EPA 340/1-77-008
MAY 1977
Stationary Source Enforcement Series
NEW SOURCE PERFORMANCE STANDARDS
INSPECTION MANUAL FOR ENFORCEMENT OF
SULFURIC ACID PLANTS
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Enforcement
Office of General Enforcement
Washington, D.C. 20460
-------
INSPECTION MANUAL FOR THE
ENFORCEMENT OF NEW SOURCE PERFORMANCE STANDARDS
AS APPLIED TO CONTACT CATALYST SULFURIC ACID PLANTS
by
E. L. Calvin
F. D. Kodras
Contract No. 68-02-1322
Catalytic Project No. 42469
Task No. 9
November 1976
EPA PROJECT OFFICER: Donald F. Carey
Prepared For
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
TECHNICAL SUPPORT BRANCH
DIVISION OF STATIONARY SOURCE ENFORCEMENT
WASHINGTON, D. C. 20460
-------
DISCLAIMER
EPA REVIEW NOTICE
This report has been reviewed by the U.S. Environmental Protection Agency
(EPA) and approved for publication. Approval does not signify that the
contents necessarily reflect the views and policy of the Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
-------
ABSTRACT
This report describes an inspection manual designed 'to aid air pollution
control officials in enforcing New Source Performance Standards (NSPS) as
applied to sulfuric acid plants:
This manual includes:
1. A brief description of the processes involved including flow
diagrams with the points of emissions indicated.
2. A checklist of inspection points for process and air pollution
control equipment where emissions may occur.
3. Detailed information about the emission points for each process
and the control equipment at these points, including diagrams, in
order that an inspector can more readily identify such emission
points and determine if emissions are exceeding applicable NSPS.
4. A list and description of the operation of the critical process
control and monitoring instrumentation - presstire gages, flow meter,
etc. - which an inspector should examine to determine process rate,
emissions, and maintenance of such equipment.
5. A checklist and inspection log to be carried by the inspector for
each operation.
6. A set of recommended records and/or recordkeeping procedures which
the operator may require to be adopted so that enforcement personnel
may assess past activities and ascertain if the operator has maintained
compliance with the regulations.
iii
-------
7. Detailed information about deviations in the normal process
operating parameters which temporarily result in exceeding the
emission standards during startups, shutdowns and malfunctions and
measures which can be taken to minimize emissions in such events.
8. Detailed information on the operating parameters for each source
which should be observed prior to or during the conducting of per-
formance tests.
iv
-------
CONTENTS
Abstract iii
Table of Contents v
List of Figures vii
List of Tables viii
Acknowledgments ix
Sections
1 INTRODUCTION 1
2 STATE IMPLEMENTATION PLANS (SIP) 4
NEW SOURCE PERFORMANCE STANDARDS (NSPS)
A. Summary of NSPS 4
1. Emissions Standards 4
2. Performance Testing 9
3. Stack and Process Monitoring 9
4. Recordkeeping and Reporting 10
B. Applicability of Standards 11
3 PROCESS DESCRIPTION, ATMOSPHERIC EMISSIONS, AND EMISSION
CONTROL METHODS 13
A. Process Description 13
B. Atmospheric Emissions 18
C. Emission Control Methods ." 20
1. Sulfur Dioxide Control Methods 20
2. Acid Mist Control Methods 26
4 INSTRUMENTATION RECORDS AND REPORTS 29
A. Process Instrumentation 29
B. Control Device Instrumentation 33
C. Emissions Monitoring Instrumentation 38
D. Facility Recordkeeping 41
E. Facility Reporting 42
5 SHUTDOWN, STARTUP AND MALFUNCTIONS 50
v
-------
6 PERFORMANCE TESTS 63
A. Pretest Procedures 63
B. Process and Control Equipment Operating Conditions 64
C. Emission Test Observations 65
D. Performance Test Checklist 66
7 INSPECTION PROCEDURES 69
A. Periodic Inspection Procedures 69
B. Inspection Checklist 80
C. Inspection Follow-up Procedures 80
8 BIBLIOGRAPHY 101
REFERENCES 102
APPENDIX
A. NSPS Standards and Performance Test Methods 105
B. Visible Emission Observation Form 112
C. Suggested Contents of Stack Test Reports 115
D. Gas Conversion Graphs 118
E. Water Pollution Factors 121
F. Summary of Troubleshooting Techniques 127
VI
-------
FIGURES
Number Page
1 Single Absorption Sulfur Burning Contact Sulfuric Acid
Plant Process Flow Diagram 15
2 Dual Absorption Sulfur Burning Contact Sulfuric Acid
Plant Process Flow Diagram 16
3 Sodium Scrubber Tail Gas Cleaning System Process Flow
Diagram 22
4 Ammonia Scrubber Tail Gas Cleaning System Process Flow
Diagram 24
5 Molecular Sieve Tail Gas Cleaning System Process Flow
Diagram 27
6 Single Absorption Sulfur Burning Contact Sulfuric Acid
Plant (P & ID) Instrumentation Diagram 30
7 Dual Absorption Sulfur Burning Contact Sulfuric Acid
Plant (P & ID) Instrumentation Diagram 32
•
8 Sodium Scrubber Tail Gas Cleaning System (P & ID)
Instrumentation Diagram 34
9 Ammonia Scrubber Tail Gas Cleaning System (P & ID)
Instrumentation Diagram 36
10 Molecular Sieve Tail Gas Cleaning System (P & ID)
Instrumentation Diagram 39
vii
-------
TABLES
Number Page
1 Emission Limitation Summaries - Regulations Applicable
to Stated Sources 5
2 Recordkeeping Requirements for Sulfuric Acid Plants -
Summary 12
3 Daily Production - 100% Sulfuric Acid 44
4 NSPS Daily Recordkeeping Data Sheets - Sulfuric Acid
Plant 45
5 Excessive S02 Emissions Incident Report 57
6 Startup, Shutdown and Malfunction History 60
7 Summary of Test Methods for New and Modified Sulfuric
Acid Plants 67
8 Performance Test Checklist 68
9 Sulfur Dioxide Monitor, Calibration, Zero Adjustment and
Maintenance Checklist for NSPS Performance Test 84
10 Preinspection Data Sheet 87
11 Typical Operating Readings - Data Sheet for Sulfuric Acid
Plants 88
12 Control Equipment Scrubber Performance Checklist 89
13 Molecular Sieve Performance Checklist 92
14 Electrostatic Precipitation Performance Checklist 93
15 Records Summary and Malfunctions Record 94
16 Additional Observations and Acid Sludge Plant Inspection
Checklists 95
17 Follow-up Procedures After Inspecting Sulfuric Acid
Plant • 97
18 Typical Daily and Hourly Plant Log Sheet 98
vm
-------
ACKNOWLEDGMENTS
The authors wish to express appreciation to the operations and plant
personnel contacted. Special appreciation is expressed to the U.S. Army
Arsenal, Volunteer Army Ordinance Plant personnel, especially Mr. R.S. Twichell,
for permitting inspection of the plant and maintenance records and for pro-
viding pertinent information.
The assistance of the EPA Project Officer, Mr. Mark Antell, is acknowledged with
sincere thanks. Mr. Donald Carey, Division of Stationary Source Enforcement,
EPA, Washington, D.C., also provided valuable information and guidance.
The personnel of the Technical Library, Continuous Monitoring Branch, and
Enforcement Branch, EPA, Research Triangle Park, North Carolina, furnished
useful data during the preparation of this report. This support is greatly
appreciated.
The EPA Region IV personnel, Atlanta, Georgia, and personnel of the Florida
Department of Pollution Control, Winter Haven, Florida,supported the project
through the use of their experience and knowledge in performance testing.
Mr. Timothy J.. Browder provided excellent consulting services by his review and
comments on the draft of this Inspection Manual for Sulfur Acid Plants.
ix
-------
SECTION 1
INTRODUCTION
Federal New Source Performance Standards have been promulgated by EPA
for new sulfuric acid plants. To ensure consistent and uniform implementation
and enforcement of these standards, standardized procedures must be developed
for engineering inspection of new sources to determine compliance with the
NSPS requirements. The purpose of this manual is (1) to examine the chemical
processes and control systems likely to be incorporated into a modern sulfuric
acid plant, (2) to determine operation and maintenance practices, and (3) to
determine conditions which might affect the ability of the source to meet the
prescribed emission standards. This information is incorporated into this
technical guide for field inspection of new sources.
Under Section 111 of the Clean Air Act (42U.S.C.1857 et. seq.) as amended by
the Clean Air Amendments of 1970 (Public Law 91-604), the Administrator of the
EPA is authorized to develop and promulgate standards of performance for new
stationary sources.
The standards of performance for new sulfuric acid plants were promulgated on
December 16, 1971, and were published in the Federal Register on December 23, 1971,
Since that time these standards have been subject to several amendments.
Each state may develop a program for enforcing NSPS applicable to sources within
its'boundaries. If this program is adequate, EPA will delegate implementation
and enforcement authority to the state for all affected sources with the excep-
tion of those owned by the U.S. Government. Coordination of activities between
the state agency and the EPA, both Regional Office and Division of Stationary
Source Enforcement, is essential for effective operation of the NSPS program.
To facilitate state participation, EPA has established guidelines identifying
the administrative procedures the states should adopt to effectively implement
and enforce the NSPS program.
-------
The long-term success of the NSPS program depends essentially upon the
adoption of an effective plant inspection program. Primary functions of
the inspection program are monitoring the NSPS performance tests and routine
field surveillance. This manual provides guidelines for conducting such field
inspections. The basic inspection procedures presented in this manual should
be of use in enforcing emission regulations contained in state air quality
implementation plans.
SECTION 2 - The New Source Performance Standards and the state emission
standards that sulfuric acid plants must meet are reviewed and summarized. This
inspection manual is designed to aid air pollution control officials in enforcing
New Source Performances Standards as applied to sulfuric acid plants.
SECTION 3 - This manual includes (1) a brief description of the processes, in-
cluding flow diagrams with the points of emissions indicated, (2) a checklist
of inspection points for process and air pollution control equipment, and (3)
detailed information about the emission points for each process and the control
equipment at these points, including diagrams, in order that an inspector can
more readily identify emission points and determine if emissions are exceeding
applicable NSPS.
SECTION 4 - Includes a set of recommended records and/or recordkeeping procedures
the operator may be required to adopt so that enforcement personnel may assess
past activities and ascertain if the operator has maintained compliance with the
regulations. A list and description is given of the operation of the critical
process control and monitoring instrumentation - pressure gages, flo'w meter,
etc. - which an inspector should examine to determine process rate, emissions,
and maintenance of such equipment.
SECTION 5 - Detailed information about deviations in the normal process operating
parameters which temporarily result in exceeding the emission standards during
startups, shutdowns, and malfunctions and measures which can be taken to minimize
emissions in such events are outlined.
-------
SECTION 6 - Contains detailed information on the operating parameters for each
source which should be observed prior to or during the conducting of perform-
ance tests.
SECTION 7 - Consists of a checklist and inspection log for each operation to
be carried out by the inspector.
-------
SECTION 2
STATE IMPLEMENTATION PLANS (SIP) AND
NEW SOURCE PERFORMANCE STANDARDS (NSPS)
State Implementation Plans (SIP) regulations applicable to sulfuric acid
plants are summarized in Table 1.
Sulfuric acid production facilities can discharge sulfur dioxide as well as
acid mist and nitrogen oxides. At this time, standards of performance are
established only for sulfur dioxide, acid mist and for attendant visible
emissions which are a function of acid mist. The latter pollutant is a "non-
criteria pollutant" as defined by Section lll(d) of the Act, and requires the
establishment of state emission standards for existing sources.
SUMMARY OF NEW SOURCE PERFORMANCE STANDARDS (NSPS)
Emission Standards
Sulfur Dioxide Standard -
"(a) On and after the date on which the performance test required
to be conducted by 60.8 is completed, no owner or operator subject
to the provisions of this subpart shall cause to be discharged into
the atmosphere from any affected facility any gases which contain sulfur
dioxide in excess of 2 kg per metric ton of acid produced (4 Ib. per ton),
the production being expressed as 100 percent H SO ." (39 FR 20790,
June 14, 1974).
Acid Mist Standard -
"(a) On and after the date on which the performance test required to
be conducted by 60.8 is completed, no owner or operator subject to the
provisions of this subpart shall cause to be discharged into the atmos-
phere from any affected facility any gases which: (1) Contain acid mist,
expressed as H SO,, in excess of 0.075 kg per metric ton of acid produced
(0.15 Ib. per ton;, the production being expressed as 100 percent H-SO,.
(2) Exhibit 10 percent opacity, or greater. Where the presence of uncom-
bined water is the only reason for failure to meet the requirements of
this paragraph, such failure will not be a violation of this section."
(39 FR 20790, June 14, 1974).
-------
EMISSION LIMITATION SUMMARIES
Table 1
REGULATIONS APPLICABLE TO STATED SOURCES
Sulfuric Acid Plants
Mist
ALABAMA
ALASKA
ARIZONA
ARKANSAS30
CALIFORNIA2
COLORADO1
CONNECTICUT
DELAWARE
DIST. OF COL.
FLORIDA
GEORGIA
HAWAII
IDAHO
ILLINOIS
INDIANA
IOWA
KANSAS
KENTUCKY
LOUISIANA
MAINE .
MARYLAND
MASSACHUSETTS
MICHIGAN13
MINNESOTA
MISSISSIPPI
MONTANA
NEBRASKA
NEW HAMPSHIRE
NEW JERSEY37
NEW MEXICO
NEW YORK
NORTH CAROLINA
OHIO
OKLAHOMA34
OREGON
PENNSYLVANIA
SOUTH CAROLINA
SOUTH DAKOTA
S09
Lbs/Ton
100% Acid
0.513
0.154
0.15
0.15
0.58
0.59
0.1510
0.7
.1528
0.5
32
16
0.15
0.5
0.5
0.15
0,
0,
5
5
33
Lbs S02/Ton
100% Acid
6.5
6.5
3
4.0f
4.0
4.0C
30.08
30.09
4.011
6.5
12
4.0
6.5
4.029
2.017
4.0
27.0
6.5
4.0
6.5
10.O19
33
-------
Table 1 (continued)
Sulfuric Acid Plants
TENNESSEE
TEXAS
UTAH
VERMONT
VIRGINIA
WASHINGTON
WEST VIRGINIA26
WISCONSIN
WYOMING
AMERICA SAMOA
GUAM
PUERTO RICO
VIRGIN ISLANDS
Mist
Lbs/Ton
100% Acid
0.520
34
23
25
0.15
38
S09
Lbs S02/Ton
100% Acid
6.521
22
_34
27. O24
25
30.0 '
4.0
4.0
6.5
Table I - Footnotes
ground level standards given.
2Each county has its own regulations.
ppm by volume for existing plants; 500 ppm by volume for new plants.
new plants only; no regulations stated for existing plants.
plants constructed after January 1, 1972; 10 Ibs S02 ton 100%
acid for plants constructed before January 1, 1972.
"For new plants only; no regulation given for existing sulfuric acid
plants.
7East Chicago: Sulfuric Acid Plants - 6.5 Ibs S02/ton 100% acid;
0.5 Ibs/ton 100% acid.
Q
0 After January 1, 1974 for mist; after January 1, 1975 for S02-
9Per ton of 98% acid.
new plants only; 0.9 Ib/ton 100% acid for existing plants.
11For new plants only; 27.0 Ibs S02/ton 100% acid for existing plants.
12For all AQCR's, for new plants only; 27.0 Ibs S02/ton 100% acid for
existing sulfuric acid plants.
-------
Table I - Footnotes (continued)
regulations are for Wayne County; no regulations were stated for
the state.
new plants only; 1.7 Ibs/ton 100% acid for existing plants.
15For new plants only; 6.5 Ibs S02/ton 100% acid for existing plants.
paragraph 4704.40.
new plants only; for existing sources after December 31, 1972:
Tons/day capacity Ibs. S02/100 Ibs. S02 Type plant
200 5.0 All acid
plants except
those manufac-
turing sulfuric
acid from H2S
gas.
200 7.0 Acid plants
manufacturing
sulfuric acid
from H2S gas .
200 3.0 Sulfuric acid
plant.
1°lbs S02/100 Ibs S02 for new plants only, no regulations stated for
existing plants .
194.0 Ibs S02/ton 100% acid by July 1, 1977.
20After July 1, 1975; until July 1, 1975, 0.15 Ib/ton.
21After July 1, 1975; until July 1, 1975, 4.0 Ibs S02/ton.
2234.7 Ibs S02/hr/1000 scfm effluent flow rate for plants burning other
than elemental sulfur; 19.8 Ibs S02/hr/1000 scfm effluent flow rate for
plants burning elemental sulfur.
plants must reduce acid mist emissions to not more than 5.0 mg.
HoSO, including uncombined S02 per standard cubic foot.
elemental sulfur is used; 45 Ibs S02/ton 100% acid when other
materials are used as feed.
25Northwest APA: Sulfuric acid plants — 20 Ibs S02/ton 100% acid.
26By June 30, 1975.
-------
Table I - Footnotes (continued)
'When elemental sulfur is used; 40 Ibs S02/ton 100% acid when other
materials are used as feed.
new or modified plants only.
29sulfur trioxide emissions not to exceed 0.2 Ib SC>2/ton.
30Sulfur Dioxide
Sulfuric acid mists or sulfur trioxide |
0.20 parts per million
30.0 micrograms per cubic meter
31For all 6 AQCRS.
3^35 milligrams/dry cubic meter at standard conditions.
Commission may establish emission limitations if it is determined
that any source is causing ambient air quality standards to be exceeded.
*3 /
All new installations with a potential for emission of sulfur oxides in
an amount greater than 250 tons of sulfur per year as a gaseous or mist
effluent, shall install such controls as are necessary to result in
discharge to the atmosphere of 20% or less of input sulfur to the
effluent sulfur removal device.
35
Sulfur dioxide in tail gases from existing sulfur recovery operations
shall not exceed a concentration of 8000 ppm by volume and shall not
exceed a mass emission rate of:
Sulfur SO
Production Rate Mass Emission Rate
(tons/day) (Ibs/hr)
50 415
100 830
200 k 1660
300 2490
400 3320
500 4150
o/:
For plants constructed after April 3, 1972; 5.5 Ibs/ton after July 1, 1975.
37
Maximum S02 concentration from a stack is limited to 2000 ppm. Quantita-
tive allowable emission rate for sulfur compounds in the form of gases,
vapors, or liquid particles is a function of stack height and velocity and
temperature of gases through the stack.
O Q
No regulations for acid mist.
-------
Performance Testing
Compliance with the NSPS is determined only by performance tests of 60.8 con-
ducted by the operator to furnish a written report of the tests. The arithmetic
mean of three test runs will be used to determine compliance with the NSPS. The
operating conditions for the performance tests are to be representative of nor-
mal plant performance. The test conditions will be determined from records fur-
nished by the operator. The operator is to provide the following performance
testing facilities:
1. Adequate sampling ports.
2. Safe sampling platforms.
3. Safe access to sampling platforms.
4. Utilities for sampling and testing equipment.
Performance tests are to be made within 60 days of achieving the maximum
production rate, but no longer than 180 days after startup. Thirty days'
notice must be given to the EPA.
Stack and Process Monitoring
Sulfuric acid plant operations are to install, operate, calibrate, and main-
tain an instrument to continuously monitor and record sulfur dioxide emissions.
The instrument and sampling system is to be capable of providing a measurement
of emission concentration within + 20 percent with a 95 percent confidence level.
The instrument is to be calibrated using manufacturer's prescribed methods. The
manufacturer's recommended zero adjustments and calibrations are to be made once
every 24 hours or more often if recommended by the manufacturer.
-------
Recordkeeping and Reporting
All records are to be kept by the plant for two years following the date of
measurement and summary. Performance records must be made available to EPA.
Emission data shall be made available to the public. Table 2 summarizes the
items to be recorded and the frequency of data to be recorded.
The promulgation of the September 11, 1974 additions will revise the record-
keeping and reporting requirements. Data reduction will be performed monthly
rather than daily, allowing the use of computerized data reduction techniques.
Sulfuric acid plant production rate and hours of operation are to be recorded
daily.
A written report of excess emissions must be filed by the operator for each
calendar quarter. The report is due by the thirtieth day following the end
of the quarter and is required only if excess emissions occurred. The report
shall include:
1. Magnitude of excess emissions by monitoring equipment reduced to
units of the standard.
2. Date of excess emissions.
3. Time excess emissions started.
4. Time excess emissions were corrected.
5. Identify cause of excess emissions such as startup, shutdown, or
malfunction.
6. Nature and cause of any malfunction.
10
-------
7. Corrective action taken to correct malfunction.
8. Measures adopted to prevent reoccurrence.
Emissions occurring two or more consecutive hours with average sulfur dioxide
concentration exceeding four pounds per ton of acid produced must be reported.
(Refer to Section 5)
APPLICABILITY OF STANDARDS
These performance standards shall apply to contact process sulfuric acid and
oleum facilities that burn elemental sulfur, alkylation acid, hydrogen sulfide,
organic sulfides, mercaptans, or acid sludge. They do not apply to metallurgical
plants that use acid plants as SO- control systems, or to chamber process plants
or acid concentrators.
11
-------
Table 2
RECORDKEEPING REQUIREMENTS FOR
SULFURIC ACID PLANTS
Item
Plume from state exit
so2
Acid Mist
Production rate - Sulfuric Acid,
100%
Compliance tests
Instrumentation calibration
Malfunctions, startup
shutdowns, etc.
Applicable to
Burning Sulfur
All3
All
All
All
All
All
All
Recordkeeping
Frequency
Continuous
Continuous
Continuous
Daily
As required
As required
As required
Comments*
Convert to opacity.
Convert to Ib/MM Btu, required
for use of low-sulfur fuel.
Convert to Ib.
Daily hours of production.
Contact process burning elemental sulfur, alkylation acid, hydrogen sulfide, organic sulfides,
mercaptans, or acid sludge, but does not include pyritic ores, smelters and roaster cleanup.
Revised Federal Register, Vol. 38, No. 84, May 2, 1973. Quarterly reports are required including
malfunction, corrective actions and preventive means.
* Refer to Appendix "A".
-------
SECTION 3
PROCESS DESCRIPTION, ATMOSPHERIC EMISSIONS,
AND EMISSION CONTROL METHODS
PROCESS DESCRIPTION
Contact Sulfuric Acid Process
Although variations occur in feed or application, all contact acid plants
contain the same five operations.
1. Burning sulfur or sulfur bearing feeds to produce sulfur dioxide.
2. Cooling the dilute sulfur dioxide gas.
3. Catalytic oxidation of the sulfur dioxide to sulfur trioxide.
4. Cooling the oxidized gas containing sulfur trioxide.
5. Absorbing sulfur trioxide in strong sulfuric acid.
The simplest contact plant configuration uses elemental sulfur as feed. When
acid or acid sludge feeds are used, additional processing steps must be added
to remove water and particulate matter before processing the combustion pro-
ducts in the catalytic converter. Plant feed variations will affect the sulfur
conversion ratio, the volume of exhaust gases, and the character and amount of
pollution emitted. The processes discussed will use elemental sulfur as feed.
References (1), (2), (3), and (4) outline detailed process descriptions for
additional acid plant background information.
13
-------
Single Absorption Process
A simplified process flow diagram for a single absorption contact sulfuric
acid plant burning elemental sulfur is presented in Figure 1.
Cooling Sulfur Trioxide Gas
The gas leaving the converter heats boiler feed water in an economizer before
going to the acid absorber.
Absorbing Sulfur Trioxide
The final sulfuric acid product is manufactured by passing the gases through
an absorption tower. Product acid strengths can be varied by controlling the
water makeup to the acid circulating system. Absorption efficiency is affected
by the temperature of the absorbing acid.
If fuming sulfuric acid or oleum is required, a portion of the gases containing
sulfur trioxide leaving the economizer are passed through oleum towers where
sulfur trioxide is absorbed in re-circulated oleum with makeup 98.5 percent acid.
The gas stream leaving the oleum tower is stripped of sulfur trioxide by passing
through a standard acid absorber containing 98.5 to 98.8 percent sulfuric acid.
Dual Absorption Processes
An example of a typical modern dual absorption plant is shown in Figure 2.
Such a plant can convert 99.7 to 99.8 percent of the sulfur dioixde to sulfur
trioxide.
The primary difference between the single and dual absorption processes is
the addition of a primary sulfur trioxide absorber for gas leaving the third
catalyst bed.
Some processes use this absorber after the second bed. The gas stream is
cooled before this interstage absorber and is reheated before going to the next
14
-------
«-
IOZ-V
f H V :""";
? ^> j i <3j°LEu
4 STAGE j "I
i > i i / CONVERTER 1 If
/\ 1 — I 1 ->- • WITH 1 lo
1 -UUTJlV ^ 1 ~*~~r-M /iM" INTERCOOLERS 1 1 \ /
tsULnrMURNACE WP B01UER^ /////.-. 5^. J( 1 }^
LKJ2U njaj LBHII 1 j /\ % | j / Ss
-, v,
^> ^^2:2f~±-J i t
s^r
1 . ECONOMIZER •» V.^ >/ 1 1 OPTIOWL
BOLE^V ^og x^v ^ ///// N->V— J •
"/ ^-K L... '-^ 1 B^ —
i ,
. , I t .;
xxxxx> JIB C0^ER H
W \^ ^/ DRYING 1 L— ] k. — - J
| ^ ^C _.„.. 1 ^ ^^f
^^Y n ^ "::: ^ "CI"D " « D^ ^
^sr ^.;.-^s f*( s ) oai L ^g^ I--
I y~rm I Arm » ^ — Aj — t^ .L ^
1 "^ i ' » PUMP /" \PROOUCT ACIO ^ pti \^ 4
-H STEAM)
n TOWER (OPTIONAL)
OLEUM PRODUCE
STORAGE TANK
^ *' ^
ACID MIST
ELIMINATOR
, 4S> ,
ABSORPTION
CID COOLER
1 x-iq
' EBE] .. V V ^^^f1^ ,-T*^N '- ' 1« = ( WATER 1
1 " " _ .... ^
I
SINGL^ ABSORPTION
SULFUR BURNING CONTACT
SULFURIC ACID PLANT
PROCESS FLOW DIAGRAM
FIGURE 1
A : £ ^ ^
A A A (^ IM*«D FOO COtMENT
— — ~ — , ] 1 1 < 1 1
GASES •— -*
KEY LIQUIDS >
Ml Ml ~
IMI1IIIM
aK^A.K^i
jSp**1"" ™OMI1' * m CATAiniC, IMC.
_ • — >• (=.B.*t,T-« «,w PLANT WITH 1 STAGE CONVERSION
|
A
•
C
•
I
'
-------
SULFUR BURNING CONTACT
SULFURIC ACID PLANT
PROCESS FLOW DIAGRAM
-------
catalyst bed. The type and arrangement of heat exchangers varies, but
this cooling" and reheating operation is included in all designs.
Sulfur Burning
The sulfur combustion portions of the single and dual absorption plants are
similar. Combustion air is dried in a tower with 93 to 98 percent sulfuric
acid before being introduced in the sulfur furnace. Furnaces normally
operate with gas strengths of 9-12 percent S0_.
Cooling Sulfur Dioxide Gas
The waste heat boiler is designed to permit the cooling of the gas to the
required converter inlet temperature of 795-820 F.
Catalytic Oxidation
The cooled gases pass through the first bed of the catalytic converter where
the gas temperature is increased to 1100-1130 F.
Cooling Sulfur Trioxide Gas
The high temperature gas leaving the first catalyst stage is cooled in the
No. 2 heat exchanger to about 820 F for reaction in the second catalyst bed.
Heat generated in the second catalyst bed is removed by the waste heat boiler
superheater. Heat generated in the third catalyst bed is removed by an e-
conomizer in the boiler feed water system. The cool gas flows to the primary
absorption tower after the third catalyst bed.
Primary Sulfur Trioxide Absorbing
In the primary absorption tower the concentration of sulfur trioxide in the
gas is reduced to approximately 100 parts per million by contact with 98.5
percent sulfuric acid.
17
-------
Gas Reheating
4
The cold gas leaving the primary absorption tower must be reheated by
passing in parallel through No. 1 and No. 2 heat exchangers before intro-
duction to the fourth catalyst bed.
Catalytic Oxidation
Approximately 97 percent of the sulfur dioxide remaining in the gas stream
is converted to sulfur trioxide in the fourth catalyst bed. A higher overall
conversion rate than is possible in a single absorption plant and lower partial
pressure of sulfur trioxide drive the reaction with increased conversion ef-
ficiency.
Secondary Sulfur Trioxide Absorption
The gases leaving the fourth catalyst bed are cooled in a second economizer
while also heating boiler feed water. The cooled gas passes to a secondary
absorption tower containing 98.5 percent sulfuric acid. The gases leaving the
secondary absorption tower will contain about 100 to ,300 parts per million sul-
fur dioxide and will meet the existing emission standards without further pro-
cessing.
If required, an oleum tower is installed before the primary absorber and is
similar to the single absorption process.
With the exception of the primary absorber and arrangement of the heat ex-
changers, all major designs of dual absorption sulfuric plants use similar equip-
ment configurations. Design variations are found in converters, heat exchangers,
and absorbers.
ATMOSPHERIC EMISSIONS (Ref. 5, 6, and 7)
The emissions from sulfuric acid plants are sulfur dioxide, acid with acid
mist causing opacity. Organic compounds, nitrogen oxides, and nitrosyl sul-
18
-------
furic acid also appear at the exhaust stack exit along with water vapor not
removed by the drying tower and acid mist plumes.
Sulfur Dioxide Emissions
The sulfur dioxide emitted from the plant stack as effluent is the product
from the sulfur furnace that was not converted to sulfur trioxide in the
catalytic converter. This unconverted sulfur dioxide is not absorbed in the
absorber tower and is contained in the vent gas. Primary reasons for S09 not
being converted to sulfur trioxide are caused by inactive or poisoned catalyst,
insufficient process air for the catalytic conversion to sulfur trioxide, or
improper catalyst bed temperatures.
Acid Mist Emissions (Ref. 8 and 9)
The acid mist emitted from the plant results from (1) liquid sulfuric acid
carryover from absorbers; (2) sulfur trioxide in the converter reacting with
the water vapor in the process gas system preceding the converter thus producing
sulfuric acid mist; and (3) unabsorbed sulfur trioxide reacting with atmospheric
moisture. The water vapor in the process gas can come from insufficient drying
of combustion air, air leaks, steam or boiler feed water leaks or combustion of
organics in the sulfur furnace feed.
Nitrogen Oxides Emissions
Yellow vapors indicate small quantities of nitrogen oxides may be present in
sulfuric acid plant vent gases. Nitrogen oxides can come from high temperatures
and usually occur when sulfur impinges on the furnace walls or floor, or from
the combustion of organic nitrogen compounds in the furnace. Small quantities
may be produced but will increase opacity. There is no standard restricting
the nitrogen oxides from the sulfuric acid plants except indirectly through
plume opacity.
Plume Opacity (Ref. 8 and 9)
The opacity of the vent gas from a sulfuric acid plant must be less than 10
19
-------
percent unless the plume consists of uncombined water only. The presence of
acid mist, water vapor and nitrogen oxides will contribute to plume opacity.
The effect of acid mist on opacity is more dependent on the size of the mist
particles than the quantity of mist. The mist size usually ranges from 0.3
to 3.0 microns. Factors such as concentration and temperature of absorber
acid and nitrogen content of feed stock affect the quantity and size of mist.
The smaller particles scatter light more, producing a denser plume. The
effect of water vapor o-n plume opacity is also more dependent on particle
size than quantity. Nitrogen oxides will add yellow vapors to the plume.
The effect will vary from a very slight yellowish tinge to a definite yellow
cast.
Careful plant operation can minimize the effect of process conditions that
cause acid mist, excess water vapor, and nitrogen oxides, and keep the plume
opacity below the standard limits.
EMISSION CONTROL METHODS
Sulfur Dioxide Control Methods (Ref. 10, 11, 12, 13, 14, and 15)
The typical single absorption contact sulfuric acid plant is not capable of
meeting the current sulfur dioxide emission standards when using an economically
feasible converter design. The minimum sulfur dioxide concentration in the vent
gas is limited by equilibrium conditions within the catalytic converter and the
amount of catalyst that can be installed economically in the plant. Because of
these limitations the single absorption sulfuric plant must be equipped with sul-
fur dioxide removal systems to reduce the vent gas sulfur dioxide concentration
to an acceptable level.
Many processes have been proposed to perform this operation, but only three
have been included in this manual: sodium sulfite scrubber, ammonia scrubber,
and molecular sieve absorption.
Sodium Scrubber System (Ref. 16)
The sodium scrubber process is a wet regenerative system based on a sodium
sulfite/bisulfite cycle.
20
-------
The system includes absorber and chemical regeneration processes. The
reactions that take place in the process can be simplified to the following:
Absorption: S02 + Na2SC>3 + H20 — 2NaHSO
Regeneration: ZNaHSO ~ Na2s°3 + S02 + H2°
The process flow diagram is shown in Figure 3.
The sulfur dioxide rich gas is contacted counter-currently in the absorber by
the sodium sulfite solution and passes out the top stripped of sulfur dioxide.
(An absorber with inlet concentration of 1560 parts per million sulfur dioxide
and a 95 percent scrubber efficiency can achieve an emission level of 86 parts
per million sulfur dioxide)-
The condensate is recycled to the dissolving tank and the product, sulfur di-
oxide gas, is recycled to the sulfuric acid plant or claus elemental sulfur plant.
The rich slurry of sodium sulfate purged from the scrubbing system is either
(1) directly discharged to the river stream for small plants and small quantities,
or (2) the slurry is dried for direct sale to paper pulp mills.
Sodium sulfate (Na SO.), which is non-regenerable in the normal process, is
formed in the absorber from the reaction between the sulfite ion and oxygen or
sulfur trioxide as follows:
Na2S03 + 1/2 02 — Na2S04
2 Na2S03 + S03 + H20 — Na2S04 + 2NaHS03
The sodium sulfate formed is controlled at about 5 to 10 weight percent in the
cooling fractional crystallizer to minimize NaOH makeup. Sodium hydroxide is
used to replace the sodium lost in the sodium sulfate purge. This make-up
solution reacts with sodium bisulfite in the absorber to form sodium sulfite
solution:
NaOH + S02 — NaHSO
21
-------
t-02-V
.. J CLEAN ED GAS \ (EMISSION1,
f I TQ STACK / ^SOURCE-'
NJ
NJ
TAIL GAS CLEANING SYSTEM
PROCESS FLOW DIAGRAM
A:
^_
ass1
HTUVTIC. INC.
' BKOVEH
•~~A-204
-------
Ammonia Scrubber System (Ref. 17, 18, and 19)
Commercial ammonia scrubber processes based on the same chemical reactions
are available from several design companies.
The ammonia scrubber uses a solution of ammonium sulfite to form ammonium
bisulfite. The ammonium bisulfite is regenerated by reaction with ammonia to
form ammonium sulfite. The equations for the two reactions are:
This allows S0? to be absorbed and react with excess ammonia to go into the
solution. A slip stream of scrubber liquid is acidulated with sulfuric acid
releasing the S0~ which is recycled and returned to the acid plant system.
+ (NH )2SO
A flow sheet of the process is shown in Figure 4.
The primary disadvantage of this system is the generation of particulate
ammonium sulfite in the vent gas as a blue haze. The quantity of haze produced
depends upon the partial pressures of the gases in the vapor phase and cannot
v
be completely eliminated using pH control in a single stage absorption. Where
the particulate haze is not permissible in the exhaust gas from sulfuric acid
plants, it has been standard practice to equip the plant with a high efficiency
fiber type pad demister to remove the submicron particles.
Although high efficiency filters are satisfactory for particle removal, the
high pressure drop across the filter requires additional blower capacity and
energy consumption. In the acid treating process, the absorber solution over-
flow is mixed with sulfuric acid and pumped to a packed column. The reaction
of sulfuric acid and ammonium sulfite/bisulfite takes place in the column
liberating gaseous sulfur dioxide and generating ammonium sulfate. The primary
23
-------
1 La EXHAU
-*1
I
/EMISSION
•-SOURCE'
STRIPPER TOWER
*--<
HIGH EFFICIENCY
PARTICULATE COLLECTOR
/BRINK \
VFILTER/
lF-4061
_ JSO2
ISUL
FURIC ACID PLANT/
HOLDING TANK
AMMONIUM SULFATE SOLUTION
CRYSTALIZATION OR TO
OIAMMONIUM PHOSPHATE
FERTILIZER GRANULATION
AMMONIA SCRUBBER
TAIL GAS CLEANING SYSTEM
PROCESS FLOW DIAGRAM
FIGURE 1
AMMONIA VAPORIZER
IJTTO1
ANHYDROUS
\ AMMONIA
MKl
CATALYTIC. IIC.
-------
reactions of the process are shown in these equations:
The sulfur dioxide is recycled to the sulfuric acid plant while the ammonium
sulfate solution is collected for further processing.
Various processes are used for reclaiming the sulfur from the absorber solution
overflow. These include treating with sulfuric acid, to release SO- about 20-25
percent by volume and ammonium sulfate. Thermal decomposition of the resulting
ammonium sulfate to ammonium bisulfite and ammonia gas is in pilot plant develop-
ment by Tennessee Valley Authority (TVA) . The ammonium sulf ite/bisulf ite solution
also may be added.
The ammonium sulfate solution is concentrated and crystallized to produce solid
ammonium sulfate or is used in mixed fertilizers. When the acid plant is a part
of a fertilizer complex, the ammonium sulfate or ammonium sulf ite/sulfate solu-
tion is included in the diammonium phosphate production process. Mixing the
ammonium sulfate solution in fertilizer provides a low cost outlet with a secondary
use of the ammonia. The sulfur content of the solution is also valuable as a
plant nutrient. Thus, the ultimate disposal of waste products is recycled back
to the soil as fertilizer.
Molecular Sieve Adsorption Process (Ref. 19 and 20)
One of the newest sulfur dioxide recovery processes to be applied commercially
to sulfuric acid plant vent gas is the molecular sieves. Molecular sieves are
substances which selectively absorb molecules with certain characteristics, such
as shape and polarity. The adsorption cycle is followed by desorption, with an
air stream or some other gas, during which the molecular sieve is regenerated.
A number of molecular sieves are commercially available for the removal of S0~
from the tail gas. Features of such a system are:
1. High sulfur dioxide removal efficiency especially at low sulfur
dioxide concentrations.
2. Freedom*- f rom liquid handling problems.
25
-------
3. Absence of waste products.
4. Simple operation.
The adsorption efficiency of the molecular sieves is not dependent upon
flow rate or concentration of sulfur dioxide. Normal upsets in acid plant
operations do not affect the concentration of sulfur dioxide in the gas
leaving the molecular sieve system. Carbon dioxide and nitrogen oxides in
vent gas from burning acid sludge or dirty sulfur do not affect the adsorption
efficiency of the molecular sieves system.
A process flow diagram for the molecular sieve sulfur dioxide recovery system
is shown in Figure 5.
The exit gas from the molecular sieve tower contains 15 to 20 parts per million
sulfur dioxide (and normally 0-10 ppm after breakthrough).
The addition of the stripping air from molecular sieve regeneration, containing
20 to 30 percent SO- is charged to the gas leaving the furnace and will vary
the sulfur dioxide concentration entering the converter. During normal operation
this variation of sulfur dioxide entering the converter does not adversely affect
the process.
Acid Mist Control Methods (Ref. 8 and 9)
Removal of acid mist from the vent gas requires techniques different from those
used for sulfur dioxide emissions and scrubber systems. The molecular sieve
systems are equipped to remove acid mist before the adsorber tower. Additional
mist removal equipment is not necessary with these systems. Earliest mist
eliminators were beds packed with saddle or pebble packing installed in the
outlet of absorption towers. These remove spray (greater than ten microns) but
are not effective on mist (less than ten microns).
Electrostatic Precipitators (Ref. 21)
Electrostatic precipitators have been used in sulfuric acid plants for about
65 years. They are effective in removing spray and in process mist for moderate
to light loadings in preburning and gas cleaning stages. Power costs are nominal.
The drawbacks are the large size, high first cost, and heavy maintenance cost.
26
-------
A 206
MOLECULAR SIEVE
TAIL GAS CLEANING SYSTEM
PROCESS FLOW DIAGRAM
FIGURE 5
CATALYTIC, 1KC.
MOLEOJLOS £1
sts
A-206 A
-------
In general, electrostatic precipitators have been superseded by fiber type
mist eliminators for tail gas cleanup.
Dual Horizontal Fiber Pads (Ref. 22) '
Horizontal pads of fluorcarbon fibers are used for acid mist elimination.
The pads depend on impingement for mist removal. Like all impingement devices,
fiber pads are sensitive to velocity and are more effective for large particles.
Fiber Packed Mist Eliminators (Ref. 22)
Two types of fiber mist eliminators most commonly used are high efficiency (HE)
or high velocity (HV).
The high efficiency type is effective for mist and spray. These mist eliminator
elements are tubular and are made of acid-resistant glass fiber packed between
two concentric screens. One hundred elements may be used to provide enough
surface to ensure the low superficial velocity required for efficient operation.
The high velocity fiber mist eliminators are vertical panels of acid-resistant
glass fibers and are mounted in a polygon framework. The superficial velocity
through the panels (of the impingement device) is about ten times as great as
through the high efficiency type; the collection efficiency is velocity sensitive;
and the high velocity fiber mist eliminators are most effective in the removal of
large particles. In plants where the acid mist is made up of particles of three
microns and larger, the high velocity type works well, requires less space than
the high efficiency type, and can be built at a lower cost.
28
-------
SECTION 4
INSTRUMENTATION RECORDS AND REPORTS
PROCESS INSTRUMENTATION
Single Absorption Plants
Most sulfuric acid plants have automatic control systems. Figure 6, a
piping and instrumentation diagram (P&ID), shows a highly automated
single absorption acid plant.
Process parameters affecting the temperatures and sulfur dioxide concentrations
in the converter and the temperature of the acid in the absorber must be con-
trolled in any sulfuric acid plant. Acid concentration in the air dryer and
absorption tower is important for control of acid mist emissions. Another
process parameter having a strong effect on plant emmissions is plant production
rate. In compliance with EPA, the instruments regulating the flow of sulfur
and air feed to the plant have an effect on emissions from the plant.
Normally the flow of molten sulfur is adjusted to set the production rate of the
unit and the air flow is adjusted to control the temperature and sulfur dioxide
of the gas leaving the sulfur furnace. Since the gas leaving the sulfur furnace
is cooled in the heat recovery boiler, the control of the sulfur furnace tem-
perature is important in obtaining complete combustion of the sulfur without
exceeding temperature limitations of the equipment.
The temperature levels of gases in each stage of the converter are important
for maintaining high conversion efficiency. All inlet and exit catalyst
bed temperatures are recorded on a multi-point recorder with furnace and
absorption tower temperatures. This multi-point recorder provides a profile
of temperatures across the converter permitting careful malfunction monitoring
29
-------
©
©
©
©
©
0
©
©
ANALIZER ELEMENT
ANAUZER RECORDER
BUTTERFLY VALVE
FLOW ELEMENT
FLOW RECORDED
FLOW TRANSMITTER
GATE VALVE
LEVEL ALARM LOW
LEVEL INDICATOR
PRESSURE ALARM L(W
PftCSSUfE INDICATOR NANOMETRE
PRESSURE INDICATOR
PRESSURE WDKATOfi TRANSMITTER
PRESSURE SWITCH
PRESSURE TEST POOTi
TEMPERATURE RECORDER CONTROL
THERMOWELL
1 EQUIPMENT ITEM NO.
SULFUR BURNING CONTACT
SULFUR 1C ACID PLANT R&I.D
FIGURE 6
GAS
LIQUIDS
SULFUR
ERATUMC
I
I:
« • U JH.T rm WAP
Ki
CATALYTIC. IHC.
-------
and assisting in the diagnosis of problems affecting converter efficiency.
Information obtained from the multi-point recorder is used to adjust manual
control valves and setpoints of automatic control systems. Reliable and
accurate operation of this recorder is important to the operation of the plant
with low emission levels.
Absorber tower acid concentration and temperature is important for control of
acid mist emissions in the single absorption plant. If the temperatures and
concentrations of acids to the absorber and drying tower are outside control
limits, acid mist can result from improper operation of these units. Although
equipment arrangement designs in plants are not sizable, some variations in
heat exchangers are possible.
Dual Absorption Plants (Ref. 15, 23, 24, and 25)
The instrumentation and control systems for a dual absorption contact acid
(Figure 7) plant are similar to that used on the single absorption plant. The
differences in the control system of the dual and single absorption plants in-
volve controlling the temperature of the gas entering various stages of the
converter.
Although all dual absorption contact sulfuric acid plants operate on the same
principle, many variations of equipment arrangements are used by manufacturers.
The instrumentation shown on the P&ID for the dual absorption plant includes
a high degree of automation for the functions considered but does not consider
many of the auxiliary control systems required for operation of a complete
plant. The control functions shown on the P&ID are required for normal opera-
tion of the acid plants, but some of these functions may be accomplished through
manual adjustment rather than automatic control. The details of the instrumen-
tation and control system must be determined for individual plants.
The critical process parameters in the primary and secondary absorber are
temperature, flow, and concentration of the acid feed to the absorbers. If
these parameters are not controlled within specified limits, excessive acid
mist emissions can occur. In the primary absorber, high concentrations of
SO in the vent gas may be experienced.
31
-------
UJ
M
(2) ANALYZER ELEMENT
(*R) ANALYZER RECORDER
@ BUTTERFLY VALVE
@ FLOW ELEMENT
@ FLOW RECORDER
@ FLOW TRANSMITTER
@ GATE VALVE
© LEVEL ALARM LOW
(1^ tEVEL INDICATOR
@ PRESSURE ALARM LOW
@ PBESSure INDICATOR M
(PJ) PfiESSW»E INDICATOR
@ PRESSURE INDrCATOT TRANSMITTER
@ PRESSURE SWITCH
-^ PRESSURE TEST POINT
(TE) TEMPERATURE ELEME
TEMPERATURE INDICATOR
TEMPERATURE MONITOR
TEMPERATURE RECORDER CONTROL
THERMOWELL
| EQUIPMENT ITEM N«.
PRODUCT ACID STORAGE
TANK
DUAL ABSORPTION
SULFUR BURNING CONTACT
SULFURIC ACID PLANT P£I
FIGI|C:Z 7
GAS
LIQUIDS
NOMETER
RJLD.
ISSUED COB. COMMEMT 5-17
. TK IIN
M Mr «*T
CATALYTIC. INC.
A-203
-------
The temperature of acid feed to the primary and secondary absorber and the
drying tower is normally controlled by adjusting the water flow to the acid
coolers feeding these units. These controls may be manual or automatic. The
primary and secondary absorbers operate with concentrated sulfuric acid which
must be controlled within the proper concentration range to maintain acid
mist emissions at the required level. The acid circulating in the final ab-
sorption tower is passed through the drying tower to remove moisture from the air
feed to the sulfur furnace and converter. The acid concentration in the primary
and the secondary absorber systems is maintained by analyzers in each system
controlling dilution water feed to the system. Control of acid concentrations
is important. If an automatic control system is not installed or is inoperative,
manual acid concentration analysis must be run frequently to permit adjustment
of the water addition to the absorber tower systems.
Acid concentration control for the primary and secondary absorbers is important
to maintain good absorption of SO., and a "clear" stack condition.
CONTROL DEVICE INSTRUMENTATION
Sodium Scrubbing Process
Figure 8 is a sodium scrubber system P&ID. The system presented includes the
absorber and regeneration process for recovering SO and recycling scrubbing
solution.
The gas flow to the unit depends upon the load from the sulfuric acid plant.
The liquid/gas ratio in the absorbers must be maintained within limits as in
any liquid/gas system. Th^s is accomplished by recorder controllers
adjusting the flow of recirculating solution to the absorbers. The scrubber
acid pump recirculates concentrated sulfuric acid for removal of acid mist
and SO . The S0? absorber receives a recycle stream from the recovery system.
A caustic make-up flow is added to the recirculating stream to control pH of
the scrubbing solution.
33
-------
EVAPORATOR CRYSTALLIZER
WITH STEAM JET VACUUM
COOLING
SODIUM SCRUBBER
TAIL GAS CLEANING SYSTtM PUD
-------
As explained in the process descriptions, incidental oxidation of sodium sulfite
to sodium sulfate produces a component in the scrubbing solution that is inert
in the absorption of S0_. It is necessary to maintain a low concentration of
sodium sulfate to ensure efficient scrubbing of SO . This concentration is
maintained by adjusting the purge flow from the mother liquor recycle stream
by use of a flow recorder controller. This purge stream is decomposed and
recycled or disposed of as a waste.
Instruments are provided to assist in the evaluation of the flow meters mea-
suring S0~ return to the acid plant from the recovery units, condensate
flow from the evaporator condenser to the redissolving tank, and flow of liquor
from the redissolver tank to the absorber. These auxiliary instruments should
not cause malfunction of the unit but are necessary for adequate analysis and
diagnosis of problems.
Ammonia Scrubber Process (Ref. 17 and 19)
An ammonia scrubber process for removing S0_ from sulfuric acid plant tail gas
is shown on the P&ID of Figure 9. Other ammonia scrubbers have varying con-
figurations but require the same types of instruments and control systems.
The P&ID of Figure 9 shows only the absorption section since many types of re-
cycle and recovery systems are used for removing sulfur from the scrubbing
system. Generally, the recovery and recycle system does not directly affect the
operation of the ammonia scrubber or contribute to emissions from the tail gas
cleaning system.
The most important process parameters encountered in an ammonia scrubber
are liquid and gas flow through the adsorber and pH of the scrubbing liquid.
In practical installation where the ammonia scrubber is cleaning the tail gas
from a sulfuric acid plant, the gas flow is controlled by the operation of the
sulfuric acid plant and cannot be changed in the operation of the scrubber.
The gas flow is recorded and the liquid flow to the top of the absorber column
is adjusted by the setpoint of the flow recorder controller to maintain proper
liquid-to-gas (L/G) ratio (gpm/lOOOscfm).
35
-------
,'EMISSKW.
-SOURCE^
HIGH EFFICIENCY
PARTICULATE COLLECTOR
OR BRINK FILTER
I F:-I pel
AMMONIA SCRUBBER
TAIL GAS CLEANING SYSTEM PflXX
FIGURE 9
TO SULFATE \
RECOVERY SYSTEM/
AMMONIUM SULFATE SOLUTION
OR TO DIAMMONIUM PHOSPHATE
FERTILIZER GRANULATION
ANHYDROUS
AMMONIA
C1TUTTIC, IK. IK linMTIM
cofTitio ma* NII KT K no
H cwia ii HT niaor •ITMVT
IU WIITBI KMIUtM IF HE
AMMONIA SCRUBBER,
.TAIL GAS CLCANIHC SYSTEy P{L[
-------
Efficient adsorption of S0_ in the ammonia scrubber depends upon -maintaining
proper pH in the scrubbing liquid, the pH value normally ranges from 5.8 to
6.0. Careful control of ammonia flow and concentration is required to obtain
efficient scrubbing in the absorber. This control system is very important
since loss of availability of ammonia gas will result in lower pH scrubbing
solutions and excess SCL emissions from the unit.
Auxiliary equipment in the ammonia scrubbing system includes: (1) sulfur
analyzers on the inlet and outlet gaslines to show the amount of SO- removal
obtained, (2) pressure differential indicators across the columns to show the
condition of column operation, and (3) pressure gages to indicate the gas
loading in the.column. The pressure differential indicators across the column
are of value when operating the absorbers at high gas velocities and where
there is danger of flooding the column.
Molecular Sieve Process (Ref. 20)
The controller for this system is a cycle time.r to sequence valves to switch
S0_ absorbers and air dryers from absorption to regeneration.
The main process parameter requiring automatic control is the regenerating
air temperature from the air heaters. Air temperature is controlled by a re-
corder controller, if a steam preheater is used, or by the fuel flow to a fuel
fired furnace. Temperature indicators in the sulfur dioxide adsorbers and the
air dryers assist in evaluating the performance of these desiccant beds and in
determining the degree of saturation during the adsorption cycle. Differential
pressure indications across the beds provide evaluation of the condition of the
desiccant charge and will help guard against excessive flow rates.
Sulfur analyzers on the inlet and outlet streams from the SO absorbers in-
dicate the overall sulfur removal efficiency. The P&ID of Figure 10 shows the
simplified form of the basic instrumentation for this process.
37
-------
EMISSIONS MONITORING INSTRUMENTATION (Ref. 26)
The emission monitor must be maintained and must perform in accordance with the
NSPS. Measurement principles used for the development and marketing of gas
analysis instruments are:
1. Infra-red absorption
2. Colormetric titration of iodine
3. Selective permeation of S0_ through a membrane
4. Flame photometric measurement
5. Chromatographic measurement
6. Ultraviolet absorption
The ultraviolet absorption system and the iodine titration method have
received widespread application in modern sulfuric acid plants.
The principle of ultraviolet absorption by each type of gas at a specific
wave length is applied in the analyzer as the gas is passed through a 316 stain-
less steel sample tube equipped with quartz windows at each end. This beam
is divided into two portions by a prism which transmits each portion to a
separate photo detector tube. One portion of the light beam goes to an ultra-
violet filter that passes light of 578 nm wave length. This photometric signal
is the reference for comparison to the measurement signal generated by the
second ultraviolet beam going to a filter. The difference in these two signals
is amplified and sent to a recorder through proper signal conditioning equip-
ment .
38
-------
MOLECULAR SIEVE
TAIL GAS CLEANING SYSTEM Rfl.D.
FIGURE 10
KEY
KC SEQUENTIAL TIME CONTROL
— »ABSORPTION OF S02
HEATING
» COOLING
8:
A.
A
A
r»nm»ii»u m rgnmg
•wrung'MUM
. u m won
K. Tit IMOWTI
[im «ii »r H «
CATALYTIC, IHC.
BtMOVAL RECOVfE»Y TROM
_S,B,mr|vENTW
*• •)g"&b
A-206 A
-------
One advantage of this measurement system is the relative freedom from
calibration changes caused by reduction in light transmission from
dirty quartz windows or changes in the emission of light from the ultraviolet
source. Only the signal difference represents the concentration of sulfur
dioxide. The absolute values of light transmitted do not affect the output
reading.
A proper sample system is essential and must be withdrawn to obtain accurate
SO readings of the stack gas. The sample point must be far enough
downstream from the last piece of process equipment (eight stack diameters
is required by the NSPS) to provide thorough mixing. The sample system must
have appropriate filters to prevent solid material from collecting in the
filter system. These filters must be changed regularly to prevent an accumu-
lation of solids and a loss of flow.
Although the analyzer is insensitive to water vapor in the sample gas, ex-
cessive water vapor will cause an error in the sample flow rate measurement.
To1prevent condensation, the complete system must be heated from sample
probe to,analyzer.
Gas analyzing equipment requires careful and frequent service to ensure
reliable and accurate reading. The analyzer must be zeroed and calibrated
ever 24 hours using appropriate gases of known composition to ensure continued
accuracy in the SO- reading. If recommended by the manufacturer, more frequent
calibration should be made.
Most analyzers with automatic cycle control zero during each analysis cycle.
This zero is often an electrical adjustment to change the recorder reading and
does not substitute for the introduction of a zero SO concentration gas. Air
or nitrogen is often used for the zero calibration gas.
Calibration gases can be purchased from distributors equipped to mix
gas to precise specifications. It is very important that the S0_ concentration
40
-------
in calibration gas be checked periodically for consistency. The stack analysis
using the standard EPA Method 8 can be run periodically and compared to the
results obtained on the SO., analyzer. This confirmation will prove the satis-
factory performance of the sample system and the analyzer.
The calibration and operation of the SO analyzer must have a measurement
error no greater than plus or minus 20 percent and a confidence level of
95 percent.
Continuous analysis of acid mist and opacity at the sulfuric acid vent stack
is not required by the NSPS. However, when stack opacity reaches 10 percent
or greater, without considering uncombined water vapor, a record must be
maintained. Under potential failure of mist eliminator conditions and where
acid mist emissions are suspected, an analysis should be run using EPA Standard
Method 8. Details of this analysis can be found in the NSPS.
FACILITY RECORDKEEPING (Ref. 27)
Operators of sulfuric acid plants maintain operating logs, recording charts,
and laboratory analysis sheets. Each plant determines the quantity and variety
of information kept and the length of storage. The NSPS specifies the recording
and maintenance of operating information pertaining to sulfur dioxide and acid
mist emission control. The following summarizes a minimum of NSPS record-
keeping requirements:
1. A file will be maintained of monitoring and performance testing,
quarterly excess emission reports, and all other reports and records
required by NSPS.
2. Production rate and hours of operation are to be recorded daily.
(See Table 3, for example.)
3. A record is to be maintained of the occurrence and duration
of any startup, shutdown or malfunction in operation.'
(See Table 4*5 for example.)
41
-------
Records are to be retained for two years. Items directly or indirectly
associated with air pollutant emissions that should be recorded are in-
dicated in Tables 4.1 to 4.5.
The inspector can review plant performance records by completing records
during an inspection visit or by reviewing a checklist completed by facility
personnel. The latter method appreciably reduces the time required of the
inspector at each sulfuric acid production facility. The form presented in
Table 9.1 in Section 7, can be completed in either manner.
FACILITY REPORTING (Ref. 26)
All reports and other communications to the Administrator are to be submitted
in duplicate and addressed to the appropriate Regional Office of Environmental
Protection Agency, to the attention of the Director, Enforcement Division.
The minimum written reports required from the operator are:
1. Notification of anticipated date of initial startup of new
sulfuric acid plants, 30 to 60 days prior to anticipated startup
date.
2. Notification of initial startup date, within 15 days after startup.
3. Results of performance tests. These tests are to be made
within 60 days after achieving maximum production rate but not
later than 180 days after initial startup. The owner or
operator of an affected facility shall provide the Administra-
tor 30 days prior notice of the performance test to afford the
Administrator the opportunity to have an observer present.
4. A written report of excess emissions for each calendar quarter.
The report is due on the 30th day of the month following the end
of the quarter. A quarterly report is not required if no excess
emissions occurred.
42
-------
A report of excess emissions should include:
1. Magnitude of excess emissions measured by monitoring equipment
and reduced to units of the standard.
2. Date of excess emission.
3. Time excess emissions started.
4. Time emissions returned to NSPS limits,
5. Nature and cause of any malfunction,
6. Corrective action taken.
7. Preventive measures adopted.
43
-------
Table 3
DAILY PRODUCTION 100% SULFURIC ACID
DATE
TIME
START
•
TIME
SHUTDOWN
OPERATING
HOURS
PRODUCTION - 100% SULFURIC
LBS./HR.
*
TONS/HR.
METRIC
TONS/HR.
-
TOTAL
TONS
44
-------
Company Name
Plant Identification
Plant Location
Part I of V, Process Data
Table 4.1
NSPS DAILY RECORDKEEPING DATA SHEETS
SULFURIC ACID PLANT
Company Plant Code
For Week Ending
Ui
DATE
Item
Hours Operated
Feed Rate:
Air, SCFH
S02 SCFH
Process Water, gpm
Production Rate:
Tons/Hr., H2SO4 (100%)
Acid Strength, %
Sulfur Conversion Efficiency, %
WEEK AVG.
-------
Table 4.2
NSPS DAILY RECORDKEEPING DATA SHEETS
SULFURIC ACID PLANT
Part II of V, Emissions
DATE
Item
SO2, ppm (by continuous monitor)
Opacity, %
(method 9)
(unless 100% uncombined water)
Ibs. SO2/ton 100% H2SO4 (as S02>
SOs Acid Mist
NOTE: Daily averages to be weighed
averages.
NSPS
STANDARD
350 ppm
or 2KG S02/
metric ton
of 100%
H2SO4
10%
4.0
0.075 kg/MT
or OO.15 Ibs
SOs/1 ton
WEEK AVG.
-------
Table 4.3
NSPS DAILY RECORDKEEPING DATA SHEETS
SULFURIC ACID PLANT
Part III of V, Emission Control Method
CHECK APPLICABLE METHOD
CONTROL METHOD
DESIGN SPECIFICATION
PERFORMANCE LIST EFFICIENCY; %
Dual Absorption
Alkaline Scrubbing
Molecular Sieves
Absorption
DATE
Item
Time in operation, hrs.
Inlet cone., ppm SO2
Outlet cone., ppm S02
SO2 Reduction, %
NSPS
99.7%
; ''i :'•'.. ' '
WEEK AVG.
-------
Table 4.4
NSPS DAILY RECORDKEEPING DATA SHEETS
SULFURIC ACID PLANT
Part IV of V, Calibration and Maintenance
ITEM
DATE OR DATES
DESCRIPTION OF CALIBRATION AND MAINTENANCE
00
SO2 Monitor
Acid Flow (Abptn) Controller
Process Water Flow Control
Production Acid Flow Indicator, gpm
Control Device
Others:
-------
Table 4.5
NSPS DAILY RECORDKEEPING DATA SHEETS
SULFURIC ACID PLANT
Part V of V, Startup, Shutdown, and Malfunction History
Duration:
ITEM
DATE
TIME PERIOD
TOTAL TIME
Startup
Shutdown
Malfunction
Detailed Explanation:
Corrective Action Taken:
Preventive Measures Taken:
-------
SECTION 5
SHUTDOWN, STARTUP, AND MALFUNCTIONS
The pattern of malfunctions and shutdowns in sulfuric acid plants is
difficult to establish because of the variation in plant condition, age
and feedstock. A new plant can have one-half the shutdowns of an older
plant and malfunctions causing excessive emissions of less severity and
shorter duration. A plant using clean elemental sulfur feedstock can have
fewer malfunctions and less frequent excess emissions than a plant using dark
sulfur or reclaimed acid.
An evaluation of the excess emissions will include a review of plant opera-
ting records to determine the frequency and reasons for shutdowns. A high
occurrence of excess emissions may require a review of operating and mainten-
ance procedures, general plant condition, or feed, Tables 5 and 6.
SHUTDOWN (Ref. 1)
When a sulfuric acid plant is shut down, the emissions will not necessarily
rise above those produced by the malfunction that made the shutdown necessary.
The effectiveness t>f the shutdown procedure will be reflected in the emissions
during the plant startup.
Planned Shutdown
The shutdown procedure used will depend on the purpose and the work to be done
during the shutdown. The initial steps will be the same for each type. These
are:
I
1. Have available a supply of strong acid to be transferred into the
drying and absorption systems when excessive dilution occurs.
50
-------
This addition of strong acid will help reduce acid mist emissions
during the startup. Increase acid concentration in the drying
and absorbing towers to help offset moisture leakage and dilution
of absorbing acid.
2. Shut off sulfur flow and continue air flow through the sulfur
furnace.
3. Continue air flow through the furnace, converter, and absorber
for a short period until all sulfur dioxide is removed from the
furnace and sulfur trioxide is removed from the converter to the
absorber.
Unplanned Shutdowns
The emissions during an unplanned shutdown are produced by the malfunction
that caused the shutdown. If a proper shutdown procedure cannot be followed,
sulfur dioxide and sulfur trioxide will not be purged from the system and
excess emissions will probably occur during startup.
STARTUP
A sulfuric acid plant can be restarted without excessive emissions if the
temperatures in the catalyst beds of the converter and the temperature of
the furnace have not dropped below an efficient operating level. If the
temperature in the furnace and the converter have dropped below the minimum
operating conditions, then the plant will require reheating before sulfur
dioxide can be introduced into the converter. Otherwise, excessive S0_
emissions will occur. A plant restarted without preheat will emit SO- in
proportion to the length of time the plant has been shut down.
During startup, most plants will reach a-peak S0_ concentration in the vent
gas approximately two hours after introduction of sulfur to the furnace.
51
-------
By using proper startup procedures, the SO- emission concentration should
drop to compliance level within four hours.*
When a new plant has been charged with new catalyst, a startup will require
one to two days of slowly increasing production rates until full production
is reached. Plants with catalyst exposed to moisture can be in full production
without emissions in 3-4 days.
More details of shutdown, startup , and malfunction operations involving
emissions will be found in "Evaluation of Emissions During Start-up, Shutdown,
Malfunction and Normal Operating Conditions of Sulfuric Acid Plants" Task 6
Report of Contract No. 68-02-1322, EPA-600/2-76-010.
MALFUNCTIONS
Plant malfunctions causing excessive SO- and acid mist emissions can be
grouped by the process in which they occur as shown in Appendix F.
Sulfur Feed System
Malfunctions in the sulfur feed system usually cause the reduction or stop-
page of flow to the furnace and a reduction of SO feed to the converter. Loss
of sulfur feed to the furnace can be caused by plugging of the sulfur guns,
trip out of the sulfur burner pumps, or loss of heat to the sulfur melting sy-
stem. The loss of sulfur feed to the furnace will not produce excessive S0?
emissions if the flow can be reinstated before the converter temperatures have
dropped below the permissible operating range. If converter temperatures have
dropped below this permissible range, high emissions of S09 may occur until
temperatures are stabilized at the control points. Acid mist emissions can
be caused in the sulfur feed system when steam (for jacketing) leaks into the
sulfur feed pump, sulfur tranfer lines, and sulfur gun (burner). The system
*NOTE - The acid concentration in the system cannot be increased substantially
because of the narrow absorption range of SO in sulfuric acid in the
absorption tower(s). The range is usually 98.5 to 98.8%, and bad
absorption of SO occurs outside of this narrow range.
52
-------
can produce acid emissions when excessive hydrocarbons, acid, ammonia,
and halides are in the feed sulfur.
Combustion Air
Insufficient combustion air to the furnace or dilution air to the converter
is one of the most frequent causes of excessive S0_ emissions. Excessive
wear, or errosion of the blower bladesv will cause decreased air flow after
many years of operation. The clearances of the impeller blades and the casing
must be checked periodically to ensure full flow of air.
Malfunctions of Blower
The air blower unit normally is driven by a steam turbine. A reduction in
blower speed , or other malfunction causing a reduction in air flow, will result
in incomplete conversion of sulfur dioxide to sulfur trioxide in the converter
because of low oxygen/SCL ratio. Further reduction in air flow to the furnace
will cause incomplete combustion of sulfur to sulfur dioxide. The unburned
sulfur may sublime and redeposit in the catalyst beds. .When proper air flow
is restored, excess sulfur dioxide will be produced by oxidation of this sulfur
in the catalyst bed. This excess will overload the converter and produce ex-
cess sulfur dioxide emissions.
Sublimation in the furnace may cause sulfur to be deposited and burned
in the boiler tubes and cause tube failure. Sulfur deposition on catalyst
will destroy the catalyst by reducing the activity porosity and the conversion
activity. Sublimed and recondensed sulfur can also plug heat exchangers, de-
mister* media, towers, and even the acid distributor systems. A sudden failure
of the air blower causing a plant shutdown will not permit the sulfur dioxide
and sulfur trioxide to be swept out of the system. These gases will cause ex-
cessive emissions from the plant during the startup.
53
-------
Malfunction of Air Drying Tower
Too -high acid concentration can cause acid mist carryover into the furnace.
Moist air feed to the plant can be caused by a low concentration of acid
in the drying tower or a reduction of acid flow. Wet air feed to the acid
plant usually is indicated by a heavy white plume of acid mist from the
vent stack. The white plume and acid emission will continue until the plant
is shut down or concentration and flow of the drying acid is restored.
Plugging of the tower packing can occur from sulfate, dirt from the air, and
from sublimed/recondensed sulfur. This plugging can cause improper drying of
the air and lead to acid mist problems.
Errosion of acid distributors (weirs or parts) can cause improper distribution
in the packing and lead to acid mist problems caused by improper drying.
Heat Exchangers, Boiler, Superheaters, Economizers
Sulfuric acid plants are equipped with gas to liquid heat exchangers and gas
to gas heat exchangers. The most common malfunction occurring with heat exchangers
is leaks allowing water or steam to enter the process streams and producing
a dense white plume at the vent stack. Leaks to gas heat exchangers used in
dual absorption plants can allow bypassing around the converter and excess sul-
fur dioxide emissions.
CONVERTER
The most common cause of sulfur dioxide excess emissions is loss of temperature
control in the converter. Sulfuric acid plants may use automatic control or
manually adjusted dampers for establishing temperatures within the acceptable
range. It is estimated that some temperature control problems will arise on an
average of one time in each 24-hour period. If the converter temperatures
54
-------
deviate from the normal setpoint by more than one to two percent, inefficient
conversion to SO will occur. Careful operator attention to the SO analyzer
in the vent stack should permit early detection and quick correction of these
problems. Converter malfunctions can occur as a result of converter grates
failing (breaking) and dumping the catalyst from the bed. This malfunction
will cause gas bypassing and loss of conversion efficiency. Catalyst loss
of activity can result from foreign material such as excess moisture, sulfur,
halides, (fluorine, etc.), dust, etc. in the gas stream.
Mist Eliminator
Malfunction caused by errosion, shrinkage, or plugging can result in acid mist
problems. Plugging can result from condensed sulfur, dirt in the air or feed
sulfur, sulfate in the acid mist carryover, or sulfate dripping on these units
from the tower's top, outlet elbows, or stacks.
Careful operator attention should permit early detection and quick correction
of these problems.
Absorber and Strong Acid Systems
In a dual absorption plant the concentration of absorber acid feeding the
primary .and secondary absorbers can contribute to SO and SO emissions from
£• «J
the plant. Control system failure can produce high or low concentrations of
acid in circulation. A failure to maintain proper acid circulation will produce
acid concentration changes and an inefficient operation of the absorbers. Also,
loss of temperature control will result in inefficient absorber operation.
Plugging or improper distribution of acid can cause similar problems with the
absorbers. Any deviation from the concentration flow or temperature range per-
missible for efficient S0_ absorption will cause sulfur trioxide emissions and
acid mist from the plant. High inlet gas temperatures to absorption or oleum
towers will also produce acid mist plumes. If the problem occurs in the primary
absorber, the S0_ concentration in the vent also will increase since the ef-
ficiency will be reduced by the increased SO concentration in the gas. Drastic
55
-------
changes of acid concentration or temperature control in any of the towers,
and especially in the final absorber, will result in S03 emissions. Most
commonly, failure of an acid circulating pump, loss of dilution water supply,
or instrument malfunction causes these changes. Liquid sulfuric acid carry-
over can result from a plugged demister in the final absorber tower. Exces-
sive flow rates through the absorber will also cause this type of acid mist
emissions.
Sulfur Dioxide and Acid Mist Emission Control Systems
In a single absorption acid plant equipped with a tail gas cleaning system
high emissions are caused by a malfunction in the cleaning system rather than
in the acid plant. In the sodium and ammonium scrubbing systems, the most common
causes of excess emissions are loss of solution concentration control, absorber
solution pH control systems failure, loss of absorber solution circulation,
and improper temperature control. These conditions can result from failure
of circulating pumps, instrument failure, or improper operation of ammonia
vaporizer.
Most ammonia scrubber systems are equipped^with a sulfur recovery system that
does not directly affect the operation. Failure in the recovery system should
not cause emissions from the scrubber. The sodium scrubber system, however,
depends upon recycled solution from the recovery system as makeup to the scrubber.
Any plugging of the crystallizer-evaporator or failure of instrument or pumping
systems causing a change in the concentration or flow of absorber solution cause
high SO emissions.
Malfunction of the sodium and ammonium scrubbing systems is caused by the opera-
tion of the scrubbers at a gas rate in excess of design conditions or with
a scrubbing solution concentration below the required level.
Because of the simple design of the molecular sieve SO adsorption system, most
malfunctions will result from instrument failure or in cycle timer failures.
Failure of the air blower will prevent regeneration of an SO adsorber and
cause high emissions when the unregenerated adsorber is automatically placed
back in operation.
56
-------
Table 5
EXCESSIVE S02 EMISSIONS INCIDENT
Date: _____ Time:
Shift:
Shift Foreman:
1. Maximum SC«2 level reached: ppm
2. Duration that S02 limit (300 ppm) was exceeded: hours
minutes
3. Primary cause of upset:
4. Unit data
a) Furance temperature:
b) Rate:
c) Converter temperatures:
1st pass in
1st pass out
2nd pass out
3rd pass in
3rd pass out
4th pass in _
4th pass out_
d) Acid strengths:
Interpass tower
Final Tower
e) Acid temperatures:
Interpass tower
Final tower
5. Additional information:
57
-------
TABLE 5 (continued)
SHUTDOWN PLANNING CHECKLIST
Date -
Plants -
Foreman -
1. Reason for Shutdown -
2. Will repairs require a total steam or water outage? If yes, list all
checks that were made by operations and maintenance to ensure that a
total outage is necessary for repairs -
3. Has maintenance foreman been notified of possible shutdown? Are
needed materials or spare parts available?
4. Has General Foreman been contacted? (After above steps have been taken)
5. What is the estimated time for repairs? Total time will include equipment
repairs and operations shutdown and startup. (Break down into maintenance
time and operating time).
58
-------
6. Have shift foremen from associated or dependent operations been
notified of approximate time of shutdown and steam priorities?
7. After plant shutdown is completed, have all necessary safety procedures
(valve tagging, tank entry checks, etc.) been followed?
8. Before plant startup, have all effected areas been notified?
STARTUP
1. When repairs have been completed and plants(s) are back on line, please
fill out the following:
A. Actual cause of equipment failure
B. Actual downtime? Explain any large amount of difference in actual and
estimated downtime
C. Did we have any equipment that didn't operate or respond properly during
startup? If so, have W.O.'s been written?
General Foreman - Sulfuric Plant
59
-------
Table 6
STARTUP, SHUTDOWN AND MALFUNCTION HISTORY
Date
CH Startup Time Start
O Shutdown Time Stop
Q Malfunction
SULFUR DIOXIDE
ppm
KG per metric ton
Ibs. per ton
Nature of Malfunction
Cause of Malfunction
Corrective Action Taken
Preventative Means Adopted
60
-------
CAUSE OF
TRANSIENT
CONDITION
EFFECT
ON
PROCESS
FREQUENCY DURATION
OF OF STACK
CORRECTIVE ACTION 'OCCURRENCE CONTROL EMISSIONS
Converter Bed Inlet Conversion Efficien- Manual Adjustment of Daily
Temperature Out Of cy Reduced Dampers, Adjustment
Range or Repair of Instru-
Dual Absorption Plant ments
Planned Shutdown Sulfur Feed Stopped
Dual Absorption Plant and Unit Purged of
SAP With Scrubber
SO., & SO,
Manual Adjustment of 4/Yr to
Valves and Control- 1/2 Yr.
lers
2 Hrs.
1 Hour
to 2
weeks
SO , 400 -
1,000 PPM
None
PREVENTION
OR
CONTROL
Proper Operation
and Control and
Maintenance
Proper Procedure
for Shutdown to
Facilitate Start-
up
. COMMENTS EXAMPLE *
Range of Permissible Var- Table 4A
lation From Temperature
Specifications on Inlet
Temperatures is I to 3%
of Specified Temperature
Planned Shutdown Should Figure 21
Not Cause Emissions On
Shutdown. Proper Shut-
down Minimizes Startup
Emissions
Startup Warm Plant After
Dual Absorption Plant Short Term Shutdown
«4 Hrs.)
Preheat of Plant
Required
Not 12/Yr.
4 Hrs.
< 300 PPM
SO,,
Heat Conservation
and Proper Start-
up Procedures
SO- Concentration Inlet' Table
to Converter Most Impor- 12
tant to SO. Emission
Control
11 &
Startup Cold Plant After
Dual Absorption Plant Long Term Shutdown
(> 4 Hrs.)
Startup Cold Plant After
Dual Absorption Plant Long Term Shutdown
(> 4 Hrs.)
Misoperation of
Sodium and Ammonia
Scrubber Systems
Misoperation of
Ammonia Scrubber
Systems
Operation at Gas
Flow Above Design
Limit
High Gas Flow
Rates and Solution
Concentration Too
Low
Plant Must Be Pre-
heated Up to 5 Days
1-2 Times/
Yr.
3-5 Days
Plant Receives Mini- 1-4 Times/ 4-6 Hrs.
mum Heat Before SO.
Addition
Yr.
Operate Scrubber With Daily
Gas Flow Within De-
sign
Reduce Gas Flow Rate Daily
and Increase Solution
Concentration
< 300 PPM
SO.
300 to 3000
PPM SO,
1-6 Hrs. Up to
1,200 PPM
SO,
1-6 Hrs.
Up to
1,200 PPM
SO,
Complete Preheat SO. Concentration Can
and Reduced SO. Be Kept Below NSPS
Inlet Cone. Start- With Sufficient Preheat
Figure 15
up Period 4-5
Days Using Proper
Startup Proce-
dure
Minimum Preheat
is Applied and
Inlet SO. Con-
centration is
Started At Full
Rate
Reduce Gas Flow
Rate. Proper
Instruments and
Procedures.
Operate With Gas
Flow Within De-
sign and Solution
Concentration At
7%. Proper In-
Time End Low Initial
Inlet S0_ Concentrations.
This is Ideal And Seldom
Used Because of Produc-
tion Loss During Long
Startup. Auxiliary
Prcheaters Required for
Faster Heat Up.
Startup Method Most
Commonly Used to
Minimize Startup Time
and Product Loss.
Balance With Above
Method Most Desirable
Most Common Cause of High
SO. Emissions is High Gas
Flow. More Conservative
Design Should Be Employed.
Table 11
Figure 12
& 16
Figure 22
& 23
struments
cedures .
Operation With Solution Figure
Concentration at 4% (Spec- & 22
ified Set Point) Will Re-
duce NH. Consumption But
Will Produce High SO
20
and Pro- Emissions.
* Ref. 1 - EPA-600/2-76-010
-------
CAUSE OF
TRANSIENT
CONDITION
Brink Filter On Ammo-
nia Scrubber Outlet
Inoperative
Loss of Sulfur Flow
to Furnace
High Sulfur Flow to
Furnace
Loss of Dilution
Water to Primary
Absorber
Loss of Dilution
Water to Secondary
Absorber
EFFECT
ON
PROCESS
CORRECTIVE ACTION
High Opacity and Restore Effective Op-
High SO Readings eration of Brink
On Reich Test Filter
Low SO- Inlet
Concentration
High S02 Inlet
Concentration
Restore Burner or
Pump Operation or
Unplug Burners
Reduce Sulfur Flow
to Furnace or Increase
Air for Proper S02
Concentration
Increased Absorber Restore Dilution
and Concentration Water Flow to Pump
of Acid Tank
Increased Absorber Restore Dilution
and Concentration Water Flow to Pump
of Acid Tank
FREQUENCY
OF
OCCURRENCE
1/2 Year
Frequent
Frequent
Infrequent
DURATION
OF
CONTROL
Continuous
Until
Repaired
1-4 Hours
Depends
Upon
Operator
Depends
Upon
Operator
Attention
Continuous
Until
Repaired
STACK
EMISSIONS
SO Read-
ing Up to
3,000 PPM
High Opac-
ity
None
High S02
S02 In-
creased
Small SO,
and Opac-
ity In-
crease
PREVENTION
OR
CONTROL
Repair Leak in
Brink Filter In-
ternals. Place
Booster Blower
and Brink in
Service.
Use Clean Sul-
fur, Proper
Sulfur System
Maintenance and
Operator Atten-
tion.
Control SO
Inlet Concen-
tration Consist-
ant with Catalyst
Condition
Assure Adequate
Supply and In-
strument, Mainte-
nance Operator
Inspection
COMMENTS
Brink Sometimes Bypassed
on Startup Because of
Lack of Steam for Booster
Blower. Corrosion Can
Cause Leak Around Filter
Sleeve Connections.
Loss of Sulfur Feed Will
Not Cause High SO. Unless
Extended Period Reduces
Converter Temp.
Dual Absorption Plant
Normally Uses Higher S02
Inlet Concentration Than
Single Absorption. Cata-
lyst Condition Limits
Concentration.
.Reduced SO, Absorption in
Primary Absorber Increases
SO. Exit Converter by
Equilibrium Shift In Suc-
ceeding Converter Stages.
SO, and Opacity May Be
Increased.
EXAMPLE *
Table 7
& 14
Figure 23
•
Figure 23
Figure 23
Infrequent Continuous SO, and
Until Opacity
Repaired Increased
Assure Adequate Secondary Absorber Will
Supply and In- Increase SO, and Opacity
strument, Mainte- But Will Not Increase SO
nance Operator Emissions
Inspection
Figure 23
Feed of Dark Sulfur
or Sludge Acid
Increased Water in Change Feed, Filter
System Sulfur
Continuous Acid Mist
Until Increased
Feed Change
Improved Demis- Additional Water in System Figure 17
ters and Filters Causes Generation of Acid & 19
Such As Brink Mist. Modern Dual Absorp-
Higli Efficiency tion Plants Will Remove
Most With Efficient De-
misters.
Feed of Dark Sulfur
or Sludge Acid
NO Generation in Change Feed, Filter
Furnace Sulfur
Continuous Acid Mist
Until Increase
Feed Change
Improved Derois-
ters and Filters
Such As Brink
High Efficiency.
Use of ESP
Presence of NO in Gas
Stream Causes Formation
of Acid Mist By Gas Phase
Reaction Through Combina-
tion With SO,,
* Ref. 1 - EPA-600/2-76-010
-------
SECTION 6
PERFORMANCE TESTS
Federal regulations require a performance test for a new or modified acid
plant within 180 days after plant startup.* The inspector is to observe
process and control equipment operations to ensure the tests are conducted
under correct operating conditions and proper test procedures are followed.
The purpose of the performance test is to determine if the emissions standards
will be met while the plant is operating at full design capacity under normal
conditions that create the maximum emission rate. Operating data for the pro-
cess and control of the equipment should be recorded as a comparison basis for
further plant inspection. A sample performance test checklist is given in
Table 8 at the end of this section.
PRETEST PROCEDURES
Although the New Source Performance Standards stipulate the exact procedures
for compliance, facility personnel may misunderstand or not be aware of cer-
tain parts of the regulations. The inspector is to arrange a meeting with
plant personnel to review the standards, latest revisions, and procedures
prior to the performance test.
The inspector is to ensure that plant management understands the performance
tests are valid only while operating at representative performance. At this
time all parties should agree on the parameters constituting "representative
performance". The inspector is to determine which testing firm will perform
the tests. If no representative of the firm attends the meeting, the firm
should be contacted to ensure the tests are run in accordance with the regu-
lations. The chief purpose of the meeting is to outline clearly the test and
the required test procedures.
* Refer to Appendix A for detail performance tests.
63
-------
PROCESS AND CONTROL EQUIPMENT OPERATING CONDITIONS
Process parameter values which must be established before the tests are
conducted:
1. Sulfuric Acid Production Rate
2. Sulfur Feed Rate, Sulfur Analysis
3. Air Flow Rates, Furnace, Converter, etc.
4. Percent S0?in Furnace, Converter, etc.
5. Pressure Profile of the Entire Plant
6. Representative Flows, Temperatures, Pressures (into and out of all
equipment, both process and utilities streams).
The emission data corresponding to the plant operation parameters will
0
include stack emissions for sulfur dioxide, acid mist, and opacity. Process
data recorded during the test will be used to determine the emission rates and
must be measured with sufficient accuracy to justify the reported emission values.
Emission rates are based upon the number of tons of production of 100 percent
acid per day. An acceptable method of measuring production rate must be avail-
able. Flow meters or storage tank level measurements are acceptable when pro-
perly confirmed by overall process material balances. If tank level measure-
ments are used, arrangements must be made to isolate the tank from other pro-
duction inputs or product outputs. If storage capacity is limited, this isolation
may be a disadvantage. If a flow meter is available, the readings can be used
for establishing the daily production rate. Appropriate calibration procedures
must be followed and periodic tests must be run to prove accuracy. With either
production rate, measurement method analysis must be performed on a periodic
basis to permit calculation of production on 100 percent sulfuric acid basis.
64
-------
The inspector is to review the files, inspect the plants, determine data to
be collected, and establish that all sampling requirements and necessary in-
struments are available. Operating flows, pressures, and temperatures should
be collected to provide a strong comparison base for future inspections. The
inspector is to prepare checklists and log sheets to ensure that no useful
operating or emission control data is overlooked.
The production rate expressed metric tons per hour of 100 percent sulfuric
acid shall be determined and shall be confirmed by a material balance. The
inspector must be sure that enough data is collected to provide a material
balance.
Acid mist and sulfur dioxide emissions expressed in grams per metric ton of
100 percent H_SO, shall be determined by dividing the emission rate in grams "
per hour by the acid production rate. The emission rate shall be determined
by the equation grams per hour = Q x C where Q = volumetric flow rate of the
gas in dry cubic meters at standard conditions per hour .and C is acid mist or
sulfur dioxide concentration in grams per dry cubic meters at standard condi-
tions.
EMISSION TEST OBSERVATIONS
Concentrations of sulfur dioxide and acid mist are to be determined by EPA
Standard Method 8, Determination of Sulfuric Acid Mist and Sulfur Dioxide Emis-
sions from Stationary Sources.
In this test, a gas sample is extracted from a stack sampling point and acid
mist is separated from sulfur dioxide. Both fractions are measured separately
by the barium thorin titration.
The number of vent stack sample traverse points is determined by EPA Standard
Method 1, Sample and Velocity Traverses for Stationary Sources. This procedure
determines the number and location of traverse points required to extract a
representative gas sample and velocity profile across the stack.
65
-------
The velocity and volumetric flow rate are determined by EPA Standard Method
2, Determination of Stack Gas Velocity and Volumetric Flow Rate (type S
Pitot tube).
Stack gas velocity is determined from the gas density and measurement of the
velocity using a type S (Stauscheible of Reverse Type) Pitot tube at the tra-
verse points established by Method 1.
Stack gas analysis will be made by EPA Standard Method 3, Gas Analysis for
Carbon Dioxide, Excess Air, and Dry Molecular Weight. Gas is extracted from
a sampling point and analyzed for its components using an Orsat analyzer.
Opacity determinations are to be made by a qualified observer using EPA Standard
Method 9, Visual Determination of the Opacity of Emissions from Stationary Sources.
The inspector must be familiar with test methods, record all test data, and
review procedures and calculations for compliance with regulations. A summary
of test methods is given in Table 7. When outside firms are to perform the
testing on contract, the inspector should be assured of their competence and
provide sufficient supervision to produce accurate results.
PERFORMANCE TEST CHECK LIST
Before a performance test can be run the facilities must be inspected carefully
to be sure all instruments, measuring elements, and sample points are provided
and calibrated. Operating log and performance test checklists must be pre-
pared in advance. Temperatures, pressures, composition, and flow rate data
must be collected to permit calculation of complete material balances around
the process.
Because of the variation in process equipment arrangement and instrumentation
provided, a special performance test checklist must be prepared for each plant.
The checklist should be similar to the sample shown in Table 8. Standard
operating and special stack analysis log sheets and flow rate sheets in the
plant operation should also be collected for the performance test period.
66
-------
Table 7
SUMMARY OF TEST METHODS FOR NEW AND
MODIFIED SULFURIC ACID PLANTS
POLLUTANT
SAMPLING
METHOD
TOTAL SAMPLES
PER REPETITION
PER TEST
COMMENTS
-------
Table 8
PERFORMANCE TEST CHECKLIST
Company Name
Source Code Number
Company Address
Name of Plant Contact
Unit Designation
Plant Design Capacity
Startup Date
Date Reach Design Production Rate
Performance Test Date
Feed
n Bright Sulfur
D Dark Sulfur
D Other _
Composition
Production Rate
68
-------
SECTION 7
INSPECTION PROCEDURES
Major inspection emphasis will be on checking facility records and emission
monitors to show how effective emission control has been since the last in-
spection. Records will show the current emission levels and can be used to
evaluate the accuracy of the instrument and the effectiveness of the main-
tenance program.
In contact sulfuric acid plants, all the sulfur dioxide and the acid mist
should discharge from the final absorption tower or the emission control
equipment. However, fugitive emissions of SO and acid mist from leaks in
the process equipment are an important possible source of air pollution and
must be included in the inspection.
t
INSPECTION POINTS - SULFURIC ACID MANUFACTURING
The inspection of sulfuric acid plants must take into account the interconnected,
continuous nature of the manufacturing process, since there is one point of
emission (in exit stack gases) for the major potential air contaminants. Wind-
blown sulfur, sulfur dioxide, hydrogen sulfide, sulfuric acid mist, and nitrogen
oxides arising from the manufacturing process will be emitted from the final
absorption tower or from the control equipment following the tower.
The emission potential is dependent upon the type of process, age of the plant,
whether or not oleum is produced, nature of the raw material, production rate,
operating variables, and type of control equipment.
The major tasks the inspector performs include: (1) determination of the
nature of the process as it affects air contaminant emissions, (2) examination
of operating conditions and relevant records, (3) surveillance for plume
appearance (if any), (4) determination of contaminant emission rates, and
(5) investigation of possible property damage.
69
-------
Inspection of the Premises
a. Interview
Most of the important information obtained in a sulfuric acid plant
inspection will be from the interview with the plant management. The
continuous enclosed nature of the manufacturing process precludes obtaining
extensive information by visual inspection.
The inspector will wish to learn the specific details of the process
employed, such as the nature of the sulfur source and the range in com-
position and extent of contaminants present. Even in a sulfur burning
plant the latter item can be important. The rated capacity and normal
operating rate of the plant should be obtained. Information on startup
procedures and the frequency of shutdowns and startups is desirable. The
nature of control and operating procedures and equipment should be secured.
Items of importance are SCL and 0 concentrations entering the converter,
temperatures at various points in the converter and absorption tower, and
the concentration and temperature of the absorption tower acid. The
inspector may be given the opportunity of examining operating records.
The inspector should obtain information on the efficiency of sulfur di-
oxide conversion and any collection equipment used and data on the tail
gas composition finally being discharged to the atmosphere. He should
inquire about maintenance procedures and frequency. (Ref. 28)
b. Physical Inspection
The inspector should become familiar with the physical layout of the plant.
Usually the permit application files will contain most of the plant back-
ground data, flow sheets and drawings.
70
-------
OUTSIDE OBSERVATIONS
Note plume opacity and color. Opacity of 10 percent or greater is in
violation unless caused by presence of uncombined water only. Inspect the
process equipment for gas and liquid leaks contributing to fugitive emissions
and enter in Table 9.1.
Environmental Surveillance
The only visual evidence of emissions from the contact process for sulfuric
acid manufacture is the white plume having a particle size range generally less
than three microns. Particles larger than this do not scatter light in the
visual wave length range effectively and thus may be present but not visible.
EMISSION MONITORS
The inspector is to observe a calibration and zero check of the sulfur dioxide
stack monitor. A review of the procedures, methods, and schedule of maintenance
will indicate compliance with the regulations and provide an appraisal of the
validity of recorder emission data. A record of instrument maintenance and
calibration should be made by completing Table 9.2, if not previously completed.
The sulfur storage area should be inspected to determine the potential for
wind-blown sulfur dust losses. The inspector should investigate the possibility
of hydrogen sulfide formation from molten sulfur containing hydrocarbon impurities.
Depending upon the type and age of the plant, indicating and/or recording in-
strumentation such as the following may be employed.
Temperature (process gas entering and leaving the several converter
stages and absorption towers).
Acid concentration (drying tower and absorption towers).
S09 concentration (entering the converter, entering and leaving the
71
-------
absorption tower or tail gas scrubber).
Miscellaneous flow and pressure measurements.
Tests for sulfur dioxide, oxygen, acid mist concentration, and nitrogen
oxides often can be performed manually.
The inspector should determine the capability of the plant to meet emission
control regulations or the discharge of (1) sulfur dioxide in the effluent
in excess of four pounds per ton of acid produced (two kgm per metric ton),
maximum two-hour average, (2) acid mist in the effluent in excess of 0..15
pounds per ton of acid produced (0.075 kgm per metric ton), and (3) a visible
emission. In determining compliance, the inspector should:
1. Check the number of catalyst stages - older plants that have only
two stages typically have only 90-95 percent conversion of sulfur
dioxide to sulfur trioxide. Plants with three stages of catalyst
will typically have a 96-98 percent conversion of sulfur dioxide to
sulfur trioxide. These conversion efficiencies are equivalent to
emission rates of 26 to 52 pounds per ton of acid produced.
2. Determine types of acid mist eliminators (Table 9.3). Mesh mist
eliminators with double pads will collect efficiently acid spray and
mist from a properly operated 98 percent acid absorber. Teflon mist
eliminators or high energy scrubbers are used to collect acid mist less
than three microns in size to meet an emission limit of .15 pound per
ton of acid, maximum two-hour average, expressed as ELSO, or a visible
24 '
emission.
3. Control room operating log. (Table 11)
a. Check concentration of sulfur dioxide entering and leaving the
converter. Any unconverted sulfur dioxide will pass through the
absorber to atmosphere.
72
-------
b. Check temperature of 98 percent absorber tower acid. If
the acid temperature is considerably above 180 F, excess
sulfur trioxide and acid mist can be discharged to atmosphere.
c. Determine operating rates from log and compare with design
capacity from permit system records. Operation at over
capacity can result in excessive emissions of sulfur dioxide
and acid mist.
4. Source of potential nuisance problem:
a. Effects of sulfur dioxide and acid mist on people and property.
b. Excessive emissions of sulfur dioxide during cold startups,
upset conditions or overload operations.
c. Excessive emissions of acid mist during oleum production or
improper operation of absorber.
Acid Mist Elimination (Table 9.3)
A special source of sulfur compound pollution is the acid mist which may be
discharged to the atmosphere from the absorbers or dryers in a sulfuric acid
plant. The Federal Emission Regulations limit this to 0.15 Ib. per ton of
acid produced, maximum 2-hour average, expressed as ELSO,. For a 1000 ton/day
acid plant, discharging 74,000 cu. ft./min. of air at 190°F, this limitation
corresponds to about 0.84 mg./std. cu. ft. The particle size in such a mist
is very fine, running as much as 60 percent less than 3 microns.
The collection of acid mist has been successfully carried out by the use of
fiber filter elements.
The inspector should attempt to relate tail gas concentrations and appearance
to operating parameters. This information will be useful in interpreting
causes of upsets or off-normal conditions leading to excessive discharge of
73
-------
air contaminants. It will be useful for the inspector to be present
during a startup operation to obtain first-hand information on optimum
procedures for minimizing losses. (Ref. 1 and 28)
Sulfuric Acid Mist Control (Table 9.3)
As can be seen from earlier portions of this section, acid mist emissions
3
range from 2-20 mg/SCF (70-700 mg/M ) for most of the sulfuric acid plants
operating in the United States. Although-sulfuric acid mist accounts for a
relatively small proportion of the total sulfur losses (approximately 1-10%),
it is responsible for visible plumes and is associated with material damage
and health effects at lower concentrations than is sulfur dioxide.
Operational and process factors which affect acid mist emissions are:
Improper concentration and temperature of the absorbing acid.
Amount and concentration of oleum produced.
High content of organic matter in the raw materials of a sulfur
burning plant.
High moisture content of the sulfur dioxide entering the converter.
Stack cooling of sulfur trioxide gases leaving the converter, i.e.,
sudden cooling below the acid dewpoint, resulting in condensation
of very small particles.
Presence of nitrogen oxides, which can result from excessive
temperatures in the sulfur combustion chamber, from nitrogen in
raw materials, and from arcing in electrical precipitators.
Insufficient acid circulation and lack of uniformity of acid
distribution in the absorption tower.
Improper type or dirty packing in the 98 percent absorber.
74
-------
Many sulfuric acid 'plants utilize some form of collection equipment designed
specifically for acid mist. The most common type is the two-stage knitted wire
or Teflon mesh pad. Such pads operate at relatively low pressure drop (2-3"
H_0) and are effective for acid mist- particles greater than 3 microns in size.
For particles less than 3 microns in diameter, the efficiency is much lower
(15-30%). These smaller particles are responsible for visible plumes and may
be carried for considerable distances.
Venturi scrubbers operating at a pressure drop of about 35-40" H?0 have been
used on acid concentrators where most of the acid mist particles are> 3 fji (microns)
but recently have been proposed for combined use in removing S0_ and acid mist.
Such units would not be expected to be effective for mist removal from oleum
plants.
The only devices capable of reducing all size ranges of acid mist to 0.1 mg/SCF
are glass fiber filters and electrostatic precipitators. Glass fiber filters
operate at about 8" tLO pressure drop. Electrostatic precipitators operate
at low pressure drops (about 1" H?0) but are initially quite expensive. They
are also rather large because of the low gas velocities necessary for efficient
operation.
Table 9.3 summarizes the expected performance for the acid mist collectors.
EQUIPMENT (Table 10)
Emissions can be caused by malfunctions or improper conditions in the plant,
misoperation, or equipment failures.* These causes can be evaluated by using
log sheets of past operations, data taken from current plant operations, data
from past performance tests, and plant design data. Table 9 is a checklist to
be used for recording inspection data and as a reminder of items to be inspected.
Operating data taken at each inspection will provide a reference and aid in
determining trends in operating variables.
* Reference 1 and 2
75
-------
Dual Absorption Acid Plant (Table 11)
Because of the complexity, the dual absorption acid plant may require more
detailed inspection than other types. To aid in analyzing the cause of excess
emissions, log sheets from such periods should be compared to performance tests
and design data. Deviations may show the cause of excess emissions.
It is difficult for plant operating people to detect results of a slow drift
in operating values. These trends can be detected by comparing data from
operating log sheets to performance test data. Comparison of data taken at
each routine inspection may also show a trend in operating parameters.
A probable cause of slow increases in emission levels in a dual absorption
acid plant is a reduction of catalyst efficiency from accumulation of foreign
material and loss of catalyst activity. (Ref. 1 contains details of descrip-
tion.)
To determine any changes, catalyst conversion efficiency and acid production
rates should be compared with data since the initial startup of the plant.
Plant operating people often slowly change the points on some process variable.
This requires periodic checks to re-establish the operating points. These de-
viations can be determined by comparing operating logs to performance test data
and observing current process controller setpoints.
A drift in the inlet temperatures to the catalytic converter beds will cause
high SO- emissions. High SO emissions can be caused by sudden process changes
in the primary absorber flow rates, reducing absorption efficiency. The con-
centration of the primary absorber acid should be checked when S0_ excess
emissions occur.
Acid mist emissions can be caused by failure to maintain the concentration of
the air dryer acid or the primary absorber acid at the proper value. However,
the most likely cause of acid mist emissions from a dual absorption acid plant
is plugging or corrosion of the acid mist entrainment separators. A comparison
76
-------
of pressure drop across these separators will show an increase if the separator
is plugged, or a decrease in pressure drop of the separator is caused by-
passing leaks.
critical process parameters to be checked in the dual absorption plant are
the catalyst bed temperatures and the absorber acid concentration.
SODIUM SCRUBBER PROCESSES (Table 12.1)
Acid Mist Scrubber
Acid mist that is not removed from the gas stream will flow through the sodium
scrubber and will be emitted with the vent gas.
Process operating log sheets should be scanned for deviation from normal levels.
During times of recorded excess emissions, the process parameters from these
log sheets should be compared with performance test data to determine the cause.
The most important process parameter to check in this system is the differential
pressure across the acid mist scrubber.
Sodium Scrubber (Tables 12.1 and 12.2)
The most critical part is the S02 absorber. Operating log sheets and charts
from the absorber unit should be reviewed and deviations noted. Slow drifts in
solution concentration or liquid/gas ratio should be noted. The deviations in
process parameters at the time of excessive S0_ emissions should be investigated
to determine the cause, if possible.
Appropriate information should be entered in the inspection checklist for future
reference including solution concentration and gas flow rate. (Tables 12.1, 12.2
and 12.3)
77
-------
Recovery System
Although operation of the SO absorber is the key to the sodium scrubber system,
malfunctions in the recovery system can also affect the SCL removal efficiency
and cause high emissions. Upsets or drifts in process parameters shown on the
operating log sheets should be noted and the effect on absorber efficiency eval-
uated.
The inspection checklist will include the current concentration of the make-up
solution returning to the scrubber. This is the most critical process parameter
for the recovery system.
Ammonia Scrubber System (Tables 12.1 and 12.2)
Because most ammonia scrubber systems use a once-through system rather than a
recovery process, it is likely to be influenced by problems in the recovery sys-
tem than with the sodium scrubber. Operation of the ammonia scrubber system,
however, is probably more sensitive to process variations than the sodium system.
Because of the sensitivity to some process parameters, deviations should be noted
by comparison to performance test data. Periods of high S0_ emission should be
evaluated to determine the cause. Acid mist emissions should not be a problem
unless caused by leakage of the mist eliminator or improper operation of the
Venturi scrubber. When high plume opacity occurs* pressure drop across the filter
or Venturi should be compared with the design data. An unusually high or low
pressure drop may indicate the filter is becoming plugged, or has corro.ded and
is allowing gas to bypass. An unusually low pressure drop across a Venturi scrub-
ber indicates low efficiency operation resulting from a faulty scrubber or low
gas or liquid flow rate.
High SO emissions can occur from improper ammonia concentration or excess gas
flow through the absorber. In times of SO,., emissions, these values should be
checked against performance test data to be sure operating setpoints have not
drifted from the initial value or that instruments are not malfunctioning.
78
-------
The inspection checklist should include ammonia concentration and gas flow.
Molecular Sieve Adsorption System (Table 13)
The molecular sieve adsorption system is simple to operate. Failure to meet
SO emission standards probably will be caused by degeneration of the material
in the adsorber. The highest SO emissions occur at the end of the adsorption
cycle just before the tower is switched to regeneration. Records should be
checked to determine any trend in peak S0? concentrations and cycle timer set-
tings compared to performance test data. S09 emissions concentration higher than
normal in the same cycle time could be caused by degeneration of the molecular
sieve or increased S0_ load on the adsorber.
High SO concentration in the regeneration gas, low temperature or low air flow
result in improper regeneration. These parameters should be checked on past
operating logs and compared to performance test data to assure proper operation
of the system and the equipment. Recordings from the water totalizer on the
regeneration air dryer should be checked to determine the drying efficiency.
The recording charts of SO^ emission during the adsorption and desorption cycles
and of water concentration in the air during regeneration cycles should provide
a good operation description. The inspection checklist should include regener-
ating air temperature and air flow.
Electrostatic Precipitators (ESP) (Tables 14 and 15)
Only a small number of modern sulfuric acid plants are equipped with electrostatic
precipitators to remove acid mist from the process stream. Records should
be checked for periods of high acid mist or high opacity emissions and operating
data on the ESP analyzed to determine the cause. The electrostatic precipitators
are subject to frequent failure. Maintenance records will provide an indication
of the overall operating quality of the unit. Many times low voltage (EMF) in
ESP will cause malfunctions and plume problems.
79
-------
The inspection checklist for ESP should include secondary current, voltage
and spark rate.
INSPECTION CHECKLIST
Each inspection of a sulfuric acid plant should provide sufficient checklist
data as a record of the operation during the life of the unit from performance
test through shutdown. Trends recorded in these checklists provide information
for evaluating condition of the plant, skill of operation, and quality of main-
tenance. The inspection checklist in Table 11 contains most of the critical pro-
cess parameters affecting emissions from sulfuric acid plants, but observation
should be made on any unusual occurrence that might help explain emission pro-
blems.
Comments concerning the general conditions in the plant should be included in
the checklist to point out fugitive emissions and to evaluate operation and
maintenance quality. (Tables 15 and 16)
The inspection checklist should note an excessive number of shutdowns, startups
in the plant, frequent changes in production rate, and significant changes
in the quality of sulfur feed.
INSPECTION RECORDS AND*FOLLOW-UP PROCEDURES (Tables 16 and 17)
At least half of the inspection will be reviewing plant operating records.
Emission monitoring records should be scanned and the occurrence of sulfur di-
oxide emissions noted. The standards for sulfur dioxide, acid mist, and opacity.
are listed in Section 2. Space has been provided to record these incidents.
Gas monitoring instruments record concentrations in parts per million. Appendix
B contains graphs for converting parts per million values to pounds per ton of
100 percent acid production. The sulfur dioxide concentration in the vent gas
corresponding to four pounds of sulfur dioxide per ton of 100 percent sulfuric
acid is 180 to 350 parts per million, depending on inlet SO volume percent
concentrations.
80
-------
The records of the plant feed should be scanned for any change and acid
production checked to determine if unit capacity was exceeded. Production
rates should be recorded for periods of excessive emissions.
Maintenance methods and frequency should be reviewed. Review the records of
startups, shutdowns and malfunctions, note the frequency, note action taken
to alleviate future occurrences, and record in Table 12.3.
INSPECTION FOLLOW-UP PROCEDURE (Table 17)
With the information taken during the inspection a material balance can be made
and from the emission data an evaluation of the standard can be made. This
evaluation can be used to verify the testing results when submitted by the plant
owner.
An inspection report must be prepared answering all of the questions of why, who,
what, when, where, and how (as shown in Table 17). If this is the first perform-
ance test, there is no past data. However, when later inspections are made the
prior performance records will provide a better picture of the operation practices.
Follow-up inspections shall be made about every three months, unless the plant
emissions require more or less frequent inspections.
Copies of the inspection report should be sent to the Regional Office, State
Agency, and plant owner.
ENFORCEMENT PROCEDURE (Table 17)
The objective of operation inspections is to establish compliance with parti-
culate emission regulations. In order to accomplish the above objectives, the
enforcement official needs to determine:
1. Current production levels and operating conditions.
2. Design production levels and operating conditions.
81
-------
3. Current controlled and uncontrolled particulate emission levels of
SO acid mists and S0? emissions levels.
4. Efficiency and adequacy of emission control equipment at current
and design operating levels.
Emission control equipment design capacities and operating conditions can be
obtained from design drawings and plans. These data should be obtained from
the company representative prior to physical plant inspection. Production levels
and emission control equipment operating conditions are monitored by the plant
operator and are recorded in the operator's daily log or are displayed on in-
strument panels (Table 18).
The plant will have a control booth near the units for monitoring. The enforce-
ment official should have little difficulty assessing the current operating
status of the vessels by observing the many recorders, gages and log sheets.
Emissions from an installation depend on the operating condition of the control
equipment. Part of this manual provides detailed analysis of the air pollution
control devices.
The enforcement official should observe one complete shift. Certain types of
operational data should be recorded on the inspector's worksheets. If possible,
this data should be compared to other plant records for other shifts to diagnose
whether there are any unusual temperatures, especially with respect to capacity
and SCL flow rate. Table 18 is an example of the kind of operating logs that
are commonly used.
The enforcement official should complete all inspector's worksheets for contact
acid plants. The data on each sheet can be used as a comparison of the operating
variables from inspection to inspection. As usual, the enforcement official
should verify that the ducts, fans, and abatement equipment are maintained re-
gularly and are functioning properly.
It is not only important that the control equipment be operating correctly during
82
-------
the inspector's visit, but operating continuously. The routine maintenance
of control equipment should be verified as for effective air pollution control.
It is mandatory that plant operators carry out a regular maintenance program.
Since air pollution emissions depend primarily on the abatement equipment,
the enforcement official should spend most of this time assessing the operating
condition of the air pollution control devices.
Visible emissions are the simplest means for estimating particulate control
equipment performance, and the enforcement official should estimate the percent
opacity of control equipment stack plumes. If in excess of allowable limits,
appropriate action should be taken.
Building openings should be observed for evidence of escape of inadequately
captured process fumes and, if so noted, determine point(s) of origin and require
corrective actions.
83
-------
Table 9.1
NSPS INSPECTION CHECKLIST FOR CONTACT ACID PLANTS
PERFORMANCE TEST
Company Name
Source Code Number
Company Address
Name of Plant Contact
Unit Designation Identification
Plant Design Capacity
Actual Present Capacity
Previous Inspection Date
Present Inspection Date
A. Pre-Entry Visual Observations Time Date
Weather Conditions
Stack Plume Color
Equivalent Opacity (circle one):
0 10 20 30 40 50 75
Opacity Regulation Q in compliance
I I not in compliance
Note vapor or gas leaks off dry equipment
Note fugitive dust or liquid emissions
Is S02 odor present? Strong, Detectable, Barely detectable
B. Emission Monitors Time
Transmittance
Concentrations or
Opacity % Ibs/ton 100% H2SO4
Sulfur Dioxide ppm Ibs/ton
Acid Mist ppm Ibs/ton
Calibration Gas Monitor
Gas cone. pressure readout Statis. Unsat.
(ppm) (psig) (ppm)
so2 D D
Acid Mist
Describe Ductwork Condition, Corrosion, Leaks
Maintenance Program
84
-------
Table 9.2
SULFUR DIOXIDE MONITOR
CALIBRATION, ZERO ADJUSTMENT AND MAINTENANCE
DATE
DESCRIPTION OF CALIBRATION OR MAINTENANCE
85
-------
Table 9.3 EXPECTED PERFORMANCE OF ACID MIST COLLECTION SYSTEMS
System
Efficiency
> 3 Microns
Efficiency
< 3 Microns
Emission Level
99% Acid Plants
Emission Level
Oleum Plants
oo
Wire or Teflon Mesh
Glass Fiber Filter
Electrostatic Precipitator
Venturi Scrubber
99+%
100%
99%
98%
15-30%
95-99%
100%
Low
to 2 mg/SCF
0.1 mg/SCF
0.5 mg/SCF
3 mg/SCF
to 5 mg/SCF
0.1 mg/SCF
0.1 mg/SCF
Ineffective
with < 3 micron
mist
Unless additional control equipment is used, the tail gases leaving the absorption tower are discharged
to the atmosphere. Typical tail gas concentrations from a 4-stage sulfur burning contact acid plant are
shown below:
so2
Acid Mist
1500-4000 ppm
2-20 mg./SCF
0.1-1.3 ppm
-------
Table 10
PREINSPECTION DATA SHEET
Q Adequate Information
I I Inadequate Information (Obtain needed data during first inspection)
SLUDGE ACID
FIRING CAPACITY PER BURNER
WAS UNIT A CONVERSION UNIT
IF GAS STANDBY, STATUS OF BURNER
CONTROL EQUIPMENT
Type of Cleaning Equipment
Pressure Drop Across Collector
Design Efficiency (if known)
Airflow to Control Device Inlet
Stack Diameter
Stack Height
Stack Temperature
MONITORING
Opacity Meter
Others
SO 2 Meter
S03
02 Meter
C02 Meter
Combustion Gas Analyzer
S02 Alarm
MAINTENANCE AND OPERATING RECORDS KEPT
Amount of Steam Generated
Amount of Sulfur Used
Type of Burner Used
Sulfur Burner Equipment
Instrumentation Calibration
Fans, Ductwork, Control Equipment
Rated
Normal
Maximum
Btu/hr
Btu/hr
Btu/hr
D
YES [
Left in Firebox
Pulled Out and Stored
Multiple Fuel Burner
ACFM @
YES
D
D
D
D
D
YES
D
D
D
D
in H20
%
OF
ft
ft
OF
NO
D
D
D
D
D
NO
D
D
D
D
87
-------
Table 11
Typical Operating Reading Data Sheet for Sulfurfc Plants
SULFUR SYSTEM PRODUCTION
Pit Temperature - °F
Pit Level - Inches
BLOWER FLOW RATE, SCFM
Suction - H20
Discharge - H2O
Speed - RPM
BOILER
Steam Pressure - PSIG
Water Level - Inches
Cont. Slowdown Valve Setting
GAS TEMPERATURES - °F
Gas Lvg. Sulfur Burner
Gas Lvg. No. 1 Boiler
Gas Lvg. No. 2 Boiler
Gas in No. 1 Converter Mass
Gas Lvg. No. 1 Converter Mass
Gas in No. 2 Converter Mass
Gas Lvg. No. 2 Converter Mass
Gas in No. 3 Converter Mass
Gas Lvg. No. 3 Converter Mass
Gas in No. 4 Converter Mass (1st Layer)
Gas in No. 4 Converter Mass (2nd Layer)
Gas Lvg. No. 4 Converter Mass
INTERPASS ABSORBING ACID,
EXIT GAS TEMPERATURE op
Temperature Acid to Tower °F
Pump Tank Level - Inches Acid
Dilution Water - GPM
Acid Strength - % H2S04
Acid Flow to Tower - GPM
FINAL ABSORBING ACID SYSTEM
INLET GAS TEMPERATURE °F
Temperature Acid to Tower - °F
Dilution Water - GPM
Acid Strength % H2S04
Acid Flow to Tower - GPM
Acid Flow to Sales/Storage GPM
DRYING ACID SYSTEM
Temperature Acid to Tower - °F
Pump Tank Level - Inches Acid
Dilution Water - GPM
Acid Strength - °Be or % H2SO4
Acid Flow to Tower - GPM
Exit Gas Temperature °F
GAS ANALYSIS
% SO2 Int. Converter, Reich
% SO2 Exit Stack, Reich
% SO2 Exit Recorder/Monitor
% Conversion
pH - Cooling Water
Set
Points
750°F
82QQF
800°F
800°F
790°F
200°F
160°F
98.6
190°F
160°F
-
98.6
160°F
98.6
8.8
300
99.7+
7.0
2-19
1600
266
52
4.4
195
3500
490
0
0
1715
735
735
805
1118
845
992
822
821
863
821
846
L150
42
44
98.5
4000
179
420
98.5
2320
112
--
4.0
94.62
2300
8.7
.03
= 130
99.7
6.8
2-20
1600
267
52
4.2
185
3330
490
0
0
1746
721
719
1740
795
1098
828
1000
886
832
832
864
184
42
44
98.8
4000
175
--
98.6
2340
111
43
120
93.38
1850
8.8
.03
110
99.7
6.9
Ave.
1600
266
—
100,
776
4.3
190
3467
500
..
-
1717
—
—
801
1111
840
994
823
869
824
851
851
185
-
-
98.6
160°
-
98.6
~
160°
~
•-
98.6
~
8.0
.03
120
99.83
6.9
Min.
1600
260
-
92,
262
4.2
183
3310
490
-
-
1690
_
..
795
1097
826
988
816
859
815
842
852
150
~
~
98.5
160°
-
98.5
-
160°
-
-
98.5
-
8.0
.01
50
99.75
6.8
Max.
1850
270
-
106,
593
201
3600
600
~
-
1750
~
..
806
1118
846
1001
832
886
834
866
866
185
-
-
98.9
185°
-
98.9
-
185°
-
-
98.9
-
8.9
0.04
385
99.86
7.0
800-
1100-
800-
950-
800-
875-
780-
785-
-850°F
1150°
-850°
-1000°
-850°
925
-810
815
425-
595-
425-
510-
425-
465-
415-
418-
83
-455°C
620
455°
540°
455
495
432
435
-------
Table 12.1
AIR POLLUTION CONTROL EQUIPMENT
Type
Mechanical — Mist Eliminators/Collectors Type
Interval Between Acid Drain Cleanouts
Exterior Condition of Supports D
Acid Level Indicators Q
Pressure before Collector in. H20
Pressure after Collector in.
Scrubber — Alkaline Absorbent
Scrubbing liquor flow
Pressure before scrubber
Pressure after scrubber _
Gas Flow Rate
Pressure Drop
Removal of S02 Efficiency
*
Electrostatic Precipator
Interval Between Hopper Cleanouts
Exterior Condition
Spark Rate:
RECORDKEEPING REQUIREMENTS
Item
Sulfur burned
Secondary temperature
APC Device Design Parameter
(Specify pressure drop,
corona power, water flow
rate, etc.)
hours
Satisfactory
Satisfactory
pH Level
Unsatisfactory
I I Unsatisfactory
_GPM, Temp. °F
in. H20
in. H20
SCFM
in.
Concentration,
hours
Satisfactory
Operating Voltage (KV)
[~| Unsatisfactory
sparks/minute
Operating Current (MA)
Field 1
Field 2
Field 3
Field 4
Number
Tons/day daily record; maintain
records for 3 months
maintain recording charts
for 3 months once per
shift.
89
-------
Table 12.2
CONTROL EQUIPMENT
Time
Acid Mist Scrubber
Sodium Scrubber
Ammonia Scrubber
SECTION
Pressure Drop Across Scrubber
(in H2O)
Tower Circ. Solution Temperature
OF
Solution Circ. Rate (GPM)
Solution Cone. %
Solution pH
Make-Up From Recovery Cone. %
Make-Up From Recovery pH
Gas Flow Rate SCFM
1
2
3
4
PERFORM.
TEST
90
-------
Table 12.3
INSPECTION CHECKLIST
SULFURIC ACID PLANT
EQUIPMENT MAINTENANCE
Plant Inspection
GENERAL HOUSEKEEPING
Below Average
D
Comments:
EQUIPMENT APPEARANCE
Below Average
Comments:
Below Average
D
Comments:
ge
D
Average
D
D
Above Average
n
Average
EQUIPMENT MAINTENANCE RECORDS
Preventive Maintenance Program Established
Is P.M. Program Being Followed
Number of P.M. Tasks Not Completed Last Month
Number of Forced Shutdowns Last Month
Above Average
D
L INSULATION CONDITION
ige Average
D D
^KS OBSERVED: Number
KS OBSERVED: Number
D
Severity
Severity
Above Average
D
LJ Yes |_l No
D Yes D No
/Previous Month
/Previous Month
Percent Downtime for Maintenance Last Month
/Previous Month
Number of Occurrences of High Emissions Resulting from Equipment Malfunction Reported
Last Quarter
Critical Equipment Causing the Highest Frequency or Severity of Emissions (more than one
occurence) _____ number
Is P.M. Program Adequate
D Yes D No
91
-------
Table 13
[~l Molecular Sieve
SECTION
Pressure Drop Across Tower
(in H20)
Regeneration Air Temperature
Regeneration Air Flow Rate
Exit Temperature °F
Percent SC>2 Inlet
Percent S02 Outlet
1
9
2
3
\
4
PERFORM.
TEST
92
-------
Table 14
Electrostatic Precipitator (ESP)
SECTION
Primary Current (Amps)
Primary Voltage (Volts)
Secondary Current (MA)
Secondary Voltage (KV)
Spark Rate (SPK/MIN)
Vent Gas Flow, SCFM
1
2
3
4
PERFORM.
TEST
Q High Efficiency Mist'Eliminator
Q High Velocity Mist Eliminator
Cl Dual Pad Mist Eliminator
SECTION
1
2
3
4
PERFORM.
TEST
Additional Observations
93
-------
Table 15
Records Summary
Comparison
Parameters
Perform
Test
Values
Values Over Perform Test Date
Approx.
Allow.
Value
Typical Abatement Equipment Readings During Performance Test
Parameter
Particulate Efficiency (%)
Scrubber Pressure Drop
(in. H20)
Scrubber Water Flow
Rate gpm
1000 scfm
Precipitation Spark
Rate, (spm)
Primary Voltage
Primary Amps
Flow Rate, (scfm)
Inlet temp., (°F)
Opacity or
Ringlemann No.
Unit 1
Unit 2
Unit 3
Unit 4
Average in Industry
95+%
60+
5 to 10
50 to 400
20 to 100 kv
1
30,000 to 300,000
300°
0
Malfunctions
Date
Description
Max
Monitor
Reading
Repetitious Occurrences
94
-------
Table 16
ADDITIONAL OBSERVATIONS
General Plant Appearance
Equipment Needing Attention
Fugitive Emissions and Leaks
95
-------
Table 16 (continued)
FURNACE INTERIOR- ACID SLUDGE INSPECTION CHECK
Furnace Pressure
I I positive
I I negative
A. Furnace Walls
Have operator open furnace door. Use extreme caution when looking
into furnace. Wear either a face shield or safety glasses. Use proper
filters to protect eyes against brightness of flame.
Satisfactory Unsatisfactory
Last
Maintenance
Date
B.
C.
Cracks and/or Leaks
access doors
breechings
air ducts
Interior refractory
Sludge Fired Units
Acid sludge storage tank cleaning
frequency
Sludge preheat temperature °F
Atomization pressure psi
Burner maintenance frequency
Sulfur Fired Units
Burner maintenance frequency
Flame Characteristics
Impingement on walls and arches
Flame pattern
Characteristics related to air quantities (circle)
Excess
D
D
D
D
M
I I
Sprayer
Burners
White
Totally Blue
D
D
Normal
Yellowish Orange
Blue and Yel low Mix
CONTROL PANEL INSTRUMENTATION
Satisfactory Unsatisfactory
Lack
Grey
Totally Yellow
Last
Maintenance
Date
Secondary chamber temperature
Gages reading properly
Graph recording time trace
FANS AND DUCTWORK
Fan condition
Duct condition
°F
D
D
D
D
D
96
-------
TABLE 17
FOLLOW-UP PROCEDURES AFTER INSPECTING SULFURIC ACID PLANT
Compliance Parameter
Visual emissions
Opacity, S02, 803
monitors
Control equipment
Records
Course of Action
If opacity is constantly over 10 percent,
issue citation. If plant personnel have
isolated the problem, inquire how long it
will take to remedy the situation. Enforce-
ment officer should request a compliance
schedule in a follow-up letter.
a. Not in operation - issue citation.
b. Not properly calibrated or zeroed -
advise plant personnel to implement
a satisfactory program which might
include services of outside consultants.
a. Not in operation - request in follow-up
letter schedule to repair instruments.
b. Values indicating unit out of compliance-
Determine reasons - have plant take
appropriate corrective action.
a. Not kept - Issue citation.
b. Values indicating plant is out of
compliance:
i. monitors - If SOo and/or 803 standards
are exceeded more than 5
times a month for intervals
less than 4 hours, issue
citation.
- If S02 and/or 803 standard
is exceeded more than 8
continuous hours , issue
citation.
- If opacity standard is ever
exceeded for more than 2
hours, issue citation.
c. Daily instrument zero/calibration -
Issue citation if instruments are not
zeroed and calibrated within 3 or more
consecutive days.
d. Fuel analysis - Units without S02 control
equipment must analyze fuel daily.
e. Malfunction records - If complete infor-
mation (time, levels, malfunction
description, problem correction methods)
is not recordefl for all malfunctions,
issue citation.
97
-------
Sulfuric Acid Plant:
Unit:
Table 18
PLANT LOG
Date:
Run Number
Data Sheet 1 of 3
PARAMETER
Water Content of Sulfur (wt. %)
Hydrocarbon Content of Sulfur (wt. %)
Gas Temperature to Converter (°F)
SC-2 Concentration to Converter (vol. %)
Gas Temperature to Economizer (°F)
Gas Temperature to Absorber (°F)
Stack Gas Flow Rate
Stack Gas Temperature (°F)
Stack Gas Pressure
Acid Flow Rate to Absorber (gpm)
Acid Temperature to Absorber (°F)
Acid Concentration to Absorber (wt. %)
Acid Concentration to Drying Tower (wt. %)
Acid Production Rate (Flowmeter)
Gas Temperature from No. 1 Boiler (°F)
PM TIME (MIN.)
SeeT
est Resu
ts
oo
Production Rate = TPD 100% H2S04
-------
Sulfuric Acid Plant:
Unit:
Table 18
Date:
Run Number:
Data Sheet 2 of 3
PARAMETER
Sulfur Feed Rate(% gauge)
Air Flow Rate to Drying Tower (acfm)
Air Temperature to Drying Tower (°F)
Air Pressure to Drying Tower (inches r^O)
Water Content of Air to Drying Tower
Water Content of Air to Furnace
Air Flow Rate to Furnace (acfm)
Air Temperature to Furnace (°F)
Air Pressure to Furnace
Gas Temperature from Furnace (°F)
O2 Concentration to Converter (vol. %)
Water Content of Gas to Converter
Gas Temperature from First Stage (°F)
Gas Temperature to Second Stage (°F)
Gas Temperature from Second Stage (°F)
Gas Temperature to Third Stage (°F)
PM TIME (MIN.)
VO
VO
-------
Sulfuric Acid Plant:
Unit:
Table 18
Date:
Run Number:
Data Sheet 3 of 3
PARAMETER
Gas Temperature from Third Stage (°F)
Gas Temperature to Fourth Stage (°F)
SC>2 Concentration from Absorber (vol. %)
02 Concentration from Absorber (vol. %)
Acid Temperature from Absorber (°F)
Acid Concentration from Absorber (wt. %)
Acid Flow Rate to Drying Tower (gpm)
Acid Temperature to Drying Tower (°F)
Acid Temperature from Drying Tower (°F)
Acid Concentration from Drying Tower (wt. %)
Gas Temperature from No. 2 Boiler (°F)
Conversion (%)
PM TIME (MIN.)
o
o
Remarks: Started Run No. at p.m.; finished at p.m.
-------
SECTION 8
BIBLIOGRAPHY
Waeser, B., Handbuch der Schwefelsaurefabrikation, Handbook for the
Manufacture of Sulfuric Acid, Vols. 1 to 3, Braunschweig: Vieweg,
1930.
Waeser, B., Die Schwefelsaurefabrikation, The Manufacture of Sulfuric
Acid, Braunschweig: Vieweg, 1961.
Kusnezow, D. A., Die Herstellung der Schwefelsaure, The Manufacture of
Sulfuric Acid, Leipzig: Fachbuchverlag VEB, 1954.
Duecker, W. W. and J. R. West, The Manufacture of Sulfuric Acid, New York:
Reinhold, 1959.
Fairlie: Sulfuric Acid Manufacture, New York: Reinhold, 1947.
Winnacker, K. and L. Kuchler: Chemische Technologie, Technology of
Chemistry, Vol. 2, Inorganic Technology II, 2nd ed., Munchen:
Hanser, 1959. pp. 18-70.
Ullmanns Encyklopadie der technischen Chemie, Ullmann's Encyclopedia of
Technical Chemistry, Munich. Berlin: Urban and Schwarzenberg,
1962, Vol. 12, pp. 16, 21, 129; Vol. 13, p. 107; Vol. 15, pp. 424-465.
Gmelin, Handbuch der anorganischen Chemie, Handbook of Inorganic Chemistry,
Syst. No. 9, see Part A, 1942 (reprint, 1952), pp. 286-484; Syst. No. 9,
see Part B, 2nd ed., sulfuric oxy-acids, 1960, pp. 613-798.
Werth, H., Dechema-Monographien, Dechema-Monographies, Nos. 895 to 911,
Vol. 52. Waste water- solid waster- waste gases, Weinheim:
Verlag Chemie, 1964.
Amelin, A. G., The Preparation of Sulfuric Acid from H2S According to
Wet Catalysis Methods, (Russian), Moscow: Goskhimizdat, 1960.
101
-------
REFERENCES
1. Calvin, E. L., F. D. Kodras. Evaluation of Emissions During Start-up,
Shutdown and Malfunction of Sulfuric Acid Plants. Industrial Environ-
mental Research Laboratory, EPA, by Catalytic, Inc., Charlotte, N.C.
EPA-600/2-76-010. January 1976. 353 pp.
2. Farkas, M. D. and R. R. Dukes. Multiple Routes to Sulfuric Acid,
CHEMICAL ENGINEERING PROGRESS, Vol. 64, No. 11, Nov. 1968, pp. 54-58.
3. Atmospheric Emissions from Sulfuric Acid Manufacturing Processes.
Cooperative Study Project: Manufacturing Chemists' Association, Inc.,
and Public Health Service, U. S. DHEW, PHS. Division of Air Pollution.
Cincinnati, Ohio, PHS. Publication No. 999-AP-13, 1965. 127 pp.
4. Chemical Construction Corporation. Engineering Analysis of Emissions
Control Technology for Sulfuric Acid Manufacturing Processes. Final
Report, Contract 22-69-81, Public Health Service, U.S. DHEW, PHS.
National Air Pollution Control Administration, Publication No. PB-190-
393. March 1970, Vols. I and II.
5. Moller, W., and K. Winkler. The Double Contact Process for Sulfuric
Acid Production, presented at 60th Annual Meeting APCA, Cleveland,
Ohio. June 1967, J.A.P.C.A., Vol. 18, No. 5. pp. 324-325.
6. Control Techniques for Sulfur Oxide Air Pollutants, National Air
Pollution Control Administration, Washington, D.C., Publication No.
AP-52, January 1969, pp. 3, 4, and 81.
7. Tucker, W. G.,APCO, Seattle, Washington and J. R. Burleigh, Chemical
Construction Corp. SO Emission Control from Acid Plants. CHEMICAL
ENGINEERING PROGRESS, Vol. 67, No. 5. pp. 57-63.
8. York, O.K. and E. W. Poppele. Two-Stage Mist Eliminators for Sulfuric
Acid Plants. CHEMICAL ENGINEERING PROGRESS. 6Ch 67-72, November 1970.
9. Brink, J. R. , Jr., W. F. Burggrabe, and L. E. Greenwell. Mist Elimina'tors
for Sulfuric Acid Plants. CHEMICAL ENGINEERING PROGRESS. fr4: 85,
November 1968.
10. Sulfuric Acid Process Reduces Pollution. CHEMIST ENGINEERING NEWS,
42(40): 42-43, December 21, 1964.
102
-------
REFERENCES
11. Lawler, C. Air Pollution Control by a Sulfur Dioxide Scrubbing System.
Presented at Semiannual Technical Conference of APCA, Houston, Texas.
December 1967.
12. Donovan, J. R. and P. J. Stuber. The Technology and Economics of
Interpass Absorption Sulfuric Acid Plants. American Institute of
Chemical Engineers, New York, New York. Presented at the AIChE
Meeting, Los Angeles, California. December 1-5, 1968.
13. Guidelines for Limitation of Contact Sulfuric Acid Plant Emissions.
EPA Publication No. APTD-0602 and No. APTD-0711.
14. Burkhardt, D. B. Kinetic Plots Air Catalytic Operations. CHEMICAL
ENGINEERING, June 26, 1961. pp. 115-116.
15. Burkhardt, D. B. Increasing Conversion Efficiency. CHEMICAL ENGINEER-
ING PROCESS, Vol. 64 No. 11, November 1968. pp. 66-70.
16. Pedroso, R.I. Davy Powergas Inc. Lakeland, Florida. An update of the
Wellman-Lord Flue Gas Desulfurization Process. EPA-600/2-76-136,
May 1976. pp. 719-733.
17. Ennis, C. E. APCI/IFP Regenerative FGD Ammonio Scrubbing Process.
EPA-600-2-76-136b, May 1976. pp. 865-875.
18. S02~Recovery from Sulphuric Acid Plant Off-Gases. Sulfur, No. 80.
pp. 36-38.
19. Jimeson, R. M. and R. R. Maddocks. Sulfur Compound Cleanup:
Trade-offs in Selecting SOX Emission Controls. CHEMICAL ENGINEERING
PROGRESS, August 1976. pp. 80-88.
20. Kiovsky, J. R., P- B. Koradio, and D. S. Hook. Molecular Sieves for
S02 Removal. CHEMICAL ENGINEERING PROGRESS, August 1976. pp. 98-103.
21. Stasney, E. P. Electrostatic Precipitation. CHEMICAL ENGINEERING
PROGRESS. i62:48, April 1966.
22. Shah, I. S. Acid Mist Recovery and Control. CHEMICAL ENGINEERING
PROGRESS, Vol. 67, No. 5, May 1971. pp. 50-56.
103
-------
REFERENCES
23. Remires, Raul. Double-Absorption Gets U. S. Foothold. CHEMICAL
ENGINEERING, January 27, 1969. pp. 80-82.
24. Kamimura, Yoshihiko. Double Contact Process for Sulfuric Acid
Manufacturing Facility, Ryusan (J. Sulfuric Acid Association, Japan),
20:167-177, 1967-
25. S02 Scrubber - Two Scrubbers Better Than One, CHEMICAL ENGINEERING,
New York, New York, 62: 132-134, February 1955.
26. Emission Testing Compliance Manual, PEDCo-Environmental Specialists,
Inc., EPA Contract No. 68-02-0237, Task No. 19, August 1974.
27. Standards of Performance for New Stationary Sources, Supplemental
Statement in Connection with Final Promulgation, FEDERAL REGISTER,
Vol. 37, No. 55-Tuesday, March 21, 1972.
28. Calvin, E. L., F. D. Kodras. Effect of Equipment Maintenance and
Age on Sulfuric Acid Plant Emissions. Industrial Environmental
Research Laboratory, EPA, by Catalytic, Inc., Charlotte, N.C.
EPA-600/2-76-119, April 1976. pp. 93.
104
-------
APPENDIX A
STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES
CODE OF FEDERAL REGULATIONS
105
-------
NSPS STANDARDS AND PERFORMANCE TEST METHODS
Federal Register (NSPS)
December 23, 1971
May 2, 1973
October 15, 1973
PERFORMANCE TEST METHODS
Method 1: Sample and Velocity Traverse
Method 2: Determination of Velocity and Volumetric Flow Rate
Method 3: Gas Analysis
Method 4: Determination of Moisture in Stack Gas
Method 7: Determination of No
X
Method 8: Determination of SO
Method 9: Visual Opacity Determination
106
-------
Method 1
1. Stack height and diameter.
2. Location of sample pott.
3. Location of traverse points.
Method 2
1. Stack static pressure.
2. Obtain Pitot tube coefficient.
3. Stack temperature.
4. Average traverse and temperature.
5. Barometric pressure at plant site.
Method 3
1. Gas Analysis
Method 4
1. Average stack temperature.
2. Moisture train data, meter temperature, rotameter setting, meter readings
and clock time.
3. Water volume increase.
4. Barometric pressure at plant site.
Method 7
This test is done in an analytical laboratory and the sample collection
technique is all that can be checked at the plant site. The test result must
be obtained from the analytical laboratory. The identification of the analytical
laboratory should be obtained and a check made of its reputation.
107
-------
TEST REPORT FORMAT
Process Sections
I. Table of Contents
II. Introduction
III. Summary and Discussion of Results
IV. Process Description and Operation
V. Sampling and Analytical Procedures
a. Location of Sampling Point
b. Analytical Procedures
Appendix
A. Complete Particulate Results with Example Calculations
B. Complete Gaseous Results with Example Calculations
C. Complete Operation Results (with Example Calculations)
D. Field Data
E. Operating Data Log
F. Sampling Procedure
G. Laboratory Report
H. Test Log
I. Project Participants
J. Correspondence with Source
108
-------
Performance Test
Process Operating Conditions
During the performance tests as required by the NSPS, the sulfuric
acid plant must be operated under these conditions:
1. The plant must be operated at or above its design production rate.
The acid concentration must be at or above the design concentration.
2. The plant must be operated under the same conditions as planned for
future operation.
3. The emission is expected to be at or under four pounds of sulfur
oxides as sulfur dioxide per ton of sulfuric acid produced (100% basis)
Process Observation
The total time involved for a performance test is two hours. This includes
four samples (Method 9) at one-quarter hour intervals. Additional time is
required to select the sampling point in the stack and determine the volumetric
flow rate. During the two-hour period the plant must be operated at a constant
production rate, and the acid concentration should remain essentially constant.
Process observations of the plant operation should be tabulated in log form
during this test period. An example log form for these observations is pre-
sented in Tables 17.2 to 17.4. The following minimum observations should
be logged:
Flow Rates
1. Air to Converter
2. Air to Furnace
3. SO- to Converter
4. Absorption Water to Absorber
5. Acid Production
6. Cooling Water to Absorber
7. Flow Ratio of Oxygen to SO-- Air Mixture (flow to each converter bed)
8. Fuel Gas to Abater System (if applicable)
109
-------
Temperatures
1. Air from Compressor
2. Oxygen Vapor to S02 - Air Mixture
3. Reaction Gases from Converter
4. Process Gas to the Absorber
5. Tail Gas from the Absorber
6. Tail Gas to the Abater System
7- Tail Gas from the Abater System
8. Absorption Water to Absorber
9. Product Acid from the Absorber
10. Cooling Water to the Absorber
11. Cooling Water from the Absorber
Pressures
1. Air Compressor Discharge
2. Oxygen Vapor to S0? - Air Mixture
3. Reaction Gases from the Converter
4. Process Gas to the Absorber
5. Tail Gas from the Absorber
6. Tail Gas to the Abater System
7. Tail Gas to the Expander
Analysis
1. Product Acid Concentration
2. Tail Gas to the Abater System
3. Tai;l Gas from the Abater System
4. Sulfur Dioxide Concentration in the Stack Gas (continuous, required
by NSPS)
5. Stack Opacity
6. Any other process gas analysis made by operators in plant operation
(these should be logged and identified).
110
-------
Remarks
A column should be provided to record any unusual events that affect
the plant operation and/or tests. Also check regular plant log remarks.
By having the log form prepared before the performance test and recording
the above observations at fifteen-minute intervals an operating picture is
obtained. This log will verify the operation as submitted in a permit
application or review of p.lans submitted to the EPA Administrator.
Ill
-------
APPENDIX B
VISIBLE EMISSION OBSERVATION FORM
112
-------
APPENDIX B
Date
Observer
Plant name
Plant address
Observation Point
Stack - Distance* Height
Wind - Speed Direction
Sky condition:
Color of emission:
Fuel
Observation began Ended
Comments:
Observer' s
Signature
Remarks :
\30C
nin^v.
0
1
2
3
4
5
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23"
24
25
26
27
28
29
0
15
•
30
45
^^sec
min\.
30
31
32
33
34
35
is
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
0
15
30
45
•Distance from observer to stack.
113
-------
RECORD OF VISUAL DETERMINATION OF OPACITY
PAGE of
COMPANY
LOCATION
TEST NUMBER,
DATE
TYPE FACILITY_
CONTROL DEVICE
HOURS OF OBSERVATION,
OBSERVER
OBSERVER CERTIFICATION DATE,
OBSERVER AFFILIATION
POINT OF EMISSIONS
HEIGHT OF DISCHARGE POINT
CLOCK TIME
OBSERVER LOCATION
Distance to Discharge
'Direction from Discharge
Height of Observation Point
BACKGROUND DESCRIPTION
WEATHER CONDITIONS
Hind Direction
Wind Speed
Ambient Temperature
SKY CONDITIONS (clear,
overcast, % clouds, etc.)
PLUME DESCRIPTION
Color
Distance Visible
OTHER
Initial
Final
R
T
t
SUMMARY OF AVERAGE OPACITY
Set
Number
Tlrnp
Start—End
Opacity
Sum
"verage
eadings ranged from to % opacHy
he source v/as/was hot In compliance with .at
he time evaluation v/as made.
Pd
M
X!
W
-------
APPENDIX C
SUGGESTED CONTENTS OF STACK TEST REPORTS
115
-------
CONTENTS OF STACK TEST REPORTS
In order to adequately assess the accuracy of any test report, the basic
information listed in the following suggested outline is necessary:
1. Introduction - Background information pertinent to the test is
presented in this section. This information shall include but
not be limited to the following:
a. Manufacturer's name and address.
b. Name and address of testing organization.
c. Names of persons present, dates and location of test.
d. Schematic drawings of the process being tested showing emission
points, sampling sites, and sta'ck cross section with the sampling
points labeled and dimensions indicated.
2. Summary - This section shall present a summary of test findings
pertinent to the evaluation of the process with respect to the
applicable emission standard. The information shall include, but not
be limited to the following:
a. A summary of emission rates found.
b. Isokinetic sampling rates achieved if applicable.
c. The operating level of the process while the tests were conducted.
3. Procedure - This section shall describe the procedures used and the
operation of the sampling train and process during the tests. The
information shall include, but not be limited to the following:
a. A schematic drawing of the sampling devices used with each com-
ponent designated and explained in a legend.
b. A brief description of the method used to operate the sampling
train and procedure used to recover samples.
116
-------
4. Analytical Technique - This section shall contain a brief description
of all analytical techniques used to determine the emissions from
the source.
5. Data and Calculations - This section shall include all data collected
and calculations. As a minimum, this section shall contain the following
information:
a. All field data collected.
b. A log of process and sampling train operations.
c. Laboratory data including blanks, tare weights, and results of
analysis.
d. All emission calculations.
6. Chain of Custody - A listing of the chain of custody of the emission
test samples.
7. Appendix; (Within this Stack Test Report)
a. Calibration work sheets'for sampling equipment.
b. Calibration or process logs of process parameters.
117
-------
APPENDIX-
GAS CONVERSION GRAPHS
118
-------
APPENDIX D
99.92
10,000
SULFUR CONVERSION, % feedstock sulfur
99.7 99.0 98.0
97.0 96.0 95.0 92.9
2 2.5 3
40 50 60708090100
4 5 6 7 8 9 10 IS 20 25 30
S02EMISSIONS, Ib/ton of 100% H2S04 produced
Sulfuric acid plant feedstock sulfur conversion versus volumetric and
mass S02, emissions at various inlet SC>2 concentrations by volume.
119
-------
APPENDIX D
10
i
Ill '
10 '"
SULFURIC ACID PLANT VOLUMETRIC
AND MASS EMISSIONS OF ACID MIST
AT VARIOUS INLET S0? CONCENTRATIONS
By VOLUME.
1 b 0.02 0.025 0.03 .. 0.04 5 C J 8 9 0.10
ACID MIST EMISSIONS, IB. HjSC>4 PER TON OF 100% H2SO4 PRODUCED
120
-------
APPENDIX E
WATER POLLUTION FACTORS
121
-------
Sulfuric Acid Plant Effluent Control
A sulfuric acid plant has no inherent water pollutants associated with the
actual production of acid. An indispensable part of the process, however,
is heat removal accomplished with steam generating equipment and cooling
towers. These cooling methods require blowdown and subsequent disposal to
natural drainage. The amount and degree of impurities discharged vary widely
with the raw water quality.
An inherent hazard of any liquid handling process is the occurrence of an
occasional accidental break and operator error. The sulfuric acid cooling
coils are most prone to any accidental break. On these occasions the cooling
tower water quickly becomes contaminated. In turn, the normally acceptable
practice is to take care of that break as soon as it is discovered and protect
the natural drainage waters.
Process Description
The facilities are relatively simple. These involve the installation of a
reliable pH or conductivity continuous monitoring unit on the plant effluent
stream (preferably, the combined plant effluent stream but at least on the
cooling tower blowdown). A second part of the system is a retaining area
through which noncontaminated effluent normally flows. This area can be any
reasonable size but should be capable of retaining a minimum of 24 hours of the
normal plant effluent stream. The discharge point from the retaining area requires
a means of positive cutoff, preferably a concrete abutment fitted with a
valve. A final part of the system is somewhat optional. For example, the
retaining area could be provided with lime treatment facilities for neutraliza-
tion. In addition, equipment for transferring this acid water from the retaining
area to a contaminated water holding or recirculating system could also be pro-
vided.
The procedure is that an acid break is detected by the water monitoring in-
strument, located at the inlet of the cooling tower, and causes an audible alarm
to be sounded. It is preferable to have the instrument automatically
activate the positive cutoff at the discharge of the retaining area although
122
-------
this can be done manually. Activation of this system necessitates a plant
shutdown to locate the failure and initiate repairs. The now contaminated
water in the retaining area must be neutralized in the pond or moved to a
contaminated water storage area where it can .be stored or neutralized through
a central treatment system.
Sketches of the suggested treatment facilities are attached. Such a
system provides continuous protection of natural drainage waters as well as
means to correct a process failure. The primary factor to control is pH.
Sufficient neutralization to raise the contaminated water pH to 6 is required.
Neutralization is preferably by use of lime. Lime serves not only to neutralize
the hydrogen ion concentration (low pH) but also removes sulfate (SO.) as an
insoluble calcium sulfate according to the following reaction:
H2SO, + CaO + H20 — > CaSO^ -2H2°
Sulfuric Acid Lime Water Calcium Sulfate
123
-------
SULFURICACID
PROCESS PLANT
TO EFFLUENT DISPOSAL
-k- (ALTERNATE)
v i_s.>*_! *•*•
TO GYPSUM POND
— CONTROLLED DISCHARGE RETENTION
POND
SITE VARIES WITH AREA AVAILABLE AND PLANT SIZE
MAY BE BLOCKED/DAMMED
TO PERMIT POND WATER PH
CONTROL IF REQUIRED
(SIZE MIGHT BE 300' x 30' x 6')
FROM 4th CONVERTER
MASS
CLARIFIED WATER
TO PUMP
TANK
TO ATMOSPHERE
FROM HT.
I EXCHANGER
I
I
| FROM HT.
CLARIFIED WATER | EXCHANGER
I
TO PUMP
TANK •<•
COOLING
TOWER
SLOWDOWN
NOTE-
CIRCLED ITEMS ADDED
F^REFFLUEfclT CONTROL
SULFURIC ACID EFFLUENT CONTROL
NOTE: THIS APPLIES TO BOTH
SINGLE AND DOUBLE
ABSORPTION PLANTS
-------
STREAM LEGEND
Ol
OFF GAS
MAIN LIQUID
— MAIN GAS
| MINOR
FEED STREAM
1300 ~ 1670 l/kkg
(310 ~ 400 GAL/TON;
1875 ~ 2080 l/kkg
(450 ~ 500 GAL/TON)
BLOW DOWN
SULFUR
FURNACE
75.000 ~ 83,500 l/kkg
(8.000 ~ 20,000 GAL/TON)
ED
R
:E
"2° r~
*
BOILER
r*| STEAM
"1 !
WASTE
HEAT
BOILER
1
1
~~T'~~*
CONVERSION
— *-
SLOWDOWN | . \_ J
5 ~ 10 GAL/TON) 21 ~ 40 l/kkg ~| \
r
I !
ACID
COOLING &
PUMPING
ABSORPTION
PROCESS WATER
(15 ~ 20 GAL/TON)
63 ~ 83 l/kkg
INTERSTAGE
ABSORPTION
PRODUCT
TON ~ SHORT TON
SULFURIC ACID PLANT - DOUBLE ABSORPTION
FLOW RATES PER TON 100% H2SO4
-------
F.egen Slowdown
Na£!
FEED STREAM
OFF GAS
TREATED H,O|
(310~ 400 GAL/TON)
1300 ~ 1670 l/kko
SULFUR
FURNACE
'ON)
— — *
i
rm-
1
1
1
- i
WASTE
HEAT
BOILER
STEAM
T
i
i
I
i
0 TO ATMOSPHERE
CONVERSION
ABSORPTION
(5-10 GAL/TON)
21-40 l/kkg
ACID
CIRC. TANK
[P
(15 ~ 20 GAL/TON)
63 ~ 83 l/kkg
STREAM LEGEND
- MAIN LIQUID
— — — MAIN GAS
- ___ >_\ MINOR
ACID
COOLING
COOLING H2O
ACID
COOLING
WDOWN 'r
118.QQQjr-gO.OOO GAL/TON)
75.000 ~ 83,000 l/kkg ~
1875 ~ 2080T/kkg
(450 ~ 500 GAL/TON)
PRODUCT
TON ~ SHORT TON
SULFURIC ACID PLANT (SINGLE ABSORPTION)
FLOW RATES PER TON 100% H2SO4
-------
APPENDIX F
SUMMARY OF TROUBLESHOOTING TECHNIQUES
127
-------
A. High Opacity Stack Gas Plume by Moisture
1. Moisture in SO- gas or air.
2. Moist air leakage into ductwork system — see next sections for
corrective action.
3. Poor acid distribution over absorption or drying towers.
4. Insufficient flow rate of H-SO,, 98% acid circulating into
towers.
5. Channeling due to dirty towers, absorption and drying.
6. Spray from drying tower.
7. Splashing at weirs.
8. Splash from leaking distributor tubes.
9. Leakage of internal acid piping.
10. Failure of plugging of entrainment separators.
11. Flooding ot packing ia the tower.
12. Sulfur impurities, oil, hydrocarbons, organic and excessive
moisture form water by combustion due to the hydrogen content.
B. Mist Formed In System Between Converter Outlet and Absorbing Tower -
Causing High Opacity Stack Gas Plume
13. Duct cooling below dewpoint - Refer to subsequent section
corrective action.
14. Poor drying tower operation
Entrained drying acid
Inadequate gas purification
Acidity of gas (SO-)
Organic matter in the sulfur
Above conditions cause acid mist formation.
15. Absorbing tower operating conditions.
16. Acid strength too high (99.0-100%) + (?SO.) or acid too low
(90-97.5% H2S04).
17. Air leak at base of stack.
18. Temperature of gas entering absorption tower too high.
19. Insufficient acid flow rate - gpm.
128
-------
20. Poor acid distribution.
21. Channeling due to dirty tower packing.
22. Tower packing settled, disarranged or disintegrated.
C. Sulfur Burning (Raw Gas) Units
23. Steam or water leaks. Sulfur line to burner. (Refer to subsequent
pages for corrective action.
24. Leaks in the boiler, superheater, or economizer tubes.
25. Oxides of nitrogen in gas due to excessive combustion temperatures.
26. Quality of the sulfur or raw material.
27. Hydrocarbons or organics in sulfur.
28. Acidity in sulfur.
129
-------
APPENDIX F
INSPECTION CHECKLIST FOR TROUBLESHOOTING MALFUNCTIONS, UPSETS AND POOR PROCESS OPERATOR CONTROL
All Types of Units, Including Equipment from Drying Tower to Exit Stack
SYMPTOM
A. Excess Moisture in S02 gas or air
CAUSE - Item Number
1. Poor drying
2. Moist air leakage
3. Poor acid distribution.
Dirty distributor or
tubes. Distribution
points too far apart
or acid not equally
distributed in the
area and not level.
METHOD OF DETERMINATION
(Verification Tests)
Make moisture tests of air or gas leaving the drying
tower. Opacity is high.
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.) Plume opacity is
highly visible.
Inspect visually with and without acid circulating.
Distributing points not more than 18-inch centers,
no more than 12 inches from the inside of shell
lining. Opacity reading is high.
REMEDY
Increase Acid Flow Rate.
Locate leak and weld hole
shut with patch of steel
plate.
Adjust distribution
level position.
UJ
o
Insufficient acid cir-
culating in the towers.
5.
Channeling due to
dirty tower.
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
temperature of the acid entering the tower. They should
be approximately the same. Check the increase in acid
temperature across tower. Opacity reading should be
high.
Determine pressure drop through the tower, including
and excluding the spray catcher. Inspect visually for
sulfate on the top of tower packing. Wash tower if
necessary.
Increase flow rate of
acid.
Clean out tower packing
and/or repack tower.
-------
SYMPTOM
CAUSE - Item Number
METHOD OF DETERMINATION
(Verification Tests)
Page 2
REMEDY
B. Spray from drying tower
6. Exit Stack Plume
greyish white.
7. Splashing at weirs if
the distributor is the
weir type.
8. Splash from leaking
distributor tubes.
9. Leakage of internal
acid piping.
10. Failure or plugging
of entrainment separ-
ators.
11. Flooding of packing
in the tower or
flooding of packing
at the acid distri-
butor due to improper
packing, high acid
or gas flow, or break-
down of packing.
Make stick test at exit duct. Two sticks at right angles Add new mist eliminator
to each other, and across the duct diameter, are necessary to top of tower.
at times if flow pattern of gas including mist is distorted.
Opacity reading is high.
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.
Examine visually for leaks in internal acid pipe while
acid is circulating at full normal rate.
Inspect. Measure pressure drop.
Flooding evidenced by high pressure differential. Visual
inspection of tower internals will show uneven dis-
tribution of packing or "washing" effect causing packing
to move and relocate in an uneven manner.
Adjust distributors
to no free drop.
Align piping.
Replace corroded
pipe.
Wash or repack spray
catcher if necessary.
Repack tower.
-------
SYMPTOM
CAUSE - Item Number
METHOD OF DETERMINATION
(Verification Test)
Page 3
REMEDY
C. Mist formed in system between converter
outlet and absorbing tower. High plume
opacity readings indicated.
12.
Cooling in SO^ cooler
or economizer is too
great, too fast, or
localized. Inadequate
heat exchanger
capacity.
Appearance of drip acid in the economizer or a larger-
than-nonnal amount of drip acid drained from the S03
cooler shell. This condition may be aggravated by an
abnormally high mist content in the 303 gas. Opacity
reading is high.
Improve control by
operator and temperature
control adjustments.
13. Duct cooling.
14. When large amounts of
moisture are in the
SO, gas leaving the
converter, as from
poor drying, entrained
Note if the poor appearance of the stack varies More insulation is
with atmospheric conditions. If appearance is worse required or better
during rainstorms, or during sudden changes in temperature shielding provided.
and wind velocity, top shielding from rain or side shield-
ing from wind may be required.
Can be detected quantitatively by mist tests of the gas
entering and leaving the absorbing 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
Trace out entire plant
for various equipment
malfunctions and correct
offender.
drying acid, inadequate determining whether the escape of fumes from the absorbing
gas purification,
acidity or organic
matter in the sulfur,
etc., it is impossible
to prevent acid mist
formation. Much of
the mist so formed
cannot be removed in
the absorbing tower
and escapes as visible
mist from the exit stack.
tower stack is due to unabsorbed SO^ or sulfuric acid mist.
The presence of mist in the gas will cause a cloudy appear-
ance inside the tower. If the gas is clear inside the
tower and the stack if fuming, the poor appearance of the
stack is due to poor SO, absorption and not to mist in the gas.
-------
SYMPTOM
D. Absorbing tower operating conditions.
CAUSE - Item Number
15.
Temperature of acid
in the tower may be
too high or too low.
METHOD OF DETERMINATION
(Verification Tests)
Low acid temperature has more affect on stack than high
temperature. Usually the minimum is 50°C (122°F) and
and the maximum is 90°C (194°F) for acid entering.
16.
17.
Acid strength too high
or too low.
Air leak at base of
stack.
Determine optimum strength by actual operation, adjusting
slowly within the range of 98.5 percent to 99.4 percent.
Approximately 99.2 percent is good practice.
Visual inspection
Page 4
REMEDY
The optimum temperature
must be found by operat-
ing experience. Lower
temperatures are gen-
erally permitted with
better quality gas that
contains less I^SO/j mist
or vapor. If stack appear-
ance is poor due to mist
or moisture condition, it
can usually be improved
by increasing the temper-
ture of the acid going to
the tower to 90°C to
110°C. This is done only
as a temporary measure to
confirm that a mist or
moisture condition exits.
Same as above.
Weld leaks tight.
-------
Page 5
SYMPTOM
CAUSE - Item Number
18. Temperature of gas
entering tower.
METHOD OF DETERMINATION
(Verification Tests)
In plants that do not produce oleum, temperatures,
of 150° to 160°C entering the absorber are low
enough.
REMEDY
Temperatures could be
considerably higher
with good stack appear-
ance, but with higher
gas inlet temperature
the absorbing acid
temperature must be
higher also and cor-
rosion will be greater.
19. Insufficient Acid
Flow Rate
Check pump motor amperage check tower drain sight glass
for flow.
20. Poor Acid Distribution Same as Items 3 and 4 above in Verification Tests column.
21. Channeling due to
dirty tower.
Determine pressure drop through the tower, both including
and excluding the spray catcher. Inspect visually for
sulfate on the top of tower packing.
Increase flow rate by
proper valving or
repair pump.
Same as Item 3 and 4 in
above Remedy column.
Wash tower if necessary.
Check Remedy, Item 5.
U>
-P-
22. Tower packing settled When all other points have been checked and found satis-
or disarranged. factory, this item might be the. cause.
Packing under the distri-
butor tubes may have to
be removed and rearranged
-------
Page 6
SYMPTOM
CAUSE - Item Number
METHOD OF DETERMINATION
(Verification Tests)
E.
Sulfur Burning (Raw Gas) Units,
Steam or Water Leaks.
23.
Sulfur line to burner. 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.
24.
Leaks in the boiler,
superheater, or
economizer tube.
Symptoms are a considerable increase in the condensed acid
drip in SO, -cooler and in the economizer or decrease in
the amount of water required for dilution. Apply hydro-
static tests on boiler system equipment when leaks are
suspected and cannot be detected. Comparative Tyndall
beam tests can be made on gas entering and leaving
equipment suspected of leaks.
UJ
Ln
REMEDY
Repair or replace leaky
piping.
Weld leaky tubes or plug.
When boiler leaks are sus-
pected, shut down and
examine by inspection
for water dropping from
boilers into the compart-
ments 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.
-------
Page 7
SYMPTOM
F. Oxides of nitrogen in gas.
CAUSE - Item Number
25. 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 converter
and the absorbing tower.
G. Quality of the sulfur or raw material
METHOD OF DETERMINATION
(Verification Tests)
Examine condensed drip in economizer or SO,
26. Nitrogen compounds.
cooler
for niter. When drip Is diluted with water, brown fumes
will be noted if a considerable amount of niter is present,
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).
27. Hydrocarbon or organ- Good sulfur filtering sometimes helps by partially
ics in sulfur. reducing organics.
28. Acidity in sulfur.
Neutralize acidity with lime, but only when sulfur is
subsequently filtered.
REMEDY
Niter in the burner gas
may be prevented by re-
ducing the burner teraper-
perature, lowering SO
gas strength, or lessen-
ing preheating of the air.
This condition may be due
to high localized temper-
atures that are not
recorded or evident; it
might be corrected by
improving the sulfur
spray distribution and
burning pattern.
Use highest purity sulfur
economically possible.
Use lower sulfur flame
temperature.
Use sulfuric acid in
sulfur pit to coagulate
hydrocarbons, then
neutralize with lime
and filter.
Use highest purity
sulfur economically
possible or use liming
and filtration of
molten sulfur.
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
2.
3. RECIPIENT'S ACCESSION-NO.
EPA 340/1-77-008
4. TITLE AND SUBTITLE
Inspection Manual for the Enforcement of New
Source Performance Standards as Applied to
Contact Catalyst Sulfuric Acid Plants
5. REPORT DATE
November 1976
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
E.L. Calvin and F.D. Kodras
8. PERFORMING ORGANIZATION REPORT NO.
Project No. 42469,Task 9
9. PERFORMING ORG "VNIZATION NAME AND ADDRESS
Catalytic, Inc.
Post Office Box 15232
Charlotte, N.C. 28210
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-02-1322
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Technical Support Branch
Division of Stationary Source Enforcement
Washington, D.C. 20460
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
EPA Project Officer: Donald F. Carey
16. ABSTRACT
Standards of performance for new sulfuric acid plants were promulgated
under Section 111 of the Clean Air Act on December 16, 1971; the
standards have been subjected to several amendments since that time.
This report presents procedures for inspection of Contact Catalyst
Sulfuric Acid Plants toward determination of their compliance with
NSPS. It also includes background information that will aid the in-
spector in understanding the manufacture of sulfuric acid using the
Contact Catalyst process. The report provides a list and description
of the critical process controls related to major operating parameters
of the process.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
COSATI Field/Group
Air Pollution Control
Sulfuric Acid Plants
Verification Inspection
Performance Tests
New Source Perfor-
mance Standards
Enforcement
Emission Testing
13 B
14 D
8. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
147
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
*U.S. GOVERNMENT PRINTING OFFICE 1977 0-720-335/6011
------- |