DRAFT
ENGINEERING HANDBOOK
FOR HAZARDOUS WASTE INCINERATION
November 1980
Contract No 68-03-2550
Work Directive T1OI6
For
U.S. Environmental Protection Agency
Office of Research and Development
Cincinnati, Ohio 45268
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DRAFT
ENGINEERING HANDBOOK FOR HAZARDOUS WASTE INCINERATION
November 1980
by
T. Bonner, B. Desai, J. Fullenkamp, T. Hughes, E. Kennedy,
R. HcCormick, J. 'Peters and D. Zanders
Monsanto Research Corporation
1515 Nicholas Road
Dayton, Ohio 45407
EPA Contract No. 68-03-2550; Work Directive T1016
Project Officer: Mr. Richard Carnes
Industrial Environmental Research Laboratory
Office of Environmental Engineering and Technology
Cincinnati, Ohio 45208
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
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EPA REVIEW NOTICE
This report has been reviewed by the U.S. Environmental
Protection Agency, and approved for publication as a draft
report. Approval does not signify that the contents necessarily
reflect the views and policy of the Agency, nor does mention of
trade names or commercial products constitute endorsement or
recommendation for use.
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PREFACE
The Resource Conservation and Recovery Act (RCRA) authorizes the
United States Environmental Protection Aqency (EPA) to regulate
owners/operators of facilities that treat hazardous waste in
incinerators. Pursuant to the legislative mandates specified in
RCRA, the EPA has issued regulations to ensure that hazardous
waste incinerators are operated in an environmentally responsible
manner. Briefly, the regulations include an operational perform-
ance standard for destruction criteria, waste analysis, trial
burns, monitoring and inspections, recordkeepinq and reporting,
control of fugitive emissions, and closure requirements, as well
as operating criteria, specified on a case-by-case basis.
These site-specific determinations of operating criteria will
be made by permit writers through the exercise of their engin-
eering judgement. As an aid to those permit writers the Aqency
has compiled in this manual a summary of existing knowledge
about the operation of hazardous waste incinerators. '''his manual
should also be of interest to public citizens concerned about
incinerator operations. Finally, the manual may be useful to
facility owners or operators, both as a source of information
for operational decisions, and as a reference for preparation of
permit applications.
The Agency intends to revise this manual regularly to include
results of new research or knowledge. Please contact EPA with
requests for revised copies or with suqqested material for
inclusion in future editions.
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CONTENTS
1. INTRODUCTION 1-1
2. CURRENT PRACTICES 2~1
2.1 Introduction 2-1
2.2 Commercially Available Hazardous Waste Incineration
Technologies 2~4
2.2.1 Rotary Kiln 2'-j
2.2.2 Liquid Injection 2~8
2.2.3 Fluidized Bed 2-11
2.2.4 Multiple Hearth 2'14
2.2.5 Coincineration 2"18
2.3 Emerging Hazardous Waste Incineration Technology 2-20
2.3.1 Starved Air Combustion/Pyrolysis 2-20
2.4 Air Pollution Control Devices (APCD) 2'23
2.4.1 Afterburners 2~24
2.4.2 Gas-Atomized Spray Scrubber (Venturi) 2-27
2.4.3 Packed Bed Scrubber 2"30
2.4.4 Spray Tower 2~34
2.4.5 Plate Scrubber 2-36
2.4.6 Electrostatic Precipitator (ESP) 2-39
2.4.7 Wet Electrostatic Precipitator (WEP) 2-42
2.5 References 2"44
3. WASTE CHARACTERIZATION 3"1
3.1 Introduction 3-1
3.2 Waste Characterization Background Information 3-1
3.2.1 Information Available from Waste Generators 3-1
3.2.2 Information Available from Transporters 3-1
3.2.3 Additional Information Sources 3'2
3.3 Waste Sampling 3"22
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CONTENTS (continued)
3.4 Basic Analysis of Waste 3-24
3.5 Supplemental Analysis of Waste 3-28
3.6 Analysis Test Methods 3-29
3.7 Thermal Decomposition Unit Analysis 3-30
3.8 Work Sheet 3-33
3.9 References 3-36
4. INCINERATOR AND AIR POLLUTION CONTROL SYSTEM DESIGN
EVALUATION 4-1
4.1 Introduction 4-1
4.2 Destruction and Removal Efficiency 4-2
4.2.1 Definition 4-2
4.2.2 Sample Calculation 4-3
4.3 Incinerator Evaluation 4-4
4.3.1 Basic Design Considerations 4-6
4.3.1.1 Liquid Injection Incinerators 4-6
4.3.1.2 Rotary Kiln Incinerators 4-7
4.3.2 Physical, Chemical, and Thermodynamic Waste
Property Considerations 4-8
4.3.2.1 Liquid Injection Incinerators 4-8
4.3.2.2 Rotary Kiln Incinerators 4-18
4.3.3 Temperature, Excess Air, Residence Time, and
Mixing Evaluation 4-20
4.3.3.1 Liquid Injection Incinerators 4-21
4.3.3.2 Rotary Kiln Incinerators 4-33
4.3.4 Auxiliary Fuel Capacity Evaluation 4-41
4.3.4.1 Liquid Injection Incinerators 4-41
4.3.4.2 Rotary Kiln Incinerators 4-42
4.3.5 Combustion Process Control and Safety Shutdown
System Evaluation .* 4-43
4.3.5.1 Liquid Injection Incinerators 4-43
4.3.5.2 Rotary Kiln Incinerators 4-44
4.3.6 Construction Material Evaluation 4-46
4.4 Air Pollution Control and Gas Handling System Design
Evaluation 4-47
vi
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CONTENTS (continued)
4.4.1 Emission/Air Pollution Control Device Hatching
Criteria 4-47
4.4.1.1 Particulate Removal 4-51
4.4.1.2 Gaseous Pollutant Removal 4-52
4.4.2 Air Pollution Control Device Design and Operating
Criteria Evaluation 4-54
4.4.2.1 Venturi Scrubbers 4-54
4.4.2.2 Packed Bed Scrubbers 4-58
4.4.2.3 Plate Tower Scrubbers 4-63
4.4.3 Quenching and Hist Elimination Considerations 4-66
4.4.4 Prime Hover Capacity Evaluation 4-68
4.4.5 Process Control and Automatic Shutdown System
Evaluation 4-73
4.4.6 Haterial of Construction Considerations 4-74
4.5 Worksheets 4-75
5. OVERALL FACILITY DESIGN, OPERATION, AND MONITORING 5-1
5.1 Introduction 5-1
5.1.1 Purpose 5-1
5.1.2 Hazardous Waste Incinerator Facility Design 5-2
5.2 Incinerator Facility Site Selection and Operation 5-2
5.2.1 Site Selection Concerns 5-2
5.2.2 Operation of the Facility 5-4
5.2.2.1 Operations Plan 5-4
5.2.2.2 Operations Hanual 5-5
5.2.2.3 Emergency Manual or Handbook 5-5
5.2.2.4 Leak Detection and Repair Plan 5-12
5.2.2.5 Hazardous Chemical Spill Handling Plan .... 5-12
5.2.2.6 Facility Security 5-14
5.2.2.7 Operator Practices and Training 5-14
5.2.2.8 Loss Prevention Program 5-15
5.3 Waste Receiving Area 5-15
5.3.1 Typical Operations and Layouts 5-16
5.3.2 Laboratory for Waste Verification and/or Characterization 5-17
5.3.3 Liquids Unloading 5-19
5.3.3.1 Safety/Emergency Provisions 5-25
5.3.3.2 Spill and Runoff Containment 5-27
5.3.3.3 Static Electricity Prevention 5-27
vn
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CONTENTS (continued)
5.3.4 Container Unloading 5~29
5.3.5 Bulk Solids Unloading 5-31
5.3.5.1 Mechanical Conveyors 5-31
5.3.5.2 Pneumatic Conveyors 5-32
5.4 Waste Storage Area 5"33
5.4.1 Types of Storage 5"34
5.4.1.1 Liquid Storage 5~34
5.4.1.2 Bulk Solids Storage 5-37
5.4.1.3 Container Storage 5'40
5.4.1.4 Tank Cars 5-40
5.4.2 Segregation of Wastes During Storage 5-40
5.4.3 Safety Provisions for Storage Areas 5-41
5.4.3.1 Fire Safety 5-42
5.4.3.2 Spill/Toxicity Safety 5-42
5.5 Waste Blending and/or Processing Before Incineration 5-47
5.5.1 Waste Compatibilities 5-48
5.5.2 Liquid Feed and Blending Equipment 5-49
5.5.3 Pumps and Piping 5"51
5.5.3.1 Positive-Displacement Pumps 5-53
5.5.3.2 Centrifugal Pumps 5~54
5.5.3.3 Pump Emission Control 5-54
5.5.3.4 Pump and Piping Safety 5-56
5.5.4 Valving and Controls 5'60
5.5.5 Valving and Control Safety Consideration 5-61
5.5.5.1 Safety Shutoffs 5-61
5.5.5.2 Gages, Meters, and Gage Glasses 5-63
5.5.5.3 Operating Controls 5-63
5.5.6 Solids Feeding Equipment 5-65
5.5.6.1 Shredders 5'65
5.5.6.2 Explosion Suppression and Safety Considerations
for Shredders 5"66
5.5.6.3 Feeders 5-67
5.5.6.4 Container Feeding Equipment 5-69
5.5.7 Backup/Redundancy Provisions 5-71
5.5.8 Waste Processing Instrumentation 5-71
5.6 Combustion Process Monitoring 5~72
5.6.1 Temperature Monitoring 5-73
5.6.1.1 Metal Tubes 5-76
viii
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CONTENTS (continued)
5.6.1.2 Ceramic Tubes 5-76
5.6.1.3 Metal-Ceramic Tubes 5-77
5.6.2 Oxygen Monitorinc; 5-77
5.6.3 Gas Flow Measurement 5-77
5.6.3.1 Orifice Plates 5-78
5.6.3.2 Venturi Tubes 5-79
5.6.3.3 Pitot Tubes 5-80
5.6.4 Solid Waste Retention Time and Mixing Characteristics
Information 5-80
5.7 Air Pollution Control Device Inspection and Monitoring .... 5-80
5.7.1 Wet Scrubbers 5-80
5.7.1.1 Temperature 5-80
5.7.1.2 Liquid and Gas Flows 5-80
5.7.1.3 pH 5-81
5.7.1.4 Pressure Drop 5-83
5.7.1.5 Residue Generation 5-83
5.7.2 Fabric Filters 5-87
5.7.2.1 Temperature 5-87
S.I.2.2 Gas Flow and Pressure Drop 5-87
5.7.2.3 Residue Generation 5-88
5.7.3 Electrostatic Precipitators 5-88
5.7.3.1 Rapping Cycle Practice 5-89
5.7.3.2 Temperature, Resistivity, and Gas Moisture
Effects 5-89
5.7.3.3 Applied Voltage (Power Supply Control) .... 5-91
5.7.3.4 Gas Flow 5-92
5.7.3.5 Residue Generation Rate and Dust Removal
Capacity 5-92
5.7.3.6 Internal System Pressure 5-92
5.7.4 Mist Eliminators 5-92
5.7.4.1 Temperature 5-93
5.7.4.2 Gas Flow and Pressure Drop 5-93
5.7.4.3 pH Level 5-93
5.7.4.4 Maintenance 5-93
5.8 Scrubber Waste Stream Treatment Inspection and Monitoring. . . 5-93
5.8.1 Flow Measurement and Monitoring 5-93
5.8.2 Flow Control 5-94
5.8.3 pH Monitoring 5-94
5.8.4 pH Control Systems 5-95
5.8.4.1 On-Off Controller 5-95
ix
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CONTENTS (continued)
5.8.4.2 Proportional Controller ............ 5~95
5.8.4.3 Resetting Derivative Controller ........ 5-95
5.8.4.4 Flow Proportional Controller ......... 5-95
5.8.5 Scrubber Solution pH Control .............. 5"95
5.9 Continuous Monitoring Instrumentation for Gaseous Components . 5-97
5.9.1 Available Systems ................... 5"97
5.9.1.1 Extractive Systems .............. 5-99
5.9.1.2 In-Situ Monitoring Systems .......... 5-103
5.9.2 Analyzers ....................... 5"104
5.9.2.1 NDIR Analyzers ................ 5-104
5.9.2.2 Nondispersive Ultriviolet Analyzers (NDUV) . . 5-105
5.9.2.3 Polarographic Analyzers ............ 5-106
5.9.2.4 Electrocatalytic Oxygen Analyzers ....... 5-106
5.9.2.5 Paramagnetic Oxygen Analyzers ......... 5-107
5.10 Plant Condition Monitoring Systems .............. 5'110
5.10.1 Machine Vibratory Signature Analysis ......... 5-110
5.10.2 High Frequency Acoustic Emission Analysis ...... ^-UQ
5.11 Scrubber/Quench Water and Ash Handling ............ 5~ln
5.11.1 Description of Potential Incinerator Wastes ..... 5-111
5.11.1.1 Quench Water ................ 5-111
5.11.1.2 Scrubber Effluents ............. f 110
5.11.1.3 Ash .................... 5'119
5.11.2 Sampling and Analysis of Quench/ Scrubber Water and Ash 5-120
5 ill. 3 Handling of Quench/Scrubber Wastewater ........ 5-121
5.11.4 Handling of Ash ................... 5"123
5.12 Fugitive Emissions ...................... 5-123
5.12.1 Significance of Observed Emissions .......... 5-123
5.12.2 Fugitive Emission Control .............. ~
5.12.3 Fugitive Emission Measurement Devices and Methodology
5.12.3.1 Area Monitoring .............. 5-127
5.12.3.2 Fixed-Point Monitoring ........... 5-127
5.12.3.3 Source Monitoring ............. ="177
5.12.3.4 Current Instrumentation .......... 5-127
c_i 28
5.13 Materials of Construction .................. 3
5.13.1 Metals ........................
5.13.2 Nonmetallics .....................
5.14 Miscellaneous Concerns .................... 5-136
5.14.1 Personnel Health and Safety ............. 5"136
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CONTENTS (continued)
5.14.2 Facility Housekeeping 5-137
5.14.3 Maintenance 5-138
5.14.4 Firefighting/Emergency Personnel and Equipment. . . . 5-140
5.14.5 Stornwater Diversion 5-141
5.15 Technical Assistance 5-142
5.16 References 5-142
6. ESTIMATING INCINERATION COSTS
(This Chapter was Undergoing Revisions at the
Time of Publication of this Document. A Revised
Chapter 6 will be Available Upon request at a
Later Date.)
Appendices
A. Subject Index
B. Glossary of Terms
C. Conversion Factors
D. Bibliography
E. Laboratory-Scale Thermal Decomposition Analytical Data
F. Trial Burn Summaries
-xi
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Reserved for Chapter Six
XII
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LIST OF FIGURES
Number
2-1 Packed tower pressure drop as function of gas rate
and liquid rate 2"32
3-1 Field sampling chain of custody form 3-25
3-2 Decomposition of hexachlorobiphenyl 3-31
3-3 Decomposition of pentachlorobiphenyl in different gaseous
atmospheres
3-31
3-4 Effect of oxygen content on decomposition of
pentachlorobiphenyl ...................... 3-32
3-5 Decomposition profile of hexachlorobenzene ............ 3-32
4-1 Incinerator design evaluation criteria .............. 4-5
4-2 High heat release burner for combustion of liquid waste ..... 4-6
4-3 Internal mix nozzle ....................... 4-9
4-4 External mix nozzles ....................... 4-9
4-5 Sonic atomizing nozzle ...................... 4"10
4-6 Equilibrium constant versus temperature ............. 4-15
4-7 Relationship between activation energy and heat of combustion . . 4-16
4-8 Heat of combustion of chlorinated hydrocarbons .......... 4-17
4-9 Energy balance for combustion chamber .............. 4-23
4-10 Enthalpy balance for combustion processes ............ 4-24
4-11 Logic diagram for air pollution control and gas handling
system design ......................... 4"4^
4-12 Pressure drop versus cut diameter for gas-atomized scrubber
systems. (Experimental data from large Venturis, other
gas atomizers, scrubbers, and mathematical model. ) ....... 4-57
xiii
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Number
4-13 Pipe flow chart 4"70
4-14 Total frictional pressure drops in 90° bends 4~71
4-15 90° bends (a) smooth bend, (b) segmental bend 4'71
5-1 Typical incinerator facility layout 5'3
5-2 Spill-response diagram illustrating the interrelating
information available, decisions to be taken, and
improvements needed 5~13
5-3 Flow diagram showing handling procedures for incineration
of hazardous wastes 5"16
5-4 Layout for liquid receiving area 5"17
5-5 Typical tank trailer (car) with parts identified 5-20
5-6 Typical tank car with parts identified 5-21
5-7 Tank car unloading station 5"21
5-8 Bonding and grounding of a flammable liquid tank truck
and loading rack
5-9 Compressed inert gas transfer method 5-24
5-10 Fail-safe transfer line for hazardous fluids 5-24
5-11 Fail-safe transfer line inlet and outlet assemblies 5-25
5-12 Containment curb type spill catchment system, depressed
area form
5-13 & tank car unloading siding showing rail joint bonding,
insulated track joint, detail, and track grounding 5-28
5-14 Fluidizing outlets for hopper cars 5-31
5-15 Diagram of pneumatic railcar unloading 5'33
5-16 Typical shapes for storage vessels 5-35
5-17 Typical tank condenser vent system 5"36
5-18 Dike drain detail Type "A" diversion box 5'46
5-19 Compatibility matrix for neutralized hazardous wastes 5-49
xiv
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Number
5-20 Compatibility matrix when wastes cannot be neutralized 5-49
5-21 Example of a baffled mixing vessel 5-50
5-22 Slurry injection and monitoring system 5-50
5-23 Liquid feed system with redundant recirculation 5-51
5-24 Pump classification chart 5-52
5-25 Reciporacting pumps: (a) Principle of reciprocating pump,
(b) principle of fluid-operated diaphragm pump, (c) direct-
acting steam pump, (d) principle of mechanical diaphragm
pump, (e) piston-type power pump, (f) plunger-type power
pump with adjustable stroke, (g) inverted, vertical,
triplex power pump 5-53
5-26 Rotary pumps: (a) External-gear pump, (b) internal-gear
pump, (c) three-lobe pump, (d) four-lobe pump, (e) sliding-
vane pump, (f) single-screw pump, (g) swinging-vane pump,
(h) cam or roller pump, (i) cam-and-piston pump, (j) three-
screw pump, (k) shuttle-block pump, (1) squeegee pump,
(m) neoprene vane pump 5-54
5-27 Centrifugal pumps: (a) Principle of centrifugal-type pump,
(b) radial section through volute-type pump, (c) radial
section through diffuser-type pump, (d) open impeller,
(e) semi-enclosed impeller, (f) closed impeller, (g)
nonclog impeller 5-55
5-28 Two safeguards for piping of highly toxic liquids 5-58
5-29 Three areas of a typical gate valve that can leak and result
in fugitive emissions 5-61
5-30 Cross-section through a nonreversible horizontal shredder .... 5-66
5-31 Continuous feeding of sludge to fluid bed incinerator 5-69
5-32 Continuous type containerized toxic material thermal
disposal process 5-70
5-33 Liquid waste incinerator schematic 5-71
5-34 Recommended temperature measurement points 5-74
5-35 Recommended measurement and inspection locations 5-88
5-36 Typical vibratory rapper 5-90
xv
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Number
5 — 50
5-37 Recommended measurement location
5-38 Power supply system for modern precipitators 5'91
5-39 Elements of a typical pH control system 5'96
5-40 Two-step neutralization flow schematic 5'97
5-41 Elements of pollutant monitoring system 5'98
5-112
5-42 Various quenching devices
5-43 Generalized schematic of incinerator facility 5'114
5-44 Schematic of rotary kiln facility with quench spray
chamber and venturi scrubber 5~1Jl*
5-45 Single-pass scrubber system 5"11
5-46 Recirculating scrubber system 5"117
5-47 Incineration system with two-stage scrubber 5'119
5-48 Incineration system with three-stage scrubber S-120
5-49 Incineration process with emissions treatment and
disposal options
5-50 Possible process leakage areas 5~12
6-1 Total capital investment for a rotary kiln incinerator 6-3
6-2 Total capital investment for a liquid injection incinerator ... 6-4
6-3 Total annual operating cost for a rotary kiln incinerator .... 6-5
6-4 Total annual operating cost for a liquid injection ^
incinerator
6-8
6-5 Installed cost of dry centrifugal collectors
6-6 Installed cost of wet collectors 6"
6-7 Installed cost of fabric filters 6"10
6-8 Installed cost of high voltage electrostatic precipitator .... 6-11
6-9 Installed cost of low voltage electrostatic precipitators .... 6-12
xvi
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Number
6-10 Theoretical operating and maintenance costs for dry
centrifugal collectors 6-16
6-11 Theoretical operating and maintenance costs for wet collectors. . 6-17
6-12 Theoretical operating and maintenance costs for fabric filters. . 6-18
6-13a Theoretical operating and maintenance costs for high voltage
electrostatic precipitators 6-20
6-13b Theoretical operating and maintenance costs for low voltage
electrostatic precipitators 6-21
6-14 Theoretical operating and maintenance costs for afterburners. . . 6-22
6-15a Capacity vs. installed cost for a fan 6-24
6-15b Capacity vs. installed cost for a steam boiler 6-24
6-15c Capacity vs. installed cost for an incinerator 6-25
xvii
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LIST OF TABLES
Number
1-1 ENGINEERING HANDBOOK FOR HAZARDOUS WASTE INCINERATION -
CHAPTERS AND THEIR CONTENT
2-1 PERTINENT INCINERATION PROCESSES AND THEIR TYPICAL
OPERATING RANGES
2-2 APPLICABILITY OF AVAILABLE INCINERATION PROCESSES TO
INCINERATION OF HAZARDOUS WASTE BY TYPE *'*
3-1 HAZARDOUS WASTES RATED AS GOOD, POTENTIAL, OR POOR CANDIDATES
FOR INCINERATION BY APPROPRIATE TECHNOLOGIES J"*
4-1 KINEMATIC VISCOSITY AND SOLIDS HANDLING LIMITATIONS OF
VARIOUS ATOMIZATION TECHNIQUES
4-2 EVALUATION PROCEDURE FOR PHYSICAL WASTE PROPERTY/
ATOMIZATION TECHNIQUE COMPATIBILITY
4-3 STOICHIOMETRIC OXYGEN REQUIREMENTS AND COMBUSTION PRODUCTS ^^
YIELDS
4-4 CHEMICAL AND THERMODYNAMIC WASTE PROPERTY EVALUATION ^^
PROCEDURE
4-5 TEMPERATURE/EXCESS AIR EVALUATION PROCEDURE 4'30
4-6 GAS RESIDENCE TIME EVALUATION PROCEDURE 4'32
4-33
4-7 MIXING EVALUATION PROCEDURE
4-8 TEMPERATURE/EXCESS AIR EVALUATION PROCEDURE FOR ROTARY
KILN/AFTERBURNER INCINERATORS
4-9 KILN RETENTION TIME EVALUATION PROCEDURE 4'40
4-10 LIQUID INJECTION INCINERATOR COMBUSTION PROCESS CONTROL ^g
EVALUATION PROCEDURE
4-11 ROTARY KILN INCINERATOR COMBUSTION PROCESS CONTROL ^g
EVALUATION PROCEDURE
4-12 GENERAL CHARACTERISTICS OF SILICA AND ALUMINO-SILICATE ^^
REFRACTORY BRICK
xviii
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Number
4-13 PROCEDURE TO COMPARE PARTICULATE REMOVAL REQUIREMENTS WITH
PROPOSED CONTROL STRATEGIES 4-52
4-14 PROCEDURE TO COMPARE GASEOUS POLLUTANT REMOVAL REQUIREMENTS
WITH PROPOSED CONTROL STRATEGIES 4-54
4-15 VENTURI SCRUBBER DESIGN EVALUATION PROCEDURE 4-58
4-16 TYPICAL VALUES OF K a 4-60
9
4-17 PACKING DEPTH REQUIRED TO ACHIEVE SPECIFIED REMOVAL
EFFICIENCY 4-60
4-18 PACKED BED SCRUBBER EVALUATION PROCEDURE 4-63
4-19 MURPHREE VAPOR PHASE EFFICIENCY FOR PLATE TOWERS 4-64
4-20 PLATE TOWER SCRUBBER EVALUATION PROCEDURE 4-66
4-21 SUDDEN CONTRACTION-LOSS COEFFICIENT FOR TURBULENT FLOW 4-72
4-22 PRIME MOVER CAPAPCITY EVALUATION PROCEDURE 4-73
5-1 HAZARDOUS WASTE INCINERATOR MALFUNCTIONS AND REMEDIAL OR
EMERGENCY RESPONSES 5-6
5-2 TYPICAL STEEL DRUM SPECIFICATION FOR HAZARDOUS MATERIALS 5-30
5-3 TYPES AND CHARACTERISTICS OF DRY BULK STORAGE 5-37
5-4 MATERIALS OF CONSTRUCTION FOR POSITIVE DISPLACEMENT PUMPS .... 5-52
5-5 FEEDERS FOR BULK MATERIALS 5-68
5-6 LIMITS OF ERROR FOR THERMOCOUPLES 5-75
5-7 DEVICES FOR LIQUID FLOW MEASUREMENT 5-82
5-8 A GUIDE TO PRESSURE SENSING ELEMENT SELECTION 5-84
5-9 ANALYZERS CAPABLE OF MEASURING GASEOUS COMPONENTS 5-99
5-10 INFRARED BAND CENTERS OF SOME COMMON GASES 5-105
5-11 EXTRACTIVE MONITOR SUMMARY 5-108
5-12 IN-SITU MONITOR SUMMARY 5-109
5-13 OXYGEN ANALYZER SUMMARY 5-109
5-14 POTENTIAL AIR POLLUTANTS FROM HAZARDOUS WASTE INCINERATION. . . . 5-115
xix
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Number
5-15 SCRUBBER WATER AND WASTE PARAMETERS FOR TWO LAND-BASED LIQUID
INJECTION INCINERATORS 5"119
5-16 SCRUBBER WATER QUALITY 5"118
5-17 POSSIBLE SOURCES OF FUGITIVE EMISSIONS FROM HAZARDOUS WASTE
INCINERATOR SYSTEMS 5~124
5-18 CONTROL ALTERNATIVES FOR FUGITIVE DUST 5"126
5-19 BRAND NAMES OF POLYMERIC MATERIALS 5'133
5-20 PROPERTY COMPARISONS - NATURAL AND SYNTHETIC RUBBERS 5-134
5-21 PROPERTIES OF COMMERCIALLY AVAILABLE PLASTICS 5-135
6-1 ANNUAL MAINTENANCE COSTS FOR ALL GENERIC TYPES OF CONTROL
DEVICES
6-2 MISCELLANEOUS COST AND ENGINEERING FACTORS 6'15
6-3 HOURLY FUEL COSTS 6"19
6-4 MATERIAL COST FACTORS 6"23
6-5 TRIAL BURN COST ASSUMPTIONS 6"27
xx
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ACKNOWLEDGEMENT
The preparation of Engineering Handbook for Hazardous Waste Incineration
required a major, well-orchestrated effort by numerous individuals inside and
outside the Agency. The accelerated nature of the effort necessitated the
employment of individuals from six EPA organizations and the utilization of
contractor support for the actual composition of the technical materials. The
EPA personnel had to serve as the technical critique committee for this effort,
even as they were forced to carry their own regular work load. The following
EPA organizations contributed staff to work with the Honsanto Research Corpor-
ation, A. D. Little, Inc., and TRW, Inc., in the preparation of this manual:
Municipal Environmental Research Laboratory. Cincinnati
Industrial Environmental Research Laboratory, Cincinnati
Industrial Environmental Research Laboratory,
Research Triangle Park, NC
Office of Solid Waste
Region II, New York, NY
Region V, Chicago, IL
The authors would like to express their most sincere thanks to the above
groups and to their dedicated staff, who produced this document in a genuine
team effort.
MONSANTO RESEARCH CORPORATION
Dayton Laboratory
Dayton, Ohio 45407
xxi
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CHAPTER 1
INTRODUCTION
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CHAPTER 1
INTRODUCTION
Lons of tons of industrial waste materials are generated each y^ in the
>d States A sizable fraction of this waste is considered hazardous (an
"nated 57 million metric tons in 1980). In recent years, incineration has
ged as an attractive potential alternative to hazardous waste disposal
ads such as landfill, ocean dumping, and deep-well injection.
leration possesses several advantages as a hazardous waste disposal
nology:
- Toxic components of hazardous wastes can be converted to harmless
compounds or, at least, to less harmful compounds.
- Incineration provides for the ultimate disposal of hazardous wastes,
eliminating the possibility of problems resurfacing in the future.
-he volume of hazardous waste is greatly reduced by incineration.
- Heat recovery makes it possible to recover some of the energy
produced by the combustion process.
s likely that incineration will be a principal technology for the dis-
1 of hazardous waste in the future because of the above advantages.
engineering handbook is a compilation of information available in the
rature and describes current state-of-the-art technology for the incin-
ion of hazardous waste. The handbook is designed to serve as a technical
mrce document in the evaluation of hazardous waste incineration operations.
. document is intended to serve as a useful technical resource for Federal,
onal, and state EPA officials; designers of hazardous waste incineration
Cities, owners and operators of hazardous waste incineration facilities,
the general technical community.
i chapter in the handbook addresses a separate topic involved in hazardous
:e incineration. A brief abstract for each chapter is presented in
Le 1-1.
user is encouraged to make use of the references cited in each chapter
additional information is required.
1-1
-------
TABLE 1-1. ENGINEERING HANDBOOK FOR HAZARDOUS WASTE
INCINERATION - CHAPTERS AND THEIR CONTENT
Introduction
Describes the utility of the handbook. Details the structure of the
handbook, specifying where various types of information are
available.
Current Practices
Contains basic and general information about the nature and op««-
Sons of the various^ incinerators and air pollution control devices
currently used in hazardous waste disposal. Subject matter includes
process descriptions, diagram, general operating Parameters and
process advantages and disadvantages. An overview of emerging
incineration technologies is included.
Waste Characterization
Describes the basic waste analysis required to characterize wastes
and Sscusses how this information is used to match the ««te to an
annrooriate incinerator design and determine operating conditions.
Hazardous wastes listed undeletion 3001 of the RCRA regulations
are evaluated as to their suitability for incineration.
tneinerator and Air Pollution Control System Design Evaluation
Provides detailed information and procedures for evaluation of in-
cinerator and air pollution control device design and operating con
dUions Basically^ this involves a series of internal consistency
cnecks designed todetermine whether (1) acceptable temperatures
residenceiimes, oxygen concentrations, and mixing can be achieved
nd maintained in Se incinerator, (2) the various componen s of the
system have sufficient capacity to accommodate fche quantities of
waste to be burned, (3) appropriate air pollution control device
operating conditions can be maintained, (4) the design includes
process control and automatic shutdown safeguards to minimize re-
lease of hazardous materials in the event of equipment """J^.
and (5) proper materials of construction are used. Individual eval
uation procedures are provided for liquid in3ection and rotary kiln
incinerators, and for several types of wet scrubbers.
(continued)
1-2
-------
TABLE 1-1 (continued)
Chapter Abstract
Overall Facility Design, Operation, and Monitoring
Provides engineering bachground information on the technical capa-
bilities necessary for the incineration facility to process hazard-
ous waste safely and effectively. The chapter discusses overall
facility layouts; equipment requirements common to all facilities;
waste receiving equipment, procedures, and storage; personnel
safety; emergency procedures and provisions; monitoring procedures
and instrumentation; sampling and analysis equipment and methodolo-
gies; sources of fugitive emissions and their control; scrubber/
quench water handling and disposal; and ash collection systems.
Estimating Incineration Costs
Examines the economic factors involved in the construction of new
facilities and the operation of existing facilities. Capital costs
for incinerators and air pollution control devices are discussed.
The costs involved in changing incinerator operating conditions
(temperature, percent excess air, residence time) and the removal
efficiency of air pollution control devices are examined. The
costs involved in performing trial burns are also addressed in this
chapter.
Appendices
Provide a subject index, glossary of terms, tables of conversion
factors, bibliography, and summaries of incineration data. In-
cluded in the summaries are: results of University of Dayton
laboratory-scale experiments, and pilot-scale test results.
1-3
-------
CHAPTER 2
CURRENT PRACTICES
-------
CONTENTS
... 2-1
2. CURRENT PRACTICES
.... 2-1
2.1 Introduction
2.2 Commercially Available Hazardous Waste Incineration ^
Technologies
2.2.1 Rotary Kiln 2.8
2.2.2 Liquid Injection 2_n
2.2.3 Fluidized Bed 2-14
2.2.4 Multiple Hearth 2_18
2.2.5 Coincineration
2.3 Emerging Hazardous Waste Incineration Technology 2~20
2.3.1 Starved Air Combustion/Pyrolysis 2"2
2-23
2.4 Air Pollution Control Devices (APCD)
2.4.1 Afterburners • • • • • • • 2-27
2.4.2 Gas-Atomized Spray Scrubber (Venturi) 2_3Q
2.4.3 Packed Bed Scrubber 2_34
2.4.4 Spray Tower 2.36
2.4.5 Plate Scrubber. - - : • • • • ; 2.39
2.4.6 Electrostatic Precipitator (ESP). 2_42
2.4.7 Wet Electrostatic Precipitator (WEP)
.... 2-44
2.5 References
-------
CHAPTER 2
CURRENT PRACTICES
2.1 INTRODUCTION
Incineration has developed over a number of years as a means of disposing of
various types of waste materials. Recently, the application of incineration
to hazardous waste has been given much attention. From an environmental
standpoint incineration can be the best method of disposing of certain hazard-
ous wastes. Incineration of hazardous wastes does not necessarily have to be
carried out at land-based facilities. Shipboard incineration has been used to
dispose of chlorinated hydrocarbon wastes. The U.S. Environmental Protection
Agency estimates that in 1979 only 5% of the country's total hazardous waste
stream was managed by incineration. However, approximately 60% of all the
hazardous material can be incinerated successfully [1, 2].
The EPA estimates that in 1979 about 39 million short tons (35 million metric
tons) of hazardous wastes were generated in this country by some 270,000
industrial plants and other facilities. The majority of these wastes (65%)
were produced in ten states: Texas. Ohio, Pennsylvania, Louisiana, Michigan,
Indiana. Illinois, Tennessee. West Virginia, and California. It is expected
that the quantities of hazardous waste generated will increase annually by 3«.
Based on these figures, incineration is becoming increasingly more important
in solving waste problems [3, 4].
Incineration is an engineered process that uses thermal decomposition via oxi-
dation to convert a waste to a less bulky, toxic, or noxious material. A
waste must be combustible for incineration to be an applicable disposal
means [5] Two important operating conditions for proper incineration are
temperature and residence time. These conditions vary with a waste's chemical
structure, physical form, and type of incinerator. Table 2-1 summarizes the
typical ranges for the two operating conditions mentioned above in six inciner-
ation processes. Other important parameters, oxygen availability and adequate
mixing, are covered in Chapter 4. Table 2-2 presents a summary of those
physical forms suitable for the six technologies.
The following technologies are covered in this chapter: rotary kiln, liquid
injection fluidized bed, multiple hearth, coincineration, and starved air
combustion/pyrolysis. The first five technologies mentioned are presented in
Section 2 2 Commercially Available Hazardous Waste Incineration Technologies.
The other technology, starved air combustion/pyrolysis. appears in Section 2.3,
Emerging Hazardous Waste Incineration Technology. Rotary kiln and liquid
injection are at present the most highly developed and most commonly used in-
cinerators for hazardous waste incineration. Both exist throughout the United
2-1
-------
TABLE 2-1. PERTINENT INCINERATION PROCESSES AND THEIR TYPICAL
OPERATING RANGES [6]
Process
Temperature
range. °F (°C)
Residence time
Rotary kiln
Liquid injection
Fluidized bed
Multiple hearth
Coincineration
Starved air combustion/pyrolysis
1,500 to 2,900
(820 to 1,600)
1,200 to 2,900
(650 to 1,600)
840 to 1,800
(450 to 980)
Drying zone
600 to 1.000
(320 to 540)
Incineration
1,400 to 1,800
(760 to 980)
300 to 2,900
(150 to 1,600)
900 to 1,500
(480 to 820)
Liquids and gases, seconds;
solids, hours
0.1 to 2 seconds
Liquids and gases, seconds;
solids, longer
0.25 to 1.5 hours
Seconds to hours
Tenth of a second to
several hours
aA highly developed hazardous waste incineration technology; covered in detail
in Chapter 4.
2-2
-------
TABLE 2-2. APPLICABILITY OF AVAILABLE INCINERATION PROCESSES TO INCINERATION OF HAZARDOUS WASTE BY
TYPE |61
Rotary Liquid Fluidized Multiple
Waste type kiln injection bed hearth Coincineration
Solids:
Granular, homogeneous X XXX
Irregular, bulky
(pallets, etc.) X x
Low melting point _
(tars, etc.) X X X X
Organic compounds with
fusible ash constituents X XX
Unprepared, large, bulky
material X
Gases: d d vd vd yd
Organic vapor laden XX X A
Liquids :
High organic strength
aqueous wastes often
toxic X* X X *
Organic liquids X X X
Solids/ liquids:
Waste contains halogenated
aromatic compounds f
(2,200°F minimum) XX x
Aqueous organic sludges X X X X
Starved
air combustion/
pyrolysis
X*
xd
A
aSuitable for pyrolysis operation.
Handles large material on a limited basis.
CIf material can be melted and pumped.
dlf properly presented to the incinerator.
flf liquid.
Provided waste does not become sticky upon drying.
-------
States in full-scale operations. Due to their widespread and successful use
in hazardous waste incineration, they are covered in detail in Chapter 4.
Air pollution control devices (APCD) are considered an essential part of most
hazardous waste incineration processes due to the possibility of pollutant
emissions during incineration. Because they are usually an integral part of
the overall incineration design, they are covered in this chapter. Fact
sheets have been developed and precede a detailed description for each inciner-
ation technology and APCD.
2.2 COMMERCIALLY AVAILABLE HAZARDOUS WASTE INCINERATION TECHNOLOGIES
This section deals with available hazardous waste incineration technologies.
Included are fact sheets that contain the information listed in the example
below, in the format illustrated.
_ _ .a
Fact Sheet— G> s» L
Description - Brief discussion of technology.
Flow Diagram -
Status - Discusses the technology's applicability to hazardous waste
incineration.
Wastes -
Wastes previously
incinerated Potential candidates Unlikely candidates
Advantages -
Disadvantages -
References -
aAbbreviations for the types of waste (physical form) applicable to this
technology:
G = gas L = liquid Slg = sludges
S = solid Sly = slurry
2-4
-------
2.2.1 Rotary Kiln
2.2.1.1 Fact Sheet—
sly
Description - The rotary kiln is a cylindrical refractory-lined shell^that is
mounted at a slight incline from the horizontal plane. Rotation of the shell
provides for transportation of the waste through the kiln as well as for
enhanced mixing of the waste with the combustion air. Applicable for
incineration of both liquid and solid hazardous wastes and slurries.
Flow Diagram -
CONVEYOR
FIBER PACKS
SOLID WASTE
FEED CHUTE
WASTE FEED
SAMPII
ASH RESIDUE
SAMPLE
ASHES
KILN EXIT DUCT
APCD
Status - Widespread applicability for hazardous waste incineration. Current
technology used by industrial plants to destroy hazardous waste. At present,
the rotary kiln is a major type of incinerator used in hazardous waste disposal.
Wastes -
Wastes previously incinerated
PCB wastes in capacitors
Obsolete munitions
Obsolete chemical warfare agents
Polyvinyl chloride waste
(GB, VX, and mustard)
2-5
-------
Potential candidates
Compounds containing C, H, 0 Organics containing either phosphorus, silicon,
sodium, sulfur, fluorine,
nitrogen or sulfur Halogenated (bromine, chlorine, iodine) organics
Unlikely candidates
Heavy metals
High-moisture-content waste
Inert material
Inorganic salts
Materials with a high inorganic content; such as: lime sludge from acetylene
production by the carbide method; neutralized acid waste from the manufac-
ture of methyl methacrylate; alkylation sludge containing sulfuric acid from
petroleum refineries; settled sludge from clarification of wastewaters in the
manufacture of paint additives; and lime clay mixtures with absorbed solvents
and resins.
Advantages -
(1) Will incinerate a wide variety of liquid and solid wastes.
(2) Will incinerate materials passing through a melt phase.
(3) Capable of receiving liquids and solids independently or in combination.
(4) Feed capability for drums and bulk containers.
(5) Adaptable to wide variety of feed mechanism designs.
(6) Characterized by high turbulence and air exposure of solid wastes.
(7) Continuous ash removal which does not interfere with the waste oxidation.
(8) No moving parts inside the kiln (except when chains are added).
(9) Adaptable for use with a wet gas scrubbing system.
(10) The retention or residence time of the nonvolatile component can be con-
trolled by adjusting the rotational speed.
(11) The waste can be fed directly into the kiln without any preparation such
as preheating, mixing, etc.
(12) Rotary kilns can be operated at temperatures in excess of 2,500°F
(1,400°C), making them well suited for the destruction of toxic compounds
that are difficult to thermally degrade.
(13) The rotational speed control of the kiln also allows a turndown ratio
(maximum to minimum operating range) of about 50%.
2-6
-------
Disadvantages -
(1) High capital cost for installation. .
(2) Operating care necessary to prevent refractory damage,- thermal shock is a
particularly damaging event. ....
(3) Airborne particles may be carried out of kiln before complete combustion.
(4) Spherical or cylindrical items may roll through kiln before complete
combustion. . . .
(5) The rotary kiln frequently requires additional makeup air due to air leakage
via the kiln end seals.
(6) Drying or ignition grates, if used prior to the rotary kiln, can cause
problems with melt plugging of grates and grate mechanisms.
(7) High particulate loadings.
(8) Relatively low thermal efficiency. .
(9) Problems in maintaining seals at either end of the kiln are a significant
operating difficulty.
References - 6-12
2.2.1.2 Detailed Description—
A typical rotary kiln incineration system used for hazardous waste destruction
includes the following components [7]:
• Waste feed system
• Rotary kiln incinerator
• Auxiliary fuel feed system
• Afterburner
• Air pollution control device system
The rotary kiln is a cylindrical unit mounted on a slight incline. Kiln
dimensions vary with each facility. A typical kiln is 16 ft (5 m) long and
10 ft (3 m) in diameter. Temperatures in the kiln range from l,aOO F to
2 900°F (820°C to 1,600°C). Since rotary kilns are normally totally refractory
lined and have no exposed metallic parts, they can operate at high incinera-
tion temperatures and experience low corrosion. Residence time may vary from
a couple of seconds (gaseous wastes) to a couple of hours (solid wastes).
Afterburners, normally used with rotary kilns, are described in Section 2.4.1.
Batch feeding is common in rotary kiln systems. A typical feed capacity for
solids is 1.300 Ib/hr to 4,400 Ib/hr (600 kg/hr to 2,000 kg/hr). Solid wastes.
sometimes packed in fiber drums, are fed into the rotary kiln by a conveyor.
Liquids and sludges may also be pumped into the kiln. Liquid residues are
typically burned in suspension by atomization with stream or air and have a feed
capacity of 22 ft3/hr to 79 ft3/hr (630 L/hr to 2,250 L/hr). The kiln and the
liquid burner (when used) are equipped with natural gas igniters and gas burners
for initial refractory heatup, flame stability, and supplemental heat, if
necessary [7].
Atmospheric emissions from the combustion of solid and liquid wastes are
generally controlled by a venturi scrubber. Lime is injected to neutralize
the scrubber water. Used scrubber water enters settling ponds where it is
2-7
-------
analyzed and further treated, if necessary, before discharge. Exhaust gases
also pass through absorption trays and a mist eliminator for pollution
control before entering the stack.
2.2.2 Liquid Injection
2.2.2.1 Fact Sheet—
L. Sly. Slq
Description - Liquid injection combustors can be used to dispose of virtually
any combustible liquid waste (liquid, slurries, sludges). The heart of the
liquid injection system is the waste atomization device or nozzle (burner)
which atomizes the waste and mixes it with air into a suspension. Combustion
takes place in the combustion chamber. Atomization is usually achieved either
mechanically using rotary cup or pressure atomization systems, or via gas
fluid nozzles using high-pressure air or steam.
Flow Diagram -
LIQUID WASTE
STORAGE
WASTE
CONDITIONER
SUPPORT FUEL IF REQUIRED
SUPPORT GAS
COMBUSTION AIR
• APCD
NOZZLE
Status - Widespread applicability for hazardous waste incineration. Current
technology used by industrial plants to destroy hazardous waste. At present,
liquid injection is the most commonly used incinerator for hazardous waste
disposal.
Wastes -
Wastes
previously incinerated
Phenols
Still and reactor bottoms
Cyanide and chrome
plating wastes
Polyester paint
Polyvinyl chloride paint
Thinners
Solvents
Off-specification isoprene
PCB's
Separator sludges
Detergent sludges
Digester sludges
Potential candidates
Organic vapor laden gases
Liquid halogenated (chlorine
bromine, iodine) organics
Organic liquids containing
either nitrogen, sulfur
fluorine, phosphorus,
silicon, or sodium
Unlikely candidates
Heavy metals
High-moisture-content
waste
Inert material
Inorganic salts
Material with a high
inorganic content
(see Section 2.2.1
for a more detailed
list)
2-8
-------
Wastes previously incinerated (continued)
Latex paint
Polymers
Resins
Hexachlorocyclopentadiene
Organophosphate pesticides
Waste from polymer polyol production
Dodecyl mercaptan wastes
Fluorinated herbicide wastes
Ethylene glycol manufacture residue
Waste residues from alkyl benzene production
Perchloroethylene manufacture still bottoms
Alkyl and aryl sulfonic acid wastes
Still bottom from acetaldehyde production
Nitrochlorobenzene
Advantages -
(1) Capable of incinerating a wide range of liquid wastes.
(2) No continuous ash removal system is required other than for air pollution
control.
(3) Capable of a fairly high turndown ratio.
(4) Fast temperature response to changes in the waste fuel flowrate.
(5) Virtually no moving parts.
(6) Low maintenance costs.
Disadvantages -
(1) Only wastes which can be atomized through a burner nozzle can be incin-
erated.
(2) Heat content of waste burned must maintain adequate ignition and incinera-
tion temperatures or a supplemental fuel must be provided.
(3) Burners susceptible to pluggage (burners are designed to accept a certain
particle size; therefore, particle size is a critical parameter for
successful operation).
(4) Burner may or may not be able to accept a material which dries and cakes
as it passes through the nozzles.
References - 3, 5, 6, 8, 9, 11-13
2.2.2.2 Detailed Description—
The typical liquid injection incinerator includes the following components:
• Waste burner system
• Auxiliary fuel system
• Air supply system
• Combustion chamber
• Air pollution control device system
2-9
-------
The use of a burner nozzle characterizes liquid injection incinerators. Liquid
wastes are fed and atomized into the combustion chamber through the burner nozzli
Having a large surface area, the atomized particles vaporize quickly, forming
a highly combustible mix of waste fumes and combustion air which ignites and
is combusted as it proceeds through the combustion chamber. Typical combustion
chamber residence time and temperature ranges are 0.5 to 2 seconds and 1,300 F
to 3,000°F (700°C to 1,650°C), respectively. Typical liquid feed rates are as
high'as 200 ft3/hr (5,600 L/hr).
The combustion chamber is a refractory-lined cylinder. Burners are normally
located in the chamber in such a manner that the flames do not impinge on
the refractory walls. The combustion chamber wall can be actively cooled by
process air prior to its entry into the combustion zone, thus preheating the
air to between 300°F (150°C) and 700°F (370°C) .
Liquid waste fuel is transferred from drums into a feed tank. The tank is
pressurized with nitrogen, and waste is fed to the incinerator using a remote
control valve and a compatible flowmeter. The fuel line is purged with N2
after use. A recirculation system is used to mix the tank contents [15J.
Normally a gas (for example, propane) preheats the incinerator system to an
equilibrium temperature of approximately 1,500°F (815«C) before introduction
of the waste liquid.
Atmospheric emissions from the combustion of liquid wastes are often controlled
by a high energy venturi scrubber system. Gases leaving the combustion chamber ^
pass through this scrubber into a separator tank (often equipped with a demister
Quenching the exhaust gas is required before it is sent to the venturi scrubber.
Scrubbing water mixed with a caustic solution is commonly used in the venturi.
Such liquids are injected at the venturi inlet and mixed with the combustion
gas at velocities of approximately 100 ft/s to 400 ft/s (30 to 120 m/s) in the
venturi throat. Spent scrubber water is collected in a separator tank then
usually transferred to a holding tank. The water-saturated, scrubbed effluent
gases are discharged up the stack [14].
2-10
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2.2.3 Fluidized Bed
2.2.3.1 Fact Sheet—
G, S, L. Sly, Slg
Description - The fluidized bed incinerator consists of a refractory-lined
vessel containing inert granular material. Gases are blown through this
material at a rate sufficiently high to cause the bed to expand and act as a
fluid. The gases are injected through nozzles that permit flow up into the
bed and restrict downflow of the bed material. Waste feed, which can be in
any form, enters the reactor either above or within the bed. Preheating of
the bed to startup temperatures is accomplished by a burner located above and
impinging down on the bed.
Flow Diagram -
APCD
WASTE FEED
SAMPU
LIQUID INJECTORS
y 1181
XV";;" KO^V .V"
*"" :-—V-.4'.J!»a*
Status - Has primarily been used for municipal and industrial waste
incineration. Significant potential for hazardous waste incineration.
Wastes -
Wastes
previously incinerated
Off-specification phenol
Waste from toluene
diamine production
from dinitrotoluene
Organic wastes from
pharmaceutical
manufacture
Organic peroxide manufac-
turing wastes
Ethylene bromide manufac-
turing wastes
Methyl methacrylate
Phenol waste
Potential candidates
Halogenated (bromine,
chlo r ine, iodine)
hydrocarbons
Organics containing either
sulfur, nitrogen, phospho-
rus, silicon, fluorine,
or sodium
Unlikely candidates
Heavy metals
High-moisture-content
waste
Inert material
Inorganic salts
Materials with a high
inorganic content
(see Section 2.2.1
for a more detailed
list)
2-11
-------
Wastes previously incinerated (continued)
Araiben® manufacture liquid wastes
Corboryl manufacture waste
Ethylene manufacturing wastes
Tetraethyl orthosilicate wastes
Urethane manufacture wastes
Advantages -
(1) General applicability for the disposal of combustible solids, liquids,
and gaseous wastes.
(2) Simple design concept, requiring no moving parts in the combustion zone.
(3) Compact design due to high heating rate per unit volume (100,000 to
200,000 Btu/hr-ft3 (900,000 to 1,800,000 kg-cal/hr-m3) which results in
relatively low capital costs.
(4) Relatively low gas temperatures and excess air requirements which tend to
minimize nitrogen oxide formation and contribute to smaller, lower cost
emission control systems.
(5) Long incinerator life and low maintenance costs.
(6) Large active surface area resulting from fluidizing action enhances
the combustion efficiency.
(7) Fluctuation in the feed rate and composition are easily tolerated due to
the large quantities of heat stored in the bed.
(8) Provides for rapid drying of high-moisture-content material, and combus-
tion can take place in the bed.
(9) Proper bed material selection suppresses acid gas formation,- hence,
reduced emission control requirements.
(10) Provides considerable flexibility for shockload of waste; i.e., large
quantities of waste being dumped in the bed at a single time.
Disadvantages -
(1) Difficult to remove residual materials from the bed.
(2) Requires fluid bed preparation and maintenance.
(3) Feed selection must avoid bed degradation caused by corrosion or
reactions.
(4) May require special operating procedures to avoid bed damage.
(5) Operating costs are relatively high, particularly power costs.
(6) Possible operating difficulties with materials high in moisture content.
(7) Formation of eutectics is a serious problem.
(8) Hazardous waste incineration practices have not been fully developed.
(9) Not well suited for irregular, bulky wastes, tarry solids, or wastes with
a fusible ash content.
References - 6, 8, 9, 11-13, 15, 16
2-12
-------
2.2.3.2 Detailed Description—
A representative fluidized bed reactor will have the following basic system
components [16]:
• Fluidized bed reactor
• Fluidizing air blower
• Waste feed system
• Auxiliary fuel feed system
• Air pollution control device system
A typical reactor has an inside diameter of 26 ft (8 m) and an elevation of
33 ft (10 m). Silica beds are commonly used and have a depth of 3 ft(l m) at
rest and extending up to 6.5 ft (2 m) in height when fluidizing air is passed
through the bed. Waste and auxiliary fuel are injected radially into the bed
and reacted at temperatures from 840°F to 1,500°F (450°C to 810°C). Further
reaction occurs in the volume above the bed at temperatures up to 1,800°F
(980°C). A typical residence tine for liquid hazardous waste is 12 to 14
seconds [16].
Reactor heat release rates of up to 15 million kcal/hr and, waste, input feed
rates of up to 48 ft3/hr (1,360 L/hr) for liquids over 10,000 Btu/lb (5,560
kcal/kg) in heat content, and up to 270 ft3/hr (7,570 L/hr) for liquids with a
heat content of 3,000 Btu/lb (1,670 kcal/kg), are reported [16].
Liquid wastes can be pumped directly from a tank truck into the reactor by a
recirculating pump system. Wastes are injected radially into the reactor bed
through a nozzle. Flow rates are determined by recording waste liquid level
changes in the calibrated tanker as a function of time [16].
Auxiliary fuel is often fed radially into the bed through a number of bed
nozzles manifolded around the reactor circumference [16].
Atmospheric emissions from the combustion of liquid hazardous wastes have been
controlled by a venturi scrubber. Recirculating water is injected into the
venturi to scrub particulate matter from the combustion gas stream and quench
the gas temperature from 1,500°F to 175°F (~820°C to *80°C) prior to emission
into the atmosphere through the stack. Spent scrubber liquid is sent to a
wastewater treatment plant for processing [16].
2-13
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2.2.4 Multiple Hearth
2.2.4.1 Fact Sheet—
S, Slg
Description - A typical multiple hearth furnace includes a refractory-lined
steel shell, a central shaft that rotates, a series of solid flat hearths, a
series of rabble arms with teeth for each hearth, an air blower, fuel burners
mounted on the walls, an ash removal system, and a waste feeding system. Side
ports for tar injection, liquid waste burners, and an afterburner may also be
included.
Sludge and/or granulated solid combustible waste is fed through the furnace
roof by a screw feeder or belt and flapgate. The rotating air-cooled central
shaft with air-cooled rabble arms and teeth plows the waste material across
the top hearth to drop holes. The waste falls to the next hearth and then
the next until discharged as ash at the bottom. The waste is agitated as it
moves across the hearths to make sure fresh surface is exposed to hot gases.
Flow Diagram -
RETURN AIR
SOLID
WASTE FEED
BUCKET ELEVATOR
—* i APCD
HAULING
\
^
FUEL
BURNERS
(LIQUID AND
GASEOUS
WASTE)
COOLING AIR FOR RABBLE
ARMS AND DRIVE SHAFTS
Status - This technology has moderate applicability for hazardous waste in-
cineration. A pilot-scale study has been conducted (jointly incinerating PCB's
and sewage sludge) [12].
2-14
-------
Potential candidates
Halogenated (bromine, chlorine,
iodine) organic solids or
sludges
Organic solids or sludges con-
taining either sodium, silicon,
sulfur, phosphorus, nitrogen,
or fluorine
Wastes -
Wastes previously incinerated
Isophthalic acid and terephthalic acid
still bottoms
Solid residue from manufacture of
aromatic amines
Reactor bottoms from PVC manufacture
Chemical sludge
Oil refinery sludge
Pharmaceutical wastes
Still bottoms
Unlikely candidates
Heavy metals
Inert materials
Inorganic salts
Materials with a high inorganic
content (see Section 2.2.1
for a more detailed list)
Advantages -
(1) The retention or residence time in multiple hearth incinerators is usually
higher for low volatile material than in other incinerator configurations.
(2) Large quantities of water can be evaporated.
(3) A wide variety of wastes with different chemical and physical properties
can be handled.
(4) Multiple hearth incinerators are able to utilize many fuels including
natural gas, reformer gas, propane, butane, oil, coal dust, waste oils,
and solvents.
(5) Because of its multizone configuration, fuel efficiency is high and
typically improves with the number of hearths used.
(6) Fuel burners can be added to any of the hearths to maintain a desired
temperature profile.
(7) Multiple hearth incinerators are capable of a turndown ratio of 35%.
(8) High fuel efficiency is allowed by the multizone configuration.
Disadvantages -
(1) Due to the longer residence times of the waste materials, temperature
response throughout the incinerator when the burners are adjusted is
usually very slow.
(2) It is difficult to control the firing of supplementary fuels as a result
of this slow response.
(3) Maintenance costs are high because of the moving parts (rabble arms, main
shaft, etc.) subjected to combustion conditions.
2-15
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Disadvantages - (continued)
(4) Multiple hearth incinerators are susceptible to thermal shock resulting
from frequent feed interruptions and excessive amounts of water in the
feed. These conditions can lead to early refractory and hearth
(5) If used to dispose of hazardous wastes, a secondary combustion chamber
probably will be necessary and different operating temperatures might be
(6) NoTwell suited for wastes containing fusible ash. wastes which require
extremely high temperature for destruction, or irregular bulky solids.
References - 1, 3, 6, 8, 11-13
2.2.4.2 Detailed Description— .
The multiple hearth incinerator (commonly called Herreshoff furnace) is a
flexible unit which has been utilized to dispose of sewage sludges, tars,
solids gases, and liquid combustible wastes. This type of unit was initially
designed to incinerate sewage plant sludges in 1934. In 1968 there were over
125 installations in operation with a total capacity of 17,000 tons/d (wet
basis) for this application alone [3].
Furnaces range from 6 ft to 25 ft (1.8 m to 7.6 m) in diameter and from 12 ft
to 75 ft (3.6 m to 23 m) in height. The diameter and number of hearths are
dependent on the waste feed, the required processing time, and the type of
thermal processing employed. Generally, the uppermost hearth is used as an
afterburner. Normal incineration usually requires a minimum of six hearths,
while pyrolysis applications require a greater number [6J.
Normally, waste material enters the furnace by dropping through a feed port
located in the furnace top. Rabble arms and teeth, attached to a vertically
positioned center shaft, rotate counterclockwise to spiral the w?st%?c"«rth
the face of the hearth to the drop holes. The waste drops from hearth to hearth
through alternating drop holes located either along the periphery of the hearth
or adjacent to the central shaft. Ultimately, the residual ash falls to the
furnace floor. Air and combustion products flow countercurrently to the feed
from the bottom to the top of the combustion chamber [6].
The rabble arms and teeth located on the central shaft all rotate in the same
direction; additional agitation of the waste (back rabbling) is accomplished
by reversing the angles of the rabble teeth. Waste retention time is con-
trolled by the design of the rabble tooth pattern and the rotational speed of
the central shaft [3].
Liquid and/or gaseous combustible wastes may be injected into the unit through
auxiliary burner nozzles. This utilization of liquid and gaseous waste repre-
sents an economic advantage because it reduces secondary fuel requirements,
thus lowering operating costs [3].
One coincineration study conducted demonstrated that DDT and 2 4 5-T could
be destroyed in a multiple hearth incinerator. DDT powder (75< AI). DDT in
2-16
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kerosene (20% AI), and Weedon® solution (20% 2,4,5-T), were incinerated in a
30 in. (76 cm) six-hearth pilot-scale furnace. The pesticides were mixed with
sludge containing about 20% by weight solids in the ratio of 0.02 g/g pesticides
to sludge. Incineration was conducted on all the pesticides with the afterburner
at 1,400°F (760°C), at 1,7508F (955°C), and shut off. Results showed that the
destruction efficiencies of 2,4,5-T were above 99.95% with and without the
afterburner operating. In almost all cases the highest pesticide losses
(including DDT, ODD, DDE, and 2,4,5-T) were in the scrubber water. No tetra-
chlorodioxin was detected in the 2,4,5-T formulation or in the incinerator
off-gas [13].
The report concluded that DDT and 2,4,5-T can be safely destroyed by coincin-
eration with sewage sludge in a multiple hearth furnace and that the internal
hearth temperatures should be maintained in excess of 1,000°F to 1,100°F
(550°C to 600°C) in order to minimize the formation of DDE [13]. Additional
information on coincineration is given in Section 2.2.5.
2-17
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2.2.5 Coincineration
2.2.5.1 Fact Sheet— L, S, Sly, Slg
Description - Coincineration generally refers to the joint incineration of
hazardous waste, in any form, with refuse and/or sludge. This is not a unique
technology; any existing incineration process can be used for this special case
of mixing waste streams to obtain better destruction of a particularly intract-
able waste material.
Status - Hazardous waste Coincineration has been performed in a rotary kiln
pyrolyzer and a multiple hearth incinerator. This technique is used to supply
needed Btu's when the principal waste to be burned possesses insufficient heat
content to be autogenic.
Wastes - Any thermally destructible waste is a potential candidate for coin-
cineration. Currently, incineration of the following wastes has been performed:
Wastes previously incinerated Incinerator
Kepone Rotary kiln pyrloyzer
DDT Multiple hearth
2,4,5-T Multiple hearth
PCB Multiple hearth
Advantages -
(1) Will potentially incinerate any thermally destructible hazardous waste.
(2) Incorporates the advantages of the type of incinerator used.
(3) Provides for the incineration of two different wastes simultaneously in
the same facility, thus increasing return on investment.
(4) Provides potential for hazardous waste incineration in existing incinera-
tion facilities.
Disadvantages -
(1) Incorporates the disadvantages of the type of incineration used.
References - 18
2.2.5.2 Detailed Description—
Two types of incinerators have been tested for Coincineration of hazardous
wastes- a rotary kiln pyrolyzer and a multiple hearth incinerator. The rotary
kiln pyrolyzer test unit used for Kepone incineration contained the following
components [19]:
• Waste feed system • Afterburner
• Rotary kiln pyrolyzer • Air pollution control device system
Kepone-contaminated sludge was simulated by the mechanical mixing of appropriate
amounts of Kepone solution in acetic acid into sludge in the feed tank. The
latter was a cylindrical vessel, 33 in. (86 cm) in diameter and 24 in. (60 cm)
2-18
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high fitted with a pneumatic stirrer. The 3!9-in. (10 cm) outlet port in the
conical bottom of the feed tank was fitted with a screen and connected to a
two-stige variable speed pump. The discharge line ™™™^\?»™
relief valve and with provisions to inject sludge from the feed tank or water
from the mains. The feed line, which entered the kiln within the kiln dis-
charge line, was water jacketed to prevent caking within the feed line. At
the end of a run. the feed line was flushed with water [18].
The rotary kiln pyrolyzer was 5 ft (1.52 m) in diameter and 10 ft (30 m) in
length fitted with rotary seal charge and discharge connections so as to mini-
mizf the leakage of gases into or out of the kiln. It was heated directly by
tie hot gases from a 0.923-J/s burner to maintain a nominal temperature of
900°F (500'C). Normally this kiln was batch fed through cover doors on the
side but for the purposes of the coincineration experiments the sludge feed
was Accomplished through a water-cooled feed line which entered the kiln
through the discharge pipe. The maximum feed rate was a nomimal 100 Ib/hr
(45 kg/hr). Cake buildup within the kiln was prevented by 10 rows of link
chain within the kiln [18].
The afterburner, with a residence chamber volume of 8.4 x 10' ft3 (2.4 m3).
was fired by two 0.147-J/s throat mix burners and an auxiliary gas supply.
The incinerator was equipped with a temperature controller and a high limit
safeJy shutoff instruSen?. In this configuration, the maximum temperature
that could be sustained was 2.300°F (1.260'C) with residence tunes in the
order of several seconds [18].
The multiple hearth test unit used for pesticide and PCB incineration contained
the following components [13]:
• Waste feed system • Air pollution control device system
• Multiple hearth incinerator
The PCB's were fed in the form of a solution in kerosene from a burette into
the sludge cake feed screw at a rate of 0.05 Ib/hr (22.5 g/hr) The test PCB
was a preparation Aroclor 1254 which is a combination of some 14 to 16
PCBs [13].
The DDT feed was accomplished by a hopper arrangement placed over the screw-
feed mechanism used toPconduct the dewatered sludge from the centrifuge to the
top hearth of the furnace. The mechanical properties of the powdered DDT
preparation used were such that the simple gravity feed device was not partic-
ularly satisfactory; one might elect to go to a more elaborate vibratory feed
system in practice The feed device used did not effect a constant feed rate,
which was less serious than might be supposed [13].
The furnace was equipped with a scum line feeding into the third hearth The
in ection of 2%. ^'solution was accomplished by gravity feed ng thj.me ered
solution into the scum flow. Incinerating temperature was 1,175'F (635 C) and
afterburner temperature was 1,200°F (650°C) [13].
2-19
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2.3 EMERGING HAZARDOUS WASTE INCINERATION TECHNOLOGY
This section deals with a technology that is in a research and development
stage and is not necessarily recommended for application. A fact sheet for
this emerging technology is presented, each followed by a more detailed
description of the technology's operating parameters. The technology dis-
cussed is starved air combustion/pyrolysis.
2.3.1 Starved Air Combustion/Pyrolysis
2.3.1.1 Fact Sheet—
S, Slg
Description - Starved air combustion utilizes equipment and process flows
similar to those for normal incineration, but in this process less than the
theoretical amount of air for complete combustion is supplied. When the pro-
cess is neither purely pyrolytic nor purely oxidative, it is called starved
air combustion or thermal gasification. Pyrolysis is the thermal decomposition
of solids or sludges in the absence of oxygen.
Flow Diagram -
APCD OR
RECOVERY UNIT
FEED-
PYROLYTIC REACTOR
-SUPPlfMENTALFUEL
•COMBUSTION AIR
•ASH
Status - Minimal use in hazardous waste incineration.
to wastes with purely organic (C,H,0) content.
Potentially applicable
Wastes -
Wastes previously incinerated
API separator bottoms
Tars from the production of styrene
Rubber manufacturing waste sludge
Tars from production of phthalic anhydride
Spent filter aids
Potential candidates
C-, H-, and 0-containing compounds
2-20
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Unlikely candidates
Organics containing either nitrogen, sulfur, sodium, silicon, phosphorus,
fluorine, bromine, chlorine, or iodine
Materials with a high inorganic content (see Section 2.2.1 for a more
detailed list)
Inorganic salts
Heavy metals
Inert material
Materials with a high moisture content
Advantages -
(1) Potential for byproduct recovery.
(2) Reduction of sludge volume without large amounts of supplementary fuel.
(3) Thermal efficiency is higher than for normal incineration due to the lower
quantity of air required for this process.
(4) Reduced air emissions are sometimes possible.
(5) Converts carbonaceous solids into a gas which is more easily combustible.
(6) Allows for the suppression of particulate emissions.
(7) Allows for some treatment of the hot fuel gas stream prior to combustion
to suppress the formation of acid gases.
Disadvantages -
(1) Potential source of carcinogenic decomposition product formation.
(2) Not capable of functioning very well on sludgey or caking material alone
unless cake-breaking capabilities are included in the design.
References - 3, 6. 8, 19, 10, 25
2.3.1.2 Detailed Description—
The terms "starved air combustion" and "pyrolysis," while often used inter-
changeably, are not one and the same. Starved air combustion uses less than
the stoichiometric amount of oxygen required for complete combustion.
Pyrolysis is defined as the thermal decomposition of a compound in the absence
of oxygen.
Pyrolytic conversion processes are generally custom engineered according to
input volumes and types of waste being treated [1]. With respect to waste
carbonaceous material, pyrolysis represents a means of converting the unwanted
waste into a usable commodity with economic value. Modifications to the
pyrolysis process involve treatment of converter effluents. The pyrolysis oils
may be sent through a hydrotreating unit and converted to industrial fuel oil.
The pyrolysis effluent gas may be cooled and the resultant condensate separated
into its components (namely, acetic acid, methanol, furfural, acetone, butyric
acid, propionic acid, methyl ethyl ketone, light fuel oil, and other water
soluble volatile organics) through the use of conventional separation tech-
niques. The cooled wet gas may be dried and utilized as fuel gas. The char-
like pyrolysis residue can be further treated and converted into activated
carbon [1].
2-21
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Other variations include the pyrolyzer itself, which may be incorporated into
a specific incinerator unit (i.e., rotary kiln, molten salt, etc.). A typical
rotary kiln pyrolyzer, for instance, is a sealed, airtight retort cylinder with
an insulated shell. The retort is mounted on a slight incline and rotates.
Kiln dimensions are covered in Section 2.2.1. Without oxygen, the wastes in
the retort chamber cannot burn; they are broken down (pyrolyzed) into steam,
carbon oxides, volatile vapors, and charcoal. Gases formed during pyrolysis
are combusted in an afterburner.
Operational temperatures will vary with waste type, incinerator type, and
desired products. Operating temperatures are usually in the 1,200°F ± 300°F
(650°C ± 150°C) range, with the lower operating temperature generally result-
ing in greater residue (coke), tar, and light oil yields, and lower gas yields.
Residence times will range from a fraction of a second (for flash pyrolysis)
to hours (for solids) [1].
2-22
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2.4 AIR POLLUTION CONTROL DEVICES (APCD)
Air pollutants from the incineration of hazardous wastes may arise both as a
result of incomplete combustion and from the products of combustion of constit-
uents present in the wastes and combustion air. The products of incomplete
combustion include carbon monoxide, carbon, hydrocarbons, aldehydes, amines,
organic acids, polycyclic organic matter (POM), and any other waste constitu-
ents or their partially degraded products that escape thermal destruction in
the incinerator. In well designed and operated incinerators, these incomplete
combustion products are emitted in insignificant amounts. The primary overall
end products of combustion are in most cases carbon dioxide (C02) and water
vapor (H20), but there are also a multitude of other products formed, depend-
ing on the composition of the waste material incinerated and combustion condi-
tions. Hydrogen chloride (HC1) and small amounts of chlorine (C12), for
example, are formed from the incineration of chlorinated hydrocarbons. Hydro-
gen fluoride (HF) is formed from the incineration of organic fluorides, and
both hydrogen bromide (HBr) and bromine (Br2) are formed from the incineration
of organic bromides. Sulfur oxides, mostly as sulfur dioxide (S02), but also
including 1% to 5% sulfur trioxide (S03), are formed from the sulfur present
in the waste material and auxiliary fuel. Phosphorus pentoxide (Pz05) is
formed from the incineration of organophosphorus compounds. In addition,
nitric oxide (NO) is formed by thermal fixation of nitrogen from the combus-
tion air and from nitrogen compounds present in the waste material. Particu-
late emissions include particles of mineral oxides and salts from the mineral
constituents in the waste material, as well as fragments of incompletely
burned combustible matter.
Organic pollutants emitted as a result of incomplete combustion of waste
material are often present in effluents from the primary combustion chamber at
low concentration levels well under the lower flammability limit. The control
of the emission of these organic pollutants can be handled by continued
combustion at high temperatures using afterburners (also termed secondary
combustion chambers).
Scrubbers are also used to control pollutant emissions. They operate by
removing pollutants from the gas stream, instead of changing the pollutants,
as afterburners do. Afterburners and four types of scrubbers are covered in
this section, as are electrostatic precipitators (ESP) and wet electrostatic
precipitators (WEP). The fact sheets presented for each control device addres-
ses operating principles, status with hazardous waste incinerators, suitable
waste streams, advantages, and disadvantages. Following each fact sheet a
more detailed description of the control device is presented.
2-23
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2.4.1 Afterburners
2.4.1.1 Fact Sheet-
Description - Afterburners are simple combustors employed to destroy (by
oxidation) gaseous hydrocarbons not destroyed in the incinerator. Three types
of afterburners are described here: direct flame, thermal, and catalytic.
Direct flame and thermal afterburners are similar, but they destroy organic
vapors by different methods. A high percentage of the vapors pass directly
through the flame in a direct flame unit. In a thermal unit the vapors remain
in a high temperature oxidizing atmosphere long enough for oxidation reactions
to take place. Catalytic devices incorporate a catalytic surface to
accelerate the oxidation reactions.
I NCI NERATOR ^ AFTERBURNER ^ EFFLUENT TO STACK
EFFLUENT CHAMBER OR APCD
AUXILIARY
BURNER AND FUEL
Status - Thermal afterburners are usually an integral part of rotary kilns
used in hazardous waste incineration. Thermal afterburners are also used
with: liquid injection incinerators in a few instances,- pyrolysis units when
chemicals are not being recycled; and conincineration units where the inciner-
ator used normally requires an afterburner. Catalytic afterburners are a
proven technology for nonhazardous gaseous material.
Applicable Waste Streams - Thermal afterburners are suitable for any gaseous
material that is also suitable for incineration or which has been produced by
auxiliary equipment; i.e., a rotary kiln. Catalytic afterburners are appli-
cable to the destruction of combustible materials in low concentrations (they
are not applicable to chlorinated hydrocarbons due to the HCl formation).
Advantages -
Thermal or Direct Flame
(1) Destroys those pollutants that were not destroyed in the primary
incineration.
(2) Allows more flexibility in incinerator operation.
2-24
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Catalytic
(1) Carries out combustion at relatively low temperatures (more economical
to operate than other afterburners).
(2) Clean heated gas produced is veil suited for waste heat recovery units.
Disadvantages -
Thermal or Direct Flame
(1) Auxiliary fuel requirements.
(2) Afterburner costs.
Catalytic
(1) Burnout of the catalyst occurs at temperatures exceeding 1,500°F.
(2) Catalyst systems are susceptible to poisoning agents, activity
suppressants, and fouling agents.
(3) Occasional cleaning and eventual replacement of catalyst is required.
(4) Maintenance costs are high.
2.4.1.2 Detailed Description—Thermal afterburners, used commonly with rotary
kilns, provide exposure of the organic vapors to a high temperature oxidizing
atmosphere to ensure vapor destruction. Temperatures ranging from 1,200°F to
2,400°F (650°C to 1,300°C) are generally required for successful operation of
these devices. Hydrocarbon levels can usually be satisfactorily reduced at
temperatures below about 1,400°F (760°C), but higher temperatures may be
required to simultaneously oxidize the CO [5]. The following temperatures are
often used as guidelines [5]-.
To oxidize hydrocarbons: 900-1,200°F
To oxidize carbon monoxide: 1,200 - 1,450°F
Depending on the type of pollutant in the gas stream, residence times ranging
from 0.2 s to 6.0 s are required for complete combustion. The residence time
in most practical afterburner systems is dictated primarily by chemical kinet-
ic considerations. To ensure good mixing, afterburners are operated at high
velocity gas flows. Gas velocities in afterburners range from 25 to 50 ft/s.
A typical afterburner will be 32 ft (10 m) long, 13 ft (4 m) high, and 13 ft
(4 m) wide [5].
From a chemical viewpoint, two main types of reactions occur in afterburner
systems: oxidation and pyrolysis reactions. In general, the detailed mecha-
nisms for the oxidation and pyrolysis of even the simplest organic compounds
are not completely understood, but it is well established that the reactions
occur in many complicated sequential and concurrent steps involving a
multitude of chemical intermediates [5].
An auxiliary fuel is fired to supply the heat to warm the gases in a temper-
ature that will promote oxidation of the organic vapors. Usually a portion of
the gas stream supplied the oxygen necessary for organic vapor oxidation.
2-25
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Both gaseous and liquid fuels are used to fire afterburners. Gaseous fuels
have the advantage of permitting firing in multiple jet (or distributed)
burners. Oil firing has the disadvantage of producing sulfur oxides (from
sulfur in the oil) and normally produces higher nitrogen oxides emissions [5].
Catalytic afterburners are applied to gaseous wastes containing low concentra-
tions of combustible materials and air. Usually noble metals such as platinum
and palladium are the catalytic agents. A catalyst is defined as a material
which promotes a chemical reaction without taking a part in it. The catalyst
does not change nor is it used up. However, it may become contaminated and
lose its effectiveness [1].
The catalyst must be supported in the hot waste gas stream in a manner that
will expose the greatest surface area to the waste gas so that the combustion
reaction can occur on the surface, producing nontoxic effluent gases of carbon
dioxide, nitrogen, and water vapor. Most of the combustion occurs during flow
through the catalyst bed which operates at maximum temperatures of 810°C to
870°C (1,500°F to 1,600°F). The ability to carry out combustion at relatively
low temperatures while achieving high destruction efficiencies is a major
advantage of the catalytic incinerator for gaseous wastes [1].
Residence time for catalytic oxidation is about 1 second [1].
Due to the form of the waste material to be treated (dilute and in the gaseous
state), the catalytic afterburner is best suited for use at the processing
site where the waste material is generated [1].
Generally, catalytic afterburners are considered for operation with waste con-
taining hydrocarbon levels that are less than 25% of the lower explosice
limit. When the waste gas contains sufficient heating value to cause concern
about catalyst burnout, the gas may be diluted by atmospheric air to ensure
operating temperatures within the operating limits of the catalyst. Burned
gases are discharged through a stack to the atmosphere if they are not sent to
a waste heat recovery unit [6].
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2.4.2 Gas-Atomized Spray Scrubber (Venturi)
2.4.2.1 Fact Sheet-
Description - Gas atomized spray scrubbers utilize the kinetic energy of a
moving gas stream to atomize the scrubbing liquid into droplets. Typical of
these devices are the venturi scrubbers and orifice scrubbers. In the venturi
scrubber, liquid is injected into the high velocity gas stream either at the
inlet to the converging section or at.the venturi throat. In the process, the
liquid is atomized by the formation and subsequent shattering of attenuated,
twisted filaments and thin, cup like films. These initial filaments and films
have extremely large surface areas available for mass transfer.
Orifice scrubbers are similar to venturi scrubbers, however, the orifice in
this type creates more turbulence than is provided by the venturi type.
Diagram -
4AS
LIQUID
Status - Venturi scrubbers are a major air pollution control device for hazard-
ous waste incineration. They are commonly used with rotary kilns and liquid
injection incinerators. The venturi scrubber has also been used with
fluidized bed incinerators.
Applicable Waste Streams - Suitable for particles, and fairly effective in
removing noxious gases that are highly soluble (HCL, HF.) or reactive with the
scrubber solution (S02/ NO , HCN).
A
2-27
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Advantages -
(1) Simultaneous gas absorption and dust removal.
(2) Suitable for high temperature, high moisture.
(3) Particulate removal efficiency is high.
(4) Scaling not usually a problem.
Disadvantages -
(1) Corrosion and erosion problems.
(2) Dust is collected wet and the wastewater will have to be treated.
(3) Moderate to high pressure drop; large amount of energy needed.
(4) Requires downstream mist eliminator.
References - 24
2.4.2.2 Detailed Description—
One of the most predominant air pollution control devices for hazardous waste
incinerators is a venturi scrubber. A typical venturi scrubber is a duct with
a constricted area (throat). Generally, liquid is introduced into the venturi
at the throat. Incinerator exhaust gas enters the venturi at a velocity of
approximately 100 to 400 ft/s (30 to 120 m/s). The moving gas atomizes the
liquid into fine filaments and droplets which allow a large surface area for
mass transfer. It is the gas/liquid contact that permits removal of gaseous
contaminants.
Prior to passage of the incinerator exhaust gas into the venturi, the gas is
quenched to reduce the temperature. While it is recognized that the quench
systems when utilized will effect some degree of particle removal, the primary
function of these units is to reduce flue gas volume and downstream materials
and operating problems through gas cooling. As a result of quenching, inlet
temperatures for venturi scrubbers range from 1108F to 300°F (60°C to 150°C).
Some hazardous waste incineration facilities employ sequential venturi and
plate type or packed bed scrubbers. For these systems, a gas quench is op-
tional since the venturi may be utilized to effect gas cooling by the mecha-
nism of adiabatic expansion of the gases. Such systems are capable of han-
dling a variety of incineration gas compositions and dust loadings. Plate
towers or packed beds, when used in conjunction with gas-atomized spray scrub-
bers, serve the dual function of eliminating the entrainment of liquid drop-
lets from upstream and further reducing the emission levels of gaseous
contaminants.
Incinerating hazardous waste may produce effluent gases with corrosive con-
taminants, such as HC1. It is possible to neutralize the acid with a caustic
solution. The scrubbing solution is determined by the waste burned and its
exhaust gas. In addition to corrosion, erosion is a particular problem in
venturi scrubbers. This is due to the high gas velocities and particulate
loadings encountered during normal duty. Throat and elbow areas are generally
subject to the most wear. Acid-resistant tile liners, polymeric liners, and
Inconel 625 are often used for scrubber construction.
2-28
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venturi scrubbers have been used to control emissions of S02/ HF, and HCl.
Several of Se primary operating parameters that will affect the removal of
these gaseous contaminants are pressure drop, liquid-to-gas ratio, «mt.ct
time and gas flow rate. Pressure drops in venturi scrubbers for controlling
aa^eous emissions from incineration of hazardous wastes are typically in the
1" to sS-in water gage (WG) (7.5 to 12.5-kPa) range [24] "is necessary
to use the correct pressure drop to ensure efficient removal. A higher than
needed Pressure droj will result in wasted energy; a lower than needed pres-
surf drop will result in a lower removal efficiency. As a prune oP«^ing
Jaramete?, the pressure drop should be as low as possible yet yield the needed
removal efficiency.
The liquid-to-gas ratio is a design and operating parameter of prime impor-
tance It is needed in the determination of the scrubber diameter, and has an
effect on the unit dimensions. Normal liquid-to-gas ratios for venturi
scrubbers are 5 to 20 gal/1,000 acf (0.7 to 2.7 L/m3) [24].
Higher efficiencies are attained by allowing the gas and liquid phases to be
in contact for a longer period of time. The contact time required for gas
action is a func?ionPof the rate of mass transfer. The mass transfer
rate in general, is dependent upon four separate resistances: gas-phase
resistance, liquid-phase resistance, chemical reaction resistance and a
solids dissolution Resistance for scrubbing liquids containing solid re.et.nt..
For absorption of gaseous contaminants that are highly soluble or chemically
reacSve with the scrubbing liquid, such as the absorption of HCl by caustic
solution the contact time required for 99% removal is extremely short (of the
order o?'o 4 to 0.6 s). The less reactive and less soluble pollutants require
a longer contact time [24] .
The rate at which a flue gas from waste incineration must be processed by a
particle control device depends primarily on the waste composition the quan-
tity of excess combustion air used, the initial gas temperature, and the
method(s) by which the gas has been cooled, if cooling is used. Hence these
parameters, in conjunction with control device size or geometry, will dictate
?he velocity at which the gas will pass the particle collection elements [24] .
It has been shown that the pressure drop across a ven turi is Pr°P°r^°"^ to
the square of gas velocity and directly proportional to the liquid- to-gas
ratio* Therefore, within limits, increasing gas velocity will result in
increasing pressure drop, other parameters being equal [24] . Typical gas
velocities employed commercially are 100 to 390 ft/s (30 to 120 m/s). The low
Ino of this »nge. 100 to 150 ft/s (30 to 45 m/s). is typical of power plant
applications, while the upper end of the range has been applied to lime kilns
and blast furnaces [24].
Particle cut diameter (diameter of particles in which there is a 50% collec-
tion is a frequently used parameter for describing the particle collection
performance of venturi scrubbers. One reason for this is because plots of
collection efficiency versus particle diameter tend to be rather steep in the
region where inertial inaction is the predominant collection ^chanism High
energy venturi scrubbers provide the highest wet scrubber efficiency with cut
diameters in the 1.17 in x 10 * to 1.95 in. x 10 » (0.3 to 0.5 >.) range [24].
2-29
-------
243 Packed Bed Scrubber
interfacial surface area for mass transfer vith the gas phase.
GAS FROM
INCINERATOR
LIQUID IN
PACKING
ELEMENTS
GAS DISTRIBUTOR
AND
PACKING SUPPORT
LI QUID OUT
Packed bed scrubbers are a major air pollution control device for
incorporated upstream as the primary APCD
ApplicableWaste_Streams - Most suitable for the removal of noxious gases in
streams containing low or no particulate loading.
Advantages -
(1) High removal efficiency for gaseous and aerosol pollutants.
\l] iSSLSTSlSST-Sui* tb. performance of pa=k.d bed
are well developed and understood.
(4) Availability of corrosion-resistant packings to withstand corrosive
materials.
2-30
-------
Disadvantages -
(1) Low efficiency for fine particles.
(2) Not suitable for high temperature or high dust loading applications.
(3) Requires downstream mist eliminator.
(4) Potential scaling and fouling problems.
(5) Possible damage to the scrubber if scrubber solution pumps fail.
References - 24
2.4.3.2 Detailed Description—
Packed bed scrubbers are used in hazardous waste incineration facilities
because of their high removal efficiency for gaseous emissions. Designed
properly, a packed bed scrubber will remove >99% of the halogens from inciner-
ator exhaust gases. The inherent nature of the design does not. however.
allow for removal of particulates from exhaust gases with high particulate
loadings. Unless prior treatment is used, this type of waste stream will
cause clogging in the packed bed scrubber [24].
The packed bed scrubber is a vessel filled with packing material. The scrub-
bing liquid is fed into the top of the vessel, with gas flowing in either a
cocurrent, countercurrent, or crosscurrent mode. As the liquid flows through
the bed, it wets the packing material and provides interfacial surface area
for mass transfer with the gas phase [24].
Differences between packed bed scrubbers include the flow mode, the packing
material, and the depth of packing. The choice of flow mode is dependent upon
the particular application. Crossflow scrubbing is generally applied to
situations where the bed depth is less than 6 ft, and countercurrent design is
applied at bed depths of 6 ft or more [24].
Packing material varies in shape and type. Shapes used include rings, spiral
rings, and saddles. Packing materials are usually made of ceramic or some
other material that will withstand corrosion from acids [24].
The primary parameters that affect scrubber design and the removal of gaseous
emissions are discussed below. These include pressure drop, liquid-to-gas
ratio, contact tijne, and gas flow rate [24].
Packed beds used for gaseous emission control in hazardous waste incineration
facilities usually have a pressure drop range from 2.0 to 7.2 in. WG (0.5 to
1.8 kPa). The total pressure drop across the packed bed is directly propor-
tional to the depth of packing and affects the gaseous removal efficiency in
the packed bed scrubber. Normal liquid-to-gas ratios in packed beds vary from
6 to 75 gal/1000 acf, (0.8 to 10 L/m3, with most units operating between 22
and 52 gal/1000 acf (3 and 7 L/m3) [24].
In gas absorption devices, higher efficiencies are attained by allowing the
gas and liquid phases to be in contact for a longer period of time. Removal
efficiencies for gaseous contaminants in packed beds are directly related to
the depth of packing, which in turn determines the contact time [24].
2-31
-------
The contact time required for gas absorption is a function of the rate of mass
transfer. The mass transfer rate, in general, is dependent upon four separate
resistances: gas-phase resistance, liquid-phase resistance, chemical reaction
resistance, and a solids dissolution resistance for scrubbing liquids
containing solid reactants [24].
In the design of gas absorption devices, the cross-sectional area for gas-
liquid contact is determined by the superficial gas velocity selected. The
greater the gas velocity selected, the smaller will be the scrubber diameter
but the larger will be the pressure drop [24].
There are two additional factors to be considered in the selection of gas
velocity. First, the gas velocity through the scrubber should allow suffi-
cient residence time for gas-liquid contact. Second, in a countercurrent
packed bed, the gas velocity should not exceed the flooding velocity. At the
flooding point, the pressure-drop-versus-gas-rate curve becomes almost vertical,
and a liquid layer starts to build up on top of the packing. The flooding
poing represents the upper limiting conditions of pressure drop and fluid
rates for practical tower operation (Figure 2-1). A margin of 30% to 40% of
the flooding velocity should be allowed in designing these scrubber types.
The most common gas velocities in packed beds range from 7 to 10 ft/s (2.1 to
3.0 m/s) [24].
-V4-HL IINC!
I '
* 1
^v. 0.8
£ 0.6
nT
o
| 0.4
3
ut
-------
As in the case with other wet scrubbers, mist eliminators are often used down-
stream of the packed bed scrubber for proper pollution control. When a wet
scrubber follows or precedes a packed scrubber, mist eliminators are often not
used. A packed bed scrubber is often sequential to a venturi in a hazardous
waste incineration facility.
Most commonly, packed scrubbers are used with liquid injection incinerators
because of the low particulate loading in the exhaust gas. The particulates
in gas streams tend to clog up the bed and decrease removal efficiency.
2-33
-------
2.4.4 Spray Tower
2.4.4.1 Fact Sheet-
Description - Spray towers remove contaminants by a gas absorption process.
The scrubbing liquid is atomized by high pressure spray nozzles into small
droplets, then directed into a chamber that gases pass through in either
countercurrent, cocurrent, or crossflow direction. In this case, the scrub-
bing liquid is the dispersed phase and gas is the continuous phase.
mas? transfer occurs at the liquid droplet surface, gas absorption is enhanced
by finer droplets; i.e., by the increased droplet surface area.
GAS OUT
SPRAYS
GAS FROM t iV ••*•*.'
INCINERATOR —•-"•••
LIQUID IN
LI QUID OUT
Status - Potential as an APCD for hazardous waste incinerators, although
pTr7Ic"ulate efficiency is lower than that of a high energy ventun and
absorption efficiency is lower than that of a packed bed scrubber.
Applicable Waste Streams - Spray towers are suitable for gas streams with
particles and gaseous pollutants.
Advantages -
(1) Simultaneous gas absorption and dust removal.
(2) Suitable for high temperature, high moisture, and high dust loading
applications.
(3) Simple design.
(4) Rarely have problems with scaling.
Disadvantages -
(1) High efficiency may require high pump discharge pressures.
(2) Dust is collected wet.
(3) Nozzles are susceptible to plugging.
(4) Requires downstream mist eliminator.
2-34
-------
Disadvantages - (continued)
(5) Structure is large and bulky.
(6) Lower particulate collection efficiency than a high pressure venturi.
(7) Lower absorption efficiency than a packed tower.
References - 24
2.4.4.2 Detailed Description—
Preformed spray towers are chambers in which a liquid is atomized by high
pressure spray nozzle. The gas stream usually enters the bottom of the cham-
ber and flows countercurrent to the liquid, although both cocurrent and cross-
current modes have been used. The gas may travel in a single path or may be
directed by a series of baffles. The atomized liquid forms droplets and mass
transfer occurs at the droplet surface. The finer the droplets, the more gas
absorption is enhanced. Impurities which are soluble in the scrubbing liquid
are removed by the gas absorption process.
Several of the primary operating parameters that will affect the removal of
gaseous contaminants in preformed towers are discussed here. These include
the pressure drop, liquid-to-gas ratio, contact time, and gas flow rate. A
normal pressure drop for a preformed spray tower is 0.5 to 4 in. WG (0.125 to
0.996 kPa} [24].
Liquid-to-gas ratios are strongly dependent upon the control device and the
specific application. Under normal operating conditions, preformed spray
towers employ liquid-to-gas ratios in the range of 0.0299 gal/acf (4 to 14
L/m3) [26].
In gas absorption devices, higher efficiencies are attained by allowing the
gas and liquid phases to be in contact for a longer period of time. The
contact time required for gas absorption is a function of the rate of mass
transfer. The mass transfer rate, in general, is dependent upon four separate
resistances: gas-phase resistance, liquid-phase resistance, chemical reaction
resistance, and a solids dissolution resistance for scrubbing liquids contain-
ing solid reactants. For absorption of gaseous contaminants that are highly
soluble or chemically reactive with the scrubbing liquid, such as the absorp-
tion of HC1 by caustic solution, the contact time required for 99% removal is
extremely short (of the order of 0.4 to 0.6 s). The rate at which flue gas
from a waste incinerator must be processed by a particle control device de-
pends primarily on the waste composition, the quantity of excess combustion
air used, the initial gas temperature, and the method(s) by which the gas has
been cooled, if cooling is used. Hence these parameters, in conjunction with
the control device size or geometry, will dictate the velocity at which the
gas will pass the particle collection elements. Because inertial impaction is
the principal particle collection mechanism it is beneficial to operate with a
high relative velocity between the gas and the collection element. Practical
relative velocity limitations occur as a result of the increased operating
costs associated with high pressure drops, flooding, or other considerations.
The most common gas velocities in spray towers range from 7 to 10 ft/s (2.1 to
3.0 m/s) [24].
2-35
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2.4.5 Plate Scrubber
2.4.5.1 Fact Sheet--
Description - A plate scrubber is a type of wet scrubber that relies on a gas
absorption process for the removal of contaminants. The basic design is a
vertical cylindrical column with a number of plates or trays inside. The
scrubbing liquid is introduced at the top plate and flows successively across
each plate as it moves downward to the liquid outlet at the tower bottom. Gas
comes in at the bottom of the tower and passes through openings in each plate
before leaving through the top. Gas absorption is promoted by the breaking up
of the gas phase into little bubbles which pass through the volume of liquid
in each plate.
Diagram -
GAS OUT
LIQUID
DOWNCOMER
LIQUID IN
PUKES' jJXPUTCS
GAS FROM t
INCINERATOR
LIQUID OUT
Status - Not as common as packed bed towers or venturi scrubbers for the
control of air pollution from hazardous waste incineration. Capable of
controlling gaseous emissions from liquid injection incinerators.
Applicable Waste Streams - Most suitable for the removal of noxious gases with
low particulate loadings.
Advantages -
(1) Simultaneous gas absorption and dust removal.
(2) High removal efficiency for gaseous and aerosol pollutants.
(3) Low to moderate pressure drop.
(4) Mass transfer increases with multiple plates.
(5) Handles high liquid rates.
2-36
-------
Disadvantages -
(1) Low efficiency for fine particles.
(2) Not suitable for high temperature or high dust loading applications.
(3) Requires downstream mist eliminator.
(4) Limestone scrubbing solution causes scaling.
(5) Not suitable for foamy scrubbing liquid.
References - 25
2.4.5.2 Detailed Description—
Plate scrubbers, like all wet scrubbers, remove gaseous contaminants in a gas
absorption process that depends on intimate gas/liquid contact. The basic
design of a plate scrubber is a vertical cylindrical column with a number of
plates or trays inside. Each plate has openings which can be in the form of
perforations or slots. The scrubbing liquid is introduced at the top plate
and flows across it, then down to the nest plate. A downcomer, located on
alternate sides of each successive plate, permits the downward movement of the
liquid. The scrubbing liquid, exits along with the pollutants at the liquid
outlet located at the tower bottom.
Incinerator gas enters the bottom of the tower and passes up through the plate
openings before exiting at the top. The gas has enough velocity to prevent
the liquid from flowing through the holes in the plates. Gas absorption is
promoted by the breaking up of the gas phase into little bubbles which pass
through the volume of liquid in each plate.
At hazardous waste incineration facilities, plate towers with two sieve trays
are typically used as an absorber/mist eliminator in conjunction with a high
energy venturi scrubber.
The primary operating parameters that will affect the removal of gaseous con-
taminants such as S02 are discussed here. These include the pressure drop,
liquid-to-gas ratio, contact time, and gas flow rate.
Total pressure drop across the plate towers is similar to that of packed beds,
and in the 2.0 to 7.2 in. WG (0.5 to 1.8 kPa range). In plate towers pressure
drop is not used as an operating parameter to estimate removal efficiency.
Rather, the number of plates is the primary parameter that determines removal
efficiency [24].
The liquid-to-gas ratio is a design and operating parameter of prime impor-
tance It is needed in the determination of the scrubber diameter, and has an
effect on the height of a transfer unit. A high liquid-to-gas ratio will lead
to the requirement of a larger diameter, but at the same time will also reduce
the height of a transfer unit. Normal liquid-to-gas ratios in plate towers
vary from 6 to 75 gal/1000 acf, (0.8 to 10 L/m3) with most units operating at
between 22 and 52 gal/1000 acf (3 and 7 L/m3) [24].
2-37
-------
Higher efficiencies are attained by allowing the gas and liquid phases to be
in contact'for a longer period of time. Greater depths of liquid on the trays
lead to higher tray efficiency through longer contact time. An increase in
the number of plates and the column height also improves removal efficiency.
In the design of gas absorption devices, the cross-sectional area for gas-
liquid contact is determined by the superficial gas velocity selected. The
greater the gas velocity selected, the smaller will be the scrubber diameter
but the larger will be the pressure drop.
There are two additional factors that must be considered in the selection of
gas velocity. First, the gas velocity through the scrubber should allow
sufficient residence time for gas-liquid contact. Second, in countercurrent
plate towers, the^gas velocity should not exceed the flooding velocity (the
upper limiting conditions of pressure drop and fluid rates for practical
operation). A margin of 30% to 40% of the flooding velocity should be allowed
in designing these scrubber types. The most common gas velocities in plate
towers, range from 7 to 10 ft/s (2.1 to 3.0 m/s) [24],
Parameters that affect the particle collection performance of a plate scrubber
include pressure drop, liquid-to-gas ratio, gas velocity, dust loading, and
particle size distribution. High particulate loadings and fine particles are
unfavorable conditions.
Plate towers are appropriate when particle size is not less than 1pm. Unlike
absorption efficiency, particle collection efficiency will not necessarily
improve with an increased number of plates, but decreased perforation diameter
does increase particle collection efficiency. The other parameters have been
discussed previously and will not be addressed [26].
2-38
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2.4.6 Electrostatic Precipitator (ESP)
2.4.6.1 Fact Sheet-- _ . . .
Description - Electrostatic precipitation is a process by which particles sus-
pended in a gas are electrically charged and separated from the gas stream
under the action of an electric field. Particles are collected on plates
where subsequent removal is effected by periodically rapping or rinsing.
Diagram -
CLEAN GAS OUT
NEGATIVE EUCTRODE CONNECTED TO
ELECTRICAL POWER SOURCE
NEGATIVELY CHARGED WIRE
GROUNDED COLLECTING PLATE
WITH POSITIVE CHARGE
DIRTY GAS IN
HOPPER TO
DISCHARGE
Reprinted by permission
Status - Electrostatic precipitators have been widely used in conjunction with
utility boilers and with municipal and industrial incinerators. Dry ESP's are
not capable of removing acid gases and, therefore, facilities burning halogen-
ated wastes must employ wet scrubbing of acid halides if ESP's are used for
particulate emission control.
Applicable Waste Streams - Effective for the collection of fine particles
(less than 3.9 x 10 3 in. [1 uim] in diameter), but unable to capture noxious
gases. Performs poorly on particles with high electrical resistivity.
Advantages -
(1) Dry dust collection.
(2) Low pressure drop and operating cost.
(3) Efficient removal of fine particles.
(4) Collection efficiency can be improved when stream is treated (i.e.
conducting dust treated with S02).
Disadvantages -
(1) Relatively high capital cost.
(2) Sensitive to changes in flow rate.
(3) Particle resistivity affects removal and economics.
highly
2-39
-------
Disadvantages - (continued)
(4) Not capable of removing gaseous pollutants.
(5) Fouling potential with tacky particles.
References - 27
2.4.6.2 Detailed Description— .
Electrostatic precipitation is a process by which particles suspended in a gas
are electrically charged and separated from the gas stream. In this process,
negatively charged gas ions are formed between emitting and collecting elec-
trodes by applying a sufficiently high voltage to the emitting electrodes to
produce a corona discharge. Suspended particulate matter is charged as a
result of bombardment by the gaseous ions and migrates toward the grounded
collecting plates due to electrostatic forces. Particle charge is neutralized
at the collecting electrode where subsequent removal is effected by periodical-
ly rapping or rinsing. A majority of industrial EPS's used today are the
single-stage, wire and plate type; charging and collection take place in the
same section of the ESP. Two-stage ESP;s, often called electrostatic filters,
utilize separate sections for particle charging and collecting, and are not
generally employed for controlling particulate emissions from combustion
sources.
Electrostatic precipitators have been widely used in conjunction with utility
boilers and with municipal and industrial incinerators. ESP's have been
employed by European facilities where hazardous wastes are incinerated, al-
though the wastes generally do not contain highly chlorinated compounds. When
halogenated wastes are incinerated, careful waste blending is employed to
protect ESP's from corrosion, so that HCl concentrations do not exceed 1,000
ppm and usually average 300 ppm [27]. Dry ESP's are not capable of removing
acid gases and, therefore, facilities burning halogenated wastes must employ
two-stage gas cleaning if ESP's are used for particulate emission control.
ESP components that are in direct contact with the process gas stream include
the shell, electrodes, high voltage frames, rapper rods and gas distribution
plates On the basis of mild steel construction, such components constitute
approximately 68% of the total precipitator weight and account for 45-s of the
total unit cost [27]. Hence, the applications requiring exposure to corrosive
gas streams have substantial impact on ESP design and ultimate cost. Lead
linings, used in acid mist ESP's, are not generally suitable for use in incin-
erator gas treatment due to poor resistance to attack by gaseous halogens
Fiber glass reinforced plastic (FRP) has been successfully utilized for inlet
and outlet plenums as well as collecting electrodes; however, the latter
application requires provision of adequate conductivity to permit current flow
to ground.
ESP's are carefully designed and constructed for maximum electrical safety,-
however, normal high voltage precautions must be observed. Design features
such as interlocks between access doors and electrical elements should be
employed. Also, access after deenergizing should be delayed to allow for
static charge drainage.
2-40
-------
Compared to those of wet scrubbers, pressure and temperature drops across
ESP's are very small. The pressure drop across an ESP is typically below 1.00
in WG (0 25 kPa) as compared with wet scrubbers which may operate with pres-
sure drops up to 60.2 in. WG (15 kPa). Additionally, ESP's provide, generally
higher removal efficiencies for particles smaller than 3.9 x 10 in. (1 pm) in
diameter than do wet scrubbers. A standard gas temperature range is up to
700°F (370°C) and the voltage normally applied ranges from 30 kV to 75 kV.
2-41
-------
2.4.7 Wet Electrostatic Precipitator (WEP)
2.4.7.1 Fact Sheet-
Description - The wet electrostatic precipitator is a variation of the dry
electrostatic precipitator design. Particle collection is achieved by intro-
duction of evenly distributed liquid droplets to the gas stream through sprays
located above the electrostatic field sections, and migration of the charged
particles and liquid droplets to the collection plates.
GAS FLOW IN
GAS FLOW OUT
HIGH VOLTAGE
LEADS
"^rQ
-WATER PIPES
Status - There are presently no WEP installations at hazardous waste
incineration facilities.
Applicable Waste Stream - Effective in removal of fine particles and of con-
densed organic fumes.
Advantages -
(1) Simultaneous gas absorption and dust removal.
(2) Low energy consumption.
(3) No dust resistivity problems.
(4) Efficient removal of fine particles.
Disadvantages -
(1) Low gas absorption efficiency.
(2) Sensitive to changes in flow rate.
(3) Dust collection is wet.
References - 28, 29
2-42
-------
2 4.7.2 Detailed Description--
The wet electrostatic precipitator is a variation of the dry electrostatic
precipitator design. The two major added features in a WEP system are: (1) a
preconditioning s£p, where inlet sprays in the entry section are provided for
cooling gas absorption, and removal of coarse particles and (2) a wetted
cofleclion surface, where liquid is used to continuously flush away collected
materials. Particle collection is achieved by introduction of evenly dis-
tributed liquid droplets to the gas stream through sprays located above the
electrostatic field sections, and migration of the charged particles and
liquid droplets to the collection plates. The collected liquid droplets from
a continuous downward-flowing film over the collection plates, and keep them
clean by removing the collected particles. To control the carryover of liquid
droplets and mists, the last section of the WEP is often operated without
penetrate and mists can be collected on baffles.
The WEP overcomes some of the limitations of the dry electrostatic precipita-
tor The operation of the WEP is not influenced by the resistivity of the
particles. Further, since the internal components are continuously being
washed with liquid, buildup of tacky particles is controlled and there is some
capacity for removal of gaseous pollutants. In general applications of the
WEP fall into two areas: removal of fine particles, and removal of condensed
organic fumes. Outlet particulate concentrations are typically in the 2 to 24
mg/m3 range.
Data on capability of the WEP to remove acid gases are very limited. WEP's
have been installed to control HF emissions from Soderberg aluminum reduction
cells [27]. With a liquid-to-gas ratio of 5 gal/1000 acf 0 67 L/m") and a
liquid pH between 8 and 9, fluoride removal efficiencies higher than 98% have
been measured. Outlet concentration of HF was found to be less than 1 ppm.
There are no WEP installations at hazardous waste incineration facilities A
potential application is to consider use of the WEP in conjunction with «.low
pressure drop venturi scrubber upstream, where a ma^or portion of the gaseous
contaminantsPand heavy particles will be removed. The WEP will then serve as
a second stage control device for removal of the submicron particles and
remaining gaseous pollutants. Because of its limited application history,
extensive pilot testing prior to design and installation may be necessary.
2-43
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2.5 REFERENCES
1 Ottinger, R.; Blumenthal, J.: Dalporto, D.; Gruber, G.,- Santy, M.; and
Shih C. Recommended methods of reduction, neutralization, recovery, or
disposal of hazardous waste. Volume III. Disposal processes descrip-
tions, ultimate disposal, incineration, and pyrolysis processes.
Cincinnati, OH; U.S. Environmental Protection Agency; 1973 August. 251 p.
PB 224 582.
2 Stevens, J.; Grumpier, S.; and Shih, C. Thermal destruction of chemical
wastes. Presented at the 71st annual meeting of the American Institute
of Chemical Engineers,- 1978 November 16. 45 p.
3. Dawson, R. Hazardous sludge criteria procedures. Sludge Magazine.
2(1):12-21, 1979 January-February.
4. Chementator. Chemical Engineering. 87(5):72, 1980 March 10.
5. Barnes, R. H; Barrett, R. E.; Levy, A.; and Saxton, M. J. Chemical
aspects of afterburner systems. Research Triangle Park, NC; U.S.
Environmental Protection Agency; 1979 April. 117 p. PB 298 465.
6 Hitchcock, D. Solid-waste disposal: incineration. Chemical
Engineering. 86(11)=185-194, 1979 May 21.
7 Ackerman, D.; et al. Destroying chemical waste in commercial-scale
incinerators, facility report No. 6, Rollins Environmental Services
Washington, DC; U.S. Environmental Protection Agency,- 1977 June. 162 p.
PB 270 897.
8 Destructing chemical wastes in commercial-scale incinerators; technical
summary. Volume I (preliminary draft). Washington, DC; U.S. Environ-
mental Protection Agency,- 1975 March. PB 257 709.
9 Farb D; amd Ward, S. Information about hazardous waste management
facilities. Cincinnati, OH; U.S. Environmental Protection Agency; 1975
July. 130 p. EPA-530/SW-145.
10 Genser. J.; Zipperstein, A.,- Klosky, S.; and Farber, P. Alternatives
for hazardous waste management in the organic chemical pesticides, and
explosives industries. Washington, DC,- U.S. Environmental Protection
Agency; 1977 September 2. 286 p. PB 278 059.
11 Technical briefing report: optimizing the energy efficiency of incin-
erators for the disposal of industrial waste (second draft Jrgonne,
IL; Argonne National Laboratory; 1972 June 20. Contract 31-109-38-4223.
12. Scurlock, A.; Lindsey, A.; Fields, T., Jr.; and Huber D. Incineration
in hazardous waste management. Washington, DC,- U.S. Environmental Pro-
tection Agency; 1975. 110 p. PB 261 049.
2-44
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13. Wilkinson, R.; Kelso, G.; and Hopkins, F. State-of-the-art-report:
pesticide disposal research. Cincinnati, OH; U.S. Environmental Protec-
tion Agency; 1978 September. 247 p. PB 284 716.
14. Clausen, J.; Johnson, R.,- and Zee, C. Destroying chemical wastes in
commercial-scale incinerators, facility report No. 1, Marquardt Company.
Washington, DC; U.S. Environmental Protection Agency; 1976 October 116 p.
PB 265 541.
15. Hanson, L.; and Unger, S. Hazardous material incinerator design criteria.
Cincinnati, OH; U.S. Environmental Protection Agency,- 1979 October. 100
p. PB 80-131 964.
16. Ackerman, D.; Clausen, J.; Johnson, R.; and Zee, C. Destroying chemical
wastes in commercial-scale incinerators, facility report No. 3, Systems
Technology Inc. Washington, DC; U.S. Environmental Protection Agency,-
1976 November. PB 265 540
17. Per gust on, T.,- Bergman, F.; et al. Determination of incineration operat-
ing conditions necessary for safe disposal of pesticides. Cincinnati,
OH; U.S. Environmental Protection Agency,- 1975 July. 400 p. PB 251 131.
18. Bell, B. A.,- and Whitmore, F. C. Kepone incineration test program.
Cincinnati, OH; U.S. Environmental Protection Agency,- 1978 May. 148 p.
PB 285 000.
19. Adams, J.; Cunningham, N.,- Harris, J.; et al. Destroying chemical wastes
in commercial-scale incinerators, facility report No. 2, Surface Combus-
tion Midland Ross Corp. Washington, DC; U.S. Environmental Protection
Agency,- 1976 November. 150 p. PB 268 232.
20. Innovative and alternative technology assessment manual (draft report).
Washington, DC; U.S. Environmental Protection Agency,- 1978. EPA-430/ 9-
78009.
21. Destructing chemical wastes in commercial-scale incinerators,- facility
test plans, Volume II. Washington, DC,- U.S. Environmental Protection
Agency,- 1975 July. PB 257 710.
22. Adams, J.; Cunningham, N.; Harris, J.; et al. Destroying chemical wastes
in commercial-scale incinerators; facility report No. 4, Zimpro, Inc.
Washington, DC,- U.S. Environmental Protection Agency; 1976 December. 85
p. Contract 68-01-2966.
23. NHAB ad hoc Committee on Materials for Wet Oxidation Processing Equipment
(Shipboard). Materials for wet oxidation processing equipment
(shipboard). Washington, DC; ODDRE, Department of Defense,- 1973 November.
87 p. AD 771 745 (NMAB-312).
2-45
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CHAPTER 3
WASTE CHARACTERIZATION
-------
CONTENTS
Page
3. WASTE CHARACTERIZATION 3-1
3.1 Introduction 3-1
3.2 Waste Characterization Background Information 3-1
3.2.1 Information Available from Waste Generators 3-1
3.2.2 Information Available from Transporters 3-1
3.2.3 Additional Information Sources 3-2
3.3 Waste Sampling 3-22
3.4 Basic Analysis of Waste 3-24
3.5 Supplemental Analysis of Waste 3-28
3.6 Analysis Test Methods 3-29
3.7 Thermal Decomposition Unit Analysis 3-30
3.8 Work Sheet 3-33
3.9 References 3-36
-------
CHAPTER 3
HASTE CHARACTERIZATION
3.1 INTRODUCTION
Waste characterization is a major factor in assessing the feasibility of
destroying a hazardous waste material by incineration. It affects the design
of the incinerator and its emissions control system and helps determine the
compatibility of a waste with a proposed or available facility. It also plays
a part in determining incinerator operating conditions for complete destruction
of a specific waste.
This chapter discusses the importance of the physical, chemical, and thermo-
dynamic properties of hazardous wastes in evaluating them for incineration and
in selecting a compatible incineration technology type. It also classifies
RCRA Section 3001 hazardous wastes and other hazardous wastes as good, poten-
tial, or poor candidates for incineration, based on technical considerations,
and identifies compatible incineration technology types for these wastes. In
addition, it presents information on sampling and analysis of hazardous wastes
for characterization, and it provides a work sheet to help in evaluating a
waste for incineration.
3.2 WASTE CHARACTERIZATION BACKGROUND INFORMATION
Background information about the hazardous waste(s) is generally available.
Such information may have been generated under Section 3001 (Identification
and Listing of Hazardous Waste), Section 3002 (Standards Applicable to Gener-
ators of Hazardous Waste), or Section 3003 (Standards Applicable to Transporters
of Hazardous Waste) of the RCRA regulations. Additional information can usu-
ally be obtained from studies of the process(es) generating the waste(s).
This background information is helpful in evaluating waste for incineration.
3.2.1 Information Available from Waste Generators
A generator of hazardous waste should be able to provide the Standard Industrial
Classification (SIC) code of the industry from which the waste originates, the
EPA hazardous waste number, and a short description of the waste. The generator
may also provide a detailed description of the process that generates the
waste.
3.2.2 Information Available from Transporters
Federal or state regulations regarding transportation of the waste may give
additional waste characterization information. The manifest that accompanied
3-1
-------
a waste shipment will identify the waste hazard class according to DOT regula-
tions. Also, waste data sheets (forms) that are used prior to discharge of any
waste at a disposal operation may be available. These types of information
are helpful in evaluating a waste or planning provisions for personnel and
environmental safety during storage and handling of the waste at the facility.
3.2.3 Additional Information Sources
Additional information relevant to hazardous waste incineration can be obtained
by contacting the following sources:
A. EPA regional offices:
Region I
John F. Kennedy Federal Building
Room 2203
Boston, HA 02203
Telephone: (617) 223-7210
Region II
26 Federal Plaza, Room 1009
New York, NY 10007
Telephone: (212) 264-2525
Region III
Curtis Building
6th & Walnut Streets
Philadelphia, PA 19106
Telephone: (215) 597-9814
Region IV
345 Courtland Street, NE
Atlanta, GA 30308
Telephone: (404) 881-4727
Region V
230 S. Dearborn Street
Chicago, IL 60604
Telephone: (312) 353-2000
Region VI
First International Building
1201 Elm Street
Dallas. TX 75270
Telephone: (214) 767-2600
Region VII
1735 Baltimore Street
Kansas City, MO 64108
Telephone: (816) 374-5493
3-2
-------
Region VIII
1860 Lincoln Street
Denver, CO 80203
Telephone: (303) 837-3895
Region IX
215 Fremont Street
San Francisco, CA 94105
Telephone: (415) 556-2320
Region X
1200 6th Avenue
Seattle, WA 98101
Telephone: (206) 442-1220
B. Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
5555 Ridge Avenue
Cincinnati, OH 45268
Telephone: (513) 684-4303
C. Office of Solid Waste
U.S. Environmental Protection Agency
401 M Street, SW
Washington, DC 20460
Telephone: (202) 755-9206
D. State Environmental Protection Departments
Table 3-1 can also be consulted relative to RCRA Section 3001 hazardous wastes
and other hazardous wastes which are good, potential, or poor candidates for
incineration with appropriate incineration technologies, based on technical
considerations. This table was prepared using available background documents
for some of the listed waste, trial burn data, and engineering judgment based
on chemical formula(s) of compound(s) present in the waste. The following
criteria were used to structure engineering judgment:
Waste containing Incineration category
• Carbon, hydrogen, and/or oxygen Good
• Carbon, hydrogen, <30% by weight chlorine and/or
oxygen " Good
• Carbon, hydrogen, and/or oxygen, >30% by weight
chlorine, phosphorus, sulfur, bromine, iodine,
or nitrogen Potential
• Unknown percent of chlorine Potential
• Inorganic compounds Poor
• Compounds containing metals Poor
Other factors to be considered in evaluating waste for incineration are:
3-3
-------
TABLE 3-1. HAZARDOUS WASTES RATED AS GOOD. POTENTIAL, OR POOR CANDIDATES
FOR INCINERATION BY APPROPRIATE TECHNOLOGIES [1-8]
EP. hazardo,
Generic
pool
is
r Hazardous waste
The spent halogenated solvents used in degreaslng. tetrachloroethylene.
for incineration
Good Potential Poor
Liquid
injection
Rotary
kiln
Fluidized
bed
trlchloroethylene. nethylene chloride. 1.1.1-trichloroethane, carbon
tetrachloride. and the chlorinated fluorocarbons; and sludges from the
plvents in deqreasina operations.
The spent halogenated solvents, tetrachloroethylene. nethylene chloride.
trichloroethylene. 1.1.1-trichloroethane. chlorobentene. 1.1,2-tn-
chloro-1,2.2-trifluoroethane. o-dichlorobenzene. trichlorofluoromethane
bottoms from the~recovery of these solvents.
ana tne Still cottons tron tne rccnvciy m IIICPP oM*y^«fcg.
-p003 The spent nonhalogemted solvents. Bylene. acetone, ethyl acetate, ethyl
benzene, ethyl ether, n-butyl alcohol, cycloheaanone. and the still
bottoms from the recovery of these solvents.
F004
potions iron me recovery u* nicac aw*yg»iv». ^_—_ .
The spent nonhalogenated solvents. cresols and cresylie acid, nitrobenzene.
and the still bottoms from the recovery of these solvents.
The spent nonhalogenated solvents, nethanol. toluene, methyl ethyl ketone.
-poor
Ui
carbon disulfide. isobutanol. pyridine and the still bottoms fron the
F006
F007
FOOB
F009
F010
P011
F012
F013
POM
F01S
F016
Nastevater treatment sludges from electroplating operations
Spent plating bath solutions from electroplating operations
Plating bath sludges from the bottom of plating baths from electroplating
operations.
Spent stripping and cleaning bath solutions from electroplating operations.
Quenching bath sludge from oil baths from metal heat treating operations.
Spent solutions from salt bath pot cleaning fron metal heat treating
operations.
Quenching vastewater treatment sludges from metal heat treating operations.
Flotation tailings from selective flotation from mineral metals recovery
operations .
Cyanidation wastewater treatment tailing pond sediment from mineral metals
Spent cyanide bath solutions from mineral metals recovery operations
Dewatered air pollution control scrubber sludges from coke ovens and
J
J
J
^
7
V
J
V
J
tool Bottom sediment sludge from the treatment of wastewaters fron wood preserv-
inq processes that use creosote and/or pentachlorophenol
Inorganic piaments
K002 Hastewater treatment sludge from the production of chrome yellow and orange
pignents
K003 Hastewater treatment sludge from the production of molybdate orange
pigments
K004 Wastewater treatment sludge from the production of zinc yellow pigments
(continued)
-------
TABLE 3-1 (continued)
EPA hazardous
waste number
.norganic
K006
Hastevater treatment sludge from the production of chrome green !>£«*»
Wastewater treatment sludge from the production of chrome onide green
pionents (anhydrous and hydrated)
Wastewater treatment sludge from the production of iron blue
KUUO Oven residue from the production of chrome onide green pigments
Organic chemicals production of acet.ldehyde from ethylene
KO?O Ss illation side cuts from the production of "cetaldehyde from ethyl.n,
KOll Bottom stream from the wastewater stripper in the production of
acrylonitrile . —-—n—j—
Still bottoms from the final purification of acrylonitrile in
_. _ «___j»._im_
K012
K013
K014
U*
Ui
K015
K016
K01B
K019
K020
K021
K022
K023
K024
K02S
K026
K027
R028
K029
duction of acrylonitrile
Bottom stream from the acetonitrile column in the production or
acrvlonitrile
acryAuiiiii **» —. . - j ..———
Bottoms from the acetronitrile purification column in tne pr
acrylonitrile
Still bottoms from the distillation of benzyl <="<"•"«
Heavy ends or distillation residues from the production of carbon
tetrachloride
in the
Heavy ends (still bottoms) from the purification co
production of epichlorohydrin
Heavy ends from fractionation of ethyl chloride production
Heav? ends from the distillation of ethylene dichloride in ethylene
dichloride production . , fM.r^
'Heavy ends from the distillation of vinyl chloride in vinyl chloride
from the production of phth.lic anhydride from
Aqueous spent antimony catalyst waste from fluoromethane. production
Distillation bottom tars from the production of phenol/acetone from
cumene .
Tghtei
Distillation
Distiimion'bottoms from the production of phthalic anhydride from
Distillation'bottoms from the production of nilrobentene by the
Stripping0stillbtail"efrom the production of methyl ethyl pyriaine.
Centrifuge residue from toluene diisocyanate production
Spent catalyst from the hydrochlorinator reactor in the production of
1.1,1-trichloroethane
Waste from the product stream stripper in the production of
1.1.1-trichloroethane
(continued)
-------
TABLE 3-1 (continued)
Organic
K034
K03S
K036
K037
K03B
K039
U»
I
K040
K041
K042
K043
Explosives
K044
K04S
K046
K047
Petroleum refi
K04B
K049
KOSO
KOS1
K052
Leather tanning
KOS3
ethvlene and perchloroethvlene
By-products salts generated in the production of KSMA andcacodylic acid
wlatewater treatment sludge from the production of chlordane
u"!ewater Snd sTrub w.te? from the chlorination of cyclopentadiene in
the production of chlordane
exachlorocyclopent
v»tewater treataent siuoges generated in the production of creosote
«U1 Dottoms fro. toluenl reclamation distillation in the production
of disulfoton —- —-JT
1 Wastewater treataent sludges from the production of ol
Wastewater from the washing and stripping of phor.te production
Filter cake from the filtration of diethylphosphorodithoric acid in the
production of phorate .—.—_—
Wastewater treatment sludge from the production of phorate
Hastewater treataent sludge from the production of tonaphene
Heavyen* or dmill.tioTresidues fro. the distillation of tetr.chloro-
benzene in the production of 2.4.5-T , , , .
2.6-Dichloroohenol waste from the production of 2.4-D
Uastewater treataent sludges from the manufacturing and processing of
Spen^carbon from the treataent of wastewater containing explosives
Hastewater treataent sludges from the manufacturing, formulation .nd
loading of lead-based initiating compounds
Pink/red water from TOT operations
^Dissolved air flotation (OAF) float from the petroleum refining industry
Slop oil emulsion solids from the petroleum refining industry
Heat exchanger bundle cleaning sludge from the petroleum rerining
industry
API separator sludge from the petroleum refining industry
Tank bottoms (leaded) from the petroleum refining industry
Srome^blue) trimmings generated by the following subcategories of the
leather t.nmng and finishing industry, hair ~.in/rhr«« t.n/retan/
leater t.mng an , .
wet finish, hair save/chrome tan/retan/wet finish; retan/wet
no beamhouse; through-the-blue, and shearling
(continued)
-------
TABLE 3-1 (continued)
EPA hazardous
waste number
Hazardous waste
Candidate
for incineration Liquid Rotary Fluidized
Good Potential Poor injection kiln bed
Leather tanning finishing (cont'd)
KOS4 Chrome (blue) shavings generated by the following subcategorles of the
leather tanning and finishing industry: hair pulp/chrome tan/retan/
wet finish; hair save/chrome tan/retan/wet finish; retan/wet finish;
no beaahouse; through-the-blue, and shearling
Buffing dust generated by the following subcategorles of the leather
tanning and finishing industry: hair pulp/chrome tan/retan/wet
finish; hair save/chrome tan/retan/wet finish; retan/wet finish; no
-J50S6 Sewer screenings generated by the following subcategories of the leather
tanning and finishing industry, hair pulp/chrome tan/retan/wet finish;
hair save/chrome tan/retan/wet finish; retan/wet finish; no beamhouse;
rlii
15)57 Hastewater treatment sludges generated by the following subcategories of
the leather tanning and finishing industry; hair pulp/chrome tan/retan/
wet finish, hair save/chrome tan/retan/wet finish; retan/wet finish; no
rlii
KOSB
wastewater treatment sludges generated by the following subcategories of
the leather tanning and finishing industry: hair pulp/chrome tan/retan/
wet finish; hair save/chrome tan/retan/wet finish; and through-the-blue
Wastewater treatment sludges generated by the following subcategory of
Ut
-J
K059
the leather tanning and finishing industry:
retan/wet finish
hair save/nonchrome tan/
Iron and steel
K060
K061
Ammonia still line sludge from coking operations
Emission control dust/sludge from the electric furnace production
of steel
K062
K063
Spent pickle liquor fron steel finishing operations
Sludge from lime treatment of spent pickle liquor from steel finishing
operations
Primary copper
R064
Primary lead
K06S
Acid plant blowdown slurry/sludge resulting from the thickening of
blowdovn slurry from primary copper production .—
Surface impoundment solids contained In and dredged from surface im-
poundments at primary lead smelting facilities
Primary zinc
K066
K067
K06B
Sludge from treatment of process wastewater and/or acid plant blowdown
from primary zinc production
Electrolytic anode slimes/sludges from primary zinc production
Cadmium plant leach residue (iron omde) from primary zinc production
V
(continued)
-------
TABLE 3-1 (continued)
EPA hazardous
waste number
Secondary lead
K069
Hazardous waste
Candidate
for incineration
Good Potential Poor
Incinerator type
Liquid
inection
Rotary
kiln
Fluidized
bed
dust/sludge from secondary lead smelting
Discarded coonercial chemical products.
off-specification species, containers.
and spill residues thereof
P001 3-(alpha-Acetonylbenzyl)-4-hydro]iycoumarin and salts
ui
I
OB
P002
DAAl
PUOJ
P004
POOS
PAAA
P007
POOB
P010
P011
PA 12
P013
P014
P01S
P016
P017
PA1A
P019
P020
PA91
P022
P023
PA 3d
P025
P026
P027
P02B
P029
pmo
P031
P032
P033
P034
P03S
P037
P03B
P039
P040
l-Acetyl-2-tniourea , J J J
Aldrin , V j J J
Allyl alcohol v j
5-(Aminooethyl)-3-i80Barolol I j
4-ABinopyridine J ,
Arsenic acid i
Arsenic pentonide j
Barium cyanide J •J V V
Benzene thiol j
Bis(chlorooethyl) ether ] V V
Bromoacetone j * ,
2-Butanone peroxide / j
2-sec-butyl-4.6-dinitrophenol V j
Carbon disulfide ^ • J ,
Chloroacetaldehyde , v ^
l- j
Dieldrin ^ i V
Diethylarsine . / J J
0.0-Diethyl-S-|2-(ethylthio)ethyl| ester of phosphorothioic acid 4 J V V
0.0-Diethyl-0-(2-pyrazinyl) phosphorothioate V »
(continued)
-------
TABLE 3-1 (continued)
Ul
i
vO
BPk hazardous
waste number
Candidate
for incineration Liqu
Hazardous waste Good Potential Poor injec
Discarded comnercial chemical products,
off-specification species, containers,
and spill residues thereof (cont'd)
P041 0,0-Diethyl phosphoric acid, 0-p-nltrophenyl ester V V
P042 3,4-Dihydroxy-alpha-(methylamino)-methyl benzyl alcohol V V
P043 Di-isopropylfluorophosphate V V
P044
P045
P046
P047
P04B
P049
POSO
POS1
POS2
POS3
P054
P055
P056
P057
POS8
POS9
P060
P061
P062
P063
P064
P065
P066
P067
P068
P069
P070
P071
P072
P073
P074
P075
P076
P077
P07B
P079
P080
P081
P082
P063
Dimethoate V
3,3-Dimethyl-l-(methylthio)-2-butanone-0-|(methylamino)carbonyl] oxime V
alpha, alpha-dimethylphenethylamine J «'
4,6-Dinitro-o-cresol and salts i
2,4-Dinitrophenol ,
2,4-Dithiobiuret »'
Endosulfan V
Endrin V V
Ethylcyanide J J
Ethylenediamine V V
Ethyleneimine V V
Ferric cyanide J
Fluorine V
2-Fluoroacetamide V
Fluoroacetic acid, sodium salt J
Heptachlor V
1.2.3.4,10.10-Hexachloro-1.4,4a,5,8.8a-hexahydro-l,4:5.B-endo.
endo-dlaethanonaphthalene V
Hexachloropropene J J
Hexaethyl tetraphosphate V
Hydrocyanic acid V V
Isocyanic acid, methyl ester j J
Hercury fulminate V
Hethomyl V
2-Hethylaziridine J J
Nethyl hydrazine V V
2-Hethyllactonitrlle V V
2-Nethyl-2-(methylthio)propionaldehyde-o-(methylcarbonyl) oxioe <
Hethyl parathion V
l-Naphthyl-2-thiourea V
Nickel carbonyl J
Nickel cyanide V
Nicotine and salts V
Nitric oxide J
p-Nitroaniline V
Nitrogen dioxide V
Nitrogen peroxide V
Nitrogen tetroxide V
Nitroglycerine V V
N-Nitrosodimethylamine V
N-Nitrosodiphenylamine 7
Incinerator type
id Rotary Fluldized
tion kiln bed
i i
3 3
j i
v
V V
V V
V
i
1
i
V
j V
V V
V V
V V
(continued)
-------
TABLE 3-1 (continued)
EPA hazardous
__ — Candidate
for incineration Lii
u,,,,^,. u,.». Good Potential Poor inj
Discarded coomercial chemical products.
off-specification species, containers.
and spill residues thereof (cont'd) /
POM H-Nitrosomethylvinylamine ]
P08S octamethylpyrophosphoramide .
poflft m — i .I..MU.I <-nnide i
Zinc cyanide j
kcetaldehyde ]
Acetone v /
Acetonitrile v
v
V v
V V i
^ '
V v
V V V
1 ] 1
V v V
~~/~ J
} v
3 } i
j i—
j }
j i i
(continued)
-------
TABLE 3-1 (continued)
EPA hazardous
waste number
Discarded commercial chemical products.
off-specification species, containers.
and spill residues thereof (cont'd)
U004 Acetophenone
0005 2-Acetylaminoflourene
U006 Acetyl chloride
U007
UOOB
U009
Ul
I
Acrylamide
Acrylic acid
6-to!no-iria!2.B.Ba.8b-hexahYdro-B-e.BethoKY.5.BethYlc.rD.
nate azirino(2'.3':3.4) pyrrolO(1.2-a)indole-4. 7-dione (ester)
Amitrole
Aniline
Asbestos
Auramine
Azaserine
Benz[c]acridine
Benzal chloride
Benztalanthracene
Chloral
Chloranbucil
Chlordane
Chlorobenzene
Chlorobenzilate
p-Chloro-m-cresol
U040 chlorodibromome thane
U041 l-Chloro-2.3-epoxypropane
U042 Chloroethyl vinyl ether
U043 Chloroethene
U044 chloroform
U04S Chloromethane
Benzene
Benzenesulfonyl chloride
Benzidine
Benzo[a|pyrene
Benzotrichloride
Bi9(2-chloroethoxy)me
Bis(2-chloroethyl) ether
N.N-Bis(2-chloroethyl)-2-naphlhylaniine
Bis(2-chloroisopropvl) ether
Bromone thane
4-BromophenYl phenvl ether
n-Butyl alcohol
Calcium chrornate
Carbonyl fluoride
(continued)
-------
TABLE 3-1 (continued)
Ui
I
EPA hazarc
waste nuat
Discarded
off-speciJ
and spill
0089
0090
0092
0093
0095
0097
U098
0099
U100
0101
0102
0104
0105
0107
oioa
U109
0110
Dili
U112
0113
0114
0115
U116
U117
one
0119
U120
0121
U122
0123
U125
0126
0128
0129
0130
«"« HalardouS -ast, pood Potential Poor inaction Hi.. ••"•_
connercial chenical products.
Fication species, containers.
residues thereof (cont'd) 7 V
Diethylstilbestrol 7 y
Dihydrosaf role j ^ i „
Dimethylamine 7 V
p-Diaethylaninoazobenzene i «
3,31-Diaethylbenzidine j 7 V
alpha-alpha-Diaethylbenzylhydroperoxide * 7 ^
Dinethvlcarbanovl chloride 1i 7 «
1.1-Dinethylhydrazin* 7 7 v
1,2-Diwthylhydrazine J 7 %
2.4-Diaethylphenol 7 V V
Dinethyl phthalate 7 7 >
2.4-Dinltrophenol 7 ^
2.4-Oinitrotoluene j _s
Di-n-octyl phthalate i 7 '
1.4-Dioxane 7 i
Dipropylanlne 7
Di-n-propylnitrosaaine j J
Bthyl acryiate / V
Ethylenebisdithiocarbanate j
Ethylene thiourea / 7
Bthyl ether 7
Bthyl nethanesulfonate /
Fluoranthene 7
Formaldehyde / 7
Formic acid j J
Furfural 7 7
Glvcidvlaldehyde J
Hexachlorobutadiene 7
Hexachlorocyclohexane ^ 7
HeMchlorocyclopentadiene
Jr
^
^
1
4
, s
^
^
1
5
1 •-
j
i
p
^•^^^
™— •— •
h
V
J,
1
V
-------
TABLE 3-1 (continued)
u>
i
U)
EPA hazardous
for incineration liquid Rota
•,„«*„„. «»te e™<> Potential Poor injection kil
ir IWB
ry Fluidized
n bed
Discarded commercial chemical products.
off-specification species, containers.
and spill residues thereof (cont'd) / V V V
U046 Chlorooethyl methyl ether , V «
U047 2-Chloronaphthalene "j J J
U049
U050
U052
U053
DOSS
UOS6
UOS8
UOS9
U061
U062
U064
U065
U067
U06B
U070
U071
U073
U074
U076
U077
U079
uoao
1)082
U083
UOB4
uoas
U086
U087
U088
4-Chloro-o-toluidine hydrochloride . * j
Chrysene j J J
Cresols j V
Crotonildehyde j j
Cumene j V
Cyclohexane j J ,
Cyclophosphamide i ,
Daunooycin j
DDT }
Diallate j v
V
,
Dibenzo[a,i]pyrene v < V V
Dibromochlorome thane J j
1.2-Dlbromoethane ^ ^
Dlbromomethane / J ,
1,2-Dichlorobenzene ^
1,3-Dichlorobenzene j ,
3.3'-Dichlorobenzidine i ^
1.4-Dichloro-2-butene i
1.1-Dichloroe thane ^
1.2-Dfchloroe thane j J ,
1,2-trans-dichloroethylene ^ J
Dichloromethane /
2,6-Dichlorophenol j J
1.2-Dichloropropane I jf
•• ••
/
1— ^
1
1
^
/ J
> • — '
{ i
Diepoxybutane / V *
1.2-Diethylhydrazine i ^ V V
0.0-DiethylS-methyl ester of phosphorodithioic acid » V V »
Die thy 1 phthalate
-------
TABLE 3-1 (continued)
EPA hazardous
waste number
Hazardous waste
for incineration
Good Potential Poor
Incinerator type
Liquid Rotary Fluidized
injection kiln bed
Discarded commercial chemical products,
off-specification species, containers,
and spill residues thereof (cont'd)
U089 Diethylstilbestrol
U090 Dihydrosafrole
iinql » 1l-nim«thnvuh»nTl(iin*
U092
U093
IIAQd
U09S
U096
U09B
U099
lllflA
U101
0102
U104
U10S
U107
uioa
U110
Ulll
1111}
11113
U114
U116
U117
una
U119
U120
' 0122
U123
0125
0126
U128
U129
U130
Diaethylamine
p-Diaethylaminoazobenzene
3.3* -Dimethylbenzidlne
alpha-alpha-Dunethylbenzylhydroperoxide
1 , 1-Diae thylhydrazine
1,2-Dinethylhydrazine
2.4-Dinethylphenol
Dimethyl phthalate
2,4-Dinitrophenol
2 , 4-Dinitrotoluene
oi-n-octyl phthalate
1,4-Dionane
Dipropylamine
Di-n-propylnitrosamine
Ethyl acetate
Ethyl acrylate
Ethylenebisdithiocarbamate
Ethylene thlourea
Ethyl ether
Ethyl nethanesulfonate
Fluoranthene
Formaldehyde
Formic acid
Furfural
Glycidylaldehyde
Hexachlorobutadiene
Hexachlorocyclohexane
Hexachlorocyclopentadiene
i
" V
5 J
1
q
. S
1
J J
, j
: <
i v
V
V
v J,
V
V
\
J J
V
\
V
^
V 1
i \
,
4
9l
1 '
V i
V ^
1
V
V
j
V
,
j
1 V
si,
1
V
^
1
l{ 1
/ li, -
j j j
! i !
V v V
, i i
(continued)
-------
TABLE 3-1 (continued)
to
I
BPn hazardous
for
Good
Discarded commercial chemical products.
off-specification species, containers.
and spill residues thereof (cont'd)
U131 Hexachloroe thane
U132 Hexachlorophene
U133 H»Hr.«»n.
U134
U13S
U136
U137
U138
U140
U141
U143
U144
U146
U147
U149
U1SO
U152
U153
U1SS
U156
U1S8
U1S9
11161
U162
U164
U16S
1 U167
U16B
U170
U171
1)172
U173
Hydrofluoric acid
Hydrogen sulfide
Hydroxydimethyl arsine oxide
Indeno( 1.2. 3-cd)pyrene
lodomethane
Iron Dextran
Isobutyl alcohol
Isosafrole
Lasiocarplne
Lead acetate
Lead phosphate
Lead subacetate
Maleic anhydride
Haleic hvdrazide
Halononitrile
Helphalan
Hethacrylonltrile
Hethanethlol
Hethapyrilene
Hethyl chlorocarbonate
3-Methylcholanthrene
4.4'-Hethylene-bis-(2-chloroaniline) '•
Hethyl ethyl ketone
Methyl ethyl ketone peroxide
Hethyl isobutyl ketone
Hethyl methacrylate
M-Methyl-M'-nitro-H-nitrosoquanidine
Hethylthiouracil
Naphthalene
1-Naphthylanine
2-Naphthylamine
4-Nitrophenol
2-Nitropropane
N-Nitrosodi-n-butylamine
N-Nitrosodiethanolanine
v
V
J
V
J
J
V
J
1
i
Candidate
incineration
Potential Poor
J
V ....
7
* j
.
7
v. v
J
V
J
7
v
V
v
Inc
Liquid
injection
V
1
'
V
V
7
J
J
J
V
inerator
Rotary
kiln
V
J
<
7
7
V
V
V
7
7
1
1
•I
7
— L
V
J
V
7
V
type
Fluidized
bed
V
'
7
V
V
V
7
V
7
— i—
J
— i—
V
V
V
(continued)
-------
TABLE 3-1 (continued)
i
•—
o»
EPA hazart
. •
for incineration Liquid Rotary Fluidized
tous HMardoiis uaate cood Potential Poor H~""" ^" ^—
Discarded comercial chenical products.
off-specification species, containers.
and spill residues thereof (cont'd) ^
U174 N-Nitrosodiethylamine |
U175 N-Nitrosodi-n-propylanine ^
U17J N-Mifroso-n-*
1-4-
i
j
£_ j__
? F
j i
] i
v j 4 4-
V
v y
v v
-------
TABLE 3-1 (continued)
Ul
Hazardous waste Good Potential Poor injectl
Discarded commercial chemical products.
off-specification species, containers,
and spill residues thereof (cont'd) . /
U220 Toluene » /
U221 Toluenediamine \ /
U222 ».T«I..Jrf«n. hurfrorhlnrilh. * «
U223
U224
U225
U226
U227
U229
U230
U232
(1233
U235
U236
U238
Other hazardous
SIC code number
2865
2865
2865
2869
2869
2869
2869
2869
2869
2869
2869
2295
2869
Toluene diisocyanate J v
Toxaphene j /
1,1,1-Trichloroe thane "> ",
1,1,2-Trichloroethane * y/
Trichloroethane ->F j
Trichlorofluoromethane / v
2,4,5-Trichlorophenol '
2.4.6-Trichlorophenol -— J,
2,4,5-Trichlorophenoxyacetic acid V
2,4.5-Trichlorophenoxypropionic acid alpha, alpha, alpha-Trichlorotoluene i
Trinitrobenzene *,
Tris(2,3-dibromopropyl) phosphate \
Trypan blue '
lire thane "*. j
wastes
Vacuum still bottoms from the production of maleic anhydride V
Distillation residues from fractionating tower for recovery of benzene
and chlorobencenes \
Vacuum distillation residues from purification of l-chloro-4-nitrobeniene ._* .
Still bottoms or heavy ends from methanol recovery in methyl methacrylate
production \
Heavy ends and distillation from production of carbaryl V
Residues from the production of henachlorophenol, trichlorophenol and
2 4 5-T «
Heavy ends from distillation of ethylene dichloride in vinyl chloride
production '
Solid waste discharge from ion exchange column in production of
acrylonitrile *
Bottom stream from quench column in acrylonitrile production of
acrylonitrile \ * —
Still bottoms from aniline production V
Tars from manufacture of bicycloheptadiene and cyclopentadiene V
Still hnttnm from production of furfural V
Unrecovered triester from production of disulfoton V
Waste polyvinyl chloride (PVC) from the manufacture of coated fabrics V
Still bottoms from the production of pentachloronitrobenzene V
an kiln bed
S i
^
-------
TABLE 3-1 (continued)
u>
I-1
OB
_^_— «^-^-^— .^^—
EPA hazardous
Other hazardous
SIC code number
2869
2869
2822
2669
2869
2869
2869
2869
3333
3339
3339
3339
3341
. • • Candidate
for incineration
Incinerator type
Liquid Rotary Fluidized
Hazardous waste <*od Potential Poor injection ill.! !«-_
wastes (cont'd)
Process clean out sludges from production of 1.1.1-trichloroethane V
Heavy ends and light ends from the production of methyl acrylate V
Polvvinvl chloride sludge from the manufacture of polwinyl chloride i
Still bottoms from the purification of fluoromethanes in the production
of fluoromethanes /
Heavy ends and light ends from the production of ethyl acrylate V
Heavy ends from the production of glycerine from allyl chloride V
Heavy ends from the distillation of acetic anhydride in the production j
Light ends from the distillation of acetaldehyde in the production at
acetic anhydride *
• Reactor cleanup wastes from the chlorination, dehydrochlorination or
oxychlorination of aliphatic hydrocarbons ,, ,. .1
• Fractionation bottoms from the separation of chlorinated aliphatic ^
• Distillation bottoms from the separation of chlorinated aliphatic
• Reactor'cleanup wastes from the chlorination or onychlorination of
cyclic aliphatic hydrocarbons
• Fractionation bottoms from the separation of chlorinated cyclic
• Distillation bottoms from the separation of chlorinated cyclic
aliphatic hydrocarbons *,
• Batch residues from the batch production of chlorinated polymers V
• Solution residues from the production of chlorinated polymers jt
• Reactor cleanup wastes from the chlorination of aromatic hydrocarbon V
• Fractionation bottoms from the separation of chlorinated aromatic hydro-
c&rbons
• Distillation bottoms from the separation of chlorinated aromatic hydro-
Zinc production: oxide furnace residue and acid plant sludge *
Ferromanganese emissions control, baghouse dusts and scrubwater solids i
i 1
1 J
j j
J V V
V V V
J J J
V V
-------
TABLE 3-1 (continued)
ut
i
.M
VO
EPA hazardous
Other hazardous
SIC code number
3341
3341
3341
3341
3341
3691
3691
3691
3691
3691
3692
2819
2834
2851
2869
2869
3312
3322
3331
3339
3339
1099
1475
2874
2819-2874
2812
2812
r,n,i, H=t. Incinerator type
for incineration Liquid Rotary Fluldlzed
Hazardous waste "ood Potential Poor injection kiln !~a_
Hastes (cont'd)
Secondary lead-white metal production furnace dust \
Secondary copper-pyrometallurgical. blast furnace slag ^ ^ «
"Secondary aluminum dross smelting-high salt slag plant residue »
Zinc-cadmium metal reclamation, cadnium plant residue *
Lead acid storage battery production cleanup wastes from cainone ana anoue ^
paste production I
Nickel cadmium battery production wastewater treatment sludges *
Cadnium silver onide battery production wastewater treatment sludges . — . X
Mercury cadnium battery production wastewater treatment sludges «
Maonesium carbon battery production chromic acid wastewater treatment sludges V
arsenic bearing wastewater treatment sludges from production or Doric acid 1
Arsenic or organo-arsenic containing wastewater treatment sludges from pro-
ductlon of veterinary Pharmaceuticals
Air pollution control sludges from paint production
By-product salts in production of HSHA
Bv-oroduct salts in production of cacodylic acid
Steel Finishing: Alkaline cleaning waste
• Waste pickle liquor
• Cyanide-bearing wastes from electrolytic coating
• Chromate and dichromate wastes from chemical treatment
Lead/phenolic sand-casting waste from malleable iron foundries V
Primary copper smelting and refining electric furnace slag, converter dust.
acid plant sludge, and reverberatory dust (T) j
Primary antimony-electrolytic sludge i
Primary tungsten- digest ion residue ^
~ChTorinator residues and clarifier sludge from zirconium eitractlon '
Overburden and slimes from phosphate surface mining j
Slag and fluid bed prills from elemental phosphorus production »
Sodium calcium sludge from production of chlorine by Down Cell process V
Mercury bearing brine purification muds from mercury cell process in ^
chlorine production
-------
TABLE 3-1 (continued)
Candidate Incinerator type
HPA hazardous for incineration Liquid Rotary Fluidized
waste number Hazardous waste Good Potential Poor injection kiln bed
Other hazardous wastes (cont'd)
SIC code number
2816 Mercury bearing waateuater treatment sludgea from the production of
mercuric sulfide pignent V
2616 Chromium bearing wastewater treatment sludgea from the production
of TiOj pigment by the chloride process V
2816 Arsenic bearing sludges from purification process in the production
of antimony oxide V
2816 antimony bearing wastewater treatment sludge from production of
antimony o»ide V
3312Iron making:Perromaganese blast furnace dust7
• Ferromanganese blast burnace sludge
* Electric furnace dust and sludge
'use this table for indicative guidance only. For decision making, read the material presented in the teat.
10
O
-------
• Moisture content
• Potential pollutants present in incinerator effluents
• Inert content
• Heating value and auxiliary fuel requirements
• Potential health and environmental effects
• Physical form
• Corrosiveness
• Quality
• Known carcinogenic content
• PCB content.
Table 3-1 should be used with caution. The information is indicative rather
than conclusive. Conclusive decisions can be made only after studying the
actual physical, chemical, and thermodynamic characteristics of the material(s)
along with trial burn data (if available), and comparing expected behavior with
the known behavior of a similar material (similar composition or physical,
chemical, and thermodynamic characteristics) undergoing thermal destruction.
The incineration technology ratings in Table 3-1 are influenced by the physi-
cal form of the waste. In general, liquid wastes can be incinerated by a
liquid injection incinerator, rotary kiln, or fluidized bed incinerator.
Waste in gas, liquid, solid, and mixture forms can be incinerated by either
a rotary or fluidized bed incinerator. The kinematic viscosity of the liquid
waste has to be considered in determining its suitability for incineration
by liquid injection incinerators.
Liquid injection, and rotary kiln incinerators are widely used to dispose of
hazardous wastes. There is substantial research going on fluidized bed inciner-
ators and they appear to be promising in disposing of hazardous wastes.
Multiple hearths and multiple chambers incinerators have moderate applicability
for incineration of hazardous wastes. They are widely used for the destruction
of solids (municipal refuse) and sludges (sewage sludges). If the ash resulting
from incineration of a waste is fusible, multiple hearths incinerators are
not well suited for its disposal. Multiple hearth incinerators are not capable
of operating at elevated temperatures - so that if a temperature over 2000°F
is needed for destruction, multiple hearths incinerators are not applicable.
Multiple hearths and multiple chambers incinerators have limited applicability
to hazardous wastes, so they are not included in Table 3-1.
It may be possible to blend different wastes or wastes and fuel oils to change
poor or potential candidates into good candidates for incineration. Such
blending may also change the characteristics of a waste, making it incinerable
in a different incineration type than is identified in Table 3-1. It is also
possible that some wastes identified in Table 3-1 as good or potential candi-
dates may turn out to be poor candidates for incineration if mixed with or
contaminated by poor incineration candidates like metals (arsenic, chromium,
etc.). Therefore, such factors as blending and waste contamination should
be considered on a case-by-case basis in making decisions. As mentioned
earlier, Table 3-1 should be used with caution for indicative guidance rather
than conclusive decisions.
3-21
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3.3 WASTE SAMPLING [9]
It is important that a representative sample of the waste be collected and
properly handled in determining waste characteristics. Sampling situations
vary widely and therefore no universal sampling procedure can be recommended.
However, it is important to incorporate quality assurance procedures as necessary
components in any waste sampling plan.
Sampling procedures require a plan of action to maximize safety of sampling
personnel, minimize sampling time and cost, reduce errors in sampling, and
protect the integrity of the samples after sampling. The following steps are
essential in this plan of action:
1. Prior to collecting a sample, check the manifest to see whether dangerous
emissions can be expected and to make sure that what is sampled resembles
what is described in the manifest.
2. Ask the generator for background information on the waste.
3. Determine what should be sampled (truck, barrel, pond, etc.).
4. Select the proper sampler (Coliwasa, scoop, bucket, etc.).
5. Select the proper sample container and closure (glass, plastic, etc.).
6. Design an adequate sampling plan that includes the following:
(a) Choice of the proper sampling point, (b) Determination of the number
of samples to be taken, (c) Determination of the volumes of samples to be
taken.
7. Observe proper sampling precautions (safety of personnel, protective
gear).
8. Handle samples properly (sample preservation).
9. Identify samples and protect them from tampering.
10. Record all sample information in a field notebook.
11. Fill out chain of custody record.
12. Fill out sample analysis request sheet.
13. Deliver or ship the samples to the laboratory for analysis.
Various samplers and their applicabilities; sample containers and their com-
patibility with wastes; sampling points, number of samples and sample volume
requirements; personnel protective gear and other safety precautions; sample
preservation requirements; sampling procedures for various situations; and
sample handling (labeling, field logging, chain of custody, analysis request
form and sample shipping) are discussed in detail in "Samplers and Sampling
3-22
-------
Procedures for Hazardous Waste Streams" (EPA-600/2-80-018, January 1980).
This source can be consulted prior to sampling.
Chain of custody procedures recommended by EPA's National Field Investigation
Center are described below:
1. The laboratory director designates one full-time employee (usually the
laboratory supervisor) as a sample custodian and one other person as an
alternate. In addition, the laboratory sets aside a "sample storage
security area." This is a clean, dry, isolated room which can be
securely locked.
2. All samples are handled by the minimum number of persons.
3. All incoming samples are received only by the custodian or, in his absence.
the alternate, who indicates receipt by signing the sample transmittal
sheets and, as appropriate, sample tags, accompanying the samples and re-
taining the sheets as permanent records.
4. Immediately upon receipt, the custodian places the sample in the sample
room, which is locked at all times except when the samples are removed or
replaced by the custodian. To the maximum extent possible, only the
custodian is permitted in the sample room.
5. The custodian ensures that heat-sensitive or light-sensitive samples, or
other sample materials having unusual physical characteristics, or
requiring special handling, are properly stored and maintained.
6. Only the custodian, or in his absence, the alternate, distributes samples
to, or divides them among, personnel performing tests. The custodian
enters into a permanent log book the laboratory sample number, time and
date, and the name of the person receiving the sample. The receiver also
signs the entry.
7. Laboratory personnel are then responsible for the care and custody of the
sample until analytical tests are completed. Upon completion of tests un-
used portion of the sample together with all identifying tags and labora-
tory records are returned to the custodian, who records the appropriate
entries in the log book. These, and other records are retained as
appropriate.
8. The analyst records in his laboratory notebook or worksheet the name of
the person from whom the sample was received, whether it was sealed, iden-
tifying information describing the sample (by origin and sample identifi-
cation number), the procedures performed, and the results of the testing.
If deviations from approved analytical procedures occur, the analyst is
prepared to justify this decision under cross-examination. The notes are
signed and dated by the person performing the tests. If that person is not
available as a witness at time of trial the government may be able to
introduce the notes in evidence under the Federal Business Records Act.
3-23
-------
Samples, tags, and laboratory records of tests may be destroyed only upon the
written order of the laboratory director, who ensures that this information is
no longer required.
The Field Sampling Chain of Custody Form should be completed by the field
sampling team and included with the shipping container when sent to the con-
tractor's laboratory. A separate form should be included with each box of
samples, listing the samples contained in that box. A sample of a completed
form is included for reference (Figure 3-1).
A copy of chain of custody procedures can be obtained by contacting:
National Field Investigation Center
U.S. Environmental Protection Agency
Denver Federal Center
Building #53, Box 25227
Denver. Colorado 80225
Telephone: (303) 234-4650
Other reference materials that can be consulted before developing a sampling
plan are listed below.
1. Sampling petroleum and petroleum products; Method ASTM D270.
2. Sampling industrial chemicals; Method ASTM E300.
3. Benedetti-Pichler, A. A. Theory and principles of sampling for chemical
analysis. In: Walfer, E. J.; and Bell, G., eds. Physical methods in
chemical analysis, Vol. 3. New York, Academic Press, Inc., 1956.
4. Preparing coal samples for analysis,- Method ASTM D2013.
5. Sampling coke for analysis; Method ASTM D345.
6. Guidelines establishing test procedures for the analysis of pollutants,
proposed regulations. Federal Register. 44(233):69464-69575, 1979
December 3.
7. Procedures for level 2 sampling and analysis of organic materials.
Research Triangle Park, NC; U.S. Environmental Protection Agency;
1979 February. 164 p. EPA-600/7-79-033.
8. Test Methods for Evaluating Solid Waste - Physical/Chemical Methods,- SW-
646-1980.
9. Hazardous Waste and Consolidated Permit Regulations, Federal Register.
45(98):33063-33285. 1980 May 19.
3.4 BASIC ANALYSIS OF WASTE [10, 12]
This section discusses the basic physical and chemical information about a
waste that may be required in determining its feasibility for incineration and
3-24
-------
FIELD SWUNG CHAIN Of CUSTODY PORN
LEADER HAKE OF SURVEY OR ACTIVITY DATE OF COLLECTION SHEET
Melvin Priority Pollutant Survey 533.10 9/12/B4 1 of 1
DESCRIPTION OF SHIPMENT
TYPE OF SAMPLE Mater Saoples
TOTAL NUMBER SAMPLE CONTAINERS 10
CONTENTS OF SHIPMENT
FIELD NO. OF CONTAINERS/FIELD NO. ANALYSES REQUIRED - CHECK WHERE APPROPRIATE
SAMPLE NO. PLASTIC CLASS VOA CYANIDE PHENOLS ASBESTOS PESTICIDES METALS VOA 5EHI-
0876 1 /
0895 2 /
1992 1 /
3862 1 • /
3812 3 /
6413 1 •
6863 1
PERSONNEL CUSTODY RECORD . . ,
RELINQUISHED BY (SAMPLER) RECEIVED BY DATE TIME REASON
H. Melvin Harpy Airlines 10/1/84 1600 Delivery to lab
SEALED UNSEALED X SEALED UNSEALED
RELINQUISHED BYRECEIVED BYDATETIMEREASON
Airline Vender 10/3/84 900
Figure 3-1. Field sampling chain of custody form.
3-25
-------
its compatibility for a given incineration facility and in designing an
incineration facility. Basic hazardous waste data helpful in selecting an
incineration system are as follows:
• Type(s) of waste: Physical form - liquid, gas, solid, or
mixture
• Ultimate analysis: C, H, 0, N, S, P, Cl, F, Br, I, ash.
moisture
• Heating value: Btu/lb
• Solids: Size, form, and quantity
• Liquids: Viscosity as a function of temperature, specific gravity
• Sludges: Density, viscosity, and percent solids
• Slurries: Density, viscosity, and percent solids
• Gases: Density
• Special characteristics: Toxicity, corrosiveness, and
other unusual features
• Disposal rate: Peak, average, and minimum (present and
future)
• Trace metals: As, Ba, Cd, Cr, Pb, Hg, Se, Ag
• Major organic compound groups: e.g., aromatics, aliphatics, etc.
It may not be necessary to follow the complete, elaborate analysis protocol
for each shipment of waste from the same source, unless the material is entire-
ly different from earlier shipments. How often the shipments should be sampled,
and for what parameters samples should be analyzed, should be determined on a
case-by-case basis using best engineering judgment by the user of this
handbook.
In matching different wastes with commercial incineration facilities, the
physical form (solid, liquid, etc.) of the wastes is very important. The
criteria used for matching different wastes to the various incineration
facilities are:
(1) Physical form:
Gas, liquid, slurry, sludge, or solid
(2) Temperature range required for destruction:
(a) >2,000°F (>1,087°C)
(b) 1.400-2.000°F (757-1,087°C)
(c) 700-1.400°F (367-757°C)
(d) <700°F (<367°C)
3-26
-------
(3) Off-gases:
(a) Essentially oxides of carbon and nitrogen, and
water vapor
(b) Halogen, sulfur, phosphorus or volatile metal
species
(4) Ash:
Nonfusible, fusible, or metallic
(5) Heating value:
(a) 10,000 Btu/lb (>23 MJ/kg)
(b) 5,000-10,000 Btu/lb (12-23 MJ/kg)
(c) 5,000 Btu/lb (<12 MJ/kg)
Liquid injection, fluidized bed, and rotary kiln incinerators are widely used
to dispose of hazardous waste. A particular incinerator may be better suited
for incineration of a particular type of waste based on the physical character-
istics of the waste. Solids, sludges, and slurries of high viscosity liquids
can be disposed in rotary kiln or fluidized bed incinerators, but not in a
liquid injection incinerator. If the ash resulting from the incineration of a
waste is fusible, fluidized bed incinerators are not well suited for its
disposal. Furthermore, fluidized bed incinerators are not capable of opera-
ting at elevated temperatures, so if a temperature over 2,000°F (1,087°C) is
needed for destruction, rotary kilns or liquid injection incinerators are
applicable. Fluidized bed incinerators are generally not operated at temperatures
above 1,500°F.
The percentages of carbon, hydrogen, oxygen, nitrogen, sulfur, halogens, and
phosphorus in the waste, as well as its moisture content, need to be known to
calculate stoichiometric combustion air requirements and to predict combustion
gas flow and composition. The presence of halogenated and sulfur-bearing
waste can result in the formation of HCl, HF, H2S, and S0? in the incinerator
gases. These must be removed with suitable scrubbing equipment before dis-
charge to the atmosphere. Also, in the incineration of organic wastes contain-
ing chlorine, sufficient hydrogen should be provided by either the waste or
auxiliary fuel for the chlorine to form HCl and not C12. Nitrogen oxides are
produced during high temperature combustion by reaction between nitrogen and
oxygen in the air. Their formation can be reduced by reducing combustion
temperature or excess air, but such controls may cause the formation of other
pollutants. Nitrogen content of waste material is generally low, but the
presence of nitrogen-containing materials (nitrates, ammonium compounds, etc.)
can greatly increase the NO emissions.
A
Trace metals (arsenic, barium, cadmium, chromium, mercury, lead, selenium, and
silver) are a potential cause for concern in incinerator emissions. Analyses
for them should be performed unless it is known that they are or are not
present in the waste. Wastes containing significant amounts of metals will
generally be poor candidates for incineration. Such wastes will require
postcombustion emission control of a special type, and the effluent or solid
waste from the emission control device must in turn be treated as a hazardous
3-27
-------
waste, although considerably reduced in volume and weight from the original
hazardous waste.
Ash content of the waste should be determined to evaluate the potential for
excessive slag formation as well as potential particulate emissions from the
incinerators. Kinematic viscosity and the size and concentration of solids in
a liquid waste are the most important physical properties to consider in
evaluating a liquid waste incinerator design. The physical handling system
and burner atomization techniques are dependent on viscosity and solid content
of the waste. Chemically complex sludges may contain such elements as Na, K,
Mg, P. S, Fe, Al. Ca, Si, 02, N2, C and H2. Several chemical reactions can be
expected to take place in the high temperature oxidizing atmosphere of an
incineration operation of chemically complex sludges. Resulting ash may
contain Na2S04, Na2C03, NaCl, etc. Pure Na2S04 has a melting point of
1,623°F. Pure Na2C03 has a melting point of 1,564°F. However, mixtures of
these two compounds have melting points lower than either one of the two by
themselves. At 47% Na2S04 - 53% Na2C03, the melting point is 1,552°F. Sodium
chloride has a melting point of 1,472°F. In combination with Na2C03, sodium
chloride will lower the melting point of the mixture. At 62 mole % Na2C03,
the eutectic melting point is 1,172°F. Likewise, mixtures of NaCl and Na2S04
form low melting mixture with the eutectic melting point of 1,154°F for a 65
mole % Na2S04 mixture. When all three of these compounds are present, a
mixture melting point as low as 1,134°F is possible. So sludges containing
substantial amounts of sodium can cause defluidization of fluidized bed by
forming low melting eutectic mixtures. Furthermore, if the particles of the
fluidized bed are silica-sand, Na2S04 will react with the silica to form a
viscous sodium-silicate glass, which will cause rapid defluidization.
The heating value of a waste corresponds to the quantity of heat released when
the waste is burned, commonly expressed as Btu/lb. It should be considered in
establishing an energy balance for the combustion chamber and in assessing the
need for auxiliary fuel firing. As a rule of thumb, a minimum heating value
of about 8,000 Btu/lb is required to sustain combustion.
Special characteristics of the waste such as extreme toxicity, mutagenicity or
carcinogenicity, corrosiveness, fuming, odor, pyrophoric properties, thermal
instability, shock sensitivity, and chemical instability should also be con-
sidered in incinerator facility design. Thermal or shock instability are of
particular concern from a combustion standpoint, since wastes with these
properties pose an explosion hazard. Other special properties relate more
directly to the selection of waste handling procedures and air pollution
control requirements.
Chapter 4 discusses detailed procedures for evaluating the design and compati-
bility of incinerators with the basic physical, chemical, and thermodynamic
properties of the waste.
3.5 SUPPLEMENTAL ANALYSIS OF WASTE
In addition to its basic analysis, supplemental analysis of waste to identify
and quantify its major chemical components will be helpful in evaluating waste
for incineration. This information will help to determine whether or not the
3-28
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waste is similar to others that have been successfully incinerated previously,
in a similar facility or in the existing facility. The necessary supplemental
information may be available from sources described in Section 3.2. For
example, the waste generator may have previously analyzed the waste stream or
may have a sufficiently thorough understanding of the process generating the
waste to adequately characterize it.
The supplemental analyses that may be necessary to determine whether a waste
can be effectively incinerated and/or whether a trial burn is required are the
following:
• Level 1 organic analysis
• Specific organic analysis
• Trace metal scan
• Thermal decomposition unit analysis
3.6 ANALYSIS TEST METHODS
All the physical, chemical, and thermodynamic analyses of the waste should be
conducted following ASTH, EPA, or EPA-sponsored equivalent methods. The May
19, 1980 Federal Register (pages 33130 and 33131) identifies approved measure-
ment techniques for each organic chemical and inorganic species (heavy metals)
listed in Section 3001 of RCRA (May 19, 1980 Federal Register). Additional
reference materials that can be consulted for analytical guidance are listed
below:
1. ASTM books.
2. Test methods for evaluating solid waste. Washington, DC; U.S. Environ-
mental Protection Agency; 1980 May. EPA SW-846.
3. Lentzen, D. E.; Wagoner, D. E.,- Estes, E. D.,- and Gutknecht, W. F.
IERL-RTP procedures manual: level 1 environmental assessment, second
edition. Research Triangle Park, NC; U.S. Environmental Protection Agency;
1978 October. 279 p. EPA 600/7-78-201.
4. Guidelines establishing test procedures for the analysis of pollutants,
proposed regulations. Federal Register. 44(233):69464-69575, 1979
December 3.
5. Procedures for level 2 sampling and analysis of organic materials.
Research Triangle Park, NC; U.S. Environmental Protection Agency,-
1979 February. 164 p. EPA-600/7-79-033.
6. Standard methods for the examination of water and wastewater, 14th ed.
Washington, American Public Health Association, 1976. 1193 p.
7. Methods for chemical analysis of water and wastes. Cincinnati, OH;
U.S. Environmental Protection Agency; 1979 March. 463 p.
EPA-600/4-79-020.
3-29
-------
8. Mauser, R.; and Cummins, R. L. Increasing sensitivity of 3-methyl-
2-benzothiazolone hydrazone test for analyses of aliphatic aldehydes
in air. Analytical Chemistry. 56:679, 1964.
9. Kraak, J. C.; and Huber, J. F. K. Separation of acidic compounds by
high-pressure liquid-liquid chromatography involving ion-pair formation.
Journal of Chromatography. 102:331-351, 1974.
10. Smythe, L. E. Analytical chemistry of pollutants. In: Bockris, J. O'M.,
ed. Environmental chemistry. New York, Plenum, 1977.
Thermal decomposition unit analysis is briefly discussed in Section 3.7.
3.7 THERMAL DECOMPOSITION UNIT ANALYSIS [11]
In the interest of safety, it may be necessary that knowledge of the thermal
decomposition properites of a toxic organic substance be obtained before
large-scale incineration is conducted.
In response to this need, a laboratory system has been designed and assembled
by the University of Dayton Research Institute (UDRI) under EPA sponsorship.
This thermal decomposition analytical system (TDAS) is a closed, continuous
system which consists of a versatile thermal decomposition unit followed by
in-line dedicated gas chromatograph-mass spectrometer-data handling computer
(GC-MS-COMP). The objective of this laboratory system is to provide fundamen-
tal thermal decomposition data on a wide variety of organic materials - gases,
liquids, and solids (including polymers).
Thermal decomposition tests were conducted with the TDAS on polychlorinated
biphenyls (PCB's) and on "Hex" wastes. The PCB's were found to have high
thermal stability in air. Furthermore, in oxygen-deficient atmospheres their
thermal stability is increased by at least 390°F (200°C) over that experienced
in air. "Hex" wastes also demonstrated a high degree of thermal stability.
Several chlorinated, aromatic compounds were still present after exposure to
1,470°F (800°C). Further increases in temperature to 1,830°F (1,000°C) decom-
posed all compounds except for low levels of hexachlorobenzene.
Figures 3-2, 3-3, 3-4, and 3-5 illustrate decomposition of hexachlorobiphenyl
in air, decomposition of pentachlorobiphenyl in different gaseous atmospheres,
the effect of oxygen content on decomposition of pentachlorobiphenyl, and the
decomposition profile of Hex wastes, respectively.
The UDRI thermal decomposition analytical system, decomposition experiments,
resulting test data and their interpretation are discussed in detail in Appendix
E. Also, the following articles can be consulted for more information on
TDAS:
1. Rubey, W. A. Design consideration associated with the development of a
thermal decomposition analytical system (TDAS). Dayton, OH; University
of Dayton Research Institute; 1979 May. Technical Report UDR-TR-79-34
(EPA Grant No. R805 117-01-0).
3-30
-------
I
LO
ai
ir.*.r.i.tf-
ttXAOUMMIMCNn
IN AIR
lEIMOUMKNZENI
m «o LOOO
DtPOSUK TWPCTATUK. °C
Figure 3-2. Decomposition of hexachlorobipenyl [11]
100
10
LO
0.1
0.01
0 50
EXPOSURE TEMPERATURE. °C
1.000
Figure 3-3.
Decomposition of pentachlorobipenyl in
different gaseous atmospheres [11] .
3-31
-------
1,000
900
I 800
i
§ 700
600
2,2'. 4,5.5' - PENTACHLOROBIPHENYL
2.00s
0.001 0.01 0.1 1.0 10
CARRIER OXYGEN, vol%
100
Figure 3-4. Effect of oxygen content on decomposition
of pentachlorobiphenyl [11] .
200
0 100 200 300 400 500 600 700 800 900
EXPOSURE TEMPERATURE, °C
Figure 3-5. Decomposition profile of hexachlorobenzene [11].
3-32
-------
2. Duvall, D. S.; Rubey. W. A.; and Mescher. J. A. High temperature decom-
position of organic hazardous waste. Treatment of hazardous waste, pro-
ceedings of the sixth annual research symposium. Cincinnati. OH; U.S.
Environmental Protection Agency; 1980 March, p. 121-131. EPA-600/9-80-011.
The temperature, residence time, and oxygen required to destroy a given waste
by incineration can be determined by thermal decomposition unit analysis or by
a pilot- or full-scale trial burn. It is not necessary to generate tempera-
ture residence time, and oxygen requirement data for wastes for which such
data already exist. Trial burn data for some wastes are presented in Appendices
F and G.
3.8 WORK SHEET
The work sheet presented in this section is designed to help evaluate a waste
for incineration in light of the information presented in this chapter for
waste characterization.
WORK SHEET
Yes No*
1. Background Information
• Is background information available and known?
• Is the SIC code of the waste generating source
known?
• Does the waste fall into an EPA hazardous
waste classification?
• If the waste falls into an EPA hazardous waste
classification, is the EPA hazardous waste
number known?
• Any special characteristics of the waste known?
• Are principal waste components and their per-
centages known?
• Is the detail of the process generating the
waste known?
• Is the waste hazard class according to DOT
regulations known?
2. Waste Sampling
• Is the waste sampled with a compatible sampling
device?
• Is the waste collected in a compatible sample
container?
3-33
-------
Yes No*
• Was sampling plan adequate to collect repre-
sentative samples (determination of sampling
points, number of samples, and samples'
volumes)?
• Were the samples properly handled (preserva-
tion, labeling, and shipping)?
• Was pertinent information adequately recorded
in the field log book?
• Were the chain of custody procedures recom-
mended by EPA's National Field Investigation
Centers followed?
3. Basic Analysis Information
• Are data for specific basic analysis known?
- Physical state of waste at 25°C
- Single phase
- Multiphase
- Vapor pressure
- Viscosity
- Specific gravity
- Melting point
- Boiling point
- Flash point
- Solids (size, form, and quantity)
- PH
- Trace metals (As, Ba, Cd, Cr, Hg, Pb, Se, Ag)
- Net heating value
- Elemental analysis (C, H, 0, N, S, P, Cl, F, Br, I)
- Ash content
- Moisture content
- PCB's
- Presence of
Carcinogen
Pesticide
Odor
- Toxicity
Ingestion
Inhalation
Dermal
Eyes
- Reactivity
- Fire hazard
- Radioactivity
3-34
-------
Yes No*
4. Supplemental Analysis Information
• Are the major chemical components of the waste and their
percentages known?
• If waste is known or suspected to contain potentially
hazardous metals other than those listed in basic analysis
information, are their percentages known?
• Has the waste been tested for thermal decomposition analysis?
• Are the temperature and residence time necessary for destruc-
tion as determined by IDAS known?
• Are any principal hazardous particle decomposition products
identified by IDAS?
• Has the waste been incinerated before and, if so, in what
type of incineration technology?
5. Other Information
• Are past disposal practices for the waste known?
• Are any other wastes similar to the one under consideration
known for good or potential incineration?
• Has the proposed facility and/or technology been used before
to destroy a similar or like waste?
• Are waste generation rates (i.e., peak, average, and minimum)
known (present and future)?
• Are there any trial burn data available for the waste?
• Are any potential health and environmental effects of the
waste known?
6. Waste Incineration Decision
• Can a decision be made about waste incineration with the
available information about the waste and information
available from this chapter and Chapter 4?
• If answer is no to the above question, will any additional
waste characterization information help to make a decision
about waste incineration? —
• If answer is no to the above question, will a trial burn
be necessary? —
*Any response in the "No" column may indicate the possibility that the informa-
tion provided is not sufficient for a decision, and additional information
may be required.
3-35
-------
3.9 REFERENCES
1 Hazardous waste and consolidated permit regulations. Federal Register.
45(98):33121-33133, 1980 May 19.
2 Assessment of industrial hazardous waste practices: leather tanning and
finishing industry. Washington, DC; U.S. Environmental Protection Agency;
1976 November. 233 p. EPA SW-131C.
3 Assessment of hazardous waste practices in the petroleum refining industry.
Washington, DC; U.S. Environmental Protection Agency,- 1976 June. 353 p.
EPA SW-129C.
4. Assessment of industrial hazardous waste practices: paint and allied
products industry, contract solvent reclaiming operations, and factory
application of coatings. U.S. Environmental Protection Agency; 1976.
EPA SW-119C.
5. Alternatives for hazardous waste management in the organic chemical,
pesticides and explosives industries. Cincinnati, OH; U.S. Environmental
Protection Agency; 1977. EPA SW-151C.
6. Assessment of industrial hazardous waste practices: electronic components
manufacturing industry. Washington, DC; U.S. Environmental Protection
Agency,- 1977 January. 207 p. EPA SW-140C.
7 Assessment of industrial hazardous waste practices: special machinery
manufacturing industries. Washington, DC; U.S. Environmental Protection
Agency,- 1977 March. 328 p. EPA SW-141C.
8. Background document. Resource Conservation and Recovery Act; Subtitle C -
Identification and listing of hazardous waste,- Section 261.31 and 261.32 -
Listing of hazardous wastes. Washington, DC; U.S. Environmental Protection
Agency; 1980 May 2.
9. Sampling and sampling procedures for hazardous waste streams. Cincinnati,
OH,- U.S. Environmental Protection Agency; 1980 January. 78 p.
EPA-600/2-80-018.
10 Hazardous material incineration design criteria. Cincinnati, OH,- U.S.
Environmental Protection Agency; 1979 October. 110 p. EPA-600/2-79-198.
11. Duvall, D. S.; Rubey, W. A..- and Mescher, J. A. High temperature decom-
position of organic hazardous waste. Treatment of hazardous waste, pro-
ceedings of the sixth annual research symposium. Cincinnati, OH; U.S.
Environmental Protection Agency,- 1980 March, p. 121-131.
EPA-600/9-80-011.
12. Becker, K. P.; and C. J. Wall. Waste treatment advances: Fluid bed
incineration of wastes. Chemical Engineering Progress. 72:61-68,
1976 October.
3-36
-------
CHAPTER 4
INCINERATOR AND AIR POLLUTION CONTROL SYSTEM DESIGN EVALUATION
-------
CONTENTS
4. INCINERATOR AND AIR POLLUTION CONTROL SYSTEM DESIGN
EVALUATION 4-1
4.1 Introduction 4-1
4.2 Destruction and Removal Efficiency 4-2
4.2.1 Definition 4-2
4.2.2 Sample Calculation 4-3
4.3 Incinerator Evaluation 4-4
4.3.1 Basic Design Considerations 4-6
4.3.1.1 Liquid Injection Incinerators 4-6
4.3.1.2 Rotary Kiln Incinerators 4-7
4.3.2 Physical. Chemical, and Thennodynamic Waste
Property Considerations 4-8
4.3.2.1 Liquid Injection Incinerators 4-8
4.3.2.2 Rotary Kiln Incinerators 4-18
4.3.3 Temperature, Excess Air, Residence Tine, and
Mixing Evaluation 4-20
4.3.3.1 Liquid Injection Incinerators 4-21
4.3.3.2 Rotary Kiln Incinerators 4-33
4.3.4 Auxiliary Fuel Capacity Evaluation 4-41
4.3.4.1 Liquid Injection Incinerators 4-41
4.3.4.2 Rotary Kiln Incinerators 4-42
4.3.5 Combustion Process Control and Safety Shutdown
System Evaluation 4-43
4.3.5.1 Liquid Injection Incinerators 4-43
4.3.5.2 Rotary Kiln Incinerators 4-44
4.3.6 Construction Material Evaluation 4-46
4.4 Air Pollution Control and Gas Handling System Design
Evaluation 4-47
4.4.1 Emission/Air Pollution Control Device Matching
Criteria 4-47
4.4.1.1 Particulate Removal 4-51
4.4.1.2 Gaseous Pollutant Removal 4-52
-------
4.4.2 Air Pollution Control Device Design and Operating
Criteria Evaluation 4-54
4.4.2.1 Venturi Scrubbers 4-54
4.4.2.2 Packed Bed Scrubbers 4-58
4.4.2.3 Plate Tower Scrubbers 4-63
4.4.3 Quenching and Mist Elimination Considerations 4-66
4.4.4 Prime Mover Capacity Evaluation 4-68
4.4.5 Process Control and Automatic Shutdown System
Evaluation 4-73
4.4.6 Material of Construction Considerations 4-74
4.5 Worksheets 4-75
-------
CHAPTER 4
INCINERATOR AND AIR POLLUTION CONTROL
SYSTEM DESIGN EVALUATION
4.1 INTRODUCTION
This chapter presents engineering calculations and general "rules of thumb"
that can be used to determine whether or not incinerator and air pollution
control system design and operating criteria are consistent with good industry
practice and sufficient to meet current emission standards. The evaluation
procedures are intended to determine if (1) the physical, chemical, and thermo-
dynamic properties of the waste have been properly considered in the incinera-
tor and air pollution control device design; (2) the basic design considera-
tions for these units have been addressed; (3) acceptable temperatures,
residence times, oxygen concentrations, and mixing can be achieved and main-
tained in the incinerator; (4) air pollution control system design and operat-
ing criteria are in line with current industry practice and the desired degree
of pollutant removal; (5) various components of the incinerator, air pollution
control, and gas handling systems have sufficient capacity to handle the
quantities of waste to be burned; (6) the design incorporates process control
and automatic shutdown capability to minimize the release of hazardous material
in the event of equipment malfunction,- and (7) appropriate materials of con-
struction are used.
Evaluation procedures are presented for two generic types of incinerators and
three generic types of air pollution control devices: liquid injection incin-
erators, rotary kiln/afterburner incinerators, venturi scrubbers, packed bed
scrubbers, and plate (or tray) tower scrubbers. While liquid injection incin-
erators are used only for disposal of liquid organic wastes, rotary kilns
are used to dispose of both liquid and solid wastes. Venturi scrubbers are
primarily used for particulate control, while packed bed and plate tower
scrubbers are used for acid gas removal. It is believed that more than 90% of
the hazardous waste incineration facilities in the United States employ these
generic incinerator and air pollution control device designs. Electrostatic
precipitators may be used for particulate removal at large incineration
facilities. However, these devices are extremely difficult to evaluate from a
theoretical standpoint; a compliance test is usually needed to ensure accept-
able performance. If other types of incinerators and/or air pollution control
devices are being evaluated technical assistance can be requested.
Incinerator and air pollution control system evaluation procedures are pre-
sented in Sections 4.3 and 4.4, respectively. Section 4.5 presents worksheets
to simplify some of the calculations shown in 4.3 and 4.4.
4-1
-------
The following section, 4.2, describes how the destruction and removal
efficiency (DRE) of an incinerator/air pollution control system can be cal-
culated for the principal organic hazardous constituent (s) (POHC) of a waste.
The current state-of-the-art in combustion modeling does not allow a purely
theoretical prediction of destruction and removal efficiency based on design
and operating parameters for the incinerator/air pollution control system.
Therefore, the DRE calculations presented in Section 4.2 cannot be applied in
preliminary design evaluation unless sampling and analysis data are available.
However, destruction and removal efficiency calculations are an integral part
of the final design evaluation process.
4.2 DESTRUCTION AND REMOVAL EFFICIENCY CALCULATIONS
4.2.1 Definition
Destruction and removal efficiency for an incinerator/air pollution control
system is defined by the following formula:
DRE = w (100)
in
where DRE = destruction and removal efficiency, %
W. = mass feed rate of the principal organic hazardous constituent(s)
111 to the incinerator.
W = mass emission rate of the principal organic hazardous constit-
out uent(s) to the atmosphere (as measured in the stack prior to
discharge .
Thus, DRE calculations are based on the combined efficiencies of destruction in
the incinerator and removal from the gas stream in the air pollution control
system. The (potential) presence of principal organic hazardous constituents
in incinerator bottom ash or solid/ liquid discharges from air pollution con-
trol devices is not accounted for in the DRE calculation as currently defined
by EPA.
Part 264, Subpart 0 regulations for hazardous waste incineration require a DRE
of 99.99% for all principal organic hazardous components of a waste unless it
can be demonstrated that a higher or lower DRE is more appropriate based on
human health criteria. Specification of the principal organic hazardous con-
stituents in a waste is subject to best engineering judgment, considering the
toxicity, thermal stability, and quantity of each organic waste constituent.
DRE requirements in the Subpart 0 regulations do not apply to metals or other
noncombustible materials.
Destruction and removal efficiencies are normally measured only during trial
burns and occasional compliance tests, and are used as a basis for determining
whether or not the incinerator/air pollution control system operating condi-
tions are adequate. Sections 4.3 and 4.4 present design evaluation procedures
for incinerators and air pollution control devices that are based on state-of-
the-art engineering practice. However, any conclusions reached through these
4-2
-------
evaluation procedures should be supported by trial burn data demonstrating
acceptable destruction and removal efficiency.
4.2.2 Sample Calculation
A liquid injection incinerator equipped with a quench tower, venturi scrubber,
and packed bed caustic scrubber has been constructed to burn a mixture of
waste oils and chlorinated solvents with the following empirical composition:
73.0 wt % carbon
16.5 wt % chlorine
10.5 wt % hydrogen
The principal organic hazardous components are trichloroethylene , 1,1,1-tri-
chloroethane, methylene chloride, and perchloroethylene. Each of these com-
pounds constitutes about 5% of the total waste feed to the incinerator.
During a trial burn, the incinerator was operated at a waste feed rate of
5,000 Ib/hr and 50% excess air. The gas flow rate measured in the stack was
19,200 dscfm. Under these conditions, the measured concentrations of the
principle organic hazardous components were:
Trichloroethylene -4.9 pg/dscf
1,1,1-Trichloroe thane - 1.0 ug/dscf
Methylene chloride - 49 pg/dscf
Perchloroethylene - 490 ug/dscf
In order to calculate destruction and removal efficiency for each of these
compounds using the equation,
DRE = (100)
in
it is necessary to calculate the mass flow of each component entering and
exiting the system. Because each hazardous component constitutes about 5% of
the waste and the total waste feed rate was 5,000 Ib/hr, V»in for each compo-
nent is.-
W. = 0.05 (5,000 Ib/hr) = 250 Ib/hr
in
The mass flow rate of each component exiting the stack is then calculated by
the following equation:
(" (19.200 dscfm) (60 min/hr) "I
out i X L 4.54 x 10* Mg/lb J
4-3
-------
where W = mass flow rate of component i exiting the stack, Ib/hr
out
C. = concentration of component i in the stack gas, pg/dscf
Using this equation to calculate W for each component and the previously
cited equation for destruction and removal efficiency, the following results
are obtained:
Component
Trichloroethylene
1 , 1 , l-Trichloroe thane
Methylene chloride
Perchloroethylene
W . Ib/hr
out.
0.0124
0.00254
0.124
1.24
ORE, %
99.995
99.999
99.95
99.5
These results indicate that the required 99.99% destruction and removal effi-
ciency was achieved in the trial burn for trichloroethylene and 1,1,1-tri-
chloroethane, but not for methylene chloride and perchloroethylene.
Worksheet #1 in Section 4.5 presents a generalized procedure for destruction
and removal efficiency calculations.
4.3 INCINERATOR EVALUATION
A logic diagram for evaluating both liquid injection and rotary kiln incinera-
tor designs and operating criteria is shown in Figure 4-1. It consists of six
separate evaluation procedures intended to answer the following questions:
• Are the basic incinerator components properly incorporated in the design?
• Have the physical, chemical, and thermodynamic properties of the waste
been properly considered in the incinerator design and proposed operating
conditions?
• Are the proposed temperature/excess air/residence time combinations
internally consistent and achievable? Can adequate turbulence and mixing
be achieved under these conditions?
• Is the auxiliary fuel firing capacity acceptable?
• Does the design incorporate suitable combustion process control and
safety shutdown interlocks?
• Are appropriate materials of construction employed?
Subsections 4.3.1 through 4.3.6 present background information and procedures
for answering questions.
4-4
-------
BASIC DESIGN
CONSIDERATIONS
SECTION 4.3.1
1
PHYSICAL. CHEMICAL. AND
THERMODYNAMIC WASTE
PROPERTY CONSIDERATIONS
SECTION 4.3.2
1
TEMPERATURE/EXCESS AIR/
RESIDENCE TIME/MIXING
EVALUATION
SECTION 4.3.3
1
AUXILIARY FUEL FIRING
CAPACITY EVALUATION
SECTION 4.3.4
COMBUSTION PROCESS
CONTROL EVALUATION
SECTION 4.3.5
I
MATERIAL OF CONSTRUCTION
CONSIDERATIONS
SECTION 4.3.6
Figure 4-1. Incinerator design evaluation criteria.
4-5
-------
4.3.1 Basic Design Considerations
Liquid Injection Incinerators--
Liquid injection incinerators are usually simple,
(either horizontally or vertically aligned) equipped "ith one or "°"
burners Liquid wastes are injected through the burner(s), atomized t
droplets, and burned in suspension. To heat the unit to operating temperature
before wwte is introduced, however, all liquid injection ^""r^J1*"
should also include an auxiliary fuel firing system. This may consist of
separate burners for auxiliary fuel, dual-liquid burners, "•Jjgj1**""
burners equipped with a premix system whereby fuel flow is gradually turned
doTand wafte flow is increased'after the desired operating temperature> is
Stained. If auxiliary fuel firing is needed during routine operation he
same types of systems are needed: fuel/waste premix, dual-liquid burners, or
separate auxiliary fuel burners.
Each burner, regardless of type, is generally mounted in a refractory block or
ionition tile (see Figure 4-2 for an illustration). This is necessary to
cosine the primary combustion air introduced through the burner to ensure
proper air/waste mixing, and to maintain ignition. The shape of the ignition
file cavity also affects the shape of the flame and the ff-rtigof primary
air which must be introduced at the burner. Some burners and tiles
ranged to aspirate hot combustion gases back into the tile, which aids in
vaporizing the liquid and increasing flame temperature more rapidly.
SCANNER PORT
nun
BURNER BLOCK
rv>"*
^~~r
COMBUSTION AM
"Reproduced courtesy of Trane Thermal Company, Conshohocken, Pa."
Figure 4-2. High heat release burner for
combustion of liquid waste [1].
The dimensions of the burner block, or ignition tile, vary depending on the
burner design. Each manufacturer has his own geometrical specifications,
which ha" been developed through past experience. Therefore, it is not DOS
siJle to specify a single burner block geometry for design evaluation purposes.
However Sis aspect of the design can be checked to eliminate systems that do
not provide for any flame retention.
4-6
-------
The location of each burner in the incinerator and its firing angle, relative
to the combustion chamber, should also be checked. In axial or side-fired
nonswirling units, the burner is mounted either on the end firing down the
length of the chamber or in a sidewall firing along a radius. Such designs,
while simple and easy to construct, are relatively inefficient in their use of
combustion volume. Improved utilization of combustion space and higher heat
release rates can be achieved with the utilization of swirl or vortex burners
or designs involving tangential entry. Regardless of the burner location
and/or gas flow pattern, however, the burner is placed so that the flame does
not impinge on refractory walls. Impingement results in flame quenching, and
can lead to smoke formation or otherwise incomplete combustion. In multiple
burner systems, each burner should be aligned so that its flame does not
impact on other burners.
Engineering judgment is used in predicting whether or not these undesirable
phenomena will occur with a specific incinerator design.
4.3.1.2 Rotary Kiln Incinerators—
To insure complete waste combustion rotary kiln incinerator designs normally
include an afterburner. The primary function of the kiln is to convert solid
wastes to gases, which occurs through a series of volatilization, destructive
distillation, and partial combustion reactions. However, an afterburner is
almost always required to complete the gas-phase combustion reactions. The
afterburner is connected directly to the discharge end of the kiln, whereby
the gases exiting the kiln turn from a horizontal flow path to a vertical flow
path upwards to the afterburner chamber. The afterburner itself may be hori-
zontally or vertically aligned.
Both the afterburner and kiln are usually equipped with an auxiliary fuel
firing system to bring the units up to the desired operating temperatures. As
explained in Section 4.3.1.1 for liquid injection incinerators, the auxiliary
fuel system may consist of separate burners for auxiliary fuel, dual-liquid
burners designed for combined waste/fuel firing, or single-liquid burners
equipped with a premix system, whereby fuel flow is gradually turned down and
liquid waste flow is increased after the desired operating temperature is
attained.
If liquid wastes are to be burned in the kiln and/or afterburner, additional
considerations are:
• flame retention characteristics of the burners,
• burner alignment to avoid flame impingement on refractory walls, and
in multiple burner systems, burner alignment to avoid interference with
the operation of other burners.
These topics are discussed in Section 4.3.1.1 under liquid injection incinera-
tor evaluation.
One difference between liquid injection incinerators and rotary kilns burning
liquid wastes in conjunction with solids is that in the kiln liquid wastes may
4-7
-------
be fired either at the feed or discharge end of the unit. Cocurrent and
countercurrent firing designs are both widely used.
4.3.2 Physical. Chemical, and Thermodvnamic Waste Property Considerations
Jefore'a liquid wastfcan FZSSSL" * must be converted to the gaseous
state Tnis change from a liquid to a gas occurs inside the
=3 i£TM 7=2
to small droplets, usually to a 40 MM size or smaller. Good atomization i
SSris^^r^
at the point of air/ fuel mixing.
The degree of atomization achieved in any burner depends on the kinematic
viscosity of the liquid and the amount of solid impurities present ^qu
sno"d generally have a kinematic viscosity of 10,000 SSU or less to be sat
factorily pumped and handled in pipes. For atomization, they should have a
maximum kiStic viscosity of about 750 SSU. If the "»« gJ/^SS.
exceeds this value the atomization may not be fine enough. Thls.mav """
smoke or other unburned particles to leave the unit. Howev er, this is only a
rule of thumb. Some burners can handle more viscous fluids, while others
cannot handle liquids approaching this kinematic viscosity.
viscositv can be reduced by heating with tank coils or in-line heaters. How-
SE S-S5-r<5o-260-C) is normally the limit for heating to reduce viscos
ity since pumping a hot tar or similar material becomes difficult above these
* "
temperatures. hould gases be evolved in any
DaSeQ On tnese tu»iaA«c* »!.*»«•», — ----- *
added to reduce the viscosity of the mixture; fuel oil for example.
Solid impurities in the waste can interfere with burner operation ^ap1^
gage, erLion, and ash buildup. Both the concentration and size of ^ solids.
relative to the diameter of the nozzle, need to be considered. As discussed
In Cnapter 5 filiation may be employed to remove solids from the waste prior
to injection through the burner.
Liquid waste atomization can be achieved by any of the following means:
rotary cup atomization
• single-fluid pressure atomization
• two-fluid, low pressure air atomization
• two-fluid, high pressure air atomization
• two-fluid, high pressure steam atomization
4-8
-------
can be handled without plugging problems.
AIR OR
STEAM
MECHANICAL FU& TIP BODY f CONE FLAME TIP
iv V'.. X "». . *V
FINAL
SPRAY
STEAM MIXING
ORIFICES CHAMBER
-Reprinted by permission of Chemical Engineering Progress."
Figure 4-3. Internal nix nozzle [2].
WASTE
UOLNO
f
ATOMBNG AUD
GASEOUS WASTE
WASTE NO 1
*
'-> ">
LIQUID
WASTE MO 2
ATOMIZED
LIQUID
ATOMIZED
LIQUIDS
ATOMIZING HUIO
GASES
-Reproduced courtesy of Trane Thermal Company, Conshohocken, Pa."
Figure 4-4. External mix nozzles [1] .
4-9
-------
snuraoucrai
• SONIC KAVI AK
Reprinted by permission of Fluid Kinetics, Inc.
Figure 4-5. Sonic atomizing nozzle [3].
atomizing liquids with relatively high solids content. Burner turndown is
about 5:1 and capacities from 1 to 265 gal/hr, (1-280 cm3/S) are available.
In single-fluid pressure atomizing nozzle burners, the liquid is given a swirl
as it passes through an orifice with internal tangential guide slots. Moder-
ate liquid pressures of 100-150 psi provide good atomization with low to
moderate liquid viscosity. In the simplest form, the waste is fed directly to
the nozzle but turndown is limited to 2.5 to 3:1 since the degree of atomiza-
tion drops rapidly with decrease in pressure. In a modified form, involving a
return flow of liquid, turndown up to 10:1 can be achieved.
When this type of atomization is used, secondary combustion air is generally
introduced around the conical spray of droplets. Flames tend to be short,
bushy, and of low velocity. Combustion tends to be slower as only secondary
air is supplied and a larger combustion chamber is usually required.
Typical burner capacities are in the range of 10 to 105 gal/hr. Disadvantages
of single-fluid pressure atomization are erosion of the burner orifice and a
tendency toward pluggage with solids or liquid pyrolysis products, particu-
larly in smaller sizes.
Two-fluid atomizing nozzles may be of the low pressure or high pressure vari-
ety, the latter being more common with high viscosity materials. In low
pressure atomizers, air from blowers at pressures from 0.5 to 5 psig is used
to aid atomization of the liquid. A viscous tar, heated to a viscosity of
15-18 centistokes, requires air at a pressure of somewhat more than 1.5 psig,
while a low viscosity or aqueous waste can be atomized with 0.5 psig air. The
waste liquid is supplied at a pressure of 4.5-17.5 psig. Burner turndown
ranges from 3:1 up to 6:1. Atomization air required varies from 370 to
1,000 ft3/gal of waste liquid. Less air is required as atomizing pressure is
increased. The flame is relatively short as up to 40% of the stoichiometric
air may be admixed with the liquid in atomization.
High pressure two-fluid burners require compressed air or steam at pressures
from 30 to 150 psig. Air consumption is from 80 to 210 ft3/gal of waste, and
steam requirements may be 2.1 to 4.2 Ib/gal with careful control of the oper-
ation. Turndown is relatively poor (3:1 or 4:1) and considerable energy is
4-10
-------
employed for atomization. Since only a small fraction of sto"hlom^"
is used for atomization, flames tend to be relatively long The major ad-
vantage of such burners is the ability to burn barely pumpable liquids "J
further viscosity reduction. Steam atomization also tends to reduce soot
formation with wastes that would normally burn with a smoky flame.
Table 4-1 identifies typical kinematic viscosity and solids handling "•
tions for the various atomization techniques. These data are based on a
survey of 14 burner manufacturers. In evaluating V!K° V* shluld £e
Ssim however the viscosity and solids content of the wastes should be
compared with manufacturer specifications for the particular burner employed.
TABLE 4-1 KINEMATIC VISCOSITY AND SOLIDS HANDLING LIMITATIONS
OF VARIOUS ATOMIZATION TECHNIQUES
Maximum
kinematic . . .
viscosity. Maximum solids Maximum solids
Atomization type _ SSU _ mesh size - concentration
Rotary cup 175 to 300 35 to 100 20%
irn Essentially zero
Single-fluid pressure 150
10n Essentially zero
Internal low pressure 100
air (<30 psi)
External lo. pressure air 200 to 1,500 ZOMdepend, on
External high pressure 150 to 5.000 100 to 200 (depends 70%
. on nozzle 111;
External high pressure 150 to 5,000 100 to 200 (depends 70%
steam on nozzle ID)
S/S3S
assumed:
lAir requirements, combustion gas flow, and gas composition form the basis
for many subsequent evaluation procedures.
4-11
-------
c + o2 -» co2
H2 + 1/202 -»• H20
H20 f H20
N2 * N2
C12 + H20 •» 2HC1 + 1/202
F2 + H20 -*• 2HF + 1/202
Br2 -»• Br2
I2 * I2
S * 02 -» S02
2P + 2.502 * P205
TABLE 4-2. EVALUATION PROCEDURE FOR PHYSICAL WASTE
PROPERTY/ATOMIZATION TECHNIQUE COMPATIBILITY
1. Identify the atomization technique employed.
2. Identify the kinematic viscosity of the waste at the proposed injection
temperature.
3. Check Table 4-1 and/or burner manufacturer specifications to determine if
the waste viscosity and atomization technique are compatible.
4. Identify the solids content of the waste and the maximum size of the
particles (after pretreatment, if any).
5. Check Table 4-1 and/or burner manufacturer specifications to determine if
the solids content of the waste and the atomization technique are
compatible.
Table 4-3 shows the stoichiometric or theoretical oxygen requirements and com-
bustion product yields for each of these reactions. Once the weight fraction
of each element in the waste has been determined, the stoichiometric oxygen
requirements and combustion product yields can be calculated on a Ib/lb waste
basis. The stoichiometric air requirement is determined directly from the
stoichiometric oxygen requirement via the weight fraction of oxygen in air.
Of course, the reactions listed above are not the only ones that occur in com-
bustion processes. Carbon, carbon monoxide, free hydrogen, nitrogen oxides,
free chlorine and fluorine, hydrogen bromide and iodide, sulfur trioxide, and
4-12
-------
TABLE 4-3. STOICHIOMETRIC OXYGEN REQUIREMENTS
AND COMBUSTION PRODUCTS YIELDS
Elemental
waste Stoichiometric Combustion
component oxygen requirement product yield
C 2.67 Ib/lb C 3.67 Ib C02/lb C
H2 8.0 Ib/lb H2 9.0 Ib H20/lb H2
Oo -1.0 Ib/lb 02
S2 - 1.0 Ib N2/lb N2
H20 - 1.0 Ib H20/lb H20
Cl, -0.23 Ib/lb C12 1-03 Ib HCl/lb C12
2 -0.25 Ib H20/lb C12
F -0 42 Ib/lb F2 1-05 Ib HF/lb F2
2 -0.47 Ib H20/lb F2
Br - 1.0 Ib Br2/lb Br2
I 2 - 1.0 Ib I2/lb I2
s2 10 Ib/lb S 2.0 Ib S02/lb S
P l".29 Ib/lb P 2.29 Ib P205/lb P
Air N2 - 3.31 Ib N2/lb (02)stoich
Stoichiometric air requirement = 4.31 x (02)stoich
hydrogen sulfide. among other compounds, are also formed to some extent when
the corresponding elements are present in the waste or fuel being *»™J-
However, these combustion product yields are usually small in comparison to
the Yields of the primary combustion products identified above, and need not
be considered in gas flow scoping calculations. (They do however need to be
considered to determine the potential products of incomplete ""tuition)-For
most organic wastes and fuels, nitrogen, carbon dioxide, and ^e£ ^^e
the major combustion products. When excess air is factored into th« combus
tion gas flow, oxygen also becomes a significant component of the gas. Excess
air requirements are discussed in Section 4.3.3.
Exceptions to the aforementioned combustion stoichiometry can occur when
K-i«hiw r-hlorinated or fluorinated wastes are being burned and insufficient
hydrogenis present for equilibrium conversion to the halide form. Since
hydrogen halides are much more readily scrubbed from combustion gases than
"* y . U..J--,,-,, ehonlH he nrovided for this equili-
HO/ 35.5 Ib C12 and 1 Ib Ho/19 Ib Fg in the waste.
Equilibrium between halogens and hydrogen halides in incinerator gases is
given by:
X2 + H20 = 2HX + 1/2 02
4-13
-------
where X2 represents any free halogen.
For chlorine, this expression becomes:
C12 + H20 = 2HC1 + 1/2 02
At equilibrium, the concentrations of C12, H20, HCl, and 02 in the combustion
gas (at essentially atmospheric pressure) is given by:
*<> * <"C12>
where K = equilibrium constant
p. = partial pressure of ith component, atra
Figure 4-6 presents a plot of the equilibrium constant, K , vs. temperature
for the conversion of C12 to HCl. If the combustion temperature is known, K
can be identified from Figure 4-6 and the following equation can be used to
predict the extent of conversion of C12 to HCl.
(po»i
where x = fractional conversion of C12
p • ' pn • • p« n • = calculated partial pressures of C12 , 02 , and H20
Cl2i 02i H20i assuming that all organic chlorine is converted
to C12 before the reaction to form HCl occurs.
In addition to the aforementioned waste constituents, metallic elements pre-
sent in the waste influence the assessment of air pollution control require-
ments and materials of construction (e.g., refractory type). However, the
metals content of a waste will not significantly affect the stoichiometric air
requirements or combustion gas flow rate.
The heating value of a waste corresponds to the quantity of heat released when
the waste is burned, commonly expressed as Btu/lb. Since combustion reactions
are exothermic, all organic wastes have some finite heating value. However,
the magnitude of this heating value must be considered in establishing an
energy balance for the combustion chamber and in assessing the need for auxil-
iary fuel firing. To maintain combustion, the amount of heat released by the
burning waste must be sufficient to heat incoming waste up to its ignition
temperature and to provide the necessary activation energy for the combustion
reactions to occur. Activation energy, expressed as Btu/lb or the equivalent,
4-14
-------
100
-------
is the quantity of heat needed to destabilize molecular bonds and create
reactive intermediates so that the exothermic reaction with oxygen will pro-
ceed. Figure 4-7 shows the general relationship between activation energy and
heating value.
T
ACTIVATION
ENERGY
I
HEAT OF
COMBUSTION
,1
REACTION
Figure 4-7. Relationship between activation energy and heat of combustion.
Note: The diagram is simplified in the sense that it shows a single activa-
tion energy for the reaction. Reactions with more than one intermediate
have correspondingly more activation energy levels.
Waste heating values needed to sustain combustion without auxiliary fuel
firing depend on the following criteria:
• physical form of the waste (i.e., gaseous vs. liquid vs solid),
temperature required for refractory waste component destruction,
• excess air rate, and
• heat transfer characteristics of the incinerator.
In general, higher heating values are required for solids vs liquids vs gases,
for higher operating temperatures, and for higher excess air rates, if combus-
tion is to be sustained without auxiliary fuel consumption. Gases can sustain
combustion at heating values as low as 3,000 Btu/lb, while 4,500 to
5,500 Btu/lb may be considered minimum heating value requirements for combus-
tion of liquid wastes in high efficiency burners [1]. Higher heating values
are needed for solid wastes, but the requirements depend on particle size, and
thus, the area available for heat and mass transfer. In the hazardous waste
incineration industry, it is common practice to blend wastes (and fuel oil, if
necessary) to an overall heating value of 8,000 Btu/lb.
4-16
-------
When an organic waste exhibits a low heating value, it is usui ly due to high
concentrations of moisture or halogenated compounds. Since water is an ulti
mate oxidation product, it has no heating value. In fact, a po
heat generated by combustion of the organic waste fraction is consumed in
vaporizing and heating the moisture up to incinerator temperature^ Therefore ,
an increase in the moisture content of an organic waste proportionately de
creases the overall heating value on a Btu/lb waste basis.
The heating value of a waste also decreases as the chlorine
content increases, although there is no simple mathematical
Fioure 4-8 shows an empirical relationship between heating value and chlorine
cogent for p£e substances. At chlorine contents of 70% or greater auxil-
iary fuel is needed to maintain combustion. Auxiliary fuel may also be re-
quited for less highly chlorinated waste unless high efficiency burners are
used.
X EXPERIENCED RESULTS
10.000
1.000
10 20
30 « 50 60 70
CHLORINE CONTENT. Wt *
1.800
"Reproduced courtesey of Trane Thermal Company, Conshohockon, Pa."
Figure 4-8. Heat of combustion of chlo-
rinated hydrocarbons [4].
in hazardous waste incineration, it is common practice to blend wastes so that
the chlorine content does not exceed 30%. This is done to maintain sufficient
heating value for sustained combustion and to limit free chlorine
concentration in the combustion gas.
When heating value data are reported for a given waste, it is desirable to
too" whetne? they are "higher heating values," "lower heating values "or "net
Sating values." The difference between the higher heating value and lower
heatSg value of a material is that the higher value includes the heat of con-
densation of water formed in the combustion reaction. In ^e combustion of
methane, for example, the higher heating value is based on the following
stoichiometry:
CH4 + 202, * C02, x + 2H2°(£)
where the subscripts g and £ represent gaseous and liquid states, respectively.
The lower heating value is based on:
4-17
-------
OT4(g) + 2°2(g) * c°2(g) * 2H2°<*>
The net heating value of a waste is determined by subtracting from its lower
heating value the energy necessary to vaporize any moisture present in the
waste initially. Thus high aqueous wastes may exhibit a negative net heating
value. Since this quantit? represents the true energy input to the combustion
process, only net heating values should be used in developing energy balances
for incinerators.
riori.
The heating value of a complex waste mixture is difficult to predict a _
Therefore, these values should be measured experimentally. Since heating
values measured using oxygen bomb calorimeters are higher heating values,
conversion to the net heating value is required for energy balance calcula-
tions. Worksheet 4-3 in Section 4.5 shows how this conversion is performed.
Approximate net heating values for common auxiliary fuels are:
Residual fuel oil (e.g., No. 6) - 17,500 Btu/lb
Distillate fuel oil (e.g.. No. 2) - 18,300 Btu/lb
Natural gas - 19,700 Btu/lb (1,000 Btu/scf)
Special characteristics of a waste such as extreme toxicity. mutagenicity or
carcinogenicity, corrosiveness, fuming, odor, pyrophoric properties, thermal
instability, shock sensitivity, and chemical instability should also be con-
sidered in incinerator facility design. Thermal or shock instability is of
particular concern from a combustion standpoint, since wastes with these
properties pose an explosion hazard. Other special properties relate more
directly to the selection of waste handling procedures and air pollution
control requirements. If potentially explosive wastes are encountered, technical
assistance is advised.
Table 4-4 presents a procedure for chemical and thermodynamics waste property
evaluation.
4.3.2.2 Rotary Kiln Incinerators— .
When liquid wastes are to be burned in the kiln or afterburner, the kinematic
viscosity of the liquid and its solids concentration and solids particle size
must be considered to determine whether or not good atomization can be achieved
with the proposed burner design. This subject is addressed in subsection 4.3.2.1
under liquid injection incinerator evaluation. The procedure outlined in
Table 4-2, along with the discussion preceding this table, can be used to
check physical waste property/burner compatibility for rotary kiln
incinerators burning liquid wastes.
Although liquid wastes are frequently incinerated in rotary kilns kilns are
primarily designed for combustion of solid wastes. They are exceedingly
versatile in this regard, capable of handling slurries, sludges, bulk solids
of varying size, and containerized wastes. The only wastes that create prob-
lems in rotary kilns are (1) aqueous organic sludges that become sticky on
drying and form a ring around the kiln's inner periphery, and (2) solids
(eg drums) that tend to roll down the kiln and are not retained as long as
the bulk of solids. To reduce this problem, drums and other cylindrical
4-18
-------
TABLE 4-4. CHEMICAL AND THERMODYNAMIC WASTE
PROPERTY EVALUATION PROCEDURE
1 Identify the elemental composition and moisture content of the waste and
record this information on Worksheet 4-2 for future reference.
2. Does the waste contain chlorinated or fluorinated materials? (If YES,
proceed to checkpoint #3. If NO, proceed to checkpoint #5.)
3 Is sufficient hydrogen present in the waste for equilibrium conversion of
chlorine and fluorine to hydrogen chloride and hydrogen fluoride, respec-
tively? See aforementioned evaluation criteria in Section 4.3.2.1. (If
YES, proceed to checkpoint #5. If NO, proceed to checkpoint #4.)
4. Is auxiliary fuel firing or steam injection employed to provide the
necessary hydrogen equivalents?
5 Identify the major components of the combustion gas, based on the ele-
mental composition of the waste, that need to be considered in subsequent
material and energy balance calculations. See Worksheet 4-2 for the
recommended procedure. This procedure also determines the stoichiometric
air requirement and combustion gas flow, which will be needed for subse-
quent evaluation procedures.
6 Determine the net heating value of the waste. Worksheet 4-3 shows how
the net heating value can be calculated when higher heating values are
known.
7 Does it appear likely that the waste will sustain combustion, based on
its net heating value? (If YES, proceed to checkpoint #9. If NO, pro-
ceed to the following checkpoint.)
8. Is auxiliary fuel to be burned in conjunction with the waste?
9. Is the waste potentially explosive when exposed to high temperature or
shock?
•
containers are usually not introduced to the kiln when it is empty. Other
solids in the kiln help to impede the rolling action.
The major design checkpoint for rotary kiln/physical waste property
compatibility is the type(s) of solid waste feed systems employed. These feed
systems are discussed in Chapter 5.
Chemical and thermodynamic properties of the waste that need to be considered
in rotary kiln design evaluation are its elemental composition, its net heat-
ing value, and any special properties (e.g., explosive properties, extreme
toxicity) that may interfere with incinerator operation or require special
design considerations. These are essentially the same properties that must be
4-19
-------
considered in liquid injection incinerator evaluation. Therefore, the back-
ground discussion in Section 4.3.2.1 and the evaluation procedure presented in
Table 4-4 can be used for rotary kilns as well as liquid injection
incinerators with some modifications.
The first modification relates to the calculation procedures for stoichio-
metric air requirement, combustion gas flow and composition. These calcula-
tions are more complex for rotary kiln incinerators because (a) liquid and
solid wastes may be fed simultaneously to the kiln, and (b) liquid wastes and
auxiliary fuel may be fed to the kiln,afterburner, or both. Therefore, Work-
sheet 4-4 (See Section 4-5) should be used instead of Worksheet 4-2 for com-
bustion gas flow calculations. Worksheet 4-3 can still be used to calculate
net heating values.
The second modification relates to the consideration of special waste proper-
ties. As discussed in Section 4.3.2.1 for liquid injection incinerators,
technical assistance may be required if wastes with explosive properties are
encountered. For rotary kilns, technical assistance is also advised if ex-
tremely toxic, mutagenic, or carcinogenic wastes are to be burned. This
recommendation is based on the fact that kilns are much more prone to release
of fugitive emissions than are liquid injection incinerators.
Unlike liquid injection incinerators which have no moving parts, rotary kiln
designs incorporate high temperature seals between the stationary end plates
and rotating section. These seals are inherently difficult to maintain air-
tight, which creates the potential for release of unburned wastes. Rotary
kilns burning hazardous wastes are almost always operated at negative pressure
to circumvent this problem, however, difficulties can still arise when batches
of waste are fed semi-continuously. When drums containing relatively volatile
wastes are fed to the kiln, for example, extremely rapid gas expansion occurs.
This results in a positive pressure surge at the feed end of the kiln (even
though the discharge end may still be under negative pressure), which forces
unburned waste out through the end plates seals. This phenomenon is known as
"puffing", and can pose a major problem if extremely toxic or otherwise
hazardous materials are being burned.
Fugitive emissions can also exit the kiln through the feed chute if improperly
designed. Therefore, the design of the solid waste feed system is an extreme-
ly important consideration in evaluating rotary kiln incinerators. This topic
is addressed in Chapter 5.
4.3.3 Temperature, Excess Air, Residence Time, and Mixing Evaluation
Temperature, residence time, oxygen concentration, and the degree of air/waste
mixing achieved are the primary variables affecting combustion efficiency in
any incinerator design. The theoretical significance of these interrelated
variables is discussed in the following subsection under "Liquid Injection
Incinerators." Subsection 4.3.3.2 addresses additional temperature, time,
excess air, and mixing considerations for rotary kilns.
In general, two major factors are involved in evaluating these variables as
they relate to incinerator design. The first factor is whether or not the
temperature, residence time, and excess air level, along with the degree of
4-20
-------
mixing achieved in the incinerator, are adequate for waste destruction. The
second factor is whether or not the proposed operating conditions are
achievable, since temperature, excess air, residence time, and mixing are all
interrelated.
At the current state of the art, the adequacy of incinerator operating condi-
tions can only be determined by past experience with the waste or by actual
testing. Therefore, this factor is not addressed ger se in the following
subsections. The major focus of the following evaluation procedures is on
whether or not a proposed set(s) of operating conditions is achievable.
Basically, this involves a series of internal consistency checks.
4.3.3.1 Liquid Injection Incincerators—
The most basic requirement of any combustion system is a sufficient supply of
air to completely oxidize the feed material. The stoichiometric, or theoreti-
cal air requirement is calculated from the chemical composition of the feed
material, as shown in Section 4.3.2. If perfect mixing could be achieved and
liquid waste burnout occurred instantaneously, then only the stoichiometric
requirement of air would be needed. Neither of these phenomena occur in
real-world applications, however, so some excess air is always required to
ensure adequate waste/air contact. Excess air is usually expressed as a
percentage of the stoichiometric air requirement. For example, 50-s excess air
implies that the total air supplied to the incinerator is 50% greater than the
stoichiometric requirement.
The amount of excess air used or needed in a given application depends on the
degree of air/waste mixing achieved in the primary combustion zone, process-
dependent secondary combustion requirements, and the desired degree of combus-
tion gas cooling. Since excess air acts as a diluent in the combustion
process it reduces the temperature in the incinerator (e.g., maximum theoret-
ical temperatures are achieved at zero percent excess air). This temperature
reduction is desirable when readily combustible, high heating value wastes are
being burned in order to limit refractory degradation. When high aqueous or
other low heating value waste is being burned, however, excess air should be
minimized to keep the system temperature as high as possible. Even with
highly combustible waste, it is desirable to limit excess air to some extent
so that combustion chamber volume and downstream air pollution control system
capacities can be limited.
In liquid injection incinerators, two excess air rates must be considered:
(1) the excess air present in the primary combustion air introduced through
the burner and (2) the total excess air, which includes secondary combustion
air. Normally, 10% to 20% excess air (i.e., 1.1 to 1.2 times the stoichio-
metric requirement) is supplied to the burner to prevent smoke formation in
the flame zone. When relatively homogeneous wastes are being burned in high
efficiency burners, 5% excess air may be adequate. Too much excess air
through the burner is also undesirable, since this can blow the flame away
from its retention cone. Burner manufacturer specifications are the best
source of information for analysis.
In general, the total excess air rate should exceed 20% to 25% to insure ade-
quate waste/air contact in the secondary combustion zone. However, the
4-21
-------
minimum requirement for a given incinerator depends on the degree of mixing
achieved and waste specific factors.
Four basic questions should be considered in evaluating whether or not a
proposed operating temperature is sufficient for waste destruction:
(1) Is the temperature high enough to heat all waste components (and combus-
tion intermediates) above their respective ignition temperatures and to
maintain combustion?
(2) Is the temperature high enough for complete reaction to occur at the
proposed residence time?
(3) Is this temperature within normal limits for the generic design and/or
attainable under the other proposed operating conditions?
(4) At what point in the combustion chamber is the proposed temperature to be
measured?
Complete waste combustion requires a temperature, and heat release rate, in
the incinerator high enough to raise the temperature of the incoming waste
constituents above their respective ignition temperatures (i.e., to provide
energy input in excess of their respective activation energies). In cases
where combustion intermediates are more stable than the original waste con-
stituents, higher temperatures are required for complete combustion of the
intermediates than for parent compound destruction.
Since heat transfer, mass transfer, and oxidation all require a finite length
of time, temperature requirements must also be evaluated in relation to the
proposed residence time in the combustion chamber. Heat transfer, mass trans-
fer, and kinetic reaction rates all increase with increasing temperature,
lowering the residence time requirements. For extremely short residence
times, however, temperatures higher than those needed for ignition may be
required to complete the combustion process.
The current state of the art in combustion modeling does not allow a purely
theoretical determination of temperature and residence time requirements for
waste and combustion intermediate destruction. Therefore, the only reasonable
alternative is an examination of temperature/residence time combinations used
to destroy the same or similar waste in a similar or identical incinerator.
After addressing the temperature requirements for waste destruction, it is
reasonable to determine whether or not the proposed temperature is within
normal limits for the generic incinerator design and whether or not this tem-
perature can be attained under the proposed firing conditions. Generally,
liquid injection incinerator temperatures range from 1,400°F to 3,000°F depend-
ing on the generic design, type of waste being burned, and location within the
combustion chamber. Usually 1,400°F is the minimum temperature needed to
avoid smoke formation. A more typical hazardous waste incineration tempera-
ture is 1,800°F, although temperatures of 2,000°F to 2,200°F or higher are
usually employed for halogenated aromatic wastes.
4-22
-------
The question of whether or not the proposed temperature and ««"
s
outputs for the combustion chamber.
ENTHALPY OF
INCOMING WASTE,
AIR.AUXILIARY
FUEL
HEAT LOSS THROUGH
REFRACTORY
ENTHALPY OF
COMBUST! ON GASES
HEAT OF WASTE/
AUXILIARY FUEL
COMBUSTION
Figure 4-9. Energy balance for combustion chamber.
the general relationship:
/ Heat loss \ _ / Enthalpy of \ + / Heat released by \ .
(through refractoryJ ' ^ incoming feed J (^ combustion J
Enthalpy \
of combus- I
tion gases/
or
Since enthalpy is a thermodynamic state function, the overall enthalpy change
can be represented by any series of incremental enthalpy changes, so long as
Figure 4-10.
Using this approach, the overall energy balance equation becomes:
Q = AH =
4-23
-------
where AH._. = incremental enthalpy changes, Btu/lb waste
J ™ K
In Figure 4-10, the first enthalpy change, AH!_2, represents the difference in
feed enthalpy between injection temperature and standard conditions of 77°F
(25°C). This term is seldom significant unless the combustion air is
preheated to high temperature.
WASTE AND AIR
AT INJECTION
TEMPERATURE
COMBUSTION PRODUCTS,
UNREACTED WASTE, AND
EXCESS AIR AT COMBUSTION
TEMPERATURE
WASTE AND AIR
AT 77°F (25°C)
COMBUSTION PRODUCTS.
UNREACTED WASTE. AND
EXCESS AIR AT
77°F (25°C)
Figure 4-10. Enthalpy balance for combustion processes.
The term AH2_3 represents the heat released by combustion at isothermal condi-
tions of 25°C. This corresponds to the way in which heats of combustion are
measured and presented in the literature. The third term, AH3_4, represents
the difference in combustion product enthalpy between 25°C and the temperature
at the combustion chamber outlet.
In mathematical terms, these incremental enthalpy changes are expressed as:
AH,
k
§
waste
components
li Cpi(7? ' Tin>
4-31Cpair <77-Tair><°*>
stoich
(1 + EA)
4-24
-------
.3
niXii
77°F
reactive
waste
components
and
_4
i.! "i Pi i
reaction
products
i=l
reactive
waste
components
remaining
n. C (1 - X.)
+ 4'31 Cp .ir(0«>.toich(n>
"iCpi
reactive
components
inert
waste
components
where n. = Ib ith component/Ib waste
C . = mean heat capacity of ith component over the temperature
pl range involved, Btu/lb °F
T. = waste injection temperature, °F
in
T . = air inlet temperature, °F
air
X. = fractional conversion of ith component (X^ = 1.0 at 100%
1 combustion of ith component)
(AH ). = heat of combustion of ith component at 77°F (25°C), Btu/lb
c 177°F
T = temperature at the combustion chamber outlet, °F
out v
(02) . = stoichiometric oxygen requirement, Ib 02/lb waste
EA = excess air, %/100
4-25
-------
To determine whether or not the proposed temperature/excess air combination is
achievable, it is necessary to specify the desired temperature and calculate
the corresponding excess air rate for comparison with the proposed value.
However, there are far too many unknowns in these equations to solve for EA.
These equations can be simplified considerably by assuming that the combustion
reactions go to essentially 100% completion. With this assumption, the
overall energy balance reduces to:
waste'77 - Tin>
4'31
air(7? ' I
- 77)
.ir
i=l
combustion
products
><°«>
.toich
<1 + EA>
.
* 4.31
p air
stoich
EA
where NHV = net heating value of the waste, Btu/lb
From the empirical waste composition (carbon content, hydrogen content, etc.).
proposed excess air rate, and combustion stoichiometry discussed in Section
4.3.2, all the variables in this equation are fixed except the outlet temper-
ature or excess air rate, mean heat capacities of the combustion gases, and
the heat loss through the walls of the combustion chamber. To avoid rigorous
heat transfer calculations, this heat loss can be assumed to be about 5% of
the heat released in the combustion chamber, based on operating experience
with hazardous waste incinerators. With this assumption, the energy balance
reduces to:
«aste<77 - Tin>
air<77 ' Tair
EA)
4-31 C . <02)
p airW2/stoich
EA
combustion
products
out
- 77) = 0
from which the first two terms can be deleted if neither waste nor air pre-
heating is employed. (The waste enthalpy term can almost always be deleted
anyway.) This yields:
Acceptance of the proposed temperature/residence combination should ensure
combustion efficiencies close enough to 100% for this value to be used in
heat balance calculations.
4-26
-------
0.95 (-NHV)
ffc
^•^^v i ni
4'31 Cp air<°2>
stoich
EA
combustion
.products
-------
0.95
[(-
^NHV)fuel+
K
E **=
*fuel
(n
i fuel pij
waste
combustion
products
+ 4.31 C . <02)
p airW2'stoich
EA
(T
out
- 77) - 0
fuel
combustion
products
where n. = lb ith combustion gas component/Ib fuel
C~ = mean heat capacity of fuel over the applicable temperature
p fuel range, Btu/lb °F
NHV£ , = heating value of fuel, Btu/lb
"
fuel
fuel/lb waste
If only carbon, hydrogen, oxygen, and nitrogen are present, the equation can
be simplified to :
0.95
[0.
26
+ 0.49
+ 1.12 <02)stoicn EA] (T^ - 77) - 0
By fixing the outlet temperature at the proposed value, the equations shown
above can be used to estimate the maximum achievable excess air rate for
comparison with that proposed. Thus, the equations provide an internal consis-
tency check for proposed temperature/excess air combinations. Worksheet 4-5
in Section 4-5 shows how the calculation can be performed in a step-by-step
manner.
When identifying a minimum temperature acceptable for waste destruction, it is
also important to identify the location in the combustion chamber at which
ln this equation, n^, n^
waste/auxiliary fuel mix, and
, <02)
stoich
. and EA apply to the combined
accounts refers to the nitrogen present in
the combustion gases under stoichiometric conditions.
4-28
-------
this temperature should be measured. Temperature varies tremendously from one
point to another in the combustion chamber, being highest in the flame and
lowest at the refractory wall or at a point of significant air infiltration
(e.g., in the vicinity of secondary air ports). Ideally, temperature should
be measured in the bulk gas flow at a point after which the gas has traversed
the combustion chamber volume that provides the specified residence time for
the unit. It should not be measured at a point of flame impingement or at a
point directly in sight of radiation from the flame. Chapter 5 discusses
temperature measurement in more detail.
A comprehensive evaluation procedure for temperature/excess air considerations
is shown in Table 4-5 (on page 4-31).
In addition to temperature and excess air, residence time is a key factor
affecting the extent of combustion. This variable, also referred to as reten-
tion time or dwell time, is the mean length of time that the waste is exposed
to the high temperatures in the incinerator. It is important in designing and
evaluating incinerators because a finite amount of time is required for each
step in the heat transfer/mass transfer/ reaction pathway to occur.
In liquid waste combustion, discrete (although short) time intervals are re-
quired for heat transfer from the gas to the surface of the atomized droplets,
liquid evaporation, mixing with oxygen in the gas stream, and reaction, which
itself involves a series of individual steps depending on the complexity of
the waste's molecular structure. The total time required for these processes
to occur depends on the temperature in the combustion zone, the degree of
mixing achieved, and the size of the liquid droplets. Residence time require-
ments increase as combustion temperature is decreased, as mixing is reduced,
and/or as the size of discrete waste particles is increased. Typical
residence times in liquid injection incinerators range from 0.5 s to 2.0 s.
Gas residence times are defined by the following formula:
6 -/" ^
8 "Jo q
where 6 = mean residence time, s
V = combustion chamber volume, ft3
q = gas flow rate, ft3/s within the differential volume, dv
and gas flow rate is given by:
<°*>stoich
where y = mole fraction N2 in the gas within the differential volume
N2
T = gas temperature, °F, within the differential volume
4-29
-------
(02) • h = stoichiometric oxygen requirement, scf/s
EA = excess oxygen fraction, %/100, within the differential
volume
As indicated in this equation, residence time is not an independent variable.
For an incinerator of fixed volume and relatively constant feed, residence
time is influenced by the temperature and excess air rate employed.
Gas flow rate at any point along the length of the combustion chamber is a
function of the temperature at that point, the amount of excess air added up
to that point, and the extent to which the combustion reactions are completed
at that point. Therefore, solution of the above equation requires a knowledge
of the temperature profile, excess air profile, and waste conversion profile
along the combustion chamber. These factors must be expressed as functions of
combustion chamber length (i.e., volume) in order for the integration to be
performed.
Since this detailed information can rarely, if ever, be determined with a
reasonable degree of accuracy, an alternate approach is normally adopted. In
this approach, the flow rate, q, is specified at the desired operating temper-
ature (measured at the incinerator outlet) and total excess air rate. The
equation is then simplified to:
6 =
The chamber volume used in this calculation is an estimated value, correspond-
ing to the volume through which the combustion gases flow after they have been
heated to the desired operating temperature. Thus, the chamber volume used in
residence time calculations should be at least somewhat less than the total
volume of the chamber. However, an upper bound residence time can be
estimated by:
where V = total volume of the chamber
Any residence times calculated by this equation should only be used for
general comparison purposes.
In the preceding discussion, all equations apply to the nominal, or mean,
residence time in the combustion chamber. A thoroughly rigorous approach
would require tracer studies to determine residence time distributions in the
incinerator. However, nominal residence times are sufficient for evaluation
purposes, so long as the incinerator design is such that significant channel-
ing (analogous to dead space in the combustion chamber) does not occur. Chan-
neling is usually prevented by creating abrupt changes in flow direction or by
establishing a definite flow pattern in the combustion chamber (e.g., cyclonic
flow).
4-30
-------
TABLE 4-5. TEMPERATURE/EXCESS AIR EVALUATION PROCEDURE.
1. Identify the proposed operating temperature.
2. Is this temperature sufficient to convert all waste components to their
ultimate oxidation products, assuming that adequate residence time,
oxygen, and mixing are provided? See the preceding discussion (Section
4.3.3.1) for general guidelines. Outside sources of information can be
consulted for waste-specific data.
3. Identify the excess primary combustion air rate proposed in the permit
application.
4. Does this excess air rate meet or exceed the general requirements identi-
fied in the preceding discussion and/or burner manufacturer
specifications?
5. Identify the total excess air rate proposed.
6. Is this excess air rate acceptable? General guidelines are presented in
Section 4.3.3.1.
7. Independently calculate the total excess air rate needed to maintain the
proposed operating temperature (see Worksheet 4-5).
8. Is this calculated excess air rate greater than or comparable to the
proposed total excess air rate? (If YES, proceed to checkpoint #11. If
NO, proceed to the following checkpoint).
9. Is this excess air rate acceptable, even though it is less than the pro-
posed excess air rate? See the preceding discussion for general guide-
lines. (If YES, proceed to checkpoint #11. If NO, proceed to the
following checkpoint.)
10. Are there any mechanical restraints in the system that would prevent
increasing the auxiliary fuel-to-waste firing ratio (which would be
needed to maintain both an acceptable temperature and excess air rate)?
If necessary, repeat the calculations shown in Worksheet 4-5 for the
maximum achievable fuel-to-waste ratio.
11. Identify the location at which temperature is to be measured in the
incinerator.
12. Is this location (a) suitable based on the considerations in the preced-
ing discussion or (b) comparable to the location at which temperature was
measured during an appropriate prior test?
4-31
-------
Table 4-6 presents a gas residence time evaluation procedure which can be used
in conjunction with the evaluation procedure for temperature and excess air
shown in Table 4-5, since all three variables are interrelated.
TABLE 4-6. GAS RESIDENCE TIME EVALUATION PROCEDURE
1. Identify the proposed gas residence time.
2. Does this residence time appear adequate, considering the proposed operat-
ing temperature and excess air rate, and assuming that good mixing is
achieved? See the preceding discussion for general guidelines and the
appendices for specific information.
3. Does the proposed residence time appear to be achievable? See
Worksheet 4-6.
Temperature, oxygen, and residence time requirements for waste destruction all
depend to some extent on the degree of mixing achieved in the combustion
chamber. This parameter is difficult to express in absolute terms, however.
Many of the problems involved in interpreting burn data relate to the diffi-
culty involved in quantifying the degree of mixing achieved in the incinerator,
as opposed to the degree of mixing achieved in another incinerator of
different design.
In liquid waste incinerators, the degree of mixing is determined by the spe-
cific burner design (i.e., how the primary air and waste/fuel are mixed),
combustion product gas and secondary air flow patterns in the combustion cham-
ber, and turbulence. Turbulence is related to the Reynolds number for the
combustion gases, expressed as:
Dvp
*e = lf
where D = combustion chamber diameter, ft
v = gas velocity, ft/s
p = gas density, lb/ft3
M = gas viscosity, lb/ft s
Turbulent flow conditions exist at Reynold's numbers of approximately 2,300
and greater. Below this Reynold's number laminar or transition flow prevails
and mixing occurs only by diffusion.
In conventional liquid injection incinerators or afterburners, it is possible
to simplify the Reynold's number to consideration of superficial gas velocity
only. Adequate turbulence is usually achieved at superficial gas velocities
of 10 to 15 ft/s. Superficial gas velocities are determined by
4-32
-------
•-S
where q = gas flow rate at operating temperature, ft3/s
A = cross-sectional area of the incinerator chamber, ft2
When primary combustion air is introduced tangentially to the burner (e.g.,
vortex burners), secondary air is introduced tangentially, or burner alignment
is such that cyclonic flow prevails in the incinerator, actual gas velocities
exceed the superficial velocity. Thus, adequate turbulence may be achieved at
superficial velocities less than 10 ft/s in cyclonic flow systems. However.
the tradeoff is difficult to quantify. Turbulence can also be increased by
installing baffles in the secondary combustion zone of the incinerator, which
abruptly change the direction of gas flow. However, this also increases
pressure drop across the system and is not a common practice in liquid injec-
tion incinerator design. Steam jets can also be used to promote turbulence.
Table 4-7 presents a procedure for evaluating the mixing characteristics of
liquid injection incinerators. Since mixing is related to the gas flow rate
through the incinerator, this evaluation procedure can be used in conjunction
with that for temperature and excess air, which affect gas flow independent of
the waste feed rate.
TABLE 4-7. MIXING EVALUATION PROCEDURE
1. Calculate the superficial gas velocity in the incinerator chamber at
operating temperature (see Worksheet 4-7).
2. Does this velocity meet or exceed the general guidelines provided above
(i.e., 10-15 ft/s)?
3. If not, is cyclonic flow or some mechanical means of enhancing turbulence
designed into the system? If YES. somewhat lower superficial velocities
than those listed above may still provide suitable mixing.
4.3.3.2 Rotary Kiln Incinerators--
In rotary kiln/afterburner incineration systems, three excess air rates must
be considered: (1) excess air present in the primary combustion air intro-
duced through liquid waste burners in the kiln or afterburner section,
(2) total excess air fed to the kiln, and (3) the excess air percentage main-
tained in the afterburner.
Normally, 10% to 20% excess air (i.e., 1.1 to 1.2 times the stoichiometric
requirement) must be supplied to liquid waste burners to prevent smoke forma-
tion in the flame zone. When relatively homogeneous wastes are being burned
in high efficiency burners. 5% excess air may be adequate. Too much excess
air through the burner is also undesirable, since this can blow the flame away
4-33
-------
from its retention cone. Burner manufacturer specifications are the best
source of information for case-by-case analysis.
As stated in Section 4.3.3.1, 20% to 25% total excess air is a practical
minimum for liquid injection incinerators to achieve adequate air/waste con-
tact. Higher excess air rates are needed in rotary kilns, however, because
the efficacy of air/solids contact is less than that for air and atomized
liquid droplets. Typical excess air rates range from 140% to 210% or greater,
depending on the desired operating temperature and the heating value of the
waste. When high aqueous wastes are being burned, lower excess air rates may
be needed to maintain adequate temperature. However, less than 100% excess
air in the kiln may not provide adequate air/solids contact.
Since it is usually desirable to maintain the afterburner at a higher tempera-
ture than the kiln, and because only liquid wastes or auxiliary fuel is fired
in the afterburner, the excess air rate in the afterburner is usually less
than that in the kiln. In a typical system operating at 1,500°F in the kiln
and 1,800°F in the afterburner, approximately 160% to 170% excess air would be
maintained in the afterburner compared to ^210% in the kiln. Considering 100%
excess air in the kiln as a practical minimum, approximately 80% excess air or
more should be maintained in the afterburner. This includes air contained in
the kiln exit gases as well as air introduced in the afterburner itself, and
is based on the total stoichiometric oxygen requirement for all wastes and
fuels burned in the system.
In evaluating temperature requirements for a rotary kiln/afterburner system,
seven basic questions should be considered:
(1) Is the temperature in the kiln high enough to volatilize, partially
oxidize, or otherwise convert all organic components of the waste to a
gaseous state?
(2) Is this temperature high enough for the aforementioned processes to occur
within the proposed solids retention time?
(3) Is the afterburner temperature high enough to heat all volatilized wastes
(and combustion intermediates) above their respective ignition tempera-
tures and maintain combustion?
(4) Is the temperature high enough for complete reaction to occur within the
proposed afterburner residence time?
(5) Is the kiln operating temperature within normal limits and/or attainable
under the other proposed operating conditions?
(6) Is the afterburner temperature within normal limits and/or attainable
under the other proposed operating conditions?
(7) At what points in the system are the temperatures to be measured?
The current state-of-the-art in combustion modeling does not allow a purely
theoretical determination of tine and temperature requirements for solid waste
4-34
-------
burnout or combustion in the gas phase. Therefore, the only reasonable alter-
native is an examination of temperature/time combinations used to destroy the
same or similar waste in a similar or identical rotary kiln/afterburner system.
This information is needed to address questions 1 through 4 above. The latter
three questions are addressed in the following paragraphs.
•
Temperatures in rotary kiln incinerators usually range from about 1,400°F to
3,000°F, depending on the types of waste being burned and the location in the
kiln. Common operating temperatures, measured outside of the flame zone, are
1 500°F to 1,600°F. The question of whether or not these or other proposed
temperatures are attainable at the proposed excess air rate can be resolved by
approximate calculations based on a heat balance around the kiln (see Sec-
tion 4.3.3.1 for a discussion of how heat balances are formulated).
The difficulty that arises in this calculation is that the extent of combus-
tion, or actual heat release compared to the maximum attainable heat release,
is unknown. However, the maximum achievable excess air rate in the kiln at
the specified operating temperature can still be estimated by assuming com-
plete combustion. This corresponds to a worst case analysis. The maximum
calculated excess air rate must exceed the proposed excess air rate, or the
specified operating temperature will not be attainable.
The applicable heat balance equation for the kiln, assuming complete
combustion is shown on the following page.
This equation is also based on the assumptions that (a) heat loss through the
kiln walls is about 5% of the heat released on combustion, and (b) waste
preheating, if employed, will result in negligible heat input compared to the
heat released on combustion (which is almost always the case). This equation
can be solved directly for EA, the maximum attainable excess air rate in the
kiln once the desired operating temperature is specified. Mean heat capaci-
ties 'for common combustion gas components, applicable over temperature ranges
normally encontered, are shown in Section 4.3.3.1.
Worksheet 4-8 in Section 4-5 presents a step-by-step calculation procedure.
4-31
air
ir (77-Ta.r)(02)stoich(k)(l+EAk)
/n1NHV1 + n2NHV2
- 0.95 I-
4.31 C
combustion
products
from kiln
-------
where C~7 = mean heat capacity of ith component over the temperature
pl range involved, Btu/lb °F
T . = air preheat temperature, °F
(02) • u = total stoichiometric oxygen requirement for wastes and
stoich auxiliary fuel fed to the kiln, Ib 02/lb feed
EA. = percent excess air/100(in kiln)
nj = Ib liquid waste/lb waste
n2 = Ib solid waste/lb waste
n^. = Ib fuel/lb waste
NHVi = net heating value of liquid waste, Btu/lb
NHV2 = net heating value of solid waste, Btu/lb
HV — = net heating value of fuel, Btu/lb
n. = Ib ith combustion product/lb feed
T ^ - desired temperature at the kiln outlet, °F
out
When no combustion air preheating is employed, this equation simplifies to:
^n1NHV1 + n2NHV2 + nfRHVfK \
-0.95 I-
E »i Si *4-31 CP
combustion
products
. from kiln
('out
Using the heat capacities presented in Section 4.3.3.1, and assuming that C02,
H20, N2, and 02 are the only significant components of the combustion gas, the
equation further simplifies to :
(n1NHV1 + n2NHV2 + n^-HV-^ \ _
nrs «-Ssi+r0.26 . + ^ *°-49nH2o
fK ' L
(Tout * 77>
aThe term n^ in this equation relates to the nitrogen present in the combustion
gas under stoichiometric conditions. It does not include excess air nitrogen.
4-36
-------
Excess air in the afterburner can be estimated in similar fashion, after the
desired operating temperature is specified. In this calculation, heat inputs
to and from the entire system (kiln and afterburner) are considered. The
resulting heat balance equation is shown below.
This equation is also based on assumptions of 5% heat loss from the system and
negligible energy input due to waste/auxiliary fuel or air preheating. Work-
sheet 4-9 presents a step-by-step calculation procedure.
-0.95
n2NHV2
NHV3
1 + n
+ n.
AK
niK cpi
Pi
combustion
products
from kiln
combustion
products
afterburner
feed
1 * "
»K
out
- 77)
+ 4.31 C
'p air
[<°2>stoich(K) + (°2>stoich(A)]
EA
-------
When quantifying the desired temperatures in the kiln and afterburner, it is
also important to fix the locations at which these temperatures should be
measured. Temperature varies tremendously from one point to another in each
unit, being highest in the flame and lowest at the refractory wall or at a
point of significant air infiltration (e.g., in the vicinity of secondary air
ports, end plate seals, and feed chute). Ideally, temperatures should be
measured in the bulk gas flow at a point after which the gas has traversed the
volume of each chamber that provides its specified residence time. Tempera-
tures should not be measured at a point of flame impingement or at a point
directly in sight of radiation from the flame. Temperature measurement is
discussed in more detail in Chapter 5.
An evaluation procedure for temperature/excess air considerations is shown in
Table 4-8.
In rotary kiln incineration systems, both the solids retention time in the
kiln and the gas residence time in the afterburner must be considered. After-
burner residence time considerations are essentially the same as those for
liquid injection incinerators, a topic which is addressed in Section 4.3.3.1.
Therefore, the following discussion focuses primarily on solids retention time
estimates. For a discussion of gas residence time estimates and corresponding
evaluation procedures, see Section 4.3.3.1.
Solids retention times in rotary kilns are a function of the length-to-diam-
eter ratio of the kiln, the slope of the kiln, and its rotational velocity.
The functional relationship between these variables is [5]:
6 = 0.19 (L/D)/SN
where 6 = retention time, min
L = kiln length, ft
D = kiln diameter, ft
S = kiln slope, ft/ft
N = rotational velocity, rpm
This equation can be used for a rough approximation of the retention time.
Typical ranges for the parameters are L/D = 2-10, 0.03-0.09 ft/ft slope, and
1-5 ft/min rotational speed measured at the kiln periphery (which can be
converted to rpm by dividing by the kiln circumference measured in ft). Some
examples of retention time requirements are 0.5 s for fine propellants, 5 min
for wooden boxes, 15 min for refuse, and 60 min for railroad ties [5]. How-
ever, the retention time requirements for burnout of any particular solid
waste should be determined experimentally or extrapolated from operating
experience with similar wastes.
Table 4-9 presents an evaluation procedure for kiln retention time.
In rotary kiln incineration systems, both the degree of air/solids contact in
the kiln and gas mixing in the afterburner must be considered. Afterburner
mixing considerations are essentially the same as for liquid injection incin-
erators, a topic which is addressed in Section 4.3.3.1. See Table 4-7 for the
afterburner mixing evaluation procedure.
4-38
-------
TABLE 4-8. TEMPERATURE/EXCESS AIR EVALUATION PROCEDURE FOR
ROTARY KILN/AFTERBURNER INCINERATORS
1. Identify the proposed kiln and afterburner operating temperatures.
2. Is the kiln temperature sufficient for complete solid waste burnout,
assuming that adequate retention time, excess air, and mixing are pro-
vided? This determination must be based on operating experience and/or
other burn data.
3 Is the afterburner temperature sufficient to complete the combustion
reactions, assuming that adequate residence time, excess air, and mixing
are provided? See the preceding discussion (Section 4.3.3.2) for general
guidelines.
4. Identify the excess primary air rates for each liquid waste burner in the
kiln or afterburner.
5. Does this excess air rate meet or exceed the general requirements
identified in the preceding discussion and/or burner manufacturer
specifications?
6. Identify the total excess air rate for the kiln.
7. Is this excess air rate acceptable? See the preceding discussion
guidelines.
8 Independently calculate the maximum total excess air rate needed to
maintain the proposed operating temperature in the kiln (see Worksheet 4-8)
9 Is this calculated excess air rate greater than the proposed total excess
air rate?(If YES, proceed to checkpoint #12. If NO, proceed to the
following checkpoint.)
10 Is this excess air rate acceptable, even though it is less than or compa-
rable to the proposed excess air rate? See the preceding discussion for
general guidelines. (If YES, proceed to checkpoint #12. If NO, proceed
to the following checkpoint.)
11 Are there any mechanical restraints in the system that would prevent
increasing the auxiliary fuel-to-waste firing ratio in the kiln (which
would be needed to maintain both an acceptable temperature and excess air
rate). In other words, is the maximum achievable fuel-to-waste firing
ratio insufficient to maintain an acceptable excess air rate? Repeat the
calculations shown in Worksheet 4-8 at this fuel-to-waste ratio, if
necessary.
12. Identify the total excess air rate for the system (i.e., in afterburner).
(continued)
4-39
-------
TABLE 4-8 (continued)
13. Is this excess air rate acceptable? See the preceding discussion for
general guidelines.
14 independently calculate the total excess air rate needed to maintain the
proposed operating temperature in the afterburner (see Worksheet 4-9).
Is the calculated excess air rate greater than or comparable to the
proposed total excess air rate? (If YES, proceed to checkpoint #17. If
NO, proceed to the following checkpoint.)
15 fa this excess air rate acceptable, even though it is less than the pro-
posed excess air rate? See the preceding discussion for general guide-
lines. (If YES, proceed to checkpoint #17. If NO. proceed to the
following checkpoint.)
16 Are there any mechanical restraints in the system that would prevent
increasing the auxiliary fuel-to-waste firing ratio in the afterburner
(which would be needed to maintain both an acceptable temperature and
excess air rate)? If necessary repeat the calculations shown in
Worksheet 4-9 at the maximum achievable fuel-to-waste ratio.
17. Identify the locations at which temperature is to be measured in the kiln
and afterburner.
18 Are these locations (a) suitable based on the general guidelines given in
the preceding discussion, or (b) comparable to the location at which
temperature was measured during a prior similar burn?
TABLE 4-9. KILN RETENTION TIME EVALUATION PROCEDURE
1. Identify the estimated solids retention time in the kiln.
2. Is this retention time acceptable, based on past experience and/or prior
burn data?
3. Independently estimate solids retention time in the kiln (see
Worksheet 4-10).
4. Does the proposed retention time appear to be achievable?
Air/solids mixing in the kiln is primarily a function of the kiln's rotational
velocity, assuming a relatively constant gas flow rate. As rotational veloc-
ity is increased, the solids are carried up higher along the kiln wall and
4-40
-------
showered down through the air/combustion gas mixture. Typical rotational
velocities are in the range of 1-5 ft/min, measured at the kiln periphery.
Since solids retention time is also affected by rotational velocity, there is
a tradeoff between retention time and air/solids mixing. Mixing is unproved
to a point by increased rotational velocity, but the solids retention time is
reduced Mixing is also improved by increasing the excess air rate, but this
reduces the kiln operating temperature. Thus, there is a distinct interplay
between all four operating variables.
4.3.4 Auxiliary Fuel Capacity Evaluation
4.3.4.1 Liquid Injection Incinerators—
As discussed in Section 4.3.1. liquid injection incinerators should be
equipped with an auxiliary fuel firing system to heat the unit to operating
temperature before waste is introduced. Although not essential from an engi-
neering standpoint, it is desirable for the auxiliary fuel system to have
sufficient capacity to attain this temperature at the design air flow rate for
waste combustion. This capacity requirement can be approximated by the
following heat balance equation :
0.95 mf NHVf = mf ^ nif C~ (TQut - 77)
4.31 mw (02)stoich(w) (1 + EA) ( air (TQut
(T (T - 77)
- 4.31 mf (02)stoich(f) r a.r (TQut - 77)
where mf = required auxiliary capacity. Ib/hr
NHV = net heating value of auxiliary fuel, Btu/lb
N.f = Ib combustion ith product Ib fuel
C~~ = heat capacity of ith component, Btu/lb °F
pi
T = proposed operating temperature, measured at the
out incinerator outlet, °F
4 31 (09) . ,_, v » stoichiometric air requirement for waste combustion,
2;stoich(w) ^ a±r/lb waste
m = proposed waste feed rate (average), Ib/hr
aSee Section 4.3.3.1 for a discussion of how heat balances are formulated.
4-41
-------
EA = proposed excess air rate, %/100
4.31(02) . . ,-. = stoichiometric air requirement for fuel combustion,
stoicn(f) ^ air/lb fuel
This equation is based on these assumptions: (a) air is not preheated,
(b) there is a 5% heat loss through the refractory walls, and (c) the air flow
rate for normal waste burning operation exceeds the air requirements for fuel
combustion during startup.
Since C02, H20, and N2 are the only major components of fuel combustion gases
at stoichiometric firing conditions, this equation can be further simplified
using the heat capacities presented in Section 4.3.3.1 The simplified form
is:
0.95 m-NHV- = m, fo.26 (n__ + n.. + 0.49 n^ 1 (TMlf. - 77)
r t i I co2 N2 n2u j
+ 1.12 mw (02)stoich(w) (1 + EA) (Tout - 77)
- !•« mf <°2>stoich(f) (Tout - 77)
where n ' "M • "H o' are based on tne stoicniometric air/fuel ratio.
Worksheet 4-11 presents a step-by-step procedure to solve this equation for
n.f, the required auxiliary fuel capacity. This value can then be compared to
tne auxiliary fuel rating of the incinerator.
If this rating is reported in Btu/hr rather than Ib/hr, the capacity require-
ment calculated in Worksheet 4-11 can be converted to equivalent units by:
Qf = mf NHVf
where Qf = required auxiliary fuel capacity, Btu/hr
4.3.4.2 Rotary Kiln Incinerators--
In rotary kiln incinerators, both the kiln and afterburner need to be heated
to operating temperature before waste is introduced. Since the afterburner-
temperature is usually higher than the kiln temperature and more critical in
terms of emissions, it should be sufficient to limit the auxiliary fuel capac-
ity evaluation; to the afterburner section. The evaluation procedure described
for liquid injection incinerators can be modified for this purpose in the
following manner:
• The proposed average waste feed rate (mw) and stoichiometric air require-
ment for waste combustion should be based on the combined kiln and after-
burner waste feed.
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• Temperature (T ) should be specified at the afterburner outlet.
• The excess air rate (EA) used in the calculation should be the proposed
excess air level for the afterburner section.
With these modifications. Worksheet 4-11 can be used to estimate the auxiliary
fuel startup requirements for rotary kiln incinerators as well as liquid
injection units.
4.3.5 combustion Process Control and Safety Shutdown System Evaluation
All incinerators should be equipped with combustion process control systems to
maintain the desired conditions of temperature and excess air. Incinerators
burning hazardous wastes should also be equipped with automatic shutdown
systems in order to prevent the release of hazardous materials to the environ-
ment in the event of flameout, other combustion process upsets, or air pollu-
tion control device failure. The following subsections discuss combustion
process control and automatic shutdown procedures related to upsets in liquid
injection and rotary kiln incinerators. Process control procedures for air
pollution control devices are discussed in Section 4.4.5.
4.3.5.1 Liquid Injection Incinerators--
In most liquid injection incinerator designs, the desired temperature at the
chamber outlet is preset by the operator, and secondary air is fed to the
system at a constant rate. Fluctuations in temperature are controlled by
increasing or reducing the waste or auxiliary fuel feed rate to the burner
within the design turndown ratio. This turndown ratio is fixed, in part, by
the limited range of liquid waste injection velocities required to prevent
flame liftoff or flashback. If waste is injected through the burner nozzle at
too high a velocity, the flame will separate from the burner and be extin-
guished. If the injection velocity is too low, the waste will burn in the
nozzle and damage it. The range of injection velocities needed to prevent
these occurrences is determined by the flame propagation rate for the wastes
and the flame retention characteristics of the burner.
Since the burner turndown ratio is also limited by the atomization technique
employed (see Section 4.3.1) and the need to maintain air/fuel stoichiometry
in the burner on turndown, the burner must be equipped with a primary air feed
control system. There are a number of ways to control burner stoichiometry,
depending on whether aspirator burners or forced-draft burners are used and on
manufacturer preference.3 For evaluation purposes, a package burner/primary
air control system provided by the same manufacturer can be considered
sufficient.
aln aspirator burners, primary air is supplied by an induced-draft fan down-
stream from the incinerator. In forced-draft burners, primary air is sup-
plied by a separate blower, although an induced-draft fan may still be
employed to pull the combustion gases through the air pollution control system.
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Problems with the automatic temperature control system described above occur
on loss of ignition, or flameout. When flameout occurs, the temperature in
the incinerator drops and more waste is automatically fed to the burner.
Without a heat source for ignition, this waste passes through the incinerator
partially or completely unreacted. Thus, temperature continues to drop, more
waste is automatically injected, and the problem of incomplete combustion is
magnified.
To prevent this phenomenon from occurring, burners are usually equipped with
flame scanners. These devices sense ultraviolet radiation from the flame.
When used in conjunction with an automatic waste feed cutoff, flame scanners
immediately terminate the feed to the burner on loss of ignition.
Flame scanners are usually designed to sense ultraviolet radiation from gas or
fuel oil flames. These flames tend to be more stable than the flames from
burning wastes which are usually much more heterogeneous than fuels. For
example, organic wastes containing a significant amount of moisture burn with
a sputtering flame, particularly when a slug of water passes through the
burner. Although combustion may continue despite such occurrences, flame
scanners often sense loss of ignition. This leads to unnecessary waste feed
cutoff.
To prevent unnecessary shutdown, flame scanners can be used in conjunction
with temperature sensors at the outlet of the incinerator. With this sys-
tem, feed is only cut off by a combination of flameout, as sensed by the flame
scanner, and low temperature at the combustion chamber. This considerably
reduces operator problems when relatively heterogeneous wastes are being
burned. If the low temperature cutoff is preset to the minimum temperature
needed for waste destruction, release of hazardous substances to the environ-
ment is also prevented.
The other automatic shutdown parameter related to the combustion process is
high temperature at the incinerator outlet. This can signal loss of secondary
combustion air or other control system malfunctions. The high temperature
cutoff point should be well above the tolerance level associated with normal
operating temperature fluctuations to prevent shutdown in the event of routine
variations, and should be low enough to prevent damage to downstream air
pollution control equipment.
Table 4-10 lists three checkpoints for liquid injection incinerator combustion
process control evaluation.
4.3.5.2 Rotary Kiln Incinerators—
In rotary kiln incinerators, temperature is controlled within a specified
range by automatically varying the liquid waste or auxiliary fuel firing rate
within the design turndown ratio and/or manually or automatically controlling
the solid waste feed. Regardless of which technique is employed, provisions
should be included for the following:
• Termination of liquid waste feed on loss of ignition in the burner. If
more than one liquid waste burner is employed, feed only needs to be
terminated in the burner where flameout occurs. See Section 4.3.5.1 for
a discussion of flame supervision systems.
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Termination of solid waste feed to the kiln when low temperatures are
sensed at the kiln outlet. If the feed to the kiln is automatic or
semiautomatic, then the low temperature cutoff system should also be
automatic. If manual feeding is employed, an alarm system is needed to
warn the operator. The low temperature cutoff point should be such that
solid waste burnout can be maintained, but at lower than the normal
operating temperature to avoid shutdown due to routine temperature
fluctuations. Engineering judgment must be used to determine an
acceptable minimum temperature.
Termination of solid waste feed on loss of negative pressure at the kiln
outlet.
TABLE 4-10. COMBUSTION PROCESS CONTROL EVALUATION PROCEDURE
Is each burner equipped with an automatic flame supervision system, as
discussed in the preceding subsection, (Section 4.3.5.1)?
Is the system equipped with an automatic high temperature/low temperature
control system, employing variable flow of either waste or auxiliary
fuel?
Is each burner equipped with an air supply control system so that air:
fuel stoichiometry is maintained on turndown?
Afterburner burner temperature can be controlled by varying the liquid or
auxiliary fuel feed or by varying the secondary air flow rate. Regardless of
which technique is employed, provisions should be included for the following:
• Termination of liquid waste or auxiliary fuel feed on loss of ignition
(see Section 4.3.5.1 for a discussion of flame supervision). This cutoff
is necessary to prevent the release of unburned waste contaminants (if
liquid waste is being burned) and to prevent potential explosion on
release of unburned fuel. However, it also eliminates the function of
the afterburner. Therefore, solid waste feed to the kiln should also be
terminated on loss of ignition in the afterburner. To minimize the
occurrence of flameout in the afterburner, only "clean," homogeneous
liquid wastes (or fuel) should be burned.
• Termination of solid waste feed to the kiln if low temperatures are
sensed at the afterburner outlet. The afterburner feed should be main-
tained, however, to minimize potential release of unburned contaminants.
As previously stated, the low temperature cutoff point should be such
that combustion is maintained, but at lower than normal operating
temperatures to avoid shutdown due to routine fluctuations.
• Termination of solid waste feed to the kiln if high temperatures are
sensed at the afterburner outlet. This is necessary to prevent damage to
4-45
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the refractory lining and to downstream air pollution control devices.
The high temperature cutoff point should be well above normal operating
temperatures, but low enough to avoid damage to the system. In the event
of this cutoff, some liquid waste or fuel feed to the afterburner should
be maintained to complete combustion of off-gases from solid wastes
remaining in the kiln.
In addition to these criteria, all liquid waste burners in the kiln and after-
burner should be equipped with manufacturer specified primary air control
systems so that air/fuel stoichiometry is maintained on turndown.
Table 4-11 presents a five-point checklist for rotary kiln incinerator combus-
tion process control evaluation.
TABLE 4-11. COMBUSTION PROCESS CONTROL EVALUATION PROCEDURE
1. Is each burner in the kiln and afterburner equipped with an automatic
flame supervision system for waste feed shutdown?
2. Is the afterburner equipped with an automatic high temperature/low tem-
perature control system employing variable flow of waste, auxiliary fuel,
or secondary combustion air?
3. Is the kiln equipped with an automatic temperature control system
employing variable feed of either waste or auxiliary fuel?
4. Is the kiln equipped with a pressure monitoring system which alerts the
operator or automatically terminates waste feed if negative pressure is
lost?
5. Is each burner equipped with an air supply control system so that
air:fuel stoichiometry is maintained on turndown?
4.3.6 Construction Material Evaluation
Since hazardous waste incinerators usually operate at temperatures of 1,800°F
or higher (sometimes hundreds of degrees higher for halogenated wastes),
refractory linings are virtually always employed to prevent damage to the
structural steel shell and to reduce heat loss. Aluminosilicate refractories
backed up by insulating brick are most commonly used, although refractories
made predominantly of silica or specialty refractories may be used in certain
applications. Table 4-12 lists various types of aluminosilicate and silica
refractories3 along with their approximate chemical compositions, fusion
aSee references listed in Table 4-12 for information on specialty refractions.
4-46
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temperatures, and resistances to degradation by different chemical species
that may be encountered in incinerator combustion gases.
Table 4-12, along with the operating temperature range and the chemical compo-
sition of the waste, can be used to evaluate the suitability of a refractory
for a given application.
In addition to refractory composition, the physical form of the material
should also be considered in evaluating liquid injection vs. rotary kiln
incinerator designs. Suspended refractory brick is normally used in station-
ary liquid injection units and afterburners. In kilns, however, castable
refractories are normally used to better withstand the physical abrasion and
vibration imparted by rotation and contact with solid wastes. Castable
refractories are made of the same clays as those used in aluminosilicate
firebrick, but bonding agents are added to impart strength until the
temperature in the incinerator during initial startup is raised sufficiently
high to "cure" the material and develop ceramic bonds. Castable refractories
are easily installed in much the same manner as cement; thus, they are also
used for quick repairs and spot patching.
4.4 AIR POLLUTION CONTROL AND GAS HANDLING SYSTEM DESIGN EVALUATION
Figure 4-11 presents a logic diagram for air pollution control and gas han-
dling system design evaluation. It consists of six separate evaluation
procedures intended to answer the following questions:
(1) Are the generic air pollution control device designs appropriate for
removal of the pollutants present in the combustion gases?
(2) Are the air pollution control device designs and operating criteria
consistent with current industry practice and capable of achieving the
necessary pollutant removal efficiencies?
(3) Have combustion gas quenching and mist elimination been properly con-
sidered in the system design?
(4) Does the prime mover have sufficient capacity to handle the combustion
gas flow and overcome pressure drops across the air pollution control
system?
(5) Are appropriate process control and safety shutdown interlocks
incorporated?
(6) Are appropriate materials of construction employed?
These topics are addressed in Sections 4.4.1 through 4.4.6
4.4.1 Emission/Air Pollution Control Device Matching Criteria
When incinerating hazardous wastes, air pollutants may arise from two sources:
incomplete combustion of organic waste constituents and conversion of certain
inorganic constituents present in the waste and/or combustion air to ultimate
4-47
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TABLE 4-12. GENERAL CHARACTERISTICS OF SILICA AND ALUMINO-
SILICATE REFRACTORY BRICK [6, 7, 8, 9, 10]
Type
Silica
High- duty
fireclay
Super- duty
fireclay
Typical
composition
95% Si02
54% Si02,
40% A1203
52% Si02,
42% A1203
Fusion
temperature . °F
3,100
3,125
3,170
Resistant
to
HC1, NH3, acid
slags
Most acids,
slag condi-
tions
HC1, NH3, S02,
most acids
Degraded
by
Basic slags,
Al, Na, Hg,
F2, Cl2 , H2,
(>2,550°F)
High- lime
slags, other
bases at high
temperature
Basic slags,
Na, Mg, F2,
«-n u
Acid-resistant 59% Si02
(type H)
3,040
High-Alumina
Extra-High-
Alumina
Mullite
50-85%
A1203
90-99%
A1203
71% A1203
3,200-3,400
3,000-3,650
3,290
Excellent for
most acids,-
bases in mod-
erate concen-
tration
HC1, NH3/ S02
HC1, HF, NH3,
S02, S2, HN03,
H2S04, C12
HC1, S02, NH3
(>2,550°F)
HF, H3P04
Basic slags,
Na, Mg, F2,
C12. H2
(>2,550°F)
Na, F2
(>1,800°F)
Na, F2, C12,
H2 (>2,550°F)
aA safety factor of at least several hundred degrees between refractory fusion
temperature and incinerator operating temperature is advisable.
4-48
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EMISSION SPECIES/AIR POLLUTION
CONTROL DEVICE MATCHING CONSIDERATIONS
SECTION 4.4.1
I
AIR POLLUTION CONTROL DEVICE DESIGN
AND OPERATING CRITERIA EVALUATION
SECTION 4.4.2
I
QUENCHING AND MIST ELIMINATION
EVALUATION
SECTION 4.4.3
PRIME MOVER CAPACITY EVALUATION
SECTION 4.4.4
i
PROCESS CONTROL AND AUTOMATIC
SHUTDOWN SYSTEM EVALUATION
SECTION 4.4.5
i
MATERIAL OF CONSTRUCTION
CONSIDERATIONS
SECTION 4.4.6
Figure 4-11.
Logic diagram for air pollution control and
gas handling system design.
4-49
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oxidation products. The products of incomplete combustion include carbon
monoxide, carbon; hydrocarbons, aldehydes, amines, organic acids, polycyclic
organic matter (POM), and any other waste constituents or their partially
degraded products that escape thermal destruction in the incinerator. In well
designed and operated incinerators, however, these incomplete combustion
products are only emitted in insignificant amounts. The primary end products
of combustion are, in most cases, carbon dioxide (C02) and water vapor (H20).
When wastes containing elements other than carbon, hydrogen, and oxygen are
burned, however, ultimate combustion products other than C02 and water vapor
are formed. These include:
• Hydrogen chloride (HCl) and small amounts of chlorine (C12) from the
incineration of chlorinated hydrocarbons,
• Hydrogen fluoride (HF) from the incineration of organic fluorides,
• Bromine (Br2) and lesser quantities of hydrogen bromide (HBr) when
organic bromides are burned,
• Iodine (I2) from organic iodide compound incineration,
• Sulfur oxides, mostly as sulfur dioxide (S02), but also including 1% to
5% sulfur trioxide (S03), formed from sulfur present in the waste
material and auxiliary fuel,
• Phosphorus pentoxide (P205), formed from the incineration of
organophosphorus compounds,
• Nitrogen oxides (NO ) from thermal fixation of nitrogen in the combustion
air or from organicxnitrogen compounds present in the waste, and
• Particulates, including metal salts from the waste, metal oxides formed by
combustion, and fragments of incompletely burned material (primarily
carbon).
Gaseous pollutant concentrations in the combustion gases leaving an incinera-
tor can be estimated by the methods described in Section 4.3.2 . Step-by-step
procedures for calculating these concentrations are presented in
Worksheets 4-2 and 4-4. Particulate emissions from liquid injection
incinerators can also be estimated from the ash content of the waste, the
combustion gas flow rate corrected to standard conditions of temperature and
pressure (see Worksheet 4-2), and the oxygen content of the combustion gas.
Oxygen concentration is important because particulate loadings are often
expressed as gr/scf (mg/m3) corrected to zero percent excess air. A procedure
to estimate particulate concentrations in combustion gases from liquid
injection incinerators is presented in Worksheet 4-12. Particulate emissions
from rotary kilns are more difficult to estimate because sizable fractions of
incombustible material are removed as bottom ash, and the fly ash:bottom ash
aThese procedures are not applicable for products of incomplete combustion.
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ratio is usually unknown prior to actual testing. In general, particulate
emissions from rotary kilns burning solid wastes are greater than particulate
emissions from liquid injection incinerators. This is due to the fact that
solid wastes frequently have a higher ash content than liquid wastes.
As indicated in Section 4.1, venturi scrubbers, packed bed scrubbers, and
plate tower scrubbers are used for air pollution control at the majority of
hazardous waste incineration facilities. In selecting from among these ge-
neric scrubber designs, the factors most frequently considered are the need
for particulate emission control, particulate loading in the combustion gas
(assuming that control is required to meet emission standards), the types of
gaseous pollutants to be removed, and the desired removal efficiencies.
Particulate loading governs the choice between venturi and packed bed or plate
tower scrubbers for a given application, and the characteristics of the gas-
eous emission species govern the choice of scrubber medium (e.g., water vs.
caustic solution, lime solution, etc.) as well as generic scrubber design.
These factors are discussed in the following subsections.
4.4.1.1 Particulate Removal—
Particulate removal is required when the ash content of the waste is such that
emissions will exceed applicable state, local, or Federal standards. Particu-
late removal is nearly always required at rotary kiln incineration facilities,
and may or may not be required for liquid injection incinerators depending on
the ash content of the waste. (See Worksheet 4-12 for a method to estimate
particulate emissions from liquid incinerators). Venturi, packed bed, and
plate tower scrubbers can all be used to control particulate emissions from
hazardous waste incinerators, depending on the particulate loading in the gas.
Packed bed or plate tower scrubbers are commonly used at liquid injection
incinerator facilities where particulate control is considered secondary to
gaseous emission control. These devices are superior to venturi scrubbers for
removal of gaseous pollutants and they operate at lower pressure drops; thus
they are more economical to operate. Both the plate tower and the packed bed
scrubber have some capacity for particle collection, and they are considered
applicable for streams containing low particulate loadings with particles
generally >5 pm in diameter [11]. Cut diameters as low as 1 |Jm can be at-
tained with plate scrubbers or packed bed scrubbers employing 1-inch berl
saddles or Raschig rings [12]. However, packed bed and plate tower scrubbers
are not primarily designed for particulate control. Both devices, particular-
ly packed bed scrubbers, are susceptible to pluggage by solids. Therefore,
they are seldom, if ever, used as the primary particulate collection devices
at rotary kiln incineration facilities or liquid injecton incineration facili-
ties where high ash content wastes are burned. Venturi scrubbers are the most
popular devices for these applications.
High energy venturi scrubbers are capable of 99% removal of particulate in the
1- to 2-kim size range and above, 90-99% removal of particulate in the 0.5 - to
1-um size range, and 50% removal of particulate in the 0.3- to 0.5-pm size
range [13]. By comparison, particulates emitted from liquid and solid waste
incinerators have mean diameters in the 0.5- to 3-pm and 5- to lOO-pm ranges,
respectively. Therefore, venturi scrubbers are capable of efficient particu-
late removal for most hazardous waste incineration applications.
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Table 4-13 presents a checklist procedure that can be used to compare par-
ticulate removal requirements with proposed control strategies.
TABLE 4-13. PROCEDURE TO COMPARE PARTICULATE REMOVAL
REQUIREMENTS WITH PROPOSED CONTROL STRATEGIES
1. If a rotary kiln incinerator facility is being evaluated, is a venturi
scrubber provided for particulate control?
2. If a liquid injection incinerator facility is being evaluated, does the
estimated particulate emission rate exceed applicable standards? See
Worksheet 4-12 for a procedure to estimate particulate emissions.
3. If particulate emissions do exceed standards, is a venturi scrubber
provided for particulate removal (upstream from other gaseous emission
control devices)?
4. If not, are packed bed or plate tower scrubbers to be used for
simultaneous particulate and gaseous pollutant removal?
5. If so, can the selected control device function properly in its dual
role? (Technical assistance may be needed to make this determination).
4.4.1.2 Gaseous Pollutant Removal—
Gaseous pollutants generated by hazardous waste incineration include HC1, C12,
SO , Br2vk HBr, HF, P20S and NO , of which NO and HCl are most commonly encoun-
tered.3' 'C These compounds are usually removed from the combustion gases by
packed bed or plate tower scrubbers, although venturi scrubbers are used in
some applications for simultaneous particulate and gaseous pollutant removal.
For highly soluble gases such as HCl and HF, water can be used in packed bed
or plate tower scrubbers to control emissions. When water is used as the
scrubbing liquor, an acidic blowdown stream is produced that must be neutral-
ized prior to discharge. HCl concentration in the scrubbing liquor is normal-
ly limited to 1-2% by adjusting the makeup water and blowdown rates. The
aNO emissions are not economically amenable to control by scrubbing or other
post-generation removal techniques. NO emissions can be minimized by con-
trolled temperature combustion, but this is seldom possible in hazardous
waste incineration due to the requirements for efficient, high temperature
waste destruction.
b!2 and HI emissions may be an occasional problem as well.
CC12 is present in conjuncton with HCl, but equilibrium favors HCl formation
at the high temperatures employed in chlorinated waste incinerators. C12 and
the other free halogens are not readily removed by scrubbing.
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scrubber must also be lined with an acid-resistant material, as discussed in
Section 4.4.6.
Caustic solution (typically 18-20 wt % caustic soda in water) is also commonly
used in packed bed and plate tower scrubbers to control HC1 and HF emissions.
Because these compounds react with caustic, the driving force for mass trans-
fer is increased and more efficient removal is achieved at the same liquid-to-
gas ratio and packing depth (or number of trays). Neutralization is also
achieved "in situ" if sufficient caustic is supplied for complete conversion
of HC1 to NaCl. Unlike water scrubbing, caustic scrubbing can also achieve
high removal efficiencies for S02, P205, and HBr, which are less soluble in
water than HC1 or HF. When gases such as S02 are being scrubbed, the caustic
addition rate is adjusted to maintain an alkaline scrubbing media. Alter-
natively, the caustic addition rate can be adjusted to sub-stoichiometric
levels. This reduces the scrubber water makeup and blowdown rates needed to
maintain a specified acid concentration in the scrubber liquor.
Lime slurry, typically 10-32 wt % Ca(OH)2 in water, can also be used to con-
trol emissions of HCl, HF, S02, and P205. However, line slurries are not
often used as the scrubbing liquid in packed bed designs because of plugging
problems. Also, the use of lime slurries can lead to plugging of the spray
nozzles and cause scale formation on the surfaces of the scrubber equipment,
particularly scrubber internals and mist eliminator surfaces. The magnitude
of the scaling problem will depend on the levels of HCl, HF, P20S, and S0x in
the incinerator exhaust gases. Lime solutions are used in plate tower scrub-
bers, however, because lime is less expensive than caustic. At several haz-
ardous waste incineration facilities, venturi scrubbers with lime slurry
injection are used to control emissions of HCl, HF, and P205.
When organic bromine and iodine wastes are incinerated, the exhaust gases from
the incinerator will contain bromine and iodine both as hydrogen halides and
as free halogens. Hydrogen bromide can be readily removed by scrubbing with
caustic soda. The technology for controlling emissions of bromine, hydrogen
iodide, and iodine, however, is not well developed. Some of the methods that
could be considered to control bromine emissions include: (1) absorption in
ammonia solution with the formation of ammonia bromide; (2) absorption in
caustic soda or soda ash solution in which bromine reacts to form sodium
bromate, sodium bromide, and either water or carbon dioxide; and (3) absorp-
tion in lime slurry in which bromine reacts to form calcium bromide and cal-
cium bromate. It is also conceivable that bromine can be reduced by the
sulfur dioxide present in the flue gas, giving rise to the formation of a
spray of fine droplets of hydrobromic and sulfuric acids, which could
subsequently be removed by absorption in caustic solutions or lime slurries.
When combustion gases contain a high particulate loading as well as one or
more of the gaseous pollutants discussed above, venturi scrubbers are often
used in conjunction with packed bed or plate tower scrubbers. Venturi scrub-
bers remove the particulate from the stream to prevent fouling of the packed
bed or plate tower absorber, and may also remove a significant fraction of
gases highly soluble in water. However, venturi scrubbers alone are not
considered suitable for removal of low solubility gases; when water is used as
the scrubbing medium, estimated efficiencies are less than 50-75% [11]-
4-53
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Venturi scrubbers using water are not suitable for highly efficient (>99%)
removal of HCl or HF either.
Table 4-14 presents a checklist procedure that can be used to compare gaseous
pollutant removal requirements with proposed control strategies. The
following rules of thumb are generally applicable:
• Water, caustic, or lime in packed bed or plate tower scrubbers for
removal of HCl and/or HF,
• Caustic or lime in packed bed or plate tower scrubbers for removal of
other acid gases discussed above, and
• Specialized scrubbing techniques for HBr, Br2, HI, and I2- Technical
assistance is advised in evaluating these systems.
TABLE 4-14. PROCEDURE TO COMPARE GASEOUS POLLUTANT REMOVAL
REQUIREMENTS WITH PROPOSED CONTROL STRATEGIES
1. From Worksheet 4-2 or 4-4, identify the gaseous pollutants present in the
combustion gases in excess of desired emission levels.
2. Is removal of Br2, HBr, I2, or HI required? If YES, technical assistance
may be required.
3. Is removal of SO or P205 required? If YES, proceed to checkpoint #4.
If NO, proceed to checkpoint #5.
4. Is caustic or lime slurry scrubbing to be used for SO /P20s removal, as
described in the preceding pages? (Water scrubbing alone is usually not
sufficient to remove these compounds).
5. Is removal of HCl or HF required?
6. Is alkali or aqueous scrubbing in a packed bed or plate tower scrubber,
or alkali scrubbing in a venturi scrubber, to be used for HC1/HF removal?
7. If not, are other methods for HCl/HF removal provided?
8. If so, are these methods acceptable? (Technical assistance may be needed
to make this determination).
4.4.2 Air Pollution Control Device Design and Operating Criteria Evaluation
4.4.2.1 Venturi Scrubbers—
Venturi scrubbers utilize the kinetic energy of a moving gas stream to atomize
the scrubbing liquid into droplets. Liquid is injected into the high velocity
4-54
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gas stream either at the inlet to the converging section or at the venturi
throat. In the process, the liquid is atomized by the formation and subse-
quent shattering of attenuated, twisted filaments and thin, cuplike films.
These initial filaments and films have extremely large surface areas available
for mass transfer [14].
Venturi scrubbers are usually designed for particulate collection, but they
can be used for simultaneous gas absorption as well. However, the design of
venturi scrubbers for removal of gaseous contaminants is dependent on the
availability of applicable experimental data. There is no satisfactory gener-
alized design correlation for these types of scrubbers, especially when
absorption with chemical reaction is involved. Reliable design must be based
on full-scale data or at least laboratory- or pilot-scale data.
Correlations are available to design venturi scrubbers for particulate removal.
The important design parameters are particulate loading and desired removal
efficiency, particle size distribution, pressure drop, liquid-to-gas ratio,
and gas velocity.
Particulate loading, size distribution, and removal efficiency—If the partic-
ulate size distribution and desired removal efficiency are known, several
correlations can be used to predict the required cut diameter for design
purposes. Calvert et al. [15] have developed parametric plots of overall
penetration versus the ratio of cut diameter to mass median diameter with
geometric standard deviation as the third parameter. These plots can be used
to determine the required cut diameter if the desired removal efficiency and
particle size distribution are known. Cut diameter can then be related to
pressure drop, liquid-to-gas ratio, and gas velocity for design purposes as
described in the following subsection.
Hesketh [16] has also developed an empirical relationship between penetration
of all particles 5 \Jtrn or less in diameter and the pressure drop across
Venturis based on data from the collection of a variety of industrial dusts.
Assuming that particles larger than 5 pm are collected with 100% efficiency,
this relationship may be utilized with size distribution data to estimate
overall penetration:
Pt = 0.065W(AP)"1-43
where Pt = fractional penetration
W = the weight fraction of inlet particles 5 pm or less in diameter
AP = pressure drop, in. WG
The major drawback in applying these correlations to venturi scrubber design
evaluation is that the particle size distribution will rarely be known until
testing is performed after startup. The size distribution of particles emit-
ted from an incinerator depends upon the relative number of particles genera-
ted by several factors responsible for the formation of particulate emissions:
(1) mechanical entrainment of combustible and noncombustible particles in the
furnace gases, (2) pyrolysis of hydrocarbons and subsequent condensation, and
(3) volatilization of metallic salts and oxides present in the wastes and
auxiliary fuels. Further, particle growth due to agglomeration and
4-55
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condensation of moisture between the incinerator and the control device will
affect the particle size distribution. There is no method for the -a priori
prediction of particle size distributions resulting from waste incineration.
While incineration of liquid wastes may result in mean particle diameters in
the 0.5- to 3-ym range, mean particle diameters resulting from incineration of
solid waste could range from 5 to 100 pm, depending upon the size distribution
of feed solids, their combustion characteristics, and the incinerator design.
If particle size distribution data is available, methods described in refer-
ences 15 or 16 can be used to determine the required cut diameter.
Pressure drop, liquid-to-qas ratio, and gas velocity—As described above,
particle cut diameter is a frequently used parameter for expressing and deter-
mining the particle collection performance of wet scrubbers. One reason for
this is because plots of collection efficiency versus particle diameter tend
to be rather steep in the region where inertial impaction is the predominant
collection mechanism. Because the cut is fairly sharp for venturi scrubbers,
a rough approximation of scrubber performance may be made by assuming that
particles larger than the cut diameter are collected with 100% efficiency
while those smaller will not be collected. A plot of cut diameter versus
pressure drop for gas-atomized scrubbers is presented in Figure 4-12 [12].
The plot is based on industrial and experimental data as well as mathematical
models, and can be used in conjunction with the methods developed by Calvert
et al. [15] to estimate penetration as a function of pressure drop.
Available data indicate that Venturis at hazardous waste incineration facili-
ties operate with pressure drops in the 30- to 50-in. WG range. Based on
Figure 4-12, this indicates that venturi scrubbers at these facilities are
designed for 0.3- to 0.4-ym cut diameters.
Pressure drop in venturi scrubbers is theoretically related to gas velocity
and liquid-to-gas ratio, as shown in the following relation developed by
Calvert [15]. This relationship assumes that all energy is used to accelerate
the liquid droplets to the throat velocity of the gas.
Q
AP = 2.12 x 10"5(UG)2 ^
where AP = pressure drop, in. WG
U = gas velocity, ft/s
Q./Q- = liquid-to-gas ratio, gal/1,000 ft3
L G
An alternative empirical approach by Hesketh [16] indicates that the pressure
drop for Venturis is proportional to U 2 and (Q./QG)°-78, as well as to the
gas density p (measured downstream from the venturi throat) and to A0-1
where A is the cross-sectional area of the venturi throat:
1270
4-56
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as
0.4
0.3
0.2
0.1
_L
_L
J L
1
(a 25)
2345 10 20304050
(0.50) (0.75)(LO)ll.2» (2.5) (5.0) (7.5) (10) (12)
GAS PHASE PRESSURE DROP. in. HjO (kPa)
100
(25)
Figure 4-12. Pressure drop versus cut diameter for gas-atomized scrubber
systems (Experimental data from large Venturis, other gas-
atomizers, scrubbers, and mathematical model.) [12].
Pressure drop will be relatively unsensitive to changes in A because of the
small exponent, but density will be inversely proportional to the gas tempera-
ture. These relationships can be used as internal consistency checks for the
proposed conditions of gas velocity, liquid-to-gas ratio, and pressure drop.
Liquid-to-gas ratios for venturi scrubbers are usually in the range of 5 to 20
gal/1,000 ft3 of gas. At existing hazardous waste incineration facilities,
liquid-to-gas ratios ranging from 7 to 45 gal/1,000 ft3 of gas have been
reported. In many cases, a minimum ratio of 7.5 gal/1,000 ft3 is needed to
ensure that adequate liquid is supplied to provide good gas sweeping. Gas
velocity data are not available at this time for venturi scrubbers operating
at hazardous waste incineration facilities. Typical venturi throat velocities
for other applications, however, are in the 100- to 400-ft/s range. The low
end of this range, 100-150 ft/s, is typical of power plant applications, while
the upper end of the range has been applied to lime kilns and blast furnaces.
Table 4-15 presents a procedure that can be used to evaluate proposed design
and operating criteria for venturi scrubbers.
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TABLE 4-15. VENTURI SCRUBBER DESIGN EVALUATION PROCEDURE
1. Is the design pressure drop comparable to current industry practice
(i.e., 30-50 in. WG)?
2. Are the proposed gas velocity and liquid-to-gas ratio comparable to
current industry practice?
3. Are the design pressure drop, gas velocity, and liquid-to-gas ratio
internally consistent? (see Worksheet 4-13.)
4.4.2.2 Packed Bed Scrubbers—
As described in Chapter 2, packed bed scrubbers are vessels filled with ran-
domly oriented packing material such as saddles and rings. The scrubbing
liquid is fed to the top of the vessel, with the gas flowing in either cocur-
rent, countercurrent, or crossflow modes. As the liquid flows through the
bed, it wets the packing material and thus provides interfacial surface area
for mass transfer with the gas phase. Water and caustic solution are both
commonly used as the liquid absorbent.
In the absorption of gaseous contaminants, the rate of mass transfer is direc-
tly proportional to the concentration gradient driving force, and restricted
by both gas and liquid film resistances. The primary design variables for gas
absorption are the depth of packing, liquid-to-gas ratio, superficial gas
velocity, and contact tine. Pressure drop across the bed is also an important
design consideration, but does not directly affect absorption efficiency.
Packed bed scrubbers can be used for limited particulate collection as well as
gas absorption, but, as explained in Section 4.4.1, they are not primarily
designed for this purpose.
Packing depth--The depth of packing required is best calculated from the
following expression [6]:
z = NOG x HOG
where Z is the packing depth, N is the number of overall transfer units, and
H is the height of a transfer unit.
OG
The number of transfer units depends on the removal efficiency requirement.
In gaseous emission control for hazardous waste incineration, the gaseous
contaminants to be removed usually constitute less than 10% of the total gas
stream because of the presence of nitrogen, oxygen, carbon dioxide, and water
vapor as the major gaseous components. Under these circumstances, the number
of transfer units can be calculated from the expression [6]:
4-58
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where Y is the actual gas concentration of the contaminant, Y2 is the con-
centration at the scrubber outlet, Yt is the concentration at the inlet,
and Y is the gas concentration of the contaminant in equilibrium with the
scrubling liquid. In industrial applications, the gaseous contaminant is
often very soluble in the scrubbing liquid, as is the case of hydrogen
chloride in water, or reacts very rapidly with the scrubbing liquid, as is the
case of hydrogen chloride with caustic solution. For both of these cases, the
equilibrium gas concentration is negligible and the number of transfer units
can be calculated as:
Nnr = In f „-"• ]
OG I * I
where Yj and Y2 are the inlet and outlet concentrations of the gaseous
contaminant.
The height of a transfer unit is a characteristic of the particular system,
and is influenced by the type and size of packing, gas and liquid flow rates,
and gas and liquid physical and chemical properties. It is often taken as a
constant over fixed ranges of operation and is given by the expression [6]:
where G is the total gas flow rate per unit cross section of bed, K is the
overall gas mass transfer coefficient, a is the interfacial surface 3rea per
unit volume of packing, and P is the total pressure. Values of K a for many
of the more commonly used gas absorption processes have been published in the
literature [17,18]. Typical values of K a are given in Table 4-16. For
gaseous contaminants that are highly solflble or chemically reactive with the
scrubbing liquid, the height of a transfer unit HQG is typically in the 1 to
1.7-ft range.
The transfer unit concept can be used to calculate packing depth requirements
if overall gas mass transfer coefficients are available. For quicker esti-
mates, however, other methods can be used. In Table 4-17, the estimated
depths of packing beds required are given for various removal efficiencies of
gaseous contaminants that are highly soluble or chemically reactive with the
scrubbing liquid. These estimated packing depth requirements are based on the
general rule that 1 in. size packings yield an H (height of a transfer unit)
equal to 1 ft, 1-1/2 in. size packings yield an HO(J equal to 1.3 ft, and 2 in.
size packings yield an HQG equal to 1.5 ft [11].
4-59
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TABLE 4-16. TYPICAL VALUES OF K a [18]
Reprinted with permission from Industrial and Engineering
Chemistry, 59(2) Copyright 1967 American Chemical Society
Gas
C12
HC1
S02
C02
S02
C12
Scrubbing
solution
NaOH
H20
NaOH
NaOH
H20
H20
Ib mole
in. H,0-ftJ-s
_s
1.4 x 10 5
1.1 X 10 6
4.8 x 10 6
1.6 x 10 7
2.2 x 10 8
9.5 x 10
TABLE 4-17. PACKING DEPTH REQUIRED TO ACHIEVE
SPECIFIED REMOVAL EFFICIENCY [11]
Reprinted by permission of Chemical Engineering Progress
Removal
efficiency,
percent
90
95
98
99
99.5
99.9
99.99
Packing size
1 in.
2.5
3.0
4.00
4.59
5.24
6.99
9.25
1-1/2 in.
3.2
3.74
4.99
5.74
6.50
8.76
11.5
2 in.
Depth, ft
3.74
4.49
6.00
6.99
8.01
10.5
14.0
3 in.
5.74
6.76
8.99
10.2
12.0
15.7
21.0
3.5 in.
6.99
8.50
11.3
13.0
14.8
19.8
26.0
Applicable only to gaseous contaminants that are highly soluble
or chemically reactive with the scrubbing liquid. Also, there are
variations in packing depths vs. the type of packing used (approx-
imately ±25% to 30%) which have not been taken into account.
The depth of packed beds for gaseous emission control typically ranges from
4.0 to 9.3 ft. The depth of packing can also be changed if removal efficiency
is lower than anticipated or if the carrier gas flow rate or waste streams
incinerated change. However, an evaluation of the packing depth requirement
is still desirable to assure that a packed tower design has sufficient
capacity.
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Liquid-to-gas ratio—The liquid-to-gas ratio is a design and operating param-
eter of prime importance. It is needed in the determination of the scrubber
diameter, and it has an effect on the height of a transfer unit. A high
liquid-to-gas ratio will lead to the requirement of a larger diameter, but at
the same time will also reduce the height of a transfer unit.
For each set of design conditions, there is a minimum liquid-to-gas ratio that
is required to achieve the desired removal efficiency. This minimum ratio can
be computed from equilibrium relationships. For gas contaminants that are
highly soluble or chemically reactive with the scrubbing liquid, the equili-
brium vapor pressure approaches zero. Theoretically, there is no minimum
liquid-to-gas ratio for the removal of these gas contaminants, based on vapor-
liquid equilibrium considerations. In practice, of course, sufficient scrubb-
ing liquid must be provided to assure that it is not saturated with the gas
contaminants removed, and to keep the packing surfaces thoroughly wet. When
scrubbing HCl, for example, acid concentration in the scrubber liquor is
normally limited to 1-2%.
The chemical requirement for acid gas neutralization in a scrubber is directly
proportional to the halogen content, sulfur content, and phosphorus content of
the hazardous waste streams incinerated. If caustic soda is used, at 60% in
excess of the stoichiometric amount, the requirement is given as:
Caustic soda requirement = 0.0176 x wt % Cl in waste + 0.0328
(Ib/lb waste) x wt % F in waste + 0.0604 x wt % P
in waste + 0.0389 x wt % S in waste
If the caustic content of the scrubbing solution is known, the minimum liquid
flow rate for neutralization can then be calculated in terms of gallons of
solution per pound of waste incinerated. The combustion gas yield per pound
of waste (previously calculated in Section 4.3.2) can then be used in conjunc-
tion with this value to determine the minimum liquid-to-gas ratio in units of
gallons per standard cubic foot of combustion gas.
Such methods can be used to determine the chemical requirements and minimum
liquid-to-gas ratio for scrubber water neutralization. However, complete
neutralization is not required for efficient acid gas scrubbing, as evidenced
by the fact that water is often used as the scrubbing liquor. When water is
used, acid gas solubilities as functions of temperature must be known to
accurately determine equilibrium relationships and minimum liquid-to-gas
ratios. A more complex situation is encountered in caustic scrubbing since
absorption in water and reaction occur simultaneously.
A simpler approach to evaluating minimum liquid-to-gas ratio requirements is
to examine current industry practices and/or to rely on actual test data.
Normal liquid-to-gas ratios in packed beds vary from 6 to 75 gal/1000 acf,
with most units operating at between 22 and 52 gal/1000 acf. In general,
lower liquid-to-gas ratios are needed for once-through scrubbing systems than
a60% excess is typical for single pass scrubbing. When scrubber liquid is
recycled, 5-30% excess can be acceptable for neutralization.
4-61
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for recycle systems to achieve the same removal efficiency because the driving
force for mass transfer is greater for once-through scrubbing. Likewise,
increasing the caustic addition rate will lower the minimum required
liquid-to-gas ratio, all other factors being equal.
The upper limit for liquid-to-gas ratio in packed towers is set by the flood-
ing condition. Generalized correlations of flooding velocities are available
and can be used to estimate the maximum liquid-to-gas ratio [6]. In practice,
however, flooding can be readily detected by sharply increased pressure drop
across the packed bed, and it can be eliminated by adjustment of the liquid
flow rate during operation. A quick check for proper column diameter sizing
can be accomplished by calculating the superficial gas velocity through the
tower. For packed beds with countercurrent flow, superficial gas velocities
are normally in the range of 7 to 10 ft/s, corresponding to approximately 60%
of the flooding velocity. The 40% safety factor allows for fluctuating gas
flows from the incinerator caused by changing waste composition and feed rate.
Contact time--In gas absorption devices, higher efficiencies are attained by
allowing the gas and liquid phases to be in contact for a longer period of
time. Removal efficiencies for gaseous contaminants in packed beds are di-
rectly related to the depth of packing, which in turn determines the contact
time.
The contact time required for gas absorption is a function of the rate of mass
transfer. The mass transfer rate, in general, is dependent upon four separate
resistances: gas phase resistance, liquid phase resistance, chemical reaction
resistance, and a solids dissolution resistance for scrubbing liquids contain-
ing solid reactants. For absorption of gaseous contaminants that are highly
soluble or chemically reactive with the scrubbing liquid, such as the absorp-
tion of HC1 by caustic solution, the contact time required for 99% removal is
extremely short (on the order of 0.4 to 0.6 s).
Pressure drop--For gas flow through packed beds, the pressure drop may be
calculated using the approximate correlation developed by Leva [6]:
AP/Z = C2 10
where AP/Z is the pressure drop in in. WG/ft of packing, U is the liquid
superficial velocity in ft/s, p is the gas density in Ib/Tt3, U is the
superficial gas velocity in ft/s. and C2 and C3 are constants. Pressure drops
for the common commercial packings can also be obtained from plots of pressure
drop versus gas and liquid flow rates. These plots are available from the
packing manufacturers and should be used for more accurate estimation of
pressure drop in the design evaluation process. For packed beds used for
gaseous emission control in hazardous waste incineration facilities, the
pressure drop usually ranges from 2.0 to 7.2 in. WG. Since the total pressure
drop across the packed bed is directly proportional to the depth of packing,
it indirectly affects the removal efficiency of gaseous contaminants. Higher
pressure drops also result in more efficient particulate collection.
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Table 4-18 presents a procedure that can be used to evaluate packed bed scrub-
ber design, based on the foregoing considerations of packing depth,
liquid-to-gas ratio, superficial gas velocities, contact time, and pressure
drop.
TABLE 4-18. PACKED BED SCRUBBER EVALUATION PROCEDURE
1. Is the proposed packing depth sufficient to attain the desired gas
absorption efficiency? See Table 4-17 .
2. Is the proposed liquid-to-gas ratio within normal limits, as described in
the preceding discussion?
3. Is the superficial gas velocity through the scrubber reasonable, based on
the preceding discussion? (Worksheet 4-7 shows how superficial gas
velocities may be calculated for incinerators. The same procedure may be
used for scrubber velocity calculation.)
4. Are the contact times and pressure drops through the scrubber reasonable,
based on the preceding discussion? (Contact time can be estimated using
the methods shown in Worksheet 4-6 for incinerator gas residence time,
replacing the incinerator volume term with the total volume occupied by
the packed section of the scrubber:
%"(*)
where Z = bed depth and D = column diameter.)
aTable 4-17 is only applicable for highly soluble gases such as HC1 and HF. If
other gaseous pollutants are to be removed, technical assistance may be
requested.
4.4.2.3 Plate Tower Scrubbers—
Plate towers are vertical cylindrical columns with a number of plates or trays
inside. The scrubbing liquid is introduced at the top plate and flows succes-
sively across each plate as it moves downward to the liquid outlet at the
tower bottom. Gas comes in at the bottom of the tower and passes through
openings in each plate before leaving through the top. Gas absorption is
promoted by the breaking up of the gas phase into small bubbles which pass
through the volume of liquid on each plate. Water, caustic solution, and lime
solution can all be used as the scrubbing liquid.
The primary design variables for gas absorption in plate tower scrubbers are
the number of plates or trays, the liquid-to-gas ratio, and the contact time.
Pressure drop is also an important design criteria although it does not direc-
tly affect absorption efficiency. Like packed bed scrubbers, plate tower
4-63
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scrubbers can be used for limited particulate collection as well as gas
absorption, but they are not primarily designed for this purpose.
Number of plates--In the design of plate towers for absorption of gaseous
contaminants that are highly soluble or chemically reactive with the scrubbing
liquid, the number of actual plates, Np, may be calculated from the
equation [6]:
N = .
Np I
where yj and y2 are the inlet and outlet concentrations of the gaseous contam-
inant and £._. is the Murphree vapor phase efficiency. In developing the above
equation, tKe assumption is made that E^ is the same for each plate in the
tower. The Murphree vapor phase efficiencies for the various plate designs may
be obtained from published data for selected gas-liquid systems [6,17]. These
would normally be in the 25% to 80% range. A rigorous estimation of the
Murphree vapor phase efficiency is extremely complex. For the case of absorp-
tion towers operating with low viscosity liquids and without excessive weepage
(liquid dripping) or entrainment, the figures in Table 4-19 can be used.
TABLE 4-19. MURPHREE VAPOR PHASE EFFICIENCY
FOR PLATE TOWERS [19]
"Reprinted by special permission from CHEMICAL ENGINEERING November 13
Copyright 1972 by McGraw-Hill, Inc., New York, N.Y. 10020."
Perforation Murphree vapor phase
diameter, efficiency,
in. percent
1/16 80
1/16 to 1/8 75
1/8 to 3/16 70
1/4 to 3/8 65
Liquid-to-gas ratio—For plate towers, the selection of the optimum liquid-
to-gas ratio depends largely on operating experience. Experience has indi-
cated that for single-pass crossflow bubble cap trays, the liquid flow should
not exceed 0.72d ft3/s, where d is the diameter of the tower in feet. Since
the gas flow rate in the tower can be estimated from the Souders-Brown
equation, the maximum liquid-to-gas ratio is given as follows:
'uguid\ = 630 / PG V'5. gal/1, OOP ft3
Gas /max
4-64
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where K is an empirical constant in the Souders-Brown equation, and p and PL
are the gas and liquid densities, respectively. Values of K are available
from Chemical Engineers' Handbook [6] or any other standard chemical engineer-
ing reference on mass transfer, distillation, or unit operations. For towers
with a tray spacing of 24 in. , K is typically 0.17.
Contact time--As in packed bed scrubbers, gas/liquid contact time is an impor-
tant factor affecting removal efficiency. In tray towers, greater depths of
liquid on the plates lead to greater plate efficiency through longer contact
time with the gas. Typical gas residence times in tray towers are comparable
to those for packed bed scrubbers; for example, 0.4 s to 0.6 s for 99+% ab-
sorption of HC1 in caustic solution. For absorption of S02 by lime solution,
longer contact times (in the range of 3-9 s) are needed to overcome the addi-
tional mass transfer resistance due to solids dissolution.
Pressure drop— For plate towers, the pressure drop across a perforated plate
is the sum of the gas resistance in passing through the perforations plus the
head required to overcome the equivalent liquid depth on the plate:
P., the pressure drop due to gas resistance in in. WG, can be calculated from
tne equation [20] :
where p. and p are the gas and liquid densities, respectively; UQ is the
linear velocity of the gas through perforations in ft/s.- and C is the ori-
fice coefficient. Values of C are 0.7-0.8 for sieve trays and 0.6-0.7 for
bubble cap trays. The pressure drop due to liquid head in in. WG, hL, can be
calculated from a knowledge of weir dimensions:
= 1.5 x 10-' pL (hw
where p is the liquid density in lb/ft3, hw is height of weir on the tray i
mm, ana h is height of weir crest in mm.
Total pressure drop can be roughly estimated by:
in
Np
where AP_ = total pressure drop
AP = pressure drop per plate
N = number of plates
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Table 4-20 presents a procedure that can be used for plate tower scrubber
design evaluation, based on consideraton of the number of plates required,
liquid-to-gas ratio, contact time, and pressure drop. The equations presented
above can be used to estimate pressure drop if this information is not
available from the vendor. However, vendor data are preferable.
TABLE 4-20. PLATE TOWER SCRUBBER EVALUATION PROCEDURE
1. Are the proposed number of plates comparable to or greater than the
required number of plates, as estimated by the procedures shown in
Worksheet 4-14a.
2. Are the proposed liquid flow and liquid-to-gas ratio reasonable and less
than the maximum acceptable values calculated by the methods shown in
Worksheet 4-15?
3. Are the contact time and pressure drop within reason?
aThis procedure is only valid for gases highly soluble in the scrubber liquor.
4.4.3 Quenching and Mist Elimination Considerations
In addition to scrubbers used for particulate and gaseous emission control,
air pollution control systems for hazardous waste incinerators frequently
include quench towers and mist eliminators. Located upstream from the scrub-
bers, quench towers are designed to reduce the temperature of the combustion
gases leaving the incinerator. This temperature reduction reduces the volu-
metric gas flow rate, and thus the scrubber capacity requirement. Quenching
also reduces evaporative water losses in the scrubber, and allows the use of
low temperature materials of construction such as fiber-reinforced plastic
(FRP) rather than more expensive, high temperature alloys or refractory.
Since venturi scrubbers provide evaporative gas cooling by the very nature of
their design, quenching may be considered optional when these devices are used
for primary particulate and/or gaseous emission control. Packed bed and plate
tower scrubbers, however, are not designed for evaporated cooling. When these
devices are used without upstream venturi scrubbing, quenching is nearly
always required. Without quenching, evaporative water loss from caustic or
lime solution can lead to particulate emissions of sodium or calcium salts.
At existing hazardous waste incineration facilities, combustion gases are
normally quenched to temperatures of 120-300°F, and below 200°F for FRP scrub-
ber construction. Typical water consumption rates for quenching are in the
range of 0.75 to 3.75 gal/1000 ft3 (0.1 to 0.5 L/m3) of gas.
Mist eliminators are widely used to reduce emissions of liquid droplets from
scrubbers. Mist eliminators are normally installed downstream from, or as an
4-66
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integral part of, the scrubbing system. In general, only one mist eliminator
is needed Where two or more scrubbers are used in series, intermediate mist
elimination may be provided, but it is not considered necessary to prevent the
release of liquid droplets to the environment.
The types of mist eliminators most commonly used in hazardous waste incinera-
tion facilities are cyclone collectors, simple inertial separators such as
baffles, wire mesh mist eliminators, and fiber bed mist eliminators. Cyclones
are used for collecting very heavy liquid loadings of droplets over 10 \an,
such as those emitted from venturi scrubbers. The design of cyclone mist
eliminators follows the principles of cyclone design for particles. For this
type of mist eliminator, therefore, the collection efficiencies for liquid
droplets and solid particles are about the same. Collection efficiencies of
nearly 100% are possible for droplets in the 10- to 50-um range, which is
consistent with the liquid droplet sizes emitted from venturi scrubbers.
In the simple inertial separators, the primary collection mechanism is iner-
tial impaction, and to a lesser extent interception. Devices such as louvers,
zigzag baffles, tube banks, and chevrons are simple inertial separators. The
cut diameter for liquid droplet collection in these devices is typically
10 urn Pressure drops are in the 0.02- to 0.12-in. WG (50-to 300-Pa range)
depending on the gas velocity and closeness in spacing of the collection
surfaces.
Wire mesh eliminators are formed from meshes of wire knitted into a cylindri-
cal open weave which is then crimped to give a stable wire configuration. As
rising mist droplets contact the wire surface, they flow down the wire to a
wire junction, coalesce, run off, and flow freely to the bottom of the bed.
The depth of the wire pad varies from 2 to 12 in. (50 to 300 mm) with 4-6 in.
pads being the most common. Pressure drops usually range from 0.02 to
4.0 in. WG, depending on the gas velocity, the wire density, and the depth of
the pad. in normal operation, the pressure drop is not likely to be more than
1 in WG The cut diameter for liquid droplet collection is a strong function
of the gas velocity, and can range from 1 to 10 Mm- Sizing of the wire mesh
mist eliminator is based on the allowable gas velocity, calculated using the
Souders-Brown equation:
u = 0.107
Where u is the gas velocity in m/s, PL is the density of the scrubbing liquid,
and p. is the gas density.
For collection of fine acid mists, fiber bed mist eliminators are most appro-
priate In this type of device, large mist particles are collected on the
fibers by inertial impaction and direct interception, whereas smaller parti-
cles are collected by Brownian diffusion. Since fiber bed mist eliminators
are designed so that Brownian diffusion is the predominant mechanism for mist
collection, extremely small particles of less than 1 pm are recovered with
high efficiency. Typical gas velocities through fiber bed mist eliminators
4-67
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range from 5 to 10.0 ft/s (1.5 to 30 m/s), with corresponding pressure drops
of 5 to 15 in. WG. Collection efficiencies are 100% for droplets larger than
3 (Jm, and 90% to 99.5% for droplets less than 3 |Jm.
In wire mesh and fiber bed mist eliminators, plugging by solid deposition is a
potential problem. This problem can be partially overcome by intermittent
washing with sprays, by selection of a less densely packed design, and by the
use of sieve plate towers or cyclone separators upstream as an additional mist
and particle collection device. At hazardous waste incineration facilities,
the most common configuration used for gas cleanup is a high energy venturi
scrubber followed by two sieve trays for additional gas absorption, and then
another sieve tray and an inertial separator or a wire mesh eliminator to
reduce emissions of liquid droplets. Operating experience has indicated that
this is a most effective combination.
In general, three "rules of thumb" can be followed in evaluating provisions
for quenching and mist elimination at hazardous waste incineration facilities.
• Quenching should be provided upstream from packed bed or plate tower
scrubbers unless these devices are preceded by a venturi scrubber.
• Quenching is optional when venturi scrubbers are used, although high
temperature materials of construction may be required if quenching is not
employed.
• A mist eliminator should be provided downstream or as an integral part of
the last scrubber in the air pollution control system.
4.4.4 Prime Mover Capacity Evaluation
Prime movers in rotary kiln incineration systems are always induced draft
fans, located downstream from the air pollution control devices, while either
induced draft or forced draft systems may be used with liquid injection incin-
erators. For the overall system to function properly, the prime mover must be
capable of moving the combustion gases through each air pollution control
device while overcoming the corresponding pressure drops. As the total pres-
sure drop through the system increases, the volumetric flow capacity of the
fan decreases. The functional relationship between these two variables,
pressure and flow capacity at a specific temperature, should be specified by
the manufacturer.
Therefore, it is necessary to (a) determine the combustion gas flow rate at
the fan inlet temperature, (b) estimate the total pressure drop across the
system, and (c) compare the fan capacity at the calculated pressure drop with
the predetermined combustion gas flow rate in order to evaluate whether or not
the fan has sufficient gas handling capacity. If this capacity is insuffi-
cient the burning rate must be decreased, the fan capacity must be increased,
or the ductwork must be modified to reduce pressure drop. The following
discussion focuses on Step (b) above, estimation of the total system pressure
drop. Combustion gas flow rate calculations are discussed in Section 4.3.2.
4-68
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The major pressure drops to be considered are the pressure drops across the
various air pollution control devices. These pressure drops can be determined
from manufacturer specifications once the gas flow rates at the inlets to
these devices are known. Flow rates can be calculated quite simply as
follows:
« = qstd
where q = combustion gas flow rate, acfm
q . = combustion gas flow rate, at standard conditions of 68°F and
std 1 atm, scfm (from Worksheet 4-2 or 4-4)
T = inlet temperature, °F
Other pressure drops that need to be considered are frictional losses due to
flow through the ductwork connecting each air pollution control device. For
any given duct, the total pressure drop may consist of three component pres-
sure drops: (1) frictional losses due to flow through straight lengths of
ductwork, (2) frictional losses due to flow through bends in the ductwork, and
(3) losses due to sudden constriction of flow at the inlet to the duct.
Pressure drop through a straight length of duct can be estimated using Fig-
ure 4-13, reproduced from Reference 6. This figure can be used in the fol-
lowing manner:
(1) Identify the temperature and average molecular weight of the gas.
(2) Draw a line through these two points on the temperature and molecular
weight scales, and extrapolate this line to a point on the viscosity
scale.
(3) Identify the inside diameter of the duct and the mass flow of combustion
gases.
(4) Draw a line through these two points on the diameter and weight flow
scales, and extrapolate this line to the arbitrary reference scale.
(5) Connect the point on the arbitrary reference scale with the predetermined
point on the viscosity scale.
(6) Identify the pressure drop per foot of duct on the AP scale at the inter-
section of the line between the reference and viscosity scales.
(7) Calculate the total pressure drop across the length of straight duct as
follows: r T
fV
AP
aFrom Figure 4-13.
4-69
-------
where AP = total pressure drop, in. H20
LS = length of straight duct, ft
PG = absolute gas pressure, atm
For a reasonable approximation, assume
P. 5 1 atm
G
FLOW IN PIPI8 AND CHANNELS
TurbuKffl nglan
Pr***ura drop
du« to friction
ift
L
Bowd on cMon «t««l pip*
Ctnlipo«.°'«
Lh/cu. ft at I aim.
-03
0.4
-O3
-O
9
at
-0.1
-oa
-oo
Hx/«o,in_lrv
/ft
-COO
k as
c^.;>'
xioa-
aooa-
QOOOO,- ^^
' • ftOttfM
ooooa-
Moooa" : rOjQOOl
aaooaa
0.00000-
•400001
10-
\
ai.
0.1
0.01
aoo-'
Tcmpamlurt.'C
-WO-
O-:
~5ol
IOW
^rMO
«»-iaso
: -iso
Liouidt
600-
Too-:
BOO- :
900-^ r100
ooo-: -
^-50
-30
soo: r200
Permission from McGraw-Hill encyclopedia of scence and technology,
Vol. XI. Copyright 1960, by McGraw-Hill Book Company.
Figure 4-13. Pipe flow chart [6].
If the duct is square or rectangular the following quantities should be used
as equivalent diameters:
Square duct: D = length of a side
Rectangular duct: D = r-
eq a + b
where a, b = width and depth of the duct
4-70
-------
Pressure drops across bends in a duct can be estimated using Figure 4-14.
Here, L /D, the equivalent straight-length-to-diameter ratio, is expressed as
a function of the ratio of the radius of curvature of the elbow, R, to the
diameter of the duct. Figure 4-15 shows the relationship between R and D.
Figure 4-14. Total frictional pressure drops in 90° bends [6].
Permission for Figures 4-14 and 4-15 from Chemical Engineers' Handbook,
fifth edition. Copyright 1973 by McGraw-Hill Book Company.
Figure 4-15. 90° bends (a) smooth bend, (b) segmental bend [6].
The procedure for estimating pressure drops from Figure 4-14 is as follows:
(1) Determine R/D and read the corresponding L /D value from Figure 4-14.
(2) Identify the pressure drop across the length of straight duct upstream
and downstream from the bend and the corresponding length of straight
duct.
(3) Convert the L /D value to a pressure drop estimate-.
AP'
API 5s
4-71
-------
where AP1 = pressure drop across the bend, in. H20
AP = pressure drop across the straight segment of duct, in. H20
D = diameter of the duct, in.
L_ = length of straight duct, ft
If 45° or 180° angle bends are encountered, the corrected pressure drops are
= 0.65 AP'go0
and
Additional pressure drops occur at the inlet to a duct because of the sudden
contraction of the gases. These pressure drops can be estimated by the
following equation:
where AP" = pressure drop, in. H20
V = gas velocity, ft/s
g = gravitational constant, 32.2 Ib-m ft/lb-f s2
p = gas density, lb/ft3
gas
p__ . = density of liquid water, 62.4 lb/ft3
**2
K = sudden contraction-loss coefficient for turbulent flow
c
Table 4-21 presents K values for various ratios of duct cross-sectional area,
A., to the cross-sectional area of the unit upstream from the duct, Ap.
TABLE 4-21. SUDDEN CONTRACTION-LOSS COEFFICIENT
FOR TURBULENT FLOW [6]
Permission from Chemical engineers' handbook, fifth
edition. Copyright 1973 by McGraw-Hill Book Company.
A^/A 0 0.2 0.4 0.6 0.8 1.0
d' p
K 0.5 0.45 0.36 0.21 0.07 0
c
When the pressure drops through each air pollution control device and segment
of ductwork are calculated and summed, this should provide a rough estimate of
the total pressure drop through the system.
4-72
-------
Table 4-22 presents a procedure for evaluating the prune gas mover capacity.
A step-by-step method for performing the necessary calculations is shown in
Worksheet 4-16.
TABLE 4-22. PRIME MOVER CAPACITY EVALUATION PROCEDURE
1. Identify the approximate combustion gas flow rate in scfm (see Work-
sheet 4-2 or 4-4).
2. Identify the temperatures at (a) the incinerator outlet, (b) the inlet to
each air pollution control device, and (c) the fan inlet. Record this
information on Worksheet 4-16.
3. Identify the pressure drops across each air pollution control device, as
specified by the manufacturer, and record this information on
Worksheet 4-16.
4. Estimate the pressure drops across each segment of ductwork between the
incinerator and the fan, and add these pressure drops to those determined
in checkpoint #3 to estimate the total pressure drop across the system.
5. Identify the manufacturer specifications for fan capacity at the calcu-
lated pressure drop and fan inlet temperature.
6. Does this capacity meet or exceed the approximate combustion gas flow
rate?
4.4.5 Process Control and Automatic Shutdown System Evaluation
In the design of the incinerator and scrubber systems, a number of safety
features should be provided to allow for equipment failures and operational
errors. Process control systems and safety interlocks for incinerators are
discussed in Section 4.3.5. The following safety interlocks relating to the
scrubber operation are recommended:
(1) Shutdown of the waste and auxiliary fuel feed systems on loss of scrubber
water flow.
(2) Shutdown of the waste and auxiliary fuel feed systems if the incinerator
effluent gas temperature exceeds the maximum design temperature for the
quench section.
(3) Shutdown of the waste and auxiliary fuel feed systems if the quenched gas
temperature exceeds the maximum design temperature for the scrubber.
(4) Shutdown of the waste and auxiliary fuel feed systems, followed by shut-
down of the scrubber systems, on failure of forced or induced draft fan.
4-73
-------
(5) Shutdown of the waste and auxiliary fuel feed systems followed by shut-
down of the scrubber systems, if the pH of the scrubbing liquid does not
meet specified values.
(6) Shutdown of the waste and auxiliary fuel feed systems, followed by shut-
down of the scrubber systems, if the pressure drop across the scrubber
becomes excessive, indicating unsteady-state operation or clogging
problems.
When possible, it is desirable to have a time delay between shutting off the
waste to be incinerated and shutting off the auxiliary fuel. This will help
to ensure an adequate burnout of the waste and minimize emissions of
incomplete products of waste combustion and unreacted waste.
In situations when the incinerator effluent gas temperature or the quenched
gas temperature exceeds the maximum design temperature for the next piece of
equipment, it is desirable to have provisions for emergency stack bypass
designed into the system. An indication of excess temperature should lead to
shutdown of the incinerator through the safety interlock system. It is recog-
nized, however, that any of the interlock devices can and will malfunction
some of the time. To protect the scrubber system from damage by excess tem-
perature, switches for stack bypass can be provided. These switches should
only be operated as an emergency measure, and under strict supervision. To a
limited extent, the additional thermal lift caused by the excess temperature
will raise the effective stack height and alleviate the impact on plant
personnel.
At power plants, chemical plants, and refineries, stack bypass switches are
often provided to enable maintenace to be done on scrubber systems while
process operation continues. Stack bypass for maintenance purposes is not
recommended for hazardous waste incineration facilities.
4.4.6 Material of Construction Considerations
Effluent gases from incineration of hazardous wastes contain a number of
corrosive contaminants, including HCl, S02, S03, HF, and possibly C12, HBr,
Br2, P2°s. and organic acids. The presence of HCl, the principal gaseous
contaminant, is of particular concern because it accelerates pitting and
crevice corrosion of most materials. The careful selection of the materials
of construction for the quench tower and scrubber system is therefore
extremely important.
In the quench section where temperatures of approximately 1800°F are commonly
encountered, Hastelloy C and Inconel 625 have found wide acceptance. Other
possibilities are the use of carbon graphite or acid resistant refractories as
lining material for carbon steel or stainless steel construction, but the
quench spray nozzles should still be made of Hastelloy C or Inconel 625.
For the scrubber, Hastelloy C or Inconel 625 can again be used as materials of
construction. At more moderate temperatures, however, FRP is recommended
because it is economical, easily fabricated, and lightweight. It also has
4-74
-------
good resistance in both acid and alkaline environments, up to a service tem-
perature of around 200°F. Polyvinyl chloride (PVC) can also be considered as
a material for wet scrubber construction, but its use is limited to tempera-
tures of less than 160°F.
If structural strength becomes a prime consideration because of the size and
weight of the scrubber, carbon steel or stainless steel can be used with a
suitable lining material to provide the required corrosion protection. Field
corrosion studies have shown that carbon steel and stainless steel both expe-
rienced severe corrosion problems and are not recommended as materials of con-
struction for scrubber systems treating acid gases unless linings are used.
Rubber, carbon graphite, FRP, Teflon, Kynar (polyvinylidene fluoride), acid
resistant bricks, and refractories are examples of suitable lining materials.
Teflon, however, cannot be bonded to a metal surface and requires multiple
flanges to stay in place. Kynar is similar to Teflon in most of its proper-
ties, but it is available in sheet form bonded to a glass backing. In packed
beds, the packing material should be made of ceramic, carbon, or plastics to
withstand attack by corrosive acids.
A special concern is the potential presence of HF in the incinerator exhaust
gases. It is well known that glass and any ceramic material containing silica
are attacked by HF or H2SiF6. Many grades of rubber linings also contain
silica as a filler, which could be leached out by HF or H2SiF6- Common mate-
rials of construction of HF scrubbers include FRP (with special shielding
material to prevent attack of the glass fibers), rubber-lined steel, Kynar,
and graphite-lined steel. Among the metals, monel has shown good resistance
over wide concentration and temperature ranges. At one hazardous waste incin-
eration facility, a Monel-lined stainless steel packed tower with polypropyl-
ene Intalox saddles is used to control HF emissions from the incinerator. In
addition, both Hastelloy C and Inconel 625 have been used as lining material
in hydrofluoric acid service and have demonstrated outstanding corrosion
resistance to HF.
Although the corrosion and temperature aspects of materials selection are of
primary importance, erosion must also be considered in scrubbers designed for
particulate control. Venturi scrubbers are particularly susceptible to ero-
sion due to the high gas velocities and particulate loadings encountered
during normal duty. Throat and elbow areas are generally subject to the most
wear. FRP does not stand up well in these regions and harder, corrosion
resistant, materials are required for long service life.
All the foregoing factors should be considered in evaluating materials selec-
tion for the quench tower and scrubber system. If materials of construction
other than those discussed above are proposed, the adequacy of these materials
for the temperature/gas environment under consideration should be evaluated.
4.5 WORKSHEETS
The worksheets in this section can be used to perform the design evaluation
calculations described in Sections 4.3 through 4.4.
4-75
-------
WORKSHEET 4-1. PROCEDURE TO CALCULATE DESTRUCTION
AND REMOVAL EFFICIENCY
1. From trial burn data, identify the following parameters:
Total waste feed rate, (win>TOTAL = _ Ib/hr
Mass fraction of each principal
organic hazardous constituent in
the waste, nt = _ Ib/lb waste
n2 = _ Ib/lb waste
n3 = _ Ib/lb waste
n4 = _ Ib/lb waste
ns = _ Ib/lb waste
Gas flow rate in the stack, q = _ scfm
Concentration of each prin-
cipal organic hazardous
constituent in the stack gas, cj _ uo/scf
c2 = ~
c3 = _ Mg/scf
c4 = _ Mg/scf
cs = _ Mg/scf
2. Calculate the mass feed rate of each hazardous constituent to the incin-
erator, using the following equation:
ni TOTAL
lb/hr
lb/hr
lb/hr
lb/hr
lb/hr
3. Calculate the mass flow rate of each hazardous constituent in the stack
using the following equation:
out'
7.57 x 10°
= lb/hr
3 = lb/hr
= lb/hr
= lb/hr
4. Calculate the destruction and removal efficiency for each hazardous
constituent using the following equation:
4-76
-------
(W. ). -
x in'i
i
(w. ).
v in'i
(100)
DREj =
ORE 2 =
DRE3 =
ORE 4 =
DRE5 =
4-77
-------
WORKSHEET 4-2. PROCEDURE TO CALCULATE STOICHIOMETRIC AIR REQUIREMENTS,
COMBUSTION GAS FLOW, AND COMPOSITION
1. Identify the elemental composition and moisture content of the waste or
waste mixture.
Carbon, C : Ib/lb waste
Fuel hydrogen, H : Ib/lb waste
Moisture, H20W: Ib/lb waste
Oxygen, 0 : Ib/lb waste
Nitrogen, N : Ib/lb waste
Chlorine, ClJJ: Ib/lb waste
Fluorine, F : Ib/lb waste
Bromine, Br": Ib/lb waste
Iodine, I : Ib/lb waste
Sulfur, S";: Ib/lb waste
Phosphorus, P*: Ib/lb waste
2. If auxiliary fuel is to be burned in conjunction with the waste, identify
the fuel type and approximate, proposed fuel-to-waste ratio from the per-
mit application. (If auxiliary fuel is to be used only for startup,
proceed to Step #5.)
Fuel type:
Fuel:waste ratio, nf = Ib fuel/lb waste
3. Determine the approximate elemental composition of the fuel from the
following table.
Ib Component/Ib fuel [21]
Residual fuel Distillate fuel Natural
Component oil (e.g.. No. 6) oil (e.g., No. 2) gas
C, 0.866 0.872 0.693
H* 0.102 0.123 0.227
Nt - 0.08
S* 0.03 0.005
4. Calculate the composition of the combined waste/auxiliary fuel feed.
C + nfcf
C: V A " WU* feed
1 + n_
H + n-H.
H: w. „ r r = Ib/lb feed
1 + n_
Ib/lb feed
4-78
-------
N: V+ n/ = Ib/lb feed
0
0: •:—— = Ib/lb feed
1 + nf
Cl: T—?— = Ib/lb feed
1 + nf
'-,_
'4f
F: ^—— = Ib/lb feed
Br«
Br: . * = Ib/lb feed
I + n, ~~^^-~~^^
I: -—2— = Ib/lb feed
1 + n,
S + n,S,
S: -i^ £-£ = Ib/lb feed
1 + nf
P
P: -—2— = Ib/lb feed
1 * nf
5. Calculate the stoichiometric oxygen requirement based on the combustion
reactions described in Section 4.3.2.1.
C x 2.67 ^r2* = Ib 02/lb feed
Ib C
" 8'° ^ " * °2/lb f"d
S x 1.0 ^% = Ib 02/lb feed
ID S ^^~~^~^~~-
P x 1.29 ^| = Ib 02/lb feed
-0(in feed) = - Ib 02/lb feed
(02).^.K =E= » 02/ Ib feed
'stoich
4-79
-------
6. Calculate the combustion gas mass flows, based on the stoichiometric
oxygen requirement.
C02: C x 3.67 j^ c
H2<>= (H - 7TT
= _ lb C02/lb feed
19
»*•' <°*>stoich
HC1: Cl x 1.03
HF: F x 1.05
Br2: Br
!2. I
« 3'31
IS (ln air>]
S0: S x 2.0
P20S: P X 2.29 -u/p
Combustion products = CP =
lb HCl/lb feed
lb HF/lb feed
lb Br2/lb feed
lb I2/lb feed
lb S02/lb feed
feed
Ib/lb feed
7. Identify the total excess air rate.
EA = _ %/100
8. Calculate the additional nitrogen and oxygen present in the combustion
gases due to excess air feed.
(02)£A = EA x (02)stoich =
(N2)EA = 3.31 ^k (in air) x (02)
9. Calculate the total combustion gas flow.
£A
02/lb waste
_ lb N2/lb waste
Combustion gases = CG = CP + (°2)EA + EA
waste
10. Calculate the mass fraction of each combustion gas component.
C02:
H20:
*
CG
Ib/lb gas
Ib/lb gas
4-80
-------
N2(from #6) +
-------
WORKSHEET 4-3. PROCEDURE TO CALCULATE THE NET HEATING VALUE OF THE WASTE
Basis: Heating value is reported as a higher heating value (HHV) determined
at standard 77°F (25°C).
Identify the following:
HHV = Btu/lb waste
H = IbH/lb waste
Cl = IbCl/lb waste
F = IbF/lb waste
H20 = Ib/moisture/lb waste
Calculate the net heating value (NHV):
NHV = HHV - 1,050 H20 + 9(H - -^r - 75] = Btu/lb waste
4-82
-------
WORKSHEET 4-4. PROCEDURE TO CALCULATE STOICHIOMETRIC AIR REQUIREMENTS,
APPROXIMATE COMBUSTION GAS FLOWS, AND APPROXIMATE GAS
COMPOSITIONS
1. Identify the elemental composition and moisture content of the wastes fed
to the kiln.
1. Solids (kiln) 2. Liquids (kiln)
Carbon. C : Ib/lb waste
Fuel hydrogen, H : Ib/lb waste
Moisture, H20 : Ib/lb waste
Oxygen, 0 : Ib/lb waste
Nitrogen, N : Ib/lb waste
Chlorine, Cl": Ib/lb waste
Fluorine, F : Ib/lb waste
Bromine, Br : Ib/lb waste
Iodine, I : Ib/lb waste
Sulfur, Sw: Ib/lb waste
Phosphorus, pJJ: Ib/lb waste
2. Identify the approximate liquid and solid waste feed rates to the kiln,
and calculate the liquid/solid feed fractions.
Liquid feed rate, n^ = Ib/hr
Solid feed rate, m2 = Ib/hr
Total feed, m12 - mj + m2 = Ib/hr
Liquid fraction, na = m1/m12 = lb liquid/lb waste
Solid fraction, n2 = 1-nj = lb solid/lb waste
3. If auxiliary fuel is to be burned in conjunction with the wastes, identify
the fuel type and approximate, proposed fuel-to-waste ratio.
Fuel type:
Fuel:waste ratio in kiln: nf = lb fuel/lb waste
4. Determine the approximate elemental composition of the fuel from the
following table.
Component
lb component/ lb fuel
Residual
fuel oil
(e.q. No. 6)
0.866
0.102
Distillate
fuel oil
(e.g. No. 2)
0.872
0.123
T21]
Natural
gas
0.693
0.227
0.08
N
S* 0.03 0.005
4-83
-------
5.
Calculate the composition of the combined waste/auxiliary fuel feed to
the kiln.
nlCl + n2C2 + nC
Ck:
Hk:
H2°k:
Nk:
ff
1 + n,
nlHl + n2H2
n,H.>Oi
+ n2N2 + n
.
c±k:
k:
Brk:
V
n
ngBrg
n
n
Ib/lb feed
Ib/lb feed
Ib/lb feed
Ib/lb feed
Ib/lb feed
Ib/lb feed
Ib/lb feed
Ib/lb feed
Ib/lb feed
_ Ib/lb feed
Ib/lb feed
6.
Calculate the stoichiometric oxygen requirement for the kiln, based on
the combustion reactions described in Section 4.3.2.1.
2-67
lb 02/lb feed
Ib 02/lb feed
lb 02/lb feed
4-84
-------
p x 1 29 2
Pk X 1-z Ib P
-Ok (in feed)
Ib 02/lb feed
lb/02/lb feed
<02)
stoich(k)
Ib 02/lb feed
7. Calculate the combustion gas mass flows, based on the stoichiometric
oxygen requirement (assume complete combustion is achieved for purposes
of gas flow estimation).
C02:
Ib C02/lb feed
H20k (in feed) =
Ib H20/lb feed
stoich(k)
3.31
(in .i
Nk (in feed)
Ib N2/lb feed
HClk:
Ib HCl/lb feed
HFk:
Ib HF/lb feed
Ib Br2/lb feed
Ib I2/lb feed
S02. : S. x 2.0
Ib SO;
Ib S
Ib S02/lb feed
Kiln combustion products = CPk =
Ib P205/lb feed
Ib/lb feed
4-85
-------
8. Identify the elemental composition and moisture content of the liquid
wastes to be burned in the afterburner (if any).
C3: Ib/lb waste
H3: Ib/lb waste
H203: Ib/lb waste
03: Ib/lb waste
N3: Ib/lb waste
C13: Ib/lb waste
F3: Ib/lb waste
Br3: Ib/lb waste
I3: Ib/lb waste
S3: Ib/lb waste
P3: Ib/lb waste
9. Identify the fuel type and approximate, proposed fuel-to-waste ratio for
the afterburner.
Fuel type:
Fuel: waste ratio, nfA = _ lb fuel/lb waste
10. Determine the approximate elemental composition of the fuel from the
table shown in Step 4.
Cf = _ Ib/lb fuel
HV* = _ Ib/lb fuel
N** = _ Ib/lb fuel
S™ = Ib/lb fuel
*^^^^^~
11. Calculate the composition of the combined waste/auxiliary fuel feed to
the afterburner.
C3 + n C
' feed
nfA
H3 + nfAHfA
i A * _ WU3 feed
l + "fA
H20S= "? -1 = Ib/lb feed
A IT n ^^^^^^^^^^^^^^^^^^
A i + nfA
nN
feed
»
A 1 + n
4-86
-------
0.: = _ Ib/lb feed
A * + nfA -
Cl_: g = _ Ib/lb feed
A X + nfA -
F_.- . f.an = _ Ib/lb feed
A 1 + nfA -
Bra: ra = _ Ib/lb feed
A 1 + n£A -
I.: . * = _ Ib/lb feed
A 1 + nfA -
S_: , = _ Ib/lb feed
A * + nfA -
nfA
Ib/lb feed
12. Calculate the stoichiometric oxygen requirement for the afterburner feed,
based on the combustion reactions described in Section 4.3.2.1.
CA X 2'67 ^"C2 = _ "* °2/lb
f C1A FA\ Ib 0,
HA * 3TT - it)" 8-° STT* = * °2/lt feed
SA x 1.0 -2 = Ib 02/lb feed
PA x 1.29 -a = Ib 02/lb feed
-0. (in feed) = - Ib 02/lb feed
A m^^^^^^^m—^^^^^^^^^
stoich(A) ~ '•- z' ~ feed
4-87
-------
13. Calculate the combustion gas mass flows, based on the stoichiometric
oxygen requirement.
Ib C02/lb feed
_
35.5
ib
'° Ib H
NV [
: «>2)
stoich(A)
x 3
H20A (in feed) =
•31 £|J (^ air) j
+ N (in feed)
A
Ib H20/lb feed
Ib N2/lb feed
HC1A:
Ib HCl/lb feed
HFA=
Ib HF/lb feed
Ib Br2/lb feed
Ib I2/lb feed
S02: S x 2.0
Ib S02/lb feed
P205A:
Afterburner combustion products = CP& =
Ib P205/lb feed
Ib/lb feed
14. Calculate the ratio of total afterburner feed to total kiln feed.
Liquid waste to kiln: ml
Solid waste to kiln: m2
Auxiliary fuel to kiln: (m1 + "«2)nfK
Ib/hr
Ib/hr
Ib/hr
4-88
-------
Liquid waste to afterburner: m3 = Ib/hr
Auxiliary fuel to afterburner: "»3nfA = Ib/hr
+ m2) (1 + n-..)
. SS_ = ib afterburner feed/lb kiln feed
fA
nAK ~ m3 n
15. Calculate the total combustion gas mass flows, based on stoichiometric
oxygen requirements.
C02v H ——z» "av
K A AK _ lb/lb feed
nAK
H20V + n... H20
H 0: JJL - AK - A = _ ^,/ib feed
+
n»v "2*
_M A _ lb/lb feed
AK
"AK
nAK
S°2K * "AK S°ZA _
1 AK
AK
HC1V + n... HC1.
uri. — = lb/lb feed
•**» J» • • m _ ^^^•^^^^^^^^••^^•^^^
1 * "AK
HFv + n»K HFa
_JS AK A _ j^/ij, feed
1 + "AK
Br2v + N Br2
lb/lb feed
1AK
a
A = ^/Ib feed
Combustion products = CP = £ = lb/lb feed
4-89
-------
16. Identify the total excess air rate for the system (i.e., to be maintained
in the afterburner).
EA =
17. Calculate the additional nitrogen and oxygen present in the combustion
gases due to excess air feed.
,0 } _ EA x (°2)stoich(K) * "AK <°«).toich(A) = _ y, Q /lb waste
(OZ)EA ~ EA x i * n^ - 2/
EA • 3'31 liHSj (in air) x (OZ)EA - - * Nz/lb waste
18. Calculate the total combustion gas flow.
Combustion gas flow = CG = CP + (02>EA + EA = _ ^/^ feed
19. Calculate the mass fraction of each combustion gas component.
C02: * =
H20: = _ Ib/lb gas
N2(from 15) +
N2: - - - _ U>/lb gas
02: -T = _ Ib/lb gas
CG
HC1: = _ Ib/lb gas
HF: = _ Ib/lb gas
Br2: 2 = _ Ib/lb gas
I,:
4-90
-------
S02: -
P205: 2g* = Ib/lb gas
20. Identify those components that constitute less than 1-2% of the combustion
gas. These components can be eliminated from further consideration in
heat and material balance calculations. In most cases, C02/ H20, N2,
and 02 will be the only combustion gas components that need to be considered.
21. Calculate the volumetric flow of the major combustion products from the
kiln at standard conditions of 68°F and 1 atm.
C02: ( §§* )x CG -r 0.114 Ib/scf = scf/lb
H20: ( ^ jx CG * 0.0467 Ib/scf = scf/lb
CG -r 0.0727 Ib/scf = scf/lb
«••(&)-
Ix CG -r 0.083 Ib/scf = scf/lb
other: Ogcr CG ^ (o.o0259 H) Ib/scf = scf/lb
\ CG /
where M = molecular weight
Total flow, q = £ = scf/lb feed
q x (in! + m2) (1 + nf ) (1 + nAK) •=- 60 = scfm
4-91
-------
WORKSHEET 4-5. PROCEDURE TO CALCULATE EXCESS AIR RATE FOR A
SPECIFIED TEMPERATURE AND FEED COMPOSITION
Identify the following input variables:
From Worksheet 4-2, Step #5
C°a>
stoich
From Worksheet 4-2, Step »6
C02
H20
Other major component(s)
From Worksheet 4-3
Ib/lb feed
Ib/lb feed
Ib/lb feed
Ib/lb feed
NHV
waste
Btu/lb waste
From proposed operating conditions
Operating temperature, T =
Air preheat temperature, T . =
(if applicable)
oF
op
If auxiliary fuel is to be burned in conjunction with the waste, also
identify the following from Worksheet 4-2.
nf =
HVf =
lb fuel/lb waste
Btu/lb fuel
If air preheating is employed, calculate the corresponding enthalpy
input to the incinerator. If the combustion air is not to be preheated,
proceed to Step #3.
- 77)(°*>stoich
Btu/lb feed
AHt = AHt'd + EA)
Calculate the heat generated by combustion of the waste or waste/
auxiliary fuel mix.
*• nf HVf
n.
Btu/lb feed
Calculate the heat loss through the walls of the incinerator, assuming
5% loss.
4-92
-------
Q = 0.05 AH2
= _ Btu/lb feed
5. Calculate the enthalpy of the combustion products leaving the incinerator.
0.26
-------
WORKSHEET 4-6. PROCEDURE TO ESTIMATE THE MAXIMUM ACHIEVABLE GAS RESIDENCE TIME
AFTER THE DESIRED OPERATING TEMPERATURE HAS BEEN ACHIEVED
1. Identify the following input variables:
Volume of the incinerator chamber, V = ft3
Combustion gas flow rate, q = scfm
Operating temperature, T = °F
2. Calculate the gas flow in actual cubic feet per second at operating
temperature.
/ T + 460 \
I 528 )
acf/s
3. Calculate the maximum achievable gas residence time in the incinerator
after the desired operating temperature has been achieved.
9 = —
max q1
4-94
-------
WORKSHEET 4-7. PROCEDURE TO CALCULATE SUPERFICIAL GAS
VELOCITY AT OPERATING TEMPERATURE
Identify the following input variables:
Gas flow rate at operating temperature, q1 = acf/s
(See Worksheet 4-6)
Cross-sectional area of the incinerator chamber, A = ft2
Calculate:
Superficial gas velocity, v = q'/A
= ft/s
4-95
-------
WORKSHEET 4-8. PROCEDURE TO CALCULATE THE MAXIMUM ACHIEVABLE EXCESS AIR RATE
FOR A ROTARY KILN OPERATING AT A SPECIFIED TEMPERATURE WITH A
SPECIFIED FEED COMPOSITION
1. Identify the following input variables:
From Worksheet 4-4, Step 6
(02)stoich(K) = lb 02/lb kiln feed
From Worksheet 4-4, Step 7
C02(R) = Ib/lb feed
H20(R) = Ib/lb feed
N2(R) = Ib/lb feed
Other major combustion product(s) = Ib/lb feed
From Worksheet 4-4, Step 2
Liquid waste feed fraction, nt = lb liquid/lb waste
Solid waste feed fraction, n2 = lb solid/lb waste
From Worksheet 4-3
Liquid waste heating value, NHVj = Btu/lb
Solid waste heating value, NHV2 = Btu/lb
From proposed operating conditions
Kiln operating temperature, TK = °F
Air preheat temperature, T . = °F
(if applicable)
If auxiliary fuel is to be burned in the kiln along with the wastes
during normal operation, identify the following from Worksheet 4-4:
n,.. = lb fuel/lb waste
HV = Btu/lb fuel
4-96
-------
2. If air preheating is employed, calculate the corresponding enthalpy input
to the kiln. If the combustion air is not preheated, proceed to Step 3:
* 77)(°2>stoich(K) = - BtU/lb £eed
3. Calculate the maximum heat generated in the kiln by combustion of the
wastes or waste/auxiliary fuel mix:
+ n2NHV2 + n
AH2 = - - r— - - — = _ Btu/lb feed
1 nfK
4. Estimate the heat loss through the walls of the kiln, assuming 5% loss:
Q(R) = 0.05 AH2 = _ Btu/lb feed
5. Calculate the enthalpy of the combustion products leaving the kiln.-
0.26 (c02(K) + N2(K) \ (TR - 77) = _ Btu/lb feed
0.49 H20(R) (TK - 77) = _ Btu/lb feed
0th"K(lb-ib)'< S other
-------
WORKSHEET 4-9 PROCEDURE TO CALCULATE EXCESS AIR IN A ROTARY KILN AFTERBURNER
FOR A SPECIFIED AFTERBURNER TEMPERATURE AND OVERALL FEED
COMPOSITION
1. Identify the following input variables:
From Worksheet 4-4, Steps 6 and 12
<°*>stoich ' -
From Worksheet 4-4, Step 15
C02 = _ U>/lb feed
H2o = _ WU* feed
N = Ib/lb feed
Other major combustion product (s) = _ Ib/lb feed
From Worksheet 4-4, Step 14
Afterburner/kiln feed ratio, n^ = _ lb afterburner feed/lb kiln feed
From Worksheet 4-3
Afterburner waste heating value, NHV3 = _ Btu/lb
From proposed operating conditions
Afterburner temperature, T& = _ °F
Air preheat temperature, Tair = _ °F
(if applicable)
If auxiliary fuel is to be burned in the afterburner along with liquid
wastes during normal operation, identify the following from Worksheet 4-4:
n = _ lb fuel/lb afterburner waste feed
HV_ = _ Btu/lb fuel
fA -
From Worksheet 4-8,
AH2/ur. = _ Btu/lb kiln feed
\K.) •^~~-~—~~~
4-98
-------
2. If air preheating is employed, calculate the corresponding enthalpy input
to the kiln and afterburner combined. If the combustion air is not pre-
heated, proceed to Step 3:
AH,' = 1-06 (Tair - 77) [ (02)stoich(K) + <0,).toich(A)] - - Btu/lb feed
AH!1 (1 + EA)
3. Calculate the heat generated in the kiln and afterburner by combustion
of the total waste/auxiliary fuel feed:
NHV3 + nf HV
AH,. . = - : - — — — = _ Btu/lb afterburner feed
* -
Btu/lb feed
nAK
4. Estimate the heat loss through the walls of the kiln and afterburner,
assuming 5% loss:
Q = 0.05 AH2 = _ Btu/lb feed
5. Calculate the enthalpy of the combustion products leaving the afterburner:
0.26 (C02 + N2) (TA - 77) = _ Btu/lb feed
0.49 H20 (TA - 77) = _ Btu/lb feed
( IB-fed) " S other ' - BtU/lb
Other
Btu/lb feed
6. Calculate the enthalpy of excess air leaving the afterburner:
*V = 1.1
-------
WORKSHEET 4-10. PROCEDURE TO ESTIMATE SOLID WASTE
RETENTION TIMES IN ROTARY KILNS
Identify the following input variables:
Kiln length, L = ft
Kiln diameter, D = ft
Slope of kiln, S = ft/ft
Rotation velocity, N = rpm
Calculation:
9 =0.19 (L/D)/SN = min
4-100
-------
WORKSHEET 4-11. PROCEDURE TO CALCULATE AUXILIARY FUEL CAPACITY REQUIREMENTS
FOR STARTUP AT DESIGN AIR FLOW FOR WASTE COMBUSTION
1. Identify the following input data from the proposed operating conditions.
Section 4.3.2, and/or Section 4.3.3.
Auxiliary fuel type
Fuel heating value, NHV = Btu/lb
Desired operating temperature, TQut = °F
Average proposed waste feed rate, mw = Ib/hr
Stoichiometric oxygen requirement for waste,
/o_\ = Ib Oo/lb waste
i02;stoich(w) 2
Proposed excess air rate, EA = %/100
2. Identify the Stoichiometric oxygen requirements and combustion product
yields for the auxiliary fuel from the following table.
Combustion products
yields. Ib/lb fuel
Fuel (02)stoich(f). l*>/lb fuel C02 H20 N2
Residual fuel oil 3.16 3.18 0.92 10.5
(e.g., No. 6)
Distillate fuel oil 3.32 3.20 1.11 11.0
(e.g., No. 2)
Natural gas 3.67 2.54 2.04 12.2
3. Calculate the enthalpy of the fuel combustion gases.
hi = 2>if ^
[0.26(C02 + N2) + 0.49 H20 ] (TQut - 77)
= _ Btu/lb fuel
4. Calculate the heat output from the unit associated with design air flow
for waste combustion.
Ql = 1.12 mw (02)stoich(w) (1 + EA) (Tout - 77)
= _ Btu/hr
4-101
-------
5. Calculate "enthalpy" of air consumed in fuel combustion.
h2 = 1.12 (02)stoich(f) (Tout - 77)
Btu/lb fuel
6. Calculate the heat of fuel combustion, less 5% heat loss through the
refractory walls.
h3 = 0.95 NHVf = Btu/lb fuel
7. Calculate the required auxiliary fuel capacity.
»f • b. * S - h. • ttfuel/hr
8. If necessary for comparison with the reported auxiliary fuel rating,
calculate the required auxiliary fuel capacity in Btu/hr.
Q, = m, NHV, = Btu/hr
4-102
-------
WORKSHEET 4-12. PROCEDURE TO ESTIMATE P ARTICULATE CONCENTRATION AND
EMISSION RATE FROM LIQUID INJECTION INCINERATORS
I. Identify the following input data:
Ash content of waste, ASH = _ wt%
Average waste feed rate, m = _ Ib/hr
Volumetric combustion gas flow rate, q = _ scfm
Volumetric fraction of oxygen in the gas, (02) = _
2. Calculate the particulate emission rate, based on the ash content of the
waste
m = ASH x m = _ Ib/hr
p w -
3. Correct the volumetric combustion gas flow rate to zero percent excess
air.
scfm
qa = q [ 1 - 4.77(02)v ] =
4. Calculate the particulate loading in the gas at zero percent excess
air.
c -
4-103
-------
WORKSHEET 4-13. INTERNAL CONSISTENCY CHECK FOR PROPOSED CONDITIONS
OF GAS VELOCITY, LIQUID TO GAS RATIO, AND PRESSURE
DROP FOR VENTURI SCRUBBERS
1. Identify the following input data:
Q
Proposed liquid to gas ratio, — = gal/1,000 ft3
G
Proposed gas velocity (at the throat), UQ =
Cross-sectional throat area, A = ft
Gas density (downstream of throat), pa = Ib/ft
p may be estimated from the ideal gas law:
n _ M P
pa ~ RT
where M = average molecular weight of gas (normally about 30)
P = absolute pressure (atm)
R = gas constant =0.73 atm ft3/°R Ib mol
T = absolute temperature (°R)
2. Calculate the pressure drop, AP
2 0.133 / \0.78
. in. WG
1270
4-104
-------
WORKSHEET 4-14. PROCEDURE TO CALCULATE THE NUMBER OF PLATES
REQUIRED FOR A SPECIFIED GASEOUS POLLUTANT
REMOVAL EFFICIENCY3
1. Identify the desired removal efficiency for pollutant i.
Ei = _ %/100
2. From Table 4-19 or other sources, identify the average Murphree vapor
phase efficiency for the plate tower
EMV =
%/100
3. Calculate the required number of plates
In (1 - E.)
N = ;
p In (1 •
aThis procedure is only applicable for gaseous pollutants that are highly
soluble or chemically reactive with the scrubbing liquid.
4-105
-------
WORKSHEET 4-15. PROCEDURE TO CALCULATE THE MAXIMUM LIQUID
TO GAS RATIO FOR PLATE TOWERS
1. Identify the inlet temperature to the tower and the tower diameter.
T = °F + 460 = °R
d = ft
2. Identify the volumetric fraction of each major component in the gas.
YC02
YH20
Yother
3. Calculate the average molecular weight of the gas
M =
Ib/lb mol
4. Calculate the gas density
5. Determine the scrubber liquor density
pT = _ lb/ft3
4-106
-------
6. Determine the Souders-Brown constant, K, from Reference 6 or other
sources. (For 24-in. tray spacing, use K = 0.17)
7. Calculate the maximum liquid-to-gas ratio
5
= gal/1,000 ft3
max
4-107
-------
WORKSHEET 4-16. PROCEDURE TO CALCULATE PRESSURE DROP BETWEEN
THE INCINERATOR AND INDUCED DRAFT FAN
1. Identify and/or calculate the following input data relevant to the
combustion gas:
a) From Section 4.3.2,
Approximate waste feed rate, m = Ib/hr
Combustion gas mass flow, CG = Ib/lb waste
CG x m = Ib/hr
Combustion gas volumetric flow, qgtd = scfm
Volumetric fraction of each major component in the gas
yC02
yH20
yo2
yother =
b) Calculate the average molecular weight of the gas
" = 44 yC02 * 18 yH20 + 28 yN2 + 32 y02 + "other yother
= _ Ib/lb mol
2. Calculate the actual gas flow rate and gas density at the entrance to
each gas conditioning or air pollution control device and the fan using
the following equations:
q = q
std
/T°F + 460 \
V 528 )
Pgas = 137 ( T«F " 460 ) '
4-108
-------
Location (inlet) Q. acfm pqas. lb/ft3
Quench tower
Scrubber
Demister
Fan
Other (specify)
Approximate gas temperatures at these locations need to be determined.
3. From manufacturer specifications, estimate the pressure drop across each
gas conditioning device for the gas flow rates calculated in the preceding
step.
Location AP. in.
Quench tower
Scrubber
Demister
Other (specify)
TOTAL
4. For the segments of ductwork entering the aforementioned devices, determine
the inner diameter (D), the cross-sectional area of the duct (Ad), the
cross-sectional area of the device preceding the duct (A ), the length of
straight duct (L ), the radius of curvature of any bends*in the duct
(R), and the gassvelocity through the duct.
If the duct is square, use the length of a side as the equivalent diameter.
If the duct is rectangular, calculate an equivalent diameter by the follow-
ing equation:
D = 2 ab., where a and b are width and depth of the duct.
a + b
Figure 4-15 in Section 4.4.4 shows how radii of curvature can be estimated.
Gas velocities can be calculated by the following equation:
ft/S
Aj, ft2 A_, ft2 AJh L. ft
(inlet duct) D, in.
Quench tower
Scrubber
Demister
Fan
Other (specify)
4-109
-------
5. Calculate the pressure drop across each straight length of ductwork
using Figure 4-13 in Section 4.4.4. and the known diameters of the ducts,
combustion gas mass flow rate, average molecular weight of the gas, and
temperatures at the specified locations.
Figure 4-13 yields pressure drop values per length of straight duct.
These can be converted to total pressure drops by the following
calculation:
Location
(inlet duct) AP. in. HgO
Quench tower
Scrubber
Demister
Fan
Other (specify)
6. Estimate the pressure drop across any bends in the ductwork.
Figure 4-14 in Section 4.4.4 shows L /D values as a function of R/D for
90° bends, e
where L = equivalent length, in.
D = diameter, in.
R = radius of curvature, in.
L /D values can be converted to pressure drops by the following calculation:
AP' = AP -=
where AP1 = pressure drop across the bend in the duct, in. H20
For 45° bends, AP1 is about 65% of that calculated for a 90° bend. For
180° bends, AP1 is about 140% of that calculated for a 90° bend. Thus,
') =0.65Ap.(g()0)
4-110
-------
Location
(inlet duct AP1, in. HgO
Quench tower
Scrubber
Demister
Fan
Other (specify)
TOTAL
7. Estimate the additional pressure drops due to sudden contraction of flow
at the entrance to each duct.
AP1 = .003 K pM_ V2. in. H20
c gas
where AP" = pressure drop due to contraction, in H20
p = gas density, lb/ft3
V = gas velocity, ft/s
K = sudden contraction-loss coefficient
K is a function of the ratio of the duct cross-sectional to the cross-
sectional area of the preceding vessel, Ad/A . Table 4-21 in Section 4.4.4
shows this relationship. P
Location
(inlet duct) AP". in. H90
Quench tower
Scrubber
Demister
Fan
Other (specify)
TOTAL
8. Calculate the total pressure drop across the system by summing the totals
from Steps 3, 5, 6, and 7
*>total = in- H20
4-111
-------
4.6 REFERENCES
1. Kiang, Yen-Hsuing. Total hazardous waste disposal through combustion.
Conshohocken, PA; Trane Thermal Co. Reprinted from Industrial Heating.
December 1977.
2. Santoleri, J. J. Spray nozzle selection. Conshohocken, PA; Trane Ther-
mal Co. Reprinted from Chemical Engineering Progress, 1974 September.
3. FloSonic® supersonic atomization, high efficiency twin fluid atomizers
and systems (manufacturer's brochure). Fairfield, OH; Fluid Kinetics,
Inc. Form No. DX1277-2.
4. Trane thermal waste disposal and recovery (manufacturer's brochure).
Conshohocken, PA; Trane Thermal Co. Bulletin No. 143-A.
5. Hanson, L.; and linger, S. Hazardous material incinerator design criteria.
Cincinnati, OH; U.S. Environmental Protection Agency; 1979 October. 100
p. EPA-600/2-79-198.
6. Perry, R. H. Chemical engineers' handbook, fifth edition. New York,
HcGraw-Hill Book Company, 1973. Section 23.
7. McGraw-Hill encyclopedia of science and technology. Vol. XI. New York,
McGraw-Hill Book Company, 1960. 409-411.
8. Ross, R. D., ed. Industrial waste disposal. New York, Van Nostrand
Reinhold, 1968. 190-239.
9. Brown, R. W. High-temperature non-metallics. Chemical Engineering.
65(8):135-150, 1958 April 21.
10. Sittig, M. Incineration of industrial hazardous wastes and sludges. Park
Ridge, NJ; Noyes Data Corp.; 1979. p. 68.
11. Hanf, E. W.; and MacDonald, J. W. Economic evaluation of wet scrubbers.
Chemical Engineering Progress. 71(83):48-52. 1975 March.
12. Calvert, S. How to choose a particulate scrubber. Chemical Engineering.
84(18):54-68, 1977 August 29.
13. Shannon. L. J.; Gorman, P. G.; and Reichel, M. Particulate pollutant
system study. Vol. II - fine particle emissions. Durham, NC; U.S. Envi-
ronmental Protection Agency; 1971. PB 203 521 (APTD-0744).
14. Wen, C. Y.,- and Uchida, S. Gas absorption by alkaline solutions in a
venturi scrubber. Industrial and Engineering Chemistry, Process Design
and Development. 12(4):437-443. 1973 April.
15. Calvert, S.; Goldschmid, J.; Leith, D.; and Mehta, D. Wet scrubber
system study, Vol. I - scrubbber handbook. Research Triangle Park, NC;
U.S. Environmental Protection Agency; 1972 August. PB 213 016
(EPA-R2-72-118a).
4-112
-------
16. Hesketh. H. E. Fine particle collection efficiency related to pressure
drop, scrubbant and particle properties, and contact mechanism. Journal
of the Air Pollution Control Association. 24(10):939-942, 1974 October.
17. Sherwood. T. K.; and Pigford, R. L. Absorption and extraction, 2nd ed.
New York, McGraw-Hill Book Company, 1952. 278 p.
18. Eckert, J. S.; Foote, E. H.; Rollinson, L. R.; and Waller, L. F. Absorp-
tion process utilizing packed towers. Industrial and Engineering Chemistry.
59(2):41-47, 1967 February.
19. Zenz. F. A. Designing gas-absorption towers. Chemical Engineering.
79(25):120-138, 1972 November 13.
20. Fair, J. R. Sorption processes for gas separation. Chemical Engineering.
75(15):90-110, 1969 July 14.
21. Devitt, T.; Spaile, P.; and Gibbs, L. Population and characteristics of
industrial/commercial boilers in the U.S. Research Triangle Park, NC;
U.S. Environmental Protection Agency,- 1979 August. 431 p.
EPA-600/7-79-178a.
4-113
-------
CHAPTER 5
OVERALL FACILITY DESIGN, OPERATION, AND MONITORING
-------
CONTENTS
5. OVERALL FACILITY DESIGN, OPERATION, AND MONITORING .......... 5-1
5.1 Introduction .......................... 5~1
5.1.1 Purpose
5.1.2 Hazardous Waste Incinerator Facility Design
5.2 Incinerator Facility Site Selection and Operation 5-2
5.2.1 Site Selection Concerns 5-2
5.2.2 Operation of the Facility 5~4
5.2.2.1 Operations Plan 5-4
5.2.2.2 Operations Manual 5~5
5.2.2.3 Emergency Manual or Handbook 5-5
5.2.2.4 Leak Detection and Repair Plan 5-12
5.2.2.5 Hazardous Chemical Spill Handling Plan 5-12
5.2.2.6 Facility Security 5-14
5.2.2.7 Operator Practices and Training 5-14
5.2.2.8 Loss Prevention Program 5-15
5.3 Waste Receiving Area 5"15
5.3.1 Typical Operations and Layouts : • : • 5-16
5.3.2 Laboratory for Waste Verification and/or Characterization 5-17
5.3.3 Liquids Unloading 5"19
5.3.3.1 Safety/Emergency Provisions 5-25
5.3.3.2 Spill and Runoff Containment 5-27
5.3.3.3 Static Electricity Prevention 5-27
5.3.4 Container Unloading j?"29
5.3.5 Bulk Solids Unloading 5"31
5.3.5.1 Mechanical Conveyors 5-31
5.3.5.2 Pneumatic Conveyors 5"32
5.4 Waste Storage Area 5"33
5.4.1 Types of Storage 5"34
5.4.1.1 Liquid Storage jT34
5.4.1.2 Bulk Solids Storage jj'3^
5.4.1.3 Container Storage 5-40
5.4.1.4 Tank Cars 5~40
5.4.2 Segregation of Wastes During Storage
-------
5.4.3 Safety Provisions for Storage Areas 5-41
5.4.3.1 Fire Safety 5-42
5.4.3.2 Spill/Toxicity Safety 5-42
5.5 Waste Blending and/or Processing Before Incineration 5-47
5.5.1 Waste Compatibilities 5-48
5.5.2 Liquid Feed and Blending Equipment 5-49
5.5.3 Pumps and Piping 5-51
5.5.3.1 Positive-Displacement Pumps 5-53
5.5.3.2 Centrifugal Pumps 5-54
5.5.3.3 Pump Emission Control 5-54
5.5.3.4 Pump and Piping Safety 5-56
5.5.4 Valving and Controls 5-60
5.5.5 Valving and Control Safety Consideration 5-61
5.5.5.1 Safety Shutoffs 5-61
5.5.5.2 Gages, Meters, and Gage Glasses 5-63
5.5.5.3 Operating Controls 5-63
5.5.6 Solids Feeding Equipment 5-65
5.5.6.1 Shredders 5-65
5.5.6.2 Explosion Suppression and Safety Considerations
for Shredders 5-66
5.5.6.3 Feeders 5-67
5.5.6.4 Container Feeding Equipment 5-69
5.5.7 Backup/Redundancy Provisions 5-71
5.5.8 Waste Processing Instrumentation 5-71
5.6 Combustion Process Monitoring 5-72
5.6.1 Temperature Monitoring 5-73
5.6.1.1 Metal Tubes 5-76
5.6.1.2 Ceramic Tubes 5-76
5.6.1.3 Metal-Ceramic Tubes 5-77
5.6.2 Oxygen Monitoring 5-77
5.6.3 Gas Flow Measurement 5-77
5.6.3.1 Orifice Plates 5-78
5.6.3.2 Venturi Tubes 5-79
5.6.3.3 Pitot Tubes 5-80
5.6.4 Solid Waste Retention Time and Mixing Characteristics
Information 5-80
5.7 Air Pollution Control Device Inspection and Monitoring 5-80
5.7.1 Wet Scrubbers 5-80
5.7.1.1 Temperature 5-80
5.7.1.2 Liquid and Gas Flows 5-80
5.7.1.3 pH 5-81
-------
5.7.1.4 Pressure Drop 5~83
5.7.1.5 Residue Generation 5-83
5.7.2 Fabric Filters 5"87
5.7.2.1 Temperature 5~87
5.7.2.2 Gas Flow and Pressure Drop 5-87
5.7.2.3 Residue Generation 5-88
5.7.3 Electrostatic Precipitators 5-88
5.7.3.1 Rapping Cycle Practice 5-89
5.7.3.2 Temperature, Resistivity, and Gas Moisture
Effects 5'89
5.7.3.3 Applied Voltage (Power Supply Control) 5-91
5.7.3.4 Gas Flow 5-92
5.7.3.5 Residue Generation Rate and Dust Removal
Capacity 5-92
5.7.3.6 Internal System Pressure 5-92
5.7.4 Mist Eliminators 5-92
5.7.4.1 Temperature 5-93
5.7.4.2 Gas Flow and Pressure Drop 5-93
5.7.4.3 pH Level 5'93
5.7.4.4 Maintenance 5-93
5.8 Scrubber Waste Stream Treatment Inspection and Monitoring. . . . 5-93
5.8.1 Flow Measurement and Monitoring 5-93
5.8.2 Flow Control 5-94
5.8.3 pH Monitoring 5-94
5.8.4 pH Control Systems 5'95
5.8.4.1 On-Off Controller 5-95
5.8.4.2 Proportional Controller 5-95
5.8.4.3 Resetting Derivative Controller 5-95
5.8.4.4 Flow Proportional Controller 5-95
5.8.5 Scrubber Solution pH Control 5-95
5.9 Continuous Monitoring Instrumentation for Gaseous Components . . 5-97
5.9.1 Available Systems 5"97
5.9.1.1 Extractive Systems 5-99
5.9.1.2 In-Situ Monitoring Systems 5-103
5.9.2 Analyzers 5"104
5.9.2.1 NDIR Analyzers 5-104
5.9.2.2 Nondispersive Ultriviolet Analyzers (NDUV) . . . 5-105
5.9.2.3 Polarographic Analyzers !"}"«!?
5.9.2.4 Electrocatalytic Oxygen Analyzers 5-106
5.9.2.5 Paramagnetic Oxygen Analyzers 5-107
-------
5.10 Plant Condition Monitoring Systems 5-110
5.10.1 Machine Vibratory Signature Analysis 5-110
5.10.2 High Frequency Acoustic Emission Analysis 5-110
5.11 Scrubber/Quench Water and Ash Handling 5-111
5.11.1 Description of Potential Incinerator Wastes 5-111
5.11.1.1 Quench Water 5-111
5.11.1.2 Scrubber Effluents 5-116
5.11.1.3 Ash 5'119
5.11.2 Sampling and Analysis of Quench/Scrubber Water and Ash. 5-120
5.11.3 Handling of Quench/Scrubber Wastewater 5-121
5.11.4 Handling of Ash 5-123
5.12 Fugitive Emissions 5-123
5.12.1 Significance of Observed Emissions 5-123
5.12.2 Fugitive Emission Control 5-126
5.12.3 Fugitive Emission Measurement Devices and Methodology . 5-127
5.12.3.1 Area Monitoring 5-127
5.12.3.2 Fixed-Point Monitoring 5-127
5.12.3.3 Source Monitoring 5-127
5.12.3.4 Current Instrumentation 5-127
5.13 Materials of Construction 5-128
5.13.1 Metals 5'129
5.13.2 Nonmetallics 5-132
5.14 Miscellaneous Concerns 5-136
5.14.1 Personnel Health and Safety 5-136
5.14.2 Facility Housekeeping 5-137
5.14.3 Maintenance 5-138
5.14.4 Firefighting/Emergency Personnel and Equipment 5-140
5.14.5 Stormwater Diversion 5-141
5.15 Technical Assistance 5-142
5.16 References 5-142
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CHAPTER 5
OVERALL FACILITY DESIGN, OPERATION, AND MONITORING
5.1 INTRODUCTION
Incineration is one controlled combustion process used in the ultimate dispos-
al of unusable hazardous wastes that result from industrial and chemical
manufacture. Careful selection of equipment and processes for the incinera-
tion of chemical wastes is essential to ensure that the basic obligations of
safe handling and proper ultimate disposal are met in a satisfactory manner.
In addition to fulfilling social obligations, an effective system will satisfy
regulatory needs with minimum, adverse community reaction.
Prior to incineration, the handling, storage, and feeding of hazardous wastes
require special care to ensure safety and reduce exposure. During incinera-
tion and while the facility operates, certain parameters must be monitored by
the operators to assure that proper conditions are maintained in day-to-day
operation.
Although the problems are substantially reduced, incineration of hazardous
waste materials alone does not eliminate all of the disposal problems associ-
ated with hazardous waste. Most incinerators produce combustion products that
must be properly removed prior to discharging gas products to the environment.
These products include ash or inert residues from such things as silica oxides
and/or metals. Captured gas products, such as HCl, when reacted with caustic
solutions in the scrubber, can also produce dissolved and suspended solids.
These solutions from the quench process and scrubber reactions must be care-
fully disposed of to ensure the entire sequence of combustion is safe. When-
ever these wastes are of a nonhazardous nature, standard procedures can be
used for their treatment and ultimate disposal. However, in some cases the
secondary wastes can be hazardous themselves and require special handling.
5.1.1 Purpose
The purpose of this chapter is to provide the permit writer with engineering
back-up information to supplement the guidance criteria necessary to judge the
capability of the overall incineration facility to technically and practically
process and monitor hazardous wastes safely and effectively.
This chapter discusses overall facility layouts, requirements common to all
facilities, site and combustor specific requirements, material and process
flows, waste receiving procedures, waste and other storage, material handling
equipment, emergency and safety procedures and provisions, personnel safety,
monitoring for the incineration process itself, monitoring of the air
5-1
-------
pollution control system, monitoring of waste handling and treatment systems,
monitoring and controlling parts of the overall facility that may become
fugitive emission sources, proper handling and disposal of quench/scrubber
water and ash, and sampling and analysis of wastewaters and ash.
5.1.2 Hazardous Waste Incinerator Facility Design
The overall facility design of hazardous waste incinerators is significantly
influenced by the category of waste involved; i.e., solids, liquids, or sludges.
The systematic approach to facility design, therefore, requires investigation
of the composition of each class of waste to define the equipment and operating
procedures for each of the following elements:
1. Safety (toxicity, fire explosion)
2. Transportation and unloading
3. Segregation of wastes during storage
4. Storage
5. Handling and feeding
6. Monitoring
7. Fugitive emission control
8. Scrubber/quench water treatment
9. Residue handling and disposal
10. Secondary problems (e.g., stream pollution, runoff, ground-water
contamination).
The overall success of an incinerator facility depends upon the successful
integration of storage, feeding, and firing equipment; often these are areas
which do not receive as much attention as is necessary. In the case of hazard-
ous waste incineration it is crucial that these areas require special attention.
Figure 5-1 is a block diagram of a typical incinerator facility layout. In an
overall facility evaluation, the key areas are the facilities and equipment
before and after the combustor; i.e., waste receiving, waste storage, waste
blending, transfer between these areas, equipment feeding waste to the incinerator,
handling and treatment of quench and scrubber waters, and ash disposal.
5.2 INCINERATOR FACILITY SITE SELECTION AND OPERATION
5.2.1 Site Selection Concerns
The Guidance Manual for Location Standards contains guidance for complying
with general (i.e., applicable to all facilities) location standards U264.18.
Flood plains, holocene faults, and endangered and threatened species are
discussed.
The selection of a site for a hazardous waste incineration facility is a
phased decision process which has occurred prior to making a permit applica-
tion. Site screening is the process of identifying and evaluating a parcel of
land for its suitability as a hazardous waste disposal site. Specific site-
screening criteria which the permit applicant has addressed include geologic,
hydrogeologic, topographic, economic, social, and political aspects. While
many sites may exist which meet technical, economic, and ecological criteria,
5-2
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INCOMING WASTE
TRUCK TANKER
RAIL TANK CAR
TRUCK TRAILER-HOPPER
RAIL HOPPER CAR
SEMI-TRAILER
METAL DRUMS
FIBER DRUMS
TON CONTAINERS
PIPELINE (RARE)
BARGE(RARE)
SECURITY _
ACCESS ^^
SECURITY FENCE
Figure 5-1. Typical incinerator facility layout.
public acceptance or rejection may ultimately decide the fate of the facility
ID.
The main geological constraints that can render a site unsuitable for a hazard-
ous waste incinerator facility are historical or predicted seismic activity,
landslide potential, soil slump of solifluction, and volcanic or hot spring
activities.
The main topographic constraints are susceptibility to flooding, erosion, and
offsite drainage runoff. The site will need sufficient area for the construc-
tion of a runoff-holding pond (or diversion to an existing holding pond) to
retain surface runoff which may contain hazardous substances in solution. Be-
cause of the holding pond and flood protection criteria, siting in flood
plains is not normally acceptable.
The primary climatic features which can adversely affect an incineration site
are the amount of annual or seasonal precipitation and incidence of severe
storms. Copious precipitation will cause surface runoff and water infiltra-
tion through the soil. Runoff, that amount of rainfall that does not infil-
trate the soil, depends on such factors as the intensity and duration of the
precipitation, the soil moisture content, vegetation cover, permeability of
the soil, and slope of the site. Normally, the runoff from a 10-year storm
(recurrence interval of only once in 10 years) or annual spring thaw, which-
ever is greater, is containable by the site's natural topography. If not,
berms, dikes, and other runoff control measures must be constructed to modify
the site.
5-3
-------
Ecological site features are those elements determined through earlier studies
and environmental impact statements (EIS) which determine whether ecosystems at
the site are in a delicate balance. Whether a site is a habitat for rare and
endangered species; or used seasonally by migratory wildlife is also a factor
determined for final site selection.
Cultural site features are those elements that are a direct result of human
activities which modify and affect the site's desirability as a hazardous
waste incineration facility—access, land-use, and aesthetics. Land areas
zoned for nonresidential uses and adequate buffer zones are generally preferred
for siting a hazardous waste management facility. The site ideally needs to
contain sufficient land area to provide a concentric ring of unoccupied space
as a buffer zone between active storage, treatment, and disposal areas, and
the nearest area of human activity. Vegetation, topography, distance, and
artificial barriers are all potential means to screen facility activities
from line-of-sight observations from commercial, residential, or recreational
areas.
One of the most difficult problems faced by a hazardous waste incineration
facility applicant has been that of gaining public approval from a community
for construction of the facility. No matter how thoroughly the above
parameters have been examined in the facility site selection, public accept-
ance or rejection probably decides the fate of the facility. Public aware-
ness of the planned facility, early planning input, and active participation
by political leaders, public officials, environmental groups, as well as
other public interest groups and adjacent industry have led to successful
facility sitings in the past.
5.2.2 Operation of the Facility
Preplanning of the proper operation of a hazardous waste incineration facility
is necessary to protect and prevent adverse effects of the facility on the
public health or to the environment. Proper facility operation, on a day-to-
day basis, includes plans and manuals of operation for handling wastes, safety
at the site, monitoring of operating parameters, monitoring to assure protec-
tion of the environment, and operator training. These plans are developed
within the operating company (and corporate structure) and are done in cooper-
ation with other neighboring or similar organizations and with governmental
agencies. It may not always be possible for all of them to fully cooperate or
participate, but through planned action each organization is made aware of
certain available assistances.
5.2.2.1 Operations Plan—
An operations plan includes the following:
(1) Classification of wastes to be handled and estimated quantities
(2) Methods and processes utilized
(a) Facility capacity
(b) Detailed description of each process
5-4
-------
(3) Storage and disposal procedures
(a) Plans for receipt, checking, processing, segregating
incompatible wastes, and odor control
(b) Life of facility based on projected use
(4) Monitoring Procedures
(a) Monitoring of incinerator operating parameters
(b) Monitoring and recording of incoming wastes
(c) Leachate control and groundwater monitoring
(d) Security system
(e) System for monitoring water and air pollution affecting area
outside the site
(f) Air pollution control device monitoring
(5) Administrative Procedures
(a) Hours of operation/day and days/week
(b) Security procedures including entry control, hours manned,
lighting, and other procedures to prevent unauthorized entry
(c) Procedures planned and equipment available in case of break-
downs, inclement weather, or other abnormal conditions.
(d) Description of recordkeeping procedures, types of records to be
kept, and use of records by management to control the
operation.
(e) List of general qualifications of key operating personnel
(f) Maintenance and inspection schedules
5.2.2.2 Operations Manual— . .
Once in operation, the incinerator facility will maintain operation guides or
manuals, covering the routine workings of the plant. An operations guide can
(1) A scaled engineering drawing, pictorial flow diagram, or scale model
of the plant, showing all major components by name and function.
(2) A set of formal drawings at the plant for reference by operational
and maintenance personnel
(3) Equipment manuals
(4) Equipment catalogs
(5) Spare parts lists .
(6) Job or task functions for each assignment during a typical shift
5.2.2.3 Emergency Manual or Handbook— .
An emergency manual or handbook is prepared which specifies the plan-of-action
for any type of emergency the incinerator facility may reasonably expect to
encounter. These include weather extremes (severe cold, heavy snowfall, hail
damage, hurricances, tornadoes, high winds, or lightning damage), floods
earthquakes, power outages, bomb scares, fires and explosion, and spills (See
Section 5.2.2.5). The typical remedial actions for emergency situations
presented in Table 5-1 cover many of the items that can be included in the
5-5
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TABLE 5-1. HAZARDOUS WASTE INCINERATOR MALFUNCTIONS AND REMEDIAL OR EMERGENCY RESPONSES
No.
Malfunction
Type a
incinerator
Malfunction
indication
Response
Ul
Partial or complete stop-
page of liquid waste feed
delivery to all liquid
burners
L
C
Partial or complete stop-
page of liquid waste to
only one burner
Partial or complete stop-
page of solid wastes feed
to rotary kiln
"Puffing", or sudden oc-
currence of fugitive
emissions from RK due to
thermal instability or
excessive feed rate of
wastes to RD, or failure
of seals
L
C
RK
C
RK
C
(a) Flowmeter reading
out of specified
range
(b) Pressure build-up in
feed lines
(c) Change in combustion
zone temperature
(d) Feed pump failure,
zero amps
As in (a), (b) and (c),
above
(a) Drop in RK combustion
temperature
(b) Power loss in waste
feed conveyor or
other feed system
(a) Pressure surge in
kiln (rapid change in
manometer level)
(b) Visible emission from
air seals at either
end of kiln
Halt waste feed, start
trouble-shooting and
maintenance in affected
system. Reinitiate or
increase auxiliary fuel
feed to maintain combus-
tion zone temperatures;
continue operation of air
pollution control devices
(APCD)
Halt waste feed to
affected burner only
As in 1, above
(a) Halt feeding of any
solid waste to kiln
for 10-30 min, but
continue combustion
(b) Evacuate unneeded
personnel from imme-
diate vicinity of
kiln
(c) Reevaluate waste
prior to further
incineration
-------
TABLE 5-1 (continued)
I
-J
Type Malfunction
No Malfunction incinerator3 indication
5 Failure of forced air L (a) Flowmeter reading for
supply to liquid waste RK air supply off scale
feed or fuel burners C (b) Automatic flame
detector alarm
activated
(c) Zero amps or exces-
sive current draw on
blower motor (s)
6 Combustion temperature L (a) Temperature
too high RK indicator (s) at
C instrument control
panel
(b) Annunciator or other
alarm sounded
Response
(a) Halt waste and fuel
feed immediately
(b) Start trouble shoot-
ing immediately and
restart as soon as
possible
(c) Continue operation of
APCD's but reduce air
flow at induced draft
fan by "damping"
accessory
(a) Check fuel or waste
feed flow rates; re-
duce if necessary
(b) Check temperature
sensors
(c) Check other indica-
tors in combustor, if
multiple sensors used
(d) Automatic or manual
activation of combus-
tion chamber vent
(sometimes called an
"emergency stack
cap")
-------
TABLE 5-1 (continued)
No Malfunction
7 Combustion temperature
too low
Type Malfunction
incinerator indication
L (a) - as above
RK (b) - as above
C
Response
(a) Check other indica-
tors in combustor, if
multiple sensors are
used
(b) Check fuel or waste
feed flow rates; in-
crease if necessary
(c) Check sensor accuracy
8 Sudden loss of integrity
of refractory lining
L
RK
C
i
CO
Excess opacity of stack
plume
L
RK
C
(a) Sudden loud noise
(b) Partial stoppage of
air drawn into com-
bustor, resulting in
decreasing combustion
temperatures, in-
creased particulate
emissions, and devel-
opment of hot spots
on external of com-
bustor shell
Visual, or instrument
opacity readings which
are above maximum allow-
able operating point
Shut down facility as
quickly as possible
(a) Check combustion con-
conditions, especial-
ly temperatures 02
(excess air) and CO
monitor
(b) Check APCD operation
(c) Check nature and feed
rates of wastes being
burned
(d) Check ESP rapping in-
terval, cycle dura-
tion and intensity
-------
TABLE 5-1 (continued)
No.
10
Malfunction
Type £
incinerator
11
CO in exhaust gas in
excess of 100 ppm, or in
excess of normal CO
values
Indication of or actual
failure of Induced Draft
Fan
L
RK
C
Malfunction
indication
CO indicator
(a) Motor overheating
(b) Excessive or zero
current (amps)
(c) Total stoppage of fan
(d) Ap drop across blower
inlet and outlet
Response
Check and adjust combus-
tion conditions, espe-
cially temperature and
excess air (03 in stack
gas), and adjust
accordingly
(a) Switch to standby
fan, if available
(b) If two induced draft
fans are used in se-
ries, reduce opera-
tional levels immedi-
ately, stop the fail-
ing unit, and operate
at reduced rate on
one fan only, until
maintenance can be
completed
(c) If there is only one
fan, and the fan
failure appears seri-
ous, shift into an
emergency shutdown
mode for entire
incinerator
-------
TABLE 5-1 (continued)
Malfunction
Type
incinerator
Malfunction
indication
Response
12
Increase in gas tempera-
ture after quench zone,
affecting scrubber
operation
L
RK
C
13
Partial or complete stop-
page of water or caustic
solution to scrubber(s)
L
RK
Ul
i
(a) Partial or total loss
of water supply to
quench zone
(b) Increase of combus-
tion temperatures
(a) Decrease in Ap across
scrubber, as indica-
ted by manometers, or
other instruments
(b) Zero or increased
amps on water or
solution pumps
(c) Flowmeter readings
out of specified
range
(d) Large increase in
acid components in
stack gas as detected
by NDIR or other type
instruments
(a) Check water flow to
quench zone. Prepare
for limited operation
rate until water sup-
ply is restored
(b) Check combustion con-
ditions, especially
temperature
(a) Halt waste feed,
start troubleshooting
and maintenance in
affected system
(b) Start up redundant
pumps, if available
(c) Check recycle water
or solution tank
levels
(d) If using alkaline
solution, switch to
water supply if
available
(e) Check for deposition
of solids from recy-
cled liquors in pump
lines
(f) Use emergency (stand-
by) water supply
which will feed water
by gravity until the
whole system can be
shutdown
-------
TABLE 5-1 (continued)
No.
14
15
16
Malfunction
Type
incinerator'
Deposition of solids in
scrubber from recycled
wastes or caustic solu-
tion, or from excess
solids emissions from
combustor
pH of recycled scrubber
liquor not in spec
Failure of demister
operation
L
RK
C
L
RK
C
L
RK
C
Malfunction
indication
(a) Buildup of Ap across*
scrubber as indicated
by manometers or
other instruments.
(b) Increased hold-up of
liquor in packed or
tray towers, up to
and including flooded
condition. This can
also be detected by
liquid level
indicators.
(a) Continuous, or spot-
checking pH indicator
shows actual pH to be
outside of desired
operating range
(d) Drop in scrubber ef-
ficiency with excess
acid gas in stack gas
Increased Ap, as measured
by manometer, due to
solids accumulation in
demister element
This requires a shutdown
to clean out the tower
and internals. The shut-
down can be scheduled if
the deposit buildup is
gradual and is monitored.
(a) Check for adequate
supply and metering
of alkaline agent
(b) Check accuracy of pH
meter and alkaline
solution metering
pump associated with
recycling of scrubber
liquor
Back-wash element
L = Liquid injection; RK = Rotary kiln; C = Combination liquid injection and rotary kiln.
-------
emergency handbook, but other items may be needed as dictated by the anticipated
emergencies and the available resources.
5.2.2.4 Leak Detection and Repair Plan—
Any facility that processes hazardous air pollutants as described under Section
112 of the Clean Air Act must develop a Leak Detection and Repair Plan (LDRP)
to aid in reducing fugitive emissions [2]. The LDRP must be certified by the
owner of the facility as meeting the fugitive emission criteria established by
the EPA under the Clean Air Act. The plan is to be reviewed and updated, as
required, once every three years, or within 90 days of a major modification at
the facility. At the minimum, the LDRP:
(1) Develops a schedule and recordkeeping program for routine
surveillance and/or monitoring of fugitive emissions.
(2) Establishs a written plan for detection and repair of leaks, and a
reasonable schedule for repair.
(3) Provides a written plan for sampling procedures, housekeeping (e.g.,
small spill cleanup) and onsite waste handling.
(4) Develops recordkeeping procedures for all aspects of the LDRP and
saves these records for one year.
(5) Establishes a written plan for specifying sufficient personnel to
fulfill the LDRP, and provides a training program with a written
manual.
5.2.2.5 Hazardous Chemical Spill Handling Plan—
Most plants' safety, disaster or operating plans and manuals do not fulfill
the requirement for a spill-handling plan. The key to adequate spill-handling
is decision-making. None of the above manuals or procedures supply the infor-
mation required to make the decisions necessary to cope with the spill of a
hazardous material. Thus, a chemical-spill-handling plan will fill an information
need, but will not program decisions.
In a spill-handling plan, the decisions that must be made in a spill incident
are defined. First, the plant or plant superintendent must accept the fact
that a spill has occurred, based on information from his monitoring systems.
The most immediate steps are those aimed at the protection of human life. If
the information obtained about the location and nature of the leak/spill shows
that the threat to life is "immediate and great," the decision should be to
"shut down - all persons immediately take cover." Otherwise, the decision
should be to "cleanup the area."
The "immediate cover" for persons is a spill response usually described by the
plant disaster/emergency plan, whereas the protection of employees during the
"cleanup the area" procedure is ordinarily contained in a safety plan. It is
the lack of information between these two extremes that the spill-response
plan fills.
5-12
-------
Once a spill-response leader has been chosen, the decision-making process
continues toward containment actions and disposition procedures. Figure 5-2
diagrams the decision-making process and information needed in a spill-
handling situation, as well as the requirements for improving the spill
response.
A spill-handling plan is written as an easy-to-consult document for decision-
making, and includes:
(1) Monitoring all possible spills of materials
INFORMATION REQUIREMENTS
SPILL-MONITORING
INFORMATION
DECISION PROCESS
PLANT-EQUIPMENT CONTENTS
AND MATERIAL-HAZARD
INFORMATION
SPILL-RESPONSE CHAIN-
OF-COMMANO INFORMATION
EQUIPMENT AVAILABLILITY
AND MATERIAL-HAZARD
INFORMATION
IS THERE A SPILL?
IS IT AN
IMMEDIATE
THREAT TO LIFE ?
IS
THE LEADER
AVAILABLE?
WHAT CONTAINMENT
ACTION SHOULD
TAKEN?
JWHAT DEPOSTION
tCnON SHOULD
TAKEN?
IMPROVEMENTS
REQUIREMENTS
REVIEW AND/OR
IMPROVE SPILL
MONITORING
REVIEW AND/OR USE
DISASTER PLAN
REVIEW SPILL RESPONSE
CHAIN OF COMMAND
IMPROVE
CONTAINMENT
DEVICES
IMPROVE
DEPOSITION
CAPABILITY
JUUU
ACTION
Figure 5-2. Spill-response diagram illustrating the interrelating information
available, decisions to be taken, and improvements needed [3].
5-13
-------
(2) Identifying of all plant equipment and other contents it may
have (can be separated into convenient process groupings or modules)
(3) Describing hazards of materials that would comprise potential spills
(4) Designating the chain of command during a spill incident
(5) Specifying equipment available for containment, and disposition
alternatives in response to a spill.
Every spill-handling plan has seven relatively independent parts that fulfill
the five needs mentioned above. These parts are kept as autonomous as
possible to facilitate the upgrading of each one. The seven parts are:
(1) List of contacts for spill emergencies, including plant/shift
individuals, safety personnel, environmental control personnel, and
government agency contacts, with home and office telephone numbers.
(2) Process flowsheets, showing primarily those pieces of equipment
containing sufficient volume of material to constitute a potential
spill problem.
(3) Site map.
(4) Chemical-effects list for all hazardous materials located within
the boundaries of the plant.
(5) Monitoring checklist, consisting of a matrix indicating how equipment
is monitored for potential spills.
(6) Containment alternatives matrix, describing the series of contain-
ments that occur in sequential order for various process equipment.
(7) Chemical-disposition alternatives, including a listing of equipment
that are considered alternative places of material disposition for
recovery, treatment, ultimate disposal.
5.2.2.6 Facility Security
Incineration facility security is management's responsibility. Basic security
problems are protection of property and controlling access to the facility.
Security procedures for hazardous waste disposal facilities are described in
the Federal Register, Vol. 45. No. 98, Part 265 - Interim Status Standards for
Owners and Operators of Hazardous Waste Treatment, Storage, and Disposal
Facilities, Subpart B - General Facility Standards, 265.14 Security, pg.
33235, May 19, 1980.
5.2.2.7 Operator Practices and Training
Operator practices and training of personnel ensure the smooth, efficient
running of a hazardous waste incineration facility. Some of the areas covered
under practice and training include:
5-14
-------
(1) Selection of personnel, pre-employment physicals, periodic
examinations
(2) Training; e.g., supervisory, operator, emergency
(3) Operating manual use; e.g., development of the manual, process
description, material specifications, safety considerations
(4) Instruction of personnel
(5) Start-up and shut-down procedures; e.g., problems of start-up,
normal shut-down, emergency shut-down
(6) Maintenance and inspection
(7) Preparation for emergencies; e.g., recognition, alarms, simulated
emergencies, disaster drills
Operator training procedures and rules are described in the Federal Register
(as cited in Section 5.2.2.6), 265.16 - Personnel Training.
5.2.2.8 Loss Prevention Program
A loss prevention program embodies many of the facets of an emergency handbook,
operations manual, and personnel training. Usually, loss prevention
encompasses a whole facility concept and can include other concerns such as:
(1) Accident prevention
(2) Industrial Health and Hygiene
(3) Environmental Control
(4) Fires and explosions
(5) Fire prevention measures
(6) Explosion prevention measures
5.3 WASTE RECEIVING AREA
The type and nature of hazardous waste received at an incinerator facility
will dictate the design and equipment of the waste receiving area. The
physical types of hazardous waste which may be received are:
(1) Liquid
(2) Containerized materials, liquid and solids
(3) Dry solid materials
(4) Wet solid materials
(a) Pumpable
(b) Nonpumpable.
The types of receiving equipment for unloading can be divided into three
general areas:
(1) Pumpable liquid transfer
(2) Container transfer
(3) Bulk solids transfer.
Figure 5-3 shows a generalized flow diagram of handling procedures for incin-
eration of hazardous wastes. Careful consideration must be given to the
layout, safety, and recordkeeping arrangements of the waste receiving area.
Unloading material offers one of the greatest spill or toxic exposure
5-15
-------
IN-PUNT AUTHORIZED
WASTE HAULAGE
1 1
INSPECTION INSPECTION
CHECK CHOC
1
PUWPABLE NONPUMPAllt
ORUMMID
BULK DRUMMED
DRUM
[— — STORAGE • •
1 AREA
PUMPED
FROM DRUMS DRUM
STORAGE
TANK
BULK
SOLID
FCEOER «""«
....« ciiDfnr
DRUM CHAMBER
AUXILIARY ,. WASH 1
FUa BLEN
DING
CR
GAS
WASHING '
INCINERATOR
STACK
Figure 5-3.
Flow diagram showing handling procedures
for incineration of hazardous wastes.
potentials at a hazardous waste facility. For recordkeeping, the waste
receiving area poses the first interface with the transporter and manifest
system.
5.3.1 Typical Operations and Layouts
A detailed flow sheet is a useful guide in laying out receiving areas, partic-
ularly those handling hazardous materials. The nature of the materials and
handling procedures can be studied and provisions made to eliminate or control
hazards.
Access to the incinerator facility will most likely be by truck or rail. (An
inspection procedure will be required for all incoming waste.) Figure 5-4
illustrates a receiving area layout of a facility designed to accommodate both
forms of transport. Most receiving areas for liquids will consist of a dock-
ing area, pumphouse. and storage facilities. For solid materials the pump-
house is replaced with mechanical or pneumatic conveyor devices. For receipt
of containers, a suitable docking area with conveyors and inspection appropri-
ate to the hazardous nature of the containers is necessary. Later sections
describe
in greater detail some of the equipment, handling procedures, and safety re-
quirements for each form of hazardous waste received.
5-16
-------
_
R.R. SIDING
MHIIIIIIH
TANK CAR TRUCK TANKER
UNLOADING STATIONS UNLOADING STATIONS
o
o o
o o
O STORAGE
AREAS
O
n
D
D
PUMP
HOUSE
n n
D D
D n
ROADWAY
Figure 5-4. Layout for liquid receiving area.
5.3.2 Laboratory for Waste Verification and/or Characterization
Analytical data should be made available for all wastes to be incinerated
The physical and chemical properties and the combustion characteristics of
each chemical waste or general classification of wastes, will be determined
before incineration. Only after such analysis can successful waste disposal
be carried out safely and without violation of air or water pollution
regulations as set forth by state and federal agencies.
A minimal but complete laboratory facility requires a working area,
office facilities, of about 2,400 sq ft. Provisions are made for air, water,
III and electricity, preferably both AC and DC. The Iab°rato7af«^r^^a^-r
eludes benches, sinks, fume hood, shelving, glassware racks and a refrigerator.
Good lighting and air-conditioning are also important. Identification of
laboratory equipment needed for analyses of chemical wastes follows. Specific
requirements depend on the types of wastes to be processed and type of inciner-
ator used. If the equipment for sophisticated analytical methods is not
available in-house, the analyses can be performed by commercial analytical
laboratories.
(1) Typical laboratory equipment to determine physical properties:
(a) Specific gravity balance - specific gravity of liquids.
(b) Brookfield viscosimeter - viscosity measurement of liquids and
sludges.
(c) Imhoff cones and centrifuge with graduated tubes -measurement
of percent solids by volume.
(d) Sieving machine for screen analysis (to 100 micron) and HIAC
particle counter (100-5 micron) - particle size measurement.
5-17
-------
(e) Cleveland open cup flash point tester - flash and fire point
determinations.
(f) Oven and balances - percent solids and moisture by weight.
(g) Gas chromatograph-mass spectrometry and infrared apparatus to
identify organic substances which may be toxic.
(h) Differential thermal analyzer - explosion characteristics and
fusion temperature.
(i) Juno meter or equivalent - sensitive to alpha, beta and gamma
rays for radioactivity.
(2) Laboratory equipment to determine chemical properties.
(a) Muffle furnace, oven, balances - for percent ash by weight.
(b) Orsat, fyrite techniques for flue gas analyses to provide data
for excess air calculations.
(c) pH meter and automatic titrator - acidity and alkalinity
measurement.
(d) Emission spectrograph for concentration and presence of metals.
(e) Atomic absorption spectrometer for concentration of metals and
elements.
(f) Optical microscope for particulate characterization down to the
sub-micron size. Electron microscope may be required for some
sub-micron determinations.
(3) Laboratory equipment to determine combustion properties:
(a) Calorimeter for heating value and combustibility.
(b) Orsat (previously listed ) for C02, CO, 02, H2 and N2 analysis.
(c) Flue gas analyzer (previously listed) for analysis at various
excess air rates.
(d) Mass spectrometer (previously listed) for hazardous products of
combustion.
Reliable, bench-scale, chemical incineration equipment is generally unavail-
able. The present practice appears to follow the line of waste characteriza-
tion, physical, chemical and combustibility analysis followed by a test burn
in pilot or plant scale equipment.
5-18
-------
5.3.3 Liquids Unloading
Liquids will arrive in bulk in tank cars or tank trucks by n,ns
rail. Standard rail tank cars vary in capacity from 6,000 " 2?'°?° £^™S
and tank trucks carry up to 10.000 gallons. Figures 5-5 and 5-6 illustrate
typical tank cars with parts and nomenclature identified.
The unloading stations are not normally located near important buildings or
facilities. The site is arranged so that escaping liquid will flow to a safe
location by utilizing the natural grade or by providing diversionary dikes or
drains. (For more information, see Section 5.3.3.1). When P°«ible, 50 feet
or more of clear space is provided between unloading stations and buildings.
Hazardous liquids and "pumpable" materials are transferred through piping by
pump gravitfflow, or compressed-gas displacement. Pumping systems are most
Sonly used and have an inherent safety advantage in that they can easily be
arranged so that the flow of liquid ceases when the pump is stopped. Either
dlrec?-displacement or centrifugal pumps can be purchased in a wide variety of
capacities suitable for a wide range of liquids.
The safest method of unloading tank cars or trucks is through the top by means
of a pump, as shown in Figures 5-7 and 5-8, which also illustrate Provisions
for grounding and bonding to prevent static electricity discharges. Many tank
cars are equipped with permanent unloading connections in the dome. For cars
not so equipped, special covers are available to replace the dome cover during
^loading. Botiom unloading, unloading by siphoning, or unloading by air
£essure9is undesirable, since accidental movement of the *f * "'i*'""* om
unloading may result in the escape of the entire contents of the car. Bottom
^loading may be tolerated under favorable conditions if a remote control or a
neat-actuated automatic shutoff is provided at the tank car connection.
Tank trucks are usually unloaded from the bottom by gravity or by pumps
mounted on the vehicle. These methods are considered acceptable.
For the best methods when transferring liquid wastes:
(1) Positive-displacement pumps are preferred
(2) Centrifugal pumps are suitable for flammable-liquid service but
cannot be used as shutoffs.
Positive-displacement pumps are preferred because, unlike centrifugal pumps,
they afford a reasonably tight shutoff and prevent siphoning when not in
operation A relief valve is provided downstream of P°sit^:dlsP^«men'
pumps, of sufficient capacity to prevent excess pressure in the system The
Velief-valve discharge is then piped back to the supply source or to the
suction side of the pump. With liquids having closed-cup flash points of OF
or lower? tnereliefPvalve should be piped to the storage tank; otherwise the
churning action of the pump might cause dangerous overheating.
Centrifugal pumps are suitable for flammable-liquid service but cannot be used
as shutoffs, since they usually must take suction under a head. Submerged or
5-19
-------
WALKWAY
LADDER
HOSE TUBE
FENDERS
U1
I
to
O
LIGHT BOX
CONNECTION
BOX
UPPER COUPLER
SAND SHOES
SUPPORTS
Figure 5-5. Typical tank trailer (car) with parts identified (4].
-------
A. CAR BRAKE
B. WHEEL BLOCK
C. IDENTIFICATION NUMBER
0. CAR SEAL
E. SAFETY VALVE
F. DOME COVER
G. OUTLET LEG VALVE
H. OUTLET LEG CAP
J. DRAIN PAN
K. OUTLET NOZZEL
L. "FLAMMABLE" CARD
Figure 5-6. Typical tank car with parts identified [5].
5.
6.
7.
8.
9.
10.
11.
BONDING WIRE ATTACHED WITH GROUND CLAMP
RELIEF-VALVE BYPASS
EXPLOSIONPROOF MOTOR
INSULATED FLEXIBLE GROUNDING CABLE ATTACHED
TO TANK CAR WITH GROUND CLAMP; NOT SMALLER
THAN NUMBER 4
NO. 4 STRANDED CABLE SECURED TO PLATFORM
COLUMN
NONFERROUS TUBE
SAFETY-DOME COVER
GROUND SLOPING AWAY FRON IMPORTANT FACILITIES
BARE-COPPER CONDUCTOR
GROUND ROD DRIVEN TO PERMANENT MOISTURE
LEVEL
WATER MAIN. IF AVAILABLE
Figure 5-7. Tank car unloading station [6]
5-21
-------
DOWNSPOUT SHOULD BOOM
TO NEAR BOTTOM OF TANK
WHEN LOADING.
PLACE PIPE CLAMP ON
EVERY PIPE t CONNED
TO COMMON GROUND
BARE STRANDED WIRE
WEIGHT
CONNECTION IS TO BE MADE -
MKME MANHOLE IS OPENED
TOR USE ON TRUCKS NOT EQUIPPED
WITH GROUNDING PLUG
yr x r-or- GROUND ROD WITH CLAMP
Bonding and grounding of a flammable liquid
tank truck and loading rack [5].
Figure 5-8.
deep-well (vertical-shaft) centrifugal pumps mounted on tanks »«
if ?he pump and bearings are cooled by the liquid being pumped This is to
prevent T£ rotating parts from operating in the vapor space of the tai
A gravity feed system has the disadvantage of being more difficult to arrange
fo? prompt automatic or manual shutoff than unloading by pumping An °£«
3S
gravity transfer ma? be necessary; it is required for many processing
operations .
Some of the safety precautions for a gravity feed system are:
(1) installation of emergency shutoff valves in all gravity transfer
systems.
(2) Location of such valves as close to the source as possible.
Inert gas transfer methods, owing to the ww...r.
medium, have the same disadvantage as the gravity system.
the event of
5-22
|j
-------
breakage or leakage, flow from the system will be continuous. Such systems
also introduce the complication of pressure storage tanks.
Among the disadvantages of the inert gas transfer methods are these:
(1) A considerable amount of liquid may be discharged in the event of
pipe failure or careless valve operation.
(2) Because vapor-air explosions are extremely violent at high pressure,
transfer by compressed air should be avoided.
(3) Tanks for inert gas transfer systems have to be constructed,
installed, and tested in accordance with ASME or other recognized
codes for unfired pressure vessels.
(4) The gas pressure is regulated at the minimum needed to force the
liquid through the transfer system, and a relief valve with a
slightly higher setting downstream must normally be installed.
(5) Provisions need to be made for automatically shutting off the supply
of inert gas and for bleeding the gas pressure from the flammable-
liquid system in event of fire.
Transfer can be made by nitrogen, carbon dioxide, or other inert gases The
system is under constant pressure, and the compressibility of the transfer
medium" results in discharge of considerable liquid if there is pipe failure or
careless valve operation.
A schematic diagram illustrating the inert gas transfer method is shown in
Figure 5-9.
Fail-safe transfer lines primarily intended for use in transferring hazardous
Fliquid:fbetw"nfearmobile "transporter and storage facility have been dev,.oped
m The operating principle is based on measurement of flow rate at the
inlet and ouUet of ?he transfer line, and detection of a leak through
comparison of the two rates.
The system consists of four items: an inlet assembly, a flexible hose, an
outlet assembly and a control module. It is designed to transfer hazardous
fluids and to automatically close both the inlet and outlet valves upon
detection of a !eak It will also cause the inlet and outlet valves to close
if electrical power is lost, the valve operating air pressure is out of toler-
ance or if any cable is severed. Figure 5-10 shows a simplified diagram of
the system.
The inlet and outlet assemblies are shown in Figure 5-11. They are identical,
except that a strainer is included on the inlet assembly only ™e transfer
h«« is a 2-inch diameter, 50 ft. length of steel-reinforced steam hose
^signed to carry a^ut 100 gpm. decontrol module is housed in -explosion
prooTjunction box, consisting primarily of a simple hardwired computing
device [7].
5-23
-------
HEAT-RESPONSM
DEVICE
PUSH-BUTTON
SWITCH
INERT GAS SUPPLY LINE 7-
MANUAL CONTROL VALVE *•
GAS COMPRESSOR 9-
PRESSURE-REGULATOR VALVE 10.
SOUNOID-OPERATED THREE-WAY TWO-PORT
VALVE. WHEN CIRCUIT TO SOLINOID IS COM-
PLETED. VALVE INLET IS CONNECTED TO OUT-
LET TO SUPPLY INERT GAS TO TANK. SHOWN 11.
WITH CIRCUIT TO SOLENOID BROKEN: VALVE
DISCHARGE IS CONNECTED TO DRAIN TO
RELIEVE PRESSURE ON TANK.
RELIEF VALVE
COMPRESSED
INERT GAS
FLAMMABLE
LIQUID
LiqUID-LEVEL DIAL INDICATOR
FILL CONNECTION
STRAINER
SOUNOID VALVE. INTERLOCKED SO THAT IT
WILL BE OPEN ONLY WHEN VALVE 5 ON INERT
GAS SUPPLY LINE IS IN THE POSITION SHOWN
AND VALVE 11 ON DELIVERY LINE IS CLOSED.
SOLINOID VALVE. ARRANGED FOR MANUAL
CONTROL AND FOR AUTOMATIC SHUTOFF IN
EVENT OF FIRE AT PROCESS.
Figure 5-9. Compressed inert gas transfer method [6].
AIR SUPPLY
AIR
RESERVOIR
FROM
TANK CAR
TO DISCHARGE
PUMP
Figure 5-10. Fail safe transfer line for hazardous fluids [7].
5-24
-------
PNEUMATIC VALVE
ACTUATOR
PILOT VALVE
PORTABLE CABLE
CONTROL MODULE
500 a RESERVOIR
CHECK VALVE
1/4" AIR LINE
PORTABLE CABLE
TO CONTROL MODULE
FtOW METER
2" STRAINER
(INLET ONLY)
Figure 5-11. Fail safe transfer line inlet and outlet assemblies [7].
The device will reliably detect leaks of 0.5% or greater. Average fluid loss
before valve actuation (closing at 85 gpm and 0.5% leak rate setting) was 250
mL. It should be noted that the extremely low fluid loss before shutdown is
only a measure of the device reaction tine and not of the total fluid loss
that may be experienced in the event of a leak. Fifty feet of 2-inch hose
holds about 8 gal of fluid; all of which could be lost through the leak after
shutdown.
5.3.3.1 Safety/Emergency Provisions—
Hazardous fluid unloading and transfer operations offer one of the highest
likelihoods of accidents; i.e., fire, spills, or worker exposure. Technical
bulletins of the Chemical Manufacturers Association (CMA) and the American
Petroleum Institute (API) provide excellent guidance for the unloading of tank
cars and tank trucks [8-11].
Some of the design provisions and procedures for safely unloading hazardous
liquids include:
(1) The condition of the cars is examined, and any leaks are to be
reported immediately.
(2) Before unloading starts the area is checked to be sure it has no
exposed lights, fires, or other sources of ignition.
(3) Vents on tank cars are protected by flame arresters.
(4) In all cases, personnel should be thoroughly trained and have been
given written instructions suitable for each material they will
handle.
5-25
-------
(5) Adequate personal, protective equipment have been furnished for
those involved in the loading and unloading of tank cars. For
materials that are corrosive to the skin or that may be absorbed
through it, full protective clothing with face masks, rubber gloves,
rubber shoes, etc., is required. When materials that have toxic
vapor or gas are unloaded, personnel should be equipped with airline
respirators or self-contained breathing equipment. Protective equip-
ment not available at the site should be obtained even though this
may mean some delay in making the transfer.
(6) First aid and medical procedures are worked out in advance and
posted in the unloading area. Where unusually toxic substances are
handled, medical personnel will have information on the character-
istics of the material and on the medical management needed for
any material they may encounter.
(7) Fire extinguishers of adequate type for the material handled are
distributed throughout the area.
(8) Personnel responsible for unloading stay in the immediate vicinity
of the operation at all times, and ascertain that all conditions
are normal.
(9) An emergency shower and an eyewash device is available at each
loading location. Preferably, these devices are tied to an alarm
system that would bring help to any man making use of them.
(10) Safe access to the top of the vehicle is one general safety
requirement for liquid unloading. This is particularly important
for top unloading, but it may also be necessary for operations such
as gauging or sampling. Thus, loading racks with suitable ladders.
platforms, gangways, or even railings permanently affixed to the
vehicle are usually required.
(11) Keeping liquid-unloading facilities usable in adverse weather
conditions, such as icing, may be difficult, but every effort
must be made to keep them safe. Good general illumination,
especially at night, is far preferable to providing the operator
with an extension light, which he might drop.
(12) Steel pipe and swing joints or flexible hose of the standard metal
type are usually used for connections to tank cars or tank trucks.
Metal-reinforced rubber hose of a type resistant to the material
being handled is acceptable but less desirable. See Section 5.13
on materials compatibility.
(13) Each line and connection should be clearly identified to avoid
intermixing materials.
(14) Liquids that require heat within the tank car for pumping purposes
should be received only in cars equipped with heater coils. The
minimum steam pressure necessary to being the liquid to a fluid
5-26
-------
state is used. A regulator adjusted to this pressure is installed
in the steam line, and a relief valve with a slightly higher setting
is provided downstream.
(15) Some tank cars and tank trucks have interior linings of rubber
or plastic of various kinds. When such cars are being unloaded,
special care must be taken to prevent damage to the lining.
(16) Pumps are preferably located outdoors so that fire at the pump will
not expose property of appreciable value. They should not be located
inside diked areas. Pumps are sometimes located in small detached
noncombustible pump houses or in cutoff rooms of main buildings.
When they are located indoors and handle flammable liquids with
flash points below 110°F, positive low-level exhaust ventilation
of 1.0 ft3/min-ft2 of pumproom floor area is recommended.
Natural ventilation is acceptable for less hazardous liquids.
(17) Where flammable liquids are handled in a pump house, motors can be
partitioned and sealed off from the rest of the pump house, or
can be of a type approved for use in flammable atmospheres. It is
a good operating and safety practice to have a well-marked master
cutoff switch outside the building. However, consideration is
normally given to locating flammable liquid pumps outside of
buildings whenever feasible.
(18) As a fail-safe precaution, an interlocked warning light or physical
barrier system is often provided in unloading areas to prevent
vehicular departure before complete disconnect of flexible or
fixed transfer lines.
5.3.3.2 Spill and Runoff Containment--
Drainage from the unloading area is collected or diverted to allow runoff of
any spills or runoff from rainfall to permit recovery or at least proper
disposal. The basic objective of secondary containment is to prevent the
discharge of hazardous materials to waterways, sewer systems, or groundwaters.
Containment systems which fail under rainstorm conditions are considered
inadequate. To the extent feasible, such containment is designed to hold 110%
of the largest unit handled (or largest unit contents plus the maximum
24-hr/10-yr rainfall event, if greater).
For tank trucks a system of containment curbs are used for unloading areas,
using ramps to provide truck access into the confines of the containment curb.
A lined trenching system encompasses the railroad tank car unloading area.
The trench is designed to carry away any spill or runoff to a catchment basin
or holding pond for later treatment. Figure 5-12 illustrates a containment
curb type spill catchment system, depressed area form.
5.3.3.3 Static Electricity Prevention—
Static electricity is generated when fluid flows through a pipe or from an
orifice into a tank. The principal hazards created by static electricity are
those of fire and explosion, which are caused by spark discharges containing
5-27
-------
SLOPE
ITEM
1
2
3
4. 5
6
7
DESCRIPTION
Of PROTECTION
DIKE
RAISED DRAIN
TRENCH DRAIN
SUMP PUMP
DILUTE SUMP
CONC. SUMP
OPERATION/EQUIP.
PROTECTED
TANKS
OVERFLOW. DRIPS
TANKCAR
PROCESS SEWER
TANK MAT
PROCESS SEWER
HAZARD
SPILLS. WASHING
CONC. SPILLS
UNLOAD, SPILLS
SLUG DISCHARGE
SPILLS
DISCHARGE
Figure 5-12.
Containment curb type spill catchment
system, depressed area form [12].
sufficient energy to ignite any flammable or explosive vapors or dust present.
A point of great danger from a static spark is the place where a flammable
vapor may be present in the air, such as a delivery hose nozzle.
The terms "bonding" and "grounding" often have been used interchangeably
because the terms are poorly understood. Bonding is done to eliminate a
difference in potential between objects. Grounding is done to eliminate
difference in potential between an object and ground. Figures 5-7 and 5-1
(Section 533) illustrate bonding and grounding of tank cars during unloading
operations. Figure 5-13 shows rail joint bonding and track grounding.
INSULATED TRACK JOINTS •
PLAN
DERAIL
•DURABLE RA& BUMPERS
^ noun
ELEVATION
GROUND ROD WIRE TO BE FASTENED
TO RAILS 1 GROUND
Figure 5-13.
A tank car unloading siding showing rail joint bonding,
insulated track joint, detail, and track grounding [5].
When unloading tank cars through open domes, it is best to use a downspout
long enough to reach the tank bottom. Generally, tank cars need not be
5-28
-------
separately grounded because the resistance of the natural ground through the
tank car wheels and rails, and the resistance of piping, flexible metallic
joints or meialUc swivel joints, are considered sufficiently low to protect
against static electricity. For detailed information and exceptions to this
generality, consult NFPA Standard No. 77, "Recommended Practice on Static
Electricity."
5.3.4 Container Unloading
For hazardous wastes, the choice of container will usually be made from among
various types of drums, barrels, and special bulk units. As is true in any
bulk handling problem, the first step is to obtain information on the type of
container which will be received with respect to its handling properties
Since it contains a hazardous waste, the container must then meet the regula-
tions for its transportation set forth by the Department of Transportation and
RCRA.
Containerized hazardous waste is most likely to arrive for unloading via rail
boxcar or truck semitrailer. Due to economics of transportation, the carrying
capacity of a trailer or boxcar will most likely be near the maximum. A
55-gal drum is the most popular form of container; a boxcar can carry 360
55-gal drums per carload.
in addition to liquid waste, certain dry materials require the strengthwater
tightness, weatherability. and general ruggedness of a »J;el *""; Standard
specifications for steel drums have been established by the Department of
Transportation; a typical specification is shown in Table 5-2. The heavier
gage drums find use in transporting liquids.
The process for unloading trailers or cars differs by the waste and hauler
Drummed material may be placed on pallets or may rest on the bed of the trail
er. in the latter case, the hauler may be involved with unloading and may
manually handle the cargo. A common delivery condition for cargo touching the
trCck bed is "tail gate delivery". whereby the truck driver moves the packaged
cargo to the tailgate of the trailer, and the recipient removes it.
Alternative methods include industrial trucks with drum-loading attachments
or fork-lifts for containers on pallets. Type EE battery-powered industrial
trucks have the additional safeguards (electrical equipment enclosed to pre-
vent emission of sparks) needed to work in hazardous locations,- Type EX trucks,
which are of explosion-proof or of dust tight construction, are also
recommended.
After removal steel drums can be handled by gravity conveyors. However, steel
drums should not be transported on wheel conveyors, because the chime, or lip,
at the drum bottom gets hung up on the wheels. If roller conveyors are used,
the rolls need to extend at least 2 in. beyond the outside surface of the
chime, unless the drums are centered by guard rails. Drum loads up to 250 Ib
can be handled on a conventional 1.9-in. roller conveyor having rollers spaced
at 3 in. and positioned at a 1-1/2 in. pitch.
5-29
-------
TABLE 5-2. TYPICAL STEEL DRUM SPECIFICATION FOR HAZARDOUS MATERIALS [13]*
Capacity.
gal
55c
55d
30d
Inside
diameter
22 1/2
22 1/3
IS 1/4
Inside
height
32 11/16
32 11/16
27 5/16
Outside
diameter
23 27/32
23 27/32
19 19/32
Overall
height
34 13/16
34 13/16
29
Steel
gage,
body
16
IS
18
55C
55=
30d
Steel
gage,
cover
16
16
IS
Steel
gage,
bottom
16
IS
18
Steel
gage,
ring
12
12
12
Tare
weight . DOT
(approx.) spec.
64.5
55.5
37.5
17C
17H
17C &
17H
All dimensions given in inches. Dimensions are within
normal manufacturing tolerances of ± 1/16 in. (± 1/8 in.
on height).
Container weights shown are approximate and may vary
within the allowable limits for manufacturers standard
gage.
C0n the 55-gal drum, a third rolling hoop, directly
below the top rim, gives strength and rigidity to meet
specifications.
^hese drums meet Department of Transportation Specifi-
cations DOE 17H and DOT 17C for storage and shipment of
hazardous materials. They also meet Rule 40 of the
Uniform Freight Classification, and Rule 26C of the
National Motor Freight Classification; DOT 17H drums
also comply with ANSI standards.
Because of the difference in weights between empty and full drums, a roller
pitch as high as 5 in. can be specified for empties, while a pitch of 3 in.
may be sufficient for full drums. Both live- roller conveyors and belt-on-
roller conveyors can also be used to convey drums.
A host of other special containers have been made for storing, shipping, and
handling hazardous materials. Some of these units are designed to hold
2,000 Ib or more; some designs include metal-walled containers equipped with
specialized filling and discharge openings and rubberized containers. A major
factor to be looked at when a facility receives these types of units is the
total system concept of handling, with appropriate machinery and design taken
into account.
5-30
-------
Once a container has been unloaded, three possible options exist for
distributing the contents:
(1) Place the container in storage.
(2) Pump the contents (liquid) into another storage tank.
(3) Dump the contents (bulk solids) into another receiver.
5.3.5 Bulk Solids Unloading
Hazardous waste bulk solids for incineration will arrive for unloading in
hopper cars - both truck and rail. Due to the hazardous nature of the materi-
al transported, the hopper cars must be the covered type, typically with
bottom unloading ports. Three types of unloading systems are used:
(1) gravity,
(2) pressure differential, and
(3) fluidized.
Figure 5-14 shows examples of fluidized unloading ports. Fluidized unloading
is preferable for hazardous wastes when possible, because gravity unloading
necessitates having a pit located under the rail spur.
LADING SLIDES TO
DISCHARGE OPENING
OPERATING
HANDLE
OPERATING
HANDLE
LOCKING BOLT
DISCHARGE
OPENING
AIR INJECTED IN TO AREA
AROUND DISCHARGE
OPENING
PERMEABLE STAINLES
STEEL SLOPE SHEETS
FUIIDIZING AIR LINE
CONTROL VALVE
Figure 5-14. Fluidizing outlets for hopper cars [14].
5.3.5.1 Mechanical Conveyors—
When a discharge pit is used for unloading, the material is then conveyed to
storage via one or more of three methods:
5-31
-------
(1) screw conveyor,
(2) belt conveyor, and
(3) bucket elevator.
The screw conveyor is one of the oldest and most versatile conveyor types. It
Insists of a long pitch, steel helix flight mounted on a shaft supported by
bearings within a U-shaped trough. Screw conveyors are generally easy to
maintain and inexpensive to replace.
Belt conveyors consist of an endless belt moving horizontally °^on *
Almost all belt conveyors for bulk solids use rubber-covered belts whose
carcass provides the strength to pull and support the load Belt conveyor
slopes are limited to a maximum of about 30° with those in the 18-20° range
more common. In an evaluation of a materials-handling system involving belt
conveyor the number of belt transfer points should be reduced to a minimum
to cut degradation, dust, and cost. Elevation of all belt lines a few feet
above ground will ease inspection, maintenance, and cleanup. Belt conveyors
emit dust almost exclusively at the transfer points. Placing enclosures
around transfer points can give effective dust control. A few simple rules
are normally followed for dust control:
(1) Reduce the number of belt transfers point to a minimum
(2) Be generous in sizing enclosures
(3) Arrange enclosures in easily removable sections
(4) Provide access doors on enclosures
(5) Install skirting and curtains at openings.
Bucket elevators are the simplest and most dependable units for making
vertical lifts. They can be totally enclosed to reduce fugitive dust
emissions.
5.3.5.2 Pneumatic Conveyors--
Pneumatic conveyors are commonly used to transfer dry granular or powdered
materials, both vertically and horizontally, to plant areas hard to reach
economically with mechanical conveyors. The properties of a ™JeriaJ f8*"' .
mine whether or not it can be successfully conveyed pneumatically. The mater i
al must pass through piping and auxiliary equipment without clogging,
degradation, or segregation, and be readily disengaged from the conveying air.
Materials from fine powders through 1/4- in. pellets can be handled.
Pneumatic systems can be completely enclosed to prevent contamination "J*"™'
al loss, and dust emissions. Furthermore, some materials are better protected
from adverse reactions when they are conveyed using an inert gas or dried air.
Pneumatic conveying systems can provide smooth, controlled handrof* "^"f .
ing of bulk rail cars. The unloading procedure begins with the insertion of a
material pickup probe into the rail car's discharge port. The probe controls
the material-to-air ratio, and probe kits are designed to fit all rail cars.
5-32
-------
They consist of housing with slotted probes of varying lengths, designed to
reach different areas or compartments across the rail car. An air intak<
filter is clamped to the car's discharge port opposite the material picKup
connection, and a car hatch filter attaches to the top of the rail car to
relieve vacuum created in the car by the material flow. Figure
trates pneumatic unloading of a railcar.
MATERIAL LINE
IN-PLANT
DISTRIBUTION
MANIFOLD
IN-PLANT CONVEY ING
VACUUM POWER UNIT
BULK UNLOAD ING
VACUUM POWER UNIT
MATERIAL
LINES
Figure 5-15. Diagram of pneumatic railcar unloading.
5.4 WASTE STORAGE AREA
The manner in which a waste is handled on-site is dependent on the nature of
the waste (corrosivity, explosivity, etc.), plant storage f-"litie.. and heat
content of the fuel. Wastes received for incineration at a dlsP"al/;"^y
are either incinerated directly (in some cases via pumping directly from the
tank truck), or stored until they can be handled more conveniently A plant
operator may want to store some of the incoming wastes with higher heating
values to possibly blend with other wastes which have heating values too low
to support combustion alone.
For further information on storage of hazardous waste in tanks, piles or con-
tainers, see The Permit Writer's Manual on each of those topics (prepared by
Fred C. Hart Assoc., Inc.).
Storage capacity is based on:
• Seasonal inventory buildup
• Redundancy or excess incinerator capacity
• Maintenance schedules and downtime
. Operating schedules (i.e., number of shifts vs. inshipment rates)
• Amounts and nature of waste blending to be done.
5-33
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Depending on the type of incinerator installation, storage facilities may be
required to hold both liquid and solid hazardous wastes. If an incinerator
cannot burn solids, facilities for solid storage are obviously not necessary.
A hazardous waste storage area is designed to address three problem areas:
(1) Segregation of incompatible corrosive and reactive waste types,-
(2) Fire hazards due to flammable liquids and solids; and
(3) Toxic hazards to prevent human exposure during storage, transfer,
and spill possibilities.
The safety and emergency design provisions for storing hazardous liquid wastes
are described in Section 5.4.3.
5.4.1 Types of Storage
5.4.1.1 Liquid storage— .
Liquid/fluid waste storage includes temporary holding tanks, batching tanks,
main storage tanks, and transfer pumps (pumps and valving are discussed in
Section 5.5). Holding tanks provide initial storage of wastes prior to final
deposition of the material. Other tanks can store specific waste categories
which have been analyzed, require segregation, and are ready for incineration.
Batching tanks are used to prepare an 8-hr shift waste feed for the incinera-
tor. Also, tanks may be needed to store fuel oil (or bottled gas) for
incinerator ignition and auxiliary burners.
Container nomenclature is vague but, ordinarily, "tank" means a container
designed to withstand pressures from atmospheric up to about 15 psig, whereas
"vessel" refers to a container which can withstand external or internal pres-
sures exceeding 15 psig.
There are several basic types of storage tanks, as shown in Figure 5-16. The
aids to design of tanks takes the form of specifications, rules, standards,
and codes.
Any of the vessels noted above can be lined or coated with corrosion-resistant
materials. All weld spatter is removed, and welds ground smooth or flush,
depending on the type of coating to be applied. Tank nozzles must be large
enough so a coating can be applied.
Both vertical and horizontal tanks are available for storing liquids Verti-
cal tanks are more economical to install, and occupy less space, while horizon-
tal tanks are easier to maintain and repair. Usually the lower maintenance
generally required by horizontal tanks does not offset their higher cost and
greater space requirements; hence, vertical tanks are normally recommended.
If however it appears that future compartmentation of the tank will be
likely (as with segregated waste storage),-it is easier to modify a horizontal
tank.
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|
^-c^l
1 CONE- 2 CONE-WTTO*
TOP FIXED ROOf SKIRTED
3 DOME ROOF
4 FLOATING ROOF.
OPEN TOP
5 FUWTING ROOF. 6 EXPANSION ROOF
FIXED TOP
7 CONE- BOTTOM. (
UNSKIRTED
SPHE
9 HORIZONTAL DRUM
Figure 5-16. Typical shapes for storage vessels [15].
Installation and maintenance of aboveground tanks are less troublesome than
for underground tanks. With underground storage, the functions of gaging,
pumping, and leak detection become more difficult. With storage of hazardous
wastes and liquids, underground tanks and their possibility of leakage is
discouraged. Underground tanks lend themselves to accelerated corrosion and
often require cathodic protection. Also, a means of containing leaked or
spilled materials is necessary for most underground tanks.
Depending upon the liquid waste contained, tank storage can also require many
accessory equipment features such as:
(1) Flash arrester fill pipes.
(2) Flame arrester rodding and sampling units.
(3) Conservation breather vents with pipe-away construction—used where
pressure or vacuum relief is required and vapors must be piped away
rather than released into the atmosphere.
5-35
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(4) Tank vent condensers—designed to condense and return to the tank vapors
that could escape, as shown in Figure 5-17.
FILL LINE
LIQUID LEVEL
CONDENSING OR
CHILLING SYSTEM
Figure 5-17. Typical tank condenser vent system.
(5) Steam-heated conservation, pressure, or vacuum relief vents—designed
for use on tanks containing liquids whose vapors tend to crystallize
at ambient temperatures (also with pipe-away construction).
(6) Mushroom vent with flame arrester—used where it is not necessary to
conserve vapor losses, but where low flash point solvent materials must
be protected against fire and explosion from exterior sources of
ignition.
(7) Steam-jacketed flame arrester vents—designed for use on tanks containing
hazardous liquids whose characteristics require steam heating to prevent
crystallization of interior vapors; e.g., naphthalene.
(8) Manhole and emergency pressure relief vent covers—to provide emergency
pressure relief as well as access for tank cleaning.
(9) Internal safety valve—intended for use where tanks are required to be
equipped with valves that close automatically when subjected to fire.
(10) Integral internal heating coils—usually steam, designed to prevent
freezing of tank contents.
(11) Overflow piping--usually connected to an adjacent tank to mitigate spill
possibilities.
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5.4.1.2 Bulk Solids Storage—
Material received as bulk solids at a hazardous waste incineration facility
can be stored in three ways:
(1) Enclosed bins or silos
(2) Concrete pits or below-grade concrete hoppers
(3) Stockpiles
Generally, solid hazardous waste materials which present a toxicity problem to
plant personnel are stored in totally-enclosed storage, such as single-outlet
bins, multiple-outlet silos, and portable bins. These enclosures protect the
hazardous material from exposure to the elements, or guard against dangers
represented by explosive, flammable, ignitable, or corrosive properties.
Table 5-3 gives a rough rating of the major types of bulk storage units in
terms of their capacities and method of reclamation or discharge.
TABLE 5-3. TYPES AND CHARACTERISTICS OF DRY BULK STORAGE [13]
Storage technique
and method of
reclaim or discharge
Storage capacity
Small, Large,
under over
20,000 700,000
ft3 Med. ft3
Stockpiles
Bottom tunnel
Bucket wheel
Scraper truck
Front-end loader X
Multiple-outlet silos
Mass flow X
Expanded flow X
Funnel flow X
Single-outlet bins
Mass flow X
Expanded flow X
Funnel flow X
Portable bins
Funnel flow X
Mass flow X
Concrete pits
Grapple X
X
X
X
X
X
X
X
X
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Multiple-Outlet Silos—Multiple-outlet silos are useful for storing small or
medium quantities of material. Because they generally rely on gravity flow to
discharge the solids, hopper slopes and outlet dimensions must satisfy the
minimum requirements for uninhibited flow.
One of the most common problems with multiple-outlet silos is structural
failure caused by nonsymmetric flow patterns. Side discharge is typically
used with free-flowing materials such as grain. With this arrangement, bin
failures, especially in steel structures, manifest themselves as dents in the
region of the localized flow channel.
Single-Outlet Bins—Single-outlet bins are the most common type of storage
units in industry. Most of them are funnel-flow type, in which the sidewalls
of the hopper are sufficiently steep to maintain continuous flow. Most
pyramidal hoppers and conical hoppers with slopes of 60° or less from the
horizontal will display funnel flow.
Portable Bins—These special bulk units, generally limited to volumes less
than 200 ft1*, are often thought of simply as large buckets used to transport
homogenous material of a specified size and composition. Typically, these
bins are cube-shaped, with a flat hopper leading to a central outlet about 10
in. or less in diameter.
Some of the solid material characteristics considered when designing a solids
storage and retrieval system include:
(1) Bulk density
(2) Moisture content
(3) Particle size
(4) Angle of repose
(5) Angle of slide
(6) Temperature
(7) Pressure differentials
(8) Abrasiveness
(9) Cohesiveness
(10) Material melting point
(11) Hygroscopicity
Many different types of bin hopper discharging devices have been developed,
primarily because solid material retrieval is difficult to achieve reliably
and consistently. Some of the bin hopper discharging devices are:
(1) Manual prodding through poke holes to eliminate material "bridging"
(definitely not useful for hazardous wastes)
(2) Chain or cable elements suspended to reduce bridging
(3) Agitators or "rotating fingers"
(4) Sweep arms or rotary vanes
(5) Rotary plows
(6) Multiple screw bottoms
(7) Bin activators or vibratory sections
(8) Electromechanical devices, such as side vibrators
(9) Pneumatic and hydraulic vibrators
5-38
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(10) Air pads, cushions, and slides, wherein air is injected to fluidize the
material.
If one word could describe the basis of all solids retrieval problems, it
would be "friction." Any hopper surface which can reduce friction can mini-
mize bridging or arching. Fortunately, for a corrosive-type hazardous solid
material, the material of construction or lining of the hopper bin can solve a
dual problem. Materials to be given consideration are:
(1) Stainless steel, full thickness or dad-polished
(2) Teflon sheets bonded to steel containers.
Items of safety in bin design considerations include:
(1) Access doors for inspection, routine maintenance, and firefighting
(2) Fire detection—sensors; alarming; automatic suppression systems such as
C02, foam, or water; standpipes for connection to a water source and
availability of fire hoses
(3) Detection of level and pluggage
(4) Provisions for dust control
(5) Provisions for maintenance removal of bin discharge mechanisms which are
normally buried under waste.
Concrete Waste Pits—Concrete solid waste pits are in wide use in municipal
and industrial waste disposal plants which handle nonhazardous wastes. Bulk
solid refuse is dumped into the storage pit by packer truck, load lugger
bucket, or other collection vehicles.
The storage pits are normally under an enclosure to prevent precipitation from
entering, and there is an approximately 10 ft wide vestibule which trucks back
into. Refuse is picked out of the pit by a bridge crane with a bucket or
grapple, and the crane delivers the solid waste to an infeed system. Control
of the crane and grapple is usually from an air-conditioned pulpit in which
the operator sits. Control is a saturable reactor type which provides cush-
ioned starting and acceleration. Protective zones are provided preventing the
operator from drawing the grapple into a wall, pulpit, etc. Automatic control
can be provided.
For fugitive dust control at each truck dumping point, there can be a down
blast heater. The vestibule and pit area are designed for complete sprinkler
protection of fire. Sprays in both the front and rear wall of the pit can be
included to suppress dust clouds that arise when a load is dumped.
The entire pit is usually watertight and sloped to troughs and drains for
dewatering. When a pit is constructed below grade, it is usually necessary to
have a sump. Screening devices to prevent material from entering the sump are
also used [16].
Stockpiles—Hazardous wastes are occasionally stored in piles, generally small
in size. Many are in buldings or maintained outside, under cover, on concrete
or other pads. They are most frequently used to accumulate waste composed of
a single, dry material.
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Wind dispersal is controlled by a cover or windscreen; piles inside a building
are adequately protected from dispersal.
5.4.1.3 Container Storage—
Hazardous materials for incineration will often arrive in small container form
(e.g., 55 gallon drums), and can be stored until used, provided the containers
are in good condition and are not leaking.
Metal and fiber containers are loaded, stored, and unloaded so as to minimize
the possibility of container damage. The containers are stored in a covered
area, off the ground, in a manner which will preclude damage, weathering, and
subsequent leakage. Storage pads of concrete or other impervious materials
are used as a base to prevent ground water leaching and percolation. The area
itself is provided for drainage to a treatment facility in an analogous manner
to diked storage tank areas.
If some containers contain corrosive substances, these are stored so that,
should leakage develop during storage, these substances will not corrode
through adjacent containers. Waste segregation practices of bulk storage
(liquid and solid) also prevail with indoor container storage.
All containers in storage are inspected to insure physical and mechanical
integrity, and the drainage and containment systems are also inspected.
Nonstationary containers can proliferate in a storage area,- hence, all con-
tainers are clearly labeled and records maintained. In this way the operator
is able to quickly locate any hazardous waste.
Waste containers are sealed to prevent the escape of vapors. Gasketed clo-
sures of containers and containers themselves are normally of a material that
will not be deteriorated by the waste inside the container. The container
storage enclosure area is vented to allow for collection and control of any
released vapors.
5.4.1.4 Tank Cars—
Hazardous waste storage can also occur in parked tank cars — both truck and
rail. Usually, the wastes are then pumped directly to the incinerator or
blending tanks. As with bulk storage, the area is designed to prevent ground
contamination and percolation, and diked or drained to collect spills and
surface runoff. As with container storage, each tank car is clearly labeled
and records maintained to quickly locate each hazardous waste.
5.4.2 Segregation of Wastes During Storage
Hazardous wastes may be segregated at an incineration facility due to waste
categories for fuel value and are certain to be segregated when incompatible
waste types are received. The type of incinerator and nature of wastes which
can be burned will greatly influence the extent of waste segregation during
storage.
Incompatible wastes are normally segregated due to corrosive and reactive
effects. Examples of segregation during storage are reactive chemicals which
5-40
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should be stored in air or water tight containers, oxidizers which should be
isolated from flammable materials, and materials which may polymerize in the
presence of accelerators. Section 5.5 on waste blending contains a ready and
quick reference for determining the compatibility reactions of most binary
combinations of hazardous wastes.
Wastes may also be segregated and stored to allow for fuel blending for maxi-
mal incinerator performance. Examples of the categorization of wastes which
could occur and the storage requirements necessary are as follows [17J:
(1) Light hydrocarbons and nonaqueous solvents — includes low flash
point wastes such as paint thinners, aromatics (toluene, benzene.
xylene, etc.) which reduce viscosity of heavier wastes and assist
fuel oil in initial heating prior to firing heavy blends.
(2) Medium to heavyweight hydrocarbons — includes still bottom
residues crankcase oils, and discarded transformer oils. Most have
high flash points but relatively low ignition temperatures and
moisture is generally under 10 percent. Handling these wastes may
require use of insulated storage tanks and auxiliary heat to
maintain proper fluidity, particularly during cold weather.
(3) Low-water-content aqueous wastes -- sludges from fatty acids
production, starches, reject fatty acids, waste soluble oils, and
clabberstock. These wastes may be blended in limited proportions
with the heavier wastes in group 2 but require storage in insulated
and heated tanks to avoid congealing and freezing of contained water
during winter.
(4) Dirty solvents -- includes kerosene, soluble inks, oil-solvent
residues, organic pigments. Storage tanks do not require insulation
or heating.
(5) High-water-content aqueous wastes, semisolids, sludges, and low
heating value liquids - includes aqueous mixture of paint enamel
and lacquer oversprays. liquid polymers in water, paint sludges.
(6) Skimmings from wastewater treatment plants — floatable material
skimmed from settling tanks and thickeners such as spent grease.
(7) Spent earth — from filters and contaminated areas. Due to high
water content this waste can require insulated storage, auxiliary
heat, and continuous agitation to maintain fluidity and prevent
freezing in cold weather.
5.4.3 Safety Provisions for Storage Areas
For safe facility design in the storage area, provisions are »ade to Protect
personnel and the immediate environment from catastrophe-particularly fire
hazards and material spills. Liquid and container storage are most likely to
occur at a hazardous waste incineration facility, and are discussed below.
5-41
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5.4.3.1 Fire Safety— . /«™,»
Volume 1 of National Fire Codes (National Fire Protection Association (NFPA),
Boston) contains recommendations and standards in NFPA 30, "Flammable and
Combustible Liquids Code," for venting, drainage, and dike construction of
tanks for flammable liquids. Also possibly applicable are NFPA 327, "Standard
Procedures for Cleaning or Safeguarding Small Tanks and Containers", and NFPA
43A, "Liquid and Solid Oxidizing Materials."
Many of the devices and equipment utilized to prevent fire hazards in the
liquid storage area were discussed in Section 5.4.1.1. Some other considera-
tions which apply to storage of large quantities of flammable liquids include:
(1) Instrumentation or remotely-operated valves to minimize flow of
flammables.
(2) Combustible gas monitors in the storage area which have an alarm
set below the lower flammable limit.
(3) Combustible gas monitors that automatically actuate a deluge system
or safely shut down systems below lower flammable limit.
(4) Drainage and collection ponds (equalization basin) to carry away
liquid spills resulting from a fire incident.
For the storage of drums, many safety precautions can be used for the protec-
tion of the operators who open and inspect drums prior to incineration.
Safety features include:
(1) explosion-proof electrical equipment
(2) automatic fire doors
(3) a "light water" system
(4) dry chemical and C02 fire extinguishers
(5) special safety fork trucks with nonsparking forks
(6) air-operated pumps
(7) nonsparking tools
(8) safety showers and eyewashes
(9) safety glasses and face shields
(10) a ventilation system which makes a minimum of three air volume
changes per hour in all areas and thirteen (13) air volume changes
per hour in the drum pumping room or area.
For storage of bulk-solids, evidence of spontaneous heating is closely moni-
tored. Heat-sensitive devices in silos and bins are installed, connected to a
continuous temperature recorder at a central control board and arranged to
sound an alarm if unsafe temperatures are produced. Excessively wet materials
are not placed or permitted in storage silos or bins.
5.4.3.2 Spill/Toxicity Safety—
The most effective way of addressing a bulk liquid storage area's vulnerabili-
ty to spill incidents is to prevent them from happening. Assuming that all
storage tanks are properly designed, equipped with overflow alarms, and used
5-42
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only for intended or compatible purposes, the possibility of spills can be
substantially reduced by:
• Assuring the continual physical integrity of the vessels and their
fittings (inspection and testing).
• Establishing strong administrative controls covering all loading/unload-
ing and in-plant transfer operations (plans and procedures).
• Providing adequate secondary containment facilities (dikes, diversion
ditches, equalization basins).
Physical Testing and Inspections—Spark testing (of lined storage tanks),
wall-thickness testing, or other appropriate means of nondestructive physical
testing or inspection are conducted on storage vessels which hold hazardous
liquids.
The exterior of each bulk storage tank is also visually examined at regular
intervals. Each inspection includes an examination of seams, rivets, nozzle
connections, valves, and pipelines directly connected to the tank. Visible
leaks of waste from tank seams and rivets are then promptly corrected.
Foundations and/or tank supports are also subject to inspection.
New and old tank installations are, as far as practical, fail-safe engineered
or updated to a fail-safe engineered installation. Design considerations are
given to providing the following devices:
(a) High liquid-level bell or horn alarms with an audio signal at a
constantly manned operating or listening station; in smaller plants
an audible air vent may suffice.
(b) Low liquid-level alarms with an audio signal at a constantly manned
operation or listening station; such alarms can also have a non-
bypassing reset device that can be readjusted to a given operating
level following tank fill or liquid removal.
(c) High liquid-level pump cutoff devices set to stop flow at a predeter-
mined tank content level.
(d) Direct audible or code signal communication between the tank gauger
and the pumping station.
(e) At least one fast response system for determining the liquid level
of each bulk storage tank such as digital computers, telepulse, or
direct vision gauges.
Tanks are then not knowingly used if the "head" or "top" is in a corroded-
through condition. Action is taken to drain such tanks and repair the defec-
tive member as promptly as possible.
Partially buried tanks for the storage of oil or hazardous materials are
normally avoided, unless the buried section of the shell is adequately coated
5-43
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to prevent rapid corrosion of metallic surfaces buried in damp earth,
especially at the earth/air interface.
Buried storage tanks represent a potential for undetected spills. A buried
installation, when required, is wrapped and coated to retard corrosive action.
In addition, the earth is subjected to electrolytic testing to determine if
the tank should be further shielded by a cathodic protection system. Such
buried tanks are also subjected to regular hydrostatic testing. In lieu of the
above, arrangements can be made to expose the outer shell of the tank for
external examination at least every five years. Alternatively, a means of
conducting examinations of the tank at regular intervals can be provided,
e.g., down-hole television.
Tank Overfill—A variety of engineering practices suited to the nature of any
hazardous material stored are used to prevent tank overfilling, a major source
of spill incidents. The following general principles can be used in designing
a system of protection against tank overfill:
(1) Tanks are gauged before filling.
(2) Overflow pipes are connected to adjacent, compatable waste storage
tanks, or to secondary containment.
(3) Fail-safe devices and level alarms have been tested and insured in
place.
(4) Provisions to prevent static electricity discharge have been
implemented.
Protection of Integral Heating Coils—Many liquids in storage require auxili-
ary heating to remain in a fluid state. This is normally accomplished econo-
mically by integral steam coils inside the storage tank and, often, agitation.
To control leakage through integral heating coils which may become defective
through prolonged use, the following design factors are considered and applied:
(1) The past life span of internal steam coils is determined, and a
regular system of maintenance and replacement that does not exceed
the anticipated life span is established.
(2) The temperature and environment is carefully considered when
selecting heating coil materials to reduce failure from corrosive
action, prolong life, and reduce replacement costs.
(3) The steam return of exhaust lines from integral heating coils which
discharge into an open watercourse is monitored for contamin-
ation, or passed through a settling tank, or skimmer, etc.
(4) The nature of the wastes is carefully considered to prevent wastes
from caking on the heating coils, which reduces their efficiency as
well as causing waste materials to be contained in a tank thought
to be empty.
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(5) The feasibility of installing an external heating system is also
considered, and, if feasible, often is recommended to solve
problems which may arise from implementation of (1) through (4).
Secondary Containment—All bulk storage tank installations at a hazardous
waste incineration facility are planned so that a secondary means of contain-
ment is provided for the entire contents of the largest single tank. Dikes,
containment curbs, and pits are commonly employed for this purpose, but they
may not always be appropriate. An alternative system would consist of a
complete drainage trench enclosure arranged so that a spill could collect and
be safely confined in an in-plant catchment basin or holding pond.
Dikes are generally constructed of concrete, cinder blocks, and/or earth.
However, dike materials are designed to be chemially resistant and essentially
impervious (e.g., permeability rate no greater than 10 7 cm/s when subjected
to a head of 1 ft of water) to the substances contained. Acceptable engineer-
ing design criteria for a dike will enable it to withstand a sudden massive
release.
Some of the important design guidelines for dike construction include [18]:
(1) Single storage tank — The capacity of diked area is at least ade-
quate to hold the entire tank contents plus a reasonable allowance
for precipitation. Local regulations may contain more stringent
requirements. An alternative design goal is for the diked area to
contain the volume of the tank plus 1 ft of freeboard.
(2) Clustered storage tanks — The capacity of the diked area is ade-
quate to hold the entire contents of the largest tank plus a reason-
able allowance for precipitation. Again, local regulations may be
more stringent.
(3) To the extent feasible, dike walls generally do not exceed a height
of 6 ft above interior grade. A greater height might require the
observance of tank entry procedures including safety harnesses,
oxygen deficiency checks, standby observers, and other precautions
each time it is necessary to enter the diked area.
(4) For earthen dikes, a slop of 2.5:1 is preferred. Earthen dike walls
3 ft or more in height are generally designed with a flat walkway
section at the top not less than 2 ft wide.
(5) Dikes may also need to be constructed to provide necessary ramps for
vehicles needing access to the storage areas.
(6) The disposal of rainwater and other liquids from within diked areas
is normally accomplished by a manually activated pump or siphon
system. Such accumulated stormwater must be removed in order to
maintain adequate volume for a maximum spill. Figure 5-18 shows a
diversion structure which serves this purpose. Of course, retained
drawoff water and the rainfall accumulated are checked (analyzed)
before release.
5-45
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Figure 5-18. Dike drain detail Type "A" diversion box [19].
(7) For hazardous and toxic liquids, the ground area within the dike
and curbing are designed to be essentially impermeable. :his can t
achieved by use of concrete, asphalt, or suitable clays. Neutraliz-
ing materials for the stored chemical waste such as limestone or
clam shells for acidic wastes are sometimes used as a ground cover,
although neutralizing ground covers need to be replaced promptly
after a spill or incident.
(8) Generally, it is recommended that there be no discharge or loading
pipes through the dike wall. However, construction design has to
conform to state and local regulation, and some local fire regula-
tions (applicable to flammable liquids) require a valved pipe
the dike wall, while others prohibit this installation. If a drain-
age valve through the dike wall is required, it is kept locked in
the closed position when not in use and a chemically resistant seal
is installed around the pipe passing through the wall.
(9) The storage tanks located immediately adjacent to the dike itself
are oriented so that no manholes face the dike. This is considered
desirable, so that, if a manhole fails, the resulting discharge
from a full tank will not be aimed over or at the dike. Where
this design is not feasible, appropriate baffles are installed
to deflect potential leaks and cause them to drop within the
contained area.
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(10) If storage tanks located immediately adjacent to the dike are
equipped with fill lines which enter the tank near the bottom, and
if the fluid pumped has suspended abrasive material, the discharge
into the tank should be on the dike side, discharging against the
tank side away from the dike. Alternatively, a baffle plate located
inside the tank opposite the pump discharge in the area apt to be
abraded, may be provided.
The final defense in the prevention and containment of liquid and solid spills
is at the end of the plant storm-drain system. Here, an automatic system mon-
itors the storm drain for acidity or alkalinity (PH), turbidity, total oxygen
demand (TOD), and flow (variance from normal).
If any of the parameters are sensed beyond normal limits, a diversion gate
automatically move into position to divert the discharge to a holding pond.
Such a system provides protection against a spill that goes beyond the process
area dikes, aSd into the storm drains. Discharges diverted to the holding
pond'are removed to a process area for recycle, treatment, or disposal.
Container Storage-Containers with a capacity of less than 45 gallons are
stored out-of-doors, when possible, in rows no more than 30 feet in le^h,
five feet in width, and six feet in height. Containers which have a capacity
of 45 gallons or more are stored in rows no more than 30 feet in length and
two containers in width and should not be stacked. A minimum of five feet
between rows of containers of hazardous wastes is usually maintained.
If exposure of the containers to moisture or direct sunlight (see Section 5 5)
will create a hazardous condition or adversely affect the containers' ability
to hold the hazardous waste, the containers are then stored in « J«J ™J
overhead roofing or other covering that does not obstruct the visibility of
the container labels.
The area under or around the container storage area is built to be able to
collect or hold any spilled material; e.g.. collection drains, trenches, or
dikes.
5.5 WASTE BLENDING AND/OR PROCESSING BEFORE INCINERATION
The methods by which hazardous wastes are removed from storage, prepared for
incineration, and fed to the incinerator are dependent on the nature of the
waste and type of incinerator. Figure 5-3 in Section 5.3 illustrates the
various pathways from storage to final feed into the incinerator. Careful
design consideration is given:
(a) To the layout for liquid waste blending, pumping and associated
pipework, and
(b) To the handling and feeding arrangements for nonpumpable sludges,
solids, and containerized wastes, where applicable.
Operating experience has shown that these are areas that do not receive as
much attention as is necessary,- the overall success of an incineration
5-47
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facility depends upon the successful integration of storage, feeding, and
firing equipment.
5.5.1 Waste Compatibilities
The "combination of wastes" often presents many problems for the management of
hazardous wastes. In some instances, the combination or mixture of two or
more types of the wastes produces undesirable or uncontrolled reactions
resulting in adverse consequences. These reactions may cause any one or more
of the following:
(1) Heat generation, fire, and/or explosions,
(2) Formation of toxic fumes,
(3) Formation of flammable gases,
(4) Volatilization of toxic or flammable substances,
(5) Formation of substances of greater toxicity,
(6) Formation of shock and friction sensitive compounds,
(7) Pressurization in closed vessels,
(8) Solubilization of toxic substances,
(9) Dispersal of toxic dusts, mists, and particles, and
(10) Violent polymerization.
Available data indicate that hazardous wastes are ill-defined, complex mix-
tures generated by a great variety of sources. No two ^^ °^"a
to be identical, for even a single process appears to Produce ^"
of wastes. Laboratory analyses of wastes seem to be non-existent or
Sue to the high cost'and complexity of analytical methods ^^-
terization of the wastes by the analysis of the processes and the "a
used appear to give inaccurate descriptions of the resulting wastes The data
indicate that elch waste is unique and that individual reactivities may be
best assessed by identifying respective chemical constituents.
For further information on compatability of hazardous waste refer to the
Guidance Manual entitled, "Treatment Trial Tests and Hazardous Waste
Compatability" .
While empirical data exist concerning the consequences of reactions between
pure substances under laboratory conditions (mostly binary Combinations) very
little work has been done in the field of waste combination reaction^ Very
seldom are wastes pure substances. They are usually sludges, emulsions,
suspensions, or slurries containing many different compounds.
The chance of combining noncompatible wastes within ^ specific "^Y
minimized in several ways. First, the problem is restricted to pumpable
can be
f
ible wastes will be combined occurs at the incineration facility.
the problem.
5-48
-------
It is evident from the existing data that the largest and most common dangers
inherent from incompatible reactions involve strong acids or bases. For this
reason, it is desirable that acids and bases be neutralized to within a pH
range of 4.5 to 9 before being mixed with other wastes (sometimes acidic and
basic wastes are mixed in a controlled manner to achieve pH neutrality).
Even within this restricted pH range, acids should be segregated from acid-
soluble sulfide and cyanide salts.
With the above inclusions, an example of a compatibility matrix is depicted
in Figures 5-19 and 5-20. If it is not feasible to neutralize acid wastes
and/or caustics to within the prescribed pH range, then the matrix in Figure
5-20 is used.
AMINES &
ALKANOI AMINES
NALOGENATED CMPOS
PEROXIDES & ETHERS
ALDEHYDES A
KETONES
MONOMERS ft.
POLYMERIZABLE ESTERS
ALKVLENE OXIDES.
NITRILES &ACID ANHYDRIDES
OXIDIZING AGENTS
1
y
^
X
X
2
X
x
3
x
4
x
5
X
6
ACIDS
CAUSTICS
AMINES ft
ALKANOl AMINES
MALOGENATED CMVOS
fCMOXIDESftETMERS
AIDE MYOf S ft
KETONES
MONOMERS ft
ALKVLENE OXIDES
OXIDIZING AGENTS
1
X
X
X
X
X
X
2
X
X,
X
X
X
1
X
x
X
X
4
x
X
5
x
6
J
x •
DENOTES INCOMPATIBILITY
DENOTES INCOMPATIBILITY
Figure 5-19.
Compatibility matrix
for neutralized
hazardous wastes [1].
Figure 5-20.
Compatibility matrix
when wastes cannot be
neutralized [1].
5.5.2 Liquid Feed and Blending Equipment
Liquid blending or mixing of hazardous wastes is done as part of an overall
liquid feed system, which includes a feed pump, usually some recirculation to
the mix vessel, and associated piping to the incinerator.
An example of a mixing vessel is shown in Figure 5-21. For hazardous waste
blending, the vessel is always closed-top rather than open-top to prevent
splashing and vapor escape. Impeller mixer drives, both direct drive and gear
drive, are available. The shaft length and number or configuration of impel-
lers must be based on the geometry of the tank and viscosities of the waste.
Generally, fuel blending requires a mild agitation or intensity of blending,
and the use of baffles increases the turbulence and mixing characteristics.
Where conditions warrant extreme safety, the blending and feeding process can
be augmented by the use of a pneumatic compressed air (or gas mixer motor,
inert gas blanketing of the mixing vessel, and pneumatically-driven diaphram
feed pump. The pumps used to transfer the wastes from storage to blending can
also be pneumatic diaphram pumps.
5-49
-------
Figure 5-21.
Example of a baffled
mixing vessel [14].
If the type of incinerator can handle a slurry feed, the piping system should
be designed to handle slurries. A slurry piping system has a minimum diameter
of 4-6 times the particle size being pumped. All piping is recirculated to
prevent settling, and possibly, mechanically comminuted to destroy any
aqalomerations which would cause plugging problems. A careful monitoring or
the pump discharge pressure allows the operator to determine whether the feed
pump Tsbeing influenced by the mixer (entrained air), as a check of slurry
density, and to point to plugging problems. Figure 5-22 shows a slurry
injection and monitoring system.
SLURRY
CONTROL
PANEL
I SLURRY GUN
I PRESSURE
| GAGE
HEADER
PRESSURE
GAGE
HEADER
PRESSURE
TRANSMITTER
SLURRY GUN
PRESSURE
TRANSMITTER
2-1/2" SLURRY HEADER
SLURRY
aow
FLUID BED
CHAMBER
.WATER COOLED
SLURRY NOZZa
Figure 5-22. Slurry injection and monitoring system.
5-50
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When slurries cannot be fed to an incinerator, the feed lines to the mixing
tanks are filtered to prevent solids from reaching the burner nozzles.
Liquid streams can carry impurities of every sort. Furthermore, they may be
highly viscous, which makes handling and atomizing difficult. Liquids should
generally have a viscosity of 10,000 SSU or less to be satisfactorily pumped
and handled in pipes. For atomization, a viscosity of 750 SSU is the maximum.
Viscosity can usually be controlled by steam heating with tank coils or in-
line heaters, but careful notice of the flash points must be taken If pre-
heating is not feasible, a lower viscosity and miscible liquid may be added
to reduce the viscosity of the mixture.
A feed system may have two or more recirculating loops installed, chiefly to
keep any solids remaining in the liquid mixture from settling and plugging
pipelines. Figure 5-23 illustrates an example of multiple recirculation.
TO INCINERATOR
STIRRER
TANK
\
MOYNO'
PUMP
CV- GATE VALVE OR GLOBE VALVE
PRV-PRESSURE RELIEF VALVE HEARTH
Figure 5-23. Liquid feed system with redundant recirculation.
5.5.3 Pumps and Piping
Pump and piping materials of construction are designed to be suitable for the
liquids encountered (See Section 5.13). While centrifugal pumps can be used
to feed liquids and/or slurries, positive displacement-type (PD) pumps are
preferred. Unlike centrifugal pumps, they afford a reasonably tight shut-off
and prevent siphoning when not in operation. Table 5-4 ^splays the materials
of construction for positive displacement pumps. Figure 5-24 provides a pump
classification chart.
5-51
-------
TABLE 5-4. MATERIALS OF CONSTRUCTION FOR POSITIVE DISPLACEMENT PUMPS
Pump body
Plunaer pump
Plunqer Lantern ring
Diaphragm pump
Diaphragm
or bellows
Steel
Iron
Stainless steel
PVC
Alloy 20
Monel
Carpenter 20
Stainless steel
Ceramic
Monel
Stainless steel
Allow 20
Hastelloy "C"
PVC
Alumina-ce ramie
Elastometer
Teflon
Polyethylene
Buna N
Neoprene
Viton
Resistant steels
Check valves
Valve body
Ball
Ball seat
Steel
Stainless steel
PVC
Alloy 20
Hastelloy "C"
Monel
Stainless steel
PVC
Hastelloy "C" to "D"
Alumina-ceramic
Stainless steel
PVC
Alloy 20
Monel
Hastelloy "C"
CENTRIFUGAL
HORIZONTAL
GENERAL SERVICE
CHEMICAL (ANSI)
HIGH TEMP. (API)
MULTISTAGE
SLURRY
SELF-PRIMING
MIXED FLOW
PROPELLER
VERTICAL
GENERAL SERVICE
TURBINE TYPE
VOLUTE TYPE
SUMP TYPE
CHEMICAL TYPE IN-LINE
HIGH-SPEED IN-LINE
CAN TYPE (LOW NPSH)
POSITIVE
DISPLACEMENT
ROTARY
GEAR
SCREW
PROGRESSING CAVITY
LOBE
VANE
RECIPROCATING
DIRECT ACTING TYPE
POWER FRAME TYPE
PLUNGER OR PISTON
HORIZONTAL OR VERTICAL
CONTROLLED VOLUME
PLUNGER TYPE
DIAPHRAGM TYPE
NUMBER OF FEEDS
TYPE OF STROKE
ADJUSTMENT
Figure 5-24. Pump classification chart.
5-52
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A relief valve is usually provided downstream of PD pumps, of sufficient
capacity to prevent excess pressure in the system. The relief valve discharge
is then piped back to the supply source or to the suction side of the pump.
5.5.3.1 Positive-Displacement Pumps—
Positive-displacement pumps have as their principle of operation the displace-
ment of the liquid from the pump case by reciprocating action of a piston or
diaphragm, or rotating action of a gear, cam, vane, or screw. The type of
action may be used to classify positive-displacement pumps as reciprocating or
rotary. Figures 5-25 and 5-26 depict some typical pumps of each type. When a
positive-displacement pump is stopped, it serves as a check valve to prevent
backflow.
0 ISCHIICE fO»l MO*
counter i*g
IOOS
countc r mi
loos
Figure 5-25.
Reciprocating pumps: (a) Principle of reciprocating pump,
(b) principle of fluid-operated diaphragm pump, (c) direct-
acting steam pump, (d) principle of mechanical diaphragm pump,
(e) piston-type power pump, (f) plunger-type power pump with
adjustable stroke, (g) inverted, vertical, triplex power pump
[20].
5-53
-------
SUCTION 01 SCHARG E
0 I SCNARGE
DISCHARGE DRIVING GEAR
D I SCHARGE
SUCTION
0 I S C H A R C E
s H u T T L E~li;' )CR o * ° *
I L 0 C H //^'
ECCENTRIC
ROLLER ECCENTRIC
h '
FLEXIBLE RUBBER
JlHIjt,
PISTON
..^^.-.-'JyCT)""'
^•^^•^ECCENTR
SQUEEZE RING
(k) shuttle-block pump, (1) squeegee pump, (m) neopre
pump [20] .
centrifugal pumps.
« •
cona.n.nt5.
of emissions.
h^dlin, of fluids can resuU in the r£as«
reciprocating and centrifugal pu^p. can be source.
5-54
-------
D I SCHARIf
NOZZLE*
•PELLER
ISCHARGE
OIFFUSER
IMPELLER
IMPELLER
EVE
. »OIUTI DIFFUSION
IMPELLER VINES »*NES
DISCHARGE
-~ -IIS OR
/[ ] PARTIAL
SHROUD
^-SM R 0 U D S
- SUCTI ON '.*•••!
VANES
f
Figure 5-27.
Centrifugal pumps: (a) Principle of centrifugal-type pump,
(b) radial section through volute-type pump, (c) radial section
through diffuser-type pump, (d) open impeller, (e) semi-
enclosed impeller, (f) closed impeller, (g) nonclog impeller
[20].
The opening in the cylinder or fluid end through which the connecting rod
actuates the piston is the major potential source of containants from a recip-
rocating pump. In centrifugal pumps, normally the only potential source of
leakage occurs where the drive shaft passes through the impeller casing.
Several means have been devised for sealing the annular clearance between pump
shafts and fluid casings to retard leakage. For most applications, packed
seals and mechanical seals are widely used.
Packed seals can be used on both positive displacement and centrifugal type
pumps. Typical packed seals generally consist of a stuffing box filled with
sealing material that encases the moving shaft. The stuffing box is fitted
with a takeup ring that is made to compress the packing and cause it to tight-
en around the shaft. Materials used for packing vary with the fluid's tempera-
ture, physical and chemical properties, pressure, and pump type. Some
commonly used materials are metal, rubber, leather, and plastics.
Lubrication of the contact surfaces of the packing and shaft is effected by a
controlled amount of product leakage to the atmosphere. This feature makes
packing seals undesirable in applications where the liquid can cause a pollu-
tion problem. The packing itself may also be saturated with some material
5-55
-------
such as graphite or oil that acts as a lubricant. In some cases cooling or
quench water is used to cool the impeller shaft and the bearings.
The second commonly used means of sealing is the mechanical seal ^ch was
developed over a period of years as a means of reducing leakage from PU">P
allndsThis type of seal can be used only in pumps that have a rotary shaft
miSon! A sLp£ mechanical seal consists of two rings with wearing surfaces
at right angles to the shaft. One ring is stationary while the °ther is
attached to the shaft and rotates with it. A spring and the action of fluid
nressure keen the two faces in contact. Lubrication of the wearing faces is
accomplished^ a thL film of the material being pumped. The wearing faces
th: ==ssah?s 2j^H5^J?ira=: =tSs:
-sM1?iS.s.pfs:rss iss 5%ff ^rciSS'S'
are made of carbon.
Emissions to the atmosphere from centrifugal pumps may be controlled in some
cases by use of the described mechanical-type seals instead of P?ckViands.
For cases not feasible to control with mechanical seals, specialized types of
pumps, such as canned, diaphragm, or electromagnetic, are required.
Another specialty category is the sealed pump which has no eternal seal or
. ,r, . «i__ ^ _.-:-»« *.mAe a*-a t-Via ranned-rotor and tne magnetic.
.
.
blesome high-preslure stuffing box. The centrifugal- type pumps follow the
same hydraGli? performance rules as conventional centrifugal pumps. Because
oftheir small size, these pumps show a rather low ««««y{*uj;"
dangerous applications, efficiency must often be sacrificed for safety.
and piping systems are to prevent escape of
pr
Squid andYto Jeep to a minimum the quantity lost if the 1-^ does escape
Inherent safety and freedom from human failure can, to a considerable extent,
be built into a hazardous/ flammable liquid system. Some design
recommendations which help to attain the above objectives are listed below:
(1) Complete automatic sprinkler protection is provided in indoor areas
where pumps, piping, tanks, and other parts of hazardous liquid
transfer systems are located. In well-drained areas, sprinkler
discharge of 0.30 gpm/sq ft of floor area is usually recommended to
prevent structural and equipment damage.
(2) Indoor piping is located either overhead or in trenches in the
( ' P
iHQOO4 U^UAiftM •" ^**^»**w^«« •»^««——
floor. Overhead piping is normally installed
beams or along walls at least 6 ft above floor level. If piping^is
located in a French in the floor, the trench is covered with remov-
able steel plates and a trapped drain installed to a point of safe
5-56
-------
discharge. Positive-exhaust ventilation is provided in the trench,
or the trench is backfilled with sand for liquids having closed-cup
flash points below 110°F.
(3) Provisions are made to clean out the piping and equipment when long
or scheduled shutdowns occur. This is usually done by purging with
steam. The condensate is then collected and treated as a wastewater.
(4) Pipe materials are used which are chemically resistant to the liquid
handled, which have adequate design strength to withstand the maxi-
mum service pressure and temperature, and which, when possible, are
resistant to mechanical damage or thermal shock. Cast-iron, soft-
rubber, or thermoplastic pipe or fittings of low melting point are
never used.
(5) If corrosive liquids or high standards of purity make special pipe
necessary, the use of stainless steel, nickel alloys, or other
materials having high resistance to heat and mechanical damage or
steel pipe with tin, glass, plastic, rubber, lead, or other lining
is preferred to more fragile piping. If problems of corrosion,
contaminations, or sanitation are the controlling factor, the use of
carbon, graphite, glass, porcelain, thermosetting-plastic, or hard-
rubber pipe is acceptable. Where specifically needed for the liquid
being handled, aluminum alloy, aluminum bronze, or lead pipe is
acceptable. Extra care is then used in locating, guarding, and
supporting specialty piping against mechanical injury.
(6) Each waste material pipeline is clearly marked by lettering (coded
or otherwise), color banding, or complete color coding to indicate
the product transferred therein. The coding normally conforms with
company policy or standard plant practice which, in turn, should
conform with state or federal requirements.
(7) Each oil or hazardous material product-fill line which enters a tank
below the liquid level has a one-way flow check valve located as
closely as possible to the bulk storage tank. In addition to confin-
ing the product to the tank, in the event of valve or pipeline
failure, the check valve permits overhaul of the main shut-off valve
and should aid in preventing shock loading of the pipeline and
valves from a "slug" of the tank content caused by backflow into an
empty fill line. The waste feed flow in suction lines is controlled
by use of a positive displacement pump.
(8) Buried pipelines are generally avoided. When they do occur however,
buried installations have a protective wrapping and coating and are
cathodically protected if soil conditions warrant. A section of the
line is then exposed and inspected regularly. This action is normal-
ly recycled until the entire line has been exposed and examined on a
regularly established frequency. An alternative would be the use of
exposable pipe corridors or galleries.
5-57
-------
(9) When a pipeline is not in service, -the terminal connection at the
transfer point is capped or blank-flanged, and marked as to origin.
(10) Wood-to-metal is normally avoided as a pipeline support since it is
apt to retain moisture and cause pipeline corrosion which, when
coupled with the abrasive action caused by the pulsating action of
the line, could cause line failure with resulting leakage. Supports
are generally designed with only a minimum point of surface contact
that allows for the pulsating movement (expansion and contraction)
inspections at which time the general condition of items, such as
flange joints, valve glands and bodies, catch trays, pipeline
supports, locking of valves, and metal surfaces, are assessed.
(12) Elevated pipelines are also subjected to constant review to insure
that the height of vehicular traffic granted plant entry does not
exceed the lowermost height of the elevated line; gate check-in and
in-plant travel are routes which warrant attention in this respect.
(13) Double-walled piping and/or flange shielding may be necessary for
some above-ground pipelines carrying an especially hazardous or
toxic waste stream if the pipeline intersects critical locations
such as highways, driveways, railroads, or small watercourses. An
example is illustrated in Figure 5-28.
(14) As far as practical, all pumps feeding the blender are located as
close as possible to the storage tank.
1. A SHIELD PREVENTS SPLASHING IF THE FLANGE FAILS.
2. OUTER CONCENTRTIC PIPE PREVENTS ESCAPE (AND
INDICATES THE FAILURE) IF INNER, LIQUID-CARRYING
PIPE FAILS.
Figure 5-28. Two safeguards for piping of highly toxic liquids [21]
5-58
-------
Many liquid wastes are solids at room temperature or become highly viscous at
lower temperatures, and require heated piping to keep them in a fluid state
suitable for transfer through the system. Liquids from heated tanks can
usually be handled by providing adequate insulation on the pipe and fittings.
The following methods of applying heat to piping systems are considered
acceptable .-
(1) Flammable-liquid lines are often steam-traced. The minimum steam
pressure needed is used to make the liquid fluid, and a regulator is
provided in the steam line with a relief valve downstream of the
regulator set somewhat higher. The pipe and tracing are enclosed
with noncombustible insulation.
(2) Electric heating cable is usually fastened along the pipe or wound
spirally around it and the whole covered with noncombustible insula-
tion. No splices in the cable should be made, and all connections
are located outside the insulation-covered pipe. Individual thermo-
static controls for each cable section should be provided and protec-
ted with a fuse or fused disconnect switches of as low a rating as
practical. Outdoors, weather-proof enclosures are provided for
thermostats, plug assemblies, and switches, and in all installations
are located safely away from the pipelines and out of the flammable-
liquid area. Accessories will introduce a hazard unless located so
that the make-and-break contacts will function in a nonexplosive
atmosphere.
(3) Thermal-electric conduction may be utilized by passing a low-voltage
alternating current though the pipe. This method is commonly used
to maintain a constant temperature in a system of piping when materi-
al in the storage tank has been previously wanned. Sufficient heat
is supplied to the piping to compensate for normal heat loss in the
system without raising the temperature of the liquid in transfer.
Thermal-electric conduction systems is normally installed and tested
as complete units by the manufacturer or his qualified agent.
Sections of the piping to be heated are insulated by electrically
nonconductive fittings from unheated sections to confine the current
paths and to eliminate any current leakage at hazardous locations.
For thermal-electric conduction systems the following
recommendations usually apply:
(a) An automatic high-temperature-limit safety cutoff switch is
provided in each circuit of each system to prevent overheating
of liquid in event of failure of the operating temperature-
control thermostat.
(b) Each circuit is protected with fuses or fused disconnect
switches of the lowest practical rating.
(c) All parts of the piping and fittings are enclosed in electri-
cal- and thermal-insulating covering to prevent accidental
grounding of the system.
5-59
-------
(d) All switches, transformers, contactors, or other sparking units
are located in a safe area away from any flammable liquid or
vapor.
(e) The system is inspected and tested periodically to insure its
continued safe operation. Maintenance of the installation is
the responsibility of trained employees.
5.5.4 Valving and Controls
Valve functions can be defined as follows:
(1) On/off service
(2) Throttling service
(3) Prevention of reverse flow, or backflow
(4) Pressure control
(5) Special functions:
(a) Directing flow
(b) Sampling service
(c) Limiting flows
(d) Sealing vessel or tank outlets
(e) Other.
Valve selection requires consideration of three basic and critical details:
(1) The flow control element
(2) The regulating mechanism
(3) The seal to contain the fluid within the valve.
In addition to these three important design aspects, features such as mechani-
cal strength, materials of construction, dimensional arrangement, and types of
end-connections are considered.
Valves are weak links in fluid transfer systems as regards leaks and fugitive
emissions. There are three types of leakage:
(1) Process fluid escapes downstream, past flow-control element in
closed position. Identified as "flow seal" leakage.
(2) Process fluid escapes to the outside of the valve, from around the
stem and from the joints (bonnet) with the body. Identified as
either stem-seal or bonnet-seal leakage.
(3) Air leaks into the valve body and to the process medium under
vacuum.
Figure 5-29 shows a gate valve with the possible leakage areas around the stem
packing, the bonnet assembly, and between the valve stem and packing gland.
5-60
-------
-V--A POSSIBU
LEAK AREAS
Figure 529.
Three areas of a typical gate valve that
can leak and result in fugitive emissions [2].
5.5.5 Valving and Control Safety Consideration
5.5.5.1 Safety Shutoffs—
Hazardous and flammable-liquid pumping and piping systems are equipped with
emergency shutoffs to stop the flow of liquid in event of fire or accidental
escape of liquid or vapor. This can usually be done by safety shutofi valves
and/or positive-displacement pumps. In general, these devices are arranged
for automatic operation in event of fire and for manual or automatic operation
in event of accidental escape of liquid. If the location of a possible fire
can be accurately determined, as would be the case at dispensing locations,
remote actuation is not necessary. If a fire could occur anywhere at an
extensive installation, provision for remote actuation of the main safety
shutoff valve will be needed.
(1) Safety shutoff valves are needed in flammable-liquid systems in the
following locations:
(a) At connections on supply and feed tanks where transfer is by
gravity, centrifugal pump, inert-gas pressure, or other means
that permits the maintenance of continuous pressure in the
system. The possibility of siphon action through a centrifugal
pump requires installation of a safety shutoff valve on the
pump inlet.
(b) On feed lines where they enter important buildings or struc-
tures or on branch lines where they take off from main-supply
headers. The valve is located out of doors or immediately
adjacent to an exterior wall, accessible from outdoors.
5-61
-------
(c) On feed lines at dispensing locations.
(2) Safety shutoff valves may be of the diaphragm, solenoid, or weight-
or spring-operated fusible-element types. They generally
incorporate some of the following design features:
(a) Have bodies with the appropriate service rating for the maximum
pressure and temperature to be encountered. Bodies should be of
cast steel, except that bronze is acceptable in sizes of 2 in.
and less if under sprinkler protection.
(b) Close on failure of the operating electrical or air supply.
(c) Close in the direction of the liquid flow so that system
pressure tends to hold the valve in the closed position.
(d) Close against a pressure of at least 150 per cent of design
rating.
(e) Close within 5 seconds after actuation.
(f) Valve should not readily be bypassed, blocked, or otherwise
made ineffective.
(g) Have an indicator to show when the valve is open or shut,
except on packless solenoid types.
(h) Be manually reset, except where the valve-control circuit is
arranged for manual resetting.
(i) Have no direct connections between the liquid and air section
of diaphragm valves that might permit leakage of the liquid
past the packing into the air lines.
(j) Have packing and lubrication, if any, resistant to the liquid
being handled.
(3) Automatic operation of safety shutoff valves and/or direct-
displacement pumps is normally accomplished by one of the following
methods:
(a) Actuation by thermal devices located at the ceiling and above
the point of flammable-liquid use where spills may be expected.
(b) Release of a dead-man control.
(c) Operation of the fire-protection system. With automatic sprin-
kler systems, actuation may be by waterflow indicators, alarm
valves, or dry-pipe valves with hydraulic-pressure switches.
With special fixed extinguishing systems, actuation is by
pressure switches. Drain and alarm tests of sprinkler system
5-62
-------
are made during idle periods or arranged that they can be made
without operating the safety shutoff.
(d) If the piping contains fragile components such as rotameters
and sight glasses, the safety shutoff is actuated automatically
by excessive pressure drop downstream from such components.
(4) Arrange safety shutoff valves and/or positive-displacement pumps for
manual shutdown by use of one or more stop buttons or switches at
safe and accessible locations throughout the flammable-liquid
system. In general, such stop buttons or switches are located near
points of egress from the building or structure.
(5) Self-closing manual valves and dead-man controls of a type not
readily blocked open are recommended as emergency safety shutoffs on
small systems, where liquid transfer is intermittent, and on larger
systems that lend themselves economically to such an arrangement.
They require constant attendance by the operator and close auto-
matically if he leaves.
(6) If normal flow in piping is in one direction only and the piping
discharges to feed tanks, receivers, or other vessels so located
that a leak in the piping upstream of these vessels could be fed by
reverse flow through the piping, check valves are installed in the
piping as close to the vessel as possible to prevent the reverse
flow.
5.5.5.2 Gages. Meters, and Gage Glasses—
(1) Accessories on flammable-liquid piping systems, such as gages,
meters, gage glasses, hydrometers, and sight glasses are designed to
have strength equal to that of the piping system.
(2) Gage glasses are particularly susceptible to breakage. Their use is
generally discouraged.
(3) Restricted orifices are used in piping to gages and instruments to
reduce the amount of leakage in event of failure.
(4) Armored rotameters or instruments that read indirectly or sample a
proportion of the flow in preference to those that enclose the
entire stream or have the full flow directed to the glass reading
chamber are also used. Vents on air releases used in conjunction
with some metering devices are then piped to outdoors in order to
dispose safely of flammable liquid that may be discharged if the
float is inoperative.
5.5.5.3 Operating Controls—
(1) operating control valves are located in hazardous and flammable-
liquid piping systems so as to regulate the control and flow of
liquids to connected equipment and to isolate equipment for mainten-
ance purposes. Conventional types of valves are suitable for most
liquids. Valves are used having the appropriate service rating for
5-63
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the maximum pressure and temperature to be encountered and packing
or lubrication resistant to the liquid being handled. Valve bodies
are normally of cast steel, except that bronze is acceptable on
piping 2 in. or less in size in sprinklered locations. Cast-iron
bodies are usually not used. If corrosive conditions or product
purity require the use of special materials of construction, stain-
less-steel, Monel, or lined-steel valves are preferred to those made
of more fragile materials.
(2) Valving is arranged to minimize the likelihood of improper operation.
Rising-stem or other valves that indicate whether open or closed are
preferred. The following recommendations for valve arrangements are
generally followed where applicable:
(a) Three-way two-port valves are used at all branch lines so that
flow can only proceed through one line.
(b) Plug-cock valves are used with a slotted guard arranged so that
the handle can be removed only when the valve is in the closed
position. This arrangement will prevent discharge through
valves accidentally left open. One handle can serve all valves
on the system.
(c) Electrical or mechanical interlocks are provided between valves
so that the position of one valve with respect to another will
be automatically determined.
(3) Where the correct sequence of additions of waste materials to a
blending tank is of importance, sequence locks are used on valves in
pipelines.
(4) Hydraulic accumulators or safety relief valves are provided on
pipelines that can be valved off with liquid trapped between valves.
This prevents damage or overpressure from thermal expansion. The
discharge is piped from safety relief valves to a collection point.
(5) Tanks, mixers, and other equipment to which hazardous liquid waste
is transferred are arranged so as to prevent accidental overflow.
The best arrangement is a trapped overflow drain leading back to the
source of supply or to a point of safe collection. The capacity of
the overflow drain should be at least equal to that of the fill
pipe.
(6) If the equipment normally operates under pressure so that an over-
flow drain is not practical but overflow is possible during filling
because of open manholes or sampling connections, a liquid-level
control is provided to stop the liquid flow by closing a valve or
stopping the pump or to sound an alarm if the maximum safe level is
approached or exceeded. Float valves or switches, pressure switches,
and various other liquid-level indicators are available and may be
used. Mechanical interlocking of valves on overflow drain and fill
5-64
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pipe can sometimes be arranged so that the overflow drain will be
open when the fill-pipe valve is open.
(7) The use of accurate measuring devices, such as dispensing meters,
measuring tanks, or weight tanks will assist greatly in the preven-
tion of overflows. Dispensing meters permit a predetermined amount
of liquid to pass and then automatically stop the delivery. Such
meters control a spring-loaded quick-action valve that should be
designed for manual starting with a hand-trip emergency shutoff.
(8) If control valves are to be remotely actuated, valves are chosen
having characteristics described in recommendation 2 of Safety
Shutoffs and arranged for operation in an emergency situation.
5.5.6 Solids Feeding Equipment
Waste material is pneumatically, mechanically, or gravity fed into an inciner-
ator capable of burning solids. Normally, heterogeneous waste material must
be reduced in size (shredded, pulverized, etc.) to facilitate the feed system
operation and allow injection, distribution, and combustion within the
incinerator.
In addition to reducing moisture content and waste material size, separation
of noncombustible material such as ferrous and nonferrous metals may often be
required. The former is removed using magnetic separators. Nonferrous metals
are commonly removed using ballistic-type separators.
To reduce the size of waste materials for easier handling and feeding, shred-
ders are used. Also, to expose all surfaces of hazardous waste containers
(metal and fiber drums), it is usually necessary to shred the containers. A
shredder capable of consuming 55-gallon steel drums has to be a rugged unit
capable of containing dusts and mists of toxic materials as well as particles
of steel thrown around at high velocity. This type of potential danger-
indicates a need for a hopper feed system to enclose flying debris, with
mechanical feed from a conveyor so that plant personnel need never be in the
vicinity of the hopper opening during operation. The hopper is elevated for
gravity feed into the shredder, which also may be above ground level and well
ventilated. A suction fan can then draw fumes and dust from the shredder into
the incinerator or an alternate collection device.
A shredder capable of consuming 55-gallon drums would probably have a capacity
for handling material several times as fast as the incinerator. Thus some
silo storage is necessary to safely contain the shredded material. The
material discharged from the silo would go directly into the incinerator.
A shredding operation normally consists of a shredding unit and a transfer
network including a variety of conveyors and feeders. Several types °^ shred-
ding devices exist: vertical and horizontal axis hammer mills, v*rt"al a*"
grinders, and horizontal axis impactors,- horizontal hammer type shredders are
the most common.
5-65
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Unlike most other rotating equipment (pimps, fans, turbines, etc.), there is
very little design criteria for predictable performance of mixed solid waste
shredders. Size, style, and power selection is on an empirical basis, and
this is not likely to change in view of the infinite types and combinations of
input material.
There are three basic types of horizontal shaft swing hammer type shredders:
(1) Topfeed, single direction rotor rotation
(2) Topfeed, reversible rotor rotation
(3) Controlled feed, single direction rotor rotation.
Figure 5-30 illustrates a cross-sectional view of a horizontal axis shredder.
FEED
CONVEYOR
\
FEED MATERIAL
FEED CHUTE
HAMMER
LINERS
MAIN FRAME
REJECT
POCKET
BREAKER PLATE
FOUNDATION
DISCHARGE
CHUTE
DISCHARGE
GRATE
DISCHARGE
CONVEYOR
Figure 5-30.
Cross-section through a nonreversible
horizontal shredder [22].
5.5.6.2 Explosion Suppression and Safety Considerations for Shredders--
The primary explosion in a shredding system is a gas explosion caused by a
friction spark and sometimes followed by a more violent dust explosion.
Explosive dust mixtures of the type most likely to form in a solid waste
shredder require a higher energy level for ignition than available from a
friction spark. Explosion suppression systems have proved effective for gas
and dust explosions on municipal solid waste shredders and are used on most
installations. Today, most systems use a demand-inerting suppression system,
whereby metal hemispherical containers release a suppressant in advance of a
flame front. Such containers are connected to the shredding chamber by piping
to channel the suppressant toward the interior of the chamber to provide
blanket coverage. The most popular suppressant is Halon (short for
5-66
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halogenated hydrocarbon), a family of chemicals which possess unique
properties with regard to fire extinguishing.
Also, sufficient pressure relief area is provided in the shredder and connect-
ing superstructures such as hoods, ducts, or any connected enclosure. Except-
ing the shredder, this can be by means of hinged flaps, tethered blowout
panels, and flexible flaps.
In addition, other means for minimizing personal injury and building damage
are [23]:
(1) Rigid enforcement of off-limits areas for roving personnel.
(2) Complete enclosure protection for the shredder operator.
(3) Separate or detached shredder building enclosures with blow-out
sidewall and roof panels.
(4) Partially open walls and/or roof.
5.5.6.3 Feeders—
Critical components in any system handling bulk solids are the feeders, which,
in conjunction with conveyors and other handling equipment, transfer solids at
a controlled rate from storage into the process, or from point-to-point within
a process. Feeders may be called upon to transfer materials from railcar to
storage bin, from storage bin to conveyor, or from conveyor to the incinerator.
There are four major types of solids feeders:
(1) Rotary
(2) Screw
(3) Vibrating
(4) Belt
Many specialized feeders are also available. Table 5-5 relates feeder types
to material characteristics. The most common types of feeders which will be
encountered in handling hazardous solid wastes are belt feeders and screw
feeders.
Both belt feeders and screw feeders have their own limitations. Steps must be
taken to alleviate dusting during operation of belt feeders. Total dust con-
trol can be assured only by enclosing the feeder with the proper dust entrain-
ment hoods. Most manufacturers furnish enclosures for belts up to about 36
inches wide. These housings can be made gas-tight for inert-gas purging.
However, if the user does not monitor feeder operation, or if a poor hopper
design allows powder to avalanche onto the feeder belt, or if a dust collec-
tion system has not been provided to remove particles as they become airborne,
the enclosure will serve only to contain the dust so that it eventually buries
the feeder.
Caution is advised when using screw feeders with sticky or very cohesive mate-
rials. Such materials can build up in short pitch sections, and conveying
will cease. For these services, longer-pitch, smoothly surfaced flights,
multiple screws with overlapping flights, or ribbons instead of solid flights
are normally specified.
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TABLE 5-5. FEEDERS FOR BULK MATERIALS
Material characteristics'
Feeder type
Fine, free-flowing materials
Nonabrasive and granular materials,
materials with some lumps
Materials difficult to handle
because of being hot, abrasive,
lumpy, or stringy
Heavy, lumpy, or abrasive materials
similar to pit-run stone and ore
Bar flight, belt, oscillating or vibrat-
ing, rotary vane, screw
Apron, bar flight, belt, oscillating or
vibrating, reciprocating, rotary
plate, screw
Apron, bar flight, belt, oscillating or
vibrating, reciprocating
Apron, oscillating or vibrating,
reciprocating
Dust leakage around covers and along shaft seals is a common problem
screw feeders. "Dust tight" means little in a specification. Because this is
an important requirement, "gas tight" to about one inch w.c. (water column)
pressure is a term used. To ensure continued dust control, followup is normal-
ly needed during operation to make sure operators maintain seals, gaskets, and
covers. Shaft seals are difficult to keep dust tight, especially if the
trough is gas-purged. Even with the variety of seals offered, most will leak
dust within a few hours unless shaft runout at the seal area is minimized
There is no standard industry specification covering runout; as much as 1/32
in runout is not unusual. Manufacturers will furnish special construction
for tight sealing, if this requirement is spelled out clearly in the
specification.
Solid Waste Charging To Combustion Zone—The methods of feed to the combusion
zone can be broken down as follows:
(1) Batch
(a) open charging
(b) air lock feeders
(2) Continuous
Batch open charging can be as simple as gravity feeding solid waste into a
chute leading to the combustion zone, as in a rotary kiln incinerator.
An example of a batch air-lock feeder can be a charging hopper located above a
rotary kiln inlet, charged by a grapple which is controlled from a fully
air-conditioned operator cab, sealed against the bin space, using TV cameras
and TV screen in a partially automatic, partially manual operation. The
rotary kiln inlet is sealed from the bin space by a lock fitted with two
sliding gates. When the inclined sliding gate in the drop chute of the rotary
kiln inlet is closed, a horizontal sliding gate located in the charging hopper
will open.
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An example of a continuous solids feed is given in Figure 5-31, which illus-
trates a screw conveyor carrying sludge to a rotary feeder which is then
pneumatically conveyed to a spin air nozzle within a fluidized bed incinerator.
TO SCRUBBER
PNEUMATIC
SLUDGE FEED
BURNER
PILOT GAS
AIR BLOWER
Figure 5-31. Continuous feeding of sludge to fluid bed incinerator.
5 5 6.4 Container Feeding Equipment—
For the most part, disposal technology for filled containers is appropriate
for toxic materials and for materials which are not readily removable from the
container. When opening the container might be harmful to operations personnel,
the container should preferably be processed within a closed system
more, if the material cannot be easily poured, co-disposal of both the
chemical and the container is preferable.
There are three basic types of automated container feeding equipment to
incinerators:
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(1) Conveyor to air-lock charging to rotary kilns.
(2) Hydraulic drum and pack-feeding mechanisms.
(3) Conveyor to air-lock vestibule with puncturing apparatus to thermal
treatment chamber.
Figure 5-32 illustrates a schematic diagram of a rotary kiln incineration
system using air-lock charging of containers. The general practice of drop-
ping small containers into a rotary kiln without emptying them has process
disadvantages. Occasionally, there will be deflagrations with strong soot
generation and excessive thermal and mechanical loading of the kiln refractor-
ies resulting from this practice. A separate explosion vent for the charging
system is required to handle possible explosions.
on. TAIK
SECONDARY
COMBUSTION CHAMBER
500-«0f
VEN7URI 6.5" H#>
TO STACK
PAC CONVEYOR
5.0)0 dm
CHAMBER
UCO - 1800°F
Figure 5-32.
Continuous type containerized toxic
material thermal disposal process [24].
A different type of container handling, feeding, and thermal treatment system
is illustrated in Figure 5-33. The process includes a remote handling opera-
tion and a completely enclosed cannister punching operation. Containers are
then thermally cleaned in the first thermal stage with the controlled
volatilization of toxic chemicals.
The process described is excellent in the protection afforded to the operators
by the remote automated handling, punching, and thermal disposal approaches.
A wide range of containers or cannisters can be processed, including 55-gallon
drums, chemical ton containers, munition cannisters, projectiles, and cans.
Contaminated filter media have also been detoxified using the same technique.
5-70
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u
FUME INCINERATOR
WASTE IN
DRUMS
PUNCHING
o o oo o
STACK
SCRUBBER
THERMAL TREATMENT
COOLING
oooooooooo oooooop 0*0 oooooooo
II
Figure 5-33. Liquid waste incinerator schematic [24].
The thermal furnace uses a containerized conveyor to transport the cannisters
through the thermal process chamber, which is equipped with entry and exit
vestibules with gas-tight doors at either end to facilitate the total contain-
ment of vapors which might escape from opened containers. Mechanized punching
of the cannisters takes place within the entry vestibule.
5.5.7 Backup/Redundancy Provisions
The functional diagram of an incineration facility indicates that most compon-
ents of the system are in a "series" configuration; each series component must
be adequately functioning to avoid degraded performance. A few process com-
ponents may be in a "parallel" configuration allowing a switchover to another
component when problems are detected with an on-stream component. Examples
are waste feed line filters which will usually have two or more units in
parallel. Feed pumps are typically redundant; if plant processing rates are
determined to be especially critical, redundant level monitors or extra gaging
in critical storage tanks and silos, and flow monitoring cells may need backup
devices to assure safety. A detailed failure mode analysis of each particular
incinerator facility will identify the most likely potential malfunctions of
each process element and point toward which safety systems cannot afford to
fail for pointing out redundancy needs at a particular facility.
5.5.8 Waste Processing Instrumentation
An automated instrumentation system is used to transfer hazardous wastes from
storage to the incinerator. Electrical and/or pneumatic systems permit obser-
vation of control, for all material handling, from a graphically illustrated
control panel which shows such things as discharge valve positions, pump motor
operation, storage tank and bin levels (high and low), storage tank agitator
operation, and liquid or solid waste flow. Equipment operation including belt
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conveyors, shredder, bucket elevator, or screw conveyors to the incinerator
can also be displayed.
5.6 COMBUSTION PROCESS MONITORING
Before incineration process conditions can be controlled automatically they
must be measured with precision and reliability. Instrumentation for an
incineration process is essential because of the variability of the many
factors involved in attaining good combustion. For example, as the heat
content of the solid waste rises, changes in the combustion process become
necessary. Instrumentation indicates these variations so that automatic or
manual control adjustments can be made.
The uses of instrumentation and controls include means of process control,
protection of the environment, protection of the equipment, and data collec-
tion. A control system must have four basic elements:
(1) the standard of desired performance;
(2) the sensor (instrument) to determine actual performance,-
(3) the capability to compare actual versus desired performance (error),
and
(4) the control device to effect a corrective change.
The four major factors governing incineration efficiency for a given waste
feed are temperature, residence time, oxygen concentration, and the turbulence
achieved. Chapter 4 discusses the significance of these factors in incinera-
tor design and operation. Methods to determine appropriate conditions of
temperature, residence time, etc., for a given waste/incinerator combination
are also described in Chapter 4.
Temperature in the incinerator can be directly measured. Instrumentation is
also available to directly monitor oxygen concentration in the combustion gas
to insure that excess air levels are maintained. Residence time and mixing
efficiency cannot be directly measured, however, so other parameters
indicative of these conditions need to be measured instead.
Gas residence time in the combustion zone depends upon the volume of the
combustion chamber and the volume flow rate. Since the volume of the chamber
is fixed for a given unit, residence time is directly related to combustion
gas volume flow rate. Therefore, measuring this flow rate is equivalent to
residence time measurement for a given incinerator.
Mixing in liquid waste incinerators or afterburners is a function of burner
configuration, gas flow patterns, and turbulence. Burner configuration and
gas flow pattern are a function of the incinerator design and will not vary
from baseline conditions. Turbulence is determined by gas velocity in the
combustion chamber, which is proportional to gas volume flow rate. Therefore,
combustion gas flow rate is an indicator of mixing as well as residence time
in liquid injection incinerators.
In incinerators burning solid hazardous wastes, other factors need to be con-
sidered to determine solids retention time and degree of agitation. These
5-72
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factors, which vary from one type of incinerator to another, are discussed in
Section 5.6.4. Sections 5.6.1 through 5.6.3 discuss where and how
temperature, oxygen concentration, and gas flow rate can be measured.
5.6.1 Temperature Monitoring
Incinerator temperature is monitored on a continuous basis to assure that the
minimum acceptable temperature for waste destruction is maintained. This
requires one or more temperature sensors in the hot zone and a strip chart
recorder or equivalent recording device.
Generally, wall temperatures and/or gas stream temperatures are determined
using shielded thermocouples as sensors. Thermocouples are the most commonly
used contact sensors for measuring temperatures above 1,000°F. Specifically,
thermocouples can measure the following thermal parameters:
a. Average gas temperature - accomplished using a shielded thermocouple with
relatively large thermal capacity anchored to a relatively large mass.
The metering circuit is provided with a 30-second time constant to
further smooth and average the readings.
b. Instantaneous gas temperature - accomplished using a shielded thermo-
couple with very small thermal capacity with the output metered by a
circuit with a 1-second time constant. (Nominally, the reaction rates
within the hot gas stream should be strongly temperature dependent; they
thus should depend on the highest temperature to which the constituents
are exposed.)
c. Open flame temperature - obtained using an unshielded low thermal mass
thermocouple with the output metered by an amplifier with a 30-second
time constant.
d. Average wall temperature - obtained using a shielded thermocouple
imbedded in the refractory wall. (Here, the averaging is accomplished by
the thermal inertia of the refractory material.)
Optical pyrometers are not recommended for these measurements due to spectral
bias factors present in the combustion area which can cause unacceptable meas-
urement error.
The location at which temperature measurements are taken is important, due to
possible variations from one point to another in the combustion chamber.
Temperatures are highest in the flame and lowest in the refractory wall or at
a point of significant air infiltration. Ideally, temperatures are measured
in the bulk gas flow at a point after which the gas has traversed the combus-
tion chamber volume that provides the specified residence time for the unit.
Generally, temperature measurement at a point of flame impingement or at a
point directly in sight of radiation from the flame is not recommended.
Figure 5-34 shows the approximate measurement location.
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A INCINERATION TEMPERATURE
3 COMBUSTION PRODUCT 0, CONCENTRATION
C CAS ROW
COMBUST! ON AIR.
FUEL-
UQUIO WASTES •
A.B
LIQUID
INJECTION
NCINERATOf
OR
AFTERBURNER
FUEL
SOLIDS/SLURRY
WASTES
SLUDGE TO
IANOFIU
TRANSFER PUMP
Figure 5-34. Recommended temperature measurement points.
The types of thermocouples used include J, K, E, R, S, and B. The letter
symbols identifying the thermocouple types are those defined in ANSI Standard
C96.1. These symbols are in common use throughout industry:
Type J - Iron versus constantan (modified 1913 calibration)
Type K - Originally Chromel-P versus Alumel
Type R - Platinum 13% rhodium versus platinum
Type S - Platinum 10% rhodium versus platinum
Type T - Copper versus constantan
Type E - Originally Chromel-P versus constantan
Type B - Platinum 30% rhodium versus platinum 6% rhodium
Table 5-6 lists the limits of error for the common thermocouple types; most
manufacturers supply thermocouples and thermocouple wire to these limits of
error or better.
Since the thermocouple element in a thermocouple assembly is usually expend-
able, confonnance to established emf-temperature relationships is necessary to
permit interchangeability. Calibration of a thermocouple consists of the
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TABLE 5-6. LIMITS OF ERROR FOR THERMOCOUPLES [25]
Type
J
K
R, S
T
E
Temperature
range, °F
32 to 530
530 to 1,400
32 to 530
520 to 2,300
32 to 1,000
1,000 to 2,700
-300 to -75
-150 to -75
-75 to +200
200 to 700
32 to 600
600 to 1,600
Limits
Standard
±4°F
±3/4%
±4°F
±3/4%
±5°F
±1/2%
±2%
±1-1/2°F
±3/4%
±3°F
±1/2%
of error
Special
±2°F
±3/8%
±2°F
±3/8%
±2-l/2°F
±1/4%
±1%
±1%
±3/4°F
±3/8%
±2-l/4°F
±3/8%
B
1,600 to 3,100 ±1/2%
determination of its emf at a sufficient number of known temperatures such
that with some accepted means of interpolation its emf will be known over the
entire range in which it is to be used. The process requires a standard
thermometer with a high-level calibration to indicate temperatures on a stand-
ard scale, a means for measuring the emf of the thermocouple, and a controlled
environment in which the thermocouple and standard can be brought to the same
temperature [25].
Thermocouples use one of three different types of measuring junctions--
grounded, ungrounded, and exposed. The grounded junction is the most popular.
The ungrounded junction is the most rugged, but its speed of response is
slower than that of the grounded type. The unprotected exposed junction
responds the fastest but is more vulnerable to corrosion and mechanical
damage.
A complete thermocouple assembly consists of the following:
1. A sensing element assembly, including in its most basic form two
dissimilar wires joined at one end and separated by an electrical
insulator
2. A protection tube, either ceramic or metal, or a thermowell.
cases, both primary and secondary protection tubes are used
3. A thermocouple head or connector
In some
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4. Miscellaneous type hardware such as pipe nipples or adaptors to join the
protection tube to the head and thermocouple glands for mounting and
pressure sealing
Protection tubes and thermowells serve the double purpose of guarding the
thermocouple against mechanical damage and shielding it from corrosive atmos-
pheres. The choice of the proper material for the protection tube or thermo-
well is governed by the conditions of use and by the tolerable life of the
thermocouple. There may be times when the strength of the protection tube is
more important that the long term stability of the thermocouple. On the other
hand, gas tightness, resistance to thermal shock, or chemical compatibility of
the protection tube with the process may be the deciding factors [25].
The most common forms of protection tubes and thermowells and their applica-
tions are covered in the following subsections [25].
5.6.1.1 Metal Tubes—
Metal tubes offer adequate mechanical protection for base metal thermocouples
at temperatures to 1,423 K (1.100°F; 1,150°C). It must be remembered that all
metallic tubes are somewhat porous at temperatures exceeding 1,088 K (1,500 F;
815°C) so that, in some cases, it may be necessary to provide an inner tube of
ceramic material [25].
(a) Carbon steels can be used to 973 K (1,300°F; 700°C) usually in oxidizing
atmospheres.
(b) Austenitic stainless steels (300 series) can be used to 1,143 K (1,600°F;
870°C), mostly oxidizing although Types 316, 317, and 318 can be used in
some reducing atmospheres.
(c) Ferritic stainless steels (400 series) can be used from 1,248 K to
1,423 K (1,800°F to 2,100°F; 975°C to 1,150°C) in both oxidizing and
reducing atmospheres.
(d) High nickel alloys, Nichrome, Inconel, etc., can be used to 2,100°F
(1,150°C) in oxidizing atmospheres [25].
Where the protection tube is subject to high pressure or flow-induced stresses
or both, a drilled thermowell often is recommended. Although less expensive
metal tubes, fabricated by plugging the end of the protection tube, may satis-
fy application requirements, more stringent specifications usually dictate the
choice of gun-drilled bar stock, polished and hydrostatically tested as a
precaution against failures [25].
5.6.1.2 Ceramic Tubes—
Ceramic tubes are usually at temperatures beyond the ranges of metal tubes
although they are sometimes used at lower temperatures in atmospheres harmful
to metal tubes [25].
The ceramic tube most widely used has a Mullite base with certain additives to
give the best combination of mechanical and thermal shock properties [upper
temperature limit 1,923 K (3,000°F; 1,650°C)] [25].
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Silicon carbide tubes are used as secondary protection tubes. This material
resists the cutting action of flames. It is not impermeable to gases and,
where a dense tube is required, a nitride-bonded type material can be obtained
so that the permeability is greatly reduced [25].
Fused alumina tubes can be used as primary or secondary protection tubes or
both where temperatures to 2,253 K (3,600°F; 1,980°C) are expected and when a
gas-tight tube is essential. Fused alumina tubes and insulators should be
used with platinum-rhodium, platinum thermocouples above 2,200°F (1,200°C) in
order to ensure long life and attain maximum accuracy. [The Hullite types
contain impurities which can contaminate platinum above 2,200°F (1,220°C).
The alumina tubes are more expensive than the Hullite base tubes, but types
impervious to most gases to 2.088 K (3,300°F; 1,815°C) can be obtained] [25].
5.6.1.3 Metal-Ceramic Tubes—
"Cermets" are combinations of metals and metallic oxides which, after proper
treatment, form dense, high-strength, corrosion-resistant tubes usable to
about 1,698 K (2,600°F; 1,425°C) in most atmospheres [25].
5.6.2 Oxygen Monitoring
Oxygen concentration in the combustion gas is usually measured at a point of
high turbulence, after the gas has traversed the full length of the combustion
chamber. A good location for measurement is at the inlet to the duct leading
from the combustion chamber to the quench zone, immediately after the gas has
gone through a 90° turn. Figure 5-34 shows this location.
Oxygen measurements are made on a continuous basis. Commercially available
instruments are discussed in Section 5.9. Whichever type of sensor is used,
it is typically equipped with a gas conditioning system specified by the
manufacturer for the gas environment in which the instrument is used.
5.6.3 Gas Flow Measurement
Gas flow rates can be measured or approximated in several ways: by insertion
in the flue gas duct of an air pressure measuring element (e.g., pitot tube)
or by measuring the drop in pressure across a restriction to the gas flow
(e.g., baffle plate, venturi section, or orifice) downstream of the combustor.
Exhaust gas flow, however, is the most difficult flow measurement application
on the incinerator for many reasons:
(1) Because the gas is dusty, moist, and corrosive, pressure taps will tend
to plug. For this reason it is extremely important that the connection
to the duct be made sufficiently large and with cleanout provision.
(2) If the two pressure sensing points are at widely different temperatures,
the resulting difference in density of the gas in the connecting lines to
the instrument will create an error in measurement. For this reason,
avoid measurement across spray chambers or other locations where gas
temperature changes radically [26].
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(3) If taken across a restriction to gas flow, the fouling tendencies of the
dirty gas will cause the restriction to increase with time, thereby
changing the differential measurement for a given rate of flow [26].
For the reasons stated above, the usefulness of this measurement as an indi-
cation of quantitative flow is limited and care should be taken in this
application [26].
Flow measurements are performed at either of two locations: (1) in the duct
between the combustion chamber and quench zone, or (2) in the stack (Figure
5-34). Both locations have their advantages and disadvantages. In the com-
bustion chamber outlet duct, a sufficiently long length of duct may not be
available for flow pattern development. Access to this location can also be a
problem when the incinerator is vertically oriented and because of the neces-
sity to breech the duct at a high temperature point. High temperatures at
this location may require special materials of construction (e.g., inconel)
for measurement elements.
The advantages of flow rate measurement in the stack are relief of the prob-
lems associated with high temperature gas flow measurement, increased access-
ibility to the gas flow, and increased likelihood of having a proper section
of duct for the flow measurement. One minor disadvantage associated with this
position is the increased possibility that ambient air leaks into the system
upstream of the draft fan could bias the flow measurement. This is not a
common occurrence, however, and good facility management practice will
normally detect such leaks quickly.
Of the instruments available to measure gas flow in closed conduits, pressure
or velocity head meters are among the oldest and most common. The principal
shortcomings are the need for elements to be inserted directly into the flow
paths (in contact with th gas stream), making them susceptible to corrosion,
erosion, and fouling; the requirement for seals,- the likelihood that the con-
duit may have to be opened for inspection or service,- and permanent pressure
losses caused by restrictions placed in the channels.
Head-type flowmeters incorporate primary elements, which interact directly
with the streams to induce velocity changes, and secondary elements, which
sense the resulting pressure perturbations. The flow rate of interest is a
function of the differential pressures which can be detected.
5.6.3.1 Orifice Plates—
Orifice plates, the predominant primary flow elements, can yield accuracy and
repeatability of ±0.25 to 2% full scale at Reynolds numbers from 8,000 to
500,000 [26]. Units are offered in a variety of designs, with flow area
shapes which can be:
(1) Concentric
(2) Eccentric
(3) Segmental,
and profile cross sections which can be:
5-78
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(a) Square-edged
(b) Sharp-edged
(c) Quadrant-edged
(d) Double bevel
(e) Conical inlet.
Principal advantages include low cost, interchangeability, and installation
with minimal modification of piping systems. The greatest disadvantages are
high unrecoverable pressure loss, requirement for skill in installation and
making pressure connections, need for long runs of unobstructed piping or use
of straightening vanes upstream and downstream of the primary element to
achieve accuracy, and sensitivity of measurement reliability to orifice geom-
etry and surface conditions which can vary as a result of normal use or
handling [26].
Orifice plates can be specified in corrosion-resistant materials appropriate
for many operating conditions. For fluids above 600°F, plate materials should
be specified that have thermal expansion coefficients matched with those of
the mounting flanges, and effort should be made to moderate the rate of tem-
perature change on the complete primary assembly to avoid thermal stresses
[26].
The most common orifices have sharp, square, or rounded upstream edges. Cir-
cular concentric designs are particularly popular since accuracy is highly
predictable and extensive performance data are available for broad ranges of
flow rates, duct sizes, pressure differentials, and other application factors.
Eccentric and segmental orifice designs may be considered when the measured
fluid contains suspended materials since these may lead to accumulations
behind concentric plates and cause erratic or false readings [26].
5.6.3.2 Venturi Tubes— _
Venturi tube configurations can be standard, eccentric, or rectangular, in
standard designs, cylindrical barrel sections having inner diameters close to
those of the main pipes connect to the throat sections through cones of fixed
angular convergence; the throats terminate in diverging exit cones which again
match the inner pipe diameters. Eccentric venturi elements are available to
handle flows with mixed phases, and rectangular units can be specified for use
in noncircular ducts [26].
Venturis handle 25% to 50% more flow than orifices for comparable line size
and head loss. The flow range for satisfactory measurement is usually con-
sidered to extend upward from Reynolds numbers of about 200,000. Advantages,
in addition to capacity, include high pressure recovery, good accuracy with
beta ratios greater than 0.75, integral pressure connections, minimal require-
ments for straight runs of upstream piping, and suitability for dirty applica-
tions because the streamlined inner surfaces resist erosion and particle
accumulation. Purchase cost is high compared with most other primary elements
but the greater pressure recovery can result in significant energy savings in
large ducts. A more significant problem is that large sizes make the tubes
awkward to install [26].
5-79
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5.6.3.3 Pitot Tubes—
Pitot tubes are the simplest velocity head sensors. Models can be specified
for a variety of difficult fluid services, including high temperature, high
pressure, and corrosive, dirty gases. Moreover, the sensors are formed as
probes, which often are designed to be inserted in conduits without system
shutdown [26].
Numerous special as well as standard configurations are available; for in-
stance, models can be ordered to measure velocity direction as well as magni-
tude Limitations include tendency to plug when fluids contain suspended
solid particles unless provision is made for purging or flushing, narrow
velocity ranges with standard secondary elements, and sensitivity to local
distrubances in the flow pattern [26].
Another fundamental problem is that measurement indicates velocity at one
point in the stream, rather than providing integrated volumetric flows. The
probes must be traversed across the pipes or the velocity profiles known in
advance to calculate average flow. Moreover, to avoid uncertainty about local
perturbations, at least 8 diameters of straight smooth pipe are recommended
upstream of typical devices [26].
5.6.4 Solid Waste Retention Time and Mixing Characteristics Information
Retention time for nonvolatile or solid wastes in an incinerator is different
from that for volatiles. When solid wastes are being incinerated using incin-
erators which have mechanical means for agitating and moving solids through
the combustion zone such as is possible with rotary kilns and multiple hearth
incinerators, residence time of nonvolatiles will become a function of these
variables. Mixing will also become a variable when rabble arms or other
mechanical devices are used to tumble or otherwise break up chunks of solid
material. Residue analysis is typically performed to ascertain the condition
of the ash produced at these conditions. If analysis shows that insufficient
agitation or residence time is being achieved in exposing the solids to com-
bustion zone conditions, a change of those conditions is normally requested to
eliminate the problem.
5.7 AIR POLLUTION CONTROL DEVICE INSPECTION AND MONITORING
5.7.1 Wet Scrubbers
Five parameters are routinely checked on wet scrubbers to monitor their opera-
tional effectiveness. These are discussed below. Gas and liquid flow rates
are discussed together in Section 5.7.1.2
5.7.1.1 Temperature—
Deviations from the design temperature can have serious effects on the removal
efficiency of a wet scrubber, particularly when the scrubber is being used to
remove gaseous components. Since incineration inherently produces high tem-
perature gas to be scrubbed, pre-cooling of the gas stream is necessary.
Units used for this are commonly called quench towers, and they normally bring
the gas temperature down to around 150°F prior to entry into the scrubber.
This scrubber inlet temperature is continuously monitored to assure that
5-80
-------
proper scrubbing conditions are maintained in accordance with the design inlet
temperature value or range. Deviations can cause several effects, including
rapid loss of scrubbing liquid, compromise of absorption efficiency, undue
corrosion, and structural damage to the unit. One or more of these occur-
rences can increase emissions from the unit. Figure 5-34 shows the approxi-
mate position for temperature measurement. Emergency shut down features
regarding this temperature measurement are discussed in Chapter 4.
5.7.1.2 Liquid and Gas Flows—
A wet scrubber must provide good gas-liquid turbulence and optimum contacting
surfaces for proper absorption of contaminant gases or removal of particles
[27]. This provision is typically specified by the vendor and normally ex-
pressed as the liquid-to-gas ratio (e.g., 5 gpm/1,000 cfm [L/G]). A certain
L/G will be necessary to achieve design removal efficiency. The vendor also
supplies the sensitivity of the L/G ratio to removal efficiency because each
design has a somewhat different sensitivity to the L/G ratio. With this data
in hand, a range of acceptable L/G ratios can be established, consistent with
removal efficiency requirements. This range serves as the parametric limits
for acceptable L/G ratio operation. System gas flow will have been measured
as part of the incinerator operating requirement covered previously. There-
fore, scrubber liquid flow rate measurement will provide the remaining neces-
sary parameter measurement to define the L/G ratio. This parameter is moni-
tored often and remedial actions taken by the operator, should the ratio
exceed the parametric limits. Operator action will normally be a minor
adjustment of the scrubber liquid flow rate.
A measurement of the moisture content of the gas leaving the scrubber is made
in cases where some other device is in the system which can contribute addi-
tional moisture to the total gas flow such as a mist eliminator. This also
covers the situation where the gas flow measurement may be made upstream of
the quench zone in the hot gas area. In the case of the hot zone measurement,
the sum of hot zone gas flow plus moisture content corrected to scrubber
pressure and temperature conditions represent scrubber gas flow. Obviously, a
direct measurement of the gas flow exiting the scrubber may also be used, but
this will necessitate another measurement system set-up.
Measurement of the liquid flow rate is accomplished by using any of several
types of flowmeters, including venturi, orifice, flow tube, pitot tube, mag-
netic, or acoustic varieties. Device acceptability considerations are sum-
marized in Table 5-7. Figure 5-34 shows the appropriate measurement location.
5.7.1.3 pjj--
Another important parameter in wet scrubber operation is pH. Materials of
construction are selected in part based upon the degree of acidity or alka-
linity provided by the scrubbing liquid during operation. Deviation from the
design pH condition or range may result in deterioration of the scrubber
structure in contact with the liquid. Furthermore, maintenance of the pH
design condition is important to scrubber liquid absorption efficiency when
removing gaseous contaminants.
The liquid composition and its attendant pH will be determined during the
design phase. Absorption efficiency can change drastically -as a function of
5-81
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TABLE 5-7. DEVICES FOR LIQUID FLOW MEASUREMENT
Flow
measurement
device
Venturi meter
Advantaaes
Low permanent
pressure drop.
Disadvantages
Flow disrupted and
plumbing modifica-
Flow range, gpm
(applicable
pipe
diameter)
0-750
(1-18 in.)
Applicable to
streams with ap-
preciable solids
content. Accurate.
Orifice meter Inexpensive.
Flow tube
Pitot tube
Magnetic meter
Applicable to
streams with
appreciable solids
content.
Low permanent pres-
sure drop. Inex-
pensive method for
pipes of large
diameter.
Minimum permanent
pressure drop.
Applicable to
streams with ap-
preciable solids
content. Accurate.
Acoustic meter
tions required for
installation.
Expensive.
Installation without
flow disruption.
Relatively accu-
rate. No head
loss or pressure
drop. Applicable
to streams with
appreciable solids
content. Portable.
Flow disrupted and
plumbing modifica-
tions required for
installation. Large
permanent pressure
drop. Solids may
deposit behind device.
Moderately accurate.
Flow disrupted and
plumbing modifica-
tions required for
installation. Inter-
mediate permanent
pressure drop. Mod-
erately expensive.
Moderately accurate.
Flow disrupted and
plumbing modifica-
tions required for
installation. Solids
may cause plugging.
High flow velocities
may cause instability.
Moderately accurate.
Flow disrupted and
plumbing modifica-
tions required for
installation. Expen-
sive. Electrodes may
be fouled by waste-
waters containing oil
and grease. Suscep-
tible to electromag-
netic interference from
nearby equipment.
Expensive. Moderately
accurate.
0-750
(0.5-30 in.)
0-750
(1-18 in.)
250-50,000
250-20.000
(0.1-100
in.)
250-20.000
(pipes of all
diameters)
5-82
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pH, thereby altering the scrubber removal efficiency, so an acceptable pH
variation range is designed for the equipment. The pH is monitored continu-
ously and either manual (operator) or automatic adjustment made to keep the pH
within proper operating specifications. A number of commercially available pH
monitoring systems can adequately serve this purpose. These systems normally
include a direct readout device which can be conveniently located on a control
panel for continuous monitoring accessibility. Figure 5-39. Section 5.8,
shows the measurement location and arrangement for scrubber liquid pH.
5.7.1.4 Pressure Drop--
Pressure drop is an important indicator parameter in monitoring the opera-
tional condition of a wet scrubber. It is sensitive to changes in the gas
flow rate, liquid flow rate, and clogging phenomena in the system. During the
design phase, a proper pressure drop value or range to maintain design removal
efficiency is specified. Monitoring this parameter provides a continuous,
additional check on the normal operation of the scrubber. A change in the
pressure drop is an indication that other measured parameters in the system
need to be observed immediately to find the cause of the disturbance and
corrective action should be taken. It is also an indicator which covers the
time span between other routine parameter checks. If, after checking the pH,
temperature, and gas and liquid flow rates, all appears in order, then the
pressure drop measuring system is checked for correct operation and a visual
inspection of the scrubber conducted to identify possible clogging problems.
A check of the control efficiency is also routinely made to see if removal
efficiency is being maintained.
Many kinds of pressure measurement devices are commercially available to meas-
ure pressure drop across a device; however, a differential pressure gage cali-
brated in inches of water is usually recommended for this purpose. The read-
out device is located in a convenient place for the operator to observe at any
time. Figure 5-34 shows the location of the pressure taps relative to the
device.
In selecting a pressure measuring device, the following items are considered:
Pressure range
• Temperature sensitivity
• Corrosivity of the fluid
• Durability
Frequency response
A guide to pressure sensing device selection is summarized in Table 5-8.
5.7.1.5 Residue Generation--
Generation of residue from wet scrubbers results from operational requirements
of the scrubber liquid in the specific system used. Vaporization losses in
the contacting area create the need for make-up liquid to be provided, and
changes in liquid pH create the need for adjustment. Collected material (such
as solid particles) also creates abrasion, contamination, and corrosion prob-
lems in the scrubbing liquid and/or transport system. In addition, when
hazardous materials are collected, a need for further treatment may be created
prior to disposal. Sometimes a designer will choose to accommodate these
5-83
-------
in
0)
TABLE 5-8. A GUIDE TO PRESSURE SENSING ELEMENT SELECTION (28]
Selection
criteria
Pressure range
Temperature range
Bourdon
12 psi to 100 K psi
-40°F to +375°F
Common sensors
Diaphragm
5 psi to 15 psi
-40°F to -t375°F
Transducers,
strain gauges
Bellows
0.5 to 30 psi
-40°F to +375°F
Unbonded
0.5 psi through
10 K psi
-320°F to 600°F
(O.OOSVF)"
Bonded foil
5 psi through 10 K
psi
-65°F to +250°F
(0.01%/°F)a
Advantages
Low cost; field re- Variety of materials Compact, accurate,
placeable; variety for media and field replaceable.
range; field re-
placeable ; large
force.
of materials for
media and range.
Disadvantages
Slow response; large
sensor volume sen-
sitive to shock
and vibration.
Limited capacity;
position sensitive
in low ranges.
Limited material;
may be position
sensitive.
Accepts unidirec-
tional and
bi-directional
pressure measure-
ments; ac or dc
excitation.
Low signal level
(4 mV/V).
Temperature effects
small and linear;
ac or dc excita-
tion; rugged con-
struction.
Low signal level-
(3 mV/V) limited
temperature range.
(continued)
Percent/°F over limited compensated range
-------
TABLE 5-8 (continued)
Selection
criteria
Pressure range
Temperature range
Thin film
15 psi through
5 K psi
-320°F to +525°F
(0.005%/°F)a
Diffused
semiconductor
1 psi through
10 K psi
-65°F to +30.000°F
(0.005%/°F)a
Transducers
Bonded in
semiconductor
5 psi through 10 K
psi
-65°F to +30.000°F
(0.01V°F)8
Reluctive
0.4 psi through
10 K psi
-320°F to +600°F
(0.02%/°F)a
Capacitive
0.01 through 200 psi
0°F to 165°F
Requires tempera-
Advantages
ui
CO
ui
Disadvantages
Excellent thermal
zero and sensi-
tivity shift; ac
or dc excitation.
Low natural fre-
quency; low signal
level. 3 mV/V.
Small size, high
natural frequency;
steady and dynamic
reliability.
repeatability.
Susceptible to han-
dling problems;
more temperature
sensitive than
most transducers;
electrical output
only.
Small size, high
natural frequency;
steady and dynamic;
excellent repeat-
ability.
Susceptible to han-
dling problems;
more temperature
sensitive than
most transducers.
High output (40 nV/V
excitation); rugged
construction; over
pressure capability.
Sensor requires ac
excitation; sus-
ceptible to stray
magnetic fields;
ac carrier systems
require balanced
line for data
transmission.
ture control.
Excellent for low
pressure, excel-
lent frequency
response; output
countable without
A/D converter.
Requires short leads
from sensor; high
impedance output;
temperature sen-
sitive; needs
extra electronics
to produce useable
output.
(continued)
Percent/0? over limited compensated range.
-------
TABLE 5-8 (continued)
Transducers
Selection
criteria
Potentiometer
Linear variable
displacement transformer
Force balance
Piezoelectric
01
I
CO
Pressure range
Temperature range
Advantages
Disadvantages
5 psi through 10 K psi
-65°F to +300°F
nonlinear 0.01%/°F
Low cost; small size;
high output without
amplification.
Tendency to short life
due to mechanical wear;
noise increases with
wear.
30 to 10 K psi
0°F to 165°F
Available in rotary
form; not affected by
mechanical overload.
1 psi through SO K psi
40°F to 165°F 0.01%/°F
High accuracy; high
output; stable; wide
ranges.
Some problem maintaining
linear movement of
core proportional to
pressure change; will
develop mechanical wear.
Large size; shock and
vibration sensitivie;
low frequency response.
0.1 psi throuh 10 K psi
-450°F to 400°F 0.01%/°F
High frequency response;
self-generating
signal; small size;
rugged construction.
Temperature sensitive;
requires amplifier and
special cabling
between device and
amplifier; slow re-
covery to shock and
overpressure.
-------
problems in an integrated system design approach. Monitoring requirements
relative to generation of residue from a wet scrubber are those required for
observation of waste stream treatment systems and are covered in Section 5.8.
Control of pH is also discussed.
5.7.2 Fabric Filters
Fabric filters basically consist of a porous layer of flexible, textile mater-
ial through which a contaminated gas is passed to separate entrained material
from the gas stream [29]. As collected material accumulates, resistance to
the gas flow increases. The collected material is removed periodically by
vigorously cleaning the filter to maintain proper pressure drop across the
system.
Certain fabric filter parameters are monitored on a regular basis to evaluate
operational effectiveness. These are detailed below.
5.7.2.1 Temperature—
A limiting factor in filtering hot gases with a fabric filter is the temper-
ature resistance of the fibrous materials from which the filter cloth is made.
Therefore, the manufacturers temperature specifications regarding appropriate
filter material are important for efficient operation. Continuous recording
of the temperature of the gas coming into contact with the filter media is
made to assure that extended excursions above the recommended value are not
occurring. Appropriate corrections are then made immediately, either automa-
tically or by the operator, to maintain inlet temperature within design cri-
teria. This helps minimize the occurrence of extraordinary material breakdown
with resultant increased emissions. It also aids in keeping maintenance of
the filter in good order and extending the life of the filter material.
Measurement technique is similar to that depicted in Section 5.7.1. Figure
5-35 shows the appropriate measurement location.
5.7.2.2 Gas Flow and Pressure Drop--
Fabric filter collectors are commercially available to handle total gas flows
from 100 cfm to greater than a million cfm. The quantity of gas processed and
the contaminant concentration in conjunction with specific flow resistance
properties of the particulate deposit on the fabric determine the amount of
filtration area required for a selected value of operating pressure drop. A
design pressure drop is generally chosen around 3 or 4 inches of water for
economic reasons, but some units are designed to operate higher than 10 inches
of water pressure drop. Variation in the pressure drop over a specified range
is normal in fabric filter operation. The operational cycle consists of a
gradual buildup of material on the surface of the filter which is periodically
cleaned off. The development of this deposition increases the pressure drop
with time. This cycle usually remains within specified limits. Continuous
recording of the operating pressure drop is maintained by the operator. The
pressure drop is maintained within the manufacturer's specified range so that
undue disturbance of the design filtration efficiency does not occur. Chapter
4 provides further information regarding fabric filters. The pressure drop
measurement device is essentially the same as described in Section 5.7.1.4.
Measurement location is shown in Figure 5-35.
5-87
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LIQUID
INCINERATOR
QUENCH ZONE
INLET GAS
TEMPERATURE
(MEASUREMENT
DIFFERENTIAL PRESSURE
GAUGE FOR PRESSURE
DROP MEASUREMENT
TO ATMOSPHERE
KILN
UPSTREAM PRESSURE
TAP LOCATION
ROTARY AIR
LOCK VALVES
DOWNSTREAM
PRESSURE TAP
LOCATION
YYT
^ 9 9.
CONVEYOR
SIGHT PORT
PARTI CULATE TO
TREATMENT
AND DISPOSAL
Figure 5-35. Recommended measurement and inspection locations.
5.7.2.3 Residue Generation—
Accumulated particulate matter is removed and transported to a central point
for reprocessing or disposal depending on the hazardous nature of the collec-
ted material. Means of preventing gas leakage at the hopper discharge is an
important design factor. This is normally accomplished through the use of
double flap valves or rotary air-lock valves, although the rotary air lock
valve will give the most positive seal.
A means of preventing bridging in the hoppers is also important. Common types
are mechanical, spring loaded rappers, electric vibrators, and compressed air
vibrators. Helicoid screw conveyors are commonly employed for horizontal
transport of the collected material to a central point.
Residue analysis is needed to ascertain the hazardous nature of the collected
material and to select appropriate disposal options. The type of such
analyses is covered in Chapter 3.
5.7.3 Electrostatic Precipitators
Precipitators are theoretically complex control devices which are almost
always specifically designed for a given application. Many technical consid-
erations are evaluated initially to aid the applicability determination [30].
In each case, however, a set of operating conditions and checkpoints are
defined by the vendor as proper and necessary to maintain the design removal
efficiency. Compliance with these and other conditions pertinent to
5-88
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maintaining the quality of the environment are evaluated; the following
information serves as a checklist for such items.
5.7.3.1 Rapping Cycle Practice—
Precipitators use a "rapping" or force impact sequence to remove buildup of
collected material on the internal surfaces of the equipment. This causes
re-entrainment of collected material in the exhaust gas stream which affects
precipitator removal efficiency. Three variables are involved; the rapping
interval, the rapping intensity, and the duration of the rapping cycle.
(1) Rapping interval - It is desirable to know the time interval of rapping
for each electrode in the precipitator field, because the upstream fields
are normally rapped more frequently than the downstream fields as a
result of the relatively high material buildup in the initial stages.
(2) Rapping intensity - How hard an electrode is rapped will affect the
amount of material removed each rap.
(3) Cycle duration - How long a time the rap covers affects the degree of
"cleanliness" achieved.
The intervals for these three variables are designed to be appropriate for the
application. This choice is normally based on the experience of the company
with their product. Common practice ranges from very frequent rapping (every
few minutes) to intervals as long as an hour. The intensity may range from
low to high with frequent intervals, but is normally high at longer intervals.
The ability to change the values is normally a part of the precipitator con-
trols. A check of the proper settings is made at least once a day by the
operator and records kept for examination by the EPA upon request. A typical
rapping mechanism is shown in Figure 5-36.
5.7.3.2 Temperature. Resistivity, and Gas Moisture Effects—
The resistivity of the material collected can have an influence on the collec-
tion efficiency. If the resistivity is greater than about 5 x 101 ohm-cm,
the electrical field developed in the collected particle layer can exceed the
breakdown field strength. Excessive spark rates and back corona can occur
which will cause operation at lower than normal current densities with result-
ing degraded performance. If the particle resistivity is less than about 10
ohm-cm, the electrical forces holding the material to the collection plates
may be low. Excessive re-entrainment can occur yielding lower performance.
A resistivity range showing the allowable span for maintenance of removal
efficiency is normally supplied with an ESP along with a measurement of the
resistivity of the material collected. As long as the feed material does not
change, no further check on the resistivity is usually necessary, unless
removal efficiency changes for no apparent cause.
Increasing moisture content will also lower the resistivity. A change in
moisture content will normally only occur with a change in the feed material
moisture or a change in steam injection conditions if such a technique is used
to increase hydrogen ion availability in the combustion zone.
5-89
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•ENCLOSURE
ENCLOSURE
VIBRATOS
MOUNTING rum
STUFFING BOX AND GUIDE
FUXIBU CONDUIT
CONDUIT FITTING
HOUSING
CERAMIC INSULATING SHAFT
cumn
[RAPPER RODS
CERAMIC SHAFT)
CLOSURE PLATE
— HIGH VOLTAGE BUSHING
RAPPER ROD ASSEMBLY.
MUST BE PLUMB
HIGH TENSION FRAME
DISCHARGE WIRES
Figure 5-36. Typical vibratory rapper.
LIQUID
INCINERATOR
TO
ATMOSPHERE
ELECTROSTATIC
PRECIPITATOR
INLET GAS
TEMPERATURE
Figure 5-37. Recommended measurement location.
TO
DISPOSAL
Temperature affects precipitator removal efficiency although not as much as it
affects baghouses and wet scrubbers. Temperature considerations are normally
evaluated during the design phase of the precipitator by the vendor.
5-90
-------
Specifications are provided by the owner/operator showing the allowable temper-
ature range for design removal efficiency. Continuous recording of the in-
coming gas temperature is made by the owner/operator to assure that extended
excursions above or below the recommended range are not occurring. Appropri-
ate corrections are then made to maintain inlet temperature within design
criteria. The measurement technique must be similar to that discussed in
Section 5.7.1. Figure 5-37 shows the appropriate measurement location.
AC VOLTAGE
INPUT
CONTROL
ELEMENT
STEP-UP
TRANSFORMER
HIGH VOLTAGE
RECTIFIER
MANUAL
AUTOMATIC
CONTROL
FEEDBACK
ELECTROSTATIC
PRECIPITATOR
H
Figure 5-38. Power supply system for modern precipitators.
5.7.3.3 Applied Voltage (Power Supply Control)—
The overall objective of precipitator design is to combine the component parts
into an effective arrangement that results in optimum collection efficiency.
A very important aspect toward this objective is the design of the
precipitator power supply.
The power supply normally consists of four components as shown in Figure 5-38;
a step-up transformer, a high voltage rectifier, a control element, and a
sensor for the control system. A step-up transformer is required because the
operating voltages (applied voltage) range from about 20 to 100 KV. This
system is used to maintain the applied voltage at an optimum value even when
the material characteristics and concentration exhibit temporal fluctuations.
Once normal operating conditions have been established, continuous monitoring
of the power supply system is typically maintained. The necessary indicators
(meters) for this are normally provided as part of the precipitator control
panel. Deviations will likely be caused by excessive buildup of collected
material in the precipitator or breakdown of the electrical supply circuitry.
Investigation should begin immediately to locate the cause, and correction
made, including shut off of feed material and/or shut down for repair if
removal efficiency drops below specifications.
5-91
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5.7.3.4 Gas Flow—
Changes in the gas flow rate can affect removal efficiency. This becomes more
critical as the particles get smaller. The precipitator is designed so that
the combination of the forces applied on the particles and the time that the
forces remain on the particle (dwell time) result in the movement of the
particles to a collection surface. The smaller the particle, the longer it
takes under fixed conditions to do this.
If the gas flow rate increases beyond design capacity, this combination
becomes compromised and a degradation of removal efficiency will occur.
The gas flow measurement requirement discussed in Section 5.7.3 is appropriate
for checking the precipitator flow parameter also. Sustained increase in the
gas flow is usually checked immediately for effect on the design removal
efficiency, and correction made to remain within design conditions. This may
require reduction in input feed material flow or some other modification(s).
5.7.3.5 Residue Generation Rate and Dust Removal Capacity—
It is important to determine that the dust removal system remains working
properly according to specifications. Hoppers are used to collect material
removed from the collecting surfaces by the rapping sequence. If the residue
generation rate exceeds the material removal capacity, re-entrainment of
collected material will occur, greatly reducing precipitator efficiency.
Historically, automatic removal of collected material is one of the major
causes of precipitator failure, and daily inspection for proper operation is
typically required.
5.7.3.6 Internal System Pressure—
If the precipitator system is operated with internal pressures less than
ambi-ent, leakage of air through the hopper can also cause a re-entrainment of
mate-rial from the hoppers. A design check to make sure the hopper area is
properly sealed is made to prevent such occurrence. Section 5.7.2.3 discusses
appropriate seal techniques. Further details regarding electrostatic
precipitators is found in Chapter 4.
5.7.4 Mist Eliminators
Mist eliminators are extensively employed to reduce emissions of entrained
liquid droplets from wet scrubbers. The most commonly used types include
cyclone collectors, simple inertial separators such as baffles, wire mesh mist
eliminators, and fiber bed elminators. In use, the latter three devices work
by the same principle. Rising mist droplets strike the mist eliminator,
coalesce due to inertial impaction and direct interception, and form larger
droplets which fall back into the scrubber.
Cyclones differ from the other types of mist eliminators because centrifugal
force is used to remove the droplets. The particulates, because of their
inertia, tend to move toward the outside wall from which they are led to a
receiver [20].
The choice of mist eliminator equipment is dependent on droplet size, gas flow
pressure drop, and cost considerations. Cyclone collectors are used to remove
5-92
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larger droplets (10 to 100 urn range), and are used commonly in conjunction
with venturi scrubbers. Simple inertial mist eliminators (baffle, louvre, and
vane-type among others) are effective with droplets about 10 urn in size.
Fiber bed mist eliminators have the highest efficiency of any of the types of
eliminators for trapping very fine droplets (as small as 0.5 urn).
Although the different types of mist eliminators vary in design, they have
common parameters which must be monitored to evaluate operational effective-
ness. These are detailed below.
5.7.4.1 Temperature— . .
Excessive temperatures can adversely effect the performance of a mist elimi-
nator. Higher temperatures could result in a heavier loading and increased
corrosion. Since the mist eliminator is located downstream from the wet
scrubber, monitoring the temperature of the scrubber is sufficient to ensure
the mist eliminator is operating at a suitable temperature.
5.7.4.2 Gas Flow and Pressure Drop—
For maximum efficiency, flow of gases through the mist eliminator should be
high enough to be practical while allowing a reasonable retention time.
Re-entrainment of the liquid droplets can result if the gas flow is too high.
The optimum gas flow varies according to the particulate mist eliminator used,
and is normally supplied by the manufacturer. Pressure drop may vary from 2
to 12 in. of water gage, in accordance with manufacturers' specifications.
Continuous recording of the operating pressure drop is typically maintained by
the owner/operator and such records made available for inspection. A change
in the pressure drop would indicate a change in the gas flow rate or, more
importantly, the accumulation of solids in the equipment, decreasing its
efficiency.
5.7.4.3 pH Level—
To prevent excessive corrosion, the mist eliminator is normally constructed of
material that is resistant to the pH level of the mist. pH is monitored in
the wet scrubber to ensure the mist eliminator is operating within the manu-
facturer's recommended pH range.
5.7.4.4 Maintenance—
Proper maintenance of mist elimination equipment is essential in order to
maintain optimal efficiency, for collection of solid material in the equipment
can decrease efficiency. The equipment can be cleaned by backwashing or by
automatic spray devices. Often, daily inspection is required to assure that
the backwash system is operating properly.
5.8 SCRUBBER WASTE STREAM TREATMENT INSPECTION AND MONITORING
5.8.1 Flow Measurement and Monitoring
In any treatment system unit operation, the measurement and/or control of flow
is a critical parameter. In this case, flow is a factor in determining the
rate of caustic solution addition in the neutralization system. Flow measur-
ing and recording devices are described in detail in Section 5.7.1.2.
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5.8.2 Flow Control
Automatic monitoring systems are employed to provide advanced warning when the
water level in the neutralization system has increased above a set operating
limit. This enables operators to institute immediate process alterations to
allow the neutralization system to equilibrate back to normal operations.
5.8.3 pH Monitoring
Sensors for automatic monitoring, recording, and control of pH are especially
sensitive to process interferences. It is necessary, therefore, that care is
taken in the selection of automatic equipment in order to ensure that it will
function satisfactorily in the treatment scheme.
Automatic monitoring of pH has the following advantages:
(1) pH is recorded on a continuous basis, producing a clear picture of
variation with time.
(2) Time lag between sampling and analysis is much shorter than in manual
sampling. Problems resulting from the storage of sampling equipment are
also eliminated.
(3) The rate of neutralizing chemical addition can be continuously
controlled.
(4) Automatic monitoring can be combined with an alarm system to provide
warning if the neutralized effluent is of insufficient quality. When
this occurs, a by-pass valve could be opened to direct the effluent to a
storage basin for gradual addition to the treatment system once normal
operations have been resumed.
Automatic monitoring is not without disadvantages, however. Among them are:
(1) The sensor may not be capable of registering unusual circumstances due to
probe location.
(2) The wastewater characteristics, at least in general, must be known in
advance of monitoring equipment selection.
(3) The initial cost of automatic equipment is relatively high.
Problems which can be anticipated and need to be addressed in system design
and operation are:
(1) Loss of calibration. Regular maintenance is necessary to prevent errors.
(2) Bacterial growth may inhibit sensor operation. Regular cleaning is
necessary unless self-cleaning sensors are used.
(3) Mechanical damage may occur if the probe is unprotected by a screen,
similar device, or design.
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(4) Miscellaneous problems resulting from power failures, mishandling of
equipment, pump difficulties, etc.
(5) Interferences should be analyzed and addressed before equipment selection
and installation.
5.8.4 pH Control Systems
A pH control system consists of a pH electrode probe, located in the flow
scheme, connected to a controller which reports to a recorder. The controller
regulates the rate of neutralization chemical addition.
In the monitoring/control system, several types of valves may be used, depend-
ing on the consistency of the influent quality and the treatment chemicals
used. The types of controllers likely to be employed are on-off, proportional,
resetting derivative, and flow-proportional.
5.8.4.1 On-Off Controller—
The on-off controller is the least expensive of the above devices. If the pH
exceeds, in either direction, a certain limiting value, the valve opens and
neutralizing agent is added until an established corrected value is achieved.
This system has limited application here due to the potential for large
chemical overdose.
5.8.4.2 Proportional Controller—
Proportional controllers are more advanced than on-off controllers and are
used where a more constant effluent quality is desired. In its simplest
application, the proportional controller regulates the amount of neutralizing
solution in proportion to a deviation from a set point as a means of control-
ling pH within an acceptable range.
5.8.4.3 Resetting Derivative Controller—
A resetting derivative controller regulates the speed with which the valve
opens to add neutralizing agent. The valve speed is based on the rate of
derivation from a set point. This system does not typically operate well with
high suspended solids effluent, however.
5.8.4.4 Flow Proportional Controller—
If the influent water quality is constant, but flow varies, the neutralization
control valve may be connected to a flow meter rather than the pH probe.
Neutralizing agent will be added proportional to the flow.
A schematic of the general elements in a pH control system using lime is given
in Figure 5-39.
5.8.5 Scrubber Solution pH Control
The particulate removal efficiency of a venturi scrubber and the acid gas
scrubbing efficiency of a packed tower is affected by maintenance of the pH of
the incoming scrubbing solution.
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RECORDER
LIME
FINAL „
CONTROL ¥-0-
ELEMENT *•*
CONTROLLER
INFLUENT
pH ANALYZER
MIX TANK
SENSING
ELECTRODES
NOTES:
FINAL CONTROL ELEMENT MAY
BE CONTROL VALVE PUMP OR
DRY FEEDER.
pH CONTROLLER MAY BE CASCADED
WITH INFLUENT FLOW.
Figure 5-39. Elements of a typical pH control system.
If a recirculating mode is utilized, the incoming stream must be neutralized
after contact with the gas. Neutralization is necessary to prevent corrosion
of metal surfaces, construction materials, and tower packing.
The process of neutralization is the interaction of an acid with a base. The
typical properties exhibited^by an acid in solution are due to the concentra-
tion of the hydrogen ion, (H ). Alkaline (basic) properties are the result of
the concentration of hydroxyl ion (OH~). In an aqueous solution, acidity and
alkalinity are defined with respect to pH, where pH = -log [H ], or as
pH = 14+ log [OH*]. Neutralization is typically the adjustment of pH from one
extreme to a range of pH 6.0 to 8.5.
The scrubber and absorber solutions will, after contact with acid gases, be
acidic in nature, (pH <7). Neutralization is accomplished by the addition of
an alkaline material, such as caustic soda (NaOH). An example of the
neutralization process is the reaction between hydrochloric acid and sodium
hydroxide:
HC1 + NaOH -> H20 + NaCl
The product, sodium chloride in aqueous solution, is neutral with pH = 7.0.
Neutralization is usually accomplished by contacting the incoming feed with
concentrated caustic or acid solution in a well mixed chamber.
Lagoons, concrete basins, chemically resistant tanks, and in-line static
mixers are all used for this purpose.
Neutralized water can be piped to storage ponds for subsequent process reuse,
solar evaporation, or further treatment, if necessary for NPDES discharge.
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A simple schematic of a two-step neutralization system is given in Figure
5-40.
WJTIAII21NC CHOUCAl
RI0SYSTIM
MUIIALIZING OCMICAL
mo SYS TIM
INCOMING WATO
Figure 5-40. Two-step neutralization flow schematic.
5.9 CONTINUOUS MONITORING INSTRUMENTATION FOR GASEOUS COMPONENTS
Continuous monitoring of at least 02, CO, and C02 gases in the exhaust stream
of hazardous waste incineration are proposed. A number of continuous monitor-
ing systems are available for this general purpose. These monitors are automa-
ted, and are capable of unattended operation for days or weeks. While such
instruments have been successfully applied to measuring CO, C02, and 02 in
combustion gases, their accuracy remains somewhat controversial within both
the technical community and users.
The following text provides a summary of aspects pertinent to the evaluation.
Should greater detail be desired, the permit writer is encouraged to consult
the EPA Handbook of Continuous Air Pollution Source Monitoring Systems,
EPA-625/6-79-005, from which most of the following information is derived
[31].
The basic elements of a pollutant monitoring system are shown in Figure 5-41.
5.9.1 Available Systems
Proposed continuous monitoring systems will likely fall into one or more of
the following types:
• Nondispersive infrared analyzers (NDIR)
• Polarographic analyzers
• Paramagnetic analyzers
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SAMPLE
MANIFOLD
CALIBRATION
UNIT
EXHAUST
Figure 5-41. Elements of pollutant monitoring system.
• Nondispersive ultraviolet analyzers (NDUV)
• Electrocatalytic analyzers
Table 5-9 summarizes what component each type of analyzer is capable of
measuring.
In addition to being categorized according to detection type, a broader classi-
fication of monitoring systems exists which distinguishes between extraction
and in-stack or in-situ type systems. All five of these instruments with the
exception of the polarographic monitor, are available in both extractive and
in situ types.
Discussions of the components, advantages and disadvantages, and limitations
of both extractive and in-situ versions follow. The general principles of
operation discussed for the analyzers themselves may be applied to either
version, as the differences in the detector mechanics are subtle.
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TABLE 5-9. ANALYZERS CAPABLE OF MEASURING
GASEOUS COMPONENTS
Component
Detection device
NDIR
NDUV
Paramagnetic
Polarographic
Electrocatalytic
02
X
X
X
CO,
X
X
X
CO
xa
X
X
aGFC method used for CO detection
(covered in text).
5.9.1.1 Extractive Systerns--
The ability of an extractive, or remote monitoring system, to provide reliable
data depends upon a properly designed sampling interface. The total
extractive system must perform several functions:
• Remove a representative gas sample from the source on a continuous basis.
• Maintain the integrity of the sample during transport to the analyzer
(within specified limits).
• Condition the sample to make it compatible with the monitor analytical
method.
• Allow a means for a reliable calibration of the system at the sampling
interface.
The design of the sampling interface, including the components used in its
construction, will depend on the characteristics of both the source gas stream
and the monitoring instrument.
The design of a sampling interface requires that the system deliver a condi-
tioned, continuous gas sample to the gas analyzer. A number of different
interface designs may be able to perform this task at a given source. The
actual system designed for a specific source generally incorporates a variety
of trade-offs based on source/analyzer requirements and financial restraints.
A system typically will include the following components:
• In-stack sampling probe
• Coarse in-stack filter
• Gas transport tubing
Sampling pump
• Moisture removal system
• Fine filter
• Analyzer
• Calibration system
Data recorder
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Sampling Probe—Representative gas sampling requires samples that will demon-
strate the total pollutant gas emissions from a source. The temperature and
velocity traverse across the duct may indicate a necessity for a multipoint
probe to extract samples from numerous points across the entire duct. Several
research studies have shown that, although gas concentration cannot be assumed
to correspond directly to temperature and velocity gradients in a duct, these
measurements are excellent indications for positioning gas sampling probes.
This research has shown that a representative gas sample may be extracted from
a grid of equal areas laid out in the duct. A temperature and velocity trav-
erse is then performed in each row of the grid. The multipoint gas sampling
probe is then positioned across the row that indicated temperature and
velocity readings closest to the average reading in the duct.
Gas sampling requires that particulate matter, which can harm the analyzer and
shorten the operating life of the sample pump, be removed from the gas stream.
Directing the probe inlet countercurrent to the gas flow helps prevent many
large particulates from entering the system. Particulates that enter the
probe can be removed by coarse and fine filters.
Coarse Filters—The coarse filter is usually located at the probe tip in the
stack, where it then can prevent particulate matter from plugging the sampling
probe and will not require heat tracing to prevent moisture condensation.
There are two general types of coarse in-stack filters: external or internal.
The external coarse filter is a porous cylinder, typically constructed of
sintered 316 stainless steel, though it may also be glass, ceramic, or quartz.
It is essential that the porous cylinder be protected by a baffle to prevent
excessive particulate buildup on the leading edges. These porous cylinders
have an expected utility of approximately 2 to 3 months before they become
clogged with particulate, depending on the sampling rate. Although they can
be regenerated by back flushing, they eventually need replacing. The nominal
cost (~$25) suggests that it may be easier to replace the filter on a routine
basis than to install costly automatic backflushing equipment.
Filter material is available from a number of manufacturers. Glass wool
filters have been used in some experiments; however, they have a higher
pressure drop than the Alundum thimble.
Fine Filters—The majority of extractive stack gas analyzers require almost
complete removal of all particles larger than 1 micron from the gas stream.
This is best accomplished by including a fine filter near the analyzer inlet.
Fine filters are divided into two broad categories: surface filters and depth
filters.
Surface filters remove particulates from the gas stream using a porous matrix.
The pores prevent penetration of particulates through the filter, collecting
them on the surface of the filter element. Surface filters can remove particu-
lates smaller than the actual filter pore size with particulate cake buildup
and electrostatic forces acting to trap smaller particles. These filters
perform well on dry, solid particulates without excessive pressure drop. A
surface filter will foul quickly if it becomes wet or if the particulate is
gummy.
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Depth filters collect particulates within the bulk of the filter material. A
depth filter may consist of loosely packed fibers or relatively large diameter
granules These filters perform well for gummy solids or moist gas streams
and dry solids. In the case of malfunction, their flexibility can protect the
analyzer from damage. Glass wool packed to a density of 0.1 gm/cm3 and a bed
depth of at least 2 inches can act as an inexpensive depth filter for normal
gas flowrates. These filters must be carefully packed to avoid channeling.
Gas Transport Tubing—The gas tubing or sample lines transport the extracted
gas sample from the stack through the interface system and into the analyzer.
When evaluating sampling lines, it is important to consider:
• Tube interior-exterior diameter
• Corrosion resistance
• Heat resistance (for lines near high temperature areas or heat tracing)
• Chemical resistance to gases being sampled
• Cost
The gas tubing is sized to ensure an adequate gas flowrate with a reasonable
pressure drop and good system response time. A flowrate of 2 standard liters
per minute (enough to supply two gas analyzers) through a 6.35-mm OD (1/4 in.)
tubing exhibits a pressure drop between 1 and 3 mm Hg per 30.48-m length.
This pressure drop is quite acceptable for most sampling pumps. The response
time (t) for a sampling line volume (V) can be calculated at a flowrate (F) in
the equation:
t = - (assuming no axial dispersion or wall effects)
At a flowrate of 1 standard liter minute, the response time for a 30.48-m tube
section at 25°C and pressure drop of 152 mm Hg is only 30 seconds. These data
indicate that 6.35-mm OD tubing is acceptable for sampling lines [31].
Teflon® and stainless steel exhibit excellent corrosion and heat resistance in
addition to being chemically inert to stack gases and acid mist. The corro-
sion resistance of stainless steel is enhanced by keeping gases above the dew
point. These materials are commercially available in heat traced form.
Teflon® is normally recommended for out-of-stack heat traced lines; stainless
steel is a good material for in-stack lines. Polypropylene and polyethylene
lines exhibit good chemical resistance (except to nitric acid). Plastic lines
are a good, economical choice for sampling lines that carry dry gas and are
maintained above the freezing point without heat tracing. A reliable,
effective, and economical sampling line system probably would incorporate
stainless steel, Teflon®, and plastic.
Sampling Pump—A diaphragm or bellows pump upstream of the analyzer is
superior to other pump types for gas handling. The primary advantages offered
are:
are:
No shaft seal required.
No internal lubrication required.
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• Pumps are relatively inexpensive.
• Adequate suction and discharge pressures are developed at flowrates well
above those needed for gas sampling systems.
Some sampling interface systems may place the pump downstream of the analyzer,
pulling the sample through the system. This could allow the use of an aspira-
tor pump without moving parts. Pressure drop at the analyzer would be higher,
but for some analyzers with built-in pressure regulators, this may be prefer-
able arrangement. Downstream pumps increase the potential for air leaking in
and, in the case of aspirator pumps, require a source of large quantities of
compressed air, steam, or water.
Moisture Removal—Stack gases may contain significant quantities of water
vapor. A limited number of analyzers are not affected by the presence of
water vapor in the sample (e.g., a differential absorption ultraviolet instru-
ment). These analyzers do, however, require that gases be kept above the dew
point to protect against condensation and corrosion within the analyzer.
Other analytical methods that are affected by water vapor require moisture
removal. Generally, the gas is dried to a low constant level of moisture
content for both stack gases and calibration gases. Refrigerated condenser
traps or permeation dryers are commonly used for moisture removal.
Sampling Interface Monitor Calibration—The entire sampling interface and
monitor must be calibrated as a unit. The calibration gases enter the continu-
ous gas monitoring system as near as possible to the same entrance point for
the stack gas. This is essential to check the entire system. The analyzer is
then calibrated at the same gas flowrate, pressure, temperature, and operating
procedure used in monitoring the stack gas. Flooding the coarse filter with
calibration gas at the probe inlet or using a check valve that allows calibra-
tion gas injection directly behind the coarse filter are the best methods for
accomplishing this calibration. Calibration in this manner assures that any
leaks, blockage, or sorption of gases taking place in the system will be
discovered. The importance of this method cannot be overemphasized.
Automatic gas injection systems are easily constructed with electric solenoid
valves.
The calibration gases are typically checked with triplicate runs of the refer-
ence method procedure for that gas. All runs of the reference method must
agree with the average for the three runs within 20% or they must be repeated.
The gas analysis is repeated every six months. Although many manufacturers
certify a longer shelf life, experience has shown that manufacturer
calibration gas certification is subject to error.
EPA is currently studying the option of using National Bureau of Standards
(NBS) calibration gases or gases traceable to NBS standards, instead of
requiring reference method analyses. NBS gases are relatively accurate and
stable but are more expensive than commercial gases.
Controlling the Sampling Interface/Monitor System—The best system does not
require elaborate control mechanisms. The necessary controls are easily
installed and maintained by owner/operator personnel. The suggested controls
include the following:
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• Temperature control at the cold end of the heated sample line. This is
to ensure that the gases are above freezing to protect the lines from
fracture or blocking. Temperature is also controlled at the refrigerated
condenser to maintain moisture removal efficiency.
• Pressure control is needed at the pump discharge to protect the pump.
The pressure drop across the fine filter is monitored to protect the
analyzer and to ensure proper system function (most analyzers are
sensitive to pressure changes).
• Gas flowrate control is installed to make certain the analyzer receives
the correct gas flow. This is not critical, since most analyzers are
relatively insensitive to minor flowrate change.
• Calibration gas valving automatically injects calibration gases once
every 24 hr. This can be accomplished with a simple electric solenoid
valve. The calibration gases should flow through the sampling system at
the same condition of temperature, pressure, and flow as does the stack
gas.
5.9.1.2 In-Situ Monitoring Systems—
The problems and expense associated with extractive monitoring systems have
led to the development of instrumentation that can directly measure source-
level gas concentrations in the stack. The so-called in-situ systems do not
modify the flue gas composition and are designed to detect gas concentrations
in the presence of particulate matter. Since particulate matter causes a
reduction in light transmission, in-situ monitors utilize advanced
electro-optical techniques to eliminate this effect when detecting gases.
Cross-stack in-situ monitors measure a pollutant level across the complete
diameter or a major portion of the diameter of a stack or duct. Stratifica-
tion effects are lessened by the use of cross-stack instruments, since an
average reading is taken over a relatively long sample path. There are two
types of cross-stack monitors: single pass and double pass.
• Single-pass systems locate the light transmitter and the detector on
opposite ends of the optical sample path. Since the light beam travels
through the flue gas only once, these systems are termed single pass.
• Double-pass systems locate the light transmitter and the detector on one
end of the optical sample path. To do this, the light beam must fold
back on itself by the use of retroreflector. The light beam will tra-
verse the sample path twice in going from the instrument housing to the
retroreflector and back to the instrument. Double-pass systems are
easier to service than single-pass systems, since all of the active
components are in one location.
In-stack in-situ systems monitor emission levels by using a probe that meas-
ures over a limited sample pathlength. All of the commercial, optical
in-stack monitors are double-pass systems.
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In principle, currently marketed cross-stack gas analyzers present many advan-
tages over extractive monitoring systems. A cross-stack system may allow
greater flexibility in site selection, since an average sample reading is
taken over a relatively long path. It should be noted, however, that gas
stratification in a duct or stack is a two-dimensional phenomenon, not one-
dimensional. A cross-stack monitor can linearly average concentrations over
its measuring path, but does not properly weigh the contributions of strati-
fied areas to the measurement. For severe cases of stratification, the prob-
lem of obtaining representative concentration values may be comparable to the
problems encountered by point monitors.
One of the principal marketing features of cross-stack analyzers is that a
single instrument can monitor a number of gases and even opacity. The cost of
such a monitor can be comparable to the purchase price of three or four
separate instruments combined in an extractive system.
There are, however, a number of disadvantages associated with the cross-stack
monitors. An in-situ cross-stack monitor can monitor only one flue or stack
at a time. Costs might be prohibitive if a number of stacks must be monitored.
In such a case, multiple probes and sampling lines leading into a single
extractive system might be the better choice. Problems with optical misalign-
ment, vibration affecting the optical systems, and the failure of electronic
components also can occur. It is common among vendors of these instruments to
offer service packages whereby the systems are periodically checked by a
company serviceman. A service package generally will ensure that a system
will continue to function, but the cost involved may bring the operating
expenses to a level comparable to that of an extractive system.
5.9.2 Analyzers
5.9.2.1 NDIR Analyzers—
Nondispersive infrared (NDIR) analyzers have been developed to monitor S02,
NO , CO, C02, and other gases that absorb in the infrared, including hydro-
carbons. NIDR instruments utilize a broad band of light that is centered at
an absorption peak of the pollutant molecule.
This broad band is usually selected from all the light frequencies emitted by
the infrared source by using a bandpass filter. Table 5-10 gives the band
centers for several of the gases found in source emissions.
In a typical NDIR analyzer, infrared light from a lamp or glower passes
through two gas cells—a reference cell and a sample cell. The reference cell
generally contains dry nitrogen gas, which does not absorb light at the wave-
length used in the instrument. As the light passes through the sample cell,
pollutant molecules will absorb some of the infrared light. As a result, when
the light emerges from the end of the sample cell, it will have less energy
than when it entered. It also will have less energy than the light emerging
from the reference cell. The energy difference is then sensed by some type of
detector, such as a thermistor, a thermocouple, or microphone arrangement.
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TABLE 5-10. INFRARED BAND CENTERS OF SOME COMMON GASES
Location of
band centers, Wave number,
Gas urn cm 1
NO
N02
S02
H20
CO
C02
NH3
CH4
Aldehydes
5.0 - 5.5
5.5 - 20
8-14
3.1
5.0 - 5.5
7.1 - 10
2.3
4.6
2.7
5.2
8-12
10.5
/ 3.3
7.7
3.4 - 3.9
1,800 - 2,000
500 - 1,800
700 - 1,250
1,000 - 1,400
1,800 - 2,000
3,200
2,200
4,300
850 - 1,250
1,900
3,700
950
1,300
3,000
2,550 - 2,950
The advantages of the NDIR-type analyzers are their relatively low cost and
the ability to apply the method to many types of gases. Generally, a separate
instrument is required for each gas, although several instruments have inter-
changeable cells and filters to provide more versatility. Problems associated
with the method are those that arise from interferring species, the degrada-
tion of the optical system caused by corrosive atmospheres, and in some cases,
limited sensitivity. The microphone type detectors are sensitive to vibration
and often require both electronic and mechanical damping, for example, by
placing the instrument on a foam insulation pad.
5.9.2.2 Nondispersive Ultraviolet Analyzers (NDUV)--
Several available nondispersive systems use light in the ultraviolet and
visible regions of the spectrum rather than in the infrared. Essentially, the
analyzers measure the degree of absorption at a wavelength in the absorption
band of the molecule of interest. This is similar to the NDIR method, but the
major different is that a reference cell is not used. Instead, a reference
wavelength, in a region where the pollutant has minimal absorption, is
utilized.
This method of analysis is often differential absorption, since measurements
are performed at two different frequencies. This method is not limited to
extractive monitoring systems, but it also is used in both in-situ analyzers
and remote sensors. As with all extractive monitoring systems, particulate
matter is removed before entering the analyzer. It is not necessary, however,
to remove water vapor in some of these systems. A heated sample line and
heated cell prevent condensation in the analyzer. Since water does not absorb
light in this region of the ultraviolet spectrum, no interference occurs.
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5.9.2.3 Polarographic Analyzers—
Polarographic analyzers have been called voltammetric analyzers or electro-
chemical transducers. With the proper choice of electrodes and electrolytes,
instruments have been developed utilizing the principles of polarography to
monitor S02, N02, CO, 02, H2S, and other gases.
The transducer in these instruments is generally a self-contained electro-
chemical cell in which a chemical reaction takes place involving the pollutant
molecule. Two basic techniques are used in the transducer: (1) the utiliza-
tion of a selective semipermeable membrane that allows the pollutant molecule
to diffuse to an electrolytic solution, and (2) the measurement of the current
change produced at an electrode by the oxidation or reduction of the dissolved
gas at the electrode.
The electrolyte of the cell generally will be used up in 3 to 6 months of
continuous use. The cells can be sent back to the company and recharged, or
new ones can be purchased. It is extremely important that the sample gas be
conditioned before entering these analyzers. The stack gas will come to
ambient temperature, and the particulate matter and water vapor are removed to
avoid fouling the cell membrane.
5.9.2.4 Electrocatalytic Oxygen Analyzers—
A new method for the determination of oxygen has developed over the past
several years as an outgrowth of fuel-cell technology. These so-called fuel-
cell oxygen analyzers are not actually fuel cells, but simple electrolytic
concentration cells that use a special solid catalytic electrolyte to aid the
flow of electrons. These analyzers are available in both extractive and
in-situ (in-stack) configurations. This versatility of design is making them
popular for monitoring diluent oxygen concentrations in combustion sources.
In basic electrochemistry, one of the common phenomena studied is the flow of
electrons that can result when two solutions of different concentrations are
connected together. The electron flow results from the fact that the chemical
potential is different on each side and that equilibrium needs to be reached.
There are two half-reactions that take place in this example.
The instruments designed to continuously monitor oxygen concentrations utilize
different concentrations of oxygen gas expressed in terms of partial pres-
sures. A special porous material, zirconium oxide, serves both as an
electrolyte and as a high temperature catalyst to produce oxygen ions.
If the temperature is well stabilized and the partial pressure of the oxygen
on the reference side is known, the percentage of oxygen in the sample can be
easily obtained.
One problem with the method is that carbon monoxide, hydrocarbons, and other
combustible materials will burn at the operating temperature of the device.
This will result in a lowering oxygen concentration in the sample cell, which,
however, would be insignificant for concentrations of the combustible
materials on the ppra level.
5-106
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5.9.2.5 Paramagnetic Oxygen Analyzers--
Molecules will behave in different ways when placed in a magnetic field. This
magnetic behavior will be either diamagnetic or paramagnetic. Most materials
are diamagnetic and when placed in a magnetic field will be repelled by it. A
few materials are paramagnetic; they are attracted by a magnetic field. Para-
magnetism arises when a molecule has one or more electrons spinning in the
same direction. Most materials will have paired electrons; the same number of
electrons spinning counterclockwise as spinning clockwise. Oxygen, however,
has two unpaired electrons that spin in the same direction. These two elec-
trons give the oxygen molecule a permanent magnetic moment. When an oxygen
molecule is placed near a magnetic field, the molecule is drawn to the field
and the magnetic moments of the electrons become aligned with it. This strik-
ing phenomenon was first discovered by Faraday and forms the basis of the
paramagnetic method for measuring oxygen concentrations.
There are two methods of applying the paramagnetic properties of oxygen in the
commercial analyzers. These are the magnetic wind or thermomagnetic methods
and the magnetodynamic methods:
• Magnetic Wind Instruments (Thermomagnetic)—The magnetic wind instruments
are based on the principle that paramagnetic attraction of the oxygen
molecule decreases as the temperature increases.
Several problems can arise in the thermomagnetic method. The cross-tube
filament temperature can be affected by changes in the thermal conduct-
ivity of the carrier gas. The gas composition should be relatively
stable if consistent results are desired. Also, unburned hydrocarbons or
other combustible materials may react on the heated filaments and change
their resistance.
• Magneto-dynamic Instruments—The magneto-dynamic method utilizes the
paramagnetic property of the oxygen molecule by suspending a specially
constructed torsion balance in a magnetic field. When a sample contain-
ing oxygen is added, the magnet attracts the oxygen and the balance
swings to realign itself with the new field. Light reflected from a
small mirror then can be used to indicate that degree of swing and hence,
the oxygen concentration.
Water and particulate matter have to be removed before the sample enters this
monitoring systems. It should be noted that NO and N02 are also paramagnetic
and may cause some interference in the monitoring method if high concentra-
tions are present.
Tables 5-11, 5-12, and 5-13 summarize information on extractives and in-situ
monitoring instrumentations, including range capabilities, approximate cost,
and ability to measure specific effluent gas components.
5-107
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TABLE 5-11. EXTRACTIVE MONITOR SUMMARY*
Approximate
Instrument
Beckman
Bendix
Esterline
Angus
Horiba
Infrared Ind.
Leeds and
Northrop
MSA
Teledyne
Gases measured Measurement
SO, NO NO, CO, CO 0, range
Nondispersive infrared instruments
XX XX Various ranges
in ppm or %
XX XX 0.5 ppm - 50%
XX XX 2 ppn - 100%
X X X X X 10 - 2,000 ppm
XX XX 200 ppm - 10%
X X 0 - 1,000 ppm
X X XX 0-2,000 ppm
XX 0 - 1.000 ppm
cost in
thousands
of dollars
3 - 5.4
3-4
5
3-5
1-2
5.5
3-4
11 - 13
Extract differential absorption instruments
CEA
DuPont
Esterline
Angus
Teledyne
Western
Beckman
IBC/Berkeley
Oynasciences
InterScan
Corp.
Teledyne
Theta Sensors
(MRI)
Western
Precipitator
(Joy)
CEA
Dynatron
Lear Siegler
MSA
Teledyne
Thermox
Beckman
MSA
CEA
SCOTT
Ledds and
Northrop
Taylor-
Servomex
XX X 2-50,000 ppm
XXX 1 ppm - 100%
X X
X 2 ppm - 100%
XXX X 75 - 5,000 ppm
Polaroaraphic instruments
X 0-25%
XXX 0 - 1,000 ppm
X XX XX 0.01- 200,000
ppm
XXX
X 0-25%
X X X 1 - 20,000 ppm
X X X X X 0 - 1.000 ppm
Electrocatalytic instruments
X 0-25%
X 0-25%
X 0-25%
X 0.1-20.8%
X 0-25%
X 0-25%
Paramagnetic instruments
X 0-25%
X 0-25%
X
X 0 - 100%
X
X 0 - 100%
3-6
13 - 23
12 - 14
12 - 22
1 - 1.5
2-55
2 - a
i
1 5
1-4
1 5
45-58
2
1 5
2
3
1-15
1 - 1.5
aThis is a representative listing of known vendors. It is not intended
to be a complete listing of all suppliers of such equipment.
5-108
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TABLE 5-12. ZN-SITU MONITOR SUMMARY
a
Approximate
Method Measure- cost in
Cases measured Opac- In- Cross- ment thousands
SO, NO CO, CO 0, ity stack stack range of dollars
X X X X
CEA
Contraves
Goerz
Dynatron
Environmental XX XX
Data Corp.
Lear Siegler X X
Westinghouse
0 - 25%
0 - 5.000
ppn
30
20 - 40
0 - 500; 4.5 - 17
0 - 1.000;
0 - 1.500
ppm
*This is a representative listing of known vendors. It is not intended to be a
complete listing of all suppliers of such equipment.
TABLE 5-13. OXYGEN ANALYZER SUMMARY3
Analysis method
Vendor Paramagnetic Polaroqraphic
Astro
Beckman X
Cleveland X
Controls
Corning
Dynasciences X
Oynatron
Esterline Angus X
Gas Tech X
Hays-Republic
Joy X
Lear Siegler
Leeds and X
Northrop
Lynn X
MSA X
Scott X
Taylor- X
Servomex
Teledyne X
Thermox
Theta Sensors X
Westinghouse
Electro-
catalytic
X
X
X
X
X
X
X
X
X
Sampling type
In-Situ Extractive
X X
X
X X
X
X
X
X
X
X X
X
X
X
X
X
X
X
X
X
X
X
aThis is a representative listing of known vendors. It is not intended to
be a complete listing of all suppliers of such equipment.
5-109
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5.10 PLANT CONDITION MONITORING SYSTEMS
The presence of defects in machinery and mechanical structures can lead to
catastrophic failure. Plant facilities which are super-designed for safety
and minimal downtime (e.g., nuclear power plants and ol1/ ^coLs Jower
large fixed-base condition monitoring systems for lowered repair costs, lower
production losses, and decreased accident and fire risks.
Defects present are characterized by corresponding abnormalities and changes
in acoustic and vibratory emission patterns. By the use of sensors small
defects in bearings and gears, growing cracks in shafts and weld joints loose
parts and operating deficiencies such as pump cavitation can be detected
early enough to either allow correction of the problem or provide time for
predictive maintenance planning. These plant-wide incipient failure detection
(IFD) systems can sequentially examine more than 800 channels and quantize
their vibratory or acoustic energy levels. The signal is compared with the
previously obtained energy level retrieved from the memory bank of a dedicated
minicomputer. Significant deviations are programmed to cause an alarm
annunciation [32].
5.10.1 Machine Vibratory Signature Analysis
Traditional machinery vibration signature analysis (MVSA) is a method of
determining the mechanical condition of an operating machine by monitoring and
analyzing frequency characteristics produced by internal elements using narrow
band spectrum analysis techniques.
Vibration signature analysis makes use of the fact that vibration produced by
a machine contains a great number of discrete frequencies some of which can
be tied directly to the operating dynamics of particular elements within the
machine, when the amplitude of a specific frequency or pattern of frequencies
changes, it represents a change within the machine and possibly a
deteriorating condition.
5.10.2 High Frequency Acoustic Emission Analysis
The basic premise of high frequency acoustic IFD monitoring is that the pres-
ence of defects in machinery and mechanical structures is characterized by
corresponding abnormalities and changes in the acoustic signature and that
machinery vibration is inevitably accompanied or even preceded by metal defor-
mation. Metal deformation generates "acoustic emissions," i.e., noise
resulting from the propagation of intergranular dislocations in material
subjected to stress.
For early identification of failure these defects must be detected when they
first develop and are quite small. However, the amount of detectable energy
released from a small defect is usually negligible in comparison to normal
machinery operating noise. Fortunately, operating noise tends to be ""«"-
trated in the low frequency range of vibration while defect-originated energy
extends to much higher frequencies. It is this frequency separation that
accounts for the success of IFD technology.
5-110
-------
High frequency acoustic techniques have been shown to be more effective in
detecting mechanical failures at a very early stage then the popularly used
low frequency vibration and sound techniques. Furthermore, high frequency
acoustics have very often picked up fluid flow deviations such as pump
cavitation and mechanical seal leakage.
5.11 SCRUBBER/QUENCH WATER AND ASH HANDLING
5.11.1 Description of Potential Incinerator Wastes
Operation of a hazardous waste incinerator typically produces a number of
secondary products, namely quench water, scrubber effluent, and ash. The
following subsections describe each of these possible secondary wastes and
provide information on their potential composition.
5.11.1.1 Quench Water—
Following the afterburner section, a quench section is usually installed to
reduce the combustion gas temperature prior to entering the scrubber. Enter-
ing temperatures are approximately 1,800°F to 2,000°F and the exit temperature
may be below 250°F. The inclusion of the quench section becomes necessary
when nonmetallic materials are used for scrubber construction and packing.
The upper temperature limit for sustained operation is about 300°F for poly-
ester and epoxy fiberglass and 150°F for PVC [33]. The gases are commonly
quenched with a water spray at a rate capable of reducing the gas temperature
to a desired level. Besides lowering the flue gas temperature, this quench
water functions as a scrubber by removing some particulate matter and certain
gaseous pollutants from the exhaust stream.
Four basic designs are used to generate the water spray in quench towers:
(1) Air and water nozzle (2) High pressure sequenced spray nozzles (3)
Orifice plate (4) Low pressure venturi or variable throat venturi
The type of device used depends upon the composition of the quench water, the
composition of the exhaust gas, the type of air pollution control equipment
being used, the initial investment, and maintenance considerations. Various
quenching devices are illustrated in Figure 5-42.
The air and water nozzle system is the most sophisticated device and requires
a fresh water feed, free from particles which might clog the spray nozzles.
It also requires the least amount of water because it produces small, uniform
droplets which efficiently cover an exhaust area.
High pressure sequenced spray nozzles operate on a demand basis. Initially,
certain banks of spray are activated and as the gas temperature rises, addi-
tional banks come on to maintain a constant temperature. This system, like
the air and water nozzle system, cannot operate on clarified recycle water due
to dissolved and suspended solids,- however, where fabric filters or
electrostatic precipitators follow, these types of systems are necessary to
prevent damage to these units from excessive heat.
5-111
-------
COLD GAS OUT
HOT GAS IN
QUENCH SPRAY
QUENCH
SPRAY
THROAT
THROAT —
ADJUSTMENT
COLD GAS OUT
VARI ABLE THROAT VENTURI
A A A A
A A A A A
HOT GAS IN
SPRAY
NOZZLES
.QUENCH
SPRAY
COLD GAS OUT
VENTURI
SPRAY TOWER
ORIFICE
PLATE
COLD GAS OUT
ORIFICE
PLATE"
J
• QUENCH SPRAY
HOT GAS IN-
ORIFICE QUENCH TOWER
Figure 5-42. Various quenching devices [34].
5-112
-------
An orifice plate is an effective precleaner capable of removing particulates
down to 5-10 microns [34]. It is simply a perforated plate through which
water is forced. It is very effective preceding a high energy scrubber be-
cause it removes the larger particles which would create an erosion problem in
the high velocity throat.
Another device which is essentially maintenance free and works well when used
ahead of a scrubber is a low pressure venturi. Water nozzles, located just
upstream of the venturi throat, saturate the flow and knock out the larger
particles. In a variable throat venturi, gas velocities and corresponding
pressure drop can be varied by adjusting throat diameter. For any particle
size, the collection efficiency increases with increased energy consumption.
Increased energy can be obtained by increasing gas velocities through the
variable throat. Due to their larger and less restrictive water nozzle sys-
tems, both the orifice plate and low pressure venturi or variable throat
venturi quenching devices may be operated using recycled quench water, after
passing through a reduction and clarification process.
A generalized schematic of incinerator facilities and schematic of a rotary
kiln facility with quench spray chamber and venturi scrubber are illustrated
in Figures 5-43 and 5-44, respectively.
Material selection of the nozzles is very important because the cooling effect
of the spray nozzle can cause condensation of the hot acidic gases along the
wall of the spray nozzle, and these gases will react with the metal at or
below the dewpoint of the acid. Also, the water will immediately react with
the acid gas to form, for example, hydrochloric acid mist in the fine spray
droplets, if an organochlorine waste is being destroyed. These are recycled
and result in direct contact with the nozzle body.
The main body of the quench chamber is in contact with the highly acidic
solution formed by the partial scrubbing of the combustion gases. Material
selection is also important for this section. Hastelloy alloy B is a material
generally recommended for the quench section, spray nozzles, and the duct work
leading into the quench chamber. This material is a nickel-molybdenum alloy
developed primarily for resistance to the corrosive effects of hydrochloric
acid. This alloy also possesses useful high-temperature properties. In oxi-
dizing atmospheres, the alloy may be used at temperatures up to 1,400°F. In
reducing atmospheres, the alloy may be used at substantially higher
temperatures.
Hastelloy alloy B is particularly well suited for equipment handling hydro-
chloric acid at all concentrations and temperatures including the boiling
points. Hastelloy alloy B is easily fabricated, and can be forged and cold-
formed by a variety of methods. Most of the common welding methods can be
used to weld it, although the oxy-acetylene process is not recommended when
the alloy is to be used in corrosion service.
Inconel alloy 625 and Incoloy alloy 825 are two other materials which show
good resistance to hydrochloric acid and could thus be used in the quench
section.
5-113
-------
GAS
OIL
WATER FLOW
AIR
AUX.
REACTION
CHAMBER
WASTE FEED
QUENCH
SCRUBBER
STACK
•ASH
Figure 5-43. Generalized schematic of incinerator facility.
SECONDARY
AIR
LIQUID
PUMPABLE
DRUMMED NON-PUMP—»1
ROTARY KILN
WATER-
PLENUM AIR
QUENCH WATER
CHAMBER
SECONDARY
COMBUSTION CHAMBER
WATER
I • av ASH I
VENTURI
THROAT
WATER/ASH
INDUCED DRAFT FAN
| SI EVE TOWER (DEMI STERI
WATERMSH
ASH/DRUMS
Figure 5-44.
Schematic of rotary kiln facility with quench
spray chamber and venturi scrubber.
5-114
-------
The composition of the quench water depends directly on the wastes being
incinerated. Table 5-14 summarizes the possible air pollutants that may be
produced and captured by the quench tower and by other air pollution control
devices. Because chlorinated organic compounds constitute the most common
type of hazardous waste disposed of by incineration, quench waters are gener-
ally acidic and must be neutralized before discharge. Although hazardous
species would not typically be present in quench water, this is typically
verified before the effluent is disposed. Quench water is normally combined
with the scrubber effluent for treatment and disposal.
TABLE 5-14. POTENTIAL AIR POLLUTANTS FROM HAZARDOUS WASTE INCINERATION
Likely removal sites
Hazardous waste
Air pollutants
Quench
tower
Scrubber
Baghouse
or ESP
Organic materials containing:
1. C, H, O only
2. Cl
3. Br
4. F
5. S
6. P
7. N
8. C, N
Materials containing some
inorganic components:'
1. Nontoxic minerals only,
e.g., Al, Ca, Na
2. Toxic elements including
metals, eg., PB, As, Sb
Thermal NOX
HC1 X
HBr X
HP X
SOX
PaOs
NOx
CH~ compounds X
Particulate matter X
Particulate matter X
Volatile species9
X
X
aBased on complete destruction (i.e., oxidation) of hazardous waste.
bNOx produced from atmospheric nitrogen at high temperatures (about 1,100°C) in the
incinerator.
CNOX is not normally controlled. Special scrubbers have been developed for NOX con-
trol in special circumstances.
^Alkaline scrubbers are required for efficient SOx control.
eSpecial high efficiency scrubbers are needed to collect phosphoric acid mist.
A portion of the inorganic components may be removed as bottom ash from the
incinerator.
9Certain elements from volatile species (e.g., AS2O3) that condense out in the
exhaust gas as the temperature falls. They can be collected in the gas phase by
special scrubbers or as particulate matter at low temperatures by normal particulate
control equipment.
5-115
-------
5.11.1.2 Scrubber Effluents—
Characterization of scrubber effluents varies considerably from that of the
quench water. Quench towers are primarily used to reduce the combustion gas
temperatures prior to entering the scrubber, whereas scrubbers are primarily
used to reduce noxious gases from the combustion gas prior to discharge to
atmosphere. Commonly used scrubber types, design, material of construction,
scrubber selection for specific applications, advantages, and disadvantages,
etc., are covered in detail in Chapter 4.
In an incinerator burning chlorinated organic compounds, if water is the
scrubbing fluid, the wastewater effluent will contain suspended particulates,
dissolved HCl (i.e., hydrochloric acid), and other soluble constituents which
may be present (e.g., trace quantities of organics and waste constituents that
may be soluble). If alkaline scrubbing solutions are used, the HCl will
undergo neutralization reactions to produce additional water and salts (either
NaCl or CaCl2 depending on whether NaOH or Ca(OH)2 was used in the scrubbing
solution). Because alkaline materials are often used in excess, residual
amounts of these substances will be present. The wastewater will also contain
suspended particulates and any soluble combustion products.
The venturi scrubbing process involves either a single pass of the scrubbing
fluid or recirculation of the scrubbing fluid. If recirculation is used,
scrubber fluid is recirculated through the venturi scrubber until the total
dissolved solids (TDS) content reaches approximately 3% [35]. When this
occurs, a portion of the scrubbing fluid is removed (blowdown) and new scrub-
bing fluid is added to make up for the fluid lost as blowdown. The blowdown
from the single pass or recirculation scrubbing systems is neutralized (as
needed) before delivery to on-site wastewater treatment processes, on-site
storage facilities (e.g., evaporation ponds), or dispensing to the municipal
sewer or a receiving water body. Single pass and recirculating scrubber
systems are illustrated in Figure 5-45 and 5-46, respectively.
Alternative types of scrubber systems have been designed to recover HCl pro-
duced during organochlorine incineration. Such systems can produce commercial
grade hydrochloric acid streams with concentrations ranging between 20% and
60% HCl [35]. These systems utilize aqueous solutions to absorb HCl from the
combustion chamber effluent gas stream, and the resulting solution is concen
trated via water extraction procedures. Residual HCl that may be left in the
remaining combustion gas stream can be removed by passing this stream through
an alkaline neutralization tower, or by using conventional gas scrubbing
procedures.
Characteristics of Blowdown from Recirculating Scrubbers—Blowdown from recir-
cu lation systems occurs when the salinity reaches approximately 3 percent.
This relates to a TDS value of 30,000 milligrams per liter [35]. The blowdown
rate is variable, depending on the amount of chlorine in the liquid
incinerated and on the liquid feed rate.
Characteristics of Single-Pass Scrubber Effluent—The characteristics of
single-pass scrubber effluents are highly variable, depending on the chlorine
content of the liquid incinerated, the liquid feed rates, the scrubber
solution feed rates, and the efficiency of the scrubber. Because single-pass
5-116
-------
TO STACK AND
ATMOSPHERE
SCRUMER SOLUTION
(NOMINAL 10 «MOHI
PAWING
ADD WATER
AMOMOH
S &
-KMISTEK
' SWAY 5
CITY
WATER
- PACKED UD
SCRUMER RJB. LW
WASH TOP
I SdUIKX SOUITION
HOLD INS TANK
«*_ADD NEUTRALIZINC N*OM OR
ACID AND DILUENT WATER
PRIOR TO DISPOSAL
NEUTRALIZED SOLUTION TO SEWER SYSTEM OR
EVAPORATION/STORAGE POND
Figure 5-45. Single-pass scrubber system [33]
TO STACK AND
ATMOSPHERE
SCRUBBER SOLUTION
;®k
NOMINAL 10«NaOHI
PACKING
ADD WATER
ANDNlOH
-DEMISTER
'SPRAYS
^,$J—PACKED BED
xj-jji SCRUBBER ^
CITY
WATER
WASTE FEED
AIR ea i
i3
I m ' T
ADD NEUTRALIZING N*OH OR
ACID AND DILUENT WATER
PRIOR TO DISPOSAL
NEUTRALIZED SOLUTION TO SEWER SYSTEM OR
EVAPORATION/STORAGE POND
Figure 5-46. Recirculating scrubber system [33]
5-117
-------
systems have so many variables, it is not possible to obtain a normal or aver-
age IDS concentration. However, it is possible to estimate the magnitude of
IDS concentration. This has been done by using two sets of data shown in
Tables 5-15 and 5-16. The data were picked because their operating parameters
produced two extremes in scrubber water quality, as shown in Table 5-15.
Generally, scrubber wastewaters will contain TDS concentrations less than
40,000 milligrams per liter.
TABLE 5-15.
SCRUBBER WATER AND WASTE PARAMETERS FOR TWO
LAND-BASED LIQUID INJECTION INCINERATORS [35]
Waste incinerated
Fresh scrubber water feed rate
(liters/min)
Caustic solution feed rate
(liters/min)
Type of solution used
Liquid waste feed rate
(kg/hr)
Elemental chlorine content of
the waste
Hexachlorocyclo-
pentadiene
60
23.8
12% NaOH
52.8
77%
Nitrochloro-
benzeneb
3,200
8.5
32% Ca(OH)_
1,893
10%
aSource: Reference 31.
Source: Reference 33.
TABLE 5-16. SCRUBBER WATER QUALITY [35]
Waste incinerated
Hexachlorocyclo-
Nitrochloro-
benzene
Chlorides (mg/L)
Calcium (mg/L)
Sodium (mg/L)
Total dissolved solids (mg/L)
11,000
--
25,670
36,670
1,300
530
~"
1,830
It can be expected that the HC1 recovery processes will have much lower TDS
concentrations than systems which do not recover HCl because a large propor-
tion of the dissolved ions would be removed during recovery of the acid.
Scrubber effluents generally contain very little organic material due to high
waste destruction efficiencies required.
5-118
-------
The particular gaseous pollutant of interest may require scrubbing with a
mediSm specific for the pollutant. Water is adequate for a gas such as HCl.
£r™hS scrubber media may be required for S02. NO etc. In some cases
multiple stages are required to efficiently remove axcombination of gaseous
pollutants, with each stage specific for given pollutant Two-stage and
?hree-stage scrubber systems are illustrated in Figures 5-47 and 5-48^ respec
tivelv The type of technology illustrated in Figure 5-47 is not normally
utilized for ^hazardous wasteincinerator. It is presented here for scrubber
review The three stage scrubber system illustrated in Figure 5-48 was imple-
mented for a research project in an attempt to very carefully scrub effluent
from a pesticide incineration program.
FEEDERS
I.D. FAN
SCRUBBER
WATER IN
2-STAGE
SCRUBBER
ASH
I
SCRUBBER
WATER OUT
Figure 5-47. Incineration system with two-stage scrubber [36].
solid residue that remains after a material is
Ash produced during incineration is primarily inorganic and ?-.
basic categories. Fly ash consists of the ash that is entrained i
gases leaving the incinerator and which is usually captured in air
control equipment. Bottom ash refers to the ash remaining in the combustion
chamber after incineration and is normally associated with inerts. The com
position of the ash depends on the composition of the waste being Jn"n^ated
and can therefore vary greatly. Because hazardous waste incinerators "e
designed for complete destruction of toxic organic compounds, the ash normally
contains very little carbonaceous material. Solid materials not ^"P^*
to oxidation (e.g.. glass or ceramic) consitute the major ash species. Amount
of ash produced is very small in relation to total mass of waste incinerated.
The relative proportion of fly ash to bottom ash is influenced by the
composition and ?he incinerator design and operation. As •J
ash and relatively little fly ash result when liquid (except when
from a complex chemical process that has inert materials in it or from a
are
5-119
-------
EXHAUST
AIR FROM
BUILDING
VENTIUTI
SYS1BM
INCINERATOR
FEED
INCINERATOR
WATER TRAP
SCRUBBER
HEXYUJMI
GLYCOL
SCRUBBER
III
J '
VSB,
Tt
^gpr
NOZ
I
\.
n
ZL
y
E
1
H20 SCRUBBER I
Figure 5-48. Incineration system with three-stage scrubber [37].
blending procedure that creates incompatible reactions that produce inerts) or
gaseous wastes are incinerated.
5.11.2 Sampling and Analysis of Quench/Scrubber Water and Ash
Samples collected must be a representative sample of the whole water or ash.
A representative sample for water can be collected by using various techniques
and devices such as a coliwasa, automatic composite samplers like Isco,
Manning, pond sampler, weighted bottle sampler, etc. Representative samples
for ash can be collected by using devices such as a grain sampler, sampler
corer, trowel or scoop, etc. Sampling devices and strategies are covered in
detail in Chapter 3. Water samples are usually preserved because of any
unstable species with the addition of appropriate preservatives. Where pos-
sible, samples are stored in a cool (4°C) and dark area prior to shipment to
the laboratory for analysis.
The analysis of samples is directed primarily at determining the concentration
Of:
• Principal chemical species known to be present in the waste incinerated
and believed to be hazardous. In some cases these will represent dis-
crete chemical species such as nitrochlorobenzene and HCB. In other
cases, such as those involving the incineration of tarry wastes from
captan, rubber manufacturing and TDI, the analyses may have to be
restricted to a general class of chemical species such as total organic
chloride, total aromatic amine, etc.
5-120
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• Primary decomposition products of waste such as chlorides, phosphates,
sulfates, nitrates.
Solids can be analyzed via soxhlet extraction and water via liquid-liquid
extraction.
5.11.3 Handling of Quench/Scrubber Wastewater
Quench water and scrubber effluents are normally combined for treatment and
ultimate disposal. Depending on the scrubbing liquids used and the gaseous
contaminants removed, wastewater may contain chlorides, fluorides, sulfites,
sulfates, phosphates, bromides, and bromates, as well as particulate matter.
Liquid waste streams containing sodium fluoride can be treated with lime or
limestone slurry to yield the insoluble calcium fluoride. Sulfates, phos-
phates, and fluorides can be readily removed from the wastewater stream be-
cause of the low solubility of their calcium salts. Therefore, treatment
normally includes clarification (to remove particulates), neutralization (to
take care of any residual acid or base that may still be present), and dilu-
tion (to help control IDS levels). Particulates which are insoluble in the
scrubber fluid become suspended solids in the scrubber wastewater. If the
particulates dissolve in the scrubber fluid, they contribute to the waste-
water's IDS level. Suspended solids in scrubber wastewater generally present
little, if any, problems because their concentrations are usually less than 5
mg/L [35]. Suspended solids are usually removed by on-site settling ponds.
Overflow from settling ponds can be recycled to scrubber.
Wastewater with either high or low pH levels is neutralized prior to final
discharge (to a municipal sewer, or receiving stream). This is usually accom-
plished by adding either acid or base.
The high concentration of total dissolved solids (due to NaCl, CaCl2 and in
some cases the excess NaOH not used to neutralize HCl) is also reduced. This
is usually accomplished by piping scrubber effluents to in-plant treatment
systems or by diluting with other plant process streams and storing in a hold-
ing pond or lagoon.
In geographical locations with high evapotranspiration rates, solar evapora-
tion could be used as a method for disposing of scrubber wastewater. For such
a method to be considered environmentally acceptable, the scrubber wastewater
would have to be devoid of potentially volatile materials which are hazardous.
The ponds used for evaporation are periodically drained, and the accumulated
sludge removed. Quench/scrubber effluents, evaporation sludge and ash treat-
ment, and disposal options are illustrated in Figure 5-49.
For a discharge to a municipal sewer (publicly-owned treatment works - POTW),
discharge must meet national general pretreatment standards and local POTW
requirements, and must have approval from local POTW authority for such a
discharge. By national pretreatment standards, pollutants introduced into
POTW by any source of a nondomestic discharge are not to inhibit or interfere
with the operation or performance of the works. The following pollutants may
not be introduced into a POTW:
5-121
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AUXILIARY
FUEL
(IF NEEDED I
WATER
CAUSTIC SOLUTION
(OPTIONAL)
LI QUID WASTE
AIR
GASEOUS
EFFLUENT
SEPARATOR TANK
w/DEMISTEROR
PACKED TOWER
COMBUSTION
CHAMBER
LIQUID
EFFLUENT
BURNER
RESIDUAL
NEUTRALIZATION
SEWER SYSTEM
OR OTHER
WATER BODY
ON-SITE
STORAGE
(EVAPORATION)
ON-SITE
TREATMENT
DILUTION
(IF NEEDED)
Figure 549.
Incineration process with emissions
treatment and disposal options [36].
1.
2.
3.
Pollutants which create a fire or explosion hazard in the POTW .
Pollutants which will cause corrosive structural damage to the
POTW, but in no case discharges with pH lower than 5.0, unless
the works is specifically designed to accommodate such discharges.
Solid or viscous pollutants in amounts which will cause obstruc-
tion to the flow in sewers, or other interference with the opera-
tion of the POTW .
4. Any pollutant, including oxygen demanding pollutants (BOD, etc.),
released in a discharge of such volume or strength as to cause
interference in the POTW.
5. Heat in amount which will inhibit biological activity in the POTW
resulting in interference but in no case heat in such quantities
that the temperature at the treatment works influent exceeds 40°C
(104°F) unless the works is designed to accommodate such heat.
Compliance with Prohibited Discharge Standards was required beginning August
25, 1978, except for the heat Standard which must be compiled with within 3
years, or August 25, 1981.
5-122
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For a discharge to a receiving body, an NPDES permit will be required. Such a
discharge has to meet with the limitations set in the permit. Wastewater may
require costly treatments to meet the limitations set in the NPDES permit.
The sludges or other sediments collected from settling ponds, evaporation
ponds or other types of lagoons may contain unburned wastes or toxic trace
elements (abstracted from the combustion gases as particulates or formed as
precipitates following chemical reactions occurring in the pond). Sludges
from scrubber processes are chemical sludges; these are handled and treated
carefully and possibly differently from municipal sludges. In order to insure
the fewest adverse effects, they sometimes can be properly disposed of in an
approved hazardous waste landfill in accordance with federal guidelines
mandated by RCRA.
5.11.4 Handling of Ash
Bottom ash will contain primarily inorganic and carbonaceous compounds. Less
than 3% of the total weight of carbonaceous compounds will be trace compounds,
including heavy metals. These solids can be disposed of in landfills approved
for hazardous wastes.
5.12 FUGITIVE EMISSIONS
Fugitive emissions are those which result from occurrences such as leaks in
valves and piping, entrainment from open vents or piles of material, and
transfer operations [2]. Such emissions must be minimized and/or eliminated
at hazardous waste incineration facilities. This section discusses monitoring
and techniques which may be used to control such emissions. Table 5-17
illustrates areas having fugitive emission potential.
The most likely areas of process oriented fugitive emissions are around rotat-
ing seals on kilns, piping joints and valves, ductwork leaks on the Positive
pressure side of induced draft systems, ash handling system leaks and quench
water scrubber liquid handling and treatment system leaks. For illustration
purposes, these areas are indicated in Figure 5-50. In the PrePro«« area
handling storage, and preparation of the waste for feeding into the inciner-
ator are critical operations to watch for fugitive emissions. Post-process
operations also can pose a problem, such as those which transport and treat
residue streams emanating from quenching, scrubbing, and post-treatment ot
residue.
5.12.1 Significance of Observed Emissions
The two primary concerns regarding inspection and monitoring of fugitive emis-
sions are protection of the personnel around the operation itself and the
health and welfare of those residing outside the fence limits of the "
Working conditions within the facility must be in accordance w*th Jhe
constraints defined by OSHA regulations. Such emissions outside the
area are governed by applicable ambient air regulatory constraints.
5-123
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TABLE 5-17. POSSIBLE SOURCES OF FUGITIVE EMISSIONS FROM
HAZARDOUS WASTE INCINERATOR SYSTEMS
WASTE PROCESSING AND FEED
• Waste shipping
Waste unloading
• Waste loading to preparation/processing plant
Waste processing
Crushing
• Sizing
• Washing
Drying
• Fine particulate removal or preparation for recycle
• Material transfer in waste processing plant
• Fugitives from loading/unloading storage bins
• Waste feed hopper backflow
WASTE INCINERATION AND POLLUTION CONTROL
• Waste feed
• Waste incineration/feed
• Air flow leaks in the incinerator furnace and associated systems
• Ash collection
• Stack flue gas particulate removal and disposal systems
• Ancillary equipment
• Scrubber wastes/neutralization water
• Dust collectors
• Secondary combustion units (afterburners)
• Gas/steam storage lines and transport lines
• Water treatment units
Air coolers
• Mixing chambers
• Ancillary equipment leaks
REMOVAL OR DISPOSAL METHODS
• Solids removal
• Ash transfer and storage
Recycling systems
• Transfer lines for scrubber and cooler water
• Ash transport vehicles
• Ash transport
• Ash unloading
• Ash disposal
5-124
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Ul
WASTE/FUEL FEED CARS
•VENT
PIPE JOINTS. VALVES
VOLATILE
EMISSIONS
ROTATING
SEAL LEAKS
ASH RESIDUE
SAMFU
ASH HANDLING
SYSTEM LEAKS
VAPOR/VOLATILE
EMISSIONS
DUCT LEAKS
,_._.! PMIIAIIV SCIOMWWY
•
-------
5.12.2 Fugitive Emission Control
Control of fugitive emissions is best accomplished through implementation of
good engineering management practice. Initially, for a new facility a careful
leak check is performed without hazardous components being treated in the sys-
tem Then during normal operation, visual inspection of all areas is performed
to minimize the occurrence of undetected leaks. These visual inspections
are then conducted regularly for any leaks, spills, odors, or other fugitive
emissions. All automatic control system alarms and emergency shutdown fea-
tures are also checked during the inspection to assure proper operation.
Any leak detected is recorded in a log as outlined in Section 5.12.5. Imme-
diate repair is accomplished if feasible. If immediate repair is not feasible,
as judged by the owner/operator, a sample of the leak is then taken. If ana-
lysis shows that a hazardous component is leaking at a concentration above
10 ppm, immediate temporary or permanent repair should be affected. Mainten-
ance data is recorded on the leak detection and repair survey log. This in-
cludes a recheck to make sure the repair was effective after maintenance.
For sources of fugitive dust emissions, several control alternatives are
possible. Table 5-18 illustrates the types of activities which can generate
dust (primarily around storage and ash handling), and the traditional tech-
niques or types of equipment used for air pollution control. Two decisions
need to be made initially for the control of particulate matter at a facility—
the degree of control required, and whether the system will handle dust, wet
or dry.
A wet-type particulate control system has limitations in that the wastewater
created must be collected and treated for discharge and/or recycle. Recycle
systems are preferred because of compliance with the NPDES permit program.
TABLE 5-18. CONTROL ALTERNATIVES FOR FUGITIVE DUST [38]
Type of activity
Transfer points
Conveyor belts
Hoppers, dumpers
Reclaimers
Baghouses/
scrubbers
X
X
Covers and
X
X
X
Control techniques
Wind breaks
Spray Encrusting and physical
systems agents arrangements
X
X
X
X
Paving or
spray vehicle
Stockpiling equipment
(bandwagons) *
Roads x
Piles x x
Bins, silos, bunkers X X
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5.12.3 Fugitive Emission Measurement Devices and Methodology
Source monitoring, area monitoring, and fixed-point monitoring are methods
that can be used to detect fugitive emissions. Each of these is discussed
below.
5.12.3.1 Area Monitoring— . .
To perform area monitoring, a path through the area to be monitored is pre-
determined so that one following the path will pass within a given distance
(~3 ft) from all equipment within the area to be monitored. An instrument
operator with a portable analyzer follows the predetermined path through the
area and makes a complete survey around each piece of equipment. The operator
must be careful that both the upwind and downwind sides of the equipment are
sampled. If a concentration peak is observed, the location is recorded and a
subsequent, more detailed survey made to pinpoint the exact source.
This is the same general procedure used for the regular visual inspection, but
with a portable measuring instrument. An advantage of this method is that
leaks can be detected quickly. Disadvantages include the possible detection
of other emissions from outside the process area or improper readings due to
wind gusts and wind direction variability. One outstanding disadvantage cur-
rently is that continuous portable monitoring equipment for measuring specific
hazardous air pollutants are in the developmental stage and use would need to
be examined carefully for appropriateness and utility.
5.12.3.2 Fixed-point Monitoring— . . .
In the fixed-point methodology, analyzers are placed at specific points in tne
process area to monitor automatically for fugitive emissions. Individual sam-
plers are placed either near specific pieces of equipment or in a grid pattern
throughout the process area. If a concentration peak is observed, the
operator then performs an individual component survey to detect the leak.
5.12.3.3 Source Monitoring— ._,...,•, *.
In this methodology, leaks are detected by examining each individual component.
Again a portable detector is used. The instrument sample probe is moved
along'the component surface with care that both upwind and downwind areas are
sampled For sources such as drains, residue treatment tanks, and pressure
relief valves, the probe is placed in the center and then along the periphery.
When no portable instrument is available, individual components can be en
closed in a plastic bag (where practical). Any leaks accumulate in the bag
and are exhausted through a sampling train designed to measure flow and
prepare the sample for subsequent analysis by applicable laboratory techniques.
5.12.3.4 Current Instrumentation—
Participate Measurements—Particulate sampling downwind of potential sources
can be accomplished using high volume samplers. These devices consist of a
pump and filter holder assembly encased in a weatherproof container. Ambient
air is drawn across a preweighed filter membrane by a calibrated/feedback pump
system. Filters are then weighed to obtain total mass particulate dust levels
and analyzed for appropriate components.
5-127
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Generally, a weather station is used to record wind speed, direction, tempera-
ture, atmospheric stability and barometric pressure over the sampling period.
Short-term ambient particulate levels can also be obtained by using either
piezoelectric or beta attenuation monotors. These devices provide quick
read-outs of ambient dust levels around a source. A number of readings can be
obtained over a long period of time. Analysis of the collections on the sub-
strate can be achieved as with the Hi-vol filter.
A particle size distribution of fugitive dust levels can be accomplished by
attaching size - selective units (impactors) to the inlet of a high volume
sampler. Particles are then collected on a substrate in each stage, depending
upon the aerodynamic diameter of the incoming particles.
Particles less than 15 pm (EPA's definition of inhalable particulates) can be
measured using dichotomous samplers. These devices consist of an elutriator
in series with an impactor. The elutriator collects particles less than 15 urn
and the impactor divides them into two fractions (<2.5 pm and >2.5 urn to
15 urn) which are collected on preweighed filters. Filters are then weighed
and analyzed as necessary.
Particles can also be classified using a beta attenuation device by employing
a small cyclone (inertial separator) in series with the pump. The cyclone
collects the >10 urn particles, which then allows an attenuation readout of the
<10 urn levels.
Measurement of Gases—Certain techniques for quantifying the fugitive gaseous
emission levels from sources are available, which can obtain either (1) hydro-
carbon-less-methane values or (2) if high enough concentrations exist, detec-
tion of individual components. In the latter case, a tandem-coupled gas
chromatograph/mass spectrometer unit or GC alone would be employed for analy-
sis with samples obtained by capture in a plastic bag for subsequent analysis.
Charcoal and porous polymer tubes connected to air pumps to draw ambient air
across the median can be employed. The collection median is then solvent
eluted for laboratory analysis.
Direct reading of ppm levels can be accomplished using Drager® tubes which are
reactant impregnated substances. Ambient air is hand pumped through the col-
lection median and the ppm levels read according to a color change.
Ambient total hydrocarbon levels can be measured using portable field gas
chromatographs or hand-held flame ionization detectors. These devices operate
on the same principle as the laboratory GC's except they have field use
capabilities.
5.13 MATERIALS OF CONSTRUCTION
Materials of construction have been discussed for specific equipment through-
out this chapter. This section is a repository of general information on
various materials which may be encountered at a hazardous waste incineration
5-128
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facility. Included is information regarding trade names, corrosion
resistances, and typical uses of both ferrous and nonferrous metals and other
nonmetallic materials.
The general corrosion resistance properties are discussed. In most inciner-
ator, receiving, storage, feed situations, and residue handling, the flow
stream will contain contaminants, so corrosion problems will be maximal. This
section will allow the permit writer to augment his knowledge of the materials
involved and check the recommended application.
5.13.1 Metals
(1) Cast Iron - This material is found in many cast process components
such as pump bodies, impellers, valve parts, etc. Cast iron is a
general term applied to high carbon-iron alloys containing silicon.
Common varieties are: gray, white, malleable, ductile, and nodular.
The material is quite susceptible to oxidation or "rust".
Increasing the silicon content to over 14% produces an extremely
corrosion resistant material; e.g., Duriron, which is very hard and
resists erosion-corrosion (notable exception: hydrofluoric acid).
The alloy is sometimes modified by the addition of 3% molybdenum,-
e.g., Durichlor or Durichlor 51, for increased resistance to hydro-
chloric acid and chlorides.
In addition to alloys using silicon and molybdenum, other alloys
using nickel, chromium and copper also produce improved corrosion
resistance. Copper addition causes the metal to better withstand
attack from sulfuric acid. High nickel-chromium cast irons with and
without copper; e.g., Ni-Resist and Ni-Hard, produce very tough
castings to resist erosion-corrosion in near-neutral and alkaline
solutions or slurries.
(2) Carbon Steel - Carbon steel is alloyed, in various combinations,
with chromium, nickel, copper, molybdenum, phosphorous, and vanadium.
Low-alloy steels (2% total maximum alloying elements or less) are
generally the more corrosion resistant. However, like cast iron, it
is very susceptible to rusting.
Steel products are cast and also readily available in sheet, plate,
and structural forms, as well as in a variety of products. Steels
can be easily field cut and welded.
(3) Stainless Steel - Stainless steel has the same versatility of usage
as carbon steel, with greatly improved corrosion resistance. De-
sired corrosion resistant properties are produced by alloying at
least 11 percent of chromium. The chromium is reactive, but sets up
a passive film to inhibit further corrosion. The following is a
brief description of the five types of corrosion resistant alloys
most commonly used in chemical applications:
5-129
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Type 304 The basic 18% Cr-8% Ni type for relatively mild corrosion
resistance.
Type 316 The "18-8" type with 2.0/3.0% Mo for superior resistance
to pitting and to most types of corrosion, particularly in
reducing and neutral solutions.
Type 317 The "18-8" type with 3.0/4.0% Mo, which has moderately
better resistance than type 316 in some conditions, such
as high concentrations of acetic anhydride and hot acetic
acid.
"20" A 29% Ni-20% Cr steel with copper and molybdenum,
developed specifically for resistance to sulfuric acid.
Ni-o-nel A 42% Ni-21.5% Cr alloy with copper and molybdenum, devel-
oped to meet more severe corrosion and stress-corrosion
conditions than can be handled by the stainless steels but
where nickel-base alloys are not needed.
A popular fallacy is that stainless steels are generally resistant to all
environments. Stainless steels do have widespread application in resisting
corrosion, but also have limitations. In fact, under conditions involving
chloride-bearing solutions and stressed members, stainless steels are subject
to chloride stress corrosion cracking and thus are much less suitable than
alloyed steels. Stainless steels are also more susceptible than regular
steels to localized corrosion such as intergranular, crevice, and pitting
attack.
Consequently, many corrosion failures have resulted from the indiscriminate
use of stainless steels on the assumption that they were the "best." In
practice, stainless steels represent a class of highly corrosion-resisting
materials of moderate strength and cost that are the bulwark of the chemical
process industries when used with discretion.
(4) Aluminum and Alloys - Next to carbon steel and stainless steel,
aluminum represents a versatile metal for construction, available in
cast form and sheet, plate, and structural forms and in a variety of
commercially available process components.
Aluminum is reactive but develops a passive oxide film which pro-
tects it from further corrosion in many environments. This film
remains stable in neutral and many acid solutions, but is attacked
by alkalies. The passive film is produced after contact with the
chemical environment, unless the film has been artificially produced
through anodizing. Structural members are typically produced from
high-copper alloys, whereas process components are usually con-
structed of the low-copper or copper-free alloys, which have better
corrosion resistance.
(5) Magnesium and Alloys - A lightweight material often found on port-
able devices and vehicles, however one of the least corrosion
5-130
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resistant. It must generally be physically separated from other
metals or it will become a sacrificial anode for them. It is cap-
able of forming a good passive film; however, the film breaks down
in salty air conditions, necessitating special coatings or other
surface preparations. Magnesium is susceptible to erosion-corrosion.
It is much more resistant to alkalies than is aluminum. It is
attacked by most acids except chromic and hydrofluoric. The
corrosion product in HF acts as a protective film.
(6) Lead and Alloys - Used often on corrosion resistant applications in
such forms as: sheet linings, solder, cable sheath, bearings, and
piping. Lead forms protective films consisting of corrosion prod-
ucts such as sulfates, oxides, and phosphates. It is subject to
erosion-corrosion because of its softness. Chemical-resistant lead,
containing about 0.06% copper, is resistant to sulfuric, chromic,
hydrofluoric, and phosphoric acids, neutral solutions, and seawater.
It is rapidly attacked by acetic acid and generally not used in
nitric, hydrochloric, and organic acids.
(7) Copper and Alloys - Copper alloys are found in pump bodies and
impellers, process component bodies and parts, and in pipe tubing
and fittings, tanks, bearings, wire and screen.
A good chemically resistant material, copper is not corroded by
acids unless oxygen or other oxidizing agents (e.g., HN03) are
present. Copper-base alloys are resistant to neutral and slightly
alkaline solutions (exception: ammonia). Common alloys are:
brass, bronze, and cupernickel. Bronze, aluminum brass, and cupra-
nickel are stronger and harder than copper and brass and less
subject to erosion-corrosion.
(8) Nickel and Alloys - A workhorse in severe corrosion applications,
nickel and its alloys are found in many commercially available
process components, expecially pumps, valve parts, and other criti-
cal process parts. Nickel is resistant to many corrosives and is a
natural for alkaline solutions, found in many tough applications on
caustics. It shows good resistance to neutral and slightly acid
solutions. It is not resistant to strongly oxidizing solutions,-
e.g., nitric acid, ammonia. Among the common varieties:
Monel - natural for hydrofluoric acid
Chlorlmet 3 and Hastelloy C - two of the most generally
corrosion-resistant materials commercially available
Chlorlmet 2 and Hastelloy B - very good in cases where
oxidizing conditions do not exist
(9) zinc and Alloys - Not a corrosion-resistant metal, chiefly used in
galvanized steel.
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(10) Tin and Tin Plate - Usually found as a coating and used in solder
and babbit bearings, it is corrosion resistant, easily formed and
soldered; and provides a good base for organic coatings. Tin has
good resistance to dilute mineral acids in the absence of air, and
many organic acids, but is corroded by strong organic acids,-
generally not used for handling alkalies.
(11) Titanium and Alloys - A newcomer to corrosion resistant construction,
is available as castings in pumps, valves, and other process com-
ponents. Titanium is a reactive metal which depends on a passive
oxide film for corrosion resistance. Titanium has resistance to
seawater and other chloride salt solution; hypochlorites and wet
chlorine; and nitric acid. Salts such as FeCl3 and CuCl2. which
tend to pit other metals do not corrode titanium. It is not
resistant to relatively pure sulfuric and hydrochloric acids.
5.13.2 Nonmetallics
(1) Natural and Synthetic Rubbers - Rubber is an important process mate-
rial with an extensive range of uses: hoses, tanks, tubing, gas-
kets, pump diaphrams and impellers, sheets, liners, etc. Rubber has
excellent chemical resistance, and has been a standard for handling
of hydrochloric acid containers. Generally, the synthetic rubbers
have better chemical resistance than the natural rubbers. Vulcaniza-
tion, the process of hardening rubber by adding sulfur and heating,
can produce a wide range of hardnesses from soft gaskets to hard
pump impellers. Corrosion resistance generally increases with
hardness.
A wide variety of synthetic rubbers is available, including combina-
tions with plastics. In developing the various products, plasticiz-
er fillers and hardeners are compounded to obtain a large range of
properties, including chemical resistance. Table 5-19 presents a
list of brand names of plastic materials and the corresponding
generic type of plastic.
Table 5-20 shows chemical resistance and other properties of commer-
cially available rubber products. One of the newer elastomers which
should be added to the list is Hypalon, which has excellent resist-
ance to oxidizing environments such as 90% sulfuric acid and 40%
nitric acid at room temperature.
(2) Plastics - Used extensively in chemical process applications as
process component bodies and parts, tanks and tank liners, pipe,
valves, tubing, and fittings, sheets, structurals, etc., plastics
are high-molecular weight organic materials that can be shaped into
a variety of useful forms.
When comparing plastics to metals, the former are softer and weaker,
more resistant to chloride ions and hydrochloric acid, less resist-
ant to concentrated sulfuric ad oxidizing acids such as nitric, less
5-132
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TABLE 5-19. BRAND NAMES OF POLYMERIC MATERIALS
Material Chart classification
Material Chart classification
Aeroflex
Alathon
Araldite
Avisco
Bakelite
Beelte
Dacron
Durcon
Durez
Dypol
Epon
Excon
Kel F
Lauxite
Lucite
Lustrex
Moplen
Polyethylene
Polyethylene
Epoxy
Urea
Phenolic
Urea
Polyester
Epoxy
Phenolic
Polyester
Epoxy
Polypropylene
Fluorocarbon
Urea
Methyl methacrylate
Polys try ene
Polypropylene
Mylar
Nylon
Penton
Plexiglas
Plioflex
Polythene
Pro-Fax
PVC
Resinox
Saran
Styron
Teflon
Tygon
Vibrin
Vinylite
Viton
Polyester
Nylon
Polyether
Methyl methacrylate
Vinyl
Polyethylene
Polypropylene
Polyvinyl chloride
Phenolic
Vinyl
Polystyrene
Fluorocarbon
Vinyl
Polyester
Vinyl
Fluorocarbon
resistant to solvents, and have definitely lower temperature limitations.
Plastics, when subjected to corrosive environments do not fail as
metals do. Rather than dissolving, they are degraded or corroded
because of swelling, loss in mechanical properties, softening,
hardening, spelling, and discoloration. Table 5-21 lists the
properties of some commercially available plastics.
For ease of using this table, commonly used tradenames and other
designations are listed here alphabetically in reference to the
chart classification to which they belong-.
(3) Other Nonmetallics - Used as materials of construction and lining of
process systems:
Ceramics - compounds of metallic and nonmetallic elements; include
magnesia, brick, stone, fused silica, stoneware, glass,
clay tile, procelain, concrete, abrasives, mortar, high
temperature refractories. Most ceramics exhibit good
chemical resistance, with the exception of hydrofluoric
acid and caustic.
Carbon and Graphite - often used for shaft seals,- inert to many
chemical environments; good resistance to alkalies and
most acids; attacked by oxidizing acids such as nitric,
concentrated sulfuric, and chromic,- also attacked by
fluorine, iodine, bromine, chlorine, and chlorine dioxide.
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TABLE 5-20. PROPERTY COMPARISONS - NATURAL AND SYNTHETIC RUBBERS [12]
ui
Property
Hardness range (Shoreb"A")a
Tensile strength, psi
(tax. elongation.
Abrasion resistance
Resistance to compression set
at 15B°F
Resistance to compression set
up to 2.500°F
Aging resistance (normal temp.)
Max. ambient temp, allowable, °F
Resistance to weather and ozone
Resistance to flexing
Resistance to diffusion of gases
Resilience
Resistance to petroleum oils
and greases
Resistance to vegetable oils
Resistance to nonaromatic fuels
and solvents
Resistance to aromatic fuels
and solvents
Resistance to water and
antifreezes
Resistance to dilute acids
Resistance to oxidizing agents
Resistance to alkali
Bielectric strength
Flame resistance
Processing characteristics
Low temperature resistance
Tear resistance
Natural
rubber
40-100
4,500
900
Excellent
Good
Poor
Good
160
Fair
Excellent
Fair
Excellent
Poor
Good
Poor
Poor
Good
Good
Poor
Fair
Excellent
Poor
Excellent
Very good
Excellent
Butyl
(GR-1)
40-90
3,000
900
Good
Fair
Poor
Excellent
275
Very good
Excellent
Excellent
Poor at low
temperature;
Good at high
temperature
Poor
Good
Poor
Poor
Good
Good
Fair
Fair
Good
Poor
Good
Fair
Excellent
Buna S
(GR-S)
40-100
3,500
600
Excellent
Excellent
Excellent
Excellent
275
Fair
Good
Fair
Fair
Poor
Poor
Poor
Good
Good
Poor
Fair
Excellent
Poor
Good
Good
Good
Neoprene
30-90
3.500
1,000
Very good
Good
Fair
Excellent
225
Excellent
Excellent
Very good
Very good
Good
Fair to
good
Fair
Fair
Good
Poor
Good
Fair
Good
Good
Fair
Good
Nitrile
(buna N)
45-100
4,000
700
Excellent
Excellent
Excellent
Excellent
300
Fair
Fair
Fair
Fair
Excellent
Very good
Good
Excellent
Good
Poor
Fair
Fair
Poor
Good
Good
Good
Polyacrylic
rubber
50-90
1,500
200
Fair
Good
Good
Excellent
400
Excellent
Excellent
Poor
Very good
Poor
Fair
Poor
Fair
Silicone
rubber
40-80
900
250
Poor
Excellent
Excellent
Excellent
580
Excellent
Poor
Good
Fair
Poor
Fair
Poor
Excellent
Poor
8100 durometer reading is bone hard and indicates that ebonite or hard rubber can be made.
Indicates soft-rubber type. Hard-rubber types run higher in value.
CThese properties available in specific compounds.
-------
TABLE 5-21. PROPERTIES OF COMMERCIALLY AVAILABLE PLASTICS [12]
Acids
Thermoplastics
Fluorocarbons
Hethyl methacrylate
Nylon
Polyether (chlorinated)
Polyethylene (low density)
Polyethylene (high density)
Polypropylene
en
^ Polystyrene
bi Rigid polyvinyl chloride
Vinyls (chloride)
Thermosetters
Epoxy (cast)
Phenolics
Polyesters
Silicones
Ureas
Inert
R
G
R
R
R
R
R
R
R
R
SA
SA
SA
A
Inert
A-0
A
A-0
A-0
A-0
A-0
A-0
R
R
SA
A
A
SA
A
Alkalies
Inert
R
R
R
R
R
R
R
R
R
R
SA
A
SA
A
Inert
A
R
R
R
R
R
R
R
R
R
A
A
SA
A
Organic
Inert
A
R
G
G
G
R
A
A
A
G
SA
SA
A
A
Water
absorption,
%/24 hr
0.0
0.2
1.5
0.01
0.1S
0.1
<0.01
0.04
0.10
0.45
0.1
0.6
0.2
0.15
0.6
Oxygen
and High Ionizing
ozone vacuum radiation
Inert
R decamp.
SA
R
A F
A F
A F
SA P
R
R P
SA
-
A
R
A
P
P
F
-
F
G
G
G
P
P
G
G
G
F
P
Temperature
resistance
High Low
550
180
300
280
140
160
300
160
150
160
400
400
350
550
170
G-275
~
G-70
G
G-80
G-100
P
P
P
L
L
L
L
L
Note: R = resistant, A = attacked, SA = slight attack, A-0 = attacked by oxidizing acids. G
L = little change.
good, F
-------
Wood - Typical chemically resistant woods are cypress, pine,
oak, and redwood; generally limited to dilute chemicals;
strong acids, oxidizing cards, and dilute alkalies attack
wood.
5.14 MISCELLANEOUS CONCERNS
5.14.1 Personnel Health and Safety
The health and safety of the public and of plant employees should be consid-
ered of major importance in any industrial installation design or operation.
Although the greater part of this manual deals with possible injury to public
health and property, the effect of plant emissions on the plant employees is
also a primary concern. Often, plant employees in direct contact with the
industrial processes for extensive periods of time are in the greatest imme-
diate danger. This section will not attempt to define the multitude of work-
related hazards facing hazardous waste incinerator workers, but will concen-
ntrate on these areas of concern: equipment for worker protection and
procedures for worker protection [39].
. Synthetic Gloves - These provide skin protection for the hand and arm, as
required. Synthetic means rubber, polyethylene, or other impervious
materials. Full-arm-length gauntlets or sleeve protectors can also be
used.
• Synthetic Aprons - Materials specified for synthetic gloves also apply to
aprons. Disposable-type coveralls or laboratory coats may be preferred
for many tasks at an incinerator facility.
. Respiratory Protective Devices - There are three types of these devices:
(1) air-purifying respirators, (2) supplied-air respirators, and (3)
self-contained breathing apparatuses.
The air-purifying respirators utilize an aerosol filter for protection
against particulate matter and/or a chemical cartridge for protection
against certain known gases of vapors. The choice of cartridge is
dictated by the hazard involved.
The supplied-air respirators are supplied with air remote from the hazard-
ous location, usually through a breathing-air manifold and hoses. The
self-contained breathing apparatus is normally used only in emergency
situations. Use only devices that are certified by NIOSH.
- Adequate Ventilation - Ventilation in an area must be sufficient to
prevent harmful exposure to toxic materials. The threshold-limit value
(TLV) for an individual chemical vapor or type of dust refers to the
time-weighed concentration for a normal workday, under which
it is believed that nearly all workers may be repeatedly exposed, day
after day, without harmful effect. If this value is exceeded, then a
"ceiling" value applies. This ceiling value should not be exceeded
(emergency situations such as spills require the use of protective
equipment). Exposure to concentrations above the TLV
5-136
-------
up to the ceiling value are not desirable, but are permitted as long as
the overall eight-hour time-weighted average (TWA) does not exceed the
TLV.
If inadequate ventilation is indicated (TLV is exceeded) for any opera-
tion or area, immediate use of a personal air-supply system is engaged.
A permanent solution involving good engineering practices is then
desirable and should be implemented as soon as possible.
• Full Suit - This is a suit that provides head-to-toe protection for the
hazard involved.
• Line Breaks - Line breaks include broken flanges on lines not previously
exposed to the atmosphere, and drained and repacking of valves and pumps,
where there exists a potential for hazardous streams in concentrated form
or under pressure. In this type of operation, the following protective
equipment is usually required: full-rubber acid-suit consisting of
rubber coat, rubber pants, acid gloves, rubber boots under the pants, and
rubber hood.
• Repairs - Repairs apply to work performed on equipment or lines that
handled hazardous waste streams, which had previously been opened to the
atmosphere, and which have been drained and proven to be under no pressure.
Since the hazardous potential still exists, goggles or an approved hood
and gloves are typically required. After flushing with water—or a
neutralizer agent where feasible—and the danger potential no longer
exists, as determined by supervision, hazardous-material protection is no
longer required. If the underfoot area is still puddled or wet from
flushing and draining, rubber overshoes are usually required.
If a pump is not delivering, and troubleshooting or priming is necessary,
goggles and gloves with coat or apron are worn even though no breaks in
the line have occurred.
5.14.2 Facility Housekeeping
Good housekeeping plays a key role in occupational health protection. Basic-
ally, it is another tool in addition to those other facility safeguards listed
for preventing dispersion of dangerous contaminants. Housekeeping is always
important; where there are toxic materials, it is paramount.
Immediate cleanup of any small spills of toxic material is a very important
control measure. A regular cleanup schedule using vacuum cleaners or lines is
the only truly effective method of removing dust from a work area, an air
hose for blowing away dust is never used.
A high standard of housekeeping is the most important single factor in the
prevention of fire. Many types of waste and rubbish are susceptible to spon-
taneous ignition. Practically all organic materials have a tendency to heat
spontaneously. This tendency is greater for those containing oil, solids when
pulverized, and vegetable or animal fibers, especially when wet. Many materi-
als which are safe at room temperature will heat spontaneously after prolonged
5-137
-------
exposure to high temperatures, such as accumulations occurring in ducts or on
heated pipes.
Accumulations of all types of dust are cleaned at regular intervals from
overhead pipes, beams, and machines, particularly from bearings and other
heated surfaces. It must be understood that all organic as well as many
inorganic materials, if ground finely enough will burn and propagate flame.
Roofs also are kept free from combustible refuse. Such cleaning perferably is
done by vacuum removal, because blowing down with air may disperse dusts into
dangerous clouds.
5.14.3 Maintenance
Testing is a prime activity in a maintenance program, particularly for a
hazardous waste incineration facility. While alarm systems, spill-alert sys-
tems, and fail-safe devices are available, a testing program usually peri-
odically creates situations which require fail-safe devices to demonstrate
their operation. For instance, pressure testing of pipe, valves, and fittings
along with hydrostatic testing of storage tanks will do this. Other tasks
such as visual and electronic inspections will make up the remainder of a
maintenance program and are included on prepared forms. These forms state the
optimum timing for each inspection as well as the required frequency.
Incidences of excess emissions can be reduced by good operation and mainten-
ance (O&M) practices and a comprehensive preventative maintenance program.
With these practices, control equipment can provide maximum benefit.
While maintenance activities are not repetitive in the same manner as operat-
ing tasks, the maintenance function can be formalized. Available to facility
management are maintenance management information systems, inventory and mate-
rials control systems, scheduling algorithms, work standards, indirect work
measurement, and replacement theory.
A mechanism which is becoming more prevalent as equipment and technologies
increase in sophistication is contract maintenance. Air pollution control
equipment lends itself particularly well to this concept and appears attrac-
tive to new facilities which own several pieces of control equipment [40].
From the vendor's perspective, the advantages of providing a maintenance
contract are:
(1) Close surveillance of the system's performance, especially during
the warranty period.
(2) Immediate identification and troubleshooting of malfunctioning
components.
(3) Avoidance of customer complaints.
(4) Operational experience that facilitates product improvement.
(5) Quick handling of emergency situations.
5-138
-------
(6) A well functioning system that is the best recommendation for sales
of additional systems.
From the user's point of view, the benefits of contract maintenance are:
(1) Plant personnel do not have to be thoroughly trained in equipment
maintenance, thus allowing them to devote their time to process
equipment.
(2) Technological troubleshooting and problem diagnosis are not usually
in-house resources.
(3) Plant personnel do not necessarily have the knowledge to improve
equipment performance.
(4) Plant personnel may lack awareness of alternative supplies and
suppliers.
(5) Expenditures for larger crews, repair facilities, tools, and
measurement instruments are reduced.
(6) Previous experience on similar equipment and applications can be
used.
(7) Intrepretations of causes of component failure can be provided.
(8) Contract maintenance programs are more effectively regulated and
administered than are in-house programs.
(9) Dirty and hazardous jobs do not have to be performed by plant
personnel.
(10) Fluctuating workloads due to startup and seasonal variations can
be handled easily.
An in-house regular maintenance/repairs program entails:
(1) Establishing a record system wherein periodic maintenance of each
incinerator component is scheduled for completion by a qualified
person.
(2) Cleaning, lubricating, and adjusting equipment by operating
personnel as part of their daily or weekly task.
(3) Certifying that maintenance has been performed.
(4) Recording major repairs separately and completely.
(5) Thoroughly reporting each inspection, including condition of
furnace, repairs performed, and expectation of future repairs
or major overhaul.
5-139
-------
(6) inspecting components subject to rapid wear or damage weekly, at
a time when such components are not being operated.
5.14.4 Firefighting/Emergency Personnel and Equipment
a ,
forced they have the authority to request the activation of the emergency
program.
A fire emergency plan includes:
(1) An emergency squad composed of personnel from operations, mainten-
ance front office supervision, and guard force-specifically
selected and trained in emergency control techniques and equipment.
(2) Emergency planning taking into account the plant's alarm system,
( communicltions. organization responsibilities e^cua^JJ!n?s~ and
bilites, available emergency equipment, mutual aid arrangements, and
traffic control.
(3) Emergency crews engaged in continual training.
(4) Emergency squad members thoroughly trained in comprehensive
first-aid treatment.
(5) Emergency squad members familiar with firefighting equipment.
The emergency squad composed of personnel from operations, njainten ance front
s rss^ -««-
control organization be activated.
Emergency planning also take into account the plant's alarm system, communica
tions organizational responsibilities, evacuation P0"1^1^1"'^"1^!
emergency equipment (and where it is located), dangers and emergency situ.
tionsEoth inside and outside the plant (such as bomb threats , ~tu.l-.id
arrangements and traffic control. A manual containing the "levant ^forma-
tion is prepared and distributed to those responsible for executing the plan.
This is reviewed at least annually, and updated as needed.
Emergency crews must undergo continual training because
respond to an actual emergency is usually quite limited. t
infrequency of calls to action can. with time, erode the ability of crews t
respond with the speed usually required. Crews are typically PJ™*J f"
shifts, and be trained to handle all types of emergencies: fire, toxic gas
releases, chemical spills, serious injury, and personnel rescue.
5-140
-------
Emergency-squad members are usually thoroughly trained in comprehensive first-
aid treatment, including cardiopulmonary resuscitation, handling of breathing
apparatus, and emergency rescue procedures, and are familiar with station and
ambulance first-aid equipment. In addition, they learn the different types of
fires, extinguishing agents, the proper protective clothing for firefighting,
and become familiar with firefighting equipment, including hoses, nozzles,
portable extinguishers, wheel units, fire trucks, and with the plant's fire-
protection systems. Finally, field training in firefighting with protective
clothing includes experience extinguishing "Christmas-tree," impingement, pan
and spill, and other types of fires.
At a sprinklered property, the most important function of men assigned to the
emergency organization is to assure at all times that the automatic sprinkler
protection will operate as intended. At the start of the fire it must be made
certain that sprinkler valves are open and fire pumps operating as needed,-
during the fire, that valves are not closed too soon; and after the fire, that
opened sprinklers are replaced and protection restored promptly.
An emergency squad is designed to be capable of containing small fires, pre-
venting them from developing into large, uncontrollable ones that can cause
loss of life and property.
5.14.5 Stormwater Diversion
Stormwater drainage and other innocuous discharges are segregated and handled
within the battery limits of the incinerator facility. These streams are
normally collected and directed by pipe, drainage ditches, or area grading
through one outlet from the area to a local feeder ditch. The single outlet
or outfall also contain a spill control structure and gate which can be closed
to contain contaminated drainage that may occur due to leaks or spills in the
facility area. Feeder ditches generally border the plant sites along roadways
and eventually drain outside the plant [41].
Facility process areas are usually paved and curbed or diked to contain leaks,
spills, and washdowns, and these directed to a process sump area. The process
sumps are pumped to the appropriate waste treatment facility.
Outlying facility storage tanks, pumps, and unloading facilities are curbed,
diked, or paved for leak and spill control to prevent contamination of area
drainage. The contained areas are then drained and valved to allow normal
storm water drainage. These valves, which are normally closed, are opened for
storm water drainage. In the event a contamination occurs, it is contained
for subsequent treatment and appropriate disposal.
Other general features relative to plant drainage are:
(1) Valves used for the drainage of diked areas are normally manual,
open-and-close design. The condition of the retained Stormwater is
determined before drainage, especially if such drainage of impounded
waters goes into water courses and not into wastewater treatment
plants.
5-141
-------
(2) All plant drainage systems, if possible, flow into ponds, lagoons,
or catchment basins designed to retain materials less dense than
water. Consideration is also given to possible chemical reactions,
if spilled chemicals are commingled.
(3) If plant drainage is not engineered as above, the final discharge of
allin-plant drainage ditches is equipped with a diversion system
that could, in the event of an uncontrolled spill, be returned to
the plant for treatment, the objective being to work toward a
closed-cycle system.
(4) Where drainage waters are chemically treated in more than one treat-
ment unit, natural hydraulic flow is usually used. If pump transfer
is needed, two pumps are typically provided, and at least one of the
pumps is permanently installed.
5.15 TECHNICAL ASSISTANCE
Other books and manuals which have applicability to overall facility design,
operation, and monitoring for hazardous waste incinerators are:
Peterson, D. The OSHA compliance manual. New York, McGraw-Hill, 1980.
241 p.
Budinski, K. Engineering materials: properties and selection. Engle-
wood Cliffs, NJ; Reston Publishing; 1980. 436 p.
Conway, R. A.,- and Ross, R. D. Handbook of industrial waste disposal.
New York, Van Nostrand Reinhold, 1980. 565 p.
Metry, A. A. The handbook of hazardous waste management. Westport, CT;
Technomic Publishing Co.; 1980. 446 p.
Scott, R. A., ed. Toxic chemical and explosives facilities: safety and
engineering design. Symposium proceedings; 1978 September; Miami Beach.
Washington, American Chemical Society, 1979. 352 p.
5-16 REFERENCES
1 Kovalick, W. W., Jr. State decision-makers guide for hazardous waste
management. Washington, DC; U.S. Environmental Protection Agency; 1977.
103 p. EPA-SW-612.
2. Wallace, M. J. Controlling fugitive emissions. Chemical Engineering.
86(18):78-92, 1979 August.
3 Wirth G. F. Preventing and dealing with in-plant hazardous spills.
Chemical Engineering. 82(17):82-96, 1975 August.
5-142
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4. Development of an emergency response program for transportation of
hazardous waste. Washington/ DC; U.S. Environmental Protection Agency,-
1979 March. 333 p. EPA-SW-171C.
5. Accident prevention manual for industrial operations, seventh edition.
Chicago, National Safety Council, 1974. 1523 p.
6. Handbook of industrial loss prevention, second edition. New York,
McGraw-Hill Book Company, 1967.
7. Houghton, A. J.; Simmons, J. A.; and Gonso, W. E. A fail-safe transfer
line for hazardous fluids. Proceedings of the 1976 national conference
on control of hazardous material spills,- 1976 April 25-28; New Orleans.
Rockville, MD; Information Transfer, Inc.; 29-32.
8. Recommended good practices for bulk liquid loss control at terminals and
depots. Washington, DC; American Petroleum Institute; 1971. API tech-
nical bulletin No. 1623.
9. Recommended practices for bulk loading and unloading of flammable liquid
chemicals to and from tank trucks. Washington, DC; Chemical
Manufacturers Association; 1975. CMA technical bulletin No. TC-8.
10. Loading and unloading flammable chemicals, tank cars. Washington, DC;
Chemical Manufacturers Association; 1975. CMA technical bulletin No.
TC-29.
11. Loading and unloading corrosive liquids, tank cars. Washington, DC,-
Chemical Manufacturers Association; 1975. CMA technical bulletin No.
TC-27.
12. Huibregtse, K. R.,- Sholz, R. C.,- Wullschleger, R. E.; Moser, J. M. ;
Bollinge, E. R.; and Hansen, C. A. Manual for the control of hazardous
material spills. Volume one - spill assessment and water treatment
techniques. Cincinnati, OH; U.S. Environmental Protection Agency,- 1977
November. 490 p. EPA-600/2-77-227.
13. Materials handling. Chemical engineering deskbook. Chemical Engineering.
85(24), 1978 October. 152 p.
14. Perry, R. J.; and Chilton, C. J. Chemical engineers' handbook, fifth
edition. New York. McGraw-Hill Book Company, 1973.
15. Liquids handling. Chemical engineering deskbook. Chemical Engineering.
85(8), 1978 April. 220 p.
16. DeMarco, J.; Keller, D. J.; Leckman, J.; and Newton, J. L.
Municipal-scale incinerator design and operation. U.S. Department of
Health, Education, and Welfare, 1969. Public Health Service Publication
No. 2012. 98 p.
5-143
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17 Bonner. R. F.; and Petura, R. C. Disposing of liquid/fluid industrial
wastes. Pollution Engineering. 11(10)=46-48, 1979 October.
18 Shields, E. F. Prevention and control of chemical spill incidents.
Pollution Engineering. 12(4):52-55, 1980 April.
19 D'Alessandro, P. L.; and Cobb, C. B. Hazardous material control for bulk
storage facilities. Proceedings of the 1976 national conference on
control of hazardous material spills; 1976 April 25-28; New Orleans.
Rockville, MD; Information Transfer, Inc.; 39-43.
20 Danielson, J. A., ed. Air pollution engineering manual, second edition.
Research Triangle Park, NC; U.S. Environmental Protection Agency; 1973
May. 987 p. AP-40.
21. Payne, W. R. Toxicology and process design. Chemical Engineering.
85(10):83-85, 1978 April.
22 Franconeri, P. Selection factors in evaluating large solid waste
shredders. Proceedings of 1976 national waste processing conference;
1976 May 23-26,- Boston. New York, The American Society of Mechanical
Engineers, 233-247.
23 Robinson, W. D. Shredding systems for mixed municipal and industrial
solid wastes. Proceedings of 1976 national waste processing conference;
1976 May 23-26; Boston. New York, The American Society of Mechanical
Engineers, 249-260.
24 Rinker, F. G. Controlled disposal of containerized toxic materials.
1979 national conference on hazardous material risk assessment, disposal
and management; 1979 April 25-27.- Miami Beach. Silver Spring. MD; Infor-
mation Transfer, Inc.; 107-111.
25. Gable, L. W. Installation and calibration of thermocouples. ISA Trans-
actions. 13(1)-.35-39, 1974 January-March.
26. Slomiana, M. Selecting pressure and velocity head primary elements for
flow measurement. Instrumentation Technology. 26(11):40-49, 1979
November.
27. The Mcllvane scrubber manual. Vol. I. Northbrook, IL; The Mcllvane
Company; 1976.
28. Hall, J. A guide to pressure monitoring devices. Instruments and
Control Systems. 51(4):19-26, 1978 April.
29. The fabric filter manual. Vol. 1. Northbrook, IL; The Mcllvane Company;
1976.
30. Smith, W. B.,- Gushing, K. M.; and McCain, J. D. Procedures manual for
electrostatic precipitator evaluation. Research Triangle Park, NC; U.S.
Environmental Protection Agency,- 1977 June. 421 p. EPA-600/7-77-059.
5-144
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31 Continuous air pollution source monitoring systems, U.S. Environmental
Protection Agency handbook. Cincinnati, OH; U.S. Environmental Protec-
tion Agency; 1979 June. 262 p. EPA-625/6-79-005.
32 Block H P Predict problems with acoustic incipient failure detection
systems. Hydrocarbon Processing. 56(10)=191-198, 1977 October.
33 Shih, C. C.; Tobias, R. F.; Clausen, J. F.; and Johnson, R. J. Thermal
degradation of military standard pesticide formulations. Washington, DC;
U.S. Army Medical Research and Development Command; 1975 March. 287 p.
34. The Mcllvane scrubber manual, Vol. II. Northbrook, IL; The Mcllvane
Company; 1976.
35 Paige, S. F.; Babodal, L. B.; Fisher, H. J.; Scheyer, K. H.; Shaug. A.
M.; Tan, R. L.,- and Thome, C. F. Environmental assessment: at-sea and
land-based incineration of organochlorine wastes. Research Triangle
Park, NC; U.S. Environmental Protection Agency; 1978 June. 116 p.
EPA-600/2-78-087.
36 Whitmore, F. C. A study of pesticide disposal in a sewage sludge
incinerator. Washington, DC; U.S. Environmental Protection Agency; 1975.
193 p. EPA-SW-116C.
37 Ferguson, T. L.,- Bergman, F. J.; Cooper, G. R.; Li, R. T.; and Honea, F.
I Determination of incinerator operating conditions necessary for safe
disposal of pesticides. Cincinnati, OH,- U.S. Environmental Protection
Agency; 1975 December. 417 p. EPA-600/2-75-041.
38 Cross, F. L. Control of fugitive dust from bulk loading facilities.
Pollution Engineering. 12(3):52-53, 1980 March.
39 Morton W. I. Safety techniques for workers handling hazardous materials
Chemical Engineering. 83(21):127-132, 1976 October.
40. Rimberg, D. B. Minimizing maintenance makes money. Pollution
Engineering. 12(3):46-48, 1980 March.
41. Elton, R. L. Designing stormwater handling systems. Chemical
Engineering. 86(11):64-68, 1980 May.
5-145
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CHAPTER 6
ESTIMATING INCINERATION COSTS
(This Chapter was Undergoing Revisions at the
Time of Publication of this Document. A Revised
Chapter 6 will be Available Upon request at a
Later Date.)
-------
APPENDIX A
SUBJECT INDEX
-------
APPENDIX A
SUBJECT INDEX
Abrasion. 2.4.1.1
Absorption. 4.3.2
Acoustic analysis. 5.10.2
Activation energy. 4.2.3
Afterburner. 2.4.1. 4.2. 6.3.2.5
Air pollution
emissions (see emissions)
fugitive. 5.1.4.1-2
monitoring. 5.3.2. 5.5-6. 6.2
Air pollution control device
absorption (see absorption)
applicability. 4.3.1
baghouse (see baghouse)
cost. 6 3
cyclone (see cyclone)
design. 4.3 2
electrostatic precipitator
(see electrosatic precipitator)
evaluation. 5.3.1-3, 2.4
scrubber (see scrubber)
Air requirements
excess air. 4.2.3. 4.4
(worksheets. 4-4. 4-7, 4-8)
stoichiometric. 4.2.2, 4.4
(worksheets. 4-1. 4-3)
Ash. 5.11.1.3 5 11 4
Atomization
evaluation. 4.2.2
general. 2.2.1
rotary cup. 4 2.2
single fluid. 4.2.2
sonic, 4.2 2
two fluid, high pressure air. 4.2.2
two fluid, high pressure steam, 4.2.2
Auto ignition temperature. 5 2.2.3. 5.2 2.8
Automatic sprinkler system, 5.5.5.1
Baghouse monitoring. 5 7.2
Bibliography, Appendix D
Bonding. 5.3.3.2
Bottom ash. 5.7.23
Burner
atomization (see atomization)
evaluation. 4.2.2
general design, 4.2.1
placement. 4.2.1
suspension. 4.2.1
Catalytic afterburner (see afterburner). 2.4.1
Chain of custody. 3.3
Co-incineration, 2.2.4.1, 2.2.S
Coding, pipe. 5.5.3 4
Combustor (see afterburner)
Compatibility matrix. S.S.I
Construction materials (see corrosion). 5.13
Container (see storage)
Contract maintenance. 5.14.3
Control system. 5.6
Conversion tables. Appendix C
Conveyors
mechanical. 5.3.5.1
pneumatic. 5.3.5.2
Corrosion. 2.4.2.1. 4.3.6
Cost
air pollution control device. 6.3
capital. 6.2.1
facility modification, 6.4
operating. 6.2.2
trial burn. 6.5
Current practices. 2.2. 2.3
Cyclone costs. 6.3.2.1. 5.7.4
Dichotomous sampler, 5.12.3.4
Differential absorption, 5.9.2.2
Dikes. 5.4.3.1
Dragertubes, 5.12.3.4
Duct design, 4.3.4
Dust tight. 5.5.63
Efficiency
destruction and removal. 4.2.3. 4.3.1-2
removal. 4.3.1-2
Effluent (see water pollution)
Electric heating cable, 5.5.3.4
Electrostatic precipitator
cost. 6.3.2.4
dry. 2.4.6
dwell time. 5.7.3.4
removal efficiency, 5.7.3.2
step-up transformer, 5.7.3.3
two stage, 2.4 6
wet. 2.4.7
Emergency handbook. 5.2.2.3
Emergency squad, 5.14.4
Emission factor. Appendix G
Emissions
air pollution. 4.2.2. 4.3.1, 4.4
(worksheet 4-11)
fugitive. 5.12
Evaluation
air pollution control. 4.3
incinerator, 4.2
safety systems. 4.2.5. 4.3.S
Fan selection. 4.3.4
Feed systems
batch feeding. 2.2.1.2
charging doors. 2.2.5
conveyor. 2.2.1.2
aThe references are to section numbers in the Handbook.
A-l
-------
Feed systems (continued)
gravity feed. 2.2.5.1
piston feed. 2.3.1.1
pressurized tank and pipe. 2.2.2
screw conveyor, 2.2.5.1
vibratory feed. 2.2.5.1
Feeder ditch. 5.14.5
Filters
depth. 5.9.1.1
surface. 5.9.1.1
Flame scanner. 2.3.2.1. 4.2.5
Flyash. 5.11.1.3
Fuel. 4.2.4. 4.4 (worksheet 4-10)
Fugitive emissions
blowdown. 5.11.1-2
control. 5.12.2
monitoring, S.I.2.3
significance, 5.1.2.1
Gauges. 5.5.4.1
Glossary. Appendix B
Grounding, 5.3.3.2
Hand-held FID. 5.12.3.4
Hazard Class (DOT). 3.3.2
Heat capacity. 4.2.3
Heat input capacity. 4.2.3. 4.2.4
Heating value
higher. 4.2.3
lower. 4.2.3
net. 4.2.3. 4.4 (worksheet 4-2)
Housekeeping (facility), 5.1.4.2
Hydralic accumulator. 5.5.5.3
Incinerator
applicability. 2.1. 2.2. 2.3
coincineration. 2.2.5
evaluation, 4.2
facility design. 5.1.2
fluidized bed. 2.2.3
general discussion. 2.1. 5.1
liquid injection. 2.2.2, 4.2
multiple hearth, 2.2.4
operation. 5.2.2
overall layout. 5.1.2
process control. 4.2.5
rotary kiln. 2.2.1. 4.2
site selection. 5.2.1
Inspections (see monitoring)
Interlock (see safety)
Leak detection and repair plan, 5.Z.Z.4
Liquid to gas ratio (see scrubber)
Loss prevention program, 5.2.2.8
Maintenance. 5.14.3
Hist eliminator, 2.4.2, 4.3.3, 5.7.4
Mixing, 4.2.3
Mixing vessel, 5.5.2
Monitoring
air pollution control system, 4.2.5. 5.7
ash, 5.3.3.1. 5.11.2
continuous, 5.9
general. 5.2.2.1
incinerator process, 4.2.5. 5.2.2. 5.6
interface. 5.9.1.1
liquids. 5.7.1.2, 5.8. 5.11.2
oxygen, 5.6.2
pH. 5.7.1.4. 5.8.3
plant condition, 5.10
pressure drop, 5.7.1.5
Monitoring (continued)
slurry, 5.7.1.3. 5.5.2
solid waste, 3.6, 5.11.2
tanks, 5.4.3.2
temperature, 4.2.3, 5.6.1, 5.7.1
waste handling. 5.3.3.1
waste. 5.3.2. 5.5, 5.6.2-3
Hulticlone (see cyclone)
Hurphee vapor phase efficiency. 4.3.2
Neutralization. 5.8.5
Nozzle (see atomization. burner)
Operations manual. 5.2.2.2
Operations plan. 5.2.2.1
Particle.4size. 2.4.11. 4.3.1. 4.3.2, 5.14.5
Penetration. 4.3.2
Pilot scale incinerator, appendix E
Piping, 5.5.3
Plant disaster emergency plan. 5.2.2.5
Polymer tube. 5.12.3.4
POTW disposal restrictions. 5.11.3
Pressure drop
calculation (also see fan selection). 4.4
(worksheet 4-15)
measurement, 5.7.1.5
Process control (see incinerator, safety)
Products of combustion (see waste)
Protection of human health (see safety)
Pump house, 5.3.3.1
Pumps, 5.5.3
Punching, 5.5.6.4
Purpose of handbook, 1.1
Pyrolysis, 2.3.1
Quench, 4.3.3
Quench water, 5.11.1.1
Rabble arms, 2.2.4.1
RCRA regulations, 3.2
Relief valves. 5.3.3
Residence time
delivered by incineration process, z.i
evaluation. 4.2.3
maximum, 4.2.3
requirements. 4.2.3, 4.4
(worksheets 4-5. 4-9)
Resource recovery, 2.3.1, 2.3.4.1
Rotary kiln (see incinerator)
Run off. 5.2.1
Safety
emergency handbook, 5.2.2.3
fire. 5.4.3.1. 5.14
general. 5.14.1
shutdown equipment, 4.2.5, 4.3.5
spills. 5.2.2.5. 5.3.3. 5.4.3
static electricity prevention, 5.3.3.J
storage, 5.2.2.7
training, 5.2.2.7
unloading hazardous liquids, 5.3.3.1
valves, 5.5.4.1
weather extremes, 5.2.2.5
Sampling (see monitoring)
Scrubber
applicability, 2.7, 4.3.1. 4.3.2
cost. 6.3.2.2
flooding velocity, 2.4, 4.3.2
gas atomized spray, 2.4.2, 4.3.1-2
A-2
-------
Scrubber (continued)
ionizing (see electrostatically augmented)
liquid to gas ratio. 4 3.2. 4 4
(worksheet 4-14), 5.7.1.2
monitoring. 4.3.5. 5.7.1
orifice. 2.4.2. 5.11.1.1
packed bed. 2 4.3. 4.3.1-2
plate tower. 2 4.5, 4.3.1-2, 4.4
(worksheet 4-13)
preformed spray. 2.4.4
seive tray, 4.3 1-2
selection (see applicability)
spray tower, 2.4.4
transfer unit. 4.3.2
venturi, 2.4.2. 4.3.1, 4.3.2, 4.4
(worksheet 4-12)
water handling, 5.11
Seals
packed. 5.5.33
mechanical, 5.5.33
Security (of facility), 5.2.2.6
Shipping and receiving, 5.3. 5.3.3-4. 5.4.3.Z
Shredders. 5.5.5.1-2
Site selection. 5.2 1
Sludge. 5 11.3
Spill and runoff containment, 5.3.3.2. 5.4.3.2
Spill handling plan. 5.2.2.5
Spills (see safety)
Stack, bypass. 435
Starved air combustion. 2.2.6, 2.3.1
Static electricity prevention, 5.3.3.3
Steam
injection, 4 2.2
requirements, 4.2.2
tracing. 5.5.3.4
Stock piles. 5.4.1.2
Storage
bulk solids. 5.4.1.2
containers, 5.4 1.3
liquid. 5 4 1.1, 5 4.3 2
safety, 5.4.2-3
tank cars, 5 4 1.4
tank. 2.2 2.1
Storm water diversion. 5 14.5
Tanks (see storage)
Temperature
incinerator. 2.1. 4.2 3
measurement. 5 6.1. 5.7.1
Test burn (see trial burn)
Testing (see monitoring)
Thermal afterburner (see afterburner)
Thermal decomposition unit. 3.7. Appendix E
Training. 5.2.2.7
Transducer. 5 9 23
Transfer lines (fail safe), 5.3.3
Trenching system, 5.3.3.2
Trial burn
cost. 6 5
results. Appendix E
use. 4 2.3
Turbulence (see mixing)
Unloading
bulk solids. 5.3.5
Unloading (continued)
containers, 5.3.4
liquids, 5.3.3
Valves. 5.5 4. 5.11.2, 5.11.4
Velocity, superficial, 4.2.3, 4.3.2, 4 4
(worksheet 4-6)
Vents. 5.4.1.1
Viscosity
absolute, 4.2.2
kinematic, 4.2.2
Visual inspection, 5.12.2
Waste (solid)
blending (see waste preparation)
characterization. 3.4. 3.5. 3.6, 3.8
comparability with incinerator, 3.2.1. 3.4, 4.2.2
composition, 3.4, 4.2.2
monitoring. 5.3.2
physical properties, 3.4. 4.2.2
pit. 5.4.1.2
preparation. 2.2.2.3, 4.2.2. 5.5
products of combustion, 5.1. 4.2.2
receiving. 5.3
sampling, 3.3
segregation. 5.4.2, 5.5.1
shipping and receiving (see shipping and
receiving)
sources. 2.1, 5.1
transport, 5.3
Water pollution
emissions (see emissions)
monitoring, 5.8. 5.11.2
Worksheet
auxiliary fuel capacity requirements. 4.4
(worksheet 4-10)
combustion gas flow and composition, 4.4
(worksheets 4-1. 4-3)
excess air rate at specified afterburner
temperature and overall feed composition, 4.4
(worksheet 4-8)
excess air rate at specified temperature and
feed composition. 4.4 (worksheets 4-4)
gas residence tune. 4.4 (worksheet 4-5)
internal consistency in venturi scrubber for
proposed gas velocity, liquid to gas ratio
and pressure drop. 4.4 (worksheet 4-12)
maximum achievable excess air rate at
specified temperature and feed composition,
4.4 (worksheet 4-7)
maximum liquid to gas ratio for plate tower
scrubber. 4 4 (worksheet 4-14)
net heating value of waste. 4.4 (worksheet 4-2)
particle concentration and emission rate in
liquid injection incinerator. 4.4
(worksheet 4-11)
plate requirement in plate tower scrubber.
4.4 (worksheet 4-13)
pressure drop, 4.4 (worksheet 4-15)
solid waste retention time for rotary kiln
incinerator, 4.4 (worksheet 4-9)
stoichiometric air requirements, 4.4
(worksheets 4-1. 4-3)
superficial gas velocity. 4.4 (worksheet 4-6)
waste characterization evaluation for
incineration, 3.8
A-3
-------
APPENDIX B
GLOSSARY OF TERMS
-------
APPENDIX B
GLOSSARY
This appendix is a glossary of terms used throughout this Handbook.
activation energy: The quantity of heat needed to destabilize molecular bonds
and form reactive intermediates so that the reaction will proceed
afterburner (or combustor): A pollution control device that uses combustion to
reduce the emission levels of organic gaseous and particulate matter.
ambient concentration (ac): The appropriately time-averaged concentration of a
substance at a location to which the general public has access.
analyzer: A device used to monitor emissions, such as: (1) a nondispersive
infrared analyzer (monitors S02, NO , CO, C02, and other gases that absorb
light in the infrared region of the spectrum, including hydrocarbons),
(2) a nondispersive ultraviolet analyzer (monitors gases that absorb light
in the ultraviolet and visible regions of the spectrum), (3) a polarographic
analyzer (monitors S02, N02, CO, 02, and H2S), (4) an electrocatalytic
oxygen analyzer, and (5) a paramagnetic oxygen analyzer.
angle of repose: The angle at which matter will lie or stack in a stationary
configuration.
ANSI: American National Standards Institute.
APCD: Air pollution control device.
ash: The solid residue that remains after a material is incinerated. There
are two types: (1) bottom ash remains in the combustion chamber after
incineration, and (2) fly ash is entrained in exhaust gases leaving the
incinerator.
ash fusion temperature (or melting temperature of ash): The temperature at
which ash has the potential to melt.
ASME: American Society of Mechanical Engineers.
baghouse: An air pollution abatement device used to trap particulates by
filtering gas streams through large fabric bags.
BaP: benzo(a)pyrene.
B-l
-------
beta, attenuation monitor: An instrument that measures the absorption of
p-radiation as it traverses a small area onto which aerosol particles are
collected by means of inertial impaction.
blowdown: The portion of scrubbing fluid that is purged in order to prevent
buildup of dissolved solids.
BOD: Biological oxygen demand.
catalytic combustion: A type of combustion employing a catalyst bed.
coburning: The burning of waste and a fuel.
coincineration: The joint incineration of hazardous waste and refuse and/or
sludge.
combustor (or afterburner): A pollution control device that uses combustion
to reduce the emission levels of organic gaseous and particulate matter.
dedicated incinerator: A privately owned incinerator used to burn only the
owner's wastes.
deflagration: The act of burning down very suddenly.
destruction and removal efficiency (ORE): This term is defined
by the following equation:
W. - W .
DRE = -*S — x 100%
in
where:
DRE = Destruction and removal efficiency
W. = Mass feed rate of principal toxic organic
in component(s) in the waste stream feeding
the incinerator (kg/min)
W = Mass emission rate of principal toxic organic
out component(s) present in exhaust emissions (kg/min).
destruction efficiency (DE): See destruction and removal
efficiency.
dry sorption process: A process that involves contacting the gas stream with
a solid phase that can remove one or more of the gaseous contaminants.
dwell time-. See residence time.
effluent: A discharge of pollutants (either gases, liquids, or solids) into
the environment.
electrostatically augmented scrubbers: Control devices that couple the
mechanisms of electrostatic attraction and inertial separation by
charging particles prior to entry into a wet collector.
B-2
-------
electrostatic precipitator (ESP): An air pollution control device that
removes participate matter by imparting an electrical charge to particles
in a gas stream, causing their collection on an electrode.
excess air: The air flow rate above that required to achieve theoretically
complete combustion.
fabric filter: A device for removing dust and particulate matter from industrial
emissions by filtration through cloth or other porous materials.
flash point: The lowest temperature at which a material will volatilize to yield
sufficient vapor to form a flammable
gaseous mixture with air.
flooding velocity: The gas velocity or narrow range of gas velocities in a
packed bed or plate tower scrubber at which (for a given packing or plate
design and liquid flow rate) the liquid flow down the column is impeded,
and a liquid layer is formed at the tip of the column. Eventually, liquid
is blown out the top of the column.
fluid: Any substance (for example, a liquid or slurry) that tends to flow or
conform to the outline of its container.
fluidized bed incinerator-. An incinerator consisting of a refractory-lined
vessel containing inert granular material through which gases are blown
at a rate sufficiently high to qause the bed to expand and act as a
theoretical fluid. The gases are injected through nozzles that permit
upward flow the bed but restrict downward flow of the material.
fugitive emissions: Pollutants arising from sources other than stacks and
effluent pipes.
GC: Gas chromatograph
general purpose incinerator: An incinerator that burns miscellaneous types of
wastes, usually from numerous sources and customers.
HCB: Hexachlorobenzene
heating value: The quantity of heat released when waste is burned, commonly
expressed as Btu/lb. The higher heating value includes the heat of
condensation of the water present in the waste and the heat formed in the
combustion reaction; the lower heating value represents the heat formed
in the combustion reaction,- and the net heating value is the lower heating
value minus the energy necessary to vaporize any moisture present.
heat of combustion: The heat evolved from the union of combustible elements
with oxygen.
hygroscopicity: Act of attracting moisture from the air.
B-3
-------
incinerator: An engineered apparatus used to burn waste substances in which all
the combustion factors (temperature, retention time, turbulence, and
combustion air) can be controlled.
incinerator, similar: Incinerator A is similar to incinerator B if, based on
the best engineering judgement, while incinerating identical waste as
incinerator B. the stream leaving the combustion chamber of incinerator A
contains equal or lower amounts of each, but no additional, potentially
hazardous components as the stream leaving the combustion chamber
of incinerator B.
kinematic viscosity: The ratio of absolute viscosity to density.
liquid injection incinerator: An incinerator that uses an atomization device
or nozzle to feed liquid waste.
mass spectrometer: An instrument that analyzes samples by sorting molecular
or atomic ions according to their masses and electrical charges.
MEG: See multimedia environmental goals.
microwave plasma destruction (or plasma destruction) : A method of destruction
that uses microwave energy to excite the molecules of a carrier gas (such
as helium or air), thus raising electron energy levels and forming highly
reactive free radicals.
mist eliminator: A control device used to reduce emissions of liquid droplets,
usually from scrubbers. There are three types: (1) cyclone mist
eliminators (used to collect heavy liquid loadings), (2) fiber bed mist
eliminators (used for collecting fine acid mists), and (3) wire mesh
eliminators (used to collect other mists).
molten salt incinerator: An incinerator in which waste is injected below the
surface of a molten salt bath.
multimedia environmental goals (MEG's): The levels of contaminants (in
air water, or land, or in emissions or effluents conveyed to ambient media)
that (1) will not produce negative effects in the surrounding populations
or ecosystems, or (2) represent control limits demonstrated to be achievable
through technology.
multiple chamber incinerator: An incinerator in which wastes are thermally
decomposed in the presence of oxygen in the primary chamber, and decompo-
sition products are oxidized in the secondary chamber(s).
multiple hearth incinerator-. An incinerator containing multiple refractory-
lined hearths, vertically aligned, designed for staged drying and com-
bustion of wastes.
NFPA: National Fire Protection Association.
B-4
-------
nitrogen oxides (NO)= The collective term used for the gaseous oxides of
nitrogen, primarily nitric oxide (NO) and nitrogen dioxide (N02).
NPDES: National pollutant discharge elimination system.
packed tower- An air pollution control device in which polluted air is forced
upward through a lower packed with materials (such as raschig rings ceramic
saddles, tiles, marbles, crushed rock, or wood chips) while a liquid is
sprayed downward on the packing material. The pollutants in the air
stream either dissolve or chemically react with the liquid.
PAH: Polycyclic aromatic hydrocarbons
particulates: Minute solid or liquid particles in the air or in an emission.
Particulates include dust, smoke, fumes, mist, spray and fog.
PCB: Polychlorinated biphenyls.
piezoelectric monitor: A type of particle monitor which measures mass
concentration by utilization of a vibrating piezoelectric crystal driven
by a standard oscillation circuit.
PNA: Polynuclear aromatic compounds.
POM: Polycyclic organic matter.
pyrolysis: The thermal decomposition of a compound in the absence of oxygen.
pyrophoric: Capable of igniting spontaneously.
quench: To cool rapidly.
removal efficiency: The ratio of the mass rate of flow of the contaminants
going into a control device minus the mass rate of the contaminants going
out of the control device to the mass rate of flow of the contaminants
going into the control device.
residence time: The period of time that the waste is exposed to the reported
temperature in the incinerator.
retention time: See residence time.
rotary kiln incinerator: An incinerator with a cylindrical, horizontal refrac-
tory-lined shell that is mounted at a slight incline. Rotation of the
shell causes mixing of the waste with the combustion air.
scrubber: An air pollution control device that uses a liquid to remove
pollutants from a gas stream by absorption or chemical reaction.
(Scrubbers also reduce the temperature of the emission.)
B-5
-------
similar waste: Waste A is similar to waste B if, based on best engineering
judgement, the incineration of waste A in the same facility and under the
same operating conditions as those used for waste B would yield a stream
leaving the combustion chamber that contains equal or lower amounts of each,
(but no additional) potentially hazardous pollutants compared to the
amounts yielded by waste B incineration.
sludge: A nonpumpable mixture of solids and liquids.
slurry: A pumpable mixture of solids and liquids.
solifluction: Liquid seepage.
SSU (standard saybolt universal): A unit for measuring kinematic viscosity.
starved air combustion (or thermal gasification) : A process that utilizes
equipment and process flows similar to those for incineration; but in
this process, uses less than the theoretical amount of air for complete
combustion is supplied.
TCDD : Te trachlorodibenzo-p-dioxin .
TDAS: Thermal decomposition analytical system.
TDD: Thermal decomposition device
TDI : Toluene diisocyanate .
temperature: A measure of the level of thermal energy in molecules to which
a waste is exposed during the incineration process.
TLV (threshold limit value): Exposure levels representing ""f^^^f"
which it is believed that nearly all workers may be repeatedly exposed
day after day without adverse effects. For airborne substances, the
exposure levels are stated as airborne concentrations and durations of
exposure, including:
• Time-weighted average concentrations for a normal 8-hour
workday or 40-hour workweek (threshold limit value - time-weighted
concentrations to which workers can be exposed for a period
up to 15 minutes (threshold limit value - short-term exposure
• Concentrations that should not be exceeded even instantaneously
(threshold limit value - ceiling).
These values are published annually by the American Conference of
Governmental Industrial Hygienists.
TOD: Total oxygen demand.
B-6
-------
trial burn: Any attempt to incinerate the waste in question for a limited
period A trial burn is designated to establish the conditions at which
incineration of waste in a given facility must be carried out to assure
protection to public health and environment.
trial burn proposal: A detailed plan which describes the procedure that will
be used and the precautions that will be taken during a trial burn.
turndown ratio: Maximum to minimum operating range of a parameter.
UDRI: University of Dayton Research Institute.
viscosity: The property of a fluid or semifluid that enables it to develop and
maintain an amount of shearing stress (dependent upon the velocity of flow)
and then to offer continued resistance to flow.
volatile organic compounds: Organic compounds that are readily vaporized at a
relatively low temperature.
WG: Water gage.
wet air oxidation: A process that operates on the principle that the rate of
oxidation of organic compounds is increased at high pressures. By pres-
surizing an aqueous organic waste, heating it to an appropriate temperature,
and then introducing atmospheric oxygen, liquid-phase oxidation reaction is
produced, destroying most of the organics.
wet electrostatic precipitator (WEP): An electrostatic precipitator which
achieves particle collection by the introduction of liquid droplets to the
gas stream through sprayers located above the electrostatic field section
of the precipitator.
wet scrubber: An air pollution control device used to remove pollution by
bringing a polluted gas stream into contact with a liquid.
B-7
-------
APPENDIX C
CONVERSION FACTORS
-------
Te convert from
Btu (British thermal unit)
Btu/minute (Btu/min)
Btu/pound (Btu/lb)
Btu/(pound-°F)[Btu/(lb-oF))
Btu/second (Btu/s)
calorie (cal)
calorie/gran (cal/g)
calorie/hour (cal/h)
centigrade (°C)
centimeter (on)
centipoise (cP)
centistokes (cSt)
cubic centineter (cm3)
cubic foot (ft3)
cubic meter (m3)
dyne/square centineter
(dyne/cm2)
Fahrenheit (°F)
foot (ft)
TABLE C-l. CONVERSION FACTORS
To
square kilometer (tan2)
square meter (m2)
square mile (mi2)
calorie (cal)
joule (J)
kilocalorie (kcal)
joule/second (J/s)
calorie/gram (cal/g)
calorie/(gram ••<:) [cal/(g-°O]
Kilocalorie/hour (kcal/h)
kilocalorie/minute
Btu
kilocalorie (kcal)
joule (J)
Btu/pound (Btu/lb)
Btu/hour (Btu/h)
erg/second (erg/s)
Fahrenheit (BF)
Kelvin (°K)
inch (in.)
gram/(centimeter-second) (g/(cm-s)]
saybolt seconds (SSU)
cubic foot (ft3)
cubic inch (in.3)
cubic yard (yd3)
cubic centimeter (cm3)
cubic meter (m3)
gallon (U.S. liquid)
liter (L)
cubic foot (ft3)
cubic yard (yd3)
liter (L)
atmosphere (atm)
bar
centimeter of mercury 9 0°C (cm Hg 9 0°C)
centimeter of water 9 4°C (cm H20 @ 4°C)
inch of mercury 8 32°F (in. Hg 9 32°F)
inch of water @ 4°C (in. H20 @ 4°C)
pascal (Pa)
pound/square inch (lb/in.2)
Centigrade (°C)
Rankin (°R)
centimeter (CD)
inch (in.)
meter (m)
millimeter (mm)
Multiply by
0.00404047
4.046.86
0 0015625
251.99576
1,054.35
0.251996
17.5725
0.555555
1.0
970.185
15.1197
0.0039683207
0.001
4.184
l.B
0.0039683207
11.622.222
°F = (1.8 x 8C) +32
°K = °C + 273.17
0.39370079
0.01
See Table C-2
3.5314667 x 10~s
0.061023744
1.3079506 x 10"6
28.316.847
0.028316847
7 4805195
28.316847
35.314667
1.3079506
1.000
9.86923 x 10~7
1 x 10 6
7.50062 x 10~s
0.00109745
2.95300 x 10-5
0.000401474
0.1
1.450377 x 10~5
°C = 0.5556 (°F - 32")
°R = °F + 459 7°
30.48
12
0.3048
304.8
(continued)
C-l
-------
TABLE C-l (continued)
To convert from
To
Multiply by
gallon (U K liquid)
(gal)
gallon (U.S liquid) [gal]
grains/standard cubic foot
(gr/scf)
gram (g)
gram/(centimeter•second)
gran/cubic centimeter (g/cm3)
gran/cubic meter (g/m3)
gram/liter (g/L)
gran/milliliter (g/nL)
inch of water 9 4°C
(in. H20 0 4°C)
joule (J)
joule/second (J/s)
kilocalorie (kcal)
kilogram (kg)
liter (L)
meter (m)
pascal (Pa)
gallon (U S liquid) [gal]
liter (L)
cubic centimeter (en3)
cubic foot (ft3)
cubic inch (in.3)
cubic meter (m3)
liter (L)
milligrams/standard cubic meter
kilogram (kg)
pound (Ib)
poise
-------
TABLE C-l (continued)
To convert from
pascal-seconds (Pa-s)
poise (P)
pound (It)
pound/(foot•second)
(lb/(ffs)]
pound/cubic foot (lb/ft3)
pound/cubic inch (Ib/in 3)
pound/gallon (U.K. liquid)
[Ib/gal]
pound/gallon (U.S liquid)
[Ib/gal]
pound/square inch (psi)
saybolt seconds (SSU)
square foot (ft2)
square kilometer ikm2)
square meter (m2)
stoke (St)
ton (metric)
To
Multiply by
Poise
centipose (cP)
dyne-second/square centimeter
gran/(centineter-second) (g/(oa-s)]
pound/(second-foot) [lb/s-ftj
gran (g)
poise (P)
gram/cubic centimeter (g/cm3)
kilogram/cubic meter (kg/m3)
gran/cubic centimeter (g/cn3)
gran/liter (g/L)
kilogram/cubic meter (kg/m3)
pound/cubic foot (lb/ft3)
gram/cubic centimeter (g/cm3)
pound/cubic foot (lb/ft3)
atmosphere (atm)
centistokes (cSt)
acre
square centimeter (cm2)
square inch (in.2)
square meter (m2)
•ere
square meter (m2)
square mile (mi2)
acre
square foot (ft2)
square kilometer (km2)
centistoke (cSt)
saybolt seconds (SSU)
square centimeter/second (cm2/s)
square foot/hour (ft2/h)
square foot/second (ft2/s)
kilogram (kg)
ton (short, 2,000 Ib mass)
10.00
100.00
1
1
0.0672
953.59237
14.88
0.016018463
16.018463
27.679905
27.68068
27,679.905
6.228839
0.11982643
7.4805195
0.0680460
see Table C-2
2.295684 I 10 s
929.0304
144
0.09290304
247.10538
1.000.000
0.38610216
0.00024710538
10.763910
0 000001
1 x 102
See Table C-2
1
3.875
0 001076
1000.
1.1023113
C-3
-------
TABLE C-2. KINEMATIC VISCOSITY CONVERSION FACTORS
FOR CENTISTOKES TO SSU UNITS
Saybolt seconds at
(SSU)
Saybolt seconds at
(SSU)
Centi-
stokes
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
11.0
12.0
14.0
16.0
18.0
20.0
22.0
24.0
26.0
100°F
32.6
36.0
39.1
42.3
45.5
48.7
52.0
55.4
58.8
62.3
65.9
73.4
81.1
89.2
97.5
106.0
114.6
123.3
130°F
32.7
36.1
39.2
42.4
45.6
48.8
52.1
55.5
58.9
62.4
66.0
73.5
81.3
89.4
97.7
106.2
114.8
123.5
210°F
32.8
36.3
30.4
42.6
45.8
49.0
52.4
55.8
59.2
62.7
66.4
73.9
81.7
89.8
98.2
106.7
115.4
124.2
Centi-
stokes
28.0
30.0
32.0
34.0
36.0
38.0
40.0
42.0
44.0
46.0
48.0
50.0
60.0
70.0
80.0
90.0
100.0
100°F
132.1
140.9
149.7
158.7
167.7
176.7
185.7
194.7
203.8
213.0
222.2
231.4
277.4
323.4
369.6
415.8
462.0
130°F
132.4
141.2
150.0
159.0
168.0
177.0
186.0
195.1
204.2
213.4
222.6
231.8
277.9
324.0
370.3
416.6
462.9
210°F
133.0
141.9
150.8
159.8
168.9
177.9
187.0
196.1
205.2
214.5
223.8
233.0
279.3
325.7
372.2
418.7
465.2
aFor kinematic viscosity levels above 100 centistokes, use the
same ratio as the ratio in the table above for 100 centistokes
(at the temperature of the fluid); e.g.
(@ 130°F) = 120 x 4.629 = 555.5.
120 centistokes
To obtain the saybolt universal viscosity at a temperature not
shown in te table above, multiply the saybolt universal viscosity
@ 100°F by [1 + (t - 100) 0.000064], where "t" is the temperature
in degrees farhenheit, e.g., 10 centistokes @ 220°F = 58.8 x
[1 + (220-100) 0.000064]; = 58.8 X 1.00768 = 59.25
C-4
-------
APPENDIX D
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-------
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D-9
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APPENDIX E
LABORATORY-SCALE THERMAL DECOMPOSITION ANALYTICAL DATA
-------
CONTENTS
1. Introduction E-l
2. Thermal Decomposition Analytical System (TDAS) E-l
2.1 General Description E-l
2.2 Operation E-l
3. Thermal Decomposition Device (TDD) E-4
3.1 General Description E-4
3.2 Operation E-6
4. Differences Between TDAS and TDD E-6
5. Differences Between Incinerators and Laboratory Devices E-6
6. Comparison of Kepone Decomposition in the TDD to
Decomposition in a Pilot-Scale Incinerator E-9
7. Possible Applications of Laboratory Experiments E-9
8. Results of Laboratory Scale Decomposition Experiments E-12
8.1 Kepone Results E-12
8.2 Methods of Data Analysis E-12
9. References E-iS
-------
APPENDIX E
LABORATORY-SCALE THERMAL DECOMPOSITION ANALYTICAL DATA
1. INTRODUCTION
Laboratory-scale thermal decomposition data for hazardous wastes may be help-
ful in screening incinerator permit conditions, in establishing sampling and
analytical protocols for incinerator performance monitoring, and in determining
potential operating conditions for incinerator trial burns. Such data may be
developed using laboratory-scale thermal decomposition systems such as the
Thermal Decomposition Analytical System (TDAS) employed at the U.S Environmental
Protection Agency research program at the University of Dayton Research
Institute (UDRI). The EPA intends to develop these data for a broad range of
hazardous wastes and substances over the next 3 years. The objective of this
appendix is to describe how the data are collected, to provide guidance on
their use, and to provide a repository for data as these are generated
during this period.
2. THERMAL DECOMPOSITION ANALYTICAL SYSTEM (TDAS)
2.1 General Description
This system is designed to evaluate the thermochemical behavior of volatile
materials under controlled conditions. As indicated in Figure E-l, it consists
of a modular control panel (where the operating parameters for tests are
established), several gas cylinders (that supply reaction atmospheres with
known compositions), a sample insertion and vaporization chamber, a special
quartz tube reactor in a furnace (for the decomposition of samples), a product
collection trap, a gas chromatograph, a mass spectrometer, and a minicomputer.
Figure E-2 is a block diagram showing a simplified representation of the
operational relationships of the various components.
2.2 Operation
In operation, several micrograms of a solid sample (or several raicroliters of
a liquid or gaseous sample) are introduced into a sample insertion chamber
(location K in Figure E-l). The chamber is then sealed and flushed with the
controlled atmosphere to be used for the experiment. Solid and liquid samples
are heated, vaporized at temperatures up to 300°C (over a controlled time
interval), and mixed with a continuous stream of the reaction atmosphere.
Samples may be flash pyrolyzed or gradually vaporized, depending on the desired
reaction conditions. The mixture then passes through a reactor (location M)
consisting of an 98-cm long, 0.097-mm inside diameter, thin walled, helical
E-l
-------
IN-LINE
GC/MS/DS
(-160°C)
A HELIUM GAS
B COMPRESSED AIR
C INERTCARRIETR
D PRESSURE REGUALTOR
E OXYGEN SCRUBBER
F DIRECTIONAL VALVE
G FILTER
H FLOW CONTROL VALVE
I FLOW TRANSDUCER
J PRESSURE TRANSDUCER
K INSERTION CHAMBER
L TEMPERATURE PROGRAMMER
M REACTOR IN FURNACE
N PRODUCT COLLECTION TRAP
0 MODULAR CONTROL PANEL
3THE MODULAR CONTROL PANEL DID NOT APPEAR IN THE
ORIGINAL PUBLICATION
Figure E-l. Simplified schematic of TDAS [1]
E-2
-------
w
w
CAPTURE OF
EFFLUENT
PRODUCTS
HIGH TEMPERATURE
TRANSFER
CONTROLLED
HIGH TEMPERATURE
EXPOSURE
SAMPLE INSERTION
AND
VAPORIZATION
COMPRESSED GAS
AND PURIFICATION
PRESSURE AND
HOW REGULATION
IN LINE
GAS CHROMATOGRAPH
(HIGH RESOLUTION)
COUPLED
MASS SPECTROMETER
(MAGNETIC)
COMPUTER SYSTEM
NIH/EPA
CHEMICAL INFORMATION
SYSTEM
ANALYSIS OF EFFLUENT PRODUCTS
Figure E-2. Block diagram of TDAS [1]
-------
quartz tube enclosed in an electric furnace. The furnace and tube can be
operated at temperatures up to 1,150°C (±2°). The temperature of the reactor
is monitored by a thermocouple located at a point representing the mean tempera-
ture for the reactor furnace [1].
It is estimated that a typical reaction mixture entering the TDAS reactor
heats to the reactor temperature within 0.005 seconds. Ninety five percent of
the molecules are estimated to be exposed to the reported temperature over time
intervals with a maximum deviation of 4% to 10% from the reported mean residence
time, depending on the conditions of the test (personal communication with Don
Duvall, August, 1980). The percent deviation increases as the mean residence
tine decreases. The temperature is controlled to within ±2°C across the
operating range of the device. Mean residence times between 0.25 and 5.0
seconds may be selected [1]. It is possible to operate the reactor at
pressures up to two atmospheres.
The effluent from the TDAS reactor enters a sorbent trap (Location N) that can
be maintained at -110°C. In the trap, reactions are quenched and reaction
products and unreacted sample are collected with a sorbent (usually Tenax,
although other materials, such as quartz wool, have also been used). The
chemicals collected are then thermally desorbed directly into a capillary
column gas chromatograph/mass spectrometer for identification and quantifi-
cation of reaction products and unreacted sample.
The chromatograph has been used with glass and fused silica capillaries coated
with selected materials (such as a 0.1-um layer of Supelco SP 2100) [4]. The
mass spectrometer contains a total ion detector upstream of the magnetic sector.
This detector may be calibrated and used to measure quantities of pure sub-
stances leaving the gas chromatograph at different times. A photomultiplier
tube downstream of the magnetic sector of the mass spectrometer responds to
the ionic fragments of molecules emerging from the magnetic field. The
identity of chemicals and mixtures of chemicals emerging from the gas
chromatograph can be determined by comparing observed ion fragment patterns
with those of known compounds. The NIH/EPA Chemical Information Mass Spectral
Data Base is routinely used to help identify compounds and mixtures. Software
is being installed to make it possible to measure the amounts of individual
chemicals in mixtures entering the mass spectrometer from ion fragment data.
Samples of effluent from the reactor may be collected on activated carbon (or
other sorbents) simultaneously with the samples collected in the cold sorbent
trap described above. These samples could be desorbed with solvents and
injected into laboratory gas chromatographs or other analytical devices not
directly connected to the TDAS.
3. THERMAL DECOMPOSITION DEVICE (TDD)
3.1. General Description
Figure E-3 is a schematic diagram of the thermal decomposition device (TDD).
It consists of a compressed air cylinder (to supply the reaction atmosphere),
pressure regulators, flow regulators (to adjust the residence time), a sample
insertion and vaporization chamber, a quartz reactor in an electrically heated
E-4
-------
DLJJ-
cV
y
t
1
,
=w*
=d H
7— I,
I
,J
HIGH TEMPERATURE REGION
VENT
A COMPRESSED AIR, BREATHING QUALITY GRADE
B TWO STAGE PRESSURE REGULATOR
C "HYDROPURGE" FILTER
D FLOW CONTROL VALVE
E PRESSURE TRANSDUCER
F SAMPLE HOLDER, PYREX
G HEATED INLET CHAMBER
H QUARTZ TUBE
I HEATED OUTELET CHAMBER
J EFFLUENT TRAP, TENAX-GC OR CHARCOAL
K FLOW METER
Figure E-3. Schematic of thermal decomposition device [3].
E-5
-------
furnace (for the decomposition of samples), a product collection trap, and a
flow meter. This device is the predecessor to the IDAS, and is no longer in use.
3.2 Operation
The TDD was operated in the following manner. Compressed air was filtered
(see location C in Figure E-3) and its flow rate adjusted (location D) to
provide the desired residence time. The gas entered the inlet chamber (location
G) which surrounds a sample holder containing several micrograms of sample
(location F). The chamber was gradually heated to a maximum temperature of
about 300°C to vaporize the sample [3]. As material from the sample vaporized,
it was swept into the reactor chamber (location H) by the compressed air flow.
In the reactor chamber, the reaction mixture was thermally stressed at a con-
trolled temperature (up to 1,000°C). An 84-cm by 0.8-mm ID quartz reaction
chamber and an 84-cm by 2.14-mm ID quartz reaction chamber were available.
The average temperature of the reactor furnace was controlled to ±5°C; but
there were temperature gradients in the furnace of ±25°C, compared to the
reported average temperature (personal communication with Wayne Rubey,
University of Dayton Research Institute, Dayton, Ohio, 8 August 1980). In
most experiments, the residence times in the reactor were approximately one
second (±0.04 s); but residence times between 0.5 s and 3.0 s were possible [3].
After the mixture passed through the reactor, it was cooled to approximately
300°C [3]. The partially cooled mixture then entered the effluent trap
(location J), where it rapidly cooled to ambient temperatures. The effluent
trap and sorbent (Tenax GC or charcoal) collected unreacted sample and the
products of decomposition of the waste. The sorbents used were generally
suitable for materials with molecular weights at or above 78 at room tempera-
ture (personal communication with Wayne Rubey, 8 August 1980).
At the end of a run, the effluent trap was removed from the TDD. If Tenax
was the sorbent, the trap was inserted directly into an adapter on a separate
laboratory gas chromatograph (GC). The trap was then heated to desorb the
products, which were flushed into the GC by a carrier gas. If activated carbon
was used as the sorbent, the products had to be desorbed with a suitable solvent.
A sample of the solvent/product mix was then injected directly into the GC
for analysis.
4. DIFFERENCES BETWEEN THE TDAS AND TDD
Both of these devices were designed for the purpose of studying the thermal
chemical decomposition of various materials, and their basic designs and
methods of operation are quite similar. However, there are differences in
several important specifications (see Table E-l).
5. DIFFERENCES BETWEEN INCINERATORS AND LABORATORY DEVICES
While the results obtained with the previously described laboratory devices
may resemble the performance of an incinerator that vaporizes materials before
introducing them into a well mixed combustion zone with high levels of excess
oxygen, highly controlled retention times, and highly controlled uniform
temperatures, there are differences. Detailed quantitative comparisons have
not been reported.
E-6
-------
TABLE E-l. DIFFERENCES BETWEEN THE TDD AND TDAS
Parameter
TDD [3]
TDAS [1]
Sample type
Reactor construction
Regulation of mean
reactor temperature
Maximum operating
temperatures
Range of tempera-
tures in reactor
Residence time range
Effluent traps
Sampling and
analysis
Liquid or soluble solids,
low volatility only
Heavy-wall folded quartz
840-cm X 0.8-mm ID
(an 84.0-cm X 2.14-mm
tube was also available)
±5°C
l,000°Ca
±25°CC
0.5 - 3.0 sc
Ambient temperature trap
Sample must be manually
removed from unit for
analysis on a nearby GC
Gas, liquid or solid
samples
(MW< -x.800)
Thin-wall helical quartz
(98 on X 0.97 mm ID)
±2°C
±2°C
0.25 - 5.0 s
Cryogenically cooled trap
Sample normally thermally
desorbed in-situ and
carried directly to
GC/MS by the carrier
gas.
aLimited by the heating unit.
Limited by the properties of quartz.
cPersonal communication with Wayne Rubey, 8 August 1980.
E-7
-------
The operating conditions in most incinerators are not as simple as those in
the laboratory devices. Among the potential complications associated with
real incinerators (compared to the TDAS and TDD systems) are the following:
• Wastes may enter the combustion chamber of an incinerator as liquids or
solids, while only gases enter the reaction zones in the TDAS and TDD.
• Direct combustion of fuel and/or waste supplies the heat required for the
reactions in incinerators, and the waste in an incinerator may pass
directly through a distinct flame or flame front. The TDAS and TDD are
indirectly heated.
• There may be a significant lack of homogeneity in the temperature profiles
of incinerators, and the temperature may not be as closely controlled as
in the laboratory devices. Furthermore, the maximum temperature in an
incinerator may be higher than the highest temperature at which labora-
tory devices can be operated.
• The residence times reported for incinerators may not really represent
the exposure times of wastes at the reported operating temperatures. An
upper bound residence time is the only valve reported for some incinera-
tors. This represents the total volume of the incinerator combustion
chamber (whether or not it is all at the reported temperature) divided by
the volume rate of flow of flue gas out of the chamber. The mean resi-
dence times in the laboratory devices are well controlled and represent
true residence tines at the reported temperatures with a degree of accu-
racy seldom achieved for incinerators.
• Physical and chemical interactions between components of mixtures of
wastes and reaction products (such as adsorption on particulates and
catalysis) might inhibit or accelerate the rate of waste decomposition
and combustion product formation. Furthermore, interaction of the com-
bustion products with the walls of the incinerator might affect the
degree of combustion and the products. Some of these effects cannot be
studied in the TDAS and TDD laboratory units, since solids and liquids
cannot enter the reaction chambers of those devices.
• Mixing in an incinerator will be different from mixing in laboratory
devices, resulting in changes in the relative proportions of uncombusted,
partially combusted, and completely combusted waste.
• In an incinerator, the conditions to which various molecules are exposed
can vary greatly in terms of temperature, oxygen concentration, and con-
centrations of free radicals. These variables can be too complicated
to simulate in the laboratory units.
• The laboratory devices were usually operated in such a manner that the
amounts of oxygen leaving the reactors were not significantly different
from the amounts going into the reactors. Furthermore, many experiments
were performed with 21% oxygen. Incinerator flue gas often contains much
less oxygen.
E-8
-------
• The feed rate of incinerators may be constant, allowing steady state
conditions to occur. The laboratory devices are batch fed.
6. COMPARISON OF KEPONE DECOMPOSITION IN THE TDD TO DECOMPOSITION IN A
PILOT-SCALE INCINERATOR
In a series of pilot-scale test burns of Kepone, an afterburner was reported to
have a Kepone destruction and removal efficiency of 99.98% at 1,093°C to
1,260°C and residence times between 2.15 and 2.44 seconds. There was 3.0% to
4.8% excess oxygen in the flue gas [5]. A 99.999655% destruction and removal
efficiency was calculated for the thermal decomposition device at 900°C, a
residence time of about 1 second, and 21% oxygen. According to these calcula-
tions, the pilot incinerator emitted 58 times as much Kepone per gram burned
as the laboratory device, even when operated at a higher temperature and
residence time than the laboratory device (but with less excess oxygen). This
illustrates the uncertainty that can occur when comparing laboratory device
results to pilot burn results.
No data were reported on emissions of products of pyrolysis and incomplete
combustion in the pilot-scale test burn. As a result, the utility of TDD data
for identifying significant byproducts of Kepone incineration could not be
verified.
7. POSSIBLE APPLICATIONS OF LABORATORY EXPERIMENTS
No systematic studies of the performance of the TDAS or TDD compared to
incinerators of different sizes, designs, and operating conditions have been
reported. Furthermore, no systematic studies of the quantitative limitations
of scaleup factors are available. As a result, great caution must be
exercised when using data from the laboratory device, since the applicability
of the data has not been demonstrated. However, some potential uses for
laboratory experiments exist:
• The TDAS and TDD devices have been used to aid in identifying byproducts
of decomposition of hazardous materials and the conditions under which
they are formed.
• It may be possible for experienced combustion chemists to obtain some
evidence that will aid in understanding the detailed operating conditions
within an incinerator by comparing the results of laboratory decomposition
experiments to the results of full-scale test burn experiments under
similar conditions.
aThe pilot burn results were based on sampling flue gas downstream of a
quench and a scrubber and sampling quench and scrubber water, rather than
sampling flue gas before the quench and scrubber. The accuracy of these
results is unknown. For more details see Reference 5.
E-9
-------
Data from the laboratory devices may have some value for checking the
accuracy of various theoretical thermochemical modeling techniques used
to predict the behavior of full scale incinerators. Such data may also
be compiled and used to develop empirical modeling techniques.
• Data from the device might be used to help determine research priorities
for hazardous waste incineration (when better data are unavailable) by
considering the types, amounts, and potencies of the reaction products
observed. Various risk assessment and prioritization models may be used
for this purpose.
• Data from laboratory waste decomposition experiments may be of some value
for helping to determine operating conditions at the beginning of trial
burns. Temperature, retention time, turbulence, and excess air levels at
the beginning of trial burns should be far enough above those associated
with unacceptable emissions (based on laboratory data) to give a reasonable
confidence of having acceptable emissions. Unfortunately, the margins of
safety for this purpose have not been systematically studied.
Data from laboratory tests might be used to help determine what to monitor
at trial burns and at full-scale industrial installations.
Unfortunately, the limitations of using the data from the laboratory devices
for the above purposes have not been demonstrated. Additional tests will have
to be performed under conditions that more nearly approximate those in an
operating incinerator, if scaleup factors are to be systematically studied.
Without such studies, any scaleup based on the data from laboratory experiments
alone will only result in an educated guess, of unknown accuracy.
Figure E-4 shows the effects of oxygen concentrations on the thermal decom-
position of a PCB in the thermal decomposition device. The high sensitivity
to oxygen is clearly shown. This suggests that operating laboratory devices (or
modifying them to operate) with amounts of excess air similar to those found
in an incinerator may significantly improve the utility of the data generated.
If the percent oxygen used in a laboratory experiment is equivalent to the
percent oxygen in incinerator flue gas, the probability of a laboratory
experiment yielding a lower destruction and removal efficiency than in an
incinerator will be increased (compared to when it is operated at 21% oxygen).
This may increase the utility of laboratory data for quickly making conserva-
tive estimates of acceptable operating conditions at the beginning of trial
burns.
E-10
-------
100
10
H
II
0.1
0.01
50
HELIUM
-------
8. RESULTS OF LABORATORY-SCALE DECOMPOSITION EXPERIMENTS
8.1 Kepone Results
Kepone decomposition experiments were performed in the thermal decomposition
device. As can be seen from Table E-2, the destruction of Kepone increases
with increasing temperature (at a relatively constant retention time). It
is also apparent that there are several byproducts: hexachlorobenzene, hexa-
chlorocyclopentadiene [3] and hexachloroindenone (the latter was identified in a
personal communication with Don Duvall and Wayne Rubey, at the University of
Dayton Research Institute in Dayton, Ohio on 4 August 1980). The amounts of
byproducts formed are dependent upon the reactor temperature. This information
is graphically represented in Figure E-5.
8.2 Method of Data Analysis
The Kepone destruction and removal efficiency was usually calculated based on
changes in the response of a hydrogen flame ionization detector to Kepone.
Hydrogen flame ionization detectors and associated electronics usually respond
linearly to concentrations. The destruction and removal efficiency was calcu-
lated using the responses of the detector to samples collected in the trap
with and without thermal stressing in the reactor, assuming linearity of response.
The assumption of linearity of response was not verified experimentally.
E-12
-------
TABLE E-2. KEPONE THERMAL DESTRUCTION SUMMARY [1*]
Waste: kepone.- sample size: 40 pg;
laboratory device: thermal decomposition device.
Unit
temperature . Input
°C atmosphere
302
397
435
463
495
603
708
807
910
433
433
433
Air.
Air.
Air.
Air,
Air.
Air.
Air.
Air.
Air.
Air.
Air.
Air,
21% 02
21% 0,
21% 0,
21% 02
21% 0,
21% 02
21% 02
21% 02
21% 02
21% 02
21% 02
21% 02
Destruction
Retention and removal
time. efficiency.
s %
0.93
0.99
0.94
0.93
1.10
0.99
0.91
0.92
0.94
0.23
1.04
1.79
0
12
48
96
299.55
299.55
299.55
299.55
299.999655
6
53
68
Relative
Byproducts. quantity of
identified^ byproducts
None
Hexachlor ocyc lopentadiene
Hexachloroindenone
Hexachlorocyclopentadiene
Hexachloroindenone
Hexachlorocyclopentadiene
Hexachloroindenone
Hexachlorocyc lopentadiene
Hexachloroindenone
Hexachlorobenzene
Hexachlorobenzene
Hexachloroindenone
Hexachlorocyclopentadiene
Hexachlorobenzene
Hexachloroindenone
Hexachlorobenzene
Hexachlorobenzene
Not reported
Not reported
Not reported
None
0.05
0.05
0.5
0.75
0.85
0.65
0.65
^*^d
-
0.04
1.75
0.05
1.10
0.05
0.45
0.15
NA
NA
NA
Hexachloroindenone identified in a personal communication with Don Duvall and
Wayne Rubey. University of Dayton Research Institute. Dayton. Ohio. 4 August 1980.
Byproducts collected on Tenax CC and detected in quantifiable amounts unless otherwise
specified.
cReported as relative peak heights on a flame ionization detector.
Detected, but below measureable levels.
"collected on activated carbon, desorbed with mixed solvent (Acetone. Benzene. CS2) and
quantified with an electron capture detector (residual kepone 138 pg; hexachlorobenzene
*200 mg).
fNot applicable.
E-13
-------
e
100
30
10
3.0
1.0
Q.
£ 0.3
0.1
0.03
0.01
5 Ka - HEXACHLOROCYCLOPENTADIENE
- KK • HEXACHLOROINDENONE
_ D
Kc - HEXACHLOROBENZENE
KEPONE
1
200 400 600
TEMPERATURE, O
800
1,000
Figure E-5. Thermal destruction plot for Kepone [3].
^exachloroindenone identified in a personal communication with Don Duvall and
Wayne Rubey, University of Dayton Research Institute, Dayton, Ohio,
August 4, 1980.
E-14
-------
9. REFERENCES
1. Rubey, W. A. Design considerations for a thermal decomposition analytical
system. Cincinnati, OH; U.S. Environmental Protection Agency; 1980
August. 143 p. EPA-600/2-80-098.
2. Duvall, D. S.; Rubey, W. A.; and Hescher, J. A. High temperature
decomposition of organic hazardous waste. Proceedings of the sixth annual
research symposium; 1980 March 17-20; Chicago. Cincinnati, OH; U.S.
Environmental Protection Agency; 1980, 121-131.
3. Duvall, D. S.; and Rubey, W. A. Laboratory evaluation of high temperature
destruction of Kepone and related pesticides. Cincinnati, OH; U.S.
Environmental Protection Agency,- 1976 December. 59 p. EPA-600/2-76-299.
4. Duvall, D. S.; Rubey, W. A.; and Mescher, J. A. Application of the
thermal decomposition analytical system. Proceedings of the seventy-
third annual meeting of the Air Pollution Control Association; 1980
June 22-27; Montreal. 15 p.
5. Bell, B. A.; and Whitmore, F. C. Kepone incineration test program.
Cincinnati, OH; U.S. Environmental Protection Agency; 1978 May. 146 p.
EPA-600/2/78-108.
E-15
-------
APPENDIX F
TRIAL BURN SUMMARIES
-------
TABLE F-l. SUMMARY OF INCINERATOR DESTRUCTION EFFICIENCY TEST WORK
Waste
Incinerator
Shell aldrin (20%
granules) [1]
Shell aldrite [1]
Atrazine - liquid [l]
Atrazine - solid [1]
Para-arsanilic
acid [2]
Captan - solid [l]
Chlordane 5% dust [3]
Chlordane, 72% emulsi-
fiable concentrate
and No. 2 fuel
oil [3]
Chlorinated
hydrocarbons,
trichloropropane,
trichloroethane,
and dichloroethane
predominating [12]
Chloroform [2]
DDT 5% oil solu-
tion [1]
DDT (solid) [14]
DDT, 10% dust [1]
Multiple chamber
Multiple chamber
Multiple chamber
Multiple chamber
Molten salt combustion
Multiple chamber
Liquid injection
Liquid injection
Two high temperature
incinerators
Performing organization
Midwest Research
Midwest Research
Midwest Research
Midwest Research
Rockwell International
Midwest Research
TRW
TRW
M/T Vulcanus Ocean
Combustion Services
Molten salt combustion Rockwell International
Liquid injection TRW
Municipal multiple
hearth sewage sludge
incinerator
Multiple chamber
City of Palo Alto
Midwest Research
Destruction efficiency (DE)
of principle components,
percent
Aldrin
Total species
Aldrin
Total species
Atrazine
Total species
Atrazine
Total species
>99.99
>99.99
>99.99
>99.99
>99.99
>99.99
>99.99
>99.99
>99.999
Captan >99.99
Total species >99.99
Chlordane >99.99
Chlordane >99.999
Chlorinated 99.92 -
hydrocarbons 99.98
Chloroform
DDT
DDT
DDT
Total species
>99.999
>99.99
>99.970 -
99.983
>99.99
>99.99
(continued)
-------
TABLE F-l (continued)
i
ro
Destruction efficiency (DE)
of principle components,
Waste
20% DDT oil solu-
tion [3]
DDT 25% emuls if table
concentrate [3]
DDT 25% emulsifiable
concentrate [l]
DDT oil 20% emulsified
DDT
Waste oil - 1.7%
PCB [13]
DDT powder [2]
Dieldrin 15%
Incinerator
Liquid injection
Liquid injection
Multiple chamber
Thermal oxidizer
waste incinerator
Molten salt combustion
Liquid injection
Performing organization
TRW
TRW
Midwest Research
General Electric Co.
Rockwell International
TRW
percent
DDT
DDT
DDT
Total species
DDT
PCB
>99.98
>99.99
>99.98 -
>99.99
>99.98 -
>99.99
>99.99
99.9999
>99.9921 -
>99.9995
99.998
>99.999
emulsifiable
concentrate [3]
Dieldrin - 15%
emulsifiable
concentrates and 72%
chlordane emulsifi-
able concentrates
(mixed 1:3 ratio) [3]
Diphenylamine-HCl [2]
Ethylene manufacturing
waste [5]
GB
Liquid injection
TRW
Molten salt combustion
Liquid injection
Rockwell International
Marquardt Co.
Molten salt combustion Rockwell International
Waste con-
stituents
Total
organics
>99.98
>99.999
>99.999
99.95 -
99.99
>99.9999998
>99.9999997
(continued)
-------
TABLE F-l (continued)
w
Waste Incinerator Performing organization
Herbicide orange [19] Two identical refrac- M/T Vulcanus Ocean
tory-lined furnaces Combustion Services
Hexachlorocyclo- Liquid injection Marquardt Co.
pentadiene [5]
Destruction efficiency 99.99
(combined
total)
>99.999
99.94 -
99.99
>99.9999
Acetic acid, solution
of kepone [6]
Toledo Sludge & Kepone
Co. - incineration
[6]
Lindane, 12%
emulsifiable
concentrate [3]
Malathion [2]
Malathion, 25% wet
power [l]
Malathion 57%
emulsifiable
concentrate [l]
Methyl methacrylate
(MMA) [5]
Rotary kiln pyrolyzer Midland - Ross
Liquid injection
Molten salt combustion
Multiple chamber
Multiple chamber
Fluidized bed
TRW
Rockwell International
Midwest Research
Midwest Research
Systems Tech
>99.9999
>99.999
99.999 -
99.9998
Malathion >99.99
Total species >99.99
Malathion >99.99
Total species >99.98
Waste con-
stituents
Total
organics
>99.999
99.96 -
99.98
(continued)
-------
TABLE F-l (continued)
Waste
0.3% Mirex Bait [l]
Mustard [2]
Nitrochlorobenzene [5]
Nitroethane [2]
Phenol waste [5]
Picloram [l]
Picloram (Tordon 10K
pellets) [1]
PCB's (8]
PCB capacitors (7]
DPR f/. 1
Incinerator Performing organization
Multiple chamber Midwest Research
Molten salt combustion Rockwell International
Liquid injection Rollins
Molten salt combustion Rockwell International
Fluidized bed Systems Tech
Multiple chamber Midwest Research
Multiple chamber Midwest Research
Rotary kiln Rollins
Rotary kiln Rollins
Cement kiln Swedish Water and Air
Destruction efficiency (DE)
of principle components,
percent
Mirex
Total species
Waste con-
stituents
Total
organics
Waste con-
stituents
Total
organics
Picloram
Total species
Picloram
Total species
Waste con-
stituents
Total
organics
>98.21 -
99.98
>97.78 -
99.96
>99. 999982
>99. 999985
>99.99 -
99.999
99.84 -
99.87
>99.993
>99.99
99.93 -
99.95
>99.99
>99.63 -
>99.99
>99.99
>99.93 -
>99.99
>99. 999964
>99. 999977
99.5 - '
99.999
99.96 -
99.98
>99.9998
Pollution Research
Institute
(continued)
-------
TABLE F-l (continued)
m
Waste
Incinerator
Polyvinyl chloride
waste [9]
Toxaphene 20% dust [l]
Toxaphene 60%
emulsifiable
concentrate [l]
Trichloroethane [2]
2,4-D low volatile
liquid ester 13]
2,4,5-T (Weedon")
[14]
2,4,5-T (10, 11]
2,4,5-T [4]
2,4,5-T [4]
2,4,5-T [4]
Rotary kiln
Multiple chamber
Multiple chamber
Molten salt combustion
Liquid injection
Municipal multiple
hearth sewage sludge
incinerator
Single hearth furnace
Single hearth furnace
Single hearth furnace
Single hearth furnace
Performing organization
3 M Company
Midwest Research
Midwest Research
Rockwell International
TRW
City of Palo Alto
Swedish Water and Air
Pollution Research
Institute
Swedish Water and Air
Pollution Research
Institute
Swedish Water and Air
Pollution Research
Institute
Swedish Water and Air
Pollution Research
Institute
Destruction efficiency (DE)
of principle components,
percent
Total
organics
Chlorinated
organics
99.80 -
99.88
99.99
>99.99
>99.99
>99.99
>99.99
99.990 -
99.996
99.995
99.995
92
99.995
(continued)
-------
Waste
VX
Zineb [1]
TABLE F-l (continued)
Inc'ineratojr.
i ' • " T i —
•**BeStruct'Jo,n efficiency (DE)
iff prin£ip& components,
Performing organization !>• percent .
holten salt combustion Rockwell International
Multiple chamber Midfcest Research
>99;,999989 -
99,.99999A5
DE =
W.
in
Where:
x 100
W = mass, feed rate of |£he principal toxic component
W in = mass^emission rate of the principle toxic component in the incinerator combustion zone
'out
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References
1. Ferguson, T. L. ; Bergman, F. J. ; Cooper, G. R. ; Li, R. T."l and Homea, F.
I. ; Determination of incinerator operating conditions ne
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14. A study of pesticide disposal in a sewage sludge incinerator. Whitmore
and Durfee, Versar, Inc. Contract 68-01-1587. 1975.
15. Ahling, B., "The Combustion of Waste Containing DDT and Lindan," The
Science of the Total Environment. 9, (1978) pp. 117*12"4.
16. Ahling, Bengt and Lindskog. "Thermal Destruction of PCB and Hexachloro-
benzene." The Science of the Total Environment,, 10, (1978) pp. 51-59.
17. Jannson, B. and C. Sundstrom, "Formation of polychlorinated dibenzo-p-
dioxins during combustion of chlorophenol formulations," The Science of
the Total Environment. 10, (1978), pp. 209-217.
18. Personal contact, August 12, 1980, James A. ftftimbuclu Industrial Sales
Manager, Hazardous and Toxic Wastes, Ztapro, Inc. Rothschild, Wisconsin
54474.
19. Ackerman, P. G.; H. J. Fisher, R. J. Johnson, R F, Haddalone,
B. J. Matthews, E. L. Moon, K. H. Scheyer, C. C. Shih; and R. F. Tobias.
At-sea incineration of herbicide orange on-boatd the-ro/t vulcanus.
EPA, 1978 April, 263 p.
20. "Fluidized-bed incineration of selected carbonaceous industrial wastes,"
Prepared by Battelle Laboratories, Columbus, Ohio. March 1972.
21. Acurex Corp., Test incineration of electrical capacitors containing PCB's,
Electric Power Research Institute, 1980 May.
22. Destroying chemical wastes in commercial-scale incinerators-facility
report 2. USEPA 1977, Contract 68-01-2966.
23. ibid., facility report 3. USEPA 1977, Contract 68-01-2966.
24. ibid., facility report 4. USEPA 1977, Contract 68-01-2966.
25. ibid., facility report 6. USEPA 1977, Contract 28-01-2966.
26. Emission Testing at Continental Can Company; Hopewell, Virginia, USEPA,
October, 1976.
F-8
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