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

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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

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       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

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                   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

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                                                          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

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                                                         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

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                                                           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

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                                                           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

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                                                         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

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                          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

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                   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

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     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

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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

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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

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       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

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         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

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         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

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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

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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

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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

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         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

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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

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    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

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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

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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

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 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

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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

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    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

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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

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 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

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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

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 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

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    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

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       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

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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

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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
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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
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        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.
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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
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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.
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 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.
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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.
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 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
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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
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         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
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 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
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    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
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         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.
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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
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    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
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    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
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 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

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     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

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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

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 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

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         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

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 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

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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

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 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

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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

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   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

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    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
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 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.
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 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.
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         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,


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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.
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 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).


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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.
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         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.
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    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
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          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.
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  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.

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          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.
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  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


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 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

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 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

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          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

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         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

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          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

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         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

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         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

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9.5  REFERENCES


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     3.   Cederloff, R., M.  L.  Edfores, L. Friberg, T. Lindvall, Jour.APCA,
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                                     9-77

-------
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35.  Grune,  W.  N., Progress Report USPHS Research Grant #RG 7004,
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                                 9-78

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36.  McWilliam, I. G., R. A. Dewar, Nature, 181, 760-(1958).

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55.  Walther, J. E., H. R. Amberg, TAPPI, 50,  (10), 108A-(1967).

56.  Applebury, T. E., "Air Pollution Abatement by Process Gas
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                                 9-79

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 57.   Wan,  E.  I.-S.,  "Analysis of  Gaseous  Sulfur Compounds by Gas
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71.  Industrial  Gas  Cleaning Institute,  Inc., "Test Procedures for
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                                 9-80

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72.  Ibid., "Procedure for Determination of Velocity and Gas Flow
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73.  Ibid., "Criteria for Performance Guarantee Determinations,"
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75.  Blosser, R. O., H. B. H. Cooper, Jr., TAPPI, 51, (5), 73A-(1968).

76.  Washington State Department of Health, "Basic Considerations
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77.  Research Appliance Co., "Staksamplr," Allison Park, Pa., 15101.

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79.  Comacho, T. F., Southern Pulp & Paper Mfg., 30,  (6), 96-(June 10,
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80.  Cooper, S. R., C. F. Haskell, Paper Trade J., 151,  (13), 58-(1967).

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                                 9-81

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  88.   American Petroleum Institute, "Manual on Disposal of Refinery
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                                  9-82

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      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

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                          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

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                   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

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   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

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 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

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 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

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 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

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        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

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 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

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 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

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 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

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 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

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         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

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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

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         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.
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        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

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 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

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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

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 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

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 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

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 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

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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.
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 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.
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 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.
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 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.

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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

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         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

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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

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 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

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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.
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 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.
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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

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 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

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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.
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        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

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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

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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

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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.
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      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.
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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
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 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

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 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

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 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

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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

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 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

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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

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        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

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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

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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.
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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
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 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

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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.
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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
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 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.
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 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.
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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.
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 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.
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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.

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 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

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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

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 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.
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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.
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 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.
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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.
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 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
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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

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        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

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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.
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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.
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       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

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  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.
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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

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 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

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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

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 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

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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

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 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

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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

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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

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 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

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       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

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 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

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                          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

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                         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

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         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

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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

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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

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        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

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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

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        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

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        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

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         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

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        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

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 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

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                             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

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                        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

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  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

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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

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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

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               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

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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

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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

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        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

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          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

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                                                                                                                                                                                  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

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  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

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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

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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

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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

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                            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

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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

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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

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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

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