EPA-450/3-85-004
Review of New Source Performance
Standards for Ammonium Suifate
Manufacture
Emission Standards and Engineering Division
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, NC 27711
February 1985
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This report has been reviewed by the emission Standards and Engineering Division of the Office
of Air Quality Planning and Standards, EPA, and approved for publication. Mention of trade
names or commercial products is not intended to constitute endorsement or recommendation
for use. Copies of this report are available through the Library Services Office (MD-35), U.S.
Environmental Protection Agency, Research Triangle Park, N.C. 27711, or from National
Technical Information Services, 5235 Port Royal Road, Springfield, Virginia 22161.
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TABLE OF CONTENTS
LIST OF FIGURES
LIST OF TABLES
1. Executive Summary 1-1
1.1 Regulatory History of Current Standard 1-1
1.2 Best Demonstrated Control Technology 1-2
1.3 Enforcement of NSPS 1-2
1.4 Industry Growth Trends 1-3
1.5 Economic Considerations Affecting the NSPS 1-3
2. Industry Description 2-1
2.1 Introduction 2-1
2.2 Background Information 2-4
2.3 Ammonium Sulfate Production 2-5
2.3.1 Caprol actam By-Product Ammonium Sulfate 2-5
2.3.2 Synthetic Ammonium Sulfate 2-9
2.3.3 Coke Oven By-Product Ammonium Sulfate 2-12
2.4 References 2-17
3. Current Standards for Ammonium Sulfate Plants 3-1
3.1 Affected Facilities 3-1
3.2 Controlled Pollutants and Emission Levels 3-1
3.3 Monitoring Requirements 3-1
3.4 Testing Requirements 3-2
4. Status of Control Technology 4-1
4.1 Emission Sources 4-1
4.2 Emission Control Equipment in Ammonium Sulfate 4-3
Industry
4.2.1 Venturi Scrubbers 4-6
4.2.2 Centrifugal Scrubbers 4-6
4.2.3 Other Wet Scrubbers in the AS Industry 4-7
4.2.4 Fabric Filtration in the AS Industry 4-7
4.3 Plant Testing 4-8
4.4 References 4-1°
5. Compliance Test Results 5-1
5.1 References 5-3
i n
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TABLE OF CONTENTS
6. Cost Analysis 6-1
6.1 Capital Costs 6-1
6.2 Annualized Costs 6-5
6.3 Cost Effectiveness 6-10
6.4 References 6-13
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LIST OF FIGURES
Figure No. Page
2-1 Caprolactam By-Product Ammonium Sulfate 2-6
Process Flow Diagram
2-2 Synthetic Ammonium Sulfate Process 2-10
Flow Diagram
2-3 Process Flow Diagram for Coke Oven By-Product
Ammonium Sulfate Showing Alternate Drying 2-14
Processes
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LIST OF TABLES
Table No. Page
2-1 U.S. Production and Consumption of 2-2
Ammonium Sulfate
2-2 Typical Parameters for a Caprolactam 2-8
By-Product Ammonium Sulfate Dryer
2-3 Typical Parameters for a Synthetic 2-11
Ammonium Sulfate Dryer
2-4 Estimated Parameters for a Coke Oven 2-16
By-Product Ammonium Sulfate Dryer
4-1 Summary of Uncontrolled Emission Data from 4-2
EPA Emission Tests on AS Dryers
4-2 Ammonium Sulfate Industry-Supplied Wet 4-4, 4-5
Scrubber Performance Data
4-3 AS Particulate Control Systems Tested by EPA 4-9
4-4 Results of EPA Emission Testing 4-10
5-1 Industry-Supplied Emission Test Data - . 5-2
6-1 Capital Cost Summary for a Venturi Scrubbing 6-2
System (Caprolactam By-Product Plant with
22.7 Mg/hr Capacity)
6-2 Capital Cost Summary for a Venturi Scrubbing 6-3
System (Synthetic Plant with 13.6 Mg/hr
Capacity)
6-3 Capital Cost Summary for a Venturi Scrubbing 6-4
System (Coke Oven By-Product Plant with
2.7 Mg/hr Capacity)
6-4 Venturi Scrubber Operating Parameters 6-6
6-5 Annualized Cost Summary for a Venturi 6-7
Scrubbing System (Caprolactam By-Product
Plant with 22.7 Mg/hr Capacity)
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LIST OF TABLES
Table No.
6-6 Annualized Cost Summary for a Venturi Scrubbing 6-8
System (Synthetic Plant with 13.6 Mg/hr
Capacity)
6-7 Annual!zed Cost Summary for a Venturi 6-9
Scrubbing System (Coke Oven By-Product
Plant with 2.7 Mg/hr Capacity)
6-8 Average U.S. Retail Price for Ammonium Sulfate 6-11
6-9 Cost Effectiveness of AS Particulate Recovery 6-12
Using Venturi Scrubbers (March 1984 dollars)
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1. EXECUTIVE SUMMARY
1.1 Regulatory History of Current Standard
The new source performance standards (NSPS) for ammonium sulfate (AS)
particul ate matter were proposed on February 4, 1980, and promulgated by
the Environmental Protection Agency (EPA) on November 12, 1980 (40 CFR 60,
Chapter 1, Subpart PP). The standards apply to ammonium sulfate dryers that
were constructed, reconstructed, or modified on or after February 4, 1980,
and produce ammonium sulfate as a caprolactam by-product, as a coke oven
by-product, or by synthetic manufacture (direct combination of ammonia and
sulfuric acid). The standards state that exhaust gases discharged to the
atmosphere from ammonium sulfate dryers must not contain AS particulate
matter in excess of 0.15 kg per megagram of ammonium sulfate produced (0.30
pound of particulate per ton of ammonium sulfate produced). The standards
also limit visible emissions from stacks to 15 percent opacity.
There are requirements in the NSPS for continuous monitoring of mass
flow rates to crystal!izers and for the continuous monitoring of pressure
drops across particulate control equipment. The flow monitoring device
must have an accuracy of +_ 5 percent. However, if a facility uses weigh
scales of the same accuracy to directly measure production rates of AS, the
use of flow monitoring devices is not required. The NSPS requires that
affected facilities install, calibrate, maintain, and operate pressure drop
monitors across emission control devices, and that these devices be accurate
to +_ 5 percent. Records from AS feedstream flow monitoring and pressure
drop monitoring are required under the NSPS to be retained for 2 years from
the date the measurements are made by the operator.
1-1
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The objective of this report is to review the ammonium sulfate NSPS
and to assess the need for revision on the basis of developments that have
occurred since the NSPS was promulgated in 1980.
1.2 Best Demonstrated Control Technology (BDCT)
The NSPS is based on the use of medium energy venturi scrubbers as
an add-on measure to control particulate emissions from AS dryers. No
significant changes in control technology for AS dryers have occurred since
promulgation of the NSPS. Because ammonium sulfate has a moderately high
water solubility, wet scrubbing is employed throughout the industry. Wet
scrubbing allows easy recycle of collected particulates back into process
streams, avoiding alternative waste disposal problems. In the caprolactam
by-product AS industry there are small amounts of caprolactam carried
through the AS manufacturing process. Dryer emissions of caprolactam, a
volatile organic compound (VOC), are also controlled effectively by wet
scrubbing.
There is only one dry emission control process that has operated at an
AS facility. This is a baghouse which was used at a synthetic AS plant. A
telephone survey of the synthetic AS industry indicates that this plant has
been mothballed since 1979.
1.3 Enforcement of NSPS
Since proposal and promulgation of the NSPS, there have been no new,
modified, or reconstructed facilities which have come under the standards.
However, emission data gathered from the industry since promulgation of
the NSPS indicate that emission levels set by the NSPS are being achieved
at existing plants. There is an incentive for AS producers to meet the
NSPS because captured emissions may be recovered, reprocessed, and sold as
1-2
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product. There are no in-stack opacity monitors in most AS participate
control applications due to the use of wet scrubbing . Water droplets and
steam in the stack make the exhaust gases difficult to monitor by available
equipment. Therefore, no continuous opacity data are available for AS dryers.
1.4 Industry Growth Trends
Since proposal and promulgation of the NSPS there has been a decline
in the total production capacity of ammonium sulfate plants. Several
plants producing synthetic AS and coke oven by-product AS have closed
operations. Caprolactam by-product AS has experienced a small capacity
increase, but the potential for further AS growth in the near future is
limited by the demand for caprol actam, which is used to manufacture nylon-6
fibers. Consumption of ammonium sulfate has also experienced a decline in
the last 4 years due to an increased use of alternative nitrogenous fertilizers.
There are no indications that these production and consumption patterns
will-be altered in the next few years.
1.5 Economic Considerations Affecting the NSPS
A review of venturi scrubber costs in the AS industry was performed
to determine the cost effectiveness of achieving the NSPS for each of the
three regulated AS processes. The cost effectiveness of venturi scrubbers
ranges from a cost savings of $36 per megagram of particulate captured for a
545 Mg/day caprolactam plant to a cost of $655 per megagram for a 65 Mg/day
coke oven by-product plant. There is a cost savings of $21 per Mg for a
326 Mg/day synthetic AS plant. Cost savings are generated by recovery
credits for AS particulates that are captured by scrubbers and recycled
back to process streams. Recovery credits are dependent on dryer emission
rates, scrubber collection efficiencies, and AS market prices.
1-3
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2. INDUSTRY DESCRIPTION
2.1 Introduction
On February 4, 1980, the EPA proposed new source performance standards
for ammonium sulfate dryers. The standards established parti cul ate emission
limits for ammonium sulfate dryers in three categories of ammonium sulfate
production. Affected facilities include dryers in synthetic process plants,
caprolactam by-product plants, and coke oven by-product plants that were
constructed, reconstructed, or modified on or after February 4, 1980.
The proposed standards were promulgated on November 12, 1980. Ammonium
sulfate is produced as a by-product of several other processes, such as
nickel reduction, sulfuric acid tail gas scrubbing, and sewage sludge
processing, none of which are subject to the NSPS.
At the time of the NSPS development, there were approximately 50 plants
employing one of the three regulated processes for production of ammonium
sulfate. Production capacity has declined between 1977 and 1983 from 3,143
x 103 Mg/yr to 2,869 x 103 Mg/yr with several plant closings in the industry.1
U. S. consumption of ammonium sulfate has dropped from 955 x 103 Mg in 1977
to 624 x 103 Mg in 1983.2 Production and consumption trends are presented in
Table 2-1.
There are three plants currently producing AS as a by-product of
caprolactam, and these three plants produce over 50 percent of the total
AS in the United States. Caprolactam is used in the manufacture of nylon-6
fibers. One caprolactam plant expanded AS production in 1980-81 from
860 x 103 to 910 x 103 Mg/yr, but the modification was exempt from the NSPS
2-1
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TABLE 2-1. U.S. PRODUCTION AND CONSUMPTION OF AMMONIUM SULFATE
(103 Metric tons)
Year
1983
1982
1981
1980
1979
1978
1977
1976
1975
1970
Production
Capacity
2869*
2869
2911
2866
2948
3099
3143
3382
3416
3530
Production Rate
(% Capacity)
N.A.
N.A.
90.2
81.2
87.1
80.7
79.3
67.8
76.2
64.1
Actual
Production
N.A.
N.A.
2626
2327
2568
2501
2492
2293
2603
2263
Consumption
624
650
769
791
707
768
955
956
742
700
* Projected
N.A. - Not Available
Sources:
"World Fertilizer Capacity," 3/26/84, TVA National Fertilizer Development
Center, Muscle Shoals, Alabama.
Fertilizer Trends 1982, TVA National Fertilizer Development Center.
"Commercial Fertilizers - Consumption for Year Ended June 30, 1984,"
USDA Crop Reporting Board.
Fertilizer Reference Manual, June 1982, The Fertilizer Institute.
2-2
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based on the date for commencement of construction.3 A survey of the
industry indicates no anticipated expansion or new construction of capro-
1 actam by-product AS plants in the near future.4'6'6
There has been a decline in production in both the synthetic
manufacture of ammonium sulfate and coke oven by-product AS since 1978,
with plant closings in both segments of the industry. A telephone survey
of synthetic AS producers confirms that most are operating well below
design production capacities.
Ammonium sulfate's share of the fertilizer market has increasingly
been displaced by other sources of higher analysis nitrogen fertilizers,
such as anhydrous ammonia and urea. Ammonium sulfate is 20.9 percent
nitrogen compared to 82 percent for anhydrous ammonia and 44.5 percent for
urea. Ammonium sulfate will continue to be a leading source of plant
nutrient sulfur in the U.S. fertilizer market, but there has been a notable
increase in the use of other sulfur carriers, such as ammonium thiosulfate,
rather than expanding supplies of AS.7 Based on current capacity utilization,
announced expansions, and consumption patterns, the likelihood of any
significant growth of ammonium sulfate fertilizer manufacture in the next
few years is nil .4
The Fertilizer Institute (TFI) reports an average operating rate for
AS producers in 1983 at 71 percent of their total capacity, with the middle
50 percent of the plants falling between 39 and 72 percent.7 This indicates
that ample capacity is available in the U.S. to meet any future increased
demands which may occur. There have been no plant modifications or recon-
structions in the AS manufacturing industry which are subject to the NSPS.
2-3
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The Clean Air Act Amendments of 1977 require that the EPA review the
NSPS at least every 4 years to assess the need for possible revision
of standards [Section lll(b)(l)(B)]. This report presents the results of
the first review of the NSPS for ammonium sulfate. The review was conducted
by examination of current ammonium sulfate literature, contacts with EPA
Regional and State offices, contacts with producing plants, and contacts
with fertilizer trade associations.
2.2 Background Information
The primary use of ammonium sulfate (>95%) is as an agricultural
fertilizer. More than 50 percent of ammonium sulfate is generated as a
by-product of caprolactam, which is used in the manufacture of nylon-6
fibers. Because a great percentage of AS is generated as a by-product of
another process, production is not based solely on the demand for fertilizer,
but more on the demand for primary products.
The ammonium sulfate dryer is the main source of particul ate emissions
in the production process. There are other sources of fugitive emissions
such as crystallization, dewatering, screening, and materials handling,
but they are not, in the opinion of EPA, significant emission sources.^
Two types of dryers used in AS production are rotary dryers and fluidized
bed dryers. Rotary dryers may be direct fired or steam heated, and
fluidized bed dryers in the industry are all steam heated. Gas flow
rates, heat transfer rates, and mass transfer rates are the important
parameters for drying AS. These parameters may vary widely with different
dryers in the industry.
2-4
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2.3 Ammonium Sulfate Production
The three ammonium sulfate production processes covered by the NSPS
are caprolactam by-product, coke oven by-product, and synthetic manufacture.
The basic difference in the three production processes is the method of
producing the AS crystals from the various feedstocks. From the step of
crystallization onward, the three processes are quite similar. The slurry
of crystals is dewatered by centrifugation, dried and screened (except in
coke oven by-product processes where screening appears to be nonexistent),
and the dryer exhaust gases are vented to the emission control equipment.
The dried AS crystals are conveyed to storage, and fines separated by
screening are recycled back to the crystallizer.
2.3.1 Caprolactam By-Product Ammonium Sulfate - A typical process flow
diagram for caprolactam by-product ammonium sulfate is shown in Figure 2-1.
It is based on information obtained from plant visits to the three capro-
lactam production plants and responses to EPA inquiries.9 The material flow
rates in Figure 2-1 are based on a typical AS production rate of 22.7 Mg/hr
(25 ton/hr).
The ammonium sulfate crystals are produced by continuously heating
and circulating a 40 percent AS mother liquor through a draft tube-baffle
crystallizer at temperatures of 77° to 82°C (170° to 180°F) and at a
pressure of about 660 mm Hg (12.8 psia). Water vapor is released from
the crystallizer and condenses in one or more heat exchangers. The AS
slurry, known as "magma" flows out of the crystallizer to the settling
tank, where clear liquid is decanted as the AS crystals settle to the
bottom of the tank.
2-5
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en
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Figure 2-1. CAPROLACTAM BY-PRODUCT AMMONIUM SULFATE
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The slurry of ammonium sulfate crystals and mother liquor moves next
to the centrifuge system, where a bulk separation is performed. Typical
crystal throughput for a two centrifuge system varies from 8-11 Mg/hr
(9-12 ton/hr) per centrifuge. A spare centrifuge is generally provided
on stand-by in the event that lines become plugged with solid AS.
From the centrifuges, the AS crystals enter the dryer, which is the
principal source of AS particulate emissions. Both rotary drum and fluidized
bed dryers are used in the caprolactam industry. Typical operating parameters
for a caprolactam by-product AS dryer are presented in Table 2-2.
Caprolactam, (CH2)5 CONH, is carried through the AS process stream in
small quantities. Caprolactam has a melting point of 60°C (140°F) and a
boiling point of 140°C (284°F), so any caprolactam present in the AS dryer
at the operating temperatures involved, about 85°C (185°F), is in the liquid
phase. This residual hydrocarbon coats the AS crystals and serves as an
anti-caking agent in storage, circumventing the need for addition of other
substances to prevent caking of the AS product. The majority of capro-
lactam is removed from the system in this manner.
From the dryer, ammonium sulfate crystals are conveyed to a screening
area for separation and storage. The screening operation is typically
carried out within a building, and a screen enclosure may be used to prevent
fugitive emissions. The exhaust gases from the dryer are passed through a
particulate collection device, usually a wet scrubber. Some screening
operations are also equipped with wet scrubbers. Liquid waste streams from
the collection device are recycled back into process streams, eliminating
water pollution concerns and increasing production efficiencies.
2-7
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TABLE 2-2. TYPICAL PARAMETERS FOR A CAPROLACTAM BY-PRODUCT
AMMONIUM SULFATE DRYER
Parameter
Type/Value
Dryer
Product flow through dryer, Mg/hr (tons/hr)
Air flow through dryer, scm/min (scfm)
acm/min (acfm) (385°C (184°F)
Air flow per ton of product, scm/Mg (scf/ton)
Ai r temperature
Inlet to dryer, °C (°F)
Outlet of dryer, °C (°F)
(Inlet to scrubber)
Uncontrolled particulate emissions from dryer
kg/Mg of product (Ib/ton)
Rotary dryer
FB dryer
AS product temperature and water content, wt. percent
Dryer inlet 66°C (150°F)
•
Dryer outlet 80°C (175°F)
Water evaporated per ton of product, kg/Mg (Ib/ton)
Steam input to dryer kg cal/hr (Btu/hr)
Sat 125 psig at 177°C (350°F)
Rotary or
fluidized bed
23 (25)
825 (29,200)
1000 (35,500)
2152 (70,000)
149 (300)
85 (185)
26 (52)
111 (221)
2.0 - 2.5
0.1 - 0.5
24 - 25 (48 - 50)
3,024,000
(12,000,000)
2-8
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2.3.2 Synthetic Ammonium Sulfate - Synthetic AS is produced by
neutralizing concentrated sulfuric acid with pure ammonia in a crystal! izer/
reactor as indicated by the following chemical equation:
2NH3 (gas) + H2S04 (liquid) — > (NH^SO^solid) + Heat
Ammonia Sulfuric acid Ammonium sulfate
This reaction is highly exothermic, liberating approximately
67,710 cal/g mole (120,000 Btu/lb mole) of product. Heat removal is
achieved by a cooling section or external heat exchanger. The AS mother
liquor stream is injected at the point of the ammonia-sulfuric acid
reaction to improve the cooling. A typical plant configuration for the
synthetic manufacture of AS is shown in Figure 2-2. Material flow rates
in Figure 2-2 are based on a typical dryer production rate of 13.7 Mg/hr
(15 tons/hr).
The crystallizer may have an "elutriation leg" at the magma discharge.
Mother liquor flowing in this leg blows back or "elutriates" the fine AS
particles into the main chamber, but allows the larger particles to pass
to the discharge point, producing a more uniform crystal size distribution.
The AS crystal slurry leaves the crystallizer and is pumped to one
or more centrifuges, which remove most of the mother liquor and recirculate
it back to the crystallizer. Upon leaving the centrifuges the AS crystals
have a 1-2 percent moisture content.
The AS crystals are then fed to the dryer, the only significant
emission source in the process. Only rotary dryers are known to be used
in synthetic AS production plants. Operating parameters for the 13.7 Mg/hr
(15 ton/hr) dryer in Figure 2-2 are shown in Table 2-3.
2-9
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Figure 2-2. SYNTHETIC AMMONIUM SULFATE PROCESS
FLOW DIAGRAM
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TABLE 2-3. TYPICAL PARAMETERS FOR A SYNTHETIC
AMMONIUM SULFATE DRYER
Parameter
Type/Value
Dryer
Product flow through dryer, Mg/hr (ton/hr)
Air flow through dryer, scm/min (scfm)
acm/min (acfm) @ 93°C (200°F)
Air flow per ton of product, scm/Mg (scf/ton)
Ai r temperature
Inlet to dryer, °C (°F)
Outlet to dryer, °C (°F)
AS uncontrolled emission from the dryer,
kg/Mg (Ib/ton) of product
Product temperature and water content percent
Dryer inlet - 88°C (190°F)
Dryer outlet - 93°C (200°F)
Water evaporated, kg/Mg (Ib/ton)
Rotary, direct
f i red
13.7 (15.0)
135 (4750)
170 (5920)
591 (19,000)
232 (450)
93 (200)
26 (52)
2.0 - 2.5
0.1 - 0.5
24 - 25 (48 - 50)
2-11
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Screening of the AS divides a coarse and a standard product. As in
caprolactam by-product manufacture, screening takes place inside a storage
building, and fugitive dust is minimal. Synthetic plants may add a small
quantity of heavy hydrocarbon to the product to prevent caking.
2.3.3 Coke Oven By-Product AS - In the carbonization of coal into coke,
many volatile substances are liberated. At a temperature of 1000°C
(1832°F), which is common in steelmaking, the liberation of ammonia in
the off-gases is optimized. Formation of ammonium sulfate is traditionally
the most common method for the recovery of the ammonia off-gases from
the coking process. This is accomplished by one of three different
methods, which are classified according to the means of contacting the
ammonia with sulfuric acid. These are the direct, indirect, and semidirect
processes. Most of the ammonia produced in coke plants is recovered as
ammonium sulfate by the semidirect process. The balance is produced
in the form of concentrated ammonia liquors by the indirect process.
The direct process also recovers ammonia directly as AS, but this
process is not used in the U.S.^
In the semidirect process the off-gases are cooled and washed to
remove tar and yield an aqueous condensate high in ammonia content.
The ammonia is released from the condensate in a still. It is then
combined with the main gas stream, reheated to approximately 21°C
(70°F), and scrubbed with a dilute (5 to 6 percent) sulfuric acid solution.
Ammonium sulfate crystals of high purity are formed and removed as product.
2-12
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The indirect process recovers ammonia from the coking off-gases as a
dilute ammonia liquor, from which ammonia is stripped and converted
to a concentrated liquor. The dilute liquor is treated with steam in a
stripping column to release free ammonia present in salts such as ammonium
carbonate and ammonium sulfide. The liquor is then treated with lime to
decompose fixed salts such as ammonium chloride, after which it passes to
a second stripping column where the remaining ammonia is released. This
ammonia is recovered in a more concentrated liquor and can be converted
directly to a solid in a crystallizer.
In the direct process the off-gases are first cooled for maximum
removal of tar, and are then passed through the crystal!izer/saturator
where they are washed with sulfun'c acid. The AS crystals that form in
the liquor are recirculated until the desired crystal size is attained.
There are problems associated with the direct process, such as deposition
of tar in the saturator and decomposition of ammonium chloride carried by
the gas to form hydrochloric acid, creating corrosion problems.
Figure 2-3 shows a schematic of the coke oven by-product ammonium
sulfate process. The reaction between ammonia and sulfun'c acid is exo-
thermic, and a large portion of the generated heat is used in evaporating
water from the sulfuric acid bath. Approximately 1 kg of 77.8 percent
F^SO^ is consumed per kg of AS produced. The AS crystals precipitate and
are pumped in a slurry to the centrifuges for removal of liquids. The
crystals are then conveyed to a dryer, where the moisture content is
2-13
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ro
i
Hulk
Slorngp
Cyclone 1
Pneumatic >v /
Conveyor \>/
Heater H A*r \ nulk
Storage
Figure 2-3. PROCESS FLOW DIAGRAM FOR COKE OVEN AMMONIUM SULFATE
PLANTS SHOWING ALTERNATE DRYING PROCESSES
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reduced to about 0.15 percent and sent to storage. In coke oven by-product
AS a small amount of gypsum may be added to prevent caking. Gypsum
preferentially combines with moisture from the atmosphere.
Dewatering equipment varies in each plant, and may include vacuum
filters, centrifuges, and dryers in more than one combination. Mother
liquor from the dewatering and drying processes is recycled back
into the process stream. Table 2-4 lists operating parameters for a
typical coke oven AS dryer.
Two U.S. facilities have adopted Nippon Steel's TAKAHAX process for
coke oven gas desulfurization (COGD), of which AS is a by-product. The
process changes were exempt from the NSPS based on the date for commence-
ment of construction. Only one of the two plants is currently in operation,
A slip stream from this process, rich in sulfur salts, constitutes the AS
feed stream. Variations in the process may use sodium carbonate or
caustic soda as the alkali in place of ammonia. In either case, the end
product is sulfuric acid or elemental sulfur, respectively, instead of
AS. The facility currently in operation produces AS as the end product.
2-15
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TABLE 2-4. ESTIMATED PARAMETERS FOR A COKE OVEN BY-PRODUCT
AMMONIUM SULFATE DRYER
Parameter
Type/Value
Dryer
Product flow through dryer, Mg/hr (ton/hr)
Air flow through dryer, scm/min (scfm)
Air mass flow assumed per ton product
scm/Mg (scf/ton)
Ai r temperature
Inlet to dryer, °C (°F)
Outlet to dryer, °C (°F)
AS uncontrolled emission from the dryer,
kg/Mg of product (Ib/ton)
Product temperature and water content percent
Dryer inlet - 49°C (120°F)
Dryer outlet - 66°C (150°F)
Water evaporated, kg/Mg (Ib/ton)
Steam heat input to dryer, kg cal/hr (Btu/hr)
Rotary vac. filter-
dryer, centrifuge-
dryer or rotary dryer
2.7 (3.0)
99 (3,500)
2203 (70,000)
149 (300)
80 (175)
10.0 (20.0)a
2.5
0.5
20 (40)
163,800 (650,000)
a Estimated based on 1 percent of AS product appearing as uncontrolled
dryer emissions.
2-16
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2.4 References
1. Fertilizer Reference Manual, June 1982. Published by the Fertilizer
Institute.
2. Commercial Fertilizers - Consumption for Year ended June 30, 1983,
USDA Crop Reporting Board.
3. Information provided in a letter from F. L. Piguet, Allied Fibers
and Plastics, to Jack Farmer, U.S. Environmental Protection Agency,
Research Triangle Park, N.C., dated August 2, 1984.
4. Information provided in a letter from Karl T. Johnson, The Fertilizer
Institute, to Peter Schindler, U.S. EPA, dated June 8, 1984.
5. Information provided in telephone conversation by Max Beal, Nipro, Inc.,
to Peter Schindler, U.S. EPA, on June 18, 1984.
6. Information provided in telephone conversation by E. Harre, TVA
National Fertilizer Development Center, to Peter Schindler, U.S.
EPA, on May 30, 1984.
7. Information provided in a letter from Edwin A. Harre, TVA National
Fertilizer Development Center, to Naum Georgieff, U.S. Environmental
Protection Agency, Research Triangle Park, N.C., dated June 7, 1984.
8. Ammonium Sulfate Manufacture - Background Information for Proposed
Emission Standards, EPA-450/3-79-034a, p. 9-3.
9. Reports of plant trips to: The Allied Chemical Company, Hopewell , Va;
NIPRO Inc., Augusta, GA; Dow Badische Company, Freeport, TX; regarding
ammonium sulfate plant emission standards development. Docket No. A-79-31,
10. Coal, Coke, & Coal Chemicals, p. 290, copy provided with letter from
John Stavik, Dravo/Still, to Naum Georgieff, U.S. EPA, dated July 11, 1984,
11. Reference 10, p. 297.
12. Information provided in letter and enclosures from R. F. Wyse, U.S.
Steel, to Peter Schindler, U.S. Environmental Protection Agency,
dated July 27, 1984.
2-17
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3. CURRENT STANDARDS FOR AMMONIUM SULFATE PLANTS
3.1 Affected Facilities
The NSPS regulates newly constructed, reconstructed, and modified
ammonium sulfate plants that produce AS as a caprolactam by-product, as
a coke oven by-product, or by the synthetic process (direct combination
of ammonia and sulfuric acid.) Each ammonium sulfate dryer is the
affected facility.
An existing ammonium sulfate plant may be subject to the NSPS if:
(1) it is modified by a physical or operational change in an existing
facility thereby causing an increase in the emission rate to the atmosphere
of particulate matter, or (2) if in the course of reconstruction of the
facility, the fixed capital cost of the new components exceeds 50 percent
of the cost that would be required to construct a comparable entirely new
facility that meets the NSPS.
3.2 Controlled Pollutants and Emission Levels
Particulate matter is the pollutant regulated by the NSPS, and dryer
emissions are limited to not more than 0.15 kg of particulate matter per
Mg (0.30 Ib/ton) of AS produced. Visible emissions are limited to not
more than 15 percent opacity.
3.3. Monitoring Requirements
The promulgated standards require continuous monitoring of the mass
flow of ammonium sulfate feed material to the crystal! izer. Those facilities
with weigh scales are exempt from this requirement. The feed stream in a
3-1
-------
caprolactam plant is the oximation AS stream to the AS plant and the
oleum stream to the caprolactam rearrangement reaction. The feed stream
in synthetic and coke oven by-product plants is the sulfuric acid stream
to the crystallizer.
Another requirement of the standard is continuous monitoring of the
pressure drop across the control system for the affected facility to help
insure proper operation and maintenance of the system. Mass flow
and pressure drop data, including calibration measurements of the
instrumentation, must be maintained for 2 years by the affected facility.
There is no in-stack opacity monitoring requirement due to the use
of wet scrubbing in most AS particulate control applications. The presence
of water droplets in the stack would make the exhaust gases difficult to
monitor by available equipment.
3.4. Testing Requirements
The EPA Reference Methods (40 CFR 60, Appendix A) to be used in
conjunction with compliance testing of AS dryers include:
1. Method 5 for the concentration of particulate matter.
2. Method 1 for sample and velocity traverses.
3. Method 2 for velocity and volumetric flow rate.
4. Method 3 for gas analysis.
For Method 5, the sampling time for each run shall be 60 minutes minimum,
and the volume shall be at least 1.50 dry standard cubic meters (53 dry
standard cubic feet). Methods for computing particulate emission rates
and AS production rates are contained in 40 CFR 60, Subpart PP.
3-2
-------
4. STATUS OF CONTROL TECHNOLOGY
4.1 Emission Sources
The ammonium sulfate dryer is the main source of particulate emissions
in the AS manufacturing process, and the only source which is regulated
by the NSPS. Both fluidized bed dryers and rotary dryers are used in AS
producing facilities. All fluidized bed dryers found in the industry are
heated indirectly with steam-heated air. Rotary dryers may be either direct
fired (by oil or gas) or steam heated.
Gas flow rates are higher for steam heated dryers—typically 2200 scm/Mg
of product (70,000 scf/ton), than for direct fired units--600 scm/Mg (20,000
scf/ton). Fluidized bed dryers have demonstrated higher rates of uncontrolled
emissions, largely due to fines being swept out of the system. Because this
characteristic creates a more granular, salable product, fluidized bed dryers
are more desirable from a production standpoint. Fluidized bed dryers exhibit
greater heat and mass transfer rates, and smaller space requirements than rotary
dryers with the same throughput. Capital and operating costs are also less
for fluidized bed dryers, making them more economically desirable.1 Fluidized
bed dryers, however, would require more efficient particulate control equipment
in order to comply with air pollution regulations, as the emission rates per
ton of product are greater.
Table 4-1 contains a summary of uncontrolled particulate emissions from
several dryersjn the industry that were tested using EPA Method 5.2 The wide
range of uncontrolled emissions (expressed as mass of particulate emissions
per mass of product) is a result of the various flow rates for differing
4-1
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TABLE 4-1. SUMMARY OF UNCONTROLLED EMISSION DATA
FROM EPA EMISSION TESTS ON AS DRYERS
Plant
A
B
C
D
Dryer Type
Rotary Drum
Fluidized Bed
Rotary Drum
Rotary Drum
Average Uncontrolled AS Emissions
gm/dscm
4.38
39.0
8.87
98.3
(gr/dscf)
( 1-93)
(17.2 )
( 3.91)
(43.2 )
kg/Mg
0.41
110.0
3.46
77.0
(Ib/ton)
( 0.82)
(221.0 )
( 6.92)
(153.0 )
4-2
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dryer systems. The high rotary dryer emission rate at Plant D was attributed
to a high inlet emission load caused by a process variation at the plant.
It was indicated that the crystallizer at Plant D periodically goes into a
fines cycle, lasting anywhere from 10 to 15 hours, during which time a much
heavier proportion of AS fines is produced in the dryer product than is normal.3
Plant personnel stated that the operator can prevent this condition by varying
the dryer air flow rate, but this was not done during testing so as to maintain
constant operating conditions. Particulate emission rates are directly
related to the gas-to-product ratio, and are influenced by gas velocity and
particle size distribution. No additional data on uncontrolled emissions
from AS dryers have become available since promulgation of the NSPS.
4.2 Emission Control Equipment in the Ammonium Sulfate Industry
There have been no major changes in control technology since promulgation
of the ammonium sulfate NSPS. Wet scrubbing is used at all of the operating
ammonium sulfate facilities for the control of AS dryer particulate emissions.
The use of wet scrubbing is for environmental reasons, as well as to increase
production efficiencies. Wet control processes allow easy recycle of captured
AS particles back into process streams, increasing production efficiency and
eliminating the cost of waste disposal. The moderately high water solubility
of AS makes wet scrubbing and recycle of captured particulates a viable
control alternative. Industry supplied operating and performance data for a
number of wet scrubbers in use is presented in Table 4-2. Most of the scrubbers
are of the low energy type with pressure drops equal to or less than 15 cm
4-3
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TABLE 4-2. AMMONIUM SULFATE INDUSTRY-SUPPLIED WET SCRUBBER PERFORMANCE DATA3
Plant F
Plant E
Plant B
Plant H
Plant G
Plant I
Plant C
Plant D
Scrubber
Vendor
Ducon
AAFb
AAF
Ducon
Ducon
MAC
NA
NA
Ducon
Ducon
Heil
AS Scrubber
Type
Centrifugal
Rotocloned
Rotoclone
Centrifugal6
Centri fugal
Venturi
Spray
Packed Tower &
NH3 Condenser
Packed Tower
Centrifugal
Centrifugal
Venturi
AS Production Gas Flow to Observed Scrubber
Rate Scrubber Pressure Drop
Mg/hr (TPH) sm3/min (scfm) cm H90 WC (in H00 WC)
1,127 (39,900)
410 (14,600)
810 (28,600)
19.1 (21) 144 ( 5,100)
19.1 (21) 242 ( 8,560)
14.7 (16) 73 ( 2,585)
8.50 ( 9.34) 90 ( 3,180)
16.2 (17.8 ) 112 ( 3,950)
8.4 (9.2 ) 85 ( 3,000)
7.6 (3)
12.7 (5)
12.7 (5)
34.0 (13.4)
22.9 ( 9.0)
25.9 (10.2)
17.3 ( 6.8)
UKf
UK
15.2 ( 6)
15.2 ( 6)
33.0 (13)
Scrubber L/G Ratio9
Liters/lOOOm3
(gal/1000 acf)
254 (1.9)
348 (2.6)
415 (3.1)
267 (2.0)
267 (2.0)
3,075 (23.0)
909 (6.8)
3,338 (25.0)
40,050 (300)
2,311 (17.3)
267 ( 2.0)
267 ( 2.0)
3,605 (26.9)
<•» All data supplied by industry in response to EPA 114 letter requests or from visits to AS production plants.
b American Ai r Filter.
c Not Applicable (not a standard design).
d Trade name of American Air Filter Company.
e Cyclones precede centrifugal scrubbers.
f Unknown.
9 Scrubber liquid-to-gas ratio.
-------
TABLE 4-2. (cont) AMMONIUM SULFATE INDUSTRY-SUPPLIED WET SCRUBBER PERFORMANCE DATA
i
en
AS Particulate Concentrati
on
Scrubber Inlet Scrubber Outlet
mq/dsm3 (gr/dscf) mg/dsnP (gr/dscf)
PI
PI
PI
PI
PI
PI
PI
ant
ant
ant
ant
ant
ant
ant
F
E
B
H
G
I
C
220
57.2
708
87
48
28,500 (12.4) 11.5
25.2
9.2
41.2
48.1
36.7
(.096)
(.025)
(.309)
(.038)
(.021)
(.005)
(.011)
(.004)
(.018)
(.021)
(.016)
AS Mass Flow
Scrubber Inlet Scrubber
kg/hr (Ib/hr) kg/hr
5.6
1.2
1,909 (4,200) .45
.22
.14
.23
.254
.25
AS Mass
Outlet
(Ib/hr)
(12.4 )
( 2.67)
(i.o )
(.48 )
(.30 )
(.50 )
(.56 )
(.55)
Discharge
kg/Mg (1
.13 (
.032 (
.36 (
.26 (
.14 (
.037 (
.012 (
.007 (
.016 (
.030 (
.015 (
Rate
b/ton
.25 )
.065)
.72 )
.52 )
.27 )
.073)
.023)
.014)
.031)
.06 )
.031)
Plant D
-------
(6 in.) WG. The data contained in Table 4-2 were provided by AS producers
during EPA plant visits and in responses to EPA inquiries during development
of the NSPS in 1978-79, and do not reflect any equipment modifications which
may have occurred since that time.
4.2.1 Venturi Scrubbers - Two existing AS plants employ venturi scrubbers
to control particulate emissions. Pressure drops and liquid-to-gas ratios
are similar for both of these control devices. Performance data and emission
test data for the venturi scrubber at Plant B are included in Table 4-2. No
emission test data were supplied for the venturi scrubber at Plant D. Based
o~n test measurements of the scrubber inlet and outlet mass flows, the venturi
at Plant B has an average collection efficiency of 99.96 percent, which is
typical of venturi scrubbers in other applications. Particulate emissions
average .037 kg/Mg of AS production. A 25 percent AS solution was used as
the scrubbing liquid, and although the emission test was conducted at
approximately 50 percent of the maximum production rate, the collection
efficiencies are similar to those measured during a period of full capacity
production.^
4.2.2 Centrifugal Scrubbers - Centrifugal scrubbers are employed at a number
of AS plants for particulate control, including two of the three existing
caprolactam plants. Energy requirements and collection efficiencies of
centrifugal scrubbers are generally lower than those of Venturis. Emission
test data for centrifugal scrubbers at Plants C, E, and F are provided in
Table 4-2. Pressure drops range from 7.6 cm to 34.0 cm WG (3 to 13.4 in. WG),
4-6
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and mass emissions vary from 0.015 to 0.26 kg/Mg (0.031 to 0.52 ib/ton) of AS
production. No centrifugal scrubber inlet data are available, and collection
efficiencies cannot be determined.
4.2.3 Other Wet Scrubbers in the AS Industry - Several other wet scrubbing
systems currently in use for AS particulate control include packed tower
scrubbers, spray type scrubbers, and Type "N" Rotoclones (a trade name of
American Air Filter Corporation). Particulate control data for each of these
control devices are presented in Table 4-2 (Plants H, G, and I). Collection
efficiencies of these devices are generally lower than those of previously
mentioned AS particulate control devices. Vendor design efficiency data for
Rotoclones typically ranges from 90 to 99.3 percent for particulates 3 microns
in diameter, with pressure drops of 15.3 to 28 cm (6 to 11 in.) WG and high
liquid-to-gas ratios.5 Collection efficiencies of packed towers depend on
liquid-to-gas ratios and pressure drops. One plant which designed its own
packed tower reports an estimated collection efficiency of less than 90
percent.5 Spray-type scrubbers demonstrate collection efficiencies near
75 percent for most types of 2 micron particulates. Pressure drops are low,
usually 2.5 cm to 5 cm (1-2 in.) WG.6
4.2.4 Fabric Filtration in the Ammonium Sulfate Industry
Only one known domestic producer of AS has used a baghouse for AS particulate
control, but this plant has been mothballed since 1979.7 The unit has 30m2
(320 ft2) of filter cloth which comprises 24 bags, and it employs a reverse
jet cleaning mechanism. The filter medium is Dacron® felt, which exhibits
good acid resistance and flex abrasion. At the operating gas flow rate of
approximately 35m3/min (1250 acfm) the gas-to-cloth ratio of this baghouse
is 4:1.
4-7
-------
Fabric filters are adversely affected if condensation occurs in the
baghouse, and this is especially true in ammonium sulfate particulate control.
Caking of AS particles due to condensation may cause blinding in fabric
filters. It is imperative that the exhaust gas be maintained at a temperature
above the dew point to avoid this problem. This is the major drawback in
employing fabric filters for AS particulate control. Evidence of condensation
problems at the existing baghouse has been confirmed by AS accumulations on
the inside wall of the inlet ducts, and periodic shutdown for bag removal,
laundering, and reinstallation (every 30 days). It is possible that energy
requirements for maintaining temperatures above the dew point may require
more energy than would ordinarily be required to operate the dryer.^
4.3 Plant Testing
During the development of the existing NSPS for ammonium sulfate plants
a survey of producing facilities determined that very few met the criteria
for AS particulate emission testing to support an NSPS. These criteria
i ncluded:
0 Candidate best demonstrated control technology in operation
0 Accessibility of potential control equipment sampling ports
0 Control equipment age and/or condition
0 Availability of sampling ports and support scaffolding
0 Reasonably nonturbulent flow field
0 Representative plant capacity
Four AS producing facilities were selected which met the criteria for testing,
and emissions testing was carried out by EPA contractors at each facility,
designated A through D. EPA Method 5 was used to determine AS particulate
4-8
-------
emission rates and grain loadings at the inlet and outlet of each control
device. Table 4-3 describes the selected test facilities, type of AS production
process employed, and control technology in use. Plant E was not tested by EPA;
information was provided by a State Agency, and the test methodology was
judged acceptable by EPA.
TABLE 4-3. AS PARTICULATE CONTROL SYSTEMS TESTED BY EPA
Plant
Designation
A
B
C
D
E
AS
Process
Synthetic
Caprolactam
Synthetic
Syntheti c
Caprol act am
Controlled
Facility
Rotary Dryer
Fluid Bed Dryer
Rotary Dryer
Rotary Dryer
Fluid Bed Dryer
Control Technology
In Use
Baghouse
Venturi Scrubber
Centrifugal Scrubber
Venturi Scrubber
Cyclones and
Centrifugal Scrubber
Results of EPA emission testing at facilities A through D are summarized
in Table 4-4, along with the industry-supplied emission data from Plant E.
The wide range of uncontrolled emission data represents the varying process
rates for AS drying equipment encountered in the industry. Lower parti cul ate
removal efficiencies at Plants A and C can be attributed partially to lower
uncontrolled dryer emission rates at these respective facilities. With
differences in uncontrolled emission rates at Plants A and C near two orders
of magnitude as compared with those of Plants B and D, comparison of outlet
mass emissions only for all four facilities may be somewhat misleading.
4-9
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TABLE 4-4. RESULTS OF EPA EMISSION TESTING
Plant
Designation
A
B
C
0
E
AS Production
Rate (Mg/hr)
16.4
26.5
15.2
8.4
8.9
Average
Uncontrolled
Emission Rate
(kg/Mg)
0.41
110.0
3.46
77.0
N.A.*
Average
Control led
Emission Rate
(kg/Mg)
.007
.156
.08
.14
.14
Particulate
Removal
Efficiency
(%)
98.3
99.9
97.7
99.8
N.A.
* Not Available
4.5 References
1. Ammonium Sulfate Manufacture - Background Information for Proposed
Emission Standard, EPA-450/3-79-034a, p. 3-10.
2. Reference 1, p. 3-11.
3. Reference 1, p. 9-12.
4. Reference 1, p. 4-10.
5. Reference 1, p. 4-12.
6. Reference 1, p. 4-13.
7. Information provided by Occidental Chemical Corporation in a telephone
conversation between Russ Bowman and Peter Schindler, U.S. Environmental
Protection Agency, Research Triangle Park, N.C., on July 13, 1984.
8. Reference 1, p. 4-15.
4-10
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5. COMPLIANCE TEST RESULTS
Since proposal and promulgation of the NSPS, there have been no new,
reconstructed, or modified facilities which have come under the NSPS. Emission
testing, however, has been performed at some existing facilities, and testing
results have been obtained by EPA.
A second State-approved emission test was performed at Plant E by a
contractor to the company and the State has provided the test results to
EPA.l The test results are contained in Table 5-1, and are well below the
NSPS requirements, at .04 kg/Mg of AS production. This facility operates one
rotary dryer and one fluidized bed dryer. The exhaust air from both dryers
is combined and treated in a series of fines removal cyclones before it is
redistributed to two wet scrubbers. The scrubbers, a Ducon type UW-3 size
126 and a Ducon type UW-3 size 72, are of the centrifugal type, and air flows
are 1250 m3/min (44,000 acfm) and 450 m3/min (16,000 acfm), respectively.
The scrubbers discharge to the atmosphere through separate stacks at about
80 feet above the ground. The emission test data provided by the State was
for the size 72 scrubber, which is the smaller of the two, and the newer
control device.2
In response to a written request from EPA, emission data have been
provided from a caprolactam by-product AS plant, designated Plant J. This
plant expanded AS production capacity in 1980, but the expansion is not
subject to NSPS based on the date for commencement of construction. The
plant controls particulate emissions from rotary dryers, centrifuges, and
fugitive sources by the use of wet scrubbers. Two scrubbers were replaced
recently, one handling centrifuge emissions (1979) and the other treating
rotary dryer emissions (1980). Both new units are Ducon UW-4 scrubbers,
5-1
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size 42 and 66, respectively, and operating efficiencies are reported to be
99 percent for each. The centrifuge abatement reduced AS particulate emissions
from 14.6 Mg/yr to 5.1 Mg/yr, though this emission source is not subject to
NSPS. The scrubbing liquor for all dust collectors at this plant is a recir-
culated oxime sulfate solution with a 10 gpm liquid rate per scrubber.
Emissions testing was performed for the rotary dryer and new scrubber addition
as part of the State permitting process, and emission results were 0.021 kg/Mg
AS produced.3 Test results for this dryer at Plant J, designated dryer #4, are
presented in Table 5-1. Additional controlled emissions data for three other
rotary dryers at Plant J are included in Table 5-1. Dryers #1, #2, and #3 were
tested in conjunction with the State's Prevention of Significant Deterioration
(PSD) program. Dryer #1 was tested in November 1980, and #2 and #3 were tested
in December 1983.4 The reported emission data from Table 5-1 indicates that
the NSPS for ammonium sulfate particulate matter (.15 kg/Mg AS produced) is
being easily achieved by current control methods.
TABLE 5-1. INDUSTRY SUPPLIED EMISSION TEST DATA
Plant Controlled
Facility
Production Air Flow Controlled
Control Rate Rate Emission Rate
(Mg/hr) (DSCM/min) (kg/Mg)
E
J
#1
#2
#3
#4
1 Rotary & 1 FB
(dryer-stream
combi ned)
Rotary Dryer
Rotary Dryer
Rotary Dryer
Rotary Dryer
- -1 - - 1
Centrif .
Scrubber
(CS)
CS
CS
CS
CS
9.85
44.5
36.4
81.8
52.7
421.7
215.9
221.8
359.4
196.3
0.04
0.031
0.053
0.090
0.021
5-2
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5.1 References
1. Letter from Lou Musgrove, State of Georgia, Department of Natural
Resources, Environmental Protection Division, to Peter Schindler,
U.S. Environmental Protection Agency, Research Triangle Park, N.C.,
dated June 11, 1984.
2. Information provided in a telephone conversation between Lou Musgrove,
State of Georgia EPD, and Peter Schindler, U.S. EPA, on October 9, 1984.
3. Letter from F. L. Piguet, Allied Fibers & Plastics, to Jack Farmer,
U.S. Environmental Protection Agency, Research Triangle Park, N.C.,
dated August 2, 1984.
4. Information provided in a telephone conversation between Evans Drake,
Allied Fibers and Plastics, and Peter Schindler, U.S. EPA, on
October 5, 1984.
5-3
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6. COST ANALYSIS
This chapter presents the updated costs of a control system required
to best achieve the current NSPS for ammonium sulfate particulate matter.
Venturi scrubbers are the selected control systems for cost analysis in the
three segments of the AS industry, as they represent best demonstrated control
technology (8DCT). Capital and annualized costs of venturi scrubbers are
estimated for three new model AS plants; a 22.7 Mg (25 ton) per hour caprolactam
by-product plant, a 13.6 Mg (15 ton) per hour synthetic plant, and a 2.7 Mg
(3 ton) per hour coke oven by-product plant. All costs are presented in
March 1984 dollars and are considered to be accurate to +. 30 percent.
The control system includes all the equipment and auxiliaries required
to provide the specified emission control. The capital cost of a control
system includes all the cost items necessary to design, purchase, install,
and commission the control system. In addition to the direct costs, the
capital cost includes such indirect items as engineering, contractor's fee,
construction expense, and a contingency.
The annualized cost represents the cost of owning and operating the
control system. The operating cost covers the utilities, supplies, and
labor required to operate and maintain the system on a day-to-day basis.
The cost of owning the system includes capital-related charges such as
capital recovery, property taxes, insurance, and administrative charges.
6.1 Capital Costs
The capital costs for a venturi scrubbing system are estimated for
three model plants, representing each segment of the AS industry. Cost
breakdowns for each model plant are presented in Tables 6-1 through 6-3.
6-1
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TABLE 6-1. CAPITAL COST SUMMARY FOR A VENTURI SCRUBBING SYSTEMS
(Caprolactam By-Product Plant with 22.7 Mg/hr Capacity)
Description Cost (10-3 dollars)
A. Di rect Costs
1. Scrubber, fan and auxiliaries (C) 113.3
2. Instruments and controls (10% of C) 11.3
3. Taxes (3% of C) 3.4
4. Freight (5% of C) 5.7
Base Price (B) 133.7
5. Installation^ (56% of B) 74.9
Total Direct Costs (TDC) 208.6
B. Indirect Costs
1. Engineering and supervision (10% of B) 13.4
2. Construction and field (10% of B) 13.4
3. Construction Fee (10% of B) 13.4
4. Start-up (1% of B) 1.3
5. Performance Test (1% of B) 1.3
6. Contingencies (3% of B) 4.0
Total Indirect Cost (TIC) 46.8
Total Capital Cost 255.4
a March 1984 dollars.
b Includes factors for foundations and supports, handling and erection,
piping, electrical, insulation, and paint. Does not include costs
for site preparation, facilities, and buildings.
Source: " Estimating Air Pollution Control Costs," Part II, Table I.
6-2
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TABLE 6-2. CAPITAL COST SUMMARY FOR A VENTURI SCRUBBING SYSTEM*
(Synthetic Plant with 13.6 Mg/hr Capacity)
Description Cost (103 dollars)
A. Direct Costs
1. Scrubber, fan and auxiliaries (C) 45.9
2. Instruments and controls (10% of C) 4.6
3. Taxes (3% of C) 1.4
4. Freight (5% of C) 2.3
Base Price (B) 54.2
5. Installation^ (56% of B) 30.4
Total Direct Costs (TOC) 84.6
B. Indirect Costs
1. Engineering and supervision (10% of B) 5.4
2. Construction and field (10% of B) 5.4
3. Construction Fee (10% of B) 5.4
4. Start-up (1% of B) 0.5
5. Performance Test (1% of B) 0.5
6. Contingencies (3% of B) 1.6
Total Indirect Cost (TIC) 18.8
Total Capital Cost 103.4
a March 1984 dollars.
h Includes factors for foundations and supports, handling and erection,
piping, electrical, insulation, and paint. Does not include costs
for site preparation, facilities, and buildings.
Source: "Estimating Air Pollution Control Costs," Part II, Table I.
6-3
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TABLE 6-3. CAPITAL COST SUMMARY FOR A VENTURI SCRUBBING SYSTEMa
(Coke Oven By-Product Plant with 2.7 Mg/hr Capacity)
Description Cost (10^ dollars)
A. Di rect Costs
1. Scrubber, fan and auxiliaries (C) 40.6
2. Instruments and controls (10% of C) 4.1
3. Taxes (3% of C) 1.2
4. Freight (5% of C) 2.0
Base Price (B) 47.9
5. Installation13 (56% of B) 26.8
Total Direct Costs (TDC) 74.7
B. Indirect Costs
1. Engineering and supervision (10% of B) 4.8
2. Construction and field (10% of B) 4.8
3. Construction Fee (10% of B) 4.8
4. Start-up (1% of B) .5
5. Performance Test (1% of B) .5
6. Contingencies (3% of B) 1.4
Total Indirect Cost (TIC) 16.8
Total Capital Cost 91.5
a March 1984 dollars.
b Includes factors for foundations and supports, handling and erection,
piping, electrical, insulation, and paint. Does not include costs
for site preparation, facilities, and buildings.
Source: "Estimating Air Pollution Control Costs," Part II, Table I.
6-4
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The methods for determining representative capital costs are described in
the EPA publication "Estimating Air Pollution Control Costs," May 1984. This
publication is a compilation of 18 articles on air pollution control cost
estimating which appeared in Chemical Engineering magazine from October 6,
1980 to April 30, 1984. All costs in this study were updated to March 1984
dollars by the Chemical Engineering Plant Cost Index for fabricated equipment.
The operating parameters for the venturi system used in this cost study are
presented in Table 6-4. The venturi scrubber is evaluated for three different
air flow rates, typical of the dryers in each AS industry segment. Volumetric
flow rate, pressure drop, and materials of construction are the main variables
for determining venturi scrubber capital costs.
6.2 Annualized Costs
In the ammonium sulfate industry the annualized cost of operating a
particulate control device is a function of the number of hours the dryer
operates per year. This value determines operating costs such as labor,
utilities, and overhead. In this study, AS dryers are assumed to operate
at the following rates: 8,400 hours/year for caprolactam by-product plants,
5,400 hours/year for synthetic plants, and 7,400 hour/year for coke oven
by-product plants. Annualized costs and cost factors are calculated from
current labor prices and from Part II of "Estimating Air Pollution Control
Costs," and are updated to March 1984 dollars.
Annualized cost breakdowns for venturi scrubbers in each of the three
regulated AS industry segments are presented in Tables 6-5 through 6-7.
Credits for recovery of AS dryer emissions by venturi scrubbers help to
6-5
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TABLE 6.4 VENTURI SCRUBBER OPERATING PARAMETERS
A. Pressure drop: 30.5 cm (12 in) H20
B. Liquid-to-gas ratio: 0.33 m3/100m3 (25 gal/103 ft3)
C. Operating temperatures
1. Inlet: 79°C (175°F)
2. Outlet: 43°C (110°F)
0. Construction materials: fiberglass lined carbon steel
E. Fan
1. Location: between dryer and venturi
2. Materials: 304 SS
3. Head pressure: 38.1 cm (15 in) H20 @ 21°C, 1 atm
4. Type: radial tip
F. Average venturi life: 10 yr
G. Particulate removal efficiency: 99.9%
H. Scrubbing liquor: 25% AS solution
I. Gas flow rate from dryer
1. Caprolactam: 1005 m3/min (35,500 cfm)
2. Synthetic: 168 m3/min (5,920 cfm)
3. Coke oven: 199 m3/min (4,200 cfm)
6-6
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TABLE 6-5. ANNUALIZEO COST SUMMARY FOR A VENTURI SCRUBBING SYSTEM
(Caprolactam By-Product Plant with 22.7 Mg/hr Capacity)
Cost Element Cost (lo3 dollars)
A. Direct Operating Costs
1. Utilities
a. Water ($0.40/1000 gal) 17-9
b. Electricity ($0.05/kwh) 54.5
2. Operating Labor
a. Direct ($10.89/hr @ 4 hrs/shift) 45.7
b. Supervision (15% Direct Labor) 6.9
3. Maintenance
a. Labor (110% x Direct Labor @ 1 hr/shift) 12.6
b. Materials (100% x Maint. Labor) 12.6
B. Capital Charges
1. Overhead [80% x (2a + 2b + 3a)] 52.2
2. Fixed Costs
a. Capital Recovery (16.3% x Capital Costs) 41.6
b. Insurance, taxes, admin. (4% x Capital Costs) 10.2
C. Subtotal 254-2
D. Credit for Recovered Product3 (1,012.8)
E. Net Annualized Cost ( 758.6)
a Based on a $60/Mg price for by-product AS, with 20% reprocessing charge,
b Values in parenthesis are cost savings.
Source: "Estimating Air Pollution Control Costs," Part II, Table III.
6-7
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TABLE 6-6. ANNUALIZED COST SUMMARY FOR A VENTURI SCRUBBING SYSTEM
(Synthetic Plant with 13.6 Mg/hr Capacity)
Cost Element Cost (1()3 dollars)
A. Direct Operating Costs
1. Utilities
a. Water ($0.40/1000 gal) 1.9
b. Electricity ($0.05/kwh) 5.8
2. Operating Labor
a. Direct ($10.89/hr @ 4 hrs/shift) 29.4
b. Supervision (15% Direct Labor) 4.4
3. Maintenance
a. Labor (110% x Direct Labor @ 1 hr/shift) 8.1
b. Materials (100% x Maint. Labor) 8.1
B. Capital Charges
1. Overhead [80% x (2a + 2b + 3a)] 33.5
2. Fixed Costs
a. Capital Recovery (16.3% x Capital Costs) 16.8
b. Insurance, taxes, admin. (4% x Capital Costs) 4.1
C. Subtotal 112<1
D. Credit for Recovered Product9 (152.0)b
E. Net Annualized Cost ( 39-9)
a Based on a $100/Mg price for synthetic AS, with 20% reprocessing charge.
b Values in parenthesis are cost savings.
Source: "Estimating Air Pollution Control Costs," Part II, Table III.
6-8
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TABLE 6-7. ANNUALIZED COST SUMMARY FOR A VENTURI SCRUBBING SYSTEM
(Coke Oven By-Product Plant with a 2.7 Mg/hr Capacity)
Cost Element C°st <103 d°11ars>
A. Direct Operating Costs
1. Utilities
a. Water ($0.40/1000 gal) I-9
b. Electricity ($0.05/kwh) 5-8
2. Operating Labor
a. Direct ($10.89/hr @ 4 hrs/shift) 40.3
b. Supervision (15% Direct Labor) 6-°
3. Maintenance
a. Labor (110% x Direct Labor @ 1 hr/shift) 11.1
b. Materials (100% x Maint. Labor) H.l
B. Capital Charges
1. Overhead [80% x (2a + 2b + 3a)] 45.9
2. Fixed Costs
a. Capital Recovery (16.3% x Capital Costs) 14.9
b. Insurance, taxes, admin. (4% x Capital Costs) 3.7
C. Subtotal 140'7
D. Credit for Recovered Product3 (9.6)
E. Net Annualized Cost 131-1
a Based on a $60/Mg price for by-product AS, with a 20% reprocessing charge,
b Values in parenthesis are cost savings.
Source: "Estimating Air Pollution Control Costs," Part II, Table III.
6-9
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offset annualized costs, which improves the cost effectiveness for participate
removal. In this study, the recovery credits in a 22.7 Mg/hr caprolactam
by-product AS plant and in a 13.6 Mg/hr synthetic AS plant create a net
savings in annualized costs. This does not hold true for the coke oven
by-product AS plant because a much lower AS production rate (2.7 Mg/hr)
and lower uncontrolled emissions limit the collected particulates available
for capture and process recycle.
Credits for recovered product will vary directly with changes in the
market price of ammonium sulfate. Credits for this cost study are calculated
based on a March 1984 average wholesale price of $60/Mg for by-product AS and
$100/Mg for synthetic granular AS, with a 20 percent reprocessing charge.1
Average U.S. market prices for AS over the past years are presented in Table 6-8.
6.3 Cost Effectiveness
The cost effectiveness of controlling AS particulate emissions can
be related to the quantity of pollutants removed from dryer exhaust streams
by using the annualized costs as a basis. This study utilizes a 99.9 percent
efficient particulate recovery rate by the control device, and particulate
emission rates from typical AS dryers as listed in Chapter 2. The calculated
cost effectiveness of venturi scrubbers for AS particulate control at each
•
model plant is presented in Table 6-9. The cost effectiveness varies from
a savings of $36/Mg of particulate removed in the caprolactam by-product
plant to a cost of S655/Mg of particulate removed in the coke oven by-product
AS plant. The synthetic AS plant in this study demonstrated a savings of
6-10
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TABLE 6-8. AVERAGE U.S. RETAIL PRICE FOR AMMONIUM SULFATE
Month/Year Price (S/ton)
March 1984 150
March 1983 146
March 1982 165
March 1981 150
March 1980 138
March 1979 118
March 1978 109
March 1977 101
April 1976 98.20
April 1975 148
April 1970 52.40
April 1965 53.40
Sources:
Fertilizer Trends 1982 - TVA National Fertilizer Development Center.
Prices Paid by Farmers - Crop Reporting Board, SRS, USDA, October 1983,
Information provided from Paul Andalinas, USDA.
6-11
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TABLE 6-9. COST EFFECTIVENESS OF AS PARTICULATE RECOVERY USING
VENTURI SCRUBBERS (March 1984 dollars)
Plant Size
Plant Type Mg/hr (ton/hr)
Annualized Cost AS Removed3 Cost Effectiveness
($1000/yr) (Mg/yr)a ($/Mg AS Removed)
Caprol actam
Synthetic
Coke Oven
22.7
13.6
2.7
(25)
(15)
( 3)
[758. 6]b
[ 39.9]
131.1
21,095
1,915
200
[ 36]
C 21]
655
a Based on 99.9% collection efficiency.
b Brackets indicate cost savings.
6-12
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$21 per Mg particulate removed. These values are sensitive to AS market prices
and particulate recovery efficiencies.
6.4 References
1. Information obtained in a telephone conversation between E. Harre, TVA
National Fertilizer Development Center, and Peter Schindler, U.S. EPA,
on September 7, 1984.
6-13
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-450/3-85-004
2.
4, TITLE AND SUBTITLE
Review of Standards of Performance for Ammonium
Sulfate Manufacture
7. AUTHOR(S)
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Office of Air Quality Planning and Standards
U.S. Environmental Protection Agency
Research Triangle Park, N.C. 27711
12. SPONSORING AGENCY NAME AND ADDRESS
Director for Air Quality Planning and Standards
Office of Air and Radiation
U.S. Environmental Protection Agency
Research Triangle Park, N.C. 27711
3. RECIPIENT'S ACCESSION NO.
5. REPORT DATE
February 1985
6. PERFORMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT NO.
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
EPA/200/04 j
15. SUPPLEMENTARY NOTES ' ~~ ~
This report presents the findings of the 4-year review of the new source
performance standards for ammonium sulfate manufacture. Affected facilities
are those dryers at plants that manufacture ammonium sulfate as a caprolactam
by-product, as a coke oven by-product, or by synthetic manufacture (direct
combination of ammonia and sulfuric acid).
17- KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
Air Pollution
Pollution Control
Ammonium Sulfate Manufacturing
Caprolactam
18. DISTRIBUTION STATEMENT
Unlimited
b. IDENTIFIERS/OPEN ENDED TERMS
Air Pollution Control
Stationary Sources
19. SECURITY CLASS (this Report)
Unclassified
20. SECURITY CLASS 1 This page)
Unclassified
c. COS ATI Field/Group
135
21. NO. OF PAGES
Rfi
22. PRICE
EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDI TION is OBSOLETE
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