves in
Figure 4-4 are frequently called Freundlich isotherms; how-
ever, in these cases, the curvatures show deviation from
the equation. At lower pressures, below 1 mm of Hg, the
tendency is for the curves to straighten out.
In 1916, Langmuir derived an adsorption equation for
vapors on kinetic considerations. According to Langmuir,
vapor molecules colliding with the adsorbent surface suffer
Inelastic collisions; the time lag is responsible for ad-
sorption. He also assumed that only unlmolecular layer
adsorption could occur. The Langmuir equation 1s presented
1n two forms below; the latter 1s more convenient for test-
Ing against adsorption data.
(4-5)
vm
In these equations v is the volume of vapor adsorbed on a
unit weight of adsorbent, b is a constant, and vm Is the
amount of vapor necessary to form a unimolecular adsorbed
layer. The equation fits chemisorptlon data and physical
adsorption data at low relative pressures or data of gases
at temperatures above their critical temperatures. Essen-
tially all pollutant vapors are adsorbed below their critical
temperatures and on adsorbents of small pore diameter in
which opposite pore wall attractive forces would induce
adsorption by molecular packing rather than unimolecular
adsorption. The equation has little or no direct application
in pollution control studies; but it 1s an Important equa-
tion used 1n developing later equations useful to pollution
control.
Brunauer, Emmett, and Teller (1938) derived equations
for multilayer adsorption of vapors by generalizing on Lang-
muir's treatment of unimolecular adsorption. On powdered
materials or adsorbents having large pores, where an un-
restricted number of molecular layers can be adsorbed; the
equation has the form
-------
4-26
1 c-1
v[p0-p] vmc vmc PO '
In this equation c Is a constant dependent on temperature,
the average heat of adsorption E] in the first adsorbed layer,
and the he^t of liquifaction E$.
c - exp - ^j (4-8)
When the adsorption data obey the equation, a plot of
Vn^TpT versus ^ (4.9)
gives a straight line graph from which it is then possible
to calculate vm and c. The number of molecules in VD mul-
tiplied by the surface area covered by a single molecule
gives the total surface area of the adsorbent. This is the
well known BET equation, and, amongst many other applications,
is used by the adsorbent manufacturers to determine and report
the surface areas of their products. It has been the center
of considerable investigation by numerous researchers whose
works have been reviewed by Gregg and Sing (1967).
For surface area determinations, the most practical gas
is nitrogen and the adsorption data are obtained at liquid
nitrogen temperature, i .e. , -196°C. The nitrogen molecule
mean diameter is 4.3 A, and the area covered by each molecule
is 16.2 square A. In adsorbents having small pores, partic-
ularly in activated carbons, the nitrogen molecule diameter
is a large fraction0of the pore diameter; as for instance in
pores less than 17 A diameter (the mean diameter for SXA and
BP Figure 4-1) the ratio is over 0.25. In these cases, the
plot of relationship (4-6) above gives a very short straight
line graph or one that has a continual but slight curvature;
hence, the surface areas reported for these adsorbents are
subject to some error. The BET equation developed for a
flat surface deviates when applied to small-pore-sized adsor-
bents. When the bulk of the pores are 30 A and larger, the
plot of relationship (4-6) gives a straight line graph that
can extend to 0.35 p/po, and thereby lend a greater confidence
level in these applications.
Where the number of molecular layers is restricted to
some finite number n, as might be the case in small-pore-
sized adsorbents, the BET equation has the form
-------
4-27
vmcx l-(n + l)x" + nx"
1-x 1 + (c-l)x - cxn + '
where x = p/p0. This equation, however, has not found accep-
tance among adsorption investigators as an equation for de-
termining the surface area.
Pore Structure Determination
Based on Nitroqen Adsorption Data - The pore size dis-
tribution is one of the most important factors that deter-
mine the overall shape of the isotherm, and conversely the
isotherm should give a measure of the pore size distribution
when correctly interpreted.
According to multimolecular layer and capillary conden-
sation theories, the adsorption of a gas such as nitrogen at the
nitrogen boiling point (-196°C) commences as a unimolecular
layer followed by multimolecular layers until the pore space
is filled. This mechanism determines the shape of the ad-
sorption branch of the isotherm. On desorption, the nitro-
gen is released by a different mechanism that gives a hys-
teresis loop to the desorption branch of the isotherm.
The general form of a nitroqen isotherm is illustrated in
Figure 4-6 for an activated carbon suited for vapor phase
adsorption.
When an incremental volume of adsorbed nitrogen (liquid
volume) is desorbed, a part of it is vaporized from the
multimolecular layer on the pore wall and a part from the
meniscus of the condensed phase in the inner capillary space.
The p/Po bears relationships simultaneously to the meniscus
radius and multimolecular layer thickness. The Kelvin e-
quation (Thompson 1871) given below expresses the function
between p/Po and meniscus radius, r^.
rk = Y c?s (4-11)
k ftt ln(po/p) VH IU
Here Y is the surface tension of the adsorbed nitroqen, V
the liquid molar volume of the adsorbed nitrogen, and the
contact angle of the miniscus with the multimolecular ad-
sorbed layer. (For nitroqen at -196°C, is zero). The
multimolecular layer thickness, T, can be determined ex-
perimentally for nonporous adsorbents and then applied to
porous adsorbents assuming the function still applies. The
pore radius at any p/p0 on the desorption branch of the
-------
4-28
0.60
0.50
CT>
- 0.40
o
t 0.30
o
m
o
E
0.20
0.10 -
0.00
I I
I I I I I
0.2
0.4
P/Po
0.6 0.8 1.0
Figure 4-6 Nitrogen Isotherm on Activated Carbon
at -195°C Showing Hysteresis Loop
Extending from p/p0 0.5 to 1.0
-------
4-29
isotherm is then
r * rk + T (4-12)
Barrett, Joyner and Halenda (1951), on these basic assump-
tions, developed a method for determining pore size distri-
bution curves for adsorbents from the desorption branch of
the nitrogen isotherm determined at -196°C. The calculations
are quite involved requiring tables of precalculated T vs
p/p0 values (American Document Institute). The method, on
theoretical grounds, is applicable only to the portions of
the isotherm above the lower p/p0 at which the hysteresis
loop closes. The lower limit can range from 0.4 to 0.5 p/pfl;
the 0.4 p/p0 corresponds to 40 A pore diameter.
Because of difficulties in measurinq p/p0 accurately
above 0.97, the practical upper limit on diameter determina-
tions is 670 A. The method has, however, been extended by
many investigators to pores smaller than 40 A.
Based on Hater Adsorption Data - An alternative method
applicable only to activated carbons involves the direct
application of the Kelvin equation (Equation 4-11) to the de-
sorption branch of the water isotherm (Juhola and W11g,i949).
The pore size distribution Is derived by measuring desorbed
liquid water volume increments at each reduced p/p0. In
Equation 4-11,molar volume V varies between 19.3 and 21.2 cm8/
mol with changinq p/p0 (Wiig and Juhola, 1949) and cos
-------
4-30
penetration at each pressure increase. This technique was
first suqqested by Washburn and first used by Ritter and
Drake (1945). They found that <> was (qua! to 140° on a
variety of solids although some uncertainty exists in its
magnitude.
o
The largest pores measurable are 100,000 A at a pressure
of 17.4 Ib/sq in. absolute. A pressure of this magnitude is
required to outline adsorbenj granules; or conversely,
"pores" larger than 100,000 A diemeter are in reality inden-
tations in thu granule exterior surfaces. The smallest
pores measurable depend on maximum pressure attainable and
the effect the pressure has on the pore structure. A theo-
retical pressure of 60,000 lb/in2 is required for mercury
penetration into pores of 30 A diameter. At these pressures
compression of the carbon can be expected resulting in
erroneous volume measurements. Measurement up to 60,000
lb/in2 are, however, made as standard practice with commer-
cially available equipment.
Comparison of the Three Methods - The pore size dis-
tribution, as determined by the above described three meth-
ods, overlap in the 30 to 760 A diameter which makes possi-
ble their comarison over a limited range of application.
Joyner, Barrett and Skold (1951) compared the pore size
distribution curves obtained by the nitrogen isotherm method
and mercury porosimetry over the diameter range 60 to 600 A,
Their studies were with bone chars and synthad, a material
chemically similar to bone char. These adsorbents were
chosen because they had an abundance of pores in the range
where the two methods overlap. They found a good agreement
between the two methods on some of seven adsorbents tested.
Where there was more than one peak in the distribution curve
both methods indicated their presence, shape and size with
good agreement in some cases, although in others.there was
displacement.
Pore distributions in the 10 to 600 H range for acti-
vated carbons, as determined by nitrogen and water adsorp-
tion methods, yield curves of the same overall shape but
disagree to some extent on magnitude of diameter at any
given accumulative volume. The most significant variance
starts at the 40 A diameter and is carried down to the
smallest pore measured (Juhola, Palumbo and Smith, 1952).
Comparisons of pore size distributions as determined
by the water adsorption and mercury porosimetry methods al-
ways show a qualitative agreement in shape of distribution
curve, but vary in agreement on magnitude of pore diameter
at any given accumulative volume. With some carbons, the
overlapping section by the two methods coincide; while with
others, the varUnce can be either way.
-------
4-31
The conclusion is that the three methods are in agree-
ment in indicating the type of pore structures for diverse
carbons. The type of distribution has an important bearing
on the adsorption of pollutant vapors at low concentrations.
Carbons with an abundance of small pores have the largest
capacity at low concentrations, a desirable property for
pollutant control; however, an abundance of small pores is
an undesirable property in solvent recovery carbons oper-
ated at high solvent concentrations.
Adsorption Thermodynamics
Heat of Adsorption - Adsorption is accompanied by two
energy changes:(1) a decrease in free energy AF measured
by the decrease in vapor pressure, and (2) a decrease in
entropy AS due to decrease in mobility of the adsorbed vapor.
These changes decrease the heat content AH of the system in
the manner expressed by the equation
AH - AF + TAS (4-14)
All adsorption processes are exothermic.
AH can be determined calorlmetrically, or more conven-
iently* from adsorption isotherms measured at separate tem-
peratures by application of the Clausius-Clapeyron equation.
In p - M + k (4-15)
This equation applies at a constant amount of adsorbed vapor
and applies over a limited temperature range because of a
gradual variation in AH with change in temperature.
Its application can be demonstrated with data taken
from Figure 4-4. Table 4-IX presents the pertinent data
and the calculated AH and k. Sample calculations are given
1n Appendix E , page E-l.
Table 4-IX Adsorption Data and Calculated AH and k for
Butane on Activated Carbon Type BP
M| cm3 liq/9
0.20
0.30
0.40
[liquid]
P.
-9°F
2.3
17
[300]
mm of Hg
77°F
7.3
38
220
[1820]
170°F
68
340
[7000]
-AH .cal/mol
8.800
8,700
7,900
[ca 5.500]
k
16.8
18.3
18.7
[16.7]
-------
4-32
AH in these cases are the differential or isosteric heats of
adsorption. They decrease as the amount of adsorbed vapor
is increased. When the pore space 1s almost completely filled,
AH will approach the heat of 1iquifaction, which varies from
5,600 at -9° to 5,400 cal/mol at 170eF.
The heat of adsorption in the initial stages is the
highest because the vapor first becomes attached to the most
active sites on the surface or first becomes located in the
smallest pores where the opposite wall attractions are the
strongest. In the final stages of adsorption, where the ad-
sorption mechanism can be multimolecular layer or capillary
condensation in large pores, the heat of adsorption approaches
that of liquifaction.
The heats of adsorption increase on the molar.weight
basis, but when converted to unit weight or unit liquid
volume basis, they are in a fairly narrow range, i.e., 100
to 200 cal/g or 200 to 300 Btu/lb of vapor adsorbed. At
low pollutant vapor concentrations, below 100 ppm, the heat
release rate 1s slow and is greatly moderated by the air-
flow. When the vapor concentrations are at the 25% LEL,
considerable heating of the carbon bed can occur. Auto-
ignition of carbon beds used for ketone recovery have been
reported. This problem is avoided by leaving the bed wet
from the prior steam regeneration.
Figure 4-7 shows the data of Table 4-IX plotted as
isosteres. When pressure data are available for a given u
at more than two temperatures, a plot of this type measures
the degree of agreement with theory. The three pressure
points for u - 0.30 cm3liq/g yield a straight line curve
indicating that AH is quite constant over the temperature
range -9° to 170°F. Carbon adsorbent systems for pollutant
control and solvent recovery are operated most effectively
in the 60° to 130°F temperature range.
Free Energy Change - The free energy change AF, as part
of Equation 4-14, is a function of the relative vapor pressure
given by the following relationship.
AF - -RT ln[po/p] (4-16)
On the basis of the data in Table 4-IX AF values were cal-
culated to show their characteristics; these AF values are
qiven in Table 4-X. For these calculations, po at -9*F 1s
300 mm, p0 at 77°F is 1820 mm and p0 at 170°F 1s 7000 mm of
Hg.
-------
4-33
1000
500
-
IMIVMI
« , p , T
\ 170*F K 77°F -9^
X \
\ \
\ \
M
^^^^
_
\
\
r- N
100
50
o>
z
£
ft 10
1.0
tiii
2.5
.40 cm'Hq/g
\
\
v
\
. . . . I . . N
3.0 3.5
1/T x 10J
4.0
4.5
Figure 4-7 Isosteres for Butane on Activated Carbon.
Type BP
-------
4-34
Table 4-X Free Energy Change AF During Adsorption of
Butane on Activated Carbon
-AF, cal/mol
to, cm3liq/g at -9°F 77°F 170°F
0,20 3,300 3,200
0.30 2,400 2,300 2,100
0.40 1,400 1,200
AF decreases as the amount of vapor adsorbed on the carbon
is increased. At complete filling of the pores, AF approach-
es zero and AH = TAS.
Entropy Change - Table 4-XIgives the entropy changes for
the butane adsorption obtained by substitution of AH and AF
from Tables 4-IX and -X into Equation 4-14.
Table 4-XI Entropy Change AS During Adsorption of Butane
on Activated Carbon
-AS. cal/mol
a), cm3 liq/q -9°F 77°F 170°F
0.20 18.6 16.0
0.30 25.2 21.6 18.8
0.40 26.0 22.6
[liquid] [22.4] [18.4] [16.0]
AS measures the change in mobility of the molecules in trans-
fer from the vapor phase to the adsorbed phase. A large
-AS indicates a large decrease in mobility while a +AS in-
dicates a large increase. As the micropores are filled -AS
increases and is maximum at the point where the micropores
are completely filled, i.e., at about 0.45 cm*/q. During
macropore filling -AS decreasesand ultimately reaches the
value at normal condensation.
Potential Theory Equations - Two properties of AF use-
ful in pollution control work are: (1) AF is fairly constant
over a moderate temperature range; and (2) AF decreases with
increased amount of adsorbed vapor. Equations have been
developed on the basis of these two properties that permit
estimating adsorptive capacities for an unmeasured vapor-when
meager data are available on some other.but similar, vapor.
-------
4-35
Tables 4-X and -XII and Figure 4-8 present numerical
figures that indicate the degree of constancy of AF with
temperature change, and show the decrease of AF with in-
creased 0).
For propane (Table 4-XII) at u less than 0.20 cm3 liq/g,
AF increases gradually with increased temperature, while
above 0.20, it decreases with increased temperature. At
high adsorption pressures p or high vapor pressures p0, the
use of fugacities, f and f0, in place of p and PA 1n Equa-
tion 4-16 improves the constancy of AF. Sample calculations
showing the use of fugacity and its effect on AF are worked
out in Appendix E, page E-3.
Table 4-XII Variation of AF or ej with Temperature and
TTmount u> of Propane Adsorbed on Type L Carbon
»AF or e-j, cal/mol
Average of
u>. cm8 liq/g 100°F 150°F 200°F 250°F 100°F & 150°F
0.10 3,800 4,000 4,200 4,500 3,900
0.15 3,300 3,400 3,600 3,600 3,350
0.20 3,000 3,000 3,100 3,000
0.25 2,600 2,500 2,550
0.30 2,100 2,000 2,050
Equation 4-16 is the basis of the Polanyi potential theory
of adsorption, the symbol ci being used in place of AF
(Polanyi, 1914). He observed that at any fixed amount to
adsorbed, el is constant; hence,
~ --InCpo/p] (4-17)
If PQ/PI and TI are known at a fixed u>i, P0/P2 can be esti-
mated for u»i at T£ provided T^ and T£ are not widely sepa-
rated. Carbon adsorbent systems are most effectively used
in the fairly narrow temperature range of 60° to 130°F;
hence, AF or e-j will be fairly constant in the temperature
range of interest.
The curves for propane, butane and pentane 1n Figure
4-8 show graphically the variation of AF with molecular size
and w. When AF is divided by the molecular weight, I.e.,
by converting AF to cal/g, the three curves are drawn closer
together giving a common curve; this effect 1s shown in
-------
4-36
1.00 r
0.01
1,000 2,000 3,000 4,000
-AF or -ei,cal/mol
5,000 6,000
Figure 4-8 Variation of Free Energy AF or Polanyi Potential
ei with Amount of Vapor w Adsorbed on Activated
Carbon. u> Measured per Gram of Vapor and AF and
ei per Mol of Vapor
-------
4-37
Figure 4-9. The amount adsorbed is now a function of M, T
and po/P as shown below,
RT
w function of j^- In (p0/p) (4-18)
where M is the molecular weight and w is measured in g vapor
per g of carbon.
If a few adsorption points are known for an activated
carbon so that a curve can be drawn, the curve can now be
used to estimate isotherms of other members of a homologous
series or of other similar vapors.
Because of packing of molecules in the micropores, ad-
sorptive capacity is determined volumetrically rather than
gravimetrically. By dividing AF by the molar volume, Equa-
tion 4-18 is greatly broadened to include other homologous
series and a wider range of higher density molecules. The
proper choice of molar volume has been an area under consid-
erable investigation amongst different adsorption investiga-
tors. Dubinin, et al. (1947) suggested using the liquid
molar volume of the adsorbed vapor at the adsorption temper-
ature. Lewis, et al. (1950) and later Grant, et al. (1962)
experimented with the molar volume at the temperature where
vapor pressure equals adsorption pressure. Robell, et al.
(1965) used the liquid molar volume at the normal boiling
point. Lewis and Grant used fugacities in place of adsorp-
tion and liquid vapor pressures where a significant differ-
ence existed.
In view of the packing of relatively large molecules of
over 4 A diameter in pores of less than 20 fl diameter, the
normal concepts of liquid molar volumes lose some of their
meaning. Two effects can occur: (1) steric hindrance which
tends to promote packing of lesser density than in normal
liquids, and (2) stronger attraction toward the pore walls
which tends to promote packing of greater density than 1n
normal liquids. The actual volume of adsorbed liquid can be
expected to vary with molecule-to-pore diameter ratio and
compressibility of the molecules.
For purposes of estimating w, the right side of Equation
4-18 is now modified so that it has the form
[T/V] log [po/p], or (4-19)
[T/V] log [f0/f] (4-20)
where V is the liquid molar volume of best choice for the
particular system. From adsorption data (at least two adsorp-
tion points) a generalized adsorption curve 1s drawn wherein u
In liquid volume per gram of carbon 1s plotted on a logarithmic
-------
4-38
1.00
on
^0.10
«k
3
0.01
C5H12
and
C4H10
1
1
1
10 15 20
-AF or ei, cal/g
25
30
Figure 4-9 Variation of Free Energy AF or e^, with Amount
of Vapor CD Adsorbed on Activated Carbon, w,
AF and et Measured per Gram of Vapor
-------
4-39
ordinate scale as function of the quantity RgJ or \20j above on
a linear abscissa scale. Whatever density is used to calcu-
late molar volume V is also used to calculate the liquid
volume of w; the effects of density selection thereby tends
to cancel out. For future reference, the quantity in if 9? or
s designated by A when it is more convenient to do so.
The adsorption results for propane, butane and pentane
as presented in Figure 4-8 are replotted in Figure 4-10,
using quantity /IsQand molar volume Vm as measured at the
normal boiling point, w was also converted from g/g to cm3
liq/g, using the liquid density at the normal boiling point.
To obtain Vm, the method of LeBas was used; see Appendix D
for table of additive volume increments.
The method gives the best generalized adsorption curves
for homologous series. On activated carbons the generalized
curves of different homologous series tend to coincide; the
largest variance comes at the large A values. Grant, et al.
found that the generalized curve for sulfur compounds was
considerably above that for hydrocarbons. On silica gel the
variances between curves of different homologous series are
larger; adsorption data on one homologous series do not lead
to an acceptable prediction regarding adsorption of members
of other homologous series.
Effect of Pore Structure on Generalized Adsorption Curve
. Figure 4-11 shows three generalized adsorption curves that
may cover the range of this type of curve for commercial carbons
suitable for vapor phase adsorption. S154 is an experimental
superactivated peach pit carbon of 154% carbon tetrachloride
activity having micropore volume near 1.00 cm3/g. It is
similar to carbon IV of Figure 4-1 but with larger micropore
volume and also larger mean micropore diameter. It approaches
the upper limit on high capacity carbons. GI is a high activ-
ity coconut carbon of 0.65 cm3/g micropore volume. The gen-
eralized adsorption curve for BPL was determined with adsorp-
tion data of sulfur containing vapors such as methanethiol ,
ethanethiol, propanethiol , hydrogen sulfide and carbon disul-
fide. These vapors are more strongly adsorbed than other
organic vapors of equivalent A value. Generalized adsorption
curves for other carbons are expected to be below this BPL
curve at the larger A values.
Figure 4-12 shows generalized adsorption curves that are
typical of solvent recovery and gas mask carbons. The pore
size distribution of SXA is number III in Figure 4-1 and that
of the upper BPL curve is number II in Figure 4-1. The lower
BPL curve, designated here as Type V, was obtained from
studies carried out by Robell (1965), and is presented here
because a large number of regeneration calculations discussed
In Chapter 6 are based on this curve.
-------
4-40
1.00
0.10
E
»
3
0.01
~r
C3H8
-~ C4H10
C5»12
i i
J L
1
A,
log [p0/p]
10
Figure 4-10 Generalized Isotherms For Propane, Butane
and Pentane
-------
4-41
10
1.00
S154, Superactivated Peach Pit Carbon,
MSA Research Corp. experimental carbon
GI, Barnebey Cheney Coconut
BPL, Pittsburgh
Activated Carbon,
curve for sulfur
compounds, Type VI
0.001
| 1 i i i I M I i I I I I h I I t I I I I I I » I I I I M I I
10 15 20
A, [T7YB]loq[p0/Pl]
25
30
35
Figure 4-11 Generalized Adsorption Curves For Three
Widely Different Types of Activated Carbon
-------
4-42
10
1.00
0.10
E
u
3
0.01
0.003
SXA, Union Carbide
Type III. Figure 4-1
BPL, Pittsburgh
Activated
Carbon, Type V
BPL, Type II,
Figure 4-1
I i I i I I I I I I i I I I I I M I ll i i i I I I i i I i t
10 15 20
A, [T/Ym]lofl[p0/p]
25
30
35
Figure 4-12 Generalized Adsorption Curves Typical of
Activated Carbons Used in Gas Masks and
Solvent Recovery
-------
4-43
Under the conditions of the carbon tetrachloride activ-
ity test described in Appendix D,
[T/VJ log [p0/p] = 2.5 . (4.21)
At 2.5, CD « 0.45 cm3 liq/g for BPL(II). From Curve II in
Figure 4-1, w 0.45 cm3/? corresponds to a pore diameter of
40A. This means that all adsorption at A larger than 2.5
occurs in pores smaller than 40 A diameter, and also the
curvature of the generalized adsorption curve is determined
by the distribution of pores in this small-diameter range.
For SXA Curve III, the volume of pores smaller than 40 A
diameter is 0.48 cm3/g. Above 0.05 cm3/g pore volume, the
pore diameters of SXA are smaller than those of BPL. This
accounts for the stronger adsorption by SXA at u> laroer than
0.05 cm3 liq/g. At A 17 or u> « 0.05 cm3 liq/g, the SXA
and BPL curves cross each other; and likewise the pore-size
distribution curves cross each other at 0.05 cm3/ci pore vol-
ume. At u or pore volume less than 0.05, BPL is the stronger
adsorbent.
In macropores larger than 40 A* diameter or, stated other-
wise, at A less than 2.5, adsorption proceeds very slowly,
although for SXA and BPL the available macropore space is
about 0.40 cm3/g. At A less than 2.5, AF, the driving force,
for the adsorption approaches zero, and at the theoretical
point where all the pores are filled
AH » TAS (4-22)
By accurate measurements of adsorption at p/p0 above 0.99,
the generalized adsorption curves of SXA and BPL would ap-
proach A 0 gradually and stop at u near 0.85 cm3 Hq/g.
By a straight extrapolation of the curves to A 0, as done
in Figure 4-11, and -12, the w intercepted is aemeasure of
pore volumes usually of diameter less than 100 A.
The operating capacity in solvent recovery applications
1s in the low A value range (1 to 15); hence, a large ad-
sorptive capacity is desirable 1n this A value range but, to
ease regeneration,a low capacity is desirable in the higher
A range. To adsorb weakly adsorbed pollutants or pollutants
at very low concentrations, strong adsorption is required at
large A values (above 15); the capacity at low A values In
this case makes very little or no contribution.
-------
4-44
Dynamic Adsorption Processes
Vapor Distribution in Adsorbent Bed - Sorptlon devices
for solvent recovery or air purification most frequently
employ a fixed adsorbent bed. It is the simplest and most
trouble free in its operations. Other systems have been
developed in which the adsorbent is moved countercurrent to
the vapor airstream or the adsorbent is fluidized in the
vapor airstream. When the adsorbent bed is fixed or moves
as a unit, the vapor concentration distributions in adsorbent
beds follow definite patterns that can be analyzed and the
knowledge so gained used to determine the adsorbent device
designs.
Curve 1 of Figure 4-13 illustrates the vapor concentra-
tion distribution at the start of the adsorption process in
a fresh carbon (adsorbent) bed. The vapor concentration de-
creases from Ci to a concentration approaching zero in a
relatively short distance. Theoretically, zero concentration
is attained only at infinite bed length, but for practical
purposes concentrations of 0.01 Ci to 0.001 C-j are considered
essentially zero, hence the finite bed lengths.
At a later adsorption time, the vapor distribution
curve has lengthened as illustrated by Curve 2. If adsorp-
tion is continued, the vapor distribution curve ultimately
stops lengthening or reaches a steady state. Curve 3 shows
the distribution curve when it has just attained the steady
state; Curve 4 shows it when it has moved down the bed some
distance in its entirety. The length of the distribution
curve is the adsorption zone length, LZ. The bed length,
Ls, following the adsorption zone is the saturated bed
length. In this section of bed, the adsorption and desorption
rates are equal; the bed is at equilibrium with the influent
concentration Ci. If adsorption is continued, the adsorption
zone ultimately starts to penetrate the bed as illustrated by
the lower end of Curve 5. Length LZ has remained constant
but Ls has increased. If it is undesirable to permit any
appreciable vapor penetration, adsorption in the bed is dis-
continued by diverting the vapor-airflow to a fresh carbon
bed. It is apparent that the full capacity of the carbon
has not been utilized since L2 is only partially saturated.
If it is not objectionable to allow continued and increased
penetration as when a fresh carbon bed can be connected
temporarily in series with the nearly spent bed adsorption
can be continued advantageously until LZ has penetrated the
bed. At this stage of the operation, the vapor concentration
at the effluent end of the bed has risen to the level illus-
trated by Curve 6, i.e., Cb C^.
-------
Figure 4-13 Movement of Vapor Concentration Distribution Curve in Carbon Bed
with Increased Adsorption Time
tn
-------
4-46
As the adsorption 2one depicted by Curve 5 penetrates
the bed, the effluent vapor concentration changes with time
in the manner shown in Figure 4-14. (This is an experimen-
tally determined curve for butane on activated carbons; con-
ditions of adsorption and sample calculations are given in
Appendix E.) The service time, tb, can be determined from
this curve when the breakpoint concentration, Cb, is defined.
The curve in Figure 4-14, indicates a service time of 600
min. at Cb B 0.01 Ci and 1100 min. at Cb a Ci.
*£ In air pollutant control, the carbon bed can be operated
under conditions indicated by Curves 2 to 6 inclusive. When
the pollutant is strongly adsorbed, and the concentration,
Ci, is very low (1 ppm) and large volumes of air are purified
the resistance to airflow becomes an overriding factor. Under
thjie_ circumstances it is economical to sacrifice capacity,
as when bed length is limited to those depicted by Curves 2
or 3. A short or thin bed length is used, varying from 1/2
to 2 inch, and pressure drop is maintained below 0.5 inch of
H20. Because the concentration is low and the pollutant 1s
strongly adsorbed, the vapor distribution curve moves down
the bed very slowly. Penetration through a fresh bed may be
1% to 53!, and, after a year's time, the penetration has in-
creased to 102. At that time the bed is exchanged for a
fresh one.
In solvent recovery the carbon bed is operated under
conditions depicted by Curves 5 and 6. In these cases, Ci
may be over three magnitudes larger than in odor removal,
but total airflows are considerably smaller.
Determination of Service Time - To attain the desired
air pollution control, or economic solvent recovery, or air
purification, the service time is one of the prime factors
to be considered in sizing the sorbent device.
When deep or long carbon beds are used, as in solvent
recovery, LS is large relative to Lz and essentially deter-
mines the service time. With usual solvent recovery prac-
tice, the solvent-air velocity through the bed is maintained
at near 100 ft/min. In these cases LZ is of the order of
3 in. and L can range from 16 to over 36 in. The capacity
of the saturated bed length, LS, can be calculated with con-
siderable degree of accuracy if an adsorption isotherm has
been determined, or it can be estimated if a generalized
adsorption curve (Figures 4-11 and -12) is available. Pol-
lutant vapor Vm values to be used in conjunction with the
generalized adsorption curves are listed in Table C-I.
-------
TOO
80
60
E
CL
o.
«0
$.
g 40
c
o
o
20
0
tb = 600
when
Cb * 0.01 C
200
1 L
400
600
800 1000
t, min.
1200
1400
1600
Figure 4-14 Effluent Concentration Curve of Butane Vapor From An
Activated Carbon Bed as Function of Time
-------
4.48
The capacity of the adsorption zone, besides varying
with C-j and T, also varies with the carbon mesh size and
flow velocity. The service time, t^, to penetration concen-
tration, 05, is dependent on the saturated bed and adsorption
zone adsorptive capacities as expressed by the equation,
+ w2L2], (4-23)
where A- is the area of the carbon bed, F the solvent-air*.
flow rate, us tne adsorptive capacity per unit carbon bed
volume in the saturated zone and wz the mean adsorptive
capacity per unit bed volume 1n the adsorption zone. In
this equation, w2L2 is a fixed amount wherein the L2 1s de-
fined as the bed length In which C decreases from C-f to
essentially zero, Ls varies with the C^/C^ ratio; at CK
Ci, Ls « L while at Cb s 0, Ls * L-L2.
In thin beds of 2 1n. and less, as used 1n air purifi-
cation, flow velocities near 40 ft/m1n. are usually employ-
ed which shortens Lz down to the 2 in. level. In these
applications, the service time 1s essentially
zLz ' <4"*4)
To attain the desired service time, the dimensions of
the carbon volumes
AC [Ls + Lz] or ACLZ
are optimized with consideration given to resistance to a1r«
flow that can be tolerated and the hardware to contain the
carbon bed. When dealing with cylindrical beds, the para-
meter L/D 1s frequently referred to.
Characteristics of the Adsorption Zone - The adsorpt1v«
capacity and length of the adsorption zone can be calculated
if the effluent concentration curve has been determined for
the flow system. This 1s possible only if the adsorption
rone has reached a steady state before the vapors penetrate
the bed. If the bed is shorter than L2, the vapor distribu-
tion curve is still changing, and the effluent concentration
curve reflects this change. By procedures and sample calCul»
tions given in Appendix E, page E-5, the effluent concentratiV.
curve of Figure 4-14 was converted to the vapor distribution
curve given in Figure 4-15. At C-f 66.8 ppm, P » 5 lb/1n*
absolute, T 111°F, 28 to 60 carbon mesh size, and 14.5 ft/
min. face velocity, the following values were calculated for
-------
4-49
TOO
E
O.
o.
c
o
60
5 40
u
e
o
20
Klotz
Theoretical
1.0
L, cm
Z.O
Figure 4-15 Butane Vapor Distribution In Activated Carbon
Bed at Time When Vapor Has Started to Penetrate
Bed
-------
4-50
the unknown parameters of Equation 4-23:
LZ
U)Z
1.27 cm
0.00738 g/cm3;
1.13 cm
0.00363 g/cm3;
0.0182 g/g
0.0089 g/g
Acwsl-s
AcuzLz
0.00470
0.00206
wz is about one-half as large as u>s» and on comparing
the last two Items about one-third of the service time for
this particular vapor-adsorbent system is contributed by
the adsorption zone. Since AcuzLz stays constant, all of
the adsorption would occur in the adsorption zone if the bed
were shortened to 1.13 cm and the service time would be re-
duced to 180 from the 600 min. On lengthening the bed, an
increasingly larger portion of vapor will be adsorbed in the
AcwcLs bed. At higher gas velocities and with coarser mesh
carbons, Lz increases in length.
Critical Bed Depth - A useful concept for determining
the extra amount of carbon required to accommodate the ad-
sorption zone is the critical bed depth. This concept was
first expressed by Mecklenburg (1925) in the following ser-
vice time - bed length equation,
FCi
- Lc]
(4-25)
where Lc is the critical bed depth. When experimentally de-
termined tb are plotted against L, a graph of the type shown
by ABC in Figure 4-16 is obtained. At short bed lengths
the graph is curved as indicated from L « 0 to some point B,
and from B to longer bed lengths the graph is straight. When
the straight portion is extrapolated to tb = 0, 1t intercepts
the L axis at some point now referred to as Lc. When tjj is
determined at low penetration concentrations, i.e., Cb « 0.01
is positive, when tb is determined at Cb near 0.5 C-j,
and at Cb u C-j, LC has a negative value. Equation 4.25
has utility in adsorbent bed size, ACL, determinations at
any penetration concentration although the most frequent
interest is at Cb ^ 0.01 C-j . An estimate of us as a function
of CT is obtainable if a generalized adsorption curve is
available by procedures discussed under Potential Theory
Equations. Lc varies with the air velocity, F/AC; hence,
tb must be known for one L at each F/AC of interest as the
minimum data requirement to use the equation.
Lr
* 0
The particular service time - bed length graphs in
-------
1200
iooo-
800-
£ 600
400-
200^
Figure 4-16 Service Time - Bed Length Curve For Adsorption of Butane on Activated
Carbon
-------
4-52
Figure 4-16 were determined from data derived from the efflu-
ent concentration curve in Figure 4-14 and data qiven 1n Appen«
dix E, i.e., at L - 2.4 cm, tb « 600 min, F « 0.223
5.06 x 10
-5
w
0.00738 g/cms and Ac « 0.502
C-j
Lc as calculated with Equation 4-25 and by extrapolation
Figure 4-16 is 0.57 cm.
cm*.
in
A relationship exists between Lz and Lc which makes it
possible to calculate Lc from LZ, if Lz and the shape of its
vapor concentration curve happens to be known. For low CD ,
I.e., when very little vapor penetration has occurred and Lz
is also measured to the same Cfc, the following relationship
holds with which Lc can be calculated:
[us -
AL
CZ
USACL(
or
(4-26)
The quantity /Ci over 0.01, the calcu-
lated Lc would be considerably larger than the correct Lc.
-------
4-53
Table 4-XIII Lc Calculated from Lz Using Equation 4-27
Lc, ctn
0.7 0.01 0.57
1.3 0.02 0.49
4.0 0.06 0.34
11.3 0.17 0.19
27.2 0.41 0.04
33.2 0.50 -0.01
Klotz Equation - Klotz did theoretical studies to es-
tablish a relationship between the vapor concentration dis-
tribution in the adsorption zone and the physical properties
of the gas and carbon. The equation involves two parts:
Lz Lt + Lr (4-28)
Lt 1s a function of the diffusion rate (mass transfer rate)
of the vapor from the gas stream to the exterior surface of
the carbon particles. The equation consists of known vari-
ables and has the form
L- 1s the function of processes occurrinq within the carbon,
such as diffusion rate of the vapor molecules alonq the pore
surfaces, accommodation of the molecules in the pores and
chemical reactions. A factor that can affect both parts is
the heat of adsorption, which can produce considerable rise in
the carbon temperature. While the adsorption 1s proceeding
at Its maximum rate, the increased temperature reduces the
adsorptive capacity, but»after the rate has subsided, the
capacity increases with the falling temperature. The overall
effect 1s a lengthening of the adsorption zone.
Lr has not been mathematically related to the properties
of the system but has been found to vary linearly with the air
velocity. The equation has the following form
Lr » 2.30 k Um log [C^Cb] (4-30)
Experimentally, 1t has been found that Lt 1s very small
for the smaller molecules of low boiling points while Lr is
relatively large. For example, Lt for the proceeding butane
adsorption is 0.08 cm, while Lz is 1.13 cm. Lr, by differ-
ence, Is then 1.05 cm. Therefore, the equation (4-28) has no
utility for predicting Lz of the low Vm vapors. For vapors
-------
4-54
of large Vm when adsorbed on coarse mesh carbons at high
vapor-air velocities, the mass transfer becomes rate con-
trolling, and Lz is nearly equal to Lt.
The shape of the vapor concentration distribution is
determined by log (C-j/Cb), as Ct is varied from essentially
zero to C-j. For these curves
V~ci
C X - AX TT
where X » log [Ci/C[j]. At C^/C^ = 0.1, 0.01 and 0.001, the
values for the above factors are 0.61, 0.77 and 0.85 respec-
tively. For the above discussed butane adsorption, the
factor at Cb/C-j = 0.01 is 0.50, considerably below the theo-
retical 0.77. This difference is due to the fact that the
Klotz' theoretical curve, as shown by the broken line curve
in Figure 4-15, is not sigmoid as is the one for the butane
adsorption. The Klotz1 theoretical shape curve is, however,
frequently observed in the adsorption of higher molecular
weight vapors.
Equation 4-29 (jives a good measure of the effects various
operating parameters have on Lt. The effects produced by
the parameters are:
1. Effect of particle diameter, Dp,
cm
2.
Lt - k DP"*> « k g (4-3!)
where a » C1'6]6. Lt increases rapidly with in-
creased Dp. Dp
Effect of vapor-air velocity. Um» cm/sec
Lt " k2 um°"*1 - k2 }'03 u°'"1 (^
where Um is the interparti cle velocity in cm/sec
and U is the face velocity in ft/min.
3.
Effect of Temperature
L I
, , 0 2 6 -" 0 6 7 r\ - 0 87
V P o
/.
(4-33)
The parameters produce opposing effects on Lt, but
the overall effect is a decrease in Lt with in-
creased temperature; y increases with temperature
-------
4-55
while p decreases, both producing an increase in
Lt. Dv increases with a rise 1n temperature pro-
ducing a decrease 1n Lt.
4. Effect of Pressure
Lt " k4 p"°*67Dv"0-67 (4-34)
An increase in total pressure decreases p and Dv,
thereby Increasing Lt.
5. Effect of molecular size. V cma/mol
Lt - k5 Dv-«-«7 (4-35)
The molecular size of the vapor affects only the
coefficient of diffusion Dv. Dv decreases with
increase in molecular size; hence, Lt increases.
Figure 4-17 presents three sets of curves which give Lz
1n Inches as a function of U measured in ft/m1n as calculated
with the complete Klotz Equation 4-28. In the fiqure, Dn «
0.35 cm is the mean particle diameter for 4 to 10 meshpcar-
bon, Dp » 0.24 cm for 6 to 16 mesh and DD « 0.12 for 12 to
30 mesh. V is the molar volume determined at 77°F. The
span, Including the 160, 110 and 60 cm3/mol V, covers the
molecular size range of pollutant vapors of interest. The
calculations were made for adsorption at 77°F and Ch/C< was
set at 0.01. ° 1
In order to use the equation for Lr, a numerical value
was required for k. In studies performed for NASA under
Lockheed Subcontract 28-5175, 1t was observed that k varies
W1th the vapor pressure of the liquid. For pollutant vapors
of Interest, an average value for k is 0.008, The contribu-
tion of Lr to Lz is small; hence, the accuracy of the numeri-
cal value of k is not significant.
When all fixed quantities are substituted Into Equation4-
28, the equation has the form
Lz * 0.80 Dp1-*1 U^^Cl/Dy]0'67 + 0.016 U (4-36)
To get approximate values for Dv, Equation 10.34, paqe
421 from Jost (1960) was used. When all necessary constants
or parameters for air are substituted Into the equation 1t
has the reduced form
7 ofi 1 |HL_*2i--.
' « < ° r-_ j m""i~n*tf I ' I (4-37}
-------
1.0 -
0.0 -
20
40 60
U, ft/mln
80
100
Figure 4-17 Effect of Gas Velocity, U, on Adsorption-Zone Length,Lz, for Carbons of
Mean Particle Diameter. Dpt and Vapor Molar Volume. V, 4 to 10 Mesh *
0.35 cm. 6 to 16 Mesh * 0°24 cm and 12 to 20 Mesh * 0.12 on.
-------
4-57
where Mi is the molecular weight of the pollutant and a is
the collision diameter of the pollutant molecule. a-| is
proportional to V as expressed by the equation
a} * 1.328 V1/s. (4-38)
Table 4-XIV gives V and Dy values for some of the most
frequently encountered pollutant or solvent vapors. Equation 4-
37 is a function of T1'*; 298°K has already been substituted.
Details of the procedure for calculating Lz are given
1n Appendix E, page E-10.
The curves in Figure 4-17 show that for the 4 to 10 mesh
carbons, L2 is longer than 2 inches at U over 40 ft/min, Since
coarse mesh carbons are used in thin beds, velocities are
maintained below 40 ft/min to avoid too great a loss of ca-
pacity. Since the factor
h "zl - 0.77
when Cfc/C-j » 0.01,
-------
4-58
Adsorption of Vapor Mixtures
The theoretical treatment of the adsorption process 1n
the prior text of this chapter deals with adsorption of a
single vapor. In actual practice, the gas phase invariably
consists of two or more components; the mutual effects of
the separate components requires further theoretical con-
sideration.
The simplest system consists of a carrier pas, usually
air, and the solvent (or pollutant vapor) as in degreasing
and dry cleaning. Air is so poorly adsorbed relative to the
solvents of concern that these gas mixtures can be considered
single vapor systems as far as adsorptive capacity is con-
cerned. This holds true with both polar and nonpolar adsor-
bents. However, water vapor is usually present, and in these
cases the gas phase is a ternary mixture. When the adsorbent
is activated carbon and the relative humidity is low, the
gas mixture can again be treated as a single vapor in re-
gard to adsortive capacity. At high relative humidities
water vapor causes interference although not in the same
manner as would be caused"by a mixture of organic vapors.
The presence or absence of water vapor is the deciding factor
in the choice of adsorbents. When water vapor is present,
adsorption of organic vapors cannot be effectively carried
out with polar adsorbents.
In air purification and recovery of solvents used in
surface coating, graphic arts, etc., mixtures of solvents are
used. These solvents are strongly adsorbed relative to each
other and thereby compete for the adsorptive capacity.
Displacement of Adsorbed Vapors - When an airstream
containing a mixture of organic vapors is passed through an
adsorbent bed, the vapors become separated along the bed
length. Vapors most strongly adsorbed are separated out
near the influent end of the bed and the less-strongly-
adsorbed ones separate out in successive bed length segments
in order of decreasing adsorbability. On continued adsorp-
tion, the more-strongly-adsorbed vapor displaces the less-
strongly-adsorbed ones. The least^strongly-adsorbed vapor
penetrates the bed first.
For polar adsorbents, the ranking of vapor adsorbabiH.
ties is given in Table 4-II. Water vapor heads the list,
hence would displace the less polar vapors lower in the 11st.
For nonpolar adsorbents, the ranking of vapor adsor-
abilities is more dependent on polarizability or molar volume
Table C-I lists most of the pollutant vapors in decreasing
order of molar volume, Vm, as measured at the normal boiling
-------
4-59
point. When there are large differences in Vm within the
mixture of vapors, each vapor with the larger Vm virtually
causes complete displacement of each vapor of lower Vm
When Vm are close together, displacement still occurs but
is accompanied by a considerable amount of coadsorption.
Profile of Adsorbed Vapors with no Coadsorption - The
profile of the adsorbed vapors in the carbon bed can be
readily calculated on the basis of material balance, esti-
mates of adsorption zone lengths from Figure 4-17 and esti-
mates of adsorptive capacities using the potential Equation 4-
19 and generalized adsorption curves of the type presented
in Figure 4-11 and -12. When no coadsorption of adsorbed
vapors is assumed to occur, the adsorption process is treat-
ed as though each vapor is adsorbed in a separate carbon bed
but with the beds placed in series. Figure 4-18 illustrates
the type of adsorbed-phase profile that is derived with this
assumption for a ternary solvent mixture (Table 1-XX) used
In spray coating operations.
The mixture selected for the calculations consists of
2-ethoxyethyl acetate, toluene and propanone at a total con-
centration of 500 ppm. This is the most probable concentra-
tion used in this operation. A 3,000 ft'/min flow was used
and bed area then sized to give a 110 ft/min air velocity.
Additional parameter data for the vapor-carbon system are
given in Table 4-XV. Details of the calculations are given
1n Appendix E, page E-12.
As shown in Figure 4-18, zones 1, 3 and 5 are saturated
bed lengths. In zone 2, 2-ethoxyethyl acetate is being
adsorbed while previously adsorbed toluene is completely
desorbed. Similarly, in zone 4, all of the influent and
desorbed toluene is adsorbed while previously adsorbed pro-
panone is completely desorbed. In zone 6, all of the influent
and desorbed propanone is being adsorbed. The zone lengths
and amount of adsorption in each zone are summarized in
Table 4-XVI.
By this procedure of estimating, an activated carbon
bed of 63 in. diameter and 28 in. length is required to com-
pletely adsorb the ternary solvent mixture at 3,000 ft'/min
flow and 500 ppm total concentration for an 8 hr service time
The diameter becomes fixed by the flow rate and the decision '
to operate at 110 ft/min velocity. The bed length is de-
termined by the type of vapors adsorbed, their concentrations
gas temperature and length of service time. This procedure is
the simplest to work out but gives an overestimate of the bed
length because of two factors which would have qiven a short
er estimated bed length had they been considered. These are
(1) coadsorption occurring 1n both the saturated and adsorption
-------
I
-------
4-61
Table 4-XV Selected Conditions for Adsorption of a Ternary
Solvent Mixture Used 1n Spray Coating Operations
Total concentration, C-j
2-Ethoxyethyl acetate
Toluene
Propanone
Solvent properties
2-Ethoxyethyl acetate
Toluene
Propanone
Total vapor-airflow, F
Vapor-air velocity, U
Vapor-air temperature
Carbon bed area, Ac
Carbon particle size
Carbon density
Service time, tk
t determined at
500 ppm
50 ppm
181 ppm
268 ppm
M
v(O
m
C0»ppm
132
92
58
135
106
73
163
118
74
3,400
37,000
290,000
3,000 ft3/roin
110 ft/min
25 °C
3,930 in.2
4 to 10 mesh; 0.35 cm
0.50 g/cm3; 0.0181 lb/1n.3
8 hr
Cb - 0.01 Ci
Table 4-XVI Summary of Adsorbed-Vapor Profile Data of
Figure 4-18
Zone 1,
2-Ethoxyethyl
acetate
Zone 2,
2-Ethoxyethyl
acetate
Zone 3,
Toluene
Zone 4,
Toluene
Zone 5,
Propanone
ws
JLz
1 wz
LWZ
w
LWI
i.
L, in.
0.5
3.6
4.1
3.3
13.2
4.1
12.7
2.9
4.1
14.8
51.6
9.6
54.2
(1) Molar volume V measured at 25°C.
-------
4-62
Table 4-XVI (Continued)
L, 1n. td. Ib/in.
Zone 6,
Propanone
L. 2.9
Totals 27.6
0.95
zone bed lengths, and (2) the rise 1n adsorptive capacities
in zones 3 and 5 because of desorptlon in zones 2 and 4
causing rises in vapor concentrations in zones 3 and 5. When
Vm are greatly different and the adsorbed liquids are quite
incompatible with each other, the estimated bed length 1s
not too greatly in error.
Profile of Adsorbed Vapors with Coadsorptipn - When co-
adsorption and the effects of desorptlon are taken Into con-
sideration, the adsorbed-phase profile can be considerably
different as is apparent when Figure 4-19 1s compared with
Figure 4-18. The zone lengths and amounts of adsorption in
each zone are summarized in Table 4-XVII to permit a compari-
son of the results of the two procedures. Details of the
calculations are given in Appendix E, page E-15.
Coadsorptlon is assumed to obey the following relation-
ships between adsorption vapor pressure and mol fraction of
the adsorbed phase:
For 2-Ethoxyethyl acetate[E] CT *]C0-\ C^d
Toluene [T] C2 « X2Co2 [wtJ
Propanone [P] C3 »
Here Ci , C2 and C, are the respective vapor concentrations
or partial pressures in the carbon bed. In Zone 1 they would
be the influent concentrations, but are different in the
following zones. X1 , X2 and X3 are the respective mol frac-
tions in the adsorbed phase. Col is the calculated equilib-
rium vapor pressure of E when the weight of adsorbed E 1s
assumed equal to the sum, [o>t3» of the actual adsorbed
weights of E, T and P. This Is also true for CQ2 and Co3.
Ci , Co and Co are known for zones 1, 3 and 5. C ., Cft? and
c'3 aPe calculated by use of Equat1on4-19 andthe°generSlized
adsorption curves of type given 1n Figure 4-11 . CQl, Cft~
and Cn-5 are determined at several [<>*] until one 1s found c
that yields XT + X2 + X3 « 1.0. X times [wtJ then determines
the amount us of each vapor adsorbed.
-------
20.0
->
15.0
10.0
5.0
Zones
2 -H 3 1*- 4 -*!
1
2-Ethoxyethyl acetate
Toluene
O.C
0
Fiaure 4-19 Adsorbed Vapor Profile 1n an Activated Carbon Bed After
Figure 4 .* ^ Established with Coadsorptlon
i
o>
ca
-------
4-64
Table 4-XVII Summary of Adsorbed-Vapor Profile Data of
Zone 1 -
Zone 2-
Zone 3-
Zone 4-
Zone 5-
Zone 6-
Figure 4-19
L*
, in.
'Ls °-6
us for E
ws for T
- us for P
Ws for E
Ws for T
,W$ for P
Total
"Lz 3.6
wz for E, average
wz for T, average
- wz for P, average
Wz for E
W2 for T
,W2 for P
Total
ws for T
us for P
Ws for T
.Ws for P
Total
"L2 3.3
-------
4-65
The length, Lz, of zones 2, 4 and 6 are determined from
Figure 4-17 and the average amount uz of each vapor adsorbed
1s determined by the factor,
i
« 0.77
as worked out for Equation 4-26. The amount uz remaining on
the carbon in zones 2 and 4 during desorption is determined
by the above factor when equal to 0.23.
The procedure for carrying out the many steps of the
calculation, as demonstrated in Appendix E, can be programmed
and carried out rapidly by a computer when many such calcula-
tions are required.
The Equation (4-39-41) was proposed by Grant and Manes
(1966). It is most accurate when applied to ideal solutions
such as might be approached by homoloaous series. Increased
deviation occurs with mixtures of dissimilar components.
The difference In bed length calculated by the two pro-
cedures is due primarily to the much larger wz when coad-
sorption is taken Into consideration. Coadsorptfon and de-
sorption produce a small increase in tos.
Under the conditions of these calculations,the coadsorp-
tion decreased the bed length from 27.6 in. to 20.6 in., or
255J decrease. When the mixture consists of very similar
vapors, such as the naphthas used in surface coatings, and
where the differences in Vm are small, coadsorption occurs
to the greatest extent. If the service time is shortened,
the Ls bed lengths decrease first and thereby the bed lengths
predicted by the two procedures diverqe more. Conversely,
for long beds or low air velocities the predicted bed lengths
converge.
Single Versus Mixture of Solvents - In surface coatings,
graphic arts, rubber products and other solvent user Indus-
tries, solvent mixtures are used to attain the desired vis-
cosity, solvent power and evaporation rate of the reactant
mixture. When solvent recovery is an important economic
factor, consideration should be given to the possible sub-
stitution of a single solvent for the mixture. Frequently
the single solvent vapor can be recovered in a smaller carbon
sorbent unit. To illustrate this, carbon bed lengths were
calculated to show the bed length required to adsorb each of
the previously discussed solvent vapors each at 500 ppm in-
fluent concentration. As shown below, the calculated bed
lengths required for single solvent vapors are compared with
ternary mixtures:
-------
4-66
Solvent ^
2-Ethoxyethyl acetate, singly at 500 ppm 13
Toluene, singly at 500 ppm 14
Propanone, singly at 500 ppm 24
Ternary mixture, no coadsorption, 500 ppm 28
Ternary mixture, coadsorption, 500 ppm 21
Resistance to Airflow
An important parameter that enters into the determina-
tion of the optimum L/D ratio is the airflow resistance of
the adsorbent bed. This information is generally available
in the sales literature of adsorbent manufacturers, but, 1f
not available, it can be estimated with the following equa-
tion (CEP, 1952).
(4-43)
By substitution of the fixed variables for air at barometric
pressure and 25°C, the equation 1s reduced to the form:
AP » 2.66xlO's Hllll + 1.02xlO-« Hill !il . (4-43)
e' Dp* e' Dp
AP is in inches of water per inch of carbon bed depth, U 1$
in ft/min and Dp in cm. The pressure drop is sensitive to
the intergranular void volume fraction, E, which varies with
the way the carbon is loaded into the adsorber and with the
mesh size distribution. For a tightly packed bed, e can be
as low as 0.30 and for a loosely packed bed as high as 0.45.
To show the variation the tightness of packing has on AP,
AP were calculated for e between 0.30 and 0,45, when U
40 ft/m1n and mesh size fraction Is 6 to 16 (0.24 cm Dp).
These results are as follows:
_e AP, 1n. H^O/in. carbon
0.30 0.51
0.35 0.28
0.40 0.18
0.45 0.10
The AP can vary five fold. If e decreases due to particu-
late matter lodged between carbon particles, the increase
In AP would be considerably greater.
-------
4-67
Regeneration of Activated Carbons
The preceding text of this chapter discusses methods
for analyzing the adsorption phase of the adsorption-regen-
eration cycle. In this part of the chapter a procedure Is
described for estimating the amount of regenerating agent
required to regenerate a spent activated carbon. In this
area considerable knowledge has been accumulated by the sol-
vent recovery systems designers and activated carbon manu-
facturers. This knowledge is quite limited to operations
that are profitable, i.e., concentrations generally above
1,000 ppm and recovery of the more common and more expensive
solvents. Air pollution control operations, however, cover
the concentration range from below 1 ppm to over 1,000 ppm
and include vapors that have no recovery valve. In the con-
centration range 10 ppm and over,regeneration of the carbon
1s an economic necessity in order for the adsorption systems
to be competitive with thermal incineration, catalytic In-
cineration or liquid absorption.
When no past experience data are available, the esti-
mating procedures for determining the carbon bed size and
regenerating agent requirements perform a valuable service
1n regard to economic analyses and preliminary choice of
type of control system best suited for the control problem
under consideration.
Desorption of Adsorbed Vapors - Figure 4-20 Illustrates
the adsorbed-phase profile of a single vapor at the service
time when the vapor has just started to penetrate the bed at
some predesignated concentration Ct>. This is the usual or
desired status of the system just prior to regeneration.
Figure 4-19 Illustrates an adsorbed-phase profile for a ter-
nary mixture. Its regeneration will follow the general pat-
tern observed in single vapor regeneration.
Figure 4-21 illustrates the progression of the adsorb-
ed-phase profiles as increasingly larger amounts of regen-
erating agent are passed through the bed in reverse flow
direction. The numbers do not Indicate equal time Intervals
nor equal amounts of regenerating agent. Adsorbed vapor at
profiles numbered 1 and 2 are easily desorbed requiring rel-
atively small amounts of agent. Increasingly larger amounts
of agent are required to desorb to profiles 4, 5 and 6.
With reference to the generalized adsorption curves, Figure
4-11, desorption at 1 and 2 is occurring at smaller A
values, while at 6 it is occurring at larger A values. In
terms of pore structure desorbed vapors at profile 1 and 2
are coming from micropores of larger diameter, while vapors
at 6 are coming from micropores of small diameter. For
reference, pore size distribution curves are presented 1n
-------
4-68
c
r-
«».
.O
m
3
30
20
10
Direction of
air-solvent flow
I I I I J I J^ I I I I I II I 1 lit ^Vj
10
L. in.
15
20 21.3
Figure 4-20 Adsorbed-Phase Profile for Trlchloroethene
at Service Time when Vapor Starts to
Penetrate Bed, BPL V Type Carbon
3
i i i I i lit
10
L, in.
15
20 21.3
Figure 4-21 Adsorbed-Phase Profiles for Trlchloroethene
at Various Stages of Regeneration, BPL V
Type Carbon
-------
Figures 4-1 and -2. Very large amounts of agent are usually
required to attain complete regeneration.
4-69
Procedure for Estimating Regenerating Agent Usage
"theoretical plate" approach 1s used In these estimates.
The carbon bed length is divided into theoretical segments
with thermal and mass transfer equilibria assumed to occur in
each segment as the gas mixture passes through. The hot gas
mixture entering the segment imparts heat and, according to
the modified Polanyi potential (4-19), I.e.,
[T/Vm] log [C0/C]
or as further defined
A - [T/Vn] log [C0/C], (4-44)
the temperature rise increases the vapor pressure C. The
released vapor is swept out of the segment causing an in-
crease in A. The rise in A registers the amount of vapor
desorbed. By a summation procedure the vapor transfer over
successive segments is determined as a function of the input
of regenerating agent.
Because of the complexity of the calculations, they are
done most efficiently by computer. To illustrate the pro-
cedure and supply data for economic analyses presented 1n
Chapter 6, regeneration calculations were done for three
solvents and four carbons after equilibration at four dif-
ferent influent concentrations. The steps for preparing the
computer programs and for carrying out the computations are
described 1n Appendix D.
Results of Regeneration Estimates - The calculations
cover steam and air as regenerating agents at the following
temperatures:
Steam at 212°F
Steam at 260°F
Air at 302°F (150°C
Air at 392°F (200°C
The results of the air regeneration are applicable to other
noncondensable gases. The three solvents Investigated are,
Trichloroethene
4-Methyl-2-pentanone
Propanone
They represent a wide range of adsorbabiHtles, essentially
bracketting most of the pollutants that are of concern. The
four carbons, listed below, were chosen to represent four
diverse types of generalized adsorption curves.
-------
4-70
Barnebey Cheney GI Type, density 24 lb/fts
Pittsburgh BPL II, density 31 lb/fts
Pittsburgh BPL V
Pittsburgh BPL VI
The GI represents a highly active carbon with pore structure
similar to S154, Type IV In Figure 4-1. The BPL Types II, V
and VI are the same carbon, but represent different gener-
alized adsorption curves (Figure 4-11 and -12) by different
investigators on greatly different types of compounds. The
Generalized Adsorption Curves II and V are representative of
most vapor phase carbons.
In regard to flows and bed dimensions the following
additional conditions are stipulated:
Influent flow, F 3000 ft'/m1n, stp
Influent flow velocity, U 110 ft/min
Bed area, Ac 27.2 ft2, 3930 in2
Bed length, L 21.3 1n. BPL, 23 1n. GI
Adsorption-zone length, Lz 3.3 in.
Carbon weight 1500 Ib
Mesh size 4 to 10
Figures 4-22, -23 and -24 present the calculated results
selected to illustrate some of the regeneration situations
that can arise during pollution control operations. Each
curve was calculated for a 1500 Ib carbon bed (I.e., L «
21.3 in. for BPL and 23 In.for GI) that had been exposed
(equilibrated) to the given concentration until the bed was
saturated to its entire length. The abscissa gives the mean
weight of adsorbed vapor remaining on the carbon after the
amount of regenerating agent,as given on the ordlnate, has
passed through the bed.
Necessary data are presented in the curves to permit
calculation of: (1) the total regenerating agent through-
put, (2) total amount of vapor desorbed, (3) total amount
of adsorbed vapor remaining on the carbon, and (4) amount
of regenerating vapor required to desorb a unit weight of
vapor. A typical problem would be the estimate of the re-
quired amount of 212°F steam to regenerate the carbon bed
on a one-hour cycle for trichloroethene at 3,000 ppm Influ-
ent concentration. From Figure 4-22, the saturation capa-
city is 0.363 Ib solvent/lb carbon or for 1500 Ib the total
amount of solvent 1n the carbon Is 545 Ib. To operate on
a 60 min cycle,180 Ib of the solvent must be desorbed on
each regeneration leaving 365 Ib on the carbon. The 365 Ib
gives an average 0.243 Ib solvent/lb of carbon. From Figure
4-22, the amount of steam required to desorb to 0.243 1s
0.30 Ib/lb carbon. Total steam requirement Is then 450 Ib
-------
4-71
TOO
10
o
.0
t-
«e
u
-o 1.0
e
to
Of
0.1
0.01
10 ppm
212°F steam
260°F steam
100 ppm
I I I I
1000 ppm
concentration
I
I .
3000
ppm
0.1 0.2
u, Ib solvent/lb carbon
0.3
Figure 4-22 Amount of Steam Required to Regenerate BPL V
Type Carbon Equilibrated with Trlchloroethene
at Varied Concentrations
-------
4-72
TOO F'r
>O
u
cr>
«o
j-
i.
1 TT
- 212°F steam
- 260°F steam
3000 ppm
concentratio
1000 ppm
^^MPMJ
I,.. I
L. I I
0.01
(i), 1b solvent/lb carbon
Figure 4-23 Amount of Regenerating Agent Required to Regen-
erate BPL V Type Carbon Equilibrated with Pro-
panone at Varied Concentrations
-------
looor
4-73
TOO
o
.0
s-
c
0)
o»
0.1
0.01
392°F
air
i
0.1 0.2 0.3 0.4 0.5
CD, Ib solvent/lb carbon
0.6
0.7
Figure 4-24 Amount of Regenerating Agent Required to Regen-
erate GI Type Carbon Equilibrated with 4-Methyl-
2-Pentanone at 10 and 3000 ppm Concentrations
-------
4-74
and the pounds of steam used per pound of solvent recovered
are then
0.30/CO.363-0.243] - 2.5.
For deep beds of 16 to 36 in.,this method gives a quick
but approximate method for estimating regenerating agent
requlrements.
Since most solvent recovery operations are carried to
service times at low vapor penetration, some adjustments are
required to take into consideration the effect of the adsorp-
tion zone. This can be done by programming the adsorption
zone Into the computer, or it can also be estimated from the
adsorbed-vapor profiles. The profiles shown 1n Figure 4-21
are for trichloroethene when the adsorption phase of the cy-
cle is at 3000 ppm concentration. They were read-out when
the computer was operating on the 3000 ppm curve 1n Figure
4-22 for 212°F steam. The computer calculated profile ex-
tends from L « 18 1n., In reverse direction, to L » 0 and
theoretically to L - -3.3 in. The parts of the profiles 1n
LZ are extropolations of the computer calculated curves.
The effect of Lz is that between 10 to 12 Ib additional
steam 1s required. The steam requirements for the L « 0 to
18 1n. profiles lengths are still the same as originally
calculated for L 21.3 1n. I.e., the efficiency of steam
utilization increases as the bed length 1s increased. To
determine the amount desorbed, the area under each profile
1s subtracted from the pounds adsorbed at the time of the
Initial penetration, I.e., when CD * 0.01 Cj. The total
pounds adsorbed comes to
Ls x ws + Lz x wz W,
where
» 0.77; 03, * 0.23 u>s
and 18 x 25.6 + 3.3 x 0.23 x 25.6 - 480 Ib
Table 4-XVIII summarizes the pertinent quantities calculated
from the profiles. The general pattern as established for
this solvent-adsorbent system appears in other systems. The
regeneration time, as given in Column 2, 1s calculated for a
steam flow rate of 250 fts/m1n measured at standard temper-
ature and pressure.
When Lz is taken Into consideration, 2.8 Ib steam/lb
solvent is required to desorb 180 Ib of trlchloroethene,
Profile 3. The regeneration time Is established at 40 m1n
and steam requirement at 500 Ib to recover the 180 Ib of
solvent per cycle.
-------
4-75
Table 4-XVIII Regeneration of Trichloroethene-Activated
Carbon System Based on Figure 4-21 Profiles
Regeneration Steam Solvent Lb steam
Profile time, min input, Ib desorb.,lb per Ib solvent
1 17 210 79 2.7
2 33 410 160 2.6
3 40 500 180 2.8
4 65 810 240 3.4
5 145 1820 310 5.9
6 640 8040 410 20
Operating Capacity - An examination of Figures 4-22,
-23 and -24, and the results of Table 4-XVIII show that the
amount of regenerating agent required increases rapidly as
desorption is carried closer to completion on each cycle.
In order to maintain a profitable solvent recovery operation,
the extent of desorption, now termed the operating capacity,
must be closely gauged to minimize the steam-to-recovered
solvent ratio. Table 4-XIX gives steam-to-solvent ratios
and operating capacities for the three solvents when the
vapor influent concentration is 3000 ppm and the adsorption-
regeneration cycle time is one hour. Two to four pounds of
steam for each pound of solvent recovered are considered
optimum ratios; 4-methyl-2-pentanone and trichloroethene fall
in this range with the particular sized system under discus-
sion.
The steam-to-solvent ratio of 6.1 for propanone recovery
is on the high side, It can be lowered by decreasing the
operating capacity, but to do this will require an increase
in bed size. There is, however, a limit to the extent the
bed size can be increased since steam requirements to heat
the carbon and associated hardware increase.
In these particular recovery operations the steam re-
quired to heat the bed to 212°F and supply the heat of de-
sorption is 80 to 100 Ib. This steam condenses and
remains in the bed. The balance of the steam, 200 to 400
Ib, serves as a sweep gas.
As the influent concentration decreases the service time
increases and the amount of regenerating agent required also
increases. In Table 4-XX this type calculated data are pre-
sented when the influent concentration is 10 ppm. The steam.
to-solvent ratio for each vapor comes to a minimum at some
operating capacity. For 4-methyl-2-pentanone the minimum is at
0,025 Ib/lb operating capacity, for trichloroethene at 0.025 lb/
Ib and for propanone at 0.005 Ib/lb. The service time 1n each
-------
Table 4-XIX Estimated Operating Capacities and Steam Requirements for Recovery of
THchloroethene, 4-Methy1-2-pentanone and Propanone for a One-Hour
Adsorptlon-Regeneratlon Cycle Time, Carbon Equlllbrated at 3000 ppm
Solvent
4-Methyl-2-pentanone
THchloroethene
Propanone
(1)
140
98
74
Solvent
desorb.,Ib
135
180
80
Steam
used, Ib
360
450
490
Lb steam per
Ib solvent
2.7
2.5
6.1
Operating
capacity,
Ib/lb
0.09
0.12
0.05
(1) 4-Methyl-2-pentanone adsorbed on GI type carbon and the other two solvents
on BPL V type carbon.
-------
Estimated Steam Requirements to Regenerate Carbons* * Equilibrated with
4-Methyl-2-
Concentrati
Solvent (Pollutant)
4-Methyl-2-pentanone
Trlchloroethene
Propanone
pentanone, Trl
on and at Vari
Operating
cap., Ib/lb
0.01
0.025
0.05
0.16
0.01
0.025
0.050
0.092
0.0025
0.005
0.010
0.014
chloroethene and Propanone at 1
ed Operating Capacities
Service
time, hr
33
82
163
610
25
62
125
230
14
28
56
100
Solvent
desorb. ,1b.
15
37.5
75
---
15
37.5
75
»
3.75
7.5
15
v «
, 212*F
Steam
used, 1
1200
3000
9000
" *"
1950
4500
12700
m m~
1300
2400
5000
"
0 ppm Influen
Steam Used
t
Ib steam per
b Ib solvent
80
80
120
**
130
120
170
340
320
400
"* *
(1) All calculations are for BPL V type carbon
£»
I
VI
-------
4-78
case 1s sufficiently short so that steam regenerations, even
though large amounts of steam are required, are much less
costly than carbon replacement and reactivation. The longest
service is for 4-methyl-2-pentanone at 0.16 Ib/lb saturation
capacity. The 610 hr at 24-hr days is equivalent to a one-
month service time.
When the influent concentration is down to 1 ppm
the pollution control operations change. At this concentra-
tion it would take about one year to equilibrate the carbon
with 4-methyl-2-pentanone. The cost of steam regeneration
is at the same cost level as carbon replacement and reacti-
vation.
Selection of Regenerating Agent - As the results pre-
sented in Table 4-XX show, the amounts of steam required for
regeneration are large relative to the amounts of solvent
desorbed. Miscible solvents (or pollutants) as represented
by 4-methy1-2-pentanone and propanone are completely dis-
solved in the large amount of steam condensate. Their re-
coveries by distillation are not economical, thereby creating
a disposal problem if water pollution is to be avoided. In
these cases the solution to the problem is to regenerate the
carbon with a noncondensable gas and burn the released vapors
immediately 1n a small thermal incinerator. If the amount
adsorbed is small so that the release rate never exceeds 25%
LEL, then air can be used as a regenerating agent; otherwise*
an inert gas such as flue gas would be safer. By the pro-
cedures already demonstrated, the noncondensable agent re-
quirements can be calculated. The cost of using nonconden-
sable gases is lower than that of steam since no fuel is re.
quired for latent heat of vaporization.
When the condensed vapor 1s Insoluble 1n the steam
condensate, or slightly soluble as is trichloroethene, com-
plete or partial separation of the organic liquid 1s then
possible by decantation.
When the desorbed organic liquid 1s soluble, but on
thermal Incineration would repollute the air, as by release
of SOg. HC1 or N02i the problem of pollutant disposal becomes
more difficult.
At higher influent concentrations where the steam-to-
solvent ratio decreases, the advantages of using nonconden-
sable regenerating agents decrease. In the concentration
range where solvent recovery is practiced, steam is the only
practical regenerating agent.
-------
4-79
Some calculations were carried out to determine the
performance of 260°F steam. The general conclusions are
that in the high concentration range, above 1000 ppm, it
offers very little advantage over the use of 212°F steam.
At times the use of 260°F steam serves a useful purpose for
the periodic removal of high molecular weight molecules,
which when present in the airstream, accumulate in the in-
fluent end of the carbon bed. When regeneration with 260°F
steam is carried to low solvent contents, the steam condensed
in the early part of the regeneration is vaporized leaving
a dry carbon bed. It then behaves as a noncondensable gas
but is more costly to use than air or flue gas.
Generalization on Adsorbent System - The results of
the calculations on adsorption and regeneration discussed
in this chapter were used to work up the costs of operating
adsorbent systems. These costs were compared to those for
the competing systems, thermal incineration and catalytic
incinerations. A number of generalizations were arrived at
in regard to the circumstances under which each system might
be used advantageously. These generalizations are presented
1n Chapter 1, pages 20 to 24.
-------
5. Theories and Types of Catalysts
Background
Terminology
The general characteristics of the process termed
"catalysis" were outlined by Berzelius. In 1835, he codified
most of the chemical reactions developed to that time and ob-
served that many reactions were affected by the presence of a
nonreacting substance. The process appeared to be initiated
by a "catalytic force" which separated or broke down the re-
actants prior to the chemical reaction. He used the term
"catalyst" to define that substance whose presence affected
the rate of a reaction while remaining essentially unchanged
itself.
Modern scientific technology has significantly altered
the "catalytic force" concept proposed to explain catalysis.
The fundamental principles of catalysis are being gradually
unveiled through the combination of modern analytical instru-
mentation, continued research and the correlation of previous
data. Mechanisms and theories describing the process of ca-
talysis continue to evolve as the result of these investiga-
tions.
Development
Although catalytic reactions have been used for over a
thousand years, theories describing these reactions have been
actively developed only during the last sixty years. The
works of Freundlich (1915), Langmuir (1918) and Sabatier (1920)
have been used as the foundation for most of these theories.
Catalysis has a dual nature involving both physical and chemi-
cal aspects which have stimulated much of the research to-
wards a description of its complex nature.
Description
Three factors have been established as criteria for de-
scribing catalysis: (1) the catalyst remains chemically un-
changed, (2) the reaction rate can be correlated to the a-
mount of catalytic reaction surface, and (3) the catalyst
does not affect the equilibrium concentrations. Examples of
catalysts, which conform to these criteria, are available for
solid, liquid and gaseous states, with both positive and
negative influence on the chemical reaction. A concise defi-
nition and evaluation of the theories and types of catalysis
can be found in Kirk-Othmers' Encyclopedia of Chemical Tech-
noloj
-------
5-2
Air pollution control systeirs are almost exclusively
confined to solid-gas, or heterogeneous contact catalysis.
The definitions, formulae and cursory examinations of theo-
retical models presented in this chapter pertain to hetero-
geneous catalysis.
Reactions of gases at a solid catalyst surface present
one of the more important alternatives available for air
pollution control. However, it is necessary to understand
and use some theoretical models and mechanisms to discern
its prominence in pollution control systems.
Theoretical Models
Types
The prominence of surface and surface effects in hetero-
geneous catalysis is evident in the theoretical models de-
veloped to describe these reactions. Theories of catalysis
fall into four general categories: (1) geometric, (2) elec-
tronic, (3) boundary layer and (4) crystal field. Research
and development of theoretical models for catalysis have
lagged behind the applications of catalysis, but have been
instrumental in its recent growth.
The general idea in each of the theoretical models has
been a more thorough elucidation of the "chemisorbed inter-
mediates" proposed by Sabatler (1920). The successes attain-
ed by these various models have increased the use of catalysts
and opened such fields as air pollution for their application.
Geometri c
Geometric models for describing catalysis rely heavily
on Langmuir's (1918) adsorption theory and surface area
measurements by Emmett and Brunauer (1937) and Brunauer,
Emmett and Teller (1938). Correlations between molecular or
atomic volume and surface area or pore sizes were made to
evaluate and predict catalytic activity.
Thlele (1938), Weisz (1954) and Wheeler (1951) did ex-
tensive work 1n this area. Wheeler (1955) derived the
equation
h - 6\/K/rDv (5.!)
to relate the reaction kinetics, pore size, surface area,
catalyst specificity, apparent reaction order and poisoning.
Balandin (1929) studied dehydrogenation and Beeck (1950)
studied hydrogenation in relation to the geometry of various
metal catalysts which engendered useful correlations.
-------
5-3
Electronic
Dowden and Reynolds (1959) are primarily responsible
for the development of the electronic theory of catalysis.
Catalysts are classified as conductors, semiconductors or
Insulators. This theory proposes the slow transfer of elec-
trons between catalyst and adsorbate as the rate determining
step.
Boundary Layer
Recent work in catalysis has concentrated on the geo-
metric and electronic states of surface layers only, bringing
it into the realm of the boundary layer theory. The influence
of surface defects, dislocations, holes and terminal surface
atoms has been suggested by many researchers. These reactive
centers have been used successfully to describe many types of
adsorption.
Crystal Field
The partial success of electronic and boundary layer
theories has been used as the basis for applying the crystal
field theory. As proposed by Dowden and Wells (1961) and
elaborated by Mango and Schacktschnelder (1967), this theory
has proven satisfactory for those few systems for which the
detailed quantum mechanics of surface atoms can be calculated.
Adsorption
Description
Adsorption of gases on solid surfaces is one of the
primary steps involved in catalysis. Its fundamental and
unique character requires some explanation before attempting
any evaluation of catalytic processes.
Heterogeneous catalysis requires at least one of the
components to be adsorbed on the catalyst surface before
chemical reaction can occur. This adsorption concentrates
atoms at the interface between the two phases and decreases
the free energy of the surface. The free energy decrease or
entropy loss makes the process exothermic. The energy re-
leased during adsorption is available for the catalytic re-
action (activation energy).
Theoretical Principles
Since adsorption 1s a basic part of catalysis, some dis-
cussion of theory is applicable. The adsorption isotherm
developed by Langmuir (1918) has traditionally been used as
-------
5-4
the basis for adsorption models. His premise of kinetic and
surface limiting factors has been established by many re-
searchers. The equation is derived from the kinetic theory
of gases:
dn - KMS6, to give e »
-------
5-5
for catalyzed systems have been reviewed by several authors.
Kougen and Watson (1943) developed mathematical expressions
to describe catalytic reaction mechanisms. Yancr and Hougen
(1950) presented a summary of experimental methods and mathe-
matical expressions for determining rates and mechanisms.
Similar work has been reported by Corrigan (1954), Hwang and
Parravano (1967), Otake, Kumiqlta and Nakao (1967) and Lin
(1969). Brodski et al. (1967) have also discussed methods
for determining the accuracy of theoretical mechanisms on
the basis of kinetic data.
Mathematical descriptions of reaction rates have been
developed empirically by Arrhenius:
K A exp E (5-6)
and from statistical mechanics by Eyring:
K « A RT exn AS* exn '-'AH* (5-7)
K A NTT exp IT exp FT ' * ;
The accuracy of these absolute reaction rates can always be
improved by more complex notations Involving more constants
and requiring sophisticated mathematical treatment.
The general results obtained from these equations pre-
sent an interesting paradox in the evaluation of catalytic
systems. If these equations are used to calculate the ratio
of heterogeneous and homogeneous reaction rates, the cataly-
tic reaction rate appears considerably smaller. By making
similar assumptions in the calculations of reaction rates,
1t can be shown that the ratio
Kheterogeneous ^ 10-io to 10-is exp AE/RT.
^homogeneous
In actual practice this theoretical deficit is sur-
mounted by the decrease in activation energy and the use of
large surface area catalysts. This rati.o denotes the sig-
nificance of the relative activation enerqies for catalyzed
and uncatalyzed reactions. It follows, therefore, that cata-
lysts which strongly adsorb the reacting species perform best.
Extraneous interferences may occur in three areas which
render these rate calculations inoperable for some applica-
tions of catalysis. Reaction chains, extraneous chemical
interactions and catalyst attrition affect the reaction rates
but do not conform to simple time functions.
-------
5-6
Thermodynamics
Thermal calculations require data from four general
areas: (1) heats of reaction, (2) heat transfer coefficients,
(3) reaction rates and (4) thermal properties of system. These
data permit the calculation of heat release as a function of
the catalytic reaction.
A volumetric heat release, for the reaction in the cata-
lyst bed, can be described as:
q/Vcat « X'Q.t.Ppollutants (5-8)
Hlavacek (1970), Wilhelm, Johnson and Acton (1943) and Lin
(1969) have published different mathematical solutions to
this proportionality.
By assuming isothermality over small integrated sections
and a linear variation of the reaction rate, Wilhelm, Johnson
and Acton (1943) have generated the equation:
ld«" (5-9)
for small, cylindrical sections of the catalyst bed. In this
calculation, HQ is the value (q/Vcat) for the initial re-
action of the "clean" catalyst in equation (5-8). Hj Is the
rate of change of (q/Vcat) as the catalytic reaction pro-
gresses; r 1s the radius of the catalyst bed and Al 1s an
incremental length.
Heat Is lost from these sections of the catalyst by two
mechanisms: (1) radial conduction equal to
-2irrAU[dT/dr],
where K Is the thermal conductivity, and (2) volumetric con-
vection equal to
2irrAJtKf[Tsol1d-Tgas]dr,
where Kf is the film heat transfer coefficient.
Equating the heat generated and lost through this cylin-
drical section generates the Identity:
rr
-2irrAA K ^1 + J 2irrAl Kf (Tsond"Tgas )dr (5-10)
-------
5-7
Equation (5-10) may be used to describe any thermal change
occurring in the system.
Solutions to these general equations form a series of
curves or parabolas depending upon the system parameters. If
appropriate data are available for the system, solutions can
be obtained for the rate of heat release and reaction temp-
erature. Additionally, residual or equilibrium concentrations
can be predicted.
Types of Catalysts
Although many substances can be prepared to act as cata-
lysts, only two types are prominent in the heterogeneous re-
actions prevalent in air pollution control. Noble metals,
such as platinum, are the most efficient and commonly used
metal catalysts. Transition metals, such as vanadium, are
the second type.
Noble Metals
The noble metal catalysts (platinum, palladium, gold
and silver)are usually deposited on an inert support to in-
crease the exposed surface area. They are most efficient for
catalyzing the oxidation reaction of hydrocarbons and maintain
their reactivity to high temperatures.
These catalysts are susceptible to poisoning reactions
with acid gases and erosion by particulates in the gas stream.
Depositing them on metal carriers does, however, increase
their resistance to abrasion.
Transition Metals
The most common transition metal catalysts include:
vanadium, nickel, iron, cobalt, manganese and copper. Both
the pure metals and thin oxides have catalytic properties
which may be used in air pollution control systems.
Transition metal catalysts may be poisoned by absorption
of inert gases, chemical reaction and erosion. Although they
are easily poisoned, their lower cost and greater versatility
are an advantage for air pollution control systems.
Methods and Parameters Used to Evaluate Catalysts
Catalysts vary in their reactivity and efficiencies for
oxidizing the various air pollution emissions. Many of the
parameters used to evaluate catalysts are dictated by the
operating conditions of a particular process.
-------
5-8
Optimum properties of a catalyst include: hiqh deactl-
vation temperature, resistance to poisoning, low initiation
temperature and high efficiency. Although these criteria
remain unchanged for all catalytic reactions, the means for
obtaining the desired characteristics change with reaction
type, reactants and reaction media.
Various catalysts have been studies by Anderson (1961),
Stein (1960) and Dmuchovsky (1965) to define the "best"
catalysts for effective oxidation of pollutants in terms of
the above parameters. In general, the noble metals are the
most efficient for hydrocarbon oxidations. The transition
metals follow in the order: Co>Cr>Mn>Cu>Ni>V>Fe>Ti>Zn.
Catalytic activity is usually insensitive to the amount,
chemical composition or the type of support used. The ac-
tivity of metals deteriorates at elevated temperatures, and
any catalyst selection must be made with thought of both
efficiency and attrition at the operating temperature. After
the selection of the catalyst, only the surface area and
temperature are variable.
Unfortunately, the development of an optimum catalyst
for a given set of conditions is not as yet relegated to the
realm of scientific selection. Most of the synthetic work
is proprietary with manufacturers and has not received much
scientific correlation. In addition, the codification of
catalysts is complicated by the combination of physical and
chemical aspects which usually make the rate and products
unique for each catalysts-reactant system.
-------
6. Package Sorption Systems
Introduction
The study of sorbent types and so'ption theories, as
presented in Chapter 4, demonstrated that, of the several
types of adsorbents available, activated carbons are better
suited for gaseous air pollutant control than the others.
Polar adsorbents such as silica gel, alumina gel and mole-
cular sieves, adsorb water preferentially to the organic
vapors while, conversely, activated carbons adsorb organic
vapors preferentially to water vapor. Since moisture is
invariably present in pollutant airstreams, only activated
carbons can function effectively over any practical length
of time. Activated carbons have an added advantage in that
their adsorptive capacities are also larger for the organic
vapors. The quest for adsorbent systems suitable for air
pollution control thereby narrowed down to systems using
only activated carbon. Polar adsorbents can be of limited
Interest in the adsorption of inorganic add vapors or
where the airstream 1s dry.
Activated carbon adsorbent systems, as presently manu-
factured for industrial and commercial uses, are oriented
toward "air purification" and "solvent recovery". In the
air purification application, the objective is to remove
pollutants at trace level concentrations (1 ppm or less) to
make the air suitable for breathing purposes. In the solvent
recovery application, the adsorbent system is used to recover
a solvent from a process exhaust stream. Profitable recovery
is attained at concentrations above 500 to 1000 ppm, the
lower level depending on the value and adsorptive properties
of the solvent. The technology associated with these two
applications is designated as "present technology" in this
handbook and is discussed in considerable detail 1n this
chapter.
Pollutants are, however, emitted into the atmosphere
at concentrations ranging from less than 1 ppm to over
10,000 ppm. The concentration range from 1 to 500 ppm (the
neglected range under present technology) is an important
range in regard to pollutant emissions. Much of the "new
technology" is concerned with development of control systems
and procedures for this concentration range. These develop-
ments are also discussed in considerable detail in this
chapter with emphasis on theoretical support for the various
concepts proposed.
-------
6-2
Both the air purification and solvent recovery systems
are also suitable for applications where the primary objective
is the purification of air exhausted to the atmosphere. Air
purification systems would be effective where the pollutants
are emitted at very low concentrations but need to be controlled
because of their highly malodorous or toxic nature. These
systems are cost effective only at low concentrations because
of their nonregenerative design. At concentrations above a
level somewhere in the range 1.0 to 10 ppm, the cost of more
frequent carbon bed replacements would raise the air purifi-
cation costs to levels above those of competing systems. Sol-
vent recovery type systems in basic design are regenerative
systems wherein the activated carbon bed can be regenerated
within the system. At concentrations above 10 ppm, these
systems purify air more economically than the nonregenerative
type and their development, strictly for pollution control,
forms the basis of the "new technology". Activated carbon
regenerative systems whether for pollution control or solvent
recovery are designated In this handbook as carbon resorb
systems.
Basic Functions
Table 6-1 presents the overall pattern of air purifi-
cation and pollutant emission control in regard to pollutant
concentration, odor level and emission sources. The types
of pollutants encountered at the various levels that require
control vary considerably and thereby the mode of control
also varies.
In the concentration range below 1.0 ppm, the primary
concern is with pollutants that are highly odorous or to
some degree toxic or those that are oxidants as In smog.
Pollutants of this type originate from combustion of fuels,
incineration, and process industries such as meat rendering.
Some industries emit reactants such as carbonyl chloride
which are toxic at very low concentrations. Occupied spaces
such as kitchens, bathrooms, offices, conference rooms,
theaters and hospitals quickly develop malodorous atmo-
spheres if not properly ventilated or the air purified by
some means.
Solvents used by the solvent user Industries do not
contribute significantly to the low concentration odor prob-
lem except when the solvents are reactive to solar radiation
and thereby contribute to smog formation. Except for 4-
methyl-2-pentanone and xylene, solvents have odor recogni-
tion threshold concentrations that are over 5.0 ppm and TLV
over 25 ppm; see Table 2-IV for odor and Table 2-III for TLV
Toluene and xylene, the solvents emitted 1n largest quantl- *
ties, are highly reactive smog precursors, see Table 2-VIH.
-------
Table 6-1 Correlation of Pollutant Concentration with Odor level. Emission Source,
and Type of Adsorbent System Required
Pollutant cone.,
PPM
0.05 to 0.1
0.5 to 1.0
5 to 10
50 to 100
500 to 1,000
5,000 to 10,000
50,000 to 100,000
Qualitative odor
level
Moderate odor
Heavy odor
Heavy odor
Moderate odor
Heavy odor
Intolerable for
continuous ex-
posure
Intolerable and
deadly even for
Intermittent ex-
posure
Emission sources
Seldom used space, non-
airconditioned offices
Highly polluted outdoor
air, conference rooms
Emissions from process
industries
Industrial plants
Solvent emissions from
Industrial operations
Solvent emissions from
industrial operations
Safe only in closed cycle
operations with inert
atmosphere
Control device
Air-
" purification
Carbon-
resorb
systems
Solvent-
recovery
en
i
-------
6.4
The basic function of control devices applicable in the
low concentration range is to purify the indoor air and/or
impure air brought in from outdoors so that it will be safe
for breathing. The control devices used for this purpose
are designated in this handbook as air purification systems.
When the would-be pollutant is a valuable solvent and
is emitted in the 500 to 10,000 ppm concentration range, it
is usually profitable to recover it for reuse with a solvent
recovery system using steam for regeneration. Although the
motivation is solvent cost sayings, the solvent recovery
system also functions as an air pollution control device.
However, many solvent using operations utilize no control
devices. In such cases the odor level can be very strong
near the emission sources. On dilution with air mass move-
ments, the concentrations become low enough to become non-
detectable as odors. This point is reached with many sol-
vents at 100 ppm and almost all solvents are nondetectable
at 5 ppm.
A third concentration range extends from about 5 to
500 ppm. At the lower end of the range, the detectable and
also offensive odors are those from meat and fish rendering
plants, from incomplete incineration of refuse, from waste
water treatment plants or any process where thermal or bio-
logical degradation takes place. At the upper end of the
range, the pollutants are primarily solvents within the
plant or neighboring areas to the plant. Pollutants In this
(5 to 500 ppm) concentration can reach inhabited areas and
cause damage to humans and property. Prevention of pollutant
emissions here Is a direct cost to the pollutor with the
benefit of purer air going primarily to the neighboring
inhabited areas; hence, their reluctance to spend funds for
this purpose. This is the pollutant control area that re-
quires considerable study to solve the many problems associ-
ated with it.
Air Purification Systems. Present Technology
General Discussion
Air purification is generally carried out in a partially
closed system, i.e., the carbon-purified air is redrculated
into the occupied spaces. When the air purification device
is an Integral part of the air conditioning system, make-up
air from outdoors is added to the recirculating airstream
in quantities ranging from 0% to 25% of the total volume.
To maintain the C0£ concentration below 1.0% - the upper
acceptable concentration level - outdoor air (with CO? con-
tent of 0.03%) is required at make-up rate of 2 ft'/mln per
-------
6-5
person at rest and at 5 ft'/roln pt«r person at work. This
establishes the minimum make-up air Input rate when the
space per person ratio 1s relatively small. In large spaces
where occupancy Is small and 1nterm1ttant, make-up air may
not be required to maintain a low C02 concentration level.
A make-up air Input rate of 5 ft'/wln per person 1s
also sufficient to maintain the oxygen concentration above
the 17* lower allowable limit.
If humidity and temperature are controlled by dryer and
cooler outdoor air, the make-up air rate would be larger than
the 5 ft3/m1n per person as required for C02 control.
When the heating and/or cooling of the occupied spaces
are a function of the ventilating system, the air redrcula-
tlon rate would be determined by their requirements. The
reclrculatlon rate thus established also determines carbon
bed area. For low pollutant emission rates the bed area
thus determined may be larger than necessary.
Recommended fresh air or purified redrculated air
requirements for general offices are 15 ft'/m1n per person;
for private offices, 25 ft*/m1n per person; and for factor-
ies, 10 ft3/ro1n per person. The minimum requirement for
factories 1s 0.10 ftvmln per square foot of floor area or
as governed by local codes (Perry Chemical Engineering Hand-
book, 1963). According to ASHRAE (ASHRAE Handbook of Funda-
mentals, 1967), the recommended fresh air or purified reclr-
culated air to an occupied space with considerable air pollu-
tion as by tobacco smoke 1s 15 ft'/mln per person*
-------
6-6
The above analysis establishes the redrculatlon rate
at a minimum of 15 ftj/m1n which Includes at least 2 ftj/m1n
of outdoor air. Large auditoriums seating 2,000 people
would then require an air purification device that can
purify 30,000 ft'/min of air. For a small room 1n a home,
the other extreme 1n size, the required air handling capacity
would be about 50 ft'/min.
Figure 6-1 presents a flow diagram of a central ventila-
tion system that incorporates the carbon bed and particulate
filter elements as integral parts of the overall system. Not
shown are the heating and/or cooling elements that are usually
required. The ventilation systems may be one of earlier
installation to which the particulate filter and carbon bed
are attached. It is then necessary to find Installation
space for the air purification elements and also install a
larger blower to overcome the added airflow resistance.
When no central ventilation system exists or It is
not feasible to make the Installation of the air purification
elements, air purification for the occupied space can still
be accomplished with a self-contained unit or true package
sorbent device. These consist of a cabinet with Influent
and effluent airflow grilles, a blower, particulate filter
and the carbon bed.
Small air purification devices consisting of one or
two radial flow canisters and a blower are available for
very small rooms.
Carbon Bed Designs
Common Characteristics - The carbon beds 1n air purifi-
cation systems have very low L/D or L/Ac ratios. L/D 1$ of
the order of 0.01 where D is expressed as the diameter of a
circular bed of area Ac. For comparison L/D for solvent
recovery systems are of the order of 0.1. L 1s very short
or more appropriately stated as being thin; depths of 0.5,
0.75, 1.0, 1.5, 2.0 and 3.0 1n. are 1n frequent use. Bed
areas are sized to control the airflow velocity 1n the 20
to 60 ft/m1n range with most units operated at about 40 ft/
min. Coarse mesh carbons of 4 to 6, 4 to 8 and 4 to 10,
fractions are used. The thin bed, the relatively low air-
flow velocity and coarse mesh all contribute to low airflow
-------
6-7
Occupied spaces
V
Ducts
V
Impure
Ducts
Pure
air
->
Blower
Particulate
filter
Carbon
bed
Outdoor make-up air
Figure 6-1
Central Ventilation System Showing Particulate
Filter and Carbon Bed for A1r Purification
resistances which are generally below 0.25 1n. of HoO pressure
drop. An exception to the above are the air purification
systems used 1n chemical-bacteriological-radiological (CBR)
warfare service. Beds are thicker, usually 1.0 In. and over,
and mesh size ranges are 6 to 8 and 12 to 30. Consequently
the pressure drop 1s over 0.25 1n. of HgO. Safety against
toxic agents 1s the overriding factor.
The thin, expanded-area carbon beds are attained by
retaining the carbon between reinforced metallic screens or
perforated sheets that are spaced apart to give the desired
bed depth. The retainer can be shaped Into various
forms to provide advantages or economtes in the
assembly, operation and replacement of the carbon bed. The
retainer can be 1n the form of a rectangular panel, also
designated as a cartridge or tray. A number of the panels
are Inserted into a cell having a designed air-handling
capacity of some definite flow volume such as 500, 1000 or
2000 ftVmln. The retainer can also be one continuous piece
folded back-and-forth or pleated across the depth of the cell.
-------
6-8
The fold at each end can be rounded OP v-shaped. Another
approach, a carry-over from the gas mask, 1s the use of
radial flow canisters. A number of canisters are attached
to a manifold within the cell.
The cell is a unit of fixed or recommended capacity
which can be combined with others to form a multiple cell
unit of any desired total capacity. The multiple cell unit
may be held together in a frame and inserted into the ven-
tilating duct, thus appearing as an enlargement of the duct.
In large installations, the multiple cell units are usually
located in large walk-In cabinets or rooms. A very small
air purifier may only consist of a small blower and one or
two radial flow canisters.
Different manufacturers or fabricators specialize 1n
one or more of the types of cell constructions described
above. A list of carbon adsorbent systems manufacturers
and/or vendors 1s given later in this chapter.
The following text briefly describes the various types of
carbon beds commercially available.
Panel and Pleated Carbon Beds - Figure 6-2 Illustrates
a nine-cell carbon filter, a cross-sectional side view of a
cell and two carbon panels. The dimensions of the panels
produced by different fabricators vary some, but are gen«
erally in the ranges 2 by 2 ft, 2 ft by 8 in and 1 ft by
8 1n. The cell front Is usually 2 by 2 ft and depth varied
from about 2 ft to 8 1n. The number of panels per cell can
vary from 10 to 24. Carbon loading for a cell varies be-
tween 45 to over 95 Ib per 1000 ft'/min airflow rate.
Ease of removal and replacement of the carbon bed 1s an
important consideration in regard to operating costs. With
this type cell the carbon panels can be readily pulled out
and replaced by simply removing the front grille which holds
the panels in place. Seals are not a critical problem ex-
cept for the CBR filters. In some carbon filters, such as
used in some toxic agent air purification systems, the panels
are parallel rather than slanted toward each other.
Figure 6-3 shows one type of CBR filter for a small
protective shelter. The carbon bed area is one square foot,
hence at the 48 ft3/tn1n flow the air velocity is 48 ft/m1n.
This filter meets the shelter requirements of up to 12
people, which gives a minimum purified air change of 4 ft1/
min per person.
-------
6.9
Carbon filter /
Bed
depth
\
\
Side view cross
section of
cell
Carbon panels
Moure 6-2 Multiple Cell Activated Carbon Filter for A1r
8 Purification
-------
6-10
Figure 6-3 A Chemical-B1ological-Radiological Filter S1?P
12 by 12 by 8 1n'.. Operated at 48 ft9/mfn'for
Small Protective Shelters. Courtesy MSA Co.
BPACINO MMOER»
TOCAIMKXM BCD
PERFORATED METAL
(2* GAGE IN CARBON STEEU)
(2» OAOE IN STAIIslLESS STEEL)
NON PERFORATED METAL
(I" MARGIN)
SEPARATE PLEATS TO
RETARD SETTLING
NON PERFORATED BAFFLE
FLAIsKjC TO SEAL AGAINST
NEOPRENE PAD
OED DEPTH (MIN. I")
SPONGE NEOPRCIS4C PAD TO
PREVENT BYPASSING OF AIM
SPONGE NEOWteNC FACCOASKET
Flqure 6-4 Pleated Type Carbon Filter for Control of
Radioactive Pollutants, Size 24 by
11.5 In., Operated at
Courtesy of MSA Co.
1000 ft'/mln
24 by
Fl ow.
-------
e-n
Dimensionally the pleated carbon beds are not qreatly
different from the panel type. Fiqure 6-4 shows the qeneral
exterior appearance and a cutaway section shows the inter-
nal construction. This carbon filter or cell is of partic-
ularly ruqqed desiqn for use in nuclear reactor facilities
to control radioactive pollutants that miqht be released
accidently. Its operating capacity is 1,000 ft3/min at 1.0
in. of water pressure drop and pollutant removal efficiency
qreater than 99.99%. The cell size is 24 by 24 in. front
dimensions and 11.5 in. deep. With 12 horizontal sections
the carbon bed area is approximately 20 ft2 and air flow
velocity 50 ft/min. Bed depth L is 1.0 in, or deeper. For
non-CBR use, pleated bed cells are simpler in construction,
L is usually less than 1.0 in., and coarser carbon is used.
The pleats may be horizontal as in Fiqure 6-4 or
vertical. To unload the spent carbon, the cell is removed
from the multiple cell filter and one of the plates at the
end of the pleats removed,
Canister Carbon Beds - Fiqures 6-5, -6 and -7 show:
(1) the construction of one type of canister, (2) their
assembly into the cell and (3) a small self-contained air
purifier. Specifications are qiven for two canisters, a
Type 28 with 0.5 in. bed thickness and a Type 42 with 0.75
in. bed thickness. The mean area, between outer and inner
retainer screens, for Type 28 is approximately 0.73 ft2
and for Type 42, approximately 0.76 ft2. The"recommended
maximum capacity for Type 28 canister is 30 ftVmin. At
this flow the oressure drop is 0.15 in. of H20 and flow
velocity approximately 41 ft/min. For Type 42 canister
the recommended maximum capacity is 25 ft'/min which qives
a 0.16 in. of HgO pressure drop and 33 ft/min flow velocity.
For a filter or cell of 1,000 ft'/min flow capacity, 33
canisters of Type 28 are needed and 40 of Type 42.
Fiqure 6-6 shows a filter where the manifold plate is
in a slanted position. Vertical and horizontal plate posit-
ions are also used. In this filter construct!on,the canister
is held to the plate by means of a bolt passed throuqh the
center. By looseninq a wing nut,the snent canister can be
easily removed for replacement with a fresh canister. The
flow direction is from the outside to the center of the
canister. This flow direction is preferred to a flow in the
reverse direction because it qives a shorter adsorption zone
length.
Materials of Construction
The carbon-cartridqe frames, cell frames and other
enclosing panels and supporting structures are mild steel
when pollutant vapors are noncorrosive. Under operations
-------
,6-1
PERFORATED
CYINDM
K-3H.-0.-*!
Figure 6-5
Radial Flow
Design for Air
Systems.
Canister
Purification
Courtesy of Connor Engi-
neering Corp.
Figure 6-6 Arrangement of
Canisters on a Slanted Mani
fold Plate for Medium and
Large Air Purification Sys-
tems
-------
6-13
where considerable moisture can enter the cells or corrosive
vapors are present, special coatinns are applied to the
steel. Zinc-nlated and chromate finishes are mentioned by
some manufacturers. Some attention is also qiven to pre-
vention of air leakage around the cartridqes. This can
be done by interlockina construction, felt seals, or caulk-
ing. The place where corrosion is most likely to occur is
at the interface between the carbon and retainer screen.
Moist carbon or carbon containing corrosive pollutants es-
tablish galvanic cells at the interface and corrosion pro-
ceeds rapidly. Stainless steel or plastic retainer screens
are required under conditions where this can happen.
Operation of Air Purification Systems
Operating Parameters - To attain the most effective and
economical service from air purification systems, various
parameters need to be optimized. These parameters are flow
velocity, carbon mesh size,and bed thickness. They determine
the resistance to flow, the adsorptive capacity (assuming
selection of carbon has already been made) and carbon bed
area. Another important factor is the determination of the
optimum service time at which the carbon bed should be re-
placed. Temperature is not a controlling factor in air-
purification as it very often is in other pollutant control
applications. Occupied spaces are generally in the 50° to
90°F temperature range, a range in which activated carbons
perform effectively. Pollutant concentration is also an
important factor that should be recognized because of its
effect on capacity and service time.
Flow Velocity - An increase in flow velocity produces
an increase in pressure drop through the bed and an increase
in adsorption zone length. Both increases are undesirable.
An increase in pressure drop raises the power reguirements
to operate the blower, and an increase in adsorption zone
length decreases the overall adsorptive capacity. Converse-
ly a decrease in flow velocity produces a favorable effect
in these two properties of the system, but the decrease in
flow velocity is accomplished by increasing the bed area.
The added panels, pleated cells or canisters represents an
increase in investment, When the pollutant is not extreme-
ly toxic, a balance in cost factors has been worked out so
that most systems have bed thicknesses of 0.5, 0.75 and
1.0 in, and are operated at about 40 ft/min flow velocity,
A coarse mesh size falling in the range 4 to 10 mesh is
used,giving pressure drops that are below 0.25 in. of
water. Some sacrifice is made on complete purification;
the efficiency specification is about 9856.
-------
6-14
Filters for toxic agents contain larger mesh carbons,
12 to 30, and are thicker, 1,0 1n. and over. Efficiencies
over 99.99% are required. The pressure drop is higher be-
cause of the smaller carbon granules and thicker bed.
Pressure Drop - The pressure drop through the carbon
bed is a function of the carbon granule size, the size dis-
tribution, the packing of the bed and flow velocity. Equa-
tion 4-43 shows the relationship between the pressure drop
and flow velocity, mean particle diameter and void volume,
e, between the granules, e is dependent on the mesh size
distribution and degree of packing of the bed. e can be
calculated if the particle density of the carbon and bulk
density of the bed are known, but usually e is the unknown
variable.
Figure 6-8 presents several curves that show the effect
of mesh size fraction and flow velocity on the pressure drop.
These curves were recalculated from curves given in Union
Carbide Corp. Catalog Section 3-6450, Data Sheet No. 1.
Service Time - The service time of the filter 1s a
function of the flow velocity, influent pollutant concentra-
tion and the adsorptive capacity of the selected carbon for
the particular pollutant under consideration. Equations
4-23 and -24 establish the relationships between these
variables for flow systems in which the bed is equal to or
deeper than the adsorption zone length at steady state. Be-
cause of the coarse carbon granule size and thin beds that
are used in air purification systems, the bed depth is
usually considerably shorter than the adsorption zone. Equa-
tion 4-24 does not then apply, except to indicate an upper
limit on service time.
From Figure 4-17, Lz at U - 40 ft/mln is 1.7 in. for low
molar-volume odor molecules In coarse 4 to 10 mesh carbon
beds. Lz increases to 2.3 in. for high molar-volume odor
molecules. When carbon beds of 0.5, 0.75 and 1.0 in. thick-
ness are used, pollutant penetration of the bed occurs long
before the adsorption zone has attained steady state. The
adsorption zone is in a transitory state during the whole
service time as depicted by Curves 1 and 2 in Figure 4-13.
Pollutant penetration of the bed occurs early in the service
time but because of the low Influent concentration the
effluent concentration rises very gradually with time. High
99.99% pollutant removal efficiencies are not attainable, but
at 98% efficiency, practical service times are attainable.
-------
6-15
1.0
0.5
a.
o>
TJ
o
e>
2 o.io:
o
CM
0.05
o.
<3
0.01
10 20
U, ft/m1n
50
100 200
Figure 6-8 Pressure Drop Through Granular Carbon Beds of
Varied Mesh Size Fractions as Function of Flow
Velocity
-------
6-16
When a finer 12 to 30 mesh carbon is used, Lz range
is from 0.6 to 0.8 in (at Cb/C-j « 0.01). In carbon beds of
1.0 In.and over,the Lz has attained steady state and is
contained within the bed depth. This state is depicted by
Curve 3 in Figure 4-13. Pollutant removal efficiencies of
99.99% and over are attainable because the adsorption zones
of length greater than 0.6 to 0.8 can be contained in the
bed, i.e., zones measured to Cb/Ci <0.01. See Chapter 4,
Dynamic Adsorption Process for further discussion.
The service times attained vary from 6 mo% when the
odor concentration is described as heavy, to much longer
periods of up to 2 yr, when odor concentration is light.
Odor concentrations are not often quantitatively defined 1n
Jr terms of ppm since odors are not always identified with
specific compounds and a direct quantitative measure made.
Operating efficiencies of 98% (1.e.,Cb/Cj « 0.02) are con-
sidered acceptable and when the efficiency has decreased
to about 90% (i.e., Cb/C-j 0.10), the carbon bed 1s re-
placed .
Equation 4-24 was used to estimate tb at L Lz,
U 40 ft/mln and Ci - 0.5, 0.1 and 0.05 ppm for
4 to 10 mesh carbon. 4-Methyl-2-pentanone was used to repre-
sent the odor and BPLV the vapor phase activated carbon. For
this system and conditions, Lz » 2.1 in. when Cb/C^ « 0.01.
Since the bed depth 1n common use are considerably less than
Lz, the true tb for L
-------
6-77
the first 23 pollutants listed in Table 2-IV. To this list
may be added smog-created vapors, odor vapors qenerated in
washrooms and two additional odor vapors emitted from ren-
dering plants. The odor vapors are:
Pollutant Source
Skatole, 3-methyl-l-benzo(b)pyrrole Washroom
Indole, l-benzo(b)pyrrole Washroom
Putrecine, 1 ,4-diaminobutane Washroom
Cadaverine, 1,5-diaminopentane Washroom
Propanoic acid Rendering
2-Methyl propenal Rendering
The recognition threshold concentrations of the above
23 designated pollutants range from the lowest, 0.0002 ppm,
for trimethylamine to the highest, 1.0 ppm, for nitrogen
dioxide. The recognition threshold concentration for ska-
tole has been reported at 7.5 x 10"8 ppm and 0.019 ppm by two
different investigators. Threshold concentrations were not
found for the others listed above,but they are expected to
be low although higher than 0.0002 ppm.
The odor recognition threshold places an upper limit
to the odor-vapor concentration level that the air purifi-
cation system can deodorize. With intermittent release of
odor vapors and redrculatlon of the air, the air purifi-
cation system need not remove the odor vapor concentration
all the way down to the recognition threshold on a single
pass. The repeated passage through the carbon bed will
bring the odor concentration down gradually to and below
the recognition threshold. Also, odor vapors are not
equally obnoxious so that some may be tolerated consider-
ably above the threshold concentration.
An air purification system operating at 98% efficiency
can deodorize air containing trimethylamine in a single
pass if the concentration does not exceed 0.01 ppm. With
recirculation the initial concentration level can be higher
but the odor will be detected for.a longer time. For skatole
the initial odor vapor concentration can be at about 1.0 ppm,
For nitric oxide the Initial concentration can be 50 ppm,
but at this concentration, and down to at least 10 ppm, the
carbon resorb system would be more economical to operate.
Odor vapor concentrations in the range 1.0 ppm and down are
realistic for the airflows to be deodorized with the above
described air purification systems.
-------
6-18
Carbon Bed Replacement - To attain the maximum but un-
interrupted service from a carbon filter, 1t would be desir-
able to monitor the progress of the adsorbed-phase profile
through the carbon bed so that the service time could be
determined at which the carbon filter should be replaced.
The other-wise generally low capital cost of the cell (about
$60 to $80 per 1000 ftj/min capacity at manufacturing cost)
does not warrant high expenditures for monitoring instru-
ments that can determine this service time precisely. How-
ever, a determination can be made of the service time by
means of a test element attached to the Influent face of one
of the cells. From prior experience with the same purifi-
cation system or with other similar systems and operating
conditions, an approximate service time is already known.
Prior to the estimated service time, the test element 1s
removed from the cell and sent to the system's manufacturer
for analysis and determination of the remaining service
time.
The spent panels, cells or canisters are shipped to the
system's manufacturer where they are emptied and reloaded
with reactivated or virgin carbon. Special procedures are
used in the reloading process to Insure tight packing of the
carbon and thereby avoid later settling of the carbon during
transit or usage. Poorly packed beds can develop open areas
through which the Impure air can pass. The carbon is re-
turned to its manufacturer where It 1s reactivated with high
temperature steam to its original capacity. Some handling
and activation losses occur on each cycle, which can be as
high as 5%. Over a number of cycles, the used carbon is com.
pletely replaced with virgin make-up carbon. The air puri-
fication systems user gets credit for the returned spent
carbon; the cell replacements are less costly than the Ini-
tial purchase.
Solvent Recovery Systems, Present Technology
General Discussion
The solvent recovery systems have been developed to a
high degree of efficiency and reliability. The technology
on solvent recovery is also well documented 1n literature.
The purpose of this part of the chapter 1s to summarize
this technology and in the next part of the chapter to ex-
plore ways whereby this technology can be expanded to appU.
cations that are unprofitable but concerned strictly with
decreasing pollutant emissions.
-------
6-19
Process engineers and equipment designers have directed
their efforts to improve the economics of solvent recovery
operations. These efforts have been directed toward decrease
of power or fuel requirements for regeneration, reduction of
pressure drop during the adsorption phase, increase of ad-
sorptive capacity by utilizing residual capacity of adsorp-
tion zone, and improved methods for recovery of the desorbed
solvent. The result has been the development of three types
of systems differentiated by the manner in which the carbon
bed is maintained or handled during both phases of the ad-
sorption-regeneration cycle. These are:
Fixed or stationary bed
Moving bed
Fluidized bed
The selection of the system depends on the type of solvent
vapor and the circumstances under which it is to be recovered,
The most efficient and economical service is obtained
from the solvent recovery system, regardless of type, if the
airflow is kept at a minimum but in keeping with proper
ventilation. In a plant with well defined operating units
that emit pollutant vapors, the airflow can be kept low by
use of closely fitting hoods over the operating units and
the hoods connected by way of ducts to the pollutant control
system. By use of close fitting hoods, sufficient draft is
created to draw the pollutant away from the point of emis-
sion with use of minimum airflow. Such situations can be
taken advantage of in degreasing (Figure 1-1), dry cleaning
(Figure 1-2), rotogravure and flexographic presses, the
various surface coatings applications, rubber products
dipping operations, paper impregnating operations and sur-
face coating and ink drying ovens. When a new plant is
being contemplated, the pollutant control system should be
considered as an integral part of the plant. This would
involve an effort on the part of the machinery designers
and plant layout men.
Figure 6-9 presents a flow diagram of a dual, sta-
tionary bed, solvent recovery system with auxiliaries for
collecting the vapor-air mixture and for solvent separation
from steam condensate. The vapor-air mixture, collected
from the various point sources, passes through the particu-
late filter and into the on-stream carbon adsorber, in this
case the upper one. The effluent air, which is virtually
free of vapors, is usually vented outdoors. In this dia-
gram the blower precedes the particulate filter; in many
applications the blower follows the particulate filter. The
lower carbon adsorber 1s regenerated during the service time
of the upper adsorber. A steam generator or other source of
-------
6-20
Hoods or direct connections to point emission sources
Y
Purified
air
exhaust
Vapor-air
mixture
Duct
Incinerator
exhaust
Particulate
filter
Blower
on stream
Carb^ont _bed
reqeneratinq
Adsorber
Steam or hot
gas generator
Decanter,
distillation
column
Condenser
<H-
Recovered
solvent
v ;'
Incinerator
t
3 ' '
' >
i
i
i
Figure 6-9
Stationary Bed Carbon Resorb System with
Auxiliaries for Vapor Collection and Solvent
Separation from Steam Condensate or Incin-
eration of Pollutant Vapors
-------
6-21
steam is required. The effluent steam-solvent mixture from
the adsorber is directed through the condenser and the liqui-
fied mixture then run into the decanter and/or distillation
column for separation of the solvent from the water.
Other carbon resorb systems can be used 1n place of the
dual, stationary bed system as the circumstances warrant.
Stationary Bed Systems
Figures 6-10 to -13 show two designs of stationary bed.
solvent recovery systems. The type shown in Figures 6-10 and
-11 employs vertical cylindrical beds wherein the solvent-
laden air flows axially down through the bed. This particular
design is advertised for use 1n recovery of solvents used in
degreasing and dry cleaning although equally well suited for
recovery of solvents from other Industries. Solvents men-
tioned are trichloroethene, tetrachloroethene, toluene, Freon
TF and dichloromethane. Regeneration 1s with steam up-flow
through the bed and, since the above mentioned solvents are
Immiscible in water, decantatlon 1s used to separate the
condensed solvent from the steam condensate. The valves are
disk type, open and close by pistons. Water Is used as
coolant 1n the condenser. Steam, electric power to drive the
blower, and cooling water are three operating cost Items.
Cost of steam and cooling water Increase with frequency of
regeneration.
Figure 6-11 shows the external features and arrangement
of the component parts of a two-adsorber system. This par-
ticular unit 1s a V1c Model 572 AD, with two adsorbers used
alternately, I.e., while one adsorber Is on-stream the other
1s regenerating. The recommended airflow capacity Is 3,000
ft'/min for each adsorber of approximately 5 ft diameter and
bed length near 20 in. This adsorber model was used as a
basis for the calculation of bed depths and adsorbed-phase
profiles, Chapter 4, page 59, and regeneration of activated
carbons, Chapter 4, page 67.
Dual adsorber systems are also operated with both ad-
sorbers on stream 1n parallel when the solvent concentration
is low. Regeneration Is less frequent than every hour and
may be done during off-working hours. Operation In parallel
almost doubles the air handling capacity. The capacity of
Model 572 AD Increases to 5,500 ftVmln.
-------
L-22,
Condenser
Vapor
& air
mixture
Decanter
A1r
Blower
Adsorption phase
Steam
Desorption phase
Figure 6-10 Cut-Away Diagram of Solvent Recovery Adsorber
Showing Vapor-Air Flow Pattern During the Ad-*
sorption and Steam Flow During Desorption.
Courtesy of Vic Manufacturing Company.
Figure 6-11 Stationary Bed Solvent Recovery System of 3000
ft3/min Flow Capacity for Each Adsorber. Used
for Uater Immiscible Solvents. Courtesy of Vic
Manufacturinq Company.
-------
EXHAUST AIR
LADEN SOLVENT FREE '
NLET
1
.
»
^7r \ '
ACTIVATED CARBON
\L- - J/
f ^^ y ^'
\ \ ADSORBERS \
J :
-7, A
ACTIVATED CARBON
-Wv %J
v.
i
*_
[^l CONDENSER
1
WAI
CO
D
, r
J
MTINUOUS
LCANTER
~>i
i
",
ADSORBING
BLOWER
LOW PRESSURE STEAM
SOLVENT
Figure 6-12 Flow Diaqram of a Solvent Recovery System
Courtesy of Vulcan-Cincinnati, Inc.
Finure 6-13
Solvent Recovery Svsten for Recovery of Manhtha
fron a Rubher Products Plant, 12.0DQ ftVnin
low Capacity. Courtesv of Vulcan-Cincinnati
I nc.
-------
6-24
For a one-hour adsorption-regeneration cycle time, the
sales literature reported recovery of trlchloroethene 1s 225
Ib and steam requirement for regeneration 1s 675 Ib, giving
a steam.to-solvent ratio of 3.0. This Is typical for a high
solvent concentration level. The solvent recovery and steam
requirements as given in Table 4-XVIII for Profile 3 are 180
Ib/hr of solvent, 500 Ib/hr of steam giving a steam.to-sol-
vent-ratio of 2.8 at solvent concentration of 3,000 ppm.
The good agreement between the steam-to-sol vent ratios 1s
an Indication of the reliability of the methods used to cal-
culate the theoretical 2.8 ratio.
The largest vertical or up-right adsorber constructed
by Vic Manufacturing Company has an airflow capacity of
5,000 ft3/min with carbon bed diameter of about 6 ft. The
overall length and width dimensions are 18 and 11 ft and
overall height 11 ft. The smallest has a 700 ft'/mln air-
flow capacity and overall dimensions 7 by 5 ft, length and
width, and 11 ft height. All of these units fit Into the
general concept of packaged sorption devices.
The horizontal tank type adsorber as Illustrated 1n
Figures 6-12 and -13 are structurally more amenable to large
capacity solvent recovery systems than the vertical type, al-
though Vulcan-Cincinnati, Inc. engineers systems as small
as 2,000 ft3/m1n. The 2,000-ft3/m1n system, designated as
Model 22, has two adsorbers, overall length and width di-
mensions are 18 and 7 ft and overall height 1s 13 ft. The
largest system, designated as Model 403, ha.s 40,000 ft'/mln
air flow capacity, overall length and width dimensions are
52 and 27 ft and overall height is 26 ft. Their largest
skid mounted system, Model 102, has design capacity of
10,000 ft3/m1n, overall length and width dimensions are 38
and 12 ft and overall height 1s 16 ft. Units of size Model
102 are basically off-the-shelf packaged sorbent devices
while units of size Model 403, fall Into the broader defi-
nition of a packaged unit in that they can be transported
and later assembled from smaller components.
This type of solvent recovery system 1s successfully
being used 1n a variety of Industries. To follow the In-
dustry category system presented in Table l-II, the Industries
1n which they are 1n use are, plastics, rubber products,
adheslves and paper coatings. Two other Industries not
Included 1n Table l-IItalthough mentioned on page 1-67,
are Pharmaceuticals and chemical manufacturing. Solvents
that are being recovered are listed below with their Vm,
-------
6-25
molar volumes, to indicate their relative adsorbabilities:
Solvent
cmM iq/mol Solvent
Heptane 163
Naphtha, 240°-340°F 140-207
Xylene 140
4-Methyl-2-pentanone 140
Hexane 140
Freon TF(1)
Cyclohexane
Toluene
2-Ethoxy ethanol
Dlethyl ether
120
118
118
116
106
Ethyl acetate
Butanone
Benzene
Tetrahydrofuran
2-Propanol
Propanone
Dichloromethane
Ethanol
Ethanenitrlle
Methanol
cm
Vm.
3! iq/mol
1,1 ,2-Trichloro-l ,2,2-trif luoroe thane
106
96
95
88
84
74
65
61
51
42
These solvents are frequently used also in surface coatings
and graphic arts industries, particularly toluene, xylene
and 4-methyl-2-pentanone. The solvent recovery systems
would also be effective in these two industries although not
specifically identified amonq the systems' users. Table C-I
Identifies these and other solvents with various pollutant
emission sources.
The flow diagram of Figure 6-12 shows one horizontal
carbon bed in each adsorber. This type of adsorber is also
fabricated with two beds, one above the other. The airflow
enters the adsorber between the beds with up-flow through
the upper bed and down-flow through the lower. This reduces
the adsorber shell size for a given flow, thereby reducing
construction costs.
The solvent recovery system illustrated in Figure 6-13
is the Vulcan-Cincinnati, Inc. Model 102 designed to operate
at 10,000 ft3/min airflow. In this particular application,
it is operated above design capacity, 12,000 ftj/min, to re-
cover naphtha from a rubber products plant. The bed area
in each adsorber is about 110 ft2 and bed length is 16 in.
At the 12,000 ft3/min flow, the linear velocity through the
bed is approximately 110 ft/min. It is operated on a one
hour adsorption-regeneration cycle, recovering on the average
293 lb of naphtha per cycle. Steam consumption is about
1770 lb per cycle which, on an average, gives a 6 Ib steam/
lb naphtha ratio. The carbon bed volume is approximately
-------
6-26
145 ft3 and.when loaded with carbon of 31 lb/ftj density the
bed weight is 4,500 Ib. For the 293 "ib/cycle recovery the
operating capacity is then 0.065, with no correction beinq
made for the adsorption zone.
The naphtha being recovered is an aliphatic-naphthenic
petroleum fraction boilinq in the 240° to 340°F range. Nor-
mal and branched chain aliphatic hydrocarbons, cyclooctane,
and substituted cyclohexanes and cycl oheptanes of Cj to C-JQ
fall into this boiling ranqe. Most of these solvents are
included in Table C-I. Their odor recognition threshold and
TLV concentrations are relatively high and they are not
particularly reactive to solar radiation. They can pass into
the atmospnere unnoticed at low concentrations.
The theoretical steam-to-naphtha ratio for the above
recovery operation is 7.2 (compared to the measured 6.0)
when cyclooctane is used to represent naphtha in the calcu-
1ati ons.
Figure 6-14 illustrates a small, cabinet-enclosed,
single adsorber, solvent recovery unit. Hoyt Manufacturinq
Corp. advertises four models; the one shown is Model 4. It
is designed for use in plants using up to 3 drums (165 qal)
of solvent per month at airflow capacity of 700 ft3/min.
Its overall dimensions are 49 by 45 in., length and width,
and 81 in. height. These units are pined directly to the
production machine emitting the solvent (or pollutant). In
an existing plant where the use of vanor collection ducts
to a central solvent recovery systemarenot feasible, the
use of a number of small directly connected units may be
the solution to an otherwise difficult problem.
Figure 1-2 presents a flow diagram of a solvent recovery
system as an integral part of a coin-operated, dry cleaning .
machine. The solvent used is Freon TF, 1,2 ,2-trichloro-
1 ,2 ,2-trif1uoroethane, which has a Vm a 120 cm3l1q/mol
and 118°F boiling point. It is relatively volatile yet
strongly adsorbed. It is not a strong pollutant in regard
to odor, toxicity or as a smog precursor.
Two sizes of dry cleaning machines of the above type
are manufactured. The smaller size machine cleans an 8-lb
load of clothing and the larger commercial size a 25-lb load.
One gallon, or 13.3 Ib.of Freon TF is required per pound of
clothing in the washing and rinsing phasesof the cleaninq
cycle. After the rinsing phase the Freon TF is drained from
the washer-extractor and clothing tumbled while air at about
85°F is passed through the tumbler. The vapor-laden air-
-------
L-2:
I
,
Finure 6-14
Small Cabinet-Enclosed Solvent Recovery Unit
ftVmin Capacity. Steam Reaeneratl'on
Courtesy of Hoyt Manufacturina Corporation
-------
6-28
stream then passes through one of the carbon adsorbers.
The overall cycle time is 14 mln, but programmed to operate
different lengths of time on extracting and tumbling depend-
ing on clothing to be cleaned.
In the 8-lb machine the clothes drying airflow is
about 100 ftVmin, The adsorbers are 16 in. diameter and 28
In. in length and contain up to 100 Ib of 4 to 6 mesh pel-
letlzed activated carbon. Steam regeneration of the carbon
usually starts after the fourth clothes cleaning cycle and
proceeds over several cycles. The Freon TF-steam vapor Is
condensed, separated by decantation and the Freon TF run
Into storage for future use without any additional treatment
required.
Moving Bed Systems
The concept of the moving bed system is illustrated In
Figure 6-15. The rotary component of the system consists of
four coaxial cylinders. The outer cylinder is impervious to
gas flow except at the slots near the left end. They serve
as Impure air 1njet ports where they are shown uncovered and
as steam-vapor outlet ports as shown at the lower left end
of the rotary. The carbon bed is retained between two cylin-
ders made of screen or perforated metal and also segmented
by partitions placed radially between the two cylinders. The
inner cylinder is again Impervious to gas flow except at the
slots near the right end of the rotary. These slots serve as
outlet ports for the purified air and Inlet ports for the
regenerating steam. On each rotation of the rotary, each
segment of the bed undergoes adsorption and regeneration.
The desorbed solvent can then be separated from the steam by
decantation or distillation.
Because of the continuous regeneration capability of the
rotary bed, a more efficient utilization of the carbon is
possible than with stationary bed systems. In most solvent
recovery operations the adsorption zone is between 3 and 4
in. The unsaturated carbon bed 1n front of the adsorption
zone and the saturated bed behind 1t are idle but add to the
bulk of the system and Increase airflow resistance through
the bed. In deep beds of 12 to 36 in., as required in the
stationary bed systems for regeneration time, a large portion
of the bed is idle at any one time. By continuous regeneration
the regeneration time for each segment of the bed Is shortened
and thereby shorter bed lengths can be used. This leads to
two advantages: (1) more compact system and (2) reduced
pressure drop.
-------
6-29
Vapor-laden air in
Purifiea air out
Steam in
Activated carbon
bed
Cross-sectional view
Steam and vapor out
Vapor-laden
air in
Steam and
vapor out
Horizontal exterior view
Figure 6-15 Continuous Rotary Bed, Based on Sutcliffe
Speakman Co., LTD Illustrations, 66 Palmer
Ave., Bronxville, N.Y.
-------
6-30
The disadvantages are those associated with wear on
moving parts and maintaining seals 1n contact with moving
parts. The use of shorter beds also decreases the steam
utilization efficiency,
Fluidized Bed Systems
Figure 6-16 shows a flow diagram for a fluidlzed bed
solvent recovery system, based on illustrations from Avery
(1969). The carbon is recirculated continuously through the
adsorption-regeneration cycle. The spent carbon, saturated
with solvent, is elevated to the surge bin and then passed
down into the regeneration bed where it is contacted to an
upward flow of steam. The regenerated carbon is then metered
into the adsorber where the carbon traverses nine beds while
fluidized with the upward flow of the vapor-laden air. Air
velocity of 240 ft/min is required to cause fluidization of
the bed. In both the regeneration and adsorption phases the
carbon is moved countercurrent to the gas or vapor.
The countercurrent movement Increases the .efficiency
of, regeneration, i.e., the steam-to-sol vent ratio Is less
'than for a stationary bed under otherwise comparable condi-
tions. For a number of solvents, Avery reports 402 to 50%
less steam required for their recovery. In addition to the
beneficial effects of the countercurrent movement, the bed
length can be increased to further Improve the steam utili-
zation.
The countercurrent movement also increases the effective
th
use ftf thft Carbon' more solvent can be recovered with less
carbon than with stationary or rotary bed systems. By adjust-
ments or balance of the carbon and solvent input rates, the
total carbon in the adsorber can be made part of the adsorp-
tion zone but have the carbon reach saturation in the lowest
bed just before it is discharged Into the elevator. Very
little of the carbon is then Idle, hence the maximum utili-
zation is made of the carbon.
The fact that the jcju&MLJbJUur.fijU^
de.Lly.e.r.&cLto ,th£«£&gAAer.AjLian jxhasfi. 1s another factor 1n the
reduced steam requirement. In this respect the fluidized bed
system offers the most favorable conditions for solvent de-
sorptlon while the rotary bed offers the least favorable, in
the notary bed, operations., the carbon moved Jnto_tbe regener-
ation phase has reached the . loweflTTtinti of saturation TrHEhe
three systems. " ~
-------
6-31
Elevator
for vapor-
laden carbon
Surge bin
Desorbed vapor and
regenerating agent
out
Regeneration bed
Regenerating agent
f Carbon metering valve
T
IV.
c:::
c::
::::"j
U
Impure air in
Purified air out
Fluid bed adsorber
Figure 6-16 Fluidlzed Bed Solvent Recovery System
-------
6-32
In the operation of this particular unit, Avery reported
penetration of 100 ppm when carbon disulfide was being ad-
sorbed at 1,000 ppm and 100 ppm when acetone was being adsorbed
at 1,700 ppm. This was a continuous penetration and not the
temporary penetration that might occur from a stationary bed
just before it is taken off stream. By increasing the number
of beds, the penetration from the fluidized bed system can be
decreased to any desired level but with an increased pressure
drop penalty.
When large air volumes are treated and available space
for the installation is at a premium, the smaller size and
also the lower initial cost are definite advantages over the
stationary bed system.
A serious disadvantage is high attrition l.os$&|j>f the
carbon caused by the fluidization of the beds". Because of
the attrition, filtration of the effluent airstream may be
required. Influent airstream need nojt be filtered since no
plugging of the fluidized beds can occur.
-ji- -~
Carbon Resorb Systems, New Technology
General Discussion
Most of the present adsorption technology has been
directed toward goals other than the reduction of pollutant
vapor emissions into the atmosphere. In complying with one
of the objectives of this study, attention has been directed
toward developing new means or adapting the present technology
for pollutant emission control. To attain this goal a detailed
study was made to determine the capabilities of available ad-
sorbents and to explore possible modifications to presently
used adsorption systems to adapt them for pollution control
under the wide variety of conditions under which pollutants
are emitted.
The area open to technical advances in package sorbent
systems for pollution control appears to be in modification
of the systems and operating procedures used in solvent re-
covery. Since the primary objective is pollution control
rather than solvent recovery, the modified systems are re-
ferred to in this report as carbon resorb systems. As in
solvent recovery, two phases of the operating cycle are ad-
sorption and regeneration, but also includes an additional
operation, the disposal of the desorbed pollutant. An import-
ant requirement of the disposal procedure is that 1t does not
cause repollutlon of the air or waterways.
-------
6-33
The main departure in the regeneration of carbon resorb
systems is the use of heated noncondensable gases in place of
steam. As the influent concentration decreases, the amount
of steam required per regeneration also increases. At low
concentrations the amount of steam required relative to the
amount of pollutant desorbed is so large that separation of
pollutant from the steam becomes impractical. The extent of
pollutant dilution in steam condensate was calculated for a
3,000 ftVmin capacity solvent recovery system when used to
clean an airstream containing pollutants at 10 ppm concentra-
tion and regenerated with steam. The results of the calcula-
tions are summarized in Table 4-XX.
The three organic compounds listed in the table were
selected as representatives for the wide variety of solvents
or pollutants that require control. 4-Methyl-2-pentanone is
representative of strongly adsorbed compounds which are
completely oxidizable to C02 and HzO and are slightly soluble
in water. Propanone is representative of weakly adsorbed
compounds, completely oxidizable, and completely miscible
with water. Trichloroethene is intermediate in adsorbabi1ity,
is slightly soluble in water, but on oxidation yields HC1, a
potential air pollutant.
The high steam-to-solvent ratios, as given in the last
column of the table, for each of these compounds mean that
many pollutants cannot be economically separated from the
steam condensate. Those that are soluble or even slightly
soluble will be completely dissolved and separation by dis-
tillation would be too costly. Disposal of polluted steam
condensate into the sewer can also lead to further pollution
of the waterways. Means are proposed by which this problem
can be avoided.
Compounds such as tetrachloroethene, aliphatic and
naphthenic hydrocarbons above Ce are reported to be insoluble
1n water. Separation of compounds of this type appears econom-
ically possible by decantation.
When a noncondensable gas is used as regenerating agent,
the desorbed pollutant may be disposed of by several means.
If it is completely oxidizable to C02 and HpO it can then be
immediately destroyed by incineration upon desorption from the
carbon. If it has recovery value, or is noncombustible or
would repollute the air on incineration, the desorbed pollut-
ant may be readsorbed on a small secondary carbon bed and
recovered from it by conventional steam regeneration or it
may be recovered from the regenerating gas by condensation.
-------
6-34
These three procedures for immediate disposal or recovery
of the pollutant can be incorporated into any of the three
solvent recovery type systems described earlier in this chap.
ter, i.e., stationary bed, moving bed and fluidized bed systems.
Other aspects of the adsorption and regeneration phases
have also been examined to determine possible means for im-
proved utilization of the carbon and regenerating agent.
The various concepts as incorporated into various oper-
ational systems can be identified according to the mode of
regeneration and disposal of the desorbed pollutant. These
are:
Heated air or inert gas regeneration followed by
thermal or catalytic incineration of the de-
sorbed (completely combustible) pollutant,
Heated air or inert gas regeneration of primary
bed followed by readsorption of desorbed pol-
lutant on a secondary bed and steam regenera-
tion of secondary bed to recover pollutant,
Heated air or inert gas regeneration with desorbed
pollutant (or solvent) condensed at lowered
temperature and recycle of uncondensed vapors
through carbon bed,
Two-stage adsorption with stationary bed system
and single-stage regeneration,
Two-stage regeneration with stationary bed system
and single-stage adsorption,
Regeneration by pressure reduction,
Continuous or intermittent removal of spent
carbon from adsorption system followed by
high temperature steam reactivation of the
carbon on plant site.
These systems are described in the following text with
statements made regarding advantages and disadvantages. The
descriptive portion is followed by economic analysis of
solvent recovery and some of the proposed systems. Cost com*
parisons are given with the competing systems: catalytic and
thermal incinerations.
-------
6-35
Gas Regeneration with Incineration
For pollutants that are completely oxidizable, regener-
ation with an inert, noncondensable gas followed by inciner-
ation of the desorbed pollutant is a procedure that offers a
relatively low cost regeneration and simultaneously effects
complete disposal of the pollutant. In this case the carbon
bed acts as a concentrator. The incinerator can then be
relatively small requiring little additional expense to
operate.
To show the manner in which the system would operate,
the following sample calculations have been worked-up for
4-methyl-2-pentanone from data given in Table 4-XX. At
0.025 Ib/lb operating capacity, 37.5 Ib of the solvent are
adsorbed on the carbon from 1,500,000 ft3 of air passed
through the bed over a period of 82 hr at 3,000 fts/min flow
and 10 ppm concentration. The regeneration can be accom-
plished with 37,000 ft3 of inert gas (near 28.9 lb/mol) at
302°F regeneration temperature, yielding an effluent mixture
of 4,000 ppm mean solvent concentration. (The regeneration
data are obtained from predetermined curves of type shown
in Figures 4-22, -23 and -24.) The size of the incinerator
depends on the regeneration time. For a two-hour regener-
ation, the incinerator would be sized for a 300 ft3/min flow
rate. This is 10% of the 3,000 ft3/min flow capacity of the
carbon resorb system or incinerator if the vapors were in-
cinerated directly at the 10 ppn. In addition, direct in-
cineration would require a considerable amount of fuel to
heat the air to the incineration temperature. Incineration
of the carbon bed effluent would require very little fuel
since the air volume is much smaller and the high concen-
tration of the pollutant supplies the major part of the fuel
requirements.
By use of a noncondensable gas, rather than steam, the
heating cost of the regenerating gas is considerably less.
The above regeneration requires 2,400 Ib of steam, which at
O.H/lb costs $2.40. Noncondensable gas regeneration re-
quirement is 2,700 Ib, which at 0.005*/lb, costs $0.13. Steam
cost is about $0.01/hr per 1000 ft'/min flow. At the 10
ppm pollutant concentration level where regenerations are
not frequent, the steam and definitely the noncondensable
gas costs are not significant relative to the other operating
costs which can add up to at least $0.25/hr per 1000 ft*/min
or to $0.55/hr per 1000 ft'/min, the more probable cost level
-------
6-36
As the pollutant concentration increases, the advan-
tages of using a noncondensable gas regeneration-Inciner-
ation combination decrease. When the pollutant 1s a sol-
vent of recovery value, the Incineration of the solvent
would constitute an Increasingly greater loss of a valuable
product. At higher pollutant concentrations and more fre*
quent regenerations, increasingly larger incinerators are
required. At concentrations approaching 25% LEL, the re-
quired incinerator capacity is the same as for direct In-
cineration. At concentrations between 700 to 1000 ppm, the
cost of the carbon resorb with incineration approach those
of direct Incineration; see Figure 6-31.
The general concept of carbon resorb and Incineration
systems combination has been Investigated by Mattla (1969,
1970). A flow diagram of the proposed process 1s presented
in Figure 6-17. Adsorption proceeds in the same manner as
1n solvent recovery, but regeneration 1s accomplished by
recycle of gas through the carbon bed and incinerator, which
can be either thermal or catalytic. The regenerating gas
is Initially air but on passing through the adsorber and
incinerator it becomes converted to a mixture low in oxygen
with increased carbon dioxide and water vapor. Make-up air
is added to the Incinerator to supply enough oxygen to burn
the pollutants desorbed from the carbon bed. To avoid
damage to the carbon from over-heated regenerating gas, a
cooler is required in the recycle line. To maintain proper
regeneration temperatures and flow rates»Instrumentation
and closer controls are required than needed for solvent
recovery. The process 1s recommended for fairly large air
volume control, 10,000 ft'/nHn and larger.
In the operation of this process, a balance is main-
tained between the time period for the adsorption phase and
regeneration phase to attain the best overall efficiency.
As an example of operating conditions, a process may be
designed to adsorb a pollutant at 200 ppm concentration in
90 min and flow velocity near 100 ft/min. Regenerating gas
flow and temperature are adjusted to regenerate the carbon
in 75 min allowing 15 min for bed cooling. Regenerating gas
flow rates are variable from 2% to 10% of the adsorption
flow rate. Temperatures are adjusted to produce the desired
rate of desorption. A 300°F temperature was considered
maximum. The carbon bed depths are 4 to 8 In., much shorter
than in solvent recovery, to bring the service time to the
one hour level at the lower concentrations.
It should be noted that the regenerating gas flow 1nd1»
cated in Figure 6-17 is In the same direction as the ad-
sorption flow, Instead of reversed as normally done 1n
-------
6-37
Participate
filter
Adsorbers
M-
>
||
n
H
n
i
Exhausts to
atmosphere
Blower
Impure
air
Heat
exchanger
Regen. gas
cooler
-o
Blower
Make-up air(""""
Nat. gas
Figure 6-17
A1r Pollution Control System Utilizing Carbon-
Resorb with Gas Regeneration and Incineration
of Desorbed Pollutants, (from Mattla, 1970)
k-
(I),
Figure 6-18
Adsorption-Phase Profile After Carbon Bed Has
Been Regenerated, When L 1s 4 to 8 1n.t and
-------
6-38
solvent recovery operations. This procedure leaves an
adsorbed-phase residue in the carbon bed that extends to
the effluent end. This is shown in Figure 6-18. Because
of the residual capacity, immediate penetration occurs in
the adsorption phase at a low concentration. The penetra-
tion concentration is the concentration in equilibrium with
the residual capacity. By increasing the operating capacity,
Aoi » tos-u)r» the amount of penetration can be decreased to
lower levels. The process is also operated with reverse
flow (Mattia, 1969). In this case the adsorbed phase pro*
files are similar to those illustrated in Figure 4-21.
Another operational characteristic that should be
noted is that the pollutant concentration in the regenerating
gas stream is not constant but varies with regeneration time
in a manner shown in Figure 6-19. This variation in concen-
tration produces effects in the disposal operation which must
be compensated by corrective measures. In incineration, It
is basically a variation in fuel input; natural gas input rat
must be adjusted to maintain the Incinerator temperature at
the effective level over the total regeneration phase.
Gas Regeneration with Secondary Adsorption
When the pollutant, adsorbed from a low concentration
airstream, contains halogens, NOx and SOx groups, Inciner-
ation of the desorbed pollutants would repollute the air with
acids of these groups. Other means are required to dispose
of the desorbed pollutants than the incineration method des-
cribed in the preceding text. One of the methods that 1s
feasible on theoretical grounds utilizes a secondary carbon
adsorber operating as a solvent recovery unit for the efflu-
ent regeneration gas stream.
The manner in which the system would operate can be
demonstrated with the sample calculations used in the pre-
ceding text on Gas Regeneration with Incineration. In the
adsorption-desorption process the 4-methyl-2-pentanone is
removed from an air volume of 1,500,000 ft3 at 10 ppm con-
centration and concentrated Into an air volume of 37,000 ft3
at a mean concentration of 4,000 ppm. The secondary adsorber
is then required to recover 37.5 Ib of 4-methyl-2-pentanone
every 82 hr from 37,000 ft3 of gas volume at 4,000 ppm mean
concentration.
Since the desorbed solvent concentration varies over
the regeneration time period in a manner shown 1n Figure
6-19 the estimating procedure for determining the carbon
bPd size would be quite Involved 1f the changes in concen-
tration were taken Into consideration. A very approximate
estimate of the bed size may be attained if the 4,000 ppro
mean concentration Is assumed constant over the regenera-
tion time period.
-------
6-39
Regeneration time
Figure 6-19 Pollutant Desorptlon Rate Variation with
Regeneration Time
Partlculate
filter
Blower
Impure
air
Exhaust to '
atmosphere
To
condenser
Regen. gas
heater
Regen.
blower
A
D
Regen. gas
cooler
Secondary
adsorber
Steam
Figure 6-20 A1r Pollution Control System Utilizing Carbon-
Resorb with Gas Regeneration and Secondary Ad-
sorber for Desorbed Pollutants,(from Mattia.
1970)
-------
6-40
The parameter that greatly affects the required bed
size is the choice of steam-to-solvent ratio that the ad-
sorber is to operate at. If operations were chosen at steam-
to-solvent ratio of 3.0, the required operating capacity is
0.08 Ib/lb for the saturated layer. The estimated carbon
bed weight is approximately 500 Ib or 332 of the 1500 Ib for
the primary bed. By increasing the steam-to-solvent ratio
to 6.0, the required operating capacity is increased to 0.14
Ib/lb. The estimated carbon weight reduces to 300 Ib or 20%
of the primary bed weight. The details of the calculations
for the latter estimate are given in Appendix E, page E-24.
By reducing the primary bed thickness and thereby, also,
the adsorption-regeneration cycle time, the secondary bed
size can be further reduced. When the adsorption and regen-
eration phases for the primary adsorbers are balanced, two
secondary adsorbers may be used, also, operating alternately
on adsorption and regeneration.
Figure 6-20 presents a flow diagram of the proposed
system as engineered by Mattia (1969, 1970). Inert gas
(could be flue gas) is fed into the system at the start of
the regeneration and recycled through the primary and secon-
dary adsorbers. The regenerating gas from the secondary ad-
sorber passes through the surface heater where it is heated
to an elevated temperature. On blending with a side-stream
being recirculated through the primary adsorber, the temper-
ature of the combined gas stream on entering the primary ad-
sorber is near 300°F. A part of the vapor-laden gas stream
from the primary adsorber passes through the cooler where
it is cooled down to 100°F, or lower, before being directed
through the secondary adsorber.
At increasingly higher pollutant concentrations the
advantages in using secondary adsorbers decrease and direct
regeneration of the primary adsorber increase.
Gas Regeneration with Condensation and Recycle
A third proposed method utilizes a condenser to recover
the desorbed pollutant vapor from the regenerating gas.U)
By operating the condenser at a very low temperature an almost
complete condensation of most pollutants could be realized,
but to avoid costly refrigeration a more economical approach
is to operate the condenser at a readily attainable higher
temperature and recycle the uncondensed vapor through the
(1) Proposed by B.B. Carr, MSA Research Corp., Evans City, p*
-------
6-41
on-stream adsorber. As the condenser temperature 1s raised
the amount of recycle becomes larger, The limiting factor
1s the adsorptive capacity of the carbon bed, hence opera-
tion of the process at practical condenser temperatures Is
only attainable with the less volatile pollutants. The In-
crease 1n regenerating gas to handle the recycled vapor 1s
small and 1s not a significant factor 1n the operating cost.
Figure 6-21 presents a flow diagram that Illustrates
eneral scheme of this type of operation. An inert re-
generating gas is prepared and heated by burning natural
gas or any other completely oxidizable fuel. The regener-
ating gas is then cooled to near 300°F and passed through
+ ho A-f f - c t i»oam arl e/>v»Ke * in + 1*4* * « » A A ,1 j»<*U »* o TU~
ating gas is tnen cooled to near 300T and passed through
the off-stream adsorber, in this case Adsorber 2. The
vapor-laden hot effluent from Adsorber 2, on passing through
the condenser, is cooled and, if the dew point is reached,'
a portion of the vapor condenses. The uncondensed vapor and
regenerating gas continue their flow into the Impure air
stream and to the on-stream Adsorber 1 where the recycle
vapor is readsorbed. During the desorption phase of Adsorb-
er 1, the vapors from the Impure air and recycle gas streams
are both desorbed but at a higher concentration and in a
slightly larger regenerating gas volume than during the
Initial start-up cycle. On each successive adsorption-re-
generation cycle the amount of vapor recycled increases
until either the adsorptive capacity of the carbon bed 1s
exceeded or the condensation rate equals the pollutant vapor
Input rate.
To gain further insight Into the manner in which this
system operates, calculations were made using the carbon-
resorb system as described in the prior text under Gas
Regeneration with Incineration and Gas Regeneration with
Secondary Adsorption. In the Initial cycle of the adsorp-
tion-desorption process the 4-methyl-2-pentanone is removed
from an air volume of 1,500,000 ft* at 10 ppm concentration
and concentrated into a gas volume of 37,000 ft3 at a mean
concentration of 4,000 ppm. On the second and successive
cycles, these gas volumes and concentrations change until a
steady state is reached. At steady state operation the
condenser removes 37.5 Ib of 4-methyl-2-pentanone from the
regenerating gas stream with the uncondensed balance return-
ed to the on-stream adsorber.
The regeneration of the off-stream adsorber is started
on the 80th hr and continued to the 82nd hr over a 2-hr
regeneration period. By regenerating the off-stream ad-
sorber near the end of the service time, the recycled vapor
is readsorbed 1n the influent end of the on-stream adsorber
-------
6-42
A
Partlculate f1
/
Impure
air
Adsorbers
Recycle
line
Natu
ga
A<
I"! Blower
f /^\
Iter Exhaus
air
?i >M
V ; VIs
-+ _-r .---.
*x ^^
*? 2:?
! I U
i f
r~^ I Cooler
_J a 300°F
'**
jj/
A
/\ ( l^
1
B1
*»»1 _
S ^ I-K
LJV
ower L_J
y
L1o
^ ^ Regeneratlng-
Condenser
Liquid solvent
or
9as pollutant
generator
Figure 6-21 A1r Pollution Control System Utilizing Carbon
Resorb with Gas Regeneration, Condensation,
Recycle of Uncondensed Vapor.
-------
6-43
The readsorbed vapor is
ease of desorptlon when
reverse direction.
now 1n a favorable position for
regenerating gas flow Is in the
The concentration of the desorbed vapor in the regen-
erating gas stream varies 1n a manner indicated in Figure 6-
19. This concentration variation has an affect on the oper-
ation of the condenser and also on the readsorption of the
recycled vapors. To simplify the calculations the concen-
tration was assumed constant at the mean level.
Two estimates were made, one with the condenser oper-
ated at 77°F and the other at 32°F. In each case the initial
flow to the adsorber is 3,000 fts/min at 10 ppm concentration
When the condenser 1s operated at 77°F, the steady state is
attained on the 6th cycle. At the steady state,the follow-
ing operating condltionsprevall during the 2-hr regenerating
time period:
F to adsorber
C-j to adsorber
F to condenser
Ce to condenser
Weight of vapor
recycled
Weight of vapor
condensed
3,330 ft
940 ppm
330 ft3/m1n
13,000 ppm
95.2 Ib/cycle
37.5 Ib/cycle
When the condenser 1s operated at 32°F, the steady state 1s
attained on the 2nd cycle. At the steady state the following
conditions prevail during the 2-hr regenerating time period:
F to adsorber « 3,310
C-j to adsorber 160
F to condenser * 310
Ce to condenser » 5,500
Weight of vapor
recycled 15
Weight of vapor
condensed
During the service time up to 80
3,000 ftVmin and C^ 1s 10 ppm.
ft'/min
ppm
ft'/min
ppm
,1 Ib/cycle
37.5 Ib/cycle
hr, F to adsorber is still
For the system operating at 77°F condenser temperature,
132.7 lb of vapor are adsorbed by the carbon every 82 hr of
Wh1ch 95.2 lb are recycle vapor and 37.5 lb are from the
atmosphere. For the system operating at 32*F condenser
-------
6-44
temperature, the carbon adsorbs 52.6 Ib of vapor of which
15.1 Ib are recycle vapor and 37,5 Ib are from the atmo-
sphere. Detailed calculations for the 32°F condenser oper-
ation are given in Appendix E, page E-27.
Figure 6-22 presents adsorbed-phase profiles showing
the probable status at the start of the regeneration phase
and at the end of the adsorption phases for the process
when operated at the two condenser temperatures. The ad-
sorptive capacity is measured in Ib/in. of bed length; hence
the product of capacity times bed length pives a direct
measure of pounds adsorbed under any curve.
The broken-line profile represents the status just
after regeneration has been completed. The mean capacity
° °° lb/1n. The area under the curve, Wr - 189.5 Ib,
- - - - -^ ^ -».. - . .. -. _ v ~- « v i wT'"*r*i^*vww« i 11 v» 111 % w 11 V M I-' Vk \« I b Jr
wr » 8.88 lb/1n. The area under the curve, Wr 189,5 Ib,
is the total amount remaining on the carbon after any cycle.
The profile designated by 10 ppm represents the status at
the end of the adsorption phase when no recycling 1s done.
In this case, us « 10.65 Ib/in. and the area under the curve
represents the adsorbed amount, Ws - 227 Ib. The difference,
Ws-Wr 227-189.5 « 37.5 Ib/cycle,
is the amount of pollutant vapor desorbed or removed from
the atmosphere.
When the vapor 1s recycled from the 32eF or 77"F con-
denser, the profile as indicated 1s superimposed on the 10
ppm profile. The area between the 10 and 940 ppm profile
represents 95.2 Ib recycle vapor and the area between 10
and 160 ppm, 15.1 Ib.
Theoretically, the process is feasible for pollutants
of Vm near or larger than 140 cm311q/mol. Pollutants of
lower Vm would require lower condenser temperatures to
avoid exceeding the carbon capacity with the recycle vapor.
When the concentration is high enough, recycle 1s no longer
necessary; direct steam regeneration again becomes feasible.
Very low molecular weight pollutants cannot be recovered by
this process unless the Input concentration 1s quite high
or the condenser is operated at a very low temperature.
Two-Stage Stationary Bed System
This system is intended for control of pollutants ad-
sorbed in the 10 to 100 ppm concentration range. It require;
two adsorbers or carbon beds on-stream In series. The first'
carbon bed, on the airstream Influent end, 1s designated as
the first stage and the second bed the second stage. For
-------
6-45
20
15
.160 ppm,
32°F
£ 10
a
940 ppm, recycle from
77*F condenser
recycle from
condenser
10 ppm
Adsorption phase
Regeneration phase
0
10
15
20 21.3 25
L.
Figure 6-22 Adsorbed-Phase Profiles at the End of Adsorp-
tion and Regeneration for a Gas Regeneratlon-
Condensatlon-Recycle Process, Lt " 21.3 1n.
best efficiency the bed lengths should be equal to or slightly
longer than the adsorption zone length. When adsorption zone
has moved into and completely occupies the second stage bed,
the first stage bed has become completely saturated and is
taken off-stream for regeneration by any one of the means
previously described. The second stage bed is moved Into the
first stage position and a third carbon bed, previously regen-
erated, is moved into the second stage position. The three
carbon beds are moved consecutively through the second and
first stages of the adsorption phase and then through the
regeneration phase.
-------
6-46
The flow diagram in Figure 6-23 shows the essential
components of the two-stage system. At the particular time
period depicted by the diagram, the airstream is passing
through Adsorbers 1 and 2 in succession while Adsorber 3 1s
being regenerated. When the vapors begin to penetrate Ad-
sorber 2, Adsorber 1 has become saturated with vapor and 1s
taken off-stream for regeneration and Adsorber 3 becomes the
second stage and Adsorber 2 the first stage.
This system approximates the countercurrent contacting
of the carbon and gas phase, as occurs in the fluidized bed
system, and thereby also the effective use of the carbon 1s
increased. However, with the two-stage stationary bed system
no carbon loss occurs because of attrition as it does in the
fluidized bed system.
The disadvantage is the cost of the additional ducts,
valves, more elaborate adsorber construction and controls to
operate the valves.
Two-Stage Regeneration of Stationary Bed
Figure 6-19 shows the change in desorption rate with
regeneration time for a stationary bed. As the bed becomes
heated with passage of regenerating agent, the desorption
rate increases to a maximum and then decreases as the pollut-
ant becomes depleted in the bed. In a countercurrent regen-
eration, the desorption rate does not go through a maximum
with regeneration time but settles to a constant rate.
Countercurrent regeneration is thereby contributive to better
utilization of the regenerating agent; the regenerating agent-
to-desorbed pollutant ratio is decreased.
Completely countercurrent regeneration is only possible
with systems such as the fluidized bed or moving bed of the
"hypersorption-type" described later in this chapter. Much
of the benefit of countercurrent regeneration could be
gained by multistage regeneration where many stationary beds
in series are 1n the regeneration gas stream. Saturated beds
would be intermittently added to the gas effluent end while
regenerated beds are removed from the gas influent end. The
complexity of the system would economically over balance the
benefits from the countercurrent regeneration. It Is doubtful
that the use of stages greater than two would be economical.
For a two-stage regeneration system, as Illustrated by
the flow diagram in Figure 6-24, three adsorbers are required
At the particular time period depicted by the diagram, Adsorber
1 is on the adsorption phase while Adsorbers 2 and 3 are on the
regeneration phase. Adsorber 2 1s 1n the Stage 2 position and
-------
6-47
Impure
air in
Adsorbers--
Regenerating
agent in
to solvent
recovery
_ _ ^
Figure 6-23 Two-Stage Stationary Bed System
Impure air
in
Adsorbers
Regenerating
agent in
rs *--^
ng iv
1 ?
1
1
\
/
J} ExhaustA
X air '
». i /""K.
^
"T"
A
<
4
\
V_
I
2
WLJ \
^ A
' "gr ^
-it J
V
"T"
/^l
t
/^x A .x \
i 4-
1 A
^M*i v
1 t
--T- |SOlV
_ rprr
/ V i 1
Ji i
. i
* i I
V V s
0
ent
very
Figure 6-24 Stationary Bed with Two-Stage Steam
Regeneration
-------
6-48
is in the influent end of the regeneration gas stream and
Adsorber 3 is in the Stage 1 position. When vapors begin
to penetrate Adsorber 1 it fs taken off-stream and connected
to Stage 1 position on regeneration. Adsorber 3 is moved
from Stage 1 to Stage 2 position and Adsorber 2 goes on-stream
on the adsorption phase.
The desorption rate from a two-stage regeneration will
fluctuate between maxima and minima with regeneration time.
The various pollutant disposal methods will operate more
efficiently than when operated 1n conjunction with a dual
stationary bed system.
The disadvantage 1s the cost of the additional ducts,
valves, more elaborate adsorber construction and controls to
operate the valves.
Regeneration by Pressure Reduction
When a process is operated at above atmospheric pressure,
advantage can be taken of the higher pressure in the adsorption*
regeneration cycle. The adsorption increases with Increased
total pressures since the pollutant concentration Increases 1i>
the same proportion. Conversely, on releasing the pressure
the vapors adsorbed at the higher pressure are released. A
small amount of sweep gas at ambient or elevated temperature
is then required to accelerate the removal of the vapors from
the carbon bed. Table 6-II presents estimated capacity figures
that show a ws " 0.029 Ib/lb at 8 atm pressure during the
adsorption phase and when pressure 1s released to 1 atm, ws
reduces to 0.014 Ib/lb. The operating capacity is then 0.015
Ib/lb. The large disadvantage 1s the Initial cost of the
heavy construction required for the adsorber tank and valves.
Table 6-II Effect of Pressure on Adsorptive Capacity of
Carbon for Prooanone. 10 ppm Concentration
Pressure, atm
1
2
4
8
Cl.
lb/ft3
1.48x10'*
2.96x10"'
5.92x10-'
1.18x10-*
A
18.0
16.8
15.5
14.3
us, Ib/lb
0.014
0.016
0.023
0.029
-------
6-49
Multistage with Bed Displacement
This type system is Illustrated in Figures 6-25 and -26.
Figure 6-25 shows the inverted conical shaped lower bed of
the first stage and the upright conical shaped upper bed of
the second stage. Additional stages can be added above the
second, although advantages accruing from stages beyond the
second diminish rapidly. Impure airflow is maintained through
the first stage bed until it becomes completely saturated. I.e.,
In equilibrium with the influent concentration. The carbon of
the first stage is then removed through the bottom valve and
simultaneously the carbon of the second stage lowers into the
first stage position. New or regenerated carbon from the
hopper moves into the second stage position. The spent carbon
can now be regenerated or reactivated 1n a separate unit.
The two-stage system Illustrated in Figure 6-26, has
an operating capacity of 10,000 fts/min. The upright tank
containing the carbon beds 1s approximately 8 ft in diameter
and 14 ft in height. Each stage contains about 3,400 Ib of
carbon, mean flow area is about 82 ft2, and bed thickness is
16 in. The carbon is a pelletized type of 4 to 6 mesh. In
this particular application, at a waste water treatment plant,
the carbon is displaced in each of the two stages every 134
da. The spent carbon is then activated with steam at a high
temperature (over 1600°F) to its original activity. This
means that the operating capacity 1s the total capacity of
the saturated layer rather than a fraction of the saturated
layer capacity as 1s the case in solvent recovery operations
where steam Is used for regeneration.
Service times were estimated for the above described
system at 1.0, 10, and 100 ppm concentrations for 4-methyl-
2-pentanone and propanone, as representatives of widely
divergent pollutants in regard to adsorbabl11ty. The details
of the calculations are given in Appendix E, page E-31 and
the results in Table 6-III.
Table 6-III Service Time for Pollutant Vapors at Varied
Concentrations in a Two-stage System with
Displacement of Beds
4-methyl-2-pentanone propanone
Ci, ppm MS, Ib/lb t, hr ms, Ib/lb t, hr
1 0.11 2450 0.0047 180
10 0.16 360 0.013 50
100 0.20 45 0.034 13
-------
6-50
Drum elevator
Perforated metal
conical shell
Adsorbent
Clean air
out
Impure air
1n
Figure 6-25 Multistage
Pollutant Control System,
Internal Construction of a
Two-Staqe System, Courtesy
T. Melsheimer Co., Inc.
Figure 6-26 Two-Staqe
Pollutant Control System
10,000 ft3/min Caoacity,
Courtesy T. Melsheimer Co.
Inc.
-------
6-51
This type system offers the most benefits when the
pollutants are high molecular-v/eight types and are emitted
at 1 ow concentrations. High molecular-weight pollutants,
having Vm larger than 190 cm3!iq/niol, ere not completely
desorbed by the regular steam regeneration procedures as
practiced in solvent recovery. Incomplete desorption also
occurs when the pollutant can polymerize while in contact
with the carbon. Reactivation would then be a frequent
necessity and would be a costly operation with the design
of equipment used in solvent recovery. The design of this
system minimizes the cost of transfer of carbon between the
adsorption and activation phases of the operation.
The longest service time calculated for Table 6-III
is 2450 hr or 102 da occurring at 1 ppm concentration when
the pollutant has the adsorptive properties of 4-methyl-2-
pentanone. For the control of low molecular weight pollut-
ants, as represented by propanone, or control of the heavier
molecules at 10 ppm and higher concentrations, the service
times are much shorter thereby requiring more frequent re-
activation of the carbon. The frequency and cost of re-
activation is the controlling operating cost which determines
the suitability of the system for any given application.
Cost estimates of carbon reactivation relative to the amount
of air purified show the trend to be expected. The equation
used for the estimates is
Wc reactivated x $/lb for react. , .
-£ 1 x [F/1000] ' $/hr Per 10°° ft>/min.
The estimated costs for three service times selected from
Table 6-III are given below when cost of reactivation, re-
activation losses and handling are $0.25/lb:
t. hr $/hr per 1,000 ftVmin
2450. 0.034
360 0.23
180 0.47
For the 2450-nr service time the $0.034 reactivation cost is
not significant relative to the fixed operating costs, which
are generally near $0.50/hr per 1000 ft'/min for carbon-
resorb systems. Carbon reactivation costs of $0.47/hr per
1000 ftVmin would make the multistage system noncompeti ti ve
with catalytic incineration and possibly with thermal incin-
eration if the airstream is already at an elevated temperature.
See Figure 6-31 for estimated operating costs of the different*
types of systems.
-------
6-52
A disadvantage of this system is that adsorbed pollutants
containing halogens, nitrogen or sulfur would repollute the
atmosphere when desorbed and decomposed during reactivation.
"Hypersorption" System
Figure 6-27 illustrates the "Hypersorption" system as
developed by Berg (1947) for the separation of the light
hydrocarbon gases: hydrogen, methane, ethane and propane.
The hot carbon from the steam regeneration, at the lower end
of the column, is gas lifted to the hopper at the top. On
passing through the cooler, the carbon 1s cooled with recycle
gas used in the gas lift. This is the least-strongly-adsorbed
gas of the mixture. In the adsorption section, the downward
moving carbon flows countercurrent to the gas mixture entering
the system at the inlet port. The least-strongly-adsorbed gas
is partially exhausted from the system at the discharge port
and partially as the recycle gas. The more-strongly-adsorbed
components of the mixture are carried downward with the carbon
through the rectifying section and to the stripper. In the
stripper the most-strongly-adsorbed gas is desorbed and leaves
the system at the make-gas port. The reflux of the most-
strongly-adsorbed gas displaces the next-strongly-adsorbed gas
upward in the carbon bed. This gas leaves the system at the
side-cut port. The reflux of the next-strongly-adsorbed gas
displaces the most-weakly-adsorbed gas upward in the rectifying
section and thereby forcing It Into the adsorption section.
The adsorption of methane, ethane and propane are quite
small even at atmospheric pressure, being of the order of
0.001, 0.01 and 0.20 Ib/lb, respectively. The differences
are significant so that separation is possible, but, because
of the low capacities, frequent adsorption-regeneration
cycles are required to attain a practical production rate.
By only moving the carbon and by the countercurrent
operation, three beneficial effects are realized:
1. In the regeneration phase only the carbon
and adsorbate are heated; no heat Is wasted
in reheating hardware;
2. Because of the countercurrent flow the full
adsorptive capacity of the carbon is utilized;
and
3. The transfer of carbon between the adsorptions
and regeneration phases is carried out con-
tinuously in an efficient manner.
-------
6-53
Cooler
Adsorption
section
Inlet
yas
Rectifying
section """""""
Stripper
C + a a m ~ .
Blov
nn
_*
v~
S >-
j ;* -
k x
) :>\
L
>
/er
» .
:i:
r J^ u i a v«n u 1 y c
> «^ ej j . _.. j.
/
k
I ii *^
1 Gas lift
< for carbon
i
Figure 6-27 Moving-Bed System for Separation of Low
Molecular-Weight Gases (Berg, 1947)
-------
6-54
The disadvantages relative to other carbon-resorb
systems are the higher structural costs and the loss of
carbon by attrition because of movement through the column
and the gas lift.
This system was described because the basic concept
is a potential means for removal of low molecular-weight
pollutants from air.
Rotating Axial-Flow Bed with Vapor Recycle
This system, proposed by Carr, MSA Research Corp.,
utilizes a rotating axial-flow carbon bed combined with a
condenser and recycle scheme for recovery of the desorbed
vapors. The carbon bed, illustrated in Figure 6-28, consists
of a horizontal, segmented bed which is relatively shallow
and rotates at about one revolution per hour or slower. The
pollutant vapor recycle is accomplished by a purge airstream,
which is circulated within the unit by a small blower. This
recycle is illustrated in Figure 6-30. The main pollutant
airstream is drawn down through the carbon bed and exhausted
through the center duct by a blower located on the top of
the unit. Part of the purified air forms the purge stream
(regenerating gas) which is first drawn up through the
cooling section of the carbon bed in order to cool the carbon
and heat the purge stream. The purge stream is further
heated by an electric heater and forced up through the regen-
eration section. The purge airstream, now loaded with the
desorbed pollutant vapor, is cooled by heat exchange with the
exhaust air and further cooled to a lower temperature 1n a
small refrigeration unit where the contaminant is condensed
and stored as a liquid. The purge airstream from the refrig-
eration unit is warmed by heat exchange with the purge air
to the refrigeration unit and recycled by the blower above
the carbon bed.
The rotation of the bed may be intermittent, i.e.,
rotated a distance of one or more segments at a time and
held for a predetermined time period or it may be rotated
continuously. When rotated intermittently, the desorption
rate varies over the time period in a manner similar to
curve given in Figure 6-19. When regeneration 1s performed
over two segments simultaneously but the bed rotated a
distance of one segment at each time period, the desorption
rate is considerably steadier than indicated in Figure 6-19.
However, any variation in desorption rate 1s undesirable
because of adverse effects on any of the subsequent pollut-
ant vapor disposal schemes that might be used. In this
respect continuous rotation has Its advantages.
-------
6-55
Cool ing
section
Regeneration
section
Impure air
in
Exhaust
Rotation
Carbon beds
Regenerat-
1ng gas
Figure 6-28 Rotating Axial-Flow Bed, Plan and Elevation
Exhaust
duct
Carbon bed
Gasket
Lower hood
regen. section
Compression
bars
(1) Solenoid releases pressure during
bed movement.
Figure 6-29 Rotating Axial-Flow Bed, Showing Seal Detail
and Mechanism for Raising and Lowering Bed
Upper hood
(fixed)
Regen. and cool,
section gasket
0-ring seal
-------
6-56
Impure
air In
r
Purified
air out
Carbon
bed
Den
Bed
drive
O
o
o
o
o
o
o
L
Refrlger- -*"![
ator unit
Recovered
solvent
Fan
Heat exchange
coll
C
C
C
C
C
C
C
C
C
C
C
C
Carbon
bed
Regenerating air
heater
Blower
Figure 6-30 Rotating Axial-Flow Bed with Condenser and
Recycle for Uncondensed Vapors, 3,800 ft'/mln
Airflow Capacity, 6 ft Bed Diameter
-------
6-57
The advantages of this system relative to the stationary
bed, are compactness and efficiencies produced by continuous
operation. The continuous discharge permits minimum size
and utility requirements for the auxiliary recovery or dis-
posal facilities. The disadvantages are those of maintaining
seals, more elaborate and costly construction, and wear of
moving parts* In regard to seals, continuous wear will occur
when rotation is continuous. When rotation is intermittent,
the bed can be lowered during rotation to lessen pressure
against the seals and again raised to tighten the seals for
the stationary time period. In this way maintenance on seals
Is lessened. Figure 6-29 Illustrates the seal arrangement
and mechanism for pressure release on the seals.
The effect of vapor recycle on the adsorptive capacity
of the carbon is discussed in the previous text under Gas
Regeneration with Condensation and Recycle.
Materials of Construction
As was the case for the air purification systems dis-
cussed in the prior text, one of the main concerns for
carbon resorb systems is corrosion. Activated carbons in
contact with a metallic surface establish galvanic cells
when moisture or acidic vapors are present and thereby
cause rapid oxidation at the contact interfaces. Many of
the pollutants are directly corrosive to metals and some are
decomposed during adsorption or regeneration forming corrosive
acidic vapors. The latter can cause deterioration, not only
of the retainer holding the carbon, but also of structural
surfaces although the most rapid deterioration would be at
the metal-carbon interface. To slow down or prevent cor-
rosion, structural members subject to corrosion are con-
structed of stainless steel or Hastaloy, or if constructed
of mild steel, are coated with corrosion resistant plastics.
The surface coatings must also be resistant to elevated
temperatures required during regeneration. When the carbon
is continuously or intermittently moved through the bed,
stainless steel construction is recommended since carbon is
quite abrasive and would rapidly wear away any coatings that
might be applied.
-------
6-58
A u x i 1 i ajry _Eq uj_pjn_e n_t
The emphasis in the prior discussions of air purifi-
cation and carbon resorb systems has centered on the adsor-
bent bed proper since it is the characterizing component
of the overall system. Important to the effective function-*
ing of the adsorbent bed and ultimate disposal of the pollu-
tants are the other components of the overall system. The
other components, listed in Table 6-IV, are considered
auxiliaries to the functioning of the adsorbent bed although
they may also be considered as integral parts of the overall
system depending on one's point of view. It is, however,
outside the scope of this manual to describe the auxiliaries
in any detail but within the scope to describe their tasks or
functions.
Table 6-IV Auxiliary Equipment for Sorbent Type Air
Pollution Control Systems
Hoods and ducts
Filters and scrubbers
Air coolers
Blowers
Steam generators
Inert-gas heaters
Condensers
Refrigerating units
Decanters
Thermal incinerators
Distillation columns
Heat exchangers
Carbon reactivators
Monitors
Controls
Hoods and Ducts - Hoods to collect the pollutant vapors
from the point sources with minimum airflow and ducting the
collected vapors to the sorbent system are an economic neces-
sity. By ducting,the quantity of air to be purified 1s kept
smaller and the pollutant concentration maintained higher.
Both act to reduce the size of the sorbent system required
and to reduce the operating costs.
In existing operations, the retrofitting of ducts and
the sorbent system can be a problem. Industrial processes
are often designed to conserve space with little room re-
maining for later installation of pollution control equip-
ment. Carbon resorb systems are frequently Installed out-
doors necessitating extra long ducts.
Filters and Scrubbers - When partlculate matter 1s
present in the pollutant airstream, 1t should be removed from
the airstream prior to the removal of the vapors. Partlculates
tend to form coatings on surfaces they contact. When the
particulate deposition occurs in air coolers and blowers their
operating efficiencies decrease and cleaning becomes necessary
-------
6.59
Particulates plug adsorbent beds and thereby necessitate a
costly replacement of the bed. Some particulate matters are
toxic and should be completely removed for this reason.
Particulates may be removed from the alrstream with
large area fabric filters made of organic and/or glass
fibers. These may be in a pleated form or bags. Bag filters
have a beneficial feature in that they may be cleaned and
used repeatedly.
Fabric filters of several efficiencies are available.
The high efficiency filter is used when finely divided toxic
material is present such as chemical warfare aerosols, bacteria
or radioactive dust. These filters have an efficiency of
99.97% in the capture of 0.3 micron diameter particles. When
the concern is more with protection of the adsorbent bed, an
intermediate or roughing filter may be used. The intermediate
filters are considerably less efficient than the high effic-
iency filters and are generally rated according to the National
Bureau of Standards (MBS) atmospheric air stain test at over
30% efficiency. The roughing filter takes out the coarsest
dust and are not rated according to NBS test. The cost and
resistance to airflow increase as the efficiency is raised.
As the filter becomes coated with partlculates, Its efficiency
Improves as also the resistance to flow. The initial resis-
tance of the Intermediate filters 1s between 0.25 to 0.55 1n.
of water pressure drop and when it rises to 1.0 in. during
usage the filter is replaced. *
Water scrubbers may under certain conditions be more
effective than a dry filter. This is the case when the
pollutant mixture contains highly soluble but poorly ad-
sorbed vapors. When a scrubber is used a demlster should
also be used and the alrstream heated to lower the relative
humidity.
Air Coolers - Exhaust air or gases from industrial
operations are generally at elevated temperatures. To main-
tain the adsorptive capacity of the carbon at an effective
level and also to attain more uniform adsorption-regeneration
cycles, the exhaust air is cooled down to at least 95*F.
Blowers - One or more blowers are required in the carbon
resorb systems as described in the previous text of this
chapter. For the main airflow stream the blower must over-
come the resistance primarily of the carbon bed which can
vary from 2 to 18 1n. of water pressure drop. Additional
resistance comes from the particulate filter which can
-------
6-60
vary from virtually zero to 1.0 in. of water. Resistances
to flow in the ducts, valves and air cooler are small rela*
tive to the carbon bed resistance.
Figure 6-8 presents graphs givlnq the pressure drop
through granular carbon beds of varied mesh size fractions
and as function of flow velocity.
Additional, but smaller, blowers are required for qas
regeneration, recycle of uncondensed vapors and circulation
to secondary adsorber as described in the various proposed
systems. In some cases the blower is operated at an
elevated temperature near 300°F,
For the air purification systems, the total resistance
to airflow can vary from less than 0.5 in. of water when
a filter 1s used for nontoxic vapors, to over 1.5 In. of
water, when a filter Is required for toxic chemicals.
The power consumption to operate the blower is one of
the operating costs and varies with air volume to be moved
and resistance to flow.
Steam Generators - Unless steam Is available from
other operations 1n the plant, a steam generator 1s re-
quired for the carbon regeneration phase. A low pressure
steam at near 212°F temperature has been found most effec-
tive in solvent recovery operations. Super heated steam
has not been found to be much more effective than 212°F
saturated steam. The enthalpy of the vapor at tempera*
tures above 212°F vaporizes the condensed steam and there*
by the latent heat of condensation is lost to the regen-
eration process. High temperature, high pressure steam
could reduce the steam-to-sol vent ratio but the benefit
1s offset by the Initial cost of heavier constructed ad-
sorber and valves.
Steam generation is one of the higher operating costs
1n solvent recovery operations.
Inert Gas Heaters - When steam regeneration is not
feasible, the carbon bed can be regenerated with air heated
indirectly by an electric or gas heater or the flue gas or
products of combustion from the gas burner can be used
directly as an inert gas. With Inert gases, regeneration
temperatures of 200Q to 300°F can be safely used. Higher
temperatures begin to have drawbacks 1n that cost savings
are nil and decomposition of the adsorbed vapors are
accelerated.
-------
6.61
Heating of the regenerating gas is another operating
cost but has been found to be small and does not appreciably
affect the air purification cost,
Condensers - When steam regeneration is used in solvent
recovery, a water cooled surface condenser is usually used to
condense the steam and desorbed solvent vapors. The cooling
water is one of the operating costs; the usual ratio of cool-
ing water weight to condensed steam weight is 30 to 1.0.
In the system utilizing gas regeneration and vapor re-
cycle, a condenser is used to liquify the vapors from the
regenerating gas. Where lower than ambient temperatures are
required this condenser would be cooled with a refrigerant.
Refrigerating Unit - Required to cool condensers.
Decanters - A virtually complete separation of the con-
densed solvent and steam condensate can be effected by de-
cantation when the solvent is insoluble in water. Examples
of much used solvents of this type are toluene, xylene, oc-
tane and naphtha. Theoretically, the method is effective
even at large steam-to-solvent ratios of over 30.
However, a large portion of solvents, or pollutants of
concern, are soluble to varying degrees. Such commonly used
solvents as 4-nethyl-2-pentanone and trichloroethene are
slightly soluble. The steam condensate phase will always
contain a small concentration of the solvent and thereby be
a source of water pollution. When the steam-to-solvent ratio
is small (less than 6.0) the solvent loss is not significant
costwise and the decantation method is effective. As the
steam-to-solvent ratio increases, the loss of solvent in the
steam condensate increases and, ultimately, a point is
reached where other methods of recovery become more economical,
such as condensation with recycle or recovery with a secondary
adsorber; see prior text on carbon resorb system. Often two
phases are obtained, one rich in solvent and the other poor
in solvent. This usually poses a disposal problem. In some
cases the solvent rich phase can be distilled to recover the
solvent and thereby defray the cost of disposal of the solvent
poor phase.
Distillation Columns - Solvents that are soluble in the
steam condensate can be separated from the steam by direct
fractionation of the steam-solvent vapor mixture. This pro-
cedure is economical only when the steam-to-solvent ratio is
low and the solvent quite valuable. Liquid phases are also
obtained from decantation, which can be economically dis-
tilled.
-------
6-62
Thermal Incinerators - When the desorbed pollutant vapor
cannot be effectively recovered by steam regeneration and
decantation or distillation, a more economical approach is to
regenerate with a noncondensable gas and burn the desorbed
vapor immediately. For this purpose a small thermal inciner-
ation is well suited. The size of the incinerator can be less
than one tenth of the size normally required to incinerate the
vapors from the primary airstream. See prior text under Gas
Regeneration with Incineration.
Heat Exchangers - The proposed carbon resorb systems as
illustrated by flow diagrams in Figures 6-17, -20 and -21
simultaneously heat and cool gas streams. By transferring
the heat from one stream to another, savings on cooling water
and fuel are realized.
Carbon Reactivators - In carbon resorb systems such as
the multistage with bed displacement, Figure 6-25, and the
fluidized bed, Figure 6-16, the carbon is removed from the
portion of the system where the adsorption phase 1s performed.
When the carbon shows signs of activity loss it can be readily
passed through a high temperature steam activator operating at
temperatures over 1600°F. This is the standard procedure with
the multistage system. For large installations where a small
activator can be operated continuously the cost of reactivation
would be greatly reduced.
Monitors and Controls - In solvent recovery operations,
the solvent to be recovered is known and its concentration
determined from solvent usage rate and exhaust airflow rate.
The service time to be expected may be known from past ex-
perience with other similar installations or can be estimated
by using the procedures as described in Chapter 4. It then
becomes a matter of setting a time schedule for change of
adsorbers for the adsorption and regeneration phases. This
can be automatically controlled with a timer and mechanically
operated valves.
Manometers, to measure the pressure drops across the
filter and carbon bed, signal the need for change of filter
and/or carbon bed when a pressure rise occurs.
-------
6-63
A temperature recorder before the bed can be used to
determine the efficiency of the air cooler, if one is being
used, and a temperature recorder on the effluent side of
the bed can be used to monitor the time of adsorption zone
penetration. The approach of the adsorption zone to the
effluent end of the bed is accompanied by a temperature rise
in the effluent stream. This can be used as a signal to
change adsorbers.
Steam input during regeneration should be metered to
avoid under or over regeneration and also timed to fit the
regeneration phase within the overall cycle.
The auxiliary equipment, the condensers, distillation
columns, incinerators, etc, also need to be monitored and
their operations controlled to integrate them into the over-
all operations.
When the carbon resorb system is involved in less well
defined areas of pollution control, the monitoring and con-
trol functions are more involved and difficult. It is
necessary to identify the components and determine their
concentrations in the pollutant airstream. These analyses
are required before a decision can be made regarding the
type and size of control system best suited for the partic-
ular emission source. At low pollutant concentrations the
adsorption zone temperature can be so slightly different
from that of the rest of the bed that it is not a reliable
indication of the adsorption zone position in the bed. In
cases of this type, a gas analyzer is required to signal
the adsorption zone penetration of the bed and thereby avoid
an overrun.
Chapter 8 discusses instruments that are suitable for
monitoring the adsorbent systems operations.
Operation of Carbon Resorb System
Operating Parameters - Unlike the air purification
systems, the carbon resorb systems are subject to a much
greater variety of conditions which demand modifications to
the equipment and modes of operation in order to attain the
most effective and economical service for any particular
application. The prior text, Carbon Resorb Systems, describes
various proposed and successfully used systems which show
the variety of equipment modifications that are possible
This part of the chapter discusses the operating parameters
which form the rationale for these modifications. The
-------
6-64
operating parameters that are controlHnq to varying degrees
are:
Pollutant type Flow velocity
Pollutant concentration Adsorption-regeneration cycle
Carbon type frequency
Temperature Regenerating agents
Pollutant T.yne - In assessing the pollution control
situation for an adsorbent system, the most Important prop-
erty of the pollutant that should be considered 1s Its molar
volume, designated by Vm 1n this handbook. Vm 1s used 1n
the adsorption potential equation, Equation 4-44 to calculate
A as used in the generalized adsorption isotherms, Figures
4-11 and -12. The equation 1s reproduced in a modified
form,
A - [T/Vm] log
and A
nverse ratio
See Chap.
The adsorptive capacity decreases with Increased A
increases with decrease 1n Vm because of the 1nver
and also because C0 Increases with decreasing Vm. see Chap
ter 4, Potential Theory Equations, for further discussion.
Appendix C-l gives the Vm values for pollutants of interest
In control of small emission sources.
If Vm is between 80 and 190 cmjlig/mol, there generally
are no real problems encountered 1n the adsorption and de-
sorptlon phases of the cycles. Exceptions occur when the
adsorbed vapor polymerizes and Vm thereby increases by a
large amount.
Vapors with Vm greater than 190 cmjliq/mol tend to be
difficult to desorb by the commonly used method, steam at
212°F, or by a noncondensable gas at temperatures up to
300°F. If a carbon resorb system is used and vapors of
this type are dominant 1n the pollutant mixture, high tern-
perature steam reactivation (over 1600°F) becomes a neces-
sary part of the operating procedure and also becomes a
substantial operating cost. The multistage system (Melshlmtr
system) 1s designed for these conditions in that the trans-
fer of carbon bed between the reactlvator and adsorber can
be done rapidly and with minimum of labor. The continuous*
moving bed (Hypersorber) and fluldlzed bed systems are also
readily adaptable to outside reactivation.
When the pollutant Vm are less than 80 cm3!Iq/mol, each
pollutant has to be evaluated separately because the effect
of the functional group becomes pronounced, but the general
-------
6-65
trend is for these pollutants to be poorly adsorbed. The
alternatives are to; (1) operate with a system that can be
economically regenerated frequently or continuously,or
(2) use an Impregnated adsorbent that is specific for the
pollutant.
Many pollutants have no recovery value. This creates
a disposal problem after the pollutant has been desorbed
from the carbon and alters the mode of operation, which may
be different than used in solvent recovery. When the pollu-
tant is completely combustible it can frequently be disposed
of with the least cost by immediate incineration after de-
sorption. When the pollution is noncombustible or contains
groups or elements such as NOX, SO* or Cl that will repollute
the atmosphere on incineration, it again becomes necessary
to recover the pollutant and hold it in storage until some
other means is used for its disposal.
Pollutants, or solvents, vary in their stability when
in contact with the carbon, and the presence or lack of
stability can considerably alter the operation and economics
of the control system. For example, cyclohexane and tri-
chloroethene are quite stable and carbon beds used in their
recovery last over 10 years before replacements are necessary.
4-Methyl-2-pentanone undergoes a small amount of polymeriza-
tion causing a shortening of useful bed life to 3 to 5 yr.
1,1,1-Trichloroethane decomposes forming an acid as one of
the decomposition products. To avoid corrosion when recover*
ing this solvent, Hastaloy construction 1s used. 2-N1tro-
propane decomposes yielding N02; carbon-bed fires have been
reported when this solvent has been adsorbed. 2-Butanone
decomposes to a small extent and carbon bed fires have also
been reported in this case.
In any new situation, it is necessary to know the ad-
sorbabilities of the pollutants and also their stabilities
before the best suited control unit can be designed and its
operating procedures worked out.
Pollutant Concentration - It is desirable to have the
pollutant, or solvent, vapor concentration high. I.e., up
to the 2555 LEL, since the adsorptive capacity increases with
concentration. A smaller carbon bed is then required to
control the vapors emitted from any given source. The higher
concentration allows operation with a larger operating capac-
ity for a given regenerating agent usage. Equation 4-44 shows
the effect of change 1n Ci on A and thereby on the adsorptive
capacity.
-------
6-66
The use of hoods, covering the point sources, and duct*
ing of the pollutant vapors to the control unit, as a means
for attaining higher concentrations, are important first
considerations in assessing the pollution control situation.
When the circumstances are such that the concentration is
low and cannot be raised by such means, the other components
of the system need to be designed so that the air can be
purified as economically as possible. This may mean the use
of an inert, noncondensable gas for regeneration rather than
steam. The desorbed vapors may then be incinerated, or if
incineration is not feasible, the desorbed vapors may be
readsorbed in a secondary adsorber and recovered for later
disposal as a liquid. The desorbed vapors may also be re-
covered by the condensation-recycle procedure as described
earlier in this chapter under Gas Regeneration with Conden-
sation and Recycle.
The heat evolved during adsorption can under conditions
of high concentration create problems that lower the effec-
tiveness of the carbon resorb system. The heat is evolved
in the adsorption zone and most of the heat is Initially
absorbed by the carbon in the adsorption zone. The adsorp-
tion zone and heated-carbon zone move down the bed at the
same rate. At high concentrations the temperature rise can
be sufficient to lower the adsorptive capacity of the ad-
sorption zone and thereby lower the bed capacity. The
elevated temperatures can also cause vapor decomposition
which may be especially undesirable in the presence of air.
In such cases internal bed cooling is necessary as done by
cooling coils. At low concentrations, the temperature rise
is not sufficient to cause any problems. In solvent recovery
operations, when temperature sensitive solvents are being
recovered, the adsorbers are operated in such a manner that
at least 12% moisture remains on the carbon after the steam
regeneration. The desorption of the water during the ad-
sorption phase moderates the temperature rise. See Chapter
4, Adsorption Thermodynamics, for discussion on heats of
adsorption.
Carbon Types - Commercially available carbons offered
for vapor phase adsorption by the manufacturers fall Into
fairly narrow ranges in regard to density and to adsorptive
capacity as measured by the CC14 activity. The density
range is 28 to 31 Ib/ft* and CC14 activity range 1s 50X to
60%.
A variety of mesh sizes are available but those of
greatest interest in carbon resorb systems utilizing fixed
-------
6-67
beds are the coarsest ranges, 4 to 6 and 4 to 10 U.S. sieve
size. The coarsest mesh sizes are used to keep the resis-
tance to airflow low although the coarse mesh size also
lengthens the adsorption zone length. The economics favor
the reduced pressure drop in this mesh size range. Carbons
coarser than 4 to 6 become more expensive to manufacture,
are more difficult to activate uniformly, are more friable
and also produce a considerable increase in the adsorption
zone length,
To know the response of a carbon under the many varied
applications, a generalized adsorption isotherm for the
carbon is necessary. This information is seldom offered as
part of the sales literature. The CC14 activity gives the
adsorptive capacity at only one point (A « 2.5) and is at
near saturation capacity. The slope of the generalized
adsorption isotherm (Figures 4-11, and -12) at A greater
than 2.5 has a bearing on whether the carbon is best suited
for solvent recovery or air pollution control at low vapor
concentrations and for poorly adsorbed vapors. The isotherm
with the steep slope and high CC14 activity is the better
carbon for solvent recovery while the carbon with a small
slope is better suited for adsorption at the low concen-
trations.
At times the ash content and ignition temperature of
the carbon become important parameters. The type of ash
present can affect the ignition temperature and can cata-
lyze the decomposition of the adsorbed vapors.
Hardness becomes an Important parameter in applications
where the carbon 1s moved frequently as in the multistage,
continuous moving bed or fluidized bed systems. In this
respect the pelletized carbons show a greater resistance.
Additional Information on carbons is presented at the
end of this chapter under Adsorbents and Adsorbent Systems
Manufacturers and Venders.
Temperature - Relatively small differences in the carbon
bed temperature cause large differences in the adsorptive
capacity. This is an important factor in regard to the ad-
sorption and regeneration phases of the control process.
The adsorption phase is carried out at as low a temperature
as is practical and the regeneration at an elevated temper-
ature at such a level where minimum damage is done to the
carbon, the adsorbed vapor and equipment.
-------
6-68
The temperature effect can be demonstrated in an
approximate manner by use of Equation 4.44 and a generalized
adsorption isotherm for any selected pollutant vapor. Table
6-V presents estimates on the effect of temperature on the
adsorptive capacity for 4-methylf2-pentanone on BPL V-type
carbon, isotherms in Figure 4-12,
Table 6-V Effect of Temperature on Adsorptive Capacity
and Equilibrium Concentration for 4-Methvl-2-
pentanone Adsorbed on DPI V-Type Carbon *
Temp. ,°F u, Ib/lb when C^lOO ppm Cj . ppm when u-0.20
77 0,20 100
105 0.17 300
120 0.15 640
212 0.07 13,000
300 0,03 110,000
As is apparent from the capacity figures in the second
column, the capacity decreases with increased temperature.
A temperature is ultimately reached where it is more econom.
ical to cool the airstream than to operate at the reduced
capacity. The generally accepted upper temperature limit
for the adsorption phase is near 120°F. At this temperature
the capacity is already down to 75% of the capacity at
77°F, Some solvent recovery systems are operated at 105°F,
To regenerate the carbon, it is heated with steam or a
noncondensable gas which also serve to sweep out the released
vapors. Referring to Table 6«V, if the carbon bed, saturated
to w « 0.20 Ib/lb, were sealed off and heated to 212°F the
4-methyl-2-pentanone concentration would rise to approximate**
ly 13,000 ppm and at 300°F to 110,000 ppm. On releasing the
pressure a considerable amount of the vapor would desorb and
with a sweep gas the desorption rate would be accelerated,
To remove all of the adsorbed vapor, it would, however,
require a large amount of sweep gas. At 212°F, when
-------
6-69
bed area that will give a practical flow velocity. The
decision on the practical flow velocity takes into consid-
eration the adsorption-regeneration cycle frequency, the
bed dimensions and resistance to flow. For a given flow
rate and concentration, the adsorption-regeneration cycle
frequency is determined by the bed volume, or weight, and
operating capacity. In solvent recovery the cycle time is
near 1.0 hr while in pollution control the adsorption phase
may last the duration of an 8-hr work day and the regener-
ation performed during off-working hours. The dimensions
of the bed may now be adjusted for the fixed bed volume
that will give the best compromise on the resistance to
flow and the structural design of the bed. A bed with a
large area and short length will operate at lower flow re-
sistances but for structural reasons may not be the best
design.
The air velocities commonly used are in the range 30
to 110 ft/min in the various types of carbon resorb systems.
The trend is toward the higher velocities, particularly in
the stationary bed solvent recovery systems. Bed lengths
range from 8 to 36 in. In order to hold the flow resistance
as low as possible, coarse, 4 to 6 mesh size, pelletized
carbons are frequently used. High flow resistance, aside
from consuming more power for the blowers, also cause oper-
ational problems with the valves.
When pressure drop measurements are not available for
the particular carbon being considered, an estimated pressure
drop can be read-off from predetermined curves such as shown
1n Figure 6-8, or calculated with Equation 4-42.
Flow velocity also affects the adsorption zone length,
although in carbon resorb systems this is not a critical
factor. Even at the 110 ft/min flow velocity and for coarse
mesh carbons, the adsorption zone length is less than 4.0
in., compared to total bed length of 12 in. and longer.
Equation 4-32 gives the relationship between flow velocity
and adsorption zone length.
Adsorption-Regeneration Cycle Frequency - The optimum
cycle frequency is attained when the combined cost of the
adsorption and regeneration phases is at a minimum. For a
fixed operating capacity, the adsorption phase cost increases
with service time because of the cost of additional carbon
required and the increase in the per unit-time power con-
sumption for the blower. When the service time is shortened
I.e.. regeneration frequency 1s Increased, the regeneration '
cost rises because of the additional fuel consumption for
-------
6-70
the more frequent heat-up of the carbon bed and associated
hardware. Steam utilization is also less efficient for the
shorter carbon bed. The adsorption phase time period and
the regeneration phase time period need not be equal although
equal phase time periods have worked-out best for stationary
bed solvent recovery systems.
To avoid underrun or overrun on the adsorption or re-
generation phases, monitoring devices are desirable to signal
the completion of each phase. For the adsorption phase, the
monitoring device would be required to detect the penetration
of the adsorption zone lead edge. For the regeneration phase
the monitoring device would be required to measure the vapor
concentration in the regenerating agent and, when the con-
centration has dropped to-a predetermined level, signal
the end of the regeneration phase.
Regenerating Agents - The regenerating agent used in
solvent recovery is steam. It has several properties that
make it uniquely suited for this purpose. Its saturated
vapor temperature is at a temperature level where many of
the solvents of recovery value are poorly adsorbed or become
readily desorbable, but the temperature is not too high to
cause extensive damage to the solvents. The heat of con-
densation is high, hence saturated steam rapidly delivers
a large amount of heat to the carbon at virtually a con-
stant and moderate temperature. A great many solvents are
fairly insoluble in water; condensation of the steam-vapor
mixture and decantation effect a satisfactory separation
and liquid solvent recovery. Steam is fairly Inactive with
most solvents although some decomposition is reported either
because of direct action with the steam and/or catalytic
help from the carbon. The steam also provides an atmosphere
in which combustible vapors can be handled safely at high
concentrations.
In solvent recovery with steam regeneration the carbon
acts as a collector or transfer medium. It collects the
solvent from the noncondensable air and transfers 1t to the
condensable steam from which it can be readily separated
by decantation or distillation. Usually the volume of
steam used is not much less than the vapor-laden air and
the concentration of solvent Initially 1n the alrstream
is not much less than the solvent concentration 1n the
steam.
In air pollution control applications where the
pollutant concentrations are low and, in addition, the
-------
6-71
pollutants may have no recovery value, steam regeneration
is frequently not the best regenerating agent. Because of
the adsorption at low concentrations, the vapors are held
tightly by the carbon and, relative to the amount of pollu-
tant adsorbed, the amount of steam required is large. Under
these conditions even slightly soluble organic compounds are
completely dissolved in the steam condensate. Under these
circumstances the more economical approach is to regenerate
with a noncondensable gas such as air, or, if there is danger
of explosion, regenerate with an inert noncondensable gas
such as flue gas. As already described earlier in this
chapter the use of noncondensable gas entails considerable
changes in equipment and operating procedures.
In the adsorption processes at the low pollutant
concentration, the carbon acts as a concentrator. The car-
bon collects the pollutant vapor from a large volume of air
over a long period of time during the adsorption phase.
During regeneration the vapors are released from the carbon
at a high concentration, in a relatively small volume of
regenerating gas, and in a relatively short period of time.
Disposal of the pollutant now becomes an easier task. The
effluent mixture of regenerating gas and pollutant vapor may
now be treated in a small incinerator to burn the vapor, or
be passed through a condenser to liquify the vapor for
separation, or readsorbed in a secondary adsorber and re-
covered by steam regeneration.
Polar Adsorbent Systems
No installations appear to be in service for air-
pollution control which utilize the polar adsorbents: silica
gel, activated alumina or molecular sieves. They are, how-
ever, being investigated for this application under very
specific conditions. The molecular sieves have a potential
application for control of SOX and NOX from exhaust gases.
Because of the polarity and water solubility of these mole-
cules, they can be effectively adsorbed from a humid air-
stream. Silica gel and activated alumina have a potential
application in the control of high molecular weight vapors
(of Vm greater than 190 cm'/mol) from dry airstreams
Their greatest usefulness is as desiccants and also for the
separation of dry organic liquids and vapors. See Chapter
4, Adsorbent Types, for discussion of polar adsorbents.
For air pollution control the systems design would
not be greatly different from the carbon resorb type 5
modification would be required because of differences in
mode of regeneration. Steam or water would be the most
Some
-------
6-72
probable regenerating agent. Prior to start of the adsorp.
tion phase, the water would have to be removed from the
adsorbent. Molecular sieves require fairly high drying
temperatures.
Impregnated Adsorbent Systems
Iodine Impregnated carbons are used 1n atomic enerqy
plants to prevent escape of radioactive methyl Iodide 1n
case of a breakdown of the reactor. This 1s an exchange
reaction of radioactive Iodine 1n the methyl Iodide with
nonactlve Impregnant on the carbon. The type filter used
1s Illustrated 1n Figures 6-3 and -4. These are considered
nonregeneratlve although In time the radioactivity would
decay completely.
For toxic chemicals such as phosgene, cyanogen chloride
and hydrogen cyanide, carbon Impregnated with copper oxide
and hexavalent chromium are very effective. The type filter
used 1s Illustrated in Figure 6-3. These are nonregenera-
tlve. When the chemicals have reacted with the stolchlo-
metrlc amount of pollutant, the carbon 1s replaced.
CatalystImpregnated Carbon Systems
The use of catalytic Impregnants to permit 1n-place
reactivation of a spent carbon bed was proposed and labora-
tory tested by Turk (1955). The carbon 1s Impregnated with
2% to 3% of an oxide of chromium, molybdenum, tungsten,
cobalt or copper. After the carbon has become saturated
with organic vapors by normal adsorption, the reactivation
1s Initiated by raising the temperature of the bed to effect
catalytic oxidation of the adsorbed organic compounds or
their vapors as they are being desorbed.
As 1n catalytic Incineration, the oxidation rate
Increases with Increased temperature, I.e., complete oxida-
tion becomes more probable as the temperature 1s raised.
In catalytic Incineration, operating temperatures at which
combustion efficiencies are 90% and better with reasonable
sized units are 1n the range 600° to 900°F, Ignition temper.
atures of carbons vary but are between 600° to 700°F, hence
the optimum temperatures for combustion catalysis cannot be
used. Some sacrifice 1n regard to completeness of combustion
1s necessary unless some corrective measures are taken. A
corrective measure that can be taken to avoid air pollution
by the combustion products 1s to recycle the gases through
the bed or Install a small thermal Incinerator to complete
the combustion. Discussions on catalytic Incineration are
given In Chapter 7 and on the use of thermal Incinerators
-------
6-73
for combustion of desorbed pollutants are given 1n this
chapter under Carbon Resorb Systems.
The potential advantage over an unlmpregnated carbon
system would occur when the pollutants are of type that
polymerizes on adsorption, thus making their desorptlon
Impossible by the more conventional regeneration procedures,
or are nondesorbable because of high molecular weights. In-
place catalytic oxidation of these pollutants to lower mole-
cular weight components would effect their desorption.
The construction of the adsorbent system would be
similar to those already described for carbon resorb but
modified so that regeneration at temperatures up to 600°F
are possible.
Economic Analyses
General Discussion
In the evaluation of the adsorbent systems relative to
the catalyllc and thermal Incineration systems, the final
decision as to which type of system should be used for a
given control problem is based on the cost of cleaning a
unit volume of air. When a cost analysis clearly indicates
that a carbon resorb system should be used, further analysis
involving the operating parameters can Indicate the optimum
operating procedure. An approach Is taken in this section
of the chapter that supplied answers in both of these areas.
To work up the estimated costs of air pollution control,
data on various operating costs are required. Common to all
three types of systems are the costs of:
Depreciation
Operating labor
Maintenance
Electric power
Fuel
The catalysts used in catalytic incinerators frequently
deteriorate faster than the rest of the system. Its re-
placement thereby becomes a direct major operating cost and
should be added to the above list when referring to cataly-
tic incineration. Frequently, activated carbons also de-
teriorate faster than the rest of the system; the replacement
cost should be added to the above list when referring to
carbon resorb systems. An additional cost in the operation
of some carbon resorb systems 1s that of cooling water used
-------
6-74
for vapor condensation. In order to determine the depre-
dation cost, the initial equipment and-installation costs
(fixed capital) should be ascertained.
Cost estimates for carbon resorb systems were prepared
for 4-methyl-2-pentanone, trichloroethene, and propanone at
influent flow concentrations of 10, 100, 300, 500, 1000 and
3000 ppm and flow rates of 800 and 3,800 ft'/min. The es-
timates are presented on a $/hr per 1000 ft'/min flow rate
basis. The systems analyzed are:
1. Stationary bed with steam regeneration and
solvent separation by decantation
2. Stationary bed with air regeneration and
thermal Incineration of combustible desorbed
pollutant vapors
3. Rotating axial flow bed with air regeneration,
desorbed vapor condensation and vapor recycle.
Comparative costs of air cleaning at varied pollutant
concentrations are presented for carbon resorb and the
incineration systems. The effect of pollutant molar volume,
pollutant concentration, flow rate, and adsorption-regeneration
time on the cost of air cleaning are also Investigated.
Operating Costs
Fixed Capital - Cost Information for the catalytic and
thermal incineration processes was collected from several
sources: ASKRAE (1966 and 1967), Meinhold (1963), UOP, -and
Phillip (1971). Equipment and/or depreciation costs from
these sources were generally for larger capacity systems than
the 3,800 ft3/min airflow. In these cases the 0.6 power
factor was used to estimate the cost for the system at the
3,800 ft'/min flow capacity, thus:
0.6
Cost for 3,800 system [3,800/F] [cost of larger system]
where F is the flow capacity of the larger system.
Installed costs for the catalytic incinerator vary
between $3,500 and $6,000 per 1,000 ft'/min air handling
capacity. The higher end of the range includes cost for
heat exchangers, filters for partlculate removal and also
reflects the costs of more expensive catalysts. As the
size increases, the cost per 1000 ft'/min flow capacity
decreases to some extent, but for the range 2,000 to 10,000
-------
6-75
ft /min flow capacities, the costs per unit flow volume were
assumed essentially constant. For these estimates, the
higher $6,000 figure was used at concentrations below
the self-sustaining concentrations (below about 3.000 pom)
since heat exchangers give a decided operating cost reduc-
t10n%o^°rrtJhe 3»800 ft /m1n system the installed cost is
then $23,000*
The installed cost for a thermal incinerator of 3,800
ft'/min airflow capacity, with heat exchanger is approxi-
mately $29,000 or $7,600 per 1,000 ftVmin capacity.
For custom designed solvent recovery systems, the
installed cost will usually range from $10,000 to $15,000
per 1000 ft'/min airflow capacity. Package type systems
are available at a considerably lower cost. The equipment
cost at the manufacturer's plant can range from $2,000 to
$3.500 per 1,000 ft'/min capacity. Freight and installation
costs must be added to these figures (Cooper, 1967).
For the air pollution control cost estimates presented
here, the base prices on stationary bed systems are those
provided by Vic Manufacturing Co. and Hoyt Manufacturing
Corporation. Table 6-VI presents the approximate systems
costs and sizes over a range of airflow capacities from
700 to 5,000 ft'/min per adsorber. Single and double ad-
sorber systems of 3,800 ft'/min capacity cost $19,480 and
$32,500. respectively. Installation costs raise the fixed
capital costs to $21,500 and $35,800, respectively. A cost
estimate was also prepared for airflow of 800 ft'/min A
dual adsorber system at this capacity level costs $6.200
and when Installed, $7,000.
For the stationary bed utilizing air regeneration and
thermal incineration, the above costs were used for the
adsorber section of the system and cost added for scaled
down sized thermal incinerators. The installed cost of a
single adsorber, 3,800 ft'/min capacity system with desorbed
VJPSnn !ClJnna^s/°fer?t1n9 at re9enet1ng gas flow range
of 200 to 500 fts/min 1s approximately $26.000.
For the axial flow bed continuous recycle system it
was necessary to work-up the cost from basic component
parts. The size and cost for a 3,800 fts/m1n capacity
system varies some with type of pollutant and concentration.
The installed cost range Is $16,500 to $19,800. atlon-
Depreciation - For the carbon resorb. catalytic and
thermal incineration systems, a 10-year depreciation rate
-------
en
i
»-j
en
Table 6-VI
ftVmin
700
750
750
800
800
800
1700
1700
1700
1700
3000
3000
3800
3800
5000
Equipment Cost and Slze^1^
Base
pr1
1
2
3
3
4
6
6
5
10
8
10
16
19
32
38
c'e, $
,280
,180
,340
,920
,070
,160
,820
,280
,770
,080
,100
9 "
,540
.480
| ~f %* W
,500
,800
No.
of
tanks
1
1
2
2
1
2
1
1
2
2
1
2
1
2
2
Carbon
Auto, or Motor per tank
manual
M
M
M
N
A
A
A
M
A
M
A
A
A
A
A
1
1
2
3
3
7
7
7
7
20
20
30
30
HP
3/4
1/2
1/2
1/2
1/2
1/2
-
«
Ib
350
350
350
350
350
350
1000
1000
1000
1000
1500
1 500
3000
3000
5400
Shipping
vreiqht ,
Ib
1030
1100
1500
1650
1950
2400
4000
4000
7000
7000
4800
9300
12000
18000
--
Size,
w x 1
49
49
77
77
63
67
92
11
x
X
X
*
X
X
X
1
&*
45
45
45
--
84
--
--
11
..
97
--
x 1
In,
x h
x 81
x 81
x 81
x 81
x 95
8 X 114
x 137
82 x 140
(1) Based on Information
Manufacturing Company.
(2) Tank or adsorber.
provided by: Hoyt Manufacturing Corporation and Vic
-------
6-77
1s used in the estimates prepared in this handbook although
systems lives of up to 20 yr are claimed under various cir-
cumstances. The control system life can vary considerably,
before major repairs are required, depending on corrosive-
ness of the pollutant vapors, frequency of the adsorption-
regeneration cycles, and continuity of operation, I.e.,
whether intermittent or continuous.
For the estimates in this handbook, an 8-hr da, 2080-hr
yr, operating basis was used. For carbon resorb systems, the
depreciation cost on the 8-hr basis is approximately one-half
of the total operating cost. For the Incinerators, the de-
preciation cost on the 8-hr basis is about one-third of total
cost at low concentrations but approaches one-half at 2555 LEL
concentrations. By adjusting the operating time closer to
continuous operation, the total operating cost can be reduced
by 30%. The estimated cost figures are on the high side in
this respect but retain their correct relative positions for
the three types of systems.
Operating Labor - Low labor costs are generally claimed
for the operation of the carbon resorb and incineration
systems. A low level of operating cost has been estimated
on the basis of 5 min of labor per 8-hr shift for each 1,000
ft3/min capacity (Hein, 1964). For the estimates for this
handbook a considerably lower labor rate 1s used, $300/yr
at $10 per man hour.
Maintenance - Yearly maintenance costs for catalytic
Incinerators have been estimated by some analysts on the
basis of 10% of the initial incinerator cost (Hein, 1964).
Other methods can consist of periodic catalyst replacement
cost combined with a low percentage rate of the initial
incinerator cost. For the estimates in this handbook, the
overall yearly maintenance cost combines a $1,200/yr cata-
lyst replacement cost and a 2% of initial capital.
For the thermal Incineration a straight 2% of Initial
capital 1s used for the yearly maintenance cost.
For the carbon resorb systems, the overall yearly
maintenance cost combines a $300/yr carbon replacement
cost and a 1% of Initial capital.
Electric Power - The main electrical power consumer is
the air circulating blower. The kilowatts to move 1,000
ft'/min of air through the Incinerator or carbon resorb bed can
vary from 1.5 to 6.0 depending on resistance to flow. Local
electrical costs per kilowatt-hour will determine the power
costs.
-------
6-78
For the stationary bed carbon resorb systems, which
are operated at bed lengths of 30 1n., the blower power
consumption is about 6 kilowatts per 1,000 ft*/min. Addi-
tional but small power requirements are needed to operate
monitoring and control devices. At a rate of $0.015/kwh,
the yearly cost of electrical power for 2080 hr of blower
operation is $710. An additional $60/yr for the other power
costs brings the total to $770/yr. For the rotating axial
flow bed system with condensation and vapor recycle, electric
power is also required for refrigeration and regenerating
gas heating. For the incinerators which operate at lower
airflow resistances, the power cost is $500/yr.
Fuel - Fuel in the form of natural gas is required in
steam and noncondensable gas regenerations, and to preheat
the air-pollutant mixtures for the incineration processes.
Natural gas costs vary for different locations but a gen-
erally accepted average cost figure is $0.60 per 1,000 ft*
or $0.60 per 106 Btu. On the basis of gas consumption,
steam generation costs $0.60/1000 Ib, but due to heat losses,
the generally accepted cost is $1.00/1000 Ib. Noncondensable
regenerating gas heating costs are considerably less than for
steam because no latent heat is involved. To heat air to
300°F, the cost is about $0.05/1000 Ib and to heat air to
400°F, $0.07/1000 Ib. The amount and type of regenerating
agent required varies with the influent concentration and
pollutant type, see Chapter 4, Regeneration of Activated
Carbons for further discussion.
Fuel costs to preheat the pollutant airstream for the
incineration processes vary considerably with the concen-
tration and to a lesser extent with type. Preheat require-
ments are discussed in Chapter 7, under Pollutant Concen-
tration.
Cooling Water - Cooling water is required to condense
the steam-pollutant vapor mixture. The ratio of cooling
water at ambient temperature to steam is 30 to 1.0. Water
cost varies with the locality but the generally accepted
cost is $0.10/1000 gal. Cooling water may also be used for
condensation of vapors from noncondensable regenerating gas,
Pollution Control Costs
Comparative Costs of Competing Systems - Relative
pollution control costs for the competing systems are
graphically presented in Figure 6-31. It is recognized that
actual operating costs can vary markedly depending on local
utility rates, operating time, choice of operating conditions.
and sophistication or completeness of the system. The cost
-------
6-79
1.40f
1.20
1.00
c
li
v*
n
* 0.80
o
o
o
£ 0.60
o.
0.40
0.20
0.0
JTTTT] I ' i | ""I
Thermal incineration
Catalytic Incinerati
Carbon-resorb
+ Incinerati
Carbon-resorb,
no solv. credit
or disposal cost
Carbon-resorb
solvent credit
4-methyl-2-pen-
tanone
propanone
it \i '
i I i 1111 i i i \ i iii
i i
hlL
10
100
1000 3000
ppm
Figure 6-31 Comparative Costs of Pollution Control with
Carbon Resorb, Catalytic Incineration and
Thermal Incineration, 3,800 ft*/m1n Capacity
System, Calculations Based on 4-Methyl-2-pen-
tanone and Propanone, 2080 hr/yr Operating
Time .
-------
6-80
factors that were used are detailed 1n Tables 6-VII and -VIII.
In some cases, it may be possible to ratio the cost factors
to reflect actual local conditions.
Minimum pollution control costs result where credit can
be taken for the recovered solvent as indicated by the low-
est curve in the figure (for 4-methyl-2-pentanone). Although
this solvent is slightly soluble in water, it was assumed 1n
making the solvent credit calculations that complete re-
covery had been effected (by decantation) even at operations
at the 10 ppm influent concentration level. The curve illus*
trates the results achievable where solvent recovery 1s
feasible and the solvent has recovery value. In this case
the cost breakeven point is at Ci " 500 ppm; recovery oper-
ations at { greater than 500 ppm would be profitable. The
breakeven point varies. For some solvents it 1s at Ci over
1,000 ppm, but a good average is at Ci * 700 ppm.
Below about 200 ppm and assigning neither credit nor
disposal cost to the recovered solvent, the lowest pollution
control cost is still indicated for the carbon resorb system.
In this concentration range, a single adsorber unit operating
on an eight-hour working cycle with regeneration at night
was assumed. Here the cost level 1s just above $0,50. The
sharp Increase in operating cost, to over $0.80, shown
between 200 and 500 ppm, results from the switch to a double
adsorber unit, because of the necessary increase in fre-
quency of regeneration. The cycle time here is one hour.
The next lowest operating cost, below 200 ppm, 1s
shown for a combination of carbon resorb and thermal incin-
eration. In this system the resorb unit is used to concen-
trate the pollutant to 25% of LEL before incineration. Air
heated by the combustion unit exhaust is used for carbon
regeneration. The pollution control cost is slightly over
$0.60 but begins to rise rapidly at concentrations above
200 ppm because of the increase in cycle frequency and need
for an Increasingly larger back-up incinerator.
As shown by the upper two curves, catalytic and thermal
incineration provide the lowest disposal costs at pollutant
concentrations above about 1000 ppm.
Pollutant Molar Volume - The effect of pollutant molar
volume on the air cleaning cost was Investigated for the
three vapors under study. The results are summarized 1n
Table 6-IX. They show no significant differences although
the Vm range brackets a considerable portion of the pollutants
of interest. These cost figures are for steam regeneration
with no credit for pollutant recovery or disposal cost, 1.e,.
-------
Table 6-VII Cost Factors for A1r Pollution Control by Carbon Resorb Systems
Design basis
Airflow:
Pollutant:
Carbon:
Operation:
3800 ftVmin at 77°F
4-methy1-2-pen tanone
4 to 6 pelletized, 3000 Ib/adsorber
8 hr/da, 2080 hr/yr
Influent concentration,
Regenerating agent
Regenerating agent temp.,
Number of carbon adsorbers
Installed equipment cost.
Airflow to Incln., ft3/
Operating costs, $/yr
Steam at $1.00/1000 Ib
Water at $0.10/1000 gal
Power at $0.015/kwh
Gas at $0.60/1000 ft3
Operating labor at $10/hr
Carbon replace (5-yr life)
Maintenance
Depreciation (10-yr life)
Total
$/hr per 1000 ftj/m1n
Pollutant recovered. Ib
Pollutant value at 50.1
$/yrO)
Operating cost - rec. v
$/hr x 1000 ftVminl1)
ppm 10
Steam
,°F 212
rs 1
, $ 21,500
V ~ w
1n
208
80
770
r 300
e) 300
215
) 2,150
4,023
0.51
yr 1,090
5/lb,
147
lue
0.49
Typical
100
Steam
212
1
21,500
--
400
154
770
300
300
215
2,150
4,289
0.54
10,900
1,470
0.36
resorb
500
Steam
212
2
35,800
-
800
310
770
_
300
600
360
3,580
6,720
0.85
54,500
7,300
0
unit
1000
Steam
212
2
35,800
900
350
770
_ _
300
600
360
3,580
6,860
0.87
121,000
16,300
Resorb
10
Air
200
1
26,000
200
--
--
800
610
300
300
390
2,600
5,000
0.63
--
--
--
+ incineration
100
Air
200
1
26,000
200
..
--
800
610
300
300
390
2,600
5,000
0.63
--
~
300
Air
200
1
26,000
500
--
--
800
1,420
300
300
390
2,600
5,810
0.73
-
-
(1)
Cost of separating pollutant from condensate not Included
i
CO
-------
tn
i
Table 6-VIII Cost Factors for Afr Pollution Control by Catalytic and Thermal
Incinerators
Design basis
Airflow: 3800 fts/m1n at 77°F
Pollutant: 4-methyl-2-pentanone
Operation: 8 hr/da, 2080 hr/yr
Catalytic^1)
Influeht cone., ppm
Installed equipment
cost, $
Operating cost, $/yr
Power at $0.015/kwh
Gas at $0.60/1000 ft3
Operating labor at
$10/hr
Catalyst replacement
Maintenance, 2%
Depredation, (10-yr
life)
Total
$/hr x 1000 ft'/mln
10
23,000
500
2,900
300
1,200
460
2,300
7,660
0.97
100
23,000
500
2,750
300
1,200
460
2,300
7,510
0.95
1000
23,000
500
1,400
300
1,200
460
2,300
6,160
0.78
3000
23,000
500
200
300
1,200
460
2,300
4,960
0.63
10
29,000
500
5,800
300
m
580
2,900
10,080
1.27
Thermal*1*
100
29,000
500
5,600
300
--
580
2,900
9,580
1.25
1000
29,000
500
3,960
300
--
580
2,900
8,240
1.04
3000
29,000
500
320
300
--
580
2,900
4,600
0.58
(1) 50* heat recovery
-------
6<83
the pollutant and steam condensates are sewered. When re-
covery or disposal (by nonpolluting means) is carried out,
the costs become variable depending on concentration, com-
bustibility and water solubility.
Table 6-IX Effect of Pollutant Molar Volume and Con-
centration on Air Cleaning Cost When No""
Pollutant Recovery or Disposal Cost is
Considered
4-methyl-
2-pentanone trichloroethene nropanone
Vmi cm'liq/mol 140 94 74
Costs when Cj 3,000 ppm, $/hr per 1,000 ft'/min
Steam and cooling
water
Fixed
Total
Costs when Cj « 1,000 ppm, $/hr per 1,000 ft'/mln
Steam and cooling
water
Fixed
Total
Costs when Ci « 100 ppm, $/hr per 1,000 ft'/min
Steam and cooling
water
Fixed
Total
Pol 1utant Concentration - The effect of pollutant con-
centration on air cleaning cost is shown 1n Figure 6-31 and
Table 6-IX. The general pattern is for the air cleaning
cost to rise with increased concentration. With reference
to Table 6-VIII, the cost at C^ 3,000 ppm 1s at the $0.90
level while at Cj - 100 ppm it is at the $0,50 level. When
disposal of pollutant of no recovery value Is added to the
process,the costs rise but the cost pattern remains. Only
when a pollutant of value is recovered is the pattern re-
versed, as shown by the lower curve 1n Figure 6-31.
-------
6-84
Flow Rate - The effect of flow rate, or more correctly
the flow capacity, on air cleaninq cost does not follow the
usual pattern observed, i.e., decreased cost with increased
size. Cost figures worked up for Table 6-X show a small
Increase in air cleaning cost when a larger unit Is used.
Table 6-X Cost Factors for Air Pollution Control by
cTrbon-Resorb Systems at Two Flow CapaciTies
Design basis
Pollutant: 4-methyl«2-pentanone
Concentration: 1000 ppm
Carbon: 4 to 6 pelletized, vapor phase
Operation: 8 hr/da, 2080 hr/yr
Flow rate 800 ft'/min 3,800 ft'/mln
Installed equipment cost $7,000 $35,800
Pounds carbon/adsorber 350 3,000
Operating costs. $/vr
Steam at $1.00/1000 Ib
Water at $0.10/1000 gal
Power at $0.015 kwh
Operating labor at $10/hr
Carbon replacement (5-yr life)
Maintenance, 1.0% of invest.
Depreciation, (10-yr life)
Total
$/hr per 1,000 ft3/min 0.83 0.87
Two operating costs, the operating labor and maintenance, are
subject to adjustment which could reverse the air cleaning
cost figures. The general impression is that at least in the
flow capacity range from 800 to 10,000 ftj/m1n the air clean*
ing costs do not vary greatly with size change.
Adsorption-Regeneration Cycle Time - Every air pollution
operation can be optimized with respect to the adsorption*
regeneration cycle time length. For a given control situation
the cycle time is dependent on the operating capacity select**
Operating capacity is the difference between the saturation *
capacity, us, at the particular Influent concentration, Cf,
and the mean amount of adsorbed pollutant, urt remaining on
the carbon after regeneration.
-------
6-85
The primary cost factor that varies with the cycle time
is the steam consumption, hence a study of steam consumption
as function of cycle time or operating capacity leads directly
to the cycle time effect on air cleaning cost. Results of
this type calculation are presented graphically in Figure
6-32. For these calculations, the carbon resorb system con-
sisted of two beds with 3,800 fts/min airflow capacity for
each bed. 4-Methyl-2-pentanone at 500 ppm concentration was
used as the representative pollutant. As shown in the figure,
the steam consumption for heating decreases as the cycle time
increases. This reflects the decrease in number of times the
carbon and associated hardware have to be heated. The steam
consumption for sweeping the pollutant vapors out of the bed
increases rapidly with increase in cycle time. This reflects
the decrease in vapor pressure as the pollutant is progress-
ively removed from the carbon. (See Chapter 4, Regeneration
of Activated Carbon for further discussion.) For this par-
ticular system, the total steam consumption passes through a
minimum at the 2-hr cycle time,
Table6-XI gives the operating capacity, ws-ur, the number
of cycles per year and the air cleaning cost ($/hr per 1,000
ft /min) for the above discussed pollution control conditions
when no credit for recovered vapor or vapor disposal cost is
taken into consideration. The minimum cost is $0.83 at the
Table 6-xl Effect of Cycle Time on Cost of Air Cleaning for
3.800 ftVmin Carbon-Resorb System. 500 ppm
Pollutant Concentration with Steam Regeneration
Cycle time 1 hr 2 hr 5 hr
us-wr, Ib/lb 0.012 0,024 0.061
Cycles/yr 2080 1040 416
$/hr per 1000 fts/min 0.85 0.83 0.89
2-hr cycle time or 0.024 Ib/lb operating capacity. Over the
cycle time range investigated, the cost differences are not
large, but the cost difference would become very large at
cycle times over 5 hr. At concentrations larger than 500 nnm.
the minimum cost shifts to cycle times approaching the 1-hr
level and at smaller concentrations the minimum cost shifts
to cycle times longer than the 2 hr.
Rotating Bed with Condensation and Recycle . To determine
whether some of the proposed innovations to the more con-
ventional single or double stationary bed solvent recover*
systems can be more economical for air pollution control cost
-------
6.86
1200
Sweep steam
(75* efficiency)
000
2 3
Cycle time, hr
Figure 6-32 Steam Requirement for Regeneration vs
Pollutant Loading and Cycle Time, Carbon*
Resorb System on 4-Methyl-2-pentanone,
3,800 ft'/mln Flow, 2080 hr/yr Operating
Time.
-------
6-87
estimates were worked up for the continuous vapor recycle
system. This system utilizes hot air regeneration, recovery
of desorbed vapors by condensation and recycle of unadsorbed
vapors to the carbon bed. Figures 6-28, -29 and -30 describe
the system. The cost factors and air cleaning costs are
given in Tables 6-XII and-XIII for a 3,800 ft'/min system
operation at several concentrations of 4-methyl-2-pentanone
or propanone.
The results show a lower air cleaning cost for 4-methyl-
2-pentanone (the higher boiling liquid) by the continuous-
recycle system than by the stationary bed systems. At 100 and
500 ppm concentrations, the costs are $0.46 and $0.54/hr per
1,000 ft'/min, respectively. For propanone, the air cleaning
costs are the same, i.e., $0.55/hr per 1,000 ft'/min. In each
case, the continuous-recycle system produces a separated
liquid pollutant (or solvent) which may then be reused or
disposed of by any means deemed best. The air cleaning cost
by the stationary bed system leaves the pollutant dissolved
in the steam condensate. When the stationary bed system is
used with noncondensable gas regeneration plus incineration
of desorbed vapors, the air cleaning cost rises to $0.63/hr
per 1,000 ft'/min. The continuous recycle system appears
more economical at the lower pollutant concentrations, al-
though, admittedly there are also more uncertainties in the
cost factors used in working up the estimates.
Adsorbents and Adsorbent Systems' Manufacturers and Vendors
Activated Carbons
Table 6-XIV lists under each manufacturer's name the
trade name, properties and selling price range of gas-nhase
carbons that are suitable for air pollution control applica-
tions. For most applications, the interest is In the coarse
mesh sizes, 4 to 6 or 4 to 10, although in some toxic chemi-
cal, biological and radiological applications the finer 12
to 30 mesh is also used. The density range 0.45 to 0.50
or 28 to 31 lb/ft3 appears to be fairly standard. In regard
to adsorptive capacity, this density range is optimum when
measurements are made on the unit carbon volume basis. Some
carbons are pelletized and others granular. The pelletized
carbons tend to be slightly harder and, because of the
narrower mesh size range, usually offer less resistance to
airflow than granular carbons of equivalent mean granular
diameter. In regard to adsorptive capacity, as measured by
the CCU activity, most carbons fall in the range 50% to
6035; see test procedure in Appendix D. The CC14 activity
essentially measures the micropore volume of pores less than
30 X in diameter; see Chapter 4, Activated Carbon Pore Size
Distribution for significance of CC14 activity in regard to
porosity.
-------
6-88
Table 6-XII Estimated Operating Cost. Continuous Recycle^
Unit Including Solvent Recovery
Design basis
Airflow:
Carbon:
Operation:
Solvent:
3800 ftV"Hn at 77«F
Granular BPL V
8 hr/da, 2080 hr/yr
4-methy1-2-pentanone
Regeneration: Continuous, Internal air recycle
250 ftVmtn at 250°F for 100 ppm
600 ftVmln at 250*F for 500 ppm
Solvent re-
covery:
Condensation via refrigeration at 0*F
Concentration
Installed equipment cost
Operating costs. $/yr
Power at $0.015 kwh
Operatlnq labor at $10/hr
Carbon replacement (5-yr life)
Maintenance, 2% of Invest.
Depreciation, (10-yr life)
Total
100 ppm
$17,600
500 ppm
$18,700
$/hr per 1,000 ft
Solvent recovered, 90% efficient,
Ibs/yr
Value of solvent recovered
(3 $0.135/15, $
1,130
300
70
350
1 .760
3,610
0.46
10,900
1,470
1,620
300
70
375
1,870
4.235
0.54
54,500
7,350
-------
Table6-XIII
Estimated Operating Cost, Continuous Recycle Unit v/lth Concentration
of Pollutant for Subsequent Recovery or Disposal
Design basis
3800 ft'/mln at 77°F
4 to 10 mesh granular BPL V type
8 hr/da, 2080"hr/yr
Regeneration: Continuous, Internal air recycle, 250 ft3/nnn
at 250°F
Airflow:
Carbon:
Operation:
Pollutant
Concentration, ppm
Purge vent, ft'/mln
Purge concentration, ppm
Purge vent concentration, % LEL
Installed equipment cost, $
Operating cost, $/yr
Power at $0.015/kwh
Operating labor at $10/hr
Carbon replacement, (5-yr life)
Maintenance, 2% of Investment
Depreciation, (10-yr life)
Total
$/hr per 1000 ftj/m1n
4-methyl-
2-oentanone
10
12
3,250
25
16,500
960
300
70
330
1,650
3,310
0.42
Acetone
10
5.1
7,500
25
17,600
1,690
300
70
350
1,760
4,170
0.53
100
51
7,500
25
17,600
1,830
300
70
350
1,760
4,310
0.55
300
153
7,500
25
19,800
1,830
300
70
400
1,980
4,580
0.58
0>
I
00
to
-------
Table 6-XIV Activated Carbon Suitable for Air Pollution Control Applications
Trade name
Norit RB I
Norit RB II
Norit RB III
Norit RB IV
BC-BD
BC-61
Informal on on
PAC PCB
(coconut shell)
PAC BPL
Mesh
U.S. s
Pellet
M
M
gran.
other
gran.
gran.
size
ieve No.
Am A ri r
16x20
8x12
6x8
4x6
6x14
grades not
rttt. f r h
rittSu
4x10
6x16
12x30
4x10
Bulk
density,
g/cmj
an Norit Compan
0.42-0.45
M
Barnebey Cheney
0.39
available
0.45
0.5
Surface CC14
area, activity,
yT n r _....,,
, 1 1 1 1> . ---ii
900-1000
100
1150-1250 60
1050-1150 60-65
Selling
price,
CA 90-100
58-63
58-63
55-58
44-49
(coal base) " 6x16
12x30
-------
Table 6-XIV (continued)
Trade name
Columbia NXC
Columbia 3LXC
Columbia SXV1C
Columbia ACC
Columbia JXC
Nuchar WV-H
HV-H
Hltco 235
164
256
337
249
360
Mesh
U.S. s
pellet
H
pellet
pellet
gran.
pellet
gran.
gran.
size
1eve No,
Mn-t
4x6
6x8
4x6
6x8
8x10
4x6
6x8
6x14
4x6
6x8
8x10
6x16
12x30
12x20
6x12
4x10
6x16
80x400
12x20
Bulk
density,
q/cm3
on Carbide Corp
0.48
0.48
0.50
0.50
0.50
0.45
0.45
0.51
0.48
0.48
0.50
Uae t-ua rn
0.48
0.48
W1tco Chemical
0.56
0.46
0.45
0.45
0.32
0.38
Surface
area,
m2/q
1000
fn
930
1200
1250
1300
1400
1800
ecu
activity,
%
60
50
50
50
65
65
65
60
60
60
60
60
Selling
price,
C/lb
42-46
41-45
41-45
90-94
85-89
59-63
48-52
47-51
47-51
44-47
44-47
Ot
I
tO
-------
6-92
Very significant information regarding a carbon would
be its generalized adsorption isotherm or isotherms; the
type of isotherm referred to are shown in Figure 4-11 and
-12, Cost estimates made on different types of carbons show
that a carbon with a steep sloped isotherm is better suited
for solvent recovery or adsorption-regeneration when adsorp.
tion occurs at high concentrations. Carbons with a small
slope are better suited for poorly adsorbed pollutants or
adsorption at very low concentrations, i.e., adsorption at
large A values. In Figure 4-11, the BPL VI carbon would be
more effective for adsorption at a very low concentration
than the S154. On carbon weight basis S154 would be more
effective than BPL V for solvent recovery. However, because
of the low density of S154 much of the advantage of S154
cancels out when comparisons are based on equivalent volumes*
The addresses of the carbon manufacturers are as
follows:
American Norlt Company, Inc.
Jacksonville, Florida
Barnebey-Cheney
Cassidy at 8th
Columbus, Ohio 43219
Pittsburgh Activated Carbon
Division of Calgon Corporation
Calgon Center, Box 1346
Pittsburgh, Pa. 15230
Union Carbide Corporation
Carbon Products Division
270 Park Avenue
New York, N.Y. 10017
Westvaco
West Virginia Pulp and Paper
Chemical Division
299 Park Avenue
New York, New York 10017
Witco Chemical Company, Inc.
Activated Carbon Department
277 Park Avenue
New York, New York 10017
Two specialty items that are of Interest to air pollution
control are, (1) a bonded granular carbon panel manufactured
by Pittsburgh Activated Carbon and (2) a partlculate web
-------
6-93
manufactured by C.H, Dexter Corporation, One Elm Street,
Windsor Locks, Connecticut 06096. The Pittsburgh procedure
for bondinq carbon qranules qives a porous riqid structure
that can be shaped into other forms aside from the panels.
The bondinq procedure does not siqnificantly lower the carbon
adsorptive capacity. The C.H. Dexter web consists of a thin
flexible sheet of orqanic fibers to which are bonded powdered
activated carbon. Fifty percent of the web weight is carbon.
Chemetron Corporation, Catalysts Division, P.O. Box 337,
Louisville, Kentucky 40201, prepare specially treated carbons
formulated for removal of sulfur compounds from synthesis and
natural gas streams. The impregnated carbon is identified as
G-32E catalyst.
Noncarbon Adsorbents
The following list presents the names of manufacturers
of silica gel, activated alumina, molecular sieves and im-
pregnated polar adsorbents. See Chapter 4, Types of Adsorbents
for discussion of adsorptive properties.
Aluminum Company of America
1501 Alcoa Building
Pittsburgh, Pa. 15319
Product: Granular activated alumina, grades F-l,
F-5, F-6 and H-181.
Davison Chemical
Division of W.R, Grace & Co.
101 North Charles St.
Baltimore, Md. 21203
Product: Granular silica gel and molecular sieves,
types 3A, 4A, 5A, 2-100 and 13X,
Linde Company
Division of Union Carbide Corp.
Pleasant Valley Road & Rt. 38
Moorestown, New Jersey
Product: Molecular sieves, types 3A, 4A, 5A, 10X
and 13X.
Marbon Division
Borg-Warner Corp.
Washington, West Virginia 26181
Product: Potassium permanganate Impregnated
alumina, Purafll trade name.
-------
6-94
Sorption Systems
The following list presents the names of firms engaged
in engineering and/or fabrications of various types of sorp.
tion systems used for air purification, solvent recovery, or
specifically for control of air pollution.
Barnebey-Cheney
Cassldy at 8th
Columbus, Ohio 43219
System: Air purification and solvent recovery.
Cambridge Filter Corporation
7645 Seventh North Road
Syracuse, New York 13201
System: Air purification, pollution control -
carbon pleated and flat panel types.
Conner Engineering Corporation
Division of Jenn-A1r
Danbury, Connecticut
System: Air purification pleated, panel, and
canister type carbon beds.
Day & Zimmermann, Inc.
Philadelphia, Pa.
System: Carbon resorb with air or Inert gas
regeneration and Incineration of
desorbed vapor or readsorption in
secondary adsorber.
Detrex Chemical Industries, Inc.
Box 501
Detroit, Michigan 48232
System: Solvent recovery - carbon stationary-
beds with steam regeneration, hood
ducts, freeboard chillers for degreasers,
Farr Company
2301 Rosecrans Ave.
El Segundo, California 90245
System: A1r purification, pollution control.
-------
6-95
Howard S. Caldwell Company
Caldwell Air-Park
P.O. Box 27
Baltimore, Ohio 43105
System: Air purification, canister and pleated
panel types carbon beds.
Hoyt Manufacturing Corporation
251 Forge Road
Westport, Mass. 02790
System: Solvent recovery, stationary carbon bed
with steam regeneration.
Marbon Division
Borg-Warner Corp.
Washington, West Virginia 26181
System: A1r purification, potassium permanganate
Impregnated alumina panel type beds.
T. Melshelmer Co., Inc.
22610 South Western Ave.
Torrance, California 90501
System: Pollution control, multistage beds
displaced at Interval countercurrent to
airflow, bed reactivated,
Mine Safety Appliances Co,
201 North Braddock Ave.
Pittsburgh, Pa. 15208
System: A1r purification, pollution control-
carbon pleated and flat panel types
carbon beds.
RSE Incorporated
34875-23 Mile Rd.
New Baltimore, Michigan 48047
System: A1r purification - carbon panel filters,
Steffey Metal Products, Inc.
Division of MacOonald Mfg. Co.
23-Mile at Sass Road
New Baltimore, Michigan 48047
System: A1r purification carbon panel filters.
-------
6-96
Sutcllffe, Speakman and Co., Ltd,
P. 0, Box 366
Bronxville. New York 10708
System: Solvent recovery, rotary bed
continuous adsorber and dual
stationary bed.
V1c Manufacturing Company
1620 Central Avenue. N.E,
Minneapolis, Minnesota 55413
System: Solvent recovery, dry cleaners with
integrated solvent recovery, stationary
bed with steam regeneration,
Vulcan Cincinnati, Inc.
1329 Arlington Street
Cincinnati, Ohio 45225
System: Solvent recovery, stationary carbon
beds with steam regeneration.
-------
7. Catalytic Incineration System
Basic Functions and limitations
Oxidation and Reduction Functions
Catalysts can perform two basic functions useful 1n air-
pollution control. The function already being used to con-
siderable extent 1s the catalysis of oxidation reactions, as
of carbon monoxide to carbon dioxide and hydrocarbons to
carbon dioxide and water. The other function, which may
have limited application to small sources control, 1s the
reduction of nitric oxides to free nitrogen and oxygen.
Since the Interest in air pollution control 1s the com-
plete combustion of hydrocarbons, catalytic oxidation systems
are regarded as incinerators, to emphasize a comparison to
the competing thermal Incinerators. A flow diagram of the
basic catalytic incinerator is shown In Figure 7-1., The
pollutant collection and blower system may be an existing
ventilating system, to which the incinerator 1s attached,
or Installed to accommodate the incinerator. Preheat is
required to raise the pollutant-air stream to the combustion-
Initiation temperature, which can vary from ambient tempera-
ture for oxidation of hydrogen to, 750eC for oxidation of
methane on a platinum alloy catalyst. Most pollutants of
concern have oxidation-initiation temperatures in the range
400° to 600°F.
Cleaned
air
Ducts
Blower
'reheater
Catalyst
bed
Pollutant
air
Figure 7-1 Basic Catalytic Incinerator Components
-------
7-2
The types of catalysts best suited for catalytic com-
bustion and reduction of pollutants are discussed 1n Chap-
ter 5.
With correctly sized catalytic incinerators 90% to
98% of the pollutants are burned to the ultimate combustion
products.
To Improve the operating economics, more complex In-
cinerators incorporate.heat exchangers whereby the heat
content of the effluent stream 1s used for preheating. When
the combustible pollutant concentration of the Influent
stream 1s high, sufficient heat 1s generated for the Incin-
eration to become self sustaining. At low concentrations
additional fuel 1s required. '
Advantages
The advantages (and disadvantages) of catalytic Incin-
eration are usually compared with thermal Incineration. In
this manual of package sorptlon devices Us merits are also
related to sorptlon devices and to a lesser extent to ab-
sorption devices or scrubbers. When the pollutant 1s a'sol-
vent with recovery value, the (nondestructive) $orpt1on-tyoe
solvent recovery systems have a large economic advantage;
see Chapter 6 - Comparative Costs for details. When the
pollutant has no recovery value but is combustible to car-
bon dioxide and water vapor, the catalytic and thermal In-
cinerators perform the same function. When incineration
is advantageous over control by sorptlon devices, the ad-
vantages of catalytic Incineration are related to thermal
Incineration.
The important advantage of catalytic incineration 1s
the decreased reaction temperature, For efficient thermal
Incineration, furnace temperatures of 1200° to 1500°F are
required while catalysts operate effectively in the 600°
to 900°F range. From this single source, the economic assets
are distributed through equipment, fuel and maintenance/
Less refractory containers and supports are required which
in turn, reduce construction material and fabrication costs
The largest economic factor 1s the savings 1n fuel. Cost '
analyses of He1n (1964) favor catalytic oxidation 2 to 6
times over the thermal equivalent. The analyses as sum-
marized in Figure 6-31 Indicate that catalytic systems are
favored by a factor of approximately 1.5.
An Important advantage to catalytic Incineration, and
also of thermal Incineration relative to sorptlon methods,
is that they can control fumes from baking, roasting and
varnish cooking operations which yield, 1n addition to sol-
vents, high molecular weight polymeric decomposition products
-------
7-3
(considerably above 190 cm3/mol Vm). These high molecular-
weight pollutants cannot be desorbed from the carbon on re-
generation, thereby shortening the useful service life of
the carbon.
Many processes emit the pollutant exhaust at elevated
temperatures, as for example, coffee roasting. This factor
is advantageous for catalytic and thermal incinerations
when combustible pollutant concentration is low since it
reduces or may eliminate the fuel requirements and reduces
equipment costs, since heat exchangers are not required.
Disadvantages
The disadvantage of catalytic incineration relative to
the thermal equivalent is the deactivation of the catalysts
due to "poisoning". Deactivation or "poisoning" may occur
through preferential adsorption of an undesirable or unre-
active compound, physical erosion of the active surface
sites, chemical reaction, or destruction of active surface
sites by excessively high operating temperatures.
Most of the heavy metals, halogens, sulfur, phosphates
and silicates will poison metal catalysts. The poisoning
mechanisms vary among these examples, but each reduces the
catalytic activity and results in higher operating costs.
Trace concentrations of any of these poisons will reduce
the catalyst life significantly. Operating life may be
limited to months instead of years, which might be realized
with a nonpoisoning atmosphere.
Particulates present in the pollutant airstream must
be removed by filtration for both the catalytic incinerators
and sorption systems to prevent possible poisoning of the
catalysts or clogging the catalyst or adsorbent bed. In
this respect some advantage can be credited to the thermal
incinerator, since it can continue operations and, in some
cases, realize complete combustion of the particulates.
A short-coming of both the catalytic and thermal in-
cinerations is the effects produced by incomplete combus-
tion. Oxidations occur through a series of steps producing
various intermediate oxidation products which may be more
undesirable than the original pollutant. An example of the
possible range of Intermediate products can be illustrated
with the oxidation of butane, as follows:
Butane + 0? » Butanol, slight odor
Butanol + 02 -» Butanal, malodor
Butanal + Qg* Butyric acid, nauseating
Butyric acid + Og * 4C02 + 4H20, odorless.
-------
7-4
Temperature control must be maintained and the Incinerator
sized to minimize or avoid the production of Intermediates.
Pollutant airstreams containing considerable amounts
of n1trogenated, sulfurated, and/or halogenated hydrocarbons
can produce unacceptable large amounts of NOX. SOx and hy-
drogen halides on Incineration. Unless provisions are made
to control the effluent acids, the alternative would be
the sorption methods. In a relatively dry effluent free
of SOX and hydrogen hallde the NOX can be catalytlcally
decomposed.
Some precautions must also be taken In the selection
of oxidation parameters to prevent explosion or flashback
in gas streams having high pollutant concentrations, Com-
plete combustion 1s more probable 1n these systems, and It
1s also possible to extract some heat from the excess heat
of combustion. However, when temperatures are high and gas
velocities low, conditions may be established for auto-
Ignition, flashback or explosion. As recommended for the
adsorption systems, the upper concentration limit 1s 25X of
LEL for general operations. In some specific cases where
the concentration 1s stable (I.e., does not fluctuate) or
where protective monitoring Instruments and controls are
used, the allowable concentration can be Increased to 40X
of LEL.
Large variations 1n pollutant concentration produce
operational problems which, however, can be corrected, at
a cost, with Instrumentation and other auxiliary equipment.
Increases 1n concentration above the concentration for
which the catalytic Incinerator was designed may cause the
catalyst temperature to rise to the point where the catalyst
becomes deactivated. Conversely, a decrease 1n concentra-
tion can lower the combustion efficiency below the design
level unless additional fuel 1s added.
Potential Applications
A number of applications of catalytic Incineration 1n
air pollution control are noted 1n Chapter 1, - the emission
sources being the spray booths, surface coating baking ovens,
drying ovens used in metal coating and lithographic opera-
tions, coffee roasting, meat smokehouses and meat rendering.
Incineration systems based on noble metal coatings, which
will correct air pollution from a number of Industrial pro-
cesses, are being advertized (Universal 011 Products), The
list contains forty-one specific processes, most of them
fitting Into the general Industries listed above or In the
list of Other Emission Sources 1n Chapter 1.
-------
7-5
Trace contaminant removal is also a significant factor
1n the preparation of controlled environments. Air and
space vehicle compartments, medical and biological test
stations and many welding and cleanina operations require
use of gases cleaned of trace impurities. Catalysis is
used in many of these applications to provide fast, effi-
cient purification,
The choice of control system depends on the balance of
advantages and disadvantages of the systems for the pollu-
tant emission under consideration,
System Design Parameters
As in the application of adsorption systems for pollu-
tion control (Chapter 6), the engineer will be required to
adapt the catalytic Incinerators in most cases to processes
already in operation. These processes have been developed
and also optimized for better production efficiency without
much consideration given to air pollution. As air pollution
control regulations have been coming into effect one approach
has been to increase the exhaust volume to decrease pollutant
concentration and another has been to make minor changes in
solvent mixtures by leaving out components that are specially
objectionable, The result 1s that the conditions are not
optimum for pollution control. When a new installation is
being considered, the opportunity exists for the machinery
manufacturer and process engineer to optimize the overall
operations to include pollution control and thereby attain
its most economical usage,
The first source of data for design and operating spec-
ifications is the properties of the pollutant exhaust gas
from the process, The Important properties to be considered
are;
Flow rate
Type of pollutant
Pollutant concentration
Temperature
Presence, type and concentration of poisons
Presence, type and concentration of partiqulates.
An important decision 1s the efficiency that should be
sought in the incineration process. Complete combustion of
the pollutant is not practical; however, 99% efficiency is
attainable under favorable conditions, Efficiencies durino
continued operation gradually decrease, hence hiqh efficien-
cies are usually attainable only with a fresh catalyst
-------
7-6
Important factors concerning the catalyst and the In-
cinerator operation to meet the desired or required goals of
efficiency are as follows:
Chemical make-up of catalyst
Catalyst surface area
Catalyst support
Operating temperature
Reaction kinetics
Resistance of catalyst bed to gas flow
Residence time of gas in catalyst bed.
In this area the mathematical expressions, 3, 4, 5, 6 and
10 presented in Chapter 5 are used for the Incinerator de-
sign purposes. Specific installations may provide additional
data or operating experience useful to finalizing the design.
The effects of the operating variables on the incinera-
tor operation are discussed further in the following text,
Type of Catalyst
Catalyst properties and classifications are reviewed
in Chapter 5. In general, the noble metals are the most
efficient for hydrocarbon combustion. The oxides of tran-
sition metals follow in the order Co>Cr>Mn>Cu>N1>V>Fe>T1>
Zn.
Transition metal oxide catalysts are more easily poi-
soned than the noble metals, but their lower cost and greater
selectivity could be advantageous.
Catalysts of tested performance and reliability are
available from various manufacturers, but their compositions
and preparations are either patented or proprietary Infor-
mation. Air pollution control systems usually require the
treatment of heterogenous mixtures (gas mixtures, catalyst
poisons and particulates) which make catalyst selection
difficult. The selection can best be made by the catalyst
manufacturer after all the other operating parameters have
been determined for the particular application.
Type of Pollutant
The chemical nature of the gaseous pollutant determines
not only the catalyst selection but also the ease with which
it can be oxidized. According to Stein (1960), the ease of
oxidation followsthe patterns given below:
Branched hydrocarbons are more difficult to oxidize
than normal hydrocarbons.
-------
7-7
Ease of oxidation increases with molecular weight
in a homologous series.
Unsaturated aliphatic hydrocarbons are more easily
oxidized than the corresponding paraffins, and
susceptibility to oxidation increases with in-
creasing unsaturation.
Open-chain compounds are more easily oxidized than
cyclic ones having the same number of carbon atoms.
Aromatic compounds, regardless of substitution, appear
to be easily oxidized over most catalysts,
Oxygenated aliphatics and aromatics are equal to
or more readily oxidized than the parent compounds.
Organic nitrogen compounds, such as pyridine, mor-
phaline and monoethanolamine, produce essentially
theoretical carbon dioxide and water with small
amounts of nitrous oxide.
The minimum oxidation-Initiation temperature or, more
important, the temperature at which 90% conversion occurs
measures the ease of oxidation of a vapor in air. Table 7-1
records these temperatures and also autoignition temperatures
for some of the known air pollutants emitted by small station-
ary sources. These temperatures are approximate and apply to
a noble metal catalyst at flows maintained to give comparable
residence times.
For a pollutant airstream at concentrations high enough
for the catalytic oxidation to be self sustaining, a portion
of the catalyst bed must be heated to the oxidation initia-
tion temperature, as by preheating the airstream. The com-
bustion of the pollutant then supplies the heat to raise the
combustion process to more efficient temperature levels and
preheat may no longer be required. At low concentrations
essentially all the heat must be supplied by added fuel to
maintain the catalyst at temperatures where catalytic effi-
ciency is maintained at 90% or better. Ninety percent and
higher efficiencies would be maintained at 800°F for most
air pollutants of concern. Some of the acetates and ketones
would require temperatures at the 900°F level,
In the incineration of flammable vapors operational
safety is an Important consideration. When the autoignitlon
temperature is lower than catalytic operating temperature
as for some of the normal hydrocarbons and ethyl acetate
(in Table 7-1) a flash-back or explosion would occur if th<»
concentration were allowed to rise to the lower explosive
-------
7-8
Table 7-1 Minimum Temperature for Initiating Catalytic
Oxidation and Autolgnltlpn of Organic Pollutant
Vapors In Air, Degrees Fahrenheit ""
Catalytic 90%
oxidation Auto- catalytic
Pollutant vapor TTTT7T ignition conversion
Methane 760 800 999 933
Ethane 680 959
Propane 650 660 870 1065
Butane 570 570 806 750
Pentane 590 495
Hexane 630 433 725
Heptane 490 433 520
Octane 490 428
Decane 500 406
Dodecane 540 399
Hydrogen 32 1076 250
Carbon monoxide 300 1204 500
Ethyne 280 365
Benzene 440 500 1076 575
Toluene 460 896 575
2-Butanone 550 960 660
4-Methyl-2-pentanone 560 860
Ethanol 540 793 575
Ethyl acetate 730 800 880(80t^
o-Xylene 470 570 924 575
iii
1) Suter (1955)
2) Romeo (1962)
limit (LEL). Table C-II 1n Appendix C records the auto*
ignition temperatures, lower explosive limits and also the
heats of combustion and molecular weights of some of the
identified small source pollutants. Dangerous concentra-
tion levels for propane, hexane, heptane and ethyl acetate
are 21,000, 11,000, 12,000 and 22,000 ppm respectively.
-------
7-9
The presence of COg and HgO in the pollutant stream
have an inhibiting effect on hydrocarbon oxidation, while
CO promotes their oxidation as was demonstrated by Klimisch
(1968) with propene and hexane on alumina supported copper
oxide catalysts.
Chemical composition of pollutants also affects the
nature of combustion products. This is important in cata-
lytic systems where partial oxidation is always a possibility
The desired products would have no toxic or odiferous nature.
Pollutant Concentration
The effects produced by the pollutant concentration
are closely involved with the heat content of the air and
heat of combustion of the pollutant. These three factors
determine the amount of added fuel and/or recycled heat re-
quired to maintain the optimum operating temperature level.
The main heating load is the heat content of the air, after
steady state has been attained. Lesser heat losses occur
through the incinerator shell. To raise the air temperature
from 60°F base temperature to 600° to 900°F (the effective
catalyst operating temperature range) requires 10.5 to 16.5
Btu/(std) ft1. (For thermal incineration operated in the
1200° to 1500PF range, the required heat input is 22.5 to
28.5 Btu/(std) ft3, or approximately twice as much.)
Table 7-II presents estimated concentrations at which
some of the more frequently encountered air pollutants would
be self sustaining at the 90% efficiency level. These esti-
mated concentrations do not cover heat losses through the
incinerator shell and also apply to incinerators without
heat recycle. In each case the concentration 1s near the
25% LEL, hence self sustaining catalytic combustions are
feasible at safe concentration levels.
When the pollutant concentrations are low, additional
heat input is required to maintain high conversion efficien-
cies. . Table 7-III presents the calculated amounts of
heat input from pollutant combustion at varied concentra-
tions, assuming 100% conversion to C02 and MpO. The dif-
ference between the total heating load, in the 10.5 to
16.5 Btu/ft3 of air range, and the Btu/ft3 given 1n Table
7-HI at each concentration is the amount of additional
heat required.
At concentration levels up to 100 ppm, 95% or more
of the required heat input comes from the preheat source.
Fluctuations in concentrations, which normally occur 1n
many industrial processes, would have very little effect
on the steady operation of the incinerator. Fluctuations
-------
Table 7-II
Pollutant Concentration
Combustion at 90%
Hea
tonverslon
t of
combustion,
Pollutant vapor Btu/ft3
Hexane
Toluene
4-fie thy 1 -2-pentanone
Ethyl acetate
Propane
Propanone
Ethanol
Natural gas(methane)
Table 7-III Heat Input from
Cone. ,
Pollutant vapor
Hexane
Toluene
4-Me thy 1 -2-pentanone
Ethyl acetate
Propane
Propanone
Ethanol
Natural gas (methane)
5
4
4
2
2
2
1
1
,000
,500
,200
,700
,600
,000
,600
,000
Pollutant
ppm
--. ..
Level
90%
conversion
temp. °F
Concentration,
pom
700
600
850
900 (80%)
1100
800 (es
600
900
Combustion
0
0
0
0
0
0
0
0
Heat 1
1
.0050
.0045
.0042
.0027
.0026
.0021
.0017
.0010
t)
at
np
1
0.
0.
0.
0.
0.
0.
0.
0.
1
3,000
2,500
4,000
7,500
8
8
7
9
Vari
ut,
0
050
045
042
027
026
021
017
010
,500
,000
,000
,000
1
ed Concentrati
Btu/ft3
100
0.50
0.45
0.42
0.27
0,26
0,21
0.17
0^10
(stp
10
5
4
4
2
2
2
1
1
j
00
.0
.5
.2
.7
.6
.1
,7
.0
25% of
LEL,
ppm
2,700
3,000
3,500
5,500
5,200
7,500
8,200
2,500
ons
3000
15
13
13.5
8.0
8.0
6.3
5.1
3.0
-------
7-11
in pollutant concentrations at levels higher than 1000 ppm
can cause catalyst overheating or underheating unless com-
pensating adjustments are made to the preheat input rate
At the low concentration, the catalytic incinerator opera-
tion is the most stable but the more costly in fuel consump-
tion,
Operating Temperature
The operating temperature - i.e., catalyst bed tempera-
ture - influences both the efficiency and life of the cata-
lyst, If this temperature is below the initiation tempera-
ture, no oxidation occurs; but above the initiation temp-
erature, the oxidation efficiency increases as the operatinq
temperature increases.
The two major catalyst types - noble metal and metal
oxide catalysts - exhibit wide differences in this operating
parameter, Transition metal oxide catalysts usually operate
in the temperature range 200° to 600° Farenheit, while noble
metal catalysts operate in the temperature range 400° to
1200°F,
The optimum operating temperatures reflect these dif-
ferences (300° to 400°F for metal oxides and 750° to 1050°F
for noble metals). Deterioration and deactivation of the
catalysts also follow this pattern. Operating transition
metal catalysts above 600°F limits their effective catalytic
life to the point where replacement costs may become a
limiting factor. Similarly, noble metal catalyst lives are
limited when operating above 1200°F.
Figure 7-2 illustrates the general pattern of tempera-
ture effect on conversion efficiency. An important charac-
teristic of the temperature effect is that the efficiency
approaches the 1002: level gradually; a large temperature
![1sf! of$?n 1nd1cated to increase the efficiency from 90%
Jf Miller (lien6 presented 1n F19ure 7-2 is based on data
The operating temperature also has an influence on the
products formed. Partial oxidation occurs to a greater
degree at low temperatures, producing undesirable combustion
ElSiJfJl'n*S!Jh Jr??UJjS would comPletely nullify the desired
benefits of the pollution control device since, in most cases.
these products are more photochemically reactive and more
odiferous than the original pollutants.
In the operation of the catalytic incinerator, the
*»o nf rno nnlin4>»_«. -. j _ j . . »«» w i wuc
-------
7-12
100
80
u
c
0)
60-
-------
7-13
100
I I » I « I I I I
Residence time (arbitrary units)
Figure 7-3 Effect of Residence Time on Catalytic
Combustion Conversion Efficiency
temperature and residence time become the two Important
variables to be optimized for minimum operating cost of the
Incineration.
As discussed under Operating Temperature* the conversion
efficiency increases at a diminishing rate with temperature
rise above the 90% level. In a similar manner,the conver-
sion efficiency also increases at a diminishing rate with
residence time. At lower operating temperatures -those
safest from temperature deactivation - the conversion effi-
ciency can be maintained by increasing residence time (i.e..
Increased bed size for a fixed flow rate). Figure 7-3 shows
this effect in arbitrary residence time units. The limit-
ing factor 1s the cost of the catalyst. As temperature 1s
increased the residence time can be decreased. In this
case, the limiting factor is the deactivation of the catalysts
at the higher temperatures.
-------
7-14
The curve 1n Figure 7-3 follows the equation;
% conversion « 100 - fn (7-1)
where f 1s the percentage of Influent concentration pene-
trating a catalyst layer and n 1s the number of layers.
The residence time 1s proportional to the number of layers
When the catalyzed reaction 1s first order with respect
to the pollutant species, Equation 5-5 reduces to,
C/C0 « e'Kt (7-a)
where C/C0 1s equivalent to f 1n Equation 7-1, Then the
efficiency of a catalytic Incineration can be represented
by the equation:
fraction converted 1 - [e'Kt]n, (7.3)
The reaction rate constant, K, and residence time, t,
for layers or Individual cells of catalysts, are generally
known by the manufacturer. Equation 7-3 shows that the
conversion efficiency Increases exponentially with K and t,
Similar theoretical correlations can be made using Equations
5-6 and 5-10.
When Equation 5-10 1s used, a catalyst bed length-to-
diameter ratio 1s also shown to Influence the efficiency.
As seen 1n Equations 7-2 and -3 above the conversion
efficiency Increases with the residence time per Individual
cell and the number of cells. Efficiency Increase, by en-
largement of the bed, can be done by adding the cells 1n
series to Increase bed length or 1n parrallel to Increase
bed diameter, or a combination of the two. When length
alone Is Increased, the flow velocity remains constant,
while an Increase in diameter produces a decrease 1n flow
velocity. K decreases slightly with decreased flow
velocity, but because 1t 1s 1n the exponent, this small
change 1s magnified 1n Its effect on efficiency. Equation
7-3 then strictly applies when the bed 1s enlarged by
adding cells 1n series. The limiting factor 1n this case
1s the resistance to airflow. In practice the pressure
drop 1s usually held below 12 1n, of HgO. If the bed volume
Is enlarged by Increasing the diameter to avoid excessive
pressure drop, the limiting factor 1s the reduction 1n K,
-------
7-15
Operating Costs
The economic analysis of the catalytic incinerator
operations Include the following costs:
Fixed capital
Depredation
Operating labor
Maintenance
Electrical power
Fuel,
To establish the operating costs on a basis that can be
compared to those of the thermal incinerators and carbon
resorb systems, they are worked up as $/hr per 1,000 ft3/m1n
of polluted air that are cleaned,
Equipment
Installed costs vary between $3,500 and $6,000 per
1,000 ftVmin (stp) air handling capacity, The higher end
of the range includes costs for heat exchangers, and filters
for participate removal, and also reflects the costs of more
expensive catalysts. As the size is increased, the cost per
unit air handling capacity decreases to some extent but, for
the range 2,000 to 10,000 ftVmin flow capacities, the cost
per 1,000 ftVmin was assumed to be essentially constant for
the comparative operating cost estimates reported in Chapter
6. The higher $6,000 figure was used at pollutant concen-
trations below the self sustaining concentrations (below
about 3,000 ppm), since heat exchangers give a decided oper-
ating cost reduction,
Depreciation
A 10-year depreciation rate is often used by analysts
making cost comparisons with thermal incineration. Some
variation 1n deterioration rate will occur depending on
whether the Incinerator 1s 1n Intermittent or continuous
service, i.e., 8 or 24 hr/da.
Operating Labor
M^HMHM*^W^^V>^^^^^^^^^^^^^^ . fc
Operating labor costs for catalytic Incinerators are
relatively small after the incinerator has been put into
operation; this Is also true of thermal incinerators and
carbon resorb systems, A low level of operating cost has
been estimated on the basis of 5 min of labor per 8-hr
shift for each 1,000 ft3/m1n capacity (Hein 1964).
-------
7-16
Maintenance
Yearly maintenance costs have been estimated by some
analysts on the basis of 10% of the Initial Incinerator cost
(He1n 1964), Other methods can consist of periodic catalyst*
replacement cost combined with a lower percentage rate of
the Initial Incinerator cost,
Electrical Power
The main electrical power consumer 1s the air circulating
fan or blower. The kilowatts to move 1,000 fts/m1n of air
through an Incinerator or carbon resorb bed can vary from
2.5 to 4 1n the control systems of 2.000 to 10,000 ft'/mln
airflow capacities. Local electrical costs per kilowatt
hour will determine the power cost.
Fuel
Fuel costs, using natural gas for preheat purposes, are
approximately $0.60 per 10* Btu. At pollutant concentrations
below the self sustaining level, preheat 1s required at varied
amounts depending on the type of pollutant and pollutant con-
centration, The amount of preheat required can be estimated
from the calculated data given In Tables 7.II and 7*111 for
several frequently encountered pollutants. The self sus-
taining concentrations of Table 7-II were calculated for a
60°F base temperature for the- pollutant airstream, At higher
pollutant airstream temperatures, 1f heat exchangers are
utilized, the preheat requirements can be considerably !«$$.
Auxiliary Equipment
Before the catalytic Incinerator proper can be put Into
operation, a number of auxiliary pieces of equipment are
required for Its efficient and safe operation. These are
listed 1n Table 7-IV.
Table 7-IV Auxiliary Equipment for Catalytic Incinerators
Ducts and supports Preheaters
Blowers Heat exchangers
Filters " Monitors
Scrubbers Controls
-------
7-17
In the previous text the blowers, filters, heaters and heat
exchangers, of necessity, have been brought Into the discus-
sion, but more can be said of their functions.
Ducts and Supports
Ducts to direct the pollutant from the emission source
to the Incinerator are an economic necessity. Incineration
of the total ventilation alrstream 1s invariably too costly
to be considered. By ducting, the quantity of air to be
treated is kept smaller and also the concentration of pol-
lutants 1s maintained higher, thereby reducing the required
fuel costs.
In existing operations, the retrofitting of the ducts,
the catalytic unit and Its supports can be a problem. In-
dustrial processes are often designed to conserve space, with
little room remaining for later Installation of pollution
control systems,
Filters and Scrubbers
Filters are usually necessary to protect the catalyst
bed from partlculates in the alrstream because particulates
may: (1) poison the catalyst, (2) cause deactivation by
erosion or coating or (3) in the case of a granular catalyst
bed cause increase in flow resistance. Removal of particu-
lates from the alrstream 1s also done by scrubbing with
water. This procedure is feasible at ambient temperatures,
at the 77°F level, where the water vapor content will then
be established at about 4%. Efficient demisters would also
be required to keep the water content low, since water vapor
at higher concentrations interferes with the catalysis;
higher temperatures would be required.
Secondary filtration, after the catalyst, may also be
required for some catalysts such as packed or fluid beds.
Blowers
Air movement produced by convection or ventilating fans
cannot effectively overcome the resistance of the catalyst
bed and auxiliaries such as heat exchangers or preheaters.
Pressure drops at the 12 in. of HzO level are encountered
with some catalyst beds. Blowers are required for the ex-
clusive operation of the incinerator.
P'reheaters
Preheaters, auxiliary fuel and external heating may
all be used Intermittently. Unless the pollutant alrstream
-------
7-18
temperature is already at the initiation temperature, extra
heating is required to initiate the combustion. Subsequent
heat or auxiliary fuel requirements depend on the fuel value
of the pollutants.
Preheaters may be of the heat exchanger type where the
pollutant airstream does not come in direct contact with
the gas burner, or it can be a direct flame type, The latter
raises the water content of the pollutant airstream, which
with some catalysts may reduce their activity,
Heat Exchangers
The effluent gas stream from the Incinerator 1s usually
at temperatures ranging from 600° to 900°F, By use of a
heat exchanger a part of this heat energy becomes available
for preheating the influent air to the incinerator or for
other purposes such as steam generation, space heating or
process heating. When the pollutant control is a steady
operation, the heat recovery for secondary uses may make
the pollutant control a profitable operation. This would
be the case when the pollutant concentration is at the self
sustaining level or at lower concentration when the Influent
1s at elevated temperatures.
The cost of the exchanger can be 25% to 40% of the total
cost of the incinerator, but a heat exchanger operating at
50% recovery used for preheat reduces the fuel cost by about
50% at low pollutant concentrations. The estimated operat-
ing cost, given 1n Chapter 6, is $0.94/hr per 1,000 ft3/m1n
with a heat exchanger, while without an exchanger it 1s $1 30/
hr per 1.000 ft'/min,
Figures 7-4, 7-5 and 7-6 show diagrams of incinerators
in the various combinations of preheaters and heat exchangers.
Monitors and Controls
Some type of measurement is necessary to determine
the efficiency level at which the catalyst is working, A
number of alternative methods are available which may be
placed in seven general categories:
Component Identification - Although it 1s usually a
temporary arrangement, 1t 1s advisable to run complete anal*
yses of the exhaust stream to assure the removal of all pol-
lutant species. This will require the use of hydrocarbon,
CO, SOX and NOX analyses, which can be done by gas chromato-
graphy. Usually this 1s done at the beginning of operation
or during a pilot run to assure the unit 1s performing tp
design.
-------
7-19
_ -- . . Preheater
Pollutant
air »L
»- ^ _ Wt
\ o r
Vliy Fuel
(natural gas)
p-
^t _^<* ^X""^C
1
Cleaned
air
Pa 1*3 1 ue
ca to i ys
bed
Figure 7-4 Basic Catalytic Incinerator With Gas Burner to
Supply Preheat
Cleaned
air
Pollutant
:>c>c>c^
J
Preheat
exchanger
Catalyst
bed
Figure 7-5 Catalytic Incinerator With Heat Exchanger to
Supply Preheat
Pollutant
air
Preheater
Fuel
(natural gas)
1
J
Cleaned
air
Secondary heat
exchanger
Catalyst
bed
Figure 7-6 Catalytic Incinerator With Burner to Supply
Preheat and Secondary Exchanger to Recover
Heat for Process Use
-------
7-20
Total Hydrocarbon Analyzers - These monitors may be
used to supply continuous information concerning the con-
centration of hydrocarbons In either the process exhaust
or catalytically treated gas streams,
Dew Point Measurement - Either hydrocarbon pollutant
or water-product dew points may be used to follow the changes
1n concentration through the catalytic burner.
Temperature Measurement - Increased temperature with
passage through the catalyst bed 1s an adequate test for
determining 1f the catalyst Is working.
Addition of a Tracer Compound - By addition of a hydro-
carbon having a characteristic; odor, cursory measurements
are possible using olefactory sensitivities to the influent
and exhaust gas streams.
Pressure Measurement - Pressure drop through the cata-
lyst bed can be used to measure the attrition of the catalyst
CO and COg Measurement - Instrumental analyses are avail
able for the continuous measuring of CO and CO? concentra-
tions 1n flue gases.
Each of the analytical tools mentioned previously can
be used to determine the deterioration of a catalytic burner
and the time for maintenance. Here again, the degree of
change necessary to Indicate poor operation and efficiency
depends upon the physical measurement and the catalyst used.
Additional information on Instrumentation 1s given in Chan-
ter 8.
Equipment suppliers provide the control parameters and
the amount of change that can be tolerated while retaining
the 90% or higher efficiency as required,
Care of Incinerator
Some care must be exercised with catalytic Incinerators
especially during start-up, shut-down and storage, The cata-
lytic elements, or beds, must be kept clean and relatively dry"
in order to maintain their activity. The degree of sensi-
tlvlty and required care will depend on the type Of catalyst
Specific care and maintenance procedures should be provided
by the manufacturer. In general though, exposure to hydro-
carbon solvents and hot, moisture laden gases should be
avoided.
-------
7-21
Start-up
An initial heat-up period will usually precede the
actual operation of any catalytic burner. A flow of clean
air is passed through the system until it is equilibrated
at the desired operating temperature.
This heat-up period provides a time to clean the system
and check all analytical instruments used to control opera-
tion. It also assures the maximum efficiency of the catalyst
from the initial hydrocarbon exposure which eliminates prob-
lems of partial oxidation of pollutants and possible deacti-
vation by absorption or poisoning.
Maintenance
Little or no maintenance is required for normal opera-
tion of catalytic incinerators. When pollutant alrstreams
contain poisons or large variations in the pollutant con-
centration, both maintenance and operating problems increase.
Catalytic activity must be rejuvenated at regular intervals
by washing with water and/or heating while passing a non-
polluted airstream over the catalyst bed.
Storage
Shutdowns and storage also require the use of non-
polluted gas streams to cool the system and maintain a
relatively dry atmosphere during storage. The catalyst-bed
temperature is slowly reduced by decreasing the pollutant
concentration and recirculating hot effluent so the bed will
not experience a thermal shock.
Catalytic Equipment Manufacturers
Several manufacturers offer complete engineering tech-
nology for the analysis of the pollution problem and for
the design and fabrication of the catalytic incinerator to
correct the problem. Some manufacturers supply only cata-
lysts. In either case the equipment supplier requires an
analysis, as complete as possible, of the pollutant airstream
to make the correct selection of the catalyst and to design
and fabricate the incinerator. The following text describes
some of the products sold by these manufacturers.
Universal Oil Products of Darien, Connecticut, manu-
factures eight basic types of pollution control equipment
that can be modified to treat most process streams accord-
ing to the results of analyses. The catalysts used are
activated noble metals deposited on nickel alloy supports.
-------
7-22
Oxy-catalyst. Incorporated of West Chester, Pennsyl-
vanla, markets catalytic oxidation systems for Internal
combustion engines and Industrial processes. Their catalyst
1s a platinized alumina which resists thermal shock, poisons
and clogging. Five different sizes are available for use as
odor eliminators or catalytic Incinerators.
Matthey-Bishop. Incorporated of Malvern, Pennsylvania,
manufactures a new platinized ceramic honeycomb, designated
THT. It 1s claimed to offer the advantages of low pressure
drop, higher activity and attrition resistance 1n the com-
bustion of many organic vapors.
Mine Safety Appliances Corporation of Pittsburgh, Penn-
sylvania, markets several sizes of catalytic oxidation units
for the purification of aircraft cabins, liquid air separa-
tion plants and removal of hydraulic fluid vapors. The
catalyst used is MSA "Hopcalite", which is an activated mix-
ture of CuO and Mn02. Catalyst life 1s designed for greater
than 500 hours, but depends upon the type of service and
pollutants. Economical replacement is facilitated by de-
signing a replaceable catalytic unit and using this rela-
tively inexpensive catalyst.
The Harshaw Chemical Company of Cleveland, Ohio, manu-
factures catalysts of all types for catalytic incinerators.
Both metallic and oxide catalysts are made from V, Cu, Mo,
Pt, Pd, Co, N1, Mn, Sn, and Pb. They do not, however, de- '
sign or fabricate complete incinerator units.
Chemetrpn Corporation, Catalysts Activity Division, of
Louisville, Kentucky, manufactures tiircner catalysis. Their
G-43 catalyst combines Pt and N1 on an alumina support and
is used commercially for removing methane, ethane, ethylene,
carbon dioxide and nitrogen oxides.
Atlantic Research Corporation of Alexandria, Virginia,
1s a fabricator of catalytic incinerators but does not manu-
facture catalysts.
E. I. DuPontde Nemours & Co.. Industrial and Biochemi-
cal s Department of Linden, New Jersey and"'1-ngTehard Mineral's"
and Chemicals of Newark, New Jersey, manufacture catalysts"
and also design and fabricate incinerators.
FEC£, of Cleveland, Ohio 44105, custom designed cataly-
tic unTtT using catalysts supplied by duPont and Matthey-
Bishop
*
-------
8. Pollutant Detection
Introduction
This section on pollutant detection presents the prac-
tical aspects of monitoring the input and effluent from a
packaged sorbent device. The intent is to provide guidance
for the designer and users of these purification devices in
the selection of appropriate monitoring systems. It is
obviously impossible to deal with each specific pollutant
source due to the many different types of pollutants, pollu-
tant emissions rates and emission standards. Therefore, the
Information which is presented is of a generalized nature
although specific details are given on detection capabilities,
sensitivities, interferences, costs and so on. With this
Information, the designer or user can evaluate his specific
emission problem and select an optimum monitoring system
based on the information presented herein.
This section on detection covers three primary areas
relating to monitoring of emissions:
1. Methods of sampling gases
2, Techniques and instruments suitable for
monitoring emissions
3. Recommended methods for specific classes
of impurities
Basically, the method of sampling, the technique or
Instrument chosen and the reason for selecting a specific
approach to emission monitoring will depend upon many factors
including the type and quantity of emission, the size of the
emission control device, the rationale for using the device .
and cost of monitoring equipment. All of these factors are
Interrelated and will require technical judgment on the
selection of a pollutant monitoring system. In the case of
large corporations, in-house capabilities may exist and can
be called upon to make the necessary decisions. Conversely,
the small businessman may have to resort to an outside con-
sulting service in order to select an appropriate monitoring
system.
Pollution monitoring is required first to determine
whether an emission control device is necessary and secondly,
if an emission control device is needed, to determine when
the emission control device requires regeneration or replace-
ment* The need to install an emission control device 1s
-------
8-2
dependent upon two primary criteria:
1. As an economic measure to recover and
recycle solvents
2. As a required measure to meet federal,
state or local emission standards.
Therefore, an organization or business must identify what
emissions exist and the extent of these emissions.
In addition to actual analytical data, other information
can be used to determine emission rates. Source evaluations
for commercial processes rely on process flow sheets, mass
balance data and specific process engineering experience to
identify possible sources. This requires the examination
and assimilation of data from several disciplines and tech-
nical personnel with appropriate backgrounds for evaluation
and correlation. This type of approach to estimating emission
rates has been described by Jacobs (1949) and Stern (1968).
Small businesses can estimate emission rates in the same
fashion. For example, the operator of a dry cleaning estab-
lishment keeps an inventory of the quantity of cleaning sol-
vent which is purchased over a period of time. By equating
the volume of solvent used with the time of operation, an
emission rate can be estimated.
The character of a source may be significantly changed
by certain mixtures of pollutants or secondary reactions,
which are not readily apparent in the initial evaluation.
Therefore, regardless of the accuracy with which the basic
variables can be estimated, analytical characterization of
the effluent will be required.
Methods of Sampling Gases
Sampling is generally divided into two basic categories:
1. Grab sampling
2. Continuous sampling
Regardless of which method is used, the objective is to
acquire a sample which 1s representative of the emission 1n
terms of both types and quantity of pollutant 1n the exhaust
effluent.
-------
8-3
Grab samples are instantaneous samples which are gener-
ally returned to the laboratory for chemical or instrumental
analysis, while continuous sampling is usually associated
with on-site instrumental analyses. Grab samples can be
taken in evacuated glass* metal or plastic containers, with
the restriction that the pollutant neither reacts with nor
is absorbed by the container wall. Grab sampling is an
acceptable means of acquiring a sample when the type and
concentration of pollutant is relatively constant.
When the type of pollutant or pollutant concentration
varies with time then grab sampling is of questionable
value. In such cases, an integrated sample can be taken
where a sample of the effluent gas is drawn through a suit-
able sample collector over a period of time. This type of
sampling provides an average concentration of the pollutant
over the scheduled time period. Integrated sampling has an
inherent advantage in that trace contaminants are concen-
trated and thus the problem of measurement of pollutant
concentration may be minimized. The disadvantages include
the necessity of accessory equipment such as flowmeters,
pumps and so on.
The time variable in grab or integrated sampling tech-
niques is an important part of the entire analytical pro-
cedure. Most commercial manufacturing is done on a cyclic
schedule or Includes "batch processes" where the emissions
and rate' of release vary. The schedule of the process must
be known and all samples Identified concerning both time
and location for accurate Interpretation.
Continuous sampling is usually associated with direct-
reading, instrumental systems. A sample of the effluent
gas is drawn through the instrument with a pump, and a con-
tinuous readout is provided by the instrument. This type of
sampling system has the advantages of continuous data dis-
play and minimization of direct labor costs in procurring
a sample. Many instruments have a sampling system as an
inherent component or a sampling system can be purchased
as an accessory. For example, portable battery powered In-
struments to measure LEL have sampling pumps as part of the
instrument package. Most industrial chromatographs are
purchased with continuous sampling equipment.
The sampling procedure which is ultimately selected
will be influenced by a number of factors. Samples will be
taken to determine whether or not an emission control device
is required. In this case, sampling and subsequent analysis
-------
8-4
on a contract basis with an analytical services laboratory
1s frequently the best route to follow. If the evaluation
Is to be performed in-house, the type of sampHnq system
used should be simple and inexpensive. Grab samples will
generally suffice except in those cases where the rate and
quantity of pollutants vary to an extreme degree over short
periods of time.
If an emission control device is deemed necessary, then
a judgment must be made on the type and complexity of the
sampling system. This will depend upon many variables, as
stated earlier, and the selection of a specific sampling
system will have to be made on the basis of these factors.
Techniques and Instruments for Monitoring
Introduction
A discussion of the various pollutants amenable to
removal by either sorption or catalytic combustion was pre-
sented in Chapter 1. These pollutants cover a multitude of
chemical groupings exhibiting various physical and chemical
properties. In most cases, the pollutants which have been
categorized for potential removal by sorptive or catalytic
devices are hydrocarbons. The specific type of hydrocarbons
rangesfrom straight chain configurations to those with
various functional groups attached to the hydrocarbon chain.
Selection of an appropriate monitoring device or technique
will depend upon the specific characteristics of a given
pollutant. For example, straight chain hydrocarbons will
likely dictate that a hydrogen flame ionization or thermal-
conductivity detector be used, while chlorinated hydro-
carbons may be identified more selectively by the use of
an electron capture detector. Functional groups containing
phosphorous or sulfur can be measured at low levels using a
flame photometric method.
Instruments and analytical techniques are classified
according to the specific physical or chemical character-
istics which are measured. In general, these can be clas-
sified into the four major categories shown in Table 8-1;
subdivisions within these categories are shown also. This
listing is not meant to be all inclusive, but does represent
the most likely means of detecting and measuring pollutants
in gaseous effluents.
The analytical requirements of various pollution sources
have encouraged the development of a myriad of analytical
methods of varying degrees of relevancy for any particular
application. Compilations such as published by Jacobs (1949).
-------
8-5
Table 8-1 Classification of Analytical Methods
I. ThermometHc Instruments
A. Thermal conductivity
B. Catalytic combustion
II. Electrometrlc Instruments
A. Flame 1on1zat1on
B. Ion1zat1on
C. Electrical conductivity
III. Spectrometrlc Instruments
A. Visible spectrum
1. Interferometrlc
2, Spectographlc
B. Ultraviolet spectrum
1. Ultraviolet photometric
2. Ultraviolet Spectrometrlc
C. Infrared spectrum
1. Infrared spectrophotometrlc
2. Infrared
IV. Chemical Methods
A. Gravimetric
B. T1tr1metr1c
C. Detector tubes
-------
8.6
Stern (1968) and Ruch (1970) are a few of the exceptionally
good references available for selecting an analytical method
or instrument capable of measuring an air pollution sample
accurately. The selection of a method or combination of
methods required to obtain a desired accuracy should be made
on the basis of best estimations for several parameters.
These complex mixtures present individually unique problems
compounded by the large variations in concentrations and
possible interferences among the components.
In general, all pollution detection methods are judged
on the basis of seven parameters (I.e., specificity, range,
sensitivity, reliability, accuracy, maintenance and costs)!
Selection of a preferred method is made by optimizing the
performance for each parameter and selecting the best com-
promise which is available for the individual gas sample.
Methods of Analysis
Detailed reviews of analytical methods for specific
compounds have been published by Jacobs (1949, 1960, 1967)
U.S. Public Health Service (1965), Stern (1968) and Ruch
(1970). These authors provide excellent descriptions of the
accuracy, interferences and actual procedures to measure
specific compounds.
Table 8-II lists the general classes of pollutants
which are most likely to require control devices, along with
possible methods of measuring these pollutants, and the de-
tection range. Costs are not included in this table since
this factor varies among manufacturers and according to the
accessories acquired with the monitoring device. Direct
contact with a manufacturer will frequently provide valuable
information on the instrumentation which is available for a
specific application and the cost of a complete instrument
package.
Thermal Conductivity - Automatic recording instruments
are commercially available for the determination of gases
and vapors based on their thermal conductivity. The absolute
values of the thermal conductivity are seldom used for
analytical purposes, but several selected values have been
reported (Willard, 1958). The thermal conductivity of a
gas mixture to be analyzed is usually compared with that of
some reference gas, such as hydrogen, nitrogen, or wet or
dry air.
A fine wire, usually platinum or some other metal or
alloy with a high temperature coefficient or resistance, 1$
stretched along the axis of a metal or glass cylinder.
-------
Table 8-II Common Analytical Methods Used for A1r Pollutant Detection
Hydrocarbons
Oxygen-containing
organlcs
Halogenated
organlcs
Inorganic oxides
Odors
Aromatic
hydrocarbons
Polynuclear
hydrocarbons
Catalytic
combustion
1-1000 ppm
1-100% LEL
1-100 ppm
1-100* lL
Thermal
conductivity
100-10,000 ppm
100-10,000 ppm
100-10,000 ppm
100-10,000 ppm
100-10,000 ppm 1-1000 ppm
1-100X LEL
Ion1zat1on
Methods
0-1 ppm
1-10,000 ppm
1-10 ppm
10-1000 ppm
0-10 ppm
10-1000 ppm
1-100 ppm
0-1 ppm
1-10,000 ppm
Ultraviolet
spectrophotometry
0-10 ppm
10-200 ppm
0-10 pom
10-200 ppm
0-10 ppm
10-200 ppm
0-10 ppm
oo
-------
Table 8-II (Continued)
CD
I
co
Infrared
spectrophotometry
Colorlmetry
Electrical
conductivity
Halogen
leak-detector
Hydrocarbons
Oxygen containing
organic*
Halogenated
organlcs
Inorganic oxides
Odors
Aromatic
hydrocarbons
Polynuclear
hydrocarbons
0-1000 ppm
1-1000 ppm
1-1000 ppm
0-1000 ppm
0-100 ppm
0-100 ppm
100-500 ppm
0-100 ppm
100-1000 ppm
0-10 ppm
10-1000 ppm
0-10 ppm
10-1000 ppm
0-10 ppm
10-1000 ppm
-------
Table 8-II (Continued)
Emission Mass
spectrometer spectrometer Scantometer
Hydrocarbons 0.5-100%
Oxygen-conta1n1nq 0.5-100%
organlcs
Halogenated 0-500 ppm 0.5-100%
organlcs
Inorganic oxides 0.5-100%
Odors 1-° LTV
Aromatic 0.5-100%
hydrocarbons
Polynuclear
hydrocarbons
00
I
-------
8-10
Either two similar cylinders and two resistances or four
similar cylinders and resistances are used to form the arms
of a Wheatstone bridge circuit. The final equilibrium tem-
perature of the wire depends upon the thermal conductivity
of the gas surrounding it. Lower temperatures produce higher
conductivity, whereas higher temperatures produce lower
conductivity. If the gases in the cells are the same, the
wires will reach the same temperature and therefore will
have the same resistance; thus the bridge is balanced. If
the gases are different, the final temperatures and resis-
tances of the wires will be unbalanced. The extent of un-
balance of the bridge is measured by a galvanometer or a
potentiometer and can be calibrated in terms of the com-
position of the gas.
The thermal conductivity method is usually operated as
a continuous recording method, since the off balance condi-
tion can be measured by a recording potentiometer.
The method is easily applied to the determination of
the composition of binary mixtures, provided that the two
gases have different thermal conductances (Willard, 1958).
The greater the difference between the two gases, the greater
the sensitivity of the method. A multlcomponent mixture can
be treated as a binary mixture if all components but one
remain constant or if all the gases except one have nearly
the same thermal conductance (Eckman, 1950).
With multlcomponent mixtures, the thermal conductivity
detector is frequently used in conjunction with gas-liquid
chromatography. The components are separated by a packed
column with each component exhibiting a characteristic re-
tention time. Quantitative measurements are made by com-
paring peak heights or areas against standards.
Catalytic Combustion - The measurement of combustible
gases or vapors is based on the principle of catalytic com-
bustion (Mine Safety Catalog No. 8B3659-3, 1971). A mixture
of gases may be either flammable or not, according to the
concentration of the vapor in air 1n which a flash will occur
or a flame will travel if the mixture is Ignited. The lowest
percent at which this occurs 1s the lower explosive limit
(LEL) and the highest percent is the upper explosive limit
(DEL). The LEL is considered 100% and the concentration
below are considered as percent of the LEL.
If propane and air are confined and Ignited, an explo-
sion results. The LEL of propane 1n air 1s 2.2% and the UEL
1s 7.3%. Mixtures above 7.3% are too rich to support com-
-------
8-n
bustion, and those less than 2.255 are too lean. Since air
is the diluent and is readily obtainable, all concentrations
above 2.255 are dangerous; therefore the instrument would be
calibrated from 0 to the 2.2% LEL for propane.
The catalyst is usually a platinum wire filament (Mine
Safety, 1971 and Scott Aviation, 1969) maintained at a con-
stant temperature. When the combustible gases or vapors
come in contact with the catalytic filament, they are oxidized
or burned catalytically. Two identical filaments are used
in the bridge circuit. One filament, known as a reference
filament, is sealed in air 1n a separate well of the same
chamber as the active or exposed filament. Two fixed re-
sistors are used as the legs of the bridge connected together
by a variable resistor. The bridge is balanced with both
filaments in air by adjusting the variable resistor or zero
control. The increase in resistance is proportional to the
amount of flammable gases or vapors in the sample and 1s
measured by a meter, the scale of which 1s calibrated to give
direct readings in percent of the LEL,
Portable combustible gas Indicators may sample auto-
matically or manually for the detection of combustible toxic
gases or vapors. The ranges and sensitivities of the indi-
cators depend on the model and the gases or vapors for which
the instrument is calibrated. The instrument may operate on
one full scale, a dual scale, or as high as five scale ranges
which may read 0 to 1.0%, 0 to 10% or 0 to 100% of the lower
explosive limit. For the gases or vapors calibrated for
those indicators with two or more scales, ranges can be pro-
vided with multiple calibrations, whereby readings on any
gas or gases for which 1t has been calibrated can be made by
turning a selector switch. There are more sensitive models
that read 0 to 1.0% of the lower explosive level on one
scale and 0 to 1,000 ppm of vapor on a second scale (Johnson-
Williams Products, 1970), Other models, while not scaled
off in ppm designation, may be calibrated to measure in this
low level area. These models provide a check on the toxicity
of combustible vapor concentrations and furnish ppm measure-
ments for comparison with threshold value limits.
A partial listing of selected gases and vapors that
are reported to be measurable by catalytic combustion devices
in the ppm range are listed in Table 8-III (Johnson-Williams
Products, 1970).
Continuous combustible gas detectors (General Monitors,
1970; Mine Safety, 1970j Erdco Engineering, 1970) consist of
two components: the control and indicating unit and a remote
detection unit. The control unit is Individually powered
-------
8-12
Table 8-III Partial Listing of Gases and Vapors
Detectable 1n the ppm Range*
Acetone Hexane
Amyl acetate Methane
Benzene Methyl alcohol
Butadiene Methyl butyl ketone
Butyl acetate Methyl ethyl ketone
Butyl alcohol Methyl Isobutyl ketone
Cyclohexane Methyl propyl ketone
Cyclohexanol Octane
Cyclohexanone Pentane
Ethyl acetate Perchloroethylene
Ethyl alcohol Propane
Ethylene Isopropyl alcohol
Ethyl ether Propyl alcohol
Formaldehyde Stoddard solvent
Heptane Toluene
1 ,1 ,l-Tr1chloroethane
Trlchloroethylene
Turpentine
Xylene
*Most aromatic hydrocarbons are reported to be measurable
1n the ppm range by sensitive combustible gas Indicators.
-------
8-13
and contains the Indication and warning devices. The remote
detection unit designed for area monitoring, houses the cata-
lytic sensing device. Each control unit may be coupled with
a single or a dual detection unit for monitoring locations
as far as 3000 to 5000 ft away. Several control units may
be housed in modules to facilitate centralized monitoring
from multiple locations.
Combustible gas or vapor is detected at the sensory
probe by means of a low temperature catalytic reaction on
a heat sensitive surface. Matched elements are heated and
exposed to the gas or vapor. One element in the pair 1s
catalytically active; the other 1s Inactive and acts as
reference.
In the presence of a combustible gas, oxidation takes
place on the active element, slightly raising Its temperature.
This Increases the resistance of a leg of a circuit bridge
and gives a direct current signal which drives the meter and
accessory circuit. The gas concentration for which the unit
1s calibrated 1s displayed 1n percent of the LEL.
The assembled units offer continuous monitoring of
areas in multiple locations. The units may be calibrated
to give direct readouts of combustible gases and vapors In
one or two ranges, 0% to 100% or 0% to 10% of the LEL. The
continuous sensory filaments operate at about one-half the
temperature of the conventional platinum wire filaments;
therefore the life of the circuit bridge Is relatively long.
A bridge life of 10,000 hr 1n air has been reported. The
control unit contains the alarm circuitry for Indicating
failure of the sensing device or an Increase of vapor con-
centration, readout circuitry for powering the meter or
potentiometric records, and all operating controls.
The assembled units are adaptable for use with any
gas or vapor whose molecular weight and explosive range are
known. Their application, therefore, extends to all Indus-
tries where combustible fluids and resultant gases and
vapors are employed.
lonization - The flame 1on1zat1on detector operates by
burning hydrogen 1n air *o produce a flame that contains a
negligible amount of ions. When hydrocarbons are Introduced
Into the hydrogen flame an lonization process ensues, where-
by a large number of Ions are produced. An electrostatic
field 1n the vicinity of the flame causes an ion migration
in which positive Ions are attracted to a collector and the
negative ions to a burner Jet. The small lonization current
established between the two electrodes 1s measured by an
-------
8-14
electrometer and the signal indicated by a meter or by a
potentiometric recorder. The magnitude of the signal is
an indication of the number of carbon-hydrogen bonds passing
through the flame and this is directly proportional to the
hydrocarbon concentration. The sampling system is an inte-
gral part of most commercial total hydrocarbon analyzers,
designed to measure continuously total hydrocarbon and
other organic compound concentrations in a gas stream or
ambient air (Davis Instr. Div.( 1965; Bendix, 1970; Beck-
man Instr. , 1969}.
Trace quantities of such organic compounds as hydro-
carbons (aliphatic and aromatics), aldehydes, amines, ketones,
acetates and alcohols in part-per-million range in air may be
detected. Carbon atoms bound to oxygen, nitrogen, or halo-
gens give reduced or no response, whereas there is no response
to nitrogen, carbon monoxide, carbon dioxide or water vapors
(EPA, 1971).
The analyzers are usually calibrated using methane and
results recorded in terms of methane equivalents. A number
of other gases such as butane and propane may also be used
depending on the sensitivity desired and the type of organic
to be monitored.
The specification for a given total hydrocarbon analy-
zer will vary as to model or manufacturer. They may be
portable or used as a stationary unit adaptable to many
industrial monitoring applications and as elaborate as the
addition of optional support equipment. The instrument may
offer one full scale range or 5 to 6 ranges with a 1:10 gain.
The full scale range may be 0 to 1 ppm, 0 to 10 ppm or
through several ranges up to 0 to 10,000 ppm hydrocarbons
per calibration equivalent. The range may be varied by ad-
justing the attenuation and flow rate of the sample to the
detector. Accuracies and noise levels are also different
and are expressed in terms of percent of the lowest full
scale per calibration gas. Zero drift varies and depends
on airflow rate, sample flow rate, fuel flow rate, ambient
temperature change, detector contamination and electronic
drift. Zero drift is usually expressed 1n range percent/24
hour period.
Other recording instruments using an ionization prin-
ciple for the determination of trace gases in the parts-per-
million and in some cases 1n the parts-per-billion range
have been developed and are commercially available (American
Industrial, I960).
-------
8-15
This method of gas analysis uses an lonization chamber
to detect an aerosol which is formed from the contaminant in
a number of ways. The ionization chamber is composed of a
stainless steel cylinder electrode and an inner electrode of
a heavy wire. An alpha emitter is placed along the inner
surface of the cylinder. The two electrodes are given oppo-
site charges which cause a flow of ion current through the
gas between them.
With only air present in the chamber, there is a rela-
tively constant flow of ion current. However, very small
concentrations of particular matter cause a pronounced drop
in this flow of ion current. The effect of the particulates
on the conductivity of the ion chamber is a measure of the
concentration of the gas or vapor of interest (Mine Safety,
1970). The formation of particulates for a wide range of
materials is accomplished by: reacting the trace gases with
various reagents to produce particulate matter; direct py-
rolysis of the sample; or a combination of both chemical
reaction and pyrolysis.
The conductivity is measured by a detector cell and a
compensator cell placed on two arms of a Wheatstone bridge
circuit. The presence of particulates causesa drop in ion
current in the cell and results 1n an unbalance of the
bridge which is amplified for driving a meter or a recorder.
There are portable models that are reported to be
accurate as well as easily operated. Applicable to the
scope and nature of this survey are the analyses of acid
and alkaline gases, oxides of nitrogen, and amines which
are sensitized through reactions with specific reagents.
For example, ammonia may be used to sensitize such materials
as halide acids, nitric oxide and sulfur dioxide. A com-
bination of pyrolysis and use of a reagent may be employed
in the determination of organic halides. On passing a
chlorinated hydrocarbon through a copper oxide converter
at elevated temperatures, a copper chloride aerosol 1s
formed.
The overall applicability of this instrument is limited
as to the variety of gases and vapors it can monitor. Sev-
eral of these gases have been mentioned, but its strongest
asset 1s not variety but the sensitivity that the Instrument
can achieve.
Ultraviolet Spectrometry - Ultraviolet analysis measures
the degree of light absorption as it occurs 1n a gas or 0
liquid sample. The ultraviolet spectrum ranges from 100A to
3800A*, and those gases whose nature It is to absorb in this
-------
8-16
ultraviolet region can be measured. In general, ethylene,
carbonyl structures and molecules which Include the benzene
ring In their structure all absorb 1n the ultraviolet region
(Holzbock, 1955 and American Industrial, 1960).
The ultraviolet spectrophotometer will detect gases
and vapors at low concentrations and will detect a great
array of gases and vapors that absorb in the ultraviolet
band. The Instrument may therefore be used either for com-
plete analyses of samples by running a complete spectrogram,
or for continuous analysis of process streams by operating
at a fixed wavelength critical to the analysis being made
(Eckman, 1950).
Ultraviolet spectrophotometry may be applied to the
detection of trace amounts of benzene, toluene, and other
aromatic hydrocarbons, and chlorinated solvents 1n air 1n
the ppm range (Univ. of Michigan, 1956), Polynuclear aro-
matics, some of which are believed to be carcinogenic, have
been qualitatively detected and quantitatively analyzed by
ultraviolet spectrophotometric methods (American Industrial,
1960) and as previously mentioned, ethylene and carbonyl
structures absorb In the ultraviolet band and are therefore
detectable with this method.
Descriptions and Illustrations of several types of
ultraviolet spectrophotometers as well as other spectro-
photometric Instruments that are commercially available have
been compiled (Wlllard, 1958). Special mechanisms have also
been described which permit automatic measurement on as many
as three plant streams by one instrument (Holzbock, 1955).
Most spectrophotometers are for stationary use as opposed
to the more portable photometers.
Infrared Spectrometry - The infrared spectrum ranges
from wavelengths of 7800X to 3,000,OOOA. Those gases or
vapors which will absorb in this heat radiation band can
therefore be measured. This applies to the analysis of
almost any organic and some inorganic compounds under the
proper circumstances (American Industrial, 1960).
Of all molecular spectroscopy, the infrared spectro-
Dhotometer 1s the most versatile. Infrared spectrophotom-
Pters may be used to analyze an entire sample or at least
a number of Us constituents. However, there are other
infrared spectrophotometers that are designed to contin-
,,n,ielv analyze for one constituent in a given sample.
Th«
-------
8-17
absorption characteristics. Conversely, elemental diatomic
gases like oxygen, hydroqen, nitrogen, helium, chlorine, etc
do not have absorption characteristics. Within acceptable
substances the concentration of any component in a mixture
can be determined by the specific absorption pattern that is
unique for each component.
There are three basic types of infrared spectrophotom-
eters: the dispersion analyzer, the positive nondispersion
analyzer and the negative nondispersion analyzer (Holzbock,
1955). Common to all three types are: they have been em-
ployed 1n commercially available Instruments; they provide
continuous measurement; and they analyze for only one constituent
either alone or in mixture for concentrations as low as ppm.
The dispersion analyzer concentrates upon a single
wavelength or a narrow wavelength band within the infrared
spectrum. The radiation of a particular wavelength that
passes through the sample without being absorbed 1s measured.
Generally, light of a second wavelength is simultaneously
applied and the ratio of transmission at two wavelengths is
measured. The dispersion analyzer may be readily adjusted
for various wavelengths and maximum sensitivity. However,
the optical system may become relatively complex.
Unlike the dispersion analyzer, the two nondispersion
analyzers utilize all the energy from an infrared radiation
source and pass it through the sample, unless the width of
the wavelength band 1s limited by filters. In addition,
the nondispersive analyzer usually spHtsthe infrared radi-
ation into two parallel beams.
The positive nondispersive analyzer operates by passing
one beam through the sample to be analyzed and from there
into a cell which is filled with the component to be detec-
ted. The other beam passes directly to a second cell with
the same component. The gas in both cells expandsdue to
the heat absorbed from the infrared radiation. The cell
directly exposed to the infrared radiation will expand more
than the cell which received Infrared radiation only after
it had passed through the sample. The relative expansion
of the two cells is then usually measured by means of a
variable capacitor. Also characteristic of this analyzer
is a light chopper that interrupts the radiation of the
infrared light source periodically, largely eliminating the
effect of changing ambient temperatures.
In the negative nondispersion analyzer, both beams pass
through the sample, but one traverses an additional cell
which is filled with the component to be detected. The non-
-------
8-18
absorbed radiation from each beam 1s then measured by a
thermocouple or bolometer and the difference measured as
an Indication of the concentration of the component for
which the sample is analyzed. This analyzer is character-
ized as being more sensitive to ambient temperature than the
positive type, less sensitive as an analytical Instrument
but simpler and more rugged.
The prisms for the infrared spectrophotometers are
usually made of four materials. The prism materials include
lithium fluoride, calcium fluoride, sodium chloride and
potassium bromide but quartz and cesium bromide have also
been used (Willard, 1958 and Eckman, 1950). The selection
of the prism is determined by the wavelength range most
adaptable to the substance under analysis.
These Infrared spectrophotometers have been described
as being reliable and easily maintained. They are relatively
rugged and yet versatile; they are simple in design, yet
possess wide construction tolerance (Conn, 1960).
Colorimetric - Colorlmetric methods Include general
laboratory wet chemical techniques as well as direct reading
colorlmetric instrumentation. The principle 1s based on the
formation of a specific color resulting from the reaction of
the contaminant with reagent or number of reagents. The
resultant color 1s then measured with a photometer. Sensi-
tive and specific colorlmetric reactors have been developed
for many of the air pollutants. Methods of colorlmetric
analysis are divided into three basic classes:
1. Detector tubes
2. Laboratory methods
3. Automatic instruments
The Initial cost investment and the degree of technical
skill required for application of these methods are repre-
sented 1n increasing order.
Detector tubes provide a noninstrumental technique for
semlquantitatlve analyses for many toxic gases and vapors 1n
the threshold limit ranges. The detector tubes are glass
tubes which contain selective, reactive chemicals impregnated
on sands, alumina gels, silica gels or other qels. The com-
oosltion of the reactive substrate Is determined by the gas
or vapor to be tested. As an example, for hydrogen sulflde,
the substrate may consist of granular silver cyanide on
activated alumina. For sulfur dioxide a mixture of Iodine
flel and tetrabase sand may be used. A yellow silica gel
Impregnated with a complex slllco-molybdate compound cata-
-------
8-19
lyzed by palladium sulfate is used for carbon monoxide. For
aromatic hydrocarbons, the substrate used may be a mixture
of sulphuric acid gel and paraformaldehyde sand (Univ of
Michigan, 1956).
Samples of the contaminated air are drawn through the
tubes by means of aspirators or assorted hand pumps. Some
hand pumps provide for measured volume samples, while both
aspirators and hand pumps are equipped with variable ori-
fices. The measured sample is drawn through the substrate
and the gas or vapor reacts with the chemicals in the sub-
strate, producing a stain which is directly proportional to
the concentration of that 9«»s or vapor in the suspected
stream. The length of the stain is measured by an appro-
priate precalibrated scale for the vapor being tested. The
stain may develop directly with contact of the gas or vapor
or may be developed with the addition of reagents.
The detector tubes are usually supplied as kits,with
aspirators or hand pumps provided. A listing of the gases
and vapors for which the Detector tubes can be used are
provided by the manufacturers (Davis Instr, Div., 1963 and
Mine Safety, 1971). Also Included 1n this listing are those
compounds that interfere with the respective reaction. The
effect of the Interference should therefore be considered
when measuring for specific compounds. Necessary reagents
are also provided when applicable. The detector tubes may
be the ready-to-use type or those that are mixed prior to
use and equipped with special filters and prefilters. Re-
mote sampling kits are available for sampling inaccessible
areas. In addition to these accessories, a pyrolyzing unit
may also be provided. The pyrolyzer separates toxic com-
pounds by the application of heat, whereby specific chemi-
cals are released whose concentration can be related to the
level of the original compound.
This type of detection is particularly suitable for
the small businessman. The Initial cost is quite low, the
technical skills required to analyze a sample are practically
nil and small businesses generally emit a single pollutant.
Laboratory colorimetric methods require a photometer
for measurement of the concentration of a developed color.
Photometers vary 1n complexity and concomitant cost. Simple
photometers employ a light source, filters, phototube and
readout. The more complex and expensive photometers use
gratings or prisms to provide light of the desired wave-
length. The sample which 1s collected must be treated chem-
ically to remove Interfering contaminants, If present, and
develop the desired colored compound. This, of course, re-
quires some technical skill plus associated laboratory
apparatus.
-------
8-20
Automatic colorimetrlc Instrumentation is available
for many contaminants. The basic instrument consists of a
sampling pump, a scrubber system to remove the contaminant
from the gas stream, automatic liquid metering of the solu-
tion, automatic reactant feed, associated electronics and
controls and direct readout. The instrument is versatile
in that various contaminants can be analyzed by changing
the scrubbing solution or reactant. This type of instru-
ment generally requires a high degree of technical skill
to select the appropriate separation and reactant solutions
and to maintain the instrument in a reliable operating
condition.
Electroconductivity - The electroconductiv1ty analyzer
continuously records concentrations of gases or vapors that
will ionize in water either directly or after decomposition
by heat. The principle of measurement is the differential
measurement of conductivity before and after a gas sample
ionizes in distilled water. The conductivity is measured by
two sets of platinum electrodes arranged in an alternating
current bridge circuit. This type of instrument is usually
used to continuously record atmospheric concentrations, but
has been adapted for process control (Univ. of Michigan,
1956). Instruments are available which permit periodic
check of gases or vapors at 3 to 13 remote points and the
results are shown on various recorders (Univ. of Michigan,
1956).
A continuous flow of water scrubs the gas sample
stream. The mixture is circulated around the platinum
electrodes and the amount of ionization is indicated. The
water is then passed through a deionizing bed and recircu-
lated through the system. In some instances the sample
need not pass through the pyrolyzing furnace before scrub-
bing with the water.
This type of system makes for a basic analyzer and is
adapted for the measurement of one gas or vapor in air in
the ranges of 1 to 5 ppm or lower if necessary for such
vapors as chlorine, sulfur dioxide and hydrogen sulfide
(American Industrial, 1960). Carbon tetrachloride, and the
oxides of nitrogen may also be determined. The system may
also be employed for the determination of organic chloride
vapors (Davis Instr. Div., 1963 and American Industrial,
1971).
Halogen Leak Detection - Halogen leak detectors main-
tain an ion current by electrically exciting an emitter.
The detector sensing element for the halogen leak detector
is a diode consisting of a heater element (positive) and a
collector (negative) arranged coaxlally (General Electric).
-------
8-21
A positive ion current flows at all times from the emitter
to the collector. When a trace of halogen gas is present
between the collector and emitter the ion current increases
markedly. The increase In ion current 1s linearly propor-
tional to the concentration of halogen from 0 to 1 ppm.
For concentrations from 1 ppm to about 1000 ppm, the in-
crease 1s exponentially proportional. Above 1000 ppm, no
further increase of ion current occurs and the element de-
sensitizes rapidly but cleaning usually restores original
sensitivity.
These instruments are portable and are designed for
continuous operation. The instruments are nonspecific in
the determination of halogenated hydrocarbons or mixtures
of halogenated hydrocarbons. Nonhalogenated compounds,
such as hydrocarbons, will not interfere, however; and
mixtures of halogenated vapors with other vapors may be
measured.
Designed for field use, the normal operating range is
0 to 500 ppm for most substances. The lower limit of de-
tection is about 10 ppm and the accuracy throughout most
of its range is about 10% of the amount being measured. The
instruments employing this principle are most often used for
the determination of perchloroethylene, trichloroethylene,
carbon tetrachloride, methylene chloride and other similar
halogenated hydrocarbons (Univ. of Michigan, 1956 and Davis
Instr. Div., 1971).
Emission Spectrometry - Emission spectrometers are
usually employed in the determination of elements and metal-
lic compounds. However, this principle has been applied to
the determination of halogenated hydrocarbons in air (Davis
Instr. Div., 1971). Briefly, emission spectrometers employ
an arc spark for producing radiation emissions and a grating
for refracting emitted radiation into a spectrum. The in-
tensity of the radiation lines are measured directly by means
of phototubes.
In this particular type of spectrometer, air containing
halogenated hydrocarbons is passed through a chamber con-
taining an alternating current electric arc between a copper
electrode and a platinum electrode (Univ. of Michigan, 1956).
A bright line spectrum of copper is produced when the air
surrounding the arc contains hallde vapors. The intensity
of the copper spectrum is proportional to the concentration
of hallde vapors present, and the blue lines are measured
with a blue sensitive phototube fitted with a blue glass
filter. The change in current output of the phototube is
then measured by a direct current vacuum tube voltmeter.
-------
8-22
This type of Instrument is expensive and 1s expected to
have little application in the measurement of absorbent bed
Inlet and outlet concentrations.
Mass Spectrometry - The mass spectrometer separates
Ions of various atoms, molecules or their fragments by pass-
ing the ions of these materials through a magnetic field.
The ions are deflected according to their mass and charge
and impinge upon a collector. The current Intensity of the
collector 1s proportional to the number of Ions which Im-
pinge on the collector.
Mass spectrometers are highly specific for individual
contaminants. The disadvantages are that they do not possess
the low level sensitivity of many other instruments, they are
expensive and they are not portable. Sensitivity can be
increased by concentration of a specific impurity of Interest,
Mass spectrometers are amenable to analysis of high concen-
tration of contaminants and the results from this type of
analysis can be used to determine what type of sorbent bed
should be used, to size the bed,and to predict the life time
of the bed.
Scentometry - Measurement of odors is, at best, semi-
quantitative even when only a single odiferous material 1s
present. When the test atmosphere contains a mixture of
odiferous materials, even semlquantltative identification
1s essentially Impossible. Fortunately, many processes emit
only one odor and since package sorbent devices will be used
1n many cases for odor control, it will be a straightforward
task to determine when the device needs replacement or re-
generation.
A scentometer 1s marketed which provides a means of
multiple dilution of a sample. A trained panel smells each
diluted sample and, if the pollutant Is known, an estimation
can be made of its concentration.
Another method of quantitatively defining odors 1s
given in ASTM D 1391-57. A sample is collected 1n an air
sampling syringe. The contents of the air sampling syringe
1s then Injected into a mixing syringe and diluted with
100 ml of clean air. After 15 sec, the syringe 1s placed
near the nostrils and the content 1s ejected for 2 to 3 sec.
Various dilutions are made until the odor 1s just percep-
tible The ratio of the total volume of the diluted sample
to the volume of the original sample 1n the diluted sample
<« a measure of the concentration of odor In the original
sample. Table 2-IV lists the odor threshold of some air
pollutants.
-------
8-23
Recommended Methods for Specific Classes of Impurities
Hydrocarbons
The hydrocarbons can be measured as a general class by
flame ionizatlon detection down to the ppm level. Gas-liquid
chromatoqraphy can be used to separate the various hydrocar-
bons and,when used 1n conjunction with flame lonlzatlon de-
tection, Individual hydrocarbons in a hydrocarbon mixture can
be measured at the ppm range. Ultraviolet and Infrared spec-
trophotometry can be used to measure individual hydrocarbons
1n low ppm ranges, also. Catalytic combustion provides a
means of detection at low levels, but is generally applicable
only when a single hydrocarbon (and no other catalytically
combustible material) 1s present. Thermal conductivity is
applicable down to about the 100 ppm level and can be used
In conjunction with gas-liquid chromatography for the detec-
tion of specific hydrocarbons. Mass spectrometry is limited
to measurement at approximately the 0.5* level but does pro-
vide detection of the individual hydrocarbons.
Oxygen Containing Organic Compounds
These compounds exhibit essentially the same detection
characteristics as the straight chain hydrocarbons. Again,
flame 1onizat1on is the most sensitive means of detecting
this class of compounds and chromatography can be used to
separate the various oxygen containing organics. Sensitivity
colorimetric methods have been developed for measurement of
oxygen containing organics, also.
Haloqenated Compounds
The halogenated compounds are particularly sensitive to
electron capture detection. The electron capture detector
has been used 1n conjunction with gas-liquid chromatography
to separate and detect mixtures of halogenated compounds.
The halogen leak detector 1s a suitable instrument for the
detection and measurement of halogenated compounds, also.
The flame ionlzation detector can be used if a single halo-
genated hydrocarbon is being detected.
Inorganic Oxides
Oxides such as CO can be measured by catalytic com-
bustion down to the few ppm level. Sensitive chemical
methods are available for the detection of other Inorganic
oxides such as S02*, Instrumentation has been developed which
will automatically perform this function.
-------
8-24
Odors
They pose the greatest problem 1n terms of quantifica-
tion. Fortunately, olfactory detection is the most practi-
cal means of sensing odors and, since the objective of sorbent
systems is to remove these odors, an inexpensive means of
detection exists. Semiquantitatlve estimations can be made
with the use of a scentometer.
Aromatic Hydrocarbons
These can be detected by the same methods used for
measurement of straight chain hydrocarbons. Again, flarte
ionization detection provides the most sensitive means~of
detection. Sensitive colorometric methods have been devel-
oped for many of the aromatics. Other methods include ultra-
violet and infrared spectrophotometry.
Polynuclear Hydrocarbons
The polynuclear hydrocarbons are generally of .interest
in the low ppm to ppb range due to the carcinogenic nature
of many of these compounds. Because of this low level re-
quirement and since other hydrocarbons are generally present
with the polynuclear hydrocarbons, ultraviolet -or Infrared
spectrometry are the best means of measuring this class of
compounds. Colorimetric methods are also applicable 1n
certain cases.
-------
Appendices
A Glossary
3 Information Sources
C Tables of Data
D Methods
E Sample Calculations
F Literature Cited
G Bibliography
-------
Appendix A
Glossary
A Adsorption potential equal to [T/Vm] log [pQ/p],
also a constant
Ac Area of adsorbent or catalyst bed, also collision
coefficient
B Constant
C Pollutant vapor concentration, also a constant
Cfc Pollutant breakpoint effluent concentration
Ce Pollutant effluent concentration from adsorbent
or catalyst bed
Cj Pollutant influent concentration to adsorbent or
catalyst bed
CQ Concentration of saturated vapor
D Diameter of adsorbent or catalyst bed
Dp Adsorbent or catalyst particle diameter
Dv Diffusion coefficient
E Heat of adsorption on different layers, also
kinetic energy
F Total gas flow
AF Free energy change equal to -RT In [p0/p]
AH Heat of adsorption or desorption
K Reaction rate constants
Kf Volumetric film heat transfer coefficient
L Adsorbent or catalyst bed length or depth
measure
Lc Critical bed length
Ls Saturated bed length
Lt Total bed length
Lz Adsorption zone length
M Molecular weight
N Avogadro's number, 6.03 x 102J molecules/mol
P,PA Total pressure
AP Pressure drop through adsorbent or catalyst bed
Q Heat of reaction, total heat
R Gas constant
S Surface area
AS Entropy change
T Absolute temperature
U Face velocity to adsorbent or catalyst bed
Um Intergranular gas velocity In adsorbent bed
-------
A-2
V Liquid molar volume of pollutant vapor at ambient
temperature
Vm Liquid molar volume of pollutant vapor at normal
boiling point
Vc Catalyst or adsorbent bed volume
W Total weight, adsorbent, catalyst or pollutant
Wc Weight of carbon
Wr Total weight of pollutant remaining in carbon after
regeneration
Ws Total weight of pollutant adsorbed in carbon
saturated layer
Wz Total weight of pollutant adsorbed in carbon ad-
sorption zone
a Superficial area of particles per unit volume
of particles
a,b,c Component species
d Pore diameter, carbon density
h Planck's constant. Wheeler mechanism index
k Constant
n Number of adsorbed layers, constant 1n FreundUch
equation
p Pollutant vapor pressure
Po Vapor pressure of pure liquid
r Pore radius
t Time, service time
tfc Service time to breakthrough concentration of C^
tc Contact time
v Volume of adsorbed vapor
vm Volume of vapor required to form a unlmolecular layer
a Polarizability
ct,3,y Constants
Y Surface tension
c Void volume in adsorbent bed
e-f Polanyi potential
n Viscosity
6 Fraction of surface area covered
X Heat of vaporization of pure liquid
u Dipole moment, viscosity of pollutant in air
v Characteristic light dispersion frequency
p Gas density
J Distance between centers of two dlpoles
T Multilayer correction factor
A Contact angle
u Amount pollutant adsorbed per unit quantity of
adsorbent
-------
A-3
cor Mean amount of pollutant adsorbed per unit quantity
of adsorbent that remains at the end of regeneration
Amount pollutant adsorbed in saturated layer per
unit quantity of adsorbent
Mean amount pollutant adsorbed in adsorption zone
per unit quantity of adsorbent
-------
Appendix B
Information Sources on Air Pollution
Trade Associations 1n the Washington, D.C. Area
Bureau of Raw Materials for Vegetable 011 & Fats
Council of Independent Laboratories
National Drycleaners Institute
National Paint, Varnish & Lacquer Association
Manufacturing Chemists Association
National Fisheries Institute
Bureau of Fish Oil and Meal Processes
Research Council of the Graphic Arts Institute
Trade Associations in the Chicago Area
National Restaurant Association
Brewers Association
Institute of Baking
National Canners - NCA Staff Center
Candy & Confectioners Institute
National Renderers Association
American Meat Institute
Institute of Paper Chemistry
Pollution Control Agencies
Allegheny County Dept. of Health
Pittsburgh, Pennsylvania
Southwest Air Pollution Control Authority
Vancouver, Washington
Los Angeles County Air Pollution Control District
Los Angeles, California
District of Columbia Dept. of Public Health
Washington, D.C.
Bureau of Air Pollution Control
Illinois Dept. of Public Health
Springfield. Illinois
Wyoming Dept. of Public Health
Cheyenne, Wyoming
Bay Area Air Pollution Control District
San Francisco, California
-------
B-2
Environmental Control Board
New York, New York
Houston Health Department
Houston, Texas
Fulton County Health Department
Atlanta, Georgia
Albuquerque Dept. of Environmental Health
Albuquerque, New Mexico
Air and Water Pollution Control
City of Jacksonville
Jacksonville, Florida
City of Chicago Dept. of Air Pollution Control
Chicago, Illinois
Dept. of Public Health
Philadelphia, Pennsylvania
Denver Air Pollution Control Agency
Denver, Colorado
Division of Air Pollution Control
St. Louis , Missouri
Plant Trips. Pollution Control
Vic Manufacturing Company
Minneapolis, Minn.
American Machinery and Foundry
Minneapolis, Minn.
Vulcan Cincinnati, Inc.
Cincinnati , Ohio
Charleston Rubber Co.
Charleston, South Carolina
Reigel Paper Co.
Edenburg, Indiana
Norfolk Tallow Co.
Chesapeake, Virginia
-------
B-3
Government Documents
Wash. D.C.
Title Ident. No.
Atmospheric Emissions from Fuel Oil Comb. AP-2
A Pilot Study of Air Pollution in Jacksonville,
Fla. AP-3
Air Pollution and the Kraft Pulping Industry AP-4
Dynamic Irradiation Chamber Tests of Automotive
Exhaust AP-5
Air Pollution in the Coffee Roasting Industry AP-9
Community Perception of Air Quality AP-10
Reactivity of Organic Substances in Atmospheric
Photooxidation AP-14
Selected Methods for the Measurement of Air
Pollution AP-11
An Air Pollution Management Plan for Nashville AP-18
Effects of the Ratio of Hydrocarbon to Oxides of
Nitrogen, Auto Exhaust AP-20
Continuous Air Monitoring Program, Cincinnati AP-21
Continuous Air Monitoring Program, Washington,DC AP-23
Atmospheric Emissions from Coal Comb. AP-24
Seminar on Human Biometeorology AP-25
Workbook of Atmospheric Dispersion Est, AP-26
Air Pollution Aspect of Tepee Burners AP-28
Rapid Survey Technigue for Estimating Community
Air Pollution Emissions AP-29
Selection and Training of Judges for Sensory
Evaluation Diesel Exhaust Fume AP-32
Sources of Polynuclear Hydrocarbons in the
Atmosphere AP-33
Air Pollution Engineering Manual AP-40
Compilation of Air Pollutant Emission Factors AP-42
A Compilation of Selected Air Pollution Emission
Control Regulations and Ordinances AP-43
Handbook of Air Pollution AP-44
Interim Guide of Good Practices for Incineration
at Federal Facilities AP-46
Air Pollution Translations, Vol. I AP-56
Air Quality Criteria for Carbon Monoxide AP-62
Air Quality Criteria for Hydrocarbons AP-64
Air Pollution Translations, Vol. II AP-69
National Survey of the Odor Problem, Phase I,
Jan. 1970, prepared by Copley Int. Corp.
Nationwide Inventory of A1r Pollutant Emissions,
1968, HEW
-------
B-4
SURVEY OF AIR POLLUTION FROM SMALL STATIONARY SOURCES
AN AIR POLLUTION CONTROL AGENCY REPORT
Section I General Information
Name of agency:
Address: City
State
Name of Individual:
Title:
Telephone number: AC_
Date:
Responsible for pollution control in: (name)
Township
City
County
State
Region
Responsible for emission from: (check)
Commercial
Industrlal
Agri cultural
Institutional
-------
B-5
Section II Emissions Source Complaints
The purpose of this question is to determine the need for
control of the various small emissions sources.
Fill in appropriate square with number of complaints per
year. If complainants did not identify odor or other effect
produced by an air pollutant emitted by a source, these may
be recorded in the last column. The next to last column,
ill-effect on health, refers to headaches, nose, lung or
skin irritations.
Number of complaints per year
o
o
o
(U
en
O)
c
o
o
01
c
o
F"
ut
o
O
O
o
Dry cleaning
Paint shop
Print shop
Electroplating shop
Gasoline transfer | | j |
Restaurants
LDLUdK
a a a EH CD c
CD [Zi iZD IZ) L
Food stores,
markets
Small chem. mfg.
Incinerators,
dwelling, school,
hospital
Others
aoaooo
aa
a
-------
CO
I
Section III Amount of Air Pollutant Discharged From Small Emission Sources
The purpose of this question is to determine the problems that might be
encountered in the control of emissions by package sorbent or catalytic com-
bustion devices. It also supplies information on sizing of the control devices
for the various pollutant producing operations.
The following table has four column headings under which data may be
tabulated.
Size of source asks for a judgment as to the medium size or size range
for each operation in terms used by the particular trade.
Type, odor or chemical formula asks for identification of the pollutant
in terms of type of odor, or chemical formula or class of compounds (halogen,
sulfurated, hydrocarbons) with some estimate of molecular weight range.
Rate of emission asks for data on amount of pollutant lost to the
atmosphere per unit of time, or per unit of material processed or per unit
serviced.
Concentration and/or rate of air exhaust asks for data on pollutant
concentration with air exhaust rate if data on rate for previous column is not
on record. In the case of odor, total air exhaust rate may be the only
numerical information available for the last two columns. Exhaust rate should
be identified with size of source.
-------
Cone, and/or
Size of Type, odor or Rate of rate of
Source source chemical formula emission air exhaust
Dry cleaning
Paint shop
Print shop
Electroplating
shop
Gasoline
transfer
Restaurants,
etc.
Food stores,
markets
Small chemical
manufacturers
Incinerators ,
dwel1 ings ,
schools ,
hospitals
Others
CO
I
-------
Table C-I Properties of Pollutant Vapors Emitted From Small Stationary Sources
Chemical
Pollutant*
Tridecanol
Dodecane
Undecane
2-Ethyl hexyl acetate
Decane
Butyl carbitol
Nonane
2,6-Dimethyl-4-heptanone
Nonanal
Diethyl cyclohexane
Butyl cyclohexane
1 ,8-Octanediol
4,5-Octanediol
Hexyl acetate
2-Methyl pentyl acetate
1-Octanol
2-Octanol
1-Methyl pentyl acetate
formula
CH,[CH2]12OH
CH3[CH2]10CH3
CH3 [CH3
J9 CIU
CH3COOCH2CH[C2H5]-
Ck Ha
% 9
CH,[CH2]eCH,
6[CH2]2OH
CH,[CH2]7CH3
[(CH,)2CH CH2]2CO
CH3[CHj
[cX;:
HOLCH2
]7CHO
[C2H5]2
CfcHg
.Oil
C3H7CH[OH]CH[OH]-
C,H7
CHjCOOCjH,
CH,COOC2Hj[CH3]C,H7
CH,[CH2]7OH
CH,COOCH[CH3]C,,H,
vm»
cm3/mol
305
274
251
238
229
213
207
207
207
207
207
203
203
196
196
194
1/\ M
94
194
Boiling
point, LEL,
A ^ ^ ^ ^K
r ppm
_ _ _
421 6,000
383
A f\ /±
390
345 8,000
448
302 7,400
334
365
354
336
381
Industry
number
4
50
.8
1,4,5
1
1
1,4,5,8
51
1
4
4
4
4
1,4
i
o>
er 3>
-^ -a
10 -a
IA to
r»
0 0.
X
0
t» r>
r*
O*
* Wherever possible the nomenclature approved by the International Union of
Chemistry was used.
-------
Table C-I (continued)
o
I
Pollutant
2-Ethyl hexanol
Diethyl cyclopentane
2,6-Dimethyl-2,5-
heptadien-4-one
Butyl cyclopentane
Octane
3-Octanone
Octanal
Butyl benzene
aPinene (turpentine)
Butyl-2-hydroxy-propanate
Pentyl acetate
Carbitol
Phenyl acetate
Dipropyl sulfide
Difurfuryl ether
Heptane
Heptanal
3-lleptanone
5-Methyl-2-hexanone
2,4-Ofmethyl-3-pentanone
Ethyl cyclohexane
Chemical
formula
CHH9CH[C2H5]CH2OH
Cs H. [CjHs ] .
[(CH,)2C = CH]2CO
C5H9[CH2]3CH3
CHS(CH2).CH,
CH3CH2CO[CH2]1,CH3
CH3[CH2]6CHO
C6H5(CH2)3CH3
CH,CH[OH]COOC.H,
CH3COO[CH2]kCH3
CH,CH20[CH2]20-
[CHll-OH
CH.COO C6H,
3 o 5
[C,H7]2S
[OCH = [CH]2=CCH2]20
CH3[CH2]sCHj
CH3[CH ] CHO
CH3CH2CO[CH2]3CH3
CH CO C H [CH3]2
f(CH3 )2CHJ2CO
C
-------
Table C-I (continued)
Pollutant
Isopropyl benzene
Propyl benzene
Dimethyl cyclohexane
2-Phenoxy-ethanol
2-Butoxy-ethanol
2-Ethoxy-ethyl acetate
1 ,6-Hexanediol
2,3-Hexaned1ol
Trlethylamlne
1-Methyl-propyl acetate
Cyclooctane
Butyl acetate
2-Methyl-propyl acetate
Dllsopropyl ether
Isopropyl propyl ether
4-Methy1-2-pentano1
2-Methyl-l-pentanol
4-Hydroxy-4-methyl-
2-pentanone
2,4-01methy1-l ,3-
pentadlene
2,3-D1methyl-l ,3-penta-
dlene
Chemical
formula
C6H5CH[CH3]2
C6H5[CH2]2CH5
C.Ht.CCH.J,
C,H,0[CH2],OH
CH,[CH ]3OfCH,]2OH
CH3COOLCH2J2OC2H5
HO[CH,]6OH
C,H7[CHOH]2CH,
[?2HJ,N
CH,COOCH[CHj] C2H5
C.H1S
CH,COOC%H9
CH,COOC,H,[CHJ2
[(CH.).CHl.O
rCHjI.CHOLCH.l.CH,
LCHsl2CsH%[Ofl]CHs
C,H7CH[CH.]CH2OH
[CH.]2C[OH]-CH2
cocfi.
CH2=C[CH.]CH=
C[CH,]|
CH2=C[CH,]C[CH3]=
CaH,
V ,
cms/mol
162
162
162
160
160
160
159
159
159
155
154
152
155
152
151
150
150
150
148
148
Boiling
point,
°F
306
318
ca 246
ca 340
313
482
402
192
ca 298
260
ca 156
181
266
ca 298
LEL,
ppm
9,000
8,000
11 ,000
12,000
12,000
14,000
14,000
10,000
18,000
Industry
number
1,10
1
1
4
1.4
1,4,5,8
4
4
51,52
1
4f
,5
1,4,7
1,4
1,4
5,8
1,4
4
4,7
51
51
o
I
to
-------
Table C-I (continued)
o
I
Pollutant
Dimethyl cyclopentane
Ethyl cyclopentane
2-Hexanone
Hexanal
4-Methyl-2-pentanone
P en tachlo roe thane
Xylene
Ethyl benzene
Hexane
Chemical
formula
cXtaftsi
CHjCO[CH2]3CH3
CH3[CH2]%CHO
[CH3]2CHCH2COCH3
C13C CHC12
C6HH[CH3]2
C6H,C2H,
CHS[CH2]%CH,
Ym »
cm'/mol
144
144
141
141
141
141
140
140
140
Boiling
point,
°F
217
258
263
242
324
291
277
154
LEL,
ppm
12,000
14,000
10,000
10,000
12,000
Industry
number
1
1
1
51
1,4,5,6,7,8
6
1,4,5,6,7,8
1
1,4,6,7,9,10,
51
Asparagine
Cycloheptane
2-Hydroxy-ethyl propanate
aChlorotoluene
3-Methyl butanoic acid
4-Methy1-3-penten-2-one
1 ,2-Dichlorobenzene
Propyl acetate
Isopropyl acetate
Cyclohexanol
2-Methyl-2-butanol
2-Pentanol
I-Pentanol
H2NCOCH2CH[NH2]-
COOH
CH2[CH2]5CH2
C2H5COOLCH2]2OH
C6HSCH,C1
[CH3]2[CH2]2COOH
[CHjJ.C-CHCOCH,
C6H,C12
CH3COOC3H7
CH3COOCH[CH3]2
C6HMOH
C2H5C[OH][CHj]2
CH,[CH2]2CH[OH]CH3
140
137
137
136
134
133
132
129
129
127
127
127
127
415
244
354
350
266
354
214
199
321
215
246
ca 279
15
20
20
18
10
12
10
,000
__ _
,000
,000
,000
,000
,000
,000
57
4,5
4
7
51
1,4
4,7,
1,4
1,4
1,4
4
4
1,4,
51
51
-------
Table C-I (continued)
Pollutant
Chemical
formula
1,1,2-Trichloro-
1,2,2-tn'f luoroethane
Pentane
2-Pentanone
Cyclohexanone
Toluene
3-Hethyl butanal
Pentanal
2-Methyl butane
3-Methyl-2-butanone
Cyclohexane
2-Furyl methanol
Tetrachloroethene
2-Ethoxy-ethanol
1,3-Butanediol
1,4-Butanediol
Diethylamine
1-Pentene
2-Methyl-tetrahydrofuran
1-Methyl-l,4-epoxybutane
Butanoic acid
Diethyl ether
1 ,1 ,1-Trichloroethane
Ethyl acetate
FC1-CCC1F.
CH3[CH2]jCH3
CH3[CH2]2CO CH3
C«HI00
C6H5CH3
[CH3]2CHCH2CH 0
CH3[CH2]3CHO
[CH3]2CH CH2CH3
[CH3]2CH CO CH3
[C H 0]CH2OH
C12C3= CC12
C2H50[CH2]2OH
HO[CH2]2CH[OH]CH3
HO[CH2],,OH
[CiH5]iNH
CH2 * CH[CHJ2CH3
[C%H70] CH,
CH«CH[CH2]jO
» i
CH3[CH2]2COOH
[C2Hs]20
CH3C Cl s
CH,COOC2H.
120
118
118
118
118
118
118
118
118
118
117
116
116
114
114
112
111
110
110
108
106
106
106
Boiling
point, LEL,
°F ppm
ca
ca
ca
ca
118
97
215
312
231
198
216
82
203
178
340
250
275
399
455
133
84
172
149
327
94
165
171
14,000
16,000
11,000
14,000
25,000
...
13,000
18,000
17,000
20,000
18,000
15,000
20,000
20,000
18,000
25,000
2,3
4,6,10,51
1,4
1,4,6,7
1,4,5,6,7,8,
51
51
51
10
4
1,4,7
2,3,6,7
4,5,7
4
4
51
10
51
4
51
1,6,7
2,4
1,4,7,8
o
I
en
-------
Table C-I (continued)
Pollutant
Chemical
formula
2-Methyl-2-propanol
2-Methyl-l-propanol
1-Butanol
2-Butanol
Phenol
1,3-Pentadiene
Dimethyl dlsulfide
Tetrachloromethane
Cyclopentane
Trichloroethene
1-Nitropropane
2-N1tropropane
Butane
2-Methyl-propane
Butanone
2-Methy!-propanal
1,4-D1oxane
Benzene
Butanal
1»2-Propaned1ol
2-Methoxy-ethanol
Trimethylamfne
1-Butene
2-Methyl*propena1
1,2-Dfchloroethane
[CH3 ],COH
CH3 [CH2]2CH2OM
CH3[CH2]3OH
C2H5CH[OH]CH3
C6 Ms OH
CH3CH = CHCH = CHj
[CH3 ]2 S2
CCK
CH2[CH2]3CH2
C12C = C HC1
CSH7N02
[CH3]2CH N02
CH3[CM2]2CH3
[CH3]2CH CH3
C2H5COCH3
[CH3]2CHCHO
]20 CHtCH2
6fi
CH3[CH2]2CHO
HOCH2CH[OH]CH3
CH.O[CH2]2OH
CH2 * CHCH2CH3
CH4 = C[CH3]CHO
Cl H CCH Cl
y
cmVmol
105
105
105
105
105
104
103
101
100
98
97
97
96
96
96-
Boiling
point,
op
179
244
210
359
ca 109
242
171
120
188
266
248
31
14
175
LEL,
ppm
17,000
17,000
14,000
17,000
15,000
.
26,000
26,000
19,000
18,000
20,000
Industry
number
4
1,4
1,4,7
1,4
55,61
4,6
52
6,7
1
2,3,6,7
1,4,7
1,4,7
10
10
1,4,5,6,7,8,
51
96
96
95
95
92
92
92
89
89
88
ca
142
214
176
168
372
253
38
21
155
182
16,000
20,000
14,000
14,000
26,000
23,000
20,000
16,000
C2.000
51
7
1,4,6,7,51
51
4
1,4,7
51,52
10
51
6,7
-------
Table C-I (continued)
Pollutant
Tetrahydrofuran
Dimethyl sulfoxide
Propanoic acid
2-Propanol
1-Propanol
Methyl acetate
1 ,3-Butadlene
Butyne
Ethanethiol
Ethanolamlne
Nltroethane
Propanone
Propane
Propanal
Propanenltrlle
Imldazol
Ethanedlol
Propene
Propenal
Propenenitr1le
Carbon dlsulflde
Chemical
formula
H
CH,CH2COOH
[CH3]2CHOH
CH,CH2CH2OH
CH3COOCH3
CH2 = CHCH = CH2
CH3CH2C = CH
CH3CH2SH
H2N CH2CH2OH
CH3CH2N02
[CH3]2CO
CH3CH2CHS
CH3CH2CHO
CH3CH2CN
NH CH = NCH
HO[CH2]2OH
CH
CH2
CH2
CH2
SCS
CH CH3
CH CHO
CHCN
V
cm'/mol
88
86
86
84
84
83
81
81
77
75
75
74
74
74
73
72
70
67
67
66
66
Boiling
point,
°F
147
372
286
180
206
135
24
46
98
338
239
133
-48
119
206
492
388
-54
126
172
113
LEL,
pprc
20,000
26,000
29,000
23,000
21,000
31,000
20,000
_ _ -
28,000
---
34,000
30,000
22,000
29,000
31,000
32,000
20,000
30,000
30,000
10,000
Industry
number
7
4
51,61
1,4,7,9,51
1,4,7,51
1,4,7
4,6
6
51,52
7
1,4,7
1,4,5,7,51,61
10,57
51,61
6,51
51
4,51
57
6,52,54
6,51
52
o
i
-------
Table C-I (continued)
o
I
00
Pollutant
Chemical
formula
Ethylamine
Di chloromethane
Ethanoic acid
Ethanol
Propyne
Methanethiol
Ethanal
Nitromethane
Ethanenitrile
Sulfur dioxide
Methanol
Methanoic acid
Hydrogen sulfide
Methanal
Nitrogen dioxide
Hydrogen chloride
Ammonia
Carbon monoxide
C2HSMH2
CH2C12
CHjCOOH
CH3CH2OH
CH3C = CM
CH3SH
CH3CHO
CH,N02
CHjCN
S02
CH.OH
HCOOH
H2S
HCHO
N02
HC1
NH3
CO
"m »
cm'/mol
66
65
64
61
59
55
54
53
51
42
42
42
33
30
27
25
22
22
Boiling
point,
°F
63
104
244
173
-9
43
69
214
176
14
149
212
-78
-6
70
_ _ _
-27
...
LEL,
opm
35,000
155,000
40,000
33,000
17,000
39,000
41 ,000
73,000
60,000
180,000
43,000
40,000
_ _ _
160,000
Industry
number
51
2,5,7
4,51,55,57,61 ,
63
1 ,4,5,7,51 ,52,58
4
51,55
51
1,4,7,55
6
6,63
1 ,4,7,55,57
57,61
51,52
57,60,61,63,65
63
65
51,57,60,63,65
63
-------
C-9
Appendix C
Table C-II Flammabil ity Characteristics of Organic Vapors
in Ai r
Organic vapor
Methane
Ethane
Propane
Butane
Pentane
Hexane
Heptane
Octane
Oecane
Dodecane
Ethene
Propene
1-Butene
2-Butene
1 ,3-Butadiene
Ethyne
Benzene
To! uene
Ethyl benzene
Xylene
Cyclobutane
Cycl opentane
Cyclohexane
Cycloheptane
Methanol
Ethanol
1-Propanol
2-Propanol
1-Butanol
Dimethyl ether
Diethyl ether
Molecular
weight
16
30
44
58
72
86
100
114
142
170
28
42
56
56
54
34
78
92
106
106
56
70
84
98
32
46
60
60
74
46
74
Ethyl propyl ether 88
Ethanal
Propanal
44
58
Heat of
combustion,
Btu/ftJ
1 ,050
1 ,850
2,640
3,180
4,200
4,950
5,760
6,530
6,870
9,080
155
2,310
3,050
3,040
2,880
1 ,560
3,920
4,520
5,480
5,450
3,100
3,920
4,420
5,440
797
1,640
2,410
2,380
3,200
1,730
3,030
3,760
1,400
2,010
Auto-
Ignition
temp. °F
997
959
939
808
543
502
477
464
446
417
914
856
723
615
784
581
1097
1054
860
986
_ - _
725
518
_ --
702
792
824
752
689
662
356
- -
347
LEL,
ppm
50,000
30,000
21 ,000
18,000
14,000
11 ,000
12,000
10,000
8,000
6,000
27^000
24?000^
17,000
'18,000
20,000
25,000
13,000
12,000
10,000
11 ,000
18,000
15,000
13,000
11 ,000
67,000
33,000
22,000
20,000
11,000
34,000
19,000
19,000
40,000
37,000
-------
C-10
Table C-II continued
Organic vapor
Propanone
2-Butanone
2-Pentanone
2-Kexanone
Molecular
weight
58
72
86
100
Ethyl acetate 88
Propyl acetate 102
Isopropyl acetate 102
Heat of
combustion,
Btu/ft3
2,020
2,910
3,680
4,210
2,690
Auto-
ignition
temp. °F
1000
961
941
990
939
842
860
LEL,
ppm
26,000
10,000
15,000
12,000
22,000
20,000
18,000
-------
Appendix D
Methods
Method for Calculating Vm
Additive Volume Increments to
Calculate Vm, Method of LeBas
Increment,
Element of factor cm'/mol
Carbon 14.8
Hydrogen 3.7
Oxygen
Doubly bonded '«*
Methyl ester and ethers 9.1
Ethyl ester and ethers 9.9
Higher esters and ethers 11.0
Adds 12.0
Joined to S. P. N 8.3
Nitrogen
Primary amines 10.5
Secondary amines 12.0
Fluorine 8.7
Chlorine 21.6
Bromine 27.0
Iodine ----
Sulfur 25.6
Ring
3-membered - 6.0
4-membered - 8.5
5-membered -11.5
6-membered -15.0
Naphthalene -30.0
Anthracene -47.5
To calculate Vm, the number of elements of each type in
the molecule is multiplied by the volume Increment for each
corresponding element. The totals for each element are added
to get the total molar volume. If the molecule contains ring
structures, the corresponding volume Increment Is subtracted
from the above total.
-------
D-2
Lower Explosive Limits of Mixtures
Method for calculating lower explosive limit (LEL) of
a mixture of combustible organic compounds, based on modi-
fied Le Chateliers1 mixture law.
100
+ P3/N3
p-j, P2, P3»»*«Pn " volume % of each flammable vapor.
NI , N2, N3«..»Nn « volume % of each flammable vapor 1n
air at the lower explosive limit.
For the mixture
LEL of each vapor
P,% N,% ppm
2-Ethoxyethyl acetate 10.0 1.2 12,000
Toluene 36.3 1.4 14,000
Propanone 53.7 3.0 30,000
The calculated LEL for the mixture 1s 1.92X or
19,200 ppm.
-------
D-3
Van der Waals1 Constant £
Van der Waals1 a 1s a force of attraction constant
incorporated into the" ideal gas equation to make it more
generally applicable to nonideal vapors. The constant b
is a volume factor related to the liquid volume of the
vapor.
pv RT Ideal gas equation
(v-b) RT Van der Waals' equation
of state
v is the molar gas volume at pressure p and temperature T.
-------
D-4
CC14 Test Method
The apparatus used to determine CC14 capacity 1s shown
1n Figure D-l. The stepwise procedure employed 1s as
follows:
1. Place approximately 1/2 gram of sample
Into a prewelghed weighing bottle.
2. Heat samples to 110°C under vacuum,
<1 mm Hg (valve 1 open, valve 2 closed).
3. After a few hours, remove vacuum, cap
bottles and place 1n desslcator to cool.
4. Weigh bottles and replace 1n ovens with
the caps again ajar.
5. Heat to 40°C under vacuum, <1 mm Hg.
6. Freeze CC14 In reservoir with cold bath
of dry Ice/acetone or methanol.
7. With vacuum still being applied, open
valve 2 to evacuate the volume above
the frozen CC14.
8. After 15 minutes, close valve 2 and
remove cold bath, allowing CC14 to liquefy.
9. Apply wet 1ce bath around CC14 reservoir.
10. Close valve 1 and disconnect vacuum pump.
11. After 0014 temperature equals 0°C and
oven temperature equals 40°C, open valve
2 SLOWLY.
12. After 3 hours, close valve 2 and open valve 1
to restore the oven to atmospheric pressure.
13. Recap bottles and place 1n desslcator to cool.
14. Rewelgh bottles.
15. Compute % CC14 activity as follows:
A. Sample weight - weight from 4 -
weight of empty bottle
-------
D-5
B. Weight CC14 picked up » weight
from 14 weight from 4
(B) - blank
% CC14 activity » rrr x TOO
-------
o
I
Dewar cold bath
Thermometer
Sample
bottles
To vacuum pump
Heating control
for vacuum oven
Figure D-l Static CC14 Test Apparatus
-------
D-7
Activated Carbon Regeneration
Two computer programs were written to simulate the
desorption of organic compounds from activated carbon using
heated air and steam as regenerating agents. These programs
use heat and mass balances combined with the concept of
theoretical adsorption stages to model the bed. Equation 19
of Chapter 4 is used to calculate the organic compound's
vapor pressure over the carbon bed and this, in turn, used to
calculate the latent heat of desorption. Equation 19, based
on the Polanye potential theory of adsorption, is reproduced
below with minor variations.
A « T/[2.3 Vm] In [p0/p] (1)
Correlation of Potential Equation with Amount
Adsorbed
The data of the carbons and three organic compounds were
fitted, using least square error techniques, to polynomial
expressions as follows
In u - a * SA + yA2 + 6A3 (2)
where u 1s the amount adsorbed, measured 1n cm' 11q/g.
The values of the constants o, 0, Y and 6 are given 1n
Table D-I for the carbons.
The predicted value of A, given co, 1s
A « o + B In u + Y [In "]2 + 6 [In w]s (3)
The values of the constants for Equation 3 are given 1n
Table D-II.
In no case can A be less than zero. If a negative value
is obtained, then u> has a larger value than the actual adsorp-
tive capacity of the bed and unbound organic liquid exists.
Under this circumstance the vapor pressure will equal that of
the pure liquid and A is equal to zero.
Heat of Desorption
The latent heat of desorption is equal to the heat of
vaporization of the pure organic liquid and its heat of
wetting on the adsorbent. The heat of wetting can be related,
using the Clauslus-Clapeyron equation, to the vapor pressure
-------
o
I
00
Table D-l Numerical Values for the Constants of Equation 2
Carbon
BPL V
BPL II
BPL VI
GI
Table D-
Carbon
BPL V
BPL II
BPL VI
GI
A range
0 0.0125
w<0.078
u>0.078
to<0.172
u»0.172
u<0.0175
o»0.0175
a
-0.781007
-0.802935
-0.182024
-0.801228
-0.104591
-0.2421
3.35328
Values for
a
1.67798
-7.80764
-0.954685
-11.7179
-0.628067
-26.0081
9.06813
-1.67587
0
-9.119E-2
-7.77809E-2
-0.189647
-4.57639E-2
-0.166206
-0.709226E-2
-0.388684
the Constants of
6
-4.19038
-11.4475
-5.27179
-18.4925
-6.01627
-50.3815
-2.09203
-9.102
Y
-5.90339E-3
-4.94474E-3
-5.00803E-3
-8.13912E-3
-1 .98237E-3
Equation 3
Y
-1.86287
-5.34297
-26.7388
1.61275
6
7.63933E-5
...
. . -
...
6
-0.159537
-0.711735
-5.53189
-0.132675
-------
D-9
of the adsorbed organic compound, which in turn can be pre-
dicted using the potential theory equation (Equation 1).
The additional heat will be small for small A values, but
will increase for the larger values.
The Clausius-Clapeyron equation has the form
In PO - - jjzf + k (4)
where X is the latent heat of vaporization of the pure
liquid. When solved for In p, the potential theory Equa-
tion 1 has the form
In p - In po - 2.3 AVm/T (5)
By substitution of Equation 4 into 5, the following equation
1s derived which relates p to the heat of desorptlon AH,
\ 4. O O A V p
_ . A T fc» J "»m1^ /r\
In p k - 57 (v)
AH - X + 2.3 AVmR (7)
Since A changes as the amount of organic compound is
desorbed, the heat of desorption also varies. The amount of
heat absorbed by the system can be found by Integrating the
heat of desorptlon over the amount desorbed. The equation
for carrying out the integration has the form
2.3 VmRWc , . .
jj / A dw, (8)
where Q " Btu heat absorbed
R - gas constant, 3.42 Btu/[lb mol x °F]
Wc ib carbon in bed
u Ib organ1c/lb carbon
(i>1 U2 Ib organic/lb carbon at beginning and
end of stage
The adsorption potential A 1s a function of to. For con-
centrations such that A is large (small amount adsorbed) the
plot of log u versus A is a straight line. For small values
of A, the plots can be considered straight lines on semi-log
graphs If the amount of adsorbed organic compound does not
-------
D-10
vary over a factor of 2.
The Integrated form of Equation 8 1s as follows
612
/A du [C8-C9][to)2-ui] + Cg [w2lnu2 - o^lnw]] (9)
W]
Here
C9 ' U
C8 « Ai-Cg In MI
A » A2 when u - 012 and A = AI when u » ai]. The Hm1t of
(»1 In ui 1s zero when o>i approaches zero.
The derivation of the Integral form of heat absorption
equation. Equation 9, Involved the following steps. Given a
straight line potential plot, the following 1s true
A » Cg + Cg In to> (10)
The Integrals to be evaluated are
^-to)2 x*
A dw » /Cg dw + /Cg In u> dco
wl
Integrating the second expression by parts
W2 -&2 ~1U)2
A dto) » Cg to) + Cg to) In to) - Cg / db)
-wi 3 * ^9 [to)2lnu2 Wilnu-j] (12)
The constants Cg and Cg are evaluated by solving simul-
taneously the following equations
Ag * Cg + Cg In «2
AI » C8 + Cg In MI
-------
D-n
This yields
9
.AZ--AI
1 n
C8 - A-j-Cg In wj
Vapor Pressure of Pure Organic Liquid
The vapor pressure versus temperature relationships for
water, trichloroethene, 4-methyl-2-pentanone and propanone
were fitted by least mean square techniques to the equation
In p0 - a + 0/T + C In T
(13)
The numerical values for these constants are given 1n Table
D-III.
Table D-III Numerical Values for Constants In Equation 12
Compound
Water
Trichloroethene
Propanone
4-Methyl-2-pentanone
Range °C a 3 C
25 to 100 50.1243 -6598.49 -4.35917
25 to 150 10.9567 -3686.53 1.00381
25 to 150 39.3263 -4774.12 -3.14373
25 to 125 45.1415 -7059.07 -3.4225
Logic Diagram for Air-Regeneration
The programs make use of heat and mass balances and
assume the organic vapors follow the perfect gas laws. There
1s little information available on heat and mass transfer
coefficients, so a "theoretical plate" type of approach was
used. The bed 1s divided into 32 theoretical segments and
thermal and mass transfer equilibria are assumed at each
segment. A given time increment Is chosen, and the gas which
enters during this Interval 1s allowed to come to full equi-
librium with the carbon. This gas then enters the next seg-
ment.
The logic diagram for air-regeneration is shown 1n
Figure 0-2. The heat and mass balances are carried out for
each segment with a trial and error search for the amount
-------
o
I
ro
For I'th segment
calculate total
moIs of organic
u0> enthaloy of
gas olus carbon.
Set hiah and low
limits.
Calculate new bed temoerature.
Pressure of orqanic vaoor over
carbon at bed temperature and
Calculate total organic
compounds.
Set up gas
Inlet
condltlons.
32
Seqments
done
Set gas
temperature
plus
composition,
Update cumulative
suns. Sum remaining
organlcs.
Print
results
At
report
point
New
value
wlthin
factor
of 2
Yes
Set low
limit
to «] .
Figure D-2 Logic Diagram for Air-Regeneration
-------
0-13
of organic compound remaining adsorbed on the bed. The heat
of desorptlon 1s modeled exactly.
The following restrictions and assumptions are to be
noted:
1. The heat capacity of the organic vapor and
the air are constant with respect to temp-
erature. For the temperatures occurring
during stripping, this 1s satisfactory,
2. The bed contains 32 equilibrium stages.
The program can be easily changed to give
either fewer or greater stages. Going above
32 stages 1s not appreciably different; fewer
stages will increase the amount of regenerant
required.
3.
required.
The latent heat of the pure compound is con-
stant with temperature.
4. The heat capacity of the organic compound on
the carbon 1s equal to the gaseous heat
capacity. This is a thermodynamic require-
ment once assumption No. 3 is made.
5. The organic vapor and the air follow the
perfect gas laws.
Logic Diagram for Steam-Regeneration
Figures D-3 and -4 show the logic diagram for the steam
system. The heat and mass balances are carried out for each
segment, with a trial and error search for water content and
the amount of adsorbed organic compound remaining on the bed.
Again, the heat of desorption of the organic compound is
modeled exactly.
This program permits several flow regimes to exist simul-
taneously:
1. The segment temperature is below an equilibrium
temperature. The entering steam (1f any) con-
denses on the bed and there is no exit steam.
2. The bed Is at an equilibrium temperature. Steam
condenses or water evaporates, depending on
whether the sensible heat of the steam will supply
the latent heat required by the organic compound.
-------
o
I
Set up
Initial
bed con-
ditions.
Set up gas
Inlet
condltlons.
Update time
For I'th segment
calculate total
nols of organic
uo enthalpy H of
gas and carbon.
Set gas
temperature
plus
composition.
Update cumulative
suns. Sum remainin
organlcs.
Calculate
latent
heat at
Polanyl
value.
Adjust
enthalpy
Set
By enthalpy calculate
new bed temperature Tj
Vaoor pressure of
carbon at bed temperature
Tj and concentration u^
Set eoulllbrlum bed
temperature to 212°F
Yes
Calculate
new trial
bed
content
"9
New
value
within
factor
of 2
Figure D-3 Logic Diagram for Steam-Regeneration
-------
vapor
pressure
<5
Vapor
pressure
>760
Trial * error
calculation of
equllIbrlum bed
temperature T;
Bed
water
sufficient
to lower
to
;
Steam
sufficient
to raise
T, to
T?
Set high
limit
to ui
Condense
all steam
adjust
enthalpy Ti
Total
organic*
thalpy steam
Figure D-4 Logic Diagram for Steam-Regeneration, Figure D-3 continued
o
I
tn
-------
D-16
3. The bed is dry and above the equilibrium
temperature. For this case, stripping pro-
ceeds like the gas stripping case.
The equilibrium temperature is the temperature at which
the organic vapor pressure and the steam total one atmosphere,
The previously noted restrictions and assumptions still
apply with the following additions:
1. The program is written specifically for steam
as regenerating agent. Other fluids would
require minor program changes.
2. There is assumed to be no interaction between
the organic compound and the steam. In partic-
ular, there is no displacement effect where
the steam will "salt out" the organic. If
displacement occurs, the effect would be to
lower the steam requirement.
3. The latent heat of adsorbing water on carbon
1s small. The program ignores the latent heat
of wetting and considers the water vapor pressure
to be equal to that of pure fluid.
4. The latent heat of evaporation of water is
constant with temperature. This requires the
heat capacity of steam and water to be the
same. Although steam has a heat capacity about
half of that of water, this effect should be
small because the majority of the heat is
provided by the latent heat.
-------
Appendix E
Sample Calculations
Heat of Adsorption
(from pape 4-31)
The following demonstrates the procedure for calcu-
lating the heat of adsorption using the Clauslus Clayeyron
equation
In P - + k (1)
The data for making the calculations were selected from
Table 4-IX for w « 0.30 cm'liq/g . When the pressure data
for the three temperatures -9°F (250°K), 77°F (298°K) and
170°F (350°K) are substituted into Equation 1, the three
following equations are obtained which can now be solved
simultaneously in pairs:
at -9°F, In 2.3 -^ + k (2)
2x250
at 77°F, In 38 + k (3)
2x298
at 170°F, In 340 « -^L- + k (4)
2x350
0.833 » 2.000 x 10'J AH + k (2)
3.638 - 1.678 x 10'3 AH + k (3)
5.830 - 1.428 x 10"J AH + k (4)
By subtracting Equation 2 from 3
2.805 « -0.322 x 10'3 AH; AH -8,710 cal/mol
k - 18.2
By subtracting Equation 3 from 4
2.192 - -0.250 x 10'3 AH; AH - -8,760 cal/mol
k - 18.3
If a generalized adsorption curve 1s available for the
carbon being considered, an estimate of AH can be made with
knowledge of only the physical properties of the orqanic
vapor. See Potential Theory Equations, Chapter 4, for dis-
cussion.
-------
E-2
To demonstrate the procedure generalized adsorption
curve of Figure 4-10 (or BPL II curve of Figure 4-12) was
selected and the calculations carried out for butane at
u « 0.25 cm3Hq/g.
From the curve at w » 0.25 cm'liq/g, A « 6.75; or
6.75 ' [T/Vm] log [p0/p] (5)
By substituting two values of T and the corresponding p0 into
Equation 5, two p values can now be calculated. The two T
and p values are sufficient data to calculate AH with Equa-
tion 1.
For the calculations T * 298°K and 350°K were selected.
The corresponding p0 are 1820 and 7000 mm of Hg. Vm « 96.2*
cm'/mol. The pair of equations are as follows
at 298°K, 6.75 « [298/96.2] log [1820/p] (5)
at 350°K, 6.75 « [350/96.2] log [7000/p] (7)
at 298°K p « 11.7 mm of Hg
at 350°K p - 97.7 mm of Hg
The above substituted Into Equation 1 give
In 11.7 - -^L_ + k (8)
2x298 '
In 97.7 « -A2 + k (9)
2x350 '
The above pair of equations solved simultaneously gives
AH « -8,500 cal/mol
k - 16.9 (ave)
-------
E-3
Free Energy of Adsorption
Calculation of AF for to « 0.10 cmsl1q/g in Table 4-12
using p0 and f0 in equations below at 100°, 150°, 200° and
250°F.
AF « -RT In [p0/p]
AF « -RT In [f0/p]
Here R 1.98 2 2.0 cal/(°C x mol)
(1)
(2)
To calculate AF for u » 0.1 cm3liq/g in Table 4-12
the following values for T, p0 and p, Table E-I below were
used in Equation 1 above.
Table E-I Data Used for Calculating AF in Table 4-12
Temperature
oF T
100
150
200
250
311
339
366
394
P0, atm mm of Hg atm
13.0
23.0
38.0
60.0
23.5
50
87
155
0.0309
0.0658
0.114
0.204
To recalculate AF using fugacity instead of pressure,
only f0 need be considered since at the low vapor pressures
under consideration f « p. The fugacity f0 for propane
liquid can be obtained approximately by using van der Waals'
Equation of State, Equation 3 below, and Equation 4 based on
Equation 3.
cv~b]
RT
(3)
In f,
In
In Equation 4, a_ is a function
between molecules and b is the
of the vapor in its compressed
atmospheres and V in liters, a
2a
ETT
(4)
x atm/mol2
obtainable
handbooks.
of the forces of attraction
ultimate van der Waals' volume
state. When p0 is measured in
for propane is 8.66 liter2
and b_ is 0.0844 liters/mol. These constants are
for many vapors from organic and physical chemistry
Here R 0.082 liters/(°C x mol).
-------
E-4
With appropriate substitutions of p« and T from Table
E-l into Equation 3, the following numerical values were
calculated for V.
JL V, 1/mol
311 1.60
339 0.910
366 0.450
394 0.198
By substituting the above V and other appropriate
values for T, a_ and b_ Into Equation 4» the following numer-
ical values were calculated for f0.
T f0, atm
311 12.0
339 18.8
366 26.8
394 39.4
With above numerical value of f« and other appropriate
values for T and p substituted Into Equation 2, the AF as
given in Table E-IIwere calculated.
Table E-II AF Based on p0 and f0
AF. cal/mol
Po
311 3,760 3,710
339 3,970 3,830
366 4,250 3,960
394 4,480 4,140
-------
E-5
Adsorption Zone
(from page 4-48)
The adsorption zone length, L2, and the mean adsorptive
capacity uz of the adsorption zone are calculated for the
vapor distribution curve given in Figure 4-15 according to
the following procedure from data derived from the effluent
concentration curve given in Figure 4-14 and additional data
given below. The adsorption data below and the curve in
Figure 4-14 were obtained from Lockheed (1966) Run Number
119 for Barnebey Cheney AC carbon. This carbon is similar
to SXA at A « 17.2 and larger.
Adsorbent
Mesh size
Vapor
T
P
F
C1
W
D
AC
L
b)
A
Barnebey Cheney AC
28 to 60
Butane
43.8°C; 317°K
5 lb/in2 absolute
0.223 1/min at P « 5 lb/1n* abs.
66.8 ppm at P - 5 lb/in2 abs.
0.488 g
0.8 cm
0.502 cm2
2.4 cm
2.98 x 10"2cmjliq/g
17.2
By a summing-up process the amount of butane penetration
can be calculated from the effluent concentration curve in
Figure 4-14. When the summation is carried from C * 0.01 Ci
to C » Ci, the penetrated amount is equivalent to the amount
adsorbed in the adsorption zone. The summation as given
below was 1n At increments of 50 min.
600-650
650-700
700-750
750-800
800-850
850-900
900-950
950-975
Mean C (C). ppm
1
3
11
27
49
59
63
65/2
245
ZAtC - 50 x 245 " 12,200
-------
E-6
To convert ZAtC to butane weight penetrated, 1t 1s
multiplied by
ZAtC x 1.69 x 10"7 « 0.00206 g
Weight of butane entering carbon bed between t - 600
and 975 m1n 1s,
[975-600] x Cf x 1.69 x 10'7 « 0.00418 g
Residual capacity or amount adsorbed 1n time Interval
t " 600 to 975 min 1s,
0.00418-0.00206 - 0.00212 g
The total amount of butane the 0.488 g of carbon can
adsorb 1s the amount adsorbed in time t * 0 to 600.
600 x Ci x 1.69 x TO'7 - 0.00677
plus residual capacity « 0.00212
total amount « 0.00889 g
The adsorptlve capacity of the carbon Is,
0.00889/W » 0.0182 g/g; 0.0302 cm3 I1q/g
The amount adsorbed 1n the saturated bed length Ls 1s
equal to the capacity of the total bed minus the residual
capacity and amount adsorbed 1n the adsorption zone. I.e.,
0.00889 - [0.00206 + 0.00212] 0.00471 g
The saturated bed length 1s then
0.00471 L , ,
i . - x - « 1.27 cm
5 0.0182 W
The adsorption zone length Is
L . 2.40-1.27 « 1.13 cm
-------
E-7
The adsorptive capacity of the saturated bed 1s
0.00889
w . . , Q.00738 g/cm1
5 LAC
The mean adsorptive capacity of the adsorption zone
1s
0.00206
« ~j :
LZAC
0.00363 g/cnr
To check the self consistancy of the above numerical
values, they may be substituted Into Equation 4-23.
If correct, t& should be equal to 600 m1n. Cj substituted
Into Equation 4-23 1s first converted from ppm at reduced
pressure to g/1, as follows:
p 97O M I ft 6
Ci 66.8 ppm 5.06 X 10'5 g/1
tb
0.502
*b ' 0.223 « 5.06 x 10" * ^'l^ ^,,j
tb 600 min
-------
E-8
Calculation of Lc at Different
(from page 4-52)
Using Equation 27 of Chapter 4, given below, Lc values
L and the
(27)
were calculated at different Cb/Ci using ws , uz,
effluent concentration curve in Figure 4-14.
1-7-
wsAc
re
Ca /»<««
C
F
A
to
to
L
f
i
c
s
z
z
66
= 0.
= 0.
- 0.
- 0.
« 1.
P
.5 ppm
223 1/min
502 cm2
00738 g/cm
00363 g/cm
13 cm
273 M TO"6
at
3
3
5
of
of
7
lb/1n2 pres
carbon
carbon
^ v in-*
sure
where P 5 lb/in2, T - 317°K and M 58 g/mol. The time
interval [tb-t-j] is measured on the effluent concentration
curve from C » 0.01 C^ to C « Ci. It is related to Cfc/Ci as
given in the following table.
0.02
0.06
0.17
0.41
0.50
0.75
0.89
0.94
0.96
0.98
1.00
625-600
675-600
725-600
775-600
790-600
825-600
875-600
925-600
975-600
1025-600
1075-600
The quantity
0.57 cm
-------
E-9
The following 1s a summary of the calculations according to
Equation 4-27.
t [when
0.01
0.02
0.06
0.17
0.41
0.50
0.75
0.89
0.94
0.96
0.98
1.00
0
25
75
125
175
190
225
275
325
375
425
475
WSAC cn
0.0
-0.08
-0.23
-0.38
-0.53
-0.58
-0.69
-0.84
-0.99
-1.14
-1.30
-1.45
i
LC. ci
0.57
0.49
0.34
0.19
0.04
-0.01
-0.12
-0.27
-0.42
-0.57
-0.73
-0.88
To calculate service time, t, when Lc 1s known at any
CjFf
0.01
°-°0738 * °-502 [2.40-0.57]
66.5 x 0.223 x 7.6 x 10'7
600 m1n,
t [when Cb - Cj] » 327 [2.40 + 0.88] 1070 m1n,
-------
E-10
Calculation of L2 and LC» Klotz Equation
(from page 4-57}
The following Is a sample calculation for 4-methyl-2-
pentanone, using Klotz Equation 4-28.
L ^.' ^ PpUmP] * f
2 T" L P J [f
u °-67 ,
Ji_ log
|pDv
+ 2.30 k Um log
The following conditions are fixed:
Dp = 0.35 cm; 4 to 10 mesh
IT = 100 ft/min; Ura is measured 1n cm/sec
p for air « 1.20 x 10-J g/cm3at 77°F
y for air 1.83 x 10'" g/(cm x sec) at 77°F
= 100
log C-t/Ck » 2
T * 77°F; 298°K
k * 0.0035
DP
e, the void volume between carbon particles, varies be-
tween 0.3 to 0.4. When e « 0.4, a » 3.6/Dp.
U = Um [60/30.5] e2/3 1.066 Um
Un,0'*1 « 0.97 U0'*1
In Equation 4-28
°-1'1 0.97 U°-%1 x [1.20 x 10-s]9-*1
yj [1.83X 10-]'." " 2-095 U<
fu I °'67
[j] ' °'284
log [C^/Cb] 2
Lz - 0.638 x 2.095 x 0.284 x 2 Dp Dp °-»Um° *» Dv'0-'1
* 0.008 Umx 2
-------
E-ll
0.80 Dp1«»1Um°-*1 (1/DV)°-67 + 0.016 U
m
When the numerical values are substituted for DD, Um and
Dv. (Dv - 0.070 cm2/sec) H
L2 « 7.2 + 1.6 » 8.8 cm; 3.5 1n.
Lc 8.8 x 0.77 6.9 cm; 2.7 in.
-------
E-12
Calculations for Adsorbed-Vapor Profile
as Presented 1n Figure 4-18
Conditions for Adsorption of Ternary Solvent Mixture
Total concentration
2-Ethoxyethyl acetate
Toluene
Propanone
Solvent properties
-
-
-
500
50
181
268
ppm
M
H
H
*
>
1.
4.
3.
68
25
96
x
x
X
1
1
1
o-
o-
o-
5
5
5
lb/ft
s
Symbol
M
0)
C0 ppm
2-Ethoxyethyl acetate
Toluene
Propanone
Total vapor-air flow, F
Vapor-air velocity, U
Carbon bed area, Ac
Carbon particle size, Dp
Carbon density
Service time, t^
Break concentration, Cj,
Vapor-air temperature, T
(1) Molar volume at 25°C
E
T
P
132
92
58
135
106
73
163
118
74
3,400
37,000
290,000
- 3,000 ftVmin
110 ft/mi n
- 3,930 in2
- 4 to 10 mesh; 0.35 cm
- 0.50 g/cm3; 0.018 lb/1nj
- 8 hr
- 0.01 C
- 25°C;
Adsorptive capacity at influent concentration
E
T
P
A - T/Vm log [C0/Ci]
A « 1.83 log [3400/50] - 3.36
A » 2.52 log [37,000/181] - 5.81
A - 4.03 log [290,000/268] « 12.1
From the BPL generalized adsorption curve in Figure 4-19
the us values given below were determined.
E
T
P
0.31 cm3liq/g
0.23 cm3Hq/g
0.074 cms
-------
E-13
To convert above
-------
E-14
Amount adsorbed In Zones 1 , 3 and 5
E
T
P
24.2 -
61.2 -
57.0 -
14.8 - 9.4 Ib
9.6 - 51.6 Ib
2.8 54.2 Ib
Length of Zones 1, 3 and 5
E 9.4/17.8 » 0.5 1n Zone 1
T 51.6/12.7 « 4.1 1n Zone 3
P 54. 2/ 4.1 13.2 1n Zone 5
Shape of adsorption zone profile 1s assumed to be Iden-
tical to the vapor-phase curve as calculated from log [C-j/C]
1n Equation 4*29. In these calculations
L » kglog [u>s/u]
^w 0.01
L 0 when o>s/u « 1.0 and
L L2 when ws/w 100.
-------
E- 15
Calculations for Adsorbed-Vapor Profile
as Presented in Figure 4-19
Conditions are the same as for adsorbed-vapor profile
presented 1n Figure 4-18 except coadsorptlon 1s taken Into
consideration.
Equations for calculating coadsorptlon
E CT « x-j CQI [wt]
T C2 " X2 CQ2 [o»t]
P C3 X3 C03
C-j , Cg and C3 are the equilibrium adsorption vapor
pressures of E, T and P, respectively. X] , Xj and X3 are
the mole fractions of adsorbed E, T and P. CQJ 1s the cal-
culated equilibrium vapor pressure of E when the weight of
adsorbed E 1s assumed equal to the sum of the actual adsorbed
weights of E, T and P. This 1s also true for C02 and CQS.
In these calculations C] , G£ and C3 are always known for the
saturated carbon zones. CQI , C02 and CQ3 were estimated
from the generalized adsorption curve for BPL carbon In Fig-
ure 4-12. By tr1al-and-error, CQ-J , C()2 and CQS are calculated
at different [ot] until XT + X2 + X3 * 1.0. To simplify cal-
culations, [wt] cm'liq/g was not corrected for differences 1n
liquid densities of E, T and P. For Zone 1 of Figure 4-19,
the [ut] that gives XT + X2 + X3 « 1.0 1s 0.32 cm'Hq/g at
A 3.28.
The following sets of calculations give the steps 1n
determining XT, X2 and X3 and the amount of E, T and P ad-
sorbed per Inch of bed length.
Adsorption potential equations
A - [T/VJ log [Co/Of]
E A 1.83 log [3,400/C01]
T A « 2.52 log [37,000/C02]
P A « 4.03 log [290,000/CQ3]
-------
E-16
C01 C02 and C03 for Zone 1
At A 3.28, found by tMal-and-error:
E 3.28/1.83 » log [3,400/C01] - 1.79
T 3.28/2.52 log [37,000/C02] 1.30
P 3.28/4.03 log [290,000/C03] 0.814
C01 - 55 ppm
Cg2 " 11860 ppm
C03 " 44,500 ppm
XT, X2 and X3 for Zone 1
X1 - 50/55 - 0.910
X2 « 181/1,860 - 0.097
X3 268/44,500 0.006
1.013
Pounds of E. T and P adsorbed per Inch of bed length
1n Zone 1
Mol fractions converted to liquid volume fractions,
[XVm].
L1g vol fraction
E 0.910 X 163 148 0.925
T 0.097 x 118 » 11.4 0.071
P 0.006 x 74 - 0.44 0.0027
160 0.999
Liquid volume fraction converted to lb/1n.
CD- 0.018 [I1q vol fraction] [wtl [M/Vm] Ac Ib/ln
-------
E-17
E 0.018 x 0.925 x 0.32 x 0.81 x 3,930 « 16.9 Ib/in
T 0.071 0.78 - 1.2 Ib/in
P 0.0027 0.78 - 0.05 Ib/in
Total 18.1
Pounds Of T and P adsorbed per Inch of bed length 1n
Zone 3 at Influent concentrations, first approximation
T C2 XgCo2 [wt] * 181 PPm
P 63 » XsCos [wtl " 268 PPm
By tr1al-and-error, X2 + X3 - 1*0 when [wtl " 0.227 cm*
11q/g at A 5.8.
T XT -
P X2 -
Mol fraction converted to liquid volume fraction and
lb/1n bed length.
T 0.977 x 118 115
P 0.025 x 74 - 1.85
_
T us " 0.018 x 0.983 x 0.227 x 0.78 x 3,930 " 12.3 lb/1n
P ws 0.0158 0.78
Rate of desorption of T and P in Zone 2. second
approximation
The 12.3 Ib/in of T and 0.20 lb/1n of P are partially
desorbed by the adsorption front of E moving at the rate of
FCi/[us for E], 1n/m1n.
Lio vol fraction
-------
E-18
3,000 x 1.68 x 10'5/16.9 » 2.98 x 10"J 1n/m1n
T 12.3 - 1.2 » 11.1 Ib/in desorbed
P 0.20 - 0.05 0.15 lb/1n desorbed
T 11.1 x 2.98 x lO'3 3.31 x 10'2 Ib/min
P 0.15 x 2.98 x TO'3 « 0.45 x 10"3 Ib/min
Concentration of desorbed vapors
T 3.31 x 10'2/3,000 - 1.10 x 10"5 lb/ft3
P 0.45 x 10-3/3,000 » 0.15 x 10'6 lb/fts
T [1.10 x 10-5 x 392/92] 10* « 47, ppm
P [0.15 x 10-« x 392/58] 106 - J[ ppm
Concentration of vapors 1n Zone 3, second approximation
T 181 + 47 « 228 ppm
P 268 + 1 « 269 ppm
Pounds T and P adsorbed 1n Zone 3. second approximation
T C2 - X2C02 C"t3 " 228
P 03 - X3CQ3 [wt] " 269 ppm
By tr1al-and-error, X2 + X3 - 1 .0 when [ut] « 0.235 cm*
I1q/g at A 5.55.
Liq vol fraction
T XT 0.975 0.987
P X2 - 0.022 0.0138
0.997 1.008
T o»s 0.018 x 0.987 x 0.235 x 0.78 x 3,930 12.8 lb/1n
p w$ . 0.0138 0.78 « 0.18 lb/1n
Rate of desorotlon of T and P In Zone 2. third
approximation
T 2.98 x 10"' 1n/m1n [12.8 - 1.2] 3.46 x 10'2 Ib/min
-------
E-19
P 2.98 x 10"3 1n/m1n [0.18 - 0.05] 0.39 x 10*2 Ib/min
Concentration of desorbed vapors
T 3.46 x 10"2/3,000 » 1.15 x 10"s lb/ft3; 49 ppm
P 0.39 x 10"2/3,000 . 0.13 x 10-' lb/ft3; 1 ppm
Ctincentfation of vapors In Zone 3, third approximation
T 181 + 49 230 ppm
P 268 + 1 « 269 ppm
The third approximation made very little change in vapor
concentration; the values for cus on the second approximation
will be used.
Pounds of P adsorbed per inch of bed length in Zone 5
at influent concentration, first approximation
At 3 268 ppm, A » 12.2
A - 4.03 log [290,000/268] « 12.2
s » 0.083 or 4.60 lb/1n
-------
E-20
Pounds of P adsorbed in Zone 6
From Figure 4-17, Lz is 2.9 in. at U « 110 ft/min and
V 73 cm'/mol. From Equation 4-26 and also Page 4-54,
0.77
ws is 4.60 Ib/in and by the above equation, wz is 1.06 Ib/in
average capacity. Total amount P adsorbed 1n Zone 6 is
2.9 x 1.06 * 3.10 Ib
In Zone 2, E is being adsorbed while T and P are desorbed.
The changes taking place are as follows;
E _ l~ws increases from zero to 16.9 lb/1n
j_C-j decreases from 50 to zero ppm
T - f^s decreases from 12.8 to 1.2 lb/1n
i C2 increases from 181 to 230 ppm
P _ fws increases from 0.18 to 0.20 lb/1n
63 increases from 268 to 269 ppm
To estimate the quantities of E, T and P adsorbed in
Zone 2, several simplifying assumptions were made. It was
assumed that Lz is determined by the strongest adsorbed vapor
in this case E, and that Lz is the same in adsorption of mix-*
tures as when E is adsorbed singly. The second assumption 1s
that the factor
fill.- -iii-Tl
0.77
from Equation 4-26 applies to vapor E. The third assumption
is that for T and P
0.23
ws
Pounds E adsorbed in Zone 2
From Figure 4-17, Lz is 3.6 in. at U 110 ft/m1n and
» 135 cmVmol. Using the first factor above w, « 3.9 lb/1n
erage when us 16.9 lb/1n. The total amount E adsorbed 1n
-------
E-21
Zone 2 is then
3.6 x 3.9 « 14.0 Ib
Pounds T adsorbed in Zone 2
Using the second factor above, wz 9.86 lb/1n average
when b)S » 12.0 lb/1n. The total amount of T adsorbed in
Zone 2 1s then
3.6 x 9.86 « 35.5 Ib
Pounds P adsorbed In Zone 2
Using the second factor above, «z « 0.14 lb/1n average
when ws 0.18 lb/1n. The total amount of P adsorbed in
Zone 2 1s then
3.6 x 0.14 - 0.50 Ib
The situation 1s analogous 1n Zone 4. Lz 1s determined
by vapor T and is 3.3 in. when U 110 ft/m1n and V » 106
cm'/mol.
Pounds T adsorbed in Zone 4
wz 2.95 lb/1n average when us » 12,8 lb/1n, and total
amount adsorbed 1s
3.3 x 2.95 - 9.7 Ib
Pounds P adsorbed in Zone 4
wz 3.55 lb/1n average when ws « 4.60 lb/1n, and total
amount adsorbed is
3.3 x 3.55 - 11.7 Ib
Profile of adsorbed E
Total amount adsorbed 24.2 Ib*
Amount in Zone 2 14.0
Amount in Zone 1 10.2 Ib
Length of Zone 1
[10.2/16.9] 0.60 in
(1) See page E-13
-------
E-22
Length of Zone 2 3.6 1n
Profile of adsorbed T
Total amount adsorbed 61 9 IK
Amount In Zone 1 ID
[1.2 x 0.60]
Amount 1n Zone 2
Amount 1n Zone 4
Amount in Zone 3
Length of Zone 3
[15.3/12.8] 1.2 in
Length of Zone 4 3.3 1n
Profile of adsorbed P
Total amount adsorbed c7 « iu
Amount in Zone 1 t>/'° lb
[0.05 x 0.60] Ot03
Amount in Zone 2 0.50
Amount in Zone 3
[0.18 x 1.2]
Amount in Zone 4
Amount in Zone 6
Amount in Zone 5
Length of Zone 5
[41.5/4.60] 9.0 in
Length of Zone 6 2.9 in
Total length of carbon bed
Zone L, 1n
1
2
3
4
5
6
Total
The shape of the adsorption front profile for E 1n Zone
2, T in Zone 4 and P in Zone 6 1s assumed to be identical tn
the vapor-phase curve as calculated from log [Ci/C] In
(1) See page E-13
-------
E-23
Equation 4-28. In these calculations
n b) " 01 s
L » k log [ws/&>]
J w « 0.01 u>s,
L « 0 when ws/u » 1.0 and
L - Lz when ws/w 100.
For the desorptlon profiles of T and P 1n Zone 2 and P
1n Zone 4,
-jw 0.99 u>s
L -k log Cws/(us-w^)] + k log Cws/(ws"w^
U U>{
Here uj Is the amount adsorbed per Inch of bed length In the
previous zone. At
CD 0.99 ws, L Lz
-------
E-24
Estimate of Secondary Adsorber Size for Gas
Regeneration with Secondary Adsorption System
The following is a sample calculation for estimating
the size of the secondary adsorber for a carbon-resorb
system utilizing gas regeneration and recovery of desorbed
solvent or pollutant by means of a secondary adsorber, page
6-40. The bed is to be sized to give a steam-to-solvent
ratio of 6.0.
Bases for Calculations
Primary Adsorber Effluent
Pollutant
F
Ce
t
4-methy1-2-pentanone
306 ft3/min (at 298°l
4,000 ppm; 1.02 x 10'
302°F; 423°K
120 min
lb/ft3
Secondary Adsorber Influent
Same as above except T 298PK
Secondary Adsorber
Carbon «
Mesh size «
Density (d)
L
BPL V Type
4 to 10; Dp 0.35
31.2 lb/ft3; 2.6 Ib/in. per ft2
20 in.
Bed length L of 20 in. was selected as the fixed bed
dimension because the preliminary calculation showed that
the bed diameter would be near 24 in. A 20 in. bed length
is a reasonable dimension with a 24 in. diameter. Also,
regeneration calculations that had already been made apply
most accurately to 20 in. bed lengths.
The equation used for the estimate is Equation 4-23,
reproduced below:
wzLz]
-------
E-25
The above equation was modified for this application and
has the form
AcdAu
TcT
[Ls + 0.23 Lz]
where
t
L
d
AC
Ah)
U)Z
120 m1n, regeneration time
Ls + Lz, 1n.
2.6 lb/1n. per ft2
bed area, ft2
b)s-h)r, operating capacity, Ib/lb
0.23 Ao>
With the above known values substituted Into the above
equation, It now has the form
14.1 » AcAw[Ls + 0.23 Lz]
To determine Ao for a steam-to-solvent ratio of 6.0, 1t Is
first necessary to determine u>s, using Equation 4-19
and Curve V of Figure 4-12. In Equation 4-19 V » Vm » 140
cm'llq/mol, po 9470 ppm and p « 4000 ppm. A 0.8 and from
Curve V, >r that will give a steam-to-solvent ratio of 6.0,
according to the following equation
Ib steam/lb carbon
6.0.
At wr 0.17, Ib steam/lb carbon 1s 0.85 which qlves a steam-
to-solvent ratio of 6.0 at Aw » 0.14 Ib/lb. Now
100 - Ac [Ls + 0.23 L2].
Lz depends on U F/AC. From Figure 4-17,Lz can be deter-
mined for various U at Dp 0.35 cm and V 125 cmMlq/mol
for 4-methyl-2-pentanone. The conditions of the above
equation are satisfied when
U 54.5 ft/m1n
Lz « 2.5 1n.
Ac - 5.5 ft2
Lc - 17.5 1n.
-------
E-26
The volume of carbon 1s 9.2 ft3 and weight 1s 290 Ib.
For the 37.5 Ib solvent adsorbed by the 290 Ib, the
overall operating capacity Is 0.13 Ib/lb compared to 0.14
Ib/lb where the adsorption 1s more correctly distributed
over the saturated and adsorption zone bed lengths.
-------
E-27
Calculations on Carbon-Resorb with Gas
Regeneration, Condensation and Vapor Recycle
These calculations estimate the number of cycles to
attain steady state, and, after the steady state is attained,
estimate the flow rates and concentrations to the on-stream
adsorber and to the condenser and the weight of vapor re-
cycled when condenser is operated at 32°F. For purpose of
calculations refer to page 6-44.
Fixed Parameters
Pollutant or solvent vapor - 4-methyl-2-pentanone
Carbon type - BPLV
Carbon mesh size - 4 to 10 U.S. std sieve
Carbon density - 31.2 Ib/ft1
tbi service time 82 hr
t, regeneration time « 120 min
Ac 27.2 ft2
Lt 21.3 in.
Weight of carbon for each inch of bed depth is 71 lb. The
regeneration starts on the 80th hr of service time and term-
inates on the 82nd.
First Cycle Adsorption Phase
F to adsorber « 3,000 ft'/min .
Ci to adsorber - 10 ppm; 2.55 x 10'* Ib/ft'
T 77°F; 298°K
First Cycle Regeneration Phase
F to condenser - 306 ft3/m1n P 77°F
Ce to condenser 4000 ppm; 1.02 x 10"' Ib/ft
Saturation vapor concentration at 32°F for 4-methyl-2-
pentanone is 0.44 x 10"' Ib/ft1.
Amount removed by the condenser, at 100* efficiency,
1s:
Concentration in gas stream at 32°F 1.11 x 10"3 Ib/ft3
Saturation concentration at 32°F » 0.44 x 10*'
Amount condensed 0.67 x 10'* Ib/ft3,
-------
E-28
306 [273/298] x 0.67 x 10'3 - 0.188 Ib/min,
120 m1n x 0.188 22.6 Ib.
Since 37.5 Ib must be condensed, the process has not come
to a steady state.
The total weight recycled is
306 [273/298] x 120 x 0.44 X TO"3 - 14.7 Ib.
Second Cycle Adsorption Phase
The rate of recycle to the Impure airstream (during
regeneration) is
306 [273/298] x 0.44 x 10'3 0.123 Ib/min.
The rate of outside vapor input to the impure airstream
is
3000 x 10 x 10'6 [100/392] » 0.0076 Ib/min,
where 392 is the molar volume of air in ft3 at 77°F and 100
is the molar weight of 4-methyl-2-pentanone. The total
vapor input rate (during regeneration) is
0.1230 + 0.0076 « 0.131 Ib/min,
The total flow rate to the adsorber (during regeneration)
is
3000 + 306 - 3306 ft3/min.
The Influent concentration (during regeneration) is
[0.131/3306] x [392/100] X 10* 155 ppm.
Second Cycle Regeneration Phase
It reguires a slightly larger amount of regenerating
gas to regenerate the carbon bed on the second cycle than
on the first. The new figure for F to condenser is 313 ft3/
min at 77°F.
The amount desorbed is 37.5 Ib brought in from the out-
side and the 14.7 Ib recycled. The concentration Ce to con-
denser is
-------
E-29
[37.5 + 14.7] [313 x 120] 1.39 x 10" lb/ft»; 5440 ppm
Amount removed by the condenser, at 10035 efficiency,
Is:
Concentration 1n qas stream at 32°F 1.52 x 10"s lb/fts
Saturation concentration at 32°F » 0.44 x 10-J
Amount condensed « 1.08 x 10" Ib/ft*,
313 [273/298] x 1.08 x 10"s 0.310 Ib/m1n,
120 m1n x 0.310 - 37.1 1b.
Since 37.5 1b must be condensed, the process has virtually
come to a steady state. The total weight recycled 1s
313 [273/298] x 120 x 0.44 x 10" 15.1 lb.
Third Cycle Adsorption Phase
The rate of recycle to the Impure alrstream (during
regeneration) 1s
313 (273/298] x 0.44 x 10" 0.126 Ib/m1n,
The total vapor Input rate (during regeneration) 1s
0.126 + 0.0076 0.134 Ib/m1n
The total flow rate to the adsorber (during regeneration)
1s
3000 + 313 - 3313 ft3/m1n.
The Influent concentration (during regeneration) 1s
[0.134/3313] x [392/100] x 10* - 158 ppm
Third Cycle Regeneration Phase
The required Increase 1n the amount of regenerating gas
1s nil. F to condenser 313 ft'/m1n at 77PF.
The amount desorbed 1s 37.5 lb brought 1n from the out-
side and 15.1 lb recycled. The concentration Ce to conden-
ser 1s
-------
E-30
[37.5 + 15.1] [313 x 120] - 1.40 x 10'3 lb/ftj; 5500 ppm.
Amount removed by the condenser, at 100% efficiency,
is*
Concentration in gas stream at 32°F « 1.53 x 10'3 Ib/ft1
Saturation concentration at 32°F - 0.44 x 10"3
Amount condensed » 1.09 x 10'3 Ib/ft3
313 [273/298] x 1.09 x 10'3 - 0.312 Ib/min,
120 min x 0.312 « 37.5 Ib.
Since 37.5 Ib must be condensed, the process is at
steady state.
At steady state operation the following conditions
prevail, measured at 77°F:
F to adsorber 3313 ft3/m1n
C-| to adsorber 158 ppm
F to condenser - 313 ftVmln
Ce to condenser 5500 ppm
Weight of vapor
recycled/cycle 15.1 Ib
Weight of vapor
condensed/cycle 37.5 Ib
-------
E-31
Calculation of Service Times for
Multistage with Displacement of Beds
(from page 6-49)
These calculations are for the T. Melshime type system.
Two organic compounds, 4-methyl-2-pentanone and propanone,
are used to represent the range of pollutants that might be
encountered. Service times are calculated for three influ-
ent concentrations, 1,0, 10, and 100 ppm.
Fixed Parameters
Carbon type
Carbon mesh size
Carbon density
AC, bed area
l_t. total bed length
F, flow
d, carbon density
T, adsorption temp.
BPL V
4 to 10 U.S. std sieve
31.2 lb/fts
82 ft2
16 in.
10,000 ft'/min
2.6 lb/1n. per ft2
298'K
Equation for the Calculations
A modified form of Equation 4-23 was used in the calcu-
lations. After the first displacement of the carbon beds,
be given to the amount adsorbed in the
it is always displaced into the second
has the form
no consideration need
adsorption zone since
stage. The equation now
it.
or with fixed parameter substituted,
t « 0.341 [u»s/Ci]
Calculated Results
(1)
(2)
The following tables summarize the results of the
calculations. u>s was determined for each Ci using mathematical
term 4-19, and the generalized adsorption curve given 1n Figure
4-12.
Ci, Ib/ft'
1
10
100
4-methy1-2-pentanone
2.55 x 10-7
2.55 x 10"*
2.55 x l
-------
E-32
ppm
4-tnethy1-2-pentanone
ws, Ib/lb t, hr
1
10
100
0.11
0.16
0.20
2450
360
45
propanone
ws. Ib/lb
0.0047
0.013
0.034
t, hr
180
50
13
-------
Appendix F
Literature Cited
Abeles, P.O. and Gahagen, H.E., "Abscission: The Role of
Ethylene, Ethylene Analogues, Carbon Monoxide and
Oxyqen", Plant Physiol 43, 1253-1258 (1968),
ACGIH, "Threshold Limit Values of Airborne Contaminants and
Intended Chanqes", American Conference of Governmental
Industrial Hygienists (1970)."
AIHA, "Odor", Air Pollution Manual Part I. American Indus-
trial Hygiene Association, 14125 Prevost, Detroit,
Michigan, Cp. 11, 148, copyrinht (1960).
Altshuller.A.P., "An Evaluation of Techniques for the
Determination of Photochemical Reactivity of Orqanic
Emissions", J. A1r Pollution Control Assoc.» 16, 257
(1966).
Altshuller.A.P., et.al,, "Products and B1oloq1cal Effects
from Irradiation of Nitroqen Oxides with Hydrocarbons or
Aldehydes Under Dynamic Conditions". International Journal
of Air. Water Pollution, 1_0, 81-98 (1966).
American Document Institute, "ADI Document 2936", 1719 N.
St., N.W., Washington 6, D.C.
American Industrial Hyqiene Association, Air Pollution
Manual> Part I, "Evaluation", Am. Ind. Hyg, ASSOC. (1960).
American Industrial Hygiene Association, "Hygienic Guide
Series", Am. Ind. Hyq. Assoc. J.t January (1971).
Anderson, R.D., et.al., "Catalytic Oxidation of Methane",
Ind. & Enq. Chem., 53, (10), 809 (1961).
Arrhenius, S., Theories of Solution. Yale University Press,
68 (1912).
ASHRAE, Handbook of Fundamentals, "Odors", Cp. 12, Am. Soc.
Heat. Refrlg. A1r-Cond. Engrs., New York, 175 (1967).
ASHRAE, "Odor Control", Guide and Data Book, Applications.
Cp. 80, 962 (1966 and 1967).
ASTM, STP-310, "Properties of Commerlcally Available De-
greasing Solvents", Am. Soc. Testing Mater. - Handbook
of Vapor Decreasing (1962).
-------
F-2
Avery, D.A. and Boiston, D.A., "The Recovery of Solvents
from Gaseous Effluents", The Chemical Engineer. January/
February (1969).
Bailor, W.C., A1r Pollution Engineering Manual FS2.300,
AP-40, Washington, D.C., 393 (1967).
Balandln, A. A., "The Theory of Heterogeneous Catalytic
Reactions, The Multiplet Hypothesis. A Model for De-
hydration Catalysis", Zeit Phys. Chem. 132t 289 (1929).
Barnebey, H.L., "Removal of Exhaust Odors from Solvent
Extraction Operation of Activated Charcoal Adsorption",
J. Air Pollution Control Assoc.. Jj5_ (4), 422 (1965).
Barr, A., "From Waste Materials: Tallow and High Protein
". Chem. Eng.. June (1966).
Barrett, E.P., Joyner, L.G. and Halenda, P.H., "The Deter-
mination of Pore Volume and Area Distributions in Porous
Substances, I. Computations from Nitrogen Isotherms",
^J. Am. Chem. Soc.. £3_. 373 (1951).
Barth, D.S., Romanovsky, J.C., Knelson, J.J., Altshuller, A. P.
and Horton, R.J.M., "Discussion", J. Air Pollution Control
Assoc.. 21_ (9), 535 (1971).
Bay Area APCD, "Source Inventory of Air Pollutant Emissions,
San Francisco Bay Area", Bay Area Pollution Control Dis-
trict, San Francisco, California (1969).
Bay Area APCD, "Regulations for the Bay Area", Air Pollution
Control District, Bay Area (1971).
Beckman Instruments, Incorporated, "Hydrocarbon Analyzer",
Bulletin P70565-1269-106F (1969).
Beeck, 0., Advances in Catalysis. 2, Academic Press, 151
(1950).
Beeck, 0., "Hydrogenation Catalysts", Discussions of Fara-
day Soc. 8. 118 (1950). "
Bendix Process Instruments Division. "Total Hydrocarbon
Analyzer", Bulletin A530SB-1070 (1970).
Berg, C. and Bradley, W.E., "Hypersorption-New Fractionating
Process", Petroleum Eng., 18. 115 (1947).
Bera. C.. "Hypersorption-A Process for Separation of Light
Gises", Gas 23 (1), 32 (1947).
Berq. D.B. and Lewandowski, R., "Trichlorofume Control Saves
$780 per Week", Chem. Process., January (1968).
-------
F-3
Berzelius, "On the Progress of Physical Sciences", report
to Swedish Academy of Sciences. Mar. 31 (1835).
Brodski, A.M.. et.al., "Quantitative Characterization of the
Reliability of Chemical Reaction Mechanisms". Dold. Akad.
Nauk SSSR. Proceedings of the Academy of Science of the
USSR, 174 (4). 865 (1967).
Brunauer, S., Emmett. P.M. and Teller, E., "Adsorption of
Gases in Multimolecular Layers", J. Am. Chem. Soc.. 60.
309 (1938). "
Brunauer, S., Emmett, P.H. and Teller, E., "On the Theory
of Van der Waals Adsorption of Gases", J. Am. Chem. Soc.
62, 1723 (1940). ~
Bruno, M.H., "Printing Processes", in Kirk-Othmer Encvclo-
tedia of Chemical Tecl
ork, J£, 494 (1968).
v p * p (*»ii*^j iw«*^«*^w^ p i »^ »^ _. _v^ _w_» _ * * * * »j »
pedia of Chemical Technology. Interscience Pub., New
YT"
Burg, S.P. and Berg, E.A., "Molecular Requirements for the
Biological Activity of Ethylene", Plant Physio! 42. 144-
152(1967). - --
California, "Emission Inventories", California Air Resources
Bojrrd, the Resources Agency, November (
Carter, J.W., "Adsorption Processes", Chem. and Process Eng.
37,, August (1966). "
C.E.P., "Fluid Flow Through Packed Columns", Chem. Eng.
Progr. 48 (2), 89, February (1952).
Committee on Hazardous Materials, "Evaluation of the Hazard
of Bulk Water Transportation of Industrial Chemicals",
National Academy of Sciences. Washington, D.C. (1970).
Conn, G.K. and Avery, D.G., Infrared Methods. Academic
Press (1960). -
Conrad, E., Interview at Haynie Products, 5010 York Road,
Baltimore, Maryland (1971).
Cooper, B.J., "Platinum-Carbon Catalysts with Molecular
Sieve Properties", Platinum Metals Review 14 (4), 133,
October (1970).
Cooper, J.C. and Cunniff, F.T., "Control of Solvent Emissions'
Metropo'li tan Engineers Council on Air Resources. New York,
N . Y . 11967).
Copley Report, "National Survey of the Odor Problem",
National Air Pollution Control Administration. Coolev
International Corp., Contract CPA Ul>-b9-70 (1970).
-------
F-4
Corrigan, I.E., "Catalysis and Absorption", Chem. Eng. 61,
236 (1954). """
Cowan, J.C., "Soybeans", 1n K1rk-0thmer Encyclopedia of
Chemical 'Technology. Intersclence PUD., hew Vork, 18,
599 11969).
Crocker, W., Hltchock, A.E. and Zimmerman, P.M., "Similari-
ties 1n the Effects of Ethylene and the Plant Auxins",
Contribution from the Boyce Thompson Institute. 7 (3),
""
Davis Instrument Division, "Toxldty Limits and Detector
Methods", Bulletin 7020763 (1963).
Davis Instrument Division, "Flame Ion1zat1on Meter", Bulletin
11-65-2 (1965). -
Davis Instrument Division, "Davis Hallde Meter", Bulletin
P/N 11-9000 (1971). -
Davlson Chemical Division, W.R. Grace and Co., "Davlson
Molecular Sieves", Sales Catalog. 101 North Charles St.,
Baltimore, Md.
Debye, P., "Van der Waals Cohesion Forces", Physlk. 2.. 21,
178 (1920). -
Debye, P., "Molecular Forces and Their Electrical Interpre-
tation", Physlk. Z. (Journal of Physics), 22,, 302 (1921).
D'Imperlo, J., "Rubber-Compounding Equipment", A1r Pollution
Engineering Manual . Danlelson, J.A., ed., U.s. uept. of
Health, Education and Welfare, 999-AP-40, 375 (1967).
Dmuchovsky, B., Freerks, M.C. and Zrenty, F., "Metal Oxide
Activities In the Oxidation of Ethylene", J. Catalysis
£, 577 (1965).
Dobler, L.A., "Solvent Emissions from Stationary Sources
1n Denver", Correspondence from Denver Air Pollution
Control, Denver, Colorado (1971).
Dowden, D.A. and Reynolds, P.W., "Heterogeneous Catalysis:
Theoretical and Hydrogenatlon by Binary Alloys", J. Am.
Chem. Soc.. 242-271 (1950). "
Dowden, D.A. and Wells, D., Proceedings of the Second Inter.
national Congress on Catalysis, vol. II. Paris. Prance
-
-------
F-5
Dubinin, M.M, and Sayerina, E.t "The Porosity and Sorptive
Properties of Active Carbons", Acta. Physicochim. USSR,
£, 647 (1936). - -
Dubinin, M.M. and Timofeev, D.P., "Adsorbabi 1 i ty and Physico-
chemical Properties of Vapors, I. Adsorption of Vapors by
Active Carbons", J. Phys. Chem. (U.S.S.R.) 21. 1213
(1947). "
Dubinin, M.M., Zaverina, E.D. and Radushkevlch, L.V., "Sorp-
tion and Structure of Active Carbons, I. Adsorption of
Organic Vapors", J. Phys. Chem. (U.S.S.R.) 21. 1351 (1947).
Duhl, R.W., "Factors Affecting Recovery of Rotogravure Sol-
vents", Vulcan-Cincinnati, Incorporated (1970).
Easton, E.R., "Food Products", cp. 6 in U.S. Industrial
Outlook, 1970, U.S. Dept. of Commerce (1969).
Eckman, D.P., Industrial Instrumentation. John Wiley and
Sons, Inc. ( "
Emmett, P.M. and Brunauer, S., "The Use of Low Temperature
Van der Waals1 Adsorption Isotherms in Determining the
Surface Area of Iron Synthetic Ammonia Catalysts", J. Am.
Chem. Soc.. 59_, 1553 (1937).
Environmental Protection Agency, "Federal Register", Part
II, 36_ (21), January 30 (1971).
Environmental Protection Agency, "National Primary and
Secondary Ambient Air Quality Standards", Federal Regis-
ter, Environmental Protection Agency. 36 (84), April 30
(1971T "~
Erdco Engineering Corporation, "Tox-Ex", Bulletin 7160 (1970).
Eyring, H., Colburn, C.B. and Zwol1nsk1, B.J., "The Activated
Complex in Cheml sorption and Catalysis", Discussions of
Faraday Soc. 8. 39 (1950).
Falckenhagen, H., "Cohesion and Equation of Condition in
Dipolar Gases". Physlk. Z. 23. 87 (1922).
Freundlich, H. and Hase, E., "The Velocity of Absorption
Retrogression", Physik. Z. 89, 417 (1915).
Freundlich, H., Kapil larchemie, Akademische Verlagsgesel 1-
schaft m.b.h., Leipzig, 232 (1933).
Gadomski, R.R., David, M.P. and Blahut, G.A., "Evaluation of
Emissions and Control Technologies in the Graphic Arts
Industry", Graphic Arts Technical Foundation, U.S. Dept.
of Health. Education and Welfare. No. CPA-22-69-72 (1970).
-------
F-6
General Electric Company, "Type H-2, H-3, H-4 and H-5P Leak
Detectors and Control Units", Service Manual.
General Monitors, Incorporated, "Combustible Gas Detectors",
Bulletins on Models 510 and 410 (1970).
Grant, R.J., Manes, M. and Smith, S.6., "Adsorption of Normal
Paraffins and Sulfur Compounds on Activated Carbons", J.
Am. Inst. Chem. Enq. 8 (3). 403-406 (1962).
Grant, R.J. and Manes, M., "Adsorption of Binary Hydrocarbons
Gas Mixture on Activated Carbon", Ind. Enq. Chem. Fund. 5
490-8 (1966). ~ -*
Gregg, S.J. and Sing, K.S.W., Adsorption, Surface Area, and
Porosity. Academic Press, New York (1967).
Gustafson, P. and Smith, Jr., S.H., "Removal of Organic Con-
taminants from Air by Type 13X Molecular Sieve", NRL
Report 5560, U.S. Naval Research Laboratory, WashTJig'ton.
U.C., Aug. (1961).
Heck, W.W. and P1res, E.G., "Growth of Plants Fumigated with
Saturated and Unsaturated Hydrocarbon Gases and Their
Derivatives", Texas Agr1. Exp. Station Pub. 603 (1962).
Heln, G.M., "Odor Control by Catalytic and High Temperature
Oxidation", Annals of the New York Academy of Science.
116. 656 (196TF:
Hlndawl, I.J., "Air Pollution Injury to Vegetation", National
Air Pollution Control Administration, AP-71 (1971)1 "
Hlnshelwood, C.N., "Homogeneous Catalysis", Trans. Faraday
Soc. 24. 552 (1928).
Hlavacek, V., "Aspects in Design of Packed Catalytic Re-
actors", Ind. & Eng. Chem., ^2 (7), 8 (1970).
Holzbock, W.G., Instruments for Measurement and Control.
Relnhold Publishing Corporation, New York (1955).
Horesch, A.J., "The Role of Odors and Vapors In Allergic
Disease", Journal of Asthma Research 4 (2), (1966).
Hougen, O.A. and Watson, K.M., "Solid Catalysts and Reaction
Rates", Ind. & Enq. Chem. 35, 529 (1943).
Hwang, S.T. and Parravano, G.J., "Transient Response of
Chemically Interacting Solid Gas Systems", J. Electro-
chem Soc.. 114, 478 (1967).
-------
F-7
IITRI, "Identification of Chemical Constituents in Rendering
Industry Odor Emissions", Illinois Institute of Technology
(Research Institute), Final Report, IITRI Project No.
C8172. by T. Burgwald to Fats and Proteins Research Foun-
dation, Incorporated, Des Plaines, 111., D.M. Doty, Di-
rector (1971).
Jacobs, M.B., The Analytical Chemistry of Industrial Poisons;
Hazards and Solvents, Interscience (1949); The Analytical
Toxicology of Industrial Inorganic Poisons (1967); The"
Chemical Analysis of Air Pollutants, Interscience (1960).
Jaffe, H.H. and Orchln, M., Theory and Application of Ultra-
violet Spectroscopy. John Wiley and bons, inc.
Jaquet, E,, "The Theory of the Adsorption of Gases", Physik
U. Physik. Chem. (Chemical Physics and Physical Chemistry)
181 , 437 U9Z5) .
Johnson-Williams Products, Division of American Bosch Arma
Corporation, "Super-Sensitive Indicator", Bulletin SS-P.
May (1970).
Jost, W., Diffusion In Solids. Liuids. Bases, Academic Press,
Inc., New York, N.Y.
Joyner, L.C., Barrett, E.P. and Skold, R., "The Determination
of Pore Volume and Area Distribution 1n Porous Substances,
II. Comparison between Nitrogen Isotherm and Mercury
Porosimeter Methods", J. Am. Chem. Soc. 73, 3155 (1951).
Juhola, A.J. and W11g, E.O., "Pore Structure in Activated
Charcoal, I. Determination of Micropore Size Distribu-
tions", J. Am. Chem. Soc. 71. 2069 (1949).
Juhola, A.J., Palumbo, A.J. and Smith, S.B., "A Comparison
of Pore Size Distributions of Activated Carbons Calculated
from Nitrogen and Water Desorption Isotherms", J. Am.
Chem. Soc. '74, 61 (1952).
Kearney, T.J. and Kircher, C.E., "How to Get the Most from
Solvent-Vapor Degreasing, Parts I and II, Metal Progress.
93, May (1960).
Keesom, W.H., "Van der Waals Attractive Force", Physik. Z.
£2, 129 (1921).
KHmisch, R.L., "Oxidation of CO and Hydrocarbons Over Sup-
ported Transition Metal Oxide Catalysts", First National
Symposium on Heterogeneous Catalysis for Control of Air
Pollution, National Air Pollution Control Administration,
175-197 (1968).
-------
F-8
Klotz, I.M., "The Adsorption Wave", Chapter 8 of Summary
Technical Report of Division 10, NDRC (1946).
Kovats, E., Keulemans. A.I.M., "The Kovats Retention Index
System". Analytical Chemistry 16. (8), July (1964).
Lacasse, N.L., Moroz, W.J., Handbook of Effects Assessment.
Vegetation Damage. National Air Pollution Control Admin-
istration U969),
Langmuir, I., "A Chemically Active Modification of Hydrogen",
J. Am. Chem. Soc.. 34_, 1310 (1912).
Langmuir, I., "The Constitution and Fundamental Properties
of Solids and Liquids", J. Am. Chem. Soc.t 3£, 2221 (1916).
Langmuir, I., "The Adsorption of Gases on Plane Surfaces of
Glass. M1ca and Platinum", J. Am. Chem. Soc.. 40, 1361
(1918). ~~
LeBas, G., "The Molecular Volumes of Liquid Chemical Com-
pounds", Longmans Green, London (1915).
LeChatelier, H., "Estimation of Fire Damp and Inflammability
Limits", Ann. Mines. J£, 380 (1891).
Leonardos, G., Kendall, D. and Barnard, N., "Odor Threshold
Determination of 53 Odorant Chemicals", J. Air Pollution
Control Assoc.. J9. (2), 91 (1969). "
Levy, A. and Miller, S.E., "Final Technical Report on the
Role of Solvents in Photochemical Smog Formation",
Scientific Circular No. 79, National Paint. Varnish and
Lacquer Association, Washington, U.C. (19/0). """"""
Lewis, U.K., GlllHand, E.R., Chertow, B. and Cadogen, W.P.,
"Pure Gas Adsorption", J. Ind. and Eng. Chem. 42. 13-19
(1950).
Lewis, W.K., Gilliland, F.R., Chertow, B. and Cadogen, W.P.,
"Adsorption Equilibria-Hydrocarbon Gas Mixtures - Pure
Gas Isotherms". Ind. & Eng. Chem. 42. 1314-1332, July
(1950).
Lin, K.H., "Applied Reaction Kinetics", Ind. & Eng. Chem^.
61 (3), 42 (1969).
Linde Company, Division of Union Carbide Corporation,
"Physical Properties of Types 3A, 4A, 5A, 10X and 13X",
Sales Catalog F-9947-D. P.O. Box 44, Tonawand, N.Y.
11962).
-------
F-9
Lockheed, "Trace Contaminant Removal System Design", MSAR
Subcontract No. 28-5145 with Lockheed Missies and Space
Co. (1970).
London, F., "Theory of Systematics of Molecular Forces. A
General Survey of Intermolecular Forces from the Stand-
point of Quantum Mechanics", Physik." Z. BIT. 222 (1930).
London, F., "The General Theory of Molecular Forces", Trans.
Faraday Soc. 33, 8 (1937).
Lorenz, R. and Lande. H., "Adsorption and Corresponding
States", Z. anorg. u. allgem. chem. (Journal of Inorganic
and General Chemistry) 125, 47 (1922).
Los Angeles County APCD, "Rules and Regulations". Air Pollu-
tion Control District. County of Los Angeles (ly/U).
Lunche. R.G., Stein, A., Seymour, C.J. and Weimer, R.L.,
"Emission from Organic Solvent Usage in Los Angeles
County", J. Air Pollution Control Assoc. I, (4), 275
(1957). "~
MacGraw, M.J., "Air Pollution Emission Factors", U.S. Dept.
of Health. Education and Welfare, draft copy (1970).
Mango, F.D. and Schacktschneider, J.H., "Molecular Orbital
Symetry Conservation in Transition Metal Catalyzed Trans-
formations", J. Am. Chem. Soc. 89. 2484 (1967).
Maryland, "Air Quality StandardsNational Capitol Inter-
state Air Quality Control Region", Maryland State Depart-
ment of Health and Mental Hygiene. Baltimore, Maryland
October 20 (1970).
Mattia, M.M., "Process for Removing Organic Contaminants
from Air", U.S. patent 3,455,089 (1969).
Mattia, M.M., "Process for Solvent Pollution Control", Chem.
Eng. Progr. 66, (12), 74 (1970).
MCA, "Laboratory Waste Disposal Manual", Manufacturing Chemists
Assoc. (1970).
McGraw, M., Bokhe, K., Fensterstock, J. and Duggan, G.,
"St. Louis Air Pollutant Emission Inventory", U.S. Depart-
ment of Health, Education and Welfare, Durham, North
Carolina, August (1968).
McGraw, M. and Duprey, R.L., "Air Pollutant Emission Factors",
Environmental Protection Agency. Preliminary Document, 58
(1971).
-------
F-10
Mecklenburg, N., "Layer Filtration, A Contribution to the
Theory of Gas Masks"; Z. Elektrochemlc 31 (Journal of
Electrochemistry), 488 (
Melnhold, T.F. and Jones, D.L., "Objectionable Odors Snuffed
Out by Flameless Oxidation". Chem. Process.. (76), Novem-
ber 18 (1963). -___
Miller, M.R. and Wllhoyte, H.J., "A Study of Catalyst
Support Systems for Fume-Abatement of Hydrocarbon Sol-
vents", J. Air Pollution Control Assoc. 17 (121 (1967).
Miller, M.R. and Sowards, D.M., "Solvent Fume Abatement by
Ceramic Honeycomb Catalyst Systems", Proceedings. First
National Symposium on Heterogeneous Catalysis for Control
of. Air Pollution. National Air Pollution Control Arim
-------
F-II
National Institute of Dry Cleaning, "Estimation of Solvent
Vapor Emission from Petroleum Dry Cleaning Plants". Feb.
v 1 * 7 1 y ,
NFPA, "Hazardess Chemicals Data", National Fire Protection
Association. No. 49 (1969). --
Otake, T., Kunigita, E. and Naleao, K., "Analysis of an
Overall Gas-Liquid Reaction Rate Based on Two-Film
Theory11, Kagaku Kogaku 31 (7), 691 (1967).
Paasche Airbrush Company, "Air-finishing Booths", Catalog
AFB-865. 1909 Diversey Parkway, Chicago, II 1 inois (197l ) .
Parker, D.H., Principles of Surface Coating Technology.
Interscience Publishers, John Wiley & Sons, New York,
(1965).
Perry's Chemical Engineers Handbook. Perry, R.H., Chilton,
C.H., and Kirkpatrick, S.D., "Humidification and Drying",
McGraw-Hill, New York, Section 15-25 (1963).
Phillip, T., Communications on assembled costs of after-
burners, Shell Development, Emery, California (1971).
Polanyi, M., "Adsorption and Capillarity from Standpoint
of 2nd Law of Thermodynamics", Verhandl. deut. physik.
Ges.t Ji6_, 1012 (1914). -
Ray, G.C. and Box, Jr., E.O., Joint Symposium on Adsorption,
Am. Chem. Soc. Meeting. Atlantic City, N.J., Sept. 18-23
Ray, G.C. and Box, Jr., E.O., "Adsorption of Gases on Acti-
vated Charcoal", Ind. & Eng. Chem. 42. 1332, July (1949).
Ritter, H.L. and Drake, L.C., "Pore Size Distribution in
Porous Materials, Pressure Porosimeter and Determination
and Complete Macropore Size Distributions", Ind. & Enq.
Chem.. Anal. Ed. 17. 782 (1945).
Robell, A.J., Ballow, E.V. and Borgardt, F.G., "Basic
Studies of Gas-Solid Interactions III", Lockheed Missies
and Space Co.. Report No. 6-75-65-22. April U9b5).
Robell, A.J. and Merrill, R.P., "Gaseous Contaminant Removal
by Adsorption: II. Adsorption Dynamics in Fixed Beds",
Chemical Engineering Progress Symposium 65 (96). 100 (1969).
Rogers, T.H., "Natural Rubber", in Kirk-Othmer Encyclopedia
9f-Chei!lJ9a^ Technology. Interscience Pub., New York. 17
660 U968). "
-------
F-12
Romeo, P.L. and Warsh, A,, Catalytic Incineration Design
Parameters and Operating Practices. Public Health g«h
Training Manual, Feb. (1967).
Rosen, A. A., Peter, J.B. and Mlddleton, P.M., "Odor Threshold*
of Mixed Organic Chemicals". J. Water Pollution Control
Federation. 3£ (1), 7 (1962). ~ -- - - L
Ruch, W.E., Quantitative Analysis of Gaseous Pollutants
Ann Arbor-Humphrey, Science Publishers, London (1970)*.
Sabatier, P., LaCatalyse en Chemle Organlgue. C. Beranger
Paris, France (
Scott Aviation Daves Products Company, "Vapotesters" . Bulle
tin Nos. 17031. 17025. November (1969). ' '
Sheehey, J.P. and Henderson, J.J., "A Pilot Study of A1r
t on In Jacksonville, Florida", U.S. Dept. of Health
tlon and Welfare. U.S. Dept. of Commerce, Pb IbUUWL
U963J. *
Smith, M.F., "A1r Pollutant Emission 1n Greater Cincinnati"
Division of A1r Pollution Control, Department of Sewers '
Cincinnati, Ohio (1970). «wers,
Spray Engineering Company, "Spraco Spray Nozzles and Indus-
trial Finishing Equipment". Catalog 70. 100 Cambridge St
Burlington, Massachusetts (1971). - '
Stein, K.C., et.al., "The Oxidation of Hydrocarbons on S1mr»l«
Oxide Catalysts", J. Air Pollution Control Assoc. 10
275-281 (1960). - -- - ^
Stern, A.C., Air Pollution. Vol. II. Chapter 23, Academic
Press, New York, 325 U965T
Straus, W., "The Development of a Condenser for Odor Control
from Dry Rendering Plants", Journal of the Air Pollution
Control Association. ]£ (10), 4U4, October 114)64)" - ~
Sullivan, R.J., "Preliminary Air Pollution Survey of Odorous
Compounds - A Literature Review", National A1r Pollution
Control Administration. No. APTD 6fc'-42 (IM). - -
Sundaresan, B.B., Harding, C.I., May, F.P. and Hendrickson
E.P., "Adsorption of Nitrogen Oxides from Waste Gas",
Environ. Sci. and Techno!. 1 (2), 151, February (1967).
Suter, H.R., "Range of Applicability of Catalytic Fume
Burners". J. Air Pollution Control Assoc. 5 (3), 173
(1955). -
-------
F-13
Taylor. H.S. and Halsey, G.f "Contact Catalysis between
Two World Wars", J. Chem. Phys. 15. 627 (1947).
Temkin, M.I., Problems in Kinetics and Catalysis. Moscow
\ iy*ty).
Thiele, E.W., "Relation Between Catalytic Activity and Size
of Particle". Ind. & Eng. Chem. 31. 916 (1938).
Thomson, W.T., "On the Equilibrium of Vapor at a Curved
Surface of Liquids", Phil. Mag. 158. 448 (1871).
Trappe, W., "Separation of Biological Fats from Natural
Mixtures by Means of Adsorption Columns", Biochem. Z.
(Journal of Biochemistry) 305. 150 (1940). '
Turk, A., "Catalytic Reactivation of Activated Carbon In
Air Purification Systems", Ind. & Eng. Chem. 47 (1)
966 (1955).
United States Public Health Service, Selected Methods for
the Measurement of Air Pollutants, Publication No. 999-
AP-11 (1965).
University of Michigan, Encyclopedia of Instrumentation for
Industrial Hygiene. Institute of Industrial Hygiene (1956).
UOP, Universal Oil Products Company, Darien, Connecticut,
Handbook on catalytic and thermal incinerators.
U.S. Department of Commerce. "Graphic Arts", cp. 5, U.S.
Industrial Outlook, 1970 (1969).
U.S. Department of Commerce, "Food Products", cp. 6, U.S.
Industrial Outlook, 1970 (1969).
Vulcan-Cincinnati, Inc., "Solvent Recovery Installations11,
Sales literature. Vulcan-Cincinnati, Inc., Cincinnati,
Ohio (1971).
Walsh, R.T., "Solvent Degreasers", in Chapter 7, Air Pollu-
tion Engineering Manual. Danielson, J.A., ed., Public
Health Service, 999-AP-40, 383 (1967).
Webb, A.N., "Hydrofluoric Acid and Acidity of Alumina",
Ind. & Eng. Chem. 4£ (2), 261 (1957),
Weiss, S.M., A1r Pollution Engineering Manual. FS2.300,
AP-40, Washington, 387 (1967).
-------
F-14
Weisz, P.B. and Prater, C.D., Advances in Catalysis. Vol.
V^, Academic Press, New York (1954).
Wheeler, A., Advances in Catalysis. Vol. III. Academic
Press, New York (1951).
Wheeler, A., Catalysis. Vol. II, Ch. 2, Relnhold Pub. Co.,
New York (1955).
Wiig, E.G. and Juhola, A.J., "The Adsorption of Water Vapor
on Activated Charcoal", J. Am. Chem. Soc. 71. 561 (1949).
Wilhelm, R.H., Johnson, W.C. and Acton, F.S., "Conduction,
Convection and Heat Release in Catalytic Converters",
I rid. & Eng. Chem. 35 (5), 562 (1943).
Willard, H.H., Merritt, L.L. and Dean, J.A., Instrumental
Methods of Analyses, D. Van Norstrand Co., Inc., PHnce-
ton, New Jersey, 3rd Edition (1958).
Wonlers, H.C. and Jackson, W.E., "Air Pollution Emissions
in the Delaware Valley for 1965", The Environmental
Engineering and Science Program. Drexel Institute of
Technology, Philadelphia, Pennsylvania (1968).
Yang, K.H. and Hougen, O.A., "Determination of the Mechanism
of Catalyzed Gaseous Reactions", Chem. Eng. Proqr. 46.
146 (1950).
Young, D.M. and Crowell, H.O., Physical Adsorption of Gases.
Butterworths, London, 371-391 (1962).
Zimmerman, P.W., "Anesthetic Properties of Carbon Monoxide
and Other Gases in Relation to Plants, Insects and
Centipedes", Contribution from the Boyce Thompson Insti-
tute. 7 (2), 147-155 (1935)."
-------
Appendix G
Introduction to the Bibliography
Information sources considered pertinent to the Package
Sorption Device Study are included in the subsequent bibli-
ography,, Important sources include technical literature,
related government contract or in-house studies, trade pub-
lications and data obtained by letter or interviews.,
The bibliography has been divided into subsections with
references in each subsection placed in alphabetical order by
author,, This was done in order to make it easier to locate
cited references and additional collateral information , The
sections are titled and self-explanatory
In the text of the report, the author or principal
investigator is named first followed by the year the article
was publishedo In the bibliography the major author's name
appears first in the same way it appeared in the text. This
is followed by additional information needed to clarify and
enable the reader to locate the article. The year of pub-
lication is enclosed by parenthesis at the end» Often the
author is unknown, an article may be published by a govern-
ment agency, professional or trade society, or in some other
manner,, In these cases the key word and date of publication
are used in the text,, Abbreviations are sometimes used,
again followed by the year of publication. Key words or
abbreviations appear the same way in the bibliography followed
by additional identifying information spelling out the abbrevi-
ation,,
The titles of periodicals, serials and non-serial publi-
cations are abbreviated in the bibliography according to the
"American Standard for Periodical Title Abbreviations", and
can be located in Chemical Abstracts,,
-------
G-2
Appendix G
Bibliography
Air Pollutant Emission Sources
Alkire, H. L., "Air Pollution in Caroline County Maryland",
Division of Air Quality Control, Jan. (1960).
Altshuller, A. P., and Bufalini, J. J., "Photochemical Aspects
of Air Pollution: A Review", Environ. Sci. Techno!. 5
(4) (1971). ~
Annual Survey of Manufacturers, "Paper Coatings", U. S. Dent.
of Commerce, (1969).
Anon, "Know Your Solvents", Screen Process Magazine. 4£ (4),
28 (1967).
Anon, "Purifiers Remove Formaldehyde Fumes", Air Eng., June
(1968).
API Bulletin 2513, "Evaporation Loss in The Petroleum Indus-
try - Causes and Control", American Petroleum Institute
Bulletin 2513. (1959).
API 2516, "Evaporation Loss from Low-Pressure Tanks", Ameri-
can Petroleum Institute Bulletin 2516, (1962).
API Bulletin 2517, "Evaporation Loss from Floating-Roof
Tanks", American Petroleum Institute Bulletin 2517. (1962).
ASHRAE, cp. 31, "Odor Control", in Guide and Data Book
Systems. Am. Soc. Heat. Refrig, Air Cond. Engrs., New York,
459 (1970).
ASHRAE, cp. 12, "Odors", in Handbook of Fundamentals. Am.
Soc. Heat. Refrig. Air-Cond. Engrs., New York, 173
(1967).
ASTM, STP, 310, "Properties of Commercially Available De-
greasing Solvents", Am. Soc. Testing Mater.; - Handbook
of Vapor Degreasingf (1962).
Bailor, W. C. , "Dry Cleaning Equipment", in cp. 7, Air Pol-
lution Engineering Manual , Danielson, J. A. ed., PuFTTcT"
Health Service, 999-AP-4U. 393 (1967).
Barnebey.H. L., "Removal of Exhaust Odors from Solvent Ex-
traction Operation by Activated Charcoal Adsorption", J^
Air Pollution Control Assoc., 15 (4) , 422 (1965).
-------
G-3
Air Pollutant Emission Sources (continued)
Barnhart, R. F., "Rubber Compounding", in Kirk-Othmer Ency-
clopedia of Chemical
York, 12, 543 (1968).
clopedia of Chemical Technology, Interscience Pub., Mew
-k, 17,
Barr, A., "From Waste Materials: Tallow and High Protein
Meal", Chem. Eng..(1966).
Bell, K. E., "Leather and Fur Processing", in McGraw-Hil1
Encyclopedia of Science and Technology, New York, 7_t
445 (1960).
Benforado, D. M. , Rotella, W. J. and Norton, D. L. , "Develop-
ment of an Odor Panel for Evaluation of Odor Control Equip-
ment", J. Air Pollution Control Assoc., 1_9_ (2) , 101 (1969).
Benjamin, M.', Douglass, I. B. , et al , "A General Description
of Commercial Wood Pulping and Bleaching Process", J. Air
Pollution Control Assoc., 1J9 (3) , 155 (1969).
Berg, D. B. , and Lewandowski, R. , "Trichloro-Fume Control
Saves $780 per Week", Chem. Process, Jan. (1968).
Blank, D. H., "Rubber and Plastics Products", cp. 16, in U.S.
Industrial Outlook, 1970, U.S. Dept. of Commerce, (1969).
Brewer, G. L., "Odor Control for Kettle Cooking", J. Air
Pollution Control Assoc., ]3_ (4) (1963).
Bruno, M. H., "Printing Processes", in Kirk-Othmer Encyclo-
pedia of Chemical Technology. Interscience Pub., New York,
16 , 494 (1968).
Bureau of Census, "Chocolate and Cocoa", U.S. Dept. of Com-
merce. (1971).
Bureau of Census, "Coffee Roasting", U.S. Dept. of Commerce,
(1971).
Bureau of Census, "Tobacco Stemming and Redrying", U.S. Dent.
of Commerce, (1967).
Byrd, J. F., and Phelps, A. H., cp. 23, "Odor and its Measure-
ment", in Air Pollution. Vol. II, Stern, A. C., ed., p 305,
Academic Press, N. Y. (1968).
Byrnes, M. L., "Leather and Leather Products", 1n cp. 11,
U.S. Industrial Outlook. 1970, U.S. Dept. of Commerce,
(1969).
-------
G-4
A1r Pollutant Emission Sources (continued)
California (A1r Resources Board), "Emission Inventories
The Resources Agency, (1969).
N
Census of Manufacturers, "Adheslves". U.S. Dept. of Commerce.
(1969).
Census of Manufacturers, "Graphic Arts", U.S. Dept. of Com-
merce. (1967).
Census of Manufacturers, "Vegetable 011 Extraction", U.S.
Dept. of Commerce. (1963).
Chass, R.L., Kanter, C.V., and Elliott, J.H., "Contribu-
tion of Solvents to A1r Pollution and Methods for Control-
ling their Emissions", J. A1r Pollution Control Assoc..
13 (2), 64 (1963). '
Chass, R.L., Holmes, R.G., and Burlln, R.M., "Emissions
from Underground Gasoline Storage Tanks", J. A1r Pollution
Control Assoc.. JI3 (11) (1963). "
Chatfleld, H.E., "Pipe-Coating Equipment", cp. 7, In A1r
Pollution Engineering Manual. Danlelson, J.A. ed., U.S.
Dept. of Health, Education and Welfare, 999-AP-40, 390
(1967).
Collins, J.W., Webb, A.A., et al., "Components of Wood
Pulp Bleach", Pulp Manufacturers Research League Inc..
Appleton, Wise. 11968).
Cooper, J.C., and Cunniff, F.T., "Control of Solvent Emis-
sions", Metropolitan Engineers Council on A1r Resources.
New York, N.Y. (1967).
Copley Report "National Survey of the Odor Problem", National
A1r Pollution Control Administration, Copley International
Corp., Contract CPA 22-69-50, (1970).
Cowan, J.C., "Soybeans", 1n Klrk-Othmer Encyclopedia of
Chemical Technology. Intersdence Pub., New York, 1^8,
599 (1969).
Coward, H.F., and Jones, G.W., "Limits of Flammablllty of
Gases and Vapors", Bulletin 503. Bureau Of Mines. (1952).
-------
G-5
Air Pollutant Emission Sources (continued)
Crouse, W. R., and Flynn, N. E., "Summary of Oraanic Emissions
from the Dry Cleaning Industry", Bay Area Air Pollution
Control District. San Francisco 3, Calif. (1963).
Current, Fishery Statistics, "Fisheries of the U.S.", No.
5600, U.S. Dept of Commerce. (1970).
Dammakoehler, P. E., "Inventory of Emission for The City of
Chicago", J. Air Pollution Control Assoc.. Ij5 (3) (1966).
Denver, "Meeting the Challenge", Denver Air Pollution Control,
Feb. (1971).
Dickinson, J., Chass, R. L. and Hamming, W. J., "Air Contami-
nants", cp. 2. Air Pollution Engineering Manual, Daniel-
son, J. A. ed., Public Health Service, 999-AP-40, 12
(1967).
D'Imperio, 0., "Rubber-Compounding Equipment", CD. 7, In
Air Pollution Engineering Manual. Danielson, J. A., ed.,
Kubllc Health Service, 999-AP-40, 375 (1967).
Dobler, L. A., "Solvent Emissions from Stationary Sources
in Denver", Correspondence from Denver Air Pollution Con-
trol . Denver, Colorado (1971).
Drury, H. F., "Establishments 1n Commercial Printing", BDSA
Quarterly Industry Report; Printing and Publishing, 9_ (2)
, 15 (1968).
Duhl , R. W., "Factors Affecting Recovery of Rotogravure
Solvents", Vulcan-Cincinnati, Inc., (1970).
Dunn, H., et al., "Inks" 1n Kirk-Othmer Encyclopedia of
Chemical Technology. Interscience Pub., New YorK, TT,
611 (1966).
Easton, E. R. , "Food Products", cp. 6, in U.S. Industrial
Outlook, 1970, U.S. Dept. of Commerce, (1969).
ESSC, "Solvent Emission Control Laws and the Coatings and
Solvent Industry", Environmental Science Services Corp.,
24 Danbury Rd., Wilton, Conn.
Feuss, J. W. and Flowers, F. B., "State of the Art: Design
of Apartment House, Incinerators", J. Air Pollution Con-
trol Assoc., 19, (3) (1969).
-------
G-6
A1r Pollutant Emission Sources (continued)
Gadomski, R. R., David M. P. and Blahut, G. M. , "Evaluation
of Emissions and Control Technologies In the Graphic Arts
Industries", Graphic Arts Technical Foundation, U.S. Dept.
of Health. Education and Welfare. No. CPA22-69-7i!, (1970).
Glllett, T. P., "Chemicals and Allied Products", 1n cp. 15,
1n U.S. Industrial Outlook, 1970, U.S. Dept. of Commerce.
(1969). -
Glaser, J. R. and Ledbetter, J. 0., "Air Pollution from
Sewage Treatment", Paper No. 69-44. Univ. of Texas at
Austin. (1968).
Kama, G. M., "Corrosion of Combustion Equipment by Chlori-
nated Hydrocarbon Vapors", A1r Eng.. April (1965).
Hama, G., "How to Ventilate Coin Operated Dry Cleaning Equip-
ment", Air Eno., Dec., 34 (1961).
Hangebrauck, R. P., von Lehmden, D. J., Meeher, J. E.,
"Sources of Polynuclear Hydrocarbons in the Atmosphere",
U.S. Dept. of Health, Education, and Welfare. AP-33, (1967)
Hardlson, L. C., "Controlling Combustible Emissions", Paint
and Varnish Production, July (1967). '
Hardisty, J. T., "Selected Services", cp. 39, in U.S. Indus-
trial Outlook, 1970, U.S. Dept. of Commerce (1969).
Harris, T. L. , "Chocolate and Cocoa", 1n Kirk-Othmer Ency-
clopedia of Chemical Technology, Interscience Pub., New
York 5_ , 363 (1969).
HendMckson, E. R. , Roberson, J. E. and Koogler, J. B.,
"Control of Atmospheric Emissions in the Wood Pulping
Industry", U.S. Dept of Health, Education and Welfare.
Final Report^Contract No. CPA 22-69-18, Vol. 1 of (3)
Vol's. (1970).
Herbert, E. L., "Beverages", cp. 7 in U.S. Industrial Outlook,
1970, U.S. Dept. of Commerce. (1969).
Herbert, E. L., "Food Products", cp. 6, in U.S. Industrial
Outlook, 1970, U.S. Dept. of Commerce, (1969).
Heuser, A. R. , "Trends in Air Conservation 1n the Graohic
Arts Industry". Gravure. Feb. (1969).
-------
G-7
Air Pollutant Emission Sources (continued)
lanetti, M., "Solvents for Letter Press and L1thoqraph1c
Inks", American Ink Maker, 51, Oct. (1969).
IITRI, "Identification of Chemical Constituents in Rendering
Industry Odor Emissions", Illinois Institute of Technology
[Research Institute], Final Report, IITRI Project No.
C8172, by A. Burgwald to Fats and Proteins Research
Foundation, Inc., Des Plaines, 111., D. M. Doty, Director,
(1971).
Oenson, L. B. , Microbiology of Meats, Gerrard Press, Champaign,
111., (1945).
Jones, G. W. , "Inflammability of Mixed Gases", Technical
Paper 450, Bureau of Mines , (1929).
Juve, A., "Rubber Products", in McGraw-Hill Encyclppedia of
Science and Technology. New York, 11 . 664 U96QJ.
Kearney, T. J., and Kircher, C. E. , "How to Get the Most
from Solvent-Vapor Decreasing", Parts I and II Metal
Progress, April, 87 and May, 93 (1960).
Kempf, N. W., "Cocoa Powder and Chocolate", in McGraw-Hill
Encyclopedia of Science and Technology. New York, £ ,
252 (1960).
Kennedy, M. D. , "Food Products", cp. 6, in U.S. Industrial
Outlook, 1970, U.S. Pent, of Commerce, (1969).
Kerka, W. E. , and Kaiser, E. R., "An Evaluation of Environ-
mental Odors", J. Air Pollution Control Assoc.. 7_ (4;,
297 (1958) .
Knape, S. D. , "Tobacco", cp. 8, in U.S. Industrial Outlook,
1970, U.S. Dept. of Commerce, (1969).
Kovats, E. and Keulemans, A. I., "The Kovats Retention Index
System", J. Anal. Chem. 36 (8) , (1964).
Kuratsune, M., "Polycyclic Aromatic Hydrocarbons in Coffee
Soots", Proceedings of the American Association for
Cancer Research. Los Angeles, 1-15 U948).
Lange, N. A., and Forker, G. M., Handbook of Chemistry, 10th
ed., McGraw-Hill, New York (19677;
-------
G-8
Air Pollutant Emission Sources (continued)
LeBas, G., "The Molecular Volumes of Liquid Chemical Com-
pounds", Longmans Green, London (1915).
LeChatelier, H., "Estimation of F1re Damp and Inflammability
Limits", Ann. Mines, 1_9, 388 (1891),
Levy, A., and Miller, S.E., "Final Technical Report on the
Rule of Solvents in Photochemical Smog Formation", Scien-
tific Circular No. 79. National Paint. Varnish and Lacquer
Assoc.. Wash., D.C., (1970).
Lockhart, E.E., "Coffee Processing", in McGraw-Hill Encyclo-
?edia of Science and Technology, Interscience Pub., NevT~
ork, 3, , 265 U960).
Los Angeles APCD, "Rules and Regulations", Air Pollution
Control District. County of Los Angeles. (1970).
Lowry, H.H., Chemistry of Coal Utilization. Supp. Vol.,
Lowry. H.H. ed., John Wiley and Sons, Inc., New York
(1963).
Lunche, R.G., Stein, A., Seymour, C,J. and Weimer, R.L.,1
"Emission from Organic Solvent Usage in Los Angeles County
J. A1r Pollution Control Assoc., 7_ (4) , 275 (1957),
MacKnlght, R.L. and Williamson, J.E., "General Refuse In-
cinerators" cp. 8, in Air Pollution Engineering Manual.
Danielson, J.A. ed., U.S. Oept. of Health, Education and
Welfare, 999-AP-40, 419 (1967).
Maryland, "Air Quality Standards---National Capitol Inter-
state Air Quality Control Region", Maryland State Dent, of
Health and Mental Hygiene, Division of Air Quality Control.
Baltimore, Md. (1970).
McGraw, M.J. and Duprey, R.L., "Air Pollutant Emission
Factors", Environmental Protection Agency, Preliminary
Document, 58, (1971).
McGraw, M.J. and Duprey, R.L., "Evaporative Loss Sources",
in Air Pollutant Emission Factors, U.S. Environmental
Protection Agency,35 (1971).
-------
G-9
Air Pollutant Emission Sources (continued)
McGraw, M.J. and Duprey, R.L., "Fermentation", in Air
Pollutant Emission Factors, Preliminary DocumenTT" U.S.
Environmental Protection Agency, 74 (1971).
McGraw, M. , Bohke, K., Fensterstack, J. and Duggan, G.§
"St. Louis Air Pollutant Emission Inventory", U_._S_. Dept.
of Health, Education and Welfare, Durham, N.C. (1968).
Mellan, I., Handbook of Solvents, Reinhold Pub. Corp., New
York, Vol. ]_, (1957, 1959).
Mellan, I., Sourcebook of Industrial Solvents. Reinhold
Pub. Corp., New York, Vol's £, 3. (1957).
Mills, J.L., Danielson, J.A. and Smith, L.K., Control of
Odors from Inedible Rendering and Fish Meal Reduction in
Los Angeles County, Presented at the 60th Annual Meeting
of Air Pollution Control Assoc., Cleveland, Ohio (1967).
Mills, J.L., Walsh, R.T., et.al., "Quantitative Odor Measure-
ment", J. Air Pollution Control Assoc.. TJ. (10) (1963).
Moores, R.G., "Instant Coffee", in Kirk-Othmer Encyclopedia
of Chemical Technology, Interscience Pub., New York, 5_
» 757 (1964).
NAPCA 1970, "Nationwide Inventory of Air Pollutant Emissions'
National Air Pollution Control Administration, AP-73,
(1968).
Nashkovtsea, Tabak, 16 (1), 46 (1955).
National Institute of Drycleaning, "Estimation of Solvent
Vapor Emission from Petroleum Drycleaning Plants", Feb.,
(1971).
National Dry Cleaners Association, personal communication,
(1971).
NFPA, "Standard for Drycleaning Plants", National Fire Pro-
tection Assoc., NFPA No. 32, (1970).
Paasche Airbrush Co., "Airfinlshing Booths", Catalogue AFB,
Diversey Parkway, Chicago, 111., 865, 1909, (1971).
-------
G-10
Air Pollutant Emission Sources (continued)
Parker, D.H., "Industrial Finishes", cp. 42, in Principles
of Surface Coating Technology, Interscience Pub., New
York (1965).
Partee, F., "Air Pollution in the Coffee Roasting Industry",
U.S. Dept. of Health Education and Welfare. 999-AP-9,
(1966).
Polglase, W.L., Dey, H.F. and Walsh, R.T., "Deep Fat Frying",
cp. 11, in Air Pollution Engineering Manual. Danielson,
J.A. ed.. Public Health Service, 999-AP-40, 755 (1967).
Polglase, W.L., Dey, H.F. and Walsh, R.T., "Food Processing
Equipment", cp. 11, in Air Pollution Engineering Manual.
Danielson, J.A. ed., Public Health Service, 999-AP-40.
, 750 (1967). *
Randolph, A.F., ed., "Cellular Plastics", cp. 12, in Plastics
Engineering Handbook, Reinhold Pub. Corp., New York (i960)".
Randolph, V.A., ed., "Vinyl Dispersions", cp. 16, in Plastics
Engineering Handbook, Reinhold Pub. Corp., New York (I960),
Rogers, T.H., "Natural Rubber", in Kirk-Othner Encyclopedia
of Chemical Technology. Interscience Pub., New York, 17
, 660 (1968).
Rosse, D.G., "Chemicals and Allied Products", cp. 15, in U.S
Industrial Outlook, 1970, U.S. Dept. of Commerce. (1969).*
Rowe, N.R., "Controlling of Gaseous Contaminants Through
Adsorption". Bulletin T-101, J. Amer. Assoc. Cont. Contr
March (1964). ' ~*
Sallee, E.D., "Four Types of Air Pollution", Metal Decoratinn
Sept. (1968). £*
San Francisco Bay Area, "Source Inventory of A1r Pollutant
Emissions, San Francisco Bay Area", Bay Area A1r Pollution
Control District, San Francisco, Calif. (l969).
Scheflen, J. and Jacobs, M.P., The Handbook of Solvents. D.
Van Nostrand Co., Inc., New York, (1953).
-------
G-n
Air Pollutant Emission Sources (continued)
Scott Research Lab, Inc.. "Investigation of Passenger Car*
Refueling Losses", National Air Pollution Control Admini-
stration. Contract CPA-69-68, (1970).
Sheeny, J.P, and Henderson, J.J., "A Pilot Study of Air
Pollution in Jacksonville, Florida", U.S. Dept. of Health.
Education and Welfare, U.S. Dept. of Commerce, PB 168888,
April, (1963).
Shreve, R.N., The Chemical Process Industries. McGraw-Hill,
New York, (1945).
Slnitsyna, E.L., "Investigations into Certain Aspects of the
Health of People Working in the Main Shops of Tanneries",
Hygiene Sanitarian. 3£ (6) , 336 (1965).
Skeist, I., ed., Handbook of Adheslves. Reinhold Pub. Corp.,
New York (1962T1
Skolholt, 0., "Bread Production", 1n McGraw-Hill Encyclopedia
of Science and Technology. New York, 5_, 412 (1960).
Smith, M.F., "Air Pollutant Emissions 1n Greater Cincinnati",
Division of Air Pollution Control. Dept. of Sewers. C1n-
cinnati, Ohio (1970).
Solomon, G. and Petrone, J.P., "A Compilation of Solvents for
Flexographic and Gravure Inks", American Ink Maker. 51
(1969).
Spray Engineering Co., "Spraco Spray Nozzles and Industrial
Finishing Equipment", Catalogue 70. 100 Cambridge St.,
Burlington, Mass. (1971).
Stansby, M.E., "Fish and Shellfish", in Kirk-Othmer Encyclo-
pedia of Chemical Technology. Interscience Pub., New York,
|f^ 560 (1966).
Strauss, W., "The Development of a Condenser for Odor Control
from Dry Rendering Plants", J. Air Pollution Control Assoc..
]± (10) , 424 (1964).
Strauss, W., "Odor Control for the Process Industries", Chem.
& Proc. Eng., (London), March (1965).
-------
G-12
Air Pollutant Emission Sources (continued)
Sullivan, J.L., Kafka, F.L. and Ferrari, L.M., "An Evaluation
of Catalytic and Direct Fired Afterburners for Coffee and
Chicory Roasting Odors", J. Air Pollution Control Assoc.,
]£ (2), 583 (1965).
Sullivan, R.J., "Preliminary Air Pollution Survey of Odorous
Compounds - A Literature Review", National Air Pollution
Control Administration. No. APTD 66-42 (1969).
Summer, W., Methods of A1r Deodorization. Elsevier, Amster-
dam (1963).
Tl-3 Petroleum Committee, "Control of Atmospheric Emissions
from Petroleum Storage Tanks", J. Air Pollution Control
Assoc.. 21 (5), 260 (1971).
Tl-9 Pulp and Paper Committee, "A General Description of
Commercial Wood Pulping and Bleaching Process", J. Air
Pollution Control Assoc.. ]£ (3), 155 (1969).
Taylor, R.L., "Chemicals and Allied Products", cp. 15, in
U.S. Industrial Outlook, 1970, U.S. Dept. of Commerce.
(1969).
Taylor, O.C., "Injury Symptoms Produced by Oxidant Air
Pollutants", Chapter IV, in Handbook of Effects Assess-
ment. Lacasse, N.L., and Moroz, W.J., ed., Penn State
Univ., (1969).
Teller, A.J., "Odor Abatement in the Rendering and Allied
Industries", J. Air Pollution Control Assoc., 13^ (4),
148 (1963).
Thomas, G., "Mechanical Equipment", cp. 7, in Air Pollution
Engineering Manual . Danlelson, J.A., ed., U.S. Dept. of
Health, Education and Welfare, 999-AP-40. 325 (1967).
Tso, T.C., "Tobacco", in Kirk-Othmer Encyclopedia of
Chemical Technology. Interscience Pub., New York, 20.,
504 (1969).
U.S. Department of Commerce. "Graphic Arts", cp. 5, U.S.
Industrial Outlook, 1970 (1969).
-------
G-13
Air Pollutant Emission Sources (continued)
Viessman, W., "Gaseous Air-Pollution-Its Sources and Control",
Air Eng. , July (1968).
Vulcan-C1nc1nnati, Inc., "Solvent Recovery Installations",
Sales Literature, Vulcan-Cincinnati, Inc.. Cincinnati,
Ohio (1971).
Walsh, R.T., Leudtke, K.D., and Smith, L.K., "Fish Canneries
and Fish Reduction Plants", cp. 11, in Air Pollution
Engineering Manual , Danielson, J.A. ed., Public Health
Service, 999-AP-40, 760 (1967).
Walsh, R.T., "Solvent Degreasers", 1n Chapter 7, Air Pollution
Engineering Manual . Danielson, J.A., ed., Public Health
Service, 999-AP-40, 383 (1967).
Weast, R.C. and Selby, S.M., "Handbook of Chemistry and
Physics", 48th ed., The Chemical Rubber Co., Cleveland
(1967-1968).
Weiss, S.M., "Surface Coating Operations", en. 7, Air
Pollution Engineering Manual, Danielson, J.A. ed., Public
Health Service, 999-AP-40, : 387 (1967).
Wohlers, H.C. and Jackson, W.E., "A1r Pollutant Emissions
in the Delaware Valley for 1965", The Environmental
Engineering and Science Program, Drexel Institute of
Technology. Philadelphia, Pa. (1968).
Yocum, J.E. and Duffee, R.A.. "Controlling Industrial Odors",
Chen. Eng., June 15 (1970).
Zegel, W., "What's Going Out the Stack?", Ind. Finish,
(London) Dec. (1970).
Zimmerman, O.T. and Lavine, I., "Handbook of Material Trade
Names", 1953 ed., Suppl. 1, (1956), Suppl. 2, (1957),
Suppl. 4, (1965), Industrial Research Services, Dover,
New Hampshire.
-------
G-14
Air Pollutant Effects on Environment
Abeles, F.D. and Gahagan, H.E., "Abscission: The Role of
Ethylene, Ethylene Analogues, Carbon Monoxide and
Oxygen", Plant Physio!.. 43,, 1253 (1968).
ACGIH, "Threshold Limit Values of Airborne Contaminants and
Intended Changes", American Conference of Governmental
Industrial Hygienists. (1970).
AIHA, "Air Pollution Manual, Part 1 Evaluation", Am. Ind.
Hyg. Assoc.. Detroit, Mich. (1960).
AIHA, "Air Pollution Manual, Part II Control Equipment",
Am. Ind. Hyg. Assoc., Detroit, Mich. (1968).
AIHA, "Aldehydes", Am. Ind. Hyg. Assoc. J.. 29 (5) . 505
(1968). ~
AIHA, "Phenol and Cresol", Am. Ind. Hyg. Assoc. J.. 30
,425 (1969).
AIHA, "Sulfur Compounds", Am. Ind. Hyg. Assoc. J.. 31 (2)
,253 (1969).
Altshuller, A.P., "An Evaluation of Techniques for the
Determination of Photochemical Reactivity of Organic
Emissions", J. Air Pollution Control Assoc.. 16 , 257
(1966).
Altshuller, A.P., and Bufalini, J.J., "Photochemical Aspects
of Air Pollution: A Review", Environ. Sci. Techno!.» 5
(4), (1971).
Altshuller, A.P., et.al., "Products and Bioloqical Effects
from Irradiation of Nitrogen Oxides with Hydrocarbons
or Aldehydes under Dynamic Conditions", International
Journal of Air. Water Pollution. 1_0 , 81-98 (1966).
Altshuller, A.P., "Reactivity of Organic Substances in
Atmospheric Photooxidation Reactions", Public Health
Service. AP-14. July (1965). """
ASHRAE, cp. 31, "Odor Control", in Guide and Data Book
Systems, Am. Soc. Heat. Refrig. Air-Cond. Engrs., New
York, 459 (1970).
-------
G-15
Air Pollutant Effects on Environment (continued)
ASHRAE, cp. 12, "Odors", in Handbook of Fundamentals, Am.
Soc. Heat. Refriq. A1r-Cond. Engrs., New York, 173 (1967).
Barth, D.S., Romanovsky, J.C., Knelson, J.J., Altshuller,
A. P. and Horton, R.J.M., "Discussion", J. Air Pollution
Control Assoc.. 2J_ (9), 535 (1971).
Barynin, J., "Measuring Odour Pollution", New Scientist.
Oct. 15 (1970).
Bay Area APCD, "Requlations for the Bay Area", Air Pollution
Control District. Bay Area, (1971).
Benforado, D.M., Rotella, W.J. and Horton, D.L. ."Develop-
ment of an Odor Panel for Evaluation of Odor Control
Equipment", J. Air Pollution Control Assoc., 19. (2), 101
(1969).
Bl
atnik, J.A., "History of Federal Pollution Control
Leqislation", cp. 2, in industrial Pollution Control
Handbook, Lund. H.F. ed., McGraw-Hill, New Vork imi).
Brado, I.M., "Transplant Experiments with Corticulous
Lichens Usinq a New Technique", Ecology, ££ (4),
Brandt, C.S. and Heck, W.W.. cp. 12, "Effects of Air Pollu-
tants on Vegetation", in Air Pollution, Vol. 1, Stern,
A.C. ed., 401, Academic Press, New York (1968).
Brennen, E.G., Leone, I. A. and Dalnes, R.H., "Atmospheric
Aldehydes Related to Petunia Leaf Damage", Science, 143
818-819 (1964).
Brown, E.A. and Colombo, N.J., "The Asthmoqenic Effect of
Odors, Smells and Fumes", Ann, of Allergy. TJ? (1954).
Bufalinl, J.J. and Alfshuller, A. P., "Synergistic Effects
in the Photooxidation of Mixed Hydrocarbons", Environ.
Set. Techno!., 1 (2), 133 (1967). -
Burg, S.P, and Berg, E.A., "Molecular Requirements for the
Biological Activity of Ethylene", Plant Physio! . , 42,
144-152 (1967). _
Byrd, J,F. and Phelps, A.M., cp.23, "Odor and Its Measure-
ment", in Air Pollution Vol . II, Stern, A.C. ed., 305,
Academic Press, N. Y. (1968).
-------
G-16
Air Pollutant Effects on Environment (continued)
Byrd, J.F., Mills, H.A., Schellhaser. C.H. and Stokes, H.E.,
"Solving a Major Odor Problem In a Chemical Process", J.
A1r Pollution Control Assoc. , ^4 (12) , (1964).
California A1r Resources Board, "Emission Inventories", The
Resources Agency, (1969), """""
Committee on Hazardous Materials, "Evaluation of the Hazard
of Bulk Water Transportation of Industrial Chemicals",
Nat. Acad. Scl . . Wash.. D.C. (1970).
Copley Report, "National Survey of the Odor Problem", National
Air Pollution Control Administration. Copley International
Corp., Contract CPA-22-69-50, (1970).
Crass, F.L. and Ross, R.W., "Single-Pass Dryer Reduces A1r
and Water Pollution", Food Engineering. (1969).
Crocker, W., Hitchcock, A.E. and Zimmerman, P.W., "Similar-
ities in the Effects of Ethylene and the Plant Auxins",
Contributions from the Boyce Thompson Institute. 7 (3)
, 231-248 ~"
Dickinson, J., Chass, R.L. and Hamming, W.T., "Air Contamin-
ants", cp. 2, 1n Air Pollution Engineering Manual. Daniel-
son, J.A. ed., Public Health Service, 999-AP-40, 12
(1967).
EPA, "The Clean A1r Act", Environmental Protection Agency.
. Wash., D.C. (1970).
EPA, "National Primary and Secondary Ambient Air Quality
Standards", Federal Register, Environmental Protection
Agency, 36. (84) April 30 (197lT ""
EPA, "Requirements for Preparation and Submittal of Imple-
mentation Plans", Federal 'Register, Environmental Pro-
tection Agency, 3^6 (158), Aug. 14 (1971).
EPA, "Standards of Performance for New Stationary Sources",
Federal Register, Environmental Protection Agency. 36
(159), Aug. 17 (1971).
-------
G-17
Air Pollutant Effects on Environment (continued)
ESSC, "Solvent Emission Control Laws and the Coatings and
Solvents Industry", Environmental Science Services Corp.,
24, Danbury Rd., Wilton, Conn.
Fowler, P.B.S., "Printer's Asthma". The Lancet. 2, Oct.
(1952).
GCA, "Control Techniques for Polycyclic Organic Matter
Emissions", GCA Technology Division, Air Pollution Control
Administration, (1970).
Gillette, D.G. and Waddell, I.E., "Estimate of Air Pollution
Damage-Guidelines for Research and Control , presented at
Annual Meeting of Air Pollution Control Assoc., U970).
ng
et
A Symposium of the British Ecologi
- -
Goodman. G.T., et.al., "Ecology and the Industrial Society"
of the British Ecological Society. April
Guderian, R.H., et.al., "Problems of the Recognition and
Evaluation of the Effects of Gaseous Air Impurities on
Vegetation", Z. Pflanzerk lankh. Pf 1 anzenschutz, 67,
257-264, U.S. Public Health Service Report A 61-37.
Haagen-Smit. A.J. and Wayne, L.G.. "Atmospheric Reactions
and Scavenging Processes", cp. 6, in Air Pollution, Vol.
1, Stern, A.C. ed . , Academic Press, New York (1968) .
Haagen-Smit, A.J., et.al., "Investigations on Injury to
Plants from Air Pollution in the Los Angeles Area",
Plant Physio!.. 27_ , 18-34 (1952).
Hama, G.M., "Corrosion of Combustion Equipment by Chlori-
nated Hydrocarbon Vapors", Air Eng., April (1965).
Hangebrauck, R.P., von Lehmden, D.J., Meeker, J.E., "Sources
of Polynuclear Hydrocarbons in the Atmosphere", U.S. Dept.
of Health, Education and Welfare, AP-33 (1967).
Hardison, L.C., "Controlling Combustible Emissions", Paint
and Varnish Production, July (1967).
Heck, W.W. and Pires, E.G., "Growth of Plants Fumigated with
Saturated and Unsaturated Hydrocarbon Gases and their
Derivatives". Texas Agri. Exp. Station. Pub. 603, (1962).
-------
G-18
A1r Pollutant Effects on Environment (continued)
Heck, W.H.i "Measurement of Photochemical Air Pollution
with a Sensitive Monitoring Plant", J. Air Pollution
Control Assoc.. 2£ (2), (1970).
Hegnestad, H.E., "Diseases of Crops and Ornamental Plants
Incited by Air Pollutants", Phytopathology. 58, 1089-
1096 (1968). "~
Hemeon, W.C.L., "Technique and Apparatus for Quantitative
Measurement of Odor Emissions", Air Pollution Control
Assoc.. 1_8 (3), 166 (1968).
Heuss, J.M. and Glasson, U.A., "Hydrocarbon Reactivity and
Eye Irritation", Environ. Sci. Techno!.. 2 (12), 1109
(1968). -
Hill, A.C., "A Sneclal Purpose Plant Environmental Chamber
for Air Pollution Studies", J. Air Pollution Control
Assoc.. V7 (11), (1967).
H111 , A.C., "Inhibition of Apparent Photosynthesis by
Nitrogen Oxides", Atmospheric Environment. 4_ (1970).
Hill, A.C., et.al., "Ozone, Effect on Apparent Photosyn-
thesis, Rate of Transpiration and Stomatal Closure in
Plants", Center for Environmental Biology, Univ. of Utah.
(1969). '
Hlndawf, I.J., "Air Pollution Injury to Vegetation", National
Air Pollution Control Administration, AP-71 , (1971).
Hlndawl, I.J. and Altshuller, A.P., "Plant Damaqe Caused by
Irradiation of Aldehydes", Science, 146, 540-552 (1964)..
Horesch, A.J., "The Role of Odors and Vapors in Allergic
Disease", Journal of Asthma Research, 4_ (2), (1966).
Jacobs, M.B., Analytical Chemistry of Industrial Poisons.
Hazards arid Solvents, Vol. 1, Interscience Pub., N.Y,
(1949).
Jaffe, L.S,, "Effects of Photochemical A1r Pollution on
Vegetation with Relation to the Air Quality Requirements",
J. Air Pollution Control Assoc., T7_, 38-42 (1967).
Jaffe, L.S., "Photochemical Air Pollutants and Their Effect
II Adverse Effects", Archtv. Environ. Health, 1_6, 241
(1968).
-------
G-19
Air Pollutant Effects on Environment (continued)
Kerka, W.E. and Kaiser, F.R., "An Evaluation of Environmental
Odors". J. Air Pollution Control Assoc.. 21 (4)» 297 (1958).
Kniebes, D.V., Chisholm, J.A. and Stubbs, R.A., "Direct Odor
Level Measurement Instrumentation", Gas Age. Aug. (1969).
Knight, L.I. and Crocker, W., "Toxicity of Smoke", Botan.
Gaz., 55, 337-371 (1913).
Kuratsune, M., "Polycycllc Aromatic Hydrocarbons in Coffee
Soots", Proceeding of the American Association for Cancer
Research, Los Angeles, 1-15 (1948).
Lacasse, H.L., et.al., "A Cooperative Extension-Based System
of Detecting and Evaluating A1r Pollution Damage to
Vegetation", presented at the 63rd Annual Meeting of the
Air Pollution Control Assoc., Paper No. 70-107 (1970).
Lamphear, F.D., "A1r Pollution Injury to Plants 1n St. Louis",
63rd Meeting Air Pollution Control Assoc.. Paper No. 70-133,
(1970).'
Leonardos, G., Kendall, D. and Barnard, N.. "Odor Threshold
Determination of 53 Odorant Chemicals", J. Air Pollution
Control Assoc.. 1£ (2), 91 (1969).
Los Angeles County APCD, "Rules and Regulations", Air Pollu-
tion Control District. County of Los Angeles (1970).
Levy, A. and Miller, S.E., "Final Technical Report on the
Role of Solvents in Photochemical Smog Formation",
Scientific Circular No. 79, National Paint. Varnish and
Lacquer Assoc.. Wash.. D.C. (1970).
MacKniqht, R.L. and Williamson, J.E., "General-Refuse Incin-
erators", cp. 8, in Air Pollution Engineering Manual.
Danielson, J.A. ed., U.S. Dept. of Health, Education and
Welfare, 999-AP-40, 419 (1967).
Martin, D. and Tikvart, J.A., "A General Atmospheric Diffusion
Model for Estimating the Effects of One or More Sources on
Air Duality", Preprint National Air Pollution Control Ad-
ministration (1968).
MCA, "Laboratory Waste Disposal Manual", Manufacturing
Chemists Association (1970). -^.
Mills, J.L., Walsh, R.T., Leudtke, K.D. and Smith, L.T.,
"Quantitative Odor Measurement", presented at 56th Annual
Meeting of the A1r Pollution Control Assoc.. June (1963).
-------
G-20
Air Pollutant Effects on Environment (continued)
Moncrlef, R.W., Odor Preferences t Leonard Hill, London (1968).
NAPCA, "Air Quality Criteria for Hydrocarbons", National Air
Pollution Control Administration, AP-64,(1970^
NAPCA, "Air Quality Criteria for Photochemical Oxidants",
U.S. Dept. of Health. Education and Welfare, AP-63 (1970).
NFPA, "Hazardous Chemicals Data". National Fire Protection
Association, No. 49 (1969). ---_
Ottoson, D.G.R., "How We Recognize Odours", New Scientist.
Oct. 15 (1970).
Patty, F.A. ed.. Industrial Hygiene and Toxicology. 2nd ed.,
Vol. II, Toxicology, Intersclence Pub., Mew York (1965).
Peckham, B.W., "Some Aspects of A1r Pollution: Odors, Visi-
bility and Art", National Air Pollution Control Admini-
stration, (1969).
Pendray and Co., "Opinion Survey on Odors and Fumes as A1r
Pollution Problems", New York City, March (1955).
Polglase, W.L., Dey, H.F. and Walsh, R.T., "Deep Fat Frying",
cp. 11, 1n Air Pollution Engineering Manual. Danielson,
J.A. ed., Public Health Service, 999-AP-40, 755 (1967).
Philadelphia Dept. of Public Health, "Air Management Regu-
lation V - Control of Organic Substances from Stationary
Sources", Air Pollution Control Board (1971).
Rosen, A.A., Peter, J.B. and Middleton, P.M., "Odor Thres-
holds of Mixed Organic Chemicals", J. Water Pollution
Control Federation. 3,4 (1), 7 (1962T!
Sallee, E.D., "Four Types of Air Pollution", Metal Decor-
ating. Sept. (1968).
Sax, N.I., Dunn, M.S., et.al., Dangerous Properties of
Industrial Materials, 3rd ed., Relnhold Pub. Co., N.Y.
(1968).
Schonbeck, H., "A Method for Determining the Biological
Effects of Air Pollution by Transplanted Lichens", Staub-
Relnholt. Luft, 2S>, No. 1 (1969).
Seldman, G., et.al., "Environmental Conditions Affecting the
Use of Plants as Indicators of Air Pollution", J. A1r
Pollution Control Assoc., J5, (4), (1965).
-------
G-21
Air Pollutant Effects on Environment (continued)
Shepherd, M., Rock, S.M., Howard, R., and Stormes, J.,
"Isolation, Identification and Estimation of Gaseous
Pollutants of Air", J. Anal. Chem.. 23 (10) , 1431 (1951).
Sim, V.M., "Effect of Possible Smog Irritants on Human
Subjects", J. Am. Med. Assoc., Dec. (1957).
Sinitsyna, E.L., "Investigations into Certain Aspects of the
Health of People Working in the Main Shops of Tanneries",
Hyg. Sanitation. 30 (6) , 336 (1965).
Snow, G.F., et.al., "Procedures Used to Estimate the Economic
Impact of Air Pollution on Vegetation in California",
Rent. 70-06 California Dept. of Agriculture, presented at
63rd Annual Meeting of the Air Pollution Control Assoc..
(1970).
Stephens, E.R. and Burlson, F.R., "Analysis of the Atmosphere
for Light Hydrocarbons". J. Air Pollution Control Assoc..
!_£ , 147-153, (1967).
Stephens, E.R., Darley, E.F. and Burlson, F.R., "Sources and
Reactivity of Light Hydrocarbons in Ambient Air", Proc.
Div. Refining. American Petroleum Institute, 47. 466-483
(1967).
Strauss, W. , "Odor Control for the Process Industries",
Chem. & Process Eng. (London), March (1965).
Strauss, W., "The Development of a Condenser for Odor Control
from Dry Rendering Plants", J. Air Pollution Control Assoc
1_4_ (10) , 424 (1964). "~^~
Sullivan, R.J., "Preliminary Air Pollution Survey of Odorous
Compounds-A Literature Review", National Air Pollution
Control Administration, No. APTD 66-42, (1969).
Taylor, O.C., "Effects of Oxidant Air Pollutants", J,
Occupational Med., 10 (9), (1968).
Taylor, O.C., "Importance of Peroxy-acetyl Nitrate (PAN) as
a Phytotoxic Air Pollutant", J. Air Pollution Control
Assoc.. 19 , 347-351 (1969).
-------
G-22
A1r Pollutant Effects on Environment (continued)
Taylor, O.C., "Injury Symptoms Produced by Oxldant A1r
Pollutants", cp. IV, 1n Handbook of Effects Assessment,
Lacasse, N.L., and Noroz, W.J., ed., Penn State Univ.
(1969).
Teller, A.J., "Odor Abatement 1n the Rendering and Allied
Industries", J. A1r Pollution Control Assoc., 13 (4),
148 (1963).
Thompson, C.R., "Effects of A1r Pollutants on Growth, Leaf
Drop, Fruit Drop, and Yield of Citrus Trees", Environ.
Sc1. Techno!.. 3_ (1969).
Thompson, C.R., "Effects of A1r Pollutants on Lemons and
Navel Oranges", California Agriculture, 22^ (9), (1968).
Thompson, O.C., et.al., "Effects of Continuous Exposure of
Navel Oranges to Nitrogen Dioxide", Atmospheric Environ-
ment. £ (1970).
TR-1134, "Hazard Nuisance Pollution Problems Due to Odors-
Symposium IM, Japan Society for A1r Pollution. 8th Annual
Meeting. £ (1), 11-59 (1967).
Tremalne, B.K., "All About Odors - Detection, Analysis,
Control", A1r Eng.. Oct. (1959).
Treshow, M., "Evaluation of Vegetation Injury as an Air
Pollution Criterion", J. Air Pollution Control Assoc..
J_5 (6), (1965).
Turk, A., "Industrial Odor Control", Chemical Engineering
Deskbook Issue. April 27 (1970).
Van Sandt, W.A., Graul, R.J. and Roberts, W.J., "The
Determination of Acroleln in the Presence of Other
Aldehydes", presented at the 15th Annual Meeting of the
American Industrial Hygiene Association. Chicago, 111.
(1954).
-------
G-23
Air Pollutant Effects on Environment (continued)
Vlessman, VI., "Gaseous Air Pollution - Its Sources and
Control". Air Eng., July (1968),
Walsh, R.T., Leudtke, K.D. and Smith, L.K., "Fish Canneries
and Fish Reduction Plants", cp. 11, in Air Pollution
Engineering Manual, Danielson, J.A. ed., Public Health
Service, 999-AP-40, 760 (1967).
Weidensaul, T.C. and Lacasse, N.L., "Results of the State-
wide Survey of Air Pollution Damage to Vegetation",
63rd Annual Meeting of Air Pollution Control Assoc..
i ng
TTi
Paper No. 70-108, (1970).
Wilby, F.V., "Variation in Recognition Odor Threshold of
a Panel", J. Air Pollution Control Assoc., 19 (2) , 96
(1969). ~~~
Wohlers, H.C., et.al., "Recommended Procedures for Measuring
Odorous Contaminants in the Field", J. Air Pollution Con-
trol Assoc.. V7 (9) , 609 (1967). '
Yocum, J.E. and McCaldin, R.O., cp. 15, 'Effects of Air
Pollution on Materials and the Economy", 1n Air Pollution,
Vol. 1, Stern, A.C., ed., 617, Academic Press, New
York T1968).
Zimmerman, P.W., "Anaesthetic Properties of Carbon Monoxide
and Other Gases in Relation to Plants, Insects and Centi-
pedes", Contributions from the Boyce Thompson Institute,
7_ (2), 147-155 (1935).
-------
G-24
Sorptlon
AIHA and ACGIH, "Table of Sorbents for Contaminants Listed
in ACGIH 1970 Threshold Limit Values". American Indus-
trial Hygiene Association. June (1971).
ALCOA Product Data, "Activated and Catalytic Aluminas",
Aluminum Company of America, July 14 (1969).
American Document Institute, "ADI Document 2936", 1719 N.
Street, N.W., Mash. 6, D.C.
Antonson, C.R. and Dranoff, J.S., "Nonlinear Equilibrium
and Particle Shape Effects 1n Intrapartlcle Diffusion
Controlled Adsorption", Chemical Engineering Progress
Symposium, 65. (96) , 20 (1969).
API Bulletin 2513, "Evaporative Loss in the Petroleum
Industry-Causes and Control", American Petroleum Insti-
tute. Bulletin 2513 (1959).
Arrhenius, S., Theories of Solution. Yale Univ. Press (1912).
ASHRAE, "Guide and Databook Systems", Chapter 31, in
American Society of Heating, Refrigerating and Air-
Conditioning Engineers. Inc.. New Vork U970).
ASHRAE, "Handbook of Fundamentals", Chapter 12, 1n American
Society of Heating. Refrigerating and Air-Conditioninq
Engineers. Inc., New York (1967).
Avery, D.A. and Boiston, D.A., "The Recovery of Solvents
from Gaseous Effluents", The Chemical Engineer. Jan/Feb
(1969).
Bailor, W.C., "Dry Cleaning Equipment", in Chapter 7, Air
Pollution Engineering Manual, Danlelson, J.A. ed.,
Public Health Service, 999-AP-40 , 393 (1967).
Barnebey, H.L., "Activated Carbon for Air Purification",
Heating, Piping and Air Conditioning, March (1958).
Barnebey Cheney, T-108, "Air Purification and Recovery with
Activated Charcoal", Bulletin T-108, Sept. (1963).
Barnebey Cheney, T-196, "A1r Recovery by Charcoal Adsorption",
Barnebey Cheney Technical Bulletin T-196 (1958).
-------
G-25
Sorptlon (continued)
Barnebey, H.L., "Removal of Exhaust Odors from Solvent
Extraction Operation by Activated Charcoal Adsorption",
J. Air Pollution Control Assoc.. 1^ (4) , 422 (1965).
Barrer, R.M., McKenzie, N. and Reay, J.S., "Capillary Con-
densation in Single Pores", J. Colloid Sc1.. H. , 479
(1956).
Barrett, E.P. Joyner, L.G. and Halenda, P.M., "The Deter-
mination of Pore Volume and Area Distributions in Porous
Substances", J. Am. Ghent. Soc., 73,, 373 (1951).
Beeck, 0., "Hydrogenation Catalysts", Discussions Faraday
Soc.. £ , 118 (1950).
Bohart, G.S. and Adams, E.Q., "Some Aspects of the Behavior
of Charcoal with Respect to Chlorine", J. Am. Chem. Soc.
4£ , 523 (1920).
Brooman, D.L. and Edgerly, E., "Concentration and Recovery
of Atmospheric Pollutants Using Activated Carbon", J. Air
Pollution Control Assoc.t 1_6 (1) , 25 (1966).
Brown, R.A. and Foster, Jr.,'A.G., "The Sorption of Amines
by Silica Gels". J. Phys. Chem.. 5_6 , 733 (1952).
Brunauer, S., Emmett, P.A. and Teller, E.t "Adsorption of
Gases in Multimolecular Layers", J. Am. Chem. Soc. , 60
, 309 (1938).
Brunauer, S., The Adsorption .of Gases and Vapors, Princeton
Univ. PressT27 (1945).
Brunauer, S., "New Approaches to Pore Structure Analysis",
Chemical Engineering Progress Symposium. 6_5_ (96) , 1
(1969).
Brunauer, S., Deminq, U, Deminq, W. and Teller, E., "On
the Theory of van der Waals Adsorption of Gases", J. Am.
Chem. Soc., 62_ ,1723 (1940).
Brunauer, S., Emmett, P.H., "The Use of Low Temperature
van der Waals Adsorption Isotherms in Determininq the
Surface Areas of Various Adsorbents", J. Am. Chem. Soc.,
59 , 2682 (1937).
-------
G-26
Sorption (continued)
Buchwald, H., "Activated Silica Gel as an Adsorbent for
Atmospheric Contaminants", presented at 26th Meeting of
American Industrial Hygiene Assoc.. May (1965).
Burnett, R.W. and Turnbull , W.T., "Industrial Applications
of Molecular Sieves", British Chemical Engineering. 11
(4), (1966). ~~
Carter, J.W., "Adsorption Processes", Chem. and Process Enq.
. 37, Aug. (1966). ' a-
C.E.P., "Fluid Flow Through Packed Columns", Chem. Enq.
Progr., 48. (2) , 89, Feb. (1952).
Chass, R.L., Kanter, C.V. and Elliott, J. H., "Contributions
of Solvents to Air Pollution and Methods for Controlling
Their Emissions", J. Air Pollution Control Assoc., 13
(2) , 64 (1963). ~ ~"~ ~"
Cohan, L.H., "Sorption Hysteresis and the Vapor Pressure of
Concave Surfaces", J. Am. Chem. Soc.. 60 . 433 (1938).
Collins, J.J., "The LUB/Equi1ibrium Section Concept for
Fixed Bed Adsorption", 59th Annual Meeting of American
Institute of Chemical EFglneers, Detroit, Dec* U966).
Cooper, B.J., "Platinum-Carbon Catalysts with Molecular
Sieve Properties", Platinum Metals Review, 14 (4) , 133
(1970).
Cooper, D.E., Griswold, H.E., Lewis, R.M. and Stokeld, R.W.,
"Improved Desorption Route to Normal Paraffins", Chem.
Eng. Progr.. 62_ (4) , 69 (1966).
Cooper, J.C. and Cunniff, F.C., "Control of Solvent
Emissions", Metropolitan Engineers Council on Air Re-
sources, New York (1967).
CoughUn, R.W. and Ezra, F.S., "Role of Surface Acidity 1n
the Adsorption of Organic Pollutants on the Surface of
Carbon", Environ. Sci. Techno!.. 2_ (4), (1968).
Coward, H.F. and Jones, G.W., "Limits of FlammablHty of
Gases and Vapors", Bulletin 503, Bureau of Mines. U.S.
GOV't. Printing Office (1952).
-------
G-27
Sorptlon (continued)
Davison Chemical Division, W.R. Grace & Co., "Davison Mole-
cular Sieves", Sales Catalogs. 101 North Charles St.,
Baltimore, Md.
de Boer, J.H. and Custers, J.F.H.. "Regardinq the Nature of
Adsorption", Z. Phvsik. Chem. (Journal of Physical Chem-
istry) B 25 , 225 (1934).
Debye, P., "Molecular Forces and their Electrical Inter-
pretation", Physik. Z. (Journal of Physics), 2_2_ , 302
(1921).
Debye, P.. "van der Waals1 Cohesion Forces", Physik Z., 21_
, 178 (1920).
Dubinin, M.M. and Timofeev, D. P., "Adsorbability and
Physicochemical Properties of Vapors I. Adsorption of
Vapors by Active Carbons", J. Phys. Chem. (USSR), 21_
, 1213 (1947).
Dubinin, M.M., Vishnyakova, M.M., Zhukovskaya, E.G.,
Leont'ev, E.A., Luk'yanovich, V.M. and Sarakhov, A.I.,
"Investigation of the Porous Structure of Solids by
Sorption Methods", Russ. J. Phys. Chem. . 3£ , 959 (1960).
Dubinin, M.M., "Theory of the Bulk Saturation of Micro-
porous Activated Charcoals During Adsorption of Gases
and Vapours", Russ. J. Phy. Chem. . 39^ (6) , 697 (1965).
Dubinin, M.M. and Saverina, E., "The Porosity and Sorptive
Properties of Active Carbons", Acta. Physicochim. USSR,
£ , 647 (1936).
Dubinin, M.M., Zaverina, E.D. and Radushkevich, L.V.,
"Sorptlon and Structure of Active Carbons, I. Adsorption
of Organic Vapors", J. Phys. Chem., USSR. 21 , 1351
(1947).
Emmett, P.H. and Brunauer, S., "The Use of Low Temperature
van der Waals Adsorption Isotherms in Determining the
Surface Area of Iron Synthetic Ammonia Catalysts", J. Am.
Chem. Soc., 59^ , 1553 (1937).
Falckenhagen, H,, "Cohesion and Equation of Condition 1n
Dipolar Gases", Physik. Z., 23. , 87 (1922).
-------
G-28
Sorption (continued)
Foster, A.G., "Sorption Hysteresis, Some Factors Determining
the Size of Hysteresis Loop", J. Chem. Soc. (London).
1806 (1952),
Fraust, C.L. and Hermann, E.R., "The Adsorption of Aliphatic
Acetate Vapors onto Activated Carbon", Am. I rid. Hyg.
Assoc. J.. Sept-Oct (1969).
Freundlich, H., Kapil larchetnie, Akademische, Verlagsgesell-
schaft, m.b.h. Leipzig, 232, (1933).
Grace, W.R. and Co., "Davison Molecular Sieves", ADS-96-670.
Davisori Chemical Division.
Grant, R.J. and Manes, M., "Adsorption of Binary Hydrocarbon
Gas Mixtures on Activated Carbon", Ind. and Enq. Chem.
Fund.. £ , 490-498 (1966).
Grant, R.J., Manes, M. and Smith, S.B., "Adsorption of Normal
Paraffins and Sulfur Compounds on Activated Carbon", Am.
Inst. Chem. Engrs. J.. 8_ (3), (1962).
Grant, R.J., "Basic Concepts of Adsorption on Activated
Carbon", Pittsburgh Chemical Co., Activated Carbon
Technical Information.
Gregg, S.J. and Sing, K.S.W., Adsorption. Surface Area and
Porosity, Academic Press, N.Y. U967J.
Gurvitsch, L., "Theory of Heterogeneous Catalysis", J. Phys.
Chem. Soc. Russ., 4_7 , 805 (1915).
Gustafson, P. and Smith, Jr., S.H., "Removal of Contaminants
from Air by Type 13X Molecular Sieve", U.S. Naval Research
Lab.. NRL Report 5560, Aug. (1961).
Hasz, J.W. and Barrere, Jr., C.A., "Prediction of Equilibrium
Adsorption Capacity and Heats of Adsorption by the Polanyl
Potential Theory", Chemical Engineering Progress Symposium
6£ (96) , 48 (1969).
Hodgson, A.S., "Portable Smoke and Gas Removal Unit for
Personnel Shelters-Feasibility Study", Naval Civil
Engineering Laboratory, (1968).
Jaquet, E.§ "The Theory of the Adsorption of Gases", Physik.
V Phvsik. Chern (Chemical Physics & Physical Chemistry)
TST,437 l
-------
G-29
Sorption (continued)
Jones, G.W., "Inflammability of Mixed Gases", U.S. Dept.
of Commerce. (1928).
Jost, W., D1ffus i o n i n So 1 i d s , Liquids, Ba s e s . Academic
Press, New York (I960).
Joyner, L.C., Barrett, E.P, and Skold, R., "The Determination
of Pore Volume and Area Distribution in Porous Substances,
II Comparison between Nitrogen Isotherm and Mercury
Porosimeter Methods", J. Am. Chem. Soc.t 7^ , 3155 (1951).
Juhola, A.J., Palumbo, A.J. and Smith, S.B., "A Comparison
of Pore Size Distributions of Activated Carbons Calcu-
lated from Nitrogen and Water Desorption Isotherms", J^
Am. Chem. Soc.. 74. , 61 (1952).
Juhola, A.J. and Wiig, E.G., "Pore Structure in Activated
Charcoal, 1. Determination of Micro Pore Size Distri-
bution". J. Am. Chem. Soc.. 7± , 2069 (1949).
Juhola, A.J., "Report 40059", Pittsburgh Carbon Company.
Nov. (1951).
Keesom, W.H., "van der Waals Attractive Force", Phvsik. Z.,
22_ , 129 (1921).
Kiselev. A.V., The Structure and Properties of Porous Solids
195, Butterworth, London (1958).
Klotz, I.M., "The Adsorption Wave", Chem. Rev.. 39 , 241
(1946).
Kraemer, E.O., in A Treatise on Physical Chemistry ed. by
Taylor, H.S., , 1661, Macmillan, N.Y. (1931).
Langmuir, I., "The Adsorption of Gases on Plane Surfaces
of Glass, Mica and Platinum", J. Am. Chem. Soc.t 40
, 1361 (1918).
Langmuir, I., "A Chemically Active Modification of Hydrogen",
J. Am. Chem. Soc.. 3£ , 1310 (1912).
Langmuir, I., "The Constitution and Fundamental Properties
of Solids and Liquids", J. Am. Chem. Soc. 38 , 2221
(1916). "~
-------
G-30
Sorptlon (continued)
Ledoux, "Avoiding Destructive Velocity Through Adsorbent
Beds", Chem. Eng.. March (1948).
Leonard-Jones, J.E., "Processes of Adsorption and Fusion on
Solid Surfaces", Trans. Faraday Soc,, 28 , 333 (1932).
Lewis, W.K., G1ll1land, E.R., Chertow, B. and Cadogen, W.P.,
"Adsorption Equilibria-Hydrocarbon Gas Mixtures" - "Pure
Gas Isotherms". Ind. & Eng. Chen. 42, 1314-1332, July
(1950).
L1nde Company, Division of Union Carbide Corp., "Physical
Properties of Types 3A, 4A, 5A, 10X and 12X", Sales
Catalog F-9947-D. P.O. Box 41, Tonawand, N.Y. TT9T7).
Lippens, B.C., Linsen, B.G. and DeBoer, J.H.. "Pore Systems
1n Catalysts", J. Catalysis, 3, , 32 (1964).
Lockheed, "Trace Contaminant Removal System Design", MSAR
Subcontract No. 28-5145, with Lockheed Missies and Space
Co., (1970).
London, F., "The General Theory of Molecular Forces", Trans.
Faraday Soc. 33 . 8 (1937).
London, F., "Theory and Systematics of Molecular Forces.
A General Survey of Intermolecular Forces from the Stand-
point of Quantum Mechanics", Z. Physik., B 11 , 222
(1930).
Lorenz, R. and Lande, H., "Adsorption and the Corresponding
States", Z. Anorg. U. Allgem. Chern. (Journal of Inorganic
and General Chemistry), 125, 47TT922).
Loven, A.W., et.al., in J. Makowskl, et.al. "Collective
Protection Against CB Agents", Eighth Progress Report on
Contract No. DA 18-035-AMC-279 (A), AiResearch Mfg. Co.
Report Ho. CB-1008, Feb. (1966).
Maher, P.K., "Silica (Amorphous)", 1n Kirk-Othmer Encyclo-
pedia of Chemical Technology. Intersdence Pub., New York,
18, , 61 (1969).
Mattla, M.M., "Process for Solvent Pollution Control", Chenu.
Eng. Progr., 66. (12) , 74 (1970).
-------
G-31
Sorption (continued)
McBain, J.W., "An Explanation of Hysteresis in the Hydra-
tion and Dehydration of Gels", J. Am. Chem. Soc.. 57
, 699 (1935). '
McKee, D.W., "The Sorption of Hydrocarbon Vapors bv Silica
Gel", J. Phys. Chem.. £3 , 1256 (1959).
Mecklenburg, W., "Layer Fi1tration--Theory of the Gas Mask"
Z. Elektrochem. (Journal of Electrochemistry) 31 , 488
(1925).~-
Myers, A.L. and Prausnitz, "Thermodynamics of Mixed-Gas
Adsorption", Am. Inst. Chem. Engrs. J., 11 , 121-127
(1965). ~"
Othmer, D.F. and Sawyer, F.G., "Correlating Adsorption Data",
Ind. & Enq. Chem.. 35.. 1269 (1943).
Othmer, D.F. and Josefowitz, S., "Correlating Adsorption
Data", Ind. & Eng. Chem.. 4£ (4) , 723 (1948).
Papee, D. and Tertian, R., "Aluminum Compounds"! in Kirk-
Othmer Encyclopedia of Chemical Technology, Interscience
Pub., New York, 2_ , 42 (1963).
Pierce, C. and Smith, R.N., "Adsorption in Capillaries",
J. Phys. Chem.. 57_ ,64 (1953).
Pierce, C. and Smith, R.N., "Adsorption-Desorption Hysteresis
in Relation to Capillarity of Adsorbents", J. Phys. Chem.,
£4 , 784 (1950).
Pierce, C., Smith, R.N., Wiley, J.W. and Cordes, H., "Adsorp-
tion of Water by Carbon", J. Am. Chem. Soc., 73 ,4551
(1951). "~
Pierce, C., Wiley, J.W. and Smith, R.N., "Capillarity and
Surface Area of Charcoal", J. Phys. Chem.. 53 ,669
(1949). *
Pierce, C.. "Heats of Adsorption", J. Phys. Chem.t 57, 149
(1953).
Polanyl, M., "Adsorption and Capillarity from Standpoint of
2nd Law of Thermodynamics", Verhandl. deut. physik. Ges.
16 , 1012 (1914). "
-------
6-32
Sorption (continued)
Ray, G.C. and Box, Jr., E.O., "Adsorption of Gases on
Activated Charcoal", Ind. & Eng. Chem.. 42 ,1332,
July (1949). ~~
Rltter, H.L. and Drake, L.C., "Pore Size Distribution in
Porous Materials, Pressure Porosimeter and Determination
and Complete Macropore Size Distributions", Ind. & Eng.
Chem.t Anal. Ed.. ]_£ , 782 (1945). ~~
Robell, A.J., Ballow, E.V. and Borgardt, F.G., "Basic Studies
of Gas-Solid Interactions III", Lockheed Missies and Space
Co.. Report No. 6-75-65-22, Apri I 11965).
Robell, A.J. and Merrill, R.P., "Gaseous Contaminant Removal
by Adsorption: II. Adsorption Dynamics in Fixed Beds",
Chemical Engineering Progress Symposium. 65 (96) 100
(1969).~~
Robinson, C.S., "Commercial Activated Carbon Systems", cp. 13
in The Recovery of Vapors, with Reference to Volatile
Solvents, Relnnold Pub., N.Y. (194ZJ.
Rowe, N.R., "Controlling of Gaseous Contaminants Throuqh
Adsorption". Bulletin T-101, J. Am. Assoc. Cont. Contr..
March (1964).
Rowson, H.M., "Design Considerations in Solvent Recovery",
Proceedings MECAR Symposium. New Developments in Air
Pollution Control, Metropolitan Engineers Council on
Air Resources, New York (1967).
Sheehy, J.P., Achinger, W.C. and Simon, R.A., Handbook of
Air Pollution. National Center for Air Pollution Control.
Durham, N.C., 999-AP-44 (1970).
Sing, K.S.W. and Madeley, J.D., "The Surface Properties of
Silica Gels. I. Importance of pH in the Preparation from
Sodium Silicate and Sulfuric Acid", J. Appl. Chem.
(London) 3_ (1953).
S1ng, K.W.W. and Madeley, O.D., "Surface Properties of Silica
Gels. II. Adsorption of Water Vapor", J. ADD!. Chem.
(London), £ , 365 (1954).
Strauss, W., "Odor Control for the Process Industries",
Chem. & Process Eng.. March (1965).
-------
G-33
Sorption (continued)
Sundaresan, B.B., et.al., "Adsorption of Nitrogen Oxides
from Waste Gas", Environ. Sci. Techno!.. J_ (2), (1967).
Teller, A.J., "Odor Abatement in the Renderinq and Allied
Industries", J. Air Pollution Control Assoc.. 13 (4)
, 148 (1963). ~
Thomson, W.T., "On the Equilibrium of Vapor at a Curved
Surface of Liquids", Phil. Mag. 158 : 448 (1871).
Trappe, W., "Separation of Biological Fats from Natural
Mixtures by Means of Adsorption Columns", Biochem. Z..
(Journal of Biochemistry) 305 , 150 (1940).
Turk, A., "Industrial Odor Control", Chemical Engineering/
Deskbook Issue. April (1970).
Turk, A., Sleik, H. and Messer, P.O., "Determination of
Gaseous Air Pollution by Carbon Adsorption", Industrial
Hygiene Quarterly, 1J. (1) , 23 (1952).
Turk, A.. "Source Control by Gas-Solid Adsorption", Chapter
47, in Air Pollution, Vol. Ill, Stern, A.C. ed., 497,
Academic Press, N.Y. (1968).
Viessman, W., "Gaseous Air-Pollution-Its Sources and Control"
Air Enq. . July (1968).
Walsh, R.T., "Solvent Deqreasers", 1n Chapter 7, AjTr
Pollution Engineering Manual, Danielson, J.A. ed.,
Public Health Service, 999-AP-40, 383 (1967).
Webb, A.N., "Hydrofluoric Acid and Acidity of Alumina",
Ind. & Enq. Chem. 49 (2) , 261 (1957).
Weiss, S.M., "Surface Coating Operations", in Chapter 7,
Air Pollution Engineering Manual, Danielson, J.A. ed.,
Public Health Service, 999-AP-40, 387 (1967).
Wiig, E.O. and Juhola, A.J., "The Adsorption of Water Vapor
on Activated Charcoal", J. Am. Chem. Soc.. 71 561
(1949). "
-------
G-34
Sorntlon (continued)
Yocum, J.E. and Duffee, R.A.. "Controlling Industrial Odors",
Chem. Enq., June 15 (1970).
Young, D.M. and Crowell, A.O., Physical Adsorption of Gases,
Butterworths, London, 371-391 (1962).
-------
G-35
Sorbent Systems
API Bulletin 2518, "Evaporation Loss from Fixed-Roof Tanks"
American Petroleum Institute Bulletin 2518. (1962).
ASHRAE, Handbook of Fundamentals. "Odors", cp. 12, Am. Soc.
Heat. Refrig. Air-Cond. Engrs., New York, 175 (1967).
Aunln, W.J. and Kolarl, C.E., "Meat and Meat Products", 1n
Kirk-Qthmer Encyclopedia of Chemical Technology. Inter-
science Pub,, New York, 13, 176 (1967).
Bailor, W.C., "Dry Cleaning Equipment", 1n cp. 7, Air Pollu-
tion Engineering Manual, Danlelson, J.A. ed.. Public Health
Service, 999-AP-40, 393 (1967).
Barnebey, H.L., "Activated Carbon for Air Purification",
Heating. Piping and Air Conditioning. March (1958).
Barnebey, H.L. and Davis, W.L., "Costs of Solvent Recovery
Systems", Chem. Eng.t Dec. 29 (1959),
Barnebey, H,L., "Removal of Exhaust Odors from Solvent
Extraction Operation by Activated Charcoal Adsorption",
J. Air Pollution Control Assoc., ]£ (4), 422 (1965).
Berg, C. and Bradley, W.E., "Hypersorption-New Fractionatinq
Process", Petroleum Enn. . JJB, 115 (1947).
Berq, C,, "Hypersorntion-A Process for Separation of Light
Gases", Gas, 23, (1), 32 (1947).
Berg, D.B. and Lewandowski, R., "Trichloro-Fume Control Saves
$780 per week", Chem. Process., Jan. (1968).
Bloomfield, B.D., "Control of Gaseous Pollutants", Heating.
Piping and Air Conditioning. Jan. (1968).
Burchsted, C.A. and Fuller, A.B., "Hiqh-Efficiency A1r
Filtration Systems for Nuclear Application", ORNL-NSIC-65,
Oak Ridge National Laboratory, Jan. (1970),
Burnett, R.W. and Turnbull, W.T., "Industrial Applications
of Molecular Sieves", British Chem. Eng.. Vl^ (4), (1966).
Calgon Corp., Activated Carbon Adsorption Handbook, Pitts-
burgh Activated Carbon Div.
-------
G-36
Sorbent Systems (continued)
Chass, R.L,, Kanter, C.V. and Elliott. J.H., "Contribution
of Solvents to Air Pollution and Methods for Controlling
Their Emissions". J. Air Pollution Control Assoc.. 13 (2),
64 (1963).
Cooper. J.C. and Cunniff, F.T., "Control of Solvent Emissions",
New Developments in Air Pollution. Metropolitan Engineers
Council on Air Resources. (MECAR), New York (1967).
Duhl, R.W., "Factors Affectinq Economic Recovery of Roto-
qravure Solvents", Vulcan-Cincinnatit Inc.
Glaser, J.R. and Ledbetter, J.O., "Air Pollution from Sewaqe
Treatment", Paper No. 69-44. Univ. of Texas, at Austin.
(1968),
Gravure, "Exhaust Air Purification and Solvent Recovery in
Gravure Printing11, Gravure. March (1969).
Hardison, L.C., "Controllinq Combustible Emissions". Paint
and Varnish Production. July (1967). "
Harrinqton, R.E., "Gas-Solid Sorption Study", National A1r
Pollution Control Administration. Nov. 12 (1968).
Lauber, J.D., "The Control of Solvent Vapor Emissions", New
York State Dept. of Health. Paper No. 69-42. Jan. (1969T.
Mattia, M.M., "Process for Solvent Pollution Control", Chem.
Eng. Progr.. 66. (12), 74 (1970).
McGraw, M.J. and Duprey, R.L., "Air Pollutant Emission
Factors", Environmental Protection Agency. Preliminary
Document, 58 (1971).
Moncrieff, R.W., "Industrial Odors, Part 2 - General Methods
of Treatment", Industrial Water and Wastes. Sept-Oct (1961).
Perry's Chemical Engineers Handbook. Perry, R.H., Chllton,
C.H, and Klrkpatrick, S.D., "Humidlfication and Drying",
McGraw H111, New York, section 15-25 (1963).
Richardson, N.A. and Middleton, W.C., "Evaluation of Filters
for Removing Irritants from Polluted A1r", American
Society of Heating* Air Conditioning; Engineers, Journal
Section, Nov. (1958).
-------
G-37
Sorbent Systems (continued)
Robinson, C.S., "Commercial Activated Carbon Systems", cp.
13 in The Recovery of Vapors with Reference to Volatile
Solvents. Relnhold Pub., New York (1942).
Rowe, N.R., "Controlling of Gaseous Contaminants Through
Adsorption", Bulletin T-101, The Journal of the American
Association for Contamination Control . March U964).
Rowe, N.R., "The Economics of Activated Charcoal", Barnebey
Cheney, Air Enq.. May (1963).
Rowson, H.M., "Desiqn Considerations in Solvent Recovery",
Proceedings MECAR Symposium, New Developments in Air
Pollution Control, Metropolitan Enqlneers Council on A1r
Resources, New York (1967).
Santry, Jr., I.W.. "Hydroqen Sulflde Odor Control Measures".
Hater Pollution Control Federation, March
Stenburq, R.L., "ControlUnn Atmospheric E"1 J', 1tll
Paint and Varnish Operations, Part 1", Paint and Varnish
Production. Sept. (1959).
Strauss, W., "Odor Control for the Process Industries", Chem.
& Process Enq., March (1965).
Teller, A.J., "Odor Abatement 1n the Renderlnq «"d Allied
Industries", J. Air Pollution Control Assoc.. jj, (4),
148 (1963).
Turk, A., "Source Control by Gas-Sol1d Adsorption", 1n
cp. 47, Air Pollution, Vol. Ill, Stern, A.C. ed., 497
Academic Press. New York (1968).
Vulcan-Cincinnati, Inc., "Adsorption", Chem. Enq.. Oct.
(1952).
Westvaco, "Sulfur Recovery Process Under Development", Puljj.
and Paper. April (1971).
Yocum, J.E. and Duffee. R.A.. "Controlling Industrial Odors",
Chem. Enq.. June 15 (1970).
-------
6-38
Catalysis
Accomazzo, M.A. and Mobe, K., "Catalytic Combustion of Ci to
C3 Hydrocarbons", Ind. & EngV Chem., Process Design De-
velop.. 4_ (4), 425 (1965).
Acres, G.J.K., "Platinum Catalysts for the Control of Air
Pollution", Research Labs. Johson Matthey & Co.. Ltd.
Acres, G.J.K., "The Elimination of Organic Fume by Catalytic
Combustion", Platinum Metals Review, 14 (1), 2 (1970).
Anderson, R.B., et.al., "Catalytic Oxidation of Methane",
Ind. & Eng. Chem., 53, (10), 809 (1961).
Arrhenlus, S., Theories of Solution, Yale Univ. Press, 68
(1912).
Balandln, A.A., "The Theory of Heterogeneous Catalytic
Reactions. The Multlplet Hypothesis. A Model for De-
hydration Catalysis", Ze1t Phys. Chem.. 132. 289 (1929).
Beeck, 0., "Hydrogenatlon Catalysts", Discussions of Fara-
day Soc., 8., 118 (1950).
Berzellus, "On the Progress of Physical Sciences", report
to Swedish Academy of Sciences. Mar. 31 (1835).
Bloomfleld, B.D., "Control of Gaseous Pollutants", Heating.
Piping and A1r Conditioning. Jan. (1968).
Brewer, G.L., "Fume Incineration", Chem. Eng., Oct. 14
(1968).
Brewer, G.L., "Odor Control for Kettle Cooklno", J. A1r
Pollution Control Assoc.. 1_3_ (4) (1963).
Brodskl, A.M., et.al., "Ouant1tat1ve Characterization of the
Reliability of Chemical Reaction Mechanisms", Dold, Akad.
Nauk SSSR, (Proceedings of the Academy of Science of the
USSR). 174 (4), 865 (1967).
Brunauer, S., Emmett, P.H, and Teller, E., "Adsorption of
Gases 1n Multlmolecular Layers", J. Am. Chem. Soc., 60,
309 (1938).
Christian, J.6. and Johnson, J.E., "Catalytic Combustion of
Aerosols", Ind. A Eng. Chem., Prod. Res. 4 Develop., £
(3) (1963).
-------
6-39
Catalysis (continued)
Christian, J.G. and Johnson. J.E., "Catalytic Combustion of
Atmospheric Contaminants Over Hopcallte", International
Journal of A1r Water Pollution. Perqamon Press. 9. 1-10
(1965).
Cooper, B.J., "Platinum-Carbon Catalysts with Molecular
Sieve Properties". Platinum Metals Review. 14 (4), 133
(1970).
Crouse, L.F., "Efficient Design of After Burners for Incin-
eration of Many Industrial Fumes", Air Eng.. Aug. (1967).
Corrigan, I.E., "Catalysis and Absorption", Chem. Eng^. 61,
236 (1954).
Dmuchovsky, B., Freerks, M.C. and Zrenty, F.t "Metal Oxide
Activities 1n the Oxidation of Ethylene", J. Catalysis
1, 577 (1965).
Dowden, D.A. and Reynolds, P.W., "Heterogeneous Catalysis:
Theoretical and Hydrogenatlon by Binary Alloys", J. Am.
Chem. Soc.. 242-271 (1950).
Dowden, D.A. and Wells, D., Vol. II, Proceedinos of the
Second International Congress on Catalvsls, Paris, France
(1961).
Edwards, F.R., "Catalytic Combustion of Fumes and Odors",
presented at Air and Water Pollution Control, 5th Annual
Seminar (1969TI~
Emmett, P.H. and Brunauer, S., "The Use of Low Temperature
van der Waals' Adsorption Isotherms 1n Determining the
Surface Area of Iron Synthetic Ammonia Catalysts", J. Am.
Chem. Soc.. 59., 1553 (1937).
Eyring, H., Colburn, C.B. and Zwolinskl, B.J., "The Activated
Complex in Chem1sorpt1on and Catalysis", Discussions Fara-
day Soc.. 8., 39 (1950).
Freundlich, H. and Hase, E., "The Velocity of Absorption
Retrogression", Zelt Physik. Chem. 89. 417 (1915).
Hardlson, L.C., "Controlling Combustible Emissions", Paint
and Varnish Production. July (1967).
-------
G-40
Catalysis (continued)
Harkness, A.C., Murray. F.E. and Glrard, L., "Catalytic
Oxidation of Sulfurous Air Pollutants", Atmospheric
Environment* 2., 303, Grt. Brltlan (1968).
He1n, R.M., "Odor Control by Catalytic and Hlqh Temperature
Oxidation", Ann. N.Y. Acad. Scl., 116. 656 (1964).
Hlnshelwood, C.N., "Homoqeneous Catalysis", Trans. Faraday
Soc. 24_, 552 (1928).
Hlavacek, V., "Aspects 1n Deslqn of Packed Catalytic Reac-
tors", Ind. & Eng. Chem., 1_2_ (7), 8 (1970).
Houqen, O.A. and Watson, K.M., "Solid Catalysts and Reaction
Rates", Ind. & Enq. Chem., 3£, 529 (1943).
Hwano, S.T. and Parravano, G.J., "Transient Response of
Chemically Interacting Solid Gas Svstems", J. Electro-
chem Soc.. 114, 478 (1967).
Johns, P.H., "Kinetics and Catalyst Selection 1n the Com-
bustion of AtmosnheMc Trace Contaminants", Chemical
Engineering Progress Symposium. 6_2_ (63), 81 (1966).
KHmlsch, R.L., "Oxidation of CO and Hydrocarbons Over
Supported Transition Metal Oxide Catalysts", First
National Symposium on Heterogeneous Catalysis for Con-
trol of A1r Pollution, National A1r Pollution Control
Administration, 175-197 (1968).
Krenz, W.B., Dlckenson, J. and Chass, R.L., "An Appraisal of
Rule 66 of the Los Angeles Count'/ A1r Pollution Control
District", J. A1r Pollution Control Assoc., 18, 743
(1968). "~
Lamb, A.B., "The Preferential Catalytic Combustion of
Carbon Monoxide 1n Hydrogen", J. Am. Chem. Soc., 44,
738-57 (1952).
Lanqmulr, I., "The Adsorntlon of Rases on Plane Surfaces
of Glass, Mica and Platinum", J. Am. Chem. Soc.. 40.
1361 (1918).
Lin, K.H., "Applied Reaction Kinetics", Ind. & Enq. Chen,.
61 (3), 42 (1969).
-------
G-41
Catalysis (continued)
Mango, F.D. and Schacktschneider, J.H., "Molecular Orbital
Symetry Conservation In Transition Metal Catalyzed
Translormations" J. Am. Chem. Soc.. 89, 2484 (1967),
Miller, f'.R. and Wilhoyte, H.J., "A Study of Catalyst Support
Systems for Fume Abatement of Hydrocarbon Solvents", J.
Air Pdllution Control Assoc.. H (12) (1967).
Mi-lls, G.A., "Catalysis", in Kirk-Othirer Encyclopedia of
Chemical Technology, Interscience Fub., New York, 4_ , 534
(1964).
Ctake, T., Kunigita, E. and Naleao, K., "Analysis of an
Overall Gas-Liquid Reaction Rate Based on Twp-Film
Theory". Kagaku Kogaku 31 (7) ,691 (1967).
Paulus, H.J., "Nuisance Abatement by Combustion", cp. 48 1n
Air Pollution, Vol. Ill, Stern, A.C. ed., 521, Academic
Press, N.Y. (1968).
Pitzer, E.C. and Frazer, J.C.W., "The Physical Chemistry of
HopcalUe Catalysts", J. Phys. Chem., £5 (1941).
Romeo. P.L. and Warsh, H., Catalytic Itineration Design
Parameters and Operating Practices, Public Health Service
Training Manual, Feb. (1962).
Sabatler, P., LaCatalvse en Chemie Organique, C. Beranger
Paris, France (1920).
Selwood, P.W., "Magnetism and the Structure of Catalytically
Active Solids", in Advances in Catalysis, 3_ . 27 (195U-
Sherwood, P.W., "Get Rid of That Smell", Food Manufacture,
July (1961).
Stein, K.C., et.al., "The Oxidation of Hydrocarbons on
Simple Oxide Catalysts", J. Air Pollution Control Assoc..
l_p_ , 275-81 (1960).
Strauss, W., "Odour Control for the Process Industries",
Chem. & Process Eng., March (1965).
Suter, H.R., "Range of Applicability of Catalytic Fume
Burners", J. Air Pollution Control Assoc., 5_ (3), (1955).
-------
G-42
Catalysis (continued)
Taylor, H.S. and Halsey, G., "Contact Catalysis between
Two World Wars", J. Chem. Phys. 1.5 , 627 (1947).
Temkln, M.I.. Problems in Kinetics and Catalysis, Moscow
(1949). ""
Thlele, E.W., "Relation Between Catalytic Activity and Size
of Particle", Ind. & Eng. Chem., 3J_ , 916 (1938).
Thomaldes, L., "Why Catalytic Incineration?", Pollution
Engineering, May/June (1971).
Viessman, W., "Gaseous A1r-Pol1ution-Its Sources and Con-
trol", A1r Eng., July (1968).
Welsz, P.B. and Prater, C.D., Advances in Catalysis. Vol. VI,
Academic Press, New York (l9b4j.
Wheeler, A., Catalysis, Vol. II, cp. 2, Relnhold Publ. Co.,
New York (1955).
Wheeler, A., Advances in Catalysis. Vol. Ill, Academic
Press, New York (1951).
Wllhelm, R.H. Hohnson, W.C. and Acton, F.S., "Conduction,
Convection and Heat Release in Catalytic Converters",
Ind. & Eng. Chem., 35, (5) , 562 (1943).
Yang, K.H. and Hougen, O.A., "Determination of the Mechanism
of Catalyzed Gaseous Reactions", Chem. Eng. Progr., 46,
146 (1950).
Yocum, J.E. and Duffee, R.A.. "Controlling Industrial Odors",
Chem. Eng.. June 15 (1970).
-------
fi-43
Catalytic Incineration
Acres, G.J.K., "The Elimination of Organic Fume by Cataly-
tic Combustion", Platinum Metals Review. 14 (1) . 2
(1970).
Bloomfield, B.D., "Control of Gaseous Pollutants", Heating.
Piping and Air Conditioning, Jan. (1968).
Brewer, G.L., "Odor Control for Kettle Cooking", J. Air
Pollution Control Assoc., V3 (4), (1963).
Brewer, G.L., "Fume Incineration", Chem. Eng., Oct. 14
(1968).
Grouse, L.F., "Efficient Design of Afterburners for
Incineration of Many Industrial Fumes", Air Eng.. Aug.
(1967).
Cooper, J.C. and Cunnlff. F.T., "Control of Solvent Emissions",
Metropolitan Engineers Council on Air Resources. New York,
N.Y. (1967)."~
Dmuchovsky, B., Freeks, M.C. and Zrenty, F., "Metal Oxide
Activities 1n the Oxidation of Ethylene", Journal of
Catalysis 4 . 577 (1965).
Edwards, F.R., "Catalytic Combustion of Fumes and Odors",
presented at Air and Water Pollution Control, 5th Annual
Seminar (1969).
Hardison, L.C., "Controlling Combustible Emissions", Paint
and Varnish Production, July (1967).
He1n, G.M., "Odor Control by Catalytic and High Temperature
Oxidation", Ann. M.Y. Acad. Sci.. 116 , 658 (1964).
Klimisch, R.L., "Oxidation of CO and Hydrocarbons Over
Supported Transition Metal Oxide Catalysts", First
National Symposium on Heterogeneous Catalysis for Con-
trol of Air Pollution. National Air Pollution control
Administration, 175-197 (1968).
Lin, K.H., "Applied Reaction Kinetics", Ind. ft Eng. Chem..
61 (3) , 42 (1969).
Mattia, M.M., "Process for Solvent Pollution Control", Chem.
Eng. Progr. 66 (12) , 74 (1970).
-------
G-44
Catalytic Incineration (continued)
McGraw, M.J. and Duprey, R.L., "Evaporative Loss Sources",
In Air Pollutant Emission Factorst 35 (1971).
Mills, J.L., Walsh, R.T., et.al., "Quantitative Odor
Measurement", J. Air Pollution Control Assoc., 13 (10)
(1963). ~
Miller, M.R. and WUhoyte, H.J., "A Study of Catalyst Support
Systems for Fume-Abatement of Hydrocarbon Solvents", J.
A1r Pollution Control Assoc.. 17 (12) (1967).
Partee, F., "A1r Pollution 1n the Coffee Roasting Industry",
U.S. Dept. of Health, Education and Welfare. 999-AP-9,
(1966).
Paulus, H.O., "Nuisance Abatement by Combustion", cp. 48 1n
'A If Pollution, Vol. Ill, Stern, A.C. ed., 521, Academic
Press, New York (1968).
Romeo, P.L. and Warsh, H.t Catalytic Incineration Design
Parameters and Operating Practices. Public Health Service
Training Manual, Feb. (1962).
Strauss, W., "Odor Control for the Process Industries", Chem.
& Process Eng.t March (1965).
Sullivan, J.L., Kafka, F.L. and Ferrari, L.M., "An Evalu-
ation of Catalytic and Direct Fired Afterburners for
Coffee and Chicory Roasting Odors", J. Air Pollution
Control Assoc.. 1_5 (2) , 583 (1965).
Suter, H.R., "Range of Applicability of Catalytic Fume
Burner", J. Air Pollution Control Assoc., 5 (3) , 173
(1955). "
Taylor, H.S. and Halsey, G., "Contact Catalysis between Two
World Wars", J. Chem. Phys.. ^5 , 627 (1947).
Wilhelm, R.H., Hohnson, W.C. and Acton, F.S., "Conduction,
Convection and Heat Release in Catalytic Converters", Ind,
& Eng. Chem., 35. (5) , 562 (1943).
Yocum, J.E. and Duffee, R.A., "Controlling Industrial
Odors", Chem. Eng., June 15 (1970).
-------
G-45
Thermal Incineration
Anon., "Direct Flame Method of Incineration for Combustible
Solvents", Air Eng.. April (1968).
Benforado, D.M. and Waitkus, J., "Exploring the Applicability
of Direct-Flame Incineration to Wire-Enamel Ing Fume Con-
trol". Wire and Wire Products. Nov. (1967).
Bloomfield, B.D., "Control of Gaseous Pollutants", Heating,
Piping and A1r Conditioning, Jan. (1968).
Brewer, 6.L., "Fume Incineration". Chert. Eng.. Oct. 14
(1968).
Chass, R.L., Kanter, C.V. and Elliott, J.H., "Contribution
of Solvents to Air Pollution and Methods for Controlling
Their Emissions", J. Air Pollution Control Assoc.. ^ (2)
. 64 (1963).
Cooper, J.C. and Cunniff, F.T., "Control of Solvent Emissions",
Metropolitan Engineers Council on Air Resources, New York,
N.Y. (1967).
Coward, H.F. and Jones, G.W., "Limits of Flammability of
Gases and Vapors", Bulletin 503. Bureau of Mines, (1952).
Grouse, L.F., "Efficient Design of Afterburners for Incin-
eration of Many Industrial Fumes", Air Eng., Aug. (1967).
GCA, "Control Technigues for Polycyclic Organic Matter
Emissions", GCA Technical Division. Air Pollution Control
Administration. (1970).
Hardison, L.C., "Controlling Combustible Emissions", Paint
and Varnish Production, July (1967).
He1n, G.M., "Odor Control by Catalytic and High Temperature
Oxidation", Ann. N.Y. Acad. Sci.. 116 , 656 (1964).
McGraw, M.J. and Duprey, R.L., "Air Pollutant Emission
Factors", Environmental Protection Agency. Preliminary
Document, 58 (1971).
McGraw, M.J. and Duprey, R.L., "Evaporative Loss Sources",
in Air Pollutant Emission Factors. 35 (1971).
-------
G-46
Thermal Incineration (continued)
Mills, J.L., Walsh, R.T., et.al., "Quantitative Odor
Measurement", J. Air Pollution Control Assoc., 13 (10)
(1963).
Paulus, H.J., "Nuisance Abatement by Combustion", cp. 48,
1n Air Pollution. Vol. Ill, Stern, A.C. ed., 521
Academic Press, N.Y. (1968).
Polglase, W.L., Dey, H.F. and Walsh, R.T., "Deep Fat Frying",
cp. 11, 1n A1r Pollution Engineering Manualt Danlelson,
J.H. ed., Public Health Service, 999-AP-40, 755 (1967).
Polglase, W.L., Dey, H.F. and Walsh, R.T., "Food Processing
Equipment", cp. 11, In Air Pollution Engineering Manual.
Danlelson, J.A. ed., Public Health Service, 999-AP-40,
746 (1967).
Sullivan, J.L., Kafka, F.L. and Ferrari, L.M., "An Evaluation
of Catalytic and Direct Fired Afterburners for Coffee and
Chicory Roasting Odors", J. Air Pollution Control Assoc..
!£ (2) , 583 (1965).
Thomaldes, L., "Why Catalytic Incineration?", Pollution
Engineering, May/June (1971).
Vlessman, W., "Gaseous Air Pollution-Its Sources and
Control", Air Eng.. July (1968).
Walsh, R.T., Leudtke, K.D. and Smith, L.K., "Fish Canneries
and Fish Reduction Plants", cp. 11, In Air Pollution
Engineering Manualt Danielson, J.A. ed., Public Health
Service, 999-AP-40, 760 (1967).
Yocum, J.E. and Duffee, R.A.. "Controlling Industrial Odors",
Chem. Eng., June 15 (1970).
-------
G-47
Liquid Absorption
ASHRAE, "Odor Control", cp. 31, in Guide and Data Book
Systems, Am. Soc. Heat., Refriq., Air-Cond. Engrs.. New
York, 459 (1970).
Barnebey, H.L., "Removal of Exhaust Odors from Solvent
Extraction Operation by Activated Charcoal Adsorption",
J. Air Pollution Control Assoc.. 1_5 (4) 4?2 (1965).
Bloomfield, B.D., "Control of Gaseous Pollutants", Heating.
Piping and Air Conditioning. Jan. (1968).
Calvert, S., "Source Control by Liquid Scrubbing", in Air
Pollution, chapter 46, Vol. Ill, Stern, A.C. ed., "T57
Academic Press, New York (1968).
Chass, R.L., Kanter, C.V. and Elliott, J.H., "Contribution
of Solvents to A1r Pollution and Methods for Controlling
Their Emissions", J. Air Pollution Control Assoc.. 13
(2) , 64 (1963). " ~
Chatfield, H.E., "Pipe-Coating Equipment", chapter 7, in
Air Pollution Engineering Manual. Danielson, J.A. ed.,
U.S. Dept. of Health, Education and Welfare, 999-AP-40,
390 (1967).
Cooper, J.C. and Cunniff, F.T., "Control of Solvent Emis-
sions", Metropolitan Engineers Council on Air Resources.
New York, N.Y. (1967).
Mattia, M.M., "Process for Solvent Pollution Control", Chem.
Eng. Proqr.. 6£ (12) , 74 (1970).
Mills, J.L., Walsh, R.T., et.al., "Quantitative Odor
Measurement", J. Air Pollution Control Assoc.. 13 (10)
(1963).
Partee, F., "A1r Pollution in the Coffee Roasting Industry",
U.S. Dept. of Health, Education and Welfare. 999-AP-9,
(1966).
Strauss, U., "The Development of a Condenser for Odor Con-
trol from Dry Rendering Plants", J. Air Pollution Control
Assoc.. V4 (10) , 424 (1964).
Strauss, W., "Odor Control for the Process Industries",
Chem. & Process Enq. . March (1965).
-------
G-48
Liquid Absorption (continued)
Teller, A.J., "Odor Abatement In the Renderlno and Allied
Industries", J. A1r Pollution Control Assoc., 13 (4),
148 (1963).
Walsh, R.T., Leudtke, K.D. and Smith, L.K., "F1sh Canneries
and F1sh Reduction Plants", cp. 11, 1n A1r Pollution
Enolneerlnq Manual, Oanlelson, J.A. ed.f 999-AP-40,
760 (1967).
Yocum, J.E. and Duffee, R.A., "ControlUnq Industrial
Odors", Chem. Eng.» June 15 (1970).
-------
G-49
Absorption Systems
Bloomfield, B.D., "Control of Gaseous Pollutants1*. Heating,
Piping and Air Conditioning, Jan. (1968).
Calvert, S., "Source Control by Liquid Scrubbing", cp. 46,
In A1r Pollution, Vol. Ill, Stern, A.C. ed., 457,
Academic Press, N.Y. (1968).
Cooper, J.C. and Cunnlff, F.T., "Control of Solvent
Emissions", Metropolitan Engineers Council on A1r Re-
sources, New York, N.Y, (1967^
McGraw, M.J. and Duprey, R.L., "Air Pollutant Emission
Factors", Environmental Protection Agency, Preliminary
Document, 58 (1971).
Strauss, W., "The Development of a Condenser ^ °d°r Con-
trol from Dry Rendering Plants", -i - Air Pollution Control
Assoc.. 14 (10), 424 (1964).
Strauss, W., "Odor Control for the Process Industries", Chenr
& Process Eng.. March (1965).
Teller, A.J., "Odor Abatement 1n the Rendering and A]]{ed
Industries", J. A1r Pollution Control Assoc., H V^/»
148 (1963).
Walsh, R.T., Leudtke, K.D. and Smith, L.K., "F1sh Canneries
and F1sh Reduction Plants", cp. 11, 1n A1r Pollution
Engineering Manual . Danlelson, J.A. ed.. Public Health
Service, 999-AP-40, 760 (1967).
-------
G-50
A1r Pollutant Detection
American Industrial Hygiene Association, Air Pollution Manual.
Part I, "Evaluation", Am. Ind. Hyg. Assoc. J. (1960).
American Industrial Hyqlene Association, "Hyq1en1c Guide
Series", Am. Ind. Hyg. Assoc. J., January (1971).
Barvnln, J.. "Measuring Odor Pollution". New Scientist.
Oct. 15 (1970).
Beckman Instruments, Incorporated, "Hydrocarbon Analyzer",
Bulletin P70565-1269-106F (1969).
Bendlx Process Instruments Division, "Total Hydrocarbon
Analyzer", Bulletin A530SB-1Q70 (1970).
Conn, G.K. and Avery, D.G., Infrared Methods. Academic
Press (I960).
Davis Instrument Division, "Davis Hallde Meter", Bulletin
P/N 11-9000 (1971).
Davis Instrument Division, "Flame Ion1zat1on Meter", Bulletin
11-65-2 (1965).
Davis Instrument Division, "Toxldty Limits and Detector
Methods", Bulletin 7020763 (1963).
Eckman, D.P., Industrial Instrumentation. Wiley, New York
(1955).
Eckman, D.P., Industrial Instrumentation. John Wiley and
Sons, Inc. (1950).
Environmental Protection Agency. "Federal Register", Part
II, 36. (21), January 30 (1971).
Erdco Engineering Corporation, "Tox-Ex", Bulletin 7160
(1970).
General Electric Company, "Type H-2, H-3, H-4 and H-5P Leak
Detectors and Control Units". Service Manual.
General Monitors, Incorporated, "Combustible Gas Detectors",
Bulletins on Models 510 and 410 (1970),
-------
G-51
A1r Pollutant Detection (continued)
Hemeon, W.C.L., "Technique and Apparatus for Quantitative
Measurement of Odor Emissions", J. Air Pollution Control
Assoc., 18 (3), 166 (1968).
Hochhelser, S., Burman, F.J. and Morgan, G.B., "Atmospheric
Surveillance, The Current State of the Art", Environ.
Scl. Techno!., 5. (8), 678 (1971).
Holzbock, W.G., Instruments for Measurement and Control.
Relnhold Publishing Corporation, New York (1955).
Jacobs, M.B., The Analytical Chemistry of Industrial Poisons;
Hazards and Solvent's, Intersdence (1949); The Analytical
Toxicology of Industrial Inorganic Poisons (1967); The.
Chemical Analysis of A1r Pollutants. Intersdence (1960).
Jaffe. H.H. and Orchln, M., Theory and Application of Ultra-
violet Spectroscony. John WHey and Sons, Inc. (1962).
Johnson-Williams Products, D1v. of American Bosch Jrma
Corporation, "Super-Sensitive Indicator", Bulletin SS-P,
May (1970).
Kay, K., "Analytical Methods Used 1n A1r Pollution Study",
Ind. and Eng. Chem.,., 44, 1383 (1952).
Knlebes, D.V., Chlsholm, J.A. and Stubbs, R.C., Direct
Odor Level Measurement Instrumentation", Gas Age, w-ti,
August (1969).
Mills, J.L., Walsh, R.T., Leudtke. K.D. and Smith. L.K..
"Quantitative Odor Measurement", presented at the 56th
Annual Meeting of the A1r Pollution Control Association.
June (1963).
Mine Safety Appliances Company. "B11Hon-a1re, Trace Gas
Analyzer", Bulletin 0706-2 (1970),
Mine Safety Appliances Company, "Combustible Gas Detection",
"Combustible Gas Analyzer", Bulletins 0703-18 and 0703-4
(1970).
Mine Safety Appliances Company, "Combustible Gas Indicators",
Bulletin Nos. 0806-10. 0804-11 (1971).
-------
G-52
A1r Pollutant Detection (continued)
Mine Safety Appliances Company, "Universal Tester*. Bulletin
0815-5 (1971).
Prince, R.G.H. and Inc1, J.H., "The Measurement of Intensity
of Odors", J. Appl. Chem.. 8;. 314 (1958).
Ruch, W,E., Quantitative Analysis of Gaseous Pollutants, Ann
arbor-humphrey, Science Publishers, London (1970).
Sax, N.I., Dunn, M.S., et.al. eds.. Dangerous Properties of
Industrial Materials, 3rd ed., Relnhold Pub. Co., New
York (1968).
Scott Aviation Oaves Products Company, "Vapotesters",
Bulletin Nos. 17031, 17025, November (1969).
Stern, A.C., ed., A1r Pollution. £, 2nd ed. (1968).
Turk, A., Slelk, H. and Messer, P.J., "Determination of
Gaseous A1r Pollution by Carbon Adsorption", Ind. Hyq.
Quarterly, JJ. (1), 23 (1952).
Turk, A., "Measurements of Odorous Vapors 1n Test Chambers,
Theoretical", J. Am. Soc. Heating. Refrlg. & A1r Cond.
Engrs.. £ (10), 55 (1963).
United States Public Health Service, Selected Methods for
the Measurement of A1r Pollutants, Publication No. 999-
AP-11 (1965).
University of M1ch1nan, Encyclopedia of Instrumentation for
Industrial Hygiene, Institute of Industrial Hygiene
(1956).
WHlard, H.H., Merrltt, Jr., L.L. and Dean, J. A., Instru-
mental Methods of Analyses, D. Van Norstrand Co., Inc.,
Princeton, New Jersey, 3rd Edition (1958).
Wohlers, H.C., "Recommended Procedures for Measuring Odorous
Contaminants 1n the Field", J. Air Pollution Control
Assoc., V7 (9), 609 (1967).
-------
BIBLIOGRAPHIC DATA
SHEET
1- Report No.
EPA-R2-73-202
3. Recipient's Accession No.
Package Sorption Device System Study
5. Report Date
April 1973
6.
7. Author(s)
Juho1af Program Manager
8' Performing Organization Kept.
No.
9. Performing Organization Name and Address
MSA Research Corporation
Division of Mine Safety Appliances Company
Evans City. Pennsylvania 16033
10. Project/Task/Work Unit No.
11. Contract/Grant No.
EHSD 71-2
12. Sponsoring Organization Name and Address
EPA, Office of Research and Monitoring
NERC/RTP, Control S ystems Laboratory
Research Triangle Park, North Carolina 27711
IX Type of Report & Period
Covered
Final
14.
15. Supplementary Notes
16. Abstract,The report. Q) identifies and characterizes the numerous small, but
objectionable, sources of gaseous pollutants; (2) ranks sources according to relative
importance; (3) assesses the equipment and technology available for controlling these
sources, in handbook form; (4) investigates the potential and need for development of
technology and new sorbents; and (5) details research and development recommend-
ations to improve existing devices or to develop new control methods. Emission
sources amenable to control by package sorption devices contribute 15% of the total
organic emissions from all sources and can be divided into two broad categories:
(1) solvent-user industries that emit solvents essentially unchanged, and (2) process
industries that generate pollutants by chemical, biological, or thermal reactions.
Regenerative activated carbon adsorbent systems show promise for the control of
pollutants from these sources, particularly at concentrations below 700 ppm. At
higher concentrations, catalytic
17. Key W'otds and Document Analysis. 17o. Descriptors
Air Pollution
*Sorption
Activated Carbon
Hydrocarbons
Solvents
Incinerators
Catalysis
17b. Identifiers/Open-Ended Terms
Air Pollution Control
Stationary Sources
*Packaged Control Devices
Organic Emissions
and thermal incinerators are
more economical except where
the would-be pollutant is a
valuable solvent recoverable by
the adsorbent system.
17e. COSATI Field/Croup
18. Availability Statement
Unlimited
19. Security Class (This
Report)
..IftjC
UK ? "^-^-'"-'irir-iJ
20. Security Class (This
P«e
UNCLASSIFIED
21. No. of Pages
22. Pt
USCOMM-OC I4»J2-«MI
------- |