DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
CONSUMER PROTECTION AND ENVIRONMENTAL HEALTH SERVICE
NATIONAL AIR POLLUTION CONTROL ADMINISTRATION
DIVISION OF PROCESS CONTROL ENGINEERING
DIVISION OF ECONOMIC EFFECTS RESEARCH
CONTROL OF ATMOSPHERIC EMISSIONS
IN THE WOOD PULPING INDUSTRY
FINAL REPORT
CONTRACT NO. CPA 22-69-18
MARCH 15, 1970
VOLUME 3
ENVIRONMENTAL ENGINEERING, INC., GAINESVILLE, FLORIDA
E. SIRRINE COMPANY, GREENVILLE, SOUTH CAROLINA
-------
CONTRACTORS:
Environmental Engineering, Inc.
2324 S. W. 34th Street
Gainesville, Florida 32601
J. E. Sirrine Company
P. 0. Box 5456
Greenville, South Carolina 29606
SUB-CONTRACTORS:
CONSULTANT:
Reynolds, Smith and Hills
P. 0. Box 4850
Jacksonville, Florida 32201
PolyCon Corporation
185 Arch Street
Ramsey, New Jersey 07446
Professor Donald F. Adams
Washington State University
Pullman, Washington 99163
-------
DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
CONSUMER PROTECTION AND ENVIRONMENTAL HEALTH SERVICE
NATIONAL AIR POLLUTION CONTROL ADMINISTRATION
DIVISION OF PROCESS CONTROL ENGINEERING
DIVISION OF ECONOMIC EFFECTS RESEARCH
CONTROL OF ATMOSPHERIC EMISSIONS
IN THE WOOD PULPING INDUSTRY
FINAL REPORT by
CONTRACT NO. CPA 22-69-18 E R Hendrickson, Ph. D., P. E.,
MARCH 15, 1970 Principal Investigator
VOLUME 3
J. E. Roberson, M. S., P. E.,
Sirrine Project Manager
J. B. Koogler, Ph. 0., P. E.,
EEI Project Manager
ENVIRONMENTAL ENGINEERING, INC., GAINESVILLE, FLORIDA
J. E. SIRRINE COMPANY, GREENVILLE, SOUTH CAROLINA
-------
GENERAL TABLE OF CONTENTS
A Detailed Table of Contents for Each Chapter
Will Be Found on the Separator Sheet
Preceding Each Chapter
VOLUME I
Page No.
Letter of Transmittal iii
Abstract v
Acknowledgements vii
Preface ix
Chapter 1 - INTRODUCTION
Air Quality Act of 1967 1-1
General Description of Industry Studies 1-1
Objectives of This Study 1-2
Procedures for the Study 1-2
Chapter 2 - THE CHEMICAL WOOD PULPING INDUSTRY
Summary 2-1
Introduction 2-2
Economic Position 2-4
Present Geographic Distribution 2-6
Forecasts , 2-9
References 2-14
-------
Page No.
Chapter 3 - PRESENT PULPING PRACTICES
Summary 3_1
Introduction 3_2
Kraft Pulping 3-12
NSSC Pulping 3-54
Sulfite Pulping 3-62
Chapter 4 - QUANTITY AND NATURE OF EMISSIONS
Summary 4-1
Introduction 4_2
Kraft Gaseous Emissions 4_4
Kraft Particulate Emissions 4-44
NSSC Emissions 4-49
Sulfite Emissions 4-53
Auxiliary Furnace Emissions 4-59
References 4-66
Appendix A - Summary Data for Chapter 2
VOLUME II
Chapter 5 - CONTROL METHODS PRESENTLY IN USE
Summary 5-1
Introduction 5-3
General Description of Control Equipment 5-4
Application, Cost, and Effectiveness of Present
Control Methods 5-25
-------
Page No.
Kraft Sources 5-33
Sulfite Sources 5-151
NSSC Sources 5-156
References 5-157
Chapter 6 - NEW DEVELOPMENTS IN CONTROL TECHNOLOGY
Summary 6-1
Introduction 6-2
General Description of Control Methods 6-2
Application, Cost, and Effectiveness of New
Control Methods 6-10
Kraft Sources 6-10
Sulfite Sources 6-40
NSSC Sources 6-42
References 6-45
Chapter 7 - CRITICAL REVIEW OF CONTROL TECHNOLOGY
Summary 7-1
Introduction 7-2
Kraft Process 7-3
Sulfite Process 7-18
NSSC Process 7-21
Chapter 8 - POWER BOILER SULFUR RECOVERY
Summary 8-1
Introduction . 8-2
Flue Gas Desulfurization Technology 8-19
-------
Page No.
Process Feasibility Considerations 8-32
R & D Efforts 8-38
References 8-39
Appendix B - Summary Data for Chapter 8
VOLUME III
Chapter 9 - SAMPLING AND ANALYTICAL TECHNIQUES
Summary 9-1
Introduction 9-2
Kraft Sources 9-4
Sulfite Sources 9-65
NSSC Sources 9-76
References 9-77
Chapter 10 - ON-GOING RESEARCH RELATED TO REDUCTION
OF EMISSIONS
Summary 10-1
Introduction ' 10-2
Emissions Control Technology 10-2
Cost and Effectiveness of Emission Control 10-39
Sampling and Analytical Techniques 10-40
Control Equipment Development 10-50
Process Changes Affecting Emissions 10-54
Chemistry of Pollutant Formation or Interactions 10-57
New Pulping Processes 10-68
Control Systems Development 10-72
-------
Page No.
Chapter 11 - RESEARCH AND DEVELOPMENT RECOMMENDATIONS
Summary 11-1
Areas of Needed Research 11-2
Specific R & D Projects 11-6
Emission Control Technology 11-6
Cost and Effectiveness of Emission Control 11-8
Sampling and Analytical Techniques 11-9
I
Control Equipment Development 11-10
'Process Changes 11-10
Chemistry of Pollutant Formation or Interaction 11-11
New Pulping Processes 11-12
Control System Development 11-12
Other 11-12
Chapter 12 - CURRENT INDUSTRY INVESTMENT AND OPERATING
COSTS
Summary 12-1
Introduction 12-2
Incremental Cost Categories 12-7
Chapter 13 - FUTURE INDUSTRY INVESTMENT AND OPERATING
COSTS
Summary 13-1
Introduction 13-2
Concepts for a Management Model 13-2
-------
Page No.
Analysis of Emission Sources and Controls 13-9
Assignment of. Costs 13-33
Trends in Future Capital Expenditures 13-40
References 13-49
-------
CHAPTER 9
SAMPLING AND ANALYTICAL TECHNIQUES
TABLE OF CONTENTS
Summary
Introduction
Kraft Sources
Source Sampling (Gases)
Source Sampling (Particulates)
Source Sampling (Non-sulfur)
Recommended Source Methods
Ambient Sampling (Gases)
Ambient Sampling (Particulates)
Recommended Ambient Methods
Sulfite Sources
Source Sampling (Gases)
Source Sampling (Particulates)
Recommended Source Methods
Ambient Sampling (Gases)
Ambient Sampling (Particulates)
Recommended Ambient Methods
NSSC Sources
References
Page No.
9- 1
9- 2
9- 4
9- 5
9-24
9-28
9-28
9-33
9-60
9-63
9-65
9-65
9-67
9-68
9-69
9-74
9-75
9-76
9-77
9-i
-------
CHAPTER 9
SAMPLING AND ANALYTICAL TECHNIOUES
SUMMARY
At the very heart of any program to improve air
quality are adequate and accurate sampling and analytical
techniques. Monitoring of both the ambient air and sources
of emissions are necessary to define the problems, determine
the basis for design of corrective measures, if necessory,
and evaluate the results of reducing emissions. Both sampling
and analysis are equally important parts of the monitoring
procedures.
This chapter is not intended as a complete descrip-
tion of all sampling and analytical techniques applicable to
pulping operations. The references cited, however, do give
complete details. Most of the methods applicable to both
sources in the mills and the ambient air must be considered
research methods in a state of evolution at this time. Few
standardized procedures are available at present for the
compounds of interest. Information on accuracy, precision,
and reliability is very limited.
The sampling and analysis of gases and particulates
produced during the manufacture of pulp, whether they be in
the emission streams or in the atmosphere, has been in a rapidly
changing state as the result of continuing application of new
technology. The last twenty years has seen progress from the
early applications of conventional wet chemical analytical
techniques to the development of relatively sophisticated gas
chromatographic procedures which permit sulfur-specific sepa-
ration of a spectrum of sulfur-containing compounds present in
the atmosphere and in the pulping process emission streams and
final reduction of the analytical data by computer from data
logged on magnetic tape. Each of the various available analyti-
cal procedures has either served a useful purpose in providing
9-1
-------
initial identification of the type and magnitude of the
pulping industry's air pollution problem or in the im-
mediate and continuous monitoring and control of the unit
processes so that the causes of the emissions can be mini-
mized or eliminated.
It must be recognized that suitable methods of
analysis are not available for all compounds of interest.
A review of the available methods for malodorous sulfur
compounds reveals that many are inadequate or relatively
new and untried. It is apparent that many of the available
methods and instruments have not achieved the state of
reliability and simplicity needed for routine application.
The descriptions and evaluation of available
methods are grouped under source or ambient for each of the
pulping processes of interest to this study (kraft, sulfite,
and NSSC). For each grouping recommendations are made of
the best available procedures.
9.1 INTRODUCTION
At the very heart of any program to improve air quality are
adequate and accurate sampling and analytical techniques„
Monitoring of both the ambient air and sources of emissions
are necessary to define the problems, determine the basis
for design of corrective measures if necessary, and evaluate
the results of reducing emissions. Both sampling and analysis
are equally important parts of the monitoring procedures.
This chapter is not intended as a complete description of all
sampling and analytical techniques applicable to pulping
operations. The references cited, however, do give complete
details. Most of the methods applicable to both sources in
the mills and the ambient air must be considered research
methods in a state of evolution at this time. Few standardized
procedures are available at present for the compounds of interest.
Information on accuracy, precision, and reliability is very
limitedo
9-2
-------
9.1.1 GENERAL PROBLEMS OF SOURCE SAMPLING
Collection of representative samples of gases and
particulates from a source is an art in itself.
Separation of particulates and gases from the gas
stream is frequently required and presents special
problems in this instance because of the possibility
of odorous gases being adsorbed on the particulates.
The sampling of particulates requires that strict
attention be given to the well known problems
associated with isokinetic sampling. When particu-
late matter is in the range of 3 y or greater, the
inertial effect on the particles can produce an
erroneous sample if the velocity of the sample in
the sample nozzle or probe is not the same as the
velocity of the gas stream at the sampling point.
When the gas velocity within the probe is less than
the gas velocity in the duct, the sample collected
contains a relatively higher proportion of heavier
particles and the error is on the high side. Con-
versely, when the sample gas velocity is greater
than the gas velocity of the duct, the heavier
particles are not collected, and the error is on
the low side.
It has been concluded from many isokinesic studies
reported in the literature that isokinetic sampling
is not necessary when the particulate matter sampled
is below 5 p in size.
Procedures and recommendations for conducting source
sampling have been published by the National Council
for Air and Stream Improvement (67, 74), Industrial
Gas Cleaning Institute (71 - 73), and American Society
of Mechanical Engineers (66).
Several extensive research contracts on source
sampling are being conducted for NAPCA. Results of
these studies should improve our knowledge concerning
source sampling techniques.
9-3
-------
9.1.2 GENERAL PROBLEMS OF AMBIENT SAMPLING
There are several stages involved in making quantitative
determinations of the relatively low concentrations of
gases and particulates of interest in the ambient air.
Representative samples must be collected, refined, and
analyzed before results can be calculated. Decisions
must be made as to location of collector, type of
collector, size of sample required, rate and duration
of sampling, and analytical technique to be used. Such
decisions frequently are not mutually independent. The
problems associated with separation of gases and particu-
lates are of importance for the reasons cited in the last
section.
Procedures for planning the sampling of the atmosphere
are available from NCASI, ASTM, APCA, and the Intersociety
Committee.
Unfortunately few standard methods of analysis with known
precision, accuracy, and interferences are available at
this time for compounds of interest. Hopefully the activities
of the Intersociety Committee, ASTM, and the Analytical
Methods Evaluation Service of NAPCA will remedy this situation
in the near future.
9.2 KRAFT SOURCES
The sampling and analysis of gases and particulates produced
during the manufacture of pulp, whether they be in the
emission streams or in the atmosphere, has been in a rapidly
changing state as the result of continuing application of new
technology. The last twenty years has seen progress from the
early applications of conventional wet chemical analytical
techniques to the development of relatively sophisticated gas
chromatographic procedures which permit sulfur-specific
separation of a spectrum of sulfur-containing compounds
present in the atmosphere and in the pulping process emission
streams and final reduction of the analytical data by computer
from data logged on magnetic tape* Each of the various avail-
able analytical procedures has either served a useful purpose
9-4
-------
in providing initial identification of the type and
magnitude of the pulping industry's air pollution
problem or in the immediate and continuous monitoring
and control of the unit processes so that the causes
of the emissions can be minimized or eliminated.
Major emissions from sources in the kraft process have
been identified and characterized in Chapter 4. Par-
ticulates of interest include mainly sodium sulfate,
sodium carbonate, calcium carbonate, and calcium oxide.
The principle gaseous emissions include sulfur dioxide,
hydrogen sulfide, and various alkyl mercaptans, sulfides,
and disulfides. Many other gaseous compounds are formed
in the process or in the atmosphere, but appear in much
lower concentration. It must be recognized that suitable
methods of analysis are not available for some of the
compounds of interest. A review of the available methods
for analysis of malodorous sulfur compounds will indicate
that many are either inadequate or relatively new and
untried. It is apparent that many of the available
methods and instruments have not achieved the state of
reliability and simplicity needed for routine application.
Control techniques presently available, when applied to
kraft sources, may reduce the emission of the hydrogen
sulfide to the point where it is no longer the major
constituent and may require monitoring of compounds for
which we have no satisfactory analytical methods.
9.2.1 SOURCE SAMPLING (GASES)
Analytical techniques have always been an important aspect
of engineering development. In 1953, Felicetta, et al. (I)
stated:
"Those interested in kraft pulp production have
expended much effort on the development of pro-
cesses to avoid the discharge of odorous substances
from kraft pulp mills. While this effort has
resulted in important progress, the problem does
not appear to be entirely solved because practical
means for complete odor elimination do not seem to
have been yet established. A major difficulty in
locating odor sources and in testing performance of
odor elimination processes has been the lack of
accurate and facile analytical methods."
9-5
-------
Analytical techniques used in the 50's and early 60's did
not produce sufficient data to permit major breakthroughs
in odor reduction technology. Wet chemical methods such
as proposed by Fellicetta, et al. (1_) in 1953, while they
did permit determination of the four major malodorous
sulfur-containing compounds emitted from the kraft pulping
process, were quite tedious and required one man-day to
perform two or four analyses. Since two analyses are
generally required to establish efficiency of a particular
process—up and down stream—little progress could be
expected.
Those pioneer chemists who did study process emissions with
wet chemical methods or early gas chromatographic techniques
reported such wide variations in emission levels from one
sample to another that management failed to accept the
validity of the data. Within the past two to three years,
however, continuous monitoring instrumentation utilized by
a number of mills, the National Council for Air and Stream
Improvement/ and others have produced sufficient data to
confirm that processes which were once thought to be at
equilibrium are, in fact, subject to frequent and wide
excursions in emission rates. Accurate material balances
can be attained only by continuous or frequent interval
sampling. Variability in composition caused by changes in
operating parameters are common in a kraft mill and flow
rates vary widely.
9.2.1.1 Odors
Monitoring of odors represents one of the most difficult
problems facing workers in the field. Even at source con-
centrations, methods frequently are not available for chemical
analysis of odorous compounds of interest. In several instances
the available chemical methods have a sensitivity which is
above the human odor threshold for a given compound.
Human sensors suffer from other shortcomings in attempting to
"quantify" odor concentrations. Among the factors which
influence the individual's response, according to Lindvall (2) ,
are sense of smell, age, hormonal factors, diurnal variation,
adaptation, nature and strength of stimulus, motivation,
attitude and expectations regarding the experiment, and previous
experience. Nevertheless, physiologists feel that these variables
can be compensated for and that this is the only method of evalua-
tion available in many instances.
9-6
-------
Cederl6f and co-workers (3_) designed a single chamber
exposure hood and flue gas dilution system which per-
mitted determination of odor thresholds in the field
for various flue gases from the kraft process. A
number of subjects compared different samples of flue
gases diluted with fresh air and decided at what con-
centration the flue gas odor was no longer noticeable.
Estimates of the effects of different deodorizing
measures were obtained by taking the flue gas samples
from the stack and from various phases of the production
process.
Sullivan, et al. (4j designed and installed a six-
chamber exposure hood and gas dilution system in a 35-
foot bus which could be driven to mill sites to determine
flue gas odor detection thresholds and the effects of
odor control processes on the detection thresholds of
the resultant gases.
Use of human panelists, exposure chambers, and flue gas
dilution systems can provide meaningful data which can
be directly related to the engineering design and opti-
mem operation of odor control processes.
9.2.1.2 Manual Sampling and Analysis
As indicated in the introduction to this chapter, the
proper collection and handling of the sample prior to
analysis is as important as the analytical method.
Batch samples must be collected and handled with care
to prevent sorption and reaction prior to analysis. In
some cases, only continuous sampling systems can be used.
Particulate matter must be separated from gases insofar
as possible in a manner which avoids sorption of the
gases or contribution of interferences. The interactions
between gases and particulate matter has not been definitely
established.
The chemical nature of kraft mill gaseous effluent streams
has been studied by a number of investigators utilizing
mass spectrometry, gas, and column chromatography. A 1952
mass spectrometric study by Fellicetta, et al. (1) reported
that the major sulfur-containing compounds were hydrogen
sulfide, methyl mercaptan, dimethyl sulfide, and dimethyl
9-7
-------
disulfide, whereas sulfur compounds containing ethyl
groups were substantially absent. Subsequent investi-
gators have confirmed the identity of the major sulfur-
containing gases and have reported lesser concentra-
tions of isopropyl mercaptan (5).
Fellicetta, et al. (1) collected batch samples in
evacuated 20-liter bottles. Hydrogen sulfide and
mercaptans were determined by potentiometric titration
with silver nitrate (6_, 7_) using a silver wire coated
with silver sulfide as the indicating electrode. Aqueous
samples are titrated in 1.0 N aqueous sodium hydroxide to
which ammonium hydroxide has been added to prevent pre-
cipitation of silver oxide. Elemental sulfur interferes
with the procedure since it reacts with the mercaptan
and the reaction product imparts an electrode potential
too close to that of the sulfide ion. The alkyl sulfides
and disulfides were then determined by bromate-bromide
titration (8_, 9) .
Although the method did provide limited information con-
cerning the relative quantities of the four major malodorous
sulfur compounds present in various process streams, little
useful information was thereby obtained describing the
relationship between these sulfur gases and process variables
because of the tedious and time-consuming nature of the
procedure. The usual and understandable response of kraft
mill chemists was one of disenchantment with the method
because of the unfavorable ratio of useful information to
man-hours expended.
Martin (10) utilized a sequential sampler on the recovery
furnace stack to obtain a 30-minute sample every two hours
over a 24-hour period. One complete cycle of twelve samples
was run each weekday. The impinger charge was analyzed for
H S by argentometric titration.
Wright and associates (11) studied the colorimetric deter-
mination of hydrogen sulfide and methyl mercaptan. These
authors contended that an analytical improvement was
achieved through the substitution of an intermediate color
body—Bindschindler's green—for the usual dimethyl-p-
phenylenediamine.
9-8
-------
In 1957, Colombo, et al. (12) critically evaluated the
wet chemical methods then available for the separation
and analysis of the major sulfur-containing compound
types present in kraft pulp mill gaseous emissions.
The Bertgstrtim-Trobeck procedure (13, 14) utilizing
selective absorption in solutions of acidified cadmium
chloride, mercury cyanide, and mercuric chloride was
considered unsatisfactory because of the interference
of sulfur dioxide in the determination of hydrogen sulfide.
The Wright: et al. Bindschindler green method for hydrogen
sulfide and methyl mercaptan was considered unsatisfactory
because of its low sensitivity and its non-reproducible
absorption spectra for methyl mercaptan.
The Fellicetta, et al., method' (1) utilizing the AgNO
stepwise potentiometric titration for hydrogen sulfide
was considered inadequate when the ratio of H S/CH SH is
in the range of 10-20/1.
Colombo and co-workers then proposed a selective absorp-
tion system in which SO was collected in 0.2 N sodium
acetate; hydrogen sulfide in 5% CdCl -0.2 N HC1; and
methyl mercaptan in methanol at -75°C. Analysis was
accomplished by oxidizing the SO to sulfate and precipi-
tating and weighing BaSO ; titrating the collected CdS
iodometrically and titrating the methyl mercaptan
potentiometrically with AgNO .
The Colombo procedure suffers from the obvious problems
of a time-consuming gravimetric determination of SO and
the use of a -75°C bath for collection of methyl mercaptan.
Bialkowsky and DeHaas (15) in describing one of the early
continuous methods for determining sulfur compounds in
mill gases, observed that:
"the evaluation and control of sulfur losses
in sulfate pulping and recovery operations
have been limited by the availability of
adequate and convenient testing procedures...
Thorough investigations by the U. S. Public
Health Service (16) have shown that the odor
threshold detection values for hydrogen sul-
fide, methyl mercaptan, and dimethyl sulfide
are . . . somewhat less than 1 ppm on a weight
basis."
9-9
-------
Odor threshold data developed within the past few years
have shown these thresholds to be in the ppb or less range.
Bialkowsky and DeHaas cited problems common to wet chemical
methods as well as new instrumental methods. For example,
they noted that "if oxygen is present, it is often advisable
to complete the analyses as rapidly as possible since under
wet conditions hydrogen sulfide is oxidized to elemental
sulfur and the mercaptans are converted to disulfides."
Bialkowsky and DeHaas also discussed the testing techniques
available and in use at that time including precipitation
with Hg II (13), potentiometric titration with silver nitrate
(6_, 7) , bromine oxidation in acidified solution using a bromate-
bromide solution (8_, 9), and the colorimetric determination
of H S with methylene blue or Bindschindler's green (11).
They noted that all of "these procedures are time consuming
and often-times the composition of the streams change very
rapidly."
Harding, et al., (17) modified the Fellicetta procedure and
provided for the additional collection and determination of
sulfur dioxide. Sulfur dioxide was determined by the West-
Gaeke method. Sulfamic acid was added before color develop-
ment to eliminate nitrogen dioxide interference. Hydrogen
sulfide and mercaptans were absorbed in cadmium chloride
and separated by pH adjustment of half the combined precipi-
tate to 1.0 to dissolve cadium mercaptide. The remaining
suspension was filtered, the cadmium sulfide precipitate
dissolved and the sulfide determined by iodometric titration.
The other half of the combined cadmium sulfide-mercaptide
precipitate was completely dissolved and titrated iodometrically.
The mercaptan concentration was calculated by difference between
the first and second titration. Dimethyl sulfide and dimethyl
disulfide were absorbed in benzene solution and the RSR-iodine
complex measured spectrophotometrically. The remainder was
oxidized in standard bromide-bromate for determination of
total RSR + RSSR. RSSR was calculated by difference. This
procedure also was time consuming.
In 1969, Adams and Wan (18) studied the recovery of hydrogen
sulfide in the concentration range of 50-500 ppm by collecting
the gas in a Greenburg-Smith impinger containing 100 ml of
cadmium chloride solution and titrating the collected sulfide
iodometrically according to the NCASI procedure outlined in
Technical Bulletin 28 (17) . An average recovery of 65 percent
was achieved over this concentration range. Simultaneous analysis
of the hydrogen sulfide dilutions with a Barton Model 286 showed
a relative standard deviation within ±5 percent from the prepared
9-10
-------
concentrations. The addition of 1 percent STRactan 10
to the cadmium chloride absorption solution improved
the recovery to 95 ±5 percent from the prepared con-
centration.
Batch sampling and manual, wet chemical analysis fail
to provide the type of information necessary for effec-
tive and efficient process control. The data are not
readily available for several hours after the sample is
obtained. Even if one could automate the analytical
processes,_by use of a multi-channel Technicon Auto-
Analyzer 'Q, data would not become available for approxi-
mately 15 - 30 minutes. Any system which employs one or
more steps involving batch sampling and manual analysis
techniques cannot be recommended for present day mill
process control because of (a) the unfavorable ratio of
detail of data obtained to the man hours required to
obtain the data and (b) the time lag in obtaining
analytical data which lowers its significance to mill
operators and management.
9.2.1.3 Instrumental Sampling and Analysis
The problems of representative sampling as described
previously are still applicable and must be considered
when instrumental sampling is involved.
The dual problem of particulate and water removal from
process streams prior to gas analysis must be specifically
considered for each analytical method. These problems
become more acute as the sampling time and rate increases
and generally are most critical for continuous process
monitoring.
Blosser and Cooper (29) designed a plastic and stainless
steel system which accomplishes the three functions of
particulate removal, dewatering, and SO stripping. The
primary difficulty in the mill application of this device
appears to be in the abbreviated useful lifetime of the
particulate filter.
9-11
-------
Thoen (58) has applied for a patent on a ceramic and
stainless steel probe which is claimed to filter and
dewater satisfactorily for longer periods of continu-
ous use.
Probably the most critical part of a continuous process
gas monitoring system involves particulate removal and
dewatering. Analyzers such as the Barton operate
continuously for weeks in the laboratory almost without
attention without calibration changes.
However, when automatic analysis instruments are taken
to the mill and used as continuous process monitors
subtle and/or drastic changes in calibration may take
place at anytime from a few hours to several weeks.
These changes are generally related to particulate
build-up in the sampling line between the source and
the detector, excess liquid accumulation in the detector
itself, or changes in the air sampling rate.
Careful design of the sample handling system and frequent
checking of the effectiveness of the system are required
in the early stages of the development of a continuous
monitoring program to assure adequate filtration and
dewatering. Otherwise, the program may fail.
At the present time, it appears that no completely
reliable system has been developed for removal of water
and particulates on a continuous basis. Components of
a suitable system might include a ceramic or stainless
steel filter; a cyclic blow-back to clear the probe of
collected particulates; a condenser with drop-leg; and
a short, small diameter heated sample line.
A discussion of the separation of particulates from
gases would be incomplete without mention of the proba-
bility that reactive gases such as hydrogen sulfide, sulfur
dioxide, mercaptans, et cetera, will be adsorbed onto the
particulates collected by the filter whether it be glass-
ware, ceramic, or a stainless steel frit. Adsorption
(possibly reaction) will result in an initial (or sustained)
lower apparent sulfur gas concentration. Once an equilibrium
has been established between the adsorbing surface and the
gas, the apparent concentration will approach the actual
concentration. Changes in gas concentration, either up or
9-12
-------
down, will obviously affect the equilibrium and result in
an error in measured or apparent concentration which will
lag the actual concentration. The magnitude of these
errors can be mathematically modeled for any assumed magni-
tude of range of gas concentration and demonstrated with an
analog computer.
A. pH_
Since one practical solution of kraft odor
control may well be oxidation of the malodorous
compounds to sulfur dioxide (for maximum economical
heat recovery as well as odor reduction) and because
of the rapidly varying character of the source emissions,
Bialkowsky and DeHaas (15) observed that "it is much
more important that facile and rapid methods are available
for the determination of the total amount of sulfur
compounds and sulfur dioxide.1: Unfortunately, this
observation is still true thirty years later.
To this end they proposed the catalytic oxidation of
the reduced sulfur compounds to sulfur dioxide and continuous
read-out of the resultant variation in pH of a sulfuric
acid<-hydroxide peroxide collection solution. Total
reduced sulfur was determined as the difference between
the concentrations of sulfur dioxide in the oxidized
and unoxidized emission gases.
Their data first revealed wide, short term fluctuations
in emissions of total reduced sulfur compounds not only
from the digestors, but the lime kiln and recovery furnace
as well. Until this time, the rapid and wide fluctuations
in sulfur gas content of the recovery furnace gases
had not been recognized. Unfortunately, this phenomenon
received little attention by other investigators and
mill management during the following fifteen years.
B. Lead Acetate Tape
Mathews and co-workers (20) redesigned the Rubicon acetate
tape H S instrument for the reliable, continuous duty
monitoring of H S losses. These instruments were used
extensively in their Ohio and West Virginia mills to
measure H S losses.
9-13
-------
C. Ultraviolet
In 1965, Murray and Risk (21) described an ultra
violet, real-time hydrogen sulfide analyzer to assess
the effects of operating variables on hydrogen sulfide
release from a kraft recovery furnace. Sulfur dioxide
has strong absorption bands both in the ultraviolet
and infrared; whereas, hydrogen sulfide absorption in
those wavelengths is unfortunately low. Ultraviolet
absorption was chosen for the measurement because stable,
moisture-resistant optics could be used. Since sulfur
dioxide is present in the recovery furnace flue gas, a
double beam instrument was required. Flue gas was split
into two streams, one passing through an oxidation fur-
nace where the hydrogen sulfide was converted to sulfur
dioxide in the same manner used by Bialkowsky and DeHaas
in 1952 and thence to the second optical cell. The
difference in the sulfur dioxide content of the oxidized
and reference streams was measured as the difference in
radiation intensity of the two beams. The primary
advantage of this ultraviolet analyzer over the earlier
Bialkowsky and DeHaas SO analyzer is related to the
substitution of ultraviolet spectroscopy for a wet
chemical technique, thereby improving the probability for
lower instrument maintenance.
D. Coulometry
Coulometry is based upon the electrolytic generation of
bromine from a bromine-containing electrolyte in the
absorption-reaction cell. The cell voltage is determined
by the concentration of bromine in the electrolyte. The
current flow through the bromine generating circuit is
controlled by the voltage sensing circuit to maintain a
constant predetermined concentration of bromine. As the
sample gas containing reduced sulfur compounds (and other
bromine-reacting compounds) is drawn through the cell at
a constant rate the bromine in the electrolyte is consumed,
The resultant drop in bromine concentration is sensed as
a drop in cell voltage and the bromine generating circuit
is activated to restore the original cell voltage. The
additional current flow through the bromine generation
circuit is proportional to the quantity of bromine-
titratable gases reacting in the titration cell. The
generating current readout and the sample flow rate are
9-14
-------
are then converted to concentration. Each class
of sulfur-containing gases is oxidized by a
different quantity of bromine according to the
following equations :
S°2 + 6H2° + 4Br2 " 2H2S°4 * 8HBr
H2S + 2H2° + 2Br2 * H2S°4 + 4HBr
RSH + 3H O + 3Br -> RSO H -t- 6HBr
^ £, J
RSR + HO + Br -»• RSOR + 2HBr
The Titrilog (22, 23) , utilizing this principle,
has been successfully used by Troebeck, et al.,
(24) to provide a real-time evaluation of total
reduced sulfur emissions from the small Pena
Pobre kraft mill near Mexico City for over twelve
years . The Titrilog has provided continuous infor-
mation describing relationships between changes in
process variables and reduced sulfur gas emissions.
Significant reductions in emission rates of
malodorous sulfur gases from various unit operations
with the Pena Pobre kraft mill during this period
were achieved and documented. (Parenthetically, it
should be noted despite the documented improvement
at Pena Pobre, the mill has not achieved an "odorless"
operation and that its earlier and present stage of odor
emission cannot be directly related to U. S. kraft
mill technology since the comparison is between the
40 - 80 tons per day pulp production capacity of
Pena Pobre and the 200 - 1200 tons per day pulp
production rate of typical U. S. kraft mills.) The
new version of the Titrilog reportedly has a sensi-
tivity for H S of 0.01 ppm, for SO , 0.02 ppm, and
for RSH, 0.02 ppm.
The Barton Model 286 electrolytic titrator (25) has
been used by a number of investigators for monitoring
(26) and control (27) of the emission from kraft mill
sources .
Two sampling procedures have been used by Thoen and
co-workers . Batch sampling is accomplished by draw-
ing the source gas into a 12-liter evacuated flask
through the sampling line containing a glass wool plug
9-15
-------
at the flask neck. The sample is pumped out of the
flask and into the titration cell at the rate of 200 -
300 ml/min. Total sulfur is calculated from the direct
analysis of the collected sample. Sulfur dioxide is
then removed from the sample gas by absorption in 3 percent
potassium biphthalate. The difference in generating
current corresponds to the concentration of SO in
the grab sample. Other compounds are then successively
removed with additional wet scrubbers until only the
"residual" sulfur compounds are passed into the
titration cell.
Thoen, et al. (27) provide a typical calculation
procedure for the analysis of flue gases from a furnace
burning oxidized liquor. Several ''proportionality
factors" were used in their calculations, "most of
which were taken from the Barton operating manual."
A word of caution is required at this point. Wan and
Adams (28) have compared four Barton titration cells
against standard H S atmospheres and have found that
only one of the cells approximated the manufacturer's
reactions factors sufficiently close to be used for
quantitative analysis. Each cell should be calibrated
against known concentrations and the manufacturer's
factors confirmed or new factors calculated. It should
also be noted that much of the data in the instruction
manual refers to the analysis of natural gas rather than
air or combustion gases. The calibration curves provided
in the manual are based upon a gas density of approxi-
mately 0.65 rather than 1.0.
The Barton Model 286 and the modified Model 400 (25) have
been evaluated by NCASI personnel under a wide variety of
kraft mill conditions. A detailed description of suitable
procedures for using the Barton titrators, including the
operation, modifications, calibration, batch sampling and
continuous monitoring, has been prepared by Blosser and
Cooper (29).
The quantification of each component in a mixture of
sulfur-containing gases is not possible without prior
knowledge of the ratio of compounds present or through
use of a pre-separation procedure. An approximation of
9-16
-------
the "total" sulfur gases present can be obtained
by assuming (or knowing) which of the various
possible sulfur gases predominates. There currently
is no satisfactory technique other than chromatography
for the measurement of SO in a wet gas stream according
to Blosser and Cooper.
Thoen, et al., (27) reported the use of a series of
wet gas scrubbers to separate sulfur compounds prior
to titration. The following scrubbers were recommended:
1. SO removal
2. SO + H S removal
3 % potassium biphthalate
1% cadmium sulfate and
2% boric acid
3. SO + H S + RSH
removal
4. SO + H S + RSH +
RSR removal
10% sodium hydroxide
0.5% silver nitrate
These authors state that "residual" compounds are not
removed by any of these scrubbing solutions. However,
no evidence was presented to substantiate this state-
ment.
It should be noted that others (30) have found that the
analyzer has severe limitations in the analysis of
kraft mill streams that contain all major sulfur com-
pounds in appreciable concentration. Only in measuring
emissions from the recovery furnace and lime kiln, which
contain low concentrations of organic compounds and high
concentrations of inorganic sulfur, has the application
of the instrument been satisfactory. In other kraft sources
such as washer vents, digester and evaporator noncondensibles,
et cetera, difficulty has been experienced in obtaining
quantitative separation of the classes of sulfur compounds
with the scrubber solutions. The higher concentrations
of the organic sulfur as well as high concentrations of
alcohols, ketones, and terpenes prevent a good separation.
The unit has as much as a five-minute time constant in
the electronics and a five-minute time lapse in the
sample system. However, significant fluctuations are
recorded as it responds to a concentration increase more
rapidly. Absolute values could be in error for rapidly
fluctuating concentrations.
9-17
-------
Continuous Barton records of TRS from kraft recovery
furnaces have shown changes of 200-500 ppm over a
period of less than five minutes. If one considers the
possible lag effects of (a) gas adsorption on filtered
particulates (b) the sometimes-used practice of inserting
a surge chamber between the source and the Barton, and
(c) response-time of the Barton cell, then it can only
be concluded that the observed rapid fluctuations in TRS
emissions are in fact more rapid than revealed by the
continuous records.
The sensitivity of the newer model 400 is reported (25)
to be 0.02 ppm for H S, 0.02 ppm for RSH, 0.05 ppm for
organic sulfides, and 0.05 ppm for SO .
E. Gas Chromatography
The advent of gas chromatography provided the technological
means for significant improvement in the number of source
samples which'-'could-- be 'analyzed, pier^'majbday and at the
same time provided greater detail as to the range of mer-
captans and alkyl sulfides and disulfides concomitantly
present in the various kraft mill process streams. The
gas chromatography provided an inexpensive, alternative
instrument to the mass spectrometer for identification and
quantification of the many compounds present in kraft mill
emissions streams.
Batch Technique. Adams, et al.» Oil, 32) and Cave (33)
reported the earliest applications of gas chromatography
to the analysis of kraft process gases. Adams, et al.,
concentrated the process gases on silica gel in 1/4': x
8" stainless steel tubes at -78°C. After the sample was
collected, the tubes were sealed with Swagelok caps. The
adsorbed gases were flash desorbed directly onto a 30
percent Triton X-305 column followed by a thermal con-
ductivity detector. Water vapor tended to interfere with
the determination of dimethyl disulfide, the latter peak
being superimposed upon a broad water peak. Analysis of
a single sample for the five major sulfur gases could be
completed within thirty minutes.
Adams, et al., (34) conducted an in-plant survey of
process emissions at nine West Coast kraft mills utilizing
the above technique. Rather widely varying emission rates
were found. Several significant observations were reported
9-18
-------
such as the addition of four gases to the air
feed of a black liquor oxidation tower resulted
in formation of dimethyl disulfide which was then
lost to the atmosphere.
Grune (35_) confirmed the GLC separation of volatile
sulfur gases in process streams using Triton-coated
packed columns and thermister and hot wire thermal
conductivity detectors. In addition, he showed that
a Triton-coated capillary column provided separation
of volatile sulfur gases, although a tailing of the
resultant elution peaks was observed„
Cave (33) absorbed the emission gases in ethyl
benzene at -78°C. The sample was then concentrated
by either one or two fractional distillations and the
distillate analyzed by thermal conductivity gas
chromatography on a TCP column. Approximately two
days were required to complete three distillations
and analyses.
The subsequent availability of the flame ionization
detector (FID) (36) permitted direct analysis of
organic sulfur-containing gases without the inter-
ference of water. Unfortunately, the FID is also
insensitive to H S and SO . Thomas (5) studied the
emissions from five sources at a Maine kraft mill.
Anderson (37) and Ruus (38) studied volatile organic
sulfur compounds in the kraft emissions by GLC using
a 30 percent Triton X-305 column and FID.
Bethge and Ehrenberg (39) examined the volatile
constituents of the kraft pulp mill blow and relief
gases by gas chromatography and confirmed the identi-
fication of the compounds by mass spectrometry. A
number of terpenes and twenty-five other compounds,
including hydrogen sulfide, the organic sulfides, and
thiophene were identified.
Rhoade (40) described a gas chromatographic system
using a thermal conductivity detector for the analysis
of recovery furnace combustion products, including
carbon dioxide hydrogen, oxygen, nitrogen, methane,
and carbon monoxide. He was unable, with the instrumen-
tation used, to determine any of the sulfur gases
9-19
-------
including sulfur dioxide, hydrogen sulfide, methyl
mercaptan, dimethyl sulfide, and dimethyl disulfide.
Microcoulometric (MCT) detectors using electrolyti-
cally generated iodine (41, 42) and bromine (43)
permit determination of all five major types of
sulfur-containing gases.
Adams and Koppe (44) used a bromine microcoulometric
detector in conjunction with GLC for the direct
analysis of sulfur gas emissions from a kraft mill.
The MCT detectors also respond to unsaturated hydro-
carbons , but the stoichiometry is incomplete.
Brink and co-workers (45) studied the pyrolysis
products of kraft black liquor burned in an experi-
mental laboratory furnace. Two analytical methods
were used. Gas-solid chromatography (GSC) with a
thermal conductivity detector (TC) was used to
detect the presence of several gaseous inorganic
products. GLC and FID were used to detect the
organic gases present. In addition, iodine MCT
was employed to complement FID in the quantitative
determination of volatile, sulfur-containing pyrolysis
products. Brink, et al., converted the various sulfur
gases to H S by reduction in the presence of hydrogen
as they eluted from the GLC column. This provided for
maximum detector response as well as yielding a common
titration factor for all sulfur compounds present in
the pyrolysis mixtures. They selected the reducing
mode because it has been shown (46) that conversion of
the sulfur in organic compounds to sulfur dioxide is
incomplete.
The flame photometric detector (FPD) was developed by
Brody and Cheney (47). The flame emission from sulfur-
containing compounds is viewed at 394 my by a photo-
multiplier tube.
Alley and Turner (49) described the use of an FPD for
the detection of H S, CH SH, CH SCH , CH SSCH and SO
following gas chromatographic separation on a ten-foot
column of Triton X-305 on acid washed DMES Chromosorb G.
The data show peak height linear with concentration on a
log-log plot up to about 150 ppm. A 0.25 ml sample loop
was used.
9-20
-------
Stevens and associated (50, 51) using an improved
model of the FPD, found a linear response to SO
over the range of 10 - 700 ppb. In addition, they
reported linearity of response for H S, CH SH and CS
in the range of 10 ppb to 10 ppm. Although Stevens'
initial application of the FPD was to the direct and
gas chromatographic analysis of ppb concentrations of
SO in urban atmospheres, there appears to be little
doubt that the FPD will be equally useful for the
direct GLC analysis of ppm concentrations of sulfur
gases in krafr process emissions. The FPD appears
to have the greatest range of linear response of any
of the presently available GC detectors. Coupled
with log electronics, a single sample containing
components within a many-fold concentration range
should yield to analysis.
Stevens and co-workers (52) have assembled a dilution
system to act as an interface between sources of kraft
mill gaseous emissions and an elaborate gas chromato-
graphic system using three multiple columns and three
detectors. By selection of the appropriate emission
gas dilution, they hope to provide detailed chromato-
graphic analyses of (a) the light sulfur-containing
gases including H S, CH SH and SO by FPD, (b) any
heavier homologous mercaptans, the alkyl sulfides and
alkyl disulfides by FPD and (c) the hydrocarbons by
FID. A parallel analysis for "total reduced sulfur
gases" will be conducted with a Barton titrator. As
late as December 1969, this unit had not been tested
in the field.
The data which should be obtained by use of this
expensive and complicated analysis system will be
extremely interesting from an academic viewpoint. How-
ever, because of the expensive and complex nature of
the system, it is not planned to have two separate sets
of instrumentation to obtain simultaneous data obtained
up and downstream from available or experimental odor
reduction equipment. Up and downstream data, if obtained,
will not be directly comparable because different points
in time will be represented.
(In this regard it should be noted that continuous,
simultaneous analyses of process gases with two Barton
analyzers have revealed rapid fluctuations in both up
9-21
-------
and downstream emission concentrations in several kraft
mills. Such fluctuations will not be as readily observed
with a batch gas chromatographic technique involving
three chromatographs sampling one source at a time.)
Walther and Amberg (53) assembled a mobile gas chromato-
graphic laboratory for source gas analysis at their widely
separated company mills. The sample system includes a
ceramic type probe for installation in the process line,
a heated sample line, a heated sample conditioner which
houses the rotameter and pressure control valves, and a
vacuum pump. The sample system draws a sample from the
process stream by means of the pump, filters it twice and
delivers it to the analyzer at constant temperature and
pressure. Part of the sample flow is split at the sample
conditioner to by-pass the chromatograph, thereby reducing
the lag time to the chromatograph to about 20 seconds.
The sampling line is 1/4 inch stainless steel tubing,
electrically traced, insulated, and enclosed in a vinyl
jacket. Three sampling lines totaling 250 feet are
carried in the van. The chromatograph system consisted
of five modules: (a) analyzer system, (b) controller
section, (c) programmer module, (d) readout system, and
(e) sample system. Both thermal conductivity and flame
ionization detectors were used with three columns and
two column ovens. In addition, the mobile lab carries
equipment for sampling particulate emission. A Barton
Titrator was also available for analyzing the gases from
the recovery furnace and lime kiln.
The work of Williams and Murray (54) must be noted here. These
authors reported an enhancement of the conversion of methyl
mercaptan to dimethyl disulfide in the presence of heated
stainless steel.
Process Techniques. Walther and Amberg (55) prepared a set
of specifications for a recovery furnace process chromato-
graph and submitted them to instrument manufacturers for bid.
Beckman Instruments responded with an acceptable proposal.
The resultant process gas chromatographic unit was installed
at the Crown-Simpson kraft pulp mill at Samoa, California.
The chromatograph was designed to provide a measurement of
hydrogen sulfide, methyl mercaptan, and sulfur dioxide at
ten-minute intervals. The process chromatograph uses two
columns to permit automatic back-flushing of the heavier
flue gas constituents from one column while the three lighter
compounds of interest are being separated on the other column.
Frequent data points are obtained to guide in the operation
of the recovery furnace.
9-22
-------
Applebury (56) and Schaer developed a process gas
chromatograph utilizing a modified bromine micro-
coulometric detector. The chromatograph has the
capability of converting the output signal from
the microcoulometer to a binary signal. This
signal passes through a digital translator changing
the signal to an ASCII code, which in turn is fed to
a teletype. A punched paper tape record is produced
which serves as an input to a Hewlett Packard 2116A
computer which prints out peak areas.
Wan (57) and Schaer improved the response of this
chromatograph by changing the microtitration cell
electrolyte formulation, positions of the titration
electrodes within the microcell, substituting a GC
column packing with lower sulfur gas affinity, re-
placing all tubing and connections with Teflon or
stainless steel. Samples are analyzed within 15
minutes. The instrument performed successfully for
ten months without major technical problems.
F. Selective-Ion Electrode
Orion (59) manufactures a number of solid-state
electrodes which have high anionic selectivity and
sensitivity. Their sulfide electrode is claimed to
be free from interference from chloride, fluoride,
sulfate, carbonate, hydroxyl, and phosphate ions.
Light and Swartz (60) have studied the use of this
electrode in a system to monitor sulfide in spent
black liquor from the kraft pulping process. Megy
(61) evaluated the Orion sulfide electrode for
possible continuous determination of sulfide ion activity
in kraft process streams and effluents. It was not
found applicable, probably due to rapid deposition of
organic material on the membrane.
Despite the possible inapplicability of the sulfide
electrode for the direct measurement of sulfide in
a complex mixture such as spent black liquor, the
electrode appears to have a high potential for
measuring sulfide in process off-gases. A gas
sample could be continuously passed through a
counter or concurrent scrubbing system and the
absorbing liquid drained through a cell containing
the sulfide electrode. Changes in measured voltage
from the sulfide electrode are readily calibrated
and recorded.
9-23
-------
A line of ion-selective measurement systems designed
by Foxboro specifically for on-line industrial appli-
cations has just been announced (62). Reported capa-
bilities include: fluoride, chloride, sulfide, silver,
copper, cyanide, and a divalent cation electrode for
measuring water hardness.
Field evaluation under a variety of conditions will be
required to establish the reliability and range of
application of the sulfide electrode in the kraft pulp-
ing process. In the meantime, it is an interesting
research tool.
Infrared
Thoen and Nicholson (63) utilized a dual 10 meter path
infrared instrument in conjunction with gas chromato-
graphy to identify approximately twenty compounds in
off-gases from the black liquor recovery furnace,
multiple effect evaporators, digestors, black liquor
recovery furnace, multiple effect evaporators, digestors,
black liquor oxidation tower, dissolving vent, and lime.
kiln. Althoughi infrared identification is not recom-
mended as a primary analytical method for process gases,
it did provide excellent confirmatory identification for
gas chromatographic peaks. This must be considered a
research technique at this time. The experience of
these researchers indicated that several compounds could
be identified from a single sample with no pre-treatment
other than removal of water with anhydrone.
The identification of carbonyl sulfide in recovery furnace
gases and its increase in concentration as the furnace
atmosphere becomes reducing is considered one of their
most important findings.
9.2.2 SOURCE SAMPLING (PARTICULATES)
Isokinetic sampling is frequently considered important in
the proper sampling of particulate emissions from kraft
mill sources. However, the test procedure specified by
the Industrial Gas Cleaning Institute (71) indicates that
"most scrubbers are such that the larger particles are
collected with virtually 100 percent efficiency, while
a proportion of the particles below 5y may escape." Al-
though IGCI recommends that isokinetic sampling may be
9-24
-------
necessary to determine the concentration of dust
entering the collector, ''a simplified sampling
procedure is usually permissable for the determi-
nation of the dust concentration in the scrubber
exit gases."
It is obvious, therefore, that a rational decision
to use or ignore isokinetic sampling procedures
must be based upon a prior determination of the
particle size distribution of the specific source
gas to be sampled. "Once systematic sampling has
proved the particulate matter all to be below the
size (approximately 5 p) for which such sampling
procedure is necessary, future sampling need not
be isokinetic." (69)
If isokinetic sampling is found to be necessary,
the Western Precipitation (65), ASME Power Test
Code (66) , and IGCI (72) procedures provide
descriptions of the use of a series of nozzles of
varying diameter and a constant sampling rate to
provide the desired match between probe and duct
gas velocity. However, it is important that the
nozzle be not less than 1/4 inch diameter (66).
Duncan arid Cooper (74) in NCASI Technical Bulletin
No. 41 provide a complete review and instructions
for conducting simultaneous velocity and particulate
sampling in a duct.
It is also possible to achieve isokinetic sampling
with a single nozzle diameter by varying the flow
rate of the sample pump. This condition is most
readily achieved by use of a null probe and manometer
which measures the differential pressure between the
interior and exterior of the probe. The operator can
then continually readjust the sampling rate to main-
tain the "null" condition of no pressure differential
across the manometer. A commercially available stack
sampling kit utilizing this principle is available
(77). Unfortunately, errors have been reported of
lack of reliability of the null system in low velocity
(1000 ft/min) gas streams (69).
In 1947, Collins (64) described a sampling and analyti-
cal procedure for measuring the sodium and sulfate loss
from a recovery furnace. Since then several detailed
9-25
-------
and authoritative descriptions of acceptable
methodology have been published (65 - 75). At this
writing there is no one universally accepted technique
for determining particulate emissions from such sources
as the kraft recovery furnaces, lime kilns, or smelt
tanks. The Industrial Gas Cleaning Institute (IGCI),
founded in 1960, has developed detailed methods which
are most frequently used by equipment manufacturers
when establishing the performance guarantee character-
istics of industrial gas-cleaning equipment. These
IGCI methods have been prepared and agreed upon by
more than twenty-five of the leading manufacturers of
industrial gas-cleaning equipment.
Several recommended methods exist for collecting samples
of particulate matter from kraft mill emissions; i.e., the
1969 Oregon and Washington "Basic Considerations Re Monitoring
Programs for Kraft Mills" which utilizes a modified NCASI
sampling train consisting of a 1-gallon knockout bottle,
Greenberg Smith impingers, and a glass fiber filter in
series. The IGCI manuals (71 - 73) present vital details for
properly measuring gas velocity, temperature, water con-
tent and selecting pilot tubes and traverse patterns. A
filter or other collector is specified which demonstrates
99+ percent collection efficiency for particles of the
approximate size analysis to be encountered during the
test.
The batch sampling of solids emissions has the same
inherent limitations in process control as in the case
of gaseous sampling techniques, since the data do not
become available until it is too late to take corrective
action. Rapidly varying loss rates associated with
"normal" operating procedure as well as with process upsets
have remained unrevealed until recently when continuous
analysis techniques have been utilized. As a result,
both large and small differences between a series of
batch samples have frequently been attributed to sampling
and analysis errors rather than real process operating
variables.
Leonard (78) described a continuous particulate analyzer
for monitoring soda losses from the recovery furnace
electrostatic precipitators. He assumed a linear function
9-26
-------
between the conductivity of the aqueous collecting
media and the collected sodium sulfate. The
continuous particulate recorder trace revealed
wide and rapid fluctuations in particulate
emission which could be related to furnace
operating conditions. Having established the
authenticity of a wide range of particulate
loadings over a short time span and the rela-
tionship between the higher emission rates and
process parameters, it was possible to correct
conditions associated with maximum emission
rates.
Camacho (79) described the use of a glass
electrode sensitive to sodium ions (and other
monovalent positive ions) for monitoring
kraft mill stream soda losses. It was concluded
that the sodium electrode was as accurate as the
flame spectrophotometer for total sodium ion
determination under conditions existing in the
kraft mill streams. Although the sodium ion
electrode was used as a spot check tool, its
potential for conversion to a continuous monitor-
ing system is obvious.
Cooper and Haskell (80) used a light scattering
bolometer to measure continuously particulate
concentration in a kraft recovery stack.
Comparison of the problems associated with wet
methods for particulate measurement using the
conductivity and ion-selective electrode concepts
with the bolometric method results in a trade-off
of maintenance problems and the dynamic range of
particulate loadings which can be measured and
recorded. Sampling probes used for removing
solids from the stack should be operated
isokinetically, the probe can become plugged,
the liquid media can vary in flow rate or cease
flowing, et cetera. The light source and
detector in optical devices, such as the bolometer,
must be frequently cleaned, the light and/or photo-
sensing device can change in intensity or sensitivity
with time, and optical devices are non-specific for
sodium sulfate. Because of the non-specificity of
9-27
-------
the bolometer, it will provide assistance in a
general mill program to minimize solid losses
from the recovery furnace, but it will not provide
a direct measure of specific chemical losses.
Achinger and Shigehara (81) have developed a "guide
for selecting sampling methods for different source
conditions." These authors classified all possible
combinations of time and cross sectional variations
of the ductwork into four categories. Sampling
approaches were suggested for each category which
are dependent upon the source conditions existing
at the time of sampling. These procedures permit
collection of representative data with a minimum
of work by the sampling team.
9.2.3 SOURCE SAMPLING (NON-SULFUR COMPOUNDS)
Non-sulfur-containing compounds in recovery furnace
combustion products were examined by Hendrickson,
et al. (82) . Ten kilograms of saltcake dust obtained
from an electrostatic precipitator were benzene-
extracted and separated on an activated alumina
column. Polynuclear aromatic hydrocarbons including
benzo[a]pyrene, benzo [e]pyrene, benzotg, h, ilperylene,
chrysene, coronene, fluoranthene, and pyrene were
identified by their ultraviolet absorption spectra.
Tentatively identified were anthanthrene, anthracene,
phenanthrene, and vanillan.
9.2.4 RECOMMENDED SOURCE METHODS
Selection of Applicable Methods for Source Gas Emissions,
Selection of the optimum sampling and analysis
technique for specific sources in the kraft mill must
be based upon prior knowledge of the approximate compo-
sition and concentration ranges present and, most
importantly, the proposed use of the data obtained.
It is essential to state clearly the objectives of the
sampling program and to define the use of the data
prior to the selection of the most suitable method.
While it may be understood that the recommended
methods are to be used for research, no single method
can satisfy the requirements of the spectrum of
research problems associated with emissions from the
kraft mill.
9-28
-------
For example, a complex objective might be to
provide a complete characterization and inven-
tory of all hydrocarbons and sulfur-containing
gases in each malodorous emission source within
the mill. A research, dual column gas chromato-
graphic technique utilizing a sulfur-selective
detector and a flame ionization detector would
be required for this application. The columns
best suited for this application include Triton
X-305 (28), Dow Corning 710 silicone oil (32),
polyphenyl ether (48), and carbowax 20 M (47).
This technique will permit differentiation
between organic and inorganic, sulfur-containing
compounds.
Because of the complex nature of the usual FID
chromatogram, a "time-of-flight" type of mass
spectrometric analysis of a split stream from
the chromatographic column would provide confirma-
tory identification as well as information
describing the many presently concomitantly
present and as yet unidentified non-sulfur organic
gases. The use of "time-of-flight" mass spectro-
metric in conjunction with GLC has not been
reported in relation to the kraft mill gases. The
data thereby obtained will be of greater academic
than practical value. Infrared identification
has been used but the method has insufficient
sensitivity to detect many of the peaks. In
addition, considerable time would be required to
provide a complete analysis.
A less complex research goal would be a mill-by-
mill quantitative inventory of the five major
sulfur-containing gases designed to reveal a
range of emission concentrations from various
processes within each mill and between mills.
A sulfur-sensitive detector, either flame photo-
metric or microcoulometric, should be used in
conjunction with gas chromatographic separation.
Attention must be given to the dynamic response
range of the detector used. Concentrations
ratios among SO , H S, CH SH, RSR, and RSSR in
9-29
-------
source gas emissions may require the analysis of a
small sample volume first to obtain a quantitative
measure of the major compounds. A large sample
would then be injected, the elution of the major
compound(s) vented, and the eluent then switched back
through the detector (44) . The addition of a FID
detector would not complicate such a system and would
provide dual analysis of the organic sulfur compounds.
Process application of the FPD and MCT have been limited
due to narrow "linear" calibration (log-log) of the FPD
and maintenance of the MCT detector. The FPD can be
used only at low concentrations (less than 10 ppm,
possibly). Adjusting sample volumes to meet this re-
quirement might require a different sample volume for
each sulfur compound. The value of the MCT and FPD
would be to detect the inorganic sulfur and to determine
incomplete separation of sulfur components detected by
the FID. Research data thus obtained would be of great
practical value in relating odor emission rated to
process variables, particularly if simultaneous
samples were obtained up and downstream from odor control
equipment.
Perhaps the most useful research method for kraft mill
process odor control, (considering the present state-of-
the-art of the operation of the kraft process) would
involve continuous, real-time analysis of total reduced
sulfur (TRS) gases or the major reduced sulfur gas in
the emission source under study. Because many mills have
demonstrated wide and sudden fluctuations of sulfur gas
emissions, realtime analytical data can be most readily
correlated with the numerous process parameters already
recorded in the mill plus those which could be additionally
measured and/or recorded. For example, additional measure-
ments including flame temperature, liquor drop size, liquor
temperature, and percent black liquor oxidation would be
useful in the case of the recovery furnace.
Realtime, broad spectrum continuous analyzers are recom-
mended to achieve this objective. Considerable mill
experience is available to confirm the usefulness of this
approach. The Titrilog, as well as the Barton Model 286
and Model 400, are well suited for this work. The addition
of a pre-scrubber to remove SO , for example, provides
separation of the major non-malodorous volatile sulfur gas
from malodorous sulfur-containing gases.
9-30
-------
Mill experience with TRS-types of coulometric
analyzers has not been entirely satisfactory.
Problems have been encountered which limit the
reliable, continuous application of these instru-
ments. These major problems include (a) inadequate
probe for dust removal, (b) inability to maintain
a constant air flow rate through the coulometric
cell, (c) electronic malfunctions, and (d) unsatis-
factory state of liquid pre-filters for separating
the various sulfur-containing gases in the kraft
process emission gases.
At the risk of repetition it is implicit that the
essential objective of source sampling and analysis
must be properly identified before methods are
selected for use. Presumably, the most important
research objective of the kraft pulping industry is
to reduce to a minimum the emissions of the primary
and already identified particulate and malodorous
compounds by correlating total reduced sulfur
emissions with process variables and then confining
mill operations within a specified range of conditions.
Once the achievable reduction in emissions has been
attained by presently known control techniques and
proper equipment operation and the effect upon the
community response or ambient air quality evaluated,
then the more complex and sophisticated techniques of
Stevens, et al., (52) can be applied to define any
remaining problems. If these complex and sophisticated
analytical methods for process evaluation are used
prior to attainment of the major reductions in emissions
which can now be achieved utilizing known and proven
techniques, the acceptance of these control techniques
will be delayed because of the greater time and effort
required to obtain the detailed inventory and relate
the mass of collected data to process parameters versus
the relatively simple total reducing sulfur gas method.
Furthermore, once the known control techniques have
been applied to the process, the remaining gases will
still have to be subjected to the complex analytical
techniques to indicate the additional control methods
required to effect further emission reduction.
9-31
-------
Other Analytical Approaches. Less experience has been
obtained with the Risk and Murray UV H S analyzer (21).
The commercial availability of such an instrument is
not known. The FPD used in conjunction with preselective
filters might well provide a more reliable approach to
real time analysis than the Barton coulometric detector
because of the obvious maintenance advantages of solid
state over wet-chemical detectors. However, other
maintenance problems would be introduced such as the
flow regulation of combustion gases, but these should
be relatively minor. In the absence of extensive field
use, the FPD and UV methods cannot yet be given an un-
qualified recommendation as process monitoring or control
devices in their present state of mill experience.
9-32
-------
AMBIENT SAMPLING (G?SES)
Much of the literature published prior to 1966 (and even
some of the more recent publications) related to the deter-
mination of hydrogen sulfide, methyl mercaptan and the alkyl
sulfides and disulfides present conflicting and erroneous
conclusions. Publication of new research information since
1966 has provided numerous explanations for these previously
observed paradoxes. Thus, in 1969 one must conclude that
regardless of the scientific integrity of the investigators
who published ambient sulfur gas data prior to 1966-1968,
these data may well be in error by as much as one to three
orders of magnitude.
The primary sources of these errors may be classified as (a)
inaccurate knowledge of the odor thresholds for the malodorous,
sulfur gases, (b) acceptance of the published calibration
curve for the lead acetate tape method, and (c) the unrecognized
significance of the photodecomposition of collected cadmium
sulfide in the ppb concentration range which resulted in
losses up to at least 80 percent prior to colorimetric deter-
mination of the collected sulfide by the methylene blue
procedure.
ven as late as January 1968, explanations for anomolous field
measurements of hydrogen sulfide were partially attributed to
published hydrogen sulfide odor detection threshold concentrations
which were in error by 10-500 fold (83). Recently published
works indicate that the odor threshold for hydrogen sulfide
may be in the range of 0.4 to 4 ppb (8_4-87_, 2_) , whereas it
was previously thought to be in the range of 30-100 ppb (88, 89).
The improvement in definition of odor thresholds resulted from
the development of reliable, dynamic techniques for the pro-
duction of sub-parts per billion concentrations of gases,
critical examination of the errors associated with pre-1966
analytical methods, and the development of new analytical
techniques and instrumentation.
The lead acetate tape had been considered as a reference
procedure for the determination of the two-hour average concen-
tration of hydrogen sulfide in numerous field studies conducted
9-33
-------
spots exposed to light and laboratory air faded seriously.
They further reported that lead sulfide exposed to ozone
and sulfur dioxide faded significantly in even less time.
They concluded that the fading of the lead sulfide spots
during sampling and the interval between sampling and
analysis reduced the status of the method to a "qualitative
indicator of the presence of hydrogen sulfide, but that a
negative test was not conclusive." The confusion which
resulted from "negative" lead sulfide tape samples was
highlighted in a 1963 study in the vicinity of a kraft
pulp mill in which the odor of hydrogen sulfide was clearly
identified while at the same time negligible response was
obtained with the tape samplers (91).
Using reliable gas dilution techniques it has recently been
shown that the lead acetate tape is not discolored at 35
ppb H S (92) produced from permeation tubes (93) and that
the threshold concentration of approximately 50-60 ppb H S
is required for production of a lead sulfide color on impreg-
nated cellulose tape (94).
These data provide a sound explanation for much of the para-
doxical data provided by the lead acetate tape technique
since 1954.
The difficulty in providing rational explanations for the
ability of trained personnel to detect the odor of hydrogen
sulfide while conducting field sampling was frequently
compounded by the general agreement which was found between
the lead acetate tape method and the widely used cadmium
hydroxide slurry-methylene blue method described in 1957 by
Jacobs, et al., (95). Since these two diverse sampling and
analytical methods usually provided comparable concentration
data, it was logical to conclude that both methods were
reliable.
When these methods were applied to the calibration of gas
dilution systems designed to produce H S concentrations in
the 0.3-30 ppb range, it became obvious that either the
sampling and analytical methods were inadequate or that a
serious engineering error had been made in the design of
the gas dilution equipment (96). At this same time Sanderson,
et al.,(90) verbally presented their information describing
9-34
-------
the shortcomings of the lead acetate tape procedure at the
1965 Air Pollution Control Association meeting in Toronto.
Adams and co-workers then examined the Jacobs wet chemical
method and found that the precipitate cadmium sulfide was
photodecomposed and that the addition of 1% STRactan 10 (97)
minimized this decomposition thereby providing reproducible
data (98). The reliability of the STRactan modification
has now been confirmed in the field by the Bay Area Air
Pollution Control District (99).
The foregoing background discussion will provide a perspective
for the more detailed discussion of the many atmospheric
methods which have been proposed and used to varying degrees
for the determination of ppb atmospheric concentrations of
the malodorous, sulfur-containing gases found in the vicinity
of the kraft pulping process.
9.2.5.1 Odors
No present instrument or chemical analysis can fully replace
the human nose. Unfortunately this sense is extremely subjective
and quite variable in its response. In some instances, such as
malodorous emissions from kraft pulp mills, members of the
lay public will claim to identify the malodor. However it is
commonplace for several persons detecting the odor at the same
place and time to describe it differently(100). The quality
of an odor will frequently change with dilution as the observer
progresses away from a source. This change may be due in part
to a difference in response to the concentration gradient of
a given malodor or it may be due to the varying detection
thresholds of a number of different malodors present in a
complex mixture as exemplified by the kraft mill emissions.
The problems described in Section 9.2.1.1 apply equally as well
here.
A. Community Odor Panels
In situations where a single source apparently is responsible
for odor complaints a continuing community odor survey may be
a valuable technique to evaluate the effectiveness of odor
abatement methods. To be of value, the survey must be
9-35
-------
conducted on a daily basis over a period of years to
establish trends. The results of an occasional survey
will have no significance because of day-to-day, ground
level variations within the normal odor intensity range
for a given level of odor emission related to the influence
of meteorological variables.
The value of an organized, continuing community odor survey
is exemplified by the many years of observations by an
odor panel living in the vicinity of the Pefta Pobre kraft
mill near Mexico City (101) . The mill utilizes the
services of a large number of volunteer observers distri-
buted throughout the area of historic odor complaints.
These observers are unpaid and were primarily selected
from the group of original complainants. The observers
are furnished a weekly report card, providing spaces for
recording the time of day, the day of the week, the
observed strength of the odor, and the quality of the
odor. These cards are then returned to the mill. All
weekly records are composited and related to the sequencing
of blow operations. The weekly correlations are further
reduced to a yearly trend value relating the number of
complaints or observations of odor divided by the number
of observers reporting divided by the number of blows per
day. This evaluation program has been in continuous operation
since 1957 prior to the installation of odor control processes.
These empirical values expressing community odor have gone
from 0.7 in 1957 to less than 0.01 in 1962. This record
provides management with an objective evaluation of the
effectiveness and value of their odor control installations.
This simple technique provides evidence, albeit subjective
of the effectiveness of odor control techniques as measured
by the observers' responses.
Odor surveys have been conducted in other pulp mill communities,
but with much different objectives. A community survey in
the vicinity of Lewiston, Idaho, (102, 103) was designed to
determine the nature and extent of air pollution in the area
and to attempt an analysis of the "environmental stress of
air pollution" on a population sample. High school science
students recorded their subjective response to odors detected
9-36
-------
three times daily, morning, afternoon and evening. Since
the study was of short duration and no major mill process
changes were involved, the study merely indicated that
odors were present and that the students identified
additional community odor sources including burning garbage,
cattle odors, and commercial food processing odors.
Cederlof, et al.f (85) determined the odor threshold for
kraft mill flue gases to provide a basis for calcuations
of the dilution with air required to ensure freedom from
odor. Thirty-six subjects were tested according to the
principle of paired comparisons between test gases and fresh
air. The technique revealed that black liquor oxidation
and a ''chlorine scrubber" reduced the odor threshold of
recovery flue gas by approximately one power of 10 and by
two powers of 10, respectively. These data showed a correla-
tion between the concentration of sulfur compounds present
in the test gases and the observed odor thresholds.
Sableski (104) outlined a guide to the selection of observers,
evaluating sensitivity and making odor measurements either on
a subjective intensity scale or with Scentometers to estimate
odor intensities.
B. Scentometer.
Huey, and co-workers (105) developed an inexpensive, portable
device known as the Scentometer which has been used to
contribute greater quantitative significance to the subjective
evaluation of odor concentration by field observers. Prior
to this development in 1960, observers rated odors on some
arbitrary numerical scale (for example, 0-5) which subjectively
described their response from "undetectable" to "overpowering."
With the Scentometer an observer can provide an order of
concentration magnitude of the malodorous gas in terms of the
number of volumes of clean air required to dilute the malodor
to its detection threshold. Four dilution levels are avail-
able 2, 8, 32, and 128. The low number of dilutions are
sufficient in field application to provide rapid, inexpensive
and meaningful data in terms of the degree of odor reduction
which would be achieved by a given reduction of malodorous
emission from a known source. It is recognized in the use of
this device that variations among individual observers and the
variability of an individual with time is of sufficient magnitude
9-37
-------
that the limited dilutions provided by the Scentometer are
inadequate for field evaluations of concentration. Any
semi-quantitative use of this device would be predicated
upon knowledge and application of known principles of
sensory fatigue, individual variations in odor threshold,
and the effects of recent eating, smoking, physical condition,
etc.
9.2.5.2 Hydrogen Sulfide
A. Lead Acetate Tile
Chanin, et al., (106), suggested that ceramic tiles soaked
in an aqueous solution of lead acetate, acetic acid, and
glycerol, when exposed to outdoor air containing hydrogen
sulfide, could provide a semi-quantitative measure of
hydrogen sulfide level by visual estimate of the darkening
of the tile. Tiles were examined twice daily and the cumu-
lative darkening recorded. One of the problems encountered
was the fading of the lead sulfide color.
Gilardi and Manganelli (107) provided a comprehensive
evaluation of the influence of exposure variables upon the
developed lead sulfide color. They concluded that the tile
had an upper useful exposure limit of 8 hours and that the
tile had to be exposed in a light-proof chamber designed
to minimize air movement. The surface darkening was measured
with a reflectance attachment to a Spectronic 20 colorimeter.
They developed a quantitative expression of exposure units:
mg. x hrs.
in which there was a direct relationship between the exposure
concentration in mg/m and the hours of exposure within the
limits stated. It is not known whether laboratory evaluation
of the tiles and development of the above mathematical
relationship was based upon reliable H S concentration data.
It may be that the lead acetate tile has a response threshold
similar to that shown by the lead acetate tape and thus would
not correlate well at H S concentrations in the vicinity of
the threshold concentration for human sensory detection.
9-38
-------
B. Paint Darkening
Qualitative evaluation of atmospheric hydrogen sulfide
has been 'made by measuring the darkening of test panels
coated with lead-base paint (108) . Following 30-day
field exposures , the amount of paint darkening was
reported as a percentage decrease in light reflectance .
A method to keep the paint surface wet must be developed
if paint darkening measurements are to be at all useful
because of the significant influence of humidity upon
the rate of color development.
Filamentous growths of bacteria may develop on painted
surfaces during periods of high humidity and be confused
by the layman for hydrogen sulfide-induced paint darkening.
Mildew may be readily identified under low power magnifi-
cation or its removal by five percent sodium hypochlorite
solution.
Wohlers and Feldstein reported that the incidence of
lead-base paint darkening is time -concentration dependent
following the equation:
c = + o.ooi
where
C = H S concentration, ppm vol.
t = time, hours
Surfaces freshly painted with lead base paints appear to
be resistant until weathered for approximately ten months.
Despite the myriad variables controlling the onset of paint
darkening, H S concentrations above 50 ppb for several hours
under optimum conditions will darken paint. This reported
paint darkening threshold appears to agree with the similar
threshold reported for the lead acetate tape.
Reffner, et al. , (109) studied the H S discoloration of
exterior paints containing heavy metal salts as pigments
9-39
-------
or fungicides. An electron microscope technique was
developed which identified lead sulfide and mercuric
sulfide on the surface of discolored paint.
C. Metal Tarnishing
Wohlers and Feldstein (108) found that H S concentrations
above 3 ppb for more than 40 hours will tarnish sensitive
metals such as silver and copper. Insufficient reliable
quantitative experience has been obtained to develop meaning-
ful relationships between average H S exposure concentrations
and tarnishing. Although the National Air Sampling Network
"Effects Package" utilizes silver plated panels, no H S
concentration information is available to develop a meaning-
ful correlation between reflectance loss and intensity of
H S exposure.
Falgout and; Hardi.ng ,;(83) . descri^gd^a dynamic, sampling method
for the determination of hydrogen sulfide and methyl mercaptan
by measuring the decrease in reflectance of silver membrane
filters through which air had been drawn at a known rate
for a selected time period. The method depends upon the
reaction between metallic silver and hydrogen sulfide.
These authors suggested that their inability in 1965 to
determine hydrogen sulfide in the air of Jacksonville,
Florida, by the methylene blue method when the odor of
hydrogen sulfide was detected might be due to the presence
of interfering substances such as ozone. Based upon present
knowledge (98) it seems more reasonable to postulate that
the collected cadmium sulfide photodecomposed prior to the
determination of the sulfide by the methylene blue colori-
metric procedure.
Falgout and Harding studied the possible interference from
nitrogen dioxide, ozone, and ultraviolet light upon the
silver membrane filter. It was concluded that the silver
membrane response to hydrogen sulfide and methyl mercaptan
was not affected by other commonly encountered pollutants
and that the filters could readily be protected from ultra-
violet light and atmospheric particulates by wrapping the
9-40
-------
filter with black tape and placing a cellulose filter
ahead of the silver membrane filter. As applied by the
authors, air was sampled at the rate of 0.9 1pm and
provided 23-hour average concentrations of sulfide and
mercaptan reported as AR/m .
It appears that further evaluation of the silver membrane
technique should be undertaken under controlled conditions
in which AR is related to known concentrations of H S
generated by the permeation technique.
D. Chemically-Treated Filter Tape
Sequence samplers using chemically-impregnated tapes have
been used widely to determine average ambient air concentra-
tions of selected compounds for designated periods of
time—for example, two hours.
In the most popular, commercially available tape samplers,
air is drawn through a lead acetate-impregnated tape for
a predetermined time, leaving a darkened area when hydrogen
sulfide is present in the air. The exposed tape is then
returned to the laboratory and optical density determined
(110) . The optical density of the spot was reported to
be proportional to the hydrogen sulfide concentration.
Two-hour average hydrogen sulfide concentrations have
'been,.determined in many localities using the AISI sequential
ttap«^irgamp;ler''r (111) or similar instruments (112-114) . In
most field applications there is a variable time lapse
between the first sample on a roll of tape and the final
sample several days later when the tape is returned to the
laboratory and the density of each spot photometrically
determined. There is conflicting opinion concerning the
stability of the lead sulfide color with storage either
on the roll in the tape sampler or subsequently in the
laboratory when analysis is delayed or when the tapes are
exposed to air or light (90) , (103).
Subsequently, improved sequence tape instrumentation became
Available''which provided instantaneous photometric read-out
%'S^^^^^l^fibping spots throughout the sampling period (111)
or a single, automatic read-out upon completion of the
9-41
-------
sampling period (114). Short-term fluctuations in
H S concentration are then calculated from the slope
or the recorder tracing. This immediate read-out should
minimize possible fading of the lead sulfide spots, since
no more than two hours of storage is involved. This
approach, however, has an inherent source of error because
of the reported instability of the PbS color in both sun
and laboratory light (90, 115).
According to the instrument manufacturer's calibration
curve, the minimum two-hour average HS concentration
detectable by the lead acetate tape method is approxi-
mately 1.0 ppb (111). At least two laboratories, however,
have been unable to produce lead acetate tape darkening
until minimum threshold concentration of 50-60 ppb H9S has
been exceeded irregardless of the exposure time (92, 94)
utilizing a well-designed gas dilution panel and a H S
permeation tube, respectively. Therefore, it is theorized
that the original calibration curve was developed by either
(a) adding the total quantity of H S present in the total
volume of air to be sampled in a 2-hour period as a single
concentrated slug and then passing air through the tape
for 2 hours or (b) inadequate dilution techniques were
available for use in 1954.
The 1963 report (91) that lead acetate tape gave negligible
response when the odor of hydrogen sulfide was detected was
undoubtedly due to the recent observations that the spots
fade on storage and under light, that the color formation
is modified when sulfur dioxide is present, and lead acetate
tape will not discolor until at least 50-60 ppb hydrogen
sulfide is present. Although the earlier literature
reports that the odor threshold for hydrogen sulfide is
in the order of 30-100 ppb, more recent studies utilizing
more refined techniques for production and chemical deter-
mination of low concentrations indicate that the odor
threshold for hydrogen sulfide may be in the order of
0.4 to 4 ppb.
Pare (115) confirmed many of the Sanderson, et al. (90)
observations about the inadequacies of the lead acetate
tape and suggested the use of a mercuric chloride impreg-
nated tape. The resulting spots were reportedly stable
9-42
-------
even when exposed to 10 ppm of ozone for three days.
Fare's mercuric chloride tape was complicated by the
need to develop the color of the spot in the laboratory
just prior to photometric measurement. Also, mercuric
chloride corrodes the metal parts of presently avail-
able tape samplers. Substitution of more resistant
metals such as stainless steel might eliminate this
problem, but raise the cost of instrumentation.
Hochheiser and Elfers (116) have devised a one-step
mercuric-type tape which eliminates the need to develop
the mercury sulfide in the laboratory prior to photo-
metric measurement. This improved technique appears
promising, but will require additional laboratory and
field testing before adoption as a "standard" method.
E. Adsorption Sampling
—^ __^ __. _^ j__.__
beads treated with KHSO and Ag SO .
sulfide was dissolved with a solutio]
Buck and Gies (117) proposed collecting atmospheric
hydrogen sulfide in dry sorption tubes packed with glass
The collected
tution of ZnCl in concen-
trated hydrochloric acid and the liberated hydrogen
sulfide determined by the molybdenum blue method. The
hydrogen sulfide test atmospheres were in the range of
200-300 ppb, well above values normally found in the
atmosphere.
Although the authors carefully considered a wide variety
of possible interferences from other air pollutants, the
validity of their hydrogen sulfide test atmosphere was not
adequately established. Air oxidation, light sensitivity,
storage delays, etc. which have been shown to affect adversely
cadmium sulfide (98) and lead sulfide (90, 115) were not
evaluated as possible sources of similar errors when collecting
hydrogen sulfide with the silver sulfate sorption tube.
A relative detection limit of 0.009 mg H S/m (6.5 ppb)
for a 30 minute-sample and 0.02 mg H S/m (14 ppb) over a
15-minute sample cycle was claimed for the Ag SO sorption
method. Extrapolated to a 2-hour midget impinger cycle,
this would be equivalent to a sensitivity of 2.2 ppb H S.
9-43
-------
Buck and Gies concluded that the above sensitivities were
"below the odor threshold (approximately 0.05 mg/m )."
This conclusion is questionable, since the odor threshold
for hydrogen sulfide is actually in the order of 0.4-4
ppb (0.00056-0.0056 mg/m ).
Cadmium Hydroxide-Methylene Blue
Sequence samplers using absorption solutions in manifolded
impingers have been used to determine average ambient air
concentrations of selected compounds for designated periods
of time; for example, two hours.
Because sulfide standards have been observed to decrease
rapidly in concentration in dilute alkaline solution,
many absorption solutions have been examined in an attempt
to minimize this loss and permit the subsequent color-
metric analysis of the collected sulfide. An excellent
review covering the literature to 1957 has been published
by Jacobs, et al. (95). Sulfide stablization techniques
have involved the precipitation of metal sulfides with
zinc (118) and cadmium (119). Jacobs, et al. reported
that a cadmium sulfate-sodium hydroxide absorbant was
preferable to zinc acetate or ammoniacal cadmium chloride.
In the Jacobs method, hydrogen sulfide is absorbed in
an aqueous, alkaline suspension of cadmium hydroxide
prepared by dissolving 4.3 grams of cadmium sulfate
(3CdSO .8H 0) and 0.3 gram of sodium hydroxide in 1 liter
of distilled water.
Jacobs et al., emphasized the problem of the "oxidation"
of sulfides by the relatively large volumes of air which
were aspirated through an impinger and suggested that
"oxidation" was minimized by using the alkaline cadmium
hydroxide absorbing mixture. Recently, chemists of the
Swedish Air and Water Laboratory (120) have reported that
the zinc slurry is superior to the widely accepted cadmium
hydroxide slurry. This report appears to contradict the
earlier data of Jacobs/ et al./and Marbach and Doty. Thus
it appears necessary to re-examine the zinc absorbing
solution in view of the recent improvement in the cadmium
hydroxide slurry sampling technique (121).
9-44
-------
Since the cadmium hydroxide slurry-methylene blue method
for the determination of hydrogen sulfide is commonly
used and Adams, et al. (122) were unable to obtain
agreement between this method and the coulometric titration
method, the former method was intensively investigated.
This study revealed losses of 30-80 percent when collecting
ppb concentrations of hydrogen sulfide in cadmium hydroxide
suspension in midget impingers and determining the collected
sulfide by methylene blue.
The methylene blue color development is dependent upon
the formation of methylene blue from the reaction between
sulfide and p-amino-N,N-dimethylaniline in the presence
of ferric chloride. The molar absorptivity is reported
to be about 34,000 in range of 5-50 pg S~ per 100 ml,
thus providing an exceptionally sensitive system. The color
development is influenced by temperature, time and acidity.
However, the colorimetric method is quite reproducible
using ordinary laboratory precautions and was not related
for the sulfide losses observed.
The possibility that the observed loss could be related
to low collection efficiency had been eliminated by the
work of Bostrom (123) wherein the collection efficiency
for isotopic H S* in cadmium hydroxide suspension was
found to be in the range of 93-98 percent. The CdS* _
collected in the absorption solution was oxidized to S*O
with hydrogen peroxide in slightly acid solution. Unfortu-
nately, the analytical method did not provide any infor-
mation concerning the fate of the S* during aspiration
and storage, since analysis was based upon the amount of
BaS*O. precipitated from the S*O produced from the complete
oxidation of CdS*.
A review of the earlier literature showed that Marbach
and Doty experienced the lowest sulfide losses when the
cadmium was either completely precipitated with an equimolar
addition of NaOH (pH 9.6) or when an excess of NaOH was
present (pH 13.0). Marbach and Doty used the equivalent
of 4.3 g of 3CdSO .8H 0 and 1.3 g NaOH to prepare their
fully precipitated CdTOH) sulfide collection media.
Subsequently, Jacobs, et al., recommended only 0.3 g NaOH
per liter (pH 7.5) .
9-45
-------
Since Jacobs, et al., did not discuss the reasoning behind
their reduction of the 1:1 molar ratio of Cd/2NaOH—recom-
mended earlier by Marbach and Doty—to the Jacobs ratio
of 1:0.25, a series of Cd/2NaOH ratios between 1:0.25
and 1:1.3 were prepared to re-examine the influence of
alkalinity. Samples of higher pH gave consistently
higher sulfide recoveries, however, the improvement was
not considered to be significant. Variable losses of
30-70 percent were observed over the pH range of 7.5
to 12.0.
Since Jacobs, et al», (95) had suggested that sulfide
losses were caused by oxidation, replicated impingers
containing 15 ml of Cd(OH) suspension and added sulfide
were purged with nitrogen, air/and oxygen. Sulfide losses
were not significantly greater for the air and oxygen
treatments than for the nitrogen treatment, indicating
that the observed sulfide losses were not related to
oxidation. However it was observed that the sulfide loss
appeared to be related to the length of exposure to labora-
tory light. The data indicated a possible photodecomposition
of the sulfide. A parallel study of a number of common
antioxidants and protective colloids showed that sulfide
collected in a cadmium hydroxide slurry containing 1 percent
STRactan 10 (98) significantly improved the sulfide recovery
in light and dark.
The modified cadmium hydroxide slurry with 1 percent added
STRactan provides reasonable protection from photodecomposition.
Recoveries are in the order of 80 percent +_ 3 percent in the
low parts per billion concentration range. This method has
been field tested (124) and adopted as standard by the Bay
Area Pollution Control District (99). An extensive eval-
uation of the effect of possible interfering compounds is
underway and was reported during 1969 (125). The method is
being considered for adoption by the Intersociety Committee.
Prescher and Lahmann (126) have also discussed the methylene
blue colorimetric determination of hydrogen sulfide in ambient
air. They concluded that methods available in 1966 for the
determination of low concentrations of hydrogen sulfide were
inadequate. The lead acetate and silver nitrate impregnated
tapes were deemed neither sufficiently sensitive nor
accurate. They recommended collecting hydrogen sulfide in
9-46
-------
cadmium hydroxide suspension in the dark from the moment
of air intake until the analysis was accomplished. These
authors also compared the Buck and Stratman (127) molybdenum
blue method with the Mecklenburg and Rosenkranzer (128)
methylene blue method for determination of hydrogen
sulfide and concluded that the reaction of hydrogen sulfide
with methylene blue produced a more intense color and was
therefore to be preferred.
G. Fluorimetry
Andrew and Nichol (129) described a continuous analyzer
for hydrogen sulfide. Hydrogen sulfide quenches the fluor-
escence of tetra-acetoxymercuri-fluorescein linearly between
5 ppb and 1 ppm. The short-term sensitivity of the instru-
ment is approximately 5 ppb. This reagent appears to have
useful application in a continuous, automatic colorimetric
analyzer for H«S. However, extensive studies would first
be required to establish possible interferences from other
air pollutants and to confirm the reported sensitivity.
H. Selective Ion Electrodes
At the present time more than 20 ion-selective electrodes
are commercially available and several are being adapted
for the continuous monitoring of flowing streams. Swartz
and Light (130) have used three electrodes—fluoride,
sulfide, and cyanide—as detectors for process monitoring
instruments for use in the pulp and petroleum industries.
There is insufficient evidence to establish the limits of
sensitivity and hence the potential usefullness of the
sulfide electrode for atmospheric monitoring, although
considerable progress has been reported in the application
of the fluoride electrode for atmospheric monitoring in the
ppb concentration range in the vicinity of alumina reduction
plants (131). A study of the possible application of the
sulfide electrode for atmospheric monitoring is recommended.
SI.2.5.3 Methyl Mercaptan
A. Colorimetric
The odor threshold for methyl mercaptan is reportedly in
the range of 0.3-5 ppb (86, 87). Mercaptans in the air are
9-47
-------
absorbed in an aqueous solution of mercuric acetate-acetic
acid in midget impingers (132).
The spectrophotometric method for mercaptans depends upon
the reaction between N,N-dimethyl-p-phenylenediamine and
mercaptan in dilute nitric acid and in the presence of
ferric chloride (133). Moore, et al.,(132) reported that
hydrogen sulfide did not interfere when present in the
range of 0-150 yg. Figure 9-1 compares the absorbance of
the complexes produced by hydrogen sulfide, mercaptan, and
alkyl disulfides with the "Jacobs" and "Moore" reagents.
From these absorbance curves it is apparent that (a) methyl
mercaptan will interfere with the "Jacobs" colorimetric
determination of H S by approximately 5 percent on a molar
basis, (b) the potential interference from dimethyl disulfide
in the Jacobs method is negligible, (c) hydrogen sulfide will
not interfere with the "Moore" colorimetric determination
of methyl mercaptan and (d) dimethyl disulfide will interfere
with the "Moore" colorimetric method approximately mol for
mol if retained in the impinger by the absorption solution.
Fortunately, dimethyl disulfide is only partly retained in
the mercuric acetate=acetic acid absorbing media and* therefore,
is not a practical source of interference.
This method is intended for the determination of mercaptans
in the range below 100 parts per billion. For concentration
above 100 ppb the sampling period can be reduced or the liquid
volume increased either before or after aspirating. The
minimum detectable amount of methyl mercaptan is 0.04 yg
per ml (86) in a final liquid volume of 25 ml. When sampling
air at the maximum recommended rate of 1 liter per min. for
2 hours, the minimum detectable mercaptan concentration is
2.0 ppb (3.9 yg methyl mercaptan per cubic meter at 76
cm mercury and 25°C).
The N,N-dimethyl-p-phenylenediamine reaction is also suitable
for the determination of other sulfur-containing compounds.
including hydrogen sulfide and dimethyl disulfide. The potential
for interference from these latter compounds is especially
important, since all of these compounds commonly coexist in
certain industrial emissions. Appropriate selection of the
sample collection and color formation conditions minimize the
interference from hydrogen sulfide and dimethyl-disulfide.
9-48
-------
VO
0.3
0.2
0.3
25 ug H2S
100 ug CH3SH
103 ug DHDS
0.1
500
600
700
-I
800
•
•
•
•
•
•
•
.*-v
\ / x '•
v/ \ \
0.2
0.1
400
\ \
\ \
\ \
\
"MOORE"
500
600
700
tnu
(flu
FIGURE 9-1. ABSORBANCE - "JACOBS" AMD "MOORE" REAGENTS
-------
Hydrogen sulfide, if present in the sampled air, may cause
a turbidity in the sample absorbing solution. This precipitate
must be filtered before proceeding with the analysis. One
study showed that 100 yg H S gave a mercaptan color
equivalent to 1.5-2.0 yg mercaptan (132), Another study
reported no absorption at 500 my in the presence of 150 yg
of hydrogen sulfide (136).
Approximately equimolar response is obtained from the
hydrolysis products of dimethyl disulfide—the extinction
coefficient for the amine-mercaptan reaction produce being
4.4 x 10 and for the amine-dimethyl disulfide reaction
product being 5.16 x 10 (92). In practice, however, the
collection efficiency for dimethyl disulfide in aqueous
mercuric acetate is low and the actual interference is
negligible. Sulfur dioxide up to 250 yg does not influence
the color development even when sampling a test atmosphere
containing 300 ppm SO-.
Nitrogen dioxide does not interfere up to 700 yg NO when
sampling a test atmosphere at 6 ppm. Higher concentrations
of NO caused a positive interference when mercaptans were
present but no interference in the absence of mercaptans.
The supply of mercuric acetate must be free of mercurous
ion. If mercurous ion is present turbidity will result when
the chloride ion-containing reagents are added in the last
step of the analytical procedure.
The coefficient of variation for four mercaptans from methyl
to hexyl mercaptan ranged from 0.0-2.6 percent (132). The
coefficient of variation increased with increasing molecular
weight of the mercaptans.
In several instances (133, 134) interferences have been
reported from unknown compounds when using the method in
the vicinity of kraft mills. In one of these, formation of
a light-colored precipitate was reported. The apparent
interference was not delivered due to emissions from the
kraft mill since in most instances the wind was blowing from
a nearby community toward the samples when the precipitate
was noted. Cause of the problem is being investigated.
The method is being considered for adoption by the
Intersociety Committee.
9-50
-------
9.2.5.4 Alkyl Sulfides and Disulfides
A satisfactory analytical method for these compounds which
is sensitive to concentrations usually found in the ambient
air is not available at this time.
9.2.5.5 Sulfur-Containing Gases - Total or by Separation
A. Conductivity
Conductivity instrumentation, such as the Thomas Autometer (55),
designed for monitoring sulfur dioxide by measuring the increase
in electrolytic conductivity of a dilute hydrogen peroxide-sulfuric
acid absorption media, can be used for hydrogen sulfide by first
passing the air sample through an oxidizing furnace to convert
the hydrogen sulfide to sulfur dioxide (138). The sample is then
analyzed in the usual manner by continuous or batch conductivity
measurements. If sulfur dioxide is also present in the atmosphere,
correction must be made by simultaneous analysis of oxidized and
unoxidized samples or by alternating a single air stream first
through the furnace to the Autometer and then directly to the
Autometer. This technique has not been used extensively because
of the obvious equipment complications and the potential errors
from many common interfering substances in the atmosphere which
would either increase or decrease the reagent conductivity (139).
B. Coulometry
Coulometry is based upon the principle of electrically generating
a selected titrant (ion or element) in a titration cell. The
current required to generate sufficient titrant is a linear
measure of the concentration of reactable compounds in the
gas sample. In practice the titration cell has two sets of
electrodes—a generating pair and a reference pair. A constant
low level of titrant is continuously generated to produce a
"zero level" on the instrument. When reactable compounds enter
the cell the available titrant is reduced. The associated
feedback amplifier responds to the change in sensed titrant
level and generates sufficient additional titrant to maintain
the "zero level" concentration. The additional generating
current is related to the reactant by the following equation:
Microequivalents = Q coulombs x 10
(96,000 coulombs/equivalent)
9-51
-------
The following equation is used to calculate the concentration of
reactant when using a recorder of known characteristics to follow
a coulometric titration:
—? 6
Microequivalents = V x S x 6 x 10 x A x 10
R x 96,500
where V = mV/in. recorder sensitivity
R = ohms resistance of the coulometer range ohms switch
S = chart speed in min/in.
2
A = area under the titration curve, in.
Instrumentation for coulometric titration with electrolytically-
generated bromine has been used for the determination of bromine-
oxidizable sulfur gases (140). The Titrilog (22, 23) embodying
this principle has a sensitivity of approximately 100 ppb. The
sensitivity of the Titrilog was improved approximately 10-fold
to 10 ppb by addition of a "R-C" network (141, 142).
The barton "Titron" Model 286 (25) represents a similar instrument
using bromine coulometry and solid-state electronics.
This instrument has a limiting sensitivity of approximately 25
ppb H S. Thoen (27) has reported a 5 ppb sensitivity for a
"total sulfur" in the ambient air with this instrument by substituting
a Leeds and Northrup Model H recorder for the API recorder provided
with the Barton 286.
Microtitration cells utilizing silver-silver chloride electrodes
have been used for coulometric analysis of hydrogen sulfide and
mercaptans (143). The cell will not respond to SO2 or alkyl
sulfides and disulfides. The sensitivity of this .detector'is
reported to be approximately 100 ppb.
An iodine, microtitration cell (MCT) (41, 42) and a Dohrmann
coulometer (144) have been used for the analysis of sulfur-containing
pesticides which have first been separated by gas chromatography
and then oxidized to S0? or reduced to H S in an appropriate
furnace (138, 145, 149). This detector could also be used for
the direct analysis of SO in air. The sensitivity of this iodine
microtitration cell is in the order of 100 ppb for direct atmospheric
analysis. The cell response is relatively slow and the electrolyte
is too short-lived for practical application.
The basic design of the iodine cell was modified and converted
to bromine coulometry by Adams, et. aL, (150). This microcell has
9-52
-------
an instantaneous sensitivity of approximately 3 ppb for
hydrogen sulfide, which approaches the sensory detection
threshold. The cell has been calibrated with permeation
tubes (93).
Selective pre-filters have been developed for use in sequence
ahead of the MCT cell to provide a separate analysis for sulfur
dioxide, hydrogen sulfide, mercaptans, and alkyl sulfides
and disulfides (151) . Table 9-1 describes the series of pre-
selective filters which provides the best compound separation.
The filters are preceded by an all plastic and stainless steel
electrostatic precipitator to prevent build-up of particulates
on the face of the impregnated membrane filters. The electro-
static filter must be operated at a sufficiently low voltage
to prevent ozone production which would yield a negative
response from the MCT.
The filters must be placed in the order shown in Table 9-1
for optimum results. When mercuric nitrate or silver nitrate
is used to retain H S or CH SH, the nitric acid reaction product
interferes with the MCT response. This interference is
eliminated by using a bicarbonate backup filter.
T A B L E 9-1
SELECTIVE FILTRATION SERIES-PERCENT RETENTION
SO H S CH SH DMS DMDS
ft £ -J
1. No filter
2. NaHC03
3. Lead acetate
4. Mercuric acetate
5. Hg acetate + tar-
tar ic acid and
NaHCO 100 100 100 85 10
6. AgNO +H BO +
tartaric acid and
NaHC03 100 100 100 100 100
9-53
0
100
100
100
0
10
100
100
0
4
4
100
0
5
5
5
0
3
5
3
-------
In an automatic, sequential sampling system, air is sequentially
sampled through a series of filters and then passed through the
bromine MCT, thereby providing a stepwise recording of the con-
centrations of the various sulfur-containing gas fractions
present in the air. A typical stepwise analysis for the five-
gas mixture is shown in Figure 9-2. The pre-selective filter-
bromine microcoulometric techniques and the STRactan-cadmium
hydroxide-methylene blue techniques were compared in the field
near a kraft pulp mill. Excellent agreement was obtained for
hydrogen sulfide (152).
A study of the break-through or life expectancy of each of the
five filters for five sulfur gas types has been completed (153)•
The data indicate that these filters have a useful life of
at least 24 hours at concentrations well above those which
have been observed in previous field studies. Additional
work will be required to determine the possible effects of
other common air pollutants on the pre-selective filters.
The small plastic precipitator could be a source of contami-
nation and possibly a maintenance problem. More work is needed
to verify the separation of sulfur compounds in the presence
of other non-sulfur compounds. Also, some work should be
conducted to determine if there is a relationship between
particulate matter and odor. Does particulate matter from
the kraft process actually act as a carrier for malodorous
compounds? If this is true, prefiltration of samples could
give erroneous results.
C. Flame Photometry
A flame photometric detector (FPD) for the gas chromatographic
analysis of sulfur and phosphorus compounds was described by
Brody and Chaney (154). In its original application this
detector was attached to the exhaust of a chromatographic
column. The flame is viewed through selected optical filters
(394 my for sulfur compounds) and the emission is sensed with
a photomultiplier tube. Applications have been suggested
for pesticide residue, air and water pollution process control,
and natural gas (155).
Adams (156) suggested that "it should be possible to use this
detector for the direct analysis of the atmosphere for total
sulfur gases." Harding (157) reported varying detector response
to CH SH and H S. The sensitivity of his detector appeared to
be in the range of 50-100 ppb.
9-54
-------
Total Sulfur Gases
5-Conponent Nliture
Mixture
minus
S02 & H2S
H2S, CH3SH & DMS
Hg(N03)2+tartar1c
AgN03+H3BO,+tartar1c
z: No filter
add and NaHCO
-. acid and NaHCO
FIGURE 9-2. STEPWISE SEPARATION AND ANALYSIS OF 5-COMPONENT SULFUR-CONTAINING GAS MIXTURE
-------
Approximately two years later, Stevens and co-workers
(50) reported that an improved FPD could be used for the
direct analysis of volatile sulfur compounds in the
atmosphere. The continuously sampled air is passed
through a hydrogen-rich flame which is viewed at 394 my
by a photomultiplier tube. The detector has a reported
specificity ratio for sulfur to non-sulfur compounds of
40,000:1 and a sensitivity to sulfur dioxide down to
5 ppb. Selective scrubber systems including aqueous
and impregnated filters were used to remove quantitatively
one or more of several sulfur compounds from atmospheric
samples and thus make the detector more specific for
an individual sulfur compound. This research is
discussed in detail in the section on sampling and
analysis of gases from sulfite mills.
D. Long Path Infrared
Intramolecular bonding may also be studied by infrared
analysis techniques. This is probably the least sensitive
of the techniques discussed. A multiple-reflection gas
cell of 10-40 meters path length would have a sensitivity
above the ppm level. The Franklin Institute 430 meter
infrared gas cell used in the study of the complex
photochemical reactions of the Los Angeles-type smog
has a sensitivity of approximately 100 ppb and a price in
excess of $25,000 (158). Infrared instrumentation
is considered to be the least practical of the methods
described for direct, automatic air analysis.
E. Plasma Source Emission Spectrometry
McCormack et al., (159) have reported a sensitive emission
spectrometric detector with excellent selectivity for
certain chemical bonds including C-S and C-N. This detector
was successfully used by Bache and Lisk (160) for the
gas chromatographic analysis of organo-phosphorous insecti-
cide residues. Characteristic spectral lines for these
and other organic bonds produced in a microwave-excited
argon plasma are measured in the ultra violet light region
using a grating spectrometer. Moye (161) increased the
sensitivity of this detector. Specific instrumentation
utilizing this detector is not commercially available.
9-56
-------
An automatic instrument probably could be constructed using
a relatively low-cost multi-channel quantometer-type
spectrometer by substituting a microwave-excited argon
plasma emission source for the usual spark or arc source.
The airborne sulfur-compounds would first have to be
collected and concentrated in a liquid absorbant and then
periodically injected into the argon plasma, The concen-
tration step is required to separate the sulfur compounds
from air since the argon plasma will not form in the
presence of air. The sensitivity of this technique for
C-S bonds should approximate 200 ppb, if present for 30
minutes.
F. Gas Chromatography
Columns. The use of gas chromatography for the separation
and determination of individual compounds from the kraft
pulping process has progressed through several generations
of detectors and column packing with ever increasing
sensitivity and specificity since its first applications
to the analysis of kraft source gases (162-164). Williams
(165) used GLC analysis of ambient air samples to identify
more than 30 organic compounds including dimethyl disulfide.
The air sample was first dried by passing through a drying
agent and then concentrated on a cooled, short section of
stainless steel tubing packed with same column packing used
for separation. The samples were later desorbed and analyzed
with FID and EC detectors. Although detector technology
provided dramatic improvements in sensitivity and compound
specificity between 1957 and 1968, the direct analysis of
ambient air concentrations of sulfur gases has been delayed
by a lack of non-reactive partition liquids and column
packings (166).
Stevens and co-workers (51) reported early in 1969, two
techniques for the direct gas chromatographic analysis of
sulfur gas mixtures in the low ppb range normally encountered
in the ambient air. The first method involves the use of
"differential response chromatography" (168). In this technique
low concentrations of the sulfur gases to be determined are
added to the chromatographic carrier gas by passing the carrier
gas over appropriate permeation tubes (93). In this manner
a frontal elution takes place and the eluate composition assumes
a steady state value. Unknown samples introduced into the
same column will emerge and generate signals corresponding in
elution time to the minor component, but in magnitude and
9-57
-------
algebraic sign to the difference in concentration from the
steady stream. Using this technique, Stevens, et al. achieved
a chromatographic separation of the determination sulfur
dioxide from other sulfur gases at levels as low as 20
ppb.
The second, and more useful, method involves the
elimination of sorption or reaction in:the chromatographic
column and column packing. Empirical studies disclosed
that polyphenyl ether coated at 5 percent on 30 - 40
mesh Teflon, and containing 0.05 percent phosphoric acid,
permitted passage and separation of the highly reactive
sulfur-containing gases down to concentrations of 10
ppb.
Unfortunately this work has not been substantiated at
the low levels by other investigators. Further work
appears necessary to confirm this pioneering effort.
Thermal Conductivity. Neither hot wire nor thermister
thermal conductivity (TC) cells had adequate sensitivity
to detect compounds in the sub parts per million concen-
tration range.
Flame-Ionization Detector. Later when the flame ionization
detector (FID) was developed it became possible to obtain
a direct quantitative determination of the hydrocarbon
sulfur compounds present in kraft source gases without
resort to prior sample concentration. The FID is extremely
sensitive for the analysis of hydrocarbons. The detector
response is proportional to the number of carbon atoms
in the molecule. Unfortunately, this detector responds
only weakly to inorganic sulfur compounds such as hydrogen
sulfide and sulfur dioxide. Bellar, et al., (169) have
studied the sensitivity limits of the FID for the direct
analysis of hydrocarbons in the atmosphere. Feldstein,
et al.,(170) established a comparative response factor
of 0.3 for methyl mercaptan as compared with methane.
These two values indicate that the FID should have a
limiting sensitivity of 12.5 ng. CHJSH for direct atmospheric
analysis.
Since the FID has a greater response for hydrocarbons
than for sulfur-substituted compounds of equivalent
carbon content, these compounds must be separated prior
to FID analysis.
9-58
-------
Using the FID, Thomas (171) found the usual methyl mercaptan
and sulfides as well as n-propyl, isopropyl, and ethyl mercaptans
and sulfides in blow and relief gases. Unfortunately, the FID
does: not respond to H S or SO and shows even greater sensitivity
for non-sulfur containing hydrocarbons.
Electron Capture. An obvious extension of this work was
the application of the highly sensitive FID to the gas
chromatographic analysis of ambient air for hydrocarbon
sulfides as well as evaluation of the electron capture
(EC) detector for all sulfur-containing gases. Adams, et. al.,
(172) reported on the sensitivity of these detectors for sulfur-
containing compounds. The EC detector was unsatisfactory
because of its loss of sensitivity when in contact with water
vapor and its apparent temporary poisoning by methyl mercaptan.
Coulometric. Microcoulometric detectors (MCT) including
silver-silver chloride (143) , iodine (41, 42) and bromine
(150) can be used in conjunction with a polyphenyl ether
column (51) for the selective determination of sulfur-
containing gases. The microbromine cell is the most sensitive
of the three and responds to all of the major sulfur gas emissions
from the kraft process, whereas the response of the silver-
silver iodine cell is limited to mercaptans.
Eads and Cooper (167) have reported that "odor producing
sulfur compounds . . . including sulfur dioxide, have been
detected at very low levels. . .by modifying a chromatograph
coupled to a microcoulometer." The primary difference between
this system and those previously reported by others (51, 166) appears
to be in the use of a sample concentration step wherein the air
is drawn through an impinger containing methanol. The introduction
of a sample concentrating step wherein the absorbing media must
be "measured, weighed and proper microliter quantities of methanol
then injected into the system" appears to overly complicate
the technique without achieving any greater sensitivity than is
presently possible. Even the claimed sensitivity is subject to
question since the GC column was 10 percent Triton X-305 on
Fluoroport T which has previously been shown to retain appreciable
quantities of sulfur-containing compounds (51).
Flame Photometric Detector. An improved Brody-Chaney flame
photometric detector (FPD) {154) which is highly sensitive
and specific for sulfur containing compounds at 394 my, was
used by Stevens, et al./ffjl) in both methods for "direct" and
"differential" analysis of sulfur compounds in the atmosphere.
9-59
-------
This detector has a linear response over a concentration range
from 10 ppb to 10 ppm. Stevens reports that the direct,chromato-
graphic technique has been automated and that air samples are
periodically obtained with a rotating 6-port valve. Their
present objective is to determine the ratio of sulfur dioxide
to other sulfur containing gases in the atmospheres of urban
and pulp mill environments.
The FPD must still be subjected to a critical evaluation
of the possible interference from other air pollutants.
Solid-state Electrochemical Detectors. Bechtold (173) used
the solid-state electrochemical cell Pt/Ag/AgI/Ag2S/Pt to
measure concentration changes in sulfur- and halogen-containing"
compounds in a carrier gas stream. Sulfur and halogen compounds
were., first oxidized in a combustion furnace containing platinum
at 800°C and then passed over the electrode surface within an
operating temperature range of 200 - 420° G. The electrode response
was linear over at least four orders of magnitude and had a
detection limit of approximately 1 nanogram for CS,,. Detector
response was not affected by overloading.
This electrode was initially used as a gas chromatographic
detector for pesticide analysis. Because of its sensitivity
and specificity, this electrode has a potential use as a
continuous detector for total atmospheric sulfur gases, or
as a stepwise sulfur compound class analyzer using pre-
selective filters. Because the detector is solid-state,
the problems associated with conventional coulometric detectors
having liquid electrolytes will be eliminated. However, other
problems may develop under the application proposed above.
9.2.5.6 Sulfur Dioxide
Both continuous and batch sampling methods are available for
sulfur dioxide concentrations which are experienced in the
ambient air. These will be discussed in detail in Section 9.3.4.
9.2.6 AMBIENT SAMPLING (PARTICULATES)
9.2.6.1 Dustfall
This technique is intended for the collection of settleable
particulates from the atmosphere and the subsequent character-
ization of the collected material (70, 174, 176). ASTM, APCA,
9-60
-------
and NCASI have similar methods for this technique. Particulate
material which is of a particle size and density which will
settle by gravity into an open-top container is usually collected
over a 28-day or one-month period. The container and contents
is then transported to the laboratory for weighing and analysis.
The analytical procedures which are most frequently used in
evaluating the collected material in the vicinity of kraft
pulp mills include the determination of pH, total weight, total
water-soluble and benzene-soluble material, total volatile and
non-volatile matter, sodium, calcium, sulfate, and chlorides.
When dustfall is sampled and analyzed over an extended period
of time and from an adequate number of representative sampling
sites the relative contribution of settleable material from a
kraft pulping operation and other segments of the community
activities can readily be seen from monthly isopleths of each
measured component or characteristic of the dustfall. A
typical evaluation of the relative contribution of a kraft
mill and the community to dustfall was reported by Adams and
Koppe (175.) . Isopleths of the average values for 15 sampling
sites for each of 13 components determined in the collected
dustfall revealed the existence of several significantly different
fallout patterns. Similar patterns were found for sodium,
sulfate, soluble solids, ash, and pH. Different patterns
were observed for ammonia, nitrates, calcium, insolubles,
insoluble ash, loss on ignition, phosphate, and chloride.
Duncan (70) has provided a comprehensive description of the
manner in which to establish a dustfall survey within a kraft
mill community.
Studies on the influence of the design of dustfall collectors
have been reported by several groups of investigators. It now
appears that dry bottom plastic collector is entirely satis-
factory (176). Elimination of water or antifreeze from the
collector has greatly simplified the procedure for agencies
or companies maintaining a number of collectors over a relatively
large area. However, it is recommended that in areas where more
than one agency is maintaining a dustfall network, all collectors
be of a uniform nature to permit intercomparison of data. It
is further recommended that agencies establishing new networks
utilize the latest Intersociety Committee, ASTM, or APCA Standards?
in that order,when they are available. This is a field method
of long standing.
9-61
-------
9.2.6.2 Suspended Particulates
This method is intended for the collection of fine particulates
between 0.3 and 50-100 microns (177). A large volume of air
(40,000-75,000 ft ) is drawn through the fibrous filter for a
period of time such as 24 hours . The filter is weighed under
controlled temperature and humidity conditions before and after
use and the difference in weight is reported as micrograms per
cubic meter of air sampled. The "hi-vol" samplers and shelters
designed to prevent collection of partigles larger than approxi-
mately 100 microns are well known and extensively used by the
National Air Sampling Network of NAPCA (177.) . Two comprehensive
reviews relative to the use of the hi-vol sampler to kraft mill
air pollution problems have been published by the National Council
for Air and Stream Improvement (70, 178) . These are field methods.
Committee TR-2 of the Air Pollution Control Association has
recommended a "Standard Method for Atmospheric Sampling of Fine
Particulate Matter by Filter Media-High Volume Sampler" (179).
The standard describes suitable instrumentation, instrumentation
housing, and analytical procedures to be used for characterization
of the collected particulates.
In addition to the determination of the total weight of suspended
particulates collected, portions of the filter may be analyzed
for sulfate, sodium, calcium, and benzene solubles. Other analyses
may be performed if the objective is to determine the relative
contribution from a kraft mill as compared with other community
sources.
Scaringelli and co-workers (180) have devised a fractional decom-
position technique wherein sulfuric acid aerosol and alkali sulfates
are separated from concomitantly present heavy metal sulfates on a
high volume filter. The volatized sulfates are passed over copper
gauze and the sulfates reduced to SO . The resultant SO is
determined by iodine MCT.
9.2.6.3 Sticky Paper
Various sticky coatings, including vaseline, dilute rubber cement,
gelatin, glycerine jelly, and Scotch tape have been exposed to
collect atmospheric particulates. Pritchard, et al., (181) evaluated
several gum rubber label stocks as impingement media for collecting
wind blown atmospheric dusts. Field evaluation of 37 adhesive-coated
materials indicated that Fasson R-135 was best suited for particle
collection. In practice the sticky tape is placed on a vertically
mounted cylinder and the north direction of the tape marked for
orientation. Following exposure for one week the tape is returned
to the laboratory for examination, counting and identification by
known microscopic techniques (182).
9-62
-------
9.2.6,4 Visual Range
The Charlson-Ahlquist visual range nephelometer is a light
scattering device which is finding increased application in
the continuous recording of the variations in meteorological
range at the sampling site (183) . The scattering coefficient
(meter ) thus derived can be related to meteorological range
and to the mass of aerosol per volume of air. The correlation
between meteorological range as determined by the nephelometer
and the mass loading as determined by the hi-vol sampler has
been found to be above +0.9 in widely separated urban
areas such as Seattle, San Jose, and New York City (184). When
the atmospheric humidity exceeds 70% the correlation between
the nephelometer and mass loading decreases.
Further evaluation of the nephelometer under a variety of urban,
industrial, and rural conditions will be required to further
substantiate its usefulness in the characterization of atmos-
pheric particulates. The nephelometer is non-specific and
responds to particulates from all sources present in the
environment.
9.2.7 RECOMMENDED AMBIENT METHODS
9.2.7.1 Gaseous Sampling and Analysis
A. Sensory
Use the Seentometer (105) as an aid in conducting subjective odor
evaluation studies in place of an arbitrary odor intensity scale.
B. Wet Chemical
Hydrogen Sulfide. Sample air at 1 liter per minute using a midget
impinger containing cadmium hydroxide slurry and 1 percent STRactan
10 (121). Protect the impinger(s) from light by wrapping with black
paper or electrician's tape. Determine the collected sulfide by the
methylene blue procedure (95, 118) within 24 hours if possible.
Methyl Mercaptan. Sample air at 1 liter per minute using a midget
impinger containing mercuric acetate solution. Determine the
collected mercaptans spectrophotometrically by reaction with N,
N-dimethyl-p-phenylenediamine (132, 135).
Dimethyl Sulfide and Dimethyl Disulfide. There are no sufficiently
sensitive wet chemical methods for determination of these compounds
in the ambient air.
9-63
-------
Sulfur Dioxide. See Section 9.3.6
Gas Chromatography. A polyphenyl ether-Teflon column will
separate complex mixtures of volatile sulfur gases down to
approximately 5 ppb (168) . Detection of the separated com-
pounds can be accomplished at this concentration range with '
either the FPD (154) or the bromine MCT (150) . The gas
chromatographic method has been automated to provide sequen-
tial analyses at 10 - 15 minute intervals (51).
Pre-Selective Filtration. Chemically impregnated membrane
filters provide separation of the five major volatile sulfur
gases found in the vicinity of kraft pulp mills (152).
Detection of the fractionated samples may be accomplished
with either the bromine MCT (151) or the FPD (154).
Total Volatile Sulfur Gases. Either the bromine MCT (151)
or the FPD (51) can be used to provide a continuous real-
time determination of atmospheric fluctuations of these
gases. Both detectors will require a minimum of daily
attention to assure maximum operating reliability.
9.2.7.2 Particulate Sampling and Analysis
Pustfall. Dry bottom containers with adequate bird rings
are useful in examining 4-week or 30-day accumulations of
settleable particulates. Selected chemical analyses can
provide information on possible sources of the collected
material (70, 174, 176).
Suspended Particulates. Hi-vol sample filters can be
analyzed to provide information concerning possible sources
of suspended particulates (70, 178, 179).
Sticky Paper (181). Microscopic examination of sticky paper
can provide information on the nature of particles Collected
and the direction from which they came.
9-64
-------
9.3 SULFITE SOURCES
The gaseous emission of principle interest in the
sulfite process is sulfur dioxide. The nature of
particulate emissions depends upon the cooking base
and whether recovery by burning is practiced.
9.3.1 SOURCE SAMPLING (GASES)
9.3.1.1 Continuous Monitoring
Three methods have been used to monitor sulfur
dioxide from the sulfite process. These methods
include infrared and ultraviolet spectroscopy and
conductivity.
Non-dispersive infrared analyzer (185) has been used
in a magnesium base acid bisulfite mill with success.
The reference cell contained all of the flue gas com-
ponents less the sulfur dioxide. The flue gas is
passed through the sample cell at 3.5 CFH and the
differential output is related to the SO in the flue
gas. The IR cell windows must be protected from water.
In one instance, a large filter is followed by a re-
frigerated dryer reducing the flue gas to -10°F.
Particulates in the flue gas caused frequent plugging
of the sample line and the instrument environment was
unduly corrosive for the electronic circuitry. It is
estimated that one installation cost in excess of
$10,500 and has been continually plagued with approxi-
mately 50 percent instrument downtime.
Thoen's ultraviolet system (186) by contrast is quite
simple in design, relatively inexpensive (less than
$2,000), and extremely reliable. The ultraviolet
source and detector are mounted externally to the flue
gas duct and protected from the flue gas by quartz
windows. A 2 1/2 inch diameter tube is located at 90°
to the flue gas flow and connects the externally mounted
source and detector. One-half inch holes are placed
2 1/2 inches apart at 90° to the gas flow. These physical
arrangements minimize particulate and water accumulation
in the light path tube. Maintenance is limited primarily
to a cleaning of the quartz windows every three weeks.
The instrument has been calibrated externally to the flue
9-65
-------
gas duct by passing nitrogen-sulfur dioxide mixtures
through the light path tube. (Possibly a more reliable
calibration procedure would involve the addition of
known quantities of sulfur dioxide to a flue gas matrix
rather than the nitrogen gas base which has been used.)
This work has not been confirmed by others.
A variety of conductivity instruments from home-builts
to modified commercial units have been successfully used
by several sulfite mills (187, 188). Conductivity units
require close control of reagent and sample gas flow to
maintain calibration. These instruments are relatively
inexpensive.
Correlation spectrometry and multiple-scan interferometry
(189 - 191) have been proposed for use as remote sensing
devices to determine the SO concentration from industrial
and power plant stacks. In theory the instrument could
be used by the emitter at the source to monitor SO
emissions or by regulatory officials located in a mobile
unit at some distance from the source. Significantly,
this can also be done at night. This instrumentation is
considerably more complex than Thoen's ultraviolet system.
Thus initial expense and subsequent maintenance could be
significantly greater.
9.3.1.2 Batch Sampling
A large number of methods has been published. Some methods
such as the hydrogen peroxide titration method will include
all of the sulfur trioxide. The sample is drawn through an
impinger containing dilute hydrogen peroxide. The sulfuric
acid formed is titrated with standard sodium hydroxide solu-
tion using a mixed indicator of bromocresol green and methyl
red (192) .
In the iodine thiosulfate method, the sample is drawn
through a standard solution of iodine in potassium iodide,
the iodine remaining is then determined by titration with
standard thiosulfate solution (193). A major source of
error is the loss of iodine from the impinger containing
the iodine --KI solution. A second impinger in series con-
taining standard thiosulfate solution is used to collect
any iodine carried over from the first impinger.
9-66
-------
9.3.2 SOURCE SAMPLING (PARTICULATES)
9.3.2.1 Continuous Monitoring
Particulate loading in kraft flue gases has been determined
by continuously measuring the sodium ion concentrations
in a stream of liquid which has scrubbed the flue gas
.sample. Leonard (194) has described a home-built analyzer
in which a dilute ammonia solution is injected at the end
of a sample probe. The particulates are removed from the
flue gas sample by the liquid as the sample is drawn to
the detector. The sodium concentration is measured with
a sodium ion selective electrode. The instrument is calibrated
against aqueous standards containing known concentrations of
sodium ions. The technique may be applicable where recovery
of sodium-base sulfite liquors is practiced.
Tretter (195), and Pavers and Neuberger (196) reported the
use of a Chemonoitor^' in a similar manner. In this application
a Calgon buffer reagent is used instead of Leonard's dilute
ammonia reagent. It is planned to substitue a steam eductor
for the sample air pump and to back-flush the probe automatically
every eight hours to eliminate problems of electrode fouling
and probe plugging. The technique may be applicable where
recovery of sodium-base sulfite liquors is practiced.
The bolometer which has been used for many years to measure
smoke density and more recently to monitor particulate
loading in kraft mill recovery furnace stack emissions (197)
might be equally effective in recording total particulate
loadings in sulfite mill emissions when properly calibrated
and maintained.
Laxton and Lawton (198) have described an automatic monitor
for recording sulfur trioxide in flue gas. The collected
sulfate is reacted with barium chloranilate in 80 percent
isopropyl alcohol in a continuous colorimetric recording
system. The monitor has an upper limit of 50 - 100 ppm
9.3.2.2 Batch Sampling
Fielder, et al., (199) sampled flue gas through a heated
stainless steel probe containing glass wool. The flue
gas is saturated with cold 80 percent isopropyl alcohol.
A sulfuric acid mist is formed and collected on a sintered
glass filter. The collected acid mist is washed off the
filter and the sulfate determined turbidimetrically. The
gases pass through the filter, are collected in an iodine-
potassium iodide solution, and the SO_ determined iodimetrically.
9-67
-------
A similar sampling train was developed by M. Hissink
(200) by collecting sulfuric acid aerosol on a heated
glass filter cone kept at 200 - 250°F which is between
the dew point of sulfuric acid and water. The SO passes
through the filter and is collected in a. water scrubber.
Mader, et al., (201) filtered the sample through filter
papers, specially prepared by leaching with distilled
water and then dried, to trap the sulfuric acid aerosol.
The acidity was determined by titration. Sulfur dioxide
reportedly did not interfere.
9.3.3 RECOMMENDED SOURCE METHODS
9.3.3.1 Gaseous Sampling and Analysis
The ultraviolet and conductivity procedures have been
most successfully used in the mill. The ultraviolet (186)
instrumentation is less complex and it is not necessary
to replenish reagents or control reagent flow or gas
sampling rate. These latter methods appear to be the
methods of choice.
Batch sampling requires a considerable expenditure of
manhours to obtain intermittant data of limited value
for process control. Non-dispersive infrared and inter-
ference or correlation spectrometric instruments are
much more expensive and complex than are needed to
monitor SO emissions.
9.3.3.2 Particulate Sampling and Analysis
Measurement of particulate loading where recovery of sodium-
base sulfite liquor is practiced is most readily accomplished
by continuously measuring the sodium ion concentration (activity)
in a continuous flow scrubbing system using an ion-selective
electrode. The bolometer has not had adequate mill use. Its
calibration to provide direct readout in terms of soda loss would
be more difficult than with the ion selective ion electrode technique.
Methods for other particulate sources in sulfite mills have not been
s tandardi zed.
9-68
-------
9.3.4 AMBIENT SAMPL-ING (GASES)
Methods used for measuring sulfur dioxide may be
classified into three categories ? continuous
monitoring, short-term batch, and cumulative.
Each category provides a different type of infor-
mation required in each given situation.
9.3.4.1 Continuous Monitoring
The most commonly used monitoring system is exemplified
by the Thomas Autometer (202) which embodies the
measurement of changes in the conductivity of the
reagent due to the absorption of pollutants,
assumed to be primarily sulfur dioxide, from the
sampled air and interpreted in terms of equiva-
lent sulfur dioxide concentrations. The sensitivity
of these devices generally averages 0.05 ppm; however,
they are non-specific, responding to any material
which is collected by the absorbing solution and
which will alter the conductivity of the absorbing
solution. Fortunately, in most practical field
situations, sulfur dioxide may represent the major
polluting constituent or the solubility or col-
lection efficiency of the scrubber may be signifi-
cantly lower for other pollutants. Numerous field
comparisons have been conducted which indicate
that conductivity and other SO procedures agree
fairly well (203, 204) , although the observed
difference may be either positive or negative depending
upon the characteristics of the indigenous air pollution.
HC1, NH , and Cl give particularly significant positive
recorder responses. Shikiya and McPhee (205) foun
unexplained differences from two- to four-fold between
conductivity analyzers and between conductivity and
colorimetric analyzers. Terabe, et al., (206) found
that the conductivity method gave higher SO values
than the colorimetric method in Kawasaki, Japan.
More recently other continuous monitoring methods for
SO have become available including coulometry, colori-
metry, flame photometry, and permeation into an electro-
chemical cell. The earliest available continuous
coulometric analyzer, the Titrilog (22, 207), originally
lacked the sensitivity and specificity required for
monitoring the ambient air. Nader and Dolphin (208)
and McKee and Rolliwitz (209) suggested modifications
to improve the sensitivity; however, the method is not
specific since any compound which can be oxidized by
9-69
-------
bromine will be interpreted as equivalent sulfur
dioxide. The Titrilog II (23) has recently been
introduced and is reported to have a minimum
sensitivity of 0.02 ppm SO . The instrument
response time is not stated in the instrument
brochure.
Philips Industries (210) has also introduced a
new coulometric analyzer. Their specifications
indicate a standard full scale sensitivity of
1.15 ppm SO with a possibility for achieving
0.115 ppm full scale sensitivity. The reported
response time is 1.5 minutes to 63 percent of
final value and 3 minutes to 95 percent of final
value. The instrument is provided with a built-
in SO calibration source which may represent
the first SO instrument which can automatically
provide a total instrument calibration. Beck-
man's (211) coulometric instrument is reported
to have a very slow response time (212).
A bromine coulometric microtitration cell and
selective pre-filters has been used in the labora-
tory and field for the analysis of sulfur-containing
gases (150, 151, 213). Appropriate selection of
chemically-impregnated membrane filters will per-
mit measurement of the total sulfur-containing
gases in the atmosphere and determination of the
SO levels by difference between total sulfur gas
ana total minus SO . Electrolyte in the micro-
titration cell is automatically replaced to main-
tain a drift-free condition. A sensitivity of
0.01 ppm SO can be achieved and the response time
for 90 percent of final value is attained in 15 -
seconds.
The performance chacteristics of twelve commercially
available (as of September 1, 1967) continuous
sulfur dioxide monitors were determined by Rodes, et
al. (214) . Instruments based upon conductivity,
colorimetry and coulometry were examined to determine
such instrument characteristics as stability, sensiti-
vity, response time, collection efficiency and response
to interfering substances. Other, less extensive,
instrument evaluations have been reported by Potter
(212) and Givens, et al., (215). These studies have
9-70
-------
provided invaluable insight into the limits
of application of these instruments. Certain
instrument models have since been modified to
improve certain shortcomings as revealed by
these comparative tests.
In addition to the instruments reported in
these studies, a number of new instruments
have been reported or become commercially
available within the past two years.
The flame photometric detector (FPD) (216) has
been incorporated into a continuous sulfur gas
analyzer (217) which will respond not only to
SO , but also to H S and possibly mercaptans
and alkyl sulfides and disulfides. Stevens,
et al., have utilized the FPD in conjunction
with gas chromatography (50, 51) to provide a
separation of SO from H S.
The automated colorimetric analyzers (218-220)
provide delayed data output for sequenced sampling
periods and therefore would not be adequate to
establish compliance with an air quality standard
involving 3-minute maximum allowable concentra-
tions. These instruments would, however, provide
suitable information for longer averaging periods
of 15 minutes or more where additional delays of
15 - 30 minutes for completion of the analysis can
be tolerated. The automated chemical procedures
required, will most certainly increase the required
maintenance and provide additional variables which
must be accurately controlled if reasonable data
are to be obtained.
Specially designed electrochemical cells separated
from the sample air stream by a thin plastic film
have been developed which appear to be relatively
selective for SO , NO , and NO (221). Two versions
of the SO monitor provide for analysis of a maxi-
mum of 2 - 10 ppm or 1000 ppm SO . Initial labora-
tory evaluation of the low SO monitor indicated
that the full-scale sensitivity could be adjusted
to 1 ppm SO . Interference from O , NO , Cl , H S,
CH SH, RSR, and RSSR was either negligible or non-
existent within reasonable ranges of concentration.
9-71
-------
Since the SO enters the electrochemical reaction
cell by permeation through the thin plastic membrane, the
response of this detector is independent of a sample gas
flow rate in the range of 1 - 3 CFH. Thus instrument
maintenance should be limited in most instances to the
manufacturer's recommended replacement of the sealed
electrochemical reaction cell once every three months.
Insufficient time has elapsed since the introduction
of the instrument to permit adequate laboratory and
field evaluation.
Selection of the continuous SO analyzer to be used
for ambient studies in the vicinity of a sulfite mill
must be based upon a careful evaluation of the character-
istics of the available instruments, the location of other
sources of interfering compounds in the locality, and the
requirements of the local air quality regulations. If the
regulatory agency requires hourly or 24-hourly averages,
then rapid response time is not a critical characteristic.
If, on the other hand, a regulation states that a three-
minute peak in excess of 1.51 ppm constitutes a violation,
the Bay Area finds that instruments must provide a 75
percent of scale response to 2 ppm SO for at least 1.75
minutes of a three-minute exposure at 2 ppm (212).
Data obtained'with the non-specific analyzers described
in this section must be interpreted with extreme caution
because of the possible presence of interfering substances.
Instrument maintenance and reliability varies greatly
from one instrument to another. With the newer instru-
ments either limited or no field experience has been
developed and no comparative testing has been reported
to indicate how they compare with methods already in use.
9.3.4.2 Short Term Batch
The modified West-Gaeke (222) colorimetric method has
gained the widest acceptance for either grab or sequential
sampling for periods of ten minutes to 24 hours. Sulfur
dioxide is collected in 0.1 M sodium tetrachloromercurate
(II). The colorimetric determination is based upon the
measurement of the red-violet color produced by the
reaction of dichlorosulfitomercurate (II) with hydrochloric
acid-pararosaniline and formaldehyde. Modifications have
been developed to eliminate interference from oxidant
(223), nitrogen dioxide (224, 225) and heavy metal ions
(226). The method has been adopted as tentative by the
Intersociety Committee on Methods for Ambient Air Sampling
and Analysis (227) .
9-72
-------
Other ,short~term methods include (a) collection in dilute
hydrogen peroxide-sulfuric acid solution and measurement
of the change in conductivity, (b) collection in dilute
hydrogen peroxide solution and titrimetric determination
of the acidity, or turbidimetric or gravimetric determina-
tion of the resultant sulfate, and (c) collection in
iodine-iodide and titration with standard thiosulfate
solution. These latter methods are either not sufficiently
sensitive or too time consuming to be used routinely for
determination of sulfur dioxide in the ambient air.
Stratmann (228) described a method wherein SO was first
sorbed on silica gel. After sampling a known volume of
air, the SO was then desorbed and reduced to H S at 700 -
900° C in contact with a platinum catalyst. The H S was
then absorbed in a 2 percent solution of ammonium molybdate
and the equivalent sulfur dioxide determined colorimetrically.
The method is fairly specific for S0_, but the final determi-
nation of the resulting H S by molybdenum complex is not the
most sensitive procedure available.
Pate, et al., (229) sampled concentrations of S0_ by filtering
air samples through potassium bicarbonate-impregnated types
HA and AA Millipore'^- filters. The filters were then analyzed
for collected sulfate. The duration of. the sampling period
would determine whether the technique would be classified as
"short-term batch" or "cumulative." The technique can pro-
vide air concentrations of SO if the air sample volume is
measured. Such quantificati9n is not possible with static
samplers such as the lead peroxide candle and Huey sulfation
plate.
9.3.4.3 Cumulative Methods
The lead peroxide candle was developed in England by Wilsdon
and McConnell (230) in 1932 as an inexpensive method for
measuring the relative "sulfation" of the atmosphere at
numerous selected sampling sites within a prescribed study
area. Numerous investigators have reported varying relation-
ships between sulfation and sulfur dioxide concentration in
parts per million as a mean of the sulfur dioxide concentra-
tion over the period of the peroxide candle exposure. The
method will not, however, provide short-term concentration
data because of its relative insensitivity.
9-73
-------
Huey (231) has developed a more convenient procedure
which utilizes an inverted 48 mm Petri dish containing
the lead peroxide paste. This technique eliminated the
tedious job of coating the 100 square centimeter gauze
surface used in the candle technique. A simplified
Petri dish holder-bracket may be attached to a convenient
utility pole, thus eliminating the square or round louvered
shelters used with the candle. The performance of the
plates was compared with the candles at several different
locations. The plates were approximately 20 percent more
reactive than the candles (231).
Harding and Kelley (232) used a 44-station network of
3x4 inch mild steel plates to demonstrate monthly
corrosion patterns. The dispersion pattern of corrosion
gave a reasonably good description of the SO dispersion
from several nearby sources. The correlation coefficient
between sulfation and corrosion was 0.60, indicating that
less than half of the variance could be accounted for by
the relation to sulfation. Sea salt gave high corrosion
rates near the Jacksonville beach, but dropped off to
background within one mile from the beach.
9.3.5 AMBIENT SAMPLING (PARTICULATES)
9.3.5.1 Sulfur Trioxide
There is no satisfactory specific method for this material.
Generally, available methods depend upon collection of the
aerosol by filtration, electrostatic precipitation, or im-
paction (233) . Subsequent interference by sulfur-containing
gases may occur particularly in filtration. The collected
material is then subsequently analyzed by determination of
acidity of the sample, determination of the sulfate ion, or
determination of the resulting conductivity charge. All of
these techniques are subject to interference from other
acidic materials, other sulfate salts, or all ionic pollutants,
Thomas, et al., (234) developed an automatic, non-specific
method wherein the aerosol is collected by sonic impaction
and the collected acid is determined with a conductivity
cell. The air sample was then scrubbed through dilute
sulfuric acid-hydrogen peroxide reagent and "SO " determined
with a second conductivity cell. The method measures only
the "effective" hydrogen ion concentration and is subject
to potential positive and negative interferences.
9-74
-------
Scaringelli and Rehme (235) developed a method wherein
aerosols are separated from gases by impaction or filtration.
The collected sulfuric acid aerosol is then decomposed at
controlled temperature under a. stream of nitrogen to separate
sulfur trioxide from collected sulfates. The sulfur trioxide
is converted to sulfur dioxide by reaction with hot copper.
The sulfur dioxide is then collected and determined either
spectrophotometrically, coulometrically, or flame photo-
metrically . Ammonium sulfate is the only known compound
which reacts similarly, but it is assumed that ammonium
sulfate is formed in the atmosphere by the reaction of
sulfuric acid and gaseous ammonia. The method is reported
to be sensitive to sulfur trioxide in the parts per billion
range with samples of only one liter of air.
Two visual methods have been proposed. Gerhard and Johnstone
(236) impinged the air stream on an acid-base dye-impregnated
film and measured the area of the resulting yellow spots.
Lodge, et al., (237) microscopically examined and counted
characteristic spots resulting from the impingement.of the
aerosols on a film of silicon monoxide supported on a Formvar
impingement plate which was subsequently shadowed with cadmium
or chromium. Both methods involve considerable manual labor
in the microscopic evaluation of the film or;plate. The Lodge
procedure undoubtedly provides the most specific method avail-
able for detection and identification of sulfuric acid aerosol.
Unfortunately, the method is limited to qualitative examination
of aerosols to determine whether sulfuric acid aerosol is
present and to provide an estimate of the ratio of sulfuric
acid aerosol to other particulates in small volumes of air.
9.3.6 RECOMMENDED AMBIENT METHODS
9.3.6.1 Gaseous Sampling and Analysis
Continuous Analysis. At the present state of the art, con-
ductivity and possibly the Titrilog II (23) offers the best
reliability for the field monitoring of SO in ambient air.
Serious interferences may be encountered, however, in using
these instruments.
Batch Sampling. Sample air at 1 liter per minute using a
midget impinger containing sodium tetrachloromercurate (II)
solution. Determine the collected by reaction with acid
bleached pararosaniline following the Intersociety Committee
Tentative Procedure (227).
9-75
-------
Cumulative Sampling. The Huey sulfation plates (231) are
recommended for use in any new survey. The British "candle
has been in use for many years and comparative data should
be obtained by both techniques before abandonment of the
"candle" is contemplated in an area where considerable his-
toric data has been accumulated with "candles."
9.3.6.2 Particulate Sampling and Analysis
Continuous Analysis. The Thomas sulfuric acid aerosol
impactor (234) and conductometric determination of the
collected aerosol represents the only known method. The
data obtained must be carefully evaluated considering the
non-specificity of the method.
Batch Sampling. Impaction, filtration, and electrostatic
precipitation may be used to collect samples for up to
24 hours. There is no satisfactory method for the determi-
nation of the collected sulfuric acid aerosols. Conductivity
yields "effective" hydrogen ion. Gravimetric or colorimetric
determination of total sulfate will include other soluble
sulfates such as sodium and ammonium sulfate. Coulometric
analysis of the pyrolyzed sample provide probably the best
method for the determination of sulfuric acid (235), although
titrimetric determination is much less complex.
9.4 NSSC SOURCES
No unique or special conditions apply to emissions from
NSSC mills. It is believed that methods already discussed
in previous sections will be adequate when applied to NSSC.
9-76
-------
9.5 REFERENCES
1. Felicetta, V. F., Q. P. Peniston, J. L. McCarthy, TAPPI, 36,
425-(1953).
2. Lindvall, T., "Experimental Techniques of Organoleptic Odor
Measurement," in Atmospheric Emissions from Sulfate Pulping
CE. R. Hendrickson, Ed.), April 1966.
3. Cederloff, R., M. L. Edfores, L. Friberg, T. Lindvall, Jour.APCA,
16, 92-(1966).
4. Sullivan, D. C., D. F. Adams, F. A. Young, Atmoshperic Environment,
2^, 121- (1968) .
5. Thomas, E. W., TAPPI, 47, 587-(1964).
6. Tamele, M. W., L. B. Ryland, Ind. Eng. Chem., Anal. Ed., £, 16-(1936).
7. Tamele, M. W., L. B. Ryland, V. C. Irvine, Ibid., 13, 618-(1941).
8. Lykken, L., F. D. Tuemmler, Ibid., 14, 67 (1942).
9. Siggia, S., R. L. Edsberg, Anal. Chem., 20, 938-(1948).
10. Martin, F. R., Atmospheric Pollution Technical Bulletin #35,
National Council for Stream Improvement, New York, 1968.
11. Wright, R. H., M. A. Schoening, A. M. Hayward, TAPPI, 34, 289-(1951).
12. Colombo, R. , D. Corbetta, A. Pirotta, A. Sartori, Ibid., 40,
490-(1957).
13. Bergstrdm H., K. G. Trobeck, Svensk Papperstid., 42, 554-(1939).
14. Ibid., 48, 49-(1945).
15. Bialkowsky, H. W., G. G. DeHaas, PulpSPaper Mag. Canada, 53, (11)
100-(Oct., 1952).
16. "Public Health Service Reports," U. S. Public Health Service,
Washington, D. C., Jan. 13, 1939.
17. Harding, C. I., E. R. Hendrickson, B. B. Sundaresan, C. G. Walker,
Atmospheric Pollution Technical Bulletin #28, National Council for
Stream Improvement, New York, 1965.
9-77
-------
18. Adams, D. F., E. I. -S. Wan, Research Report #69/1-28, Washington
State University, Pullman, Washington, March 1969.
19. STRactan, trademark brand aribinoglactan, St. Regis Corp.
20. Mathews, W. C., Personal Communication 1962.
21. Murray, F. E., J. B. Risk, paper presented Pacific Northwest
International Section Air Pollution Control Assoc., Vancouver,
B. C., Nov. 1965.
22. Consolidated Electrodynamics Corp., Sierra Madre Villa, Calif.
(no longer available).
23. Process Analyzers, Inc., Houston, Texas.
24. Trobeck, K. G., W. Lenz, A. A. Tirado, TAPPI, 42, 425-(1959).
25. ITT-Barton Instrument Co., Monterey Park, Calif.
26. Cooper, H. B. H., Jr., J. A. Megy, paper presented at Pacific
Northwest International Section Air Pollution Control Assoc.,
Vancouver, B. C., Nov. 1966.
27. Thoen, G., G. G. DeHaas, R. R. Austin, TAPPI, 51, 246-(1968).
28. Wan, E. I.-S., D. F. Adams, unpublished information, 1969.
29. Blosser, R. O., H. B. H. Cooper, Jr., "Compendium of Methods
for Measuring Ambient Air Quality and Process Emissions -
Section 11A - Gaseous Emissions - Automatic Techniques -
Electrolytic Titration," Atmospheric Pollution Technical
Bulletin #38. National Council for Air and Stream Improvement,
New York, Dec. 1968.
30. Amberg, H. / Personal Communication, 1969.
31. Adams, D. F. , R. K. Koppe, TAPPI, 41, 366-(1958).
32. Adams, D. F., R. K. Koppe, D. M. Jungroth, Ibid., 43, 602-(1960).
33. Cave, G. C1. B. , Ibid. , 46, 15-(1963).
34. Adams, D. F., D. M. Jungroth, B. Blymeyer, Jr., "Survey of Kraft
Mill Gaseous Emissions Using Gas Chromatographic Techniques."
Atmospheric Pollution Technical Bulletin #16, National Council
for Stream Improvement, New York, Oct. 1962.
35. Grune, W. N., Progress Report USPHS Research Grant #RG 7004,
Atlanta, Ga., Jan. 1961.
9-78
-------
36. McWilliam, I. G., R. A. Dewar, Nature, 181, 760-(1958).
37. Anderson, K., J. G. T. Bergstrom, Svensk Papperstid., 70, (23),
805-(Dec. 15, 1967).
38. Ruus, L., Medd. Skogsind. Vattenskyddsrad, 38, 18-(1964).
39. Bethge, P. O., L. Ehrenberg, Svensk. Papperstid., 70, 347-(1967).
40. Rhoad, F. N. Southern Pulp & Paper Mf., 28 (3), 60- March 10, 1965.
41. Coulsen, D. M., L. A. Cavanagh, paper presented Pittsburgh Conf.
on Anal. Chem. & Appl. Spect., March, 1961.
42. Klaas, P. J., Anal. Chem., 33, 1851-(1961).
43. Adams, D. F., G. A. Jensen, J. P. Steadman, R. K. Koppe, T. J.
Robertson, Ibid., 38, 1094-(1966).
44. Adams, D. F., R. K. Koppe, Jour. APCA, 17, 161-(1967).
45. Drink, D. L., J. R. Thomas, D. L. Feuerstein, TAPPI, 50, 276-(1967)
46. Martin, R. L., J. A. Grant, Anal. Chem., 37, 644-(1965).
47. Brody, S. S., J. E. Chaney, J. Gas Chromatog., 4^ 42-(1966).
48. Harding, C. I., Personal Communication, 1966.
49. Alley, F. C., J. H. Turner, paper #68-34 presented 61st Annual
APCA Meeting, St. Paul, June, 1968.
50. Stevens, R. K., A. E. O'Keefe, G. C. Ortman, J. A. Hodgeson, paper
presented 156th ACS meeting, Atlantic City, Sept., 1968.
51. Stevens, R. K., A. E. O'Keefe, J. D. Mulik, K. J. Krost, paper
presented 157th meeting ACS, Minneapolis, April, 1969.
52. Stevens, R. K., Personal Communication, 1969.
53. Walther, J. E., H. R. Amberg, TAPPI, 51, 126A-(Nov., 1968).
54. Williams, I. H., F. E. Murray, Pulp S Paper Mag. Canada, 67, (8),
3-(Aug. 1966).
55. Walther, J. E., H. R. Amberg, TAPPI, 50, (10), 108A-(1967).
56. Applebury, T. E., "Air Pollution Abatement by Process Gas
Chromatography," Thesis Montana State Univ., March 1968.
9-79
-------
57. Wan, E. I.-S., "Analysis of Gaseous Sulfur Compounds by Gas
Chromatography," Thesis Montana State Univ., December 1968.
58. Thoen, G. N., paper presented West Coast Regional Meeting National
Council for Air and Stream Improvement, Portland, Oregon,
Nov. 1968.
59. Orion Research Inc., Cambridge, Mass.
60. Swartz, J. L., T. S. Light, paper presented Ion-Selective
Symposium, Gaithersburg, Md., 1969.
61. Megy, J. A., "An Evaluation of the Orion Sulfide Probe,"
NCSI Progress Report, Corvallis, Oregon, Oct. 1967.
62. Foxboro Company, Foxboro, Mass., April 23, 1969.
63. Thoen, G. N. , D. C. Nicholson, Personal Communication, 1968.
64. Collins, T. T. , Jr., Paper Ind., 28, 680, 830 and 986 (1947).
65. "Methods for the Determination of Velocity, Volume, Dust and
Mist Content of Gases," Bull, WP-50. Western Precipitation
Corp., Los Angeles, 1956.
66. Power Test Code No. 27, "Determining Dust Concentration in a
Gas Stream," Am. Soc. Mech. Engrs., New York, 1957.
67. Hendrickson, E. R. , "Manual for the Sampling and Analysis
of Kraft Mill Recovery Stack Gases," Atmospheric Pollution
Technical Bulletin #14, National Council for Air and Stream
Improvement, New York, October 1960.
68. Harding, C. I., E. R. Hendrickson, R. S. Sholtes, "Measuring
Non-steady Flow in Industrial Stacks" Atmospheric Pollution
Technical Bulletin #27, National Council for Air and Stream
Improvement, New York, October 1965.
69. Bloomfield, B. B. , "Source Testing," Chap. 28, Air Pollution
Vol. II, 2nd Ed., A. C. Stern, Editor, Academic Press, New
York, 1968.
70. Duncan, L. "Compendium of Methods for Measuring Ambient Air
Quality and Process Emissions, Section 4," Atmospheric Pollution
Technical Bulletin No. 37, National Council for Air and Stream
Improvement, New York, December 1968.
71. Industrial Gas Cleaning Institute, Inc., "Test Procedures for
Gas Scrubbers," Publication No. 1, 1964, Rye, N. Y.
9-80
-------
72. Ibid., "Procedure for Determination of Velocity and Gas Flow
Rate," Publication No. E-P 2, 1965, Rye, N. Y.
73. Ibid., "Criteria for Performance Guarantee Determinations,"
Publication No. E-P-3, 1965, Rye, N. Y.
74. Duncan. L. and H. B. H. Cooper, "Compendium of Methods for
Measuring Ambient Air Quality and Process Emissions - Part I -
Basic Information," Atmospheric Pollution Technical Bulletin
No. 41, National Council for Air and Stream Improvement.
New York, August, 1969.
75. Blosser, R. O., H. B. H. Cooper, Jr., TAPPI, 51, (5), 73A-(1968).
76. Washington State Department of Health, "Basic Considerations
Re Monitoring Programs for Kraft Pulp Mills," Sept. 1969.
Seattle, Washington.
77. Research Appliance Co., "Staksamplr," Allison Park, Pa., 15101.
78. Leonard, J. S., "Continuous Kraft Recovery Emission Monitoring,"
Atmospheric Pollution Technical Bulletin No. 35, National
Council for Air and Stream Improvement, New York, March 1968.
79. Comacho, T. F., Southern Pulp & Paper Mfg., 30, (6), 96-(June 10,
1967). i
80. Cooper, S. R., C. F. Haskell, Paper Trade J., 151, (13), 58-(1967).
81. Achinger, W. C. , R. T. Shigehara, "A Guide for Selecting Sampling
Methods for Different Source Conditions" paper presented 60th
Annual APCA Meeting, Cleveland, Ohio, June, 1967.
82. Hendrickson, E. R., C. G. Walker, V. D. Chapnerkar, Am. Ind. Hyg.
Assoc. J., 24, 121- (1963).
83. Falgout, D. A., C. I. Harding, Jour. APCA, 18, 15-(1968).
84. Cederlof, R. , L. Friberg, T. Lindvall, "The Organoleptic
Evaluation of Odors with Special Reference to the Kraft Pulp
Industry," in Atmospheric Emissions from Sulfate Pulping
(E. R. Hendrickson, Ed.), April 1966.
85. Cederlof, R., M. L. Edfors, L. Friberg, T. Lindvall, Jour. APCA,
16, 92-(1966).
86. "Research on Chemical Odors, Part I," A. D. Little, Inc., 1968.
87. Adams, D. P., F. A. Young, R. A. Luhr, TAPPI, 51, (3), 62A-(1968).
9-81
-------
88. American Petroleum Institute, "Manual on Disposal of Refinery
Wastes, Sect. 2 Waste Gases and Vapors," 1st Ed. 1931.
89. Dalla Vale, J., E. H. Dudley, Public Health Reports, 54_ (2),
36-(1939).
90. Sanderson, H. P., R. Thomas, M. Katz, Jour. APCA, 16, 329-(1966).
91. Sheey, J. P., J. J. Henderson, C. I. Harding, A. L. Danis, PHS
Publication No. 999-AP-3, USPHS, D.H.E.W., Cincinnati, Ohio,
April 1963.
92. Adams, D. F., W. L. Bamesberger, unpublished information 1968.
93. O'Keefe, A. E., G. C. Ortman, Anal. Chem., 38, 760-(1966).
94. Levaggi, D., Personal Communication, 1968.
95. Jacobs, M. D., M. M. Braverman, S. Hochheiser, Anal. Chem.,
•&_, 1349-(1957).
96. Sullivan, D. C., D. F. Adams, F. A. Young, Atmospheric Environment,
2:, 121-(1968).
97. STRactan, trademark brand aribinoglactan. St. Regis Corp.
98. Bamesberger, W. L., D. F. Adams, Env. Sci. Techno!., in press.
99. Feldstein, M., Personal Communication, 1968.
100. Wohlers, H. C., Jour. APCA, 17, 609-(1967).
101. Lenz, W. and A. A. Tirado, "Method of Measuring Odors by Means
of Observers," in Atmospheric Emissions from Sulfate Pulping
(E. R. Hendrickson, Ed.), April 1966.
102. Horstman, S. W., R. F. Wromble, A. N. Heller, Jour. APCA, 15,
261-(1965).
103. "A Study of Air Pollution in the Interstate Region of Lewiston,
Idaho and Clarkston, Washington," U. S. Department of Health,
Education and Welfare, Public Health Service Publication 999-AP-8.
104. Sableski, J. J., Air Eng., 10, (9), 16-(1968).
105. Huey, N. A., L. C. Boering, G. A. Jutze, C. W. Gruber, Jour.
APCA, 10, 441(1960).
9-82
-------
106. Chanin, G. A., J. R. Elwood, E. H. Chow, Sew, and Ind. Wastes,
26_, 1217-(1954).
107. Gilardi, E. R., R. M. Manganelli, "A Laboratory Study of a Lead-
Acetate-Tile Method for the Quantitative Measurement of Low
Concentrations of Hydrogen Sulfide," Atmospheric Pollution
Technical Bulletin #15, National Council for Stream Improvement,
New York, August 1962.
108. Wohlers, H. C. , M. Feldstein, Jour. APCA, 16, 19-U966).
109. Reffner, J. A., C. I. Harding, T. R. Kelley, Jour. APCA, 17,
36-(1967).
110. Sensenbaugh, J. D. , W. C. L. Hemeon, Air Repair, 4_, 5-(1954).
111. Research Appliance Co., Allison Park, Pennsylvania.
112. Moses, D. V., L. T. Jilk, U. S. Patent 2,232,622, E. I. DuPont
DeNemours & Co., February 18, 1941.
113. Rubicon Company, Philadelphia, Pennsylvania.
114. Gelman Instrument Co., Ann Arbor, Michigan.
115. Pare, J. P., Jour. APCA, 16, 325-(1966). |
i
116. Hochheiser, J., L. A. Elfers, paper presented 157th ACS meeting,
Minneapolis, April, 1969.
117. Buck, M., H. Gies, Staub, Reinhaltung der Luft (Eng. Ed.), 26,
27-(Sept. 1966).
118. Marbach, E. P., D. M. Doty, J. Agr. S Food Chem., 4_, 881-(1956).
119. Budd, J., H. A. Berwick, Anal. Chem., 23, 1536-(1952).
120. Hasselhuhn, B. , "Sampling and Analytical Procedures Used in
Connection with the Swedish Odor Studies," in Atmospheric
Emissions from Sulfate Pulping (E. R. Hendrickson, Ed.),
April 1966.
121. Bamesberger, W. L., D. F. Adams, Env. Sci. Technol., in press.
122. Adams, D. F., 3rd Annual Progress Report RTGB Project #AP-00215-03.
123. Bo'strom, C. E. , Air & Water Pollution Jour. , 10, 435-(1966).
124. Bamesberger, W. L., D. F. Adams, submitted for publication.
9-83
-------
125. Thomas, B., W. L. Bamesberger, D. F. Adams, paper presented
157th ACS meeting, Minneapolis, April, 1969.
126. Prescher, K.-E., E. Lahman, Gesundh. Ingr., (Munich) 87, (12),
351-(1966).
127. Buck, M., H. Stratman, Staub, 24, 241-(1964).
128. Mecklenburg, W., F. Rosenkranzer, Z. Anorg. Chem., 86, 143-(1914).
129. Andrew, T. R., P. N. R. Nichols, The Analyst, 90, 367-(1965).
130. Swartz, J. L. , T. S. Light, paper presented Ion-Selective
Symposium, Gaithersburg, Md., 1969.
131. Farrah, G. H., Personal Communication, 1968.
132. Moore, H., H. H. Helwig, R. J. Graul, Ind. Hyg. J., 21, 466-(1960).
133. Hendrickson, E. R., Personal Communication, 1969.
134. Droege, H., Personal Communication, 1969.
135. Sliwinski, R. A., D. M. Doty, J. Agr. & Food Chem., 6_, 41-(1958).
136. Bamesberger, W. L., D. F. Adams, unpublished information, 1968.
137. Thomas, M. D., J. O. Ivie, T. C. Fitt, Ind. Eng. Chem., Anal. Ed.
18_, 383- (1946) .
138. Bialkowsky, H. W., G. G. DeHaas, Pulp S Paper Mag. Canada, 53,
99-(1952).
139. Terabe, M., S. Oomichi, F. B. Benson, V. A. Newill, J. E. Thompson,
Jour. APCA, 17, 673-(1967).
140. Washburn, H. W., R. R. Austin, "Air Pollution" (L. C. McCabe, Ed.)
Chap. 72, 596, McGraw Hill Company, New York, 1952.
141. Nader, J. S., J. L. Dolphin, Jour. APCA, £, 336-(1959).
142. McKee, H. C., W. L. Rolliwitz, Ibid. , £, 338-(1959) .
143. Fredricks, E. M., G. A. Harlow, Anal. Chem., 36, 263-(1964).
144. Dohrmann Instrument Co., San Carlos, California.
145. Lieber, E., R. Rosen, Ind. Eng. Chem., Anal. Ed., ^, 90-(1932).
9-84
-------
146. Rogers, F. M., R. F. Baldaste, Anal. Chem., 12, 724-C1940).
147. Field, E., C. S. Oldach, Ind. Eng. Chem., Anal. Ed., 18, 668-(1946)
148. Fogo, J. K., M. Popowsky, Anal. Chem., 21, 734-(1949).
149. Martin, J., J. A. Grant, Ibid., 37, 644-(1965).
150. Adams, D. F., G. A. Jensen, J. P. Steadman, R. K. Koppe, T. J.
Robertson, Anal. Chem.,38, 1094-(1966).
151. Adams, D. F., W. L. Bamesberger, T. J. Robertson, Jour. APCA, 18,
145-(1968). ;
152. Bamesberger, W. L. , D. F. Adams, submitted for publication.
153. Bamesberger, W. L., D. F. Adams, unpublished information, 1969.
154. Brody, S. S., J. E. Chaney, J. of Gas Chromatog., 4_, 42-(1966) .
155. Microtek Instruments, Inc., Baton Rouge, La.
156. Adams, D. F., discussion presented Gordon Research Conference
"Chemistry of Odors and Flavors," Crystal Mtn., Wash., July, 1966.
157. Harding. C. I., Personal Communication, 1966.
|
158. Stephens, E. R., P. L. Hanst, R. C. Doerr, W. E. Scott,
Ind. Eng. Chem., 48, 1498-(1956).
159. McCormack, A. J., S. C. Tong, W. D. Cooke, Anal. Chem., 37,
1470-(1965).
160. Bache, C. A., D. J. Lisk, Anal. Chem., 37, 1477-(1965).
161. Moye, H. A., Anal. Chem., 39, 1441-(1967).
162. Adams, D. F., R. K. Koppe, TAPPI, 41, 366-(1958).
163. Adams, D. F., R. K. Koppe, TAPPI, 43, 602-(1960).
164. Cave, G. C. B., TAPPI, 46, 1-(1963).
165. Williams, I. H., Paper presented Pacific Northwest International
Section Air Pollution Control Assoc. Meeting, Vancouver, B. C.,
Nov. 1965.
166. Koppe, R. K., D. F. Adams, Environ. Sci. Technol., 1^, 479-(1967).
9-85
-------
167. Eads, E. A., W. H. Cooper, Personal Communication, 1969.
168. Zhukhovitskii, A. A.,N. M. Turkel'taub., Dokl. Akad, Nauk SSR,
143, 646-(1961).
169. Bellar, T., J. E. Sigsby, C. A. demons, A. P. Altshuller,
Anal. Chem., 34, 743-(1962).
170. Feldstein, M. , S. Balestrieri, D. A. Lavaggi, Jour. APCA,
15, 215-(1965).
171. Thomas, E. W., TAPPI, 47, 587-(1964).
172. Adams, D. F. , R. K. Koppe, W. N. Tuttle, Jour. APCA, 15,
31-(1965).
173. Bechtold, E.Z., Anal. Chem.. 221, 262-(1966).
174. "Collection and Analysis of Dustfall (ASTM Designation:
D 1739-62)," 1965 Book of ASTM Standards, Part 23.
175. Adams, D. F.,R. K. Koppe, Jour. APCA, 16, 314-(1966).
176. Herrick, R. A., Jour. APCA, 16, 372-(1966).
177. "Air Pollution Measurements of the National Air Sampling
Network—Analysis of Suspended Particulates 1957-1961,"
U. S. Public Health Service, Publ. No. 978m Washington,
D. C. (1962).
178. Hendrickson, E. R., and C. I. Harding, "Manual for Calibration
and Use of High-Volume Samplers in the Measurement of Suspended
Particulate Matter," National Council for Stream Improvement,
Atmospheric Pollution Technical Bulletin No. 20, New York, 1964.
179. Jutze, G. A., K. E. Foster, Jour. APCA, 17, 17-(1967).
180. Scaringelli, F. P., K. A. Rehme, paper presented 155th meeting
ACS, San Francisco, April 1968.
181. Pritchard, W. L., E. C. Schumann, C. W. Gruber, Jour. APCA, 17,
305-(1967).
182. McCrone, W. C., R. G. Draftz, J. G. Delly, "The Particle Atlas,"
Ann Arbor Science Publishers, Inc., Ann Arbor, Mich., 1967.
183. Charlson, R. J., H. Horvath, P. Pueschel, Atmospheric Environ-
ment, 1, 469-(1967).
9-86
-------
184. Charlson, R. J., N. C. Ahlquist, H. Horvath, Atmospheric Environ-
ment, 2^, 455-(1968).
185. Hague, M., paper presented National Council for Air and Stream
Improvement Special Technical Session, Seattle, Oct.,1969.
186. Thoen, G. N., G. G. DeHaas, and F. A. Baumgartel, TAPPI,
52_, 2304-(1969).
187. Miller, A. M., paper presented National Council for Air and
Stream Improvement Special Technical Session, Seattle, Oct. 1969.
188. Georgia-Pacific Corp., Bellingham, Washington.
190. Low, M. J. D., F. K. Clancy, Env. Sci. Techno!., ^, 73-(1967).
191. Barringer, A. R., B. C. Newbury, paper presented 60th Annual
Air Pollution Control Assoc. Meeting.
192. Jacobs, M. B., "The Chemical Analysis of Air Pollutants,"
Interscience Publishers, New York, 1960.
193. Jacobs, M. B., "The Analytical Chemistry of Industiral Poisons,
Hazards, and Solvents," 2nd Ed., Interscience Publishers, New
York, 1949. I
j'
194. Leonard, J. S., paper presented National Council for Air and
Stream Improvement, Special Technical Session, Seattle, Oct., 1969.
195. Tretter, V., TAPPI, 52, 2324-(1969).
196. Rivers, H. M. and E. D. Neuberger, paper presented at 23rd
Alkaline Pulping Conference, Jacksonville, Florida, Oct., 1969.
197. Gansler, N. R., paper presented at Pacific Northwest International
Section Air Pollution Control Assoc., Vancouver, B. C., Nov. 1968.
198. Laxton, J. W., P. J. Lawton, J.. Inst. Fuel, 37, 12-(1964).
199. Fielder, R. S., P. J. Jackson, E. Raask, Ibid., 33, 84-(1960).
200. Hissink, M. Ibid., 36, 372-(1963).
201. Mader, P. P., W. J. Hamming, A. Bellin, Anal. Chem., 22,
1181-(1950).
202. Thomas, M. D., R. J. Cross, Ind. Eng. Chem., 20, 645-(1928).
9-87
-------
203. Yocum, J. E., R. L. Richardson, I. M. Saslaw, S. Chapman,
Proc. 49th Meeting APCA, Buffalo, 1956.
204. Kuczynski, E. R. Env. Sci. Technol., ^, 68-(1967).
205. Shikiya, J. M., R. D. MacPhee, paper presented 61st Annual
Meeting APCA, St. Paul, June, 1968.
206. Terabe, M., S. Oomichi, F. E. Benson, V. A. Newill and
J. E. Thompson, Jour. APCA, 17, 673-(1967).
207. Washburn, H. W., R. R. Austin, "Air Pollution" (L. C. McCabe,
Ed.) Chap. 72, 596, McGraw Hill Company, New York, 1952.
208. Nader, J. S. , J. L. Dolphin, Jour. APCA, £, 336-(1959).
209. McKee, H. C., W. L. Rolliwitz, Ibid., £, 338-(1959).
210. Philips Electronic Instruments, Mt. Vernon, N. Y.
211. Beckman Instrument Co., Fullerton, California.
212. Potter, L. B., "Comparison of Sulfur Dioxide Analyzers,"
paper presented 10th Analytical Methods Conference,
Feb. 1969, Oakland, California.
213. Bamesberger, W. L., D. F. Adams, TAPPI, 52, 1302-(1969).
214. Rodes, C. E., H. F. Palmer, L. A. Elfers, C. H. Norris,
Jour. APCA, 19, 575-(1969).
215. Givens, R., C. Gordon, J. English, paper presented West Coast
Regional Meeting National Council for Stream Improvement,
Oct. 14, 1969, Seattle, Wash.
216. Brody, S. S., J. E. Shaney, J. Gas Chroma tog. , _4, 42-(1966).
217. Melpar, Falls Church, Va.
218. Technicon Corporation, Tarrytown, N. Y. 10591.
219. Wilkens-Anderson, Co., Chicago, 111., 60651.
220. Precision Scientific Development Co., Chicago, 111., 60647
221. Whittaker Corp., San Diego, Calif., 92123
222. West, P. W., G. C. Gaeke, Anal. Chem., 28, 1816-(1956).
9-88
-------
223. Scaringelli, F. P., B. E. Salzman, S. A. Prey, Ibid., 39,
1709-U967).
224. Pate, J. B. , B. E. Ammons, G. A. Swanson, J. P. Lodge, Jr.,
Ibid., 37, 942-(1965).
225. West, P. W., Fe Ordoveza, Ibid., 34, 1324-(1962).
226. Zurlo, N., A. M. Griffini, Med. Lavoro., 53, 330-(1962).
227. Intersociety Committee, "Tentative Method of Analysis for
Sulfur Dioxide Content of the Atmosphere (Colorimetric),"
Health Laboratory Science, 6^, (4), 228-(1969).
228. Stratmann, H., Mikrochimica Acta, j6, 668-(1954).
229. Pate, J. B., J. P. Lodge, Jr., M. P. Neary, Anal, Ghent. Acta.,
28, 341-(1963).
230. Wilsdon, B. H., F. J. McConnell, J. Soc. Chem. Ind., 53,
385-(1934).
231. Huey, N. A., Jour. APCA, 18, 610-(1968).
I
232. Harding, C. I., T. R. Kelley, Ibid., 17, 545-(1967).
i
233. Keerigan, J. W., K. Snajberk, E. S. Anderson, Anal. Chem.,
_32, 1168-(1960).
234. Thomas, M. D., J. O. Ivie, J. N. Abersold, R. N. Hendricks,
Ind. Eng. Chem. Anal. Ed., 15, 287-(1943).
235. Scaringelli, F. P., K. A. Rehme, paper submitted for publication
Anal. Chem.
236. Gerhard, E. R., H. F. Johnstone, Anal. Chem., 27, 702-(1955).
237. Lodge, J. P., E. R. Frank, pps. 62-65, Am. Chem. Soc. Div.
Water and Waste Chemistry Preprints, Sept. 1963.
9-89
-------
CHAPTER 10
ON-GOING RESEARCH RaATED TO REDUCTION OF EMISSIONS
TABLE OF CONTENTS
Summary
Introduction
Emission Control Technology
Recovery Boiler Systems
Black Liquor Oxidation
Multiple Effect Evaporators
Lime Kilns
Miscellaneous Research
Research on Control of NSSC Sources
Research on Control of Sulfite Sources
Research Not Reported in the Literature
Cost and Effectiveness of Emission Control
Sampling and Analytical Techniques
Research Not Reported in the Literature
Control Equipment Development
Process Changes Affecting Emissions
Chemistry of Pollutant Formation or Interactions
Research Not Reported in the Literature
New Pulping Processes
Research Not Reported in the Literature
Control System Development
Kraft Systems
Sulfite Systems
Page No.
10- 1
10- 2
10- 2
10- 2
10- 9
10-14
10-16
10-17
10-27
10-28
10-36
10-39
10-40
10-48
10-50
10-54
10-57
10-68
10-68
10-71
10-72
10-72
10-83
10-i
-------
CHAPTER 10
ON-GOING RESEARCH RELATED TO REDUCTION OF EMISSIONS
SUMMARY
A number of the problems facing the chemical wood pulping
industry with respect to air quality improvement cannot be
resolved until further research points the way.
A search of the technical literature for the past five years
was undertaken. With few exceptions, it was decided that work
reported more than five years ago was presently incorporated
into practice, was under further development, or was found
unsuitable for practical application.
The format selected for presentation was that of an annotated
bibliography insofar as possible. Eight major! categories were
selected for presentation of the abstracts. Within each major
category the abstracts are arranged in sub-categories by year of
publication.
10-1
-------
10.1 INTRODUCTION
A number of the problems facing the chemical wood pulping industry
with respect to air quality improvement cannot be resolved until
further research points the way. Answers to other problems are
becoming clearer as a result of research presently underway.
Since one of the main objectives of this study was identification
of needed research, a survey of on-going research was a logical
starting point.
A search of the technical literature for the past five years
was undertaken. With few exceptions, it was decided that work
reported more than five years ago was presently incorporated into
practice, was under further development, or was found unsuitable
for practical application. In addition to the published literature
researchers known to be active in the field were contacted directly
and NCASI provided information on in-house research not published
in the open literature or not quite ready for publication. There
is some work underway at individual mills, at research laboratories
of the companies, and by equipment manufacturers which is proprietary
in nature and thus cannot be reported here.
The format selected for presentation was that of an annotated
bibliography insofar as possible. Eight major categories were
selected for presentation of the abstracts including emission
control technology, cost and effectiveness of emission control,
sampling and analytical techniques, control equipment development,
process changes affecting emissions, chemistry of pollutant
formation or interactions, new pulping processes, and control
systems development. Of course, there is some overlapping of
the categories and assignment of abstracts to some categories
had to be arbitrary. Within each major category the abstracts
are arranged in sub-categories by year of publication.
10.2 EMISSION CONTROL TECHNOLOGY
10.2.1 RECOVERY BOILER SYSTEMS
The recovery furnace and auxiliary equipment such as the direct
contact evaporator have long been identified as the major
contributors to atmospheric emissions of both particulates and
odorous gases. Electrostatic precipitators or scrubbers, or a
combination of the two have been used to reduce emissions.
10-2
-------
For sometime it has been known that the firing rate of furnaces,
above an,.pptimflm. level^ 'have a directr:ihfluencenon 'hydrbgen sulfide
emissions ifrbm the:furnace. ..It^has'.not "-been until recent years,
however, that research has revealed the effect of various operating
and process variables oh emissions from the recovery boiler system.
The most recent research reported as of the end of 1969, has been
very enlightening but has barely scratched the surface of the
problem. To meet the objective of reduced emissions with
modifications to existing systems a more complete understanding
is required. " • ••; ::.wo -'. >.:•-..-.-.- :>- -
Arhippainen, B.j and Westerberg, .E-.--H. , RECOVERY FURNACES AND THEIR
OPERATION, in Atmospheric -Emissions -from Sulfate Pulping (E. R«
Hendrickson/'^Ed. ) v"'April
A review is -presented of the recovery boiler operations in the
sulfate pulping process. The situation can be summarized as
follows: (1) significant odor release. (2) Where the black
liquor "-is- such v 'that -it -as •difficulti to -; -obtain high enough dry ••'••'•'-
solids concentration from a steam 'evaporator , or where economics
are grossly in favor of direct contact evaporation, efficient
black liquor -oxidation -would be •• necessary to limit odor emission.
(3) - ^Electrostatic : precipitators can be designed -and operated to
remove particulate -riatter -almost -as efficiently as one -wishes , •
( 4 ) ; •' Wet j scrubBers ; if installed 'for heat -recovery •- afford 'Some :
'additional "dus t ^removal,' ' but rwiH • :require : excessive caustic ; ••- •
addition t for :effidieri-b removal of ddorous gases i^-"The;-'xo'le of the
recovery rboi-ler-in'stheieconoirtics -of- 'sulfate pulping is briefly •
discussed.-" ^r-"~ .. jj^nj-isb Y—-"-' -';1?J •„ •> .--'- : ': - ••--^•- ~\ • '- • •'•"- '•--'-' •'-•''-
Gladding, Jataes N.j'fRECOVERY BOILER-CONTROL, TAPPr '49 (5) ,
112A, : (May, ; 1966)^. < ^ o; ;,:;,:: ,- - ; ., , v
In the last 30 years developments in both the boiler and
instrument industries have permitted the evolution of the recovery
system 'from all' that "was entirely oriented to the chemical process
through manufacture-of steam as• a by-product to the present time
when both steam generation and recovery of chemicals can be done
efficiently^ ^ At'the present \time' multiple units are being controlled
in a central -control';room with the~ instrumentation, as far as
combustion ^control :is concerned ^approximating that' of modern
power boilers.--- The efficiencies of the liquor systems have been
increased1 by" the development of-instrumentations which will more
precisely controt *he density of : the ;liquors entering and leaving
the boiler ^plant. /Accidents in irecent years have pointed up the
necessity for^additional 'safety controls on the auxiliary fuel systems,
for control systems ori: the-liquor evaporation, and for established
systems for emergency shutdown of the boilers. :
10-3
-------
Reiche, H., COMBUSTION OF SULFATE BLACK LIQUORS, Papier 21 (10),
593-7, (October 1967), and Papier 21 (11), 834-7, (November 1967).
A boiler manufacturer reports on the operation of soda recovery
furnaces, based en techniques currently in use. Initially he
discusses furnace construction and the properties that influence
the burning of kraft black liquors. The most advantageous combin-
ations of operating variables are described, incl. factors such
as the flow of concentrated black liquors through existing conduits
and orifices, pressures and temps, required in spraying thickened
liquors, size of droplets entering the furnace, temp, ranges within
the furnace, the draft required, and means used for introducing
fresh air. Based on these factors, the author deals with conditions
that could lead to a smoother furnace operation. Tabulated data
include the prods, obtained and the conditions required in burning
black liquors from straw, wood, and bamboo kraft cooks.
Byers, R. E., COMBUSTION AIR FLOW - ITS MEASUREMENT AND CONTROL,
TAPPI 50 (4), 52-8A, (April 1967).
Investments in new boilers and auxiliary equipment show a poor
return if they do not perform as an integrated unit, and frequently
poor performance is synonymous with unreliable air flow measurement.
Equally common is the conversion of a unit for multifuels which
has intricate operating procedures and unsafe fuel-air ratios. Few
plants escape the symptoms and complications of inaccurate air flow,
indicating that the importance of this measurement is not appreciated,
nor has the responsibility been clearly defined. There is no
perfect primary air flow elt. or universally accepted location,
and the configurations of ducts and dampers may not be conducive
to a good installation; the degree of acceptance of such an air
flow measurement is directly related to who is paying the bill for
field research to reinvent solutions to a repetitive problem.
Puhakka, L., SPECIAL CONSIDERATIONS IN KRAFT RECOVERY BOILER DESIGN,
Paperi Puu 49 (12) , 795-800, (December 1967).
The main functions of kraft recovery boilers are the generation
of steam and the regeneration of valuable chemicals. Recovery
units resemble conventional steam boilers, but require special
features owing to the particular fuel used (black liquor) and the
continuous accumulations on the superheater, boiler bank, and
economizer tubes, since such deposits will ultimately cause shut-
downs. In boiler design, special attention must be paid to wide
passages for flue gases; thermal efficiency is of secondary
importance. The most sensitive heating surfaces are located outside
the boiler, and the boiler itself should be as simple as possible.
Hints for the construction of various parts of the recovery unit
are given.
10-4
-------
Osborne, M. J., SUMMARY REPORT ON ACTIVITIES OF THE BLACK LIQUOR
RECOVERY BOILER ADVISORY COMMITTEE, TAPPI 52 (6), 1143, (June 1969).
The gradually evolving by-product utilization development of the
pulp and paper industry has been urged forward by the growing
concern for water and air pollution. Producers of essentially all
types of pulp are interested in the abatement of these pollutions
and, if possible, in converting waste effluents into revenue-producing
by-products. A number of successful operations are described„
Fundamental and practical research is continuing. Technology of
by-product production is necessary, but, for successful commercial
operation, this technology may be subordinate to such factors as
needs of outside industry, changing national and international
economies, changing consumer requirements, tariffs, subsidies,
political pressures, production costs relative to those of other
processes, and the like.
Vegeby, Anders, SCANDINAVIAN PRACTICES IN THE DESIGN AND OPERATION
OF RECOVERY BOILERS, TAPPI 49 (7), 103A, (July 1966).
The main differences between the Scandinavian recovery boiler design
and operation as compared to the Canadian and American methods are
that more of the heat from the combustion of the black liquor is
recovered as steam by using economizers cooling the flue gases to
about 260°F. The rating of the recovery boiler capacity is much
more conservative in Scandinavia than in the United States and
Canada to meet the normal increase in pulp mill capacity which will
normally be reached by small marginal investments in the pulp mill
but which are impossible in the recovery boiler department. At
least in Sweden, no direct contact type evaporators are used. To
get satisfactory operation for the economizer, hot precipitators,
placed between the boiler and the economizer, are used. In Sweden,
the black liquor concentration from the evaporation is between
60 and 65%. The differences in investments and operation costs
for the Scandinavian and the American and Canadian methods have
been calculated. The Scandinavian methods show a gross profit of
29-33%.
Anon., KRAFT RECOVERY BOILER FACES NEW CHALLENGE, Can. Chem. Process.
51 (12), 54-6, (December 1967).
A fluidized bed reactor linked to a conventional kraft liquor
recovery boiler can reduce the load on the recovery boiler. This
reduction in load is possible because the evaporator is able to
burn black liquor at solids contents near 30# (as opposed to the
60% solids required by the recovery boiler). Work is underway
aimed at replacing the black liquor recovery boiler with a
fluidized bed reactor.
10-5
-------
Tirado, A. A., RECOVERY UNITS FOR PULP MILLS UNDER 15 T./DAY,
Pulp Paper 42 (23), 26-8, (June 3, 1968).
The design and performance characteristics of kraft black liquor
heat and chemical recovery units are described which are particularly
designed for use in small mills such as those found in devg.
countries. Called RLP units, they include a direct contact
evaporator and a 2-stage combustion furnace and feature a low
capital investment.
Thoen, G. N., DeHaas, G. G., Tallent, R. G., Davis, A. S., EFFECT
OF COMBUSTION VARIABLES ON RELEASE OF ODOROUS COMPOUNDS FROM KRAFT
RECOVERY FURNACE, TAPPI 51 (8), 329-33, (August 1968).
The concentrations of odorous compounds in normal kraft recovery
furnace stack gas before and after the direct-contact flue gas
evaporators were determined under various operating conditions.
Results of this testing program indicated that odorous S compounds
can be decreased to negligible concentrations if sufficient excess
oxygen is available and good turbulence is obtained in the upper
oxidation zone of the furnace. Black liquor oxidation has no
significant effect on the amounts of odorous material leaving the
furnace, but the fineness of the black liquor spray does significantly
affect the concentrations of sulfur dioxide and hydrogen sulfide.
Belevitskii, A. M. , PURIFICATION OF KRAFT MILL GASEOUS EFFLUENTS
IN FINLAND, Bumazh. Prom. 3, 29-32, (march 1965).
In this report from a visit of a Russian delegation to several
modern Finn kraft mills, the author discusses the methods used
in Finland for the purification of gaseous wastes, and the attitude
of the Finn pulp industry toward the problem of air pollution.
In all Finn purification installations, emphasis is placed on the
recovery of solid particles as a valuable industrial material,
and on the recovery of heat from the gases. Air pollution is
regarded as a secondary, less important problem. The Finn technical
people differ in their opinion as to the way to achieve chemical
and heat recovery, and in the 6 mills visited by the delegation,
different methods and equipment are used for this purpose.
The purification of gases is done in one, two, or three stages, but
all installations have a common characteristic, i.e., the use
of electrofilters (which are operated automatically). Because of
the strict control of the soda recovery furnace variables, these
filters operate under standard and constant conditions, and
achieve a high purification efficiency. According to Finn specialists,
the "hot" electrofilters are more efficient, but they are more
difficult to operate and control, and for this reason "warm"
filters are used more frequently. Scrubbers are the second
10-6
-------
important component of Finn purification installations. They are
installed either ahead of the electrofliters, or constitute one
of the last elements of the system. The main role of the scrubbers
is the utilization of heat of the hot gases (a description is
given of the design and operation of several scrubbers}. The
"tail" scrubbers also absorb the foul-smelling S compounds,
although no data are available as to their deodorizing efficiency.
There are no regulations in Finland concerning the control of
air pollution. Consequently, Finn mills have no special installations
for the removal of foul-smelling compounds from gaseous effluents
of the digester and black liquor evaporation rooms. The efforts
are concentracted on the prevention of water pollution.
Dyck, A. W. J., IS YOUR ELECTROSTATIC PRECIPITATOR OPERATING AT
MAXIMUM EFFICIENCY?, Am. Paper Ind. 48 (1), 63-4, (January 1966).
Methods and applications used in 2- and 3-dimensional model studies
of electrostatic precipitators used in air pollution control are
briefly examined. The studies concern the determination of optimum
design of a precipitator for a specific mill installation with
respect to uniform gas flow and maximum operating efficiency.
Lund, H. F., Air Pollution Criteria for Industrial Plant Equipment,
U. S. Public Health Service Publication No. 1649, 1966 (pages 207-13)
Economic and technical aspects of plant equipment for pollution
control are reviewed. Special attention is directed at high
efficiency scrubbers and electrostatic precipitators. Pollution
control costs for the various industries most affected are
considered.
Blosser, R. O., Cooper, H. B. H., Jr., TRENDS IN REDUCTION OF
SUSPENDED SOLIDS IN KRAFT MILL STACK, Paper Trade Journal 151 (11),
46-51, (March 13, 1967).
A survey of secondary wet scrubbing practices in kraft mill air
pollution control systems showed that relatively low pressure drop
devices may produce a 50-80% reduction in particulate emission from
the primary precipitators. The percent reduction is somewhat less
when these devices are employed behind Venturi recovery units.
Removal efficiency was independent of the type of scrubber used over
the range of inlet loadings observed. Final effluent quality was
related directly to scrubber inlet grain loading. While effective
scrubbing can reduce particulate fallout in the area around a
mill, it may also reduce the height of plume rise. Hence dispersion
is reduced and an odor problem may be accentuated. It is difficult
to predict that any real benefit in either fallout or total emission
is obtained with secondary scrubbing behind some of the new precipi-
tators which are capable of 96 to 99% particulate removal efficiency.
6 ref.
10-7
-------
Blosser, R. O. , Cooper, H. B. H.f Jr., PARTICULATE MATTER REDUCTION
TRENDS IN THE KRAFT PULP INDUSTRY, Pulp Paper Mag. Can. 69 (3),
55-61, (T77-88) , (February 2, 1968).
Recent surveys indicate a trend to reducing particle emissions
in kraft mills by installing high-efficiency venturi scrubbers on
lime kilns and electrostatic precipitators with rated efficiencies
exceeding 97.5% on recovery furnaces. A recent field study of
low-pressure-drop secondary scrubbers installed behind primary
recovery devices on kraft furnaces showed them to achieve particle-
collection efficiencies of 50-80%. Although secondary scrubbers
reduce particle emission and fallout in the vicinity of mills,
they may also significantly reduce the height of plume rise. 6 ref.
Mita, A., COMPLETE TREATMENT OF PULP WASTE LIQUOR AND UTILIZATION
OF BY PRODUCTS, Kami-pa Gikyoshi 22 (10), 515-32, (1968).
When black liquor was first baked and then burned in an oxidizing
atmosphere, the resultant ashes (I) contained 80.7% Na CO and 17.1%
Na SO , but neither Na S O nor Na S. The ashes (II) obtained in
a similar manner from the spent liquor of the neutral sulfite
semichemical (NSSC) process contained 59.6% Na CO_ and 32.3% Na SO .
Sulfitation of I made it possible to reuse I for NSSC and Na-base
acid sulfite cooking liquor. Carbonization of an aqueous solution
of II in NH converted both Na^SO and Na CO to NaHCO , which was
recovered from the mother liquor containing TNH ) SO . The NSSC spent
liquor was subjected to evaporation and combustion to yield an aerosol
containing Na. Air oxidation of this aerosol together with SO gave
anhydrous Na SO powder of 95-8% purity. It is proposed to use
H S liberated from the petroleum refining process as a kraft cooking
liquor together with NaOH.
Jones, K. H., Thomas, J. F., Brink, D. L., CONTROL OF MALODORS
FROM KRAFT RECOVERY OPERATIONS BY PYROLYSIS, J. APCA 19 (7) ,
501, (July 1969).
The major source of malodorous emissions which emanate from kraft
mills is the recovery furnace and its associated direct contact
evaporator. The primary reasons for this problem are gross furnace
overloading and/or inadequate design. Existing recovery furnaces
are incapable of carrying out, to an acceptable degree of completion,
the complex sequence of physical and chemical steps which describe
combustion. These steps are evaporation, sublimination, pyrolysis,
recombination, and oxidation. A simplified odor model is presented
which establishes the constraints which must be placed on the combustion
phase of the recovery operation if environmental concentrations of
malodorous compounds are to be held below their respective threshold
10-8
-------
odor levels."-The-pyrolysis and recombination steps of
combustion have-been isolated for study,because they encompass
the reaction mechanisms responsible for malodorous compound
production. The findings of the steady state pyrolysis study
indicate that the optimization of pyrolysis appears to be a
vary desirable process technique for abating malodorous
emissions from kraft mills. The comprehensive data obtained
in the study has engendered the current design and construction
efforts toward a pilot plant operation.
10.2.2 BLACK LIQUOR OXIDATION '
-Nearly-all of'the emission of H S from the direct contact
evaporator "and much 7of.that from the'multiple effect evaporators
can be: traced'-directly to "the presence of Na S in the black
v liqu'or. -Work done in^the late-1930's demonstrated, that
oxidation'of"the sulfide to thiosulfate reduced the chances
"-of H^S formation ; appreciably.-Much ^work has been done on
black liquor oxidatiom;since:that "time. Numerous BLO systems
have been developed to meet specific problems. As of late
1969, however, gaps in our knowledge still existed. Problems
. of understanding!'the>"mechanisms-of oxidation, foaming,
' *c -economics',' and£rey6Esiqn2are^some'.6f: those.istill remaining to
be solved. Since BLO will probably continue to be of importance
; :•••••' as- a; means ^.Qfiodor ^reduction 'for ;some -time1 to; come, these gaps
rHendricksony ;Ev .R.:r:-and;-Haraing, C.r.I. ; BLACK LIQUOR OXIDATION
AS;A'METHOD FOR REDUCING AIR POLLUTION FROM.SULFATE PULPING,
J. APCAel4 (12) ',-487-90y (December 1964) ...
The sources of-odorous-air'pollutants from kraft pulping
operations are discussed. One of the major sources is
improper operation of the recovery furnace. Odors from this
source can be reduced considerably by oxidation of the black
.liquor prior to evaporation and burning. This procedure has
been used.with considerable success in the NE and NWsections
of the^U.' S. -However', kraft:pulp production in areas where
southernopine^is the basic raw material results in a high
degree'pof--foaminess of .the black liquor making the above
procedure impractical. Various attempts to oxidize black liquor
resulting from the pulping of southern pine have met with
only "-limited success. Various procedures for oxidizing black
liquor;'-are discussed and the ^results of stack sampling in
U. S.:'^pulp" mills with and without an oxidation unit are
presented.'-19 ref; •: ::
10-9
-------
Murray, F. E., CONTROL OF ODOR IN KRAFT PULPING, World Paper Trade
Rev. 162 (11) , 802, 804, (September 10, 1964).
The source of odor at a kraft mill (sources are illustrated by
chemical reactions describing the preparation of cooking liquor
from Na sulfate and the cooking and recovery cycles) are discussed,
and possible measures (e.g., oxidation of black liquor) to control
or eliminate kraft pulping odors are outlined briefly.
Murray, F. E., THE OXIDATION OF KRAFT BLACK LIQUOR, in Atmospheric
Emissions from Sulfate Pulping ( E. R. Hendrickson, Ed.), April 1966.
A review is presented of kraft black liquor oxidation systems.
Included are discussions of the theoretical mechanisms, catalysts,
and the kinetics of the reactions. The sources which might be
affected by the process of BLO are described. Descriptions are
presented of the various types of oxidation systems used for both
weak and concentrated liquor. An economic analysis and citation
of research needs complete the discussion.
Alferova, L. A., and Titova, G. A., OXIDATION OF SODIUM SULFIDE AND
MERCAPTIDE IN BLACK LIQUOR, Bumazh. Prom. (10) , 5-6, (October 1966) .
The recommended method for deodorization of foul-smelling kraft
mill effluents is a two-stage oxidation, first by aeration, then
by chlorination. The spent air from the first stage is purified
jointly with the gaseous wastes. However, if oxidation is carried
out so as to convert the sulfides and mercaptides to sulfates and
sulfonic acids, respectively, the formation of foul-smelling
compounds and their evoln. can be prevented. To determine the best
conditions for such oxidation, aqueous solutions of hydrogen
sulfide, methyl mercaptan, and of their Na salts, were oxidized
by aeration at various air flow rates, various temps., and within
a wide range of pH. For all solutions, the rate of oxidation was
determined mainly by temperature and the surface area of contact
between the solution and the oxidizing agent. Both the hydrogen
and the hydroxide ions had a catalytic action, and the course of
the reaction, as well as the end products were determined by the
pH. To achieve a large contact area, aeration should be done in an
app. of the atomizing type. The recommended conditions are a
temperature of 80-100°C., and a pressure of 4-6kg/cm. . Under these
conditions, the reaction is of the zero order, and its rate is
determined by the ionic strength of the black liquor and its pH.
The final pH must not be lower than 12.6, as at a lower pH other
oxidation products (thiosulfates, sulfites, polythionates, etc.),
predominate. Also at a pH below 11, MeSH is partially converted
to methyl and hydroxide sulfide, the latter escaping from the
solution. The oxygen consumption for oxidation under optimum
conditions is approximately equal to the theoret. calcd.
10-10
-------
Owens, V. P., TRENDS IN ODOR ABATEMENT FROM KRAFT MILL RECOVERY
UNITS, Paper Trade"J. 152 (33), 52-4, (August 12, 1968).
New developments in odor abatement in kraft mill chemical recovery
units are discussed, including direct-contact evaporation of the
black liquors using clean air rather than flue gases, elimination
of direct-contact evaporation from the recovery cycle, and the use
of a black liquor oxidation stage prior to direct-contact evaporation,
7 ref.
Zerebeski, O. H., HOW KAMLOOPS [PULP & PAPER CO. LTD„, KAM-LOOPS,
B. C.] STOPPED "Mflll] OtDor]", Pulp Paper 42 (25), 40-3, (June 17,
1968).
The weak black liquor oxidation system at the mill is described.
Basically, the system consists of a reactor tank continuously fed
with weak black liquor. Low pressure compressed air is injected
into the bottom of the reactor through a dispersing ring, causing
the formation of foam which rises to the top. A mech. foam breaker
separates the gaseous and liquid phases. The gases are discharged
to the atmosphere through roof vents. Oxidized liquor is drawn off
from the bottom of the reactor. Startup problems were experienced
and the system had to be enlarged before a satisfactory oxidation
efficiency of 95% was attained (weak black liquor sulfide loading
below 8.0 g/liter) installation of a stilling tank following the
reactor tank eliminated pumping problems with the oxidized liquor.
Laasonen, E., EXPERIENCE WITH BLACK LIQUOR OXIDATION AND ODOR
CONTROL AT THE KUUSANNIEMI SULFATE MILL [OF KYMIN OY.], Paperi Puu
49 (4a), 217-19, 221-6.
A review of pertinent research work reported in the literature
is followed by a report on the R & D work done at this Finn kraft
mill, supplemented by 2.5 years of operating experience with the
liquor oxidation system. By means of special measures, both odor
and corrosion problems have been largely eliminated at the mill.
10 ref.
Menzies, M. A., OXIDATION OF PINUS RADIATA KRAFT WEAK BLACK
LIQUOR, Appita 22 (1), 16-24 (July, 1968).
Oxidation studies on weak black liquors have shown certain advantages
due to S stabilization and reduction of odor. However, the practical
oxidation of black liquor has not found wide acceptance because of
difficulties caused by excessive foam formation. A study was made of
the oxidation of Pinus radiata kraft weak black liquor using a
10-11
-------
falling-film type of contacting system. The liquor descends over
the face of a vertical sheet of packing cocurrently with a stream
of air. Recirculation of the liquor allows the simulation of an
oxidation tower having the height required on a mill scale. Excessive
foam formation was not experienced with the unit used when oxidation
rates were up to 4 Ibs. Na sulfide/hr. over a packing surface of
100 sq. ft. Effect of gas velocity, liquor flow rate, sulfide
concentration, and the configuration of the packing surface were
studied, and a mathematical model of the oxidation process was
developed based on the 2 film resistance theory of absorption.
This model was appl. in the design of a mill scale unit. The
factors that require consideration for designing an economical
pract. system are discussed. Publ. data of the oxidation reactions
are also considered in relation to the results obtained in this
study. The layout of the lab. app. and details of the packing
strips are depicted, and symbols used by the author are given in a
glossary. 12 ref.
Kacafirek, Stanislav, Kubes, Jiri, Racek, and Vaclav, PRACTICAL
EXPERIENCE WITH OXIDATION OF BLACK LIQUOR IN THE STETI PULP MILL,
Papir Celul 23 (7), 194-6, (1968).
The main systems for the oxidation of black liquor are mentioned
and the equipment installed in the cited pulp mill by BT-Metoder
Stockholm is described. It consists of 2 oxidation towers with
3 perforated plates through which air is passed countercurrently.
The foam is passed into a storage tank equipped with a device for
mech. breaking of the foam. The height of the pipe from the foam
layer on the top of each tower to the tank is 1700 mm., which was
found to be optimal. At present, the equipment operated with a
load of 3.3 tons of liquor/m. /hr. The air-liquor ratio is
1:60-5 for liquor contg. 16% dry matter; this concentration is
advantageous because the sepn. of sulfate soap does not take place.
The course of chemical reactions during oxidation of black liquor
and their importance for the reduction of losses of S and limiting
of equipment corrosion is discussed. Analytical results characterizing
the operation of the equipment as well as those of corrosion tests
of oxidized and nonoxidized liquors performed by detn. of wt. losses
of steel samples and by polarization measurements are also given.
10-12
-------
Galeano, S. F. and Amsden, C., WEAK BLACK LIQUOR OXIDATION WITH
MOLECULAR OXYGEN, Paper presented at the 62nd Annual Meeting of
APCA, New York, June 1969.
Oxidation of black liquor (BLO) is one of the most effective
ways to control odor from the operation of kraft pulp mills.
Maximum reduction in atmospheric emissions is obtained when
the weak black liquor is oxidized. Up until this time, the
foaming properties of weak black liquor from pulping southern
pine have hindered the development of successful oxidation
schemes for weak liquor.
The possibility of using molecular oxidation as a means of oxidizing
weak black liquor in a pipeline was set forth some ten years ago.
Economic considerations weigh heavily, however, in the use of
pure oxygen. The decrease in costs of tonnage oxygen has been
dramatic over the past few years. Also, the possibility of new
markets for tonnage oxygen in waste treatment systems could
further enhance the economic balance over using the gas.
An advantageous market condition for a pipeline supply of oxygen
to the new kraft mill of Owens-Illinois at Orange, Texas, made a
study of a pure oxygen system appealing. A complete trial was
planned in which all of the effects (BLO) in the system could be
evaluated. The paper describes the system tested at the Orange
mill in which all of the weak kraft black liquor' was successfully
oxidized in a tubular reactor at production levels ranging from
700 to 1,000 tons of air dried pulp per day. For this installation,
it was estimated that the breakeven point in comparing the system
with a conventional system would occur where oxygen costs were
below $8.50 per ton. The trial was conducted during October and
November, 1968.
Obviously, the design and installation of air oxidation units is
mainly a problem to be solved for each individual mill. The
implementation of a tonnage oxygen system is likewise an individual
mill decision and will depend largely on the price and availability
of oxygen.
Martin, F. R. , IMPROVED ODOR CONTROL THROUGH SECONDARY OXIDATION
OF KRAFT BLACK LIQUOR, Pulp and Paper 43, (June 1969).
Oxidation of kraft black liquor is an industry accepted method for
preventing the evolution of H S during direct contact evaporation
by recovery furnace flue gas. This paper reports that H S evolution
may occur in spite of complete weak black liquor oxidation. During
studies of H S emissions from direct contact evaporators, reversion
of oxidized liquor in multiple effect evaporators became apparent.
A secondary oxidation step which results in improved odor control is
described.
10-13
-------
Shah, I. S. and Stephenson, Wayne D., WEAK BLACK LIQUOR OXIDATION
SYSTEM: ITS OPERATION AND PERFORMANCE, TAPPI 51 (9), 87A, (September
1968) .
After a thorough analysis of the advantages of weak and strong black
liquor oxidation and after an evaluation of weak black liquor
oxidation in a pilot plant (capable of handling 100 gal/min of liquor
equivalent to 50 tons/day of pulp production), a full-scale weak
black liquor oxidation system was installed. The system is designed
to handle 400 gal/min of weak black liquor at 16-17% solids--
concentration and 4.0-6.0 g/liter of sodium sulfide content. The
wood furnish is a mixture of pine and hardwood, with pine content
varying to a maximum of 60%. The commercial system has successfully
operated since startup and provides essentially 100% oxidation
efficiency, even with variations in liquor flow and sodium sulfide
content from 300 to 475 gal/min and 2.3 to 6.6 g/liter,
respectively. The total operating power, including fan, pump, and
foam breakers is less than 100 hp. The extensive and stable foam
that is formed during oxidation is efficiently handled and causes
no operating problems. As a result of the oxidation of weak black
liquor, the sulfidities of green and white liquors are raised from
18.2 to 27.1% and 22.6 to 27.9%, respectively. The total lime
requirement is reduced by 0.085 Ib of lime per gal/min of green
liquor, a 15.4% reduction. The amount of hydrogen sulfide leaving
the recovery furnace stack is reduced by 98.5%. The biochemical
oxygen demand of the multiple effect evaporator condensate is
reduced by 27% and the pH raised from 6.5 to 9.0, thus making the
175 gal/min of the evaporator condensate suitable for reuse in the
pulp mill. Overall, a significant reduction in odor and chemical
loss is achieved, as a direct result of the weak black liquor
oxidation system.
10.2.3 MULTIPLE EFFECT EVAPORATORS
The multiple effect evaporators are usually classified as a low
volume, high intensity source of odors in a kraft mill. Emissions
from this source are variable. Operating and process variables which
affect emissions are largely unknown, but BLO may result in a reduction
of some of the odorous sulfur compounds. In some of the newer
recovery system designs, the direct contact evaporator is eliminated
and the black liquor is evaporated to high solids content in the
multiple effect evaporators. Operational problems may result.
Means for maintaining the high evaporation rate and a better under-
standing of the effects of operating and process variables on
emissions need to be investigated further.
10-14
-------
Droy, M., MODERN METHOD OF CONCENTRATING BLACK LIQUORS, Papier
Carton Cellulose 17 (2), 77-80 (March/April 1968).
A newly developed multiple effect evaporator for the concentration
of black liquors is described which employs a combination "upflow-
downflow" system. The upflow tubes merely serve to facilitate
the diffusion of the liquor in the downflow tubes. This obviates
the need for circulation pump at each stage. A special reheater
is used to heat the liquor between successive stages. The new
system features circuit simplicity, ease of maintenance, rapid
startup, and a minimum control equipment requirement.
Arhippainen, B., Jungerstam, B., OPERATING EXPERIENCE OF BLACK
LIQUOR EVAPORATION TO HIGH DRY SOLIDS CONTENT, TAPPI 52 (6),
1095 (June 1969).
Operating practice in most modern Scandinavian kraft mills includes
evaporation of the black liquor to 60-65% dry solids content in
multistage evaporators and direct firing of the strong liquor.
In most cases, the selection of this system in preference to a
direct-contact evaporator system can be justified by economical
consideration alone, with no regard to air pollution. Operating
experience with multistage evaporation plants operating at high
dry solids content is reported. The heat transfer characteristics
of black liquors are related to reported physical properties, and
the importance of increasing boiling point rise with increasing
dry solids content is pointed out. The scaling properties of
black liquors at high dry solids content is related to their chemical
properties. The importance of maintaining a low temperature in the
high dry solids effect, a reasonable content of residual alkali,
and low contents of sodium sulfate, carbonate, and fiber in the
black liquor, efficient soap separation, and high white liquor
clarity, in order to limit scaling, is stressed. It is indicated
that the optimum product dry solids content may be higher than the
62-63% presently achieved with natural circulation evaporators,
because of favorable secondary effects in the recovery boiler.
Some Scandinavian mills use forced circulation in the high dry
solids effect, whereby 65-67% dry solids content can be reached.
The use of forced circulation in the high dry solids effect is
not always justifiable in Scandinavia, but it is assumed that
forced circulation should be a first choice in many areas with
lower power costs.
10-15
-------
Stacie, J. H., Wilhelmsen, L. A., MAINTAINING MULTIPLE EFFECT
EVAPORATION RATE, TAPPI 52 (7), 1278, (July 1969).
A material containing polymethacrylate as the active ingredient
was added to kraft black liquor feed to multiple effect evaporators
at various rates, in an attempt to reduce tube scaling and prevent
loss of heat transfer. Although there is substantial evidence
that this material reduces the rate of scale formation, the evaluation
is clouded by the usual operating variations encountered in black
liquor evaporation. An increase in overall evaporation capacity
was found when this material was added continuously in conjunction
with scheduled water boil-outs and good maintenance of the associated
equipment.
Morrison, J. L., COLLECTION AND COMBUSTION OF NONCONDENSIBLE DIGESTER
AND EVAPORATOR GASES, TAPPI 52 (12) , 2300-, (December 1969).
Vaporspheres have successfully contained the odorous, noncondensible
organic vapors from both batch and continuous digesters and from
black liquor evaporators. The vaporsphere systems not only reduce
the local mill odor emission but also reduce the fuel requirements
of the lime kiln in which the gases are burned. A vaporsphere,
or gas accumulator, is a 27-ft. steel sphere with a lightweight-
fabric diaphragm attached inside around the equator of the sphere.
Gases enter through the bottom of the vaporshpere and are retained
under the diaphragm which "floats" up and down on the gas cushion.
As the vaporsphere fills, an automatic valve discharges just
enough gas to equal the net flow generated for each cooking cycle.
The gases leaving the vaporsphere are then passed through a
scrubber.
10.2.4 LIME KILNS
Particulate losses from lime kilns represent a direct loss of
a valuable chemical and thus have stimulated considerable research
and development activity for emissions control. Little is known,
however, about the lime kiln as a source of odors and SO . The
origin of the odorous gases reported by some investigators has not
been satisfactorily demonstrated. Many workers report no emission
of SO even when noncondensibles are being burned in the kiln.
This phenomenon also has not been explained adequately. Fluidized
bed calciners as substitutes for kilns have not been adequately
evaluated with respect to emissions and no information appears to
be available regarding the use of such systems for destroying
noncondensibles.
10-16
-------
Taylor, C. E., LIME KILNS AND THEIR OPERATION, in Atmospheric
Emissions from Sulfate Pulping (E. R. Hendrickson, Ed.),
April 1969.
The lime kilns of the kraft pulping industry constitute an integral
part of the causticizing and chemical recovery processes. The
application of emission control systems to the kiln has been
typified by evolutionary changes. The current systems in use are:
impingement scrubbers and higher energy venturi scrubbers, A
description of a typical impingement scrubber installation is
given, followed by operational and cost data applicable for a
kiln serving a pulp mill of about 300 tons/day capacity. Several
factors influence the scrubber system operation. Technically,
from an air quality control point of view, this scrubber system
does a very adequate job when operated properly. However from
an operator's view, these scrubbers have some limitations and
disadvantages, specifically the deposition of calcium resulting
in plugged screen plates, and the problem of water balance, A
typical venturi scrubber system is described; operational and cost
data are presented. Reports indicate very low maintenance for
this equipment with minimum attention from the operator. The
quantity of odor constituents emitted from lime kilns is generally
small in comparison with other sources in the pulp mills. As
improvements are made in over-all odor control, the factors
influencing odor emission from the kilns will have to be thoroughly
evaluated in order to minimize their formation and release»
Possible sources of sulfur compounds for the kilns system are
considered. Conclusions drawn from survey work in kiln odor control
are presented. The best method of assuring minimum odor release
appears to be a combination of low sulfur fuel, good combustion
control, and adequately washed lime mud. Recent developments
with the fluidized bed calciner as a substitute for the kiln are
discussed. Research and development needs for control in this
area are listed.
10.2.5 MISCELLANEOUS RESEARCH
Amarinel, E., Weiss, E., Brasat, R. , DEODORIZATION
TRIALS FOR KRAFT FLUE GASES, Celuloza Hirtie,15 (1)
23-9 (January 1966}.
Laboratory and pilot-plant trials with kraft process-
derived gaseous effluents are reported. Both the flue
gases and the black liquor itself were oxidized, and
the gases were tried successively with solutions of
Ca hypochlorite and NaOH. Each step resulted in a
reduction of odiferous noxious components. Results
indicated that the process is applicable on an ind.
scale and could remove more than 95% of the volatile
S compounds. 21 refs.
10-17
-------
Alferova, L.A., Panova, V.A., and Titova, G.A.
DEODORIZATION OF EFFLUENTS FROM THE MANUFACTURE
OF KRAFT PULP, Bumzah, Prom.38 (6) 5-8 (June 1963).
Analyses of black liquor evapn. effluents and of
digester relief condensate led to the conclusion that
the deodorization of these two effluents should be
carried out separately, because of the different
cpn. of the S compounds. The odor of the evapn.
effluents which contain mainly H S, and MeSH can be
controlled by chlorination or by aeration and chlori-
nation. On the other hand, the condensates usually con-
tain also Me S, Me S , and small amounts of other S com-
pounds., and their deodorization by extn. or distn.
presents the possibility of recovering some of the S com-
pounds . Digester relief condensates from continuous cooks
contain more MeSH than H S, and little or no turpentine
(in such cooks, the bulk of turpentine remains in the
black liquor). Experimental data presented show that the
S compounds can be removed from the condensates by extn.
with sulfate turpentine. For example, a condensate
originally containing 52 mg. Me S and 11 mg Me S /liter,
contained no S compounds fig. three extns. with turpentine.
Equally good results were obtained by fractional distilla-
tion. Complete deodorization of the black liquor evapn.
effluents was obtained by aeration in a. packed tower at an
air consumption of 2 cu.m./ 1 cu.m. effluent, fid. by the
removal of residual odor by chlorination, at a Cl consump-
tion of 0.7 - 8 kg./t. pulp produced. The deodorized
effluent contained 0.7 mg Cl/liter. Diagrams are given of
installations for the two-stage purification of evapn.
effluents, and for the extn. and distn. deodorization of
relief condensates.
Wulfinghoff, M. Disposal of Process Wastes - Liquids, Solids,
Gases, Chemical Publishing Co., New York, 1968 (240 pages).
The 18 separate contributions to this symposium dealt with
industry's contributions toward maintaining a clean environ-
ment, developments in chemical effluent reclamation, waste
treatment in the chemical industry, ion exchange as a unit
operation in treatment of industrial waste waters, removal
and recovery of proteins. IR spectroscopic detn. and
removal of oil contaminants (emulsions) from waste waters,
biodegradable detergents, reclamation of radioactive waste
10-18
-------
watery encapsulation ofunuclear wastes, air pollution and
its control, -treatment of waste air and gases in the process
inds., catalytic afterburning of industrial waste gases, the
Bayer double-contact process for sulfur dioxide conversion
into trioxide, chem. eng. methods for removing inorganic
emissionsT removal of industrial wastes by incineration,
ion-exchange and extn. methods in-the rare-metal inds., and
a report on progress made ,during 1964 - 1966 in industrial
waste treatment. A selected bibliography, a glossary of
terms, conversion tables, and a subject index are appended.
Shah, I. [KRAFT] PULP PLANT POLLUTION-CONTROL,
Chemical Engineering Progress 64., (9.) 66-77 (Sept. ,
1968).
A detailed description is given of the kraft pulping
process ,- aixd the steps which are being taken in each
stage of the process- to eliminate the emission of
contaminants such as hydrogen sulfi.de, mercaptans,
or methyl sulfides to the atmosphere or to waste
waters. 17 ref.
Roberts, D PRINCE GEORGE PULP & PAPER. LTD. ACHIEVES
PRODUCTION TARGET; ODOR AND EFFLUENT CONTROL- ARE MAJOR
CONCERNS; PROCESS AND EQUIPMENT DETAILS, Pulp and Paper
Magazinerrf.-Canadan;6.7 -(J-O) 75 -.88 .(Oct.- 1966).
A detailed illustrated description is given of the, new
$84 mi4rlion k-raft-.mill-^o.f Prince , George Pulp & Paper
Ltd. in 43ie -interior of 3 .•£.,, which. has a pulp capacity
of 360 and -a- bag paper, and ..linerboard capacity of 300
daily t. A process flow chart is included. Highlighted
are the extensive installations for odor control (a
Trobeck-Ahlen oxidation and Lundberg-Ahlen vapor-treat-
ment system utilizing, bleach plant- effluent for gas
cleaning) -and for effluent treatment, (save-all filter
centrifugal dewatering, soapy froth skimmer, aeration
lagoons, etc. ) .
Pucek, ,B^. CONTROL BY. OPTIMIZATION IN THE PULP INDUSTRY,
Sb. Vyskum^ Prac Odboru Celulpzy -Papiera (10) 219-28 (1965)
The principles of optimization control, i.e., cases-when
the relation between the variable controlled and the con-
trolling factor can be represented by a curve with a max.
10-19
-------
is discussed in general terms. Such control can be achieved
manually or automatically. At the Pulp s Paper Research
Institute in Bratislava, a control instrument was developed
which can achieve optimization and operates on the basis of
a compensating recorder. The control system was applicable
to the production of dimethyl sulfide from spent pulping
liquors and to the combustion of hydrogen sulfide in the
process of spent liquor chemical recovery. The operation
of the system is described and its efficiency illustrated
by a graph. 6 ref.
Misra, N.D. SODA RECOVERY; THE LIFE-BLOOD OF THE
PAPER INDUSTRY, Indian Pulp Paper 22 (12) 679-81
(June, 1968).
The nature of soda losses when blowing the digester
and in stacks, in the brown stock washing system, in black
liquor evaporators, in thin black liquor, and in heat re-
covery furnaces and causticizers are all discussed briefly.
The vital importance of good soda recovery is emphasized.
Lenz, W., Tirado A.A. MEXICAN KRAFT MILL USES OBSERVERS
TO CHECK ITS ODOR CONTROL PROGRAM, Paper Trade Jour. 150
(34) 64, 68 (Aug. 1966).
A program for evaluating the effectiveness of odor control
at the kraft pulp mill of Loreto Y Pena Pobre (Mexico City)
consists in getting weekly odor reports from 15 to 20
"observers" chosen among people who are not connected other-
wise with the mill, who live within a 7 km. radius of the
mill, and who in many cases, have frequently complained
:about the mill's odor.
Landry, Joseph E., and Longwell, Daniel H. ADVANCES IN AIR-
POLLUTION CONTROL IN THE PULP AND PAPER INDUSTRY, TAPPI 48 (6),
66-70 (June, 1965).
Considerable progress is being made in the application of
existing and the development of new control measures. Equip-
ment available for maintaining air quality in the vicinity of
kraft pulp mills, advances in the control of odors and particu-
lates, and some analytical methods used for detecting the
efficiency of control measures are summarized. 10 ref.
10-20
-------
Institute of Paper Chemistry, PROGRESS IN ALKALINE
PULPING (1966) , TAPPI 51 (6) 75-87A (June 1968).
This bibliographical survey of the indicated litera^
ture reviews advances in the manufacture of alkaline
pulps from woody and nonwoody fibers, the complete
pulping/recovery cycle (white liquor, black liquor,
chemical recovery, and by-products), bleaching of
alkaline pulps, new mill constructions, and expansions
(modernizations), corrosion problems, and stream and
air pollution. 346 ref.
Harding, C. I., Landry, J. E./ FUTURE TRENDS IN AIR
POLLUTION CONTROL IN THE KRAFT PULPING INDUSTRY,
TAPPI 49 (8) 61-7A (August 1966).
The reasons for the mounting pressure on the kraft
industry to reduce atmospheric emissions are reviewed.
Measured gaseous and particulate emission figures are
presented together with recent advances in emission
control technology as bases for proposing the types and
extent of emission control to be utilized by the pulp
industry during the next five years. 1 ref. |
Grossmann-Cooper> Anna, Sulfur Oxides and Other Sulfur
Compounds: A Bibliography with Abstracts, Public Health
Service Publication No. 1093, 1965 (383 pages).
Nearly 1000 annotated references are arranged under 13
subject categories, indexes of authors, titles (separated
for each of the 13 subjects), and geographical locations
are appended. Emphasis is on sources, effects, and
monitoring of air pollution caused by S compounds.
10-21
-------
Freyschuss, S-, PULP MILL WASTE IN SWEDEN, Pulp Paper
Mag. Can. 68 (2), T35-9, (February 1967).
Water and air pollution (Odor) problems of Swedish pulp
mills (48 Sulfite, 34 kraft installations) are surveyed,
along with control measures taken (sedimentation, basins,
sediment treatment, waste water discharge and diln., etc.)
and contemplated. Discharges from modern mills are only
about 50% of what they were 5 years ago, owing largely to
advances in pulp washing methods and equipment and the
introduction of continuous pulping processes. Further
improvements may be expected in sulfite pulping from the
increased use of soluble-base liquors, and in kraft pulp-
ing from reduced water consumption. The latter may be
held so as low as 75 cu.m/t of unbleached pulp, which is
only about 1/3 of the average for present Swedish kraft
mills, but the present profitability limit for the rend.
of washing losses would seem to be a loss of Na sulfate
of about 15 kg./t. of pulp.
Galeano, S. F., REMOVAL AND RECOVERY OF SULFUR DIOXIDE
IN THE PULP MILL INDUSTRY, Ph.D. Thesis, University of
Florida, 1966 (254 pages).
The technical and economic feasibility of a purification
system for the removal and recovery of SO from pulp mill
waste gases was studied. An experimental pilot plant
consisting of a Venturi scrubber and a cyclone was used.
Two different scrubbing solutions were employed: a car-
bonate solution (simulating a NSSC mill) and weak black
liquor (simulating a kraft mill). With the carbonate
solution, SO removals in excess of 90% were obtained,
the system being both technically and economically sound.
With the weak black liquor scrubbing solution, economy
becomes a matter of the particular conditions in indi-
vidual mills.
Galeano, S. F., Adams, F.A., AS DEMAND FOR POLLUTION
CONTROL GROWS, SO DOES PROGRAMMING SYSTEM NEEDS, Pulp
Paper 42 (28), 21-4 (July 8, 1968).
A program is described for evaluating the present and
future pollution level of a mill on the basis of the
production level and the implementation of pollution
control measures.
10-22
-------
Evans, J. C. W., CANADIAN [PULP AND PAPER] INDUSTRY ADVANCES
IN AIR AND WATER EFFLUENT CONTROL, Paper Trade. Journal 152
(40), 50-60 (September 30, 1968).
Rather detailed summaries are presented of the following
papers given at the 4th Paper Industry Air & Stream Im-
provement Conference held by the Tech. Section, Can. Pulp
S Paper Association at Halifax, Nova Scotia: Smith, R.C.:
Outside dry barking of hardwoods and softwoods.; Morris, J.
V., and McGill, L.H.: Mechanical aerator [for water aeration]
testing at London, Ontario.; Hochmuth, F.W.: Odor control
system for [kraft] chemical recovery units.; Harvey,E.H.,
and Devine, T.M.: [effluent] bark fines removal and recovery
system.; Parker, G.R., and White, L.C.: Effluent treatment
at the Hinton [Alberta] kraft [pulp] mill [of North Western
Pulp & Power Ltd.]; Malarkey, E.J., and Rudosky, C.: [Air
Pollution control with] high efficiency kraft [pulp] mill
[electrostatic] precipitators [incombination with gas
scrubbers].; Wong, P.M.: Primary treatment of effluent at
Great Lakes Paper Company's kraft mill; Clement, J.L. and
Elliott, J.S.: Kraft recovery boiler design for odor control.;
Lankenau, H.G. and Flores, A.R.: Multiple effect evaporation
of kraft mill black liquor to 55-65% solids. !
Canadian Chemical Processing, POLLUTION: CLEANUP IN THE
PULP MILLS, Can. Chem. Process. 50 (12), 43-7, 60 (Decem-
ber 1966).
Air and water pollution, already a problem in some Canadian
provinces (e.g., British Columbia) is being further aggra-
vated by new or the expansion of present pulp and paper-
making facilities. This report summarizes to what extent
the Canadian government and the pulp and paper industry are
cooperating (e.g., fiscal incentives offered by the govern-
ment) in an effort to reduce pollution. Some details are
given of the types and amounts of pollution produced, to-
gether, with pollution abatement measures taken by some of
the mills.
10-23
-------
Banciu, I., DEODORIZATION SYSTEMS USED IN THE KRAFT PULP
INDUSTRY, Celuloza Hirtie 17 (1), 36-40 (January 1968).
This is a brief review of some odor control measures em-
ployed at various American and European kraft installations,
including the principles involved (black liquor oxidation,
catalytic oxidation, flue gas combustion in recovery fur-
naces and lime kilns, and gas scrubbing with various chem-
icals) . 14 ref.
Anderson, K. , HOW KRAFT PULP MILLS CAN DECREASE COOKING
ODORS, Pulp Paper Intern. 9 (6), 52-3 (June 1967).
Kraft pulp mill odor can be decreased by decreasing the
amount of organic sulfur compounds formed during the cook.
The influence of various cooking variables on organic
sulfur compound formation is outlined. It is shown that
organic sulfur compound formation can be reduced by in-
corporating a Sion-poor or lignin-poor second stage into
the cook. The latter case, which involves the withdrawal
and cooling of the cooking liquor when the cook reaches
the maximum temperature, is the more attractive. Reducing
kraft mill odor through oxidation, absorption, and extn.
of sulfur compounds in the gaseous emissions from a kraft
mill is also discussed along with steam stripping of
digester condensates.
Adams, Donald F., A SURVEY OF EUROPEAN KRAFT MILL ODOR
REDUCTION SYSTEMS, TAPPI 48 (5), 83-7A (May 1965).
During the spring and summer of 1964, a study was made of
selected kraft pulp mill installations in Norway, Sweden,
Finland, France, Italy, and Austria. Information was ob-
tained by personal interviews with tech. personnel in the
mills and research workers in institutes and universities.
Equipment in 18 mills was observed, and the unique fea-
tures of these installations are reported. The principal
methods contributing to odor reduction included incinera-
tion, alk. absorption, heat recovery, black liquor oxi-
dation, and Cl treatment. 6 ref.
10-24
-------
Harding, C. I. and Galeano, S. P., USING WEAK BLACK LIQUOR
FOR SULFUR DIOXIDE REMOVAL AND RECOVERY, TAPPX 51 (10), 48A
(October 1968).
Pulp mill air pollution problems are of three basic types:
odor, particulate emissions, and sulfur dioxide emissions
from power boilers. Black liquor oxidation is the single
step most effective for odor reduction. Work has been com-
pleted on a pilot scale on the development of a weak black
liquor oxidation system using southern kraft liquor with
subsequent use of the liquor for SO scrubbing of power
plant flue gases. The results of this work show that weak
black liquor from southern kraft mills can be oxidized
effectively by using kerosene for foam control. The scrubb-
ing of the flue gas with the weak liquor by using a moderate
head loss Venturi scrubber (approximately 14 in. HO) showed
consistent SO removal efficiencies above 92%. Work by
earlier investigators was confirmed, showing that approxi-
mately 80% sulfide oxidation gave the most effective SO
absorption without any measurable release of hydrogen sul-
fide. Complete oxidation of sulfide enhanced the formation
of sulfates which inhibited SO removal during scrubbing.
The liquor can be recirculated for multiple passes through
the scrubber provided the pH is kept sufficiently high to
prevent lignin precipitation. The economics of the system
indicate that a net savings of about 30£/ton a.d. pulp can
be effected by installing the integrated oxidation and
scrubbing system without any dollar credit for reduction
in SO emissions.
Tirado, A. A. and Gonzales, V. P., TEN YEARS EXPERIENCE IN
ODOR CONTROL AT THE LORETO Y PENA POBRE KRAFT MILL, TAPPI 52
(5), 853, (May 1969).
Additions and modifications were made to a kraft mill odor
control system, which has been operated for 10 years. Em-
phasis was placed on determining and maintaining proper re-
action conditions for each process. Odor levels were moni-
tored at various locations around the mill, and modifications
to the odor control system were based on these reports. The
original odor index in 1957 was 0.072; and by 1967 the aver-
age was 0.00187, a reduction of 97%. The absorption of mer-
captans and other sulfur compounds in white liquor, to make
a special cooking liquor, was successfully applied. As a
result, pulp quality was improved and odor emission dropped
about 67%. Lime kiln emissions were controlled by careful
operation.
10-25
-------
Walther, J. E. and Amberg, H. R., A POSITIVE AIR QUALITY
CONTROL PROGRAM AT A NEW KRAFT MILL, Paper to be published
J.APCA, (January 1970).
In the design of the Crown Simpson bleached kraft mill at
Fairhaven, California, the latest technological develop-
ments in odor and dust control were used to design a sys-
tem capable of removing in excess of 90% of the malodorous
sulfur emission and more than 98% of the dust load. The
odor control system consists of high efficiency black
liquor oxidation, noncondensible gas burning, and stripping
of "foul" condensate followed by burning of the off-gases.
The dust control system on the recovery furnace consists
of a high efficiency electrostatic precipitator followed
by wet scrubbers. The lime kiln gases are scrubbed in a
Venturi scrubber and the smelt dissolver stack was equipped
with demister pads. The gases from the lime kiln, power
boiler, recovery furnace, and black liquor oxidizer are
combined and discharged through a 310 ft. stack. A com-
plete emission inventory has been conducted and the volume,
composition and quantity of materials discharged are pre-
sented.
Walther, J. E. and Amberg, H. R., THE STATUS OF ODOR CONTROL
IN THE KRAFT PULP INDUSTRY, paper presented at the National
Meeting of AIChE, Portland, Oregon, August 24 - 27, 1969.
Technological advances in the control of odor from kraft
pulp mills have been rapid and new installations presently
discharge only a fraction of the malodorous sulfur compounds
discharged by the older mills. Emission surveys conducted
at mills which do not have odor control equipment indicate
a total reduced sulfur emission rate of about 20 Ibs./A.D.
ton of pulp can be expected. New mills employing high
efficiency oxidation of black liquor and burning of non-
condensible gases from the digesters and multiple-effect
evaporators can reduce the emission rate to about 1.5 Ibs/
ton of pulp, a reduction of 92%. Comprehensive surveys of
new recovery furnaces indicate that elimination of direct
contact of flue gas with black liquor can reduce the
emission rate from the recovery furnace to 0.01 Ibs. of
total reduced sulfur per A.D. ton of pulp. Miscellaneous
sources such as the pulp washer hood vent, washer seal
tank vent, oxidizer off-gas vent and knotter hood vent now
constitute the major source of total reduced sulfur. Be-
cause of the large volume of these streams and low concen-
tration of reduced sulfur compounds, treatment of these
streams presents a difficult problem. Research and develop-
ment efforts must now be concentrated on these sources.
10-26
-------
10.2.6 RESEARCH ON CONTROL OF NSSC SOURCES
Little information is available about atmospheric emissions
from NSSC process variations and about the operating and
process variables that affect emissions. Data are lacking
regarding the effect of NSSC liquor on emissions from NSSC-
kraft cross-recovery. Some work has been done on processes
for recovering NSSC liquor to prevent stream pollution, and
this is reported here because of the possibility that the
systems could be a source of atmospheric emissions.
Copeland, G. C. and Hanway, John E., Jr., THE TREATMENT OP
NEUTRAL SULFITE SEMICHEMICAL SPENT LIQUORS IN A FLUIDIZED-
BED REACTOR, TAPPI 47(6), 175-84A, (June 1964).
The experimental and commercial development of a fluidized-
bed process, the Container Copeland process, for the dis-
posal of spent NSSC liquor has given encouraging results in
efficiently eliminating the usual disposal problems. A
commercial unit capable of treating the effluent from a
130 ton/day NSSC pulp mill has been operated for over 1
year. The results of this operation indicated ithat com-
plete oxidation of the organic content of the liquor can
be accomplished under autogenous conditions at Relatively
low solids concentrations and that a pelleted granular
residue of oxidized inorganic chemical containing essen-
tially Na CO and Na SO. can be produced. No evolution
of sulfur-bearing gases, which could serve as a source of
atmospheric pollution has been noted. It is believed that
this system represents a significant improvement for the
treatment and disposal of many types of pulp mill liquors.
From a disposal standpoint, the process is simple, relative-
ly foolproof, and economical.
Howard, W. C., A NEW AND ECONOMIC SOLUTION TO THE PROBLEMS
OF STREAM AND AIR POLLUTION [IN THE PAPER INDUSTRY - THE
FLUID-BED COPELAND PROCESS], Norsk Skogind 21 (4), 133-9,
(April 1967).
The fluid-bed Copeland process for disposal (by combustion
and oxidation) of spent liquors of various pulping processes
(NSSC, Mg-base sulfite, kraft overload relief) and bark and
sludge incineration is described in some detail with sche-
matic drawings, along with applications of the fluid-bed
reactor to lime burning (lime mud calcining), etc. 21 ref.
10-27
-------
Klass, C. P., CONTAINER] CORPORATION OF] A[MERICA] SOLVES
NSSC LIQUOR DISPOSAL PROBLEM [AT CARTHAGE, IND. MILL] WITH
FLUID[IZED] BED REACTOR, Paper Trade J. 151 (13), 50-3,
(March 27, 1967).
The Container Copeland Process plant at the mill for the
combustion of NSSC spent liquor is described. The plant
receives spent liquor from the first-stage vacuum washers
at 9-10% solids. Triple-effect Horton long-tube vertical
evaporators concentrate the liquor to a point where it will
burn without additional fuel in the fluidized bed reactor.
Air from the reactor goes to a 2-stage scrubber system. A
dry pelletized product consisting of the residual inorganic
salts (mainly Na SO. and Na CO ) results from the operation.
At present, this is being snipped to company kraft mills
for use as make-up saltcake. Operation and economics of
the process are discussed.
Williamson, D. F., Hough, G. W. and Mason, F. I., RECOVERY
OF CHEMICAL IN COMBINED KRAFT AND NSSC PULP MILLS, TAPPI 52
(11), 2105, (November 1969).
The kraft/NSSC pulp production ratio for minimum capital
expenditure of the NSSC mill depends on the chemical re-
quirements of the kraft mill. With the processes avail-
able today, excess chemical from the kraft recovery can
be converted to NSSC cooking liquor. Introduction of spent
NSSC liquor to the kraft process is best carried out at the
kraft digester, blow tank, or brown stock washers. Addition
is also carried out at the evaporators, where pH of the com-
bined liquors must be above 11 to avoid liquor precipitation
and scaling. The use of 316 or 316L stainless steel tubes
should be considered in the evaporators in order to keep
down-time due to scaling to a minimum.
10.2.7 RESEARCH ON CONTROL OF SULFITE SOURCES
Only in recent years have process modifications been made
to the sulfite process to reduce water pollution problems
and recover heat and chemicals. The old calcium base has
been replaced to some extent with soluble bases which are
more amenable to recovery. Recent research has been di-
rected toward recovery systems for the cooking liquor and
improved absorption of SO . Complete information concern-
ing gaseous emissions is still not readily available.
10-28
-------
loffe, L. O. , COMPUTATION OF THE FINAL DIGESTER BLOW-OFF
IN THE SULFITE PROCESS, Bumazh. Prom. No. 6, 18-20, (June
1966).
During the final digester blow-off in the sulfite process
30-70% of the sulfur dioxide (I) and 10-20% of the heat
are recovered. Moreover, the final blow-off determines
to a large extent the content of the residual (I) in the
spent liquor, hence the extent of pollution of the surround-
ing air during the discharge of the digester, and also the
suitability of the SSL for biochemical processing. Despite
the importance of this process, no computation means have
been developed relating the temperature and pressure changes
in the digester with the (I) content in the spent liquor.
The author made an attempt to develop a computation method,
based on the earlier devd. equation for the calculation of
the amount of WV accompanying (I) during evaporation of the
latter from aq. solutions and on the following assumptions:
the liquid and the gaseous phases are in equil.; the solu-
bility of (I) in the SSL is the same as in water; the SSL
does not contain bound and easily split (I); and the volume
of the SSL does not depend on the mat. of dissolved sub-
stances or on temperature. The equation relates the follow-
ing parameters: the weight of spent liquor prior to blow-
off WIS. (in kg.); the weight of WV accompanying (I), ^ ;
the ratio P/K characterizing the rel. volatility of WV"^
and of (I) at a given temperature; and the content of (I)
in the spent liquor prior to and after the blow-off X. and
}C , respectively. Two difficulties were encountered in
applying the equation, notably two unknowns (w and X, ),
and the fact that the equation was devised for^an isothermic
process, while the blow-off is an adiabatic process, and
hence, because of the dependence of P_/K on temperature,
by utilizing a second equation, that of the heat balance
of the blow-off (assuming that the heat is consumed entirely
for the evaporation of water and (I)). The second diffi-
culty was eliminated by the method of successive approxi-
mations, to give data necessary for the determination of
the temperature dependence of P_/K and of the heats of
evaporation of water and (I). Also, a method is presented
for the calculation of pressure changes during the blow-
off, by assuming the pressure to be equal to the sum of
partial pressures of WV and (I). An example of computation
for 1 ton wood is given, from which certain practical
conclusions are drawn: The blow-off process should be
10-29
-------
controlled by the drop of temperature, not pressure. In
order to lower the content of CD in the SSL to 0.01-0.03%,
a cooling of the digester by 20° C is sufficient [the
residual (I) content will be also determined by its initial
concentration in the liquor]. A lower starting temperature
for the blow-off is more convenient, as it gives a lower
residual (I) content. The calculations also show that the
residual (I) content on the SSL can be made sufficiently
low not to necessitate its additional removal prior to
biochemical processing of the SSL.
Kann, P. and Fuchsel, R., COMPARISON OF THE DISTINCTIVE
CHARACTERISTICS FOUND IN BURNING CONCENTRATED SPENT LIQUORS
OBTAINED IN MAGNESIUM BISULFITE COOKS AND IN CALCIUM BI-
SULFITE PULPING OPERATIONS, Papier 21 (4), 174-9, (April
1967).
After a brief review of current recovery systems, the basic
differences required in burning the two types of SSL are
described. Differences in digester operations, as well as
in subsequent treatments are due to the fact that chemical
recovery is not possible in the case of CaHSO but is
essential for MgHSO spent liquors. Reasons for the more
difficult techniques used in burning concentrated Mg spent
liquors are described in detail together with the require-
ments for the construction of combustion chambers needed
for Mg spent liquors. Difficulties have been overcome,
thanks to studies made at the Lenzinger Zellulose and
Papierfabrik in Austria; some of the experiments are
described. The relationship between the brightness (white-
ness) of the MgO ash and the temperature of the combustion
chamber is emphasized. By maintaining a temperature of
1150°C an ash brightness of 54% was obtained. A unit
recently installed at Lenzing permitted a combustion temp-
erature of 1250°C, thus giving an ash brightness of 65%.
After combustion the excess air was only 1.5% which was well
within the limits required to prevent SO_ from being oxi-
dized to SO . Certain pitfalls are outlined and simple
sketches are included.
10-30
-------
Kruel, M., and Juntgen, H., DUST CLOUD REACTION OF DOLOMITE
AND OTHER ALKALINE-EARTH COMPOUNDS WITH SO IN WASTE GASES,
Chem.-Ing.-Tech. 39 (9/10), 607-13, (May 24, 1967).
In a study of the desulfurization of waste gases through re-
action with dolomite dust, a pilot plant was constructed in
which the hot waste gases.were passed through a heated re-
actor tube into which dolomite dust (or similar com. prod.)
was blown. Measurement of the SO content of the waste gases
at various points along the reactor tube shows that the de-
gree of desulfurization depends mainly on the temperature,
the stoichiometric ratio of dolomite or other desulfurizer
to SO , and the particle size and chemical composition of the
desulfurizer. Reaction period was of secondary importance as
long as a minimum of 1.5 seconds was exceeded. 6 ref.
Rusten, D., CONSTRUCTION AND OPERATION OP SCOTTISH PULP S
PAPER MILLS, Norsk Skogind. 21 (11), 443-50, (November 1967).
An illustrated description is given of the layout, planning,
and production operations of Scottish Pulp & Paper Mills at
Fort William, including reafforestation of highlands for pulp-
wood, reasons for site selection, process water and effluent
treatment, wood handling, pulping, bleaching, paper machine,
and social importance of the new mill which is the first to
use the Stora 2-stage high-yield sulfite process for an
integrated operation. The flexible process gives bleaching-
grade pulp for printing and writing papers without air
pollution. Softwood is delivered by rail and road and pur-
chased on a green weight basis, while hardwood chips are im-
ported from North America. Wood storage is in chip piles.
Five batch digesters of 225 cu.m. capacity each and a 5-stage
bleach sequence (CEDED) are used. Bleached pulp is either
baled at 50% dryness or pumped in slush form to the paper
mill. Fine paper grades from 60 to 300 g./sq.m. basis weight
are run on a 530 cm. wide fourdriner at speeds up to 450 m./
minute. Total annual capacity is 80,000 tons of pulp and
40,000 tons of paper.
10-31
-------
Smith, E. L., SULFITE PULPING AND POLLUTION CONTROL,
Combustion 38 (12), 42-4 (1967).
Among the various means of disposing of sulfite pulping waste
liquors, the least expensive method at present appears to be burn-
ing of the org.portion of the liquor. Many mills, in efforts
to avoid the expenditures of a positive pollution control sys-
tem, have resorted to makeshift arrangements such as lagooning
to relieve their pollution problem. In the long run, this
generally results in larger expenditures than if a positive
pollution control system were installed initially. The devel-
opment of the process for disposal of waste sulfite liquors
by burning is traced and economic advantages to be gained by
the installation of such a system are discussed. Finally,
capital investment costs for such a system are considered.
Clement, J. L., MAGNESIUM OXIDE RECOVERY SYSTEM, TAPPI 49 (8),
127-A, (August 1966).
Equipment arrangements are presented to meet the requirements
of a magnesia base pulp mill for complete recovery of heat
and chemicals from spent sulfide liquor. Several designs of
recovery boilers including alternate arrangements and designs
of economizers and air heaters provide heat recovery in an
integrated system. The cyclone direct-contact evaporator can
recover heat to reduce the multiple-effect evaporator duty or
increase the firing concentration of low heat value liquor.
Heat recovery can be increased further by utilizing the low-
level heat in the gas for production of hot process water.
Boiler design can incorporate auxiliary fuel firing to assure
steam production independent of liquor availability. Recovered
magnesium oxide is used to remove 95% + sulfur dioxide from
combustion gases in a Venturi absorption system to prepare
acid at a concentration required by the pulp mill. Thermal per-
formance and horsepower requirements for two pulping tech-
niques of diverse yield establish that recovery capacity and
size are a function of the heat input and not related to pulp
production. The capacity of a recovery system is about twice
as large for a low-yield dissolving-grade pulp as for a pulp
to be used in newspring furnish.
10-32
-------
Votoupal, J., SOME REMARKS ON THE ECONOMICS OR EVAPORATION
AND BURNING OF SPENT CALCIUM BISULFITE LIQUORS, Papir Celu-
loza 22 (7), 193-8, (July 1967).
A system for evaporation and burning of Ca-base SSL was in-
stalled in 1966 at the Southern Czechoslavakian Mills. The
evaporator has a capacity of 47-50 tons evaporated water/hr.,
and the two boilers for joint burning of the evaporated li-
quor and brown coal produce 75 tons stream/hour, the steam
having a pressure of 64 atm. and a temperature of 450°C.
The equipment includes a distillation column for the recovery
of sulfur dioxide. The wash waters go directly to the evap-
orator. Considering that in the evaporation and burning of
Ca-base liquor, the base is not recovered, the economic
efficiency of the process is lower than in the case of other
spent liquors, and calculations of the economic justifications
must be based on the amount of sulfur dioxide and heat re-
covered and the amount of solid fuel saved. The author
discusses the factors affecting the efficiency of the process,
such as the concentration of the spent liquor prior to evap-
oration, the solids content of the liquor/ton pulp, the heat
content of the liquor, the type of evaporation equipment used
(vacuum or back pressure) , and the type of fuel! burned joint-
ly with the liquor (coal of various types or oil). Graphs
are presented illustrating the relation between the amount
of water evaporated/kg, solids and the degree of liquor con-
centration; between the spent liquor solids and the pulp
yield; between the concentration of the liquor and its heat
content; between the amount of fuel saved and the spent
liquor solids content when different types of evaporators
are used; and between the evaporation efficiency and the
concentration of liquor to be evaporated. Also given are
diagrams of the equipment installed at the Southern Mills
and of the Ramen system. It is pointed out that these con-
siderations should be regarded as a general guide for eco-
nomic calculations. A more precise evaluation must be based,
in each individual case, on local conditions. 7 ref.
10-33
-------
Copeland, G. G. and Overall, J. E., ELIMINATION OF SULFITE
MILL WASTES BY FLUID[IZEDJ BED TREATMENT, Am. Paper Ind. 49
(3), 41-2, 45-9, 51, (March 1967).
The fundamentals of the Container-Copeland process are re-
viewed. Although the process was originally developed for
the disposal of NSSC spent liquor, various modifications have
been developed which permit its application in disposal of
spent liquors from Mg and NH base sulfite pulping, in pro-
cessing kraft liquor recovery system overloads, and in the
incineration of waste bark and paper machine white water
sludge. Some cost data are cited on savings resulting from
the use of the process.
Erdman, A., Jr., APPLICATION OF FLUIDIZED BED PROCESSING TO
SPENT SULFITE LIQUOR COMBUSTION, TAPPI 50 (6), 110-12A,
(June 1967) .
SSL has long been a severe source of pollution. The SSL com-
bustion system represents an economical method of abating
both water and air pollution by converting the SSL to a gran-
ular inorganic solid and a clean, dust-free, odorless exhaust
gas. In most cases, complete or partial chemical recovery
is possible, or a salable product can be made which will pay
for part of the operating costs of the system. Still more
attractive is the fact that return on investment becomes an
attainable asset when chemical recovery is coupled with other
recovery devices, such as high- and low-level heat recovery.
Copeland, G. G., Hanway, J. E., Jr., Container Corporation of
America, FLUID BED RECOVERY FOR FRANCONIA, Pulp Paper 42 (37),
29-31, (September 9, 1968).
The Copeland fluidized bed recovery system installed for
chemical recovery at the company's sulfite pulp mill at
Lincoln, New Hampshire, is described. When the conversion
from ammonium-base to Mg-base pulping is effected, the sys-
tem will recover both Mg and S.
10-34
-------
Moody, Dennis M., BLOWPIT GAS RECOVERY WITH A SINGLE BLOW
STACK SYSTEM, TAPPI 52 (3), 448, (March 1969).
A single blow stack system for the recovery of blowpit
vent gases was designed and installed in the summer of
1966, replacing multiple wooden blow stacks. It consists
of a stainless steel stack connected to the six blowpits
by a header system. The stack acts as a scrubbing column,
condensing steam and recovering sulfur dioxide from blowpit
gases for reuse. The system is designed to operate at high
flow rates and low pressure drops. Water is sprayed
counter-currently to rising gases over specially designed
stainless steel and wood packing. Water flow control is
based on gas temperature and pressure. The system is 98%
efficient in sulfur dioxide recovery and has resulted in
both improved sulfur dioxide and heat recovery. Exit
gases average about 1400 ppm SO .
Leitner, G. F., SPENT SULFITE LIQUOR EVAPORATORS - DESIGN
AND PERFORMANCE, TAPPI 52 (7), 1296 (July 1969).
One of the main considerations in selecting a pulping pro-
cess is the means of spent liquor recovery or disposal.
The sulfite pulping process has some important advantages
over kraft pulping, but until recent years its progress
has been retarded by the inherent problems connected with
the spent liquor. Six processes for treatment of spent
sulfite liquor have been developed to the point of commer-
cial use. All six have one thing in common: they require
concentration by evaporation as a preliminary step. Some
significant improvements have been made in recent years
in evaporators for concentrating spent sulfite liquor.
These have been in the area of scale control. These plants
now operate continuously, whereas early designs experienced
major operating difficulty in control of scale formations
which caused frequent shutdowns. A new system being tested
for use as a preconcentrator for very dilute wash water,
reverse osmosis, is also described.
10-35
-------
Clement, J. L. and Sage, W. L., AMMONIA-BASE LIQUOR BURNING
AND SULFUR DIOXIDE RECOVERY, TAPPI 52 (8), 1449 (August 1969).
The use of ammonia-base for sulfite pulping requires con-
sideration of waste liquor burning and sulfur dioxide com-
bustion product recovery. Burning tests in a pilot unit
demonstrate liquor can be burned at stable combustion con-
ditions without supplementary fuel where the solids content
of the liquor exceeds 50% and air temperature 550°F, and
establish parameters for the projected design of a commercial
liquor atomizer and water-cooled furnace to burn ammonium
liquor. Reported sulfur dioxide absorption experience pro-
vides information to design a system for sulfur dioxide at
a temperature of about 100°F; more economical design at the
flue gas dew-point temperature requires additional know-
ledge of the effect of temperature on absorption system para-
meters.
10.2.8 RESEARCH NOT REPORTED IN THE LITERATURE
In addition to the foregoing, NCASI has identified the follow-
ing categories of research or specific projects which presently
are under way in the industry. Results may or may not be re-
ported eventually in the open literature. It is not possible
at this time to define the scope of work more completely nor
to indicate the level of effort.
a. Completion of miscellaneous kraft emission source inven-
tories at several mills, concentrating on brown stock
washer, seal tank and knotter vents, and black liquor oxi-
dation tower off-gases, to determine their relative im-
portance as reduced sulfur compound emission sources. This
program is being expanded to cover a large group of kraft
mills with the knowledge that changes in recovery furnace
systems definitely will result in greater attention being
focussed on these miscellaneous sources.
b. Determination of the relation between pulping temperature
sulfidity and sulfur emission at the digester and evapo-
rator.
10-36
-------
c. Gas chromatographic identification of evaporator non-
condensible and recovery furnace organic compound
emissions.
d. Completion of the investigation of relative importance
of the kraft recovery furnace and direct contact evap-
orator as reduced sulfur emission sources under varying
conditions of furnace loading and operation, and degree
of black liquor oxidation.
e. Determination of nitrogen and sulfur oxides emission
levels for recovery furnaces.
f. Determination of particulate emission levels and charac-
teristics for waste wood fired pulp mill power boilers.
g. Examination of recovery furnace operating variables in-
cluding air supply and distribution, and liquor droplet
size to develop furnace operating procedures which mini-
mize internal process emissions.
h. Comprehensive review of black liquor oxidation tech-
nology leading to pilot testing of proprietary devices
such as the spiral oxidizer, and multistage oxidation
using tonnage oxygen for polishing purposes.
i. Review of emission control technology for lime kilns
and bark-fired boilers.
j. Review of industry practice in Thermal oxidation of
non-condensible gases from digesters and evaporators.
k. Evaluation of Scandinavian recovery furnace system
evaporation features and their limited application in
the United States specifically for sulfur odor emission
control.
1. Examination of alternate particulate emission control
systems for the recovery furnace, including bag fil-
tration and electrostatic pre-agglomeration followed
by wet scrubbing.
m. Evaluation of several techniques for scrubber recovery
of S02 f
mill pow
liquors.
of SO from sulfite pulpmill furnaces as well as NSSC
mill power boilers to reconstitute sulfite pulping code
10-37
-------
n. Development of high efficiency particulate collection
systems for waste wood fired pulp mill power boilers,
including scrubbing and electrostatic precipitation.
o. Cryogenic separation of odorous materials from kraft
recovery furnace stacks and other process emission
sources.
p. Stripping of evaporator condensates followed by acti-
vated carbon adsorption of odorous materials on acti-
vated carbon.
q. Catalytic and alkaline scrubbing and electrostatic pre-
cipitation as means for reducing H S content of kraft
recovery furnace gases.
r. Use of fluidized bed techniques to modify the kraft
chemical recovery process through substitution of an
oxidative phase for the conventional smelting phase.
10-38
-------
10.3 COST AND EFFECTIVENESS OF EMISSION CONTROL
During the course of this study, a dearth of information was
noted on cost and relative effectiveness of a variety of
control equipment for removal of gases, particulates, and
combinations of the two. Reliable information was obtained
on costs from some mills. Most mills, however, do not
maintain their cost data in a manner which makes the infor-
mation readily available for individual items of equipment.
Little information in this category was noted in the
published literature.
Kleinegger, J. C., RELATIVE ABSORPTIVE EFFICIENCY OF PACKED
TOWERS IN MAGNESIUM ACID BISULFITE PRODUCTION, TAPPI 52 (7),
1291, (July 1969).
Two similar magnesium acid bisulfite absorption trains are
compared and evaluated. The first system is a conventional
series of four countercurreht packed towers using 6 X 6 in.
cross partition packing-throughout. The second system is a
series of four towers, with the last three towers of the
acid plant using 3 1/2 in. Pall rings, rather than cross
partition rings. Development of the concept of 'mass trans-
fer effectiveness is presented and applied to th!e two absorption
systems. In each tower" utilizing 3 1/2 in. Pall rings the
height of an overall gas transfer unit is demonstrably less
than for the comparable tower using 6 X 6 in. cross partition
packing.
Arhippainen, B., and Westerberg, E. N., KRAFT ODOR CONTROL: ITS
EFFECT ON MILL OPERATING PARAMETERS AND COSTS, Pulp Paper Mag.
Can.69 (8), 65-70, (April 19, 1968).
This rev. discusses current knowledge on kraft odor control with
emphasis on Scand. conditions and experiences; effects of an odor
control installation on mill conditions (process S. equip., S
losses, operating costs, etc.) and mill environment (attitude of
people); and recovery boiler systems without and with direct
contact evapn. and with or without addnl. odor control equipment
(comparing Scand. to N. Am. practices). The two systems are
believed to be competitive, but cost comparisons between the two
countries must be modified to fit local conditions. 9 ref.
10-39
-------
Willett, H. P., CUTTING AIR POLLUTION CONTROL COSTS, Chem. Eng.
Progr. 63 (3), 80-3, (March 1967) .
The costs of air pollution control can be drastically reduced
by design innovations in the basic process which causes the
pollution. Several examples are presented which show that
substantial savings are possible by rel. inexpensive changes.
For example, in the paper ind., the amt. of H S released to
the atm. by combustion of the black liquor in the recovery
furnace can be reduced greatly, if prior to combustion, the
black liquor is oxidized with air.
10.4 SAMPLING AND ANALYTICAL TECHNIQUES
Much progress has been made since the early 1950"s in sampling
and analytical techniques for both gases and particulates. Time
consuming wet chemical methods have been replaced by more sensitive
and efficient techniques involving gas chromatography, coulimetry,
UV spectroscopy, and IR spectroscopy. Progress has been made in
both ambient air and source monitoring. Despite the progress,
however, it is obvious that the available methods and instrumen-
tation have not achieved the state of reliability and simplicity
needed for continuous application in the field. Much of the
work reported in the literature is applicable to kraft sources
and the environment surrounding kraft mills. Although some of
these procedures are applicable as well to sulfite and NSSC
sources, but many are not. Reliable, standardized techniques
for both gases and particulates for both ambient air and
source monitoring are still the top research need.
Hendrickson, E. R., Walker, C. G., and Chapnerkar, V. D.,
IDENTIFICATION OF NON-SULFUR ORGANIC COMPOUNDS IN STACK GASES
FROM PULP MILLS, Am. Ind. Hyg. Assoc. J. 24, 121-6, (March-
April 1963) .
Objectionable odors of stack emissions from pulp mills have
been traditionally assocd. with S cpds. Concns. of identified
cpds. are not considered dangerous to health of the community.
In this study of stack gases, qual. identification was made
of the presence of: benz[a]-anthracene, benzo[a]pyrene,
benzo[e]pyrene, benzo[g, h, i]perylene, chrysene, coronene,
fluoranthene, and pyrene. Tentatively identified were:
anthanthrene, anthracene, phenanthrene, and vanillan I sic].
9 ref.
10-40
-------
Lur'e, Yu. Yu., Alferova, L. A., and Titova, G. A., ANALYSIS
OF KRAFT PULPING EFFLUENTS, Zavodsk. Lab 29 (4), 412-15,
(1963).
A method is described for the anal, of kraft mill effluents,
which makes possible direct detn. of H S, MeSH, Me S, and Me S . A
stream of CO is passed through an acidified sample of the
effluent and the components, entrained by the gas, are
successivley absorbed in appropriate solns. Thus, H S is
absorbed into an acidic soln. of CdCl , MeSH, and Me S (the
latter after conversion into MeSH by hydrogenation) into
an alk. soln. of CdCl , and Me S into a 6% soln. of HgCl .
The H S and MeSH are detd. iodometrically, Me S gravi-
metrically. The detn. of Me S presents certain difficulties,
due to its low volatility (it requires longer time of blowing
CO )and retention in the absorption vessels prior to hydro-
genation. For this reason, it is recommended that Me S be
blown, after the anal, is completed from the absorption
vessels. The method was appl. to the anal, of effluents
from a black liquor regeneration process. The results of
the anal, are given. 4 Ref.
Suzuki, Y., Nishiyama, K., Oe, M. and Kametani, F., STUDIES
ON THE PREVENTION OF PUBLIC NUISANCE BY THE EXHAUST GASES
FROM THE KRAFT PULP MILL, Tokushima J. Exptl. Med. 11, 120-6,
(1964).
Anal, of the exhaust gases from the kraft pulp mill showed the
fig. to be present: 0.259 g./. of Na sulfate, 750 ppm of
hydrogen sulfide, 196 ppm of sulfur dioxide, and org. cpds.
of S. The org. S cpds. included the fig. in order of amt. present:
methyl mercaptan, dimethyl sulfide, isoprophy mercaptan, dimethyl
disulfide, propyl mercaptan or ethyl methyl sulfide, diethyl
sulfide, and ethyl mercaptan. The concn. of dimethyl sulfide was 8.7
ppm. Org. S cpds. in the gas in the upper part of the Jansson
screen were of the same cpn. as those in the stack gases, but
the arrangement of the constituents in order of amts. present
were different. All of these gaseous S cpds. have offensive
odors and characterize the exhaust gases from a kraft pulp mill.
Risk, J. B., and Murray, F. E., CONTINUOUS RECORDING OF SULFUROUS
GASES CONCENTRATIONS IN FLUE GASES, Can. Pulp Paper Ind. 17 (10) ,
31-4, (October 1964).
Methods of measuring the concn. of hydrogen sulfide and sulfur
dioxide in flue gases are revd. and the devt. of a new method
based on the use of a com. UV analyzer is described. The
10-41
-------
new method permits the continuous and reliable measurement of
hydrogen sulfide content in flue gases of varying cpn. and
contg. sulfur dioxide on a com. basis.
Thomas, Edgar W., DIRECT DETERMINATION OF HYDROCARBON SULFIDES
IN KRAFT GASES BY GAS-LIQUID CHROMATOGRAPHY, TAPPI 47 (9), 587-
8, (September 1964).
A rapid method of sampling and analg. kraft gases for hydrocarbon
sulfides has been devd. by the use of a gas chromatograph. The
use of a flame ionization detector with its high sensitivity to
hydrocarbons and its insensitivity to water enables samples of
gases to be taken directly from the stream and anald. It is
not necessary to cone, or dry the samples as would be the case
if a thermal conductivity detector were used. All concnts. of
mill gases have been anald. and tables are given for the
various sampling points. 7 Ref.
Adams, D. F., Koppe, R. K., and Tuttle, W. N., ANALYSIS OF
KRAFT MILL, SULFUR-CONTAINING GASES WITH GLC IONIZATION
DETECTORS, J. APCA 15 (1), 31-3, (1965).
Simulated process gas mixtures comprising H S and CH SH were
comparatively separated with five types of detectors in
chromatographic columns. Minimum detectable concentrations
of CH SH was 0.5-1.0 ppm with flame ionizatioh and that of
H S was 3.0 ppm with coulometric titration. Electron capture,
thermionic emission, and thermal condensation were also
evaluated.
Adams, D. F., Jensen, G. A, Steadman, J. P., Koppe, R. K., and
Robertson, T. J., IMPROVED SULFUR-REACTING MICROCOULOMETRIC
CELL FOR GLC, Anal. Chem. 38 (8), 1094-6, (1966).
The sensitivity of the cell configuration of a common trans-
istorized coulometer was modified by converting to a Br cell
with the reference electrode in direct contact with the
titration cavity was 30 times greater than the original cell.
The column effluents can be oxidized to SO2 or reduced to
H S prior to introduction into the microcoulometric cell.
Reduction to H_S provided a four-fold increase in sensitivity
over oxidation to SO .
10-42
-------
Adams, D. F, and Koppe, R. K., A MANUAL FOR DIRECT GAS
CHROMATOGRAPHIC ANALYSIS OF SULFUR GASES IN PROCESS STREAMS
NCSI Technical Bulletin 30, (1966) .
Rayner, H. B., Murray, F = E., and Williams, I. H., STUDIES ON
THE GAS-CHROMATOGRAPHIC ANALYSIS OF KRAFT MILL SULFIDES. (2)
DETERMINATION OF MICROGRAM QUANTITIES OF METHYL MERCAPTAN,
METHYL SULFIDE, AND METHYL DISULFIDE IN AQUEOUS SOLUTION,
Pulp Paper Mag. Can 68 (6), (June 1967).
An anal, method has been devd. for the detn, of MeSH, Me S,
and Me-S in aq, soln. Precision of the procedure is within
5%, ana a minimum of about 10 parts per billion of each of the
sulfidas in water can be estd. The method is useful in
assaying water streams from a kraft pulp mill for these
odorous cpds. 12 ref«
MacDonald, G. L. , W.C.F.P. Ltd., and Crofton, B. C., MONITOR
CUTS RECOVERY BOILER STACK LOSSES. 50%, Pulp Paper 40 (17),
39-41, (April 25, 1966).
An instr. for the continuous monitoring of Na losses in a kraft
black liquor recovery boiler stack is describedL The instr.
operates by measuring the conductivity of a continuous sample
soln. obtained by autom. mixing a const, flow of flue gases
with a const, flow of water. The monitor facilitates immediate
correction of elec. and mech. failures of the electrostatic
precipitators or the like used in chemical recovery from the
flue gases.
Banciu, I., DETERMINATION OF SODIUM SALT LOSSES IN THE FLUE
GASES OF SULFATE RECOVERY FURNACES, Celuloza Hirtie 15 (7),
253-7, (July 1966).
A method of sampling, analg., and calcg.Na salt losses from
kraft recovery boiler flue gases is presented which permits
the dust-retention capacity of electrostatic filters (pre-
cipitators) to be monitored and controlled.
Adams, D. F, and Koppe, R. K., DIRECT G[AS] L[IQUID]
CIHROMATOGRAPHIC] COULOMETRIC ANALYSIS OF KRAFT MILL
GASES, J.APCA 17 (3), 161-5, (March 1967).
A new Br microcoulometric titration cell (cf. A.B.I.P.C.
38: abstr. 862) was used with a commercially available
10-43
-------
microcoulometer for the detection and anal, of S-contg.
gases in various kraft pulp mill emissions. Sepn. of
the constituents of the gaseous mixts. emitted from mill
sources (such as the recovery furnace, digesters/ lime
kiln) is accomplished on a 8ft. X 3/16-inch, stainless
steel column packed with 10% Triton X-305 on 60-80 mesh
Chromosorb G. The column is isothermally operated at
30°C. for 4-6 min. and then rapidly heated to 70°C.
The exact program is varied with the type of sample
anald. Each source gas is initially screened by direct
injection of 0.01-0.1 mlo of gas to det. whether or
not disproportionately large concns, of one or more com-
ponents are present. Appropriate sample vols. are then
selected to provide "on-scale" recorder peaks for the
major constituents. Elution times for the major con-
stituents are noted so that these cpds. can be vented
at the proper time fig. injection of large sample vols.
(up to 10 ml.) when detecting and analg. minor constituents.
Venting of the high concn. cpds. is necessary when analg.
large vol. samples to maintain near equil. titration con-
ditions in the microtitration cell. 12 Ref.
Bethge, P. O., and Ehrenborg, L., IDENTIFICATION OF VOLATILE
COMPOUNDS IN KRAFT MILL EMISSIONS, Svensk Paperstid 70 (10),
347-50, (May 31, 1967).
In order to identify cpds. contributing to kraft mill odors,
qual. anal, were made of digester relief, blow gases, and
raw sulfate turpentine, using gas chromat. and-where necessary-
mass spectrometry. In the most volatile fractions, 25 cpds.
were identified in addn. to terpenes. Tabular data given
include rel. retention times. 3 Ref.
Cooper, S. R., and Haskell, C. F., CUTTING CHEMICAL ASH LOSSES
IN A KRAFT RECOVERY SYSTEM, Paper Trade J. 151 (13), 58-9,
(March 27, 1967).
Continuous monitoring of recovery boiler stack gases for dust
particles at the Oxford Paper Co, Rumford [Me.] kraft mill is
used in controlling burning and electrostatic precipitator
operation for minimum dust losses. The stack effluent measuring
system includes a Bailey Meter bolometer transmitter and light
source operating in conjunction with a receiver-recorder. The data
obtained are used in adjusting recovery boiler combustion con-
ditions and performing precipitator maintenance for minimum stack
losses. Tests have shown the efficiency of the precipitator to
drop from 95% at its rated load of 300 t./day to 51% at a load
of 370 t./day.
10-44
-------
Walther, J. E., and Amberg, H. R., CONTINUOUS MONITORING OF KRAFT
MILL STACK GASES WITH A PROCESS GAS CHROMATOGRAPH, TAPPI 50 (10),
108-10A, (October 1967) .
A "320 Beckman" process gas chromatograph was evald. inter-
mittently on a. recovery furnace for about 3 months. The instr.
was installed to obtain information about furnace operation,
esp. the emission of S cpds., and to det. whether it can be
used as a tool for closer control of malodorous flue gases.
During the 3-month trial period, several thousand samples were
taken and anald. for H S, SO , and MeSH. Fluctuations in
H S concnso from 100 to 400 ppm by wt. were recorded during
normal operation of the recovery furnace. "Blackouts" (loss
of fire) were preceded by high H S concns. The H S concn.
appeared to be a more sensitive parameter of furnace operation
than oxygen and combustible concns. It appears that the
process chromatograph may be used as an indicator of furnace
operation efficiency. 3 Ref.
Adams, D. F., Young, F. A., and Luhr, R. A., EVALUATION OF AN
ODOR PERCEPTION THRESHOLD TEST FACILITY, TAPPI 51 (3), 62-7A,
(March 1968) .
The design of a facility for the study of odor perception and
objectionability thresholds within a large humanl population
is described. A dynamic system of odor generation was used
to provide several test atmospheres in the ppb concn. range
within 6 exposure chambers. Panelists were consecutively
exposed to the 6 identical chambers, each contg. a different
concn. of the same cpd. (hydrogen sulfide) or purified air.
Test atms. were presented in ascending, descending, or random
order and ranged from undetectable to objectionable for most
panelists. The panelists reported for each chamber, whether
or not an odor was detected and, if so, whether it was
pleasant or unpleasant. In addition, each panelist provided
comprehensive personal information including age, sex, smoking
habits, respiratory abnormalities, occupation, and population
range of residence. The variability of individual response
was evald. for 11 trained panelists through repeated sequences
over a period of several days. The normal variation in threshold
for each individual and the entire test panel are discussed.
These data form a statist, basis for exam, of the response of
nearly 6000 untrained subjects who were exposed only once
to 5 concns. of a single cpd. in the 6 chambers. 4 Ref.
10-45
-------
Theon, G. N., DeHaas, G» G, and Austin, R. R, INSTRUMENTATION
FOR QUANTITATIVE MEASUREMENT OF SULFUR COMPOUNDS IN KRAFT
GASES, TAPPI 51 (6), 246-9, (June 1968).
Recording electrolytic titrator has been evaldo in quant, detns.
of S. dioxide, H sulfide, EtSH, MeSH, org. sulfide, and residual
S concns. After slight modification, the instr= gave rapid and
reliable anal, of ambient air and samples drawn from kraft
recovery furnace ducts, oxidn. tower vents, and lime kiln stacks.
By selecting the proper setting, H sulfide concns„ from 10 ppb
to 800 ppm can be detd. within 7-10 min. per sample. Anal, can
be performed in the lab. or at the sample-collection point, since
the app. is portable. 4 Ref.
Walther, J. E., and Amberg, H. R. , MOBILE LABORATORY FOR SOURCE-
SAMPLING KRAFT MILL EMISSIONS, TAPPI 51 (11), 126-29A, (November
1968).
A mobile lab. contg. thermal cond. and flame ionization detectors
and gas chromatographs for the analyses of malodorous emissions
from kraft mills was constructed. The analyses conducted at a
kraft mill showed that the malodorous emissions from the recovery
furnace and direct contact evaporator can be reduced to '<3 ppm.
Black liquor oxidn. efficiency >95% combined with proper operation
of the furnace was necessary to achieve this low level.
DeChoudens, C., QUANTITATIVE DETERMINATION OF SULFUR DIOXIDE
AND HYDROGEN SULFIDE BY SPECTROPHOTOMETRY IN THE GASEOUS
EFFLUENTS OF RECOVERY BOILERS IN A SULFATE PULP MILL,
ATIP 22 (2), 113-21, (1968)=
An app. is described for sampling the stack gases from pulp
mills. Particulate matter in the effluent is removed, the
temp is lowered, condensibles and water are removed, and
the gas is metered to the clorimetric analo system. H S
and SO are each detd. with a precision of 10%. The
effects of temp, and concn. of the anal = solns. on the
calibration curves are reported.
Adams, Donald F., ANALYSIS OF MALODOROUS SULFUR - CONTAINING
GASES, TAPPI 52 (1), 53, (January 1969).
The current state of the art for analysis of five major sulfur-
containing gases in ambient air-sulfur dioxide, hydrogen sulfide,
methyl mercaptan, dimethyl sulfide, and dimethyl disulfide-is
10-46
-------
presented, inherent errors described, and improvements proposed.
Variability in the cadmium hydroxide slurry-methylene blue pro-
cedure for hydrogen sulfide is eliminated by addition of 1%
STRactan 10 to the absorbing media. Errors in the lead acetate
tape technique for determination of hydrogen are restated. The
potential interference from dimethyl disulfide in the colorimetric
determination of methyl mercaptan is defined. An automatic
technique for separation and analysis of the five sulfur-
containing gases is described.
Bamesberger, W. L. and Adams, Donald P., FIELD COMPARISON OP
THE COULOMETRIC, COLORIMETRIC, AND LEAD ACETATE TAPE ANALYSIS
METHODS FOR SULFUR-CONTAINING GASES, TAPPI 52 (7), 1302,
(July 1969).
A continuous, microcoulometric analyzer, utilizing preselective
filtration, has been used for a field study of the varying atmos-
pheric concentrations of sulfur dioxide, hydrogen sulfide,
methyl mercaptan, dimethyl sulfide, and dimethyl disulfide in
the vicinity of a kraft pulp mill. The microcoulometric
analyzer was operated on a 5-min. sequence for each of the five
sulfur-containing compounds and a 5-min. instrument blank, there-
by yielding a complete analysis cycle every 30 min. Another
coulometric analyzer with lower sensitivity was lused as a total
sulfur gas analyzer. Comparative 2-hr, average |data were
obtained for hydrogen sulfide and sulfur dioxide by using
midget impingers in a sequence sampler. Chemical analyses were
conducted by the cadmium hydroxide - STRactan - methylene blue
and modified West-Gaeke methods, respectively. A third com-
parison for hydrogen sulfide was obtained by using the lead
acetate tape method. The data show agreement for hydrogen
sulfide by the microcoulometric and cadmium hydroxide-STRactan-
methylene blue methods but not with the lead acetate tape tech-
nique. Agreement was also obtained for sulfur dioxide by the
microcoulometric and modified West-Gaeke methods, although
all observed sulfur dioxide levels were near the sensitivity
limits for these methods.
Theon, G. N., DeHass, G. G, and Austin, R. R., CONTINUOUS
MEASUREMENT OF SULFUR COMPOUNDS AND THEIR RELATIONSHIP TO
OPERATING KRAFT MILL BLACK LIQUOR FURNACES, TAPPI 52 (8),
1485, (August 1969).
A continuous instrument has been designed and built to measure
sulfur dioxide and reduced sulfur compounds in the parts-per-
million and parts-per-billion ranges. The instrument has been
placed in operation on several black liquor recovery furnaces
before the direct contact evaporator. Operation parameters under
most possible conditions have been measured and correlations between
sulfur dioxide and reduced sulfur compounds have been made. Steam
production and degree of smelt reduction have also been determined
in relation to the concentrations of the sulfur compounds.
10-47
-------
Thoen, G. N., DeHaas, G. G., and Baumgartel, F. A., CON-
TINUOUS SULFUR DIOXIDE ANALYZER AND ITS APPLICATION TO SUL-
FITE RECOVERY EMISSIONS, TAPPI 52 (12), 2304- (December,
1969).
A continuous recording SO analyzer with a variable range
of measurement has been developed. The equipment is simple
and corrosion-proof. The principle of operation is ultra-
violet emission at specific SO absorption. Water vapor
and other compounds do not interfere. A unique sampling
system has been devised to assure continuous, accurate
sampling across the full duct so that averages need not
be taken. Measurement with subsequent control can minimize
SO losses from the absorption towers of the sulfite re-
covery system.
Tretter, V. J., USE OF CONTINUOUS MONITORS OF SODA LOSS AND
MALODOROUS SULFUR LOSS IN PROCESS CONTROL, TAPPI 52 (12),
2324-, (December 1969).
Continuous monitors were used to measure soda loss and mal-
odorous sulfur loss. Normally both instruments monitor the
main stack, which contains combined flue gases from three
recovery furnaces and three lime kilns. The sulfur monitor
has been found to be effective for indirectly and continuously
monitoring the efficiency of the black liquor oxidation sys-
tem. The monitor has also been used to characterize the con-
tributions of the recovery furnace, cascade evaporators, re-
covery scrubbers, and lime kilns to total malodorous sulfur
loss. The soda loss monitor provides accurate soda loss
data and will detect firing rate changes in the furnace and
precipitator malfunctions. Continuous monitors proved to
be superior to wet sampling methods and have adaptability to
process control.
10.4.1 RESEARCH NOT REPORTED IN THE LITERATURE
In addition to the foregoing, NCASI has identified the follow-
ing categories of research or specific projects which presently
are under way in the industry. Results may or may not be re-
ported eventually in the open literature. It is not possible
at this time to define the scope of work more completely nor
to indicate the level of effort.
a. Mill-scale evaluation of sodium-specific ion electrodes
conductivity cells, flame photometers and photoelectric
cells as means for continuously monitoring recovery fur-
nace particulate emissions as a means of reducing such
emissions through more effective operation of high
efficiency particulate collection devices.
10-48
-------
b. Improvement of techniques for sampling hot, wet, corrosive
gas streams.
c. Examination of particulate collection efficiency of various
emission source sampling procedures (particle filters and
scrubbers in various combination and retention capabilities.
d. Selection of optimal analytical procedures for determination
of residual sulfide levels following black liquor oxidation.
e. Investigation of new excess oxygen analyzers for use in
recovery furnaces and lime kilns for combustion process control,
f. Development of techniques for scanning recovery furnace smelt
bed for combustion process control.
g. Differentiation of reduced sulfur compounds using various
filter systems in conjunction with coulometric, flame photo-
metric and infra red absorption instruments to achieve sensi-
tivity in the ambient ppb range.
h. Selection and development of suitable sulfur oxides analyzers
for use in sulfite pulping inventory studies.
i. Development and application of organoleptic 'techniques for
evaluation of emission control systems. \
j. Development of techniques for optimal design of mill ambient
air quality monitoring programs.
10-49
-------
10.5 CONTROL EQUIPMENT DEVELOPMENT
Control of most emission in the industry is brought about
by add-on devices. The state of the art is described
in Chapters 5 and 6. Research in the past has been
concerned mostly with recovery of particulates. In
recent years more effort is being devoted to reduction
of odorous sulfur gases. Generic types of collectors
are well known, but the effectiveness of scrubbing liquids
in removing the various gases encountered is not well
known.
Maksimov, V. F., and Torf, A. I., JET-TYPE APPARATUS FOR
THE PURIFICATION OF FLUE GASES, Bumazh. Prom. 39 (5),
6-7, (May, 1964).
An exptl. jet-type gas scrubber for the removal of dust
from flue gases of soda recovery furnaces was installed
recently at the Segezha Combine. The principle of the
scrubber operation consists in mixing the gases, in a
vert, constricted tube, with a mist of water introduced,
by means of mech. nozzles, under a pressure of 6-12 atm.
Exptl. data are presented showing the dependence of the
scrubbing efficiency of the app. on the flow rate of
gases in the constricted part of the tube, the amt. of
water fed into the tube, the conditions, the efficiency
of dust removal was 96-97%, at initial dust concns. of
up to 9.35 g./cu.m. 2 ref.
Maksimov, V. F., Torf, A. I., and Lesokhin, V. B., A JET
FLUE GAS SCRUBBER FOR SODA RECOVERY BOILERS, Bumazh. Prom.
39 (11) , 17-18, (Nov., 1964).
The gas scrubber described comprises four high-pressure
(8-11 atm.) spray nozzles, distributed so that they form
a circle, from which a stream of water is introduced into
the path of the flue gas. The app. acts as an exhaust fan
(by its sucking effect), as a scrubber to remove suspended
solids and SO-, and as a heat exchanger. At a water jet
pressure of 10 atm. and a water flow rate of 13 cu.m./hr.,
the underpressure in the flue is up to 10 mm. HO. The
water, by passing through the app., is heated to 60°C.
(from about 2°), and the gases are cooled from 170-200° to
65-70° .
The efficiency of the scrubber is up to 96% with respect
to solids particles, and 65-70% with respect to SO . The
scrubber was installed at the Astrakhan board mill and was
tested under ind. conditions.
10-50
-------
Clark, J., HOW [PULP] MILLS USE [GAS] SCRUBBERS, Pulp Paper
39, (32) , 31-3, (Aug. 9, 1965).
The author recommends the use of fiberglass-reinforced
polyester for the construction of scrubbers. To handle
corrosive matls., the entire system should be fabricated
of corrosion resistant matls. The use of scrubbers in
the recovery of sulfur dioxide, Cl, Cl dioxide, and in
the control of discharge of mercaptans and hydrogen sulfide
is discussed briefly.
Maksimov, V. F., Torf, A. I., and Lesokhin, V. B., TESTING
OF A TWO-STAGE GAS SCRUBBER, Bumazh. Prom. 40 (10), 13-15,
(Oct., 1965). ^
A series of ind. tests was performed to det. the efficiency
of a. two-stage gas scrubber mounted on a Tapella soda-regenera-
ting boiler, and sprayed with black liquor. The scrubber
(installed recently with the Tampella boiler at the Astrakhan
pulp and board mill) is described and the results of the tests
are tabulated. They include the cpn. of the gases before
purification, the operating variables of the first and
second purification stages, and the purification efficiency.
The overall purification efficiency of the scrubber was up
to 93.5% and its efficiency in absorbing sulfur dioxide and
hydrogen sulfide was 93-95%.
Maksimov, V. F., Bushmelev, V. A., Torf, A. I., and Lesokhin,
V. B., TESTING THE TURBULENT FLOW VENTURI APPARATUS, Bumazh
Prom. 40 (5), 14-15, (May, 1965).
A turbulent-flow Venturi scrubber (TAV) was installed recently
on the soda recovery boiler at the Kherson kraft mill, and
was subjected to a series of tests to det. its efficiency.
The TAV consists of a Venturi tube, spray tubes, and condensation
trap. Black liquor is used as the spray liquor. According
to exptl. data obtained SO is absorbed to the extent of 96-
98%, and the scrubber is equally effective in removing suspended
dust particles. There was no evolution of H.S or disturbances
of the combustion process (e.g., a too low supply of 0 ).
Since in preliminary expts., carried out with model equipment
at another mill, there was evolution of H_S, this problem was
further investigated. It was found that the black liquor of
the Kherson mill contains considerably less residual Na S as
compared with the black liquor used in model expts., due to
lower sulfidity of the white liquor. In addn., the vacuum
10-51
-------
filters, used at the mill for washing pulp, promote
a partial oxidn. of the black liquor/ further reducing
its Na S content. The purification of gases in the
TAV scrubber was accompanied by addnl. evapn. of
black liquor, caused by contact with hot gases at the
throat of the Venturi tube. The TAV scrubber is thus
also an effective heat exchanger. Other factors
affecting the scrubbing efficiency of the app. are
the flow velocity of the gases in the Venturi tube
throat, the concn. of the black liquor, its amt.
used for spraying, and its temp.
Shah, I. S., and Mason, L., NEW TWO-STAGE EVAPORATOR-
SCRUBBER SYSTEM FOR EFFICIENT RECOVERY OF HEAT, FUME,
AND DUST FROM RECOVERY BOILERS, TAPPI 50 (10), 27-32A,
(Oct., 1967).
The 3 systems in prevalent use in N. Am. for heat and
chem. recovery from kraft recovery furnaces (viz., the
cascade-precipitator, cyclone-precipitator, and P-A
Venturi evaporator-scrubber) are unable to meet the
increased requirements for overall dust-collection and
odor-removal efficiencies specified by recent federal,
state, and local legislation and regulations. For
this reason, a new 2-stage system comprising an S-F evapo-
rator, an S-F scrubber as separator, and a cooler has been devd.,
which is said to offer higher thermal efficiency,
comparable or greater dust-collection efficiency,
minimum maintenance, and high flexibility of operation
in that the evaporator performance is indep. of the
scrubber's performance. The S-F Venturi scrubber can
also be used as a single-stage system by mills considering
a cyclone or cascade evaporator as a direct-contact
evaporator as well as by mills about to replace their
precipitator by a wet scrubber. In addn., 3 secondary
scrubbing systems have been devd. (vis., cyclonic,
S-F Venturi fig. a cascade-precipitator, and S-F
Venturi fig. a P-A Venturi for improving dust-collecting
and/or thermal recovery efficiencies in mills having a
cascade or P-A Venturi System. The design and operation
of these new systems are described and sketched. 4 ref.
10-52
-------
Shah, I. S., NEW FLUE-GAS SCRUBBING SYSTEM REDUCES AIR
POLLUTION, Chem Eng. 74 (7), 84-6, (March 27, 1967).
In the kraft pulping process, the burning of black liquor
is a necessary step because it recovers heat and chemicals,
However, this also releases dust and S-contg. gases into
the atm. In a new Venturi scrubbing system (Chemical
Construction Corp.) described, 99% of the dust is removed
from the flue gases, and an improved oxidn. step greatly
reduces the amt. of H S released to the atm. A process
flowsheet is included.
Malarkey, E. J., and Rudosky, C., HIGH EFFICIENCY KRAFT
MILL PRECIPITATORS, Paper Trade J. 152 (40) , 57-8, (Sept.,
1968).
A dry collection system for recovery boilers in kraft mills
is compared with a dry-wet system. Although high efficiency
electrostatic precipitators can minimize fall-out or snowing,
the dry-wet system can virtually guarantee that it will not
occur. Comparative installation and operating costs are
presented.
Aho, W. O., THE JENSSEN EXHAUST SCRUBBER - AN EFFECTIVE AIR
PROTECTION SYSTEM , TAPPI 52 (4), 620, (April 1969). |
A system incorporating a bubble cap tray absorption column
was designed and installed to recover sulfur dioxide from
two Jenssen tower exhausts. With this system the exhaust
gases are scrubbed with a sodium hydroxide-sodium bisulfite
solution, and the resulting liquor is used in a neutral sulfite-
ch emimechanical pulping process. Potential problems stemming
from sulfur trioxide and carbon dioxide in the gases were
evaluated. Other types of scrubbers were examined. The
design procedure for the scrubber is reviewed and a description
of the recovery process is included. Both a source of air
pollution and economic loss were eliminated.
10-53
-------
10.6 PROCESS CHANGES AFFECTING EMISSIONS
Major, W. D., VARIATIONS IN PULPING PRACTICES WHICH MAY
EFFECT EMISSIONS, in Atmospheric Emissions from Sulfate
Pulping (E. R. Hendrickson, Ed.), April 1966.
Emissions from a kraft mill can be divided into two cate-
gories, gaseous and particulate. Malodorous emissions are
subject to far less control and precision of analysis than
particulate emissions. The magnitude of loss is more
sensitive to operating variables, the chemistry is more
complicated and the sources are more numerous„ This dis-
cussion is concerned with the effect of operating variables
on gaseous sulfur losses. Evidence is given which indicates
that the wood species has a definite effect on the odor
produced during kraft pulping. Cooking variables include:
sulfidity of the white liquor, cooking time and cooking
temperature. More recent cooking variables are: continuous
vs. batch digestion and the use of black liquor dilution in
the digester as a means of controlling the liquor-to-wood
ratio. Multiple-effect evaporators are the second largest
source of gaseous sulfur losses in the process. The high
vacuums set up by condensers result in the release of low
vapor pressure sulfur compounds. Operating variables in
direct contact evaporation are: black liquor pH, sodium
sulfide concentration, and percent CO in the flue gas.
Dust losses from the recovery furnace are controlled with
either a Venturi scrubber or an electrostatic precipitator.
Operating variables which influence the efficiencies of
these two units are overloading, and the temperature of the
flue gas. The key to the effect of operating variables on
emissions from a kraft pulp mill is to recognize the degree
to which the various steps in the kraft process are inter-
related, especially in the case of gaseous sulfur losses.
Harkness, A. C., and Murray, F. E., GAS PHASE OXIDATION OF
METHYL MERCAPTAN, Air S Water Pollution 10 (4) , 245-51, (April,
1966) .
The reaction between Me mercaptan and 0 in the gas phase has
been examd. in temp, range 201-275°C. S. dioxide is the chief
prod, of the reaction, being formed together with methane at
10-54
-------
the start of the reaction. Other prods, are carbon monoxide,
carbon dioxide, H, HCHO, and MeOH. In the presence of
excess 0, complete conversion to S dioxide is obtained
quickly at 275°C. At lower temps, and lower 0 content much
of the S remains unaccounted for. In confirmation of previous
work, the rate of reaction was found to be strongly ac-
celerated by 0 and to be inhibited by mercaptan.
Fischer, H., THE GLAUS PROCESS AND ITS MODIFICATIONS, Chem.-
Ing.-Tech. 39 (9/10), 515-2, (May 24, 1967).
The ever-increasing interest in pollution control has led
to a re-exam, of the Glaus process for the recovery of S
from H S-contg. waste gases through the bauxite-catalyzed
reaction of the waste gases with atm. O in a special combustion
chamber. Various modifications of the process have been devd.,
some of which are specially designed for trg. the H S-contg.
waste gases of a particular ind. (e.g., the petroleum ind.,
the pulp ind., etc.). Several Glaus recovery systems are
diagrammed, incl. 2 examples for pulp mill installation. 4 ref.
Murray, F. E., and Rayner, H. B., OXIDATION OF DIMETHYL DISULFIDE
WITH MOLECULAR OXYGEN, PulpSPaper Mag. of Can. 69 (9):, 64-7,
(May 3, 1968). '
The rate and mechanism of oxidn. of dimethyl disulfide with
oxygen in aq. NaOH was studied at temps, from 25 to 125°C.
In this interval, the oxidn. rate is controlled by the O mass
transfer rate, except at low disulfide concns. The reaction
mechanism seems to involve alk. hydrolysis of the disulfide
to form NaSMe (mercaptide) and NaOSMe (methanesulfensate) fid.
by oxidn. of the MeSNa to disulfide while the MeSONa is oxidized
to MeSO Na (sulfonate) which is the primary end-prod, of the
oxidn. These results indicate that the malodorous S cpds.
in kraft mill condensates can be rendered rel. innocuous by
oxidn. to methanesulfonic acid. For air pollution control,
pure 0 in a pressurized reactor would be needed. (An air
stream would strip much mercaptan and disulfide from the water
before they could be oxidized). Although the methyl mercaptide
ion in black liquor is readily oxidized to dimethyl disulfide,
much mercaptan in com. plants is given off with noncondensibles
from the multi-effect evaporators. This MeSH is probably formed
from the disulfide during black liquor storage and evapn. as a
result of alk. hydrolysis at the elevated temps, used. 10 ref.
10-55
-------
Gullichsen, J., Saiha, E., and Westerberg, E. N. , RECOVERY
OF SODIUM-BASE PULPING CHEMICALS BY BICARBONATION AND CRYSTAL-
LIZATION, TAPPI 51 (9), 395-400, (Sept. 1968)
A modified chem. recovery process is presented, based on
reductive burning of spent liquor and carbonation of green
liquor with CO -contg. flue gases. The precarbonated green
liquor is reacted with Na bicarbonate at boiling temp., pre-
ferably in a slight vacuum, to liberate" HS and form Na carbonate
which can be crystd. simult. or sep. The bicarbonate needed
is produced by carbonation of crystd. Na carbonate with flue
gases. Both lab. and pilot-plant trials showed that a highly
coned, pure H S gas and clean carbonate (monohydrate) crystals
can be produced, and that carbonation of soda with flue gases
yields pure cryst. bicarbonate. The process is suitable for
chem. recovery and cooking liquor regeneration in both acid
and alk. processes, and is ep. adaptable to cross-recovery
operations. 8 ref.
Izumrudova, T. V., Parashina, F. I., and Shorygina, N. N.,
MODIFICATION OF SPENT SULFITE LIQUORS BY CHLORINATION, Bumzah.
Prom. 43(11) , 34, (Nov., 1968).
LSA isolated from a com. SSL from mixed Ca/Na base cook,
and from a lab. cook of extd. sprucewood sawdust with a di-
sulfite liquor contg. 8.5% sulfur dioxide, were dried over P
pentoxide and anald. to det. their empirical formulas. The
two prepns. which differed in their contents of S and C and
contained no ash elts., were then chlorinated in an aq. medium
and in carbon tetrachloride. Chlorination in the aq.medium
was more extensive yielding derivs. with 13 Cl atoms/10
phenylpropane units. In the non-aq. medium, 6-8 Cl atoms
were introduced/10 units. The S. content remained unchanged in
all expts., but chlorination was accompanied by oxidn. (as
evidenced by an increase of the O content) and by demethoxylation.
Changes in the chm. cpn. of the LSA upon chlorination were
confirmed by their IR spectra. Of pract. interest is the
chlorination of the residual liquor from ale. fermentation of
SSL. The chlorinated residual liquor is a surface-active agent
stable in media contg. mineral cpds,; these props, make it esp.
well suited for use as a drilling fluid additive and as a cement
suspension stabilizing agent. 2 ref.
10-56
-------
10.7 CHEMISTRY OF POLLUTANT FORMATION OR INTERACTIONS
For a complete tinderstanding of the effect of pulp mill
emissions on the environment and to provide a firm base
for developing control technology, an appreciation of how
the pollutants are formed is essential. Partly because
of the unavailability of reliable analytical techniques,
development of the required information was slow. It
has only been in recent years that more complete knowledge
of the chemistry and kinetics of odor formation from
kraft pulping is developing. Reactions in the atmosphere
after discharge are still largely unknown. The relation-
ship between particulates and gases in odor transmission
is also unanswered.
McKean, William T., Jr., Hrutfiord, Bjorn. P., and Sarkanen,
K. V., KINETIC ANALYSIS OF ODOR FORMATION IN THE KRAFT PULPING
PROCESS, TAPPI 48 (12),699-704, (Dec., 1965).
The kinetics of the consecutive formation of MeSH and Me S
at const, liquor cpn. were detd. at several temps, using
a novel gas anal, technique based on vapor-phase sampling.
Comparative kraft cooks of softwoods vs. hardwoods shows
that more org. S. cpds. are produced from hardwoods. During
the alk. delignification of softwoods, the reactivity of
lignin MeO groups is enhanced, which results in accelerated
odor formation during the last phase of pulping. The
activation energies of the reactions suggest that the
formation of org. S cpds. may be substantially reduced by
raising the reaction temp, and shortening•- the duration of
the kraft cook. These findings suggest that kraft mills
without odor problems should operate by maximizing cooking
temp., minimizing cooking time and sulfidity, and improving
oxidn. of black liquor early in the evapn. phase. Continuous
digesters hold more promise than batch digesters. 27 refs.
Uchida, T. , and Shirota, F., STUDIES ON VOLATILE MATTER IN
KRAFT COOKING, (1) VOLATILE MATTER IN THE KRAFT COOKING OF
HARDWOODS, J. Jap. TAPPI 19 (10)/ 479-87, (Oct., 1965).
The volatiles obtained from ind. kraft cooks of hardwoods
(compared to softwoods) were factionally distd. and examd.
10-57
-------
for b.p., and sp.gr., refractive index, optical rotation,
and IR spectra. The crude condensed volatiles differed
considerably in phys. props, from those obtained in soft-
wood kraft cooks. The essential oil components in the
crude condensate of hardwoods had rel. high b.p. Colored
and malodorous cpds. of low b.p. (aldehydes, ketones, ales.,
furans) were found in hardwood volatiles, but not in soft-
wood condensates. The a-pinene content was ca. 40%, i.e.,
somewhat less than in the crude condensates from softwoods.
Components identified in the rectified fractions included
mixts. of ales., ketones, aldehydes, furan, a-pinene, dl-
limonene, cadinene, and azulene.
Sokolva, O. I., and Maksimov, V. F., EQUILIBIRUM CONCENTRATIONS
OP S-CONTAINING GASES IN RELATION TO DEODORIZATION OF FOUL-
SMELLING EFFLUENTS FROM PULP MILLS, Bumazh. Prom. 40 (17),
122-6, (1965).
In connection with the construction of new large kraft mills,
the problem of purification of effluents from S cpds. became
urgent (at present, most mills simply discharge such effluents
into the rivers, causing considerable pollution and damage to
the fishing ind.). A study made at the Segezha kraft mill showed
that during aeration of S-contg. effluents, two processes take
place, viz. the desorption of gases from soln., and oxidn. of
S cpds. by the O of the air. The desorption process is based
on mass transfer, and the rate of transfer is detd. by the
equil. conditions, and is proportional to the degree by which
the system is shifted from the equil., i.e., to the difference
between the actual and the equil. concn., this difference being
the "driving force" of the mass transfer process. In the
equation M = KFAC_ (where M is the amt. of substance transferred
from one phase into the other, F_ is the surface area of contact
of phases, 1C is the mass transfer coeff.), the driving force
AC_ can be expressed as a function of the initial and final
equil. concns. of a given substance and of the initial and final
actual concns., and hence can be calcd. and used for computing
the aeration equipment. The equil. conditions of the S cpds.
were studied in digester relief condensate (the aq. phase after
removal of turpentine), and in the first and second stage con-
densates from black liquor evapn., by sep. detns. of partial
vapor pressures of each component at temps, from 25 to 85°C.
From the exptl. data empirical formulas were obtained expressing
the partial pressures at equil. for hydrogen sulfide, MeSH,
methyl sulfide, and methyl disulfide as functions of the concn.
in the liquid phase and temp.
10-58
-------
Landry, J. E., THE EFFECT OF A SECOND ORDER CHEMICAL REACTION
ON THE ABSORPTION OF METHYL MERCAPTAN IN A LAMINAR LIQUID JET,
Ph.D. Thesis, Louisana State Univ., 1966 (188 pages).
The laminar liquid jet was used in obtaining basic data on
abosrption of MeSH in an aq. NaOH soln. because its unique
fluid dynamic and operating characs. permit the use of the
penetration theory for the description of the process. These
data are needed for air pollution control in the paper ind.
The diffusion coeffs. of CO , SO , and MeSH in water at 25°C.
were measured. The gas absorption rates in the liquid jet
follow the penetration theory results over the studied contact
time range of 2.5 to 30 milliseconds. Absorption data for
MeSH in aq. solns. of NaOH were correlated to penetration
theory values for an infinitely fast irreversible reaction.
The diffusion of the OH ion determines the effect on the mass
transfer rate. The reaction of the dissolved MeSH with the OH
ions is a very fast second order irreversible reaction. The
kinetics of this reaction were inferred by extension of the
penetration theory values in the parametric range studied.
The absorption of dil. gas solns. of MeSH in aq. NaOH
contacted in a packed absorber was predited by a
method of caln. based on the penetration theory, j Knowing
the reaction kinetics and the phys. absorption consts.,
the height of chemical absorbers can be calcd.
Feuerstein, D. L., A STUDY OF MALODOROUS PRODUCTS FROM
THERMAL DECOMPOSITION OF KRAFT BLACK LIQUOR, Ph.D.
Thesis, University of California, Berkely, 1966.
Lab, app., procedures, and anal. methods were devd. to
study the thermal decpn. of kraft black liquor. Emphasis
was placed on pyrolysis in the absence of atm. O within
the temp, range 400-970°C. Twenty individual unidentified
S cpds. in addn. to those commonly reported as being present
in recovery furnace stack gases, were isolated from the
condensable pyrolytic gases. Detectable noncondensible
constituents in the pyrolytic gases included H, CH , C2H5'
acetylene, H S, Me S, Me S , Co and CO_. A minimum of
20% by wt. of the total S was contained in the solid
phases (residue) at 700°. This increased to nearly 40%
at 970. The decreasing rate of S increase in the residue
indicated that less than half of the total S would be con-
tained in the solid phase at temps, approaching 1500°. A
process is hypothesized to replace the recovery furnace and
direct contact evaporator and eliminate the need for an oxidn.
tower. This process should significantly reduce the malodorous
gaseous emissions from the overall chem. and heat recovery
system while providing a more controllable operation.
10-59
-------
Douglass, I. B., and Price, L., STUDY OF METHYL MERCAPTAN AND
DIMETHYL SULFIDE FORMATION IN KRAFT PULPING, TAPPI 49 (8),
335-42, (Aug., 1966) .
The formation of MeSH (I) and methyl sulfide (II) in kraft
pulping was studied to determine the influence of wood sp.,
cooking temp., sulfidity and cooking time. Digestions were
carried out on a semimicro scale, using 1.0 g. of wood and
4.0 ml. of cooking liquor in a 7.5 ml. stainless steel digester.
Four woods (spruce, loblolly pine, red maple, and paper birch)
were digested at 150, 160, 170, and 180° C. for 1, 2, 3, and
4 hr. at 14.7, 22.2, and 30.5% sulfidities. After each cook,
the digester contents were acidified to liberate (I), and the
amts. of org. S cpds. formed were detd. by gas-liquid chromat.
Under comparable conditions, hardwoods produced more (I) and
(II) than did softwoods. Cooks carried out at lower temps.
and for shorter times produced more (I) and (II) , whereas
cooking at higher temps, and for longer periods, esp. at high
sulfidity, produced much more (II) than (I). Curves prepd.
from the data clearly demonstrate that (I) is the primary prod.
and is consumed in the formation of (II) . Extrapolation of
results obtained on this semimicro scale agree well with results
reported from mill and pilot-plant studies.
Stanik, V., Polak, M., and Wolf, J., MECHANISM OF DIMETHYL
SULFIDE FORMATION FROM KRAFT BLACK LIQUOR, Sb. Vyskum, Prac.
Odboru Celulozy Papiera No. 11, 185-200, (1966).
The amt. of S-cpds. (MeSH, dimethyl sulfide, and dimethyl disulfide)
in black liquor increases during concn. to a dryness of 50-60% and
subsequent trmt. with Na sulfide at 220-300 C. It is gen. agreed
that dimethyl sulfide (DMS) is formed in two stages. In the first,
NaSH present in the liquor demethylates lignin with the formation
of MeSH. The latter, or MeSNa, demethylates further portions of
lignin yielding DMS. In a study of the mechanism of DMS formation,
the possibility was investigated of its originating from MeSH.
When heated 1 hr. at 260°C., MeSH was converted into DMS to the
extent of 45%. Under similar conditions, MeSNa conversion into
DMS was 68.4%. Considering that in the prodn. of DMS from black
liquor there is an equil. between MeSH in the vapor phase and
MeSNa in soln., it can be concluded that DMS is formed both in
soln. and in the vapor phase. To study the reaction of NaOH
10-60
-------
with the Me groups of lignin, two series of expts. were
conducted with black liquor. In the first, 1000 ml. liquor
sample contg. 38.1 g=, NaOH was heated 2 hrs. at 20°C. The
yield of DMS was 73.74% of theoretical. In the second series,
a similar sample contg. 69,9 g. NaOH was heated under the
same conditions. The yield of DMS was 36.87%. The lower
yield in the second series can be explained by more extensive
demethylation of lignin with the formation of MeOH which, as
exptl, demonstrated, has a low reactivity. When MeOH was
heated with hydrogen sulfide or Na sulfide the yield of
DMS was very loWo Consequently, the reaction of NaOH with
lignin can be regarded as secondary in the formation of DMS.
From the pract. viewpoint, the concn. of NaOH in the prepn.
of DMS from black liquor should be as low as possible, i.e.,
just sufficient to maintain the viscy. of the soln,, at a level
compatible with the reaction. 12 ref.
McKean, W. T., Jr., Hrutfiord, B.F., Sarkanen, K. V., Price,
L., and Douglass, I. B., EFFECT OF KFAFT PULPING CONDITIONS
ON FORMATION OF METHYL MERCAPTAN AND DIMETHYL SULFIDE, TAPPI
50 (8), 400-405, (Aug., 1967).
Rev. of available data on the formation of MeSH and DMS in
kraft pulping allows estn. of the kinetic characs. of these
reactions for softwoods. The summative rate of MeSHjplus
DMS formation is proportional to the initial hydrosulfide
(HS) concn. in accordance with an S 2 mechanism. The formation
of DMS from MeSH and lignin MeO groups appears to be subject
to some unusual catalytic effects. Larger amts. of MeSH
and DMS are produced from hardwoods than from softwoods,
because of a rapid initial demethylation of some labile
MeO groups. In softwood cooks the formation of DMS can be
reduced by short high-temp, cooks, while the temp, effect
on MeSH formation is rather insignificant. More effective
redn. of odor formation is possible by lowering the sulfidity
and by minimizing black liquor recycling. 23 ref.
Peuerstein, D. L., Thomas, J. F., and Brink, D. L., MALODOROUS
PRODUCTS FROM COMBUSTION OF BLACK LIQUOR: (1) PYROLYSIS AND
COMBUSTION ASPECTS, (2) ANALYTICAL ASPECTS, TAPPI 50 (6), 258-62,
276-85, (June, 1967) .
Undersirable side-effect malodors customarily assocd, with the
kraft process may originate at 6 major points in the total system
comprising digestion, inorg. chem. and heat recovery, and org=
waste disposal. The recovery furnace is the major source of
10-61
-------
malodorous air pollution, fid. by evaporators, digester, lime
kiln, oxidn. tower, and dissolving tank. In this study, the
recovery furnace operation was assumed to include distn.,
sublimation, pyrolisis, auto-oxidn., stoichimetric combustion,
and quenching. Single charges of spent reaction liquors were
carried sequentially through these various steps in the lab.
under controlled conditions, and all prods, were quant, collected
and anald., thus considering the simult. individual processes
in a furnace from the air-pollution standpoint. Results
pointed to several unique control possibilities. Combustion
techniques and sample collection are described in some detail.
The gaseous and liquid produs. isolated from pyrolyzates of
black liquor were anald. quant, by gas-liquid chromat. and
qual. by flame ionization. More than 60 components were
detected in the pyrolysis liquid, of which at least 32 were
also present in the gas phases despite thorough condensation
at 0°C. Detn. of S was based on microcoulometric titration
using a newly devd. app. which detected H S, MeSH, Me^S,
Me2S , and at least 19 addnl. tentatively identified or
unidentified S cpds. of which 17 were detd. quant. Low-
boiling org. and inorg. cpds. in the gas phase were conductivity
measurements. Quant, detns. were made of H, O, N, CO, CO ,
CH , C H , and acetylene, whereas H S, MeSH, and 5 unidentified
components could be distinguished qual. The S in pyrolysis
residues was detd. by wet combustion. Within the exptl error,
total S of all prods, equalled the total content of the
original black liquor, and total S of pyrolysis prods, (excl.
the residue) accounted for 70% of the black liquor S. Changes
in cpn. of prods, with changes in pyrolysis (combustion)
conditions indicated that increased emphasis should be placed
on the overall combustion process to further reduce malodorous
emissions. 32 refs.
A. C. Harkness and Murray, F. E., REACTION BETWEEN METHYL
SULFIDE AND OXYGEN IN A STATIC SYSTEM, Atmos. Environ. 1 (4),
491-7, (1967) .
Me?S and O react explosively at temps, as low as 210°. At
195°, the nonexplosive reaction has an initiation stage and
a main stage. The rate of the main stage detd. from pressure-
time curves is linearly dependent on initial O pressure, but
substantially independent of initial Me S pressure. The
extent of the initiation stage is reduced by increase in the
O pressure. The chief oxidn. products are SO and CO. Even
with an excess of O not all the Me S reacts.
10-62
-------
Hales, J. M., AN INVESTIGATION OF THE REACTION BETWEEN HYDROGEN
SULFIDE AND OZONE IN A LAMINAR-FLOW REACTOR, Ph.D. Thesis,
University of Michigan, 1968 (160 pages).
Exptl, data were obtained from 2 tubular laminar-flow
reactors of varying dimensions concerning the kinetics
of the reaction between hydrogen sulfide and ozone. Based
on the data, a math, expression was devd. giving the rate of
sulfur dioxide generation in the absence of light. Comparison
of the data from the 2 reactors indicates that the reaction
is almost totally homogeneous with the tubular laminar flow
reaction rates. The study is related primarily to air
pollution research, incl. work in the pulp and paper ind.
99 refs.
McKean, W. T., Jr., KINETICS OF METHYL MERCAPTAN AND DIMETHYL
SULFIDE FORMATION DURING KRAFT PULPING, Ph.D. Thesis, University
of Washington, 1968 (118 pages).
The kinetics of the demethylation of lignin during kraft pulping
by hydrosulfide ion to form MeSH and dimethyl sulfide (DMS) were
studied. Exptl. data were obtained using lab. microdigesters
and a gas chromatograph for anal. of prods. Rate data were
obtained for demethylation of wood meal by kraft liquor and
by alk. solns. of MeSNa in the temp, range of 150-2103C. The
results indicated that sulfide and hydrosulfide ions have approx.
the same reactivity with MeO groups of lignin. Diffusion
processes did not affect the reaction rates. Furthermore, the
extent of irreversible hydrosulfide bonding with lignin by
degradation reactions was found to be very small (max, 0,4% by
wt. of lignin). Larger amts. of MeSH and DMS are produced
from hardwoods than from softwoods, because of rapid initial
detachment of some labile MeO groups. Nonionized MeSH is in-
effective in reaction with lignin MeO, but its ionized form is
a strong nucleophilic demethylating agent. The summative rate
of MeSH + DMS formation is proportional to the intial hydrosulfide
ion and MeO concns. Furthermore, the formation of DMS is
proportional to MeS (mercaptide ion) and MeO concns. These
results are in accordance with a second-order nucleophilic
substitution rate model for demethylation. In gen., effective
redn. of odor formation is possible by using the highest
pulping temp, consistent with pulp quality, by lowering the
sulfidity, and by minimizing black liquor recycling. High
levels of residual alkali will be particularly effective
by minimizing release of MeSH and by promoting conversion
of methyl mercaptide ion to less odorous DMS.
10-63
-------
Harkness, A. C. and Kelman, B. A., SOLUBILITY OF METHYL
MERCAPTAN IN WATER, TAPPI 50 (I), 13, (1967).
The soly. of MeSH in water, detd. by measuring the vol. of
gas absorbed at const, pressure, was 4.90 vols./vol./atm.
at 30°. The differential heat of soln. was - 6.2 kcal./mole
in the temp. range 0-50° . The soly. of MeSH in other solvents
at 30° was also detd. (solvent and sol. of MeSH in vol./vol./atm.
given): 0.05M H SO , 5.06; 1M H SO , 4.29; 0.1M NaSCH , 5.39;
1M Nad, 3.94; 1M Na SO , 2.24. The soly. of H S in water at
30° was 1.86 vols./vol./atm.
Shih, T. T. C., Hrutfiord, B. P., Sarkanen, K. V., and Johanson,
L. N., METHYL MERCAPTAN VAPOR-LIQUID EQUILIBRIUM IN AQUEOUS
SYSTEMS AS A FUNCTION OF TEMPERATURE AND pH, TAPPI 50 (12),
634-8, (December 1967) .
The vapor-liquid equil. of MeSH in buffer solns. was studied
as a function of temp, and pH. Measurements were made at
temps, ranging from 80-185°C. using solns. buffered to pH
7, 8, 10, 12, 13, and 14 at 25° and contg. 0.000182 to 0.0451 M
of MeSH per liter. These measurements also necessitated pre-
liminary kinetic studies of the rate of disproportionation
of MeSH to H2S and Me S in alk. solns. An activation energy
of 22.4 kcal./g.-mole was found for the reaction in IN NaOH
soln. Small corrections to the MeSH concn. were required
at high concn. levels, as a result of this reaction. Vapor
pressure-temp, relationships for 0.01N MeSH soln. were
formulated with the pH level as a parameter. Henry's Law
was found to be valid for any particular pH and temp. Henry's
Law consts., the dissocn. const., and vaporization equilibrium
consts. as a function of temp, were calcd. from exptl. data.
An overall math. expression relating the vapor pressure of MeSH
to its concn. and to H ion concn. is given for dil. aq. solns.
11 refs.
Shih, T. T. C, Hrutfiord, B. F., Sarkanen, K. V., and Johanson,
L. N., HYDROGEN SULFIDE VAPOR-LIQUID EQUILIBRIUM IN AQUEOUS SYSTEMS
AS A FUNCTION OF TEMPERATURE AND pH, TAPPI 50 (12), 630-4,
(December 1967) .
The kraft pulping process continues to increase in importance,
both in regard to no. and capacity of mills. Concurrently,
requirements are becoming more stringent concerning reduced
emanation of odors. Data are presented that are important to
an understanding of situations in which H S is transferred between
liquid and vapor phases. Vapor-liquid equil. relationships of
H S in buffered systems are presented as a function of temp.
10-64
-------
and pH (at 25°C.). Measurements were made by a potentiometric
titration technique at temps. ranging from 80 to 185° and using
solns. buffered to pH 2 to 13 at 25°. Concns, ranged from
0.00097 to 0.0315 M of H S/liter of buffered soln. If the
degree of dissocn. of E^S is taken into consideration, it is
then possible to express the vapor pressure of H S mathematically
in terms of temp,, concn., and pH (at 25°) of the soln,, New
values of the first dissocn. const, up to 185° are presented.
20 refs.
Sakhuja, L., and Basu, S., STUDIES ON THE FIXATION OF SULFIDE
SULFUR IN SULFATE BLACK LIQUOR, Indian J. Technol 6 (5)_, 149-52,
(May, 1968).
The possibility of stabilizing sulfide S (sodium sulfide) in the
black liquor obtained in the prepn. of bamboo pulp, through
its oxidn. into thiosulfate by introducing oxygen or air into
the liquor, thereby preventing loss of S during the soda regener-
ation cycle, was investigated. The influence of different
variables (temp., gas velocity, degree of turbulence and duration
of the oxidn. reaction) as well as the presence of different aromatic
hydroxy cpds. (phenol, phloroglucinol, pyrogallol, and hydroquinone)
on the extent of stabilization achieved was studied. Max. possible
conversion of sulfide to thiosulfate (89%) is achieved at 80-C,
The degree of turbulence has a pronounced effect on the rate of
conversion. An increase in gas velocity up to 60 ml./sec. gives
a continuous increase in the rate of conversion. Hydroquinone
at 0.061% concn. has a pronounced catalytic effect on the
reaction. 16 ref.
Murray, F. E. , and Rayner, H. B., EMISSION OF HYDROGEN SULFIDE
FROM KRAFT RECOVERY FURNACES, Pulp Paper Mag. Can,. 69 (5) ,
71-4, (March 1, 1968).
The evolution of hydrogen sulfide gas from a Combustion Eng.
recovery furnace was monitored for several months, along with
simult. detns. of flue gas oxygen content, rate of black liquor
solids flow, and air flows (primary, secondary, and total) to
the furnace. The amt. of hydrogen sulfide in flue gases from
the economizer section of the boiler varied from zero to
ca. 700 ug./liter. It varied with the rate of solids flow to
the furnace and with the total and secondary air flow rates,
but appeared indep. of the primary air flow rate. 5 ref.
10-65
-------
Douglass, I.E., SOME CHEMICAL ASPECTS OF KRAFT ODOR CONTROL,
J. APCA 18 (8), 541-5, (August 1968).
The principal sources of odor in the kraft pulping process are
the digester, the direct contact evaporator, and the recovery
furnace. Control of odor from the digester requires the
confinement of the noncondensible gases and their destruction
by chlorination, burning, or by some other means. Control
or odor from the direct contact evaporator depends on efficient
black liquor oxidn. The recovery furnace, which can be the
most serious source of air pollution, must be operated properly
within its rate capacity. The chemistry of the various control
measures is discussed.
Douglass, Irwin B., and Price, Lawrence, SOURCES OF ODOR IN THE
KRAFT PROCESS - 11. REACTIONS FORMING HYDROGEN SULFIDE IN THE
RECOVERY FURNACE, TAPPI 51 (10) , 465, (October 1968).
In the recovery furnace concentrated black liquor loses its
remaining water and the residual solids then undergo pyrolysis.
One may assume that the black liquor solids consist of lignin-
and carbohydrate-derived organics and various inorganic sulfur-
containing substances such as sodium sulfate, sodium sulfite,
sodium thiosulfate, sodium sulfide, or elemental sulfur. In
two series of experiments, each of the inorganic substances
listed was heated at 600°C, first with soda lignin and then
with glucose. In the experiments using sodium sulfate and
sodium sulfite, negligible amounts of hydrogen sulfide were
formed. In the experiments with elemental sulfur, sodium
sulfide, and sodium thiosulfate, however, heating with soda
lignin or glucose caused 30-75% of the inorganic sulfur to be
converted to hydrogen sulfide. These results clearly indicate
that in a recovery furnace large volumes of hydrogen sulfide
are formed which, if the furnace is not operated properly,
may escape to the atmosphere and be a major cause of air
pollution.
Douglass, I. B., Kee, M., Weichman, R. L., and Price, L.,
SOURCES OF ODOR IN THE KRAFT PROCESS (III) ODOR FORMATION
IN BLACK LIQUOR MULTIPLE EFFECT EVAPORATORS, TAPPI 52 (9) ,
1738, (September 1969).
Dilute unoxidized kraft black liquor from pulping hardwood
carries into the multiple effect evaporator an appreciable
amount of dissolved methyl mercaptan (0.219 g/gal or 438
g/ton pulp), but very little dimethyl sulfide. This
10-66
-------
mercaptan is evidently stripped from the liquor in the
evaporation process. At the relatively low temperature
to which the dilute liquor is subjected in the first
evaporation stage, there is no detectable dimethyl
sulfide formed and only a small amount of methyl mercaptan.
In successive evaporation stages, at the higher temper-
atures employed, larger amounts of methyl mercaptan are
formed but the total amount appears to be less than that
carried into the evaporator. A partially oxidized (68%)
hardwood black liquor, because it has been subjected
to aeration in the oxidation tower, carries into the
evaporator much less residual methyl mercaptan (0=047
g/gal or 103 g/ton pulp). During the evaporation
process, there is less methyl mercaptan formed in
each effect, primarily because most of the sodium sulfide
originally present has been converted to sodium thio-
sulfate. The amount of dimethyl sulfide formed from
either oxidized or unoxidized black liquor was too
small to measure. A more completely oxidized (99%)
sample of hardwood black liquor showed less mercaptan
formation than when oxidation was less complete.
Another sample of "fully oxidized" heavy black liquor
from a southern mill showed still less mercaptan
formation under comparable conditions. ;
Thomas, J. R., Jones, K. H., and Brink, D. I,., A MECHANISM TO
EXPLAIN THE PRODUCTION OF MALODOROUS PRODUCTS IN KRAFT
RECOVERY FURNACES, TAPPI 52 (10), 1873, (October 1969).
This paper reviews some fundamentals of combustion which
may offer an explanation for the origin of malodorous sulfur
pollutants which originate in kraft recovery furnaces and
which may indicate a method to control these malodors. The
combustion can be characterized by initial endothermic
reactions, which degrade the organic part of the black
liquor into smaller and smaller fragments, and by the
competing exothermic reactions of oxidation and recombin-
ation. The recombination reactions are responsible for the
formation of the malodorous compounds. It is suggested that
by separating the oxidation reactions from the endothermic
and recombination reactions, a furnace effluent could be
produced which would be completely odor free.
10-67
-------
McKean, W. T., Jr., Hrutfiord, B. F., and Sarkanen, K. V./
KINETICS OF METHYL MERCAPTAN AND DIMETHYL SULFIDE FORMATION
IN KRAFT PULPING, TAPPI 51 (12), 564-7, (December 1968).
Earlier reaction rate studies on the formation of MeSH and
DMS in kraft cooks were repeated under carefully controlled
conditions. Rate consts. agreed well with earlier date, but
a higher rate const, was found for DMS formation above 160°C.;
the difference was traced to pH effects. The rate of DMS
formation was shown to be directly proportional to mercaptide
concn., whereas non-ionized MeSH does not react with lignin
MeO groups. As a result, the alkali charge in kraft liquor has
a definite influence on the ratio of MeSH and DMS formed in
the cook. Noncondensibles escaping from the blow gases of
mills which cook to alkali-exhaustion (ca.pH 10.5) are,
therefore, more obnoxious than those from mills maintaining
adequate residual alky. Sufficient active alkali charge
is hence recommended for older installations. 10 ref.
10.7.1 RESEARCH NOT REPORTED IN THE LITERATURE
In addition to the foregoing, NCASI has identified the
following categories of research or specific projects
which presently are under way in the industry. Results
may or may not be reported eventually in the open literature.
It is not possible at this time to define the scope of work
more completely nor to indicate the level of effort.
a. Examination of the relationships between meteorological
conditions, atmospheric visibility, kraft mill particulate
emission control, and ambient behavior and size of
recovery furnace systern particulates.
b. Investigation of the ambient rate of odorous sulfur
compounds through use of airborne instrumentation,
to determine extent of atmospheric natural self-
purification capacity.
10.8 NEW PULPING PROCESSES
All of the chemical pulping processes reported in this study
use sulfur in some form in the cooking liquor. This gives
rise to many of the air quality problems facing the industry.
The most severe problems of air quality occur in kraft pulping
10-68
-------
because of the formation of odorous sulfur compounds. Almost
since the inception of the kraft process, researchers have
been interested in developing a process which is economically
attractive and as versatile as kraft without the odor problems.
The developing of widespread interest in improving air quality
has given added impetus to the search for other processes.
Some old studies are being re-examined and new approaches are
being proposed. A first hand report on the Holopulping
Process under development at the Institue of Paper Chemistry
was not available in the literature„
Sanyer, Necmi, and Laundrie, James F„, FACTORS AFFECTING YIELD
INCREASE AND FIBER QUALITY IN POLYSULFIDE PULPING OF LOBLOLLY
PINE, OTHER SOFTWOODS, AND RED OAK, TAPPI 47 (10), 640,
(October 1964) .
The alkaline pulp yield from loblolly pine reaches a maximum
with the addition of an increasing amount of polysulfide.
With the use of 12% polysulfide sulfur, the yield of kraft
pulp at 50 Kappa number is increased from 50 to 61% and the
respective bleached yield of pulps at 35 Kappa number from
44.5 to 53.5%. The strength properties of polysulfide pulps
are comparable with kraft except tear, which is slightly lower.
Polysulfide decomposes in alkaline cooking liquor before
reaching the digestion temperature by an auto-oxidation-
reduction reaction which has a very high temperature coefficient.
This results in a large loss of polysulfide, as well as active
alkali. Therefore, the active alkali requirement increases
with increasing polysulfide. The use of low digestion temp-
erature, preimpregnation, slow rate of heating to maximum
temperature, and short or thin chips increases the efficiency
of polysulfide. Further improvements in cooking conditions
are expected to reduce the sulfur requirements to more practical
levels. Although the rate of delignification in pulping with
polysulfide is considerably faster than in kraft, the increase
in pulp yield was primarily due to protection of wood carbohydrates,
probably through the oxidation of their reducing and groups
by polysulfide and decreased peeling-off degradation in alkali.
The yield of glucomannan was doubled, accounting for one-half
of the pulp yield increase, and 10% increases in cellulose and
xylan were responsible for the other half. The response of
loblolly pine, white spruce, balsam fir, and Douglas-fir to
polysulfide pulping was more or less similar. With red oak,
the maximum-yield was about one-half that of pine, mainly
because of improved xylan retention.
10-69
-------
Mauch, R. C., OFF-GAS ANALYSIS AND REACTION RATE STUDY IN
NITRIC ACID PULPING, M.~S. Thesis, University of California
Berkeley, 1965 (90 pages).
Gaseous components evolved from HNO -wood and HNO.-wood-O.
reactions were identified and a quant, method for their detn.
was devd. The rate of oxidn. 'reactions of wood substance in
the presence of O was found to be const., whereas the kinetics
of reactions without O appeared to fit a 2nd-order pseudoreaction
mechanism. 15 ref.
Hartler, N., RECENT EXPERIENCES IN POLYSULFIDE COOKING, TAPPI
50 (3), 156-60, (March 11967)1 .
A changeover to polysulfide pulping in a kraft mill requires
the introduction of new or modified techniques. Attention must
be paid to the entire system if a successful result is to be
achieved. Some of the pertinent factors are considered 'in...'
detail. The amt. of odorous org. S cpds. formed in polysulfide
cooking is higher than in conventional kraft~cooking, but this
is not due to the presence of polysulfide as such;.before temps.
high enough for the formation" of org. S cpds'.'. are reached, the
polysulfide is degraded to thiosulfate and sulfide. This
build-up of sulfide is probably the cause of the higher odor
level. 20 ref.
Sanyer, N., PROGRESS AND PROSPECTS OF POLYSULFIDE PULPING, TAPPI
51 (8), 48-51A, (August 1968).f 1 : : " .
Polysulfide pulping reactions are discussed in relation to the
high S requirement of the process,"the delignificatioh rate,
the mechanism of carbohydrate protection, and increased yield.
The major obstacle to com. use of polysulfide pulping is the
lack of an effective recovery system. Present kraft recovery
techniques can be appl. only with major modifications, because
of the high sulfidity of the smelt that would result from burning
of polysulfide spent liquor. It is proposed to develop a novel
recovery furnace having sep.bxidn. and redn. sections with
built-in air pollution abatement features. 29 ref.
10-70
-------
Nolan, W. J., THE PULPING OF SLASH PINE, USING ROSIN PREEXTRACTED
CHIPS IN KRAFT PULPING AND UNEXTRACTED CHIPS IN PULPING WITH
MIXTURES OF SODIUM SULFITE AND CARBONATE, TAPPI 52 (11), 2118,
(November 1969) .
Slash pine chips were extracted with methyl isobutyl ketone,
reducing rosin content to 0.1-0.2% of dry wood. In kraft
pulping, the removal of most of the rosin had no effect
on pulping rate or strength of pulps. Foaming properties
of black liquor were not reduced, nor were the mercaptan
and hydrogen sulfide concentrations in the black liquor.
In neutral sulfite semichemical pulping, preextraction of
rosin had no beneficial effect. The cooking liquor (3:1-
6:1 molal. ratio of SO to C03) saponified wood rosin as
well as in kraft pulping. Semichemical pulps of 52-53%
yield were as high in burst, tensile, and tear strength as
fully cooked, screened kraft pulps and about 10 points higher
in brightness on the GE scale. Energy for fibration in a
100 hp attrition mill equipped with toothed plates, operating
at 20% consistency, was less than 5 hp-days per dry ton.
A total cooking time (60 min. to maximum temperature of
190°C) of 160 min was required to reach 55% yield (o.d. basis)
as compared to 78 min (60 min to maximum temperature of
173'C) for kraft pulping to the same yield. Increasing the
ratio of SO to CO resulted in more selective removal of
lignin and increased the rate of pulping without impairing
saponification of rosin. No objectionable odors could be
detected as the neutral sulfite cooks were blown.
10,8.1 RESEARCH NOT REPORTED IN THE LITERATURE
In addition to the foregoing, NCASI has identified the
following categories of research or specific projects
which presently are under way in the industry. Results
may or may not be reported eventaully in the open literature.
It is not possible at this time to define the scope of work
more completely nor to indicate the level of effort.
Development of new pulping process eliminating use of
sulfur compounds or substituting alkaline sulfite pulping
for the kraft alkaline sulfide pulping process, avoiding
generation of reduced sulfur compounds.
10-71
-------
10.9 CONTROL SYSTEMS DEVELOPMENT
The widespread interest in improving air quality has also
stimulated the development of complete systems for reduction
of emissions„ The odorous sulfur compounds have been the
major target. Many of the systems described in this section
incorporate components previously described. Much work remains
to be done in this area for all pulping processes.
10.9.1 KRAFT SYSTEMS
Ignatenko, A. A., Alferova, L. A., Bondareva, T. N., Volkova,
T. I., and Titova, G. A., DEODORIZATION OF EFFLUENTS FROM THE
MANUFACTURE OF KRAFT PULP, Bumazh. Prom. 39 (5), 16-17,
(May, 1965).
Chem. analyses were made of effluents from continuous kraft
pulping in a Kamyr digester at the Mariisk mill, to det. the
content of foul-smelling components. All samples tested
were colorless, acidic (due to the presence of volatile org.
acids) and had the charac. unpleasant odor. The contents
in mg./liter, of H S ranged from traces to 38.8, of MeSH
from traces to 60, of Me S from traces to 59.6 to MeOH from
10.5 to 1560, and of turpentine from 2.1 to 58.6. There
was no Me,,S , and the content of volatile org. acids was
up to 348 mg./liter. The cl absorption capacity of the
samples (upon 5-30 min. contact) was 460-625 mg./liter.
In studying the possible means of deodorization of the effluents,
it was found that the unpleasant odor disappears fig, chlorination.
The amt. of Cl need is 50-75% of the Cl absorption capacity,
i.e., 0.5 g./t. pulp, on the av. Another efficient deodori-
zation method is rectification at 78-80% C., a process which
removes MeOH, and foul-smelling cpds., and reduces considerably
the C.O.D. of the effluent. A system combining purification
of effluents with that of crude turpentine is described. In
this system, the liquid from the lower part of the distn.
column (after removal of the volatile fraction) goes to con-
densers, and then to a Florentine flask, where it is sepd.
into two layers, an aq. and a turpentine layer. The crude
turpentine is collected, the aq. phase is neutd., sedimented,
and re-used. The volatile fraction contg. the foul smelling
cpds. is condensed and further processed for the recovery of
chemicals.
10-72
-------
Lindberg, S., COMBUSTION OF MALODOROUS GASES FROM ALKALINE
PULP COOKING, in Atmospheric Emissions from Sulfate Pulping
(Eo R. Hendrickson, Ed.), April 1966.
This paper describes an invention to get rid of malodorous
air and water pollutants by combustion of gases from the
cooking in a continuous digester of alkaline pulp, especially
sulfate pulp. The aim of this invention is to destroy both air
and water pollutants in one single operation. The application
to cintinuous cooking is demonstrated with a flow diagram.
Hrutfiord, B. F., and McCarthy, J. L., SEKOR I. - VOLATILE
ORGANIC COMPOUNDS IN KRAFT PULP MILL EFFLUENT STREAMS,
TAPPI 50 (2), 82-5, (February 1967).
As part of a program for devt. of a process to strip ag. effluents
for kraft mill odor redn. (SEKOR), a study has been made of
the volatile org. cpds. that may be steam-distd. from kraft mill
effluent liquors. Some cpds. have been isolated and characd. by
gas chromat. The matls. studied include an oil isolated from
blow gas condensate, an aq. blow gas condensate, and several crude
sulfate turpentines. Cpds. identified include hydrogen sulfide,
methyl mercaptan, dimethyl sulfide, dimethyl disulfide, methanol,
ethanol, acetone, methyl isobutyl ketone, a-pinene, 0-pinene,
A -carene, camphene, limonene, cineole, and a-terpine. A large
no. of addnl. cpds. have been detected. Turpentines from a no.
of sources have been anald. and compared.
Maksimov, V. F., Sokolva, O. I., PURIFICATION FROM GASES OF
MALODOROUS CONDENSATES OF THE EVAPORATION PLANT, Bumazh. Prom.
41 (3), 9-10, (March, 1967).
Purification of the condensate from unoxidized black liquor
evapn. is usually done in the aeration method. Plant tests
showed, however, that a large fraction of gaseous S-cpds,
passes from the liquid into the gaseous phase and is thus
discharged into the atm. At the Segezha mill, which used
white liquor of high sulfidity (32-26%), about 100 cu.m.
WV-satd. gases are formed/t. pulp produced during aeration.
The gases contain, on the av., in g/cu.m. 4.5 H S 0.5 MeSH,
and 0.4 Me S . Recovery of the gaseous S-cpds. was studied
in an exptl. app., consisting of a plate column into which
the air-gas mixt. is fed at the top and, mounted above
the column, a scrubber, in which the gaseous mixt. enters
at the bottom and the scrubbing liquid (white liquor) at the
10-73
-------
top. Two types of scrubbers were tested (viz., a Rashig ring-
packed column and a spray (jet) column). The white liquor
used in the scrubbers contained 16-22 g./liter alkali (as Na20)
and had a temp, of 75°C. Max. purification was achieved in
the Rashig ring scrubber under optimum operating conditions
(a white liquor flow rate of 15 cu.m/aq.m./hr. and a packed
height of 2 m.). The efficiency of H S removal was 96-99%
that of MeSH and Me S 90-95%. The efficiency of the jet
scrubber was detd. mainly by the gas flow rate at the throat
of the app. and the degree of dispersion of the white liquor,
but even under the most favorable conditions (gas flow rate
18.22 m./sec.) , the max. purification was 95%. Moreover,
the alkali concn. in the white liquor was reduced to 2-8 g./
liter, as compared with a redn. to 12-14 g./liter in the case
of the packed column scrubber. To completely prevent the
evolution of gaseous S cpds. from white liquor fig. absorption
(the liquor is recycled to the causticization room) its alkali
concn. should be maintained at 25-40 g./liter.
Matteson, N. J., Johanson, L. N., and McCarthy, J. L., SEKOR
II-STEAM STRIPPING OF VOLATILE ORGANIC SUBSTANCES PROM KRAFT
PULP MILL EFFLUENT STREAMS, TAPPI 50 (2), 86-91, (February
1967) .
A pilot-plant study has been carried out of the "SEKOR" process
which comprises mainly the fig. operations: the continuous steam
stripping with reflux of kraft pulp mill effluents to remove
volatile org. cpds. and the collection of the resultant bottoms
and overhead streams to avoid discharging effluent volatile
org. cpds. into the air; the recovery of an overhead stream
of water-immiscible oils; the substantial removal of volatile
org. cpds. from the condensate effluents, which reduces the
hazard of water pollution should the effluent be discharged
into water courses; and the recovery of a bottoms streams of
condensate water now purified to such a degree that often it
may be reused in kraft pulp mill process operation. Expts.
demonstrated that hydrogen sulfide, methyl mercaptan, dimethyl
sulfide, and dimethyl disulfide were removed to a degree
exceeding 95%. Operations were conducted satisfactorily using
steam stripping without reflux (SEKOR-a) or with reflux (SEKOR-b).
When the- SEKOR-b process was used under appropriate conditions
nearly all of the volatile org. cpds were collected in the
water-immiscible overhead stream. 9 ref.
10-74
-------
Maahs, H. S., Johnson, L. N., and McCarthy, J. L., SEKOR III.
PRELIMINARY ENGINEERING DESIGN AND COST ESTIMATES FOR STEAM
STRIPPING KRAFT PULP MILL EFFLUENTS, TAPPI 50 (6), 270-5,
(June 1967).
A prelim, illus. eng. design and cost est. was conducted on the
SEKOR B (refluxed column) process. As basis for these calcns.,
exptl. detns. were made of vapor-liquid equil. consts. for MeSH,
Me2S, and Me2S2 ^n 3d.3.- aq. solns. at 1 atm. total pressure, as
well as for limonene, a-pinene, as a-terpineol-major constituents
of the recovered volatile oil. All these cpds. were more volatile
than water and could be steam-stripped; a-Terpineol and Me S were
the most difficult to strip. The optimum feed/steam ratio reflux
rate, and no. of stages required to strip H S plus the above
cpds. from condensates of a 400t./day kraft mill were calcd.
To reduce the Me S concn. to 1% of its feed concn. capital
costs were estd. at $51,500 to treat 1,000,000 Ib./day of blow
and relief gas condensates. If amortized over 5 yr., the capital
plus operating costs would result in a total cost of 25 cents/t.
of o.d. pulp for the first 5 yr., and 13 cents/t. thereafter.
If recovered crude SEKOR oils could be sold at 4 cents/lb. and
hot process water is valued at 3 cents/1000 gal., the costs for
trg. blow and relief gas condensates are estd. at 7 cents/t.
The bases for these calcns. and designs are described, permitting
similar calcns. to be made for different local mill conditions.
9 ref.
Adams, D. F., and Koope, R. K., GAS-PHASE CHLORINATION OF KRAFT
PULP MILL GASES, TAPPI 51 (5), 173-5, (May 1968).
Gas-phase chlorination of gases from kraft pulp mills appears
to be of limited value as a means of odor reduction. In
laboratory experiments, gas samples from the recovery furnace,
batch digester, multiple-effect evaporator, and lime kiln of a
mill were charged with known volumes of chlorine gas and the
reactions were recorded by gas chromatography. The chlorine
oxidized the methyl mercaptan in the gases to dimethyl disulfide
but did not change the concentrations of hydrogen sulfide or
dimethyl sulfide in the samples. Complete elimination of the
methyl mercaptan apparently is possible if adequate chlorine
doses are added. However, the odor reduction effected in the
total gaseous effluent would probably not be sufficient to
justify use of this process on a plant scale.
10-75
-------
Vedernikov, V. G., and Kaksimov, V. F., SOME PROBLEMS OF
DEODORIZATION OF GASEOUS WASTES IN THE KRAFT PULP INDUSTRY,
Tr. Leningrad. Tekhnol. Inst. Tsellyuloz. Bum. Prom.
(13), 148-54, (1964).
In the digester room, the gaseous prods, can be effectively
deodorized by absorption in the so-called "doctor's soln."
obtained by dissolving 6 kg. PbO and 12.5 kg. caustic soda
in a 100-fold amt. of water (Na plumbite is formed in such
soln.) or in a soln. of polysulfides. Me2S2 and Me2S
accumulate in the doctor's soln., and can be easily sepd.
In the evapn. plant, deodorization can be achieved by sepg.
H S and MeSH formed by means of a system of heat exchangers
and then by absorption in the doctor's soln. or a soln. of
polysulfides. In the soda recovery plant, S-contg. gases
can be trapped in a desorption scrubber equipped with an
electrofilter. The suggested deodorization system with full
recovery of S makes the installation of equipment for oxidn.
of black liquor of doubtful value. The deodorization system
is connected with Me S is utilized, without further processing,
as a solvent and/or as a starting matl. in org. synt.
Buxton, Winslow H., and LaPointe, Markley W., CHEMICAL
RECOVERY AND ODOR ABATEMENT ON A KRAFT RECOVERY FURNACE,
TAPPI 48 (5), 112-13A, (May 1965).
Air pollution at Western Kraft Corp. in Albany, Oregon, has
substantially reduced by establishing uniform recovery furnace
control and utilizing secondary stack gas chem. recovery. Using
wet gas scrubbers in conjuction with an alk. shower wash, Na ion
collection efficiencies as high as 50% have been reported. H-S
recovery of 90% was obtained during extensive testing. Gen.
chem. fallout on mill prop has been reduced 94%.
Jensen, G. A., Adams, D. F., and Stern, H., ABSORPTION OF
HYDROGEN SULFIDE AND METHYL MERCAPTAN FROM DILUTE GAS MIXTURES,
J. APCA 16 (5), 248-53, (May 1966).
The absorption of hydrogen sulfide (I) and methyl mercaptan (II)
by aq. solns. of Cl, NaOH, and Cl + NaOH was studied using a
2-inch diam, absorption column packed with 1/4 inch Intalox
saddles. Absorption rates were noticeably affected by chem.
10-76
-------
reactions occuring in the aq. Cl and hydroxide media. These
solns. were studied as a means of controlling S-contg. gas
emission at a pH above 12 were effective absorbents for
(I) removal in absorption equipment designed to handle S in
suspension. The absorption of (II) in aq. Cl solns. appeared
to be impractical since dimethyl disulfide was apparently
the only prod, formed and was stripped from the tower by the
gas stream. NaOH soln. was an effective absorbent for both
(II) and (I) when hydroxide to (I) or (II) feed ratios were
greater than 1 or 1.8 resp. The (II) absorption coeff. was
approx. twice that for sulfide absorption.
Jafs. D., RECOVERY OF HEAT AND CHEMICALS FROM FLUE GASES USING
THE WARKAUS VENTURI SYSTEM, Paperi puu 48 (6) , 337-9, 341-2,
(June 1966)
The constructional design and operating theory of the Warkaus
Venturi scrubber devd. by T. F. Holmberg (previously known
as the Imatra Venturi) are outlined. The use of this device
for recovering heat and chemicals is exemplified by actual case
histories in which efficiencies of 90-99% (and even as high
as 99.9% for a 3-stage system) were emphasized, since it is
well suited for scrubbing org. S cpds. from flue gases. 19 ref.
Russ, L., SCRUBBER RECOVERS SULFUR LOSSES, Pulp Paper 40 (27),
22-3, (July 4, 1966).
Fig. a brief rev. of work in the area of odor abatement systems
for the kraft pulp mill, the design and performance characs.
of the Venemark scrubber, which uses a white or weak liquor
and/or caustic soln. scrubbing liquor to absorb noncondensible
evaporator gases/ are outlined. 7 ref.
Kiyoura, R., STUDIES ON THE REMOVAL OF SULFUR DIOXIDE FROM
HOT FLUE GASES TO PREVENT AIR POLLUTION, J. APCA 16 (9) ,
488-9, (September 1966) .
A study was made of a process, applicable in ind., for removing
SO from hot flue gases. The process, referred to as the Kiyoura
T.l.T. [Tokyo Inst. of Techno.] process converts SO2 in the flue
gas to SO in the presence of vanadian oxide at a temp, of
380-450°C. A limited amt. of WV present in the flue gas reacts
with SO, to form H_SO.. Ammonia is then introduced into the
gaseous mixt., which is now at a suitable temp. (220-260°C.)
to form (NH.) SO . The (NH.)-SO. aggregates produced can be
removed by a dry cyclone separator. The process was tested in
lab. and semi-pilot plants. A pilot plant is currently under
construction. Estd. operating costs of the process are given.
2 ref.
10-77
-------
van der Feyst, J., PULP PRODUCER HELPS DESIGN RECOVERY SYSTEM,
Can. Pulp Paper Ind. 21 (4), 60, (April 1968).
The devt. of a gas scrubber with a heat recovery sect, by 2
Swedish companies (Mo och Domsjo AB, and the SF group) is
briefly described. The heat recovery sect, uses a ser,, of
3 nozzle bank and water collector units to heat water by
spraying it into the scrubbed flue gases and recollecting it.
Murray, F. E., Oloman, C., and Risk, J. B., SELECTIVE ABSORPTION
OF HYDROGEN SULFIDE FROM STACK GAS, Paper Trade J. 153 (7), 92,
94, (February 17, 1969).
A process for the selective absorption of hydrogen sulfide from
gas streams containing high proportions of carbon dioxide is
discussed. The process involves the absorption of H S into
a strong solution of sodium carbonate and bicarbonate and is
being designed specifically for application to the flue gas
from pulp mill recovery boilers.
Russ, Lennart, INVESTIGATION OF ODOR ELIMINATION AT AB MORRUMS
BRUK, MORRUM, Sevensk Papperstid 66 (15), 554-7, (August 15,
1963).
A system for the redn. of odorous cpds. formed during alk. pulping,
devd. by the British Columbia Research Council, consists of an
oxidn. tower through which black liquor is pumped in the same
direction as a gas mixt. contg. air, uncondensed gases from the
turpentine recovery, and gases from the digester blow. After
leaving the oxidn. tower the mixt. is washed with Cl and dil.
NaOH in a scrubber before being vented into the atm. The
efficiency of the system has been investigated at AB Morrums
Bruk, Morrum, Sweden. The atms. of MeSH, Me_S, and Me_S in
the gas mixt. before- and after the oxidn. tower and the scrubber
were detd. by gas chromat. If operated under proper conditions,
the system removes more than 99% of the methyl sulfides and
more than 97% of the mercaptan. The greater part of these
cpds. was taken up by the black liquor in the oxidn. tower, and
the rest was oxidized in the scrubber. The concns, of the
odorous cpds. in the outlet from the scrubber were very low and
the smell was characd. as "faint." The gas mixt. leaving the
scrubber is probably immediately dild. by fresh air so that the
concns. of the odorous cpds. decrease below the noticeable level.
The efficiency of the oxidn. tower decreased below a certain
limit. About 90% of the Na_S in the black liquor was oxidized in
the oxidn. tower. 1 ref*
10-78
-------
Murray, F. E., HOW KRAFT PULP ODOR IS ABATED, Pulp Paper Intern
6 (2), 52-3, (February 1964).
A brief rev. is given of the use of the British Columbia Research
Council system in controlling odor from the kraft pulp mill of AB
Morrums Bruk, Morrum, Sweden.
Collins, T. T., Jr., NEW SYSTEMS PROPOSED FOR KRAFT MILL ODOR
CONTROL AND HEAT RECOVERY, Paper Trade J. 149 (22), 34-5, (May
1965) .
Using stack gas heat recovery app = as a. parr of an odor control
system, this recent invention makes profitable a combination
process for redn. of kraft pulp rail! odors. Three flow diagrams
show the modification of basic concepts, incl. collection and
disposal systems for high and low temp, gases and condensates?
central heat recovery and odor control system, and modified
central heat recovery and odor control system. These are
also applicable to recovery of spent neut= sulfite and medium
base acid sulfite liquors alone or in conjunction with kraft
mills.
Nowicki, R., and Zajac-Wierzchowska, E., STUDIES ON THE CONTROL
OF ODOR IN KRAFT MILLS, Przeglad Papier 21 (6), 195-8, (June 1965).
Results are presented and discussed of the study on the possibility
of redg. the amt. of foul-smelling S cpds., formed during kraft
cooks, and the means to deodorize these cpds. The expts. were
carried out on a pilot plant scale, under conditions resembling
as much as possible the ind. process used at the mill in Jeleniz
Gora (this included pulping variables, the digester relief process,
the digester blow-off, collection of the condensate, etCo) = Under
the conditions prevailing at the mill, the av, amt = of foul-
smelling S cpds. formed (hydrogen sulfide, MeSH, methyl sulfide),
expressed as S, is 2430 g./t. pulp. Of this amt., 87% are
noncondensing S cpds., which are a direct cause of the air
pollution, and a major fraction of these are evolved during
digester blow-off. The amt. of S cpds. can be substantially
reduced by increasing the alkali content of the cooking liquor,
while an increase in the liquor sulfidity has the opposite effect.
Thus, expressed in g. S per t. wood an increase of alkali concn.
(as NaOH) from 20 to 26%, at a sulfidity of 17% caused a redn»
10-79
-------
from 390 to 124, and an increase of sulfidity (at alkali concn.
of 20%) to 25%, caused an increase to 580. Expts. on the
deodorization of S cpds. with Cl (using spent liquor from the
chlorination tower) indicated that at stoichiometric ratios,
50% of S cpds. are oxidized. For full deodorization an excess
of Cl, equal to three times the stoichiometric amt., is needed.
Since the spent chlorination liquor available at the mill contains
less than that amt., the problem could possibly be solved by
a combination of the fig. means: redn. of the mat. of S cpds.
formed by modifying the pulping parameters, lowering of the
temp, of gas condensation and the introduction of an addnl.
amt. of Cl for deodorization. 30 ref.
Carlson, D. A., and Gumerman, R. C., HYDROGEN SULFIDE AND METHYL
MERCAPTAN REMOVALS WITH SOIL COLUMNS, (Proc. 21st Ind. Waste Conf.)
Eng. Bull. Purdue Univ. 50 (2), 172-9, (May 1966).
The use of soil bacteria to remove gaseous odors from kraft
pulp mills, sewage facilities, sewage trmt. plants, and other
inds. appears to have excellent possibilities„ Microbial
populations are responsible for the odor removal; water absorption,
efficiencies approaching 100% were attained for a concn. of 15
mg/liter of hydrogen sulfide and for 775 ing/liter of degrade
hydrogen sulfide and methyl mercaptan in quantities of 1.86
and 2.68 liters/week/cu.ft. of soil, resp. clay, sand, and
sandy loam solid low in volatile matter were inferior in degrada-
tive ability to the artifically enriched fertile loam soil.
Total bacteria counts during the test period showed an initial
decrease but then increased substantially once acclimation
occured. Fifteen bacteria cultures were isolated from soil
degrading methyl mercaptan. These included 8 Pseudonomongs,
2 Bacillus, 2 Nocardia, and 1 each of Flavobacterium, micro-
coccus, Phizobium. Soils oxidg. hydrogen sulfide often
contained Bacillus, Streptomyces, Thiobacillus. Specific
responsibility of these bacteria for the resp. boil, degra-
dations has not as yet been established. Optimum soil depth
was not established, although a depth of 3.5 ft. appears
to be effective. As previously noted, soil filters have
been successfully appl. in the elimination of malodorous gases
emanating from anaerobic sewage in residential area lift
stations and/or hog and poultry farms. Larger installations,
such as kraft pulp mills, could apply the soil filter principle
in conjunction with a spray irrigation for the removal of
excess BOD. 8 ref.
10-80
-------
Benjamin, M., AN EXAMPLE OF PLANNING FOR POLLUTION CONTROL
IN KRAFT PULPING, J APCA 16 (3), 128-30, (March 1966).
This paper deals mainly with the planning and action taken
ac the Owens-Illinois Kraft Pulp and Paper Mill in Jacksonville,
Florida, in an effort to reduce air pollution. Steps taken
at the mill over the last several yr. are outlined. These
include education and training of personnel, changes in the
mfg. process or equipment, installation of new equipment
for redg. pollution, attention to maintenance and control,
utilization of research and devt. from all sources, and
relations with the public and regulatory agencies. 5 ref.
Thomas, E., Brcaddus, B,, and Ramsdell, E. W., AIR POLLUTION
ABATEMENT AT S. D, WARREN'S KRAFT MILL IN WESTBROOK, Me.,
TAPPI 50 (8], 61-3A, (August 1967).
Sources of gas emission in a kraft mill were studied, and
corrective equipment was installed. A system was devd. in
which digester blow gases are passed through primary and
secondary deodorizing scrubbers, utilizing the chlorination
stage effluent. As backup, weak hypo bleach can be added to
the secondary unit, Noncondensible digester relief gases
are burned in the lime kiln. Oxidn, control instrs. have
been installed on the two recovery boilers to insure complete
combustion. One recovery boiler stack has a Cottrell
precipitator, another has a Venturi scrubber. Both recovery
boilers have scrubbers on their smelt tank vents. Black
liquor is presently oxidized in a Trobeck-Lundberg-Tomlinson
oxidn, tower before passing to the evaporators. Chem. test
are performed daily to det. the efficiency of black liquor
oxidn. Periodic surveys are conducted on all suspended
sources of air pollution to det. the effectiveness of this
abatement program.
Lindgerg, S., HOW UDDEHOLM IAB.J DESTROYS AIR AND WATER
POLLUTANTS AT THE SKOGHALL WORKS [SWEDEN], Pulp Paper Mag.
Can. 69 (7), 125-30, (April 5, 1968).
The Skoghall Works, center of the Uddeholm Co.'s forest
ind. operations, include sawmill, kraft and sulfite pulp
mills, paper mill, and chenu plants. They are located
on Lake Vanern (the largest Europ. lake outside Russia)
in a well populated recreational area* Malodorous gases
are destroyed by combustion, and gas mixts. excl, O
are burnt in the recovery boiler. Those gases that
are mixed with air on collection are eliminated in a
specially designed furnace, installed as a preiiirui oven
to a conventional boiler. The worst water pollutants
are cooking and evapn, condensates, Before being
10-81
-------
discharged into the lake, the digester condensate is freed
from odiferous components by blowing with steam through
a column. The evapn. condensate contg. mostly hydrogen
sulfide is scrubbed by mixing with backwater from the
chlorination stage of the bleach plant. The total sulfide
content in the waste water has been reduced from 6 to 1 Ib.
of hydrogen sulfide per t. of pulp. Capital outlay has
been moderate (ca. $100,000) , and process operating costs
are low (less than $0.02/t. of pulp), comprising largely
the steam consumed in the stripping column (1.2 t./hr.
equiv. to 12 cents/t. of pulp) and 3 cents/t. for the
oil flame in the special furnace.
Van Donkelaar, A., AIR QUALITY CONTROL IN A BLEACHED KRAFT
MILL, Pulp Paper Mag. Can 69 (18), 69-73, (September 20,
1968).
Equipment, process eng., and monitoring practices at the Samoa
bleached kraft mill of Georgia-Pacific Corp. in northern
Calif, are described. Emphasis is placed on measurement and
attempted control of malodors (H sulfide, MeSH, and org.
sulfides). It is shown that through nearly 100% black liquor
oxidn, stack emissions of H sulfide can be reduced nearly to
zero, while mercaptans and org. sulfides can be eliminated
efficiently through incineration and/or chlorination of non-
condensibles from the cooking and evapn, stages. Use of
telephone lines and home monitoring systems has proved
valuable. Close cooperation with regulatory agencies has
brought better understanding of problems and realistic guide-
lines for future pollution-control effort. 10 ref.
Galeano. S. F, and Harding, SULFUR DIOXIDE REMOVAL AND RECOVERY
FROM PULP MILL POWER PLANTS, J,AFCA 17 (8), 536-9, (August 1967).
The redn. of SO7 emissions has become a prime goal of air
quality improvements programs. Special circumstances unique
to pulp mills, ice,, on-site power plants and a demand for S
cpdSo in the cooking liquor, suggest that wet scrubbing for
SO removal from boiler flue gas might be economically feasible.
The use of Na^CO soln, to scrub 5O_ from power plant flue
gases was studied in a pilot plant consisting of a Venturi
scrubber and a cyclone. The rel. effects of the major operating
variables (temp,, Na_CO3 concn., and the gas/liquid flow ratio)
on the absorption phenomenon were detd» the economics of a full-
scale unit operating at a NSSC pulp mill prodg, 150 t. of pulp
daily are discussed„ 17 ref„
10-82
-------
Harding, C. I., and Galeano, S. F., USING WEAK BLACK LIQUOR FOR
SULFUR DIOXIDE REMOVAL AND RECOVERY, TAPPI 51 (10), 48-5lA,
(October 1968).
Pulp mill air pollution problems are of 3 types! odors, par-
ticulate emissions, and SO emissions from power boilers.
Black liquor oxidn. is the single most effective step for
odor rend. Work has been completed on a pilot scale on
the devt. of a black liquor oxidn. system, with subsequent
use of the liquor for SO scrubbing of power plant flue
gases. Results of this study, conducted at the Univ. of
Fla., indicate that weak black liquor from southern kraft
mills can be oxidized effectively by using kerosene for foam
control. A Venturi scrubber with moderate head loss (ca.
14 in. water column) gave consistent SO removals above 92%.
Work of earlier investigators was confirmed, showing that
ca. 80% sulfide oxidn. gave the most effective SO absorption
without measureable release of H S„ Saltcake makeup is
virtually eliminated. Complete oxidn. of sulfide enchanced
the formation of sulfates which inhibited SO removal during
scrubbing. The liquor can be recirculated for multiple
passage through the scrubber if the pH is kept high enough
to prevent lignin pptn. the intergrated oxidn. scrubbing
system can achieve net savings of ca. 30 cents/t. of A. D.
pulp, excl, the benefits of reduced SO emissions. 9 ref.
10.9.2 SULFITE SYSTEMS
Laberge, J. C., SULFITE MAGNESIUM OXIDE SYSTEM—SULFUR DIOXIDE
ABSORPTION EFFICIENCY IMPROVEMENT, TAPPI 46 (9), 538-41,
(September 1963) .
In 1948, the Weyerhaeuser Co, converted its Longview, Wash.,
sulfite plant from the Ca to the Mg-base system and became the
first com. producer of Mg-base pulp. By applg. the information
acquired during this study, the atm. SO losses in the exhaust
gases from that plant were reduced by a factor of 20 without
addnl. capital investment. The SO2 absorption system consists
of a pair of absorption trains preceded by cooling towers. Each
absorption train is designed to absorb the SO from the flue
gas of a spent liquor recovery boiler. The towers are hand-
packed with 6X6 inc. cross partition rings. In addition
to flue gases, certain other gas streams enter the absorption
system. By reapportionment of these streams, an evanl. of their
effects upon overall absorption efficiency was made. From
this knowledge, the controlling source of excessive SO2 loss
was traced to a makeup SO gas stream. The acid recirculation
system was then modified to absorb the SO from that makeup
stream more efficiently, 2 ref.
10-83
-------
Lea, tt, 3, and Cnrisroferson, E. A , HOW SCOTT [Paper Co., Everett,
Wash,] RECOVERS SULFITE BLCWP1I GASES, Pulp Paper 39 (42), 48-9,
(GctuDer 18, 1965),
The hoc gas flash condenser, sulfur dioxide (I) absorption tower,
arid assocd, piping, pumping, and heat exchange equipment employed
at th= mill in the recovery of (I'i from the gases from the 12
sulfice digester blcwpits are briefly described along with
the use of the recovered (I'j in cooking liquor prepn= In
addn,, data are presentsd on the economics of the recovery
system.
Vclgin, B, p.-, Ef imove, T „ P., and Gofman, M. S,, ABSORPTION OF
SULFUR DIOXIDE BY AMMONIUM SULFITE/BISULFITE SOLUTION IN A
VENTURI SCRUBBERf Khiitic Prom 4^ (2, , 132-6, (February 1967).
The absorption of SO, by NH ouiiite/bisuifite solns, was
studied in a model app., the Venturi tube being made of
transparent plastic for better visual control of the soln*
atomizationn The exptl, results are presented in a series
of graphs expressing the fig. relations: The degree of
absorption at various amts, of tne spray liquid, as a function
of SO, concn. in the gas; the degree of absorption at various
gas i_ow velocities as a function of the mat, of absorbent;
the resistance (to flow, of the scrubber as a function of
hydraulic parameters; the degree or absorption as a function
of the resistance of the scrubber; the degree of absorption
as a function of power consumption at various gas flow
velocities and various arnts = of the absorbent; the degree of
absorption as a function of the Venturi throat length at
various amts= of the absorbent and flow velocities; the
resistance of the scrubber as a function of the total power
consumption in a multistage scrubber; and the mass transfer coeff.
as a function of the hydraulic parameters of the scrubber.
Equations are given, expressing the expti, relations, The
data presented are to be regarded as preliminary, as the study
is to £>e continued in equipment of larger capacity 0
Nacu, A,, and C^nstantinescu, O-, PROCESS FOR REDUCING THE
POLLUTING EFFECT OF SPENT NSSC LiQUORS, Celuloza Hirtie 16
(II) , 418-28, 'November ^.967 .
Chem, recovery processes for spent Na-base neut.- suifite liquors
are revcL and their principles ilius, by flow charts, incl,, the
Zimmerman^ 'Sterling Diug' Mead, Sivoia iCoiaDustion Eng.)
Gauvin (PRRIC'; , Bradley '.Western Pptn,; , Copeland {Carthage) , and
I.P.C. PiQ'j^sses, ^" ret.
10-34
-------
CHAPTER 11
RESEARCH AND DEVELOPMENT RECOMMENDATIONS
TABLE OP CONTENTS
Page No.
Summary 11- 1
Areas of Needed Research 11- 2
Specific R S D Projects 11- 6
Emission Control Technology 11- 6
Cost and Effectiveness of Emission Control 11- 8
Sampling and Analytical Techniques 11- 9
Control Equipment Development 11-10
Process Changes 11-10
Chemistry of Pollutant Formation or Interaction 11-11
New Pulping Processes 11-12
Control System Development 11-12
Other 11-12
-------
CHAPTER 11
RESEARCH AND DEVELOPMENT RECOMMENDATIONS
SUMMARY
The investigations undertaken during the course of this
study have led to the conclusion that existing technology, plus
present technology in the experimental stage, still may result
in emission levels which can be unacceptable to the public in
some instances. Many gaps exist in our present knowledge which
need to be filled by future research.
It is felt that several major gaps in technology have
been identified which will need to be filled before any further
great steps in progress can be taken. Brief statements of these
needed areas of research of highest priority are as follows:
1. Develop and standardize methods and instruments
for monitoring emissions and ambient air.
2. Assess the effect of operating variables on
emissions from the kraft pulping and recovery
systems.
3. Develop and standardize organoleptic techniques
for determinations of process emissions and
evaluation of ambient air quality.
4. Investigate new pulping methods which eliminate
the use of sulfur.
5. Define the mechanisms, with emphasis on transport
processes and emission interactions, which will
relate emission limitations to ambient air objectives.
6. Evaluate emissions from sources in sulfite and NSSC
mills and determine operating variables which affect
emissions.
7. Investigate adsorption and absorption of odorous
gases and reuse of the collected material in process.
8. Determine whether TRS is an effective measure of
the acceptability of odorous emissions from kraft
mills or must the compounds be identified more
definitively.
11-1
-------
These brief statements of needs are defined more completely
and specific projects identified.
Although not a recommendation for specific research necessary
to a technology breakthrough, it is felt that the industry and
government regulatory agencies would benefit from more definitive
information on costs. It is suggested that an effort be made
to develop and encourage the use of a system for recording
maintenance and operating costs.
Any listing of research needs and priorities must be under
continuous review by the industry and NAPCA.
11.1 AREAS OF NEEDED RESEARCH
Previous chapters of this report have evaluated existing control
technology, relatively untried or nearly developed control
technology, and research underway related to emissions control.
These evaluations have led to the conclusion that existing tech-
nology plus present technology in the experimental stage, still
may result in emission levels which can be unacceptable to the
public in some instances. In bringing presently major sources
under control many gaps appear in our knowledge. As these
sources are brought under control, presently minor sources assume
greater importance. The problem of identifying the most
important research needs is complicated by the fact that some
mills are located in remote areas and some in cities. Some
mills are old and some represent fairly new installations. Many
gaps exist in our present knowledge of evaluation, effects, process
variables, and application of control techniques. Major research
needs have been developed taking into consideration that the
kraft odor problem is the most troublesome, there are more kraft
mills than other types, and little is known of the emissions
from sulfite and NSSC. Of course, any listing of research
needs and priorities must be under continuous review by the
industry and NAPCA.
It is felt that several major gaps in technology have been identi-
fied which will need to be filled before any further great steps
forward can be taken. These needed areas of research of highest
priority are as follows:
11.1.1 DEVELOPMENT AND STANDARDIZATION OF METHODS AND INSTRUMENTS
FOR MONITORING EMISSIONS AND AMBIENT AIR
This probably is the foremost needed research effort. Reliable
evaluation methods are necessary to provide more definitive
information on receptor effects, establish emission standards,
determine compliance with emission standards, establish ambient
11-2
-------
air standards, determine progress toward air quality objectives,
establish applicability of control measures, determine efficacy
of ameliorating measures, and for many other purposes.
Although much progress has been made in this direction in recent
years, few methods have been standardized and there are no
reliable methods available for some compounds of interest.
Specific projects are listed in Section 11.2.3.
In general, the need is to develop and/or standardize methods
for both ambient and source sampling which achieve a state
of greater reliability and simplicity for continuous application
in the field. It is imperative, also, to promulgate a set of
sampling specifications for uniform application thoughout the
industry.
11.1.2 ASSESSMENT OF THE EFFECTS OF OPERATING VARIABLES ON EMISSIONS
FROM THE KRAFT PULPING AND RECOVERY SYSTEMS
For many sources, in the immediate future, it is felt that control
of operating variables holds the greatest promise of meeting
emission limitations. It must be recognized, however, that not
all of the variables will be mutually independent.
Some work has been done on units such as the recovery furnace.
This work is encouraging, and serves to emphasize the need for
more difinitive and extensive work on the recovery furnace as
well as other unit processes.
Most applicable odor regulations probably can be met with adequate
black liquor oxidation. Definitive information is lacking, how-
ever, on the various factors influencing both weak and concentrated
BLO. The reversion phenomenon particularly needs explanation.
Since some new systems eliminate the : DC evaporator and thus do
not require BLO to reduce H S emissions from that source, it
is important to evaluate any H?S contribution in wet-bottom
precipitators using unoxidized black liquor.
Included in this area of investigation might be an evaluation
of possible alternatives to the present system of furnace
recovery.
Specific projects are listed in Section 11.2.1, 11.2.5, and 11.2.6-
11-3
-------
11.1.3 DEVELOPMENT AND STANDARDIZATION OF ORGANOLEPTIC TECHNIQUES
FOR DETERMINATIONS OF PROCESS EMISSIONS AND EVALUATION OF
AMBIENT AIR QUALITY
In the final analysis, the human nose will be the judge of
the success of odor abatement activities. The sense of smell,
however, is notoriously variable due to physiological as "well
as external physical factors. Except in the case of trained
observers, odor panels leave much to be desired.
Some work has been done on application of organoleptic
techniques in Sweden but only a limited amount of work has
been done in the U. S. There is little agreement on odor
threshold levels, but concentrations of odorants frequently
are perceptible at levels far below the detection limit by
chemical methods. A better understanding is needed of the
influence of physical, physiological, and psychological
factors on odor perception.
Specific projects are listed in Section 11.2.6 and 11.2.9.
11.1.4 INVESTIGATION OF NEW PULPING METHODS, ESPECIALLY THOSE
WHICH ELIMINATE THE USE OF SULFUR
The most positive way of eliminating problems associated
with the emission of sulfur compounds is to eliminate the
use of sulfur in the process of wood pulping. It must be
recognized that eradication of these problems may result
in the creation of others. The long-range objective of
this research and development is to provide a permanent
solution.
Since the advantages and versatility of the sulfate process
over the soda process were recognized beginning in the late
19th century, researchers have been attempting to eliminate
the odor. In addition to add-on equipment and process
modifications, new pulping bases (acid, neutral, and alkaline)
have been investigated. Other delignification techniques
also have been tried. Several of the processes appear
promising.
Other approaches such as wood chip modification prior to
cooking may make possible the use of modifications of present
cooking bases under conditions which will not form objection-
able compounds.
Specific projects are listed in Sections 11.2.7 and 11.2.8.
11-4
-------
11.1.5 DEFINITION OF THE MECHANISMS, WITH EMPHASIS ON TRANSPORT
PROCESSES AND EMISSION INTERACTIONS, WHICH WILL RELATE
EMISSION LIMITATIONS TO AMBIENT AIR OBJECTIVES
It is necessary to develop the background information and
procedures by which it will be possible to formulate meaning-
ful emission standards for chemical wood pulping installations.
Mills of the pulp industry are widely distributed throughout
the U. S. in areas of varying climatic conditions. Conversions
and combinations are known or believed to occur after gaseous
compounds leave the source. Adsorption of odorants on par-
ticulates has been postulated to explaint the extreme transport
distances reported for some mill emissions. Dilution in the
atmosphere undoubtedly will play an important but quantitatively
undetermined role in providing ambient air quality which will
be acceptable under all conditions.
This is a unique modelling situation involving various com-
binations of gases and particulates. Present dispersion
modelling techniques can provide only a bare foundations for
the needed effort.
Some of the projects which will provide needed background will
be found in Sections 11.2.1, 11.2.3, 11.2.6, and 11.2.9.
11.1.6 EVALUATION OF EMISSIONS FROM SOURCES IN SULFITE AND NSSC MILLS
j^ND DETERMINATION OF THE OPERA'TING VARIABLES WHICH AFFECT
EMISSIONS
The intensive work done on this project has demonstrated the
paucity of information on these sources. Before definitive
progress can be made in determining what reductions are
required and the most appropriate ways to bring about the
reductions, reliable information on emissions is essential.
Some of the work described in Section 11,2.3 must be completed
and existing methods verified before progress can be made.
11.1.7 INVESTIGATION OF ADSORPTION AND ABSORPTION OF ODOROUS GASES
AND REUSE OF THE COLLECTED MATERIAL IN PROCESS
For some sources, control of operating variables or modification
of unit process may not reduce emissions of °dorants to an
acceptable level. Until processes are available which avoid
the formation of odorants, destruction or add-on devices may
be the only answer. To improve the economics and avoid creation
of other problems, reuse may be necessary.
11-5
-------
Specific projects which will contribute to this objective
will be found in Section 11.2.1, 11.2.4, and 11.2.5.
11.1.8 DETERMINATION OF WHETHER TRS IS AN EFFECTIVE MEASURE OF THE
ACCEPTABILITY OF ODOROUS EMISSIONS FROM KRAFT MILLS OR MUST
THE COMPOUNDS BE IDENTIFIED MORE DEFINITIVELY
Little is known about the human perception of mixtures of
odorants. The odorants may continue to react in the atmosphere
so that the perceived odor is not always the same as the one
emitted. The odor threshold concentration of each compound
in a mixture does not vary uniformly with changes in temp-
erature, pressure, and humidity. Further, examples have
been noted of counter-action (net lowering of perceived odor
in mixtures of odorants) and synergism (increase of perceived
odor in mixtures of odorants). A TRS concentration where
all of the sulfur is present as H S may be perceived differently
than the same TRS concentration made up of equal parts of H s,
RSH, RSSR, and RSR. Whether these subtleties will
decrease the value of a TRS determination as a measure of
acceptability needs to be determined. The alternative may
be a complicated and costly alternative.. The results will
have an. important bearing on the work proposed in Section '
11.1.5.
11.2 SPECIFIC R & D PROJECTS
Section 11.1 defined eight major areas of research effort
in which work is required to produce substantial progress
in emissions control. This section describes specific
project areas arranged in categories similar to those in
Chapter 10, but keyed insofar as possible to the eight major
areas.
11.2.1 EMISSION CONTROL TECHNOLOGY
The following projects are among those necessary to fulfill
the objectives of Section 11.1.2.
a. Obtain more definitive information on weak and strong
BLO (e.g. identification of catalytic agents, effect
of pH, and effect of thiosulfate concentration on reaction
rate and completion; effect of BLO on subsequent emissions
from ME evaporators, DC evaporators; Venturi evaporators,
and recovery furnace for hydrogen sulfide and other sulfur
compounds).
11-6
-------
b. Determine the factors which affect the "reversion" of
thiosulfate to sulfides when oxidized black liquor is
evaporated.
c. Investigate the contribution of hydrogen sulfide from
contact between flue gases and unoxidized black liquor
in wet bottom precipitators.
d. Continue studies on effect of operating variables on
odorous emissions from recovery furnace.
e. Determine the effect of operating variables on emissions
and gas volumes from slakers, evaporators, and smelt tank.
f. Compare emissions from batch and continuous digesters
as a function of operating variables (temperature,
time, sulfidity, wood species, et cetera).
g. Compare emissions from lime recovery using rotary kiln
versus fludizied bed calciner. Also delineate factors
which influence emissions (e.g. operating variables and
form of sulfur in lime mud).
h. In general, emission data collected in ithe future
should be related to process and operating conditions
which existed at the time of the sampling.
The following projects propose investigation of possible
alternatives to presently used emission control schemes
which may improve effectiveness or be more economical:
i. Investigate alternatives to treat stack gases effectively
and economically to remove odorous sulfur gases (e.g.
alkaline liquor scrubbing, caustic liquor scrubbing,
thermal oxidation, absorption and chemical oxidation).
j. Evaluate the effectiveness of injecting vent gas from
the smelt tank into the flue gas duct ahead of the ID
fan.
k. Investigate alternative treatment methods for control of
odorous emissions from evaporators, slakers, smelt tank,
and BL oxidizers.
1. Investigate feasibility of using bag filters for particu-
late collection on various sources.
11-7
-------
m. Investigate alternative methods for collection and dis-
posal of bark char (e.g., scrubbers and precipitators) .
n. Determine whether odorous sulfur compounds can be des-
troyed in the digester before blowing.
o. Investigate application and feasibility of using brown
stock washer vent gases as forced draft air supply for
the recovery furnace.
The following projects are intended to provide needed infor-
mation on emissions which is not presently available or evaluate
effects of control techniques presently in use or proposed:
p. Evaluate the effect on the environment of converting
essentially all TRS emissions to sulfur dixoide by thermal
oxidation.
q. Identify and quantify particulate and gaseous emissions
from "minor" sources in the kraft, sulfite, and NSSC
processes. Place emphasis on odorous sulfur gases. Relate
emissions to operating and process variables. (Minor sources
include brown stock washers/ hot wells, mud washers, waste
water sumps, waste water treatment facilities, et cetera).
r. Evaluate emissions from vented and closed circuit pressure
brown stock washers.
s. Evaluate the effects of scrubbing with oxidized weak
black liquor on subsequent evaporation of the liquor
and chemical recovery cycle.
t. Evaluate results on emissions of burning noncondensibles
in a fludized bed calciner.
11.2.2 COST AND EFFECTIVENESS OF EMISSION CONTROL
The basis for selection of a particular control scheme is
an evaluation of the cost and effectiveness. Better infor-
mation is needed for operating and maintenance costs on
existing systems and cost data should be developed for
proposed techniques. This would help to evaluate the economic
impact of various abatement alternatives. The following
projects will aid in obtaining such information:
a. Investigate the economics of the various alternatives
to maintaining the performance level of high-efficiency
particulate collection systems.
11-8
-------
b. Parts of i, k, 1, m, n, and o in Section 11.2.1.
c. A more detailed look into some of the subtleties of
sulfur recovery as more and more operating data are
gathered on some of the proposed SO recovery systems.
d. Evaluate cost-effectiveness of "multi-use" control
devices (e.g.,scrubbers effective on both particulates
and certain gases).
e. Encourage collection of better information on annual
operating effectiveness and maintenance costs on all
types of control equipment.
11.2.3 SAMPLING AND ANALYTICAL TECHNIQUES
The following projects are among the most important in ful-
filling the objectives of Section 11.1.1.
a. Develop and standardize analytical methods for malodorous
sulfur compounds at ambient air concentrations (both manual
and instrumental methods).
b. Conduct extensive intercomparisons of instrumental and
wet chemical methods at a number of sites ranging from
a simple situation where a pulp mill represents the
primary source of pollutants to a complex situation
where other types of pollutants also exist.
c. Conduct extensive intercomparisons of available analyti-
cal methods on a variety of mill and synthetic sources
to establish the reliability and inconsistencies of each.
d. Examine possible changes which may take place in flue
gas samples as they pass through sample lines of
varying lengths, materials of construction, and temp-
erature .
e. Verify the separation of sulfur compounds in the
presence of other non-sulfur compounds by preselective
filtration.
f. Evaluate sophisticated gas chromatographic instrumenation
under mill conditions.
g. Promulgate a set of sampling specifications for uniform
application throughout the industry. • :.••••• -
11-9
-------
h. Encourage increased use of continuous TRS monitors on
a variety of sources in the mills (e.g., recovery
furnace, lime kiln, smelt tank, evaporators, blow tank,
and digesters), and determine limitations.
i. Encourage a series of regional workshops regarding
application of TRS monitors and exchange of constructive
information by working personnel.
j. Improve reliability of TRS instrumentation and required
ancillary equipment for monitoring and process control.
k. Extend the development of the basic principle of newer
detectors such as the Whittaker electrochemical cells
to units which will exhibit selectivity for the odorous
compounds of interest.
The following projects are among those necessary to fulfill
the objectives of Section 11.1.6:
1. Develop analytical techniques applicable to sulfite and
NSSC processes particularly where these sources are
near other known sources.
m. Develop instrumental method for sulfuric acid aerosol in
the ambient air.
11.2.4 CONTROL EQUIPMENT DEVELOPMENT
In the immediate future, dependence will have to be placed,
in many locations, on add-on control devices. The following
projects are intended to improve the reliability and
application of such devices:
a. Development activities to improve reliability and
lower operating maintenance costs of control devices.
b. Develop and assess scrubber or other systems for removal
of SO and TRS compounds of interest simultaneously.
11.2.5 PROCESS CHANGES
The following projects are among those necessary to fulfill
the objectives of Section 11.1.2:
a. Evaluate the effectiveness of new recovery boiler designs
which eliminate direct contact between the flue gases and
the black liquor, and investigate the effect of operating
variables on all gaseous and particulate emissions.
11-10
-------
b. Evaluate the impact of high black liquor solids (62 -
65 percent) requirements on emissions from ME evapora-
tors.
c. Investigate possible alternatives to furnace recovery
of valuable costituents in spent liquors.
d. Investigate designs for improving oxidation of the
black liquor in the diffusion washer zone of continuous
digester systems.
e. Study various stripping operations to determine the
effectiveness for removal of odorous compounds from
liquid streams.
11.2.6 CHEMISTRY OF POLLUTANT FORMATION OR INTERACTIONS
The following projects are among those necessary to fulfill
the objectives of Sections 11.1.2, 11.1.3, and 11.1.5.
a. Obtain more complete knowledge of the reaction between
oxidized and unoxidized black liquor with flue gases.
b. Investigate the conditions which control the generation
of odorous sulfur compounds in the recovery furnace
itself.
c. Elucidate the role of adsorption of odorous sulfur
gases on concomitant particulates on human odor per-
ception and response.
d. Also item c with respect to the validity of reported
concentrations obtained when ambient air is either
sampled through filters or passed directly into the
collector or impinger.
e. Investigate transformation of kraft emissions during
transport and diffusion in the ambient air.
f. Determine the chemistry of oxidation of RSH, RSR, RSSR,
H S, and S~~.
g. Chemical characterization of non-sulfur compounds in
recovery furnace emission.
11-11
-------
11.2.7 NEW PULPING PROCESSES
The following projects are among those necessary to fulfill
the objectives of Section 11.1.4:
a. Intensify investigations into Holopulping.
b. Continue efforts toward development of other sulfur-
free pulping systems.
11.2.8 CONTROL SYSTEM DEVELOPMENT
Several new developments have occurred in recent years which
promise reduced emissions. These have not been combined into
workable systems as yet. To satisfy some of the objectives
of Section 11.1.4 evaluations should be made of emissions
and economics of various combinations of the following:
a. Solvent extraction of chips
b. Increased permeability of chips
c. High-yield soda cook
d. Alkaline sulfite cook
e. Vapor-phase kraft cook
f. Oxygen/alkali bleaching
g. Standard recovery
h. Berkeley VC recovery
11.2.9 OTHER
The following projects are among those necessary to fulfill
the objectives of Sections 11.1.3 and 11.1.5:
a. Develop and standardize methodology for evaluating
human response to odor annoyances.
b. Intensify research into receptor effects (physical,
biological, and aesthetic) of chemical pulp mill
emissions.
11-12
-------
CHAPTER 12
CURRENT INDUSTRY INVESTMENT AND OPERATING COSTS
TABLE OF CONTENTS
Page No.
Summary 12-1
Introduction 12-2
Incremental Cost Categories 12-7
Total Installed Costs 12-8
Total Annual Costs 12-9
Net Annual Costs 12-13
12-i
-------
CHAPTER 12
CURRENT INDUSTRY INVESTMENT AND OPERATING COSTS
SUMMARY
Past estimates of the expenditures made by the wood pulping
industry-for air quality control have indicated that
substantial sums are involved, but the numbers vary widely.
Because of congressional interest in the impact of the federal
air quality control program on all aspects of the economy, cost
figures for the wood pulping industry would have to be obtained
on a rational basis. Using the latest available data, estimates
were made of the replacement cost and the annual operating cost
of air quality control equipment in present operation in the
industry.
Sophisticated engineering cost estimates were prepared in three
categories: (1) Total Installed Cost (for replacement), (2) Total
Annual Cost, and (3) Net Annual Cost (which reflects a credit for
recovered materials). Estimates were prepared for a variety of
controls on a number of sources. It should be noted that the
cost analyses in this chapter are based on prices of chemicals
and equipment as of January 1969. As these prices change the
whole balance could change.
Total Installed Cost for kraft was in excess of $166 million
and for sulfite about $900,000. Total Annual Cost for kraft
was about $24 million and Net Annual Cost about the same. Net
Annual Costs for sulfite indicated a slight net return.
12-1
-------
12.1 INTRODUCTION
Over the past 5 to 10 years a number of estimates has
been made of expenditures by the wood pulping industry
for air quality control. The estimates have indicated
that substantial sums of money are involved, but the
numbers vary widely. In attempting to update the data
and provide a foundation for projections into the future
it was discovered that the basis of most of the projections
was obscure. Even where fairly good coverage of the in-
dustry was obtained by questionnaire, the cost items
included in the replies varied from company to company
and even mill to mill.
Since Congress is vitally interested in the economic
impact of the federal air quality control program, now
and in the future, it was determined that cost figures
would have to be obtained on a rational basis.
There are several cost categories which must be identified
and assigned a cost before a total cost estimate can.be
prepared. Tangible items of cost are identified in this
chapter. There are, however, intangible cost categories
such as research and development, engineering, and air
quality monitoring which are an integral part of the
environmental protection picture, but for which cost estimates
are difficult to make.
Activities, such as research and development, engineering,
and air quality monitoring contribute extensively to the
total bank of knowledge on emission sources, control techniques,
and the effects of emissions; but the costs for such activities
have not been estimated for this report.
12.1.1 PURPOSE OF THIS CHAPTER
The purpose of this chapter is to assess the cost
of emissions control for the wood pulping industry.
Specifically it is desired to determine the replace-
ment cost and annual operating cost of air quality
control equipment in present operation in the industry.
It should be noted that the cost analyses in this chapter
are based on prices of chemicals and equipment as of January
1969. As these prices change the whole balance could change.
12-2
-------
12.1.2 EVALUATION OF METHODS FOR DETERMINING COSTS
There are two methods by which the desired result
could be achieved. These are a direct survey of
the industry or an engineering cost estimate for
specific types of equipment coupled with an inven-
tory of the number of such items installed today.
The latter alternate was chosen for this study.
Contacts with the industry revealed that accounting
procedures varied widely within the industry. Some
companies charge part of the cost for a particular
system to air quality control and part to process,
while others may charge the entire cost to either
one or the other. Maintenance charges are not
always charged to a specific piece of equipment,
but perhaps to a group of equipment items or to a
section of the plant. For these reasons, it would
be difficult, if not impossible, to determine the
required costs on any kind of a common basis. There-
fore, the second alternate, that of an engineering
cost estimate, was chosen.
12.1.3 SPECIFIC PLAN FOR ASSESSMENT OF COSTS
The plan chosen consisted of four steps:
1. Determining what types of equipment and/or
systems for air quality control are now in-
stalled in the pulp industry.
2. Develop cost data by means of an engineering
estimate for those items.
3. Determine the actual number of each such item
currently installed in the industry.
4. Using 2 and 3 above, calculate the replacement cost
for air quality control systems.
Steps 1 and 2 above were covered in Chapter 5
of this report. Step 3, for the kraft industry,
was accomplished through a study of the NCASI-
NAPCA kraft pulp industry questionnaires. Forty-
four of the questionnaires were examined.
12-3
-------
These forty-four questionnaires, covering 38 per-
cent of the 116 known kraft mills, account for a
daily air dried pulp capacity of 40,319 tons or
46 percent of the total of 87,808 tons per day.
The data obtained from these questionnaires were
extrapolated to the total industry, modified by
in-house knowledge and discussions with NCASI.
Items covered in this survey included type of
digesters: yield; treatment of noncondensible
gases; black liquor oxidation; recovery boilers;
lime kilns; and types of controls on recovery
boilers, smelt dissolving tanks and lime kilns.
The same type of tablulation was made based on
data from Post's Pulp and Paper Directory, 1969
edition, for comparison. These data, extrapolated
in the same manner gave essentially the same
results. The extrapolated totals on which the
calculations were made are shown in Table 12-1.
Questionnaire data for the sulfite and NSSC processes
were not available to this study team. Therefore,
only gross estimates can be made as to the number of
specific control schemes which are utilized.
For sulfite mills only three types of controls have
been described in Chapter 5. These are (1) blowpit-
condenser with cyclone and packed tower, (2) blow-
pit with packed tower, and (3) packed tower added to
the acid tower. It is estimated that only 2 mills
utilize the first control method, about 10 mills
utilize the 2nd method, and 22 mills utilize the 3rd
method.
For NSSC mills, the only specific control device, in
addition to those used for sulfite, is a scrubber
serving the Copeland reactor. Only 2 or 3 mills are
expected to employ this scheme.
12-4
-------
TABLE 12-1
AIR QUALITY CONTROL IN THE WOOD PULPING INDUSTRY
EQUIPMENT AND PROCESSES PRESENTLY EMPLOYED FOR KRAFT
Item
Digesters :
Batch (only)
Continuous (only)
Batch & Continuous
High Yield (>48 percent)
Low Yield (<48 percent)
Noncondensible Gases :
Vented
Incinerated in lime kilns
Scrubbers (cyclonic,
packed towers, etc.)
Catalytic Oxidation
Units
Black Liquor Oxidation Units :
Weak
Strong
None
Number
Of Mills
77
13
26 /
116
34
82
116
85
13
16
2
116
21
21
74
116
Percent
Of Total
66.4
11.2
22.4
100.0
29.3
70.7
100.0
73.3
11.2
13.8
1.7
100.0
18.1
18.1
63.8
100.0
12-5
-------
TABLE 12-1 (Cont'd)
Item
Recovery Boilers:
Units with Electrostatic Precipitators
Units with Venturi Evap/Scrubbers
Total Number of Recovery Boilers
Actual Number of Precipitators
Secondary Scrubbers on Precipitators
Secondary Scrubbers on Venturi
Evap/S crubbe rs
Dissolving Tanks :
Units with no Control
Units with Mesh Pads
Units with Packed Towers
Units with Cyclonic Scrubbers
Lime Kilns:
Rotary Kilns
Fluid Bed Kilns
Scrubbers :
Units with Dust Chamber or Similar
Units with Peabody or Similar
Units with Cyclonic Scrubbers
Units with Venturi Scrubbers
Units with no Scrubbers
Total Number of Power Boilers
Number
Of Units
244
39
283
196
11
7
96
156
3
28
283
189
2
191
32
102
11
44
_2
191
347
Percent
Of Total
86.2
13.8
100.0
5.6
17.9
33.9
55.1
1.1
9.9
100.0
99.0
1.0
100.0
16.8
53.4
5.8
23.0
1.0
100.0
12-6
-------
12.2 INCREMENTAL COST CATEGORIES
Three broad classes of costs are used to define the cost
of air quality control devices presently installed in the
pulp industry. These are: (1) Total Installed Cost, (2)
Total Annual Cost and (3) Net Annual Cost.
Obviously, there are several categories within each of the
three broad classes.
There are six cost categories which must be considered in
arriving at Total Installed Cost. The first item of cost
is that of the control device itself, purchased equipment.
Other cost items are equipment erection, equipment found-
dation and building, process instrumentation and piping,
power wiring and lighting, and indirect costs which in-
clude contingency, engineering, construction supervision,
general construction overhead, spare parts, and sales tax.
In turn, each of these cost categories is influenced by
several variables which depend on specific circumstances;
some can only be evaluated on a mill-by-mill basis.
Equipment costs are dependent upon collection efficiency,
size, and material of construction. Equipment erection
costs are dependent on labor rates. The amount of labor
involved is obviously influenced by the material of construction
of the control device, size, site conditions, as well as the
physical location of the control device (on the ground or
on top of a building).
Building costs are controlled by local building codes and
by labor rates and are dictated in the first place by
climatic conditions. Foundation costs are affected by
soil conditions, labor rates, and material costs. Process
instrumentation and piping, and power wiring and lighting
costs are determined by labor rates and by material costs.
Total Annual Cost includes charges for labor (including
overhead), maintenance, utilities (electricity or steam,
fuels, water, air and others), materials and chemicals,
12-7
-------
waste water disposal facilities and/or methods, taxes
and insurance, depreciation and interest, and administrative
costs.
Net Annual Cost is identical to Total Annual Cost, except
that credit has been allowed for recovery of heat and/or
chemicals. More details concerning the method of calcu-
lation used for these cost categories may be found in
Chapter 5.
12.2.1 TOTAL INSTALLED COST
The data contained in Table 12-1 were used along
with cost data from Chapter 5 to determine the
total installed cost which would have to be expended
by the kraft industry to replace existing si± 'quality
control systems. To illustrate the method used, an
example using electrostatic precipitators installed
following recovery boilers is shown below:
Number of recovery boilers = 283
Total daily capacity = 87,808 A.D. Tons
Average tonnage per
recovery boiler = 87,808 - 283 = 310 TPD
*
Number of recovery boilers
with precipitators = 244
Actual number of pre-
cipitators = 196
Average number of pre-
cipitators per recovery
boiler = 196 - 244 = 0.804
Average tonnage per pre-
cipitator = 310 T 0.804 = 386 TPD
Gas flow at precipitator
per A.D. TPD = 350 ACFM
12-8
-------
Average gas flow per
precipitator = 386 x 350 = 135,000 ACFM
Assumed average pre- Tile, wet bottom, 95 percent
cipitator = efficiency
Cost per unit = $540,000
Total installed cost for
the industry = 196 x 540,000 = $105,840,000
This figure represents the total cost to replace the 196 electrostatic
precipitators. Perhaps 10 percent of this value ($10,580,000) could
be directly chargeable to air quality control. Costs for other units
were calculated in a similar manner and are tabulated in Table 12-2.
-All costs are on a January 1, 1969, basis. .....
Data presented in Chapter 2 suggest that the average size of
sulfite and NSSC mills is about 250 TPD. For purposes of
estimating the replacement cost of current control equipment
we have taken costs from Chapter 5 for the 200 TPD mill.
With this assumption, one estimates that the replacement
cost of control equipment installed at sulfite mills is
approximately three million dollars. Data are not avail-
able to allow an estimate of the replacement cost of control
devices installed at NSSC mills to be made.
The costs estimated above do not include an estimate for
costs of controls on power boilers associated with sulfite
and NSSC. No accurate count is available to suggest the
number of such boilers which might exist.
12.2.2 TOTAL ANNUAL COSTS
Total annual costs were developed in a manner similar to the
method used to determine total installed costs in the previous
section. Table 12-3 lists this cost for the same items in
Table 12-2.
12-9
-------
TABLE 12-2
AIR QUALITY CONTROL IN.THE. WOOD. PULPINR INDUSTRY
TOTAL INSTALLED COST. FOR EQUIPMENT .FOR .KRAFT:,. .
Total Installed
Item Cost
Noncondensible Gas Treatment
Lime Kiln Incineration $ 400,000
Catalytic Oxidation 300,000
Scrubbers 500,000
Black Liquor Oxidation Units
Weak Black Liquor Oxidation 5,400,000
Concentrated Black Liquor Oxidation 5,800,000
Recovery Boilers
Electrostatic Precipitators (196 units) 105,800,000*
Secondary Scrubbers on Electrostatic
Precipitators 1,600,000
Secondary Scrubbers on Venturis 2,000,000
Dissolving Tank Vents
Mesh Pads 2,000,000
Packed Towers 100,000
Cyclonic Scrubbers 1,100,000
Lime Kiln Scrubbers
Venturi Scrubbers 4,000,000
Peabody and Similar Types 7,800,000
Cyclonic Scrubbers 500,000
Power Boiler Mechanical Collectors 29,000,000
$166,800,000
*This figure represents the total cost to replace the 196 known
electrostatic precipitators. Perhaps 10 percent of this value
($10,580,000) could be directly chargeable to air quality control.
12-10
-------
TABLE 12-3
AIR QUALITY CONTROL IN THE WOOD PULPING INDUSTRY
TOTAL ANNUAL COST FOR EQUIPMENT FOR KRAFT
Item Total Annual Cost
Noncondensible Gas Treatment
Lime Kiln Incineration 400,000
Catalytic Oxidation 100,000
Scrubbers 200,000
Black Liquor Oxidation Units
Weak BLO 1,800,000
Cone. BLO 2,500,000
Recovery Boilers
Electrostatic Precipitators (196 units) *
Secondary Scrubbers on Elect. Ppts. 700,000
Secondary Scrubbers on Venturis 800,000
Dissolving Tank Vents
Mesh Pads 600,000
Packed Towers 35,000
Cyclonic Scrubbers 300,000
Lime Kiln Scrubbers
Venturi Scrubbers 1,600,000
Peabody & Similar Types 3,000,000
Cyclonic Scrubbers 100,000
Power Boiler Mechanical Collectors 12,000,000
$24,135,000
*Total Annual Cost for the 196 precipitators was estimated at
$28,100,000. It is not possible, however, to assess the
true portion of this cost which could be directly chargeable
to air quality control.
12-11
-------
Total annual costs for control equipment in sulfite mills
is estimated as:
1. Blowpit: condenser with cyclone and
packed tower — $262,000
2. Blowpit: packed tower — $580,000
3. Packed tower added to acid tower — $ 57,200
Total — $899,200
The above estimates do not include costs for controls on power
boilers associated with sulfite or NSSC mills because no
accurate count is available to suggest the number of such
boilers which might exist.
It was originally planned to include an extensive table of
maintenance costs, based on data from actual operating mills,
for all types of installed air quality control systems. However,
it became readily obvious that this could not be done since the
majority of mills do not have such charges documented by specific
equipment items. The limited amount of information which was
collected is presented in Table 12-4 which summarizes the
costs in cents per ton of air dried pulp production. Each
value shown represents a specific piece of equipment. The
data include varying sizes of equipment and varying ages of
equipment.
TABLE 12-4
CONTROL EQUIPMENT MAINTENANCE COST
Specific Values
Item Cents per ton of pulp produced
Electrostatic Precipitators 29.6, 5.4, 3.9, 2.9, 2.5, 2.3, 2.3
Recovery Boiler Fans 3.2, 2.0, 1.0, 0.9, 0.5, 0.4
Scrubbers (All Types) 2.8, 2.4, 2;0, 1.0, 0.5
BLO Systems 2.8, 1.0, 0.5
Bark Boilers (Ash Collecting Equip.) 1.8, 0.7
Bark Boilers (Fans) 1.7, 0.5
12-12
-------
Figure 12-1 attempts to portray the maintenance cost
data for precipitators as influenced by process size.
This figure shows that cost per ton for maintenance
generally decreases as process size increases. Built
into this curve, however, is the fundamental fact that
the smaller sizes (which have the highest maintenance)
are also the older units. Undoubtedly, it is a
combination of both size and age which influences
maintenance costs.
Table 12-5 represents the output from another approach
toward establishing annual maintenance charges for
existing emission control equipment. Engineering estimates
of maintenance costs, used in Chapter 5 as part of the
annual operating cost, were coupled with data in Table
12-1 to give the results shown in Table 12-5. This
estimate totals nearly three million dollars annually.
12.2.3' NET ANNUAL COSTS
Net annual cost is identical to total annual cost
except that credit has been allowed for the value
of the recovered chemicals. For the kraft process,
the only equipment items to which this has been
applied are the electrostatic precipitators, secondary
scrubbers installed subsequent to electrostatic pre-
cipitators, venturi evaporator/scrubbers, and lime
kiln scrubbers. With the exception of the precipitators,
the cost data from Chapter 5 were used directly.
Table 12-6 lists the net annual cost to the kraft
industry for operating existing air quality control
equipment and totals just over $23 million.
In sulfite mills, cost estimates for the blowpit:
condenser with packed tower, and blowpit: packed
tower, show that the value of chemical and heat
recovery outweighs the total annual costs, thus
giving rise to a net return or savings.
There is no appreciable chemical or heat recovery
associated with the packed tower added to the acid
tower, so net annual costs are the same as total annual
costs.
12-13
-------
30
25
o
-M
S-
-------
T ABLE 12-5
AIR QUALITY CONTROL IN THE WOOD PULPING INDUSTRY
ANNUAL MAINTENANCE COSTS FOR EOUIPMENT FOR KRAFT
Item
Noncondensible Gas Treatment:
Lime Kiln Incineration
Catalytic Oxidation
Scrubbers
Black Liquor Oxidation Units;
Weak BLO
Concentrated BLO
Recovery Boilers;
Electrostatic Precipitators
(196 units)
Secondary Scrubbers on Elec. Ppts.
Secondary Scrubbers on Venturis
Dissolving Tank Vents;
Mesh Pads
Packed Towers
Cyclonic Scrubbers
Lime Kiln Scrubbers;
Venturi Scrubbers
Peabody & Similar Types
Cyclonic Scrubbers
Power Boiler Mechanical Collectors
Annual Maintenance Cost
15,600
10,200
1,920
136,500
136,500
1,607,200
29,330
54,600
12,792
2,625
24,500
9,680
18,360
11,000
832,800
$2,903,607
12-15
-------
TABLE 12-6
AIR QUALITY CONTROL IN THE MOOD PULPING INDUSTRY
NET ANNUAL COST FOR EQUIPMENT FOR KRAFT
Net Annual
Item Cost
Noncondensible Gas Treatment
Lime Kiln Incineration $ 400,000
Catalytic Oxidation 100,000
Scrubbers 200,000
Black Liquor Oxidation Units
Weak Black Liquor Oxidation 1,800,000
Concentrated Black Liquor Oxidation 2,500,000
Recovery Boilers
Electrostatic Precipitators (196 units) *
Secondary Scrubber on Electrostatic
Precipitators 400,000
Secondary Scrubbers on Venturis 500,000
Dissolving Tank Vents
Mesh Pads 600,000
Packed Towers 35,000
Cyclonic Scrubbers 300,000
Lime Kiln Scrubbers
Venturi Scrubbers 1,400,000
Peabody and Similar Types 2,600,000
Cyclonic Scrubbers 100,000
Power Boiler Mechanical Collectors 12,200,000
TOTAL $23,135,000
*When credit is taken for the value of chemicals recovered by the
Precipitators, a net gain of about $7,600,000 is observed.
12-16
-------
CHAPTER 13
FUTURE INDUSTRY INVESTMENT AND OPERATING COSTS
TABLE OF CONTENTS
Page No.
Summary 13— 1
Introduction 13-2
Concepts for a Management Model 13-2
Analysis of Emission Sources and Controls 13~ 9
Costs of Control Methods 13-10
Optimization Model 13-15
Analysis of Cost impact 13-21
Limitations of the Model 13-31
Assignment of Particulate Control Costs (Process 13-33
or Emission Control) - Case I
Effect of Value of Recovered Chemicals 13-33
Effect of Varying Performance Standards 13-34
Effect of Using Higher Rate of Return 13-40
Trends in Future Capital Expenditures 13-40
Example Calculations for New Mill 13-42
Example Calculations for Existing Mill 13-43
Control Expenditures at New Mills 13-46
Control Expenditures at Existing Mills 13-48
References 13-49
13-i
-------
CHAPTER 13
FUTURE INDUSTRY INVESTMENT AND OPERATING COSTS
SUMMARY
This chapter reports the rationale for and development
of a model which provides flata which can be used to project
the investment and operating costs for emission control in
the kraft pulping industry through 1980. Data are not
available to perform similar analyses for sulfite and NSSC
mills. A sensitivity analysis is also presented which
suggests how the costs: for emission control are influenced
by emission standards, value of recoverable chemicals, and
assumed rate of return.
To assist with the analysis, multi-path flow diagrams have
been developed to indicate the various process alternatives
which influence emissions. A simple program is presented to
estimate total annual costs as a function of fixed and
variable costs.
A mathematical programming model was developed and
is presented by which it is possible, for any specified
mill, to determine the optimal way to satisfy specified
emission standards. The objective function is to
maximize net revenue from emission control. Constraining
functions include continuity from source to control,
continuity from control to recovery, performance standards,
control bounds, implicit integer constraints, and
non-negativity restrictions. An example is analyzed
with the model using the 1969 Oregon regulations. Costs
for the example were based on prices of chemicals and
equipment as of January 1969. As these prices change,
the results of the analysis would also change.
13-1
-------
13.1 INTRODUCTION
Investments and costs incurred by the industry for emission
control are not uniform throughout the U. S. Emission
limitations imposed by various authorities range from none
to relatively strict. Few applicable regulations are in
effect in the southeast where the great bulk of pulp pro-
duction is concentrated. The trend, however, appears to be
for more restrictive regulations.
This chapter reports the rationale for and development of
a model which provides information which can be used to pro-
ject the investment and operating costs needed for emission
control in the kraft pulping industry through 1980. Sufficient
data are not available to perform similar analyses for
sulfite or NSSC mills. This chapter also presents a
sensitivity analysis which determines how the costs for
particulate emission control are influenced by emission
standards and value of recoverable chemicals.
13.2 CONCEPTS FOR A MANAGEMENT MODEL
This chapter has as its objective to set forth a rational
mechanism whereby the costs of emission control can be
determined. Certain steps within the kraft system are
there for the prime purpose of chemical recovery. Without
chemical recovery (in the recovery furnace) the kraft
process is not economically feasible. The critical
issue is how far would the industry go in designing for
chemical recovery in an unrestrained decision as opposed
to how far it may be forced to go to satisfy emission
constraints established by law. Such an analysis is
presented in later sections.
To assist with this analysis a multi-path flow diagram
for kraft processing was developed (Figure 13-1). This
diagram represents a composite picture of kraft processes
and indicates the various processing alternatives which
influence emissions.
13-2
-------
Figure 13-1 is to be interpreted as follows: solid line
boxes represent distinct processing steps; "clouds" represent
emissions. If there is no cloud attached to a solid line
box it is concluded that no emissions are generated at
that point. Numbers contained within the clouds refer
to emission values contained in Table 13-1. If there are
two numbers in the cloud this indicates that "yield" influences
the emission. The upper number refers to the emission from
a high yield mill, the lower number refers to that from a
low yield mill. For purposes of this study low yield is defined
to be less than 48 percent, high yield is said to be 48
percent or more.
An example will further illustrate interpretation of
Figure 13-1. The first processing variable is batch versus
continuous digestion. The number 1 (only one number) shown
in the cloud attached to the turpentine condenser box indi-
cates that emissions from that source are not influenced by
yield nor are they influenced by the type of digester.
The eight lines in the center of the sheet show the many
processing alternatives using weak and/or heavy BLO, et
cetera. Looking at emissions from the D.C. evaporator-
recovery furnace on the top two lines, one sees that there
are two different numbers in each box. This means that
yield influences the emissions from this processing step
and also that the utilization of weak BLO will influence
emissionso
At the smelt dissolving tank there is only one number
shown. This means that emissions from the smelt tank
are independent of all other process alternates. The
only other emission variable comes at the lime kiln where
it is shown that incineration of noncondensible gases
as well as yield affects emission values.
Power boilers, which are independent of processing alternates,
are shown separately with emissions being dependent on type
and quantity of fuel consumed. Some repetition is shown
in the interest of simplifying flow paths.
Figure 13-2 indicates those sources emitting particulates
and the control devices applicable for particulate control
at each source. Figure 13-3 presents the same information
for hydrogen sulfide and total organic sulfur compounds
and; igure 13-4 is a similar presentation for sulfur dioxide.
13-3
-------
TABLE 13-1
SOURCE ID SOURCE NO
X TURPENTINE CJ.J J ENSER-HIGH OR LOW YIELD Ol ~
XHEAT />CCUMU_ATJR-hIGH OR LOW YIELD 02
XOATCH fcASH£rto-HIGH OR LOW YIELD 03
XCONTINUOUS 4A3HERS-HIGH OR LOW YIELD O4
XMULTIPLE EFFt£v_T E VA PGRA TOR-HI GH OR LOW YIELD OS
XDC EV/>PO,«ArO»*-rJ ECOVERY BOILER-WI THOUT BLO-HIGH YIELD 06
XDC EV/PORATOK-RECCVERY B CI LE R-W I TH OUT BLO-LOW YIELD O7
XWEAK. ELAC< LiJUOK O X IOAT ION- HIGH YIELD OS
XWEAK ELAC< iL.lUJCR OXIDATION-LOW YIELD O9
XMULTIPLE Ef-Ft£Cr EVAPORATOR-HIGH OR LOW YIELD 10
XQC EVAPOKATll<--tECCVERY BOILER WITH BLO-HIGH YIELD 11
XCC EVAPORATOR--* ECOVERY BOILER WITH 8LO-LOW YIELD 12
XCONCENTRATEC Ji_O-HlGH YIELD 13
XCONCENTRArSC Ji_O-LOW YIELD 14
XVENTUfil EVAP/oCRCBBER VklTHOUT BLO-HIGH YIELD 15
XVENTUHI EVAP/JCRUBBER WITHOUT 3LO-LOW YIELD 16
XVENTURI EVAP/3CRUBBER WITH 6LO-HIGH YIELD 17
XVENTURI EVAP/3CRU3BER WITH BLO-LOW YIELD 18
XHIGH SOL I 05 c. VA PORA TOR-H I GH OP LOW YIELD 19
XRECOVERY EO Ii_c^-H IGH OR LOW YIELD 20
XSNELT TANK-HIjil OR LOW YIELD 21
XSLAKE TANK-HlsiH CR LOW YIELD 22
XL IME KILN WITHOUT INCINERATION-HIGH YIELD 23
XL IMS K IL.M *ITr»JtT INCINERATION-LOW YIELD 24
XLIME KILN WITH INC INERA TI CN-HIGH YIELD 25
XLIME KILN WITH INCINERATION-LOW YIELD 26
XPCWEH eCILER-clARK 27
XPOWER BCILEK-COAL 28
XPOWER BCILER-JIL 29
XPOWER BOILER-GAS 30
*EMICOEF
XSORC01
XSCRCC2
XSORC03
XSORC 0 A
XSQRCOS
XSORCC6
XSGKCC7
XSORCC€
XSCHCC^
XSORC 10
XSORCl 1
XSORCl 2
XSORC13
XSCPC14
XSCRC If
XSORC ie
XSORC17
XSORCl 8
XSORC19
XSCRC2C
XSORC2 1
XSORC22
XSORC23
XSORC24
XSORC25
XSCKC26
/*EOJ
GASVUi. PARTICLE
60.
300.
97CCO.
7CCQJ.
30 .
230000 .
42000O .
3200.
13300.
5o.
230000.
4200OO .
«J4OO .
12200.
2S2CGO.
3 7dCOO.
2=2000 .
378000.
SO.
4000O0.
45000.
7CCO.
3 1400.
40*00 .
31400 .
4C900.
0.
0 .
0.
0.
0.
93.
140 .
0.0
0.0
0.0
93.
140 .
0 .
0.
30.
45.
30.
45.
0.
p-4-»-e-
4. 0
39.0
51.0
39.0
51 .0
HTWOS TOTORGS SOT WO
0.01
0. 1
0.01
0.02
0.40
10.
15.
0.02
0.02
0,01
1.0
1.5
O.01
O .0 1
1O.
Ib.
1.0
1.5
0.5
O.I
O.04
0.0
C. 8
1.0
0. 8
1.0
0.50
3.20
0. 10
O.22
0.5O
1.00
1 .50
O.4C
0.40
O.4O
0.70
1.00
0.30
O.30
l.O
1 .5
0.70
l.O
0.3
o.o
O.06
0.0
0.46
0.6
0.54
0. 70
o.
0.01
0. 01
O.O2
0.01
3.3
5.O
0.0
0.0
0.01
3.3
5 .O
0.0
0. 0
3.3
5.0
3.3
5.0
o.o
4.4-
0. O
O .0
3.0
4 .0
3.0
4. 0
13-4
-------
TO DIGESTER
DATE: Oct. 6, 1969
MULTI-PATH FLOW DIAGRAM
KRAFT PROCESSES
EXHIBIT NO.
Fig. 13-1
SYSTEMS ANALYSIS STUDY OF
EMISSIONS CONTROL IN THE WOOD PULPING INDUSTRY
CONTRACT NO CPA 22-69-18
FOR
DEPARTMENT OF HEALTH, EDUCATION AND WELFARE
CONSUMER PROTECTION AND ENVIRONMENTAL HEALTH SERVICE
NATIONAL AIR POLLUTION CONTROL ADMINISTRATION
ENVIRONMENTAL ENGINEERING, INC.
13-5
J E.SIRRINE COMPANY, ENGINEERS
GREENVILLE, 3.C.
-------
SYMBOLS
CHIPS
TERP COND
BATCH
DIGESTER
I TERP CONO
CONTINOUS
DIGESTER
BLOW TANK — WASHERS
_^_ BLACK
"*" STORA
iHERS
o
AIR EMISSIONS
CONTROL DEVICE
PROCESS EQUIPMENT
"ROCESS EQUIPMENT EMITTING PARTICULAR
POLLUTANT
CONTROL DEVICES
C-l ELECTROSTATIC PRECIPITATOR
C-2 CYCLONIC SCRUBBER
C-6 VENTURI SCRUBBER
C-7 CONVERT TO CYCLONIC EVAP. AND ADD PRECIPITATOR
C-8 PACKED TOWER SCRUBBER
C-9 MESH PAD
C-l2 MECHANICAL COLLECTOR
C-13 MECHANICAL COLLECTOR PLUS SCRUBBER
C-J-2 ELEC. PPT. PLUS CYCLONIC SCRUBBER
C-t-6 ELEC. PPT. PLUS VENTURI SCRUBBER
TO OI6ESTER
DATE: Oct. 6, 1969
SOURCES OF PARTICULATES AND APPLICABLE
CONTROL DEVICES
MULTI-PATH FLOW DIAGRAM
KRAFT PROCESSES
(XHIBIT NO.
Fig. 13-2
SYSTEMS ANALYSIS STUDY OF
EMISSIONS CONTROL IN THE WOOD PULPING INDUSTRY
CONTRACT NO CPA 22-69-18
FOR
DEPARTMENT OF HEALTH, EDUCATION AND WELFARE
CONSUMER PROTECTION AND ENVIRONMENTAL HEALTH SERVICE
NATIONAL AIR POLLUTION CONTROL ADMINISTRATION
I ENVIRONMENTAL ENGINEERING, INC.
, GAINCSVILLC. FLORIDA
J E. SIRRINE COMPANY, ENGINEERS
GREENVILLE, 9.C.
13-6
-------
SYMBOLS
CHIPS
RECOVERY BOILER
(ACE SYSTEM)
AIR EMISSIONS
CONTROL DEVICE
PROCESS EQUIPMENT
•
PROCESS EQUIPMENT EMITTING
PARTICULAR POLLUTANT
CONTROL DEVICES
INCINERATION IN LIME KILN
SEPARATE INCINERATION
CHLORINATION
PACKED TOWER SCRUBBER
WEAK B.L.O.
CONCENTRATED B.L.O.
HOTE: MEN INCINERATION IN LIME KILN IS
USED IT IS ASSUMED THAT SOURCES I,
2, 5, 8, 9, 10, 13, & 14 ARE ALL
TREATED TOGETHER.
••— TO DIGESTER
ITERP COMO|
1
SOURCES OF H2S AND ORGANIC SULFUR
COMPOUNDS AND APPLICABLE CONTROL DEVICES
ICONTINOU3
DIGESTER
BLOW TANK
MULTI-PATH FLOW DIAGRAM
KRAFT PROCESSES
EXHIBIT NO.
Fig. 13-3
SYSTEMS ANALYSIS STUDY OF
EMISSIONS CONTROL IN THE WOOD PULPING INDUSTRY
CONTRACT NO. CPA 22-69-18
FOR
DEPARTMENT OF HEALTH, EDUCATION AND WELFARE
CONSUMER PROTECTION AND ENVIRONMENTAL HEALTH SERVICE
NATIONAL AIR POLLUTION CONTROL ADMINISTRATION
ENVIRONMENTAL ENGINEERING, INC.
GAINESVILLE, FLORIDA
J.E. SIRRINE COMPANY, ENGINEERS
ORieNVILLl.S.C.
13-7
-------
CHIPS
SYMBOLS
AIR EMISSIONS
CONTROL DEVICE
PROCESS EQUIPMENT
PROCESS EQUIPMENT EMITTING
PARTICULAR POLLUTANT
— TO DIGESTER
DATE: Oct. 6, 1969
SOURCES OF S02 AND
APPLICABLE CONTROL DEVICES
MULTI-PATH FLOW DIAGRAM
KRAFT PROCESSES
EXHIBIT NO.
Fig. 13-4
SYSTEMS ANALYSIS STUDY OF
EMISSIONS CONTROL IN THE WOOD PULPING INDUSTRY
CONTRACT NO. CPA 22-69-18
FOR
DEPARTMENT OF HEALTH, EDUCATION AND WELFARE
CONSUMER PROTECTION AND ENVIRONMENTAL HEALTH SERVICE
NATIONAL AIR POLLUTION CONTROL ADMINISTRATION
ENVIRONMENTAL ENGINEERING, INC.
I GAINESVILLE .FLORIDA
J. E. SIRRINE COMPANY, ENGINEERS
GREENVILLE, 3.C.
13-8
-------
13.3 ANALYSIS OF EMISSION SOURCES AND CONTROLS
In the preceding chapters of this report extensive cost
data for the alternative control schemes available to the
wood pulping industry have been brought together. It was
found that the technology for control of particle emissions
is well established and that the use of "add-on" devices
can be effective for this type of control.
Chlorination, packed tower scrubbing and lime kiln incineration
were shown to be practical methods for the control of H S and
other organic sulfur compounds being emitted from digesters,
blow tanks, and multiple effect evaporators. The effective-
ness of lime kiln incineration could be expected to approach
100 percent; chlorination and packed tower scrubbing are con-
sidered less effective. Therefore, with standards specify-
ing that malodorous compounds must be controlled by a method
equally as effective as lime kiln incineration, it becomes
apparent that only incineration can be considered as a feasible
solution.
For pulp washers, smelt tanks, and lime kilns there are
no known add-on devices, which can be utilized for the
control of malodorous emissions. It seems reasonable to
think that scrubbers at smelt tanks and lime kilns would have
somejeffect on the emission of H S and other sulfur compounds
but to date, data are lacking which would give a clue to the
effectiveness of these devices on odors. Apparently, the
only practical way to control emissions of H S and organic
sulfur compounds is to assure nearly 100 percent oxidation
within the kiln itself.
Chapter 6 makes reference to some new process technology
which might be applicable to pulp washers. The conclusion
drawn is that diffusion washing and pressure washing
appear to have significant future potential.
The installation of weak or heavy black liquor oxidation
can be considered as a control option for application to
D.C. evaporator-recovery furnace installations and Venturi
evaporator/scrubbers. If emissions still exceed limits
imposed by the regulations and a fairly new furnace is in
operation, an option might be conversion to one of the new
high solids evaporator designs and modification of the DC
evaporator. If an older furnace is in use, the only
alternative may be installation of a new recovery system
in which contact between flue gas and black liquor is
eliminated.
13-9
-------
No feasible methods for control of SO were identified.
A detailed discussion of sulfur recovery and control
schemes for power boilers was presented in Chapter 8.
From this discussion, it is concluded that if there are
no feasible schemes for the control of SO at power plant
scale then surely it is difficult to expect feasible
control to be effected on the more dilute process streams.
Control methods applicable to power boilers are effective
only in the removal of particulates. None of the methods
investigated would be effective in reducing emission
of sulfur compounds. The conclusion drawn in Chapter
5 is that due to the range of operating efficiencies
and costs, the selection of the most effective control
method would have to be determined for each individual
case.
13.3.1 COSTS OF CONTROL METHODS
The total cost of a given control can be partitioned
into a fixed cost and a variable cost. It is being assumed
that the fixed costs are comprised of the amortized capital
investment, taxes, insurance, and administrative cost.
Variable costs consist of direct operational costs as
itemized in Chapter 5 and include labor (including overhead),
raw materials and chemicals, utilities, maintenance and
supplies, and waste disposal.
A simple program has been written using the MARVEL language
associated with the IBM MPS/360 system to determine the
total annual costs as a function of the selected rate
of return, service life, administrative costs, and taxes
and insurance.
Let
U . = Total annual cost of control j
U . = Direct operating cost of control j
U . = Direct capital cost of control j
13-10
-------
n. • = Service life of control'j
i. = Rate of return for control j
Ali = Ratio of indirect capital costs to U for control j
A = Ratio of taxes and insurance to U_. (1+A,.) for control i
2] 3] 13 J
A = Ratio of administrative cost to U_,. (1+A, .) for control -i
•33 33 Ij J
Then, the total annual cost of control j, U ., can be expressed
as 3
j = U2j + (1+V D3jA2j + A3j
Eq. 13.1
For the calculations to date, indirect costs have been assumed
to equal 20 percent of direct capital costs (A . = 0.20 for all
j); taxes and insurance are 2 percent of total capital costs
(A = 0.02 for all j); and administrative costs are assumed to
equal 5 percent of total capital cost (A = 0.05 for all j).
Also rates of return of 10 percent (i. = 0.10 for all j) and
20 percent (i. = 0.20 for all j) have been used. The direct
operating cost, U , can be expressed as a function of gas
flow in CFM. Likewise, the cost functions for direct capital
costs can be presented as a function of gas flow in CFM. A
sample printout from the program is presented as Table 13-2.
All costs are based on the price of chemicals and equipment
as of January 1969. As these prices change, the results of
the analysis would also change.
Using equation 13.1 and knowing the relationships for direct
operating costs and direct capital costs, it is possible to
estimate the total annual costs directly for a relatively
wide variety of assumed conditions. These cost data also are
used to determine the fixed and variable costs for the opti-
mization model. However, the measure of effectiveness in the
optimization model is ability to remove the particular commodity
of interest. Also, it is desired to depict the unit's actual
capability as accurately as possible so it is preferred to use
the annual operating efficiency rather than total efficiency.
13-11
-------
TABLE 13-2
COST ANALYSIS OF CONTROL METHODS
THIS KEPJrtT CJ STAINS A COST ANALYSIS OF THE FOLLOWING CONTROL
CCNThCL CONTROL IDENTIFICATION TOTAL
NUM3ER • EFF.
l-l 'XJJ.O* GUARANTEED PRECIP. AOO TO EXIST. 90% PRECIP. ON GRND,• 99.0
Tt-E FGLLJWINo ^ESULTS ARE PHSENTED
2£C CA,->ilAL COSTS
2.ITL;MIZcJ Ol^tCT OPERATING COSTS
3.lTEMI2cJ "IJF/XL ANNCAL COSTS FOR RATE OF RETURN BEFORE TAXES = 10%
4.TOTAL AMNUAt- COST FOR RATES OF RETURN FROM 0% TO 20%
-------
w
TABLE 13-2 (continued)
A SSUMPTICNS
A. INDIRECT CJSfo = 20X OF blREC T CA pTf A^L C OSTs
G . T AXES AND I >l oJ ,« A NClf S~~2 %"TF~ToT"AL"~ CAP~I TAL COST
C .ADM I N I S Ti-J A f I \t^. CO STS = s¥ oF TOTAL" CAPITAL" COST
C. SER VICE LlHd = 10 YEARS ~"
i. i"r'dM Tzlo""cM'lTAir<;"csTs :
CAPITAL C~dsf(S)
COST ITEM
' 1 .PUKCHAScU fcGL IP JldiMF' K35I200.0 212840. 0 297O50_.0 370b70.0
• 2 . c.Q (j 1PM t'N T tiH EC T I C N • 79t78^6V6 1^0700.0 ~2d"790lf. ~6"~" 26 T 050 . 0
«5 .tiCU IP.FfJUNOATIO^ i, Ju D. • 6HOOO.O 81000.0 88000.0 108000.0
•4.HRUCESS !, INST. PlPi.MG' 39000.0 67000.0^ 93OOO.O 117000.0
«£,FCWt£P iVIHING G L £ Grl f i N C • 12000.0 1250O.O 13300.0 15000.0
•6.TOTAL DIKcCT CAfJlTAi_ C GST ' 333880. 0 524040~.o" 6O9250.0 871720.0
•7.TCIAL CAPITAL CJjT* _ _^0vi_65b.y_ 628847.9 839099.8 _J04b063.8
-------
j . tr.
TABLE..1.3-^.(cQnt1nuedL..
TOTAL ANNUAL COST FfJR RATE OF
TOTAL ANNUAL CCST($1YR)
COST ITEM
•1.Dinner CPdR/ST I^<3 CJjf'
•2.TAXcS & INSURANCd1
• 3.ACM INI STRATI ye GJ oIo•
' 4 . C EPREC IAT IJ N •""
•E.TCTAL ANNUAL CJST'
* 1OOQOOCFM***200000CFM***300000CFM***400000CFM**
I M I 0 . 0 t 6???' 0 22730_.0 , 29 760 . 0
3013.1 12577.0 " 167Q2.'0 2:0921^3"
£0032.8 _ 31442.4 41955.0 5_2JOJ! .2
10 250 2.2 I 36773.3 170500.4
163411.5 218290.2 273492.8
65306.9
104762.8
4 . FU T A L ANNUA L C C5T P ORI H AT(ES__ OF RETURN
0% TO 20 %
RtiLATI QNSHIP
U)
I
TCTAL ANNUAL COST = DIRECT OPtRATlNG COST •«- TAXES £. INSURANCE +
_ ___ ^'IJNISTHATJ^ve CjfJSJ f CAP I T A L C O ST » ( XI ( 1 . + X
"" "c (i .+xT)**'xN-T. >
XI= RATE CF RETURN
XN= SERVICE LIFE IN YEARS
** ICOOOUCr V#****200000CFM*
RATE OF TOTAL ANNUAL TOTAL ANNUAL
RETURN COST(SirR) COST($lYR)
•
*
•
•
•
•
' •
•
*
•
02
04
06
Oil
1C
12
14
16
18
20
64 C JO
9Ja*a
•3y loo
1 046uJ
1 103aj
1 28 60 7
1 3o02 I
. 9
. 5
. 1
C
. 4
. 9
. e
. 0
. €
.4
1
I
1
60909
30918
38440
46350
1 £4626
163251
1
1
72205
81468
191 018
20C837
2
IOS03
.3
.3
.6
. 1
.2
.7
.4
.2
.6
. 3
. 8
#4**300OOOCF
M*****400000CFM*
TOTAL ANNUAL
COST(*IYR )
81516.
174933.
134970
195524
206567
218076
230024
242384
255 I 27
268229
281661
»
•
«
•
•
.
•
.
*
9
1
4
3
6
9
3
0
6
1
3
TOTAL ANNUAL
COST ( $1YK)
102984
219441
231954
2451 I 1
258878
273227
288121
303529
319416
335749
352494
.4
.7
.7
.a
.8
.0
.1
.4
.2
. 1
.4
-------
It is assumed that the desired percent removal at a
given source will be in the range of the available
control equipment and that any percent removal can
be utilized within that range; e.g., a 97.8 percent
precipitator. Consequently, it is possible to aggre-
gate those control methods which differ only in the
percent removal into an equivalent single control with
a fixed cost and a variable cost as a function of the
quantity removed.
13.3.2 OPTIMIZATION MODEL
The objective of the mathematical programming model is to
determine, for any specified pulp mill, the optimal way
to satisfy the specified standards. This constrained
optimization technique is comprised of an objective
function and a set of constraints. The interested reader
is referred to texts on mathematical programming for a
more detailed description (1_, 2).
A literature review was made to determine whether suitable
mathematical models had been developed by others. Teller
(3_) reports the use of linear programming to examine the
costs of alternative air pollution abatement policies in
an urban area. Norsworthy (£), and Burton and Sanjour (5)
have also presented the results of their analyses of urban
air pollution problems. Correspondence with NCASI and
NAPCA personnel did not uncover any specific references to
emissions control modeling in the pulping industry. D. H.
Moreau (6_) has devised a nonlinear programming model for
water pollution control in an unbleached kraft mill. Based
on the unavailability of directly relevant models it
appeared that it would be best to devise a new model for
analyzing emission control in the pulp industry.
It was felt that the model should be able to analyze
simultaneously multiple emission sources of one or
more commodities. Performance standards can be formulated
either on a source-by-source basis (equiproportional
abatement) or by specifying an allowable level of emissions
from all sources (selective abatement). Also, provision
needs to be made for analyzing the trade-offs that exist
between the removal of a specified pollutant(s) and the
generation and/or removal of other pollutants.
The components of the mathematical programming model are
described below in algebraic form. The notation is
presented in Table 13-3. Following presentation of the
entire model, procedures for decomposing the model will
be discussed.
13-15
-------
TABLE 13-3
NOTATION FOR OPTIMIZATION MODEL
Symbol Definition
y. . interger variable associated with entering the k commodity
into the j control at the i source, y. . = o,l .
iD
x quantity of commodity k entering the 1 removal range
in the j control at the i source .
c unit cost of routing commodity k into 1 removal range
J_-L +.-U
in the j control at the i source.
z. . quantity of commodity k going from the j control at the
i source to the atmosphere, o.
z. . quantity of commodity k leaving j control at the i
source.
a. quantity of commodity k produced at the i source per
unit of pulp tonnage.
a. allowable quantity of commodity k which can be emitted
at the i source per unit of pulp tonnage.
(k 'k)
p , . .. quantity of another commodity , ' k , produced or removed
1 (k1)
per unit of x. .,
(k)
p. . price per ton of commodity k recovered from the
j control at the i source.
(k)
f . . fixed cost for routing commodity k to control j
at source i.
- (k)
Y . . , upper bound on percent removal of commodity k in the
1 removal range of the j control at the i source.
13-16
-------
13.3.2.1 Continuity From Source to Control
I y.. = 1.0 for i = 1,
= D
Eq. 13.2
Equation 13.2 denotes that a control is used at
each of the i sources.
Equation 13.3 denotes that the emissions from a
(k)
mill producing B tons of pulp per day, a, B,
(k)
go to either one of the controls, x. . , or are
(k)
emitted to the atmosphere, z.. . It is possible
that a given control for commodity k may introduce,
or remove another commodity k , so that the
(k'k) (k1) . . , . , ,
p. ... x. „ term is included.
(kk) *!*;> + i x.(kwk) = a.(k) B
13! 13! 130 i
for i = 1, • • • • ,p
Jv ™ ^ f « * • * / U
Eq. 13.3
13.3.2.2 Continuity From Control to Recovery
It is convenient to determine the total amount of
(k)
recovered chemicals, z.. , which is the sum of
commodity flows to the various controls, or
- xfki + Z(k) = 0
1=1 ^1 13
for i = !,• "',p; j = l,"",q; k = !,••••,u
Eq. 13.4
13-17
-------
13.3.2.3 Performance Standards
a. Equiproportional Abatement
for i = l,"",p; k = l,---«,u
Eq. 13.5
b. Selective Abatement
for k = !,••••,u
Eq. 13.6
13.3.2.4 Control Bounds
A given removal range can control only a specified
(k) y~ (k)
amount of a given commodity a. JH ? B' at a
given unit cost. This bound is expressed in constraint
13.7.
for i = !,•••«,p; j = l,"--,q;
1 = !,••••,t; k = !,«•••,u
Eq. 13.7
13-18
-------
13.3.2.5 Implicit Integer Constraints
I£ the fixed charge is included, then we require
(k)
that y,.^ = 0 or 1. Thus, if a given control
is selected, then the full fixed charge is assessed.
In a linear programming format, this restriction
can be written as
0 y . 1.0
for i = !,••••,p; j = l,"'«,q;
k = !,'•••,u
Eq. 13.8
i and the usual optimization procedure is modified so
fkl
i that y..v is either 0 or 1.
13
13.3.2.6 Nonnegativity Restrictions
Lastly, we require that all of the variables be non-
negative .
(k) (k) (k) >
X. ., , 2. . , Z. . =0
I]! 130 1]
for all i, j, k, 1
Eq. 13.9
13-19
-------
13.3.2.7 Decomposing The Problem
The problem is set up so that it can handle many of the
complexities arising in actual cases. However, it is
sometimes possible to divide the single large problem
into smaller independent sub-problems under specified
conditions. These possible simplifications are outlined
below.
13.3.2.7.1 No Commodity Interdependencies
If each commodity is emitted and/or controlled independent
of the presence of the other commodities, then an optimal
control strategy can be determined for each commodity
independently. Mathematically, this means that
(k'k)
p = 0 for all k in Eg. 13.3.
13.3.2.7.2 Equiproportional Abatement Formulation
If equiproportional abatement type of performance standards
are employed, then an optimal control program can be
specified for each source independent of the other sources.
13.3.2.8 objective Function
The objective is to maximize the net revenue from
emission control. Negative revenues indicate a positive
control cost. The objective function is
Max.z= I I I p ,<*>. -III fW yOO - f ? • V ? c"0 x<*>
i-i j=i k-i 1:I ^ i£i 3£i kii v Yij >! >! ^ ^ ciji x
Eq. 13.10
The first term on the right hand side represents the gross
revenue from recovered chemicals. The middle term is
the fixed cost and last term is the variable costs.
13-20
-------
13.3.3 ANALYSIS OF COST IMPACT
There is some level of particulate control which is
sought voluntarily by the industry because the value
of recovered chemical offsets the cost of collection.
This is not the case, however, when consideration is
given to control of emissions of H S, organic sulfur
compounds, or SO . There are no directly measurable
savings which accrue as a result of controlling these
emissions. It must be concluded, therefore, that
virtually all costs incurred in reducing other than
particulate emissions should be looked upon as direct
costs of pollution control.
The cost impact analysis is made of a mill of specified
size, technology, and yield. Availability of control
devices depends on the technology under consideration.
The analysis of cost impact includes consideration of
the value of recovered chemicals and existing control
equipment. Performance standards must be specified for
each indicated constituent either at each source or as
an allowable emission from all sources.
It was decided to analyze high and low yield mills pro-
ducing 300 tons/day, 500 tons/day, and 1000 tons/day
of pulp. It is assumed that the pulp industry will select
the most effective strategy for emission control. If
there are no recovered chemicals, then the problem can be
reduced to minimizing the cost of meeting a. specified
standard. If chemicals can be recovered then the cost of
emission control to the industry will be estimated by find-
ing the change in net expenditures attributable to satis-
fying the emission standards.
Using the multi-path flow diagrams, it is possible to make
an analysis of any single source or combination of sources
which exist in kraft mills. Thus, an estimate for a single
plant can be made by selecting the applicable subset of
sources from the multi-path flow diagram.
13-21
-------
13.3.3.1 Assumed Performance Standards
The model is designed so that the optimal solution
can be specified for various numerical values of
performance standards (see Section 13."4.2) . In order
to obtain a cost estimate for an existing set of
standards, the state of Oregon standards have been
utilized in this analysis. It should not be concluded,
however, that these standards are "typical" or "repre-
sentative" of practices in other states. They are used
in this study only to provide one estimate of emission
control costs. The relevant excerpt from these standards
is presented below (7).
"EMISSION LIMITATIONS. The following emission limits are
based upon average daily emissions.
(1) Emission of TRS.
(a) The emission of TRS from a recovery furnace stack
shall not exceed 2 pounds of sulfur per ton of equivalent
air-dried kraft pulp or 70 ppm expressed as H S on a dry
gas basis, whichever is the more restrictive.
(b) No later than July 1, 1975, the emission of TRS from
the recovery furnace stack shall not exceed 0.5 pound of
sulfur per ton of equivalent air-dried kraft pulp or 17.5
ppm, expressed as H S on a dry gas basis, whichever is the
more restrictive, or such other limit of TRS that proves to
be reasonably attainable utilizing the latest in design of
recovery furnace equipment, controls and procedures.
(c) No later than July 1, 1972, the emission of noncon-
densibles from digesters and multiple effect evaporators
shall be treated to reduce the emission of TRS equal to the
reduction achieved by thermal oxidation in a lime kiln.
(2) Emission of Particulate Matter.
(a) No later than July 1, 1975, the emissions of particulate
matter from the recovery furnace stack shall not exceed 4
pounds per ton of equivalent air-dried kraft pulp.
(b) No later than July 1, 1975, the emission of particulate
matter from lime kilns shall not exceed 1 pound per ton of
equivalent air-dried kraft pulp.
(c) No later than July 1, 1972, the emission of particulate
matter from the smelt tank shall not exceed 1/2 pound per
ton of equivalent air-dried kraft pulp."
13-22
-------
It is seen that the standards can be classified as
equiproportional, so that from the point of view of
the standards, each source is independent.
Using the Oregon standards as a data source, the
allowable particulate emission from source 7 in a
kraft mill is calculated as follows:
B = 500 tons of pulp/day,
4 Ibs. of par
pulp, so that
4(500)/2000 =
particulates/day.
a. = a_ =4 Ibs. of particulates/ton of
a? (B) = 4(500)/2000 = 1.0 tons of
13.3.3.2 Assumed Emissions
(k)
The assumed unit emissions (a. ) for a 300, 500, and
1000 ton/day pulp mill were obtained from Table 13-1.
It is desired to calculate a • 'B, the right hand side
of Eq. 13.3. Sample calculations are shown below.
B = 500 tons of pulp/day,
a.' = a_ = 140 Ibs. of particulates/ton of
pulp, so that
140(500)/2000
particulates/day.
a_(1)B = 140(500)/2000 = 35.0 tons of
13.3.3.3 Control Bounds
It is necessary to know how much a given control can
remove at a specified source and what the'unit removal
costs are. The upper bound on the. actual removal
• _ /vy • '
capability, Y^ai' was estimated.using.the annual.operating
efficiency estimates from Chapter 5. For precipitators,
five removal ranges (expressed as percentages) were con-
sideredj 0-89.5, 89.5 - 94.5, 94.5 - 98.5, 98.5 - 99.0,
and 99.0 - 99.5. Thus
13-23
-------
= *945 " '
- (k) = - (1)
Yij3 Y713 = .985 - .945 = 0.04
-7 = -990 - -985 = °-005
714
= -995 - .990 = 0.005
- (k)
The control bounds for each removal range, a. (B) y. •-, /
then be calculated. From the previous section,
a_ B = 35.0. Thus, the control bounds for a precipitator at
source 7 can be calculated as follows:
(1) (a?(1)B) = 0.895(35) = 31.25 tons of part. /day.
(1) ( " } =0.05 (35) = 1.75 tons of part. /day.
Y713(1) ( " ) = 0.04 (35) = 1.40 tons of part. /day.
(1) ( " ) = 0.005 (35) = 0.175 tons of part. /day.
Y715(1) ( " ) = 0.005 (35) = 0.175 tons of part. /day.
13.3.3.4 Unit Control Cost Analysis - Case I
The Case I cost analysis is applicable for either:
1. A new mill making its initial investment
decision in control equipment; or
2. An existing mill which is replacing obso-
lete equipment. This obsolescence, however,
did not result from emission limitations
imposed by control agencies .
13-24
-------
The fixed cost of a precipitator at source 7, and at
all other sources, can be obtained using the procedure
described in Section 13.3.1. Knowing the variable
costs of emission control over a specified range of
control and the amount of emissions which can be removed,
(k)
the variable costs, c , ., can be determined.
A sample calculation for a Case I investment is presented
im.fcable ;13r*4.
This cost analysis would not be appropriate for
examining an existing mill which is required to
make an additional investment in control equipment
due to the imposition of emission standards. The
latter situation may be viewed as causing premature
obsolescence of existing equipment. It is not
possible to generalize about the present value of
this existing equipment for all mills without a
detailed study on a mill by mill basis.
13.3.3.5 Unit Control Cost Analysis - Case II
The emission standards would have a relatively severe
cost impact on a mill which has just recently installed
control equipment without cognizance of impending
emission standards which might necessitate modifying
or replacing this relatively new equipment. This case
(II) will be analyzed as the other limiting condition
to consider so that the range of cost impact for any
mill (existing or planned) might be determined.
13.3.3.5.1 Add-On Particulate Controls at Recovery Boiler
If a mill has an existing control device in operation,
the costs and revenues from this investment are
historical or sunk expenditures; i.e., will not be
affected by the decision to add-on additional equip-
ment. What is affected most significantly is the
particulate removal which can be achieved by this
add-on equipment.
13-25
-------
TABLE 13-4
SAMPLE CALCULATION OF INCREMENTAL COSTS FOR
PRECIPITATORS - CASE I ANALYSIS
(i = 0.10)
SOURCE 7 of a 500 ADT/DAY MILL
(1) (2)
Removal Total Incremental
Range: Cost
% $/Day
(3)
(4)
(5)
Particulates Unit Incremental Symbol
Removed: Cost/Ton
Tons/Day $/Ton =
Col.(2) 4
Col.(3)
0-89.5
89.5-94.5
94.5-98.5
98.5-99.0
99.0-99.5
$366.00
49.70
73.80
35.80
86.80
31.25
1.75
1.40
0.175
0.175
$11.70
28.40
52.80
205.00
495.00
'711
'712
'713
(1)
(1)
I
(1)
»
(1)
'714
(1
'715
13-26
-------
For the sample analysis shown in Table 13-4 the
decision-maker decides to recover between 0 and
99.5 percent of the 35 tons of chemicals. However,
given that he has an existing 90 percent precipitator
(with an assumed AOE of 89.5 percent) the decision-
maker must decide how much to recover of the remaining
3.675 tons of chemicals that leave the existing 90
percent precipitator. The corresponding sample
calculations for this situation are shown in Table 13-5.
TABLE 13-5
SAMPLE CALCULATIONS OF INCREMENTAL C^STS FOP. ADDITIONAL
PRECIPITATOR - CASE II ANALYSIS
(i = 0.10)
SOURCE 7 OF A 500 ADT/DAY MILL
(1)
(2)
(3)
(4)
Removal Range
For Additional
Particulates
0
89.5
94.5
98.5
99.0
%
-89.5
- 94.5
- 98.5
- 99.0
- 99.5
Total Additional Unit Incremental
Incremental Particulates Cost/Ton =
Cost Removed Col. (2) *Col.(:
$/Day
$366.00
49.70
73.80
35.80
86.80
Tons /Day
3.28
0.184
0.147
0.018
0.018
$ 112.00
270.00
502.00
1990.00
4820.00
Comparison of Tables 13-4 and 13-5 reveals that the
total incremental costs stay the same. However, the
amount of particulates removed by the add-on precipitator
in each removal range is nearly an order of magnitude
less. Correspondingly, the unit incremental removal
cost/ton increases significantly. Thus for this con-
figuration it is apparent that a single larger precipitator
is more economical than two smaller units in series.
For example, the average unit incremental costs in the
89.5 - 98.5 percent range are about $39/ton for a single
larger unit as compared to adding an additional 89.5
percent unit at a unit cost of $112/ton for a similar
removal range.
13-27
-------
If a decision is made to replace an existing control
then the operating costs associated with this control
fall to zero. The unamortized capital costs, however,
continue at their same level for the remainder of the
amortization period. Thus the problem in this case
is to determine the net expenditure required to replace
the existing control with an acceptable alternative.
13.3.3.6 Value of Recovered Chemicals
The value of recovered chemicals varies from mill to
mill depending on local conditions. For this analysis
a value of $30/ton has been selected as a realistic
estimate for the recovery boiler and smelt tank. A
value of $15/ton has been used for the lime kiln. The
effect of varying these assumed values will be evaluated
later in this chapter.
13.3.3.7 Results of Analysis of Particulate Emissions for Case I.
This section describes the results from applying the
mathematical model to analyzing particulate emissions.
The multipath flow diagram for particulates indicates
particulate emissions from the following sources:
[6, 7, 11, 12, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26].
However, the particulate emissions from the slake tank
are unknown so that it will not be possible to analyze
this source (No. 22). Results from analysis of each of
the other sources is presented below.
Detailed analysis of the problem revealed that it is
possible to decompose this single large optimization
problem into equivalent sub-problems. While commodity
interrelationships are felt to exist in the pulp industry,
no one was able to quantify this interrelationship so
(k 'k)
that p.. .. =0 for all k in Eq. 13.3. The Oregon
standards may be classed in the equiproportional abatement
category so that each source can be analyzed independently
13-28
-------
of other sources. With the problem decomposed in
this manner, the problem of analyzing the integer
variables may be resolved by explicit enumeration
of the remaining alternatives.
In the absence of performance standards, the industry
is assumed to be making a straightforward investment
decision of choosing the optimal control and removal
efficiency. Given the answers to this problem, the
performance standard is added as an additional con-
straint, and its impact is thereby evaluated.
Lastly, to examine the case of existing mills with
usable control equipment, the above analysis can
be repeated with the additional constraint that the
cost of upgrading or replacing this equipment be
included in the analysis. Such an analysis will
be made later for an existing mill.
The results of the cost impact studies for the recovery
boiler sources are shown in Table 13-6. For source
6 of a 500 ton/day mill, the results indicate that the
performance standard reduces net revenues from $333/day
to $315.40. Thus, the reduction in net revenue
attributable to satisfying the performance standard
is $17.60/day. The low yield source (No. 7) derives
larger net revenues than the high yield source (No. 6).
However, the reduction in net revenue from satisfying
the emission standard at source 7 is also seen to be
greater than for source 6 for this mill size. Thus
for sources 6, 7, 11, and 12, it appears that emission
control equipment is an attractive investment and that
the selected standards do not have a significant impact
on the investment decision. Case I removal in the
90 percent range was selected for the smaller mill
sizes while 95 -percent was selected for the 1000-ton
mill size. No significant economies or diseconomies
of scale were evident.
13-29
-------
TABLE 13-6
ANALYSIS OF PARTICULATE EMISSIONS FROM RECOVERY BOILERS
co
CJ
o
Source
6 or 11
7 or 12
15 or 17
16 or 18
20
Mill
Size
Tons/Day
300
500
1000
300
500
1000
300
500
1000
300
500
1000
300
500
1000
Air Flow
1000 CFM
58
97
194
88
146
292
52.5
87.5
175
79
131
262
84
139
278
CASE I
(1 = 0.10)
Particulates
Tons/Day
13.9
23.2
46.5
21.0
35.0
70.0
4.5
7.5
15.0
6.8
11.3
22.5
31.5
52.5
105.0
Optimal
Revenue ;
W/O Stds.
148.00
333.00
815.00
290.00
571.00
1301.00
0
0
0
0
0
56.80
582.00
1075.00
2320.00
Soln:Net
: $/Day
W. Stds.
125.50
315.40
796.50
263.30
547.00
1245.00
-89.00
-66.20
-23.60
-96.20
-68.00
- 9.20
564.00
1056.00
2285.00
Cost of Meeting
Stds . $/Day
22.50
17.60
18.50
26.70
24.00
56.00
89.00
66.20
23.60
96.20
68.00
66.00
18.00
19.00
35.00
-------
The analysis of source 15 (and equivalent source 17) and
source 16 (and equivalent source 18) indicates that there
is a positive cost of meeting the standards for all mill
sizes. A removal efficiency in the range of 90 percent,
based solely on optimum economic considerations with a
gross return on investment of 10 percent, was found for
these sources. A small positive cost of meeting the
standards was found for source 20. A removal efficiency
in the range of 95 percent, based solely on optimum economic
considerations with a gross return on investment of 10 per-
cent, was observed for this source.
The results for the smelt tank (source 21) indicate a net
cost incurred to satisfy the performance standards as
shown in Table 13-7. Without the standard, the mesh pad
offers an economically attractive but low removal efficiency
alternative so that a positive net revenue results. Im-
position of the standard necessitates the use of a different
control with a higher unit cost so that a positive net cost
results. A removal efficiency in the range of about 75
percent was observed for this source based solely on optimum
economic considerations with a gross return on investment of
10 percent.
A similar analysis of the lime kiln selected indicated a removal
efficiency of about 99 percent of the particulates so that the
standard of constraint is not binding. Particulate emission
control at lime kilns appears to be an attractive investment
based on this Case I analysis.
13.3.4 LIMITATIONS OF THE MODEL
The optimization model provides the best solution to the
problem for the assumed set of conditions. The results would
be more accurate if the input emission data, cost data, et
cetera, are calculated for a specific plant. This study has
focused on the behavior of hypothetical pulp mills in the
United States. The intent of the study is to provide an analysis,
based on the best available data, of the expenditures for emission
control in this industry. The results of analyses for such
hypothetical mills are not to be considered applicable to any
specific pulping operation in this country.
Improvements in this concept will undoubtedly be possible with
further study and experience gained with collection and process-
ing of data. This may warrant changes in the preceding formu-
lations and models or constraints.
13-31
-------
TABLE 13-7
ANALYSIS OF PARTICULATE EMISSIONS
FROM SMELT TANK (#21) and LIME KILN (#23-126)
23 or 25
U)
I
U>
24 or 26
Mill
Size
Tons/Day
300
500
1000
300
500
1000
300
500
1000
Air Plow
1000 CPM
9.4
15.6
31.2
6.5
10.9
21.8
8.5
14.2
28.4
CASE I
(i = 0.10)
Particulates
Tons /Day
0.6
1.0
2.0
5.85
9.75
19.50
7.65
12.75
25.5
Optimal
Revenue :
W/0 Stds.
2.60
10.20
31.60
66.00
120.00
251.00
92.00
166.00
321.00
SolniNet
$/Day
W. Stds
-19.40
-14.00
- 7.00
66.00
120.00
251.00
92.00
166.00
321.00
Cost of Meeting
Standards
$/Day
22.00
24.20
38.60
0
0
0
0
0
0
-------
13.4 ASSIGNMENT OF PARTICULATE CONTROL COSTS (PROCESS OR
EMISSION CONTROL) - CASE I
An evaluation of the impact of performance standards
on particulate emission control decisions was presented
in the previous section for a single set of standards
and a single value of recovered chemicals. It is often
desired to evaluate the effect on the optimal solution
of changes in some of the original assumptions. Sensi-
. tivity analysis is a post-optimal procedure which permits
examination of the response of the optimal solution to
changes in the assumed conditions. Control of SO and
total organics takes place only when required by the
performance standards. Consequently, the total expenditure
is chargeable to satisfying the performance standards.
However, the cost of particulate control can often be
reduced significantly because of the value of the
recovered chemicals. Thus the following post-optimal
analyses for the particulate sources will be presented
for Case I. The other case of an existing mill
adding on additional control devices in response to
new performance standards is not considered here.
; 1. For each source, how high must the value of the
• recovered chemicals be in order to justify emission
control solely for chemical recovery?
2. For each source, at what value of recovered chemicals
would the optimal emission control not be employed in
the absence of the performance standard for each
source?
3. For each source, what is the effect of changing
performance standards?
4. For each source, what is the effect of using
a rate of return (before taxes) of 20 percent
instead of 10 percent.
13.4.1 EFFECT OF VALUE OF RECOVERED CHEMICALS - Case I
This section examines the value of recovered chemicals
needed to justify particulate removals greater than
would be required by the performance standard. Thus, if
13-33
-------
the performance standard constraint was initially
binding, there is some higher value of recovered
chemicals at which the constraint would not be
binding and the decision-maker would rationally
remove more particulates than he is required by
the standard.
The second item examined in this section is the effect
of decreasing the value of recovered chemicals to the
point that a rational decision-maker would elect not
to use the control he originally selected.
The results of this analysis are presented in Table
13-8. For 500 ton per day pulp mills, it is seen
that emission control for chemical recovery only
can be justified for recovery boilers if the value
of chemicals is in the $40 to $240 range. The required
value for the smelt tank is $46 while the required
value for lime kilns is only $7 to $10. It is also
apparent that the optimal control (at some lower percent
removal) would be selected for recovery boilers in
500 ton/day mills if the unit value of chemicals
is in the $8 to $40 range.
NO sensitivity analysis was made of the other case
where additional particulate controls at an existing
mill must be added to satisfy a newly imposed standard.
13.4.2 EFFECT OF VARYING PERFORMANCE STANDARDS-CASE I
This section analyzes the impact of changing particulate
performance standards on the optimal solution. Insights
can be gained by examining the total cost function
over the feasible removal range. This analysis was
performed for each source. For the controls examined,
the marginal cost (as a function of quantity of
particulates removed) increases in the higher removal
range. Thus, removal of the last units of particulates
is the most expensive for a given control. Another
factor which increases costs is when a change in
13-34
-------
TABLE 13-8
EFFECT OF VALUE OF RECOVERED CHEMICALS
ON PARTICULATE CONTROLS
Source
6
7
11
12
15
16
17
18
20
21
23
24
CASE I ANALYSIS
(i=0.10)
Value of Recovered Chem. To Value of Recovered Chem. To
Justify Process Control Justify Using Any Optimal
Beyond Standards : $/Ton Control : $/Ton
300 T/D
$ 55.00
52.50
55.00
52.50
52.80
269.00
1
52.80
269.00
247.00
67.00
12.60
9.60
500 T/D
$ 52.70
52.80
52.70
52.80
40.20
240.00
40.20
240.00
204.00
46.00
9.50
7.20
1000 T/D
$ 53.30
55.30
53.30
55.30
30.80
194.00
30.80
194.00
170.00
34.00
7.00
5.30
300 T/D
$ 18.10
14.50
18.10
14.50
52.80
37.80
52.80
37.80
9.40
67.00
12.60
9.60
500 T/D
$ 13.90
11.80
13.90
11.80
40.20
30.40
40.20
30.40
7.60
46.00
9.50
7.20
1000 T/D
$ 10.70
9.65
10.70
9.65
30.80
24.90
30.80
24.90
6.10
34.00
7.00
5.30
13-35
-------
the selected control must be made because the previously
selected control has reached its maximum removal
capability. Both of those factors will be analyzed.
The analysis of the control cost function for recovery
boiler sources is shown in Table 13-9. The results are
presented for the entire range over which controls are
feasible. For source 7, control 1 can be employed in
the 0-89.5 percent range; control 1 alone, or 1 and 2,
or 1 and 6 in the 89.5-98.5 percent range; and only control 1
in the 98.5 to 99.5 percent range. The next column
shows the least cost control to select. Examination
of the variable cost, in $/ton, indicates the cost
functions are convex and that the marginal cost of
particulate removals in the upper ranges is relatively
high. For source 7, the marginal costs are $28.40/ton
in the 89.5 to 94.5 percent range whereas they rise
to almost $500/ton in the 99.0-99.5 percent range.
Analysis of the lime kiln and the smelt tank indicates high
marginal cost for lime kilns above 99 percent removal,
and increasing costs due to changing controls for the
smelt tank as shown in Table 13-10.
13-36
-------
TABLE 13-9
ANALYSIS OF COST FUNCTION FOR VARYING PERCENT REMOVALS
FOR RECOVERY BOILERS IN 500 TON/DAY MILL
Performance
Standard
Proportion
Source Removed (AOE)
6 or 11 0-.895
.895-. 945
.945-. 985
.985-. 990
.990-995
7 or 12 0-.895
.895-. 945
.945-. 985
.985-. 990
.990-. 995
Feasible
Control
Numbers
1
1
1&2
1&6
1
1&2
1&6
1
1
1
1
1S2
1&6
1
1&2
1&6
1
1
CASE I
(i = 0.10)
Selected Fixed
Control Cost
Number $/Day
1 256.00
1
1
1
1
1 329.00
1
1
1
1
Variable
Cost
$/Ton
1.50
38.50
52.70
336.00
472.00
1.18
28.40
52.80
205.00
483.00
Addnl .
Particulates Fixed
Removed Cost
Tons $/Day
20.8
1.16
.93
.116
.116
31.3
1.75
1.4
.175
.175
Total
Cost
$/Day
287.00
332.00
381.00
420.00
475.00
366.00
416.00
490.00
526.00
611.00
-------
T A R L E 13-9 (continued)
f— 1
U)
1
to
00
15 or 17 0-.895
.895-. 985
.985-. 990
.990-. 994
16 or 18 0-.895
.895-. 985
.985-. 990
.990-. 994
20 0-.895
.895-. 945
.945-. 985
.985-. 990
.990-. 995
1
1&6
1&6
7
1&6
7
1
1&6
1&6
7
1&6
7
1
1
1S2
1&6
1
1&2
1&6
1
1
1
1&6
1&6
1&6
1
1&6
1&6
1&6
1
1
1
1
1
241.00 4.32
258.00
264.00
867.00
306.00 7.10
238.00
268.00
1130.00
318.00 0.76
18.70
34.20
134.00
333.00
6.72
.675
.038
.030
10.1
1.02
.056
.045
47.0
2.62
2.10
.26
.26
270.00
444.00
454.00
480.00
378.00
620.00
635.00
686.00
354.00
403.00
475.00
510.00
596.00
-------
TABLE 13-10
ANALYSIS OF COST FUNCTION FOR VARY IMP. PERCENT REMOVALS
FOR SMELT TANK AND LIME KILN IN 500 TON/DAY MILL
CASE I
(i - 0.10)
H
U)
1
CJ
ID
Performance
Standard
Proportion
Source Removed (AOE)
21 0 - .75
.75- .90
.90- .97
23 or 25 0 - .99
.99- .999
24 or 26 0 - .99
.99- .999
Feasible
Control
Numbers
6,8,9
6,8
6
6
6
6
6
Selected Fixed
Control Cost
Number $/Day
9 9.00
8
6
6 24.00
6
6 24.00
6
Variable
Cost
$/Ton
4.00
10.00
26.00
7.00
860.00
5.40
656.00
Addnl.
Particulates Fixed
Removed Cost
Tons $/Day
.75
.15 27.50
.07 12.50
9.65
.01
12.60
.013
Total
Cost
$/Day
12.00
41.00
55.00
91.00
100.00
92.00
100.00
-------
13.4.3 EFFECT OF USING HIGHER RATE OF RETURN
This section analyzes the impact of using a 20 percent
instead of a 10 percent rate of return. These are
gross rates of return and do not include deductions for
taxes. The 10 percent rate of return was used in this
study in order to be compatible with previous in-
dustrial studies of NAPCA. The 20 percent rate of
return is an estimate by pulping industry represen-
tatives of their minimum required rate of return.
This analysis will be done for the particulate control
devices in 500 TPD mills and the results will be
compared with the 10 percent rate of return analysis.
The results of this analysis are shown in Table 13-11.
The use of a higher rate of return will necessarily
decrease the amount of surplus revenue relative to
that rate of return. This effect is shown by comparing
columns two and five. The use of a higher rate of return
had the expected result of significantly reducing net
revenues. The cost of: satisfying the standards increased
significantly. Also, cost increases significantly or
accordingly, as in Table 13-11.
13.5 TRENDS IN FUTURE CAPITAL EXPENDITURES
Looking to the future the pulping industry is faced
with two parallel problems in meeting emission standards.
One problem is that of upgrading existing facilities;
the other is to assure compliance of new mills or mill
expansions which must be built to satisfy the increasing
demand for wood pulp.
The following sections present example emission control
cost calculations for a 500 TPD new mill and an identical
size existing mill.
13-40
-------
TABLE 13-11
EFFECT OF RATE OF RETURN ON OPTIMAL SOLUTION
FOR CASE I ANALYSIS OF
PARTICULATE CONTROLS: 500 TPD MILL
Source
or 11
or 12
or 17
dr 18
20
21
or 25
or 26
i = 0.10
Optimal Solution
Net Revenue :$/Day
..W/p.Stds
333.00
571.00
0
0
1075 1; 00
10^0
120.00
166.00
Cost Of
Meeting Stds.
$/Day
4 W. Stds.
315.40
547.00
-66 . 20
-68.00
1056.00
-14.00
120.00
166 .00
17.60
24.00
66.20
68.00
19.00
24.20
0
0
i
= 0.20
Optimal Solution
Net Revenue : $/Day
W/O Stds.
255.00
465.00
0
0
520.00
7.30
33.80
80.00
W. Stds
220.90
418.30
-142.00
-166.00
411.00
-23.30
33.80
80.00
Cost Of
Meeting Stds
34.10
46.70
142.00
166.00
109.00
30.60
0
0
13-41
-------
13.5.1 EXAMPLE CALCULATIONS FOR NEW MILL
This section shows an example for a new 500 TPD
mill with the following configuration:
Continuous digestion
High or low yield
High solids evaporation
Incineration in lime kiln
The controls employed should be sufficient to meet
1975 Oregon standards. Referring to the multi-path
flow diagram, this example mill has the following
set of sources [1, 4, 19, 20, 21, 22, 25, 26]. Analysis
of particulates, H S, SO , and organic sulfur compounds
is shown below. The analysis of power boilers is not
included in this study. Emission control at that source
is a total cost since no revenues are derived from
recovered chemicals.
13.5.1.1 Particulate Controls - New Mill
The sources of particulates for this configuration are
obtained from Figure 13-2, the multi-path flow diagram,
and comprise the following subset of sources [20, 21, 22,
25, 26]. From Table 13-6, the cost of meeting the :standards
is obtained and is presented below.
TABLE 13-12
PARTICULATE EMISSION CONTROL COST ANALYSIS-NEH 500 TPD MILL
Source Cost of
Meeting Stds. $/Day
20
21
22
25 or '
26
$19.00
24.20
_*
0
0
Daily Cost of Meeting Standards
High Yield $43.20
Low Yield 43.20
*No unit particulate emission could be estimated. It
appears that net revenue would be about zero so analysis
will be done using this assumption.
13-42
-------
13.5,1.2 H^S and Organic Sulfur Compounds - New Mills
The sources of these emissions are shown in Figure 13-3
and are the subset II, 4, 21, 25, 26]. Using the fact
that the standards specify treatment equivalent to in-
cineration in a lime kiln, the control cost is $37.20/
day, for H S and organic sulfur compounds.
13.5.1.3 SO2 Control - New Mills
The sources of SO emissions are shown in Figure 13-4
and are the subset [4, 25, 26]. The multi-path dia-
gram indicates no known SO controls so that the con-
trol cost is zero.
13.5.2 EXAMPLE CALCULATIONS FOR AN EXISTING MILL
This section shows an example for an existing 500 TPD
mill with the following configuration:
Batch digestion
High or low yield
Direct contact evaporation
No incineration in lime kiln
No black liquor oxidation
The controls employed should be sufficient to meet
1975 Oregon standards. Referring to Figure 13-1, this
example has the following set of sources [1, 2, 3, 5,
6, 7, 21, 22, 23, 24]. Analysis of particulates, H S,
SO , and organic sulfur compounds is shown below.
This analysis provides an estimate of the initial cost
impact of emission standards on such mills. However,
this impact is not permanent. It represents a measure
of the cost of prematurely replacing existing equipment.
The analysis of power boilers is not included in this
study. Emission control at that source is a total cost
since no revenues are derived from recovered chemicals.
13-43
-------
13.5.2.1 Particulate Controls - Existing Mill
The sources of particulates for this configuration
are obtained from Figure 13-2 and comprise the
following subset of sources [6, 7, 21, 22, 23, 24].
It is assumed that the mill has the following con-
trol equipment already in use.
1. 90 percent precipitator at sources 6, 7
2. Mesh pad at source 21
3. 80 percent scrubber at sources 23, 24
This equipment is assumed to have useful service
life remaining and credits will be given accordingly.
The least cost way to upgrade to meet the standards
will be selected. For sources 6 and 7, an 80 per-
cent cyclonic scrubber can be added to satisfy
standards. For source 21, the mesh pad will be re-
placed by a packed tower scrubber. For sources 23
and 24, the 80 percent scrubber will be replaced by
a 99 percent venturi scrubber. The results of this
analysis for each applicable source of particulates
are shown in Table 13-13. It is apparent that
particulate emission standards exert a strong impact
on costs for existing mills which must upgrade to
satisfy new standards. It is not possible to know
directly what net revenues were without the standards
for this case. Thus, the cost of meeting the stand-
ard is not known. For example, though a positive net
revenue is shown for sources 23 and 24, it cannot be
concluded that the industry would voluntarily invest
at this level because the original control level may
have yielded an even larger net revenue.
13-44
-------
13.5.2.2 H S and Organic Sulfur Compounds
The sources of these emissions are shown in Figure
13-3 and are the subset [1, 2, 3, 5, 6, 7, 21, 23,
24). In order to satisfy the standards, it is
necessary to add lime kiln incineration (at a cost
of $37,20/day) and weak black liquor oxidation (at
a cost of $264/day).
13.5.2.3 SO2 Control
The sources of SO are shown in Figure 13-4 and are
the subset [2, 3, 5, 6, 7, 23, 24]. The multi-path
diagram indicates no known SO controls so that the
control cost is zero.
13-45
-------
TABLE 13-13
PARTICIPATE EMISSION CONTROL COST ANALYSIS - EXISTING MILL
Source Net Revenue W. Stds,
$/Day
6 or - $124.00
7 - 113.00
21 23.00
22 -*
23 or 13.50
24 57.00
Total Net Revenue w. Stds.
High Yield -$133.50
Low Yield - 79.00
*No unit particulate emission could be estimated.
Assumed that net revenue was zero.
13.5.3 CONTROL EXPENDITURES AT NEW MILLS
Kraft Flow Sheet No. 10 (Chapter 3) depicts an approach to the
control of new facilities incorporating control options which
have been shown to be effective and practical. This approach
emphasizes the use of a process change to reduce emissions
from the recovery boiler, provides for lime kiln incinera-
tion of non-condensible gases, and calls for high
efficiency scrubbers to be installed on the lime kiln,
smelt tank, and slaker tank. BLO is not required because
of the process change involving the recovery boiler. The
only source uncontrolled by this scheme is the pulp
washers. Even this source might eventually be controlled
by the use of diffusion or pressure washing as described
in Chapter 6.
The single most significant innovation on Kraft Flow Sheet
No. 10 is the utilization of the new high solids evaporator
to supplant the more conventional DC evaporator or Venturi
13-46
-------
evaporator/scrubber systems. Figures 5-46 and 5-47
reflect cost data which allow for a comparison of
the total capital cost for the "new" recovery system
with the total capital cost of the conventional
recovery system. This comparison suggests that the
capital cost of the "new" system is only slightly
higher {within 10 percent) than the capital cost of
the conventional system. When the annual costs of
the two systems are compared, however, preliminary
estimate of costs for the "new" system come out lower
than those of the conventional system for a rate of
return equal to 10 percent.
It seems reasonable to conclude, therefore, that
new mills and mill expansions can be effectively con-
trolled and that the costs for using "new" recovery
systems do not differ drastically from the cost of
the more conventional designs.
The cost impact analysis presented previously sug-
gests that standards for particulate emission as
proposed by the states of Washington and Oregon for
1975 would not cause a significant departure from the
particulate control level that would be selected in
their absence (For i = 0.10). However, should the
standards become more stringent than currently en-
visioned, the analysis shows that marginal costs of
satisfying more stringent standards are significantly
higher than the anticipated value of the recovered
chemicals.
Prior analysis has shown that a proper measure of con-
trol effectiveness for H S and other organic sulfur
compounds defies description. With standards specify-
ing that treatment shall be "equivalent" to lime kiln
incineration, we reach a point where the decision is
either go or no go. There is no economic incentive to
make an investment in H S and organic sulfur control
so that the costs may be viewed as directly attributable
to pollution control.
13-47
-------
13.5.4 CONTROL EXPENDITURES AT EXISTING MILLS
Hie problem of what to do with an existing mill to
bring it into compliance with standards similar to
those promulgated in the Pacific Northwest has been
the subject of much debate during the course of this
study. While a firm consensus has not been reached,
the tenor of the debate has been that the control of
H S and other organic sulfur compounds emanating
from recovery boilers can be achieved to a_ degree
through the use of 99+ percent black liquor oxidation
or by the conversion of existing fairly modern units
to incorporate one of the new high solids evaporator
designs. It is conceivable though that for some
older recovery systems, the odorous emissions may
never be reduced to levels which are currently being
considered by regulatory authorities, even though the
most modern technology is employed. This means that
these older recovery systems may have to be scrapped
and replaced with a new system which eliminates direct
contact between the flue gas and black liquor.
The impact of standards for the H S emissions from
recovery boilers could be dramatic. Apparently,
there is a consensus that standards set for 1972 (in
Washington and Oregon) can be met by the utilization of
BLO or by conversion to one of the "new" design evaporator
systems. Standards proposed for 1975, however, might only
be met by scrapping existing process equipment and re-
placing it with a completely new system which eliminates
direct contact between the flue gas and black liquor.
If BLO can be utilized effectively, or if a conversion of
existing facilities can be successfully achieved, then
the capital costs (for a 500 TPD mill) could range from
$200,000 (for BLO) to $1.5 million (for an air contact
evaporator). If it is determined, however, that a new
recovery boiler, per se, is required, then the capital
costs could approach $8 million.
13-48
-------
13.6 REFERENCES
1. Hadley, G., Linear Programming, Addison Wesley Publishing
Company, Inc., Reading, Mass. (1963).
2. Simonnard, M., Linear Programming, Prentice Hall, Inc.,
Englewood Cliffs, N. J. (1966).
3. Teller, A., "The Use of Linear Programming to Estimate the
Cost of Some Alternative Air Pollution Abatement Policies,"
Proc. IBM Scientific Computing Symposium - Water & Air
Resource Management (1968).
4. Norsworthy, J. R. "A Computer Simulation Design for
Economic Evaluation of Alternative Air Resource Manage-
ment Policies "Proc. IBM Scientific Computing Symposium -
Water & Air Resource Management (1968).
5. Burton, E., and W. Sanjour, "Evaluating the Efficiency of
Urban Air Pollution Abatement Strategies," presented at
15th Meeting of The Institute of Management Sciences,
Cleveland, Ohio (1968).
6. Mofeau, D. H., "Mathematical Models for Industrial Waste
Disposal Systems," Harvard Water Resources Group, Harvard
University (1967).
7. Oregon State Sanitary Authority, "Rules and Regulations
for Kraft Pulp Mills," Oregon Administrative Rules,
Section 47-020, June 1969.
13-49
------- |