ATMOSPHERIC
EMISSIONS
FROM SULFURIC ACID
MANUFACTURING
U. S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
Environmental Health Service
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ATMOSPHERIC EMISSIONS FROM
SULFURIC ACID MANUFACTURING PROCESSES
Cooperative Study Project
Manufacturing Chemists' Association, Inc.
and
Public Health Service
U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
Environmental Health Service
National Air Pollution Control Administration
Durham, North Carolina
1965
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The AP series of reports is issued by the National Air Pollution Control
Administration to report the results of scientific and engineering
studies, and information of general interest in the field of air pollution.
Information reported in this series includes coverage of NAPCA intra-
mural activities and of cooperative studies conducted in conjunction with
state and local agencies, research institutes, and industrial organiza-
tions. Copies of AP reports maybe obtained upon request, as supplies
permit, from the Office of Technical Information and Publications,
National Air Pollution Control Administration, U. S. Department of
Health, Education, and Welfare, 1033 Wade Avenue, Raleigh, North
Carolina 27605.
Znd printing September 1970
National Air Pollution Control Administration Publication No. 999-AP-13
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CONTENTS
PREFACE vii
ACKNOWLEDGMENTS viii
USE AND LIMITATIONS OF THE REPORT 1
SUMMARY
Sulfuric Acid Production 3
Emissions From Sulfuric Acid Manufacture 3
Control of Emissions 4
Emission Guidelines 5
GROWTH OF SULFURIC ACID INDUSTRY 7
SULFURIC ACID MANUFACTURE
Raw Materials 11
Chamber Process 11
Contact Process 16
SUMMARY OF SAMPLING AND ANALYTICAL TECHNIQUES
Sulfuric Acid Mist 41
Sulfur Dioxide and Sulfur Trioxide 41
Oxides of Nitrogen 42
GLOSSARY OF TERMS 43
APPENDICES
A. Emission and Operating Data for Chamber and Contact Sulfuric
Acid Plants 49
B. Sampling and Analytical Techniques 59
C. Methods of Determining Causes of Visible Plumes From Stacks
of Contact Sulfuric Acid Plants 99
D. Sulfuric Acid Establishments in the United States 107
E. Physical Data 117
REFERENCES 125
SUBJECT INDEX 127
iii
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FIGURES
Figure 1. Simplified flow diagram of typical lead-chamber process
for sulfuric acid manufacture (based on use of elemental
sulfur as the raw material) ^
Figure 2. Gas flow diagram for typical sulfur-burning contact plant
in which air quench is used for part of converter interstage
cooling 18
Figure 3. Flow diagram for typical sulfur-burning contact plant in
which air quench is not used for converter gas cooling 19
Figure 4. Flow diagram for typical metallurgical-type contact plant
(roasting and gas-purification equipment) 22
Figure 5. Flow diagram for typical metallurgical-type contact plant
(drying, conversion, and absorption equipment) 23
Figure 6. Equilibrium conversion efficiencies at various temperatures
and gas compositions 27
Figure 7. Relationship of conversion efficiency to SO, in exit gas
(based on data in Tables A2 and A3) ' 28
Figure 8. Percent conversion of sulfur dioxide to sulfur trioxide
for plants with no air dilution (Ref. 10) 29
Figure 9. Percent conversion of sulfur dioxide to sulfur trioxide for
plants with air dilution (Ref. 11) 30
Figure 10. Sulfur dioxide emissions at various conversion efficiencies
(per ton of equivalent 100% H,SOi produced) 31
Figure Bl. Acid-mist sampling train, control panel 61
Figure B2. Acid-mist sampling train, collection compartment 62
Figure B3. Data sheet for sampling sulfuric acid mist 64
Figure B4. Typical orifice calibration curve at 70°F and 29.9 in. Hg 65
Figure B5. Apparatus for determination of moisture content of acid-
dried air or gas in contact sulfuric acid plants 80
Figure B6. Apparatus for determination of acid content of acid-dried
air or gas and exit gas in contact sulfuric acid plants 83
Figure B7. Sulfur dioxide — sulfur trioxide sampling train 86
Figure B8. Train for analysis of converter entrance gas 88
Figure B9. Portable apparatus for determination of acid mist, SO2,
and SO., 89
Figure BIO. Apparatus for integrated grab samples 92
Figure Bll. Apparatus for grab samples 95
Figure B12. Nitrogen dioxide sampling train 97
Figure El. Oleum freezing-point diagram 123
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TABLES
Table 1 — Growth of Sulfuric Acid Industry in the United States 7
Table 2 —Production of Byproduct Sulfuric Acid From Copper, Zinc,
and Lead Plants in the United States - 8
Table 3 — Capacity and Production of Sulfuric Acid in United States
by Regions
Table 4 —Emissions From Acid Drum Concentrators 34
Table 5 —Effect of Wire-Mesh Mist Eliminators on Acid-Mist Collection.. 38
Table 6 — Collection of H.,SO4 Mist From a Sulfur-Burning Contact
Sulfuric Acid Plant With Fiber Mist Eliminators 40
APPENDIX TABLES
Table Al—Emission and Operating Data for Chamber Sulfuric Acid
Plants 51
Table A2—Emission and Operating Data for Contact Sulfuric Acid
Plants without Mist Eliminators 52
Table A3—Emission and Operating Data for Contact Sulfuric Acid
Plants with Mist Eliminators 54
Table A4—Concentrations of Sulfuric Acid Mist and Spray at Various
Stack Elevations 56
Table A5—Acid Mist Collection in Absorber Stacks of Contact Sulfuric
Acid Plants 57
Table Bl—Reich Test for Sulfur Dioxide in Entrance Gas 68
Table B2—Reich Test for SO2 in Exit Gas 70
Table B3—Barometric Correction Factors for Reich Test 72
Table B4—Normal Barometer Readings for Various Altitudes 73
Table B5—Sulfur Dioxide Conversion Chart for Sulfur-Burning Plants
with No Air Quench 74
Table B6—Sulfur Dioxide Conversion Chart for Sulfur-Burning Plants
with Air Quench 78
Table Dl—Sulfuric Acid Establishments in the United States 109
Table El—Physical Data, Sulfuric Acid (0-93%) 119
Table E2—Physical Data, Sulfuric Acid (94-100%) 122
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PREFACE
To provide reliable information on the nature and quantity of emissions
to the atmosphere from chemical manufacturing, the Manufacturing Chemists'
Association, Inc. and the Division of Air Pollution, Public Health Service,
United States Department of Health, Education, and Welfare, entered into
an agreement on October 29, 1962. A cooperative program was established
to study emissions from selected chemical manufacturing processes and pub-
lish information about them in a form helpful to air pollution control and
planning agencies and to chemical industry management. Direction of these
studies is vested in an MCA-USPHS Steering Committee, presently composed
as follows:
Representing USPHS: Representing MCA:
John H. Ludwig* Willard F. Bixby*
Austin N. Heller Louis W. Roznoy
Robert Porter Clifton R. Walbridge
Andrew H. Rose, Jr. Elmer P. Wheeler
Information to be published will describe the range of emissions during
normal operating conditions and the performance of established methods and
devices employed to limit and control these emissions. Interpretation of
emission values in terms of ground-level concentrations and assessment of
potential effects produced by the emissions are both outside the scope of this
program.
This report deals with emissions from sulfuric acid manufacture, the first
study to be made under the joint program. Sulfuric acid manufacture was
chosen because it represents an important segment of the chemical manu-
facturing industry in the United States, involves plants in many parts of the
country, and has well-recognized air pollution potential (1).
*Principal representatives
vii
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ACKNOWLEDGMENTS
Many companies and individuals in the sulfuric acid industry have been
helpful in carrying forward this study, and for their contributions the project
sponsors extend sincere gratitude.
Special thanks are due the following organizations for their participation
in a program of stack sampling and analysis specifically for this study:
The American Agricultural Chemical Company
American Cyanamid Company
Chemical Construction Corporation
E. I. du Pont de Nemours & Co.
V-C Chemical Company — Division of Socony Mobil Oil Company
Several companies also provided from their records, either directly or
through the air pollution control districts of Los Angeles County and the
San Francisco Bay Area, additional stack sampling and analytical data, which
have been incorporated into the report. Other companies contributed valuable
assistance to the project. Among those are:
Allied Chemical Corporation
The American Agricultural Chemical Company
Collier Carbon and Chemical Corporation
Monsanto Company
Stauffer Chemical Company
U. S. Phosphoric Products Division, Tennessee Corporation
Stanley T. Cuffe of the Public Health Service and Carlton M. Dean of
Monsanto Company were the investigators in the study and are the principal
authors of this report. The sponsors acknowledge the contribution of Mon-
santo Company in providing the services of Mr. Dean, who assembled much
of the technical information.
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USE AND LIMITATION OF THE REPORT
This report has been prepared to provide reliable information on atmos-
pheric emissions from sulfuric acid manufacturing plants and on methods
and equipment normally employed to limit these emissions to satisfactory
levels.
Background information is included to define the importance of the
sulfuric acid industry in the United States. Basic characteristics of the indus-
try are discussed, including growth rate in recent years, types of raw materials
used, end uses for the product, and the number of producing establishments,
i.e. manufacturing sites, in existence during the past and at the present time.
Process descriptions are given for the two processes in commercial use:
the contact process and the chamber process. Process information includes
discussions of the normal process variables that affect the types and quantities
of emissions, the normal range of emissions, startup and shutdown losses, and
methods of emission control and recovery. Supplemental material provides
detailed descriptions of sampling and analytical methods.
The emission data represent results from approximately 12 percent of
the present number of establishments.* Most of these data have been gathered
from production records of sulfuric acid producers. The data also include
results from several stack-sampling programs conducted jointly during 1963
by the Manufacturing Chemists' Association and the United States Public
Health Service. One contact plant and two chamber plants were included in
this sampling program. Results obtained from these tests are consistent with
the values of the emissions reported from other sources.
The manufacture of sulfuric acid has been a basic industry in the United
States for many years, and the manufacturing procedures have become well-
established. Based on this fact and the indication that the industry growth
in recent years closely parallels the growth curve of the general economy,
it is likely that the information provided in this report will be characteristic
of the industry for at least 5 years and possibly for 10 years.
Over a long period of years, the number of contact plants has increased
while the number of chamber plants has decreased. During the mid-1940's,
the number of establishments producing sulfuric acid by the chamber process
was approximately equal to the number producing acid by the contact process.
Today more than twice as many establishments use the contact process. This
trend indicates that the contact process will continue to gain in importance
on a nationwide basis.
Emissions to the atmosphere from a sulfuric acid plant depend upon a
number of factors, such as design of the plant, skill of operation, efficiency of
the catalyst, completeness of recovery operations, and the use of special devices
to reduce emissions. As our technology progresses, we can logically expect
that improvements will make it feasible to reduce emissions from sulfuric
acid plants. A review of the industry in 5 to 10 years should indicate
"'Establishment: a works in which there may be one or more sulfuric acid
plants or units, each being a complete production entity.
USE OF THE REPORT
-------
whether the data presented in this report are still representative or should
be updated to reflect the then-prevailing conditions.
Although this report has been prepared as an industry review primarily
for public officials concerned with the control of air pollution, we expect that
the information will also be helpful to chemical plant management and
technical staffs. It may aso be helpful to engineering students, medical per-
sonnel, and other professional people interested in emissions from sulfuric
acid manufacturing plants.
USE OF THE REPORT
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SUMMARY
SULFURIC ACID PRODUCTION
In 1963 production of sulfuric acid in the United States was approxi-
mately 20,500,000 tons (2). Based on the 24.4 percent increase in production
from 1956 to 1963, the expected average growth for the next 5 years should
be 3 to 4 percent per year.
All sulfuric acid is made by either the chamber or the contact process.
The 163 contact establishments account for about 90 percent of the U. S.
production. The 60 chamber establishments account for the balance of U. S.
production. Products include 50° to 66° Be (62 to 93 percent acid), 98 to 99
percent acid and up to 100 percent oleum, i.e. 100 percent sulfur trioxode(2).
Elemental sulfur, or any sulfur-bearing material, is a potential raw
material for both chamber and contact processes. Elemental sulfur accounts
for about 75 percent of all raw materials used in sulfuric acid production.
Most of the remaining new acid comes from pyrites or other iron sulfides;
zinc, copper and lead ores; smelter gas; hydrogen sulfide; and crude sulfur.
Substantial quantities of "fresh clean acid" are made by regeneration or de-
composition of spent acid from petroleum refineries or other chemical
processes.
EMISSIONS FROM SULFURIC ACDD MANUFACTURE
Chamber Plants
The primary source of emissions in the chamber process is the final Gay
Lussac tower. Emissions include nitrogen oxides, sulfur dioxide, and sulfuric
acid mist and spray.
Concentrations of total nitrogen oxides in these exit gases range from
about 0.1 to 0.2 volume percent. Sulfur dioxide concentrations occur in the
same range. About 50 to 60 percent of the total nitrogen oxides is nitrogen
dioxide, which characterizes the exit gas by a reddish-brown color.
Combined sulfuric acid mist and spray in the exit gas varies from 5 to
30 milligrams per cubic foot. The sulfuric acid mist contains about 10 percent
dissolved nitrogen oxides. Over 90 percent of the acid mist particles are
larger than 3 microns diameter.
Contact Plants
The major source of emissions from contact sulfuric acid plants is the
exit gas from the absorber. This gas contains unreacted sulfur dioxide, sul-
furic acid spray and mist, and unabsorbed sulfur trioxide. Trace amounts
of nitrogen oxides may also be present under some conditions, e.g. use of a
raw material feed containing nitrogen compounds.
Unconverted sulfur dioxide gas, which is colorless, passes through the
absorption system and is discharged to the atmosphere. The quantity of this
gas emitted is a direct function of the degree of conversion of sulfur dioxide
to sulfur trioxide and may vary- from 0.1 to 0.5 percent by volume of the
stack gases. During startup or during some emergency shutdowns, higher
concentrations will occur.
Emissions of sulfuric acid mist and spray usually vary from 3 to 15
SUMMARY
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milligrams per standard cubic foot of gas; values ranging from as low as 1 to
as high as 50 milligrams per standard cubic foot have been observed. The
appearance of a dense white plume at the absorber exit stack indicates the
presence of a substantial number of small particles (i.e. less than 3 microns
in diameter) and does not necessarily reflect the concentration of sulfuric
acid mist present.
Unabsorbed sulfur trioxide usually constitutes a small part of the ab-
sorber exit gas. When discharged to the atmosphere it is hydrated and forms
a visible white plume of acid mist. Although the concentration of unabsorbed
sulfur trioxide can vary appreciably, from 0.5 to 48 milligrams per standard
cubic foot of gas, it is usually closer to the lower figure and is a small part
of the total acid mist emission.
Acid Concentrators
Emissions of sulfuric acid mist may originate from the operation of either
vacuum-type or drum-type concentrators of dilute acid. Significant emissions
are unlikely with the vacuum type, however.
Minor Losses
Minor amounts of sulfur oxides may be emitted to the atmosphere from
tank car and drum-loading operations, and from storage tank vents. Oxides
of nitrogen may be emitted from process acid tanks in the chamber process.
Wind may cause losses of solid sulfur or sulfide ores from storage piles.
CONTROL OF EMISSIONS
Chamber Plants
The most important factors in minimizing emissions to the atmosphere
in chamber plants are selection of raw materials, skill of operation, and
preventive maintenance. Recovery equipment following the final Gay Lussac
tower is rarely employed. In one known instance, however, water-scrubbing
the exit gases reduced the sulfur dioxide by 40 percent and the oxides of
nitrogen by 25 percent.
Contact Plants
As with chamber plants, selection of raw materials, quality of plant
design, skill of operation, and preventive maintenance are the principal
factors in the control of emissions from contact plants. When contact plants
operate at excessively high throughput rates, a substantial increase in emis-
sions may be expected.
Although processes are available for recovering 70 to 90 percent or more
of the unconverted sulfur dioxide in the stack gases, these are generally
uneconomical. Plants have used the "Cominco"® ammonia scrubbing process
for reducing the concentration of sulfur dioxide to about 0.08 percent in a
single stage and to 0.03 percent in two stages. This process removes little or
no acid mist. Economical disposal of byproduct ammonium sulfate may be
a problem.
Control devices currently used for minimizing emissions of acid mist and
spray are electrostatic precipitators and glass-fiber and wire-mesh eliminators.
Electrostatic devices are highly efficient regardless of acid-mist particle size
and are capable of reducing mist emissions by 92 to 99.9 percent.
SUMMARY
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The collection efficiencies for glass-fiber acid-mist eliminators range
from 94 to 99.99 percent. These high efficiencies can be maintained at vari-
able tail-gas flow rates in collection of acid-mist particles smaller than 3
microns in diameter.
Stainless steel wire-mesh eliminators for acid mist and spray provide
low first cost but are susceptible to corrosion by concentrated sulfuric acid.
A typical installation may show 93 percent collection efficiency for acid mist
during the production of 98 percent acid. When oleum is produced, the pro-
portion of acid-mist particles smaller than 3 microns in diameter is higher:
collection efficiency decreases sharply and may be less than 40 percent.
In some cases tall stacks, 150 feet or higher, are used to disperse exit
gases from the absorber into the atmosphere. In addition, there is some
evidence that the walls of the stacks collect large acid particles and thus
reduce the acid-spray emissions to atmosphere.
EMISSION GUIDELINES
Contact Plants
The tabulations of emission and operating data in Tables A2 and A3
show that many contact sulfuric acid plants operate at between 97 and 98
percent efficiency for conversion of sulfur dioxide. It is practical, therefore,
to design and operate new contact plants for such efficiencies. Note, how-
ever, that the concentration of sulfur dioxide in the tail gas from one plant
having a conversion efficiency of 97 percent can be higher or lower than that
from a second plant also having a 97 percent conversion efficiency. This
variation in the concentration of sulfur dioxide in tail gases is dependent upon
the concentration of sulfur dioxide in the feed gas to the converter.
The data in Table A3 show that it is possible to recover 99 percent of all
of the emissions of acid spray and mist by adding commercially available mist
eliminators. No appreciable difference in ranges of acid-mist concentrations
is apparent for different types of contact sulfuric acid plants. Whether a
plant is a sulfur-burning type, with or without air dilution, or is a metal-
lurgical or spent-acid type does not appear to affect significantly the concen-
trations of acid mist in the stack gas from an absorber.
Excessive sulfur dioxide emissions during cold startups of contact units
can be reduced appreciably by bringing the plant and catalyst to conversion
temperatures before admitting sulfur dioxide gas to the converter and by
increasing feed rate gradually.
Chamber Plants
The tabulations for two sulfur-burning plants in Table Al indicate much
lower concentrations of sulfur dioxide in the stack gases than in most contact
plants. Conversion efficiencies appear to be higher than 98 percent; how-
ever, when raw materials other than sulfur are used, conversions are lower.
Losses of acid mist and spray were as high as 33 milligrams per standard
cubic foot of stack gas. More than 90 percent of the particles were larger
than 3 microns.
While sulfur dioxide losses from chamber plants are lower than for con-
SUMMARY
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tact plants, the stack gases contain substantial amounts of nitrogen oxides,
a condition that does not exist in contact plants. Total nitrogen oxide emis-
sions from the two sulfur-burning plants tested averaged 0.14 percent, ex-
pressed as nitrogen dioxide (NO.,), of which half to two-thirds was in the
form of NO., and the balance was nitric oxide (NO).
Auxiliary equipment is rarely installed for elimination of the sulfur
dioxide and the nitrogen oxide components.
SUMMARY
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GROWTH OF SULFURIC ACID INDUSTRY
Over a long period of years, sulfuric acid production has grown at essen-
tially the same rate as the general economy. While some uses of the product
have declined, compensating new uses have been introduced. The over-all
average growth rate has been 3% to 4 percent per year since 1950. Table 1
shows growth in acid production and in number of producing establishments
for certain years since 1939.
TABLE 1. GROWTH OF SULFURIC ACID INDUSTRY IN THE
UNITED STATES (2)
Production
thousands of short tons Number of producing establishments
(Basis: 100% H.,SO4)
Year
1939
1945
1949
1951
1956
1960
1961
1962
1963H
New acid
4,795
8,687
10,727
12,389
15,737
17,085
17,058
18,433
19,614
Total acid"
4,795
9,522
11,432
13,372
16,494
17,883
17,848
19,351
20,513
Contact only
58
94
131
144
155
Chamber only
83
83
74
65
58
Both
12
10
6
5
2
Total
153
187
211
214
215
:1 Including fortified spent acid.
''Preliminary data.
Of interest is the 330 percent increase in acid production since 1939, with
only a 40 percent increase in the total number of establishments. Average
production has increased from 31,400 tons in 1939 to 95,000 tons in 1963.
Furthermore, almost all of the new plants built use the contact process.
Another significant change is the reduction in the ratio of production for
merchant sales to production for captive use. In 1939 this ratio stood at 2:1
(merchant sales: captive), whereas it is now closer to 1:1.
In recent years, 6 to 7 percent of the total production of new sulfuric
acid has been derived from copper, lead, and zinc smelter gases. This pro-
duction is summarized in Table 2.
Although figures are not available, probably larger amounts of acid than
heretofore are presently derived from recovered hydrogen sulfide formerly
flared in refinery stacks.
Another source of acid production is domestic and imported pyrites,
which are estimated to have accounted for some 1,600,000 short tons of acid
in 1962.
The importance of various regions of the country as acid-producing areas
is also changing. Table 3 illustrates this change for the period 1956 to 1963,
and compares current capacity with production.
GROWTH OF THE INDUSTRY
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TABLE 2. PRODUCTION OF BYPRODUCT SULFURIC ACID FROM
COPPER, ZINC, AND LEAD PLANTS IN THE UNITED STATES (3)
Years
Production,
thousands of short tons"
(Basis: 100
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Fertilizer 40%
Chemicals 25
Oil refining 14
Pigments 6
Iron and steel 5
Miscellaneous, including rayon and film,
metallurgical, and other than iron and steel, etc. 10
Total 100%
Table 3 also compares estimated capacity by region as of January 1, 1963,
with 1962 production. Regionally, production varied from a low of about 65
percent of capacity in the Mountain and Pacific states to a high of about 75
percent of capacity in the South.
From the standpoint of air pollution control, the number of companies
operating acid plants may be of interest. In 1961:
23 companies operated 163 establishments
51 companies operated 51 establishments
74 companies operated a total of 214 establishments
Trends of increasing production displayed in the past may be expected
to continue. Again, changes in industrial usage may change the area produc-
tion pattern. Hydrochloric acid could displace sufuric acid in new plants
for iron and steel pickling or for phosphate rock digestion, but no large
growth in these areas is expected in the immediate future.
GROWTH OF THE INDUSTRY
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SULFURIC ACID MANUFACTURE
RAW MATERIALS
Elemental sulfur, or any sulfur-bearing material, is a potential raw
material for both chamber and contact processes. Because elemental sulfur
of high purity (99.5 percent or more) is plentiful in the U.S. at a reasonable
price, it accounts for more than 70 percent of all acid production. Most of
the remaining production of new acid comes from pyrites or other iron
sulfldes: zinc, copper and lead ores; smelter gas; hydrogen sulflde; and crude
sulfur ores. Substantial quantities of "fresh clean acid" are also made by
regeneration or decomposition of spent acid from petroleum refineries or
other chemical processes.
Elemental sulfur of extremely high purity, the predominant raw material,
is obtained from two main sources. Most of it is mined by the Frasch process
on the Gulf Coasts of Louisiana, Texas, and Mexico. As mined, it contains
not more than 0.01 percent ash and 0.05 percent or less to 1.0 percent hydro-
carbons, with no free water or acid. If low in organic matter, it is called
"bright" sulfur; if high, "dark" sulfur. There is no definite dividing line
between "bright" and "dark" sulfur.
Sulfur is delivered to the customer in either molten or solid condition.
If molten, the sulfur may be as pure when delivered as when it was mined
except for possible traces of hydrogen sulfide. If solid, the sulfur will contain
more ash, water, and acid, the amount depending on the degree of exposure en
route. If the customer's storage pile is located outdoors, these impurities will
increase and may reach 0.02 percent ash and 0.003 percent acid, or more.
Nevertheless, when the sulfur is used, it usually contains at least 99.5 percent
sulfur, dry basis. Except during a rain, moisture is about 0.1 percent.
While small by comparison with Frasch-process sulfur, substantial
amounts of elemental sulfur are recovered from sour natural and refinery gas.
Whether it is delivered in molten or solid form, this sulfur is always of higher
quality than the Frasch-process sulfur before shipment because it usually
contains less than 0.05 percent hydrocarbons, no acid or moisture, and only
0.001 to 0.003 percent ash. As with the Frasch process, if this sulfur is deliv-
ered molten it may contain traces of hydrogen sulfide.
Use of elemental sulfur in molten form is rapidly increasing because of
its higher purity and possible lower transportation and handling costs. Many
plants purchase dark sulfur rather than bright, in spite of its higher hydro-
carbon content, because it costs less.
CHAMBER PROCESS (4, 5, 6)
Introduction
The chamber process now produces approximately 10 percent of sulfuric
acid in the United States and is expected to account for less in the future.
This process yields relatively weak 60° Be (77.7 percent) acid. Because this
acid is more dilute than acid from the contact process, transportation costs
per unit of H2SO4 are higher. Chamber plants in general are captive and
of low capacity. Construction and operating costs are usually higher than for
contact plants. For these reasons, the chamber process is tending to become
a very small factor in sulfuric acid production.
SULFURIC ACID MANUFACTURE
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Production of Sulfur Dioxide (SO.,) for the Process
When elemental sulfur is the raw material, it is introduced directly into
a sulfur burner, either in solid or molten form. Air from the atmosphere is
supplied to the burner, usually under suction, to produce a gas containing 8 to
12 percent sulfur dioxide at a temperature of 1400 to 1800°F.
If sulfide ores are the raw material, they are roasted, i.e., burned, in
special proprietary equipment to produce sulfur dioxide gas at an elevated
temperature. The gas often contains less sulfur dioxide than when sulfur is
used, and more dust and other impurities. Also, the gas usually varies more
in composition. Use of byproduct sulfur dioxide gas presents the same
difficulties.
Hydrogen sulfide or spent acid may be burned or decomposed to provide
sulfur dioxide gas. Such gas is relatively clean, but care must be taken that
all organic impurities are wholly burned to avoid excessive consumption of
the gaseous catalyst (nitrogen oxides).
Description of the Chamber Process
In a typical lead chamber plant, as shown in Figure 1, the hot sulfur
dioxide gas from the sulfur burner, ore roaster, or other sulfur dioxide
producing equipment flows through a Glover tower, then through several
chambers in series, and finally through one or more Gay Lussac towers, from
which the waste gas passes through a stack to the atmosphere. If the sulfur
dioxide gases are dirty, an electrostatic dust precipitator or cyclone dust
collector precedes the Glover tower.
In the Glover tower and ensuing chambers the sulfur dioxide is oxidized
in the presence of oxides of nitrogen to sulfur trioxide, which combines with
water vapor to form sulfuric acid. The chemical reactions are complex and
not yet fully understood. It is known that intermediate compounds are formed
that finally decompose to yield sulfuric acid and nitrogen oxides for reuse.
The function of the Gay Lussac towers is to recover the released nitrogen
oxides. The final tower is fed with 60° Be acid from the Glover tower, pref-
erably at no more than 100°F, and the oxides are absorbed to form nitrosyl-
sulfuric acid (SOgNH). Maximum catalyst recovery is achieved if the nitro-
gen oxides entering the tower are maintained in equimolar proportions of
nitric oxide (NO) and nitrogen dioxide (NO.,). Because the nitrogen oxides
are an important cost item, great stress is laid on maximum recovery. The
nitrosulfuric acid is recycled to the Glover tower.
The acid made in the chambers averages 50° to 54° Be (62.18 to 68.26
percent H2SO4). It is pumped to the top of the Glover tower, flows through it
countercurrently to the hot sulfur dioxide gas, and is thus concentrated to 60°
(77.67 percent). The Glover tower decomposes the nitrosylsulfuric acid
from the Gay Lussac towers and thus releases the nitrogen oxides for reuse.
In addition, the Glover tower cools the hot sulfur dioxide gas. Up to 50
percent of all of the acid produced in the plant is formed in the Glover tower.
The hot 60° Be acid from the Glover tower is cooled, part is recycled
to the Gay Lussac towers, and the rest flows to the storage as the final product.
Yields and Losses
Sulfur — In a well-operated plant using elemental sulfur as a r?w
12 SULFURIC ACID MANUFACTURE
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EXIT GAS: AIR, SO.,, ACID MIST,
NO, AND NO.,
AMMONIA AIR
i
SULFUR
AMMONIA
OXIDATION
UNIT
OXIDES OF NITROGEN
SECONDARY AIR .
n n J
MOLTEN ^fl—
\
i
-k
r
r
1
Jt^
^m
|t^-v
sA -\A - •
XXXV^
> • K
%,
?r
78% TO ACID STORAGE
TO
STACK
.17* r
SULFUR
78%
ACID
(60-BE)
60 - 70%
CHAMBER
ACID
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VITRIOL
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LUSSAC
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NITROUS
VITRIOL
SULFUR
BURNER
COMBUSTION
CHAMBER
SUPPLY
TANK
SUPPLY
TANK
PUMP
SUPPLY PUMP
TANK
Figure 1 — Simplified flow diagram of typical lead-chamber process for sulfuric acid manufac-
ture (based on use of elemental sulfur as the raw material).
-------
material, yield is usually at least 98 percent. In plants using other raw mate
rials, a yield of 96 percent is considered satisfactory. A yield of 100 percent
is practically impossible because of such factors as chemical equilibria,
absorption efficiency, and purity of raw materials.
Niter (Nitrogen Oxides) — Loss of niter, i.e., nitrogen oxides, is often
expressed in pounds of 96-percent-pure nitrate of soda used per 100 pounds
of sulfur burned. Nitrate of soda is rarely used today as a source of the
nitrogen oxides; nitric acid or ammonia, usually the latter, has taken its
place. When sulfur is burned, a minimum niter loss would be about 3 percent,
i.e., 3 pounds of 96 percent nitrate of soda per 100 pounds of sulfur burned.
In a plant operating at 98 percent yield on sulfur burned, with burner gas
containing 10 percent sulfur dioxide, and with all niter losses in the exit gas,
the assumed 3 percent niter loss would be equivalent to approximately 0.12
percent nitric oxide (NO) by volume in the exit gas.
The minimum niter losses differ for each plant depending on such factors
as rate of operation, design and altitude of the plant, raw material, and total
niter in circulation.
Acid Mist — Losses of acid mist and mechanically entrained acid spray
in the exit gas vary with the design of the Gay Lussac tower. These losses
are usually much less than 0.1 percent of the acid produced.
Other Losses — When high-purity sulfur is the raw material, other losses
are small and may consist of nitrogen oxides or sulfur dioxide gases vented
from process acid tanks and leakage from equipment. Sulfur losses occur
chiefly from windage or washage of sulfur from raw-material storage piles.
Emissions From the Chamber Process
Composition — The exit gases are composed of nitrogen, oxygen, sulfur
dioxide, nitrogen oxides, moisture, acid mist, mechanically entrained acid
spray, and sometimes carbon dioxide. The nitrogen dioxide is responsible for
the normally reddish-brown color of the exit gases. The components of
interest from an air pollution standpoint are sulfur dioxide, nitrogen oxides,
and acid mist and spray.
Range of Emissions — In sulfur-burning plants, sulfur dioxide emissions
vary normally from less than 0.1 to 0.2 percent by volume. When other raw
materials are used, emissions may be twice as high (0.2 to 0.4 percent).
Emissions of oxides of nitrogen vary usually from 0.1 to 0.2 percent or
more by volume, expressed as NO.,.
Concentrations of acid mist, composed of sulfuric acid and dissolved
nitrogen oxides, vary from 0 to about 30 milligrams per standard cubic foot
of exit gas.
Since the cooling air temperature for lead chambers is lower in winter
than in summer, all of these emissions are usually lowest in winter and
highest in summer.
Table Al presents data from two recent tests of emissions from chamber
plants.
SULFURIC ACID MANUFACTURE
-------
Operating Factors Affecting Emissions — Operation in most chamber
plants is more an art than a science. Very few control instruments are used.
Good operators do not need formal technical training but must have experi-
ence on the job.
Emission levels are most affected by the following operating factors:
Concentration of sulfur dioxide in the burner gas.
Concentration of oxygen in the exit gases.
Ratio of nitric oxide to nitrogen dioxide in the gas entering the
first Gay Lussac tower.
Maintenance of an adequate amount of niter in circulation; the
amount varies with plant design, rate of operation, and am-
bient temperature.
Temperature and concentration of acid entering the final Gay
Lussac tower.
The operator is guided in his adjustments by observations of temperature
differences and acid concentration in various parts of the system, color of the
gases, manual analyses for oxygen and sulfur dioxide, and amount of acid in
circulation.
Methods of Control — Recovery equipment is rarely employed for pollut-
ants in the exit gases from the final Gay Lussac tower. Plant 1 in Table Al
was equipped with a water scrubber after the final Gay Lussac tower. The
scrubber reduced the concentrations of sulfur dioxide by about 40 percent
and of nitrogen oxides by about 25 percent. This scrubber recirculated the
same water; the amount of purge and degree of saturation of sulfur and
nitrogen oxides in the scrubber water were unknown. The efficiency of the
scrubber in removing acid mist was not determined because of excess carry-
over of scrubber water in the stack.
Startup and Shutdown Losses — After shutdowns lasting less than 24
hours, starting up presents few problems and results in little increase in
normal emissions. Such startups rarely require as much as 6 hours to achieve
normal operation.
After shutdowns so long that acid and equipment are cold, 24 hours or
more may be required to reach normal emission levels. Higher-than-normal
emissions will occur more frequently and for longer periods than in plants
shut down for less than 24 hours. Much more time is required to achieve
normal conditions in an ore-burning plant than in a sulfur-burning plant.
Other Losses — Loss of solid sulfur by windage and washage during
unloading and from outdoor storage piles are appreciable, usually from 1 to
2 percent of the sulfur delivered. Dust settles rapidly and completely within
a short distance, however, usually within plant boundaries. When sulfur is
purchased in molten form, such losses are eliminated.
When the raw material is sulfide ore, losses similar to those from solid
sulfur may occur, but again any dust settles rapidly.
When spent acid is a raw material, or anhydrous ammonia is involved,
ammonia, acid gas, and other odors may be detected while materials are
pumped to or from tank cars or storage tanks.
SULFURIC ACID MANUFACTURE 15
-------
There is no appreciable escape of vapor from product acid storage tanks.
Because the process equipment is under suction or at very low pressure,
emissions from gas leakage are negligible.
Current and Future Air Pollution Potential
Since the total tonnage of acid made by the chamber process is small
and the individual plants are also relatively small, the emissions from these
plants represent a low air pollution potential in the United States.
Concentrations of sulfur dioxide in the exit gases are lower in the average
chamber plant than in the average contact plant. Exit gases in the chamber
plant contain as much or more nitrogen oxides as sulfur dioxide, while stack
gases in the contact plant contain essentially no nitrogen oxides. The presence
of nitrogen oxide constituents may be readily detected by their highly visible
color.
The future air pollution potential of the chamber process is even lower
because use of this process is diminishing.
CONTACT PROCESS (6, 7)
Introduction
There are a number of different types of contact plants, even among
those designed by any one of several competitive vendors. The various types
of plants are often referred to by the name of the vendor, i.e., the builder
or designer. They include Chemical Construction Company (Chemico®),
Leonard-Monsanto, and Titlestad. A few sulfuric acid manufacturers also
design and build their own plants.
Contact plants may also be classified according to the raw materials used;
e.g., high-purity sulfur, low-purity sulfur, ores and smelter gas, spent and
sludge acids, and hydrogen sulfide.
The sulfur-burning plants are sometimes called hot-gas purification plants
or more rarely raw-gas units. Contact plants that utilize sulfide ores or crude
ores are often called metallurgical or cold-gas purification acid plants. If
designed primarily for conversion of spent acid to fresh clean acid, they may
be called spray-burning or regeneration plants. In this type of plant, the
spent acid is sprayed like oil into the combustion chamber. Plants burning
hydrogen sulfide may be of the hot-gas purification type or of the true wet-
gas type. In the true wet-gas type, sulfur dioxide gas is not dried and the
moisture is allowed to pass through the conversion system.
The term sludge plant applies specifically to plants that process acid
sludge whose acidity is too low for use in a spray-burning or regeneration
process. Although several processes have been developed for using such
sludge acid, only one or two plants are known to employ these processes.
Plants using high-purity sulfur account for about 75 percent of all
domestic sulfuric acid production.
Production of Sulfur Dioxide Gas for the Process
If elemental sulfur is the raw material, it is introduced in solid or
molten form, usually molten, into a sulfur burner, which may be operated
16 SULFURIC ACID MANUFACTURE
-------
under suction or pressure, usually the latter. Combustion air from the
atmosphere, usually predried and often preheated, is supplied to the burner
in such proportion as to produce a substantially clean gas containing 8 to
11 percent sulfur dioxide by volume. The gas leaves the burner at tempera-
tures from 1400 to more than 2000°F, depending on the amount of preheat
in the air and on the concentration of sulfur dioxide. At higher temperatures,
traces of nitrogen oxides may be present.
If hydrogen sulflde or spent acid is the raw material, it is burned in a
combustion chamber similar to the typical burner for molten sulfur. In
some instances an auxiliary fuel is required. Usually the exit gas from the
combustion chamber contains from 7 to 14 percent sulfur dioxide by volume,
the balance being chiefly nitrogen, oxygen, and water vapor. Impurities may
consist of dust, carbon dioxide, nitrogen oxides, sulfur trioxide, and unburned
hydrocarbons. Temperatures vary from 1400 to more than 2000°F.
Many types of equipment are in use for desulfurizing ores and other
sulfur-bearing materials, and produce sulfur dioxide at concentrations from
3 to 14 percent by volume. The balance is nitrogen and oxygen. The gas is
usually contaminated with widely varying amounts of dust, metallic fumes,
water vapor, and gaseous impurities. These contaminants must be removed
in the gas-cooling and purification system. The temperature of the process
gas stream to the gas-cooling and purification system may vary from 500
to 1500°F.
Description of the Contact Process
Elemental Sulfur-Burning Plants — Frasch-process or recovered sulfur
from oil refineries is melted, settled, or filtered to remove ash, and is pumped
continuously into a combustion chamber. The combustion chamber is usually
called a sulfur burner or furnace. If the sulfur is received molten, all filtra-
tion and most of the settling operation are usually omitted.
As shown in Figure 2, combustion air is usually taken directly from the
atmosphere into a blower and discharged to a drying tower with 93 to 99
percent sulfuric acid as a drying agent. The dry air containing about 3
milligrams water per cubic foot goes directly into the sulfur burner. In some
plants, the drying tower is located at the suction side of the blower (see
Figure 3).
Plants of this type operate at pressures of 2 to 6 psig, depending on
design, rate of operation, and cleanliness of equipment. The pressure gradu-
ally decreases as the gas passes through the plant until it is substantially
atmospheric at the exit stack.
The gas leaving the combustion chamber contains 8 to 11 percent sulfur
dioxide by volume. Any hydrocarbons in the sulfur are burned to carbon
dioxide and water. The gases from the combustion chamber are cooled in a
waste heat boiler to about 760 to 840 °F. Part of the cooling may be achieved
by injecting cold, dry air into the gas stream. The sulfur dioxide gas from the
boiler may be passed through a "hot-gas filter" to remove dust.
The cooled sulfur dioxide gas then enters the solid catalyst converter.
The specific inlet gas temperature is dependent upon the quantity and quality
of the catalyst and the composition and flow rate of the sulfur dioxide gas.
SULFURIC ACID MANUFACTURE 17
-------
CO
d
93
!•*
o
>
o
5
AIR INTAKE
SILENCER
OR FILTER
EXIT GAS: AIR, SO,, SOJP AND
H,SO, ACID MIST
BLOWER
(When four-pass
Figure 2 -
DRYING '—MOLTEN SULFUR WASTE HEAT
TOWER BOILER
converter is used, cooling after both second and third passes is done by air quench.)
- Gas flow diagram for typical sulfur-burning contact plant in which air quench is used for part of converter interstage cooling.
o
H
d
93
W
-------
CO
d
d
8
o
3
9
d
AIR BLOWER
AND TURBINE
EXIT GAS: AIR, SO.,, SO., AND H,SO4 ACID MIST
AIR
FILTER
93% DRYING 93% ACID
TOWER PUMP TANK
PRODUCT
COOLERS
98% ACID 98% ACID 98% ABSORPTION
COOLERS PUMP TANK TOWER
93% OR 98% ACID TO STORAGE
ECONOMIZER
Figure 3 — Flow diagram for typical sulfur-burning contact plant in which air quench is not used for converter gas cooling.
-------
The catalyst is usually placed in several horizontal trays or beds in series.
Gas cooling is provided between the various stages or passes. There may be
one or more catalyst layers in each pass. Converters usually incorporate two,
three, or four stages, rarely more than four. In general, the greater the num-
ber of catalyst stages, the higher the conversion efficiency of sulfur dioxide
to sulfur trioxide. Conversely, the leaner the gas, the fewer the passes re-
quired. As shown in Tables A2 and A3, usually from 95 to 98 percent of the
sulfur dioxide is converted to sulfur trioxide, with an accompanying large
evolution of heat. Maximum conversion cannot be obtained if temperatures
in any stage become too high. Therefore, various types of gas coolers are
employed between converter stages. Gas cooling may be affected by waste
heat boilers, steam superheaters, or tubular heat exchangers. Cooling may
also be accomplished by injecting cold, dry air (see Figure 2).
The concentration of sulfur trioxide leaving the converter is approxi-
mately the same as that of the entering sulfur dioxide. The concentration of
sulfur trioxide is lower, however, if interstage cooling has been effected by
injecting cold air (called air quench or air dilution). The converter discharge
gas is normally within a temperature range of 800 to 850°F. In addition to
the usual 8 to 11 percent sulfur trioxide, the exit gas contains oxygen, nitro-
gen, unconverted sulfur dioxide, and traces of moisture and carbon dioxide.
The moisture results from incomplete drying of combustion air or from
burning of hydrocarbons in the sulfur. Trace amounts of carbon dioxide are
also introduced from the hydrocarbon combustion.
The converter exit gas is cooled to between 450 and 500°F in an econo-
mizer supplementing a boiler feedwater heater or a tubular heat exchanger,
which may simultaneously preheat the combustion air to the sulfur burner.
Further cooling may take place in tubular heat exchangers or in the gas
duct before the gas enters the absorber. The extent of cooling depends largely
on plant design and whether or not oleum is to be produced. The cooled gas
stream enters the absorption tower, where the sulfur trioxide is absorbed
countercurrently in a circulating stream of 98 to 99 percent sulfuric acid.
The sulfur trioxide combines with the water in the acid and forms more
sulfuric acid. In the absorption tower, the sulfur trioxide is normally ab-
sorbed with an efficiency of substantially 100 percent. Any unabsorbed sulfur
trioxide passes to atmosphere. In some plants the absorber is equipped with
a mist eliminator for removal of acid mist and spray in the exit gas stream.
If oleum is produced, the sulfur trioxide passes through an oleum tower
before going to the 98 percent absorption tower. The oleum is fed with acid
from the 98 percent absorption system. The sulfur trioxide gas is cooled to
a much lower temperature before entering the oleum tower than would occur
if only 98 percent acid were to be produced. The oleum tower is unable to
absorb all of the sulfur trioxide. Therefore the effluent gas from the oleum
tower is passed through the 98 percent absorber for recovery of residual sulfur
trioxide.
The recirculating acid in the 98 percent absorber and the oleum tower, or
towers, if operating, increases in temperature as a result of (1) sensible heat
from the sulfur trioxide stream, (2) exothermic heat from the reaction of
sulfur trioxide and water, and (3) heat of solution of sulfur trioxide in oleum.
Thus, many acid coolers are required to keep the acid at the desired tempera-
ture for efficient absorption of sulfur trioxide. Acid usually enters the 98
20
SULFURIC ACID MANUFACTURE
-------
percent absorption tower between 150 and 190°F and at a concentration of
98.6 to 99 percent. The exact temperature and concentration are those that
result in the lowest visibility for the exit gases.
The drying tower, which removes moisture from the combustion air, is
supplied with acid from the 98 percent absorber and is similar in construc-
tion. The recirculating acid in the drying tower is maintained within a range
of 93.2 percent (66° Be) to 99 percent. The acid must be cooled because of
the heat evolved by dilution of the acid with moisture from the combustion
air. The increased volume of acid in the drying tower resulting from this
dilution is returned to the 98 percent absorber or pumped to storage.
A few contact plants, regardless of raw material used, produce 100 per-
cent sulfur trioxide vapor or liquid as part of their product. This product is
most easily made, however, in sulfur-burning units. The 100 percent sulfur
trioxide is frequently used to fortify lower concentrations of oleum to the
65 percent grade. Oleum concentrations stronger than approximately 40 per-
cent cannot be made in contact plants without auxiliary equipment to produce
100 percent sulfur trioxide.
Only one plant in the United States presently operates with crude sulfur
ores (15 to 25 percent S) as the raw material. It is identical to plants using
sulfide ores.
Sulflde Ores and Smelter Gas Plants — The metallurgical-type contact
plant is more elaborate and expensive than the sulfur-burning plant. It may
cost 3 times as much as the sulfur-burning plant, with lower yields and
higher operating costs. When the price of sulfide ore or smelter gas is low
compared to sulfur, however, sulfuric acid may be produced at a lower cost.
These metallurgical plants account for about 15 percent of total sulfuric
acid production in the United States.
Sulfur dioxide gas from smelters is available from such equipment as
copper converters, reverberatory furnaces, roasters, and flash smelters. The
sulfur dioxide concentrations and temperatures of these gases are often highly
variable. When pyrites or zinc concentrates are the raw material, they are
roasted in special furnaces or roasters with undried atmospheric air. The
effluent gas stream usually contains 7 to 14 percent sulfur dioxide and rarely
exceeds 1400°F. Sintering machines, which are used infrequently, produce a
gas that seldom contains more than 6 percent sulfur dioxide.
The sulfur dioxide is contaminated with dust, acid mist, and gaseous
impurities, which must be removed if high-quality acid is to be produced.
To remove the impurities, along with excessive amounts of water vapor, the
gases must be cooled to essentially atmospheric temperature. Purification
equipment consists of cyclone dust collectors, electrostatic dust and mist pre-
cipitators, and scrubbing and gas-cooling towers in various combinations as
shown in Figure 4.
After the gases are adequately cleaned and the excess water vapor
removed, they are countercurrently scrubbed with 66° Be acid in a drying
tower. The sulfuric acid removes substantially all of the remaining water
vapor before the gases pass to the blower (see Figure 5). Since the plant is
under suction up to this point, no gas leakage can occur.
SULFURIC ACID MANUFACTURE 21
-------
o>
d
d
o
o
5
O
H
d
TO ELECTROSTATIC MIST PRECIPITATOR
(SEE FIGURE 5)
STEAM
SULFIDE ORE
FEED
COMBUSTION
ROASTER
(FLUIDIZING
TYPE SHOWN)
FLUIDIZED BED
r
I
SO., GAS
CYCLONE
DUST
COLLECTOR
BLOWER
CALCINED ORE TO COOLER
AND TO STORAGE
COOLING WATER
WEAK IMPURE ACID
TO STORAGE
PUMP
SO2 gas shown as dotted lines. Cyclone dust collector may be replaced or supplemented byelectrostatic dust precipitator.
Figure 4 — Flow diagram for typical metallurgical-type contact plant {roasting and gas purification equipment).
-------
en
I
d
91
z
d
•n
EXIT GAS: AIR, SO,, SO.,, AND
H.,S04 ACID MIST
TO STACK
DRYING TOWER
FROM COOLING
TOWER
SAFETY
SEAL
EXCHANGERS
See Fig. 4 for roasters and equipment ahead of mist precipitator.
Figure 5 — Flow diagram for typical metallurgical type contact plant (drying, conversion, and absorption equipment).
-------
Beginning with the drying tower, the ore and smelter gas plants are very
similar to sulfur-burning plants, but these units usually have no sulfur-
burning facilities, waste heat boilers, superheaters, or economizers after the
boiler. The only waste heat boiler, if any, is located after the sulfur dioxide
producing equipment to provide initial cooling of the hot, dirty gases.
The cool, clean sulfur dioxide gas stream is heated to about 800°F before
it enters the converter. The heat is supplied in tubular heat exchangers by
passing the cold sulfur dioxide gas stream countercurrent to the hot sulfur
trioxide gas from the catalyst converters. The sulfur trioxide gas is thereby
cooled to a suitable temperature for absorption in the final absorber tower.
Spent-Acid and Hydrogen Sulfide Burning Plants — Plants that burn
spent acid and hydrogen sulfide are similar to plants processing ores and
smelter gas but are simpler and less expensive. However, plants for spent
acid are more expensive than sulfur-burning units.
Spent acid and/or hydrogen sulfide are introduced into the combustion
chamber and burned with undried atmospheric air. If only spent acid is
burned, auxiliary fuel may be required. A common procedure for spent-acid
plants is to burn simultaneously hydrogen sulfide, spent alkylation acid, and
sulfur. The effluent combustion gas rarely contains more than 14 percent
sulfur dioxide, but temperatures may be as high as 2400°F. Spent-acid
plants produce higher concentrations of nitrogen oxides and carbon dioxide
in the sulfur dioxide gas stream than are encountered in contact plants using
high-purity sulfur.
Two types of plants are used. In one the sulfur dioxide and other com-
bustion products are passed through gas-cooling and mist-removal equipment
before entering the drying tower. Gas cooling is effected by a waste heat
boiler followed by various types of gas coolers. Mist removal is accomplished
usually by electrostatic precipitators. Concentrated sulfuric acid removes
moisture from the sulfur dioxide and air stream passing through the drying
tower. A blower draws the gas from the drying tower and discharges the
sulfur dioxide gas to the sulfur trioxide converter. The balance of this process
is essentially the same as that in the previously discussed ore-roasting process.
In a few "wet-gas plants" the above-described process is much simplified.
The wet gases from the combustion chamber and waste heat boiler are
charged directly to the converter with no intermediate treatment. The gas
from the converter then flows to the absorber, through which 60 to 66° Be
sulfuric acid is circulating. In this type of plant, the absorber is not highly
efficient because the sulfur trioxide is in the form of sulfuric acid mist be-
cause of the excessive moisture content of the gases. Highly efficient mist
recovery equipment after the absorber is essential. Wet gas plants are used
primarily for hydrogen sulfide or hydrogen sulfide plus elemental sulfur.
Catalysts — Catalysts of the vanadium pentoxide type are used almost
exclusively in contact plants throughout the United States. Catalyst contain-
ing platinum is seldom used because of its susceptibility to poisoning by trace
amounts of foreign elements. The vanadium catalysts consist mainly of
vanadium pentoxide along with various promoters deposited usually on a
highly porous siliceous carrier. The catalyst may be in extruded, pelleted, or
tableted form. The individual pellets are usually cylinders of about i/4- to
J/2-inch diameter. The pellets may also be similar in shape to aspirin tablets
24 SULFURIC ACID MANUFACTURE
-------
A vanadium pentoxide catalyst, if well treated, has an indefinitely long
life, with no appreciable drop in activity. In practice, the sulfur dioxide gas
stream is seldom completely clean and operating temperatures may occasion-
ally rise too high. These factors can result in a slight reduction of catalyst
activity. The first catalyst stage is normally the only one in which the activity
of the catalyst is appreciably affected.
The normal impurities carried into the catalyst are dust from the raw
materials,, scale from converter equipment, and iron sulfate resulting from
corrosion of equipment ahead of the catalyst. Although the impurities do not
initially affect activity of the catalyst appreciably, the voids around the
catalyst become filled, with a resulting increase in pressure drop. Many
sulfur-burning plants rescreen the top or first layer of catalyst each year to
reduce the pressure drop. In metallurgical plants the necessity for rescreen-
ing occurs less often. Most sulfur-burning plants schedule an annual shut-
down for boiler inspection, during which time all accumulated maintenance
work, including catalyst rescreening, is completed.
The catalyst in the first stage gradually loses activity as the catalyst
pores become partially filled with dust. Not all of the dust can be removed
by rescreening. When the catalyst activity has decreased enough to affect
the over-all yield appreciably, part of the first stage catalyst is normally
replaced with new catalyst. The expense for replacement of affected catalyst
is not a serious item over a period of years.
Emissions From the Contact Process
Composition — The major source of emissions from contact sulfuric acid
plants is waste gas from the absorber exit stack. The discharge gas to atmos-
phere contains predominantly nitrogen and oxygen but also contains unre-
acted sulfur dioxide, unabsorbed sulfur trioxide, and sulfuric acid mist and
spray. When the waste gas reaches the atmosphere, sulfur trioxide is con-
verted to acid mist. Trace amounts of nitrogen oxides may also be present,
e.g., when a feed containing nitrogenous matter is used. Minor additional
quantities of sulfur dioxide and sulfur trioxide may come from storage tank
vents, from tank truck and tank car vents during loading operations, from
sulfuric acid concentrators, and from leaks in process equipment.
Loss of Unconverted Sulfur Dioxide — The major emission from a contact
plant is sulfur dioxide from the absorber exit stack. Sulfur dioxide in the
stack gas results from the incomplete conversion of sulfur dioxide to sulfur
trioxide in the catalyst converter. Conversion efficiency of 98.0 to 98.5
percent is attainable with proper plant design. Higher conversion efficiencies
require a more expensive plant and result in higher production costs.
Most contact plants are purchased from vendors who normally guarantee
a conversion efficiency of 96 to 98 percent. Guarantees of lower or higher
efficiencies are infrequent today. Although the guarantees are usually based
on plant operation at not more than rated capacity, the vendor often builds
in extra capacity to insure his guaranteed conversion efficiency. Thus, some
plants may operate at capacities appreciably greater than rated capacity and
still meet the vendor's guaranteed conversion efficiency.
In Germany a contact plant process has been offered recently that claims
to reduce the concentration of SO2 in the gases leaving the converter system
to 0.03 percent sulfur dioxide(S). The process consists of the addition to the
SULFURIC ACID MANUFACTURE 25
-------
system of a sulfur trioxide absorbing tower just ahead of the final stage of
conversion. Removal of sulfur trioxide at this point results in a reported
over-all conversion efficiency of 99.7 percent. It is claimed that plants utiliz-
ing this design can be built for approximately the same investment as plants
of commercial design in Germany and that production costs are also equal.
Information is not available at this time with which to compare investment
and operating costs in this country.
In many existing sulfur-burning contact plants or in any newly designed
sulfur-burning contact plants it is possible to reduce sulfur dioxide in the
exit gas to 0.1 percent by operating with very dilute gas. Operation in this
manner increases acid manufacturing costs.
Figure 6 shows the equilibrium efficiencies at various temperatures with
commonly used gas compositions derived from burning elemental sulfur (9).
The values in Figure 6 do not apply to other gas compositions, such as would
be obtained from other raw materials. The "percent SO2" is the volume com-
position entering the converter except for plants of the air dilution type.
In such plants the "percent SO2" is the "equivalent percent SO2", i.e. the
percent sulfur dioxide that would have entered the converter if all air dilu-
tion had taken place ahead of the converter rather than at various points in it.
The test data in Tables A2 and A3 show an efficiency range of 95.6 to
98.5 percent conversion of sulfur dioxide to sulfur trioxide. The mean con-
version efficiency for the 31 tests at typical contact plants is 97.3 percent. It
should be noted that the conversion efficiency figure usually includes any loss
of sulfur dioxide absorbed in the drying tower, i.e. in plants where the drying
tower dries wet sulfur dioxide rather than air. This occurs because of the
usual location of sampling points when determining conversion efficiency.
The unconverted sulfur dioxide from the catalyst converter passes through
the absorption system and is discharged to the atmosphere. Tables A2 and
A3 show that sulfur dioxide concentrations in the absorber discharge stack
gas range from 0.13 to 0.54 percent. The mean for the 33 tests is 0.26 percent
sulfur dioxide.
Figure 7 shows the percent conversion of sulfur dioxide to sulfur trioxide
versus percent sulfur dioxide in exit gas for all plants listed in Tables A2
and A3. Reduction of sulfur dioxide in the exit gas is seen as a direct function
of increased sulfur dioxide conversion. The conversion efficiency and the
concentrations of sulfur dioxide in the exit gas also depend upon the con-
centration of sulfur dioxide and oxygen in the gas entering the converter.
Figure 8 shows the relationship for sulfur burning plants in which no air
quench is used (10). Figure 9 applies to sulfur burning plants of air dilution
type and shows the conversion corresponding to the sulfur dioxide and oxygen
content of the exit gas (11). In this case, no test is required for the gas enter-
ing the conversion system. Figure 10 shows sulfur dioxide emissions for
various conversion efficiencies for sulfur dioxide.
Stack Gas Losses of Acid Mist and Spray — Acid-mist content of gas
leaving the absorber is shown in Tables A2 and A3. Data collected in 33 tests
show that acid-mist and spray content varied from 1.1 to 48.8 milligrams per
standard cubic foot of stack gas. The average of these values is 12.9 milli-
grams; (one value from a "wet gas" plant burning hydrogen sulfide is omitted
from this average because it concerns an unusual process that is not com-
parable with the operations of other plants included in the tabulation)
26 SULFURIC ACID MANUFACTURE
-------
on
d
CONVERSION TEMPERATURE. 'C
390 400 410 420 430 440 450 460 470 480 490 500 510 520 530 540 550 560 570 580 590 600 610 620 630 640
K
O
H
d
X
a
I I I I I I
I I I I I I I I I I
410 420 430 440
460 470 480 490 500 510 520
EXAMPLE
For a concentration of 9% SO-
and a converter temperature of
460 °C, the conversion efficiency
at equilibrium is 97%.
Figure 6 — Equilibrium conversion efficiencies at various temperatures and gas compositions.
-------
S0a IN EXIT GAS, ^
Figure 7 — Relationship of conversion effikency to SO= in exit gas (based on data in Tables A2
and A3).
Auxiliary recovery equipment will reduce the content of acid mist and
spray in the absorber gas as shown in Table A3. In 14 tests conducted in
10 plants under various conditions, the acid-mist and spray content of the
absorber gas was reduced to values ranging from 0.18 to 23.4 milligrams per
cubic foot, with an average at 3.7 milligrams. Stack impingement may reduce
the acid content of the gases even more before they are exhausted to the
atmosphere.
Table A3 illustrates the effectiveness of three different types of mist and
spray recovery equipment, including electrostatic precipitators glass-fiber
filters, and wire-mesh filters. When designed lor high performance, glass-
nber eliminators and electrostatic precipitators show a high degree of recov-
ery. Two tests with alloy, wire-mesh eliminators (plants 2A and 2B Table
A3) show good recovery when the acid is present predominantly as particles'
larger than 3 rmcrons diameter, but substantially lower recovery when the
proportion of small particles is greater.
Internal spray eliminators (spray catchers) are installed in the top sec-
n° the ^t1? abST°rberS to aid in the re™val <* ^rge acid particles entrained
m the exit gas. In most cases, the spray eliminators do an effective iob of
removing entrained acid spray and part of the mist. e"ectlve job of
Spray and mist may also be formed in the exit stack when gas coolins
°
,
that was in the gas leaving the absorber.
9Cld
mist
28
SULFURIC AMD MANUFACTURE
-------
Stack Gas Losses of Unabsorbed Sulfur Trioxide — Unabsorbed sulfur
trioxide is discharged to the atmosphere from the absorber exit stack. The
sulfur trioxide in the exit gas is hydrated to sulfuric acid from contacting
atmospheric moisture and forms a visible white plume of acid mist.
Because the sampling and analytical techniques for sulfur trioxide are
more complex than for sulfur dioxide and sulfuric acid mist, test data for
Unabsorbed sulfur trioxide are more limited. The test results for sulfur tri-
oxide may be slightly low because of the possibility of partial absorption of
sulfur trioxide in the acid-mist filter of the sample train. The test results for
plant 5A, Table A3, show the same concentration of sulfur trioxide, 1 to 2
milligrams per cubic foot, entering and leaving the glass-fiber mist eliminator.
The amount of sulfur trioxide absorption in an acid-mist filter would not,
therefore, appear to be appreciable.
The reported values for unabsorbed sulfur trioxide vary from less than
0.5 milligram per cubic foot for plant 19 to 48 milligrams per cubic foot for
plant 16, Table A2. On the basis of sulfur trioxide conversion to acid mist in
the atmosphere, the 48 milligrams per cubic foot would account for 85 percent
of the total acid-mist emission for plant 16, Table A2. Likewise, the less
than 0.5 milligram per cubic foot would be equivalent to less than 7 percent
of the total acid mist for plant 19, Table A2. Although the concentrations
for unabsorbed sulfur trioxide can vary considerably, they can comprise an
appreciable part of the total acid-mist emission, usually under upset operating
conditions.
If the absorber discharge stack shows essentially no visible plume, the
operator can assume that loss of unabsorbed sulfur trioxide is neglible. If a
8.0 9.0 10.0 11.0 12.0
SO. IN ENTRANCE GAS, %
Fiqure 8 Percent conversion of sulfur dioxide to sulfur trioxide for plants with no air
dilution(lO).
SULFURIC ACID MANUFACTURE
29
-------
7.0 8.0 9.0 10.0 11.0 12.0
0-; IN EXIT GAS, %
Figure 9 — Percent conversion of sulfur dioxide to sulfur trioxide for plants with air dilution(ll).
detached plume is observed from the absorber discharge stack, then most of
the acid-mist emission could be accounted for by unabsorbed sulfur trioxide.
Formation of Sulfuric Acid Mist — Water-based acid mists are formed as
a result of the presence of water vapor in the process gases fed to the con-
verter. The drying towers in most contact plants are able to dry the air or
sulfur dioxide gas to a moisture content of about 3 milligrams per standard
cubic foot. The remaining moisture combines with the sulfur trioxide after
the converter, when the temperature falls below the dew point of sulfur tri-
oxide. The acid mist so formed is very difficult to remove in the absorber.
Much of it passes through the absorber to the atmosphere.
Theoretically, the 3 milligrams of water vapor will form approximately
15 milligrams of sulfuric acid. In a sulfur-burning plant producing 100 tons
per day sulfuric acid with 9 percent sulfur dioxide gas at 96 percent conver-
sion efficiency, the gas volume leaving the drying tower is about 5700 standard
cubic feet per minute. If all of the acid mist formed from the moisture in
the dried air were lost in the absorber exit gas, it would amount to 271 pounds
of acid per day. Part of the mist is probably removed in the absorber,
however.
In one rare type of plant, the wet gas plant, no attempt is made to remove
water vapor either from the combustion air or from the gas resulting from
combustion of the hydrogen sulfide. Hence, the amount of water vapor in
the gas entering the converter is more than enough to combine with all of
the sulfur trioxide produced. As a result, the entire output of the plant ini-
tially is in the form of acid mist rather than sulfur trioxide as in all other
types of plants. In such a plant, if operated with 7 percent sulfur dioxide gas
30
SULFURIC ACID MANUFACTURE
-------
entering the converter and at 96 percent conversion efficiency, the gas leaving
the converter, after cooling, would contain approximately 8500 milligrams
H2SO4 mist per standard cubic foot. Actually, some of the mist is recovered
in the gas-cooling equipment and the balance in high-efficiency recovery
equipment. Plant 7, Table A3 illustrates 'this case. After cooling, the gas still
contained 2533 milligrams acid mist. The glass-fiber eliminator reduced this
total to 2.3 milligrams in the stack gas, equivalent to 99.99 percent collection
efficiency.
In sulfur-burning plants, mists may also be formed from water resulting
from the combustion of hydrocarbon impurities in the sulfur. For example, a
100-ton acid plant at 96 percent yield would burn approximately 68,200
pounds per day of sulfur. If 0.1 percent of the sulfur were organic matter
containing 20 percent hydrogen, all of which formed water and then acid
mist, 667 pounds per day of sulfuric acid mist would be formed from this
source. The 667 pounds of mist from combustion of organic matter is more
than double the 271 pounds formed from moisture in the air leaving the dry-
ing tower. Dark sulfur may contain up to 0:5 percent organic matter. Thus,
in a sulfur-burning plant, appreciably more mist may be formed from com-
bustion of organic matter in sulfur than from moisture in the" dried air.
In plants other than those burning high-purity sulfur, if trace amounts
of hydrocarbon are present in the cold gas purification system, they are sub-
stantially .scrubbed out. in the drying tower. In plants of these types,, most
of the acid mist is formed from trace amounts of moisture leaving the drying
tower and from moisture formed by combustion of trace hydrocarbons.
Even with no moisture present in the inlet gases, however, it is possible
SO2 EMISSIONS, pounds per ton 100% H»SO4 .produced
M ** 01 oo o
mo o o o o o
\
\
S>
rN
, • •
x
X,
\
X
\
X
V
2 93 94 95 96 97 98 99 1C
CONVERSION OF SO* TO SOi, %
Figure 10 — Sulfur dioxide emissions at various conversion efficiencies (per ton of equivalent
100% HaSO, produced)
SULFURIC ACID MANUFACTURE
31
-------
to form in the absorbing tower very fine acid mist from shock cooling of the
inlet gases or from excessive gas velocity.
Small amounts of nitrogen oxides in the inlet gas to the absorber inter-
fere with the absorption of sulfur trioxide and hence cause visible acid mist
in the absorber exit gases. Nitrogen oxides are formed mainly from burning
nitrogenous matter in the spent acid or hydrogen sulfide raw materials.
Brink (12) found that the sulfuric acid collected in a fiber-glass mist elim-
inator in one typical, hydrogen sulfide spent acid plant contained 2 to 5 per-
cent oxides of nitrogen, calculated as nitric acid. Electrostatic precipitators
used for mist removal in cold gas purification units may form nitrogen oxides
if arcing occurs. Excessive sulfur burner temperature also results in forma-
tion of a small amount of nitrogen oxides.
Other than plants that use raw materials containing nitrogenous matter,
the oleum-producing plants have the greatest difficulty with visible mist in
the exit gas. The amount of the mist appears to be proportional to the percent
of plant output in the form of oleum and to the strength of the oleum pro-
duced (see Table 6). Plant design and the method and extent of cooling of
the sulfur trioxide gases ahead of the oleum tower greatly influence particle
size of the acid mist and hence visibility of the exit gases. These variables
are not clearly understood.
Comparison of acid-mist concentrations for plants 2A and 2B (Table A2)
and plants 5A and 5B (Table A3) show appreciably higher acid-mist concen-
trations for oleum production than when the same unit was making only 97
percent acid. This agrees essentially with Monsanto's published data (see
Table 6). Some ot the acid-mist concentrations for plants making oleum,
i.e., plants 7A, 7B, and 7C (Table A2), are in the same range as plant 8
(Table A2), which operated with no oleum production. All of these plants
operated with very pure recovered sulfur. In many cases where tests were
conducted in different plants, other variables such as design, moisture content
of dried air, absorber packing and absorbing acid temperature, concentration,
circulation, and distribution could also appreciably affect acid-mist emissions.
Unfortunately, all pertinent information is not always available.
The acid-mist emission from plant 12 (Table A2), which burns dark
sulfur is much higher than that for any of the plants using molten recovered
sulfur. This would be expected because of the higher hydrocarbon content of
the dark sulfur. Again, however, emissions from plants burning dark sulfur
(i.e., plant 11, Table A2) can be as low as those from plants using bright
sulfur, or lower. The above-described unknown variables could account for
the relatively low emissions from some of the plants burning 'dark sulfur.
No appreciable difference in ranges of acid-mist concentrations are ap-
parent for the different types of contact sulfuric acid plants. Whether a plant
is of sulfur-burning type with or without air dilution, or is of metallurgical
or spent acid type does not appear to be significant in regard to acid-mist
concentrations in stack gas from an absorber.
The weight percent of acid-mist particles leaving the absorber ahead of
any mist-recovery equipment and having a particle size of 3 microns or less
ranged from 7.5 to 95 percent of the acid mist for those plants in which
32
SULFURIC ACID MANUFACTURE
-------
particle size was determined. The mean weight percent of such acid mist
having a particle size of 3 micron or less for these acid plants is 63.5.
Plants 2A and 2B (Table A2) well illustrate the effect of making oleum.
When no oleum was made, only 9.5 percent of the mist particles were less
than 3 microns; when oleum was made, 54 percent were lets than 3 microns.
Any exceptions in other tabulated plants were from causes such as moisture
leaks, not related to grade of acid produced.
The visibility of acid mist depends more on particle size than on mist
concentration. Thus, a high percentage of particles 2 microns or less in the
acid mist usually causes a heavy plume from the absorber stack. Acid mist
composed of particles up to about 10 microns it visible in tail gas to a trained
observer if present in amounts greater than about 1 milligrarn of sulfuric
acid per cubic foot of gas (6). Conversely, exit gas containing 5 milligrams
or more of acid mist per cubic foot may be invisible if the particles are large.
Shutdown and Startup Losses — In plants that produce & Jlfur dioxide by
roasting ores in multiple-hearth roasters, rotary kilns, copper converters, or
sintering machines, sulfur dioxide losses will occur with a sudden shutdown.
In most cases these losses are minor and exist for a short period of time. In
other types of plants, where the sulfur dioxide producing equipment is vapor
tight, no escape of acidic gases may be expected.
In startup of a plant that has been shut down for a short period of time
and where operating temperatures for the catalyst chamber and the absorbers
are maintained, emissions of sulfur oxide may be expected to be in the same
range as during normal operations. Depending on climate, size of plant, and
quality of insulation, shutdowns may vary from 8 hours in a small plant to
24 hours in a large plant without excessive cooling of the catalyst chamber
or other equipment.
When the plant has been offstream long enough to allow the catalyst
chamber to cool, it is necessary to preheat the catalyst to its ignition temper-
ature before feeding any sulfur dioxide gas. This preheating is done by use
of a fuel, usually oil or gas. In sulfur-burning plants this fuel is burned,
instead of sulfur, in the sulfur burner. In plants of metallurgical type, a
special auxiliary tubular preheater with a fuel combustion chamber is in-
stalled to heat the incoming air indirectly. While, the catalyst is being pre-
heated, the sulfur dioxide producing equipment is heated simultaneously.
When the absorber temperature is below about 150°F, absorption effi-
ciency is decreased and the emission of sulfur trioxide and acid mist is con-
siderably above normal. No auxiliary equipment is usually available to
preheat the absorbing acid. Preheating with moist atmospheric air or com-
bustion gases is not considered a desirable operating procedure because the
moisture present in these gases will dilute the absorber acid, thus reducing
absorption efficiency, and may cause corrosion in other parts of the plant.
The usual practice in heating absorbing acid is to use the hot sulfur trioxide
gas produced in the catalyst chamber. About an hour is usually sufficient to
warm the absorbing acid to normal operating temperatures.
Losses of sulfur dioxide and acid mist may be excessive during startup
after a long shutdown if, in the haste to resume operation, the vital process
SULFURIC ACID MANUFACTURE 33
-------
equipment has not been preheated sufficiently. The duration of the excessive
losses depends primarily on how much the equipment is below normal operat-
ing temperatures. It may vary from a few minutes to 12 to 18 hours, depend-
ing on temperatures and skill of operation in making necessary adjustments
of valves, etc. During this period the emissions to the atmosphere gradually
decrease.
Losses From Sulfuric Acid Concentrators — Concentrators are occasion-
ally employed by both producers and users of sulfuric acid. Their function is
to concentrate acid that has been produced in a dilute form or acid that has
been diluted through use. Concentration may be necessary for reuse or to
reduce shipping costs. Use of concentrated acid may make it possible to avoid
discharging waste acid into a water course.
Concentration is often accompanied by the evolution of acid mist and
sulfur dioxide. The concentrating process is further complicated by the high
boiling point of the acid, its corrosiveness, and its tendency to foam when
impurities are present.
The two main types of concentrators used in the United States are the
vacuum and the drum types. The vacuum type operates under high vacuum
with heat applied indirectly. Hence, the boiling point of the acid is much
reduced and the acid-mist emissions, if any, are minor. In the drum type,
heat is applied directly in the form of hot combustion gases. Emissions of
sulfuric acid mist to the atmosphere can be prevented by use of electrostatic
precipitators, venturi scrubbers, or glass-fiber eliminators.
Acid-mist emissions taken ahead of the mist-recovery equipment for a
drum concentrator are given in Table 4.
TABLE 4. EMISSIONS FROM ACID DRUM CONCENTRATOR
Operating rate, % of capacity
H,,SO4 concentration rate, tons /day
Acid mist emission, mg/scf
Particle size, (3 microns and less), wt %
55
82
199.2
85
73
110
68.0
86
100
150
66.1
57"
"At maximum capacity more entrained large particles are present.
Other Losses — Loss of solid sulfur during unloading of deliveries and
from outdoor storage piles by windage and washage are appreciable, usually
from 1 to 2 percent of the sulfur delivered. Any dust settles rapidly within
a short distance; however, when sulfur is purchased in molten form, all such
losses are eliminated. When the raw material is sulfide ore, there may be
similar losses.
When spent or sludge acids are raw materials, malodorous gases may
escape during unloading or from storage tanks. The quantity is usually small.
Most of the process equipment in a contact plant is under low pressure.
Because of the obnoxious odor, any leakage of sulfur dioxide or sulfur tri-
oxide from process equipment is very noticeable. Also sulfur trioxide leaks
can be seen easily because of the white mist that forms immediately in the
presence of atmospheric moisture. Such leaks are usually promptly repaired.
34 SULFURIC ACID MANUFACTURE
-------
Since sulfur dioxide has low solubility in common product acids (60° Be
and up) no appreciable amount escapes from product acid storage tanks. The
acid condensed in the cold gas purification system of metallurgical type plants
is relatively weak and cool, however, and under these conditions it contains
substantial amounts of sulfur dioxide. In this type of plant, gas purification
equipment is under vacuum and no appreciable leakage occurs.
When oleum is produced, acidic gases may be vented to the atmosphere
from process and product oleum storage tanks. The emissions are most acute
during loading of the tank truck or tank car. When air in the tank is dis-
placed by oleum, sulfur trioxide vapor is vented to atmosphere in the form
of white acid mist. The amount of sulfur trioxide emitted is reduced by a
submerged transfer technique. In some plants, piping is installed for venting
the displaced acidic gases into the acid plant. Another control method entails
scrubbing the displaced vapor with 98 percent acid in a packed tower.
Process Control Methods for Sulfur Compounds
Sulfur Dioxide — In a contact plant, essentially all of the unconverted
sulfur dioxide leaving the converter passes through the absorption system
to atmosphere. The quantity and concentration of sulfur dioxide emissions
are dependent upon the catalyst converter and are related to the following
factors:
1. Concentration of sulfur dioxide in the gases entering the converter
and the ratio of oxygen to sulfur dioxide particularly in the last con-
verter stage.
2. Number of catalyst converter stages.
3. Volume and distribution of catalyst in various converter stages.
4. Catalyst efficiency.
5. Uniformity of gas composition.
6. Impurities in the entering gas.
7. Temperature control at various points in the converter (This depends
in part on having properly sized interstage gas-cooling equipment).
The minimum process control usually provided consists of temperature-
indicating instruments and chemical means for determining the concentrations
of sulfur dioxide in gases entering and leaving the converter. Usually the
standard Reich test is used for sulfur dioxide analysis. Maximum instrumen-
tation consists of temperature-indicating and recording instruments, air and
sulfur flow indicators or recorders, and analyzers and recorders for the con-
centrations of sulfur dioxide entering the converter and leaving the 98 percent
absorber. Analytical equipment for conducting the Reich test or equivalent
is included to check the accuracy of the recorders. A few contact plants are
equipped with a modified smoke-density recorder for the absorber exit gases.
In air dilution plants, apparatus is also provided for determining oxygen
concentration of the gas leaving the converter or the absorber.
In addition to the above-listed instruments, most contact plants use
interlocks that automatically shut the plant down in the event of an operating
emergency. Safety interlocks may be provided for shutting down the com-
bustion air blower and sulfur feed pumps in case of:
SULFURIC ACID MANUFACTURE 35
-------
1. Failure of the 98 percent absorber feed pump.
2. Very low acid depth in absorber acid distributor.
3. Excessively low or high water level in the waste heat boiler.
4. Excessively high temperature in the equipment.
Sulfuric Acid Mist — The emission of acid mist is a minor part of the
over-all acid plant yield. Because of the small size of the particles in an acid
mist, however, the emissions are easily observed. Many factors cause forma-
tion of acid mist, and no single panacea can eliminate them. The chief factors
responsible for formation and subsequent emission of acid mist are:
1. Improper concentration and temperature of the absorbing acid.
2. Amount and concentration of oleum produced.
3. High content of organic matter in the raw materials of a sulfur-
burning plant.
4. High moisture content of sulfur dioxide gases entering the converter.
5. Shock cooling of sulfur trioxide gases leaving the converter, i.e.,
sudden chilling below the acid dew point, resulting in condensation of
very small particles.
6. Presence of nitrogen oxides, which can result from excessive tempera-
tures in the combustion chamber, from raw materials, and from arcing
of electrical precipitators.
7. Insufficient rate of acid circulation and lack of uniformity in acid
distribution.
8. Improper type or unclean packing in the 98 percent absorber.
Of all the readily controllable factors, the most important is probably
the concentration and temperature of the 98 percent absorber acid. Since
fluctuation may occur in the concentration and temperature of the absorber
acid, it is watched most closely by the operator.
If acid-mist emissions from the absorber exit stack result in a heavy
plume, changes in plant operation, raw materials, or design may be needed
to reduce or eliminate stack plume opacity. Appendix C presents a tabulation
of "Methods of Determining Causes of Visible Plumes From Stacks of Contact
Acid Plants." In addition to these causes, the tabulation lists various measures
for improving stack appearance.
Sulfuric Acid Spray — In most modern contact units, acid spray is not
a problem. If an acid-spray emission occurs, it is normally the result of
operating appreciably above design rate or of poor absorber design or ex-
sessive gas velocity in the absorber exit stack.
Use of Tall Stacks — One method for controlling emissions of sulfur
dioxide and acid mist is the use of high stacks. The average acid plant stack
is between 40 and 100 feet high; a few have been built as high as 400 feet.
The effective height of a stack can be increased by adding hot air or
waste combustion gases. Hot air recovered from process equipment is used
occasionally to dilute and heat the stack gas.
Large-size particles may be removed by increasing stack height or re-
36 SULFURIC ACID MANUFACTURE
-------
ducing stack gas velocities. Part of the entrained acid is removed either by
impingement on the stack wall or by gravitational settling.
A series of test results shown in Table A4 for one sulfur-burning unit
equipped with a 250-foot-high stack showed a decrease in concentration of
acid mist and spray from 27 milligrams per cubic foot leaving the absorber
to 2 milligrams per cubic foot at the top of the stack. Thus, 91 weight percent
of total acid mist and spray from the absorber was recovered in the stack.
Most of the reduction in acid-spray concentration was achieved by removal
of large acid-mist particles. Essentially no reduction in acid particles of small
size (true acid mist) was effected.
In order to determine the amounts of acid mist collected in the stacks of
contact sulfuric acid plant absorbers, the total acid collected in the bases of
stacks was measured daily at four different plants. The results of these meas-
urements and process operating conditions are shown in Table A5. The steel
absorber stacks for each plant were approximately 200 feet high. The tests
were conducted during the winter when appreciable cooling of the stack and
the acid mist was encountered. The weight percent of total acid mist and
spray from the absorber that was collected in the stack as acid drip ranged
from 0 to 11 percent.
The amount of acid collected for plant 1, 22 pounds per day, was over
twice that collected by plant 2, 9 pounds per day. No acid drip was collected
at plants 3 and 4. The difference between ambient and stack gas temperature
was highest for plant 1, which collected 22 pounds per day of acid drip.
However, the temperature differential was .greater for plants 3 and 4, which
collected no acid drip, than for plant 2, which collected 9 pounds per day.
Plants 1 and 3 were equipped with Teflon® mist eliminators, whereas
plants 2 and 4 were not. Based on these limited observations, the amount of
acid mist collected in the absorber stacks does not appear to be affected
significantly by, (1) temperature difference between ambient air and stack
gas or (2) the use of acid mist eliminators.
The velocity of the stack gases for these four plants varied from 775 to
1990 feet per minute. These velocities were appreciably lower than the 2820
foot-per-minute velocity for the 250-foot high stack. Thus, lower emissions
of entrained acid mist and spray would be expected. Apparently the entrain-
ment of large acid-mist particles from the absorber is the main source of acid
drip in the absorber stack.
Ancillary Techniques for Recovery and Emission Control
Sulfur Dioxide — Plants are usually designed to minimize acidic gas
emissions to the atmosphere. Since addition of auxiliary equipment increases
capital expenditures and operating costs, many plants today operate with
little or no recovery equipment.
Many types of recovery processes have been proposed, but only rarely
are -they installed. The Cominco® (ammonia scrubbing) process is used in
only two plants in the United States. The process reduces SO2 concentration
in exit gases to about 0.08 percent for single-stage units or to about 0.03
percent for two-stage units.
SULFURIC ACID MANUFACTURE 37
-------
Although this process is highly efficient for removal of SO2, it is ineffi-
cient in removal of acid mist. The ammonia scrubbing equipment must be
supplemented with mist-removal equipment if mist is also a problem.
During World Wars I and II, the SO2 content of exit gases of contact
plants was used to some extent to make sodium sulnte-bisulflte solution to
wash trinitrotoluene. In this process the gases were scrubbed with sodium
carbonate solution; the process appears to have no utility in peacetime.
Scrubbing with fresh or salt water removes half to two-thirds of the SO2
but may present problems in the use or disposal of the resulting solution.
Sulfuric Acid Mist and Spray — A number of devices of varying cost and
efficiency are in use for removal of acid mist and spray from absorber tail
gases. With any of them, relatively high efficiencies (over 90 percent) do not
necessarily result in an invisible plume unless there are few particles less
than 3 microns and unless inlet mist loading is not excessive. The following
comments apply to devices used successfully on a commercial scale.
(1) Wire-Mesh Mist Eliminators
The lowest-flrst-cost device that effectively removes particles larger than
about 3 microns diameter is the wire-mesh eliminator. Particle size and
possibilities of corrosion from concentrated sulfuric acid mist must be care-
fully considered when selecting a wire-mesh eliminator. The eliminator is
commonly constructed with two beds in series and operates with pressure
drops of 1 to 3 inches of water. Test results for a two-stage wire-mesh
eliminator, given in Table A3, show an acid-mist collection efficiency of 92.6
percent. The collection efficiency decreased to 37.3 percent, however, when
oleum was produced. In this case, 62 percent of the particles were smaller
than 3 microns. Although no plume was visible during production of 98 per-
cent acid, a plume was plainly visible when oleum was also being produced.
Massey(:3) reports the following results (Table 5) for a system using a
two-stage alloy wire-mesh unit operating at a gas velocity of 12 to 15 feet
per second. No oleum was produced.
TABLE 5. EFFECT OF WIRE-MESH MIST ELIMINATORS
ON ACID-MIST COLLECTION
Pressure drop,
inches water
%
1
lJ/4
1V4
1%
1%
AVERAGE
Acid mist,
milligrams per cubic foot
of tail gas
Inlet
4.1
8.8
13.8
66.9
32.5
13.0
23.2
Outlet
0.74
0.7
0.92
0.77
0.98
0.76
0.81
Acid mist
collection efficiency, %
82.0
92.5
93.4
98.9
97.0
94.1
96.5
38 SULFURIC ACID MANUFACTURE
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(2) Fiber Mist Eliminators
The high-effciency glass-fiber mist eliminator is capable of operating
with acid-mist collection efficiencies of over 99 percent. The data for plants
5, 6, and 7 (Table A3) show acid-mist collection efficiencies for glass-fiber
eliminators ranging from about 50 to 99.9 percent. The lower collection effi-
ciencies for plant 5 were obtained with a glass-fiber unit specifically designed
for collection at high velocity and medium efficiency. A high-efficiency glass-
fiber unit was utilized in plant 7. For this plant, an acid-mist collection
efficiency of 99.9 percent was obtained for a tail gas stream in which 38
percent of the particles, by weight, were 3 microns and smaller. The pressure
drop for a high-efficiency glass-fiber mist eliminator is usually between 5
and 10 inches of water, but the system may be designed for higher or lower
pressure drops, depending upon relative costs for power and equipment.
The glass-fiber mist eliminator is also capable of maintaining a high
mist-collection efficiency at varying tail gas flow rates. Maintenance expense
is low.
Table 6, from Brink(22), gives data for collection of sulfuric acid mist in
a sulfur-burning contact plant with a glass-fiber mist eliminator.
(3) Electrostatic Precipitators
Electrostatic precipitators are highly efficient when used for collection of
acid mist regardless of size of the acid-mist particles. The acid-mist collection
efficiencies for precipitators in plants 3 and 4 (Table A3) ranged from 92.2
to 99.9 percent.
Precipitators operate with pressure drops less than 1 inch of water and
may be either of the wet or dry type. The dry type, which is suitable only for
concentrated acid, is much less expensive but more susceptible to corrosion.
Wet-type precipitators are suitable for use only with dilute acid and thus
necessitate prior humidification of stack gases. Pre-humidification also per-
mits removal of sulfur trioxide by converting it to acid mist. The humidifi-
cation step appreciably increases the cost of a wet-type installation.
(4) Ceramic Filters
The ceramic filter, a German device, is reported to operate with highly
efficient acid-mist collection at constant tail gas flow rates. Pressure drop is of
the order of 10 to 12 inches of water. The filter has not been accepted in
commercial installations in the United States because of high maintenance
costs and inflexibility in handling varying gas volumes.
(5) Venturi Scrubbers
Venturi scrubbers are also capable of operating with high acid-mist col-
lection efficiency, but at the expense of high pressure drop. The scrubbers are
also able to remove unabsorbed sulfur trioxide. Exit acid-mist loadings
ranging from 0.5 to 3 milligrams per cubic foot have been reported by one
manufacturer at pressure drops of 28 to 35 inches of water when used on
sulfuric acid concentrators (14). Venturi scrubbers have not been used on exit
gases from contact acid plants.
SULFURIC ACID MANUFACTURE 39
-------
(6) Packed-Bed Separators
In the past contact plants commonly included a packed-bed "spray
catcher" above the acid distributor in the absorber primarily to remove en-
trained particles of spray by impingement. The spray catcher is not efficient
in removing acid mist. Although some plants have used an external packed
bed for exit gas streams, none are known to be operating in this service today.
TABLE 6. COLLECTION OF H.,SO4 MIST FROM A SULFUR-BURNING
CONTACT SULFURIC ACID PLANT WITH FIBER MIST
ELIMINATORS (12)
Contact plant
production
Mist loading" of
gases leaving
absorber and
entering mist,
eliminator,
mg H2SO4/scf
Mist loading3
of gases
leaving mist
eliminator,
mg H2SO4/scf
Particle
collection
efficiency
(3^ and smaller), %
Mist Eliminator Ab
99% HL,SO4 and
65% oleum at
full capacity
99%- H.,SO4 and
25% oleum at
75% capacity
30.9
31.8
39.9
6.55
8.75
6.64
1.50
1.48
1.64
0.124
0.169
0.125
95.1
95.3
95.9
98.1
98.1
98.1
Mist Eliminator Bb
99% H2SO4 and
25% oleum at
full capacity
99% H2SO4 and
25% oleum at
60% capacity
99% H.,SO4 at
60% capacity
14.4
18.3
19.3
6.88
2.12
0.085
0.112
0.095
0.045
0.014
99.4
99.4
99.5
99.3
99.3
•'The mist-loading values are limited to particles 3 microns in diameter and
smaller.
''Mist eliminator A was designed for 100 percent efficiency for particles larger
than 3 microns diameter and for 95 percent efficiency for particles 3 microns
and smaller, operated at a pressure drop of 3 inches of water. Mist eliminator
B was designed for 100 percent efficiency for particles larger than 3 microns
and for 99 percent efficiency on particles 3 microns diameter and smaller,
operated at a pressure drop of 6 inches of water.
40
SULFURIC ACID MANUFACTURE
-------
SUMMARY OF SAMPLING AND ANALYTICAL TECHNIQUES
A variety of stack-sampling and analytical procedures have been used by
various sulfuric acid manufacturers, by air pollution control districts, and by
the joint Manufacturing Chemists' Association — Public Health Service field-
test team in obtaining the emission data shown in Tables Al and A3. Detailed
descriptions of these sampling and analytical procedures are presented in
Appendix B.
SULFURIC ACID MIST
Many of the contact acid plants use the Monsanto Company Method for
collection and analysis of sulfuric acid mist(15).
This technique, with several modifications, was also used by the joint
MCA-PHS field test team. Effluent gas samples were collected in the duct or
exit stack just above the acid absorber. Pitot tube traverses were made to
determine the velocity profile of the gases in the duct. Sampling was per-
formed isokinetically at a number of traverse points. The stack gases were
drawn through a glass sampling train consisting of a probe, a cyclone col-
lector, and a glass-fiber mist collector. Both the probe and enclosed sample
train were heated to preclude condensation in the sample gas stream. The
cyclone collected acid-mist particles larger than 3 microns. The particles
smaller than 3 microns •were collected on the fine glass-fiber filter. Analysis
for sulfuric acid mist in both the cyclone and the glass-fiber filter tube was
performed by titrating with dilute caustic to a phenolphthalein end point.
A few of the plants for which data are reported employed medium-
porosity fritted glass disks, or millipore or Whatman filters for collection of
sulfuric acid mist. In each case analysis was performed by titrating with
dilute caustic to a phenolphthalein end point.
SULFUR DIOXIDE AND SULFUR TRIOXIDE
The most commonly used method for sulfur dioxide analysis in sulfuric
acid plants is the Reich test (16). This test is normally performed by the acid
plant operator at least once during his work shift. Most of the acid plants for
which data are reported utilized the Reich test for determining the sulfur
dioxide concentration in the stack gas. Analysis was conducted by passing a
measured volume of stack gas through a known quantity of iodine solution
containing starch until the blue color disappeared. In some cases the sulfur
dioxide concentrations were determined from gas samples collected an hour
before or after the acid-mist samples under essentially the same operating
conditions.
The Shell Development Method was used by the joint MCA-PHS field
test team for sample collection and analysis of both sulfur dioxide and sulfur
trioxide(27). Sample gas was first drawn through a glass-wool filter, then
passed through a heated glass probe into a system of three sintered glass plate
absorbers. The first absorber was immersed in an ice bath. The first two
absorbers contained an isopropyl alcohol - water solution for absorption of
sulfur trioxide. The third absorber contained dilute hydrogen peroxide in
water for absorption of sulfur dioxide. Purified air was passed through the
absorbers at the end of the run to remove any dissolved sulfur dioxide in the
first two absorbers. Any sulfur dioxide removed was absorbed by hydrogen
SAMPLING AND ANALYSIS: SUMMARY 41
-------
peroxide in the third absorber. Analysis was conducted by titrating each
solution with standard barium chloride using thorin indicator.
The Chemical Construction technique was used Jo determine the sulfur
dioxide and sulfur trioxide concentrations shown for plants 3 and 16 (Table
A2) (18). Sample gas was drawn through a glass probe and tray into a system
consisting of two glass-fiber filters held by a fritted glass disk. Two bubblers
with coarse-fritted glass gas distributors and a flow meter completed the
sampling train. Each bubbler contained a standardized solution of hydrogen
peroxide in water. At the conclusion of sampling, the absorbing solution in
the two impingers was transferred to a volumetric flask and diluted to the
mark. Half of this solution was titrated with standard potassium permanga-
nate for unused hydrogen peroxide. The difference in titration between the
standard hydrogen peroxide solution and the sample yielded the sulfur
dioxide concentration. The other half of the sample solution was titrated
with standard caustic for total concentration of sulfur dioxide and sulfur
trioxide. The sulfur trioxide concentration was determined by difference.
The sulfur dioxide concentration for plants 5A and 5B (Table A3) was
determined by the Reich method. The sulfur trioxide in this sample gas
stream was absorbed in an isopropyl alcohol - water solution contained in
Greenberg-Smith impingers. Analysis was made by titration with standard
barium chloride.
The sulfur dioxide concentration for plant 19 (Table A2) was determined
by the Reich method. The sample gas was drawn through a fine-fritted glass
disk for collection of acid mist. The acid-mist concentration was determined
by titration with dilute caustic. A second acid-mist sample was collected by
the same procedure after the sample gas stream had been humidified to
hydrate the sulfur trioxide. Analysis for total acid mist and sulfur trioxide
was then made by titration with dilute caustic. The sulfur trioxide concen-
tration was determined by difference.
OXIDES OF NITROGEN
Total nitrogen oxide concentration was determined in all tests by the
Bureau of Mines phenoldisulfonic acid method (19), which is free from inter-
ference by sulfur dioxide. The sample was drawn through a glass probe and
collected in an evacuated 2-liter flask containing a dilute solution of sulfuric
acid and hydrogen peroxide. After sampling, the resultant solution was
neutralized, evaporated to dryness, and treated with phenoldisulfonic reagent
and ammonium hydroxide. The yellow trialkali salt formed was measured
colorimetrically.
Nitrogen dioxide was determined by the Saltzman technique(20). The
gas sample was collected in a syringe containing Saltzman reagent. After the
syringe was shaken for 1 minute the gas was expelled, and after 15 minutes
the concentration of nitrogen dioxide was measured colorimetrically. This
technique minimizes the interference caused by air oxidation of nitrogen
oxide to nitrogen dioxide and by sulfuric dioxide.
After the concentrations of total nitrogen oxides and of nitrogen dioxide
were determined by the phenoldisulfonic acid and the Saltzman techniques
respectively, the concentration of nitric oxide was determined by difference'
42 SAMPLING AND ANALYSIS: SUMMARY
-------
°B<§
°C
cf, ft3, cu ft
cfm
°F
ft/min
gr
in. H2O
in. Hg
Ifm
mg
ml
mm
Mscfm
psig
°R
®
scf
scfm
slfm
sp. gr.
CHEMICAL SYMBOLS
H2O
H2S
H2S0
Hg
GLOSSARY OF TERMS
degrees Baume (Specific gravity =
145
NH3
NO
NO
S
SO2
S03
SO5NH
145 — "Be
temperature, degrees Centigrade
cubic feet
cubic feet per minute, measured at actual tempera-
ture and pressure
temperature, degrees Fahrenheit
feet per minute
grain (1 grain equals 64.8 milligrams)
inches of water
inches of mercury
linear feet per minute measured at actual tempera-
ture and pressure
milligram
milliliter
millimeter
1000 standard cubic feet per minute
pounds per square inch gage
temperature, degrees Rankine (°F plus 460 degrees)
registered trade mark
standard cubic feet measured at 0°C (32°F) and
760 mm (29.92 in.) Hg
standard cfm, measured at 0°C (32°F) and 760 mm
(29.92 in.) Hg
standard linear feet per minute, measured at
0°C (32°F) and 760 mm (29.92 in.) Hg
specific gravity
hydrogen
water
hydrogen sulfide
sulfuric acid (monohydrate of sulfur trioxide or
100 percent acid)
mercury
nitrogen
ammonia
nitric oxide
nitrogen dioxide
oxygen
sulfur
sulfur dioxide
sulfur trioxide
nitrosylsulfuric acid "nitrose"
GLOSSARY
43
-------
DEFINITIONS
Absorber
Baume (Be)
The absorber in the contact process is a cor-
rosion-resistant brick-lined steel tower usually
packed with partition rings.
Acid strength is determined by use of a floating
instrument (hydn meter) calibrated to read degrees
Baume and by a conversion chart. The Baume can
also be calculated if the specific gravity of the sul-
furic acid is known:
"Be = 145 —
145
sp. gr.
The catalyst in a chamber plant is gaseous
nitrogen oxides. In the contact process the catalyst
is a solid, consisting of vanadium pentoxide and
various promoters deposited on a highly porous
siliceous carrier.
Sulfuric acid made by the chamber process with
strength not exceeding 60° Baume (77.67 percent).
The vessel that houses the solid vanadium cata-
lyst. The catalyst is placed in several horizontal
trays or stages located in series, with means for gas
cooling between the various stages.
A low-sulfur-content raw material consisting of
a mixture of elemental sulfur and inert material.
Any sulfur in elemental form, regardless of
source.
A high-purity sulfur containing not more than
0.01 percent ash and from 0.05 percent or less to 1.0
percent hydrocarbons, with no free water or acid
when mined. (If shipped molten, it may also con-
tain traces of hydrogen sulfide.)
Sulfuric acid made from elemental sulfur or
other sulfur-bearing materials, but not from spent
acid strengthened by addition of sulfur trioxide.
A term used loosely concerning chamber plants
and having many meanings. It can refer to equiva-
lent consumption of 96 percent pure nitrate of soda
(NaNOg), nitric acid (HNO3), and ammonia (NH3),
or any of the oxides of nitrogen.
Nitrose or nitrous vitriol Sulfuric acid from the Gay Lussac tower, con-
taining 1 to 2 percent oxides of nitrogen.
Catalyst
Chamber acid
Converter
Crude sulfur
Elemental sulfur
Frasch-process sulfur
New or virgin acid
Niter or nitre
Oleum or fuming
sulfuric acid
A solution of free, uncombined sulfur trioxide
(SO3) in sulfuric acid (H2SO4), e.g. 20 percent
oleum refers to a solution containing 20 percent
free sulfur trioxide and 80 percent sulfuric acid.
Oleum is sometimes referred to as over 100 percent
44
GLOSSARY
-------
acid; thus, 20 percent oleum may be called 104.5
percent sulfuric acid. This means that if enough
water were added to 100 parts of 20 percent oleum
to combine with the free sulfur trioxide, 104.5 parts
of sulfuric acid would be obtained.
Particle size Refers to equivalent diameter assuming that
the particles are spheres.
Plant, unit, establishment The word plant, as used herein, is synonymous
with unit. The word establishment herein denotes
a works in which there may be one or more sulfuric
acid plants or units, each being a complete produc-
tion entity.
Recovered sulfur
Regenerated acid
SO,, gas or SOS gas
Sulfur oxides
Sulfuric acid mist
Sulfuric acid spray
Yield
An extremely high-purity sulfur containing no
organic matter, less than 0.005 percent ash, and no
free acid or water unless exposed to the atmos-
phere. (If shipped molten, it may also contain
traces of hydrogen sulfide.)
High-purity sulfuric acid made from decompo-
sition or regeneration of spent acid from petroleum
refineries or other chemical processes.
A gas in which SO,, or SO3 is present with
other constituents such as oxygen or nitrogen.
As used in this report, sulfur oxides include
sulfur dioxide and sulfur trioxide, and/or sulfuric
acid mist or spray.
Extremely small acid particles that are true
aerosols. No exact range of particle size is available.
The "Modified Monsanto Company Technique" (Ap-
pendix B) arbitrarily distinguishes between the per-
centage of particles greater than 3 microns diameter
and of those 3 microns and smaller.
Large acid particles introduced into the gas by
mechanical entrainment. If emitted to atmosphere,
they are invisible and fall rapidly to the ground.
See "Stick Test," Appendix B.
The molar percent conversion of sulfur and/or
sulfur dioxide into sulfuric acid.
GLOSSARY
45
-------
APPENDICES
A. EMISSION AND OPERATING DATA FOR CHAMBER AND
CONTACT SULFURIC ACID PLANTS 49
B. SAMPLING AND ANALYTICAL TECHNIQUES 59
Modified Monsanto Company Method for Sulfuric Acid Mist 61
Monsanto Company Procedures for Contact Sulfuric Acid Plants .. 67
Reich Test for Sulfur Dioxide (not for use in Air-Quench
Plants) 67
Reich Test for Sulfur Dioxide (for Sulfur-Burning Plants
of the Air-Quench Type) 76
Determination of Moisture Content of Acid-Dried Air or
Gas in Contact Sulfuric Acid Plants 80
Determination of Acid Content of Acid-Dried Air or Gas
in Contact Sulfuric Acid Plants 82
"Stick" Test for Determination of Sulfuric Acid Spray 84
Shell Development Company Method for Sulfur Dioxide and
Sulfur Trioxide 85
Chemical Construction Corporation Methods for Gas Analysis
at Contact Sulfuric Acid Plants 87
Phenoldisulfonic Acid Method for Total Nitrogen Oxides 92
Saltzman Method for Nitrogen Dioxide 95
C. METHODS OF DETERMINING CAUSES OF VISIBLE
PLUMES FROM STACKS OF CONTACT SULFURIC ACID
PLANTS 99
D. SULFURIC ACID ESTABLISHMENTS IN THE UNITED
STATES (AS OF NOVEMBER 1, 1963) 107
E. PHYSICAL DATA 117
APPENDICES 47
-------
APPENDIX A: EMISSION AND OPERATING DATA
FOR CHAMBER AND CONTACT SULFURIC ACID PLANTS
Most of the emission and operating data in Appendix A were supplied
by the major manufacturers of sulfuric acid. Data from essentially all types
of sulfuric acid plants are included. The emission data represent results from
approximately 12 percent of the present number of establishments and include
results from stack-sampling programs conducted jointly by the Manufactur-
ing Chemists' Association and the Public Health Service.
-------
TABLE Al. EMISSION AND OPERATING DATA FOR
CHAMBER SULFURIC ACID PLANTS*
Raw material
Plant number
H2SO4 production, tons/day
Percent of maximum plant capacity
Stack gas temperature, °F
Stack gas rate, Mscfmb
O2 in stack gas, vol %
SO2 in stack gas, vol %
SO2 emitted, tons /day
NO2 in stack gas, vol %
Total NOX in stack gas, vol %c
Total NOX emitted, tons/day
H2SO4 mist leaving Gay-Lussac tower, mg/scf
Total acid mist leaving Gay-Lussac tower, mg/scfa
Total acid mist leaving Gay-Lussac tower, tons /day
Acid mist, % less than 3 micron diameter
Stack plume opacity
Molten dark
sulfur
1
113
90
105
12.5
16.5
0.087
1.40
0.123
0.185
2.12
5.3
5.9
0.12
10.1
Medium
Solid
sulfur
2
29
80
105
1.9
8.3
0.164
0.41
0.048
0.099
1.14
28.2
33.0
0.10
3.5
Medium
"Sampling points were in duct or exit stack near top of Gay Lussac Tower.
Data for each plant are averages of four tests conducted by joint MCA-PHS
field test team.
bAll volumes corrected to 32°F and 29.9 in. Hg.
cTotal NOX measured at NO2.
dTotal acid mist measured as H2SO4 and HNO3.
APPENDIX A
51
-------
TABLE A2. EMISSION AND OPERATING °ATA FOR CONTACT
SULFURIC ACID PLANTS WITHOUT MIST ELIMINATORS"
Plant type
Raw material
Plant number
H.,SO4 production,
tons /day
Percent of maximum
plant capacity
Oleum made,
% of output
Oleum made,
% of free SO,
Stack gas temper-
ature, °Ff
Stack gas rate, Mscfm
SO2 entering con-
verter, vol %s
SO0 in stack gas,
vol %h
Conversion of SO.,
to SO8, %
SO2 emitted, tons /day
Acid mist leaving
absorber, mg/scf
Acid mist, % less
than 3 microns
Acid mist emission
from absorber,
tons /day
SOS concentration
leaving absorber
mg/scf
Plume opacity
Sulfur burning, air dilution
Molten dark
1
735
98
0
212
45
8.0
0.20
97.8
11.5
2.37
25
0.17
none
2Ad
650
00
0
175
48
7.0
0.31
96.0
19.0
15 5
9.5
1.18
med
2B
650
00
25
20
175
48
7.0
0.31
96.0
19.0
23 7
54
1.81
dns
3
120
80
50
20
115
7.6
8.0
0.23
97.5
2.2
1 1
19.2
4
422
51
30.8
123
25.1
8.8
0.25
97.5
8.0
2.0
4 0
0.12
It
Molten
recovered
5
130
00
0
175
7.5
8.8
0.28
97.
9 -
q 9
80
0.11
fnt
6A
100
77
0
173
6.5
8.0
0.20
97.8
1.7
3 7
81
0.04
none
6B
100
77
0
168
6.5
8.0
0.20
97.8
1.7
2 2
82
0.02
none
no air dilution
Molten recovered
7A
325
100
43
20
148
16.7
10.5
0.53
95.7
11.3
2 3
80
0.06
It
7B
325
100
43
26
148
16.6
10.6
0.54
95.6
11.5
5 1
87
0.13
med
VC
162
50
35
20-25
140
11.0
7.7
0.13
98.5
1.8
25
0.04
i
tt«
115
30
0
0
94
5.9
8.8
0.19
98.1
1 4
•M
0.02
med
"Sampling points:
Plant 11: In horizontal duct leading to remote stack about 100 feet from
absorber.
Plant 19: In stack about 35 feet above absorber.
All other plants: In duct or exit stack near top of absorber. (All plants in-
corporate internal, packed bed "spray" eliminators as part of the standard
absorber design.)
bPyrite or pyrrhotite.
cByproduct SO2 gas from decomposition of sulfates.
dPlant numbers followed by letters indicate tests made in the same plant under
different operating conditions. Thus, plants 2A and 2B represent the same
plant.
52
APPENDIX A
-------
TABLE A2 (Continued)
Plant type
Raw material
Plant number
H2SO4 production,
tons /day
Percent of maximum
plant capacity
Oleum made,
% of output
Oleum made,
% of free SO,
Stack gas temper-
ature, °Ff
Stack gas rate, Mscfm
SO2 entering con-
verter, vol %e
SO2 in stack gas,
vol %i>
Conversion of SO9
to SO3, %
SO2 emitted, tons /day
Acid mist leaving
absorber, mg/scf
Acid mist, % less
than 3 microns
Acid mist emission
from absorber,
tons /day
SO3 concentration
leaving absorber
mg/scf
Plume opacity
Sulfur burning,
no air dilution
Solid
Brt.
9
210
100
0
12.0
9.1
0.24
97.7
3.7
9.5
0.18
It
Dk.
10
500
100
40
25
170
30.0
10.2
0.40
96.7
15.4
6.1
78
0.29
med
Molten
dark
11
310
100
100
25
105
17.0
9.0
0.25
97.6
5.4
1.9
91
0.05
med
12
265
88
33
38
170
14.0
10.0
0.42
96.5
7.5
37.3
95
0.83
dns
Metallurgical
Pyr't
spent
acid
13
285
100
25
26
190
18.2
8.0
0.23
97.5
5.4
6.0
0.17
i
Pyr't
b
14
500
100
0
35
33.2
14
1.84
dns
By-
prod.
gas1'
15
100
70
yes
5.0
13.7
91
0.11
med
Spent acid
Spent acid
and sulfur
16
650
91
77
20
136
58.5
8.8
0.37
96.3
27.7
8.4
0.78
48.0
17
302
71.5
20
163
19.7
8.0
0.20
97.8
5.0
10-12
0.34
Spt.
acid
18
900
100
0
0
145
62
7.5
0.34
95.9
27.0
10.2
90
1.00
dns
Spent
acid,
H.,S,
sulfur
19
91
18
20
178
34
6.7
0.20
97.3
8.7
7.0
0.38
0.5
eThis plant uses an impingement type of separator in the stack, which removes
mainly spray.
'Some of the temperatures are of acid entering the absorbers; however, outlet
gas and inlet acid temperatures are usually close together.
sin the air dilution type of plant, this is the equivalent percent SO2 after cor-
rection for air dilution.
''Some of the concentrations of SO2 were obtained from samples collected
either before or after the acid mist samples but under essentially the same
operating conditions.
'Unabsorbed SO3 is included as part of the concentration of acid mist leaving
the absorber.
APPENDIX A
53
-------
TABLE A3 EMISSION AND OPERATING DATA FOR CONTACT
SULFURIC ACID PLANTS WITH MIST ELIMINATORS"
Plant type
Raw material
Plant number
H2SO4 production,
tons /day
Percent of
maximum capacity
Oleum made, % of output
Oleum made,
% of free SO3
Stack gas tem-
perature, °Fd
Stack gas rate, Mscfm
SO2 entering
converter, vol %
SO2 in stack gas, vol %
Conversion of SO2 to
S03, %
SO2 emitted, tons/day
Type of mist eliminator
Acid mist leaving absorber
% less than 3 microns
Acid mist leaving absorb-
er, mg/scf
Acid mist leaving mist
eliminator, mg/scf
H2SO4 collection
efficiency, %
H2SO4 emitted, tons/day
SO3 concentration leaving
absorber mg/scf
SO3 concentration leaving
mist eliminator, mg/scf
Plume opacity
Sulfur
Air dil. No air dil.
Molten dark
1
961
96
0
0
186
58
8.0
0.14
98.5
10.4
2A»
150
68
0
0
165
7.4
8.0
0.19
97.6
1.8
Wire me
70
6.5
0.60
light
7.5
48.8
3.6
92.6
0.04
2.1
1.1
none
2Bt>
150
68
13
30
166
7.4
8.0
0.20
97.5
1.9
sh
62.0
37.3
23.4
37.2
0.27
1.0
med.
Combination
Spent acid, H2S, and
supplemental sulfur
3A
240
100
0
180
0.34
3B
240
100
0
180
0.35
3C
219
91
0
76
12
8.2
0.26
97.2
4.0
4
133
60
56
40
76
7
8.4
0.17
98.2
1.5
Electrical precipitator
5.9
0.33
94.5
light
4.9
0.38
92.2
light
7.1
0.18
97.5
0.003
light
29.0
0.31
99.9
0.003
light
"Sampling points:
Plant 6A and 6B: in horizontal duct between absorber top and exit stack.
All other plants: in duct or exit stack near top of absorber.
bTest data for Plant 2A and 2B were obtained by joint MCA-PHS field testing.
The results are averages of several tests.
54
APPENDIX A
-------
TABLE A3 (Continued)
Plant type
Raw material
Plant number
H2SO4 production,
tons /day
Percent of
maximum capacity
Oleum made, % of output
Oleum made,
% of free SO3
Stack gas tem-
perature, °Fd
Stack gas rate, Mscfm
SO2 entering
converter, vol %
SO2 in stack gas, vol %
Conversion of SO2 to
S03, %
SO2 emitted, tons /day
Type of mist eliminator
Acid mist leaving absorber,
% less than 3 microns
Acid mist leaving absorb-
er, mg/scf
Acid mist leaving mist
eliminator, mg/scf
H2SO4 collection
efficiency, %
H2SO4 emitted, tons /day
SO3 concentration leaving
absorber mg/scf
SO3 concentration leaving
mist eliminator, mg/scf
Plume opacity
Combination
Spent acid, H2S, and
supplemental sulfur
5A
300
76
0
175
17
9.0
0.32
96.9
7.0
l_4e
0.5-2
50.0
0.01-.05
1-2
1-2
5B
300
76
2
25
6A<=
265
88
0
160
14
7.2
0.16
98.0
2.8
6B"
300
100
0
180
21
7.4
0.19
97.8
5.1
Glass fiber
10-306
7-9
60.0
20.6
0.23
98.9
0.005
none
32
1.9
94.1
0.06
faint
Wet
gas
H2S
sulfur
7
100
67
0
130
11
38
2533'
2.3
99.9
0.04
light
Sulfur
Molten
dark
8
429
13
21.5
176
28.0
8.0
0.19
98.0
6.8
Combi-
nation
Spent
acid,
sulfur
9
272
0
150
19.3
7.4
0.20
96.7
5.0
Teflon® mesh
1-2
faint
1-4
faint
cRaw material included 48.4% spent acid, 32.8% H2S, and 18.8% sulfur.
dSome of the temperatures are of acid entering the tower; however, inlet gas
and acid temperatures are usually close together.
eHigh-velocity type glass-fiber mist eliminator designed for only medium
performance.
'This "wet gas" unit utilized no water-removal facilities for the discharge
combustion chamber gases.
APPENDIX A
55
-------
TABLE A4. CONCENTRATIONS OF SULFURIC ACID MIST AND
SPRAY AT VARIOUS STACK ELEVATIONS
(Sulfur-Burning Plant with Molten Sulfur as Raw Material)
Oleum, % of output
Stack height, ft
Stack gas velocity, ft/min
Stack gas temperature, °F
Stack gas rate, scfma
SO2 entering converter, vol %
Conversion of SO2 to SO3, %
SO2 in stack gas, vol %
Concentration of acid spray at absorber outlet, mg/scfb
Concentration of acid mist at absorber outlet, mg/scf
Concentration of acid spray at 100-ft elevation in stack, mg/scf
Concentration of acid mist at 100-ft elevation in stack, mg/scf
Concentration of acid spray at 250-ft elevation in stack, mg/scf
Concentration of acid mist at 250-ft elevation in stack, mg/scf
Total acid mist and spray from absorber collected in stack, wt %
0
250
2,820
180
27,290
9.0
95.7
0.39
26.65
0.64
10.12
0.77
2.15
0.38
91
"Volume corrected to 32°F and 29.9 in. Hg.
hAll acid spray or mist concentrations are average values for three test runs.
Acid spray included only that caught on inside of glass probe. Acid mist was
collected in an asbestos filter.
56 APPENDIX A
-------
TABLE A5. ACID-MIST COLLECTION IN ABSORBER STACKS
OF CONTACT SULFURIC ACID PLANTS4
Raw material
Plant number
H2SO4 production, tons /day
Oleum, % of output
Oleum, % of free SO3
Stack gas temperature, °F
Stack gas rate, Mscfm
SO2 entering converter, vol %
Conversion of SO2 to SO3, %
SO2 in stack gas, vol %
Ambient temperature (avg) , °F
Ambient temperature (range), °F
Wind direction
Wind velocity (avg) , mph
Stack plume opacity
Stack gas velocity, ft/min
H,SO4 concentration
leaving absorber, mg/ft3b
H2SO4 concentration
leaving Teflon demister, mg/ft3b
Acid drip from base of stack, Ib/day
Strength of acid drip, % H2SO4
Total acid mist from absorber
collected in stack, wt %c
Molten sulfur
1
429
13
21.5
176
28.0
8.0
98.0
0.19
25
8-37
NW, W, SW
10.1
faint
1990
1-2
22
70.4
11.0
2
422
51
30.8
123
25.1
8.8
97.5
0.25
29
25-36
N,NW,W
6.4
light
1620
2-4
no
demister
9
99.5
3.6
Molten sulfur
and spent acid
3
272
0
0
150
19.3
7.4
97.6
0.20
42
S-SE
12
faint
1080
1-4
0
0
4
302
71.5
20.0
163
19.7
8.0
97.8
0.20
35
s-sw
3
medium
775
10-12
no
demister
0
0
"All plants incorporate internal, packed bed "spray" eliminators as part of the
standard absorber design.
''Acid mist concentrations are normal loadings, but were not obtained during
acid drip measurements.
c'The amounts of acid mist collected were averages from several tests con-
ducted at each plant.
APPENDIX A
57
-------
APPENDIX B: SAMPLING AND ANALYTICAL TECHNIQUES
The sampling and analytical techniques described here include those
used to obtain the emission data given in Appendix A and are those generally
used in the sulfuric acid manufacturing industry. Format and wording for
most of these procedures are those of the company that supplied the descrip-
tion.
-------
MODIFIED MONSANTO COMPANY TECHNIQUE FOR SAMPLING
SULFURIC ACID MIST (15)
Description of Sampling- Equipment
The equipment used for sampling acid mist was constructed by the
Public Health Service and is based on the equipment used by the Monsanto
Company. This portable train allows collection of a wide range of mist or
dust concentrations in a minimum of time. Particles greater than 3 microns
diameter are determined separately from the smaller particles.
The Public Health Service sampling train, Figures Bl and B2, consists
of a glass probe, a high-efficiency glass cyclone to collect particles larger than
3 microns diameter, and a filter that traps the smaller particles. A calibrated
orifice, dry gas meter, and pump complete the train.
Figure Bl — Acid-mist sampling train, control panel.
To prevent condensation of mist in the train, the collection system is
mounted in a heated, insulated box. Heating is accomplished by two thermo-
statically controlled electric heaters mounted in a transite box within the
sampler. The heaters are rated at 1000 watts each at 110 volts. They consist
of cone-shaped ceramic holders wound with heating wire and are commonly
called bowl heaters. The transite box is open at each end, and a small fan
circulates hot air around the collection equipment.
On the other side of the sampling box are mounted two manometers to
indicate flow rate through the train, two dial stem thermometers to measure
APPENDIX B
61
-------
Figure B2 — Acid-mist sampling train, collection compartment.
temperatures at the cyclone and orifice, and a temperature-controlling
thermostat.
The filter consists of a 65-mm-diameter glass Buchner funnel with a
coarse-porosity filtering disc. Two layers of fiberglass filter paper (MSA CT
75428) are placed on the filtering disc to form the acid-mist filter. The
packed fiberglass wool filter (Pyrex 3950) as described by Monsanto is also
highly efficient.
The dry gas meter may be omitted if the rate of flow through the cali-
brated orifice is carefully watched. In the field, however, circumstances may
prevent careful observation of flow rate, and a dry gas meter insures accurate
measurement of total volume flow.
Selection of Sampling Points
The location and number of sampling points are based on size and shape
of the duct, uniformity of gas flow in the duct, availability of sampling port,
and space required to set up sampling equipment.
Straight vertical ducts with no flow obstructions for at least 8 diameters
upstream of the sampling point are preferred. Sometimes one must settle
for less than these ideal conditions.
To insure a representative sample of stack gas, the duct should be divided
into a number of equal areas and sampled at the center of each of these areas.
62
APPENDIX B
-------
The number of areas depends on the size of the stack. This procedure pre-
vents erroneous results due to stratification of the acid mist in the duct.
Bulletin WP-50 of the Western Precipitation Company may prove useful in
determining the number of areas.
Stack Gas Velocity
The pitot tube is used for most velocity measurements. The basic equa-
tion for calculating velocity is, Vs = 174K V^HT8 x-^—x--, where Vs
is the gas velocity in feet per minute, K is the pitot tube calibration factor,
H is the velocity head in inches of water, Ta is the stack gas temperature in
°R, P8 is the absolute pressure of stack gas in inches of mercury, and MW is
the molecular weight of the process gas. This equation simplifies to Vs =
174KVHTB when the stack pressure is approximately equal to 29.9 and the
molecular weight of the process gas is equal to that of air (29.0).
Determination of Sampling Rate
In use of the acid mist train, a sampling rate of about 1 cfm at 70°F
must be maintained in order to insure separation of particles larger than
3 microns diameter in the cyclone.
Nozzle area is then determined by dividing sampling rate by stack gas
Q, sampling rate at stack gas conditions
velocity, i.e. An = VB, stack gas velocity
It is, of course, impractical to vary nozzle size once sampling has begun.
Therefore, if gas velocity varies considerably, the sampling rate must be
varied and either cyclone efficiency or isokinetic sampling must be sacrificed.
Isokinetic sampling is not necessary if previous testing has shown that about
90 percent of the acid mist particles are below 3 to 5 microns diameter.
Sampling rates and the corresponding pressure drop across the orifice
should be computed for each sampling point before sampling is begun. These
values should be recorded on the data sheet, Figure B3. Care must be taken
in using the orifice calibration curve at various temperatures and pressures.
A typical orifice calibration curve is shown in Figure B4. The following
equations may prove useful:
MW
-530" Pb - PQ
AP0 = pressure drop across orifice at orifice pressure and tempera-
ture, in. H2O
Pb = barometric pressure, in. Hg
AP(caiib) = pressure drop across orifice at orifice calibration conditions,
in. H2O
T0 = temperature at orifice, °R
P0 = gauge pressure at inlet to orifice, in. Hg
MW = molecular weight of gas
Qo = flow through orifice at orifice temperature and pressure, cfm
CJ(caiib = flow through orifice at calibration conditions, cfm
APPENDIX B 63
-------
Plant
Location -
Date
Test No..
Position
Time,
min.
ORIFICE DATA"
Desired Flow
(An x VJ, cfm
(AP0),
n. H20
(T,,),
°F
(Po),
in. Hg
METER DATA
Reading (QJ,
ft3
-------
o
I
.E 2°
ST
0 10
Q 8.0
LjJ 7l°
o: 6.0
CO 5.0
CO
£ 4.0
CL
3.0
2.0
1.0
0
/
/
/
/
f
f
'
/
/
/
/
/
i
1
.1 0.2 0.3 0.4 0.5 0.6 .7 .8 .9 1.0 2.0 3
FLOW RATE (Q), cfm
Figure B4 — Typical orifice calibration curve at 70°F and 29.9 in. Hg.
A sample calculation illustrates the procedure. Assume T0 = 100°F,
P0 = 2 in. Hg, MW = 29.0, and Pb = 29.9 in. Hg. Desired sampling rate at
70°F is 1 ft3/min or 1.05 ft3/min at 100°F (the stack temperature). Stack
velocity measured by pitot tube measurements was 1350 ft/min. The sample
nozzle area is then equal to 1'P5nf^/m^n = °-778 x 10~3 ft2- The area of the
probe selected was 0.8 x 10~3 ft2
The required flow at the sampling point is the stack velocity times the
probe area or 1350 ft/min x 0.8 x 10-3 ft* = 1.08 ft3/min at stack temperature
and pressure.
The corresponding orifice pressure drop at this flow is obtained by (1)
entering the orifice calibration chart at the desired gas volume and reading
the orifice pressure drop and (2) converting this pressure drop to conditions
under which the orifice will operate.
APPENDIX B
65
-------
For example,
1, Enter chart at 1.08 cfm and read AP = 6.5 in. at calibration con-
ditions.
2. AP0 = 6.5 in. x||g-x^|^-x|M.= 5.74 in. at orifice conditions.
Desired orifice setting is then 5.74 in. at this sampling point.
Sample Collection
Place two thicknesses of fiberglass filter paper in the glass filter holder or
firmly pack filter tube with glass wool to a depth of 2 inches, depending on
which type of filtering system is used. Check the packing by drawing air
through the train at about 1 cfm. A pressure drop of about 3 in. Hg indicates
sufficient fiber wool packing.
Pressure check the train by plugging the probe and drawing a vacuum of
6 in. Hg. Close the line leading from the train; the vacuum should remain at
6 in. Hg if the train is leakproof. Slowly remove plug from probe to release
vacuum and open line leading from train.
Close insulated door on sampling train and heat collection apparatus to
10°F above stack temperature. Blower should be ON whenever box is hot.
Regulate temperature with the thermostat on front of box.
Heat probe by wrapping it with electrical heating tape over its entire
exposed length.
When sample box reaches operating temperature, sampling can begin.
During testing, record all pertinent data on the data sheet. Compute the
desired flow and the corresponding pressure drop before sampling begins.
Normally a sample collection period of 20 to 30 minutes at a sampling
rate of approximately 1 cfm should be sufficient. If expected acid-mist load-
ings are high, i.e. 50 mg per scf, it is possible to overload the glass filter media
regardless of which type is used. In any case, the glass tubing downstream
of the filter should be inspected often. Any carryover of acid mist will be
indicated by droplets or liquid in the tubing.
Sample Analysis
When sampling is completed, allow train to cool. Remove collected
sample from probe and cyclone by rinsing with distilled water and collecting
washings in a 500-ml beaker. Add five drops of phenolphthalein indicator
solution and titrate with a standardized NaOH solution. For lower acid mist
loadings of 0.5 to 50 mg/scf, use an NaOH solution of about 0.01 to 0.1N.
For higher loadings, use a normality of about 1.0.
Remove the filter paper or glass wool from its holder and place in a
beaker. Rinse the cyclone outlet line and the glass filter holder with distilled
water and add this .washing to the beaker with the filter. Add enough dis-
tilled water to thoroughly remove all of the acid mist from the filter and
form a slurry. Stir the solution of paper or glass wool and water vigorously
for 15 to 20 minutes to insure a uniform mixture. Vigorous stirring should
also be employed during the titration with NaOH solution to determine an
accurate end point. When glass wool is used as a filtering medium, a stainless
steel stirring rod is recommended for stirring the rather thick, fluffy mixture
of glass wool and water; many glass rods have been broken.
There are 49 mg H2SO4 per cc of l.ON NaOH solution. Therefore,
(cc NaOH) (N NaOH) (49) = mg H2SO4.
66
APPENDIX B
-------
Take duplicate samples. Run blank titration with the filter medium used,
because NaOH may be needed to neutralize the medium.
MONSANTO COMPANY PROCEDURES FOR CONTACT
SULFURIC ACED PLANTS
Reich Test for Sulfur Dioxide (Not for use in air-quench plants)
Entrance Gas Test — Flush the sample line thoroughly with gas before
the test to insure getting a sample representative of operation at the time
that the test is being made.
Fill the shaker bottle approximately two-thirds full of water and add
about 5 ml of starch solution. Add 10 ml of N/10 iodine to the bottle by
pipette, after first bringing the solution to a faint blue color by adding one
or two drops of iodine solution. It is preferable to use the same water with
starch indicator in the shaker bottle for a number of determinations. Either
acidify new water in the shaker bottle with two drops of acid or repeat the
first determination to obtain a good reading.
With all clamps and stopcocks closed, place the rubber stopper in the
test bottle. Adjust the water level in a 250-cc burette to the "zero mark'' by
raising the water bottle with the glass stopcocks at the top and bottom of the
burette open. Then close the top stopcock and place the water bottle back on
the table. Make sure that all connections in the apparatus are tight.
Open the clamp on the sampling tube, adjusting it so that the gas bubbles
pass slowly through the solution in the bottle. Shake the bottle continuously
when gas is bubbling in to insure complete absorption of SO2. Continue until
the solution has changed to the same faint blue color obtained previously. Be
careful not to overrun the end point.
Close the clamp on the sampling line tightly when the end point has
been reached. Raise the water bottle so that its water level is balanced
against the water level in the burette, and then note the amount of air that
has been displaced in the burette. Note the temperature on the thermometer.
Values for entrance gas are given in Table Bl; refer to the column headed
by the temperature nearest that noted during the test. Follow down this
column to find the number nearest to the measured volume of air in the
cylinder. Then read the corresponding percent SO2 from the table. For
example, if the temperature is 30 °C and the measured volume is 145 ml,
then the strength of the gas is 8.0 percen't.
Exit Gas Test — Leave the water aspirator that maintains suction on the
exit gas sampling line running at all times to insure a representative sample
of gas. If gas is flowing through the line, a slight suction will show on the
manometer.
Now, in the exit gas test apparatus, repeat the procedure used for the
entrance gas test except use 10 ml of N/100 iodine solution instead of N/10
iodine solution. Note the volume of air displaced and the temperature as
before, then refer to the exit gas values in Table B2 for the percent SO2.
Barometric correction factors are given in Table B3; normal barometer read-
ings for various altitudes, in Table B4.
Conversion Efficiency — Refer to Table B5 for the percentage conversion
efficiency. For example, if the entrance gas is 8.0 percent and the exit gas is
0.22 percent, the conversion efficiency is f" percent.
Solutions — The solution of N/100 iodine solution may be prepared with
sufficient accuracy by measuring 100 ml of the standardized N/10 iodine
APPENDIX B 67
-------
TABLE Bl. REICH TEST FOR SO2 IN ENTRANCE GAS
N
(Solution:
Gas volume, ml.
°C
%SO2
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
3.8
4.0
4.2
4.4
4.6
4.8
5.0
5.2
5.4
5.6
5.8
6.0
6.2
6.4
6.6
6.8
7.0
7.2
7.4
7.6
5°
1112
925
791
691
613
550
499
457
421
390
363
340
319
300
284
269
256
244
233
222
213
204
196
189
182
176
170
164
159
154
148
145
141
137
10°
1137
945
808
706
626
562
510
467
430
398
371
347
326
307
290
275
261
249
238
228
218
209
201
193
186
179
173
167
162
157
152
148
143
139
15°
1162
967
827
722
640
575
522
477
440
407
379
355
333
314
297
281
267
255
243
232
223
214
205
197
190
183
177
171
166
160
155
151
146
142
J.U CC J^Q - i)
, at indicated temperature,
20°
1190
990
846
739
656
589
534
489
450
417
388
363
341
322
304
288
274
261
249
238
228
219
210
202
195
188
181
175
170
164
159
154
150
146
25°
1221
1015
868
758
673
604
548
501
462
428
398
373
350
330
312
296
281
267
255
244
234
224
216
207
200
193
186
180
174
169
163
158
154
149
30°
1255
1043
892
779
691
621
563
515
474
440
409
383
360
339
320
304
289
275
262
251
240
231
222
213
205
198
191
185
179
173
168
163
158
154
°C
35°
1294
1076
921
804
713
640
581
531
489
453
422
395
371
350
331
313
298
284
271
259
248
238
229
220
212
204
197
191
185
179
173
168
163
158
40°
1340
1114
953
832
738
663
601
550
507
469
437
409
384
362
342
324
308
294
280
268
257
246
237
228
219
212
204
197
191
185
179
174
169
164
68
APPENDIX B
-------
TABLE Bl (Continued)
Gas volume, ml, at indicated temperature, °C
°c
%S02
7.8
8.0
8.2
8.4
8.6
8.8
9.0
9.2
9.4
9.6
9.8
10.0
10.2
10.4
10.6
10.8
11.0
11.2
11.4
11.6
11.8
Formula used
_ f
5°
133
129
126
123
120
117
114
111
108
106
103
101
99
97
95
93
91
89
87
86
84
10"
135
132
129
125
122
119
116
113
111
108
106
103
101
99
97
95
93
91
89
88
86
15°
138
135
131
128
125
122
119
116
113
111
108
105
103
101
99
97
95
93
91
90
88
20°
142
138
134
131
128
125
122
119
116
113
111
108
106
104
101
99
97
95
93
92
90
25°
145
141
138
135
131
128
125
122
119
116
114
111
109
106
104
102
100
98
96
94
92
30°
149
145
141
138
134
131
128
125
122
119
117
114
112
109
107
105
103
101
99
97
95
35°
154
150
146
142
138
136
132
129
126
123
120
118
115
113
110
108
106
104
102
100
98
40°
160
155
151
148
144
140
137
134
130
127
130
122
119
117
114
112
110
107
105
103
101
in making calculations:
1094.4
B — W
^
760 (1
\ t
where B = barometric pressure, mm Hg
C = gas collected, cc
t = temperature of gas, °C
W = aqueous vapor pressure at temperature t, mm Hg
x = SO2 in gas, %
Percentages of SO2 not listed in the table may be calculated by use of the
factor (K), given fn Table B3, in this formula:
1094.4
N.
(for 10 cc -w I)
CK + 10.944
Where more accurate results are desired for the value of (K) than to the
nearest 10 mm Hg and the nearest 5°C, interpolate in Table B3.
The values in Table Bl are calculated for a barometric pressure of 760 mm
Hg. See Table B3 for corrections for other pressures.
APPENDIX B
69
-------
TABLE B2. REICH TEST FOR SO2 IN EXIT GAS
N
(.solution:
Gas volume, ml
°C
%SO2
0.05
0.10
0.11
0.12
0.13
0.14
0.15
0.16
0.17
0.18
0.19
0.20
0.22
0.24
0.25
0.26
0.28
0.30
0.32
0.34
0.35
0.36
0.38
0.40
0.45
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
5'
2245
1123
1021
936
863
802
748
700
658
624
591
560
511
467
448
431
400
373
350
330
320
311
295
279
248
223
203
186
171
159
148
139
131
123
117
111
10°
2297
1147
1043
956
882
819
764
713
673
636
603
573
520
477
458
440
408
381
358
337
327
318
302
286
254
228
207
190
175
162
152
142
133
126
119
113
15°
2347
1172
1067
978
903
838
781
733
692
650
617
586
533
488
468
451
418
390
366
345
334
326
308
292
259
233
212
194
179
166
155
145
137
129
122
116
, at indicated temperature
20°
2403
1201
1092
1001
924
858
800
753
705
666
631
600
547
501
479
463
428
399
375
353
342
334
315
299
266
239
217
199
183
170
159
149
140
132
125
119
25°
2460
1232
1120
1026
948
880
820
769
723
683
647
615
561
513
492
473
440
409
384
362
351
342
324
307
272
245
223
204
188
174
163
152
143
135
128
122
30°
2537
1266
1152
1055
974
904
844
792
743
705
666
632
575
528
505
488
451
421
395
372
361
352
332
315
280
252
229
210
193
179
167
157
147
139
132
125
, °C
35°
2616
1307
1188
1088
1004
932
870
815
770
724
688
652
594
543
521
501
467
434
407
384
372
363
343
325
284
260
236
216
199
185
173
162
152
143
136
129
40°
2707
1353
1229
1127
1040
965
901
847
798
749
710
675
613
563
540
520
483
449
421
397
385
375
355
337
299
269
244
224
206
192
179
167
157
149
141
134
70 APPENDIX B
-------
TABLE B2 (Continued)
Formula used in making calculations:
109.44
x =
B —W
C ^ 760 (1 + 0.00366t) J + 1.0944
where B = barometric pressure, mm Hg
C = gas collected, cc
t = temperature of gas, °C
W = aqueous vapor pressure at temperature t, mm Hg
x = SO2 in gas, %
Percentages of SO2 not listed in the table may be calculated by use of the
factor (K), given in Table B3, in this formula:
109.44 N
x = CK + 1.0944 (for 10 cc TOT X)
Where more accurate results are desired for the value of (k) than to the
nearest 10 mm Hg and the nearest 5°C, interpolate in Table B3.
The values in Table B2 are calculated for a barometric pressure of 760 mm
Hg. See Table B3 for corrections for other pressures.
APPENDIX B 71
-------
TABLE B3. BAROMETRIC CORRECTION FACTORS FOR REICH TEST
Pressure
mm Hg
760
750
740
730
720
710
700
690
680
670
660
650
640
630
620
610
600
590
580
570
560
550
540
530
520
510
Temperature, C°
5°
0.974
0.961
0.958
0.935
0.922
0.909
0.897
0.882
0.870
0.857
0.844
0.832
0.819
0.806
0.793
0.776
0.767
0.754
0.741
0.728
0.715
0.702
0.689
0.676
0.664
0.651
10°
0.953
0.940
0.928
0.915
0.902
0.890
0.877
0.864
0.852
0.839
0.826
0.813
0.801
0.788
0.775
0.762
0.750
0.737
0.725
0.712
0.699
0.686
0.674
0.661
0.648
0.636
15°
0.932
0.919
0.907
0.895
0.882
0.870
0.857
0.845
0.832
0.820
0.807
0.795
0.782
0.770
0.757
0.745
0.732
0.720
0.707
0.695
0.683
0.670
0.658
0.645
0.633
0.620
20°
0.910
0.898
0.886
0.873
0.861
0.849
0.837
0.825
0.812
0.800
0.788
0.775
0.763
0.751
0.739
0.726
0.714
0.702
0.690
0.677
0.665
0.653
0.641
0.628
0.616
0.604
25°
0.887
0.875
0.863
0.851
0.839
0.827
0.815
0.803
0.791
0.779
0.767
0.755
0.743
0.731
0.719
0.707
0.695
0.683
0.670
0.658
0.646
0.634
0.622
0.610
0.598
0.586
30°
0.863
0.851
0.840
0.828
0.816
0.804
0.792
0.780
0.769
0.757
0.745
0.733
0.721
0.709
0.697
0.686
0.674
0.662
0.650
0.638
0.626
0.614
0.603
0.591
0.579
0.567
35°
0.837
0.825
0.814
0.802
0.790
0.779
0.767
0.756
0.744
0.732
0.721
0.709
0.697
0.686
0.674
0.662
0.651
0.639
0.627
0.616
0.604
0.592
0.581
0.569
0.557
0.546
40°
0.809
0.797
0.786
0.774
0.763
0.751
0.740
0.728
0.717
0.706
0.694
0.683
0.671
0.660
0.648
0.637
0.625
0.614
0.602
0.591
0.579
0.568
0.556
0.545
0.533
0.522
Entrance gas and exit gas values shown in Tables Bl and B2 were calculated
for a barometric pressure of 760 mm Hg. If a correction for barometric
pressure is desired, find the factor (K) in Table B3 that corresponds to the
temperature and barometric pressure of the test under consideration and
determine a corrected temperature by multiplying the factor (K) by the
temperature of the test under consideration. Then use Table Bl or B2,
applying this corrected temperature in place of the test temperature.
72
APPENDIX B
-------
TABLE B4. NORMAL BAROMETER READINGS FOR
VARIOUS ALTITUDES
Altitude, Pressure,
feet mm Hg
0 760
500 746
1000 733
1500 720
2000 707
2500 694
3000 681
3500 669
4000 656
4500 644
5000 632
5500 621
6000 609
6500 598
7000 586
7500 575
8000 564
8500 554
9000 543
9500 533
10000 523
70
APPENDIX B
-------
TABLE B5 SO,, CONVERSION CHART FOR SULFUR-BURNING
PLANTS WITH NO AIR QUENCH
Percentage of
SO2 in
entrance .
gas, %
3.5
4.0
4.2
4.4
4.6
4.8
5.0
5.2
5.4
5.6
5.8
6.0
6.2
6.4
6.6
6.8
7.0
7.2
7.4
7.6
7.8
8.0
8.2
8.4
8.6
8.8
9.0
9.2
9.4
9.6
9.8
10.0
10.2
10.4
10.6
10.8
11.0
11.2
11.4
11.6
11.8
0.05
98.8
98.9
98.9
99.0
99.0
99.1
99.1
99.1
99.2
99.2
99.2
99.3
99.3
99.3
99 3
99.3
99 4
99.4
99.4
99.4
99 5
99.5
99.5
99 5
99 5
99.5
99.5
99.5
99.6
99.6
99.6
99.6
99.6
99.6
99.6
99.6
99.6
99.6
99.6
99.6
99.7
0.10
97.4
97.7
97.8
97.9
98.0
98.1
98.2
98.2
98.3
98.4
98.4
98.5
98.5
98.6
98 6
98.7
98 7
98.8
98.8
98.8
98 9
98.9
98.9
99 0
99 0
99.0
99.0
99.1
99.1
99.1
99.1
99.2
99.2
99.2
99.2
99.2
99.2
99.3
99.3
99.3
99.3
0.12
97.0
97.3
97.4
97.5
97.6
97.7
97.8
97.9
97.9
98.0
98.0
98.1
98.2
98.2
98 3
98.4
98 4
98.5
98 5
98.6
98 6
98 7
98 7
98 7
98 8
98.8
98.8
98.8
98 9
98 9
98.9
99.0
99.0
99.0
99.1
99.1
99.1
99.1
99.1
99.1
99.2
0.14
96.5
96.8
96.9
97.0
97.2
97.3
97.4
97.4
97.5
97.6
97.7
97.8
97.9
98.0
98 1
98.1
98 2
98.2
98 3
98.4
98 4
98.5
98 5
98 5
98 6
98.6
98 6
98.7
98 7
98 7
98.8
98.8
98.8
98.8
98.9
98.9
99.0
99.0
99.0
99.0
99.0
S02
0.16
96.1
96.4
96.6
96.7
96.8
96.9
97.0
97.1
97.3
97.4
97.5
97.6
97.7
97.8
97 9
97.9
98 0
98.0
98 1
98.2
98 2
98 2
98 3
98 3
98 4
98.4
98 5
98.5
98 5
98 6
98.6
98.6
98.7
98.7
98.7
98.7
98.8
98.8
98.8
98.9
98.9
SO, converted to
S03
in exit gas
0.18
95.5
95.9
96.1
96.3
96.4
96.6
96.7
96.7
96.9
97.0
97.2
97.4
97.4
97.5
97 6
97.6
97 8
97.8
97 9
98.0
98 0
98 0
98.1
98 1
98 2
98.2
98 3
98.3
98 3
98 4
98.4
98.5
98.5
98.5
98.6
98.6
98.6
98.7
98.7
98.7
98.7
0.20
94.7
95.3
95.5
95.7
95.9
96.1
96.3
96.4
96.6
96.7
96.9
97.0
97.1
97.2
97.3
97.4
97 4
97.5
97 6
97.7
97 7
97 8
97.9
97 9
98 0
98.0
98 1
98.1
98 2
98 2
98.3
98.3
98.3
98.4
98.4
98.4
98.5
98.5
98.5
98.6
98.6
0.22
94.2
94.8
95.1
95.3
95.5
95.7
95.9
96.1
96.3
96.4
96.6
96.7
96.9
97.0
97.1
97.2
97.2
97.3
97 4
97.5
97 5
97 6
97.7
97 7
97 8
97.8
97 9
97.9
98 0
98 1
98.2
98.2
98.2
98.2
98.2
98.3
98.3
98.3
98.4
98.4
98.5
0.24
93.6
94.3
94.6
94.9
95.1
95.2
95.5
95.7
95.9
96.1
96.3
96.4
96.5
96.7
96.8
96.9
97.0
97.0
97.1
97.2
97 3
97 4
97.4
97 5
97 5
97.6
97 7
97.7
97 8
97 9
97.9
98.0
98.0
98.0
98.1
98.1
98.2
98.2
98.2
98.3
98.3
0.26
93.2
93.9
94.2
94.5
94.7
94.8
95.1
9b.3
95.5
9b.7
95.9
96.0
96.1
96.3
96.4
96.5
96.6
96.7
96.8
96.9
97 0
97.1
97 2
97 3
97 4
97.4
97 5
97.5
97 6
97 7
97.7
97.8
97.8
97.9
97.9
98.0
98.0
98.0
98.1
98.1
98.2
0.28
92.6
93.4
93.8
94.1
94.3
94.5
94.7
95.0
95.2
95.4
95.6
95.7
95.9
96.1
96.2
96.2
96.4
96.5
96.6
96.7
96 8
96.9
97.0
97 1
97 2
97.2
97.3
97.4
97 4
97.5
97.6
97.6
97.7
97.7
97.8
97.9
97.9
97.9
98.0
98.0
98.0
0.30
92.1)
92.9
93.3
93.6
93.9
94.2
94.4
94.7
94.9
95.1
95.3
95.4
95.6
95.8
959
96.0
962
96.3
96.4
96.5
966
96.7
96.8
96 9
97 0
97.0
97.1
97.2
97.2
97.3
97.4
97.4
97.5
97.6
97.6
97.7
97.7
97.8
97.8
97.9
179
- % conversion of SO, to SO3 a = % SO2 in entrance gas
74 APPENDIX B
-------
TABLE B5 (Continued)
SO2 in
entrance
gas, %
3.5
4.0
4.2
4.4
4.6
4.8
5.0
5.2
5.4
5.6
5.8
6.0
6.2
6.4
6.6
6.8
7.0
7.2
7.4
7.6
7.8
8.0
8.2
8.4
8.6
8.8
9.0
9.2
9.4
9.6
9.8
10.0
10.2
10.4
10.6
10.8
11.0
11.2
11.4
11.6
11.8
b =
Percentage of SO2 converted
SO, in exit
0.32
91.5
92.4
92.8
93.2
93.5
93.8
94.1
94.4
94.6
94.8
95.0
95.2
95.4
95.5
95.7
95.9
95.9
96.1
96.2
96.3
96.4
96.5
96.6
96.7
96.8
96.8
96.9
97.0
97.1
97.2
97.3
97.3
97.3
97.4
97.4
97.5
97.6
97.6
97.7
97.7
97.7
% SO,
0.34
91.0
92.0
92.4
92.8
93.1
93.4
93.7
94.0
94.2
94.5
94.7
94.9
95.1
95.2
95.4
95.6
95.6
95.8
95.9
96.0
96.1
96.2
96.3
96.5
96.5
96.6
96.7
96.8
96.9
97.0
97.1
97.1
97.1
97.2
97.3
97.3
97.4
97.4
97.5
97.5
97.6
0.36
90.5
91.5
92.0
92.3
92.7
93.0
93.3
93.6
93.9
94.2
94.4
94.6
94.8
94.9
95.1
95.3
95.4
95.6
95.7
95.8
95.9
96.0
96.1
96.3
96.3
96.4
96.5
96.6
96.7
96.8
96.9
96.9
97.0
97.1
97.1
97.2
97.3
97.3
97.4
97.4
97.5
0.38
89.9
91.0
91.5
92.0
92.3
92.6
93.0
93.3
93.6
93.8
94.1
94.3
94.5
94.6
94.8
95.0
95.2
95.3
95.5
95.6
95.7
95.8
95.9
96.0
96.1
96.2
96.3
96.4
96.5
96.6
96.7
96.8
96.8
96.9
97.0
97.0
97.1
97.2
97.2
97.3
97.3
0.40
88.3
90.5
91.0
91.5
91.9
92.2
92.6
92.9
93.2
93.4
93.7
93.9
94.1
94.3
94.5
94.7
94.9
95.0
95.2
95.3
95.5
95.6
95.7
95.8
95.9
96.0
96.2
96.2
96.3
96.4
96.5
96.6
96.7
96.7
96.8
96.9
96.9
97.0
97.1
97.1
97.2
0.50
86.3
88.2
88.8
89.3
89.8
90.3
90.7
91.1
91.4
91.8
92.1
92.4
92.6
92.9
93.1
93.4
93.6
93.8
94.0
94.1
94.3
94.5
94.6
94.8
94.9
95.0
95.2
95.3
95.4
95.5
95.6
95.7
95.8
95.9
96.0
9611
96.2
96.3
96.3
96.4
96.5
gas
0.60
83.7
85.8
86.5
87.2
87.8
88.3
88.8
89.3
89.7
90.1
90.5
90.8
91.2
91.5
91.7
92.0
92.3
92.5
92.7
93.0
93.2
93.3
93.5
93.7
93.9
94.0
94.2
94.3
94.5
94.6
94.7
94.8
95.0
95.1
95.2
95.3
95.4
95.5
95.6
95.7
95.8
to SO
0.70
80.8
83.4
84.2
85.0
85.7
86.3
86.9
87.5
88.0
88.4
88.9
89.3
89.7
90.0
90.4
90.7
91.0
91.2
91.5
91.8
92.0
92.2
92.4
92.6
92.8
93.0
93.2
93.4
93.5
93.7
93.8
94.0
94.1
94.3
94.4
94.5
94.6
94.7
94.9
95.0
95.1
;t
0.80
78.0
81.0
81.9
82.8
83.6
84.3
85.0
85.6
86.2
86.8
87.3
87.7
88.2
88.6
89.0
89.3
89.6
90.0
90.3
90.6
90.8
91.1
91.4
91.6
91.8
92.0
92.2
92.4
92.6
92.8
93.0
93.1
93.3
93.4
93.6
93.7
93.9
94.0
94.1
94.2
94.4
in exit gas ^ lnn / ,,a ,., It ~
0.90
75.2
78.6
79.7
80.6
81.5
82.4
83.1
83.8
84.5
85.1
85.6
86.2
86.7
87.1
87.6
88.0
88.3
88.7
89.0
89.4
89.7
90.0
90.3
90.5
90.8
91.0
91.2
91.5
91.7
91.9
92.1
92.2
92.4
92.6
92.7
92.9
93.1
93.2
93.4
93.5
93.6
1.00
72.7
76.1
77.4
78.5
79.5
80.4
81.2
82.0
82.7
83.4
84.0
84.6
85.2
85.7
86.1
86.6
87.0
87.4
87.8
88.2
88.5
88.8
89.2
89.5
89.7
90.0
90.2
90.5
90.7
91.0
91.2
91.4
91.6
91.8
91.9
92.1
92.3
92.4
92.6
92.8
92.9
Sab \\
APPENDIX B '5
-------
solution in a graduated cylinder and then diluting this with water to 1000 ml
in a 1000-ml graduated cylinder.
Keep all iodine solutions in brown bottles in a cool place. Always replace
the glass stoppers as soon as possible.
Starch solution sours quickly because of bacterial and mold growth, and
then turns the iodine solution brown instead of blue so that a clear end point
is not obtained. Prepare fresh starch solutions weekly, or more often in warm
weather. A starch solution prepared as follows, however, will keep for
months without deterioration or loss of sensitivity.
Dissolve 2 grams of powdered starch in 400 ml of cold distilled water.
Dissolve 6 grams of caustic soda in a small amount of distilled water and add
to the starch solution, stirring until dissolved. Let stand 1 hour for complete
solution; the liquid should be uniformly translucent. Neutralize the alkali
by adding concentrated hydrochloric acid (about 15 ml) until the solution
is just acid to litmus paper. A slight excess of acid is beneficial in preserving
the indicator.
Reich Test for Sulfur Dioxide (For sulfur-burning plants of air-quench type)
Entrance Gas Test — Flush the sample line thoroughly with gas before
the test to insure getting a sample representative of operation at the time that
the test is being made.
Fill the shaker bottle approximately two-thirds full of water and add
about 5 ml of starch solution. Add 10 ml of N/10 iodine to the bottle by
pipette, after first bringing the solution to a faint blue color by adding one
or two drops of iodine solution. It is preferable to use the same water with
starch indicator in the shaker bottle for a number of determinations. Either
acidify new water in the shaker bottle with two drops of acid or repeat the
first determination to obtain a good reading.
With all clamps and stopcocks, place the rubber stopper in the test
bottle. Adjust the water level in the 250-cc burette to the "zero mark'' by
raising the water bottle with the glass stopcocks at the top and bottom of the
burette open. Then close the top stopcock and place the water bottle back on
the table. Make sure that all connections in the apparatus are tight.
Open the clamp on the sampling tube, adjusting it so that the gas bubbles
pass slowly through the solution in the bottle. Shake the bottle continuously
when gas is bubbling in to insure complete absorption of SO2. Continue until
the solution has changed to the same faint blue color obtained before. Be
careful not to overrun the end point.
Close the clamp on the sampling line tightly when the end point has
been reached. Raise the water bottle so that its water level is balanced against
the water level in the burette, then note the amount of air that has been
displaced in the burette. Note the temperature on the thermometer. Refer
to Table Bl and to the column headed by the temperature nearest that noted
during the test. Follow down this column to find the number nearest to the
measured volume of air in the cylinder. Then read the corresponding percent
SO2 from the table. For example, if the temperature is 30°C and the measured
volume is 145 ml then the strength of the gas is 8.0 percent.
Exit Gas Test — Leave the water aspirator that maintains suction on the
exit gas sampling line running at all times to insure a representative sample
of gas. If gas is flowing through the line, a slight suction will show on the
manometer.
76 APPENDIX B
-------
Now, in the exit gas apparatus, repeat the procedure used for the entrance
gas test except use 10 ml of N/100 iodine solution instead of N/10 iodine
solution. Note the volume of air displaced and the temperature as before,
then refer to Table B2 for the percent SO2.
Oxygen in Exit Gas — Make sure all rubber connections and stopcocks
on the Orsat apparatus are tight. Adjust the level of the potassium pyrogallol
solution so that the potassium pyrogallol just enters the small portion of the
tube under the stopcock. Connect the Orsat to the exit gas sample line. Set
the three-way cock to exhaust the atmosphere, then raise the leveling bottle
until the water fills the sampling type. While the sample tube is still full of
water, turn the three-way cock, open it to the gas sample line, then lower the
leveling bottle and draw gas into the sample tube. Repeat this procedure
about three times to be" certain the sample is representative. The last sample
must be measured very carefully. The sample line is under slight negative
pressure; to be certain that the sample contains exactly 100 cc of gas, draw
in about 110 cc and then turn the three-way cock to blank the sample line.
Now raise the leveling bottle very slowly to the 100-cc mark and exhaust
the excess gas to the atmosphere.
Turn the three-way cock so that the gas sample will flow into the tube
filled with potassium pyrogallol solutio" By raising and lowering the leveling
bottle you will force the gas through the solution, which will absorb the oxy-
gen that was in the gas. (Be careful not to force any of the solution over into
the sample tube.) After the gas sample has been bubbled through the potas-
sium pyrogallol solution several times, adjust the solution to starting level
and close the stopcock. Raise or lower the leveling bottle so that it is bal-
anced against the water in the sample tube. The reading on the calibrated
sample tube will be the percentage of O., that was in the sample, usually 6
to 12 percent.
NOTE: Allowance for SO2 in the sample is not necessary because the
SO., will be absorbed in the leveling bottle water. If mercury is used in the
leveling bottle, then the percent SO2 obtained in the exit gas test must be
subtracted from the Orsat reading to get percent O.,.
Conversion Efficiency — Refer to Table B6 for the percentage conversion
efficiency. For example, if the percentages in the exit gas are 8 percent O.,
and 0.20 percent SO2, the conversion efficiency is 98.2 percent.
Solutions — The solution of N/100 iodine solution may be prepared with
sufficient accuracy by measuring 100 ml of the standardized N/10 iodine
solution in the graduated cylinder and then diluting this with water to 1000
ml in a 1000-ml graduated cylinder.
Keep all iodine solutions in brown bottles and in a cool place. Always
replace the glass stoppers as soon as possible.
Starch solution sours quickly because of bacterial and mold growth, and
then turns the iodine solution brown instead of blue so that a clear end point
is not obtained. Prepare fresh starch solutions weekly, or even more often
in warm weather. A starch solution prepared as follows, however, will keep
for months without deterioration or loss of sensitivity.
Dissolve 2 grams of powdered starch in 400 ml of cold distilled water.
Dissolve 6 grams of caustic soda in a small amount of distilled water and
add to the starch solution, stirring until dissolved. Let stand 1 hour for
complete solution; a uniform translucent liquid should be obtained. Neutral-
ize the alkali by adding concentrated hydrochloric acid (about 15 ml) until
the solution is just acid to litmus paper. A slight excess of acid is beneficial
in preserving the indicator.
APPENDIX B 77
-------
TABLE B6. SO., CONVERSION CHART FOR SULFUR-BURNING
PLANTS WITH AIR QUENCH
Percentage
O.
e:
ga:
6
6.
6.
6.
6,
7.
7
7,
7
7,
8.
8
8
8
8
9
, in
3, %
.0
.2
.4
.6
.8
.0
.2
.4
.6
.8
.0
.2
.4
.6
.8
.0
9.2
9
9.
.4
.6
9.8
10.
10.
10.
,0
,2
.4
10.6
10.
11.
11.
11.
11.
11.
12.
12.
12
12.
.8
.0
.2
,4
.6
.8
,0
.2
.4
6
12.8
13.0
of SO,
, converted to
SO,
SO., in exit gases, %
0.10
99.2
99.2
99.2
99.2
99.2
99.2
99.2
99.2
99.1
99.1
99.1
99.1
99.1
99.0
99.0
99.0
99.0
99.0
99.0
98.9
98.9
98.9
98.9
98.9
99.8
98.8
98.8
98.8
98.7
98.7
98.7
98.7
98.6
98.6
98.6
98.5
0.12
99.0
99.0
99.0
99.0
99.0
99.0
99.0
99.0
98.9
98.9
98.9
98.9
98.9
98.8
98.8
98.8
98.8
98.8
98.8
98.8
98.7
98.7
98.7
98.7
98.6
98.6
98.6
98.5
98.5
98.4
98.4
98.4
98.3
98.3
98.3
98.2
0.14
98.9
98.9
98.9
98.8
98.8
98.8
98.8
98.8
98.7
98.7
98.7
98.7
98.7
98.6
98.6
98.6
98.6
98.6
98.6
98.6
98.5
98.5
98.4
98.4
98.4
98.3
98.3
98.3
98.2
98.2
98.2
98.1
98.1
98.0
98.0
97.9
0.16
98.7
98.7
98.7
98.7
98.7
98.7
98.7
98.7
98.6
98.6
98.6
98.6
98.5
98.5
98.4
98.4
98.4
98.3
98.3
98.3
98.2
98.2
98.2
98.2
98.1
98.1
98.1
98.0
98.0
97.9
97.9
97.9
97.8
97.8
97.7
97.6
0.18
98.6
98.6
98.6
98.5
98.5
98.5
98.5
98.5
98.4
98.4
98.4
98.4
98.3
98.3
98.2
98.2
98.2
98.1
98.1
98.1
98.0
98.0
97.9
97.9
97.9
97.8
97.8
97.8
97.7
97.7
97.7
97.6
97.5
97.5
97.4
97.3
0.20
98.4
98.4
98.4
98.3
98.3
98.3
98.3
98.3
98.2
98.2
98.2
98.2
98.1
96.1
98.0
98.0
98.0
97.9
97.9
97.9
97.8
97.8
97.7
97.7
97.7
97.6
97.6
97.5
97.5
97.4
97.4
97.3
97.2
97.2
97.1
97.0
0.22
98.3
98.3
98.2
98.2
98.1
98.1
98.1
98.1
98.0
98.0
98.0
98.0
97.9
97.9
97.8
97.8
97.8
97.7
97.7
97.7
97.6
97.6
97.5
97.5
97.5
97.4
97.4
97.3
97.2
97.2
97.1
97.0
96.9
96.9
96.8
96.7
0.24
98.1
98.1
98.1
98.0
98.0
98.0
98.0
97.9
97.9
97.8
97.8
97.8
97.7
97.7
97.6
97.6
97.6
97.5
97.5
97.5
97.4
97.4
97.3
97.3
97.2
97.1
97.1
97.0
97.0
96.9
96.9
96.8
96.7
96.6
96.5
96.4
0.26
98.0
98.0
97.9
97.9
97.8
97.8
97.8
97.8
97.7
97.7
97.7
97.6
97.6
97.5
97.5
97.4
97.4
97.3
97.3
97.2
97.2
97.1
97.1
97.0
97.0
96.9
96.9
96.8
96.7
96.7
96.6
96.5
96.4
96.4
96.3
96.2
0.28
97.8
97.8
97.8
97.7
97.7
97.7
97.7
97.6
97.6
97.5
97.5
97.4
97.4
97.3
97.3
97.2
97.2
97.1
97.1
97.0
97.0
96.9
96.9
96.8
96.7
96.6
96.6
96.5
96.5
96.4
96.4
96.3
96.2
96.1
96.0
95.9
78 APPENDIX B
-------
TABLE B6 (Continued)
O2in
exit
gas, %
6.0
6.2
6.4
6.6
6.8
7.0
7.2
7.4
7.6
7.8
8.0
8.2
8.4
8.6
8.8
9.0
9.2
9.4
9.6
9.8
10.0
10.2
10.4
10.6
10.8
11.0
11.2
11.4
11.6
11.8
12.0
12.2
12.4
12.6
12.8
13.0
Percentage
of SO2 converted to
SO,
SO2 in exit gases, %
0.30
97.
97.
97.
97.
97.
97.
97.
97.
97.
,7
7
6
6
.5
5
5
.4
.4
97.3
97.
97
97
97
97
97
97
96
96
.3
.2
.2
.1
.1
.0
.0
.9
.9
96.8
96
96
.8
.7
96.7
96
.6
96.5
96
96
96
.4
.4
.3
96.2
96.2
96.
96.
,1
.0
95.9
95.8
95.7
95.
6
0.32
97.5
97.5
97.4
97.4
97.3
97.3
97.3
97.2
97.2
97.1
97.1
97.0
97.0
97.0
97.0
96.9
96.8
96.7
96.7
96.6
96.6
96.5
96.5
96.4
96.3
96.2
96.2
96.1
96.0
95.9
95.8
95.7
95.6
95.5
95.4
95.3
0.34
97.3
97.3
97.2
97.2
97.2
97.1
97.1
97.0
97.0
96.9
96.9
96.8
96.8
96.8
96.8
96.7
96.6
96.5
96.5
96.4
96.4
96.3
96.2
96.2
96.1
96.0
95.9
95.8
95.7
95.7
95.6
95.5
95.3
95.2
95.1
95.0
0.36
97.2
97.2
97.1
97.1
97.0
97.0
97.0
96.9
96.9
96.8
96.8
96.7
96.7
96.7
96.6
96.6
96.4
96.3
96.3
96.2
96.1
96.0
96.0
95.9
95.8
95.7
95.7
95.6
95.5
95.4
95.3
95.2
95.1
95.0
94.8
94.7
0.38
97.0
97.0
96.9
96.9
96.9
96.8
96.8
96.7
96.7
96.6
96.6
96.5
96.5
96.5
96.4
96.4
96.2
96.1
96.1
96.0
95.9
95.8
95.7
95.7
95.6
95.5
95.4
95.3
95.2
95.2
95.1
95.0
94.8
94.7
94.6
94.4
0.40
96.8
96.8
96.7
96.7
96.7
96.6
96.6
96.5
96.5
96.4
96.4
96.3
96.3
96.2
96.2
96.1
96.0
95.9
95.9
95.8
95.7
95.6
95.5
95.5
95.4
95.3
95.2
95.1
95.0
94.9
94.8
94.7
94.5
94.4
94.2
94.1
.425
96.6
96.6
96.5
96.5
96.5
96.4
96.4
96.3
96.3
96.2
96.2
96.1
96.1
96.0
96.0
95.9
95.8
95.7
95.6
95.5
95.4
95.3
95.2
95.2
95.1
95.0
94.9
94.8
94.7
94.6
94.5
94.4
94.2
94.0
93.9
93.7
0.45
96.4
96.4
96.3
96.3
96.3
96.2
96.2
96.1
96.0
96.0
95.9
95.9
95.8
95.7
95.7
95.6
95.5
95.4
95.4
95.3
95.2
95.1
95.0
94.9
94.8
94.7
94.6
94.5
94.4
94.3
94.2
94.0
93.9
93.6
93.5
93.4
.475
96.2
96.2
96.1
96.0
96.0
95.9
95.9
95.8
95.8
95.7
95.7
95.6
95.6
95.5
95.5
95.4
95.3
95.2
95.1
95.0
94.9
94.8
94.7
94.6
94.5
94.4
94.3
94.2
94.0
93.9
93.8
93.7
93.5
93.3
93.2
93.1
0.50
96.0
96.0
95.9
95.8
95.8
95.7
95.7
95.6
95.5
95.5
95.4
95.4
95.3
95.2
95.2
95.1
95.0
94.9
94.8
94.7
94.6
94.5
94.4
94.3
94.2
94.1
94.0
93.9
93.7
93.6
93.5
93.3
93.2
93.0
92.9
92.7
APPENDIX B 79
-------
Methods for the preparation of 0.1 N iodine and starch solutions are as
follows:
Starch — Boil a mixture of 1 gram of soluble starch and 50 ml water.
Cool, add 0.5 gram potassium iodide, and dilute to 50 ml.
0 1 N Iodine — Dissolve 400 grams potassium iodide in about 2 liters of
hot water. Add 218 grams iodine and heat to effect solution. Dilute to about
15,800 ml. Let stand 1 month before cutting. Adjust the normality to between
0.0095 and 0.1005 using 25-ml portions. Store in a dark place until needed.
Keep two bottles prepared (not cut) in reserve.
Standardization — Standardize by withdrawing 45-ml portions from a
burette into a 500-ml iodine flask containing 30 ml cold water. Add 1 ml
concentrated HC1 and let stand in an ice bath until fumes are absorbed.
Titrate with 0.1 N sodium thiosulfate, swirling the contents of the flask con-
tinuously. When the solution becomes straw colored, add a few drops of
fresh starch solution. Continue the titration until 0.02 ml of the sodium
thiosulfate solution removes the blue color. Determine in triplicate.
Calculations •— Log N I = Log N Thio + Log ml Thio Log ml I ;
or Normality I., =
ml 1.,
Determination of Moisture Content of Acid-Dried Air Gas in Contact
Sulfuric Acid Plants
Choose a convenient sampling location on the pressure side of the blower
unless you wish to determine moisture content between the drying tower and
blower. A J/4-inch steel pipe with an all-iron gate valve closed to the flue
may be used for the sample connection. Before making a test, clean the line
thoroughly to remove any acid or acid sulfate that may have collected. An-
other suitable type of sampling connection may be made by welding a 1-inch
pipe coupling to the flue and extending a glass sample tube through it. The
sample tube may be held in place by means of a one-hole rubber stopper,
(see Figure B5).
THERMOMETER
ASPIRATOR OR
GAS PUMP
Figure B5 — Apparatus for determination of moisture content of acid-dried air or gas in contact
sulfuric acid plants.
80
APPENDIX B
-------
For removal of any acid particles or other foreign material from the
sample, connect a filter to the sample line. Either of two types of filter may
be used:
1. A Gooch-type filtering funnel (E. H. Sargent & Co., Cat. No. S-24485)
packed with acid-washed, ignited, dry asbestos supported on a per-
forated porcelain plate in the bottom of the funnel. The asbestos
should be packed tightly enough to function efficiently but not tightly
enough to seriously restrict the gas flow. If the air or gas contains an
appreciable amount of acid use two filters in series.
2. A Buchner-type, medium porosity, fritted-glass filter with a capacity
of 30 ml (Cat. L.P. 21, page 146, Corning Glass Works, Corning, New
York) may be used. The pressure drop through the glass filter may
be too great to allow a sufficient flow of gas through the testing equip-
ment without the use of a vacuum pump or aspirator.
Make the connection between the sample line and the filter with a
minimum length of rubber tubing or preferably with no rubber at all.
Allow several cubic feet of gas to flow through the sample line and filter
bulb so that the moisture in the system reaches equilibrium with the gas
sample. The gas flow may be regulated by the valve in the sample line and
also by a screw clamp in the line after the filter. After blowing out the line
and filter, close the clamp at the end of the filter to keep the line and filter dry.
Connect to the filter two moisture absorption bulbs accurately weighed in
grams to four decimal places. Nesbitt bulbs (E. H. Sargent & Co. Cat. S-22015)
are recommended because they can be closed easily and are large enough in
diameter to allow a relatively low gas velocity during the test. Large glass-
stopper U tubes are also satisfactory. The bulbs may be packed by three
methods:
1. Phosphorous pentoxide, the preferred absorbent, has the disadvantage
of "gas channeling" unless packed properly. The following method is
recommended. First place about % inch of glass wool in the bottom
of the Nesbitt bulbs. Then cut some glass wool into lengths V4 inch
or shorter and mix with P2O5 to coat the glass fiber. Pack this mixture
in the bulbs, using first a %-inch layer of the P2O5 alone, and then
alternating layers until the bulb is about three-quarters full. The final
layer should be glass wool alone to prevent blowing P2O5 from the
bulb. Close the stopcocks as soon as possible.
2. Pack the bulbs with a mixture of P2O5 and a carrier such as Drierite
(anhydrous calcium sulfate). This mixture is easy to handle and does
not "channel" easily.
3. Anhydrone (pure anhydrous magnesium per chlorate) may be used as
an absorbent, but it is recommended that only the first bulb be packed
with Anhydrone and the second with P2O5.
Tightly packed areas might obstruct the flow of gas and should be
avoided. Resistance through each bulb should be less than 10 inches water
gauge pressure when passing 5 cubic feet per hour. The gas is drawn down
the side tube and up through the bulb. Fasten the stopcocks with thin copper
wire to prevent blowing them out during the test. Use a minimum amount of
stopcock grease to prevent grease getting into the gas inlet and outlet arms.
If a loss in weight occurs in the second bulb, it is probably due to particles
of the absorbing material or of the glass wool being blown out of the bulb,
and the glass wool mat should be replaced.
APPENDIX B 81
-------
If the moisture test is run on SO2 gas rather than air, pass a lew cubic feet
of the gas to be sampled through the bulbs before they are weighed the first
time after being packed.
The bulbs should be connected by a short piece of rubber tubing, which
must at snugly and be clean and free from cracks.
Connect a flowmeter to the second moisture bulb; also provide a ther-
mometer for measuring the temperature and a manometer for measuring the
static pressure of the gas passing through the meter. Use a gas meter
(Sprague, Type 1A, Laboratory test meter, Cat. No. 16, p. 21, Sprague Meter
Company, Bridgeport, Conn.) or a calibrated orifice flowmeter.
Very slightly open the flow-regulation screw clamp between the filter
and bulbs, then open the stopcocks on the moisture bulbs. This procedure
keeps the bulbs under slight pressure so that they cannot absorb moisture
from the exit line to the flowmeter.
Allow the gas to flow through the apparatus at about 5 cubic feet per
hour. The total sample should be 15 to 20 cubic feet. Record the meter read-
ing, temperature, and pressure periodically. Unless a vacuum pump or aspir-
ator is used, the meter pressure will be barometric pressure. Maintain a
steady flow.
At the end of the test close the moisture bulbs and then the flow-
regulation screw clamp.
Reweigh the moisture bulbs. When the bulbs are weighed before and
after the test, they should be cleaned carefully and desiccated. At least 90
percent of the total increase in weight should occur in the first bulb. Use
the bulb until it is evident that the first bulb is not absorbing as much as 90
percent of the moisture. Then use the second bulb as the number one bulb,
and repack the first bulb for use as the second bulb. Weigh the bulbs immedi-
ately before and after the test.
Calculate the volume of sample as cubic feet at standard conditions.
Express the moisture as milligrams of water per cubic feet of dry gas at
standard conditions.
For interpretation and comparison of test results, it is essential to report
any pertinent operating data, including production rate and gas strength or
the air or gas volume, with the test results.
Determination of Acid Content of Acid-Dried Air or Gas in Contact
Sulfurie Acid Plants
Extend a right-angle glass sample tube into the flue approximately one-
third the distance across it. The end of the tube should face into the gas
stream. The tube should be of such diameter that when sampling at the
desired rate of 8 to 12 cubic feet per hour, the gas velocity entering the tube
is the same as the gas velocity in the flue. The velocity in the flue may be
calculated from the plant production rate and the gas strength or may be
determined by means of a pitot tube. The sampling connection may be made
by welding a 1-inch coupling into the flue. The sample tube may be held in
place by means of a one-hole rubber stopper (see Figure B6).
For removal of the acid particles from the sample, connect a series of
filters directly to the sample tube. Use either of two types of filters:
1. The preferred filter is the Buchner type, medium-porosity, fritted-
glass filter with capacity of 30 to 40 ml (Cat. L.P. 21, page 146, Corning
82
APPENDIX B
-------
Figure B6 — Apparatus for determination of acid content of acid-dried air or gas and exit gas
in contact sulfuric acid plants.
Glass Works, Corning, New York). Connect the filters by one-hole
rubber stoppers. Use two filters in series for acid-dried air or gas
and three filters in series for gas from the exit stack.
2. An alternative is a Gooch-type filtering funnel (E. H. Sargent & Co.
Cat. No. S-24485) packed with acid-washed, ignited, dry asbestos
supported on a perforated porcelain plate in the bottom of the funnel.
Pack the asbestos tightly enough to function efficiently without seri-
ously restricting gas flow. Use two or three filters in series for dry
air or gas, and four filters for exit stack gas. The end of the sample
tube and the end of the stem of each funnel should extend into the
asbestos of the following funnel. Make a blank acidity determination
on a portion of the asbestos before using it.
Glass filters are preferred because they are superior to asbestos filters
for mist removal and are simpler to use. The pressure drop through glass
filters is usually great enough to require the use of a vacuum pump or
aspirator to draw sufficient flow of gas through the testing equipment.
Connect a flow meter to the end of the filter train; also provide a ther-
mometer for measuring temperature and a manometer for measuring the
static pressure of the gas passing through the meter. Use a gas meter
(Sprague Type 1A Laboratory test meter, Cat. No. 16, page 21, Sprague Meter
Company, Bridgeport, Conn.) or a calibrated orifice flow meter.
To draw the gas sample from the flue through the test apparatus, connect
to the flow meter either a vacuum pump or an aspirator operated with air or
water. A vacuum pump or aspirator is not required for tests on dry air or
gas if the gas pressure is great enough to force the sample through the
apparatus.
Regulate the gas flow by a screw clamp in the sampling line either before
or after the filters, preferably after. If a vacuum pump or aspirator is used,
the flow-regulation screw clamp should be after the flow meter instead of
before or after the filters. If possible avoid the use of rubber connections in
the sample line to the filters.
APPENDIX B
83
-------
Allow the gas to flow through the apparatus at the calculated rate (8 to
10 cubic feet per hour). Record the meter reading, temperature, and pressure
periodically. Maintain a steady flow.
Continue the test on dry air for about 5 to 6 hours, or if the gas is sub-
stantially acid-free, for 24 hours. Continue the test on exit gas for about 3
to 4 hours (25 to 40 cubic feet).
Disconnect the flow meter at the end of the test. Carefully remove the
sample tube from the flue so that any acid that may have collected in the
tube is not lost.
Wash the acid from the inside of the sample tube.
Wash the filters, with suction, until the washings are acid-free. Combine
the washings with the sample tube solution. To check whether the filter bulbs
caught all the acid in the sample, wash and titrate the last bulb.
If the gas tested contained SO2, slowly boil the washings for 15 minutes
to remove any dissolved SO2.
Titrate the washings with standard NaOH (N/100 for dry air or gas, and
N/20 for exit gas) to a methyl red end point. Express the acidity as milli-
grams of H,SO4.
Calculate the volume of the gas sample as cubic feet at standard condi-
tions (0°C and 760 mm Hg).
Express the acid content of the gas as mg H2SO4 per cubic feet of dry
gas at standard conditions.
For interpretation and comparison of test results, it is essential to report
any pertinent operating data, including production rate and gas strength or
the air or gas volume, with the test results.
"Stick" Test for Determination of Sulfuric Acid Spray
To determine the quantity of mechanically entrained spray in the gas
stream leaving the drying or absorbing towers, insert a clean, smooth, soft
wood stick % inch wide by % inch thick into the duct across the full diameter.
The test period will vary from 1 to 5 minutes, depending on the quantity
of spray. Usually 1 minute of immersion is ample to indicate the presence of
any appreciable quantity of spray. This test is by visual observation only
and is only semi-quantitative.
A small amount of spray would consist of a few particles about the size
of a pin head. A medium amount of spray would be indicated by additional
spots and of about VB inch diameter. Heavy spray would be shown in the
droplets overlapped to present a wet surface with particle size approaching
JA-inch to %-inch diameter.
This test is for true spray only and will not show mist unless the stick
is immersed for several minutes; then mist will show up as an over-all
blackening.
The term "mist" is intended to denote the extremely finely divided
particles that escape from the mist precipitator or that enter an absorbing
tower. The term "spray" is intended to mean those much larger droplets
that may be mechanically entrained from drying or absorbing towers.
84 APPENDIX B
-------
SHELL DEVELOPMENT COMPANY METHOD FOR THE DETERMINA-
TION OF SULFUR DIOXIDE AND SULFUR TRIOXDDEU7)
Scope
This method describes a procedure for determining sulfur dioxide and
sulfur trioxide in stack gases.
Apparatus
Sampling Probe — Glass tubing (preferably borosilicate or quartz) of
suitable size with a ball joint at one end and a removable filter at the other
(a Vz-inch-OD, 6-foot-long tube has been used). It may be necessary to
support the glass probe in a stainless steel pipe; if the stack gas temperature
exceeds 500°C, a water-cooled jacket of metal may be required.
Filter — A filter is needed to remove particulate matter, which may con-
tain metal sulfates and cause interference during analysis. Borosilicate glass
wool, Kaolin wool, or silica wool are suitable filters for removing particulate
matter. (Ammonia or certain gaseous ammonia compounds have been re-
ported to cause interference with sulfur trioxide determination (21).)
Adapter — Six plug-type connecting tubes T 24/40, one with a 90° bend
and a socket joint.
Heating Tape — An insulated heating tape with a powerstat to prevent
condensation in exposed portion of probe and adapter. Alternative: glass wool
or other suitable insulators.
Dry Gas Meter — A 0.1-cubic-foot-per-revolution dry gas meter equipped
with a fitting for a thermometer and a manometer. Alternately, a calibrated
tank or a rotameter calibrated at the operating pressure may be used.
Vacuum pump.
Thermometers — One 10-50°C, ± 1°C; and one 0-300°C ± 5°C are suit-
able.
Manometer — A 36-inch-Hg manometer.
Absorbers — Two U-shaped ASTM D 1266 lamp sulfur absorbers with
coarse-sintered plates.
Filter Tube — One 40-mm-diameter Corning medium-sintered plate.
Scrubber for Purifying Air — An ASTM D 1266 lamp sulfur absorber
with coarse-sintered plate.
Teflon Tubing — Teflon tubing, V4 inch ID, for connecting absorbers.
Alternative: 8-mm pyrex tubing with butt-to-butt connections held together
with Tygon.
(An alternate absorption system that will operate with less pressure drop
has been used by a study group of the American Petroleum Institute (23).
The Absorption section consists of three absorbers and two spray traps as
described in Section A-22 and 23 of the "Methods of Test for Sulfur in
Petroleum Products and Liquified (LP) Gases (Lamp Method)," ASTM Des-
ignation D-1266-59T.)
Reagents
Water — Distilled water that has been deionized.
Isopropanol, Anhydrous.
APPENDIX B 85
-------
80 Percent Isopropyl Alcohol — Dilute isopropanol with water at a ratio
of 4 to 1.
30 Percent Hydrogen Peroxide — (reagent grade).
3 Percent Hydrogen Peroxide — Dilute 30 percent hydrogen peroxide
with water at a ratio of 10 to 1. Prepare fresh daily.
Barium Chloride — (Bad, • 2 H,O, reagent grade).
0.0100N Alcoholic Barium Chloride — Dissolve 1.2216 grams Bad, • 2 H2O
in 200 ml of water and dilute to 1 liter with isopropanol. Standardize this
solution with 0.01 N alcoholic sulfuric acid solution.
(As an alternate titrating solution to 0.01N alcoholic barium chloride,
the American Petroleum Institute Study Group uses 0.0 IN alcoholic barium
perchlorate because they believe that it gives a sharper end point during
titration.)
Thorin Indicator — l-(0-arsonophenylazo)-2 naphthol-3, 6-disulfonic
acid, disodium salt.
0.2 Percent Thorin Indicator — Dissolve 0.2 gram thorin indicator in
100 ml water. Store in polyethylene bottle.
Sampling Procedure
Set up the apparatus as shown in Figure B7. Place 30 ml of 80 percent
isopropyl alcohol in the first absorber and 10 ml in the filter tube. Then add
50 ml of 3 percent hydrogen peroxide to the second absorber. A light film of
silicone grease on the upper parts of the joints may be used to prevent leak-
age. Wind the heating tape in a uniform single layer around the exposed
portion of the probe and adapter and cover the heating tape with asbestos
tape wound in the opposite direction. Place a thermometer between the
heating tape and asbestos as near the adapter joint as possible. Connect the
heating tape to a powerstat, switch on the current, and maintain the probe
and adapter at a temperature at which no condensation will occur (about
250°C). Sample at 0.075 cubic foot per minute until 2 cubic feet or a suitable
volume of gas has been sampled. Record the meter readings, temperatures,
and pressures at 10-minute intervals. Note the barometric pressure. Do not
sample at a vacuum of more than 8 inches Hg.
FILTER TUBE
SAMPLE
PROBE
MANOMETER J DJYttS
SO SO.
ABSORBERS
Figure B7 — Sulfur dioxide - sulfur trioxide sampling train.
APPENDIX B
-------
Sample Preparation
Disconnect the asbestos tape, heating tape, probe, and adapter and
allow them to cool. Connect the scrubber for purifying air to the inlet of the
isopropyl alcohol absorber and add 50 ml of 3 percent hydrogen peroxide.
Replace the water in the ice bath with tap water. Draw air through the
system for 15 minutes to transfer residual sulfur dioxide to the hydrogen
peroxide absorber. Disconnect the purifying air scrubber. (Although the use
of air for removal of sulfur dioxide from isopropyl alcohol should not result
in oxidation of sulfur dioxide to sulfur trioxide, the American Petroleum
Institute Joint Study Group uses 99 percent nitrogen to preclude any possi-
bility of oxidation.) Remove the filter and wash the probe and adapter with
80 percent isopropyl alcohol. Place the washings in the isopropyl alcohol
absorber.
Disconnect the hydrogen peroxide absorber and transfer the contents and
the water washings to a 250-ml volumetric flask. Dilute with water to the
mark. Analyze for sulfur dioxide.
Stopper the isopropyl alcohol absorber and apply suction to the filter end.
Remove the suction line and allow the partial vacuum in the absorber to draw
the solution from the filter. Rinse the filter tube with 80 percent isopropyl
alcohol before the suction is lost. Transfer the contents of the isopropyl
alcohol absorber and its washings to a 250-ml volumetric flask and dilute to
the mark with 80 percent isopropyl alcohol. Analyze for sulfur trioxide.
Analytical Procedure
Sulfur Trioxide — Pipet a suitable aliquot to a flask and dilute to 100 ml
with 80 percent isopropyl alcohol. Add a few drops of thorin indicator
(enough to give a yellow color). Titrate with 0.01N Bad., to the pink end
point. Make a blank determination in parallel.
Sulfur Dioxide — Transfer a suitable aliquot to a flask and add 4 times
this volume of isopropyl alcohol. Dilute to 100 ml with 80 percent isopropyl
alcohol, add enough thorin indicator to give a yellow color, and titrate with
standard 0.01N BaCl2 to the pink end point. Run a blank determination in
parallel.
Calculations
o^ u i 24(A-B) (N) (F) (T)
ppm SO2 or SO:i by volume = (V ) (P)
where A = 0.01N BaCl2 used for titration of sample
B = ml 0.01N Bad., used for titration of blank
N = exact normality of Bad.,
F — dilution factor
T = average meter temperature, °R
V0 = observed volume of gas sample, cu ft
P = average absolute meter pressure, in. Hg
CHEMICAL CONSTRUCTION CORPORATION METHODS FOR
GAS ANALYSIS AT CONTACT SULFURIC ACID PLANTS
Reagents
Hydrogen peroxide solution, 0.2N — Dilute 20 ml of 30 percent hydrogen
peroxide to 2 liters with distilled water in a volumetric flask. Add 0.4 gram of
ascorbic acid (inhibitor) and store in a dark bottle. Standardize daily.
0.1W Potassium permanganate — Dissolve 6.6 grams of potassium per-
APPENDIX B 87
-------
manganate in about 2100 ml of distilled water in a large Erlenmeyer flask.
Boil gently for 20 to 30 minutes. Stopper and allow to stand for several days
in the dark.
Decant through an asbestos filter into a brown bottle. Do not wash the
undissolved residue.
0.05N — Sodium hydroxide solution
0.1N •— Sodium hydroxide solution
Phenolphthalein indicator
Methyl red indicator
Dilute sulfuric acid (1:1)
Sodium hydroxide solution, 25 percent
Apparatus
Train — for analyzing converter entrance gas (Figure B8)
Portable apparatus •— for analyzing stack gas (Figure B9)
Two 50-ml burettes.
Pipettes — 25 and 50 ml
Volumetric flasks — 250 and 500 ml
Gas scrubber — 250-ml volume
THERMOMETER
Figure B8 — Train for analysis of converter entrance gas.
Sampling probe. The diameter of the sampling tube is considered so that
the gas is sampled isokinetically.
V = fa
V = Volume flow rate of gas, cfm
f = Linear flow of gas stream, Ifm
a = Area of stack, ft2
88
APPENDIX B
-------
FLOWMETER\(
Figure B9 — Portable apparatus for determination of acid mist, SOs, and SO".
Standardization of Hydrogen Peroxide Solution
Transfer 25.0 ml of the hydrogen peroxide solution to a 600-ml beaker
containing about 250 ml of distilled water. (The same pipette is used for
the standardization and the analysis.)
Add 10 ml of dilute sulfuric acid (1-1).
Titrate with 0.1N KMnO4 until the pink color holds for 30 seconds after
the addition of one drop.
The volume of 0.1N KMnO4 required for 25.0 ml of hydrogen peroxide =
A. This volume is called the blank and is usually 40 to 50 ml. The hydrogen
peroxide solution is standardized daily. The addition of ascorbic .icid helps
to reduce decomposition of H,O2.
Analysis of Converter Entrance Gas
Gas sampling train (see Figure B8) consists of:
Kel-F tubing, V4-inch bore, used for all connections.
Two gas washing bottles, 250-ml, with extra-coarse fritted glass.
Calibrated gas measuring flask made from a 2-liter round bottom flask
and a 250-ml burette.
A 4-liter aspirator bottle containing about 3 liters of 10 percent sulfuric
acid with methyl red indicator.
Rubber stopper and thermometer.
Place 75.0 ml of the O.2N — hydrogen peroxide solution in the first gas
washing bottle and 50.0 ml in the second bottle.
Add 50 ml of distilled water to each bottle.
Fill measuring flask to mark with the 10 percent sulfuric acid using the
leveling bottle.
Before taking sample, purge line well.
APPENDIX B
89
-------
Hook up apparatus and sample slowly. Sampling 2500 ml of gas should
take about 15 minutes.
Measure volume of gas sample taken with the leveling bottle. Record
temperature.
Disconnect and transfer hydrogen peroxide solution to a 500-ml volu-
metric flask. Wash gas washing bottles well. Dilute to mark with distilled
water.
Fill a 250-ml volumetric flask by carefully pouring the solution in the
500-ml volumetric flask.
Wash the contents of each flask into two 600-ml beakers.
Add 10 ml of dilute sulfuric acid (1-1) to one beaker and titrate with
0.1N. KMnO4 until the pink color holds for 30 seconds after the addition of
one drop, ml of 0.1N KMnO4 = B.
Add a few drops of phenolphthalein indicator to the second beaker and
titrate with 0.5N NaOH. ml of 0.5 NaOH = C.
Calculations
V0 = measured volume of gas (ml), sulfur free at temperature T.
T = Temperature, °C.
P = Barometric pressure, in. Hg.
W — Vapor pressure of water at T, in. Hg.
V = Calculated volume of sulfur free gas at standard conditions
(760 mm Hg and 0°C.).
Normality KMnO4 x (5A — 2B) x 10.95 = Vol. of SO., (ml) at standard con-
ditions = R.
Normality NaOH x 2C x 10.95 = Vol. (ml) of SO., + SO, as SO, at standard
conditions = S.
v ? s x 100 = percent SO,
c
s x 100 = percent total as SO.,
1.25 (percent total as SO9 — percent SO.,) = percent SO.,
Determination of Sulfuric Acid Mist, Sulfur Dioxide, and Sulfur Trioxide
in Stack Gas
Gas sampling train (see Figure B9) is a portable apparatus and consists
of the following:
Glass sampling probe; sample is taken isokinetically.
Glass trap.
Sealing tube, 25 mm diameter with coarse-fritted disk for holding glass
filter paper.
Two 40-watt tungsten lamps for keeping temperature of the fritted-glass
tube above the dew point of water.
90 APPENDIX B
-------
Portable vacuum pump, made by the Jordan Pump Co., Atlanta Ga ,
Model No. NW-222.
Two gas washing bottles, 250-ml with extra-coarse-fritted glass.
Flow meter, Brooks, Mite, Brooks Rotameter Co., calibrated 0.45 to 4.5
1pm of air at STP.
Glass-fiber filter paper, 2.4-cm diameter, No. X-934-AH made by the
Hurlbut Paper Company.
Place two glass-fiber filter papers in the sealing tube against the fritted
disk so that the fit is good.
Place 25.0 ml of the 0.2N — hydrogen peroxide solution in each of the
two gas washing bottles; add about 100 ml of distilled water to each bottle.
Connect train and check flow-meter rate before connecting sampling tube
from stack. Gas rate should be 0.7 to 1.0 liters per minute. Tungsten lamps
should be burning.
Connect sampling tube and take a 10.0-minute sample. Disconnect sample
line and continue sucking air through train for 30 seconds. Shut off pump.
Volume of sample = X (liters at S.C.)
Replace the two gas washing bottles with a scrubber containing about
100 ml of 25 percent sodium hydroxide.
Continue taking the gas sample; increase the flow rate to 4 liters per
minute. Continue sampling for exactly 30 minutes.
Volume of gas sample at high flow rate = Y (liters at S.C.)
Total volume of gas sample for mist analysis = X + Y = Z.
While taking the sample for the mist analysis, transfer the hydrogen
peroxide solution in the gas washing bottles to a 500-ml volumetric flask.
Wash bottles well and dilute to mark with distilled water. Mix.
Fill a 250-ml volumetric flask by carefully pouring the solution from the
500-ml volumetric flask.
Wash the contents of each flask into two 600-ml beakers.
Add 10 ml of dilute sulfuric acid (1-1) to one beaker and titrate with
0.1N KMnO4 until the pink color holds for 30 seconds after the addition of
one drop.
ml of 0.1N KMnO4 — B.
Add a few drops of phenolphthalein indicator to the second beaker and
titrate with 0.1N NaOH.
ml of 0.1N NaOH = C.
After taking the additional 30-minute sample, disconnect sampling line
and continue to suck air through train for 30 seconds. Shut off pump.
Remove the fritted-glass sealing tube with the two glass-fiber filter
papers. Wash and filter the contents into a small suction flask. Titrate with
0.1N NaOH using phenolphthalein indicator.
ml of 0.1N NaOH = D.
APPENDIX B 91
-------
Calculations
Normality KMnO4 x (2A — 2B) x 10.95 = Vol. of SO2 (ml) at S.C. = R.
Normality NaOH x 2C x 10.95 = Vol. (ml) of SO2 + SO, as SO? at S.C.
= S.
R
X + S
• x 100 = percent SO,.
X + S
x 100 = percent total as SO?.
1.25 x (percent total as SO2 — percent SO2) = percent SO,.
Normality NaOH x D x 49 = M H SQ j t f _
0.03533 Z - 4
A = ml of 0.1N KMnO4 required for 25.0 ml of the hydrogen peroxide
solution.
NOTE: Normally the Reich Test is used for control analysis. The pre-
ceding analytical methods are more accurate and are particularly useful for
analyzing gases containing high concentrations of sulfur trioxide.
PHENOLDISULFONIC ACID METHOD FOR TOTAL NITROGEN OXIDES
Scope
When sulfur dioxide is present in the gas to be sampled and/or the con-
centration range of the oxides of nitrogen is 5 to several thousand ppm, this
method is used. Accuracy near the lower limit is questionable. This test is
unsuitable for atmospheric sampling.
PROBE
12 5
12 5
STAINLESS STEEL
PROBE
.— TO VACUUM
/ PUMP
r^<
GLASS ( j
CAPILLARY \ /
TUBE \^_^/
DETAIL A
Figure BIO — Apparatus for integrated grab samples.
Apparatus (Figure BIO)
Sampling Probe — Stainless steel (type 304 or 316) or glass tubing of
suitable size (V4-inch-OD, 6-foot-long stainless steel tubing has been used).
92
APPENDIX B
-------
Collection Flask — A 2-liter round-bottom flask with an outer 24/40
joint for integrated samples or a 250-ml MSA sampling tube for grab samples.
Orifice Assembly — The size of the glass capillary tubing depends on the
desired sampling period (flow rates of about 1 liter per minute have been
used).
Adapter with Stopcock — Adapter for connecting collection flask to sam-
pling T.
Three-way Stopcock.
Manometer — A 36-inch Hg manometer.
Spectrophotometer •— Beckman Model B.
Reagents
30 Percent Hydrogen Peroxide — (reagent grade).
3 Percent Hydrogen Peroxide — Dilute 30 percent H2O? with water at
1:1 ratio. Prepare fresh daily.
Concentrated Sulfuric Acid.
0.1N (approximate) Sulfuric Acid — Dilute 2.8 ml concentrated H2SO4
to 1 liter with water.
Absorbing Solution — Add 12 drops 3 percent H2O2 to each 100 ml 0.1N
H2SO4. Make enough for required number of tests.
In (approximate) Sodium Hydroxide — Dissolve 40 gm NaOH pellets in
water and dilute to 1 liter.
Concentrated Ammonium Hydroxide.
Fuming Sulfuric Acid — 15 to 18 percent weight free sulfuric anhydride
(oleum).
Phenol (reagent grade).
PhenoldisuZfonic Acid Solution — Dissolve 25 grams of pure white phenol
in 150 ml concentrated H2SO4 on a steam bath. Cool and add 75 ml fuming
sulfuric acid. Heat to 100°C for 2 hours. Store in a dark stoppered bottle.
This splution should be colorless if prepared with quality reagents.
Potassium Nitrate (reagent grade).
Standard Potassium Nitrate Solution — Solution A: Dissolve 0.5495 gram
KNO3 and dilute to 1 liter in a volumetric flask. Solution B: Dilute 100 ml
of Solution A to 1 liter. One ml of Solution A contains the equivalent of 0.250
mg NO2 and of Solution B, 0.0250 mg NO2.
Calibration
Calibration curves are made to cover different ranges of concentrations.
Using a microburette for the first two lower ranges and a 50-ml burette for
the next two higher ranges, transfer the following into separate 150-ml
beakers (or 200-ml casseroles).
1. 0 — 100 ppm: 0.0 (blank), 2.0, 4.0, 6.0, 8.0, 10.0, 12.0, 16.0, 20.0 ml
of KNO3 Solution B.
2. 50 — 500 ppm: 0.0 (blank), 1.0, 1.5, 2.0, 3.0, 4.0, 6.0, 8.0, 10.0 ml of
KNO3 Solution A.
APPENDIX B 93
-------
3. 500 — 1500 ppm: 0.0 (blank), 5.0, 10.0, 15.0, 20.0, 25.0, 30.0 ml of
KNO3 Solution A.
4. 1500 — 3000 ppm: 0.0 (blank), 15.0, 30.0, 35.0, 40.0, 45.0, 50.0, 55.0,
60.0 ml KNO3 Solution A.
Add 25.0 ml absorbing solution to each beaker. Follow as directed in the
Analytical Procedure section starting with the addition of IN NaOH.
After the yellow color has developed, make dilutions for the following
ranges as follows: 50 — 500 ppm (1:10), 500 — 1500 ppm (1:20) and 1500 —
3000 ppm (1:50). Read the absorbency of each solution at 420 iry.
Plot concentrations against absorbencies on rectangular graph paper. A
new calibration curve should be made with each new batch of phenoldisul-
fonic acid solution or every few weeks.
Sampling Procedure
Integrated Grab Sample — Add 25 ml freshly prepared absorbing solution
into the flask. Record the exact volume of absorbing solution used.
Set up the apparatus as shown in Figure BIO; attach the selected orifice.
Purge the probe and orifice assembly with the gas to be tested before sampling
begins by applying suction to it. Evacuate the system to the vapor pressure
of the solution; this pressure is reached when the solution begins to boil.
Record the pressure in the flask and the ambient temperature. Open the valve
to the sampling probe to collect the sample. Constant flow will be maintained
until the pressure reaches 0.53 of the atmospheric pressure. Stop before this
point is reached. During sampling, check the rate of fall of the mercury in
one leg of the manometer in case clogging, especially of the orifice, occurs.
At the end of the sampling period, record the pressure, temperature, and
barometric pressure.
An extended period of sampling can be obtained by following this pro-
cedure. Open the valve for only a few seconds at regular intervals. For
example: Open the valve for 10 seconds and close it for 50 seconds; repeat
every 60 seconds.
Grab Sample — Set up the apparatus as shown in Figure Bll for high
concentrations (200-300 ppm) or the apparatus as shown in Figure BIO for
low concentrations (0-200 ppm), but delete the orifice assembly. The same
procedure is followed as in the method for integrated samples except that the
valve is opened at the source for about 10 seconds and no orifice is used.
Sample Preparation
Integrated Grab or Grab Sample — Shake the flask for 15 minutes and
allow to stand overnight.
Analytical Procedure
Transfer the contents of the collection flask to a beaker. Wash the flask
three times with 15-ml portions of H2O and add the washings to the solution
in the beaker. For a blank add 25 ml absorbing solution and 45 ml H2O to
a beaker. Proceed as follows for the blank and samples.
Add IN NaOH to the beaker until the solution is just alkaline to litmus
paper. Evaporate the solution to dryness on a water bath and allow to cool.
Carefully add 2 ml phenoldisulfonic acid solution to the dried residue and
triturate thoroughly with a glass rod making sure that all the residue comes
94
APPENDIX B
-------
TO VACUUM
PUMP
7
250-ML FLASK
\
MERCURY MANOMETER
Figure Bl 1 — Apparatus for grab samples.
into contact with the solution. Add 1 ml H2O and 4 drops concentrated H2SO4.
Heat the solution on the water bath for 3 minutes with occasional stirring.
Allow the solution to cool and add 20 ml H2O, mix well by stirring, and
add 10 ml concentrated NH4OH, dropwise, with constant stirring. Transfer
the solution to 50-ml volumetric flask, washing the beaker three times with
4 to 5-ml portions of H2O. Dilute to mark with water and mix thoroughly.
Transfer a portion of the solution to a dry, clean centrifuge tube and centri-
fuge, or filter a portion of the solution.
Read the absorbency of each sample at 420 m^. If absorbency is higher
than 0.6, make a suitable dilution of the sample and the blank and read the
absorbency.
Calculations
PpmNO,= (5.24
(C)
A
Where C = concentration of NO2, mg (from calibration chart)
Vs = gas sample volume at 70°F and 29.92 inches Hg, ml.
SALTZMAN METHOD FOR NITROGEN DIOXIDE (20)
Scope
A convenient but less accurate field method for determining NO2 from
stack gases utilizes the Saltzman reagent and glass syringes. Interference
caused by air oxidation of NO to NO2 and by SO2 are minimized by expelling
the gas sample immediately after the absorbing period and by reading the
absorbence 15 minutes later.
Apparatus
Sampling Probe — Stainless steel (type 304 or 316) or glass tubing of
suitable size with two short taps close to one end and a filter at the other end.
Serum Cap — A self-sealing cap the size of the tap.
Thermometer.
APPENDIX B
95
-------
Collection Flask — A 50- or 100-ml glass syringe.
Gas Washing Bottle — A 500-ml Erlenmeyer flask.
Vacuum Pump.
Glass Wool.
Spectrophotometer — Beckman Model B.
Reagents
Glacial Acetic Acid.
Sulfanilic Acid.
N-(l-naphthyl)-ethylenediamine Dihydrochloride
Absorbing Solution — To 6 liters of water, add 1120 ml glacial acetic
acid, 40 grams sulfanilic acid, and 0.160 grams N-(l-naphthyl)-ethylenedia-
mine dihydrochloride. Dilute to 8 liters with water and store in a refrigerator;
45°F has proven adequate.
Sodium Nitrite (reagent grade).
Standard Sodium Nitrite Solution — Accurately weigh 2.03 grams NaNO0
and dissolve in water. Dilute to 1 liter. Just before the standardization pro-
cedure, prepare a dilute standard sodium nitrite solution by transferring
10 ml of this stock solution to a 1-liter volumetric flask and diluting to 1 liter.
One ml of this standard solution is equivalent to 10 ^1 of nitrogen dioxide at
25°C and 760 mm Hg.
Sodium Hydroxide.
IN (approximate) Sodium Hydroxide — Dissolve 40 grams NaOH and
dilute to 1 liter with H2O.
Calibration
Transfer 0.2, 0.4, 0.6, 0.8, 1.0 and 1.2 ml of the standard sodium nitrite
solution to six 25-ml volumetric flasks and fill the flask to the mark with the
freshly prepared dilute absorbing solution. Shake thoroughly and allow 15
minutes for color development. Read the absorbence at 550 m^ in a spectro-
photometer using the absorbing solution as the blank. The 1-ml standard is
equivalent to 0.4 ^1 nitrogen dioxide per ml of reagent. Plot concentrations
against absorbences on rectangular graph paper. Make a new calibration
curve for each new batch of absorbing solution.
Sampling Procedure
Set up the sampling train as shown in Figure B12. Place 200 ml IN NaOH
in the Erlenmeyer flask. Fill the syringe with a suitable volume of absorbing
solution and cap the syringe. For a 100-ml syringe, 40 to 50 ml absorbing
solution is adequate for a concentration range of 100-400 ppm.
Turn on the pump. After the probe is purged, uncap the syringe, insert
the needle through the serum cap, and draw a sample to the 100-ml mark.
Recap the syringe and shake vigorously for 1 minute. Expel the gas immedi-
ately thereafter. Record the temperature of the gas stream and the baro-
metric pressure.
If SO2 concentrations are 10 times greater than that of NO,, add 1 ml
acetone per 99 ml absorbing solution before its use.
96
APPENDIX B
-------
Analytical Procedure
After 15 minutes read the absorbence at 550
Calculations
ppm NO =
VrC (103)
Where Vr = volume reagent, ml
C = concentration of NO2, ^1/ml reagent
V, = volume of gas sample at 25°C and 760 mm Hg, ml
REDUCING UNION
DIAL THERMOMETER
GLASS WOOL
FILTER
GAS-WASHING
BOTTLE
100-ml GLASS
SYRINGE
Figure B12 — Nitrogen dioxide sampling train.
APPENDIX B
97
-------
APPENDIX C: METHODS OF DETERMINING CAUSES OF
VISIBLE PLUMES FROM STACKS OF CONTACT
SULFURIC ACID PLANTS
Many factors, independently or in combinations, affect the visibility of
stack emissions. Rarely will a single factor be the sole cause of visible plumes.
Although much effort has been expended to provide easy methods for deter-
mining specific causes, correlating cause and effect is still an art rather than
an exact procedure. The information assembled in this section is based on a
history of experience in the operation of sulfuric acid plants. It is provided
to aid operators in an orderly investigation to determine causes of stack-
visibility problems.
-------
All Types of Units, Including Equipment from Drying Tower to Exit Stack
CAUSE
Moisture in SO2 gas or air
Poor drying.
Moist air leakage.
Poor acid distribution. Dirty
distributor pan or tubes. Dis-
tribution points too far apart
or acid not equally distributed
in the area. Pan not level.
Insufficient acid circulating in
the towers.
Channelling due to dirty
tower.
Spray from drying tower
Splashing at weirs if the dis-
tributor is the weir type.
Splash from leaking distribu-
tor tubes or leakage in the
pans.
Splash from pans overflowing.
Leakage of internal acid pip-
ing.
METHOD OF DETERMINATION
Make moisture tests of air or gas leaving
the drying tower.
When the blower is located after the drying
tower, make moisture test on air or gas in
the blower discharge duct. (Atmospheric
moisture may be drawn in the suction duct
or connections of the blower.)
Inspect visually with and without acid cir-
culating. Distributing points not more than
18-inch centers, no more than 12 inches
from the inside of shell lining.
Measure acid level in pans with a rod. Make
sure pans are level. Check amperage of
pump motors. Compare temperature of gas
or air leaving the drying tower with temper-
ature of the acid entering the tower. They
should be approximately the same. Check
the increase in acid temperature across
tower.
Determine pressure drop through the tower,
both including and excluding the spray
catcher. Inspect visually for sulfate on the
top of tower packing. Wash tower if neces-
sary.
Make stick test at exit duct. Two sticks at
right angles to each other, and across the
duct diameter, are necessary at times if
flow pattern of gas including mist is dis-
torted.
Examine visually with and without acid
flowing. None of the weir streams should
have any free drop from the bottom of the
slots to the packing. Packing must come
up to the bottom of each slot and should
not splash at any weir.
Examine visually with acid circulation both
on and off. Look for wet tubes.
Measure each pan level with a rod. Instru-
ment readings may be in error. Pans may
not be level.
Examine visually for leaks in internal acid
pipe while acid is circulating at full normal
rate.
APPENDIX C
101
-------
CAUSE
Failure or plugging of en-
trainment separators.
Spray from top surface of acid
in distributor pan.
Flooding of packing in the
tower or flooding of packing
at the acid distributor due to
improper packing, high acid
or gas flow, or breakdown of
packing.
Mist formed in system between
converter outlet and absorbing
tower.
Cooling in SO3 cooler or econ-
omizer is too great, too fast,
or localized.
Duct cooling.
When large amounts of mois-
ture are in the SO3 gas leav-
ing the converter, as from
poor drying, entrained drying
acid, inadequate gas purifica-
tion, acidity or organic mat-
ter in the sulfur, etc., it is im-
possible to prevent acid mist
formation. Much of the mist
so formed cannot be re-
moved in the absorbing tower
and escapes as visible mist
from the exit stack.
Absorbing tower operating con-
ditions.
Temperature of acid in the
tower may be too high or too
low
METHOD OF DETERMINATION
Inspect. Measure pressure drop. Wash or
repack spray catcher if necessary.
Inspect visually. Spray from distributor
pan may result from improper entrance of
acid from delivery pipe to pan. Air tapped
in acid at pump may cause spray when re-
leased in the distributor pan.
Flooding evidenced by high pressure differ-
ential. Visual inspection of tower internals
will show uneven distribution of packing
or "washing" effect causing packing to
move and relocate in an uneven manner.
Appearance of drip acid in the economizer
or a larger-than-normal amount of drip
acid drained from the SO3 cooler shell.
This condition may be aggravated by an
abnormally high mist content in the SO3
gas.
Note whether the poor appearance of the
stack varies with atmospheric conditions.
If appearance is worse during rainstorms,
or during sudden changes in temperature
and wind velocity, top shielding from rain
or side shielding from wind may be re-
quired.
Can be detected quantitatively by mist tests
of the gas entering and leaving the absorb-
ing tower. Tyndall beam tests can be made
on the gas leaving the equipment being
tested. Sight glasses directly across the
diameter of the absorbing tower, above the
packing are helpful in determining whether
the escape of fumes from the absorbing
tower stack is due to unabsorbed SO3 or
sulfuric acid mist. The presence of mist in
the gas will cause a cloudy appearance in-
side the tower. If the gas is clear inside the
tower and the stack is fuming, the poor ap-
pearance of the stack is due to poor SO3
absorption and not to mist in the gas.
Low acid temperature has more effect on
stack than high temperature. Usually the
minimum is 50°C (122°F) and the maxi-
mum is 90°C (194°F) for acid entering.
102
APPENDIX C
-------
CAUSE
METHOD OF DETERMINATION
Acid strength too high or too
low.
Air leak at base of stack.
Temperature of gas entering
tower.
The optimum temperature must be found
by operating experience. Lower tempera-
tures are generally permitted with better
quality gas that contains less H2SO4 mist
or vapor. If stack appearance is poor due
to mist or moisture condition, it can usually
be improved by increasing the temperature
of the acid going to the tower to 90° to
110°C. This is done only as a temporary
measure to confirm that a mist or moisture
condition exists.
Determine optimum strength by actual op-
eration, adjusting slowly within the range
of 98.5 percent to 99.4 percent. Approxi-
mately 99.2 percent is good practice.
Visual inspection.
In plants that do not produce oleum, tem-
peratures of 150° to 160°C entering the
absorber are low enough. Temperatures
could be considerably higher with good
stack appearance, but with higher gas inlet
temperature the absorbing acid temperature
must be higher also and corrosion will be
greater.
Insufficient acid flow.
Poor acid distribution. Dirty
distributor pan. Distribution
points too far apart or the
acid not equally distributed in
the area.
Measure acid level in pans with a rod.
Make sure pans are level. Check amperage
of pump motors. Compare temperature of
gas or air leaving the drying tower with the
temperature of the acid entering the tower.
They should be approximately the same.
Check the increase in acid temperature
across tower.
Inspect visually with and without acid cir-
culating. Distributing points not more than
18-inch centers, nor more than 12 inches
from the inside of shell lining.
Channelling due to dirty
tower.
Tower packing settled or dis-
arranged.
Determine pressure drop through the tower,
both including and excluding the spray
catcher. Inspect visually for sulfate on the
top of tower packing. Wash tower if nec-
essary.
When all other points have been checked
and found satisfactory, this item might be
the cause. Packing under the distributor
tubes may have to be removed and re-
arranged.
APPENDIX C
103
-------
CAUSE
METHOD OF DETERMINATION
Oleum tower operating condi-
tions.
Leakage of damper in SO3
gas line bypassing the oleum
tower, allowing subsequent
mixture of hot and cooled gas
streams.
Whenever possible avoid using a bypass
line. When a bypass line cannot be avoided,
try blanking it off to determine whether it
affects the stack appearance. Damper
leakage may be detected by measuring skin
temperature of the bypass duct. If part of
gas must pass through the oleum tower and
part through the bypass, the temperature of
the mixture going to the absorber should be
above approximately 150° to 160°C; such a
temperature usually results in a better
stack.
Sulfur Burning: (Raw Gas) Units
Steam or water leaks.
Sulfur line to burner.
Leaks in the boiler, super-
heater, or economizer tube.
Oxides of nitrogen in gas.
Very high burner temperature
causes nitrogen to combine
with oxygen and form oxides
of nitrogen, which tend to
form sulfuric acid mist in the
equipment between the con-
verter and the absorbing
tower.
Disconnect line at burner with pump down
and steam on jacket. Blanking at pump
may be necessary. At times it may be
possible to cut steam off the steam jackets
— carefully; stack will clear rapidly if a
steam leak is the source of trouble. Do not
allow sulfur in line to freeze.
Symptoms are a considerable increase in
the condensed acid drip in SO3 cooler and
in the economizer or decrease in the amount
of water required for dilution. When boiler
leaks are suspected, shut down and exam-
ine by inspection for water dropping from
boilers into the compartments or ducts
under the boiler or economizer. If leaks
are very large, water will run out of drain
nozzles under the boiler or economizer
when blind flange is removed from the end
of the drains. Apply hydrostatic tests on
boiler system equipment when leaks are
suspected and cannot be detected. Com-
parative Tyndall beam tests can be made
on gas entering and leaving equipment sus-
pected of leaks.
Examine condensed drip in economizer or
SO3 cooler for niter. When drip is diluted
with water, brown fumes will be noted if
a considerable amount of niter is present.
Niter in the burner gas may be prevented
by reducing the burner temperature, low-
ering SO, gas strength, or lessening pre-
heating of the air. This condition may be
due to high localized temperatures that are
104
APPENDIX C
-------
CAUSE
METHOD OF DETERMINATION
not recorded or evident; it might be cor-
rected by improving the sulfur spray dis-
tribution and burning pattern.
Quality of the sulfur or raw
material.
Nitrogen compounds.
Hydrocarbon or organics in
sulfur.
Acidity in sulfur.
Laboratory analysis of the raw material is
required.
May occur in any of the raw materials, i.e.,
sulfur, H2S, or dilution acid (if unit uses
spent acid in the tower acid circulating
systems).
Good sulfur filtering sometimes helps by
partially reducing organics.
Neutralize acidity with lime, but only when
sulfur is subsequently filtered.
Metallurgical (Gas Purification) Units
Mist.
Inefficient mist precipitators
or coke filters.
Gas leaving the electrostatic precipitators
(or leaving the coke filters) should be op-
tically clear. Examine by Tyndall beam in
gas duct leaving the precipitator or the
coke box, or examine through sight glasses
across the drying tower above the packing.
Gas should be clear, not cloudy.
Niter in the gas.
Arcing in the electrostatic
precipitators forms ozone and
oxides of nitrogen.
Niter from raw material, HCN
in H2S gas, cyanide in the
roasted ore, niter in SO2 gas
scrubbing or drying acids il
partly mixed with chamber
acid.
Arcing is visible through sight glasses in
the precipitator, or audible from the crack-
ling sparking, or will be noted from fluctu-
ating volt meters. Sparking may be caused
by broken wires, dirty wires, or swaying
wires. Dirty wires usually are cleaned by
washing, and then kept clean by flushing
at timed intervals.
Laboratory analyses required.
B
C
H
P
R
S
Sc
Z
Byproduct SO2 gas from various sources
Copper converter gas
H2S
Pyrites or pyrrhotite
Spent or sludge acid
Frasch-process or recovered elemental sulfur, solid or liquid
Crude sulfur containing 15-25 percent S
Zinc sulfide concentrates
APPENDIX C
105
-------
APPENDIX D: SULFURIC ACID ESTABLISHMENTS
IN THE UNITED STATES
The main purpose of this tabulation of sulfuric acid manufacturing
establishments (Table Dl) is to indicate the wide distribution and the prin-
cipal areas of concentration of this industry throughout the country.
Information was drawn from various sources and is believed to represent
the operable installations existing as of November 1, 1963, but not necessarily
operating at that time. Listings are without regard to the number of produc-
ing units at a given location; the total number of units far exceeds the
number of establishments. As a result of sale, merger, or lease, company
identifications may in some cases differ from those presently in use, but
should serve the intended purpose of general identification.
The contact process is shown at 163 establishments and the chamber
process at 60 establishments, a total of 223 appearing in the list. Variance of
these numbers from data given elsewhere in this report is not due to oversight
or error, but to the use of a different basis of reporting.
Sources of sulfur dioxide in the raw materials column of Table Dl are
keyed to the following abbreviations:
B Byproduct SO2 from various sources.
C Copper converter gas.
H H2S.
P Pyrites or pyrrhotite.
R Spent or sludge acid.
S Frasch-process or recovered elemental sulfur, solid or liquid.
Sc Crude sulfur containing 15 to 25 percent S.
Z Zinc sulfide concentrates.
-------
TABLE Dl. SULFURIC ACID ESTABLISHMENTS IN THE
UNITED STATES (As of November 1, 1963)
Company Location
ALABAMA
The American Agricultural Chemical Co.
American Cyanamid Company
E. I. du Pont de Nemours && Co.
Home Guano Company
Reichhold Chemicals, Incorporated
StaufEer Chemical Company
Tennessee Corporation, Lessee of
Alabama Ordnance Works
V-C Chemical Co. — Division of
Socony Mobil Oil Company
V-C Chemical Co. — Division of
Socony Mobil Oil Company
ARIZONA
Apache Powder Company
Bagdad Copper Company
Inspiration Consolidated Copper Co.
Kennecott Copper Corporation
Southwest Agrochemical Corporation
ARKANSAS
Monsanto Company
Olin Mathieson Chemical Corporation
CALIFORNIA
Allied Chemical Corporation,
General Chemical Division
Allied Chemical Corporation,
General Chemical Division
Allied Chemical Corporation,
General Chemical Division
American Smelting & Refining Co.
Collier Carbon and Chemical Corp.
Monsanto Company
Occidental Petroleum Corporation,
Best Fertilizer Co. Division
Stauffer Chemical Company
Stauffer Chemical Company
StaufEer Chemical Company
Valley Nitrogen Producers, Inc.
COLORADO
Allied Chemical Corporation,
General Chemical Division
Rico Argentine Mining Co.
Union Carbide Corporation, Nuclear Div.
DELAWARE
Allied Chemical Corporation,
General Chemical Division Claymont
Raw
materials Process
Montgomery
Mobile
Mineral Springs
Dothan
Tuscaloosa
Le Moyne
Childersburg
Dothan
S Chamber
S Contact
S Contact
S Chamber
S Contact
S Contact
S Contact
S Chamber
Birmingh'm(Wylam) S Contact
Benson
Bagdad
Inspiration
Hayden
Chandler
El Dorado
N. Little Rock
El Segundo
Bay Point
Richmond
Selby
Wilmington
Avon
Lathrop
Dominguez
Vernon
Stege
Fresno
Denver
Rico
Uravan
S Contact
S Contact
S Contact
P Contact
S Contact
S Contact
S Contact
HRS Contact
RS Contact
HRS Contact
B Contact
HRS Contact
HRS Contact
S Contact
HRS Contact
S Contact
S Contact
S Contact
PR Contact
P Contact
S Contact
PR
Contact
APPENDIX D
109
-------
Company Location
FLORIDA
Acid Inc.
The American Agricultural Chemical Co.
The American Agricultural Chemical Co.
American Cyanamid Company
Armour and Company
Armour and Company
Armour and Company
W. R. Grace & Co.,
Davison Chemical Division
International Minerals & Chemical Corp.
F. S. Royster Guano Company
Swift & Company
U. S. Phosphoric Products Division,
Tennessee Corporation
V-C Chemical Co. — Division of
Socony Mobil Oil Company
Wilson & Toomer Fertilizer Co.
Wilson & Toomer Fertilizer Co.
GEORGIA
The American Agricultural Chemical Co.
American Cyanamid Company
Armour and Company
Armour and Company
Cotton States Fertilizer Co.
Georgia Fertilizer Co.
Minerals & Chemicals Phillip Corp.
(Attapulgus Clay Products)
Pelham Phosphate Co.
F. S. Royster Guano Company
C. O. Smith Guano Co.
Southern Fertilizers & Chemical Co.
Southern States Phosphate & Fertilizer
Company
V-C Chemical Co. — Division of
Socony Mobil Oil Company
V-C Chemical Co. — Division of
Socony Mobil Oil Company
HAWAII
Pacific Chemical & Fertilizer Co.
(Pacific Guano Co.)
Standard Oil Co. of California,
Western Operations, Inc.
IDAHO
The Bunker Hill Company
(Sullivan Mining Company) Kellogg
J. R. Simplot Company,
Minerals & Chemical Division Pocatello
Raw
materials Process
Mulberry
Pensacola
Pierce
Brewster
Jacksonville
Bartow
Fort Meade
Ridgewood (Bartow)
Mulberry (Bonnie)
Pierce
Agricola
E. Tampa
Nichols
Jacksonville
Cottondale
Savannah
Savannah
Albany
Columbus
Macon
Valdosta
Attapulgus
Pelham
Athens
Moultrie
Savannah
Savannah
Savannah
Rome
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
&
S
S
S
S
S
S
S
Contact
Chamber
Chamber
Contact
Chamber
Contact
Contact
Contact
Contact
Contact
Contact
Contact
Contact
Chamber
Chamber
Chamber
Contact
Chamber
Chamber
Chamber
Chamber
Contact
Chamber
Chamber
Chamber
Contact
Chamber
Chamber
Chamber
Honolulu S Contact
Barbers Pt., Oahu HRS Contact
SZ
S
Contact
Contact
110
APPENDIX D
-------
Company Location
ILLINOIS
Allied Chemical Corporation,
General Chemical Division Hegewisch
Allied Chemical Corporation,
General Chemical Division
The American Agricultural Chemical Co.
American Cyanamid Company
American Zinc Co. of Illinois
American Zinc Co. of Illinois
Armour and Company
Hooker Chemical Corporation
(National Phosphate Corporation)
Kankakee Ordnance Works
Matthiessen & Hegeler Zinc Co.
Monsanto Company
National Distillers and Chemical Corp.,
U. S. Industrials Chemicals Co. Div.
Olin Mathieson Chemical Corporation,
Blockson Chemical Division
Chas. Pfizer & Co., Inc.,
C. K. Williams & Co. Division
Smith Douglass Co., Inc.
Swift & Company
INDIANA
E. I. du Pont de Nemours & Co.
Marion Mfg. Co.
Stauffer Chemical Company
IOWA
The American Agricultural Chemical Co.
International Minerals & Chemical Corp.
National Distillers and Chemical Corp.,
U. S. Industrial Chemicals Co., Div.
KANSAS
The Eagle-Picher Company
National Distillers and Chemical Corp.,
U. S. Industrial Chemicals Co., Div.
KENTUCKY
E. I. du Pont de Nemours & Co.
Pennsalt Chemicals Corporation
LOUISIANA
Allied Chemical Corporation,
General Chemical Division
American Cyanamid Company
Armour and Company
Cities Service Company
Olin Mathieson Chemical Corporation
Stauffer Chemical Company
MAINE
Northern Chemical Industries Searsport
Raw
materials Process
RS
Contact
E. St. Louis
E. Clinton
Joliet
Fairmount City
Fairmount City
Chicago Heights
Marseilles
Joliet
La Salle
Monsanto
Tuscola
Joliet
E. St. Louis
Streator
Calumet City
E. Chicago
Indianapolis
Hammond
Humboldt
Mason City
Dubuque
Galena
RS Contact
S Chamber
S Contact
SZ Contact
Z Chamber
S Chamber
S Contact
S Contact
SZ Chamber
S Contact
S Contact
S Contact
B Contact
S Contact
S Contact
RSZ Contact
S Contact
RS Contact
S Chamber
S Contact
S Contact
SZ Contact
Sunflower (DeSoto) RS Contact
Wurtland
Calvert City
Baton Rouge
Avondale
New Orleans
Lake Charles
Bossier City
Baton Rouge
RS Contact
S Contact
RS Contact
S Contact
S Chamber
HRS Contact
S Contact
RS Contact
Contact
APPENDIX D
111
-------
North Weymouth
Everett
S
S
River Rouge
Detroit
Bay City
Kalamazoo
Detroit
Ecorse
RS
S
S
S
S
RS
Contact
Chamber
Contact
Contact
Contact
Contact
Company Location
MARYLAND
The American Agricultural Chemical Co. Baltimore
Baugh Chemical Co. Baltimore
Bethlehem Steel Corporation Sparrows Pt.
W. R. Grace & Co.,
Davison Chemical Division Baltimore
Olin Mathieson Chemical Corporation Baltimore
F. S. Royster Guano Company Baltimore
U. S. Naval Powder Factory Indian Head
MASSACHUSETTS
The American Agricultural Chemical Co.
Monsanto Company
MICHIGAN
Allied Chemical Corporation,
General Chemical Division
The American Agricultural Chemical Co.
The American Agricultural Chemical Co.
American Cyanamid Company
W. R. Grace & Co.
E. I. du Pont de Nemours & Co.
MINNESOTA
North Star Chemical Company Pine Bend S
MISSISSIPPI
Coastal Chemical Co., Inc. Pascagoula S
International Minerals & Chemical Corp. Tupelo S
MISSOURI
W. R. Grace & Co.,
Davison Chemical Division
National Lead Company
MCWTAWA
The Anaconda Company
JVEVADA
The Anaconda Company Yerington Sc
JVEW JERSEY
Allied Chemical Corporation,
General Chemical Division Elizabeth RS
The American Agricultural Chemical Co. Carteret S
American Cyanamid Company Bound Brook S
American Cyanamid Company Warners S
Armour and Company Carteret S
Essex Chemical Corporation Newark S
Essex Chemical Corporation Paulsboro RS
E. I. du Pont de Nemours & Co. Deepwater S
E. I. du Pont de Nemours & Co. Grasselli S
E. I. du Pont de Nemours & Co. Gibbstown S
Koppers Company, Inc. Kearney HS
National Lead Company Sayreville S
Raw
materials Process
S Chamber
S Chamber
HP Contact
S Contact
S Contact
S Chamber
S Contact
Joplin S
St. Louis (Carondelet) S
Anaconda
Chamber
Contact
Contact
Contact
Chamber
Contact
Contact
Contact
Contact
Contact
Chamber
Contact
Contact
Chamber
Contact
Contact
Contact
Contact
Contact
Contact
Contact
112
APPENDIX D
-------
Company
NEW MEXICO
The Anaconda Company
Climax Chemical Company
Kermac Nuclear Fuels Corporation
NEW YORK
Allied Chemical Corporation,
General Chemical Division
The American Agricultural Chemical Co.
Eastman Kodak Company
NORTH CAROLINA
Acme Chemical Industries
Acme Fertilizer Company
The American Agricultural Chemical Co.
Armour and Company
Armour and Company
Swift & Company
V-C Chemical Co. — Division of
Socony Mobil Oil Company
V-C Chemical Co. — Division of
Socony Mobil Oil Company
OHIO
Allied Chemical Corporation,
General Chemical Division
Allied Chemical Corporation,
General Chemical Division
American Cyanamid Company
The American Agricultural Chemical Co.
The American Agricultural Chemical Co.
The American Agricultural Chemical Co.
American Zinc Oxide Company
(Farmer's Fertilizer Company)
Armour and Company
E. I. du Pont de Nemours & Co.
E. I. du Pont de Nemours & Co.
International Minerals & Chemical Corp.
Marion Plant Life Fertilizer Co.
Minnesota Mining and Manufacturing Co.
F. S. Royster Guano Company
Smith Douglass Co., Inc.
V-C Chemical Co. — Division of
Socony Mobil Oil Company
OKLAHOMA
National Zinc Co.
Ozark Mahoning Co.
PENNSYLVANIA
Allied Chemical Corporation,
General Chemical Division
The Atlantic Refining Company
Location
Raw
materials Process
Grants S Contact
Hobbs(Monument) HS Contact
Grants S Contact
Buffalo
Buffalo
Rochester
Acme
Acme
Greensboro
Greensboro
Navassa
Wilmington
Navassa
Selma
Painesville
HRS Contact
S Chamber
S Contact
S
S
S
S
S
S
Contact
Chamber
Chamber
Chamber
Chamber
Contact
S Contact
S Chamber
S Contact
Cleveland
Hamilton
Cleveland
S
S
S
Cincinnati (St.Bern'd) S
Cairo
Columbus
Sandusky
Cleveland
Fort Hill
Lockland
Sandusky
Copley
Toledo
Columbus
Cincinnati (St,
Bartlesville
Tulsa
Newell
Philadelphia
S
S
S
S
S
S
S
BS
S
S
.Bern'd) S
Z
S
PRS
HRS
Contact
Contact
Chamber
Chamber
Contact
Chamber
Chamber
Contact
Contact
Contact
Contact
Contact
Contact
Chamber
Contact
Contact
Contact
Contact
Contact
APPENDIX D
113
-------
Company
E. I. du Pont de Nemours & Co.
The New Jersey Zinc Company
Chas. Pfizer & Co.,
C. K. Williams & Co. Division
Pittsburgh Coke & Chemical Company
Rohm & Haas Company
St. Joseph Lead Company
United States Steel Corporation,
American Steel and Wire Division
Witco Chemical Company, Inc.
(Conneborn Chem. & Refining Corp.)
RHODE ISLAND
Heyden Newport Chemical Corporation
(Rumford Chemical Works)
SOUTH CAROLINA
The American Agricultural Chemical Co.
Anderson Fertilizer Co., Inc.
W. R. Grace & Co.,
Davison Chemical Division
International Minerals and Chemical
Corporation
Planters Fertilizer & Phosphate Co.
F. S. Royster Guano Company
V-C Chemical Co. — Division of
Socony Mobil Oil Company
V-C Chemical Co. — Division of
Socony Mobil Oil Company
TENNESSEE
Armour and Company
Tennessee Corporation
Tennessee Corporation
V-C Chemical Co. — Division of
Socony Mobil Oil Company
Volunteer Ordnance Works
TEXAS
American Smelting & Refining Company
Armour and Company
E. I. du Pont de Nemours & Co.
Gulf Oil Corporation
Olin Mathieson Chemical Corporation
Olin Mathieson Chemical Corporation
Olin Mathieson Chemical Corporation
Shamrock Oil & Gas Corporation
Smith Douglass Co., Inc.
Stauffer Chemical Company
Stauffer Chemical Company
Stauffer Chemical Company
Location
Cornwell Hts.
Palmerton
Raw
materials Process
S
Z
Donora
Petrolia
Rumford
S
RS
Contact
Contact
Easton B Contact
Neville Island HS Contact
Bridesburgh
(Philadelphia) S Contact
Josephtown Z Contact
Chamber
Contact
Contact
Charleston
Anderson
Charleston
Spartanburg
Charleston
Charleston
Charleston
Greenville
Nashville
Copperhill
Copperhill
Memphis
Tyner
Corpus Christi
Houston
La Porte
Port Arthur
Beaumont
Port Arthur
Pasadena
Sunray
Texas City
Fort Worth
Houston
Baytown
S
S
S
S
PS
S
S
S
S
p
p
S
S
Z
S
RS
HRS
HRS
S
S
RS
RS
S
RS
HRS
Chamber
Chamber
Contact
Chamber
Chamber
Chamber
Chamber
Chamber
Chamber
Contact
Chamber
Chamber
Contact
Contact
Chamber
Contact
Contact
Contact
Contact
Contact
Contact
Contact
Contact
Contact
Contact
114
APPENDIX D
-------
Company Location
UTAH
Garfleld Chemical & Mfg. Corp.
(Kennecott Copper Corp.) Garfleld
Texas Zinc Minerals Corporation Mexican Hat
United States Steel Corporation Provo (Geneva)
VIRGINIA
Allied Chemical Corporation,
General Chemical Division Pulaski
Allied Chemical Corporation,
General Chemical Division Front Royal
American Cyanamid Company Piney River
E. I. du Pont de Nemours & Co. James River
Hercules Powder Company, Inc.
(Radford Ordnance Works) Radford
W. R. Grace & Co.,
Davison Chemical Division
F. S. Royster Guano Company
Smith Douglass Co., Inc.
Swift & Company
V-C Chemical Co. — Division of
Socony Mobil Oil Company Lynchburg
V-C Chemical Co. — Division of
Socony Mobil Oil Co. Richmond
Weaver Fertilizer Company Norfolk
WASHINGTON
Allied Chemical Corporation,
General Chemical Division Anacortes
American Smelting & Refining Company Tacoma
WEST VIRGINIA
Allied Chemical Corporation,
General Chemical Division Nitro
Union Carbide Corporation S. Charleston
Raw
materials Process
C Contact
S Contact
H Contact
S
S
S
Norfolk (Money Pt.) S
Norfolk S
Norfolk S
Norfolk S
S
S
HRS
C
S
S
Contact
Contact
Contact
Contact
Contact
Chamber
Chamber
Contact
Contact
Chamber
Chamber
Contact
Contact
Contact
Contact
Contact
WISCONSIN
Badger Ordnance Works
E. I. du Pont de Nemours & Co.
F. S. Royster Guano Company
WYOMING
Susquehanna-Western, Inc.
Western Nuclear Co., Inc.
Baraboo
Barksdale
Madison
Riverton
Jeffrey City
S
S
S
S
S
Contact
Contact
Contact
Contact
Contact
APPENDIX D
115
-------
APPENDIX E: PHYSICAL DATA
-------
TABLE El. PHYSICAL DATA FOR SULFURIC ACID, 0-93% (23)
Be°
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
Sp. gr.
1.0000
1.0069
1.0140
1.0211
1.0284
1.0357
1.0432
1.0507
1.0584
1.0662
1.0741
1.0821
1.0902
1.0985
1.1069
1.1154
1.1240
1.1328
1.1417
1.1508
1.1600
1.1694
1.1789
1.1885
1.1983
1.2083
1.2185
1.2288
1.2393
1.2500
1.2609
1.2719
1.2832
1.2946
1.3063
1.3182
1.3303
1.3426
1.3551
1.3679
1.3810
1.3942
1.4078
1.4216
1.4356
1.4500
1.4646
1.4796
1.4948
1.5104
1.5263
Tw.°
0.0
1.4
2.8
4.2
5.7
7.1
8.6
10.1
11.7
13.2
14.8
16.4
18.0
19.7
21.4
23.1
24.8
26.6
28.3
30.2
32.0
33.9
35.8
37.7
39.7
41.7
43.7
45.8
47.9
50.0
52.2
54.4
56.6
58.9
61.3
63.6
66.1
68.5
71.0
73.6
76.2
78.8
81.6
84.3
87.1
90.0
92.9
95.9
99.0
102.1
105.3
Percent
H2S04
0.00
1.02
2.08
3.13
4.21
5.28
6.37
7.45
8.55
9.66
10.77
11.89
13.01
14.13
15.25
16.38
17.53
18.71
19.89
21.07
22.25
23.43
24.61
25.81
27.03
28.28
29.53
30.79
32.05
33.33
34.63
35.93
37.26
38.58
39.92
41.27
42.63
43.99
45.35
46.72
48.10
49.47
50.87
52.26
53.66
55.07
56.48
57.90
59.32
60.75
62.18
Weight of
1 cu ft,
Ib avdp
62.37
62.80
63.24
63.69
64.14
64.60
65.06
65.53
66.01
66.50
66.99
67.49
68.00
68.51
69.04
69.57
70.10
70.65
71.21
71.78
72.35
72.94
73.53
74.13
74.74
75.36
76.00
76.64
77.30
77.96
78.64
79.33
80.03
80.74
81.47
82.22
82.97
83.74
84.52
85.32
86.13
86.96
87.80
88.67
89.54
90.44
91.35
92.28
93.23
94.20
95.20
Percent
O. V.
0.00
1.09
2.23
3.36
4.52
5.67
6.84
7.99
9.17
10.37
11.56
12.76
13.96
15.16
16.36
17.58
18.81
20.08
21.34
22.61
23.87
25.14
26.41
27.69
29.00
30.34
31.69
33.04
34.39
35.76
37.16
38.55
39.98
41.40
42.83
44.28
45.74
47.20
48.66
50.13
51.61
53.08
54.58
56.07
57.58
59.09
60.60
62.13
63.65
65.18
66.72
Pounds
O.V. in
1 cuft
0.00
.68
1.41
2.14
2.90
3.66
4.45
5.24
6.06
6.89
7.74
8.61
9.49
10.39
11.30
12.23
13.19
14.18
15.20
16.23
17.27
1834
19.42
20.53
21.68
22.87
24.08
25.32
26.58
27.88
29.22
30.58
32.00
33.42
34.90
36.41
37.95
39.53
41.13
42.77
44.45
46.16
47.92
49.72
51.56
53.44
55.36
57.33
59.34
61.40
63.52
Freezing
(Melting)
Point, °F
32.0
31.2
30.5
29.8
28.9
28.1
27.2
26.3
25.1
24.0
22.8
21.5
20.0
18.3
16.6
14.7
12.6
10.2
7.7
4.8
+ 1.6
— 1.8
— 6.0
—11
—16
—23
—30
—39
—49
—61
—74
—82
—96
—97
—91
—81
—70
—60
—53
—47
—41
—35
—31
—27
—23
—20
—14
—15
—18
—22
—27
APPENDIX E
119
-------
TABLE El (Continued)
Be°
51
52
53
54
55
56
57
58
59
60
61
62
63
64
641/4
64V2
64%
65
65 V4
651/2
65%
66
Sp. gr.
1.5426
1.5591
1.5761
1.5934
1.6111
1.6292
1.6477
1.6667
1.6860
1.7059
1.7262
1.7470
1.7683
1.7901
1.7957
1.8012
1.8068
1.8125
1.8182
1.8239
1.8297
1.8354
Tw.°
108.5
111.8
115.2
118.7
122.2
125.8
129.5
133.3
137.2
141.2
145.2
149.4
153.7
158.0
159.1
160.2
161.4
162.5
163.6
164.8
165.9
167.1
Percent
H,SO4
63.66
65.13
66.63
68.13
69.65
71.17
72.75
74.36
75.99
77.67
79.43
81.30
83.34
85.66
86.33
87.04
87.81
88.65
89.55
90.60
91.80
93.19
Weight of
1 cu ft, ^nt
Ib avdp ' '
96.21
97.24
98.30
99.38
100.48
101.61
102.77
103.95
105.16
106.40
107.66
108.96
110.29
111.65
112.00
112.34
112.69
113.05
113.40
113.76
114.12
114.47
68.31
69.89
71.50
73.11
74.74
76.37
78.07
79.79
81.54
83.35
85.23
87.24
89.43
91.92
92.64
93.40
94.23
95.13
96.10
97.22
98.51
100.00
Pounds Freezing
O. V. in (Melting)
1 cu ft Point, °F
65.72
67.96
70.28
72.66
75.10
77.60
80.23
82.95
85.75
88.68
91.76
95.06
98.63
102.63
103.75
104.93
106.19
107.54
108.97
110.60
112.42
114.47
—33
—39
—49
—59
.... \
.... { Below
.... ( —40
.... j
. — 7
+ 12.6
27.3
39.1
46.1
46.4
43.6
41.1
37.9
33.1
24.6
13.4
— 1
—29
Specific gravity determinations were made at 60° F, compared with water
at 60" F.
From the specific gravities, the corresponding degrees Baume were cal-
culated by the following formula:
145
Baume = 145 —
sp. gr.
Baume hydrometers for use with this table must be graduated by the
above formula, which should always be printed on the scale.
66° Baume = sp. gr. 1.8354
1 cu ft water at 60° F weighs 62.37 Ib avoirdupois
H2SO4 = 100 percent
O. V.
60°
50°
H0SO4
93.19
77.67
62.18
O. V.
100.00
83.35
66.72
60°
119.98
100.00
80.06
Percentage compositions of acids stronger than 66° Be should be deter-
mined by chemical analysis.
120
APPENDIX E
-------
TABLE El (Continued)
APPROXIMATE BOILING POINTS
50° Be, 295°F
60°
61°
62°
63°
64°
65°
66°
386
400
415
432
451
485
538
FIXED POINTS
_ Percent
SP'gr- H2S04
1.0000
1.0048
1.0347
1.0649
1.0992
1.1353
1.1736
1.2105
1.2513
1.2951
1.3441
1.3947
1.4307
1.4667
1.4822
.00
.71
5.14
9.48
14.22
19.04
23.94
28.55
33.49
38.64
44.15
49.52
53.17
56.68
58.14
ALLOWANCE FOR
At Be
10°
20°
30°
40°
50°
60°
63°
66°
Be, or
0.029°
0.036°
0.035°
0.031°
0.028°
0.026°
0.026°
0.0235°
Sp. gr.
1.5281
1.5440
1.5748
1.6272
1.6679
1.7044
1.7258
1.7472
1.7700
1.7959
1.8117
1.8194
1.8275
1.8354
Percent
H2S04
62.34
63.79
66.51
71.00
74.46
77.54
79.40
81.32
83.47
86.36
88.53
89.75
91.32
93.19
TEMPERATURE
sp. gr.
0.00023
0.00034
0.00039
0.00041
0.00045
0.00053
0.00057
0.00054
= 1°F.
— 1°
= 1°
= 1°
= 1°
= 1°
===I 1°
— 1°
Percent
60°
61.93
63.69
65.50
67.28
69.09
70.90
72.72
74.55
76.37
78.22
80.06
81.96
83.86
85.79
87.72
89.67
91.63
93.67
95.74
97.84
100.00
102.27
104.67
107.30
110.29
111.15
112.06
113.05
114.14
115.30
116.65
118.19
119.98
Pounds
60° in
1 cuft
53.34
55.39
57.50
59.66
61.86
64.12
66.43
68.79
71.20
73.68
76.21
78.85
81.54
84.33
87.17
90.10
93.11
96.26
99.52
102.89
106.40
110.10
114.05
118.34
123.14
124.49
125.89
127.40
129.03
130.75
132.70
134.88
137.34
Percent
50°
77.36
79.56
81.81
84.05
86.30
88.56
90.83
93.12
95.40
97.70
100.00
102.38
104.74
107.15
109.57
112.01
114.46
117.00
119.59
122.21
124.91
127.74
130.75
134.03
137.76
138.84
139.98
141.22
142.57
144.02
145.71
147.63
149.87
Pounds
50° in
1 cuft
66.63
69.19
71.83
74.53
77.27
80.10
82.98
85.93
88.94
92.03
95.20
98.50
101.85
105.33
108.89
112.55
116.30
120.24
124.31
128.52
132.91
137.52
142.47
147.82
153.81
155.50
157.25
159.14
161.17
163.32
165.76
168.48
171.56
APPENDIX E
121
-------
TABLE E2. PHYSICAL DATA FOR SULFURIC ACID, 94-100% (24)
Percent
H2SO4
94.0
95.0
96.0
97.0
97.5
98.0
99.0
100.0
Wt. of 1 _ .
Sp.gr. cuft, P^n1
Ib avdp w- v'
1.8381
1.8407
1.8427
1.8437
1.8439
1.8437
1.8424
1.8391
114.64 100.87
114.80 101.94
114.93 103.01
114.99 104.09
115.00 104.63
114.99 105.16
114.91 106.23
114.70 107.31
Pounds
t O. V.
in 1 -
cu ft
115.64
117.03
118.39
119.69
120.32
120.92
122.07
123.08
Freezing
Point
"F
—28.1
—11.7
+ 5.7
17.1
23.2
28.6
39.9
50.6
°C
—33.4
—24.3
—14.6
— 8.3
— 4.9
— 1.9
+ 4.4
10.35
Percent
60°
121.02
122.31
123.60
124.89
125.53
126.17
126.46
128.75
Pounds
60°
in 1
cu ft
138.74
140.41
142.05
143.61
144.34
145.08
145.32
147.68
Percent
50°
151.17
152.78
154.39
156.00
156.81
157.61
159.22
160.82
Pounds
50°
inl
cu ft
173.30
175.39
177.44
179.38
180.31
181.24
182.96
184.46
Percent
S03
76.73
77.55
78.37
79.18
79.59
80.00
80.82
81.63
Pounds
S03
inl
cu ft
87.97
89.03
90.07
91.05
91.53
91.99
92.87
93.63
ALLOWANCE FOR TEMPERATURE
At 94% 0.00054 sp.gr. = 1°F
96% 0.00053 sp.gr. = 1°
97.5% 0.00052 sp.gr. = 1°,
100% 0.00052 sp.gr. = 1°:
0.00097 sp. gr. = 1°C
0.00095 sp. gr. = 1°
0.00094 sp. gr. = 1°
0.00094 sp. gr. = 1°
122
APPENDIX E
-------
102
PHASE EQUILIBRIA IN THE SYSTEM SULFUR TRIOXIDE — WATER
% FREE SO
% TOTAL SO,
% H2SO.
COMPOSITION
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90
'" ioln^mmNrtOoi^co^ioiS^SmPjrt
iHN(tj^iriu)fs*o6odo»C5»™tcvjnj«tmifih»oo
opopo6ooopGpcpcpopop0tO)O)O)O^dO)O>>cn
rotAcoo^csjinh-QroinooocNiior^orou)
o rn esi n" ** in 10 r** oi d >-J evi m ^ ID" u> co oi o
Freezing points over the entire system were determined by the equilibrium method with
purified oleum.
Determinations made at the Case School of Applied Science, Cleveland, Ohio, by S. H. Maron
and H. F. Betz.
Figure El — Oleum freezing point diagram(22).
APPENDIX E
123
-------
REFERENCES
1. Ludwig, J. H., and W. F. Bixby. Atmospheric emissions from mineral acid
manufacturing processes: MCA-PHS cooperative study project. Presented
at East Central Sect. Meeting of Air Pollution Control Association, Cleve-
land, Ohio. Sept., 1963.
2. Bureau of the Census, U. S. Dept. of Commerce.
1939 — Census of Manufacturers.
1947 — Census of Manufacturers.
1953 — Facts for Industry; Inorganic Chemicals and Gases, Ser. M19A.
1954 — Census of Manufacturers; Industrial Inorganic Chemicals,
Bull. MC-28A.
1955-56 — Inorganic Chemicals and Gases, Ser. M19A.
1957 and
later — Current Industrial Reports, Ser. 28A.
3. Minerals yearbook. Bureau of Mines, U. S. Dept. of Interior, Washington,
D. C., 1963.
4. Jones, '£. M. Chamber process manufacture of sulfuric acid. Eng. Chem.
42:2208-10. Nov., 1950.
5. Fairlee, Andrew. Sulfuric acid manufacture. A.C.S. Mono. 69. Reinhold
Pub. Co., New York, N.Y., 1936.
6. Duecker, W. W., and J. J. West. Manufacture of sulfuric acid. A.C.S.
Mono. 144. Reinhold Pub. Co., New York, N.Y., 1959.
7. Monsanto designed sulfuric acid plants. Tech. Bull. Monsanto Co., St.
Louis, Mo., 1961.
8. Sulfuric acid process reduces pollution. Chem. Eng. News. 42:42-43.
Dec. 21, 1964.
9. SO., conversion charts when burning sulfur with air. Tech. data. Mon-
santo Co., St. Louis, Mo.
10. SO.j conversion charts for sulfur burning plants with no air quench. Tech.
Data. Monsanto Co., St. Louis, Mo. 1954.
11. SO2 conversion charts for air quench plants burning sulfur. Tech. Data.
Monsanto Co., St. Louis, Mo. 1954.
12. Brink, J. A., Jr. Air pollution control with fiber mist eliminators. Can. J.
Chem. Eng. 41:134-38. June, 1963.
13. Massey, O. D. How well do filters trap stray stack mist. Chem. Eng.
66:14. July 13, 1959.
14. Private communication. Chemical Construction Company, New York, N.Y.
1963.
15. Patton, W. F., and J. A. Brink, Jr. New equipment and techniques for
sampling chemical process gases. JAPCA. 13:162-66. Apr., 1963.
16. Sulfur dioxide gas test (Reich test) for sulfuric acid plants either utilizing
or not utilizing air quench. Tech. Methods, Eng. Sales Dept., Monsanto
Co., St. Louis, Mo.
17. Determination of sulfur dioxide and sulfur trioxide in stack gases. Emery-
ville Method Ser. 4S16/59a. Anal. Dept., Shell Development Co., Emery-
ville, Calif. 1959.
18. Gas analysis of sulfuric acid plants. Tech. Method, R. and D. Lab., Chem-
ical Construction Corp., New York, N.Y. Aug., 1961.
REFERENCES 125
-------
19. Beatty, R. L., L. B. Berger, and H. H. Schrenk. Determination of oxides
of nitrogen by the phenoldisulfonic acid method. R. I. 3687. Bureau of
Mines, U. S. Dept. Interior. Feb., 1943.
20. Saltzman, B. E. Colorimetric microdetermination of nitrogen dioxide in
the atmosphere. Anal. Chem. 26:1949-55. Dec., 1954.
21. Private communications. Mr. W. E. Chalfant, Atlantic Refining Co., Phil-
adelphia, Pa., July, 1964. American Petroleum Institute study group for
developing a method for the determination of sulfur trioxide and sulfur
dioxide in stack gases.
22. Mfg. Chemists' Assoc. Tech. Chart, Manual Sheet T-8, Washington, D. C.
23. Mfg. Chemists' Assoc. Tech. Chart, Manual Sheet T-7, Washington, D. C.
24. Mfg. Chemists' Assoc. Tech. Chart, Manual Sheet T-7A. Washington, D. C.
126 REFERENCES
-------
SUBJECT INDEX
Air pollution potential, 16
Acid mist and spray. See also Emis-
sions from contact process
collectors, 38-40, 53-57
determination, 41, 61-67, 82-84
formation of, 30-33
process control methods, 35-37
Analytical techniques, 59-97
Catalysts, 12, 24-25
Ceramic filters, 39
Chamber process, 3-6, 11-16, 51
Concentrators, 4, 34
Contact processes, 3-5, 16-40, 52-55
Control methods, 4, 5, 15, 35-40, 54
Definitions, 44
Electrostatic precipitators, 4, 21, 24,
28, 32, 36, 39
Fiber mist eliminators, 4, 5, 28, 39, 40
Emissions from chamber process
acid mist and spray, 4, 5
composition, 3, 4, 14, 51
control methods, 6, 15
guides, 5
operating factors affecting emis-
sions, 15
range of emissions, 14
startup and shutdown losses, 15
Emissions from contact process
acid mist and spray, 3, 26-33, 51-57
causes, 101-105
composition, 25, 51-57
control methods, 4, 5, 35-40, 54
guides, 5
shutdown and startup losses, 33
sulfur dioxide, 25
sulfur trioxide, 29, 35
Glossary, 43
Hydrogen sulfide burning plants, 24
Metallurgical plants, 21
Nitrogen oxides
chamber process, 3, 12, 14-16
determination, 42, 92-95
losses, 14
Nitrosyl sulfuric acid, 12
Oleum, 20, 32, 35, 40, 44, 52-57
freezing points, 123
Packed bed mist and spray separators,
40
Smelter gas plants, 21
Spent acid plants, 24
Stacks, 36, 37
Sulfide ores plants, 21
Sulfur, 11
losses, 34
Sulfur-burning plants, 17-21
Sulfur dioxide. See also Emissions
from contact process
control methods, 35, 36
conversion to sulfur trioxide, 25, 26
Sulfur trioxide. See also Emissions
from contact process
determination, 41, 42, 67-80, 85-87
production, 12, 16, 17
recovery, 37, 38
determination, 41, 42, 85-92
Sulfuric acid
density of, 119
growth of industry, 3, 7-9
plants in U. S., 109-115
production, 3, 7-9
raw materials, 11
Venturi scrubbers, 39
Wire-mesh mist eliminators, 38
U. S. GOVERNMENT PRINTING OFFICE : 1965 O - 787-561
'SUBJECT INDEX
127
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