United States Office of Air Quality EPA-450/3-81 -001
Environmental Protection Planning and Standards January 1981
Agency Research Triangle Park NC 27711
Air
Urea Manufacturing
Industry — Technical
Document
-------
EPA-450/3-81-001
Urea Manufacturing
Industry — Technical
Document
Emission Standards and Engineering Division
Contract No. 68-02-3058
U.S. Environmental Protection Agency
Region 5, Library (Pi.12j) 7
77 West Jackson Boulevard l?fK n
Chicago, JL 60604-3590 ' 12th Flo°f
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air, Noise, and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
January 1981
-------
This report has been reviewed by the Emission Standards and Engineering
Division, Office of Air Duality Planning and Standards, Office'of Air,'Noise,
and Radiation, Environmental Protection Agency, and approved for publication.
Mention of company or product names does not constitute endorsement by EPA.
Copies may be obtained, for a fee, from the National Technical Information
Service, 5285 Port Royal Poad, Springfield, VA. 22161.
-------
TABLE OF CONTENTS
Chapter Page
1.0 Introduction and Summary 1-1
1.1 Purpose 1-1
1.2 Summary 1-1
2.0 The Urea Industry 2-1
2.1 Industry Structure 2-1
2.2 Urea Products and End Uses 2-4
2.3 References 2-7
3.0 Processes and Their Emissions 3-1
3.1 Introduction 3-1
3.2 Description of Processes and Emissions 3-8
3.3 References 3.37
4.0 Emission Control Techniques 4-1
4.1 Overview of Control Techniques 4-1
4.2 Description of Control Techniques 4-5
4.3 Emission Test Data 4-26
4.4 Evaluation of Control Device Performance 4-43
4.5 References 4-57
5.0 Model Plants and Control Alternatives 5-1
5.1 Model Plants 5-1
5.2 Determination of Existing Control Levels 5-7
5.3 Control Options ..... 5-18
5.4 Control Alternatives 5-30
5.5 References 5-32
6.0 Environmental Impacts 6-1
6.1 Air Pollution Impact 6-1
6.2 Water Pollution Impact 6-4
6.3 Solid Waste Impact 6-6
6.4 Energy Impact 6-6
6.5 Other Impacts 6-8
6.6 References 6-9
7.0 Cost Analysis 7_1
7.1 Cost Analysis of Control Alternatives 7-1
7.2 Other Cost Considerations 7-20
7.3 References 7-23
Appendix A A-1
Appendix B B-l
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LIST OF TABLES
Table Page
1-1 Control Alternatives 1-3
1-2 Summary of Control Alternatives and their
Effect on Product Price 1-4
2-1 Urea Producers - Plants, Locations, and Capacities . 2-2
2-2 Urea Production by Use 2-5
3-1 Uncontrolled Emissions From Urea Facilities .... 3-5
3-2 Estimated Annual Uncontrolled Emissions From
Typical Urea Plants 3-7
3-3 Uncontrolled Urea Particulate Emission Tests
For Nonfluidized Bed Prill Towers 3-22
4-1 Summary of Use of Wet Scrubbers in The Urea
Industry 4-3
4-2 Summary of EPA Mass Emission Test Results 4-28
4-3 Summary of EPA Visible Emission Test Results .... 4-29
4-4 Summary of Industry Mass Emission Test Results
For Controlled Prill Towers 4-30
4-5 Summary of Cooler Controlled Emissions 4-41
5-1 Model Urea Plants 5-2
5-2 Raw Material and Utility Requirements for
Model Plants 5-8
5-3 Summary of Existing Emission Levels 5-9
5-4 Emissions Standards Affecting Urea Plants 5-12
5-5 Allowable Emissions by Plant Size (Metric Units) . 5-14
5-5 Allowable Emissions by Plant Size (English Units) 5-15
5-6 Control Equipment Performance Parameters 5-19
m
-------
LIST OF TABLES
(Continued)
Table
5-7
5-8
5-9
5-10
5-11
5-12
5-13
5-14
5-15
5-16
5-17
6-1
6-2
6-3
6-4
Emission Characteristics for Model Plant 1
Control Options
Emission Characteristics for Model Plant 2
Control Options
Emission Characteristics for Model Plant 3
Control Options
Emission Characteristics for Model Plant 4
Control Options
Emission Characteristics for Model Plant 5
Control Options
Emission Characteristics for Model Plant 6
Control Options
Emission Characteristics for Model Plant 7
Control Options
Emission Characteristics for Model Plant 8
Control Options
Emission Characteristics for Model Plant 9
Control Options
Emission Characteristics for Model Plant 10
Control Options
Control Alternatives
Emission and Removal Factors for Control
Alternatives
Total Annual Reduction Over ELOC of Particulate
Emissions for Control Alternatives
Secondary Air Pollution Impacts Associated with
the Application of Control Alternatives to
Typical Urea Plants
Annual Energy Requirements for Urea Model Plants
Control Alternatives
Page
5-20
5-21
5-22
5-23
5-24
5-25
5-26
5-26
5-27
5-28
5-29
5-30
5-31
6-2
6-3
6-5
6-7
-------
LIST OF TABLES
(Continued)
Table Page
7-1 Summary of Urea Model Plants and Control Alternatives 7-2
7-2 Specifications for Particulate Control Systems. . 7-5
7-3a Example of Major Equipment Requirements for
Control of Prill Towers 7-6
7-3b Example of Major Equipment Requirements for
Control of Coolers 7-7
7-3c Example of Major Equipment Requirements for
Control of Granulators 7-8
7-4 Purchased Equipment Costs Associated with
Control Options 7-10
7-5 Example of Purchased Equipment Cost Breakdown
on Major Equipment 7-11
7-6 Component Capital Cost Factors for a Wet
Scrubber as a Function of Equipment Cost 7-12
7-7 Capital Costs of Control Alternatives for
Model Plants 7-13
7-8 Bases for Scrubber Annualized Cost Estimates. . . 7-14
7-9 Component Annual ized Costs 7-16
7-10 Net Annual ized Costs for Control Options 7-17
7-11 Net Annualized Costs and Cost Effectiveness
of Control Alternatives for Model Urea
Facilities (Metric Units) 7-18
7-11 Net Annualized Costs and Cost Effectiveness
of Control Alternatives for Model Urea
Facilities (English Units) 7-19
7-12 Capital Costs of Uncontrolled Urea Plants .... 7-21
-------
LIST OF FIGURES
Figure
3-1 Urea Manufacturing 3.3
3-2 Total Recycle Urea Processes 3.9
3-3 Air Swept Falling Film Evaporator 3_H
3-4 Two-Stage Vacuum Evaporator 3_12
3-5 Prill Tower - Nonfluidized Bed 3_13
3-6 Prill Tower - Fluidized Bed 3_14
3-7 Spinning Bucket 3_16
3-8 Multiple Spray Head Arrangement 3_17
3-9 Process Flow Diagram for Prill Tower 3_19
3-10 Drum Granulator 3_23
3-11 Urea Drum Granulation Process 2-25
3-12 Pan Granulator 3_2g
3-13 Process Flow Diagram for Pan Granulator 3-30
3-14 Typical Countercurrent Direct Contact Air Chilled
Rotary Cooler 3_32
4-1 Typical Spray Tower Scrubber 4.3
4-2 Typical Packed Tower Scrubber 4_10
4-3 Typical Mechanically Aided Scrubber 4_12
4-4 Typical Tray Type Scrubber 4_13
4-5 Standard Fractional Efficiency for Tray Type Scrubber. . 4-15
4-6 Effect of Pressure Drop on Tray Type Scrubber
Efficiency 4_16
-------
LIST OF FIGURES
(Continued)
Figure Page
4-7 Typical Entrainment Scrubber 4-17
4-8 Fractional Efficiency of Entrainment Scrubber Used in
the Urea Industry as a Function of Particle Size
and Pressure Drop 4-19
4-9 Typical Fibrous Filter Scrubber 4-20
4-10 Fractional Efficiency of Wetted Fibrous Filter Scrubber. 4-22
4-11 Effect of Pressure Drop on Efficiency of Wetted
Fibrous Filter Scrubber 4-23
4-12 Diagram of a Fabric Filter 4-24
4-13 Particle Size Distribution of Uncontrolled NFB Prill
Tower Exhaust (Plant C) 4-32
4-14 Particle Size Distribution of Uncontrolled NFB Prill
Tower Exhaust (Plant E) 4-33
4-15 Particle Size Distribution of Uncontrolled Prill Tower
Exhaust (Plant F) 4-34
4-16 Histograms of Six Minute Opacity Averages for
Controlled NFB Prill Tower Exhaust (Plant C) 4-35
4-17 Histograms of Six Minute Opacity Averages for
Controlled NFB Prill Tower Exhaust (Plant E) 4-36
4-18 Histograms of Six Minute Opacity Averages for
Controlled NFB Prill Tower Exhaust (Plant D) 4-48
4-19 Particle Size Distribution of Uncontrolled FB Prill
Tower Exhaust (Plant D) 4-39
4-20 Particle Size Distribution of Uncontrolled Cooler
Exhaust (Plant C) 4-42
4-21 Particle Size Distribution of Sub Micron Fraction
Measured at Plant E 4-44
vn
-------
LIST OF FIGURES
(Continued)
Figure
4-22
4-23
4-24
4-25
4-26
5-1
5-2
Variation in Particle Size with Respect to Ambient
Temperature .....
Efficiency of Wetted Fibrous Filter as a Function
of Ambient Temperature
Estimated Airflow Cutback as a Function of Ambient
Temperature
Variation in Controlled Nonfluidized Prill Tower
Emissions with Respect to Ambient Temperature
Emission Levels from Uncontrolled Granulator Exhaust . .
Process Diagrams for Model Plants 1-6
Process Diaqrams for Model Plants 7-10
Page
4-49
4-50
4-52
4-53
4-55
5-3
5-4
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1.0 INTRODUCTION AND SUMMARY
1.1 PURPOSE
The purpose of this document is to present and discuss technical
information on the emissions, control techniques, and costs associated
with control of emissions from processes in the domestic urea industry.
Results of uncontrolled and controlled emissions testing are presented
to quantify uncontrolled emissions and evaluate control device performance.
1.2 SUMMARY
1.2.1 Industry Structure
The domestic urea industry produces urea in both solid and solution
form. Solids are manufactured in two sizes. The smaller size is used
for animal feed supplement. The larger sized solid is used for fertilizer
applications and in the production of plastics and resins. Urea solutions
are combined with other types of nitrogen solutions and used as fertilizers,
There are 47 plants in the United States producing either urea solution
alone or both solution and solids. In 1979 domestic urea production was
7.2 million Mg (9.9 million tons), a 19 percent increase over 1978.
1.2.2 Processes and Emissions
Unit processes in the urea industry include urea solution synthesis,
solution concentration, solids formation (prilling and granulation),
solids cooling, solids screening, solids coating, and bagging and/or
bulk shipping. Uncontrolled particulate emission rates range from
0.00241 kg/Mg of product (0.00482 Ib/ton) for urea solution synthesis
and concentration to 148.8 kg/Mg of product (297.6 Ib/ton) for a solids
producing process (granulation). The most effective control device used
to control urea particulate emissions is a wet scrubber.
1.2.3 Model Plants and Control Alternatives
Model plants were chosen to represent the existing domestic urea
industry. These model plants have production capacities that range from
1-1
-------
182 Mg/day (200 tons/day) to 1090 Mg/day (1200 tons/day). Control
devices that exhibit various levels of removal efficiency were identified
for each source. Removal efficiencies for control devices applied to
the model plants range from 57.9 percent for a spray tower to 99.9 percent
for a wet entrainment scrubber. Several control alternatives were
identified for each model plant. The control alternatives are based
upon combinations of control devices applied to the sources within the
plant. Three control alternatives were identified for prilling plants
and one for granulation plants. Table 1-1 summarizes the control
alternatives and corresponding emission factors for the model plants.
1.2.4 Economic and Environmental Impacts
Table 1-2 presents a summary of impacts on urea product price due
to the application of control alternatives. The increases in product
price range from 2 to 8 percent based on a urea product price of $132/Mg
($120/ton). There are no water quality or solid waste impacts attributable
to the use of wet scrubbers to control emissions. The primary air
quality impact is the reduction in particulate emissions from sources in
the urea industry. These reductions range from 58 to 98 percent for
prill towers and 99.9 percent for granulators. Small secondary air
impacts exist due to increased power plant particulate emissions resulting
from the energy requirements of the control devices. The secondary
impact relative to plant-wide emission reductions range from 1 percent
for a granulation plant to 3 percent for a prilling plant.
1-2
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TABLE 1-1. CONTROL ALTERNATIVES
Model
Pl.mt Plant
No. Configuration
1-3 Nonfluldlzed bed, Agricultural
grade prill production
4-f Fluldlzed bed, Agricultural
grade prill production
7 Nonfluldlzed bed, Feed grade
prill production
8-10 Granulator
Control Alternatives -
Control Emission Factors
Alternatives kg/Hg (Ib/ton)
Sources 1231
Prill Tower 0 + ++ 0.900
Cooler
000 (1.800)
Prill Tower 0 + +t 0.600
(1.200)
Prill Tower 0 + ++ 0.800
(1.600)
Granulator 0 0.115
(0.230)
2
0.385
(0.770)
0.470
(0.930)
0.270
(0.540)
-
3
0.138
(0.276)
0.062
(0.124)
0.036
(0.072)
-
Legend: 0 - ELOC - defined In Chapter 5
+ - Option 1 - defined In Chapter 5
++ - Option 2 - defined 1n Chapter 5
-------
TABLE 1-2. SUMMARY OF CONTROL ALTERNATIVES AND
THEIR EFFECT ON PRODUCT PRICE
Model Plant
No.
1
2
3
4
5
6
7
8
9
10
Size
Mg/D
(tons/0)
181(200)
726(800)
1090(1200)
181(200)
726(800)
1090(1200)
181(200)
363(400)
726(800)
1090(1200)
Effect on Cost of Product $/Mg ($/ton)
Configuration Control Alternative
1
2 3
Nonfluidized prill tower plant 6.35 7.20 10.31
producing agricultural grade (5.77) (6.53) (9.38)
prills.
3.42 4.06 4.93
(3.11) (3.68) (4.48)
2.93 3.68 4.39
(2.66) (3.34) (3.99)
Fluidized bed prill tower 6.62 6.64 9.92
plant producing (6.02) (6.03) (9.02)
agricultural grade prills 3.73 4.79 5.77
(3.39) (4.35) (5.24)
3.64 4.81 5.45
(3.31) (4.36) (4.95)
3.86 3.37 6.43
Prill Tower Plant (3.51) (3.06) (5.85)
producing feed grade prills.
[5.93
(L5.39'
Granulation Plant [6.03"
([5.46:
[6.03=
([5.68"
b a a
' "a
' .a
)
Control alternatives 2 and 3 are not presented for granulation plants.
%
'Values on brackets represent decreases in the product price.
-------
2.0 THE UREA INDUSTRY
This chapter presents a description of the domestic urea industry.
Section 2.1 will present information on the industry history, structure
and growth. Section 2.2 will discuss urea products and end uses.
2.1 INDUSTRY STRUCTURE
The domestic urea industry consists of 47 plants operated by
36 firms. Geographically, the industry production capacity distribution
has shifted during recent years. Prior to 1966, capacity was fairly
evenly distributed throughout the country. However, as of 1979 the
primary concentrations of production capacity lay in the South-central
states and Alaska, which together accounted for 41 percent of the total
domestic capacity. This shift is attributed to the availability of
natural gas supplies (the basic feedstock for urea production) in these
regions.
Of the 36 urea producing firms, three firms account for over 39
percent of the total domestic urea production capacity. Table 2-1
presents a listing of all domestic producers, including their location,
capacity, date of construction and product line. The majority of urea
producers compete in the nitrogen fertilizer market with anhydrous
ammonia, ammonium nitrate, ammonia, nitrogen solutions, and nitric acid.
Urea's share of the domestic nitrogen fertilizer market has been steadily
increasing since 1970. In 1979, solid urea accounted for 12 percent of
the nitrogen fertilizer applied in the United States.
Historically, urea plants have operated at between 68 and 90 percent
of their rated annual production capacity, depending on market conditions.
Between 1966 and 1978 the average capacity utilization was 69.4 percent
while in 1979 industry-wide capacity utilization increased to 90.2
7 "\
percent. ' In 1979, 7.2 million Mg (7.9 million tons) of urea was
produced, a 19 percent increase over the previous year. The projected
2-1
-------
TABLE 2-1. UREA PRODUCERS—PLANTS, LOCATIONS, AND CAPACITIES
Capacity
Company name
Air Proaucts and Chemicals
Inc.
Allied Chemical Corp.
American Cyanamid Co.
Beker Industry Corp.*
Si son Nitrogen Products
(co-owned with Terra
Chemical International)
3oroen, Inc.
CF Industries, Inc.
The Coastal Corp.
Wycon Chemical Co.
Columoia Nitrogen Corp.
Cominco American Ltd.
Camex, Inc.
Enserch Corp.
Nioalc, Inc.
Esaartc, Inc.
Estech General Chemicals
Corp.
Farmland Industries, Inc.
General American Oil Co. of
Texas
Premier Petrochemicals,
subs.
Getty Oil Co.
Hawkeye Chemical Co. ,
subs.
Goodpasture, Inc.
W. R. Grace and Co.
Hercules Inc.
Raiser Aluminum 4 Chemical
Co.
Plant location
Pensacola, FL
Helena, AR
Geismar, LA
Omana, NB
New Orleans, LA
Carlsbad, MM
Woodward, OK
Geismar, LA
Oonaldsonville, LA
Fremont, N8
Olean, NY
Tunis, NC
Tyner, TN
Cheyenne, WY
Augusta, GA
Borger, TX
Kerens, TX
Beaumont, TX
Dodge City, KS
Lawrence , KS
Pasadena, TX
Clinton, IA
Dimitt, TX
Memoni s , TN
Louisiana, MO
Savannan, GA
CIO" MgJ
21
SI
285
127
120
160
104
200
788
16
53
ISO
53
54
359
75
75
45
53
244
54
55
21
317
36
120
(10-1 tons)
23
67
314
140
132
176
114
220
367
IS
75
165
53
59
395
32
32
50
54
263
70
60
23
349
95
132
Form of urea
Solutions
Solutions
Solutions
Solutions
Mel ami ne
Unspecified
Liquid feed
Prills
Solutions, granular
Solutions
Solutions, prills,
liquid feed
Solutions
Solutions
Solutions, prills,
liquid feed
Solutions, prills
Granular, prills
Unspecified
Solutions
Solutions
Solutions, granular,
liquid feed
Pri 1 1 s
Solutions
Solutions
Prills, crystal
Solutions, ureaform
ferti 1 izer
Solutions
Date on
stream
1963
1967
1967
1955
1966
1976
1978
1963
1974
1965
1967
1969
1963
1966
1966
1980
NA
1967
1975
1959
1963
1971
1955
1958
1956
(continued)
Currently snut down.
2-2
-------
TABLE 2-1. (Continued)
Company name
Mississippi Chemical Ca.
N-3en Corporation
01 in Carp.
Phillips Pacific Chemical
Co.
Phillips Petroleun Co.
Seichnold Chemicals
J.R. Simplot Ca.
Standard Oil of CA
Chevron Chemical Co.
Standard Oil of Ohio
Vistron Corp. , subs.
Tennessee Valley Authority
Tarra Chemical
International
Tnad Chemicals
Tyler Corp.
Atlas Powder Corp. ,
3UOS.
Union Oil of California
'J.S, Steel Corp.
/allay Nitrogen Producars
^illiajns Co.
Agrica Chemical Co.
Plant location
Yazoo City, MS
E. OuOuaue, IL
Pryor. OK
Lafca Charles, LA
Pin ley, VA
8eatric», N8
St. Helens, OR
Pocatallo, 10
Fort Madison, IA
Lima, OH
Muscle Shoals, AL
Port Neal , IA
Oonaldsonville, LA
Joplin, MO
3r«a, CA
Kenai , AK.
Cherokee, AL
£1 Cantro, CA
Slytheviile, AR
Oonaldsonville, LA
Verdigris, OK
(IQ-1
127
77
16
164
34
48
93
14
56
200
55
230
-125
57
109
520
70
125
300
205
430
Caoaci ty
Mg) (10J tons)
140
as
is
130
37
53
102
IS
73
220
SO
253
469
74
120
748
77
143
330
226
S23
Form of urea
Solutions, prills
Solutions, prills
Solutions
Prills
Solutions
Solutions
Mostly prills
Solutions
Solutions
Solutions, prills
Solutions, granular
Solutions, granular,
prills, liquia
faed
Prills, .Tie! ami ne
Solutions, prills
Solutions, prills
Granular, prills
Solutions
Solutions, prills,
liquid faed
Granular
Granular
Solutions
Oata on
stream
1359
1371
1970
1366
1965
1365
1367
1374
1980
195S
1372
1367
1963
1361
1965
1969
1962
1963
1375
1368
1375
2-3
-------
demand for urea in 1980 is 7.5 million Mg (8.2 million tons) which would
represent a 4 percent increase in production over 1979.
2.2 UREA PRODUCTS AND END USES
Urea has three basic uses: fertilizer, cattle feed, and as a
component in the manufacture of plastics and resins. Table 2-2 presents
the annual amount of urea used for fertilizer, feed, and plastics and
other applications.
Urea is marketed as a solution or in a variety of solid forms.
Most urea solution is used in fertilizers, with a small amount going to
animal feed supplements. Urea solution is never used alone as a fertilizer.
It is always blended prior to application with another chemical such as
ammonium nitrate or ammonium sulfate. Mixed urea-ammonium nitrate (UAN)
solutions have a number of advantages over pure urea or ammonium nitrate
solutions. UAN solutions are less corrosive than either of the individual
components and do not decompose with time like pure urea solution. Most
importantly, UAN solutions have a lower crystallization temperature than
ammonium nitrate or urea solutions separately, which reduces the likelihood
of a solution salting out during transfer and application. Solution
fertilizers are currently becoming more popular than solid fertilizer
because they are easier to transfer in tank cars and do not generate
dust problems. ' However, solid urea is still in demand for various
applications.
Urea solids are produced as prills, crystals, and granules. A
prill is an air-cooled solid sphere that is produced in two sizes. The
smaller of these, 0.35-1.7 mm (0.014 - 0.066 in) in diameter, is referred
to as feed grade and the larger, 0.5 - 4.0 mm (0.020 - 0.157 in), as
agricultural (or fertilizer) grade urea. Prills are used as a fertilizer,
as a protein supplement in animal feeds, and in plastics manufacturing.
Feed grade urea production has declined since 1960 when 12.9 percent of
total urea production was feed grade urea. By 1978 feed grade urea
represented only 6.7 percent of total urea production. The major urea
based plastics are urea-formaldehyde resins and melamine. The domestic
output of urea for use in the manufacture of plastics has grown steadily
2-4
-------
TABLE 2-2. UREA PRODUCTION BY USE'
103 Mga
1956
1957
1958
1959
1960
1961
1962
1963
1964
iww^
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
Liquid
223
(245)
284
(312)
310
(341)
341
(375)
394
(433)
428
(471)
604
(664)
748
(323)
903
(993)
1,002
(1,102)
1,278
(1,406)
1,182
(1,300)
1,148
(1,263)
1,121
(1,233)
1,221
(1,343)
1,309
(1,440)
1,029
(1,132)
1,336
(1,470)
Ferti 1 i zer
Solid
274
(301)
382
(420)
423
(465)
434
(477)
495
(544)
496
(546)
629
(692)
794
(873)
893
(982)
1,225
(1,239)
1,090
(1,199)
953
(1,048)
1,195
(1,314)
1,321
(1,453)
1,302
(1,432)
1,358
(1,494)
1,394
(2,083)
2,434
(2,677)
Total
134.18
(148.60)
169.19-
(186. 11)
223.64
(246.00)
213.91
(235.30)
497.00
(546.70)
566. 00
(732.60)
733. 00
(806.30)
775.00
(852.50)
389.00
(977.90)
924. 00
(1,016.40)
1,233.00
(1,356.30)
1,542.00
(1,696.20)
1,796.00
(1,975.60)
2,228.00
(2,450.80)
2,368.00
(2,604.80)
2,135.00
(2,348.50)
2,343.00
(2,577.30)
2,442.00
(2,686.20)
2,523.00
(2,775.30)
2,667.00
(2,933.70)
2,923.00
(3,215.30)
3,770.00
(4,147.00)
4,605.00
(5,065.50)
5,236.00
(5,760.00)
Animal
Feed
NA
NA
NA
NA
36
(95)
92
(101)
101
(111)
115
(125)
108
(119)
136
(ISO)
175
(192)
210
(231)
256
(282)
304
(334)
305
(336)
248
(273)
303
(339)
371
(408)
342
(376)
264
(290)
222
(244)
216
(238i
334 h
(367i
342 h
(376)b
Plastics
4 other
NA
NA
NA
NA
33
(91)
78
(36)
32
(90)
101
(HI)
99
(109)
107
(US)
149
(164)
145
(160)
156
(172)
153
(179)
156
(172)
452
(497)
494
(543)
401
(441)
573
(630)
514
(565)
556
(612)
514
(675)
NA
NA
Total
NA
NA
NA
NA
666
(733)
336
(920)
fn £
916
(1,008)
991
(1,090)
1,096
(1,206)
1,167
(1,284)
1,557
(1,713)
1,897
(2,087)
2,208
(2,429)
2,595
(2,964)
2,729
(3,002)
2,835
(3,118)
3,145
(3,460)
3,214
(3,535)
3,438
(3,782)
3,445
(3,790)
3,701
(4,071)
4,600
(5,060)
4,939
(5,433)
6,147
(6,762)
in parentheses are in IQ2 tons.
blncluaes all products other than fertilizer.
Totals not exact due to rounding.
2-5
-------
O
since 1960 at an annual average growth rate of 11.8 percent. Currently,
8 percent of the total urea produced is targeted for uses in plastics,
resins and melamine.
Crystals are formed by the vacuum crystallization and drying of
urea solution. These crystals may be used as is, or remelted for
prilling. The major advantage of crystals is their lower biuret content.
Biuret is a urea decomposition product and a plant poison (see Chapter 3).
Production of agricultural grade urea solids by granulation is on
the increase compared to production by prilling. In granulation, seed
particles are built up to granules by the addition of successive layers
of molten material. Because of the nature of particle buildup, granulation
can produce larger particles with greater abrasion resistance and particles
with two or three times the crushing strength of standard prills.
Another benefit of greater abrasion resistance is the reduction of
solids dusting when the product is conveyed and bulk loaded. Granular
product is not as spherical or as smooth as the prilled product, and
g
small feed grade granules cannot be manufactured using present technology.
However, any of the larger desired product sizes, from fertilizer grade
granules to even larger forestry grade granules can be manufactured.
Large granules are preferred for forestry application because they are
more massive and less likely to be caught in tree branches when being
c
applied from the air.
2-6
-------
2.3 REFERENCES
1. Stanford Research Institute. 1979 Directory of Chemical Producers.
Menlo Park, California, SRI International, 1979.
2. Search, W.J. and R.B. Reznik. (Monsanto Research Corporation.)
Source Assessment: Urea Manfacture. (Prepared for U.S. Environmental
Protection Agency.) Washington, D. C. EPA Publication No. EPA-
600/2-77-107L. November 1977. 94 p.
3. Bridges, J.D. Fertilizer Trends 1979. Muscle Shoals, Alabama,
Tennessee Valley Authority. National Fertilizer Development
Center. January 1980. p. 12.
4. Chemical ProfilerUrea. Chemical Marketing Reporter. _21_8(15):9,31.
October 13, 1980.
5. Trip report. Bornstein, M.I., GCA Corporation, to Noble, E.A.,
EPA:ISB. August 3, 1978. p. 9. Report of Visit to the Tennessee
Valley Authority National Fertilizer Development Center in Muscle
Shoals, Alabama.
6. Harre, E.A. The Outlook for Nitrogen Fertilizers. Tennessee
Valley Authority. Muscle Shoals, Alabama. (Presented at the
Forest Fertilization Conference. Union, Washington. September 25-
27, 1979.) p. 10.
7. Memo from Ramachandran, V., Research Triangle Institute, to
Rader, R., Radian Corporation. January 6, 1981. 6 p. Information
about data stored in Triangle University Computing Center.
8. Reference 1.
9. Reference 2.
2-7
-------
3.0 PROCESSES AND THEIR EMISSIONS
This chapter presents a discussion of the processes and emissions
found in the urea industry. Section 3.1 will present the urea process
chemistry, a process overview, a description of the types of urea
plants, and emissions overview. Section 3.2 will discuss in detail the
individual urea production processes and their emissions.
3.1 INTRODUCTION
3.1.1 Process Chemistry
Urea (also known as carbamide or carbonyl diamide) CO(NH2)_ is an
organic, natural gas based chemical. The primary feedstocks of urea are
ammonia and carbon dioxide. Urea is formed by reacting ammonia and
carbon dioxide at 448-473 K (347-392°F) and 19.2-23.2 MPa (2,800-3,400
psi) to form ammonium carbamate. The carbamate is then dehydrated to
form urea and water. These reactions are represented by the following
equations.
2NH3 + C02 - *-NH4C02NH2 (1)
(2)
The carbamate formation step (1) is exothermic, releasing 150-160 kJ
(64500-68800 Btu) per mole of ammonium carbamate formed. This reaction
is favored by high pressures. The dehydration step (2) is endothermic,
consuming 32 kJ (13800 BTU) per mole of urea formed. This step is
favored by high temperatures.
Urea, as a solid, is a colorless crystal with a melting point of
406 K (271°F) and a specific gravity of 1.335 at 293 K (68°F).2'3
Aqueous urea solutions begin to decompose at 333 K (140°F) to buiret and
ammonia. Dry urea, however, is stable below 403K (266°F). Above this
temperature dry urea decomposes to buiret and ammonia according to the
following reaction.
3-1
-------
2CO(NH2)2 *-(NH2CO)2 NH + NH3
Above 443K (338°F) the primary decomposition products of urea are
cyanuric acid (HNCO)7 and ammonia.
O
The biuret concentration in urea must be monitored, as it is a
plant poison, and is also undesirable in industrial (plastics) applications,
Biuret concentrations in urea solids are 0.1 percent or less in crystals,
0.3 percent in solids formed from crystal remelt, and 1.0 percent in
solids formed from concentrated urea solution.
3.1.2 Process Overview
The process for manufacturing urea involves a combination of up to
seven major unit operations. The basic arrangement of these operations
is shown in the block diagram given in Figure 3-1. These major operations
are:
(1) solution synthesis (solution formation)
(2) solution concentration
(3) solids formation
- prilling
- granulation
(4) solids cooling
(5) solids screening
(6) solids coating
(7} bagging and/or bulk shipping
The combinations of processing steps are determined by the desired
end products. Plants producing urea solutions alone are comprised of
only the first and seventh unit operations, solution formation and bulk
shipping. Facilities producing solid urea employ these two operations
and various combinations of the remaining five operations, depending
upon the specific end product being produced.
3.1.3 Types of Urea Plants
All urea plants produce an aqueous urea solution as depicted in the
process diagram shown in Figure 3-1. In these plants, ammonia and
carbon dioxide are reacted to form ammonium carbamate. The carbamate is
then dehydrated to yield a 70 to 77 percent aqueous urea solution. The
3-2
-------
AWONIA
CARBON
DIOXIDE
processes are optional dependlnn on Individual manufacturing practices.
Figure 3-1. Urea manufacturing.
-------
solution can be sold as an ingredient in nitrogen solution fertilizers
or can be further concentrated to produce solid urea. There are three
methods of concentrating urea solution: vacuum evaporation, atmospheric
evaporation and crystallization. Vacuum and atmospheric evaporation
produce a urea melt containing from 99 to 99.9 percent urea at a nominal
temperature of 413.7K (285°F). Crystallization is used primarily when
product requirements dictate an extremely low biuret concentration in
the final product.
Urea solids are produced from the urea melt by two basic methods:
prilling and granulation. In prilling there are two types of prill
towers: fluidized bed and nonfluidized bed. Each of these is capable
of producing both agricultural grade and feed grade urea prills. The
major difference between these towers is that a separate solids cooling
operation may be required when producing agricultural grade prills in a
nonfluidized bed prill tower. The fluidized bed supplies the required
cooling for agricultural prills in a fluidized bed prill tower. However,
because the small feed grade prills exhibit better heat transfer properties,
additional cooling external to the nonfluidized bed tower is not required.
Prill towers are described in detail in Section 3.2.4.
The other methods of solids formation used in the urea industry are
drum and pan granulation. In drum granulation, solids are built up in
layers on seed granules in a rotating drum granulator/cooler approx-
imately 14 feet in diameter. Pan granulators also form the product in a
layering process, but the equipment used is different from the drum
granulator. There is only one pilot scale pan granulator operating in
the domestic industry, providing 61,000 Mg/year (67,000 tons/year) of
urea granules. Details of the granulation process are presented in
Section 3.2.5.
3.1.4 Industry Emissions Overview
Emissions from urea processes include particulate matter, ammonia
and formaldehyde. Table 3-1 presents uncontrolled emission factors for
each of the major processes in the urea industry. Table 3-2 provides an
3-4
-------
TABLE 3-1. UNCONTROLLED EMISSIONS FROM UREA FACILITIES3'5
CO
I
en
Process
Solution Formation
and Concentration
Solution Formation
and Concentration
Solution Formation
and Concentration
Drum Granulation
Drum Granulation
Non-Flu1d1zed Bed Prill Tower
(Agricultural Grade)
Fluidized Bed Prill Tower
(Feed Grade)
Flu id i zed Bed Prill Tower
(Agricultural Grade)
Rotary Drum Cooler
Plant
A
B
D
A
B
E
D
D
C
Partlculate
kg/Hg (lb/ton)
0.00241
0.0150
0.0052
148.8
63.6
1.90
1.80
3.12
3.72
(0.00482)
(0.0317)
(0.0104)
(297.6)
(127.2)
(3.80)
(3.60)
(6.23)
(7.45)
Ammonl a
kg/Mg (lb/ton)
12.89
4.01
14.40 ,
1.08
1.07
0.433
2.07
1.42
0.0255
(25.77)
(8.02)
(28.80)
(2.15)
(2.13)
(0.865)
(4.14)
(2.91)
(0.051)
Formaldehyde
kg/Mg (lb/ton)
.
_
-
0.00359 (0.0072)
0.00555 (0.0111)
-
0.0020 (0.0040)
0.0095 (0.0190)
-
All data are from EPA test results (see Appendix A).
-------
estimate of the total annual emissions from sources in typical urea
plants based on the emission factors in Table 3-1.
Ammonia is emitted during urea synthesis (solution production) and
solids production processes. Ammonia emissions range from 14.40 kg/Mg
(28.80 Ib/ton) for synthesis processes to 0.0255 kg/Mg (0.0051 Ib/ton)
for a rotary drum prill cooler. A more detailed list of ammonia emission
data are presented in Appendix A.
Formaldehyde has been added to the urea melt in recent years for
the purpose of reducing urea dust emissions and to prevent solid urea
product from caking during storage. Formaldehyde is added to the urea
melt in concentrations of 0.5 percent or less prior to solids formation.
A further discussion on additives is contained in Section 3.2.8. The
use of formaldehyde as an additive has resulted in formaldehyde emissions
which range from 0.0095 kg/Mg (0.0190 Ib/ton) of urea produced for a
fluidized bed prill tower producing agricultural grade urea, to 0.0020
kg/Mg (0.0040 Ib/ton) of urea produced for a fluidized bed prill tower
producing feed grade urea solids. A more detailed list of formaldehyde
emissions is included in Appendix A.
Particulate matter is the primary emission being addressed in this
report. Table 3-1 includes a summary of uncontrolled particulate
emissions form all urea processes. These particulate emissions range
from 148.8 kg/Mg (297.6 Ib/ton) of urea produced for a rotary drum
granulator to 0.00241 kg/Mg (0.00482 Ib/ton) of urea produced for a
synthesis process. A more detailed list of particulate emissions is
presented in Appendix A.
In the following section each of the processing steps described
earlier is reviewed. Several of these processes are comparatively small
particulate emitters and/or are not expected to be built in the future
because of changing production technology. For these processes, the
sections will provide a brief description of the actual process operations.
More detailed descriptions are provided for solids production and
cooling processes which are large particulate emitters.
3-6
-------
TABLE 3-2. ESTIMATED ANNUAL UNCONTROLLED EMISSIONS FROM
PROCESSES IN TYPICAL UREA PLANTS3 Mg (Tons)
Process
Solution Formation
and Concentration
Solution Formation
and Concentration
Solution Fomation
and Concentration
Drum Granulation
Drum Sranulation
Drum Granulation
Non-Fluidized Bed Prill
Tower (Agricultural Grade)
Non-Fluidized Bed Prill
Tower (Agricultural Grade)
Non-Fluidized Bed Prill
Tower (Agricultural Gride)
Non-Ruidized Bed Prill
Tower (Agricultural Grade)
Fluidi zed 3ed Prill Tower
(Agricultural Grade)
Fluidized Bed Prill
(Agricultural Grade)
Fluidized Bed Prill
(Agricultural Grade)
Fluidized Bed Prill
(Agricultural Grade)
Fluidized Bed Prill
(Feed Grade)
Fluidized Bed Prill
(Feed Grade)
Fluidized Bed Prill
(Feed Grade)
Fluidized Bed Prill
(Feed Grade)
Rotary Drum Cooler
Rotary Drum Cool er
Rotary Drum Cooler
Rotary Drum Cooler
Tower
Tower
Tower
Tower
Tower
Tower
Tower
Plant
Mg/day
383
727
1090
363
727
1090
182
363
727
1090
182
353
727
1090
182
363
727
1090
182
363
727
1090
Capacity
(tons/day)
(400)
(800)
(1200)
(400)
(800)
(1200)
(200)
(400)
(1800)
(1200)
(200)
(400)
(800)
(1200)
(200)
(400)
(800)
(1200)
(200)
(400)
(800)
(1200)
Particulate
0.
0.
1.
342
686
028
11304
22608
33911
103.
207.
415.
623.
162.
324.
487.
730.
91.
183.
367.
550.
213.
426.
8S2.
1279.
3
7
5
3
4
7
1
6
8
6
2
3
2
4
8
2
(0.3771
(0.755)
(1.132)
(12499)
(24898)
(37348)
(114.4)
(228.8)
(457.5)
(686.3)
(178.3)
(357.5)
(536.4)
(804.5)
(101.1)
(202.3)
(404.5)
(606.8)
(234.3)
(469.6)
(939.1)
(1408.7)
Ammonia
1142
2284
3427
116.9
233.9
350.9
23.50
44.2
38.5
141.3
76.0
152.9
304.0
456.0
108.5
217.0
434.0
651.0
1.39
2.73
5.55
8.33
(1258)
(2516)
(3773)
(128.8)
(257.7)
(386.5)
(26.04)
(52.08)
(104.16)
(156.24)
(83.7)
(167.4)
(334.7)
(502.1)
(119.5)
(239.0)
(478.0)
(717.0)
(1-54)
(3.07)
(6.14)
(9.21)
Formaldehyde
b
b
b
0.00831
0.0166
0. 0249
c
c
c
c
0.492
0.984
1.968
2.953
0.104
0.208
0.416
0.621
c
c
C
c
(0.
(0.
(0.
(0.
(1.
(2.
(3.
(0.
00915)
0183)
0275)
c
c
c
c
542)
0836)
167)
251)
114)
(0.229)
(0.
(0.
4581
686)
c
c
c
c
Plant capacities are presented for comparison purposes only and do
not necessarily represent the actual capacity of the tested process.
'b. Formaldehyde is introduced to the melt after solution formation
and concentration processes.
c. Not available.
3-7
-------
3.2 DESCRIPTION OF PROCESSES AND EMISSIONS
3.2.1 Synthesis Processes
There are numerous process designs for producing urea solution.
These designs fall into 3 categories, they are once-through processes,
partial-recycle processes, and total recycle processes.
The older processes are the once-through and partial-recycle
processes, dating back to the early 1950's. These processes represent
less than 25 percent of current domestic urea production capacity. The
once-through process employs a reactor and a carbamate decomposer. The
decomposer separates urea solution from a stream containing ammonia,
carbon dioxide, and water. This ancillary stream is generally sent to
another fertilizer-producing plant. The partial-recycle process provides
a small refinement in that excess ammonia from the urea reactor is
recovered and recycled to the reactor. Ammonia excesses as large as 200
percent are used to boost urea yields up to 80 percent.
The total recycle process is the most widely used of the basic
processes since it provides the benefits of higher yields and lower
energy consumption. Major designers of urea synthesis plants have three
types of total recycle process: (1) processes in which decomposed
carbamate gases are separated and recycled to the reactor (Figure 3-2a);
(2) processes in which carbamate solution is recycled (Figure 3-2b); and
(3) processes in which both gas and liquid recycling is used (Figure 3-2c).
At least ten major companies provide designs within these total recycle
o
process classifications.
Emission sources from synthesis processes are typically noncondensable
vent streams from ammonium carbamate decomposers and separators. Emissions
from synthesis processes are generally combined with emissions from the
solution concentration process. Results of EPA testing on these emissions
are presented in Table 3-1 and Appendix A. Based on EPA testing,
combined particulate emissions from urea synthesis and concentration are
small compared with particulate emissions from a typical solids producing
urea plant. For this reason, emissions from synthesis processes will
not be considered further in this report.
3-8
-------
GAS RECYCLE
1
L
j
K
REACTOR
T
1
1
f
DECOMPOSER
^ UREA
SOLUTION
FEED**—
A. Basic gas recycle process
CARBAMATE RECYCLE
J,
>^
REACTOR
CONDENSER
i
i GASES
SEPARATOR
FEED
B. Basic liquid recycle process
r
NH3 RECYCLE
1
ADDITIONAL
LIQUID
UREA
SOLUTION
1
>J
REACTOR
SEPARATOR
,
DECOMPOSER
i
1
L
UREA
SOLUTION
FEED ~L -rt-
CARBAMATE RECYCLE
C. Basic gas / liquid recycle process
PRODUCT-CONTAINING STREAMS
RECYCLE, FEED, OR OTHER ANCILLARY STREAMS
Figure 3-2. Total recycle urea processes.q
3-9
-------
3.2.2 Solution Concentration
The 70 to 77 percent urea solution resulting from the synthesis
process must be concentrated if a solid urea product is desired. The
method of concentration depends upon the level of biuret impurity
allowable in the end product. For low biuret urea, solution concen-
tration is effected by means of continuous crystallization in an atmos-
pheric or vacuum crystal!izer. The solution is concentrated at moderate
temperatures until urea is crystallized from solution. The crystals are
separated from solution and are dried as a product or remelted for
further processing. Vacuum is often developed by use of steam ejectors.
At present, only five manufacturing plants employ crystallization, and
at least one facility has eliminated the crystallization process. s11
Solution concentration to greater than 99 percent urea is more
often accomplished by means of single or double stage evaporation.
Evaporators operating at atmospheric pressure are commonly of the thin
film or falling film variety as shown in Figure 3-3. Newer processes
employ vacuum evaporators, typically of the thermosiphon and forced
circulation design as illustrated in Figure 3-4. These evaporators
operate at slightly higher temperatures than the crystallization process
and provide a nearly pure urea melt to the solids formation process.
Again, vacuum is provided by means of steam ejectors. >1»
Noncondensable emissions from solution concentration processes are
often combined with emissions from the synthesis process and vented in a
common stack. Particulate emissions from concentration processes are
small compared to those from other plant processes. For this reason,
emissions from concentration processes will not be discussed further in
this report.
3.2.3 Prilling
Prilling is a process by which solidsnearly spherical particles are
produced from molten urea. Molten urea is sprayed from a head tank into
the top of a rectangular or circular tower (See Figures 3-5 and 3-6).
As the droplets fall through a countercurrent air flow, they are cooled
3-10
-------
AIR AND WATER
VAPOR OUT
SOLUTION IN
STEAM
AMBIENT
AIR
STEAM
CONDENSATE
AIR
HEATER
FALLING
FILM
EVAPORATOR
CONDENSATE
AIR
»• CONCENTRATED
SOLUTION
OUT
Figure 3-3. Air swept falling film evaporator.
3-11
-------
STEAM
EJECTOR
STEAM
CO
»—*
t\5
3TEAM_
COMPENSATE
INERT
VENT
STEAM
SOLUTION 1H
URC*
CONOCNSATE
RETURNED TO
PROCESS
COMPENSATE
STEAM
EJECTOR
STEAM
99.0-99.8 X
UREA
CONCENTRATED UREA
SOLUTION
1*1 STACC
2»d STAGE
Figure 3-4. Two-stage vacuum evaporator.
-------
GRATED
FLOOR
AIR
OUTLET
AIR
OUTLET
INDUCED
DRAFT FANS
CONVEYOR
HEAD TANK
SPRAY AREA (SPRAY
HEADS OR SPINNING BUCKET)
PRILLS
FORCED
~> DRAFT FANS
70-2056-1
Figure 3-5. Prill tower - nonfluidized bed.
3-13
-------
AIR
OUTLET
AIR
OUTLET
INDUCED
DRAFT FANS
GRATED
FLOOR
AIR ,
INLET y
PRODUCT
OUT
HEAD TANK
SPRAY AREA (SPRAY
HEADS OR SPINNING BUCKET)
FLUIDIZED
BED COOLER
AIR BLOWER
70-2057-1
Figure 3-6. Prill tower fluidized bed.
3-14
-------
and solidify into near-spherical particles. The solids are collected at
the bottom of the tower for further processing.
Prill towers typically range from 33.5 meters (110 feet) to 64
meters (210 feet) in height. Cross sectional areas range from 29.2
square meters (314 square feet) to 190 square meters (2040 square feet).
The height and cross sectional area of a prill tower depend upon prilling
rate, product grade produced and the amount of cooling required. Molten
urea between 99.5 and 99.8 percent in concentration is sprayed into the
prill tower at about 413K (284°F) by either a single spinning bucket
(see Figure 3-7) or a spray head arrangement (see Figure 3-8).
Natural, forced or induced draft may be used to provide air flow
through the tower. The airflow rate for cooling of the prills depends
upon ambient temperature and humidity, prilling rate and type of prills
being produced. If the tower incorporates a fluidized bed cooler, the
blower used to suspend the prill bed supplies air to the main body of
the tower as well.
Uncontrolled emission rates from prill towers may be affected by
the following factors:
(1) product grade being produced (agricultural grade or
feed grade)
(2) air flow rate through the tower
(3) type of tower bed
(4) ambient air conditions and
(5) melt spray conditions
These factors are described in this section.
Two different size prills are produced by industry: feed grade and
agricultural grade. The hole diameter in the sprayhead or bucket
determines the size of the prill being produced, which in turn deter-
mines the airflow rate required for cooling in the tower. Generally, 60
to 70 percent lower airflow rates are required when smaller sized feed
grade urea is being produced. The smaller particle size results in
better heat transfer because of the larger surface area per unit volume
of urea. Although grain loadings are higher in the exhaust streams
3-15
-------
MELT FROM
HEADTAMK
PERFORATED
BUCKET
ROTATION
BUCKET MAY BE CONICAL SHAPE.
HEADTANK
SPINNING
BUCKET
PRILL
TOWER
70-2040-1
Figure 3-7. Spinning bucket.
3-16
-------
HEAD TANK
CONTAINING
MELT
MULTIPLE
SPRAY HEADS
70-2045-1
Figure 3-8. Multiple spray head arrangement.
3-17
-------
from feed grade prill towers, the total mass emissions per unit of feed
grade prill production may be lower because of the lower airflows.
Two different types of towers may be used to produce prills:
fluidized and nonfluidized bed (see Figure 3-9). Fluidized bed prill
towers incorporate a fluid bed cooler at the bottom of the prill tower,
which provides additional cooling of agricultural grade prills without
using an auxiliary rotary drum cooler. Higher airflow rates are used to
suspend (fluidize) the prill bed and to provide supplementary cooling.
The advantage of having a fluidized bed cooler at the bottom of tower is
that the purchase of an additional large piece of equipment (a rotary
drum cooler) is not necessary. The disadvantages of this type of tower
are: (1) a large blower is required to suspend the prills at the bottom
of the tower; and (2) if the tower is also designed to produce feed
grade prills, the additional cooling provided by the fluidized bed is
10
more than required for proper solidification.
Nonfluidized bed towers may use an additional rotary drum cooler to
provide the necessary cooling during production of agricultural grade
prills. Alternately, prill tower height or prill tower air velocity
could be increased. Prills collected at the bottom of nonfluidized bed
towers are raked onto conveying belts for transport to the rotary drum
cooler or storage. If a nonfluidized bed prill tower is also designed
to produce feed grade prills, the rotary drum cooler is bypassed during
the production of feed grade prills because the prill tower alone supplies
sufficient cooling (see Figure 3-9). The advantages of a nonfluidized
bed prill tower are: (1) airflow rates through the tower are generally
lower than through a fluidized bed prill tower by as much as 20 percent
(see Appendix A) and thus entrapment is reduced and (2) the cooler can
be bypassed when making feed grade prills. The major disadvantage is
that the production of agricultural grade prills usually requires the
addition of a rotary drum cooler.
3-18
-------
CO
I
AIR OUTLETS
AIR
INLET
'• AIR
, INLET
PRODUCT
SCREENS
OFFSIZE RECYCLE
NONFLUIDIZED BED PRILL TOWER
AIROUTLEIS
FLUIDIZED BED PRILL TOWER
FERTILIZER
GRADE
COOLER
FEEDGRAOE
NH-,5 »
C02S ft.
SOLUTION
CONCENTRATION
AIR
INLET
.
A
f «
AIR
INLET
1 !
1 J
FI IIIDIZED JT • • . /
K. BAGGING
^_ BULK
BED COOLER \ i '/ '
..0 X"^
£ 1_ I
INLET1 \J
BLOWER
OPFSIZE RECYCLE
|
LOADING
. BAGGING
BULK
' LOADING
70 2058 2
Figure 3-9. Process flow diagram for prill tower.
-------
Ambient air conditions can affect prill tower emissions. The
ambient air temperature determines the required airflow rate through the
tower. Theoretically, the required winter airflow rate is approximately
60 percent of that needed during summer operation. Ambient humidity can
also affect prill tower emissions. If humidity is high, airflow rates
must be adjusted. Higher airflow rates, in general, result in higher
emissions, as noted for fluidized bed prill towers.
Data supplied by industry indicates the particle size distribution
iq
of prill tower emissions is affected by ambient temperature. It
appears that as the falling molten urea droplet is cooled by the tower
airflow, urea is vaporized from the surface of the solidifying prill.
This urea vapor then condenses in the cold tower airflow to form small
diameter particles. Therefore, during colder weather the size distribution
19
shifts toward smaller particles. Although it is reported1 that uncontrolled
emissions are reduced under these conditions, the grain loading remains
constant due to the reduction in tower airflow. Additional data concerning
this shift and its affect on control device performance is presented in
Section 4 of Chapter 4.
Melt spray conditions can also affect prill tower emissions.
Theoretically, higher melt temperatures result in higher emission rates
due to the increase in surface vapor pressure and associated increase in
9D
fuming. In addition, an increase in melt spray pressure could result
in higher emissions due to increased atomization of the spray stream.
Uncontrolled particulate emission rates from fluidized bed prill
towers are higher than those from nonfluidized bed prill towers for
agricultural grade prills, and approximately equal for feed grade prills.
Emission testing was conducted by EPA on a new, large fluidized bed
prill tower facility during the production of feed grade and agricultural
grade prills. Airflow rates during testing were within normal operating
limits and the melt temperature to the sprayheads did not vary more than
3K (6°F). EPA emission testing on a nonfluidized bed tower was conducted
during agricultural grade production only. The nonfluidized bed prill
tower tested was an older tower designed for lower production capacities.
3-20
-------
Participate emissions as measured during EPA testing from a
fluidized bed tower producing feed grade prills were 1.80 kg/Mg (3.60
Ib/ton) of product, "articulate emissions measured during EPA testing
during the production of agricultural grade prills were 3.12 kg/Mg (6.23
Ib/ton) of product from a fluidized bed prill tower and 1.90 kg/Mg (3.80
Ib/ton) of product from a nonfluidized bed prill tower. Table 3-3
presents data for tests of uncontrolled emissions from nonfluidized bed
prill towers. Industry test data shows that uncontrolled emissions from
a nonfluidized prill tower are slightly greater (13 percent) during feed
grade production than uncontrolled emissions during agricultural grade
production. However, due to differences in test methods and difficulties
involved in measuring emissions from prill towers (see Chapter 5), this
data may be misleading. Particulate emissions for a nonfluidized bed
prill tower producing feed grade prills have not been tested by EPA.
3.2.4 Granulation
Granulation has become the more popular means of producing solid
urea for fertilizer uses. There are two methods currently being used to
produce urea granules: drum granulation and pan granulation. Each of
these processes are described in the following sections.
3.2.4.1 Drum Granulation. With one exception, all drum granulators
operating in the United States are manufactured by one company and are
essentially similar in design and operation. Presently, 18 of these
granulators operate at five different urea plants in the United States.
The production rate of each granulator is approximately 363 Mg/day (400
tons/day). The one exception is a larger drum granulator designed to
produce 773 Mg/day (850 tons/day).
The drum granulator (see Figure 3-10) consists of a rotating horizontal
cylinder about 4.3m (14 ft) in diameter divided by a retaining dam into
two sections, the granulating section and the cooling section. Both
sections have lifting flights welded to the wall. A p^'pe running
axially near the center of the granulating section emits a fine spray of
liquid urea (including formaldehyde additive if used) in an upward
direction. Seed urea particles are fed into the drum at the granulation
end. As the drum rotates, the lifting flights pick up the urea seed
3-21
-------
TABLE 3-3. UNCONTROLLED UREA PARTICULATE EMISSION TESTS FOR NONFLUIDIZED BED PRILL TOWERS
21
CO
ro
ro
Plant
F
G
II
'
J
K
C
L
E
Product
Type
AG
FG
AG
AG
AG
AG
FG
AG
AG
AG
Capacity
Mij/day
(TPD)
199.6
(219.6)
198.2
(218)
818.2
(900)
236.4
(260)
227.3
(250)
500
(550)
218.2
(240)
345
(380)
409
(450)
264.8
(291.3)
Air, Flow
Nn /s
(1000 DSCFM)
42.9
(90.9)
9.1
(19.2)
143.0
(303)
85.0
(180)
51
(108)
122.7
(260)
3fi. 2
(80.9)
G r* j n
Loading
g/lta
(gr/DSCFM)
0.0822
(0.0359)
0.443
(0.1935)
0.0295
(0.0129)
0.0456
(0.0199)
0.0544
(0.0238)
0.0689
(0.0301)
0.1522
(0.0665)
Emission
Rate
B/s
(Ib/hr)
3.53
(28.0)
4.02
(31.9)
4.22
(33.5)
2.86
(22.7)
1.02
(8.13)
3.87
(30.71)
4.05
(32.18)
2.77
(22.0)
8.44
(67.1)
5.81
(46.1)
Emission
Factor
kq/Mg
(Ib/ton)
1.53
(3.06)
1.76
(3.51)
0.52
(1.04)
1.05
0.39
(0.78)
0.67
(1-34)
1.61
(3.22)
0.70
(1.39)
1.79
(3.58)
1.9
(3.8)
Temperature Percent
K Moisture
("F) in air
325
(126)
367
(209)
336
(145) 2.05
312
(102) 1.18
308
(95) 1.84
311 1.07
(101)
Data
Source
Industry
Industry
Industry
Industry
Industry
Industry
Industry
Industry
Industry
(PA
-------
SEED UREA
PARTICLES
EXHAUSTAIR
TO SCRUBBER
CONCENTRATED
UREA SOLUTION
LIFTING FLIGHTS
ROTATING DRUM
UREA
SPRAY
RETAINING
DAM
BED OF UREA
GRANULES
COOLING
AIR
PRODUCT
70-2046-1
Figure 3-10. Drum granulator.
22
3-23
-------
particles and shower these particles down through the urea spray. As
the particles fall and roll, they become coated with molten urea.
Particles gradually build up to product size by addition of successive
layers of liquid, which solidify to give the granule an onion-skin-like
(concentrically layered) structure.
Particles in the granule bed will tend to segregate according to
size, the smaller granules of urea settle to the bottom to be picked up
by the lifting flights. The drum operates at a slight angle and material
migrates by gravity towards the cooling section. Larger particles at
the top of the granule bed pass over the retaining dam into the cooling
section.
Throughout this operation granules are cooled with a countercurrent
flow of air. An airflow velocity of 1.2 meter/sec (4.0 ft/sec) is used
to minimize seed entrainment and disturbance of the fine melt spray.
The cooling air, at this velocity, is chilled to an inlet temperature of
about 283K (50°F) and has an exit temperature of about 358K (185°F).24'25
Urea spray in the granulating section is held at approximately 413K
pc
(285°F), but granules exiting the cooling section are approximately
310K (104°F).27 Cooled granules (Figure 3-11) are removed from the
cooling section and undersized particles are separated and recycled as
seed material. Oversize granules are either crushed and recycled as
seed, dissolved and returned to the solution process, or both. The
OQ
typical recycle to product ratio for a drum granulator is 2:1.
Cooling air passing through the drum granulator entrains approximately
9Q
10-20 percent of the product. This air stream is controlled with a
wet scrubber which is standard process equipment on all drum granulators.
Emission rates from drum granulators may be affected by the following
31
parameters:
1. Number, Design and Location of lifting flights
2. Airflow rates through the drum
3. Melt spray pressure
4. Dam height
3-24
-------
CO
ro
en
CONDENSATE FROM
UREA SOLUTION PLANT
WET
SCRUBBER
^SCRUBBER LIQUOR
TO UREA SOLUTION PLANT
UREA MELT
'1
I
AIR OUT
K'
5|
tl
X
EXHAUSTER STACK
/TV
GRANULATOR
PRODUCT
ELEVATOR
SCREEN
CRUSHER
CONVEYOR
TO STORAGE
Figure 3-11. Urea drum granulation process.
30
-------
5. Bed temperature
6. Recycle rate of seed material
7. Product size.
8. Rotation rate of the drum
The number, design and location of lifting flights directly affect
the emission rate. Flights lift and drop granules through the moving
air stream to cool the particles. When flights are located close to the
air exit of the granulator, fine particles are entrained in the air
stream leaving the granulator. Modifications have been made to many
existing drum granulators to change the size and/or shape of the lifting
flights, and to remove lifting flights at the air discharge end of the
granulator because of excessive entrainment. This modification is also
32
being made on new installations.
Air velocities through the drum have been reported as high as 1.8
meters/sec (7 ft/sec). A greater air velocity will result in increased
entrainment of small particles in the drum granulator and a subsequent
increase in emissions.
The pressure of the melt at the spray nozzles is maintained within
a range of about 2.5 - 3.8 kPa (10-15 psig). Lower pressures cause
the granules to take the shape of popcorn and higher pressures cause an
35
increase in fine granules, which may increase emissions.
The dam at the center of the granulator is used to separate the
granulation zone and the cooling zone. Changing its height will result
in changes in bed temperature, which could affect emission rates. The
dam height is set by the manufacturer and is not normally changed.
The bed temperature in the granulation zone is reported to be
critical. Only a relatively narrow temperature range can be tolerated.
If the bed temperature drops too low, the granules will agglomerate. If
the bed temperature is increased significantly and maintained for several
38
hours, the bed will turn to dust and emissions will increase.
3-26
-------
The recycle rate of seed material affects the bed temperature and
therefore the emission rate. An increase in seed material recycle rate
will cool the bed, while a decrease will raise the bed temperature.
As mentioned previously, increased bed temperature results in increased
particulate emissions.
Drum granulators have an advantage over prill towers in that they
are capable of producing very large particles without difficulty.
Granulators also require less air for operation than do prill towers. A
major disadvantage of granulators is their inability to produce the
smaller feed grade granules economically. To produce smaller granules,
the drum must be operated at a higher seed particle recycle rate. It
has been reported that although the increase in seed material results in
a lower bed temperature, the corresponding increase in fines in the
on
granulator causes a higher emission rate.
Increasing the rotation rate of the drum may increase entrainment
of urea in the airstream, with a corresponding increase in the loading
of urea to the scrubber. However, once set by the manufacturer the
rotation rate of the drum is not normally changed. The original granulator
design of the granulators called for the drums to rotate at 9 rpm. But
because of excessive wear, rotation rates have been decreased to 6 rpm,
with no apparent effect on product quality.
As previously stated, most granulators are a standard size and are
operated in the same way with many of the parameters affecting emissions
fixed by granulator design. Uncontrolled emissions from drum granulators
were determined at two different plants. The average particulate
emission rate from each of these tested facilities were 63.6 and 148.8
kg/Mg (127.2 and 297.6 Ibs/ton) of product. The granulators tested
were of the same design. Airflow rates, melt temperatures, and melt
pressures were within normal operating limits during EPA testing.
3.2.4.2 Pan Granulation. The pan granulation process operates on
the same principle as the drum granulator, forming granules by adding
successive layers of molten urea to seed particles. The equipment,
however, is quite different. It consists of a large, tilted rotating
3-27
-------
circular pan (see Figure 3-12). Seed material deposited near the top of
the pan along with fine particles carried up by the rotating pan, fall
through a fine spray of liquid urea. The newly sprayad particles drop
to the bottom of the pan. As in the case of the drum granulator, smaller
particles tend to sift down toward the bottom of the granule bed on the
lower part of the pan. The larger granules spill over the edge of the
pan onto a conveyor belt.
Pan granulation is a fairly recent development in urea processing
and has yet to gain widespread use. It is still in the pilot plant
stage with only one existing pan granulator in operation in the U.S.
(see Figure 3-13). The pan granulator yields a product which is less
spherical than either drum granules or prills and not quite as hard as a
granule produced by a drum granulator. Pan granulation also tends to
have a larger recycle to product ratio, as most of the required cooling
in the pan is accomplished through heat absortion by the cooled recycle
seed material. This mode of cooling is necessary since the air flowrate
is only 20 percent of a drum granulator1s air flowrate. '
The pan granulator operates with an optimum bed temperature between
377K and 380K (220°F to 225°F).44 The temperature of recycled seed
material is approximately 343K (158°F).45 The urea solution ( 99.0
percent urea) is kept at approximately 413K (285°F) to assure even
coating of particles before crystallization occurs. The recycle to
product ratio will generally fall between 2:1 and 3:1.
The recycled material serves to cool the granule bed and maintains
the desired bed temperature. A decrease in recycle ratio will result in
an increase in bed temperature.
The pan granulator is followed by two rotary drum coolers. All of
the material leaving the first cooler is screened. The oversized
stream is either redissolved and returned to the solution concentration
steps, or crushed and returned to the pan with the undersized material.
The amount of crushed material used as seed is held to a minimum, as use
of this material leads to the formation of agglomerates and weak granules.
This recycle stream to the pan contributes to the cooling of the bed
3-28
-------
SPRAY
AREA COVERED
BY SOLUTION SPRAYS
PAN ROTATION
RECYCLE
ENTERS HERE
LARGE GRANULES
LEAVE PAN HERE
Figure 3-12. Pan granulator.
3-29
-------
CO
oo
o
SOLUTION
FORMATION
AND
CONCENTRATION
PAN GRANULATOR
COOLER
1
COOLER
BAGGING
BULK
LOADING
Figure 3-13. Process flow diagram for pan granulator.
-------
particles as noted previously. Product size urea is sent to the second
cooler and then conveyed to the warehouse for shipment.
The advantage of the pan granulator over the drum granulator is
that the airflow rate required for cooling is approximately one fifth of
that required for the drum granulator. Although the existing plant
(which is still experimental) uses two coolers, a new plant could be
designed with only one cooler thus reducing the total system airflow
48
needed for cooling.
Test data on the pan granulator cannot be directly correlated to
EPA test data because of differences in test methods. However, uncontrolled
particulate emissions were reported to be approximately 2.1 kg/Mg (4.2
Ib/ton) of product.
3.2.5 Sol ids Cool ing
Supplementary cooling for the pan granulation process and for
agricultural grade prills produced in nonfluidzed bed prill towers is
provided by auxiliary coolers (see Figures 3-5 and 3-13.). All coolers
currently in use in the urea industry are of the rotary drum type. The
rotary drum cooler consists of a revolving cylindrical shell, horizontal
or slightly inclined toward the outlet. Hot feed enters one end of the
cylinder; cooled material discharges from the other. As the shell
rotates, internal flights lift the solids and shower them down through a
countercurrent flow of air.
A typical cooler is shown in Figure 3-14. A rotating shell made of
sheet steel is supported on two sets of rollers and driven by gear and
pinion. At the upper end is a hood which connects through a fan to a
stack. Flights are welded inside the shell. At the lower end the
cooled product discharges onto a conveyor. Just beyond the end of the
rotary cooler is a set of chillers which cools the incoming air. The
air is moved through the cooler by an induced draft fan which keeps the
system under a slight vacuum. Emissions from coolers consist of urea
particles that become entrained in the rotary cooler air stream.
3-31
-------
LIFTING
FLIGHTS
COOLER
SHELL
SHELL-
SUPPORTING
ROLLERS
DISCHARGE
FAN
AIR
OUTLET
FEED
CHUTE
COOLER
SHELL
/,
/ J.
W%
1 t
/
\
(
/
'aoanaaan
«
AIR
DISCHARGE
HOOD
SHELL-SUPPORTING
ROOLERS
SIDE VIEW
COOLED SOLIDS
DISCHARGE
CHILLER
AIR
INLET
70-2047-1
Figure 3-14. Typical countercurrent direct-contact air
chilled rotary cooler.
3-32
-------
The following parameters affect emissions from rotary drum coolers:
(1) Number, design and location of lifting flights
(2) Air flowrate through the drum
(3) Bed temperature
(4) Speed of drum rotation
Rotary drum coolers operate in much the same manner as the cooling
section of drum granulators. Therefore, parameters will affect emissions
in similar ways. The number, design, and location of lifting flights
affect the amount of fine particles entrained in the cooling airstream.
Likewise, the rotational speed of the drum may affect the entrainment of
urea in the airstream.
The airflow rate through the drum affects emissions from rotary
drum coolers. Increased airflow rates increase the amount of fines
entrained in the airstream. Also, with increased air flows, larger
particles may be transported in the cooling air. The bed temperature in
the rotary drum cooler can affect emissions indirectly. Higher bed
temperatures require increased airflow rates in order to cool the
prills. And, as discussed above, increased air flowrates cause higher
emission rates.
Testing of a rotary drum cooler cooling agricultural grade prills
was performed by EPA at one facility. Results of this test indicate an
uncontrolled emission rate of 3.90 kg/Mg (7.80 Ib/ton) of product. The
cooler tested was of typical capacity for urea coolers. Airflow rates
during testing varied within normal operating limits.
3.2.6 Solids Screening
Solid urea is screened to remove offsize product. The offsize
material may be returned to the process in the solid phase, as is
typically done in granulation plants, or it may be redissolved in water
and returned to the solution formation end for reprocessing. This
second option is usually performed at urea prilling facilities.
Product specifications for the more typical grades and types of
urea are presented below.50'51'52
3-33
-------
Feed Grade
TOO percent through a 10 mesh screen (U. S. Sieve)
90 percent caught on a 40 mesh screen (U. S. Sieve)
Agricultural Grade
98 percent through a 5 mesh screen (U. S. Sieve)
98 percent caught on a 30 mesh screen (U. S. Sieve)
Granular Grade
99 percent through a 6 mesh screen (U. S. Sieve)
99 percent caught on a 20 mesh screen (U. S. Sieve)
Several types of screens are employed to separate product size from
oversize and undersize material. Screening equipment commonly used in
the urea manufacturing industry include shaking screens and vibrating
screens.
Dust is generated due to abrasion of urea particles and the vibration
of the screening mechanisms. Therefore, almost all screening operations
used in the urea manufacturing industry are enclosed or have a cover
over the uppermost screen. Uncontrolled emissions from solids screening
were not tested by EPA. Results of survey inspections conducted during
this program indicated that this operation is a small emission source
53 54 55
and in most cases no visible emissions were observed. »^»w'J Therefore,
particulate emissions from solids screening will not be considered
further in this report.
3.2.7 Coating Operations/Additives
Clay coatings are used in the urea industry to reduce product
caking and urea dust formation. However, clay coatings also reduce the
nitrogen content of the product and the coating operation itself creates
of clay dust emissions. Presently, only three plants are still using
coatings. The popularity of coating has diminished considerably
because of the increasingly common practice of injecting additives into
rj co
the liquid or molten urea prior to solids formation. ' Additives
reduce solids caking during storage and urea dust formation during
transport and/or handling. Additives react with the urea to form a
59
crystalline urea compound by a mechanism that is not clearly understood.
3-34
-------
The resulting solid particle is harder than solids made without additives.
Additives, therefore, have replaced coatings in a major portion of the
urea industry, and this trend is expected to continue.
The most common additive is formaldehyde which is incorporated into
61 6?
the liquid urea before solid formation. ' The formaldehyde content of
the finished urea will generally fall between 0.3 and 1.0 percent.
Because addition of the additive involves a simple injection into the
urea melt, no particulate emissions result from the process. Formal-
dehyde emissions from EPA testing are reported in Table 3-1 and Appendix A.
Emissions attributable to coating include entrained clay dust from
loading, in-plant transfer, and from leaks around the seals of the
coater. No emissions data are available to quantify this fugitive dust
source. For this reason, coaters will not be considered further in this
document.
3.2.8 Bagging and/or Bulk Shipping
Solid urea product is either bagged or bulk shipped. The majority
of product is bulk shipped; approximately 10 percent is bagged. Two
types of bags are used: the open-top, sewn bag and the corner-fill,
valve-type bag. The open-top bag is held under the bagging machine
which fills the bag to a predetermined weight. After filling, the top
is pinched together and sewn. The corner-fill valve bag is "factory
closed"; that is, the top and bottom are partially closed either by
sewing or by pasting, and a small single opening or valve is left on one
corner. Urea is discharged into the bag through the valve. The valve
closes automatically due to the back pressure produced by the contents
of the bag as soon as it is filled.
Bagging operations are a source of particulate emissions. Dust is
emitted from each bagging method during the final stages of filling when
dust-laden air is displaced from the bag by urea. Bagging operations
are conducted inside warehouses and are usually vented to keep dus't out
of the workroom area according to OSHA regulations.
Mass emission tests were not conducted by EPA on an uncontrolled
bagging operation. However, data provided by industry indicates that
3-35
-------
uncontrolled particulate emissions are approximately 0.095 kg/Mg (0.19
Ib/ton) of product bagged. This emission rate was determined by weighing
the amount of urea collected in a baghouse used to control the bagging
operation.
On a national basis only a small fraction of urea produced is
bagged (approximately 10 percent). The major portion is bulk loaded
in trucks or enclosed railroad cars. The actual method of product bulk
loading varies from plant to plant. During bulk loading, long flexible
chutes are used to convey the urea from the storage hopper to the tank
truck or railroad car.
Very few plants control their bulk loading operations. As discussed
above, emissions vary with use of coatings. During this study, bulk
loading of a coated urea product was not observed; however, the bulk
loading of uncoated urea was observed. Generation of visible fugitive
particulates was very slight.
3-36
-------
3.3 REFERENCES
1. Search, W.J. and R.B. Reznik. (Monsanto Research Corporation.)
Source Assessment: Urea Manufacture. (Prepared for U.S. Environmental
Protection Agency.) Washington, D.C. EPA Publication No. EPA-600/2-
77-107L. November 1977. 94 p.
2. Reference 1, pp. 9-12.
3. Considine, D.M.(Ed-). Chemical and Process Technology Encyclopedia.
New York, McGraw-Hill Book Company, 1974. p. 118.
4. Reference 3, pp. 118 - 119.
5. Memo from Stelling, J., Radian Corporation, to file. April 1, 1980
p. 5. Compilation of ammonia and formaldehyde emissions data.
6. Reference 1, p. 13.
7. Reference 1, p. 14.
8. Reference 1, p. 15.
9. Reference 1, p. 16.
10. Memo from Bornstein, M., GCA Corporation, to file. December 6,
1979. p. 2. Solid urea manufacturing industry survey summary.
11. Trip report. Jennings, M., Radian Corporation, to file. March 27,
1980. Report of visit to W.R. Grace and Company in Memphis,
Tennessee.
12. Reference 10.
13. Trip report. Bornstein, M.I. and S.V. Capone, GCA Corporation, to
Noble, E.A., EPA:ISB. June 23, 1978. p. 2. Report of visit to
Agrico Chemical Company in Blytheville, Arkansas.
14. Trip report. Capone, S.V. and M.I. Bornstein, GCA Corporation, to
Noble, E.A., EPArlSB. June 21, 1978. p. 2. Report of visit to
Borden Chemical in Geismar, Louisiana.
15. Letter and attachments from Killen, J.M., Vistron Corporation, to
Goodwin, D.R., EPA:ESED. December 21, 1978. p. 9. Response to
Section 114 letter on urea plants.
16. Letter and attachments from Swanburg, J.D., Union Oil of California,
to Goodwin, D.R., EPA:ESED. December 20, 1978. pp. 4-5. Response
to Section 114 letter on urea plants.
3-37
-------
17. Reference 16.
18. Reference 15, p. 21.
19. Cramer, J.H. Urea Prill Tower Control Meeting 20% Opacity. Presented
at the Fertilizer Institute Environmental Symposium. New Orleans.
April 1980.) pp. 2-3.
20. Reference 19, p. 4.
21. Memo from Stelling, J., Radian Corporation, to file. June 18, 1980.
43 p. Compilation of uncontrolled emissions from urea prill towers
reported by industry.
22. Reynolds, J.C. and R.M. Reed. Progress Report on Spherodizer
Granulation 1975-1976. C & I Girdler Incorporated. Louisville,
Kentucky. (Presented at the Environmental Symposium of the Ferti-
lizer Institute. New Orleans. January 15, 1976.) p. 11.
23. Reference 1, p. 35.
24. Ruskan, R.P. Prilling vs. Granulation for Nitrogen Fertilizer
Production. Chemical Engineering. 83:114-118. June 7, 1976.
p. 116. ~~
25. Letter and attachments from Alexander, J.P., Agrico Chemical Company,
to Goodwin, D.R., EPA:ESED. December 21, 1978. p. 9. Response to
Section 114 letter on urea plants.
26. Trip report. Bornstein, M.I., GCA Corporation, to Noble, E.A.,
EPA:ISB. August 2, 1978. Report of visit to C & I Girdler Incor-
porated in Louisville, Kentucky, (p. 24 of addendum.)
27. Reference 25 p. 3.
28. Reference 26, p. 3.
29. Reference 28.
30. Reference 26, addendum 1, p. 12.
31. Reference 26, addendum 1, 25 p.
32. Reference 26, p. 2.
33. Reference 26, p. 2.
3-38
-------
34. Reference 26, addendum 1, p. 19.
35. Reference 34.
36. Reference 26, addendum 1, p. 6 - 7.
37. Reference 36.
38. Reference 26, addendum 1, p. 7.
39. Reference 32.
40. Reference 13.
41. Reference 38.
42. Reference 28.
43. Reference 26, addendum 1, p. 2.
44. McCamy, I.W. and M.M. Norton. Have You Considered Pan Granulation
of Urea? Reprint from Farm Chemicals, January 1977 issue, p. 4.
45. Hicks, G.C., I.W. McCamy and M.M. Norton. Studies of Fertilizer
Granulation at TVA. In: Proceedings of the Second International
Symposium on Agglomeration. New York, American Institute of Mining,
Metallurgical and Petroleum Engineers. March 6-10, 1977. p. 863.
46. Tennessee Valley Authority. New Developments in Fertilizer Technology.
(Presented at the llth Demonstration. National Fertilizer Development
Center. Muscle Shoals, Alabama. October 5-6, 1976.) pp. 80-81.
47. Reference 45, p. 3.
48. Reference 46.
49. Harre, E.A. The Outlook for Nitrogen Fertilizers. Tennessee Valley
Authority. Muscle Shoals, Alabama. (Presented at the Forest
Fertilization Conference. Union, Washington. September 25-27,
1979.) p. 6.
50. Reference 26.
51. Reference 14.
52. Reference 25.
53. Reference 25, p. 1.
3-39
-------
54. Reference 25, pp. 3-5.
55. Letter and attachments from Picquet, N.E., W.R. Grace and Company,
to Goodwin, D.R., EPArESED. December 14, 1978. p. 7. Response to
Section 114 letters on urea plants.
56. Reference 10.
57. Reference 16.
58. Trip report. Bornstein, M.I. and S.V. Capone, GCA Corporation, to
Noble, E.A., EPArlSB. June 22, 1978. p. 2. Report of visit to
W.R. Grace and Company in Memphis, Tennessee.
59. Barber, J.C. Energy Requirements for Pollution Abatement. Chemical
Engineering Progress. 72:42-46. December 1976.
60. Letter and attachments from Homan, J.M., Terra Chemicals International,
to Goodwin, D.R., EPA:ESED. December 14, 1978. pp. 2-22. Response
to Section 114 letter on urea plants.
61. Reference 50. p. 3.
62. Reference 60, p. 11.
63. Reference 60.
64. Reference 55, p. 5.
65. Trip report. Curtin, T.L., GCA Corporation, to Noble, E.A., EPA:ISB.
August 13-23, 1979. p. 4. Report of visit to W.R. Grace and
Company in Memphis, Tennessee.
66. Reference 10.
68. Reference 11.
3-40
-------
4.0 EMISSION CONTROL TECHNIQUES
This chapter discusses techniques used for controlling urea
participate emissions from prill towers, coolers, granulators, and
bagging operations in the urea industry.
As mentioned in Chapter 3, ammonia and formaldehyde emissions are
also generated in urea processes. However, the major objective of this
study is to evaluate particulate emissions. Accordingly, this chapter
concentrates on the effectiveness of various devices in controlling
particulate matter.
The majority of the data used in assessing control device effectiveness
was generated by an EPA source testing program conducted in conjunction
with this project. Testing involved particulate emission measurements
at five urea plants utilizing test methods similar to the test method in
Appendix B. Appendix A provides more detailed information on all test
data used in this chapter.
The chapter is organized in the following manner. Section 4.1
presents a general overview of control techniques used in the urea
industry. Section 4.2 describes several of these control techniques in
greater detail and outlines the factors that affect their performance.
Section 4.3 reviews available industry and EPA emission test data.
Finally, Section 4.4 evaluates this data and control device performance.
4.1 OVERVIEW OF CONTROL TECHNIQUES
With the exception of bagging operations, urea emission sources are
typically controlled with wet scrubbers. The preference toward scrubber
systems as opposed to dry collection systems is primarily due to the
ease of recycling dissolved urea collected in the device. Scrubber
liquors are recycled back to the solution concentration process, eliminating
potential waste disposal problems and recovering the urea collected.
4-1
-------
Concerning other potential control devices, fabric filters are not
suitable for controlling emissions from many sources because the hygro-
scopic nature of urea oarticulate combined with the moisture content of
the gas streams could cause blinding of the bags. Dry cyclones offer
lower collection efficiencies than scrubbers in urea particulate applications,
Electrostatic precipitators are not currently in use in any urea industry
applications.
Fabric filters (baghouses) are used in the control of fugitive dust
generated in bagging operations where humidities are lower and blinding
is not a problem. Many bagging operations are uncontrolled. However,
if a control device is used, baghouses are the typical method of control.
Table 4-1 presents a summary of the present population of control
devices being applied to prill towers, granulators, and coolers. As
mentioned previously, these sources use wet scrubbers if a control
device is used. The following subsections provide a brief description
of how controls are applied to each urea emission source under consideration.
4.1.1 Nonfluidized Bed Prill Tower Controls
The majority of nonfluidized bed prill towers are uncontrolled. Of
the seven prill towers which utilize control devices, one uses a spray
tower scrubber, two use packed bed scrubbers, one uses a wetted fibrous
filter, and three companies consider the type of scrubber used to be
confidential information.
Control devices vary considerably in the number used and in placement
for various applications. The most common location for scrubber mounting
on nonfluidized bed prill towers is on the top of the tower. Only two
1 2
installations duct emissions to ground level. ' Tower mounting is
usually more economical since long runs of corrosion resistant ducting
are not required. However, scrubbers mounted on top of towers typically
do not have the extended stacks necessary for suitable sampling locations.
In addition, tower mounting may require a strengthened prill tower in
order to withstand the additional weight and wind load of the scrubber.
4-2
-------
TABLE 4-1. SUMMARY OF USE OF WET SCRUBBERS IN THE UREA INDUSTRY46'47'48
Emission Source
Prill Towers
NFB
II)
Rotary
Gra nu la tors
-f* Pan Granule tor
CO
Coolers
No. of
Fm iss ion
Sources
15
3
19
1
6
Spray
Tower
1
1
0
0
0
Packed
Tower
2
0
1
0
2
Mechanicall y
Aided
0
0
0
0
2
T}
Wet
Cyclone
0
0
0
1
0
/pe of '
1 my
Type
0
0
0
0
1
ic rubber
Fntra i union 1
0
1
18
0
0
Fibrous
Filter
1
0
0
0
0
Scrubber
Typo
Unknown
3
1
0
0
0
llncontrol led
8
0
n
0
1
-------
The number of scrubbers used on a nonfluidized bed prill tower
varies considerably. One system uses a single device, while other prill
towers use up to four devices. The use of more than one scrubber allows
for variability in airflow rates. A prill tower which produces both
feed and agricultural grade product may need only 30 percent of the
agricultural grade airflow during feed grade production. Seasonal
changes in ambient temperatures may also dictate that flow rates be
varied in order to maintain a reasonably constant prill temperature.
Thus, a scrubber system needs the ability to be turned down to lower
airflow rates while maintaining removal efficiencies. Multiple scrubbers
allow units to be removed from service while maintaining normal airflow
and pressure drops in the remaining operating scrubbers. The wetted
fibrous filter allows pressure drop to be adjusted readily while the
unit is in operation, thus accomodating changes in airflow rates.
4.1.2 Fluidized Bed Prill Tower Controls
Three fluidized bed prill towers are currently operating and all
use some type of scrubber system. One manufacturer considers all
information concerning their in-house designed scrubber system pro-
prietary. Another manufacturer uses a spray tower scrubber with extensive
internal baffles. The third fluidized bed prill tower uses multiple
entrainment scrubbers. All fluidized bed prill towers use tower mounted
control devices. As with nonfluidized bed prill towers, tlv's mounting
typically causes problems in prill tower emission testing.
4.1.3 Granulator Controls
With one exception, all rotary drum granulators are controlled by
nearly identical entrainment scrubbers. These are essentially the same
scrubbers as used on the fluidized bed prill tower mentioned previously;
however, a higher pressure drop is used for granulator applications.
The only exception to the use of entrainment scrubbers is the use of a
packed tower at one drum granulator installation. This drum granulator
is produced by a different company than the other 18 granulators.
4-4
-------
Since nearly all drum granulators are similar designs marketed by
the same company, installations are fairly standard. One scrubber is
used for each granulator and a testable outlet stack is typically
provided. However, at least one installation uses a common outlet stack
for two scrubbers.
The single pan granulator operating in the United States uses a wet
cyclone scrubber.
4.1.4 Rotary Drum Cooler Controls
Rotary drum coolers are used to cool agricultural grade prills when
sufficient cooling is not provided in the prill tower. Coolers are not
required in fluidized bed prill towers, during feed grade production, or
when adequate cooling airflow is available in the prill tower.
A wide variety of control devices are currently used to control
cooler exhausts: packed towers (both moving bed and conventional bed),
mechanically aided scrubbers and tray towers. One cooler is uncontrolled,
4.1.5 Bagging Operation Controls
At some urea plants, a portion of the solid product is bagged, as
discussed in Chapter 3. Bagging operations are hooded and vented to the
atmosphere to reduce dust levels in the workroom air, in accordance with
Occupational Safety and Health Administration (OSHA) standards.
Emissions from the exhaust ventilation system for the bagging
operation may be vented directly to the atmosphere or through an air
pollution control device. The most commonly used control device for
bagging operations is a fabric filter (baghouse). Of the eleven urea
plants conducting bagging operations, six use baghouses while one is
reported to use a dry cyclone. The remainder are uncontrolled.
4.2 DESCRIPTION OF CONTROL TECHNIQUES
In this section, the various types of control devices used in the
urea industry are reviewed. This review includes a description of the
device, the collection mechanism, and the factors that affect performance.
4-5
-------
4.2.1 Wet Scrubbers
A wet scrubber is a device in which a gas stream is brought into
contact with a liquid, usually water. Any device which introduces a
liquid to clean an airstream may be termed a scrubber. Scrubbers are
widely used to remove gaseous components as well as particulate matter.
Scrubbers rely on a variety of collection mechanisms, however, the
dominant mechanisms in all scrubbers used in the urea industry are
impaction and interception. The scrubber provides water droplets and/or
wetted surfaces which impact and intercept the particles. The particulate
laden liquid is then separated from the gas stream and recycled or
discharged as waste.
Other collection mechanisms which may contribute to scrubber effectiveness
include gravitational settling, diffusion (brownian motion), and condensation
effects. However, the importance of these mechanisms are usually secondary
in the types of scrubbers described in this chapter.
Scrubber performance depends on the characteristics of the dust
laden airstream being cleaned and on the design and operation of the
scrubber. The most important airstream characteristics are particle
size distribution and grain loading. Other factors being equal, larger
particles are removed with greater efficiency than smaller ones.
Likewise, higher grain loadings may lead to agglomeration, enhancing
scrubber effectiveness.
Two factors in the design and operation of a scrubber which may
strongly influence performance are energy input and liquid flow rate.
Increased energy input to the scrubber causes more turbulent gas-liquid
contact and greater particulate removal. Similarily, increasing liquid
flowrate in the scrubber usually enhances gas-liquid contact. In both
factors, however, a level is reached where increases are no longer
justified by the improvement in performance.
The high velocity, turbulent flow of gas through the scrubber
causes a decrease in the gas phase pressure head. This pressure drop
4-6
-------
across the scrubber is a convenient means of measuring the energy used
in the scrubber. High pressure liquid sprays may also supply energy,
however, the importance of this energy input is usually secondary for
scrubbers used in the urea industry.
4.2.1.1. Spray Tower Scrubbers. Figure 4-1 depicts a spray tower
scrubber system of the type presently being used to control a fluidized
bed prill tower. The airflow from the prill tower travels upward
impinging on a baffle plate. As the gas flows around the baffle,
several gas vortices are formed which increase the residence time in the
scrubber. The gas stream passes through a jet of fine sprays which
impacts the particles. Particle laden droplets fall to the bottom of
the scrubber housing and are removed with the liquid stream.
In general, the performance of spray towers is influenced by the
surface area of the scrubbing droplets and the relative velocity between
the droplets and the particles entrained in the gas stream. Small
droplets can enhance performance since small droplets provide a large
surface for particle impingement. On the other hand, large droplets can
also enhance performance since large droplets fall at high terminal
velocities, and thus provide a high relative velocity between particles
and droplets. This high relative velocity usually increases the chances
of a particle impacting a droplet.
Depending on the particle size distribution of the incoming gas
stream, an optimum droplet size which balances these two effects will
provide best performance. This optimum size is reported to be in the
range of 500 to 1000 microns over a wide range of particle sizes.8 Droplet
size is influenced by the nozzle configuration and the nozzle pressure.
Nozzle pressures of 138 - 689 kPa (20 - 100 psig) are typical9; however,
high pressure sprays of 2760 kPa (400 psig) may also be used when a very
fine droplet size is desired.1 Concerning liquid use in spray towers,
a range of .0669 - 1.07 liters/m3 of gas (.5-8 gal/1000 ft3)11 has been
reported. Pressure drops in spray towers are usually very low, typically
less than .5 kPa (2 in. W.G.).12
4-7
-------
GAS
OUTLET
DRAIN
DEMISTER
SPRAY
HEADER
BAFFLE
70-2048-1
Figure 4-1. Typical soray tower scrubber.
49
4-8
-------
The spray tower currently used in urea prill tower applications is
designed to operate at .25 - .5 kPa (1-2 in. W.G.) pressure drop with
liquid to gas ratios of .134 - .268 liters/m3 (1-2 gal/1000 ft3). Spray
nozzle pressure is 689 - 1380 kPa (100 - 200 psig).13 Although efficiency
curves for various particle sizes are not available, the manufacturer
claims exit loadings of .0115 - .0344 g/m3 (.005 - .015 gr/dscf) are
achievable in urea prill tower applications. Concerning visible
emissions, the manufacturer has reported that opacities of 20 percent or
less are achievable.
4.2.1.2 Packed Towers. In packed towers (Figure 4-2) the scrubber
interior is packed with shaped elements or materials such as crushed
rock. The packing is irrigated by water sprays to keep the packing wet
and provide a wet surface for particulate impingement. Particles impact
the wetted packing and are subsequently flushed to the bottom of the
scrubber. Gas flow may be concurrent, countercurrent, or crossflow to
the liquid stream.
The performance of a packed tower is directly influenced by the
size, shape and type of packing material. Small packing material with
high ratios of surface area to volume are usually desirable, although
clogging may be a problem with small, intricate packings. The depth of
packing does not have a great effect on particulate removal once a
minimum depth is provided. This minimum depth has been reported to be
10 - 12 times the major dimension of the packing pieces.
Velocity through the tower also affects performance. Higher velocities
increase impingement of medium and large particles. For very small
particles (less than .3 microns) a low velocity may be desirable to
1R
assist removal via diffusion.
Pressure drops depend on packing type and depth. Approximately
.123 kPa (.5 in. W.G.) per foot of bed is typical for most packings.
Total pressure drop through the scrubber is typically between .5 kPa (2
in. W.G.) and 2.5 kPa (10 in. W.G.).19 Liquid use is normally .267 -
.669 liters/m3 of gas (2-5 gal/1000 ft3).
20
4-9
-------
PACKED
SECTIONS
GAS
OUTLET
>»>>»> 7
LIQUOR
OUTLET
CHEVRON
DEMISTER
LIQUOR
INLET
SUMP
70-2049-1
Figure 4-2. Typical packed tower scrubber.
4-10
-------
The major disadvantage of packed beds is their susceptibility to
clogging under high particulate loadings. A moving bed alleviates this
problem to some extent by providing a semi-fluidized packing, usually of
plastic spheres. The spheres rotate and jiggle slightly, constantly
exposing clean areas which collect particles. Higher gas velocities, a
result of fluidizing the packing material, increase turbulence and gas-
liquid contact. Pressure drops for these scrubbers are about double a
PI
conventional packed bed.
4.2.1.3 Mechanically Aided Scrubbers. Mechanically aided scrubbers
rely on a motor driven device between the inlet and outlet of the scrubber
body to effect particle removal. This device also serves as the fan
which draws air through the scrubber. Particles are collected by
impaction upon the fan blades as the gas flows through the scrubber.
Liquid is typically introduced at the hub of the rotating fan blades.
Some liquid atomizes upon fan impact, while some runs over the blades,
washing them of collected particulate. This latter portion atomizes as
it leaves the fan wheel. The liquid is recaptured by the fan housing,
which drains into a sump. Figure 4-3 shows an example of a mechanical
centrifugal scrubber.
The performance of this scrubber is influenced by the total energy
input to the fan and the liquid flow rate provided. Higher fan velocities
generally cause greater impingement of particles on the fan blades.
22
Likewise, increased liquid flow rates increase particle removal.
4.2.1.4 Tray Type Scrubbers. A tray type scrubber is shown in
Figure 4-4. It consists of a vertical tower containing one or more
transversely mounted trays. Particulate laden gas enters the tower
bottom and bubbles through valves, perforations, or other types of
openings in each tray before exiting through the top of the tower.
Scrubbing liquid is usually introduced at the top tray, and flows across
each tray, over a restraining dam, and through a downcomer to reach the
tray below. The particulate laden liquid exits the bottom of the tower.
Gas passes through the openings in each tray and bubbles through the
liquid flowing over the tray. Liquid-gas contacting causes the mass
transfer and particle removal.
4-11
-------
WATER
SPRAYS
VANES
SUMP
WATER
DRAINS
70-2036-1
Figure 4-3. Typical mechanically aided scrubber.
50
4-12
-------
DIRTY GAS
INLET
CLEAN GAS
OUTLET
SUMP
LIQUOR
INLET
TRAYS
LIQUOR
OUTLET
70-2064-1
Figure 4-4. Typical tray-type scrubber.
4-13
-------
As the diameter of the tray perforations decreases, the collection
efficiency for smaller particles usually improves. A tray type scrubber
does not have the same efficiency for all particle sizes, but instead
exhibits a sharp efficiency drop at a specific particle size. This size
23
is determined by the size of the tray perforations.
The pressure drop through a plate type scrubber is determined by
the size of the orifices, the number of trays, and the velocity of the
gas stream through the scrubber. In general, higher pressure drops
24
result in greater efficiencies.
Although, some texts indicate that increasing the number of trays
?5
has little effect on particulate removal, manufacturer's performance
curves show an increase in removal with more trays. Figure 4-5 illus-
trates this effect for a tray type scrubber used in the urea industry
for a variety of particle sizes. The efficiency on the vertical axis,
termed standard efficiency, is for a standard .375 kPa (1.5 in. W.G.)
pressure drop per tray.
Figure 4-6 illustrates the effect of increasing the pressure drop
across each tray. For any given standard efficiency at .375 kPa (1.5
in. W.G.) per tray obtained from Figure 4-5, the efficiency at higher
pressure drops may be read from Figure 4-6.
Liquid flow rate can have some effect on particle removal, however,
an optimum flow rate is usually maintained which insures adequate liquid
for particulate removal without blocking airflow through tray orifices.
Typical liquid to gas ratios are .0669 - .401 liters/m3 (.5-3 gal/1000
ft3) at 172 kPa (25 psig) liquor pressure.26
4.2.1.5 Entrainment Scrubbers. Entrainment scrubbers (also
referred to as orifice type, self-induced spray, or impingement and
entrainment scrubbers) utilize the velocity of the gas stream over the
surface of a liquid, in combination with a sudden change in direction of
the gas flow, to remove particulates. A common entrainment scrubber
used in urea industry applications is shown in Figure 4-7. The gas
stream enters the circular housing, where it is forced through a narrow
gap formed between the surface of the sump liquor and an inner housing.
4-14
-------
Standard Efficiency
-5
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100
98
90
91
92
96
97
93 94 95
High Pressure Drop Efficiency
Figure 4-6. Effect of pressure drop on tray type scrubber efficiency.
99
100
-------
OUTLET
INLET
LIQUOR
INLET
SPINNER
VANES
SUMP
70-2037-1
LIQUOR
OUTLET
Figure 4-7. Typical entrainment scrubber.
53
4-17
-------
A turbulent zone is established at this gap promoting spray droplet
formation and dispersion as the gas abruptly changes directions. The
moisture laden stream is then demisted by swirl vanes before exiting the
scrubber.
The primary factor influencing the performance of the entrainment
scrubber is pressure drop across the device. The effect of pressure
drop and particle size on scrubber efficiency is illustrated in the
fractional efficiency curves presented in Figure 4-8. Entrainment
scrubbers used in the urea industry operate at widely varying pressure
drops depending on the application.
4.2.1.6 Fibrous Filter Scrubbers. A type of wetted fibrous filter
scrubber has recently been installed and operated to control prill tower
emissions. The device is depicted in Figure 4-9. The scrubber utilizes
a filter installed over a perforated drum. The filter drum rotates
slowly through a shallow liquor bath and is also irrigated by spray
nozzles located throughout the drum chamber. Gases pass from the
exterior of the drum, through the wetted filter, and into a mist eliminator
section. The demister housing is a horizontal cylinder with an inclined
demister element located near the scrubber exit. Flow through the prill
tower and scrubber is induced by an axial fan mounted downstream from
the demister section.
The filter itself is a dense fibrous mat. For prill tower control,
a TeflonR mat is used.27 As the particles travel at high velocity
through the filter, they impact the wetted fibers and are held until
they are washed either by the sprays or the bath at the bottom of the
filter housing.
The design of the wetted fibrous filter allows the pressure drop to
be readily adjusted while the scrubber is in operation. This adjustment
is possible through the use of a moving, semi-cylindrical baffle plate
which may be used to cover a fraction of the filtration drum. By covering
a portion of the drum face, the airflow is forced to travel through a
smaller area on the drum which increases face velocities. These higher
velocities result in greater impingement of particulate on the filter
4-18
-------
COLLECTION EFFICIENCY VS PARTICLE SIZE
9999
9995
4-9990
9980
9950
9900
9800
95.00
90.00
3000
100
PARTICLE DIAMETER IN MICRONS
Figure 4-8. Fractional efficiency of entrainment scrubber used in the
urea industry as a function of particle size and pressure drop
(courtesyrgf the Western Precipitation Division of Joy Manufacturing
Company).
4-19
-------
I
ro
o
INLET
LIQUOR
SPRAYS
MIST
ELIMINATOR
ROTATING PERFORATED
FILTRATION DRUM
OUTLET
70 2050 1
Figure 4-9. Typical fibrous filter scrubber.
55
-------
mat and increase removal efficiency at the expense of higher pressure
drop.
The baffle may also be used to hold the pressure drop constant at
various airflows through the scrubber. This feature allows collection
efficiencies to be maintained while producing different grades of
product which require different airflows.
Figure 4-10 presents the efficiency of the wetted fibrous filter as
a function of particle size. This curve was obtained during prill tower
P
testing of a Teflon filter scrubber operating at 4.75 kPa (19 in.
W.G.). According to the vendor, improvements have been made to the
scrubber since this test, which allow this performance curve to be met
OQ
with pressure drops in the range of 3.0 - 3.75 kPa (12 - 15 in. W.6.).
The effect of pressure drop on particulate removal efficiency is illustrated
in Figure 4-11.
The plant where the wetted fibrous filter is used to control prill
tower emissions uses a preconditioning system involving liquor injections
in the ductwork prior to the scrubber. This preconditioning system is
reported to cause particle agglomeration prior to the scrubber and thus
increase the scrubber's effectiveness. Details of the preconditioning
system are considered proprietary by company personnel.
The wetted fibrous filter may be operated at from 2.5 - 7.5 kPa
(10 - 30 in. W.G.) differential pressure drop across the device.
Typical liquid recirculation requirements (scrubber only) are .134 -
.267 liters/m3 of gas (1-2 gal/1000 ft ). Spray nozzle pressure is
approximately 138 kPa (20 psig).29
4.2.2 Fabric Filters
Fabric filters (baghouses) are high efficiency collection devices
used quite extensively throughout the chemical processing industry.
Design variables for baghouses include method of cleaning, choice of
fabric, size of the unit, air-to-cloth ratio, and whether the baghouse
is a pressure or suction unit.
Figure 4-12 depicts a typical fabric filter system. In the type of
design shown, the airstream enters the baghouse and is pulled up into
4-21
-------
-p»
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100
99
98
97
96
95
94
93
92
91
90
89
88
87
0 .2 .4 .6 .8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8
Particle Size (microns)
Figure 4-10. Fractional Efficiency of Wotted Fibrous Filter Scrubber56
-------
Overall Efficiency
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BRANCH
HEADER
CLEAN AIR
OUTLET
NOZZLE
BAFFLE
PLATE
PYRAMIDAL OR
TROUGH HOPPERS
ACCESS
DOOR
70-2025-1
Figure 4-12. Diagram of a Fabric Filter.
58
4-24
-------
fabric sleeves located throughout the baghouse. Air is pulled through
these fabric sleeves and exhausted to the atmosphere while dust remains
trapped in the weave of the fabric, forming a layer of dust on the bag.
The pressure drop through the bag increases as this dust layer builds
up. The dust is periodically removed from the bag by one of several bag
cleaning methods.
Two methods of cleaning are shaking (rapping) and reversing the
airflow through the bag by air jets or pulses. Shaking consists of
manually or automatically shaking the bag hangers or rapping the side of
the baghouse to shake the dust free from the bags and into a receiving
hopper below. In the jet pulse method, compressed air is released at
regular intervals in to a group of bags, causing the bags to pulse and
the dust to be released.
Cleaning can be either continuous or intermittent. Intermittent
cleaning consists of shutting down the baghouse or a section of the
baghouse when it reaches its highest design pressure drop. For con-
tinuous cleaning, individual bags are cleaned at regular, timed intervals.
An important operating principle for fabric filters is that effective
filtering of the dusty airstream is accomplished not only by the fabric,
but also by the dust layer which forms on the fabric. This dust layer
bridges the gaps between adjacent fibers and increases the chances of
impaction and interception of small particles. For this reason, too
frequent cleaning can actually decrease efficiency by not allowing a
dust layer to accumulate between cleaning cycles.
The urea dust layer can cause problems in urea industry applications
due to the hygroscopic nature of urea particulate. The dust layer can
absorb moisture in the air and cause the formation of a sticky cake.
This cake increases the pressure drop and can cause difficulties in
cleaning. For this reason, use of baghouses in the urea industry is
currently limited to process airstreams with low moisture contents, such
as bagging operations.
4-25
-------
Materials available for bag construction are numerous. They
p
include cotton, Teflon , coated glass, orlon, nylon, dacron and wool.
Temperatures, frequency of cleaning, ease of removing particles, resis-
tance to chemical attack, and abrasion characteristics of the collected
particles determines the type of bag fabric material.
Factors affecting baghouse performance include air to cloth ratio,
type of fabric used, method and interval of cleaning, pressure drop, and
the properties of the dusty exhaust being cleaned. Air to cloth ratio
is dimensionally equivalent to a velocity, and thus indicates the
average face velocity of the gas stream through the effective area of
the fabric. An excessive filter ratio results in excessive pressure
loss, reduced collection efficiency, rapid bag blinding, and increased
wear on the fabric. Too low an air to cloth ratio results in an over-
size unit and can also reduce collection efficiency since an adequate
filtering dust dayer may not be allowed to accumulate between cleaning
cycles.
Pressure drops in baghouses depend on a variety of factors including
the air to cloth ratio, fabric type, and cleaning cycle. Pressure drops
typically increase between cleaning cycles as the dust layer builds.
Pressure drops of from .5-2 kPa (2-8 in. W.G.) are common for many
applications.30 Air to cloth ratios range from 2 to 10 with 3 being the
typical ratio reported in the urea industry. Methods used in the
industry for cleaning baghouses include mechanical shaking, reverse
pulse airflow, and vibration. Types of cloth material commonly used in
the industry include cotton, dacron and polyester. )5j
4.3 EMISSION TEST DATA
Available data concerning control device performance is broken down
into two basi types: data supplied by industry and state air pollution
agencies (hereafter referred to as industry data), and data collected by
EPA during source testing conducted for this study (hereafter referred
to as EPA data). In general, the available industry data is very limited.
Industry data presented in this section is confined to mass emission
measurements of prill towers and coolers. It should be noted that
4-26
-------
the industry data vary widely in test procedures and sampling techniques.
In particular, significant difficulties exist in sampling emissions from
prill towers due to their design. Comparisons between the two types of
data are not intended to imply that the sampling and test procedures are
similar.
Tables 4-2 and 4-3 present an overall summary of EPA mass emission
test results and visible emission test results, respectively. Appendix
A presents details of the test data and testing program.
As can be noted in Table 4-2, control of ammonia emissions to a
significant degree is not currently demonstrated in the urea industry.
In fact, most test data indicates an increase in ammonia emissions
across the control device. Control of formaldehyde emissions is quite
variable, however, the level of formaldehyde in the control device inlet
is usually quite low to begin with. Because ammonia control is not
currently demonstrated in the industry and formaldehyde emissions are
small, the following subsections will address control device performance
in terms of particulate removal only.
4.3.1 Emission Data for Nonfluidized Bed Prill Towers
Table 4-4 presents the available industry data for controlled
nonfluidized bed prill towers consisting of four tests conducted at
three plant sites. Two of these three plants were also tested by EPA.
(Plant E and Plant C.) Test results for Plant E are presented in Appendix
A, Tables A-63 through A-65. Tests at Plant E represent measurements of
a nonfluidized bed prill tower producing agricultural grade product.
This plant uses a wetted fibrous filter. The tests (Appendix A, Tables
A-63, and 64 versus Tables A-65 and 66) differ in the type of precondi-
tioning sprays used in the ductwork prior to the scrubber. Tables A-65
and 66 represent full preconditioning as the plant normally operates and
Tables A-63 and 64 represent testing with partial preconditioning.
Preconditioning is used to encourage particle agglomeration prior to the
scrubber. According to these tests, full preconditioning shows improvement
in outlet mass emissions (0.22 g/kg and .044 Ib/ton) compared to the
partial preconditioning (.320 g/kg and .640 Ib/ton).
4-27
-------
TABLE 4-2. SUMMARY OF EPA MASS EMISSION TEST RESULTS
ro
CO
Particulate Emissions
Process
NFB Prill
Tower - AG
Product
NFB Prill
Tower - AG
Product
FB Prill
Tower - AG
Product
FB Prill
Tower - EG
Product
Drum
Grnnulator
flnim
Granulator
Control
Device
Packed
Tower
Scrubber;.
Wetted
Fibrous
Filter
Entrain-
ment
Scrubber
Entrain-
ment
Scrubber
Entrain-
ment
Scrubber
Entrain-
ment
Scrubber
Production
Rate
Mg/day
Plant (ton/day)
C 268
(295)
E 266
(293)
D 979
(1078)
D 1020
(1123)
A 356
(392)
D NAC
Control
Device
Inlet
kg/Mg
(Ib/ton)
NAa
1.88
(3.76)
3.12
(6.24)
1.80
(3.59)
149
(298)
63.6
(127.2)
Control
Device
Outlet
kg/Mg
(Ib/ton)
.188
(.375)
.0271
(.0541)
.392
(.785)
.240
(.479)
.115
(.230)
.122
(.244)
Ammonia
Control
Devicp
Collection Inlet
Efficiency kg/Mg
% (Ib/ton)
NA N
Aa
98.3 0.326
(.653)
87.6 1
(2
86.7 1
(3
99.9 1
(2
99.8 1
(2
.39
.78)
.99
.98)
.08
.16)
.07
.13)
Emissions Formaldehyde Emissions
Control
Device
Outlet
kg/Mg
(Ib/ton)
0.
(1
2
(4
3
(6
1
(2
3
(6
(i
640
.28)
.18
.36)
.25
.50)
.04
.08)
.07
.14)
845
.69)
Control
Device
Collection Inlet
Efficiency kg/Mg
% (Ib/ton)
NA NAb
<0 NAb
<0 .00910
(.0182)
49.7 .00190
(.00380)
< 0 .00359
(.00717)
20.5 .000380
(.000560)
Control
Device
Outlet Collection
kg/Mg Efficiency
(Ib/ton) %
NA
NA
.000420
(.000839)
.000500
(.000999)
.00136
(.00271)
.000125
(.000250)
NA
NA
95.4
74.8
62.2
50.2
alnlet tests not concucted during outlet tests. Earlier inlet tests considered nonrepresentative (see Appendix A).
bFonnaldehyde tests rot conducted.
°Production rate considered confidential by company.
Data is averaged for tests A-l and A-2
Legend:
AG - Agricultural Grade
FP - Feed Grade
NFB - Nonfluidized bed
m - Fluidized bed
NA - Not available
-------
TABLE 4-3. SUMMARY OF EPA VISIBLE EMISSION TEST RESULTS
ro
Process
NFB Prill Tower -
AG Product
NFB Prill Tower -
FG Product
NFB Prill Tower -
AG Product
FB Prill Tower -
AG Product
FB Prill Tower
FG Product
Drum
Granulator
Drum -
Granulator
Bagging
Operations
Rotary Drum
Cooler
Rotary Drum
Cooler
a
Control
Device
Packed
Tower
Packed
Tower
Fibrous
Filter
Entrainment
Scrubber
Entrainment
Scrubber
Entrainment
Scrubber
Entrainment
Scrubber
Fabric
Filter
Packed
Tower
Entrainment
Scrubber
Opacity Measurements (%)
Plant
C
C
. E
D
D
A
B
D
E
C
Observations9
158
42
179C
117b
106b
79
62
35
10
11
Min.
.2
5.0
0
10.0
3.3
0.0
5.0
0.0
1.0
15.0
Max.
37.0
54.4
27.1
41.2
33.3
5.0
9.7
1.0
4.4
27.0
Average
9.68
16.8
9.33
25.3
20.8
2.92
7.62
.05
3.0
22.0
Six minute average
Includes measurements both on individual scrubbers and on prill tower as a whole.
"Data is for both tests conducted at Plant E.
Legend: NFB - Nonfluidized bed
FB - Fluidized bed
AG - Agricultural Grade
FG - Feed Grade
-------
TABLE 4-4. SUMMARY OF INDUSTRY MASS EMISSION TEST RESULTS FOR CONTROLLED PRILL TOWERS
29,48
Tower-
Plant Type Product
E NFB AG
Ma NFB
(Iwo towets)
NFB
Cb NFB AG
Dc FB FG
(two products)
FB AG
f-
Co Nb FB -
o
Production
Mg/day
(tons/day)
272
(300)
218
(240)
999
(1100)
272
(300)
923
(1017)
946
(1042)
629
(693)
Control
Devic.e
Wetted
Fibrous
Filter
Packed
Tower
Entrainment
Scrubber
Entrainment
Scrubber
Spray
Tower
Pressure
Drop
I: Pa
(in. W.G.
?. 5-4.75
(10-19)
.5
(2)
1.25
(b)
1.25
(5)
-
.-- -
Airflow
dsnr/min
) (dscfm)
2,410
(85,000)
3,750
(132,400)
10 200
(359,000)
1,530
(53,900)
8,520
(301,000)
12,470
(440,200)
3,790
(133,800)
— -
Particle
Concentration
g/dsm
(gr/dscf)
.00183
(.0008)
.00506
(.00256)
.00701
(.00306)
.00701
(.00310)
.0321
(.0140)
.0198
(.00867)
.0490
(.0214)
Emission
Rate
g/ml n
(Ib/hr)
4.41
(.583)
22.0
(2.91)
71.2
(9.41)
11.0
(1.45)
273
(36.1)
247.
(32.7)
185.
(24.5)
- -
Emission
Factor Device
kg/Mg Efficiency
(Ib/ton) I
.0271 98.8
(.0541)
.146
(.291)
.103
(.205)
.0580 91 .6
(.116)
426 86.3
(.852)
.377 79.0
(.753)
.425
(.«49)
;inn ratpH nrp not availa
r:r :;
based on uncontrolled emissions as given in Chapter 3
recorded during test. Pressure drop given measured during EPA test.
Legend: NFB - tlonfluidi?ed bed
FB - lluidized bed
AG - Agricultural Grade
FG - Feed Grade
-------
The EPA test results for Plant C are presented in Appendix A,
Tables A-26 and A-27. These results represent measurements of a nonfluidized
bed prill tower producing agricultural grade product. The emission
control system at this plant consists of four packed bed scrubbers
operated in parallel. One scrubber was tested and the total emissions
were determined by factoring the single emission measurement by four.
This assumes that the tested scrubber is representative of the remaining
three. Velocity traverses and visible emission observations of the
untested scrubbers show this assumption to be reasonable (see Appendix A).
Particle size tests were conducted at Plants C and E on prill tower
exhausts entering the scrubbers. At Plant C, tests were run during
production of both agricultural and feed grade production. This data,
presented in Figure 4-13, shows a shift toward larger particles during
feed grade production as evidenced by a shift to the left of the cumulative
distribution plot. At Plant E, the particle size distribution during
agricultural grade production (Plant E does not produce feed grade urea)
was measured. This data is presented in Figure 4-14.
One industry particle size test for a nonfluidized bed prill tower
is available and is presented in Figure 4-15. This data also shows a
shift toward larger particles during feed grade production.
Visible emission data were gathered by EPA during the tests at
Plant C and E. Figure 4-16 presents histograms of the visible emission
data collected at Plant C during both agricultural grade and feed grade
tests. Opacity during feed grade production averaged somewhat higher.
During feed grade production at Plant C, prill tower fans are shut off
and the tower airflow is induced by natural draft only. This results in
lower air velocities and pressure drops in the scrubbers, which may
contribute to higher opacity readings during feed grade production.
Figure 4-17 presents histograms of the visible emission data collected
at Plant E. These tests both involved agricultural grade production and
differ only in the preconditioning system used. Opacity readings were
generally higher with full preconditioning.
4-31
-------
o
cc
o
O
cc
<
0.
100.0-1
50.0-
40.0-
300-
200-
10.0-
50-
40-
3.0-
2.0-
1 0-
.5-
4-
3'
2-
1 T
1 2
O AGRICULTURE GRADE
A FEED GRADE
NOTE: THESE RESULTS REPRESENT AVERAGES OF
THREE RUNS FOR EACH TEST
n—r
5 1
5 10 15 20 30 40 50 60 70 80 85 90
CUMLATIVE PERCENT LESS THAN SIZE
95
98
70-2051-1
Figure 4-13. Particle size distribution of uncontrolled NFB
prill tower exhaust (Plant C).
4-32
-------
100.0—1
50.0-
40.0-
30.0-
20.0-
100-
CO
z
O
cr
o
cc
LU
Q
LU
_l
O
DC
5.0
4.0
3.0-
2.0-
1.0-
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4 —
NOTE: THESE RESULTS REPRESENT AN
AVERAGEOFTHREERUNS.
~T
.5
1 1—i—i 1—i—i—i—i i i i r
5 10 15 20 30 40 50 60 70 80 85 90 95
98
CUMULATIVE PERCENT LESS THAN SIZE
70 2052-1
Figure 4-14. Particle size distribution of uncontrolled NFB
prill tower exhaust (Plant E).
4-33
-------
100.0-
50.0-
40.0-
30.0-
20.0-
co 10.0.
O
oc
O
DC
LU
5.0-
4.0-
5 3.0 -|
Z.OH
ec
<
O.
1.0-
.5
.4
3
2
AGRICULTURE GRADE
FEED GRADE
T
.5
1 T
10 15 20 30 40 50 60 70 80 85 90 95
98
CUMULATIVE PERCENT LESS THAN SIZE
70-2053-1
Figure 4-15 Particle size distribution of uncontrolled prill
tower exhaust (Plant F - industry data)o4
4-34
-------
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45
40
35
c 30
o
* 25
s_
O)
in
S 20
o
. 15
o
10
5
0
*-
Partial Preconditioning
Average Opacity - 7.16
33
35
13
4
2 i 0
1 1 r^ n
0-5 5.1- 10.1- 15.1- 20.1- 25.1- 30.1-
10 15 20 25 30 35
Intervals of Opacity (%)
45
40
35
c 30
•M
(O
Z 25
(/>
o 20
o
. 15
o
10
5
A
29
7
45
Full Preconditioning
Average Opacity =11.4
6
3
1 0
^^^^^^
0-5 5.1- 10.1- 15.1- 20.1- 25.1- 30.1-
10 15 20 25 30 35
Intervals of Opacity (%)
Figure 4-17. Histograms of six minute opacity averages for controlled
nonfluidized bed prill tower exhausts, Plant E.
4-36
-------
4.3.2 Emission Data for Fluidized Bed Prill Towers
Three fluidized bed prill towers are currently operating in the
United States and all are controlled to some degree. Industry data on
controlled emission levels at two of the three installations is summarized
in Table 4-4.
Industry data on uncontrolled emissions from Plant D's prill tower
generally agrees with EPA data. EPA tests at Plant D are summarized in
Appendix A, Tables A-40 through A-47. Both agricultural grade and feed
grade production were tested. These tests involved measurements on two
of eight scrubbers operated at this installation. The total emission
rate from all operating scrubbers was calculated by factoring each
scrubber emission valve by four. This assumes that the tested scrubbers
are representative of the remaining untested scrubbers. Velocity and
visible emission measurements show this assumption to be reasonable (see
Appendix A).
A histogram of the visible emission data collected during the
testing at Plant D is shown in Figure 4-18. The distribution of readings
changes slightly between agricultural and feed production, and the
average opacity is 4.5 percent higher during agricultural grade production.
Particle size distribution information was obtained at Plant D
during testing. Two tests (each consisting of three runs) were made for
both agricultural and feed grade production. This data is presented in
Figure 4-19. In general, feed grade production shows increases in
particle sizes over agricultural grade production similar to the trend
noted on nonfluidized bed prill towers.
4.3.3 Emission Data for Rotary Drum Granulators
Mass emission tests were conducted by EPA on three drum granulators.
At Plant A, granulator "A" was tested twice and granulator "C" was
tested once. During granulator "C" testing, a variety of factors which
potentially could affect test method accuracy were investigated and no
particle size or visible emissions were measured. At Plant B, one test
was conducted which included uncontrolled, controlled, visible, and
particle size emission measurements.
4-37
-------
c
o
o>
t/1
o
u_
O
o
35
25
20
15
10
5
0
•
.
0- 5.0-
4.9 9.9
7
Agricultural Grade
Avg. Opacity = 25.3
29
23 23
Zl
11
3
10 Q- 15.0- 20.0- 25.0- 30.0- 35.0- 4U.U-
14.9 19.9 24.9 29.9 34.9 39.9 44.9
Intervals of Opacity
35
30
25
•2 20
o 15
-a
o
o
O
10
5
13
1
32
12
Feed Grade
Avg. Opacity = 20.8
90
0 - 5.0- 10.0- 15.0- 20.0- 25.0- 30.0-
4.9 9.9 14.9 19.9 24.9 29.9 34.9
Intervals of Opacity
35.0-
39.9
4U.U-
44.9
Figure 4-18.
Histograms of six-minute opacity averages for
controlled FB prill tower exhaust (Plant D).
4-38
-------
o
a:
o
cc
UJ
a
LU
_1
o
i—
cc
<
a.
100.0-1
500-
40.0-
30.0-
200-
10.0-
5.0-
40-
3.0-
2.0-
1.0-
5-
4-
O AGRICULTURE GRADE, SCRUBBER A
^ AGRICULTURE GRADE, SCRUBBER C
D FEED GRADE, SCRUBBER A
O FEED GRADE, SCRUBBER C
NOTE. THESE RESULTS REPRESENT AVERAGES OF
THREE RUNS FOR EACH TEST.
5 10 15 20 30 40 50 60
CUMULATIVE PERCENT LESS THAN SIZE
~T
70
-1—I T
80 85 90
~r
95
98
70-2054-1
Figure 4-19. Particle size distribution of uncontrolled FB
prill tower exhausts (Plant D).
4-39
-------
In testing granulator "A" at Plant A, and Plant B very high removal
efficiencies (above 99.8 percent) were demonstrated. One reason for the
high efficiency of granulator scrubbers is the large particle sizes
found in granulator exhausts where several particle size tests were
conducted, showing that less than 1 percent of the total emissions in
granulator exhausts were less than 5 microns in size.
Opacity measurements on all tests were low. Opacities during tests
on granulator "A" at Plant A ranged from 0 to 5 percent. Opacities at
Plant B were between 5 and 10 percent.
4.3.4 Emission Data for Rotary Coolers
No EPA test data is available to determine controlled emission
rates from any of the devices used to control cooler emissions. Industry
has reported emission rates, however, and this data is summarized in
Table 4-5. An average of this data results in an emission rate of .035
kg/Mg (.07 Ib/ton) EPA tested the uncontrolled rotary cooler exhaust
at Plant C and measured emissions of 3.73 kg/Mg (7.45 Ib/ton). Plant C
personnel have measured controlled cooler emissions of .01 kg/Mg (.02
Ib/ton). According to this data, the mechanically aided scrubber used
at Plant C is achieving an overall efficiency of 99.7 percent.
A particle size test was also conducted on the uncontrolled cooler
exhaust at Plant C. As can be seen in Figure 4-20, the particles are
large, with less than 0.3 percent smaller than 10 microns.
Visible emissions measurements were conducted on the scrubber
outlets of rotary drum coolers at plants C and E. These measurements
are summarized in Table 4-3 and presented in Appendix A. A mechanically
aided scrubber is used to control cooler emissions at Plant C with the
average opacity reported to be 23 percent. Cooler emissions at Plant E
are controlled to an average 3 percent opacity by a packed bed wet
scrubber.
4.3.5 Emission Data for Bagging Operations
Mass emission test data are not available for fabric filters controlling
emissions from a urea bagging operation. However, regardless of the
type, baghouses can attain collection efficiencies greater than 99
4-40
-------
TABLE 4-5. SUMMARY OF COOLER CONTROLLED EMISSIONS (INDUSTRY DATA)
Type of
Control Device
Packed Tower60
Tray Type61
Packed Tower62
Mechanically63
Aided
u ». , . , - . .
Model
Buell Flyash
Sly
American Air
Filter,
Hydrofilter
American Air
Filter,
Rotoclone
Type W
Plant
Where
Used
H
I
E
C
Reported
Outlet Emission
Rate
Kg/Mg (Ib/ton)
.01-. 015 (.02-. 03)
•1 (.2)
.02 (.04)
.01 (.02)
Reported
Pressure
Drop
KPa (in. W.6.)
.25 (1)
Not Available
.25 (10)
Not Applicable9
Mechanically aided scrubber supplies power through intergral rotor.
-------
100.0-t
o
tr
o
tr
LLJ
Q
LU
_1
O
cc
<
Q.
50.0-
40.0-
30.0-
20.0-
10.0-
5.0-
40-
3.0-
2.0-
1.0-
NOTE: THESE RESULTS ARE AN AVERAGE OF THREE RUNS.
I
I ill
5 10 15 20
I I I I I
30 40 50 60 70
80 85 90
95
98
CUMULATIVE PERCENT LESS THAN SIZE
70 2055-1
Figure 4-20.
Particle size distribution of uncontrolled
cooler exhaust (Plant C).
4-42
-------
percent even on submicron particle sizes. Testing conducted by EPA on
baghouses used to control emissions in the non-metallic mineral industry
demonstrated efficiencies of 99.8 percent or better with no visible
emissions (zero percent opacity).33,34,35
Opacity measurements were made at Plant D to determine visible
emission levels from fabric filter controlled bagging operations.
Visible emissions were usually nonexistent. The average opacity during
this test was .05 percent.
4.4 EVALUATION OF CONTROL DEVICE PERFORMANCE
This section presents an evaluation of the emission data presented
in Section 4.3. This evaluation includes: 1) a general examination of
the data to determine relative accuracy and representativeness, and 2)
an assessment of the effects of changes in emission characteristics on
control device performance. As in the previous section, the discussion
is arranged by emission source.
4.4.1 Nonfluidized Bed Prill Towers
Available EPA test data consist of tests of nonfluidized bed prill
towers (producing agricultural grade urea) at Plants C and E as illustrated
in Figure 4-21. Plant C was tested during both agricultural and feed
grade production in April, 1979; however, the analysis was improperly
conducted and the data unusable. During a subsequent retest it was
possible to test emissions during agricultural grade production only.
At Plant E, feed grade emissions could not be measured since this plant
produces agricultural grade only. Thus, no EPA emission data for
nonfluidized bed prill towers producing feed grade product is available.
The two scrubber outlet emission tests (each consisting of three
test runs) at Plant E measured the lowest controlled emission level of
any prill tower tested by EPA. The two tests measured emission rates of
.0320 kg/Mg and .0220 kg/Mg (.0641 Ib/ton and .0440 Ib/ton). The
wetted fibrous filter demonstrated an average removal efficiency of 98.7
percent based on uncontrolled emissions measured simultaneously with the
first outlet emission test.
4-43
-------
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1-
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Test C: Plant C, nonfluidized bed, agricultural grade packed Test 0-1: Plant 0, fluidlzed bed, agricultural grade,
bed scrubber entrainment scrubber "AM
Test E-l: Plant E, nonfluldlzed bed, agricultural grade, Test D-2: Same as 0-1 except scrubber "C"
wetted fibrous filter, partial preconditioning
Test 0-3: Same as 0-1 except feed grade
Test E-2: Same as E-l except full preconditioning
Test D-4: Same as 0-2 except feed grade
Figure 4-21. Emission levels from controlled prill tower, EPA tests
-------
This removal efficiency is confirmed by the performance curve
provided by the control device manufacturer. This fractional efficiency
curve, based on pilot plant evaluations of a prototype wetted fibrous
filter unit and presented earlier as Figure 4-10, gives the particle
removal efficiencies for various size ranges of particles. Using these
removal efficiencies and the uncontrolled particle size distribution
measured at Plant E (Figure 4-14), a removal efficiency of 98.4 percent
is predicted. This compares favorably with the 98.7 percent actually
measured.
An independent test conducted by company personnel at Plant E,
under conditions similar to those during EPA testing, confirmed the
results obtained during EPA testing. They measured controlled emissions
of .0271 kg/Mg (.0541 Ib/ton) (see Table 4-4), which is very close to
the EPA measured emissions.
A comparison of controlled emissions between Plant E and Plant C
reveals considerably higher emissions at Plant C. These higher emissions
are believed to be the results of two factors. First, the wetted
fibrous filter used at Plant E operates at a much higher pressure drop
and is specifically designed for control of particles less than 1 micron.36
In contrast, packed bed scrubbers are typically used for control of
gaseous pollutants or in situations where the particles tend to be
larger than 5 micron. Secondly, the prill tower exhaust at Plant C
contains a much higher percentage of fine particles. A comparison of
the internal air velocities between the two prill towers reveals considerable
differences which might account for the change in particle size. The
velocity in Plant C's tower is approximately .365 tn/s (1.2 ft/sec),37
while the velocity in Plant E's tower is approximately 1.29 m/s (4.24
ft/sec). Higher airflow increases the entrapment of particulates and
may also increase the generation of small particles. A higher tower
airflow would increase the turbulence near the molten prill resulting in
the formation of small, solid urea particles.
EPA tests are usually conducted on facilities which appear to be
using the best available control technology. Plant C was selected
4-45
-------
for testing because at the time of the test, it was the only plant known
to operate a nonfluidized bed prill tower which offered reasonable
sampling locations. Mistakes in the sample analysis during the first
test at Plant C resulted in erroneous data. By the time it was conclusively
determined that this data was faulty, the test at Plant E was in the
planning stage. Therefore, the retest at Plant C was limited to the
minimum necessary to confirm the errors in the initial test. Therefore,
only controlled emissions during agricultural grade production were
retested.
As mentioned earlier, no EPA mass emission data is available to
quantify either controlled or uncontrolled nonfluidized bed prill tower
emissions during feed grade production. However, a number of factors
infer that feed grade emissions are easier to control compared to
agricultural grade emissions. First, all available particle size data
shows that larger particles are generated during feed grade production.
Larger particles are more effectively removed by control systems than
small particles. A comparison of the size distributions measured at
Plant C during both grades of production (Figure 4-13) shows a clear
shift toward larger particles during feed grade production. This shift
is confirmed by a similar shift noted for fluidized bed prill towers
(Figure 4-10) and industry particle size tests of a nonfluidized bed
prill tower (Figure 4-15). Secondly, available data indicates feed
grade emissions are probably lower than agricultural grade emissions.
The only direct comparison between uncontrolled emission rates during
both types of production using a nonfluidized bed prill tower is industry
tests at Plant F (see Table 3-3). These tests measured 15 percent
higher uncontrolled emissions during feed grade production. However,
due to problems frequently encountered in testing prill towers and
differences in test methods, industry data is difficult to quantify.
The particle size data from this same plant indicates the control device
efficiency would be improved because of the larger feed grade particulate.
Increased efficiency would more than compensate for the slightly higher
uncontrolled emissions during feed grade production. EPA tests of a
4-46
-------
fluidized bed prill tower showed a 40 percent decrease in emissions in
switching from agricultural to feed grade production. Since both types
of prill towers are generally operated in a similar manner, with similar
reductions in airflow during feed grade production, this decrease in
emissions is believed to be typical for prill towers producing both
product grades.
Another variable believed to effect the uncontrolled emission
characteristics of nonfluidized bed prill towers is ambient temperature.
Available data indicates that colder temperatures promote the formation
of smaller particles in the prill tower exhaust.39'40 Since smaller
particles are more difficult to remove, the efficiency of control
devices used on prill towers tends to decrease with lower temperatures.
This can lead to higher controlled emission levels while prill towers
are operated during cold weather.
The physical mechanism responsible for this shift toward smaller
particles is not clearly understood. Available industry and EPA particle
size data indicates the existence of two distinct populations of particles
in prill tower exhausts. One population is greater than 5 micron in
size and is composed of small micro prills and prill fragments. This
population is believed to be formed as the molten urea separates into
droplets at the melt distributor and as the semi-solid prills strike
each other and the prill tower walls. The second population is smaller
than 5 micron and is believed to result from the condensation of urea
vapor into small crystals. Microscopic examination of the small particles
reveals a crystalline structure, similar in appearance to a snowflake.41
Urea vapor pressure data indicates that sufficient urea is present in
the vapor state in a prill tower to account for the small particle
42
emissions. The growth of urea crystals is directly affected by the
rate at which the urea vapor is cooled, while this rate is directly
affected by the temperature of the air drawn into the prill tower.
During cold weather the vapor is quickly cooled from melt temperature to
the exhaust duct temperature, while in warm weather the transition is
more gradual. Rapid cooling does not allow time for the formation of
4-47
-------
larger crystals in the saturated urea vapor. Instead, many small crystals
are formed as the saturated urea vapor cools.
Personnel at Plant E conducted fifteen particle size tests during a
control device evaluation program. This program involved the ducting
of a slipstream from the prill tower exhaust to a ground mounted sampling
location. Because the sampling technique did not account for segregation
of particles within the slipstream due to flow direction changes caused
by the ducting, only the fraction of particles 5 micron in size are in
size considered in the following discussion. The effect of this exclusion
on the final controlled emission levels presented later is negligible
since prill tower control devices typically remove nearly all particles
of size larger than 5 micron.
Ambient temperature during these fifteen tests ranged from 27
degrees F to 70 degrees F. Histograms of the two tests representing the
highest and lowest temperatures are presented in Figure 4-21 and illustrate
the increased fraction of particles in the smaller size ranges during
cold ambient temperatures. This general trend is evident in all fifteen
tests. Figure 4-22 presents a plot of mean particle size vs. ambient
temperature for all fifteen tests. Although some scatter is evident,
there is clear indication that temperature influences the size of particles
in prill tower exhausts.
The effect of this shift in particle size on the efficiency of the
wetted fibrous filter scrubber is illustrated in Figure 4-23. Two
approaches were used in determining this trend. The first approach
involves using each of the fifteen particle size tests in conjunction
with the fractional efficiency data presented earlier in Table 4-13 to
predict the efficiency for each specific particle size distribution.
The individual data points in Figure 4-23 represent this approach. The
second approach, represented by the solid line in Figure 4-23, involves
assuming a log-normal distribution for the sub 5 micron particles in
prill tower exhausts. Nearly all fifteen actual particle size distributions
fit the log-normal distribution. Furthermore, several authors indicate
that particle sizes are frequently log-normally distributed. ' '
4-48
-------
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Figure 4-22 Variation in particle size (sub 5 _um mean) with respect to
ambient temperature (industry data)
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80
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Figure 4-23. Efficiency of wetted fibrous filter as a function of ambient temperature
-------
With this assumption, it is possible to calculate the particle size
distribution for any temperature by varying the mean in accordance with
the trend line in Figure 4-22.
The preceding discussion has centered on the effect of temperature
on particle sizes. Temperature may also affect the quantity of emissions,
Particle concentration data obtained during the fifteen particle size
tests at Plant E shows that concentration of particles in the prill
tower exhaust is relatively constant with respect to temperature at
approximately .039 g/m (.017 gr/acfm). However, prill tower operators
typically cut back airflows during cold weather conditions to save fan
power since less of the colder air is required for adequate cooling of
the prills. From heat transfer considerations, it is possible to
predict this cutback. The results of these calculations are presented
in Figure 4-24 and agree, in general, with conversations with industry.
Finally, Figure 4-25 presents estimated outlet emissions as a
function of the ambient temperature. The prill tower configuration at
Plant E was used as a basis for this estimate. Once again, the data
points represent actual particle size tests while the trend line was
derived through the use of the log-normal distribution model. This plot
indicates a considerable increase in controlled emissions as temperature
drops.
4.4.2 Fluidized Bed Prill Towers
Controlled and uncontrolled emissions during both agricultural and
feed grade production were tested by EPA at the fluidized bed prill
tower at Plant D and are illustrated in Figure 4-21. Emissions of .392
kg/Mg (.785 Ib/ton) and .240 kg/Mg (.479 Ib/ton) were measured during
agricultural grade and feed production respectively. Control device
efficiency in both tests was approximately 86 percent. The measured
efficiencies confirm efficiencies predicted by particle size data and
efficiency curves for the entrainment scrubbers.
A similar shift toward smaller particles during cold weather might
be expected to occur in fluidized bed prill towers as discussed for
nonfluidized bed prill towers. At present, it is impossible to quantify
4-51
-------
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Ambient Temperature (degrees F)
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80
90
Figure 4- 24. Estimated airflow cutback as a function of ambient temperature
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(cutbacks as per previous figure)
.039 g/mj (.017 gr/dscf)
(constant with temperature)
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-------
to quantify a shift since particle size data for different temperatures
is not available.
4.4.3 Rotary Drum Granulators
Four EPA tests of three granulator/scrubber units at Plant A are
illustrated in Figure 4-26. Two of these tests (granulator scrubber
unit "A") measured controlled emission levels of .119 kg/Mg (.238 Ib/ton),
.111 kg/Mg (.221 Ib/ton), and the third test (granulator/scrubber "B"
had similar emissions of .114 kg/Mg (.228 Ib/ton). The fourth test
(granulator/scrubber unit "C") however, measured controlled emissions of
.378 kg/Mg (.755 Ib/ton). Unfortunately, no uncontrolled emission data
are available for this test and thus it is impossible to determine
whether the higher emissions are due to differences in uncontrolled
emission characteristics or lower control device efficiency.
According to Plant A personnel, the granulator/scrubber Unit A is
virtually identical to the Unit C. However, differences in visible
emissions between the units have been noticed since start-up with Unit C
emitting a plume of higher opacity. The plant has not investigated the
problem since both units are well below state emission standards and
have a high rate of urea recovery (99.9 and 99.7 percent recovery).
Concerning the reason(s) for the difference, plant personnel indicate
lower scrubber efficiency is most likely. They speculated that the
internal scrubber baffles may be misaligned. Based on these observations,
it appears that units "A" and "B" at Plant A are representative of a
granulator/scrubber unit operating at peak efficiency.
4.4.4 Rotary Drum Coolers
Controlled mass emission data submitted by several plants operating
coolers indicates controlled emissions that range from .01 to .1 kg/Mg
(.02 to .2 Ib/ton) with an average emission of .035 kg/Mg (.07 Ib/ton).
These emission levels are generally confirmed by predicted controlled
emissions using uncontrolled EPA emission data and control device
performance curves. A single tray type scrubber operating at a pressure
drop of .375 kPa (1.5 in. W.G.) would remove approximately 98.9 percent
of the particles in the cooler exhaust. An entrainment scrubber operating
4-54
-------
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Figure 4-26. Emission levels from controlled granulator exhausts.
4-55
-------
at an overall 1.25 to 1.50 kPa (5 to 6 in. W.G.) pressure drop would
perform at approximately 99.6 percent efficiency. These high efficiencies
are possible because of the large particles in cooler exhausts. Using
these efficiencies and EPA uncontrolled mass emission measurements,
controlled emissions of .043 and .016 kg/Mg (.086 Ib/ton and .031 Ib/ton)
are estimated for a cooler controlled with a tray type and an entrainment
scrubber respectively.
4-56
-------
4.4 REFERENCES
1. Telecon. Curtin, T., GCA Corporation, with J. Haggenmacher, Triad
Chemical. February 22, 1979. Conversation about prill towers.
2. Trip report. Jennings, M.S., Radian Corporation, to file.
June 11, 1980. 6 p. Report of January 31, 1980 visit to Reichhold
Chemical in St. Helen, Oregon, p. 4.
3. Trip report. Capone, S.V. and R.R. Hall, GCA Corporation, to
Noble, E., EPA:ISB. May 25, 1978. 5 p. Report of visit to
CF Industries in Donaldsonville, Louisiana, p. 4.
4. Memo from Brown, P., GCA Corporation, to file. December 7, 1979.
6 p. Summary of information about use of baghouses at urea plants.
5. Reference 4, 6 p.
6. Reference 4, 6 p.
7. Telecon. Stelling, J., Radian Corporation, with Lerner, B.J., BECO
Engineering. June 30, 1980. Conversation about BECO scrubbers on
prill tower emissions.
8. Theodore, L. and A.J. Buonicore. Industrial Air Pollution Control
Equipment for Particulates. Cleveland, CRC Press, 1976. p. 193.
9. Bethea, R.M. Air Pollution Control Technology. New York, Van
Nostrand Reinhold Company, 1978. p. 275.
10. Reference 8, p. 193.
11. Reference 9, p. 275.
12. Reference 8, p. 193.
13. Letter and attachments from Lerner, B.J., BECO Engineering Company,
to Sherwood,2C., EPA:ISB. February 2, 1978. 12 p. Information
about the "V4" scrubber, pp. 3-4.
14. Reference 13, p. 2.
15. Reference 13, p. 2.
16. Reference 9, pp. 294-295.
17. Reference 9, p. 285.
4-57
-------
18. Calvert, S. How to Choose a Participate Scrubber. Chemical
Engineering. 8£: 54-68. August 29, 1977. p. 58.
19. Reference 9, pp. 289-290.
20. Reference 9, p. 290.
21. Reference 9, p. 290.
22. The Mcllvaine Scrubber Manual, Volume I. Morthbrook, Illinois, The
Mcllvaine Company, 1974. Chapter III, Section 10.54, p. 70.0.
23. Reference 18, p. 57.
24. Reference 18, p. 57.
25. Reference 18, p. 58.
26. Impinjet Gas Scrubbers. Catalog No. 151. Cleveland, The W.W Sly
Manufacturing Company, p. 2.
27. Reference 2, p. 5.
28. Telecon. Jennings, M., Radian Corporation, with Brady, J.,
Anderson 2000. September 22, 1980. Conversation about fractional
efficiency for CHEAP unit.
29. The CHEAP System for Ultrafine Particle Emission Control. Bulletin
No. 75-90004B. Atlanta, Anderson 2000, Inc. October 12, 1978.
p. 2.
30. Kraus, M.N. Baghouses: Separating and Collecting Industrial
Dusts. Chemical Engineering. 86^(8):94-106. April 9, 1979.
31. Letter and attachments from Cramer, J.H., Reichhold Chemicals,
to Goodwin, D.R., EPA:ESED. December 1, 1978. 43 p. Response to
section 114 letter.
32. The National Air Pollution Control Administration. Control
Techniques for Particulate Air Pollutants. (Prepared for U.S.
Department of Health, Education and Welfare.) Washington, D.C.
Publication No. AP-51. January 1969. pp. 123-125.
33. Clayton Environmental Consultants. Emission Study at a Feldspar
Crushing and Grinding Facility. (Prepared for U.S. Environmental
Protection Agency.) Research Triangle Park, N.C. EMB Report
76-NMM-l. September 27-29, 1976. 38 p.
4-58
-------
34. Engineering-Science, Inc. Air Pollution Emission Test at Kentucky
Stone Company. (Prepared for U.S. Environmental Protection Agency.)
Research Triangle Park, N.C. EMB Report 75-STN-3. 1975. 33 p.
35. Jackson, B.L. and P.J. Marks (Roy F. Weston, Inc.) Source Emissions
Test Report for Engelhard Minerals & Chemicals Corporation.
(Prepared for U.S. Environmental Protection Agency.) Research
Triangle Park, N.C. EMB Report 78-NMM-6. July 1978. 34 p.
36. Reference 29, p. 1.
37. Letter and attachments from Swanburg, J.D., Union Oil Company, to
Goodwin, D.R., EPA:ESED. December 20, 1978. p. 9. Response to
Section 114 letter.
38. Reference 2, p. 3.
39. Cramer, J.H. (Reichhold Chemicals, Inc.) Urea Prill Tower Control -
Meeting 20% Opacity. (Presented at the Fertilizer Institute Environmental
Symposium. New Orleans. April 1980.) p. 2.
40. Letter and attachments from Skinner, D., Radian Corporation, to
Jennings, M.S., Radian Corporation. November 4, 1980. 114 p.
Information about particulate emissions from urea and ammonium
nitrate prilling towers.
41. Telecon. Jennings, M., Radian Corporation, with Cramer, J., Reichhold
Chemical. August 11, 1980. Conversation about prill tower emissions.
42. Reference 40, p. 5.
43. Trip report. Jennings, M.S., Radian Corporation, to file. November
7, 1980. 31 p. Report of October 16, 1980 visit to Reichhold
Chemical in St. Helens, Oregon.
44. Kottler, F., The Distribution of Particle Sizes. Journal of the
Franklin Institute. ^50:339-356. October 1950. p. 350.
45. Herdan, G. Small Particle Statistics, Second Edition. London,
Butterworth and Company, 1960.
46. Memo from Brown, P., GCA Corporation, to file. December 21, 1979.
4 p. Summary of information about wet scrubbers at urea plants.
47. Memo from Bornstein, M., GCA Corporation, to file. December 6,
1979. 3 p. Solid urea manufacturing industry survey summary.
4-59
-------
48. Memo from Bornstein, M.I., GCA Corporation, to file. October 26,
1979. 6 p. Summary of urea manufacturing plant information.
49. Letter and attachments from Thomson, J.W., Mississippi Chemical
Corporation, to Bornstein, M.I., GCA Corporation. July 17, 1978.
10 p. Information about MCC low-emission technology for ammonium
nitrate neutralizers.
50. Letter and attachments from Griec, J., American Air Filter, to
Stelling, J., Radian Corporation. April 18, 1980. p. 3. Information
about available equipment and efficiency.
51. Reference 26, p. 2.
52. Reference 26, p. 2.
53. Western Precipitation Gas Scrubbers: Type "D" Turbulaire Scrubber.
Publication No. S-100. Los Angeles, Joy Manufacuting Company,
1978. p. 4.
54. Reference 53, p. 2.
55. Reference 29, p. 3.
56. Brady, J. D., et al. A New Wet Collector for Fine Particle Emission
Control. (Presented at the 69th Annual Meeting of the American
Institute of Chemical Engineers. Chicago. June 16, 1976. p. 57.
57. Reference 56, p. 54.
58. Roeck, D.R. and R. Dennis. (GCA Corporation.) Technology Assessment
Report for Industrial Boiler Applications: Particulate Collection.
(Prepared for U.S. Environmental Protection Agency.) Research
Triangle Park, N.C. Publication No. EPA-600/7-79-178h. December 1979.
p. 49.
59. Letter and attachments from Bogatko, H.F., Atlas Powder Company, to
Capone, S., GCA Corporation. July 31, 1978. 16 p. Testing information,
pp. 10-11.
60. Trip report. Bornstein, M.I. and S.V. Capone, GCA Corporation, to
Noble, E.A., EPA:ISB. June 20, 1978. 8 p. Report of visit to
Mississippi Chemical Corporation in Yazoo City, Mississippi.
61. Telecon. Bornstein, M., GCA Corporation, with Segar, T., N-Ren
Corporation. June 2, 1978. Conversation about two plants.
62. Reference 31, p. 7.
4-60
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63. Reference 37, p. 9.
64. Stockham, J.D. and E.G. Fochtman (ed.s). Particle Size Analysis.
Ann Arbor, Ann Arbor Science Publishers, 1977.
65. Reference 2, pp. 3-5.
66. Telecon. Stelling J., Radian Corporation, with Boggan, J., Agrico
Company. July 30, 1980. Conversation about EPA tests result
differences, as revised by J. Boggan's comments.
4-61
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5.0 MODEL PLANTS AND CONTROL ALTERNATIVES
Model urea plants and control alternatives are defined in this
chapter. The model plants are chosen to be representative of solids
producing plants in the urea industry. The model plants and control
alternatives are used in subsequent chapters as the basis for analysis
of the environmental and economic impacts associated with control of
particulate emissions from sources in the urea industry.
Section 5.1 describes the model plants in terms of process configuration,
plant capacity, operating hours, raw material requirements, and utility
requirements. Section 5.2 defines the existing level of control (ELOC)
on each emission source. Section 5.3 describes the control options for
each source, and Section 5.4 defines the control alternatives for each
model plant.
5.1 MODEL PLANTS
Process operations used in urea manufacturing include urea solution
production, solution concentration, solids formation, solids finishing
and solids handling. Urea plants differ in process configuration, plant
capacity, and product type. In order to account for this variability,
ten model plants were selected based on the present mix of process
configurations and plant sizes in the industry. Table 5-1 identifies
the solids formation process, plant capacity, and product type for each
model plant. Process and control device flow diagrams for each model
plant are presented in Figures 5-1 and 5-2. Further information con-
cerning the control options and emission characteristics of each model
plant is contained in Section 5.2.
5.1.1 Process Confiqurations
Four solids production techniques are currently in use in the urea
industry: nonfluidized bed prilling, fluidized bed prilling, drum
granulation, and pan granulation. However, only one pan granulator is
5-1
-------
TABLE 5-1. UREA MODEL PLANTS
CJl
I
ro
Model
No.
1
2
3
4
5
6
7
8
9
10
Plant
Capacity
Mg/day
(ton/day)
182
(200)
726
(800)
1090
(1200)
182
(200)
726
(800)
1090
(1200)
182
(200)
363
(400)
726
(800)
1090
(1200)
Process
Emission Diagram
Configuration Sources Figure
Non-fluidized prill Prill Tower
tower plant producing
agricultural grade Cooler 5-l(a)
prills. Supplementary
cooling required.
Tluidized bed prill
tower plant producing
agricultural grade prills. Prill Tower 5-l(b)
No supplementary cooling
required.
Same as 4 except Prill Tower 5-2(a)
feed grade.
Granulation Plant Granulator 5-2
Emission
Characteristics
Table
5-7
5-8
5-9
5-10
5-11
5-12
5-13
5-14
5-15
5-16
-------
ELOC - 0.8 kg/Hg (1.6 Ib/ton)
Option 1 - 0.28 kg/Mg (0.57 Ib/ton)
Option 2 - 0.04 kg/Hg (0.08 Ib/ton)
ELOC - 0.1 kg/Hg (0.2 Ib/ton)
Recycle to
Concentration"
Process
Melt
( 99.51 Urea)"
FIBROUS FILTER
OR ENTRAINMEHT
SCRUBBER
A
i
TRAY TYPE
SCRUBBER
Scrubber Llminr
Uncontrolled
Emissions
1.9 kg/Hg (3.8 )g/ton)
NFB PRILL
TOWER
Uncontrolled
Emissions
3.9 kg/Hg (7.8 Ib/ton)
Prills
(a) Nonfluldlzed bed prill tower, agricultural grade Model Plants 1-3
101 Bag
storage and
shipment
. 901 Bulk storage
and shipment
Scrubber Liquor
Recycle to
Concentration
Process
Kelt
( 99.51 Urea)
ELOC - 0.6 kg/Mg (1.2 Ib/ton)
Option 1 - 0.47 kg/Mg (0.93 Ib/ton)
Option 2 - 0.06 kg/Hg (0.12 Ib/ton)
FIBROUS FILTER OR
EHTRAINHEHT
SCRUBBER
A
Uncontrolled
Emissions
3.1 kg/Mg (6.2 Ib/ton)
FB PRILL
TOWER
Prills
10* Bag
storage and
shipment
90S Bulk
storage
and shipment
(b) Fluldlzed bed prill tower, agricultural grade. Model Plants 4-6.
Figure 5-1. Process diagrams for Model Plants 1-6.
5-3
-------
Scrubber Liquor
Recycle to •*
Concentration Process
Melt
( 99.51 Urea)
Scrubber
Liquor -«—
Recycle to
Concentration
Process
MeU
( 99.51 Urea)
ELOC - .8 kg/Mg (1.6 Ib/ton)
Option I - 0.27 kg/Mg {0.54 Ib/ton)
Option Z - 0.04 kg/Mg (0.08 Ib/ton)
FIBROUS FILTER OR
ENTRAHWEMT SCRUBBER
A
Uncontrolled
Emissions
1.8 kg/Mg (3.6 Ib/ton)
PRILL TOMER
Prills
(a) Prill tower, feed gnde. Model Plant 7
ELOC - 0.12 kg/Mg (0.23 Ib/ton)
EHTRAINrlENT
SCRUBBER
Emissions Uncontrolled
120 kg/Mg (240 Ib/ton)
ROTARY DRUM
GRANULATOR
Granules
__ 10J Bag
storage and
shipped
901 Bulk storage
-*• and shipment
101 Bag
storage and
shipment
__ 90S Bulk storage
and shipment
(b) Granulator, Model Plants 8-10
Figure 5-2. Process diagrams for Model Plants 7-10.
5-4
-------
currently in operation in the United States and further expansion of
granulator production is expected to be met through the use of drum
granulators. Therefore, model plants were chosen to represent three
types of solid production techniques: nonfluidized bed prilling,
fluidized bed prilling, and drum granulation.
Model Plants 1 through 7 represent prilling plants utilizing a
single prill tower. Model Plants 1 through 3 and 7 utilize nonfluidized
bed prill towers and Model Plants 4 through 6 use fluidized bed prill
towers. For the nonfluidized bed prilling plants, supplementary cooling
of the prills is assumed to be provided by a rotary drum cooler although
some plants currently operating do not use a supplementary cooling
device.
Except for Model Plant 7, all model prilling plants produce agricultural
grade product. These plants may also produce feed grade product through
a change in melt distributor and a reduction in air flow rates. However,
feed grade towers are assumed to have lower emissions. For the purpose
of presenting conservative economic and environmental impact analyses
in subsequent chapters, it is assumed that Model Plants 1 through 6
produce agricultural products exclusively.
Model Plant 7 represents a prilling facility dedicated to feed
grade production only. This plant was selected to account for the
possibility of granulators continuing to displace prill towers for
agricultural grade production, and the subsequent need for prill towers
to produce feed grade solids exclusively. This possibility could arise
because, at the present time, feed grade solids are not produced by
granulation.
Model Plants 8 through 10 use rotary drum granulators for solids
formation. In contrast to prilling plants which use a single prill
tower of varying capacity, granulator plants generally use multiple
grenulator trains of a single uniform capacity to achieve total plant
production.
5.1.2 Plant Capacities
Currently, prilling plants producing agricultural grade urea range
in capacity from 167 Mg/day (186 tons/day) to 1150 Mg/day (1270 tons/day).
5-5
-------
Using this range as a guide, a small model prilling plant of 182 Mg/day
(200 tons/day) capacity and a large model prilling plant of 1090 Mg/day
(1200 tons/day) capacity were selected. Because this size range is
considerable, an intermediate size model prilling plant of 726 Mg/day
(800 tons/day) was selected. The choice of an intermediate size nearer
the larger plant size reflects the tendency for facilities to be large
in order to take advantage of economies of scale.
Only one size of model feed grade prilling plant was selected. The
two plants currently producing feed grade exclusively are small. Both
produce less than 217 Mg/day (240 tons/day). Therefore, a single small
feed grade model plant of 182 Mg/day (200 tons/day) capacity was selected.
Granulator plant sizes vary according to the number of granulators
operated at any particular plant location. The number of granulators
currently operated at one location varies between one and seven.
However, many of these plants brought granulators on line in increments.
Model Plants 8 through 10 utilize one, two and three 363 Mg/day (400
tons/day) capacity granulator trains respectively to represent a range
of existing plant capacities.
5.1.3 Operating Hours
Urea plants usually operate continuously except for scheduled
maintenance shutdowns and unscheduled equipment failures. Total shut-
down time is estimated at nine weeks per year. Thus, each model plant
operates 43 weeks/year, 7 days/week, and 24 hours/day for a total production
time of 7224 hours/year.
5.1.4 Raw Material and Utility Requirements
In each of the model plants, ammonia and carbon dioxide are processed
to form an aqueous urea solution which is then concentrated to 99+
percent urea. This molten urea is mixed with about 0.4 weight percent
formaldehyde additive and then solidified either by prilling or granulation.
The purpose of the formaldehyde additive is to prevent caking and breakage
of the solid product. Because the model plants use the same types of
solution production and concentration equipment and produce similar
products (99+ percent solid urea with 0.4 percent formaldehyde additive),
5-6
-------
they have the same basic raw material requirements per unit of urea
product. Thus, the annual raw material requirements for the four sizes
of model plants given in Table 5-2 are used for all model plants.
Also presented in the table are utility requirements for the various
sizes of model plants. These requirements represent the total utility
needs of the entire urea manufacturing plant, including solution synthesis
and concentration processes. Electrical energy and steam requirements
vary slightly between prilling plants and granulation plants. However,
the difference is relatively small compared to the total plant energy
usage. Therefore the utility requirements listed in Table 5-2 are used
for all model plants.
5.2 DETERMINATION OF EXISTING CONTROL LEVELS
The Existing Level of Control (ELOC) is that level of control which
is currently applied to emissions from solid urea producing processes in
the urea industry. Table 5-3 summarizes the ELOC chosen for the emission
sources in the urea industry. Consideration is first given to current
state regulations which apply to the emission sources. State regulations
usually define the primary constraint on emissions. However, for many
emission sources, a sizeable discrepency exists between actual emission
levels and those levels allowed by state regulations.
Several factors are responsible for the disparity between the
allowable state emission levels and measured industry emissions. First,
the test method used by state and industry personnel varies from state
to state and may be considerably different from the method used in this
study. The sampling procedures which have been endorsed and used by the
States include EPA's Method 5, the American Society of Mechanical
Engineers' Performance Test Code (PTC) 27, and modifications of these
procedures. The collection efficiencies of the various sampling procedures
depend upon such factors as the type of filter used, the temperature of
the filter, whether condenslble emissions are included, and the sample
recovery and analytical procedures. Even when two state emission standards
are identical, one standard can effectively be more stringent when the
sampling procedure specified collects a higher percentage of emissions.
5-7
-------
TABLE 5-2. RAW MATERIAL AND UTILITY REQUIREMENTS
FOR MODEL PLANTS1'3
en
I
CO
Plant
Size
My/ day
(tons/day)
182
(200)
363
(100)
726
(800)
1090
(1200)
Annual
Production
Mg/yr
(tons/yr)
54,700
(60,200)
109,000
(120,000)
219,000
(241,000)
328,000
(36i,000)
•
Aninonia
Consumption
Mg/yr
(tons/yr)
31,700
(34,900)
63,200
(69,600)
127,000
(140,000)
190,000
(209,000)
Ca rbon
Dioxide
Consumption
Mg/yr
(tons/yr)
41 ,300
(45,500)
02,300
(90,600)
165,000
(182,000)
248,000
(273,000)
Formaldehyde
Consumption
Mcj/yr
(tons/yr)
219
(241)
436
(480)
075
(964)
1311
(1444)
Steam
Use
Mg/yr
(tons/yr)
79,300
(87,300)
158,000
(174,000)
317,000
(349,000)
475,000
(523,000)
Electricity
Use
TJ/yr
(Mw-hr/yr)
23.9
(6,620)
47.7
(13,200)
95.8
(26,500)
134.4
(39,700)
Cooling
Water Use3
ni3x!06/yr
(galxlO'Vyr)
3.98
(1,050)
7.91
(2,090)
15.9
(4,190)
23.8
(6,280)
Cool ing
Water Use"
m3/yr
(galx!0b/yr)
4090
(1.08)
8180
(2.16)
1640
(4,34)
24600
(6.50)
^circulated cooling water with 15°F rise across process
^Consumptive use of cooling water
-------
TABLE 5-3. SUMMARY OF EXISTING EMISSION LEVELS
en
I
Emission Source
Prill Towers
Agricultural Grade,
Nonfluidized Bed
Agricultural Grade,
Fluidized Bed
Feed Grade
(either fted type)
Rotary Drum Granulators
Rotary Drum Coolers
Uncontrolled
Emissions
kg/Mg
(Ib/ton)
1.9
(3.8)
3.1
(6.2)
1.8
(3.6)
103
(207)
3.9
(7.8)
Existing
Controlled
Emissions
kg/Mg
(Ib/ton)
.80
(1.6)
.60
(1.2)
.80
(1-6)
.115
(.230)
.10
(.20)
Control Equipment
Spray Tower
Scrubber
Spray Tower
Scrubber
Spray Tower
Scrubber
Entrainment
Scrubber
Tray- Type
Scrubber
Required
Removal
Efficiency
57.9%
80.6%
55.5%
99.9%
97.4%
-------
For example, a wet impinger collection device collects more participate
matter than a heated filter, which tends to vaporize some of the collected
particles. Therefore, given equal emission standards, the standard
requiring the wet impinger collector would be more stringent.
Secondly, sampling problems may compromise the state agency's
ability to determine compliance. As an example, prill towers commonly
exhaust through horizontal vents near the top of the prill tower.
Because of the tower height, an outlet stack is not needed to gain
acceptable dispersion of pollutants. Therefore, sampling locations are
either very poor or nonexistant. Faced with sampling sites which will
not yield accurate data, state officials find it difficult to use source
tests as a compliance tool. Instead, opacity readings are often used as
a measure of compliance.
Third, plants may find it to their advantage to control emissions
to lower levels than are required by state regulations. Urea collected
in scrubbers is recycled to the solution concentration process or to
solution fertilizer make-up. This recovery of urea offsets much of the
cost of control and may encourage a higher level of removal than is
required by state regulations.
Finally, in some cases it has been reported that opacity standards
are more difficult to meet than mass emission standards. In these
cases, industry may use a control device to meet opacity standards which
also reduces mass emissions well below the state regulation for mass
emissions.
A discussion of existing regulations is presented in Section
5.2.1. Existing levels of control are presented in the sections following
for prill towers, rotary drum granulators, and rotary drum coolers.
Where appropriate, the influence of the factors mentioned previously is
addressed.
5.2.1 Existing Emissions Limitations
Standards limiting particulate emissions are in effect in all 50
states. The regulations are of three types: opacity limits, exhaust
gas particulate concentration limits, and particulate emission limits
5-10
-------
calculated from process weights. The process weight regulations can
take the form of an allowable emission factor expressed as kg (Ib) of
particulate allowed per Mg (ton) of production. This section focuses on
the regulations in effect in 23 states in which urea plants are presently
located. In nearly all of the states, industrial source emissions are
limited by both opacity standards and process weight standards.
Table 5-4 presents a summary of opacity, concentration, and process
weight standards in the 23 states. In California, regulations differ
by district. The regulation presented in Table 5-4 for California are
those for the Los Angeles County Air Pollution Control District, which
are the most stringent.
Twenty of the 23 states in which urea plants are located have
standards limiting the opacity of an exhaust stream to 20 percent. This
is the most stringent opacity regulation affecting urea plants and is
also the typical regulation. A variation of the 20 percent opacity
standard is a standard which allows a source to exceed 20 percent for a
certain time period (for example, 6 minutes in any one hour). Two of 23
states in which urea plants are located have standards limiting opacity
to 40 percent and one state has a standard of 30 percent.
Almost all states have particulate emission rate limits based on
the amount of production. As shown in Table 5-4, particulate emissions
from a 363 Mg/day (400 tons/day) process are limited to a range of 5.19
to 71.44 kg/hr (11.41 to 257.20 Ib/hr), or 0.34 to 4.72 kg/Mg (0.69 to
9.43 Ibs/ton). Illinois and the Los Angeles County Air Pollution
Control District in California have the most stringent process weight
regulation limiting a 363 Mg/day (400 tons/day) process to emissions of
5.19 and 5.97 kg/hr (11.41 and 13.14 Ib/hr) respectively, or 0.34 to
0.40 kg/Mg (0.69 to 0.79 Ibs/ton).
In addition to the process weight rate equation ranging from state
to state, the method of enforcement also varies from state to state.
Some states consider each process or stack as a source. Other states
consider the allowable emission rate to apply to the combined emissions
from all the processes or stacks at the entire plant or from one building
5-11
-------
TABLE 5-4. EMISSIONS STANDARDS AFFECTING UREA PLANTS
cn
ro
State
Alaska
Alabama
Arkansas
California0
Florida
Georgia
Idaho
Illinois'1
Iowa
Kansas
Louisiana
Mississippi
Missouri
Nebraska
Hew York*
North Carolina
Ohio
Oklahoma
Oregon
Tennessee
Texas
Washington
Wyoming
•>
Opacity Grains/ft
(percent)
20 0.05
20
20
20
20
20
20
30
40
20
20 0.3
40
20 0.3
20
20 0.05
20
20
20 0.3
20 0.1
20 0.25
20
20 0.1
20
3
Grams/m Process weight regulation
P<;M ton/hFT^O ton/hr "
0.11
3.59(P)°-fi2 17<3,(p)0.16
0.050P0-8034 1.92P0'4234
3.59(P)°'62 17.31(P)°-16
3.59(P)°'62 17.3KP)0'16
4.10(P)°'67 (55.0(P)0-n)-40
2.54(P)0-534C 24.8(P)°-16C
4.10(P)°'67 (55.0(P)°'n)-40
4.10(P)0'67 (55.0(P)0-U)-40
0.69 4.10(P)°'67 (55.0(P)°-U)-40
4.10(P)°'67 (55.0(P)°-U)-40
0.69 4.10(P)°'67 (55.0(P)°-U)-40
4.10(P)0'67 (55.0(P)°-n}-40
0.11 3.91(P)0'r'' 39.(P)0t082-50
, 377(p)0.3067
4.10(P)°'67 (55.0(P)°-U)-40
0.69 4.10(P)°'67 (55.0(P)°-U)-40
0.23 4.10(P)0'57 (55. (P)°-U)-40
0.50 3.59(P)°'62 17.31(P)°-16
3 ,2(p)0.9B5 25.4(p)0.287
0.23
3.59(P)°'62 17.31(P)°-16
Allowable
Partlculate
Emissions
In Ib/hr for
400 ton/day
process
20.54
157.20
13.14
20.54
20.54
27.00
11.41
27.00
27.00
27.00
27.00
27.00
27.00
25.74
22.22
27.00
27.00
27.00
20.54
49.85
20.54
Allowable
Parttculate
Emissions
In kg/hr for
363.6 Mg/day
process
9.43
71.44
5.97
9.34
9.34
12.27
5.19
12.27
12.27
12.27
12.27
12.27
12.27
11.70
10.10
12.27
12.27
12.27
9.34
22.65
9.34
Based on 24 hour operation.
Process weight regulations for Arkansas apply to production rates of
Based on Los Angeles county APCD process weight rate table.
P^SlO Ib/hr and
Ib/hr, respectively.
-------
at the plant. The most typical interpretation used is the first method
which is also the less stringent of the two.
Because the state process weight equations are nonlinear with
respect to production, the allowable emission factor (kg/Mg or Ib/ton)
changes with different plant sizes. Table 5-5 presents the allowable
emissions for various sizes of plants by state, for the states with
solid urea production capacity. Also included at the bottom of the
table are the average emission limitations weighted by total solid
production, prill production, and granule production respectively. If
the state process weight regulations were the only factor affecting
industry emissions, it would be expected that the existing level of
control (ELOC) could be approximated by these weighted averages.
5.2.2 ELOC of Nonfluidized Bed Prill Towers Producing Agricultural
Grade Prills
Industry data presented in Chapter 3 indicates varying uncontrolled
emission rates of .39 - 1.79 kg/Mg (.78 - 3.58 Ib/ton) for nonfluidized
bed prill towers. Although much of this variability can be attributed
to actual differences in uncontrolled emissions, the difficulties
involved in obtaining accurate emission measurements of prill towers
also play a role. These difficulties include:
- Low particle concentration
- Poor or nonexistant stack sampling locations
- Hygroscopic nature of urea particles
- Dissociation of urea particles at high
temperatures encountered in collection filters
The variability in emissions, in conjunction with the variability
in state regulations, results in differing levels of control in the
industry. Seven of fifteen existing nonfluidized bed prill towers
utilize control devices, while the rest are uncontrolled. A new prill
tower may or may not require a control device to meet applicable state
regulations depending on the particular situation.
For the purpose of this analysis, an emission level of 0.8 kg/Mg
(1.6 Ib/ton) was chosen to represent the ELOC for nonfluidized bed prill
5-13
-------
TABLE 5-5. ALLOWABLE EMISSIONS BY PLANT SIZE (Metric Units)
182 Mg/day 364 Mg/day
737 Mg/day
kg/hr "kg/Mg kg/hr kg/Mg kg/hr
Alabama
Alaska
Arkansas *
Cal ifornia
Georgia
Iowa
Kansas
Louisiana
Mississippi
Missouri
New York
Ohio
Oregon
Tennessee
Texas
Wyomi ng
Straight Average
Weighted Average
Weighted Average c
Prills only
'-.'eiahted. Average u
Granules only
a
b
6.08 .803 9.34 .617
53.32 7.036 71.5 4.717
4.95 .654 6.01 .397
6.08 .802 9.34 .617
7.71 1.019 12.27 .810
M u • M
UN M U
• * • •
II U U II
7.36 .971 11.70 .772
7.71 1.019 12.27 .810
" " " "
6.08 .802 9.34 .617
11.45 1.511 22.7 1.496
6.08 .802 9.34 .617
7.29 .96 11.90 .79
7.30 .97 11.52 .76
7.10 .94 11.16 .74
7.65 1.C1. 12.15 .80'
* This state defines an emission source
emissions for the entire plant while
define an emission source as a single
Therefore, Arkansas was not included
or weighted averages.
Straight arithmetic average
Weighted average based on percentage of
13.79
95.8
7.06
13.79
18.59
N
"
"
"
18.61
18.59
H
13.79
31.6
13.79
17.66
17.22
16.56
18.38
~
as all
kg/Mg
.455
3.162
.233
.455
.614
H
"
N
II
.614
.614
H
.455
1.043
.455
.59
.57
.55
.61
process
1091 Mg/day
kg/hr
14.71
113.7
7.79
14.71-
20.3
"
"
•
"
24.4
20.3
H
14.71
35.5
14.71
19.57
18.80
18.10
20.03
kg/Mg
.324
2.502
.172
.324
.446
"
H
"
.538
.446
.324
.781
.324
.43
.42
.40
-
.44
other states
stack
in the
-
solids
or process.
straight
production
in each state
c - Weighted average based on percentage of prill production
in each state
d - Weighted average based on percentage of granule
production in each state
5-14
-------
TABLE 5-5. ALLOWABLE EMISSIONS BY PLANT SIZE (English Units)
A1 abama
Alaska
Arkansas
California
Georgia
Iowa
Kansas
Louisiana
Mississippi
Missouri
New York
Ohio
Oregon
Tennessee
Texas
Wyoming
Straight Average3
Weighted Average
Weighted Average
Prills Only
Weighted Average
Granules Only
200
Ib/hr
13.37
117.3
10.89
13.37
16.97
II
II
II
II
16.18
16.97
II
13.37
25.19
13.37
16.04
16.05
15.61
16.82
*This
TPO
400 TPO
Ib/ton
1.
14.
1.
1.
2.
II
fl
II
II
1.
2.
II
1.
3.
1.
1.
1.
1.
2.
state
604
Ib/hr
20.
071 157.
307
604
037
941
037
604
022
604
92
93
87
02
def i nes
13.
20.
27.
ii
d
11
»
25.
27.
II
20.
49.
20.
26.
25.
24.
26.
an
54
2
22
54
00
74
00
54
85
54
17
34
55
73
Ib/ton
1
9
1
1
1
1
1
2
1
1
1
1
1
emission
emissions for the entire
define
an emission
Therefore,
or weighted
a - Straight
b - Weighted
c - Weighted
d - Weighted
Arkansas
source
.233
.433
.793
.233
.520
II
11
11
II
.544
.620
II
.233
.991
.233
.57
.53
.47
.60
800 TPD
1200
Ib/hr Ib/ton Ib/hr
30
210
15
30
40
40
40
30
69
30
38
37
36
40
.34
.8 6.
.53 0.
.34
.89 1.
II (1
it ft
II 11
-------
towers producing agricultural grade prills. This is the average allowable
mass emission rate, based upon state regulations for a 363 Mg/day (400
ton/day) plant. In addition, it is assumed that the uncontrolled
emissions for a nonfluidized bed tower are 1.9 kg/Mg (3.8 Ib/ton) based
upon EPA testing.
5.2.3 ELOC for Fluidized Bed Prill Towers Producing Agricultural
Grade Prills
Uncontrolled emissions for fluidized bed towers are higher than
uncontrolled emissions from nonfluidized bed towers. EPA tests of a
fluidized bed tower show that uncontrolled emissions are 3.1 kg/Mg (6.2
Ib/ton) for a plant producing agricultural grade prills. Industry data
for controlled emissions from fluidized bed towers vary from 0.38 - 0.43
kg/Mg (0.76 - 0.86 Ib/ton). EPA test data show controlled emissions of
0.39 kg/Mg (0.79 Ib/ton) for a fluidized bed tower producing agricul-
tural grade urea prills. All three fluidized bed towers are currently
controlled to levels required by state regulations.
Based on this data, state regulations are being met by existing
facilities and an average state regulation was used to establish the
ELOC. For agricultural grade production, 0.6 kg/Mg (1.2 Ib/ton) represents
the allowable emission under an average state regulation for a typical
size of fluidized bed prill tower (737 Mg/day or 800 ton/day).
5.2.4 ELOC for Feed Grade Prill Towers
During the production of feed grade urea, nonfluidized and fluidized
bed towers operate with approximately the same air flow and have com-
parable uncontrolled emissions. The limited industry data reports that
uncontrolled emissions for nonfluidized bed prill towers producing feed
grade product range from 1.61 - 1.76 kg/Mg (3.22 - 3.51 Ib/ton). EPA
data for a feed grade fluidized bed prill tower show uncontrolled
emissions of 1.68 kg/Mg (3.36 Ib/ton). Based on these emissions any new
feed grade prill towers would have to control emissions to meet state
regulations. A 0.8 kg/Mg (1.6 Ib/ton) of product emission level was
chosen as the ELOC for prill towers producing feed grade based upon the
average state regulations for 363 Mg/day (400 ton/day) plants. This is
5-16
-------
the same level selected for nonfluidized bed prill towers producing
agricultural grade urea prills. The larger plant size used for estab-
lishing the fluidized bed, agricultural grade ELOC is not used since
plants producing feed grade tend to be smaller.
5.2.5 ELOC for Granulators
All 19 existing granulators are controlled, 18 with entrainment
scrubbers and one with a packed bed scrubber. A comparison of uncon-
trolled emissions and applicable state regulations indicates that
collection efficiencies of better than 99 percent are required. In
addition, since uncontrolled emissions are high, process economics
dictate control at the source.
An emission level of 0.115 kg/Mg (0.230 Ib/ton) of product was
chosen as the ELOC for granulators. This level represents the emissions
measured during EPA testing and is typical of existing industry practice.
5.2.6 ELOC for Rotary Drum Coolers
Solids cooling is required, in some cases, during the production of
agricultural grade prills in a nonfluidized bed prill tower. Rotary
drum coolers are used when sufficient cooling is not available in the
prill tower.
Very little data is available to quantify typical uncontrolled
emissions from coolers. One EPA test measured uncontrolled emissions of
3.9 kg/Mg (7.8 Ib/ton). Industry data indicates four coolers have
emission rates ranging from 0.01 to 0.1 kg/Mg (0.02 to 0.2 Ib/ton).
These levels are significantly below the allowable state regulations.
No EPA data is available for controlled cooler emissions which would
allow verification of the industry test data with an EPA approved
method. However calculations based upon EPA particle size data in
conjunction with manufacturers' control device performance specifications
confirm that the devices in use are capable of reducing emissions to the
levels reported by industry. Thus, an ELOC emission level of 0.1 kg/Mg
(0.2 Ib/ton) was selected. This level represents the highest controlled
emissions reported by industry.
5-17
-------
5.3 CONTROL OPTIONS
This section presents control devices recommended for application
to control participate emissions from urea solids producing and finishing
processes. The selection of control devices (hereafter referred to as
control options) to achieve various control levels is based on per-
formance data from EPA testing and vendor information. Table 5-6
presents a summary of control options for each source. Subsections
5.3.1, 5.3.2, and 5.3.3 presents control options for prilling, granu-
lation, and rotary drum cooling processes, respectively. Section 5.3.4
presents emission characteristics for each model plant.
5.3.1 Prill Towers
To control particulate emissions to the ELOC for prill towers, a
spray tower scrubber is recommended. This scrubber exhibits a removal
efficiency of from 56 to 82 percent depending on the type of tower. To
reduce emissions to a lower level, an entrainment scrubber is recommended
and designated as control option 1 for prill towers. The greatest
degree of control is achieved by a wetted fibrous filter with a removal
efficiency of 98 percent (control option 2 for prill towers).
5.3.2 Granulators
Particulate emissions from granulators are currently well controlled
to prevent excessive product loss. Since granulators are currently
achieving the ELOC with an entrainment scrubber, no other control options
are recommended.
5.3.3 Rotary Drum Coolers
To meet the ELOC determined for rotary drum coolers, a plate
impingement scrubber with a removal efficiency of 98 percent is recommended.
Control options attaining greater levels of control are not defined.
5.3.4 Emissions Characteristics
Tables 5-7 through 5-16 define emission characteristics for each
model plant. This data is presented in terms of emission sources and
control options, as discussed in the previous sections.
5-18
-------
TABLE 5-6. CONTROL EQUIPMENT PERFORMANCE PARAMETERS
in
10
Applicable Performance Parameters
Emission Model Control Removal Pressure Drop
Source Plants Option Control Device Efficiency kPa (in. W.G.
Prill 1-7 ELOC Spray Tower a a a
Tower
1-7 Option 1 Entrapment 85% 1.3 5.0
Scrubber
1-7 Option 2 Wetted Fibrous 98% 3.1 12.0
Fi 1 ter
Granulator 8-10 ELOC Entrapment 99.9% 4.1 16.0
Scrubber
Cooler 1-3 ELOC Plate Impingement 98% 1.3 5.0
(Tray Type)
Scrubber
Liquid/Gas Ratio -
) l/m3 (gal/1000fn
.40 3.0
.87 6.5
.27 2.0
.87 6.5
.40 3.0
aRemoval efficiency and pressure drop varies according to the specific Model Plant.
Efficiencies range from 56 to 82 percent.
ELOC- Existing level of control.
-------
TABLE 5-7. EMISSION CHARACTERISTICS FOR MODEL PLANT 1 CONTROL OPTIONS
01
Emission
Source
Prill
Tower
Cooler
Control
Level
ELOC
Option 1
Option 2
ELOC
Total Stack
Fl owrate
dsm /min
(dscfm)
2690
(95000)
2690
(95000)
2690
(95000)
214
(7570)
Exhaust
Temperature
K
(F)
294
(70)
294
(70)
294
(70)
305
(90)
Particulate
Concentration
g/m
(gr/dscf)
.0375
.0164
.0133
(.0058)
.0018
(.0078)
.0586
( .0256)
Moisture
Content
%
2.5
2.5
2.5
4.5
Emission
Factor
kg/Mg
(Ib/ton)
0.80
(1.60)
.285
( .570)
.038
( .076)
.10
(.20)
-------
TABLE 5-8. EMISSION CHARACTERISTICS FOR MODEL PLANT 2 CONTROL OPTIONS
en
IX)
Emission
Source
Prill
Tower
Cooler
Control
Level
ELOC
Option 1
Option 1
ELOC
Total Stack
Fl gwrate
dsm /min
(dscfm)
6850
(242,000)
6850
(242,000)
6850
(242,000)
858
(30280)
Exhaust
Temperature
K
(F)
294
(70)
294
(70)
294
(70)
305
(90)
Particulate
Concentration
g/nr
(gr/dscf)
0.0587
(0.0257)
.0210
( .0092)
.0028
( .0012)
.0586
( .0256)
Moisture
Content
%
2.5
2.5
2.5
4.5
Emission
Factor
kg/Mg
(Ib/ton)
0.80
1.60
.285
(.570)
.038
(.076)
.10
(.20)
-------
TABLE 5-9. EMISSION CHARACTERISTICS FOR MODEL PLANT 3 CONTROL OPTIONS
en
I
ro
ro
Emission
Source
Prill
Tower
Cooler
Control
Level
ELOC
Option 1
Option 2
ELOC
Total Stack
Fl owrate
dsm /min
(dscfm)
9360
(340,000)
9360
(340,000)
9360
(340,000)
1290
( 45,400)
Exhaust
Temperature
K
(F)
294
(70)
294
(70)
294
(70)
305
(90)
Particulate
Concentration
g/rn
(gr/dscf)
.0629
( .0275)
.0224
( .0098)
.0030
( .0013)
.0586
( .0256)
Moisture
Content
%
2.5
2.5
2.5
4.5
Emission
Factor
kg/Mg
(Ib/ton)
0.80
(1.60)
.285
( .570)
.038
( .076)
.10
( .20)
-------
TABLE 5-10. EMISSION CHARACTERISTICS FOR MODEL PLANT 4 CONTROL OPTIONS
en
ro
CO
Emission
Source
Prill
Tower
Control
Level
ELOC
Option 1
Option 2
Total Stack
Flowrate
dsnr/min
(dscfm)
2830
(100,000)
2830
(100,000)
2830
(100,000)
Exhaust
Temperature
K
(°F)
294
(70)
294
(70)
294
(70)
Particulate,
Concentration
g/m3
(gr/dscf)
.0268
(.0117)
.0207
(.00904)
.00277
(.00121)
Moi sture
Content
%
2.5
2.5
2.5
Emission
Factor
kg/Mg
(Ib/ton)
0.60
(1.20)
.465
(.930)
.0620
(.124)
-------
TABLE 5-11. EMISSION CHARACTERISTICS FOR MODEL PLANT 5 CONTROL OPTIONS
en
ro
Emission
Source
Prill
Tower
Control
Level
ELOC
Option 1
Option 2
Total Stack
Flowrate
dsm3/min
(dscfm)
8890
(314,000)
8890
(314,000)
8890
(314,000)
Exhaust
Temperature
K
(°F)
294
(70)
294
(70)
294
(70)
Particulate .
Concentration
g/m3
(gr/dscf)
.0340
(.0148)
.0263
(.0115)
.00353
(.00154)
Moi sture
Content
%
2.5
2.5
2.5
Emission
Factor
kg/Mg
(Ib/ton)
0.60
(1.20)
.465
(.930)
.0620
(.124)
-------
TABLE 5-12. EMISSION CHARACTERISTICS FOR MODEL PLANT 6 CONTROL OPTIONS
ro
en
Emi ssion
Source
Prill
Tower
Control
Level
ELOC
Option 1
Option 2
Total Stack
Flowrate
dsnr/mi n
(dscfm)
12,900
(457,000)
12,900
(457,000)
12,900
(457,000)
Exhaust
Temperature
K
(°F)
294
(70)
294
(70)
294
(70)
Particulate
Concentration
g/m^
(gr/dscf)
.0351
(.0153)
.0273
(.0119)
.00362
(.00158)
Moi sture
Content
%
2.5
2.5
2.5
Emission
Factor
kg/Mg
(Ib/ton)
0.60
(1.20)
.465
(.930)
.0620
(.124)
-------
TABLE 5-13. EMISSION CHARACTERISTICS FOR MODEL PLANT 7 CONTROL OPTIONS
ro
en
Emi ssion
Source
Prill
Tower
Control
Level
ELOC
Option 1
Option 2
Total Stack
Flowrate
dsnr/min
(dscfm)
1080
(38,000)
1080
(38,000)
1080
(38,000)
Exhaust
Temperature
K
(°F)
311
(100)
311
(100)
311
(100)
Particulate
Concentration
g/m3
(gr/dscf)
.113
(.0491)
.316
(.0138)
.00421
(.00184)
Moi sture
Content
%
5.0
5.0
5.0
Emi ssion
Factor
kg/Mg
(Ib/ton)
0.80
(1.60)
.270
(.540)
.0360
(.0720)
-------
TABLE 5-14. EMISSION CHARACTERISTICS FOR MODEL PLANT 8 CONTROL OPTIONS
Emi ssion
Source
Granulator
Control
Level
ELOC
Total Stack
Flowrate
dsnr/min
(dscfm)
1360
(48000)
Exhaust
Temperature
K
311
(100)
Parti cu late.
Concentration
g/m3
(gr/dscf)
.0213
(.00932)
Moi sture
Content
5.0
Emission
Factor
kg/Mg
(Ib/ton)
115
(.230)
en
ro
-------
TABLE 5-15. EMISSION CHARACTERISTICS FOR MODEL PLANT 9 CONTROL OPTIONS
Emission
Source
Granulator
Control
Level
ELOC
Total Stack
Flowrate
dsnr/min
(dscfm)
2720
(96,000)
Exhaust
Temperature
K
(°F)
311
(100)
Particulate
Concentration
g/m3
(gr/dscf)
.0213
(.00932)
Moisture
Content
%
5.0
Emi ssion
Factor
kg/Mg
(Ib/ton)
.115
(.230)
en
ro
00
-------
TABLE 5-16. EMISSION CHARACTERISTICS FOR MODEL PLANT 10 CONTROL OPTIONS
Emission
Source
Granulator
Control
Level
ELOC
Total Stack
Flowrate
dsnr/min
(dscfm)
4080
(144,000)
Exhaust
Temperature
K
(°F)
311
(100)
Parti cul ate ,
Concentration
g/m3
(gr/dscf)
.0213
(.00932)
Moisture
Content
%
5.0
Emi ssion
Factor
kg/Mg
(Ib/ton)
.115
(.230)
en
I
ro
-------
5.4 CONTROL ALTERNATIVES
5.4.1 Approach
Control alternatives for each model plant are summarized in Table
5-17. Each alternative is comprised of various control options (control
devices) applied to each emission source in each model plant. In selecting
the control options, three basic levels of emission control are considered
for each emission source.
1. ELOC - Controlling emissions to the ELOC as defined in Section
5.2. This level of control would typically be required under
existing state regulations.
2. Controlling emissions to achieve the greatest degree of
reduction.
3. Controlling emissions to an intermediate level. This is
between the ELOC and the greatest degree of emission reduction.
Selection of the intermediate and greatest levels of control is made on
the basis of performance data in Chapter 4. For sources other than
prill towers, the selection of control levels is limited to existing
levels of control. Control alternatives will be referred to in subsequent
chapters to facilitate economic and environmental impact comparisons.
5-30
-------
TABLE 5-17. CONTROL ALTERNATIVES
en
oo
Model
Plant
No.
1-3
4-6
7
8-10
Legend:
Plant
Configuration
Nonfluidized bed, Agricultural
grade production
Fluidized bed, Agricultural
grade production
Nonfluidized bed, Feed
grade production
Granulator
0 - ELOC
Emission
Sources
Prill Tower
Cooler
Prill Tower
Prill Tower
Granulator
1
0
0
0
0
0
Control
Alternatives
2 3
0 0
+ ++
+ ++
+ - Option 1
++ - Option 2
-------
5.3 REFERENCES
1. Shreve, R.N. and J.A. Brink. Chemical Process Industries, Fourth
Edition. New York, McGraw-Hill Book Company, 1977. pp. 284-287.
2. Kirk-Othmer (ed.). Encyclopedia of Chemical Technology, Volume 21.
John Wiley & Sons, Inc., 1970. pp. 37-56.
3. Chemical Engineering (ed.). Sources and Production Economics of
Chemical Products, Second Edition. New York, McGraw-Hill Publishing
Company, 1979. pp. 277-279.
4. Trip report. Bornstein, M.I., GCA Corporation, to Noble, E.A.,
EPA:ISB. August 2, 1978. p. 2. Report of visit to C & I Gridler
Incorporated in Louisville, Kentucky.
5. Memo from Stelling, J., Radian Corporation, to file. July 6, 1980.
Compilation of state regulations on particulate emissions from urea
plants.
5-32
-------
6.0 ENVIRONMENTAL IMPACTS
The purpose of this chapter is to present the environmental impacts
of the control alternatives for participate emissions from emission
sources in the urea industry. The emission sources to be considered are
prill towers, rotary drum coolers, and rotary drum granulators. The air
quality, water pollution, solid waste, and energy impacts associated
with the application of the control alternatives to the model plants are
identified and discussed in Sections 6.1 to 6.4, respectively. Additional
impacts are described in Section 6.5.
6.1 AIR POLLUTION IMPACT
The impact of each control alternative on air quality is evaluated
in this section. Two impacts are considered: primary impacts, or the
reduction of particulates due to the control equipment used, and secondary
impacts; the pollutants generated as a result of applying the control
equipment.
6.1.1 Primary Air Quality Impacts
The primary impact on air quality resulting from implementation of
control alternatives is the reduction of particulate emissions into the
atmosphere. Table 6-1 presents plant-wide (prill towers, granulators,
coolers) emission and removal factors for the control alternatives and
model plants presented in Chapter 5. Table 6-1 also presents the
additional emissions reduction relative to the existing level of control
(ELOC) for prill towers. The control alternatives for prill towers
increase in their stringency from Alternative 1 (ELOC) to Alternative 3
(greatest degree of control). Using the emission reduction factors in
Table 6-1, Table 6-2 presents the total annual emissions reduction for
Control Alternatives 2 and 3 over the ELOC.
6-1
-------
TABLE 6-1. EMISSION AND REMOVAL FACTORS FOR CONTROL ALTERNATIVES
Model Plant
Number
1-3
4-6
7
8-10
Emission factors kg/Hg (Ib/ton)
Control Alternative
Plant Configuration
Nonfluldlzed bed
Prill tower, cooler,
Agricultural grade
Fluldized bed
Prill tower,
Agricultural grade
Prill Tower,
Feed grade
Granulator,
1
0.900
(1.800)
0.600
(1.200)
0.800
(1.600)
0.115
(0.230)
2
0.385
(0.770)
0.470
(0.930)
0.270
(0.540)
3
0.138
(0.276)
0.062
(0.124)
0.036
(0.072)
Absolute Reduction Over ELOC kg/Hg (Ib/ton)
Control Alternative
1
0
(0)
0%
0
(0)
0%
0
(0)
0%
2
0.515
(1.030)
54%
0.135
(0.270)
23%
0.530
(1.060)
66%
3
0.762
(1.524)
84%
0.538
(1.076)
90%
0.764
(1.528)
96%
en
i
-------
TABLE 6-2. TOTAL ANNUAL REDUCTION OVER THE ELOC OF PARTICULATE
EMISSIONS FOR CONTROL ALTERNATIVES,3 Mg/year (Tons/year)
CO
Model
Plant
Number
1
2
3
4
5
6
7
8
9
10
Control Alternatives
Plant Configuration
Nonfluidized bed tower,
Agricultural grade
Nonfluidized bed tower,
Agricultural grade
Nonfluidized bed tower,
Agricultural grade
Fluidized bed tower,
Agricultural grade
Fluidized bed tower,
Agricultural grade
Fluidized bed tower,
Agricultural grade
Feed Grade Tower
Granulator,
Agricultural grade
Granulator,
Agricultural grade
Granulator,
Agricultural grade
Plant Capacity
Mg/day (Tons/day)
182
(200)
726
(800)
1090
(1200)
182
(200)
726
(800)
1090
(1200)
182
(200)
363
(400)
726
(800)
1040
(1200)
1
0
(0)
0
(0)
0
(0)
0
(0)
0
(0)
0
(0)
0
(0)
0
(0)
0
(0)
0
(0)
2
28.2
(31.0)
112.7
(124.0)
169.1
(186.0)
7.4
(8.1)
29.6
(32.5)
44.3
(48.8)
29.0
(31.9)
3
41.6
(45.8)
166.4
(183.0)
249.6
(274.5)
29.6
(32.5)
118.2
(130.0)
177.3
(195.0)
41.9
(46.1)
*Based on an operating schedule of 301 days/year.
-------
6.1.2 Secondary Air Quality Impacts
Secondary air pollutants are pollutants generated as a result of
applying control equipment. There are no air pollutants generated
directly by the control equipment required for each control level.
However, the increased need for steam and electrical power to support
the emission control systems will cause an increase in utility power
plant emissions. Table 6-3 presents the emission reductions and corresponding
increased power plant emissions for model urea plants and associated
control alternatives. Also presented (as a percentage) is the increased
power plant emission compared to the corresponding amount of urea plant-
wide emission reduction. Increased power plant emissions range from 1
to 3 percent of the amount of plant-wide emission reductions.
6.1.3 Summary of Air Quality Impacts
The primary air pollutant emissions from affected facilities in the
urea industry are particulates. The major benefit of implementing control
alternatives is the reduction of these particulate emissions. A range
of particulate reductions is possible, depending upon the control alternative
chosen. Alternative 3 has the greatest particulate reduction for prilling
operations. For Model Plant 3 (1090 Mg/day nonfluidized bed prill
tower), the primary air quality impact would be an annual reduction of
249.6 Mg/year (274.5 ton/year) of particulate, with a corresponding
secondary air quality impact due to increased power plant emissions of
5.0 Mg/year (5.5 ton/year) (2 percent of the plant-wide reduction).
Hence, the net reduction in particulates from Model Plant 3 would be
244.5 Mg/year (269.0 ton/year), or 98 percent of the plant-wide reduction.
Similarly, the impact of secondary pollutants would be small for the
other model plants and their respective control alternatives relative to
plant-wide particulate emission reductions.
6.2 WATER POLLUTION IMPACT
There would be no adverse water pollution impact due to the control
alternatives, since the liquor used in the wet scrubbers controlling
particulate emissions is typically recycled to the solution concentration
6-4
-------
TABLE 6-3. SECONDARY AIR POLLUTION IMPACTS ASSOCIATED WITH THE
APPLICATION OF CONTROL ALTERNATIVES TO TYPICAL UREA PLANTS
en
Plant
Type
Hon Fluidized Bed Prill Tower,
Agricultural grade
Fluidized Bed Prill Tower,
Agricultural Grade
Prill Tower
Feed Grade
Emission Reduction over ELOC kq/Mq Ob/ton)
Control Alternative
1 2 3
0.515 0.762
(1.030) (1.524)
0.135 0.538
(0.270) (1.076)
0. 530 0. 764
(1.060) (1.528)
Power Plant Emission kq/Mq (Ib/ton)
1 2 3
-a 0.0042b 0.0121b
(0.0083) (0.0243)
-a 0.0044b 0.0140b
(0.0089) (0.0279)
-a 0.0028 0.0076
(0.0056) (0.0151)
Impact Percent0
Control Alternative
1 2 3
1 2
3 3
1 1
(a) There are no additional energy requirements attributable to control devices corresponding to the ELOC.
(b) These emissions are averages for the various plant capacities.
(c) Impact percent = f Power Plant Emission \
^Emission Reduction Over ELOCj '
-------
concentration process or used for fertilizer solutions. The amount of
excess water discharged, already present in urea plants since it is
produced as a byproduct of the carbamate decomposition reaction, will be
reduced because of the large amount of water entrained in the exhaust of
a wet scrubber.
6.3 SOLID WASTE IMPACT
There would be no solid waste impact due to implementation of the
control alternatives. Liquor from scrubbers is recycled to the solution
concentration process or sold as fertilizer solution.
6.4 ENERGY IMPACT
Emission control equipment for the urea industry uses electricity
and, indirectly, steam. The primary electrical demand is from the
control equipment fans used in conjunction with normal operating equipment
to generate sufficient airflow rates and pressure drops across the
control equipment. Pumps which circulate the scrubber liquor also
require electrical energy. Steam is used to concentrate the scrubber
liquor to a level where it can either be recycled to the solution
concentration process or sold as fertilizer solution.
Table 6-4 presents the total annual energy requirements of the
control alternatives, assuming maximum steam requirements. The relative
amounts of each type of energy (steam or electricity) vary by model
plant. For prilling plants, 20-50 percent of the control equipment
energy demand is represented by steam (assuming a scrubber liquor urea
concentration of 20 percent by weight). Similarly, steam requirements
can comprise more than 95 percent of the control equipment energy required
for granulation plants. This high percentage is due primarily to the
high uncontrolled emission rates from granulators which necessitate a
greater scrubber liquor recycle rate.
Also presented in Table 6-4 are the incremental energy requirements
over the ELOC. The greatest increase in energy consumption occurs for
Control Alternative 3, Model Plant 6, a 1091 Mg/day (1200 ton/day)
fluidized bed prill tower producing agricultural grade prills. The
6-6
-------
TABLE 6-4. ANNUAL ENERGY REQUIREMENTS FOR UBEA
MODEL PLANT CONTROL ALTERNATIVES1
Model Control q
Plant Alternative 10yBtu
1
2
3
4
5
6
7
8
9
10
Nonfluidized Bed
Prill Tower,
Agricultural Grade,
182 Mg/day (200 TPD)
Nonfluidized Bed
Prill Tower,
Agricultural Grade
728 Mg/day (800 TPD)
Nonfluidized Bed
Prill Tower,
Agricultural Grade,
1091 Mg/day (1200 TPD)
Fluidized Bed Prill
Tower, Agricultural
Grade, 182 Mg/day
(200 TPD)
Fluidized Bed Prill
Tower, Agricultural
Grade, 728 Mg/day,
(800 TPD)
Fluidized Bed Prill
Tower, Agricultural Grade
1091 Mg/day (1200 TPD)
Prill Tower, Feed Grade
182 Mg/day (200 TPD)
Granulator 362 Mg/day (400 TPD)
Granulator 728 Mg/day (800 TPD)
Granulator 1091 Mg/day (1200
TPD)
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
1
1
10.4
15.0
24.3
33.8
46.3
70.2
49.5
67.2
100.8
7.8
12.3
22.0
26.5
40.6
71.5
39.0
59.5
104.5
3.3
5.6
9.8
275.9
551.8
828.8
Increase over Alternative 1
TJ
11.0
15.9
25.6
35.7
48.9
74.0
52.2
70.9
106.3
8.3
12.9
23.2
28.0
42.8
75.4
41.1
62.8
110.2
3.5
5.9
10.4
291.0
582.0
873.3
10 Btu
4.6
4.6
12.5
36.4
17.7
49.3
4.5
14.2
14.1
45.0
20.6
65.5
2.3
6.5
TJ
4 9
~ • -/
4.9
13.2
38.3
18.7
51.4
4.6
14.9
14.8
47.4
21.7
69.1
2.4
6.9
6-7
-------
control equipment energy requirement increase over ELOC for this case is
Q
69.1 TJ/year (65.5 x 10 Btu/year), or 63 percent. The total annual
energy requirement of the control equipment for this plant is 110.2 TO
Q
(104.5 x 10 Btu). The control equipment energy requirements of Model
Plant 6 with Control Alternative 3 represent less than 7 percent of the
total plant energy demand.
6.5 OTHER IMPACTS
There would be no significant noise impact due to implementation of
any of the control alternatives in the urea industry. The increase in
noise from properly designed control equipment would be insignificant
compared to the noise associated with production process equipment.
6-8
-------
6.6 REFERENCES
1. Memo from Stalling, J., Radian Corporation, to file. June 30, 1980.
22 p. Increased power plant emissions.
2. Memo from Stelling, J., Radian Corporation, to file. June 30, 1980.
5 p. Net consumption of water - test results and model plants.
6-9
-------
7.0 COST ANALYSIS
A cost analysis of the control alternatives described in Chapter 5
is presented in this chapter. This chapter is divided into two major
sections. Section 7.1 presents the costs associated with the various
control alternatives, including an analysis of capital and annualized
costs. Both new facilities and existing facilities are considered.
Other costs that may result from the application of control equipment
are considered in Section 7.2, including costs imposed by water pollution
control regulations and solid waste disposal requirements.
7.1 COST ANALYSIS OF CONTROL ALTERNATIVES
7.1.1 Introduction
The costs of implementing control alternatives in the urea industry
are presented in this section. The cost analysis is based upon the
model urea plants and the control alternatives presented in Table 7-1
and discussed in Chapter 5. Three sources were considered in the model
plant matrix. These were prill towers, rotary drum coolers, and granulators,
Control options are identified for each source and were used as the
basis for the formulation of the control alternatives.
The cost of purchasing, installing, and operating the various
control devices are presented in the following sections. The purchased
costs for the control equipment were obtained from vendor quotes.
Cost estimating manuals and published reports were used to determine
costs for auxiliary equipment, (fans, pumps, motors, starters, downcomers,
and stacks). Equipment costs were scaled up to first quarter 1980
dollars (abbreviated 1Q80) using either the Marshall and Swift Equipment
Cost Indices or Chemical Engineering Plant Cost Indicies. '
Total capital cost for installation of the various control devices
was determined by applying component factors to the basic equipment
7-1
-------
TABLE 7-1. SUMMARY OF UREA MODEL PLANTS AND CONTROL ALTERNATIVES
I
ro
Model Plant
No.
1
2
3
4
5
6
Size
Mg/D
(tons/D)
181(200)
726(800)
1090(1200)
181(200)
726(800)
1090(1200)
Emission
Configuration Sources
Nonfluidized prill tower plant Prill Tower
producing agricultural grade
prills. Supplementary Cooler
cooling required.
Fluidized bed prill tower
plant producing Prill Tower
agricultural grade prills.
No supplementary cooling
required.
Control
Alternatives
1 2 3
0 + ++
000
0 + ++
181(200)
Prill Tower Plant
producing feed grade prills.
Prill Tower
8
9
10
363(400)
726(800)
1091(1200)
Granulation Plant
Granulator
Legend: 0 - ELOC
+ - Option 1
++ - Option 2
-------
costs. These component factors take into account direct costs (piping,
electrical, instrumentation, structural costs, construction labor,
etc.), indirect costs (engineering, contractor's fee, taxes, etc.), and
contingencies. The capital component factors were obtained from a
C 10
survey of industry and a cost estimating manual. '
The annual cost of operating and maintaining the control devices
includes direct operating expenses (utilities, labor, maintenance) and
capital charges. Capital charges include insurance, administrative
overhead, taxes, and capital recovery (the annual cost for the payoff of
the control devices). '' Any credits or gains obtained from application
of the control equipment is subtracted from the annual operating costs
in order to obtain the net annual cost of the control alternatives.
Credits are obtained from recovering urea captured by the control
equipment.
Net annual costs are divided by the quantity of pollutant removed
by the control equipment to determine the cost effectiveness of the
control alternatives. Cost effectiveness is used as a means of comparing
the various alternatives.
The costs associated with controlling emissions from new facilities
are discussed in Section 7.1.2. Cost considerations for existing
facilities are discussed in Section 7.1.3.
7.1.2 New Facilities
The capital and annualized costs of applying control alternatives
to new urea solids production, finishing, and handling facilities are
presented in this section. Costs associated with the control alter-
natives are presented in six subsections. Section 7.1.2.1 discusses
important considerations used in the determination of control equipment
costs. Section 7.1.2.2 presents the capital costs of the control alternatives,
and Section 7.1.2.3 presents the annual cost of the control alternatives.
The effect of the control alternatives on the cost of urea product is
presented in Section 7.1.2.4. Section 7.1.2.5 compares the annual
costs and cost effectiveness of the control options to Alternative 1
[existing level of control (ELOC)]. The base cost of a urea plant is
discussed in Section 7.1.2.6.
7-3
-------
7.1.2.1 Basis for Equipment Costs. This section presents important
considerations in determining the costs of the control equipment. All
the equipment, except for motors and starters, is made of stainless
steel because of the corrosiveness of urea. Table 7-2 presents control
equipment operating parameters which were obtained from vendors and are
typical of industrial operation. The control devices and auxiliary
equipment were sized to handle the airflows and emissions specified for
the model plants in Tables 5-7 through 5-16. An example of the major
equipment needed to control emissions from the sources in the model
plants are presented in Tables 7-3a through 7-3c. For each emission
source considered, the equipment for one plant size is presented as an
example.
Due to differences in plant design, scrubbers selected for prill
towers are of various sizes while only one scrubber size was selected
for each granulator processing train. For prilling operations, the
prill tower and finishing equipment are constructed and sized to handle
whatever capacity was chosen for design production. Likewise, the
scrubbers and auxiliary equipment used to control emissions from these
facilities were sized to handle the entire airflow from the facility.
The airflow through the solids production equipment varies with plant
size, therefore, all of the control equipment had to be resized for each
plant size. Granulation plants, on the other hand, employ processing
trains of specific sizes, as discussed in Chapter 5. The model granulation
plants chosen were 363 Mg/day (400 TPD), 726 Mg/day (800 TPD), and 1089
Mg/day (1200 TPD). A 363 Mg/day (400 TPD) granulator was used as a
base, representing a single processing train. Control equipment was
sized to handle the emissions from a single 363 Mg/day (400 TPD) plant.
For 726 Mg/day (800 TPD) and 1089 Mg/day (1200 TPD) plants additional
granulator processing trains were added, and the total equipment cost
for controlling emissions was obtained by doubling or tripling the cost
of controlling a single processing train.
7-4
-------
TABLE 7-2. SPECIFICATIONS FOR PARTICIPATE CONTROL SYSTEMS
I. Spray Tower (For prill towers)
A. Pressure Drop: .77 kPa (3 in.Jd.G.)9
B. Liquid to Gas Ratio: 0.40 Vm (3.0 gal/1000 acf)
C. Construction Material: 304 SS
D. Fan Location: At scrubber inlet
E. Scrubber Location: On top of prill tower
II. Entrainment Scrubber (For prill towers)
A. Pressure Drop: 1.3 kPa (5 in.,W.G.)
B. Liquid to Gas Ratio: 0.87 £/nr (6.5 gal/1000 acf)a
C. Construction Material: 304 SS
D. Fan Location: At Scrubber inlet
E. Scrubber Location: At grade level
III. Wetted Fibrous Filter (For prill towers)
A. Pressure Drop: 3.1 kPa (12 in-W.G.) ,
B. Liquid to Gas Ratio: 0.27 £/nT (2 gal/1000 acf)a>D
C. Construction Material: 304 SS
D. Fan Location: At scrubber outlet
E. Scrubber Location: At grade level
IV. Plate Impingement (Tray type) Scrubber (For coolers)
A. Pressure Drop: 1.3 kPa (5 in.-W.G.)
B. Liquid to Gas Ratio: 0.40 2,/mj: (3 gal/1000 acf)a'C)
C. Construction Material: 304 SSD
D. Fan Location: At scrubber inlet
V. Entrainment Scrubber (For granulators)
A. Pressure Drop: 4.1 kPa (16 in. W.G.)
B. Liquid to Gas Ratio: 0.87 a/m (6.5 gal/1000 acf)a
C. Construction Material: 304 SS
D. Fan Location: At scrubber inlet
a. Reference 12
b. Reference 5
c. Reference 2
d. Reference 3
7-5
-------
TABLE 7-3a. EXAMPLE OF MAJOR EQUIPMENT REQUIREMENTS
FOR CONTROL OF PRILL TOWERS
(726 Mg/day (800 TPD), Fluidized bed/Agricultural grade configuration)
Control Device
Ducting
Fan (each)
Recirculation pump
Existing Level of Control
Spray tower 304 SS,
L/G = 3.0 gal/1000 ACF.
3"WG
304 SS ductwork (4.0 feet diameter)
60740 ACFM @ 111°F. 275 rpm. 50 hp.
1800 gpm, 30 ft TDH. 125 hp.
Control Device
Ducting
Fan (each)
Stack
Recirculation pump
Control Option 1
Entrainment scrubber, 304 SS construction,
L/G = 6.5 gal/1000 ACF. AP = 5"WG
304 SS ductwork (7.0 feet diameter), including
ducting from top of prill tower to grade level.
60740 ACFM @ 111 °F. 600 rpm, 125 hp.
7.0 feet diameter. 85 ft high. CS
2400 qpm. 100 ft TDH, 150 hp.
Control Device
Ducting
Fan
Stack
Recirculation pump
Control Option 2
Wetted Fibrous Filter, 304 SS construction,
L/G = 2 gal/1000 ACF. Ap = 12"WG
304 SS ductwork (10.5 feet diameter), including
ducting from top of prill tower to grade level.
364,400 ACFM @ 111 °F, 1400 hp.
10.5 feet diameter. 120 ft high. CS
730 qpm, 100 ft TDH, 50 hp.
Preconditioning system
Recirculation pump 550 gpm, 220 ft TDH, 75 hp.
Piping CS and SS, as required
7-6
-------
TABLE 7-3b. EXAMPLE OF MAJOR EQUIPMENT REQUIREMENT FOR
CONTROL OF COOLERS
726 Mg/day (300 TPD)
Control Device
Ducti ng
Fan
Stack
Recirculation pump
Existing Level of Control
Plate Impingement (Tray Type)
Scrubber, 304 SS construction,
L/G = 3.0 gal/1000 ACF, AP = 5" WG
304 SS ductwork (3.Q feet diameter)
33800 ACFM @ 90°F, 1600 rpm, 200 hp
3.0 feet diameter. 40 ft high, CS
220 qpm, 100 ft TDH. 15 hp
7-7
-------
TABLE 7-3c. EXAMPLE OF MAJOR EQUIPMENT REQUIREMENTS FOR
CONTROL OF GRANULATORS
363 Mg/day (400 TPD)
Control device
Ducting
Fan
Stack
Recirculation pump
Existing Level of Control
Entrainment scrubber, 304 SS construction,
L/G =6.5 gal/1000 ACF. Ap - 16" WG
304 SS ductwork. 5.0 feet diameter
64000 ACFM @ 190°F, 1250 rpm. 250 hp
5.0 feet diameter, 85 ft high. CS
400 gpm. 100 ft TDH. 15 hp
7-8
-------
The cost of purchasing the control equipment is shown in Table 7-4.
This table presents the cost of the control device and the cost for all
the major equipment items associated with the control options. Table 7-5
presents an example cost breakdown of the major equipment items needed
to control Model Plant 1 to the ELOC (Control Alternative 1). The same
procedure shown in this example was used to derive the purchased equipment
cost of the control alternatives for all model plants.
7.1.2.2 Capital Costs. Capital costs represent the total investment
required for purchase and installation of the basic control equipment
and associated auxiliaries. Capital cost estimates for each control
fi IP
system were developed with cost component factors. ' These factors
were applied to the control option costs presented in Table 7-6 to give
installed capital costs. The capital costs for the control options were
then combined to give the control alternative cost presented in Table 7-7.
Costs for research and development and costs for possible production
losses during equipment installation and start-up were not included.
The costs are presented in first quarter 1980 dollars.
In computing the total installed cost of the wetted fibrous filter
for Control Option 2 on prill towers, actual installation costs provided
by the vendor were substituted for generalized installation costs in the
component factor. Therefore, the installation cost element of the
component factor was deleted during these calculations.
7.1.2.3 Annualized Costs. Annualized costs represent the yearly
cost of operating and maintaining the pollution control system. The
basis of the annualized cost estimates are presented in Table 7-8. All
annualized costs were based on 7224 hr/yr of operation.
Electricity costs were based on the power required to run the
electric motors used to operate fans and pumps. Brake horsepower for
the motors was determined by using power curves from cost estimating
manuals. The annual cost of electricity was based upon an electricity
cost of $.04/kwh.
Annual labor cost for operation of the control equipment is the
product of the total labor rate ($17.45/hr), operating hours per
7-9
-------
TABLE 7-4. PURCHASED EQUIPMENT COSTS ASSOCIATED WITH CONTROL OPTIONS (1Q80)
-J
H-1
O
Model
Plant
1
2
3
4
5
6
7
8
9
10
Control
Option
ELOCa
1
2
ELOC
1
2
ELOC
1
2
ELOC
1
2
ELOC
1
2
ELOC
1
2
ELOC
1
2
ELOC
ELOC
ELOC
Control Device Cost, 1000$
Prill Tower Cooler Granulator
203.4 11.6
135.8
468
449.8 37.6
372.3
815
532.0 47.0
467.7
1110
206.5
140.0
478
506.6
433.5
1025
749.5
620.5
1350
159.5
62.2
325
69.4
138.8
208.2
Total Control
Prill Tower
334.0
362.2
622.2
762.8
864.3
1140.0
976.1
1185.4
1507.6
340.0
368.1
632.2
903.6
1092.1
1385.1
1334.0
1661.8
1995.9
229.0
182.0
436.7
-
-
-
Equipment Cost, 1000$
Cooler Granulator
33.2
- -
•— —
82.7
— —
"" ""
121.1
-
» —
-
- -
— —
-
-
— —
-
- -
•• *~
-
— —
•~ ~
180.5
361.0
541.5
a ELOC = Existing level of control
-------
TABLE 7-5. EXAMPLE OF PURCHASED EQUIPMENT COST BREAKDOWN OF MAJOR
EQUIPMENT FOR ALTERNATIVE 1 ON A 181 Mg/day (200 TPD)
NONFLUIDIZED BED PRILL TOWER, AGRICULTURAL GRADE
(MODEL PLANT 1), $1000 (1Q80).
Item Cooler Prill Tower Total
Control Device 11.6 203.4 215 0
Fans, Motors, Starters 6.3 73.4 79*7
Pumps, Motors, Starters 7.5 19 7 27*2
Ducting 2.9 30.*5 33^4
^ack 1.4 7.0 84
Tank 3.5 3>5
33.2 334.0 367.2
7-11
-------
TABLE 7-6.
COMPONENT CAPITAL COST FACTORS 6'12
FOR A WET SCRUBBER AS A FUNCTION OF
EQUIPMENT COST, Q
Component
Major Equipment
Ductwork
Instrumentation
Electrical
Foundations
Structural
Sitework
Painting
Piping
Total direct costs
Direct
Material
1.00 Q
0.11 Q
0.08 Q
0.06 Q
0.03 Q
0.06 Q
0.02 Q
0.005 Q
0.09 Q
1.40 Q
costs
Labor
0.09 Q
0.09 Q
0.07 Q
0.12 Q
0.05 Q
0.03 Q
0.02 Q
0.02 Q
0.08 Q
0.50 Q
1.90 Q
Component
Engineering
Contractor's fee
Shakedown
Spares
Freight
Taxes
Indi rect costs
Measure of costs
10 percent material and
15 percent material and
5 percent material ano
1 percent material
3 percent material
3 percent material
Total indirect costs
Contingencies - 20 percent of direct and indirect costs
Total capital costs
Factor
labor 0.19 Q
labor 0.29 Q
labor . 0.10 Q
0.01 Q
0.04 Q
0.04 Q
0.67 Q
0.51 Q
3.08 Q
7-12
-------
TABLE 7-7. CAPITAL COSTS OF CONTROL ALTERNATIVES
FOR MODEL PLANTS, $1000 (1Q80)
Case3
1-1
1-2
1-3
2-1
2-2
2-3
3-1
3-2
3-3
4-1
4-2
4-3
5-1
5-2
5-3
6-1
6-2
6-3
7-1
7-2
7-3
8-1
9-1
10-1
Model Control
Plant Alternative
1 1
2
3
2 1
2
3
3 1
2
3
4 1
2
3
5 1
2
3
6 1
2
3
7 1
2
3
8 1
9 1
10 1
Total Control
Equipment
Cost
367
395
655
845
947
1222
1097
1306
1628
340
368
632
903
1092
1385
1334
1661
1955
229
182
436
180
361
541
Total
Installed
Cost
1131
1218
1695
2604
2916
3173
3379
4024
4232
1047
1133
1618
2783
3363
3545
4108
5112
5007
705
562
1118
555
1112
1668
Difference in
Total Installed Cost
(Alternative - Existing Level)
87
564
312
569
644
853
86
571
580
762'
1003
898
(142 )
412
-
-
-
aFirst number is model plant number; second number is control alternative number.
Note: Values in parentheses represent net credits or gains.
7-13
-------
TABLE 7-8. BASES FOR SCRUBBER ANNUALIZED COST ESTIMATES (1980)
Direct operating costs
Utilities
Water
Electricity
Operating labor
Direct wage rate
Fringe benefits
Supervision •
Total
Operating hours
Process equipment
Scrubbers
Maintenance
Capital charges
Capital recovery factor
Taxes and insurance
Administrative overhead
Recovery credit
Condensate from solution formation
processes assumed available free of
charge
$.04/kWh
$7.66/hour
25 percent of direct rate
15 percent of direct rate
$10.72/hr
7,224 hours/year
7,224 hours/year
Each unit requires one
eighth of an operator *.5
5.5 percent of capital investment
0.1669b
5.0 percent of capital investment
2.5 percent of capital investment
c
$50 in solution
aThis condensate would contribute to a plant's water pollution loading, if
not used by scrubbers and mist eliminators. Since costs of treatment and
disposal are avoided, the assumption that it is available free of charge
is conservative.
blnclu(ies wages plus 40 percent for labor-related administrative and overhead
costs. Cost (4077) updated using Hourly Wage Index:
260.4: 212.8.
cBased on a 15-year equipment life and a 10.0 percent interest rate.
• Recovery credit is taken as cost of urea (f.o.b. plant, $120/ton), less
the steam cost of removing the scrubber water (12 MMBTU/ton at $5.29/M
Ibs steam, $70/ton urea).'6
Reference 13.
fReference 15.
^Reference 6. •
7-14
-------
year of the control process (7224 hr/yr), and number of operators required
to run to control equipment (1/8 operator/unit). The annual labor cost
to operate a single control device is estimated to be $15,760/yr.
A conservative net credit of $55 per Mg ($50/ton) of urea was
calculated for urea recovered in wet scrubbers. This recovery credit
included the cost of removing all water from a 20 percent by weight urea
solution in a single stage evaporator. The total credit allowed for
each control option was dependent upon the uncontrolled emissions,
control device efficiency, and the assumed hours of operation.
An example of an annual ized cost breakdown for Control Alternative
2 on Model Plant 2 is given in Table 7-9. The procedure shown in this
example was used to determine the net annual ized costs presented in
Table 7-10 for the control options considered in this study. These
costs were combined to give the net annual ized costs of the control
alternatives, which are presented in Table 7-11.
7.1.2.4 Effect of Control Alternatives on Product Cost. The
impact of applying control alternatives on the price of the product was
also determined and is presented in Table 7-11. This cost impact
indicates the additional or credit cost per unit of urea produced. It
was calculated by dividing net annual cost of the control alternative by
annual model plant production.
7.1.2.5 Cost Effectiveness. Cost effectiveness is used as a means
of comparing control alternatives, and is defined as the total annual ized
cost of the pollution control system divided by the quantity of pollutant
removed by the system. The cost effectiveness of the control alternatives
can be compared directly to the ELOC by using the following equation.
r c
Cost Effectiveness =
- PE
C = Net annual ized cost to remove a quantity of pollutant (P ) by
A X
alternative x.
G£ = Net annual ized cost to remove a quantity of pollutant (Pr) to
meet a specified ELOC.
7-15
-------
TABLE 7-9. COMPONENT ANNUALIZED COSTS FOR ALTERNATIVE 2
MODEL PLANT 4.
Prill Tower, Control Option 2
Component
Cost, $1000 per year (1980)
Direct Costs
Operating labor and supervision
Maintenance labor and materials
Utilities
Electricity
Total Direct Costs
15.8
62.4
58.0
136.2
Administrative overhead
Capital recovery charges
Taxes and insurance
Total Capital Charges and Overhead
28.3
149.1
^56.7
234.1
Total Annual ized Costs
(without product recovery)
370.3
Credit for particulate recovery
Entrainment Scrubber
7.9
Total Credit
Net Annual ized Costs
362
7-16
-------
TABLE 7-10. NET ANNUALIZED COSTS FOR CONTROL OPTIONS, 1000$ (1Q80)
Model
Plant
1
2
3
4
5
6
7
8
9
10
Control
Option
ELOC
1
2
ELOC
1
2
ELOC
1
2
ELOC
1
2
ELOC
1
2
ELOC
1
2
ELOC
1
2
ELOC
ELOC
ELOC
Prill Tower Cooler Granulator
312 34
358
529
697 51 .
834
1028
894 66
1141
1375
314
362
537
815
1045
1255
1194
1571
1780
211
183
345
(649)
(1314)
(1979)
Note: Values in parentheses represent net credits or gains.
7-17
-------
TABLE 7-11. NET ANNUALIZED COST AND COST EFFECTIVENESS OF CONTROL ALTERNATIVES
FOR MODEL UREA FACILITIES (1Q80) (METRIC UNITS)
cx>
Case
1-1
1-2
1-3
2-1
2-2
2-3
3-1
3-2
3-3
4-1
4-2
4-3
5-1
5-2
5-3
6-1
6-2
6-3
7-1
7-2
7-3
8-1
9-1
10-1
Model Control
Plant Alternative
1 1
2
3
2 1
2
3
3 1
2
3
4 1
2
3
5 1
2
3
6 1
2
3
7 1
2
3
8 1
9 1
10 1
Net Annual
Cost 1000$
347.6
393.2
564.5
748.1
886.0
1079.1
961.0
1207.8
1441.6
362.4
362.6
543.0
815.9
1046.8
1262.1
1194.1
1573.3
1788.0
211.1
184.0
352.0
(649.1)
(1314)
(1979)
Cost Effectiveness
per unit urea recovered
$/Hg
1299
1355
1859
699
763
889
599
693
792
2654
2520
3273
1494
1819
1902
1457
1822
1796
3866
2202
3654
(57.9)
(57.9)
(57.9)
Cost Effectiveness
Relative to ELOC*
$/Mg
2027
6023
1514
2296
1810
2226
28
6144
78RO
3795
8619
3370
(937)
3376
-
-
-
Effect on cost9
of product
$/Mg
6.35
7.20
10.31
3.42
4.06
4.93
2.93
3.68
4.39
6.62
6.64
9.92
3.73
4.79
5.77
3.64
4.81
5.45
3.86
3.37
6.43
(5.93)
(6.00)
(6.03)
Effect on cost of product:3
Increase over ELOC
$/Mg
0.85
3.96
0.64
1.51
0.75
1.46
0.02
3.30
1.06
2.04
1.17
1.81
(~49)
2.57
-
-
-
Note: Values 1n parentheses represent net gains or credits.
'Based on a product price of $132/Mg of urea product ($120/ton).
-------
—I
I
TABLE 7-11. NET ANNUALIZED COST AND COST EFFECTIVENESS OF CONTROL
ALTERNATIVES FOR MODEL UREA FACILITIES (1Q80) (ENGLISH UNITS)
Case
1-1
1-2
1-3
2-1
2-2
2-3
3-1
3-2
3-3
4-1
4-2
4-3
5-1
5-2
5-3
6-1
6-2
6-3
7-1
7-2
7-3
Model Control
Plant Alternative
1 1
2
3
2 1
2
3
3 1
2
3
4 1
2
3
5 1
2
3
6 1
2
3
7 1
2
3
Net Annual
Cost 1000$
347.6
393.2
564.5
748.1
886.0
1079.1
961.0
1207.8
1441.6
362.4
362.6
543.0
815.9
1046.8
1262.1
1194.1
1573.3
1788.0
211.1
184.0
352.0
Cost Effectiveness
per unit urea recovered
$/ton
1178
1229
1686
634
692
806
543
629
718
2408
2286
2969
1355
1650
1725
1322
1653
1629
3507
1998
3315
Cost Effectiveness
Relative to ELOC+
$/ton
1839
5464
1374
2083
1642
2019
25
5574
7149
3443
7819
3057
(850)
3063
Effect on costb
of product
$/ton
5.77
6.53
9.38
3.11
3.68
4.48
2.66
3.34
3.99
6.02
6.03
9.02
3.39
4.35
5.24
3.31
4.36
4.95
3.51
3.06
5.85
Effect on cost of product:
Increase over ELOCa
$/ton
.76
3.61
0.57
1.37
0.68
1.33
0.01
3.00
0.96
1.85
1.05
1.64
(-45)
2.34
8-1 8 1 (649.1) ( 52.2) - (5.39)
9-1 9 1 (1314) ( 52.5) - (5.46)
10-1 10 1 (1979) ( 52.8) - (5.48)
Note: Values in parentheses represent net gains or credits.
aELOC = Existing Level of Control.
bBased on a product price of $132/Hg of urea product ($120/ton).
-------
7.1.2.6 Base Cost of Urea Plants. Capital costs of control alternatives
may be compared with the total capital costs of new urea manufacturing
plants. Table 7-12 presents ranges of average capital costs for complete
urea production plants, including solution synthesis, solution concentration,
and solids formation processes. These values may be compared with the
total capital costs and the capital cost relative to ELOC of each control
alternative presented in Table 7-7. The capital cost relative to ELOC
of control alternatives range from 3 to 7 percent of the total plant
costs.
The cost of producing urea has been estimated at 128 $/Mg (116
$/ton) for small plants and 101 $/Mg (92 $/ton) for large plants.17'18
The major cost component of urea is the cost of natural gas used in
manufacturing the ammonia feed to the urea synthesis process.
7.1.3 Existing Facilities
The cost for installing a control system in an existing plant is
generally greater than the cost of installing a control system in a new
facility with the same exhaust gas parameters because special design
modifications are often required.
Cost components that may increase because of space restrictions and
plant configuration are contractor and engineering fees, additional
ducting and structural reinforcement. These costs vary from place to
place and job to job depending on the difficulty of the job, the risks
involved, and current economic conditions.
Estimating this additional installation cost or retrofit penalty is
difficult because of these plant-specific factors and additional engineer-
ing requirements. However, these additional costs are not expected to
be large or to preclude the application of control equipment.
7.2 OTHER COST CONSIDERATIONS
7.2.1 Cost Imposed by Water Pollution Control Regulations
The costs of wastewater treatment at plants in the nitrogen fertilizer
22 23
industry have been researched by previous investigators. ' These
costs are related to effluent limitations placed on the fertilizer
industry and are not associated with air pollution control. Effluents
7-20
-------
TABLE 7-12. CAPITAL COSTS OF UNCONTROLLED UREA PLANTS7'18 (1Q80)
Plant Size Relevant Model Cost Range Average Cost
Mg/yr (TPD) Plant Number $ millions $ millions
181 (200) 1, 4, 7 7.2 - 9.2 8.2
363 (400) 8 11.7 - 17.2 14.4
726 (800) 2, 5, 9 19.2 - 27.4 23.3
1089 (1200) 3, 6, 10 25.8 - 33.2 29.5
7-21
-------
from air pollution control equipment are recycled to the solution
process for economic reasons. Therefore, no additional wastewater
treatment costs are expected due to air pollution control equipment.
7.2.2 Costs Imposed by Solid Waste Disposal Requirements
Due to the high solubility of urea, any solid wastes can be dissolved
and used as liquid fertilizer or recycled to the solution process to
produce solid urea. Thus, no additional solid waste is anticipated due
to air pollution control equipment.
7-22
-------
7.3 REFERENCES
1. Telecon. Brown, P., GCA Corporation, with Podhorski, J. ,
slubbers rin9' MarCh 12' 1979' C°StS and °ther t0pics c
2. Letter from Pi 1 cher, L.Y., GCA Corporation, to Hosier, R., W.W.
Sly. July 24, 1979. Wet scrubber costs.
3. Jelecon. Stelling, J., Radian Corporation, with Hosier, R. , W W
ily. May 2, 1980. Cost of plate impingement scrubbers.
4. Letter and attachment from Brady, J., Anderson 2000 Incorporated
nf wp?Il!!9f,-K M-S-'R??ian Corporation. May 9, 1980. Cost estimates
of wetted fibrous filter systems.
5. Peters MS. _ and K.D Timmerhaus. Plant Design and Economics for
Chemical Engineers, Second Edition. New York, McGraw-Hill Book
lompany, 1958. 850 p.
6. Neveril.RB (GARD, Incorporated). Capital and Operating Costs
of Selected Air Pollution Control Systems. (Prepared for the U S
Environmental Protection Agency.) Research Triangle Park, N.C ' '
Publication No. EPA-450/5-80-002. December 1978. pp. 3-1 through
0*~ / O •
7. Guthrie, K.M. Process Plant Estimating, Evaluation and Control.
bolana Beach, California, Craftsman Book Company of America, 1974.
D Uo p »
8' R° ln9lHeeHin9vSrviC?uS' InC' Process Plant Construction
Standards Volume Three. Solana Beach, California,
section 16-52.
9' plfim^nn ^ ***? ^^^ CeS ' Inc' Process Plant Construction
Estimating Standards, Volume Four. Solana Beach, California 1980
leoj'ioo - ^"a/foo -°6°52.281 thr°ugh 10° ' 283' '
10. Memo from Stelling J., Radian Corporation, to file. July 9, 1980
Cost analysis computations for regulatory alternatives.
11. Memo from Stelling, J., Radian Corporation, to file. July 2, 1980
Compilation of cost indices used in updating costs.
12. Memo from Battye, W., GCA Corporation, to file. September 7 1979
Summary of Section 114 responses. p^iuer /, iy/y.
13. Internal Revenue Service. Tax Information on Depreciation 1979
Pri-nl?ng Offl^WJB^Vp^' WaSh1ngt°n' D'C' U'S' Gove™nent
7-23
-------
14. PEDCo Environmental Incorporated. Cost Analysis Manual for Standards
Support Document. (Prepared for U.S. Environmental Protection
Agency.) Research Triangle Park, N.C. April 1979. 82 p.
15. U.S. Environmental Protection Agency and Manufacturing Chemists
Association. EPA-MCA Chemical Industry Cost Estimating Conference,
February 1977: Notebook. Washington, D.C., EPA:EPAD. January
1979. 107 p.
16. Memo from Stelling, J., Radian Corporation, to file. May 28, 1980
Determination of credit for recovered urea.
17. Memo from Stelling, J., Radian Corporation, to file. July 6, 1980.
Cost of manufacturing urea.
18. Chemical Engineering (ed.). Sources and Production Economics of
Chemical Products, Second Edition. New York, McGraw-Hill Publishing
Company, 1979. pp. 119-121, 277-279.
19. Martin, E. Development Document for Effluent Limitations Guidelines
and New Source Performance Standards for the Basic Fertilizer
Chemical Segment of the Fertilizer Manufacturing Point Source
Category. (Prepared for U.S. Environmental Protection Agency.)
Washington, D.C. Publication No. EPA-440/l-74-011a. March 1974.
p. 170.
20. David, M.L., J.M. Malk and C.C. Jones (Development Planning and
Research Associates, Inc.). Economic Impact of Costs of Proposed
Effluent Limitation Guidelines for the Fertilizer Industry.
(Prepared for U. S. Environmental Protection Agency.) Washington,
D.C. Publication No. EPA-230/1-73-010. October 1973. p. 213.
7-24
-------
APPENDIX A - EMISSION SOURCE TEST DATA
A.I PLANT DESCRIPTIONS AND TEST RESULTS
A.1.1 Introduction
Available EPA data on particulate emissions and visible emissions
from five different urea plants are presented in this Appendix. Results
of formaldehyde and ammonia emission measurements are also presented.
The uncontrolled and controlled emissions data included in this Appendix
are analyzed and discussed in Chapters 3 and 4 respectively.
The five plants where tests were performed are identified as Plants
A, B, C, D, and E. The sources tested at each plant are presented in
Tables A-l and A-2.
Mass emission measurements were determined by methods designated by
EPA to provide consistent data and are similar or identical to the
modified Method 5 presented in Appendix B. Visible emission measure-
ments were performed according to EPA Method 9 by a certified visible
emission evaluator. Particle size distributions were determined using a
cascade impaction collector. All standard units are for 293 K (68°F)
and 29.92 in. Hg. of pressure.
A brief description of each facility is presented followed by
results of the testing. References for EPA emission tests are presented
in Section A.2.
A-l
-------
TABLE A-l. SUMMARY OF MASS EMISSION TESTING
Plant
PRILL TOWER
Type*
FEED GRADE
Scrubber Inlet Scrubber Outlet
AGRICULTURAL GRADE
Scrubber Inlet Scrubber Outlet
GRANULATOR
Scrubber Scrubber
Inlet Outlet
EMISSION
Urea
Particulates
A XXX
B XXX
Cb NFB XXX
D FB X X X X X
E NFB XX X
SPECIES
Ammonia
X
X
X
X
X
TESTED
Formaldehyde
X
X
X
NFB - non-fluidized bed
FB = Fluidized bed
Mass emission testing was also performed on a rotary drum cooler scrubber inlet
-------
TABLE A-2. SUMMARY OF VISIBLE EMISSIONS AND PARTICLE SIZE DISTRIBUTION TESTS
Plant
VISIBLE EMISSIONS
Granulator Frill tower Cooler
Scrubber Scrubber Scrubber
Outlet Outlet Outlet
PARTICLE SIZE DISTRIBUTIONS
Granulator Scrubber
Inlet Outlet
Prill Tower Scrubber
Inlet Outlet
Cooler Scrubber
Inlet Outlet
I
OO
A
B
C
Oa
E
Visible anlsslons were also determined for the outlet of a baghouse controlling bagging operations
Visible aiifsslons not tested during test on Unit "C"
-------
4.1.2 Plant A1'2
Testing at Plant A was performed to gather urea particulate,
ammonia, and formaldehyde emission data for the "A" and "C" granulators.
Urea and ammonia emission measurements were also performed on the main
vent for the urea solution synthesis and concentration process. The
granulators operate on a 24 hr/day, 7 days/week basis at a production
rate of approximately 363 Mg/day (400 tons/day) for each. Each granulator
exhaust is ducted through a wet entrainment scrubber and fan before
being discharged from a stack. The urea synthesis and concentration
process operates on a continuous basis to provide urea solution for the
entire urea plant. The exhaust from this process is vented from four
locations which are combined and discharged through a common stack.
Testing was performed at the outlet of this common stack.
Mass emission tests and particle size distributions were conducted
on the gas entering and exiting the "A" granulator scrubber. Visible
emissions were determined for the exhaust exiting the 26 meter (85 foot)
vertical stack from the "A" granulator scrubber. Mass emission tests
were also conducted on gases exiting the "C" granulator scrubber. Two
different tests were performed to examine and evaluate factors affecting
the accuracy of urea sampling and analytical techniques. Objectives of
this study included establishment of a reference and analysis method
quantification of possible sample degradation during storage (conversion
of urea to other components) determination of the accuracy and con-
sistency of analytical methods, and evaluation of the interfering
effects of ammonia in the sample. This study concluded that urea
particulate measurements for both granulator tests are representative
of emissions.
The results reported for the urea and formaldehyde measurements
were determined for the samples using the colorimetric method of analysis.
Ammonia concentrations were determined by direct nesslerization, for
granulator "A" and nesslerization with preliminary distillation for
granulator "C". Outlet emission data for test run 9 on October 11, 1978
was discredited because a portion of the sample was lost.
A-4
-------
TABLE A-3. SUMMARY OF RESULTS OF UREA, AMMONIA, AND FORMALDEHYDE TESTS
ON GASES ENTERING AND EXITING THE "A" GRANULATOR SCRUBBER
AT PLANT A (English Units)
Te:t "to.
General Data
Date
Isokinetic (%)
Production Rate (- Ton/day)
Ambient Temp. °F (Ave. Dry bulb)
Relative Humidity
Exhaust Characteristics
Flowrate inlet:
(dscf/min) outlet:
Temperature inlet:
(F°) outlet:
Moisture (% Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (in. W.G. ) ,
Liquid/Gas Ratio (gal/1000 ft )
Liquor pH (Ave.)
Liquor Urea Cone. (Ib/gal) inlet:
outlet:
Urea Emissions
Particulate Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency (*)
Ammonia Emissions
Ammonia Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet
Collection Efficiency (%}
Formaldehyde Emissions
Formaldehyde Con. inlet
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
Ob/ton) outlet:
Collection Efficiency
i
10-10-78
97.2
395
b
48970
52020
161
100
1.6
4.3
17.9
b
9.4
0.180
4.220
11.260
0.00566
4726
2.523
286.1
0.154
99.9
0.0934
0.194
39.19
86.31
2.372
5.282
<0
b
b
b
b
b
b
b
2
10-10-78
96.6
389
b
50020
53090
163
98
2.1
4.1
3
10-11-78
99.0
350
b
b
50670
55420
161
103
2.8
3.4
Entrainment Scrubber
16.3 14.6
b
9.5
0.323
8.440
13.050
0.0104
5594
4.723
347.2
0.290
99.9
0.0942
0.361
38.77
164.30
2.406
10.080
<0
b
b
b
b
b
b
b
L>
9.3
0.412
4.85_7
10.940
0.00834
4753
3.953
325.7
0.271
99.9
0.0813
0.282
35.28
134.00
2.418
9.182
<0
b
b
b
b
b
b
Ave.
97.2
378
b
b
49890
53500
162
100
2n
.2
3Q
. y
16.3
k
U
9.4
0.305
5.749
11.75
0.00812
5024
3.733
319.7
0.238
99.9
0.0846
0.273
37.75
128.20
2.399
8.181
<0
b
k
U
b
b
not available
A-5
-------
TABLE A-4. SUMMARY OF RESULTS OF UREA, AMMONIA, AND FORMALDEHYDE TESTS
ON GASES ENTERING AND EXITING THE "A" GRANULATOR SCRUBBER
AT PLANT A. (Metric Units)
Test No.
General Data
Date
Isokinetic (?)
Production Rate (Mg/day)
Ambient Temp (K) (Dry Bulb)
Relative Humidity («)
Exhaust Characteristics
Flowsate inlet:
(dsm"/min) outlet:
Temperature inlet:
(K) outlet:
Moisture (* Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (kPa) ,
Liquid/Gas Ratio (1/m )
Liquor pH (Ave.)
Liquor Urea Conc.(mg/i ) inlet:
outlet:
Urea Emissions
Participate Cone. inlet:
(g/dsm3) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (%)
Ammonia Emissions
Ammonia Cone. inlet:
(g/dsm ) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (")
Formaldehyde Emissions
Formaldehyde Con. inlet:
(g/dsnT) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
1(T (g/kg) outlet:
Collection Efficiency (5!)
1
10-10-78
97.2
359
b
b
1385
1472
345
310
1.0
4.3
4.475
b
9.4
21680
506200
25.761
0.0129
35760
19.091
143.05
0.077
99.9
. 0.213
0.444
296.54
653.08
' 1.186
2.641
<0
b
b
b
b
b
b
b
2
10-10-78
76.6
353
b
1416
1502
346
308
2.1
4.1
Entrainment
4.025
b
9.5
38720
1012000
29.878
0.0230
42327
35.737
173.60
0.145
99.9
0.2571
0.826
293.36
1243.20
1.203
5.040
<0
b
b
b
b
b
b
b
3
10-11-78
94.0
318
b
1434
1568
345
312
2.8
3.4
Scrubber
3.650
9.3
49360
550000
25.046
0.0191
35964
29.911
162.85
0.136
99.9
0.186
0.646
266.95
1013.93
1.204
4.591
<0
b
b
b
b
b
b
Ave.
97.2
343
1411
1514
345
310
2.2
3f\
.9
4.075
9.4
36590
689402
26.899
0.0185
38015
28.246
159.85
0.119
99.9
0.205
0.625
285.64
970.04
1.199
4.041
,r\
-------
TABLE A-5 SUMMARY OF RESULTS OF UREA, AMMONIA, AND FORMALDEHYDE TESTS
TABLE A 5. gUWWY^Kt^ ^ ^ G»ANULATOR $CRUBBER AT PLANT A
(English Units)
Test No.
General Data
Date
Isokinetic (%)
Production Rate (Tons/day)
Ambient Temp.(°F)(Ave. Dry bulb)
Relative Humidity
Exhaust Characteristics
Flow rate inlet:
(dscf/min) outlet:
Temperature inlet:
(F°) outlet:
Moisture (% Vol.) inlet:
outlet:
Control Oevics Characteristics
Device Type
Pressure Drop (in. W.G. ) 3
Liquid/Gas Ratio (gal/1000 ftj)
Liquor pH (Ave.)
Liquor Urea Cone, (ib/gal) inlet:
outlet:
SJrea Emissions
Particulate Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(lb/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency (?)
Ammonia Emissions
Ammonia Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(lb/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet
Collection Efficiency (%)
Formaldehyde Emissions
Formaldehyde Con. inlet
(gr/dscf) outlet:
Emission Rate inlet:
(lb/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency
1
2
3
Ave.
10-11-78
100.7
347
b
52410
55350
157
99
1.6
5.4
15.5
b
b
b
b
11.01
b
4946
b
299
b
b
0.0936
b
42.040
b
2.541
b
b
0.000325
b
0.146
b
0.00883
b
b
10-11-/8 IU-U-/Q
101.7 101.2
400 418
h h
o
b
50270
54380
162
102
7 &
L . *r
A 1
H.I
Entrainment Scrubber
14.9
b
b
b
10.740
0.0126
4629
5.860
278
0.352
99.9
0.0614
0.134
26.450
62.480
1.589
3.750
,-n
-------
TABLE A-6. SUMMARY OF UREA, FORMALDEHYDE, AND AMMONIA TESTS
ON GASES ENTERING AND EXITING THE "A" GRANULATOR
SCRUBBERS AT PLANT A. (Metric Units)
Test No.
General Data
Date
Isokinetic (Z)
Production Rate (Mg/day)
Ambient Temp (K) (Dry Bulb)
Relative Humidity
Exhaust Characteristics
Flowcate inlet:
(dsm /min) outlet:
Temperature inlet:
(K) outlet:
Moisture (% Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (kPa) ,
Liquid/Gas Ratio (1/m )
Liquor pH (Ave. )
Liquor Urea Conc.(Mg/i) inlet:
outlet:
Urea Emissions
Participate Cone. inlet:
(g/dsm ) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (%)
Ammonia Emissions
Ammonia Cone. inlet:
(g/dsm ) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (%)
Formaldehyde Emissions
Formaldehyde Con. inlet:
(g/dsm ) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
10J (g/kg) outlet:
Collection Efficiency (?)
1
10-11-78
100
360
b
b
1484
1567
342
310
1.6
5.4
2
10-11-78
101
363
b
b
1424
1540
345
312
2.4
4.1
3
10-11-78
101
380
b
b
1432
1517
349
314
2.7
4.3
Ave.
101
368
b
b
1447
1541
345
312
2.3
4.6
Entrainment Scrubber
3.88
b
b
b
b
25.189
b
37425
b
149.5
b
b
0.214
b
318.10
b
1.271
b
b
0.000744
b
1.105
b
0.00442
b
b
3.73
b
b
b
b
24.572
0.0288
30026
44.34
139
0.176
99.9
0.140
0.306
200.14
472.76
0.795
1.875
<0
0.000185
0.000288
0.265
0.445
0.00105
0.00172
<0
3.53
b
b
b
b
23.107
0.00783
33111
11.08
125
0.0452
100
0.147
0.384
211.41
582.78
0.801
2.215
<0
0.000976
0,000164
1.399
0.248
0.0053
0.00095
82
3.70
b
b
b
b
24.297
0.0183
35185
28.15
138
0.111
99.9
0.164
0.345
243.19
527.78
0.955
2.045
<0
0.000631
0.000226
0.923
0.347
0.00355
0.00136
Not available
A-8
-------
TABLE A-7. SUMMARY OF RESULTS OF UREA, AMMONIA, AND FORMALDEHYDE TESTS
ON GASES EXITING THE "C" GRANULATOR SCRUBBER AT PLANT A.
(English Units)
Test No.
General Data
Date
Isokinetic (%)
Production Rate (TonS/day)
Ambient Temp. (°F)
Ambient Moisture (%}
Exhaust Characteristics
Flowrate inlet:
(dscfm) outlet:
Temperature inlet:
(F°) outlet:
Moisture (% Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (in. W.G. ) ,
Liquid/Gas Ratio (gal/1000 ft )
Liquor pH (Ave.)
Liquor Urea Cone. (%} (Ave.)
Urea Emissions
Particulate Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
Ob/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency (%)
Ammonia Emissions
Ammonia Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
Ob/hr) outlet:
Emission Factor inlet:
Ob/ton) outlet
Collection Efficiency (?)
Formaldehyde Emissions
Formaldehyde Con. inlet
(gr/dscf) outlet:
Emission Rate inlet:
Ob/hr) outlet:
Emission Factor inlet:
Ob/ton) outlet:
Collection Efficiency (%)
1
12-18-78
107
371
b
b
b
55180
b
92
b
6
b
b
b
fa
b
0,
b
13.
b
0.
b
b
0.
b
87.
b
5.
b
b
0.
b
0.
b
0.
b
2
12-19-78
.2 106.7
370
b
b
b
54220
b
102
b
.0 3.8
Entrainment Scrubber
b
fa
b
b
b
,0278 0.0431
b
,14 20.19
b
850 1.339
b
b
186 0.145
b
72 68.02
b
674 4.511
b
b
00172 0.00210
b
813 0.986
b
0526 0.0654
b
3
12-19-78
108.2
370
b
b
b
51130
b
104
b
5.1
b
b
b
b
b
0.170
b
7.438
b
0.493
b
b
0.279
b
122.36
b
8.114
b
b
0.00156
b
0.683
b
0.0453
b
A-9
-------
TABLE A-8. SUMMARY OF RESULTS OF UREA, AMMONIA, AND FORMALDEHYDE TESTS
ON GASES EXITING THE "C" GRANULATOR SCRUBBER AT PLANT A.
(Metric Units)
Test No.
General Data
Date
Isokinetic (%)
Production Rate (Mg/day)
Ambient Temp. (K)
Ambient Moisture (»}
Exhaust Characteristics
Flow rate inlet:
(dsmS/min) outlet:
Temperature inlet:
(K) outlet:
Moisture (1 Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (kPa) ,
Liquid/Gas Ratio 0/mJ)
Liquor pH (Ave. )
Liquor Urea Cone. (%) (Ave.)
Urea Emissions
Particulate Cone. inlet:
(g/dsm3) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (%}
Ammonia Emissions
Ammonia Cone. inlet:
( g/dsm3) outlet:
Emission Rate inlet:
( g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet
Collection Efficiency (%)
Formaldehyde Emissions
Formaldehyde Con. inlet
(g/dsm3) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency
1
12-18-78
107.2
336
b
b
b
1563
b
308
b
6.0
b
b
b
b
b
0.0636
b
5958C
b
0.425
b
b
0.424
b
39790
b
2.837
b
b
0.00393
b
369
b
0.0132
b
2
12-19-78
106.7
336
b
b
b
1550
b
312
b
3.8
Entrainment Scrubber
b
b
b
b
b
0.0985
b
9159JD
b
0.669
b
b
0.332
b
30860
b
2.256
b
b
0.00481
b
447
b
0.0327
b
3
12-19-78
108.2
336
b
b
b
1448
b
313
b
5.1
b
b
b
b
b
0.0388
b
3374JD
b
0.247
b
b
0.639
b
55500
'b
4.057
b
b
0.00356
b
310
b
0.0226
b
A-10
-------
TABLE A-9. SUMMARY OF RESULTS OF UREA, AMMONIA AND FORMALDEHYDE TESTS
ON THE GASES EXITING THE "C" GRANULATOR SCRUBBER AT PLANT A.
(English Units)
Test No.
General Data
Date
Isokinetic (%)
Production Rate (Tons/day)
Ambient Temp. 3F
Ambient Moisture («)
Exhaust Characteristics
Flowrate inlet:
( dscfm) outlet:
Temperature inlet:
(F D) outlet:
Moisture (', Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (in. W.G.) ..
Liquid/Gas Ratio (gal/1000 ftj)
Liquor pH (Ave. )
Liquor Urea Cone. (*) (Ave.)
Urea Emissions
Particulate Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlec:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency (%)
Ammonia Emissions
Ammonia Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet
Collection Efficiency (?)
Formaldehyde Emissions
Formaldehyde Con. inlet
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency
4
12-19-78
106.2
370
b
b
b
52910
b
103
b
4.9
5
12-19-78
106.2
370
b
b
b
51730
b
105
b
3.1
6
12-19-78
106.2
370
b
b
b
53750
b
104
b
3.8
Entrainment Scrubber
b
b
b
b
b
0.0239
b
10.85
b
0.720
b
b
0.161
b
72.95
b
4.84
b
b
0.00197
b
0.893
b
0.0592
b
b
b
b
b
0.0146
b
5.492
b
0.431
b
b
0.152
b
67.56
b
44.80
b
b
0.000974
b
0.432
b
0.0286
b
b
b
b
b
0.0230
b
10.61
b
0.704
b
b
0.139
b
64.04
b
4.25
b
b
0.00144
b
0.663
b
0.0439
Ave.
106.8
370
b
b
b
53237
b
102
b
4.5
b
b
b
b
b
0.0251
b
11.46
b
0.757
b
b
0.177
b
80.57
b
5.322
b
b
0.00164
b
0.746
b
0.0493
b = not available
A-ll
-------
TABLE A-10.
SUMMARY OF RESULTS OF UREA, AMMONIA, AND FORMALDEHYDE TESTS
ON GASES EXITING THE "C" GRANULATOR SCRUBBER AT PLANT A.
(Metric Units)
Test No.
General Data
Date
Isokinetic (?)
Production Rate (Mg/day)
Ambient Temp (K)
Ambient Moisture (")
Exhaust Characteristics
FlowKate
(dsm /min)
Temperature
U)
Moisture (% Vol.)
inlet:
outlet:
inlet:
outlet:
inlet:
outlet:
4
12-19-78
106.2
331
b
b
b
1498
b
312
b
4.9
5
12-19-78
106.
331
b
b
b
1465
b
314
b
3.
6
12-19-78
2 106.1
331
b
b
b
1522
b
313
b
1 3.8
Ave.
106.8
330
b
b
b
1508
b
312
b
4.5
Control Device Characteristics
Device Type
Pressure Drop (kPa) ,
Liquid/Gas Ratio (1/m
Liquor pH (Ave.)
Liquor Urea Cone. (*}
Urea Emissions
Participate Cone.
(g/dsm3)
Emission Rate
(g/hr)
Emission Factor
(g/kg)
Collection Efficiency (
Ammonia Emissions
Ammonia Cone.
(g/dsmj)
Emission Rate
(g/hr)
Emission Factor
(g/kg)
Collection Efficiency (
Formaldehyde Emissions
Formaldehyde Con.
(g/dsmj)
Emission Rate
(g/hr)
Emission Factor
(g/kg)
Collection Efficiency (
)
(Ave.)
inlet:
outlet:
inlet:
outlet:
inlet:
outlet:
'.)
inlet:
outlet:
inlet:
outlet:
inlet:
outlet:
•)
inlet:
outlet:
inlet:
outlet:
inlet:
outlet:
«)
b
b
b
b
b
0.0547
b
4921
b
0.360
b
b
0.368
b
J3040
b
2.419
b
b
0.00451
b
405
b
0.0296
b
Entrainment
b
b
b
b
b
0.
b
2945
b
0.
b
b
0.
b
30640
b
2.
b
b
0.
b
196
b
0.
b
Scrubber
b
b
b
b
b
0335 0.0527
b
4813
b
215 0.352
b
b
349 0.318
b
24050
b
240 2.124
b
b
00223 0.00329
b
301
b
0143 0.0219
b
b
b
b
b
b
C.0575
0
5198
b
0.378
b
b
0.404
b
36550
b
2.561
b
b
0.00374
b
338
b
0.0247
b
b = Mot available
A-1?
-------
TABLE A-ll.
SUMMARY OF RESULTS OF UREA AND AMMONIA TESTS ON
GASES EXITING THE SOLUTION SYNTHESIS TOWER VENT
AT PLANT A. (English Units)
Test -No.
General Data
Date
Isokinetic (%)
Production Rate Tons/day
Ambient Temp.(cP )
Ambient Moisture (%)
Exhaust Characteristics
Flowrate inlet:
(dscfni) outlet:
Temperature inlet:
(F°) outlet:
Moisture (' Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (in. W.G.) ,
Liquid/Gas Ratio 'gal/1000 ft )
Liquor pH (Ave. )
Liquor Urea Cone. (%}(Ave.)
'Jrea Emissions
Parti cul ate Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency (%)
Ammonia Emissions
Ammonia Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
Ob/ton) outlet
Collection Efficiency (%)
Formaldehyde Emissions
Formaldehyde Con. inlet
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency
1
10-13-78
b
b
b
b
b
1248
b
175
b
37.97
b
b
b
b
b
0.0061
b
0.065
b
b
b
b
117.2
b
1254
b
b
b
b
b
b
b
b
b
b
2
10-13-78
b
b
b
b
b
1202
b
185
b
88.37
None
b
b
b
b
b
0.00126
b
0.13
jj
b
b
b
137.5
b
1418
b
b
b
b
b
b
b
b
b
b
3
10-13-78
b
b
b
b
b
990.9
b
185
b
90.56
b
b
b
b
b
0.9152
b
0.13
b
b
b
b
131.7
b
1179
b
b
b
b
b
b
b
b
b
b
Ave.
b
b
b
b
b
1147
b
132
b
88.97
b
b
b
b
b
0.00752
b
0.11
b
b
b
b
128.8
b
1284
b
b
b
b
b
b
b
b
b
b
b = Not available
A-13
-------
TABLE A-12.
SUMMARY OF RESULTS OF UREA AND AMMONIA TESTS ON
GASES EXITING THE SOLUTION SYNTHESIS TOWER VENT AT
PLANT A. (Metric Units)
Test No.
General Data
Date
Isokinetic (%)
Production Rate (Mg/day)
Ambient Temp. (K)
Ambient Moisture (%}
Exhaust Characteristics
Floweate inlet:
(dsm /ciin) outlet:
Temperature inlet:
(K) outlet:
Moisture (% Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop C
-------
TABLE A-13. SUMMARY OF INLET AND OUTLET PARTICLE SIZING TEST RESULTS
ON "A" GRANULATOR SCRUBBER AT PLANT A
I
t—«
en
Sampling
Location
Scrubber
Inlet
Scrubber
Outlet
Scrubber
Outlet
Scrubber
Outlet
Scrubber
Inlet
Scrubber
Inlet
Test Test
Date Time
10/12/78 0919-0929
10/12/78 1109-1509
10/12/78 1629-2029
10/13/78 0855-1255
10/13/78 1316-1317
10/13/78 1508-1509
Aerodynamic
Size Range, ym
>2.2
>3.7
2.7-3.7
1.7-2.7
1.0-1.7
0.56-1.0
<0.56
>3.7
2.7-3.7
1.7-2.7
1.0-1.7
0.56-1.0
<0.56
>3.8
2.8-3.8
1.7-2.8
1.1-1.7
0.56-1.1
<0.56
>2.3
>2.4
Mass in
Size Range, %
100
98.7
0.00
0.14
0.21
0.39
0.39
89.35
0.00
7.32
1.31
1.05
0.97
65.34
0.00
4.54
0.67
23.89
5.56
100
100
-------
TABLE A-14. SIX MINUTE ARITHMETIC AVERAGES OF OCTOBER 10, 1978
OPACITY READINGS ON "A" GRANULATOR SCRUBBER STACK
AT UREA PLANT A
Test Date
10-10-78
Time
11:15
11:21
11:27
11:33
11:39
11:45
11:51
- 11:20
- 11:26
- 11:32
- 11:38
- 11:44
- 11:50
- 11:56
Average Opacity
for 6 minutes
5
5
5
5
5
5
5
A-16
-------
TABLE A-15. SIX MINUTE ARITHMETIC AVERAGES OF OPACITY
READINGS ON "A" GRANULATOR SCRUBBER STACK
AT UREA PLANT A
Avg. Opacity
Test Date Time for 6 min.
Avg. Opacity
Test Date Time for 6 min.
10-11-78 09:24-09:29
^
09:30-09:35
09:36-09:38*
09:47-09:52
09:53-09:58
09:59-10:04
10:05-10:10
10:11-10:16
10:17-10:22
10:23-10:28
10:29-10:34
10:35-10:40
10:41-10:44*
11:27-11:32
11:33-11:38
11:39-11:44
11:45-11:50
11:51-11:56
11:57-12:02
12:03-12:08
12:09-12:14
12:15-12:20
12:21-12:26
12:27-12:32
12:33-12:38
12:39-12:43*
13:43-13:48
13:49-13:54
13:55-14:00
14:01-14:06
14:07-14:12
14:13-14:18
5 10-11-78 14:19-14:24
5
5
5
5
5
5
5
5
5
3.3
0
0
3.7
3.9
2.9
4
2.5
3.3
1.8
3.4
4.2
4.7
4.3
4.8
5
5
5
4.2
5
3.9 '
14:25-14:30
14:31-14:36
14:37-14:42
14:43-14:48
14:49-14:54
14:55-15:00
15:01-15:06
15:07-15:12
16:10-16:15
16:16-16:21
16:22-16:27
16:28-16:33
16:34-16:39
16:40-16:45
16:46-16:51
16:52-16:57
16:58-17:03
17:04-17:09
17:10-17:15
17:16-17:21
17:22-17:27
17:28-17:33
17:34-17:39
16:40-17:45
17:46-17:51
17:52-17:57
17:58-18:03
18:04-18:09
18:10-18:15
18:16-18:21
18:22-18:25*
4.5
5
5
4.5
2.5
3.2
0.8
0.9
3.2
4
5
4.6
5
1.8
3.7
1.1
.5
.3
0
0
0
0
0
.6
.5
0
.3
1.5
.7
.5
1.3
0.8
0.7
^Averaging time less than 6 minutes.
A-17
-------
TABLE A-16. SIX MINUTE ARITHMETIC AVERAGES OF
OPACITY READINGS ON "A" GRANULATOR SCRUBBER STACK
AT UREA PLANT A
Test Date Time
10-12-78 14:45-14:50
14:51-14:56
14:57-15:02
15:03-15:08
15:09-15:14
15:15-15:20
15:21-15:26
15:27-15:30*
Average Opacity
for 6 Minutes
1.9
1.3
0.6
2
0
1.4
0
1.4
*Averaging time less than 6 minutes,
A-18
-------
A. 1.3 Plant B3
Testing at Plant B was performed to gather urea particulate,
ammonia, and formaldehyde emission data for the "B" granulator as well
as urea and ammonia emission data from the urea solution synthesis and
concentration process. The granulator operates on a 24 hrs/day, 7 day/
week schedule. Exhaust from the granulator is ducted to a wet entrain-
ment scrubber and then a fan prior to being discharged through a 24
meter (80 foot) vertical stack. Testing was performed on the gases
entering the granulator scrubber. The urea synthesis and concentration
process operates continuously to provide urea solution for the entire
urea plant. The exhaust from this process is vented from four locations
which are combined and discharged through a common stack. Testing was
performed at the outlet of this common stack.
Particle size distributions were determined for the granulator
exhaust entering the granulator scrubber. Visible emissions tests were
conducted on the emissions exiting the vertical exhaust stack from the
scrubber.
The urea concentration in the samples was determined by the Kjeldal
method of analysis and is corrected for possible urea loss during analysis,
Ammonia concentrations were determined by direct nesslerization and
corrected for possible conversion of urea to ammonia. Formaldehyde data
was determined by the chromotropic acid method of analysis.
The inlet percent moisture values reported for the stack gas were
based on separate moisture test runs. Moisture contents is typically
measured concurrently with each test run.
A-19
-------
TABLE A-17.
ONMGASES°ENTERINTS °F UREA> AMMONIA' AND FORMALDEHYDE TESTS
Test No.
• . —
General Data
Date
Isokinetic (?)
Production Rate (Tons/day)
Ambient Temp. °F (Ave. Dry bulb)
Relative Humidity (%)
Exhaust Characteristics
Flow ate inlet-
(dscfm) outlet!
Temperature inlet:
(< i outlet-
Moisture (t Vol.) inlet!
outlet:
Control Device Characteristics
Device Type
Pressure Drop (in. W.G.)
Liquid/Gas Ratio (gal/1000 ft 1
Liquor pH (Ave.)
Liquor Urea Cone. ( Ib/gal) inlet:
outlet:
Urea Emissions
Particulate Cone. inlet-
(gr/dscf) outlet-
Emission Rate inlet-
(lb/hr) outlet!
Emission Factor inlet-
Ob/ton) outlet.
Collection Efficiency (%)
Ammonia Emissions
Ammonia Cone. inlet-
(gr/dscf) outlet:
emission Rate inlet-
Ob/hr) outlet:
Emission Factor inlet-
Ob/ton) Out1et
Collection Efficiency (%)
Formaldehyde Emissions
Formaldehyde Con. inlet
(gr/dscf) outlet:
Emission Rate inlet:
Emission Factor inlet-
Ob/ton) outlet!
Collection Efficiency (%)
1
01-17-79
1 n-5
1UZ
a
69
76
40180
46260
10?
i y£
101
7 757
c. £3 i
5 522
J» v>C£.
b
8£
.0
.00000101
. 00458
6.238
0.0113
2147
4.499
119.3
0.248
99.8
0.0999
0.0676
34.40
26. 80
1.90
1.48
22.1
0.000604
0.000379
0.2070
0.1503
0.0115
0.0083
27 7
C / • /
""
2
01-17-79
103
a
68
82
41410
45590
190
101
2.253
5.733
Entrainment Scrubber
20.5
b
8.7
.000000739
. 00466
6.516
0.0118
2312
4.583
123.5
0.255
99.8
0. 1029
0.1041
36.52
40.17
2.03
2.26
0
0.000361
M76
0.0687
.0071
.0038
46.3
=
3
11
01-18-79
102
a
67
84
41760
45760
183
103
2.257
5.608
20.6
b
8.7
.000000838
. 00478
6.511
0.0101
2330
3.931
134.0
0.226
99.8
0.1191
0.0582
42.62
22.82
2.45
1.31
46.5
0.000715
0.000195
0.2560
0.0764
0.0147
0.0044
70.2
Ave.
102
a
68
80
41117
45870
189
101
2.256
5.621
20.7
b
8.7
.00000086
.00468
6.425
0.110
2264
4.342
127.2
0.244
99.8
0.1073
0.0766
37.85
30.10
2.13
1.69
20.5
0.000560
9.QOQ250
0.0111
0.0055
50.2
a = considered confidential by manufacturer
b = not available
A-20
-------
TABLE A-18.
SUMMARY OF RESULTS OF UREA AMMONIA, AND FORMALDEHYDE
TESTS ON GASES ENTERING AND EXITING THE "B" GRANULATOR
SCRUBBER AT PLANT B (Metric Units)
Test No.
General Data
1
Date 01-17-79
Isokinetic (%) 103
Production Rate (Mg/day) a
Ambient Temp. (K) 294
Relative Humidity {%) 76
Exhaust Characteristics
FT owcate
(dsm /min)
Temperature
(K)
Moisture (X Vol.)
inlet:
outlet:
inlet:
outlet:
inlet:
outlet:
1111
1238
362
312
2.
5.
257
522
2
01-17-79
104
a
293
82
1147
1217
361
312
2
5
3
Ave.
01-18-79
102
a
293
84
.253
.733
1161
1222
357
313
2.
5.
257
508
103
a
293
80
1138
1225
360
312
2
5
.256
.621
Control Device Characteristics
Device Type
Pressure Drop (kPa)
Liquid/Gas Ratio (1/m
Liquor pH (Ave.)
Liquor Urea Cone. Mg/i
Urea Emissions
Participate Cone.
(g/dsm )
Emission Rate
(9/hr)
Emission Factor
(g/kg)
Collection Efficiency
Ammonia Emissions
Ammonia Cone.
(g/dsnT)
Emission Rate
(g/hr)
Emission Factor
(g/kg)
Collection Efficiency
Formaldehyde Emissions
Formaldehyde Con.
(g/dsnT)
Emission Rate
(g/hr)
Emission Factor
(g/kg)
Collection Efficiency
Entrainment Scrubber
)
inlet:
outlet:
inlet:
outlet:
inlet:
outlet:
inlet:
out! et :
U)
inlet:
outlet:
inlet:
outlet:
inlet:
outlet:
(*)
inlet:
outlet:
inlet:
outlet:
inlet:
outlet:
W
10.
b
8.
122
552400
13.
0.
910400
1907
59.
0.
99.
0.
0.
15600
12160
0.
0.
22.
45
6
340
0242
65
116
8
229
155
95
74
1
10
b
8
89
561900
13
0
980230
4
.25
.7
.930
.0252
.90
64.25
0
99
0
0
16560
18450
1
1
<0
0.00138
0.00220
94.
4
0.
0.
27.
20
000068
00575
00410
8
0
0
46
.119
.8
.235
.238
.01
.13
.000826
.000402
.000058
.0000311
.00355
.00190
.3
10.
b
8.
101
576000
13.
0.
987900
1660
27.
0.
97.
0.
0.
19330
10350
1.
0.
46.
t
0.
0.
70.
30
7
920
0215
0
105
8
272
133
22
65
5
00164
00045
0000116
000035
00735
00220
1
20
b
3
104
563400
13
0
95980056
1841
63.
0
99
0
0
17170
13650
1
0
20
0
0
50
.35
.7
.740
.0236
• 60
'.114
.8
.246
.175
.06
.85
.5
.00130
.000572
.0000894
.0000446
.00550
.00270
.3
a = Considered confidential by manufacturer
b = Not available
A-21
-------
TABLE A-19.
SUMMARY OF RESULTS OF UREA, AND AMMONIA TESTS ON
GASES EXITING THE SOLUTION SYNTHESIS TOWER VENT
AT PLANT B. (English Units)
Test No.
General Data
Date
Isokinetic (%)
Production Rate Tons/day
Ambient Temp. °F
Ambient Moisture (%)
Exhaust Characteristics
Flowrate inlet:
(dscfoi) outlet:
Temperature inlet:
(F°) outlet:
Moisture (? Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (in. W.G.) -,
Liquid/Gas Ratio (gal/1000 ftj
Liquor pH (Ave.)
Liquor Urea Cone. {»} Ave.)
Urea Emissions
Particulate Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency (%)
Ammonia Emissions
Ammonia Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet
Collection Efficiency (?)
Formaldehyde Emissions
Formaldehyde Con. inlet
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency
a = Considered confidential by
b * Not available
1
01-18-79
84.2
a
b
b
b
306
b
193
b
67
b
) b
b
b
b
0.614
b
1.62
b
0.0271
b
b
115.2
b
302.0
b
5.09
b
b
b
b
b
b
b
manufacturer
2
01-19-79
66.5
a
b
b
b
402
b
136
b
57.9
None
b
b
b
b
b
0.615
b
2.12
b
0.0377
b
b
141.3
b
486.6
b
8.64
b
b
b
b
b
b
b
3
01-19-79
77.9
a
b
b
b
339
b
191
b
64.5
b
b
b
b
b
0.593
b
1.72
b
0.0306
b
b
174.5
b
506.8
b
9.00
b
b
b
b
b
b
b
Ave.
76.2
a
b
b
b
349
b
190
b
63.1
b
b
b
b
b
0.619
b
1.82
b
0.0317
b
b
143.5
b
431
b
8.02
b
b
b
b
b
b
b
A-22
-------
TABLE A-20.
SUMMARY OF RESULTS OF UREA AND AMMONIA TESTS ON GASES
EXITING THE SOLUTION SYNTHESIS TOWER VENT AT PLANT B.
(Metric Units)
Test No.
General Data
Date
Isokinetic (?)
Production Rate (Mg/day)
Ambient Temp.
Ambient Moisture (*«)
Exhaust Characteristics
Flowcate inlet:
(dsm /rain) outlet:
Temperature inlet:
(K) outlet:
Moisture (", Vol.) inlet:
outlet: '
Control Device Characteristics
Device Type
Pressure Droo (kPa) ,
Liquid/Gas Ratio (1/m )
Liquor pH (Ave. )
Liquor urea Cone. ('') (Ave.)
Urea Emissions
Parti oil ate Cone. inlet:
(g/dsm3) outlet:
Emission Rate inlet:
(g/nr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (%)
Ammonia Emissions
Ammonia Cone. inlet:
(g/dsm3) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet
Collection Efficiency (?)
Formaldehyde Emissions
Formaldehyde Con. inlet
(g/dsm3) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (%)
1
01-18-79
84.2
a
b
b
b
8.660
b
362
b
67
b
b
b
b
b
1.405
b
735.5
b
0.0136
b
b
263.3
b
137108
b
2.545
b
b
b
b
b
b
b
b
=
2
01-19-79
66.5
a
b
b
b
11.377
b
359
b
57.9
None
b
fa
b
b
b
1.407
b
962.5
b
0.0189
b
b
323.3
b
220916
b
4.320
b
b
b
b
b
b
b
b
3
01-19-79
77.9
a
b
b
b
9.594
b
361
b
64.5
b
b
b
b
b
1.357
5
780.9
b
0.0153
b
b
399.3
b
230087
b
4.500
b
b
b
b
b
b
b
b
Ave.
76.2
a
b
b
b
9.877
b
360
b
63.1
b
b
b
b
b
1.416
b
826.3
b
0.0159
b
b
328.3
b
195674
b
4.010
b
b
b
b
b
b
b
b
A-23
-------
TABLE A-21. SUMMARY OF INLET PARTICLE SIZE TEST RESULTS ON 'B1 GRANULATOR
SCRUBBER INLET ON JANUARY 18, 1979, AT UREA PLANT B
Sampling
Location
Scrubber Inlet
Scrubber Inlet
Scrubber Inlet
3=-
ro
Test
Date
1/18/79
1/19/79
1/19/79
Test
Time
15:28-15:43
10:00-10:15
11:25-11:40
Aerodynamic
Size Range, urn
> 6.0
> 5.7
> 5.8
Mass in
Size Range, %
99+
99+
99+
-------
TABLE A-22. SIX MINUTE ARITHMETIC AVERAGE OPACITY READINGS
ON "B" GRANULA.TOR SCRUBBER STACK AT PLANT B
6 Minute
Date Time Period
1-17-79 12:02
^
12:08
12:14
12:20
12:26
12:32
12:38
12:44
12:50
12:56
13:02
13:08
13:14
13:20
13:26
13:32
13:38
13:44
13:50
13:56
14:02
14:08
14:14
14:20
15:50
15:56
16:02
16:08
16:14
16:20
16:26
16:32
- 12:07
- 12:13
- 12:17
- 12:25
- 12:31
- 12:37
- 12:43
- 12:49
- 12:55
- 13:01
- 13:07
- 13:13
- 13:19
- 13:25
- 13:31
- 13:37
- 13:43
- 13:49
- 13:55
- 14:01
- 14:07
- 14:13
- 14:19
- 14:22*
- 15:55
- 16:01
- 16:07
- 16:13
- 16:19
- 16:25
- 16:31
- 16:36*
Avg. Opacity
for 6 min.
8.2
6.3
5.8
5.6
5.2
6.5
6.5
6.9
8.1
8.1
8.3
7.9
9.4
7.3
9.4
8.3
7.7
8.3
8.6
7.4
7.6
8.4
8.8
9.0
9.6
8.5
8.5
8.2
9.3
7.7
8.0
9.7
*Less than 6 min. average.
A-25
-------
TABLE A-23.
SIX MINUTE ARITHMETIC AVERAGE OPACITY READINGS
ON "B" GRANULATOR SCRUBBER STACK AT PLANT B
6 Minute
Date Time Period
1-19-79 09:53 -
09:59 -
10:05 -
10:11 -
10:17 -
10:33 -
10:29 -
10:35 -
10:41 -
10:47 -
10:53 -
10:59 -
11:05 -
11:11 -
11:17 -
11:23 -
11:29 -
11:35 -
11 :41 -
" 11:47 -
1-18-79 12:44 -
>
12:50 -
12:56 -
13:02 -
13:08 -
13:14 -
13:20 -
13:26 -
, 13:32 -
09:58
10:04
10:10
10:16
10:22
10:28
10:34
10:40
10:46
10:52
10:58
11:04
11:10
11:16
11:22
11:28
11:34
11:40
11:46
11:52
12:49
12:55
13:01
13:07
13:13
13:19
13:25
13:31
13:37
Avg. Opacity
for 6 min.
9.3
8.5
7.4
8.3
7.4
8.1
7.1
7.3
8.5
8.5
9.0
8.2
9.6
8.3
8.8
8.5
8.8
7.9
7.7
7.3
9.0
6.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
13:38 - 13:43
5.0
A-26
-------
A.1.4 Plant C4'5
Testing was conducted at Plant C to determine the urea and ammonia
emissions in gases exiting one of four scrubbers on a prill tower and at
the inlet of a rotary drum cooler scrubber. The testing was performed
during the production of fertilizer grade urea. The prill tower operates
at approximately 336 Mg/day (370 tons/day) on a 24 hr/day, 7 days/week
basis. The prill tower exhaust is controlled by four packed bed wet
scrubbers of in-house design. The exhaust from the rotary drum cooler
is controlled by a mechanically aided scrubber.
Particle size distributions were determined for the gases entering
the prill tower scrubber and the rotary drum cooler scrubber. Tests
performed on April 2nd and 3rd, 1979 were conducted during agricultural
grade urea production. Tests performed on April 4th and 6th, 1979 were
conducted during feed grade urea production. Visible emissions were
conducted during both agricultural and feed grade urea productions for
the outlet stacks from the prill tower scrubbers, and during agricultural
grade urea production on the outlet of the rotary drum cooler scrubber.
Also presented are flowrates through all four prill tower scrubbers.
This is presented to verify that conditions in the single tested scrubber
are representative for all four scrubbers.
Mass emission samples (April 1980) were analyzed for urea content
with the p-dimethylaminobenzadehyde analysis method. Mass emission
samples were analyzed for ammonia content with the specific ion electrode
analysis method.
A-27
-------
TABLE A-24.
SUMMARY OF UREA, AMMONIA, AND FORMALDEHYDE TESTS
ON GASES ENTERING PRILL COOLER SCRUBBER DURING
FERTILIZER GRADE PRODUCTION AT PLANT C. (English Units)
Test No.
General Data
date
Isokinetic (%)
Production Rate (Tons/day)
Ambient Temp °F
Relative Humidity (")
Exhaust Characteristics
Flowcate inlet:
(dscfm) outlet:
Temperature Inlet:
(F°) outlet:
Moisture (% Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Croo (in W.3.) ,
Liquid/Gas Ration (gal/1000 ft )
Liquor pH (Ave.)
Liquor Urea Conc.(^g/i) inlet:
outlet:
Urea Emissions
Particulate Cone. inlet:
(gr/dscf) outlet:
emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency (»)
Ammonia Emissions
Ammonia Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
fib/ton) outlet:
Collection Efficiency (%)
Formaldehyde Emissions
Formaldehyde Con. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency (r°)
1
04-23-80
105
281
b
b
7696
b
126.6
b
2.991
b
2
04-28-80
106
281
b
b
7102
b
126.7
b
3.336
b
3
04-28-80
106
281
b
b
7733
b
124.4
b
3.270
b
Ave.
106
281
57.3
80.3
7510
b
125.9
b
3.199
b
Entrainment Scrubber
b
K
b
b
b
1.531
107.67
b
9.197
b
b
0.00661
b
0.436
b
0.0372
b
b
b
b
b
b
b
b
b
b
b
b
b
b
1.243
75.52
b
6.468
b
b
0.0105
b
0.638
b
0.0545
b
b
b
b
b
b
b
b
b
b
b
b
b
b
1.353
39.55
b
7.686
b
b
0.0109
b
0.723
b
0.0618
b
b
b
b
b
b
b
b
b
b
b
b
b
b
1.413
b
90.96
b
7.450
b
b
0.00931
b
0.599
b
0.0512
b
b
D
b
b
b
b
b
b
a - Considered confidential by manufacturer
b = not available
A-28
-------
TABLE A-25.
SUMMARY OF UREA, AMMONIA, AND FORMALDEHYDE TESTS
ON GASES ENTERING PRILL COOLER SCRUBBER DURING
FERTILIZER GRADE PRODUCTION AT PLANT C. (Metric Units)
Test Ho.
General Data
Date
Isotdnetic ('•)
Production Rate (Mg/day)
Ambient Temp. (K)
Relative Humidity
Exhaust Characteristics
Flowicate inlet:
(dsm /min) outlet:
Temperature inlet:
('<) outlet:
Moisture (% Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (kPa) ,
Liquid/Gas Ratio (1/m )
Liquor pH (Ave. )
Liquor Urea Cone. Mg/i inlet:
outlet:
Urea Emissions
Paniculate Cone. inlet:
(g/dsmj) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (%)
Ammonia Emissions
Ammonia Cane. inlet:
(g/dsm ) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (*.)
Formaldehyde Emissions
Formaldehyde Con. inlet:
(g/dsm ) outlet:
Emission Rate inlet:
(g/min) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (?)
1
04-23-80
105
255
b
b
218.0
b
325.5
b
2.991
b
2
04-28-80
106
255
b
b
201.1
b
325.5
b
3.336
b
3
04-28-30
106
255
b
b
219.0
b
324.3
b
3.270
b
Ave.
106
255
287.9
80.3
212.7
b
325.1
b
3.199
b
Entrainment Scrubber
b
b
b
0.0243
b
3.733
b
48854
b
4.599
b
b
0.0151
b
197.4
b
0.0186
b
b
b
b
b
b
b
b
b
b
b
b
0.0225
b
2.845
b
34350
b
3.234
b
b
0.0239
b
289.7
b
0.0273
b
b
b
b
b
b
b
b
b
b
b
b
0.0242
b
3.096
b
40700
b
3.343
b
b
0.0249
b
328.0
b
0.0309
b
b
b
b
b
b
b
b
b
b
b
0.0237
b
3.224
b
41300
b
3.725
b
b
0.0214
b
271.9
b
0.0256
b
b
b
b
b
b
b
b
b
a = Considered confidential by manufacturers
b = Not available
A-29
-------
TABLE A-26.
SUMMARY OF UREA, AMMONIA, AND FORMALDEHYDE TESTS
ON GASES EXITING PRILL TOWER NORTHEAST SCRUBBER DURING
AGRICULTURAL GRADE PRODUCTION AT PLANT C. (English Units)
Test No.
General Data
Date
Isokinetic (%}
Production Rate (Tons/day)
Ambient Temp (°F) (dry bulb)
Relative Humidity (5.)
Exhaust Characteristics
Flowrate inlet:
(dscfm) outlet:
Temperature inlet:
outlet:
Moisture (% Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (in W.G.) •,
Liquid/Gas Ratio (gal/ 1000 ft )
Liquor pH (Ave.)
Liquor Urea Cone. (-".) inlet:
outlet:
Urea Emissions
^articulate Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlat:
(Ib/hr) outlet:
Emission Factor inlet:
fib/ton) outlet:
Collection Efficiency (%)
Ammonia Emissions
Ammonia Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency (5)
Formaldehyde Emissions
Formaldehyde Con. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
( Ib/hr) outlet:
Einission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency (?)
1
04-24-80
106
288
b
b
b
13076
b
77
b
4.779
In
b
b
b
127.9 E-09
b
b
0.0127
b
1.423
b
0.119
b
b
0.0281
b
3.149
b
0.262
b
b
b
b
b
b
b
b
2
04-25-80
104
300
63
55
b
13730
b
76
b
a.
House Design
b
b
b
118.
b
b
0.
b
0.
b
0.
b
b
0.
b
3,
b
0.
b
b
b
b
b
b
b
b
3
04-25-80
109
295
70
52
b
13870
b
77
b
584 5.676
Wet Scrubber
b
b
b
8 E-09 127. 1 E-09
b
b
00796 0.00926
b
,937 1.101
b
0749 0.0896
b
b
,0310 0.0561
b
,644 6.668
b
,152 0.542
b
b
b
b
b
b
b
b
Ave.
106
295
69
54
b
13559
b
77
b
5.020
b
b
b
124.5 E-09
b
b
0.00993
b
1.154
b
0.0938
b
b
0.0384
b
4.487
b
0.319
b
b
b
b
b
b
b
b
b = Not available
A-
-------
TABLE A-27. SUMMARY OF UREA, AMMONIA, AND FORMALDEHYDE TESTS
ON GASES EXITING PRILL TOWER NORTHEAST SCRUBBER AT
PLANT C DURING AGRICULTURAL GRADE PRODUCTION (Metric Units)
Test No.
General Data
Date
Isokinetic (*,)
Production Rate (Mg/day)
Ambient Temp (K)(dry bulb)
Relative Humidity (")
Exhaust Characteristics
Floweate inlet:
(dsrtr/min) outlet:
Temperature inlet:
(K) outlet:
Moisture (% Vol .) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (kPa) ,
Liquid/Gas Ratio (1/m )
Liquor pH (Ave.)
Liquor Urea Conc.(")(Ave.)inlet:
outlet:
Urea Emissions
Participate Cone. inlet:
(g/dsm ) outlet:
Emission Rate inlet:
(g/nr) outlet:
Emission Factor inlet:
(g/kg) outlet;
Collection Efficiency (",)
Anwionia Emissions
Ammonia Cone. inlet:
(g/dsm } outlet:
Emission Rate inlet:
(g/nr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (»}
Formaldehyde Emissions
Formaldehyde Con. inlet:
(g/dsm ) outlet:
Emission Sate inlet:
(g/min) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (%}
I
04-24-30
106
262
b
b
370.3
b
298
b
4.779
b
b
8.62
0.0243
b
b
0.0291
b
645.8
b
0.059
b
b
0.0643
b
1430
b
0.136
b
b
b
b
b
b
b
b
2
04-25-30
104
272
293
55
3*2.7
b
297
b
4.584
Wet Scrubber
b
b
8.38
0.0225
b
b
0.0182
b
425.2
b
0.0374
b
&
0.0709
b
1654
b
0.146
b
b
b
b
b
b
b
b
3
04-25-80
109
268
294
52
388.8
b
296
b
5.676
b
b
8.53
0.0242
b
b
0.0212
b
499.8
b
0.0443
b
b
0.0128
b
3027
b
0.271
b
b
b
b
b
b
fa
b
Ave.
107
268
294
54
383.9
b
298
b
5.020
b
b
8.5!
0.0237
b
b
0.0228
b
523.5
b
0.0471
b
b
0.0879
b
2037
b
0.160
b
b
b
b
b
b
b
b
a = Considered confidential by manufacturer
b = Not available
A-31
-------
TABLE A-28.
SUMMARY OF PARTICLE SIZE TESTS ON THE PRILL TOWER
SCRUBBER OUTLET DURING AGRICULTURAL GRADE UREA
PRODUCTION AT PLANT C
CO
INJ
Sampling
Location
Prill Tower
Scrubber Inlet
Prill Tower
Scrubber Inlet
Prill Tower
Scrubber Inlet
Prill Tower
Scrubber Inlet
Test Test Cut Diameter
Date Time Size Range, ym
4-2-79 1541-1556 >16.2
10.7-16.2
4.66-10.1
3.0-4.66
1.50-3.0
0.69-1.50
<0.69
4-2-79 1806-1813 >17.79
11.11-17.79
5.14-11.11
3.31-5.14
1.66-3.31
0.77-1.66
<0.77
4-3-79 0952-959 >19.88
12.42-19.88
5.75-12.42
3.70-5.75
1.87-3.70
0.87-1.87
<0.877
4-3-79 1145-1149 >15.01
9.37-15.01
4.33-9.37
2.78-4.33
1.39-2.78
0.63-1.39
<0.63
Mass in Size
Range %
16.0
2.6
4.3
4.5
15.8
20.6
36.2
5.2
0.0
3.3
4.1
18.7
50.5
18.2
11.5
1.9
2.9
3.6
4.9
44.5
30.7
4.9
3.8
3.0
3.1
30.0
26.5
28.7
-------
TABLE A-29. SUMMARY OF PARTICLE SIZE TESTS ON THE
COOLER OUTLET AT PLANT C
OJ
u>
Sampling
Location
Cooler
Outlet
Cooler
Outlet
Cooler
Outlet
Test Test Cut Diameter
Date Time Size Range, ym
4-3-79 1637-1652 >17.49
10.92-17.49
10.92-5.05
3.24-5.05
< 3.24
4-4-79 1237-1247 >16.57
10.35-16.57
4.78-10.35
3.07-4.78
1.54-3.07
0.70-1.54
< 0.70
4-4-79 1745-1755 >16.87
10.53-16.87
4.87-10.53
3.13-4.87
1.57-3.13
0.72-1.57
< 0.72
Mass in Size
Range %
98.50
0.82
0.54
0.10
0.0
99.18
0.44
0.31
0.03
0.01
0.02
0.01
99.17
0.38
0.39
0.04
0.00
0.00
0.02
-------
TABLE A-30. SUMMARY OF PARTICLE SIZE TESTS ON THE PRILL TOWER
SCRUBBER OUTLET DURING FEED GRADE UREA PRODUCTION
AT PLANT C
J»
CO
Sampling Test
Location Date
Scrubber 4-6-79
Outlet
Scrubber
Outlet 4-6-79
Scrubber 4-6-79
Outlet
Test Cut Diameter
Time Size Range, ym
1009-1015 > 16.61
10.37-16.61
4.79-10.37
3.07-4.79
1.53-3.07
0.69-1.53
< 0.69
1530-1534 >17.20
10.74-17.20
4.96-10.74
3.18-4.96
1.59-3.18
0.72-3.18
< 0.72
1931-1934 >15.99
9.98-15.99
4.60-9.98
2.95-4.60
1.47-2.95
0.66-1.47
<0.66
Mass in Size
Range %
11.9
2.4
7.0
24.8
45.6
8.3
4.5
11.5
6.7
9.2
22.6
34.2
13.2
2.6
12.7
7.6
10.6
20.0
28.6
11.2
9.3
-------
TABLE A-31.
SUMMARY OF VISIBLE EMISSIONS FROM THE
PRILL TOWER SCRUBBER DURING AGRICULTURAL
GRADE UREA PRODUCTION AT PLANT C
6 -Mi
Date Time
04-02-79 1400
\
1406
1412
1418
1424
1430
1436
1442
1448
1454
1530
1536
1542
1548
04-03-79 0820
i
0826
0832
0838
0844
0850
0856
0904
0910
0916
0945
0951
0957
1003
1009
1015
1021
1027
1033
1039
1110
1116
1122
nute
Period
1406
1412
1418
1424
1430
1436
1442
1448
1454
1500
1536
1542
1548
1554
0826
0832
0838
0844
0850
0856
0904
0910
0916
0922
0951
0957
1003
1009
1015
1021
1027
1033
1039
1045
1116
1122
1128
Average
Opacity
20
26
16
13
16
20
23
21
21
29
23.5
19
23.5
26
12
8
6.5
5.5
6.5
6.0
9
7
6
8
17
15
18
24
16.5
10.5
13.5
13.5
15.5
14.0
22
32
34
A-35
-------
TABLE A-32. SUMMARY OF VISIBLE EMISSIONS FROM THE
PRILL TOWER SCRUBBER DURING AGRICULTURAL
GRADE UREA PRODUCTION AT PLANT C
6-Minute Average
Date Time Period Opacity
04-03-79 1128 1134 29
1134 1140 24
1425 1431 5
1431 1437 5.5
1437 1443 4.5
1443 1450 7
1450 1457 4
1457 1503 6
1545 1551 5
1551 1557 3
1557 1603 6
1603 1609 8.5
A-36
-------
TABLE A-33. SUMMARY OF VISIBLE EMISSIONS FROM THE
PRILL TOWER SCRUBBER DURING AGRICULTURAL
GRADE UREA PRODUCTION AT PLANT C
6-Minute
Date Time Period
04-03-79 1609
i
1615
1621
1627
1633
04-04-79 0845
0851
^
0857
0903
0909
0915
0921
0927
0933
0939
0946
0952
0958
1004
1010
1016
1022
1028
1034
1040
1046
1052
1058
1104
1110
1116
1122
1128
1134
1140
1146
1152
1158
> 1204
1615
1621
1627
1633
1639
0851
0857
0903
0909
0915
0921
0927
0933
0939
0945
0952
0958
1004
1010
1016
1022
1028
1034
1040
1046
1052
1058
1104
1110
1116
1122
1128
1134
1140
1146
1152
1158
1204
1210
Average
Opacity
5.5
5
5
5
5.5
11.5
9.5
9
13
7.5
2
2.5
7
5
4.5
4
4
4
5
3.5
3.5
6
6.5
5.5
6.0
5
4.5
2.5
3
4.5
10
16
26
11
6
4.5
10.5
12.0
7.0
A-37
-------
TABLE A-34. SUMMARY OF VISIBLE EMISSIONS FROM THE
PRILL TOWER SCRUBBER DURING AGRICULTURAL
GRADE UREA PRODUCTION AT PLANT C
6-Minute
Date Time Period
04-04-79 1210
>
1430
1436
1442
1448
1454
1500
1506
1512
1518
1524
1600
1606
1212
1218
1224
1230
1236
1242
f 1248
1254
04-05-79 0930
0936
,
0942
0948
0954
1000
1006
1012
1018
1024
1030
1036
1042
1048
1054
1216
1436
1442
1448
1454
1500
1506
1512
1518
1524
1530
1606
1612
1218
1224
1230
1236
1242
1248
1254
1300
0936
0942
0948
0954
1000
1006
1012
1018
1024
1030
1036
1042
1048
1054
1100
Average
Opacity
8.0
16
11
13
11.5
10
10.5
10
12.5
12
1.5
0
0
0.5
2.5
0.5
1.0
2.5
1.0
0.0
1.0
6
6
6
6
6
5
4
5
6
6.5
5
7
6
4
7
A-38
-------
TABLE A-35.
SUMMARY OF VISIBLE EMISSIONS FROM THE
PRILL TOWER SCRUBBER DURING AGRICULTURAL
GRADE UREA PRODUCTION AT PLANT C
6-Minute
Date Time Period
04-05-79 1100
1106
^
1112
1118
1124
1220
1226
1232
1238
1244
1250
1256
1305
1311
1317
1323
1329
1335
1342
1348
1354
1400
1106
1112
1118
1124
1130
1226
1232
1238
1244
1250
1256
1302
1311
1317
1323
1329
1335
1342
1348
1354
1400
1406
Average
Opacity
9.5
5
6
7
15
0.5
9
4
4
14
6
13
6
4
6
8
9
8
16
30
37
34
A-39
-------
TABLE A-36. SUMMARY OF VISIBLE EMISSIONS FROM PRILL
TOWER SCRUBBER EXIT DURING FEED GRADE
UREA PRODUCTION AT PLANT C
6 -Minute
Date Time Period
04-05-79 1642
ii
1648
1654
1700
1706
1712
1718
1724
1730
1736
04-06-79 1100
•
1106
1112
1118
1124
1130
1136
1142
1148
1154
1206
1242
1248
1254
1300
1306
1312
1318
1324
1330
1622
1629
1636
1643
1650
1657
1704
1711
1718
' 1725
1648
1654
1700
1706
1712
1718
1724
1730
1736
1742
1106
1112
1118
1124
1130
1136
1142
1148
1154
1200
1212
1248
1254
1300
1306
1312
1318
1324
1330
1336
1628
1635
1642
1649
1656
1703
1710
1717
1724
1731
Average
Opacity
5
5
5
5
5
5
5
5
5
5
14
14.5
18
54
38
32
31
32
29
31
29
33
25
22
33
34
28
26
25
23
11
15
12
16
13
13.5
15
13.5
14.5
15
A-40
-------
TABLE A-37. VISIBLE EMISSIONS FROM ROTARY
DRUM COOLER SCRUBBER OUTLET AT
PLANT 'C1.
6-Minute
Date Time Period
04-02-79 1400
i
1406
1412
1418
1424
1430
1436
1530
1536
1542
1 1548
1406
1412
1418
1424
1430
1436
1442
1536
1542
1548
1554
Average
Opacity
20
25
15
20
23
17
30
25
20
25
27
A-41
-------
TABLE A-38. PRILL TOWER SCRUBBER OUTLET
FLOW RATES* AT PLANT C
Scrubber Outlet
Northeast
Southeast
Southwest
Northwest
Total Flow0
Time
During
Before3
Afterb
Average
Before
After
Average
Before
After
Average
Run 1
13070
11258
**
11258
10496
**
10496
11814
**
11814
46600
Run 2
13730
11808
12609
12208
12645
12888
12766
12076
12902
12489
51200
Run 3
13870
12609
12150
12379
12888
12798
12843
12902
12497
12699
51800
Average
13560
11892
12379
12135
12010
12843
12426
12264
12699
12481
49900
aFlow rates calculated from velocity traverses performed before the indicated runs
Flow rates calculated from velocity traverses performed after the indicated runs.
GSum of during and average flow rates, rounded to the nearest 100 DSCFM.
*Dry standard cubic feet per minute @ 68°F, 29.92 inches Hg.
**Velocity traverse data invalid due to shut down of the prill tower.
A-42
-------
TABLE A-39. PRILL TOWER SCRUBBER OUTLET
FLOW RATES* AT PLANT C
Scrubber Outlet
Northeast
Southeast
Southwest
Northwest
Total Flow0
Time
During
Before3
Afterb
Average
Before
After
Average
Before
After
Average
Run 1
370
319
**
319
247
**
297
335
**
335
1321
Run 2
389
334
357
346
358
365
362
342
366
354
1451
Run 3
393
357
344
351
365
363
364
366
354
360
1468
Average
384
337
351
344
340
364
352
348
360
354
1414
Flow rates calculated from velocity traverses performed before the indicated runs.
Flow rates calculated from velocity traverses performed after the indicated runs.
cSum of during and average flow rates.
*Dry standard cubic meters per minute @ 293 K, 29.92 inches Hg.
**Velocity traverse data invalid due to shut down of the prill tower.
A-43
-------
A. 1.5 Plant D6
Testing at Plant D was conducted to determine the urea, ammonia and
formaldehyde emissions from a fluidized bed prill tower during feed and
agricultural grade urea production. Urea and ammonia emissions were
also determined for the urea solution synthesis and concentration
process main exhaust vent. The prill tower is operated 24 hrs/day, 7
days/week producing approximately 1000 Mg/day (1100 tons/day) of urea
prills. Exhaust from the fluidized prill tower is ducted to eight
entrainment scrubbers located on the roof of the prill tower. Two
(scrubbers "A" and "C") of the eight scrubbers were tested for mass
emission in the inlet and outlet gas streams. Volumetric flow rates for
all eight scrubbers are presented to verify that conditions in the two
tested scrubbers are representative of all the scrubbers. The urea
solution synthesis and concentration process operates on a continuous
basis providing urea solution for the entire urea plant. Emissions from
this process are vented through a single stack and then exhausted to the
atmosphere. Mass emissions were determined at the outlet of this stack.
Particle size distributions were determined for the inlet gas
streams of prill tower scrubbers "A" and "C". Visible emissions were
evaluated for the individual stacks of scrubbers "A" and "C" as well as
for all eight scrubber stacks combined. Visible emissions were also
evaluated for the outlet stack of the baghouse controlling emissions
from bagging operations.
Urea emission data was determined from samples using the
p-dimethylaminobenzaldehyde colorimetric method of analysis. Ammonia
emissions were determined using the direct nesslerization method of
sample analysis. Formaldehyde emissions were determined with the
chromotropic acid analysis method.
It should be noted that preliminary velocity traverses on the
scrubber inlet duct indicated that cyclonic flow existed due to axial
flow fans. To account for this condition, the cyclonic flow angles were
measured and the sampling probe rotated in accordance with the angle
measured at each point. This is considered to be state-of-the-art
procedure for these conditions.
A-44
-------
TABLE A-40.
SUMMARY OF RESULTS OF UREA, AMMONIA, AND FORMALDEHYDE
TESTS ON GASES ENTERING AND EXITING PRILL TOWER SCRUBBER "A"
DURING AGRICULTURAL GRADE PRODUCTION AT PLANT 0. (English Units)
Test No.
General Data
Date
Isokinetic (?)
Production Rate ( Tons/day)
Ambient Temp. °F (Ave. Dry bulb)
Relative HumidityU)
Exhaust Characteristics
Flowrate inlet:
(dscf/min) outlet:
Temperature inlet:
(F°) outlet:
Moisture (% Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (in. W.G.) ,
Liquid/Gas Ratio (gal/1000 ft )
Liquor pH (Ave.)
Liquor Urea Cone, fib/gal) inlet:
outlet:
Urea Emissions
Parti cul ate Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency (%)
Ammonia Emissions
Ammonia Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet
Collection Efficiency (%)
Formaldehyde Emissions
Formaldehyde Con. inlet
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency^)
1
08-15-79
103
1044
79
69
65680
62180
113
90
2.382
3.655
2
08-16-79
102
1099
79
46
68880
60510
112
90
1.881
3.556
3
08-17-19
98
1099
81
43
70130
60530
116
89
1.844
3.677
Ave.
101
1077
80
53
68250
61073
114
90
2.036
3.633
Entrainment Scrubber
a
b
a
a
a
0.0699
0.00465
39.35
2.48
0.905
0.057
93.7
0.0283
0.105
15.93
56.01
0.366
1.287
<0
0.000204
.0000082
0.115
0.00437
.00264
.000101
96.2
a
b
a
a
a
0.0922
0.0124
54.43
6.41
. 1.188
0.139
88.2
0.0375
0.118
22.14
61.61
0.483
1.345
<0
0.000285
.0000102
0.168
0.00529
.00368
.000115
96.9
a
b
a
a
a
0.0807
0.00868
48.51
4.50
1.066
0.099
90.7
0.0380
0.0993
22.84
51.51
0.502
1.132
<0
0.000281
.0000111
0.168
0.00576
.00371
.000126
96.6
a
b
a
a
a
0.0811
0.00853
47.43
4.47
1.056
0.099
90.6
0.0347
0.108
20.29
56.37
0.452
1.255
<0
0.000257
0.0000098
0.150
0.00513
.00335
.000114
96.6
a = Considered confidential by manufacturer
b = Not available
A-45
-------
TABLE A-41.
SUMMARY OF MASS EMISSION RESULTS FOR UREA, AMMONIA, AND
FORMALDEHYDE TESTS ON GASES ENTERING AND EXITING PRILL
TOWER SCRUBBER "A" DURING AGRICULTURAL GRADE PRODUCTION
AT PLANT D. (Metric Units)
Test No.
General Data
Date
Isokinetic (?)
Production Rate
Ambient Temp (K)
(Mg/day)
(Dry Bulb)
1
08-15-79
936
299
CO
Relative Humidity u"
2
08-16-79
102
1008
299
46
08-17-79
98
984
300
43
Exhaust Characteristics
Flowsate
(dsn /min)
Temperature
(K)
Moisture (' Vol.
inlet:
outlet:
inlet:
outlet:
) inlet:
outlet:
1860
1761
318
305
2.382
3.655
1951
1714
317
305
1.831
3.556
1986
1714
320
305
1.844
3.677
Ave.
101
984
299
53
1932
1730
319
305
2.036
3.633
Control Device CJiaracteri sties
Device Type
Pressure Drop (kPa) -
Liquid/Gas Ratio (1/aT
Liquor pH (Ave.}
Liquor 'Jrea Conc.'Mg/;]
Urea Emissions
Participate Cone.
(g/dsm4)
Emission Rate
(g/hr)
Emission Factor
(a/kg)
Collection Efficiency
Ammonia Emissions
Ammonia Cone.
(g/dsmj)
Emission Rate
(g/hr)
Emission Factor
(g/kg)
Collection Efficiency
Formal denyde Emissions
Formaldehyde Con.
(g/dsmj)
Emission Rate
(g/hr)
Emi ssion Factor
(g/kg)
Collection Efficiency
i
!)
i inlet:
outlet:
inlet:
outlet:
inlet:
outlet:
inlet:
outlet:
(«)
inlet:
outlet:
inlet:
outlet:
inlet:
outlet:
("<•}
inlet:
outlet:
inlet:
outlet:
inlet:
outlet:
('-)
a
b
3
3
3
0.159
0.0106
17849
1124
0.453
0.0285
en 7
y-j . /
0.0647
0.240
7226
25400
0.183
0.643
<
0.000467
0.0000188
52.07
1.98
0.00132
0.0000503
°
a
0.211
0.0283
24690
2910
0.594
0.0699
88.2
0.0858
0.272
10040
27940
0.241
0.673
<0
0.000652
0.0000233
76.34
2 40
o'. 00 184
0.0000578
96.9
a
b
a
a
a
0.185
0.0199
22004
2043
0.533
0.0495
90.7
0.0865
0.227
10360
23365
0.251
0.566
<0
0.000643
0.0000254
76.61
2.61
0.00185
0.0000633
96.6
a
b
a
a
a
0.136
0.0195
21514
2030
0.528
0.0498
90.6
0.0794
0.246
9204
25569
0.226
0.627
<0
0.000588
0.0000221
68.18
2.33
0.00167
0.0000571
96.6
a = Considered confidential by manufacturer
b = Not available
A-46
-------
TABLE A-42.
SUMMARY OF RESULTS OF UREA, AMMONIA, AND FORMALDEHYDE
TESTS ON GASES ENTERING AND EXITING THE PRILL TOWER
SCRUBBER "C" DURING AGRICULTURAL GRADE UREA PRODUCTION
AT PLANT D. (English Units)
Test No.
General Data
Date
Isokinetic (%}
Production Rate (Ton/day)
Ambient Temp. °F (Ave. Dry bulb)
Relative Humidity (%}
Exhaust Characteristics
Flowrate inlet:
(dscf/min) outlet:
Temperature inlet:
(°F) outlet:
Moisture (% Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (in. W.G.) ,
Liquid/Gas Ratio (gal/1000 ft )
Liquor pH (Ave.)
Liquor Urea Cone, (ib/gal )inlet:
outlet:
Urea Emissions
Particulate Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/nr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency (%}
Ammonia Emissions
Ammonia Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet
Collection Efficiency (?)
Formaldehyde Emissions
Formaldehyde Con. inlet
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency (%)
i
^
08-15-79
110
1044
79
69
62360
56220
113
86
2.03
3.31
a
b
a
a
a
0.0464
0.00571
24.80
2.750
0.570
0.0632
88.9
0.0206
0.0258
11.01
12.41
0.253
0.285
<0
0.000129
0.000003
0.0693
0.00305
0.00159
0.000070
95.6
O
£
3
Ave.
08-16-79 08-17-79
114
1099
79
46
53660
56450
111
80
1.39
3.37
Impingement Scrubber
a
b
a
a
a
0.0406
0.01052
18.670
5.089
0.408
0.111
72.8
0.0237
0.0400
10.90
19.37
0.238
0.423
<0
0.000109
0.00000107
0.0500
0.00517
0.00109
0.000113
89.7
108
1092
81
43
59050
62410
115
82
1.37
4.01
a
b
a
a
a
0.0486
0.00985
24.600
5.270
0.541
0.116
78.6
0.0306
0.0345
15.49
18.45
0.340
0.405
<0
0.000139
0.0000088
0.0707
0.00471
0.00155
0.000103
93.3
Ill
1078
80
43
58357
58360
113
83
1.59
3.57
a
b
a
a
a
0.0453
0.00872
22.660
4.363
0.505
0.0972
80. 6
0.0248
0.0334
12.41
16.70
0.276
0.372
<0
0.000126
0.00000086
0.0632
0.00429
0.00141
0.000096
93.2
a = Considered confidential by manufacturer
b = Not available
A-47
-------
TABLE A-43.
SUMMARY OF RESULTS OF UREA, AMMONIA, AND FORMALDEHYDE
TESTS ON GASES ENTERING AND EXITING PRILL TOWER SCRUBBER
"C" DURING AGRICULTURAL GRADE PRODUCTION AT PLANT D.
(Metric Units)
Test No.
General Data
Date
Isokinetic (*»)
Production Rate (Mg/day)
Ambient Temp. (K)
Ambient Moisture (%)
Exhaust Characteristics
Flowsate inlet:
(dsm /min) outlet:
Temperature inlet:
(K) outlet:
Moisture (5 Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (kPa) ,
Liquid/Gas Ratio (1/m )
Liquor pH (Ave.)
Liquor Urea Cone. Mg/z. inlet:
outlet:
'Jrea Emissions
Particulate Cone. inlet:
(g/dsirT) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (5)
Ammonia Emissions
Ammonia Cone. inlet:
(g/dsm ) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (%)
Formaldehyde Emissions
Formaldehyde Con. inlet:
(g/dsm ) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (%)
a » Considered confidential by
b = Not available
1
08-15-79
110
948
299
69
1776
1592
418
403
2.029
3.314
2
3
Ave.
08-16-79 08-17-79
114
996
299
46
1519
1601
417
400
1.395
3.371
108
990
300
43
1672
1767
420
401
1.371
4.012
Ill
977
299
43
1652
1653
419
401
1.598
3.566
Impingement Scrubber
a
b
a
a
a
0.106
0.0131
11249
1247
0.285
0.0316
38.9
0.0471
0.0590
4994
S629
0.127
0.143
0.000297
0.0000144
31.42
1.38
0.000796
0.0000350
95.4
manufacturer
a
b
a
a
a
0.0929
0.0241
8469
2308
0.204
0.0556
72.8
0.0542
0.0916
4994
8786
0.119
0.212
0.000249
0.0000245
22.69
2.34
0.000547
0.0000560
38.9
a
b
a
a
a
0.111
0.0225
11159
2390
0.271
0.0579
78.6
0.0700
0.0789
7026
8369
0.170
0.203
0.000319
0.0000201
32.05
2.135
0.000777
0.0000520
92.8
a
b
a
a
a
0.104
0.0299
10280
1980
0.253
0.0486
80.6
0.0567
0.0764
5629
7575
0.138
0.186
0.000289
0.0000197
28.68
1.945
.000701
.0000180
92.8
A-48
-------
TABLE A-44. SUMMARY OF RESULTS OF UREA, AMMONIA, AND FORMALDEHYDE TESTS
ON GASES ENTERING AND EXITING PRILL TOWER SCRUBBER "A"
DURING FEED GRADE PRODUCTION AT PLANT D. (English Units)
Test "to.
General Data
Date
Isokinetic (%)
Production Rate (Tons/day)
Ambient Temp. °F (Ave. Dry bulb)
Relative Humidity ("<,)
Exhaust Characteristics
Flowrate inlet:
(dscfm) outlet:
Temperature inlet:
(F3) outlet:
Moisture (% Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (in. W.G.) ,
Liquid/Gas Ratio (gal/1000 ft )
Liauor pH (Ave.)
Liquor Urea Cone. (1 b/gal) inlet:
outlet:
Urea Emissions
Particulate Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(lo/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency (%)
Ammonia Emissions
Ammonia Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet
Collection Efficiency (*)
Formaldehyde Emissions
Formaldehyde Con. inlet
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency (%)
1
08-20-79
104
1133
87
65
51720
49750
189
106
2.731
5.472
a
b
a
a
a
0.0774
0.00519
34.31
2.21
0.727
0.0469
93.5
0.104
0.050
46.24
21.33
0.980
0.452
53.9
0.0000833
0.0000277
0.0369
0.00963
0.000782
0.000205
73.8
2
3
Ave.
08-21-79 08-22-79
104
1138
86
64
51720
42270
139
103
3.416
5.291
Entrainment Scrubber
a
b
a
a
a
0.117
0.0190
51.96
6.89
1.096
0.145
36.7
0.113
0.0591
50.18
21.41
1.059
0.452
57.3
0.000123
0.0000360
0.0547
0.0131
0.00115
0.000275
76.1
102
1102
82
66
53010
50390
182
97
2.509
5.377
a
b
a
a
a
0.106
0.0192
48.07
8.31
1.047
0.181
82.7
0.126
0.0676
57.25
29.18
1.247
0.636
49.0
0.000127
0.0000288
0.0579
0.0124
0.001263
0.000271
78.5
103
1123
85
65
52150
47470
184
102
2.885
5.380
a
b
a
a
a
0.1002
0.0142
44.79
5.78
0.957
0.124
37.1
0.115
0.0589
51.32
23.94
1.097
0.512
53.3
0.0001120
0. 000288
0.0501
0.0117
0.00107
0.000250
76.6
a = Considered confidential by manufacturer
b = Not available
A-49
-------
TABLE A-45.
SUMMARY OF RESULTS OF UREA, AMMONIA, AND FORMALDEHYDE TESTS
ON GASES ENTERING AND EXITING PRILL TOWER SCRUBBER "A"
DURING FEED GRADE UREA PRODUCTION AT PLANT D. (Metric Units)
Test No.
General Data
Date
Isokinetic ("»)
Production Rate (Hg/day)
Ambient Temo. (K)
Relative Humidity (*)
Exhaust Characteristics
FlowKate
(dsm /min)
Temperature
Moisture (5 Vol.)
inlet:
outlet:
inlet:
out! et :
inlet:
outlet:
1
08-20-79
104
1028
304
65
1464
1409
355
314
2.731
5.472
2
3
Ave.
08-21-79 08-22-79
104
10
303
64
1465
1197
360.2
313
3.416
5.291
102
1000
301
66
1501
1427
356
310
2.509
5.377
103
1123
302
65
1476
1344
357
312
2.885
5.380
Control Device Characteristics
Device Type
Pressure Oroo (kPa) ,
Liquid/Gas Ratio (1/m
Liquor pH (Ave. )
Liquor Urea Cone. Mg/
Urea Emissions
Darticulate Cone.
(g/dsm )
Emission Rate
(g/hr)
Emission Factor
(gAg)
Collection Efficiency (
Ammonia Emissions
Ammonia Cone.
(g/dsmj)
Emission Rate
(g/hr)
Emission Factor
(g/kg)
Collection Efficiency (
Formaldehyde Emissions
Formaldehyde Con.
(g/dsmj)
Emission Rate
(g/hr)
Emission Factor
(gAg)
Collection Efficiency (
Entrainment Scrubber
)
inlet:
outlet:
inlet:
outlet:
inlet:
outlet:
inlet:
outlet:
*)
inlet:
outlet:
i nl et :
outlet:
inlet:
outlet:
inlet:
outlet:
inlet:
outlet:
inlet:
outlet:
J)
a
b
a
a
a
0.177
0.0179
15566
1000
0.364
0.0235
93.4
0.238
0.114
20970
91675
0.490
0.226
53.9
0.000191
0.0000519
16.74
4.39
0.000391
0.000103
73.3
a
b
a
a
a
0.268
0.0435
23569
3126
0.5i8
0.727
86.7
0.259
0.135
22752
9712
0.529
0.226
57.3
0.000283
0.0000824
24.87
5.92
0.000577
0.000138
76.1
a
b
a
a
a
0.242
0.044Q
21805
3767
0.524
0.905
82.7
0.288
0.155
25969
13236
0.524
0.318
49.0
0.000292
0.0000659
26.26
5.53
0.000631
0.000135
78.5
a
b
a
a
a
0.229
0.0325
20317
2523
0.473
0.0618
87.1
0.263
0.135
23270
1086
0.548
0.256
53.3
0.000256
0.0000656
22.71
5.31
0.000535
0.000125
76.6
a = Considered confidential by manufacturer
b = Not .available
A-50
-------
TABLE A-46. SUMMARY OF RESULTS OF UREA, AMMONIA, AND FORMALDEHYDE
TESTS ON GASES ENTERING AND EXITING PRILL TOWER SCRUBBER "C"
DURING FEED GRADE PRODUCTION AT PLANT D. (English Units.)
Test No.
General Data
Date
Isokinetic (%)
Production Rate ( Ton/day)
Ambient Temp. °F (Ave. Dry bulb)
Relative Humidity
Exhaust Characteristics
Flowrate inlet:
(dscf/min) outlet:
Temperature inlet:
C°F) outlet:
Moisture {% Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (in. W.G. ) ,
Liquid/Gas Ratio (gal/1000 ft )
Liquor pH (Ave.
Liquor Urea Cone. Ib/gal inlet:
outlet:
Urea Emissions
Particulate Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency (%}
Ammonia Emissions
Ammonia Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet
Collection Efficiency (%)
Formaldehyde Emissions
Formaldehyde Con. inlet
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency (%)
1
08-20-79
103
1133
87
55
44150
46270
184
104
3.04
5.83
a
b
a
a
a
0.0983
0.00682
37.20
2.70
0.788
0.0573
92.7
0.129
0.0593
48.86
23.52
1.035
0.498
51.9
0.000100
0.0000241
0.0379
0.00957
0.000803
0.000202
74.7
2
08-21-79
104
1131
86
64
48880
45160
179
103
2.86
6.39
Entrainment Scrubber
a
b
a
a
a
0.0942
0.0161
39.47
6.23
0.833
0.132
84.2
0.106
0.0533
44.58
20.63
0.941
0.435
53.8
0.000125
0.0000337
0.0523
0.0130
0.00110
0.000275
75.0
3
08-22-79
104
1101
82
66
46920
50470
174
99
2.49
6.19
a
b
a
a
a
0.104
0.0168
41.75
7.27
0.910
0.159
82.6
0.108
0.0686
43.56
29.68
0.949
0.647
31.8
0.0009986
0.0000283
0.0397
0.0122
0.000864
0.000266
69.2
Ave.
104
1123
85
65
46650
47300
179
102
2.80
6.13
3
b
a
a
a
0.0987
0.0134
39.47
5.43
0.843
0.116
86.2
0.114
0.0607
45.70
24.61
0.976
0.526
46.1
0.000108
0.0000287
0.0432
0.0116
0.000924
0.000249
73.1
a = Considered confidential by manufacturer
b = Not available
A-51
-------
TABLE A-47. SUMMARY OF RESULTS OF UREA, AMMONIA, AND FORMALDEHYDE
TESTS ON GASES ENTERING AND EXITING THE PRILL TOWER
SCRUBBER "C" DURING FEED GRADE PRODUCTION AT PLANT D.
(MptHr UnitO
Test No.
General Data
Date
fs&kinetic (»)
Production Rate (Mg/day)
Ambient Temp. (K) (dry bulb)
Relative Humidity (%)
Exhaust Characteristics
Flowsate inlet:
(dsm /min) outlet:
Temperature inlet:
(K) outlet:
Moisture (% Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (kPa) •>
Liquid/Gas Ratio (1/m )
Liquor pH (Ave.)
Liquor Urea Cone. Mg/i inlet:
outlet:
Urea Emissions
Particulate Cone. inlet:
(g/dsnT) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (%)
Ammonia Emissions
Ammonia Cone. inlet:
(g/dsnT) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (J)
Formaldehyde Emissions
Formaldehyde Con. inlet:
(g/dsm ) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (%)
a = Considered confidential by
b * Not available
1
08-20-79
103
1024
304
65
1250
1310
357
313
3.04
5.03
2
08-21-79
104
1032
303
64
1384
1278
354
312
2.86
6.39
3
08-22-79
104
998
301
66
1329
1429
353
310
2.49
6.16
Ave.
104
1020
302
65
1321
1339
354
312
2.80
6.13
Impingement Scrubber
a
b
a
a
a
0.2249
0.0156
16874
1226
0.394
0.028
92.7
0.2594
0.1357
22163
10669
0.518
0.249
51.9
0.000229
0.0000551
17.201
4.341
0.000402
0.000101
74.7
manufacturer
a
b
a
a
a
0.2155
0.0368
17904
2827
0.417
0.066
34.2
0.2434
2022?'1219
9350
0.471
0.218
53.3
0.000286
0.0000771
23.719
5.917
0.000555
0.000138
75.0
a
b
a
a
a
0.237
0.038
18938
9299
0.455
0.079
32.6
0.2478
.1570
19759
13463
0.475
0.324
31.8
0.000226
0.0000648
17.985
5.543
0.000432
0.000133
69.2
a
b
a
a
a
0.2258
17904°-°307
2464
0.422
0.058
86.2
0.2615
0.1389
20730
11163
0.488
0.263
46.1
0.000247
0.0000657
19.605
5.278
0.000462
0.000125
73.1
A-52
-------
TABLE A-48.
SUMMARY OF RESULTS OF UREA AND AMMONIA TESTS ON GASES EXITING
THE SOLUTION SYNTHESIS TOWER MAIN VENT AT PLANT D. (Metric Units)
Test No.
General Data
Date
Isokinetic (%}
Production Rate (Mg/day)
Ambient Temp. (K)
Ambient Moisture (*)
Exhaust Characteristics
FlowKate inlet:
(dsm /min) outlet:
Temperature inlet:
(K) outlet:
Moisture (% Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop ( kPa) •>
liquid/Gas Ratio (1/m )
licmor pH (Ave. ]
Liquor Urea Cone. (".} (Ave.)
Urea ...Emissions0
Particulate Cone. inlet:
(g/dsm3) outlet:
Emission Rate inlet:
(9/hr) outlet:
Emission Factor inlet:
(9/kg) outlet:
Collection Efficiency (',)
Ammonia Emissions
Ammonia Cone. inlet:
(9/dsm3) outlet:
Emission Rate inlet:
(9/hr) outlet:
Emission Factor inlet:
(g/kg) outlet
Collection Efficiency (%}
Formaldehyde Emissions
Formaldehyde Con. inlet
( g/dsm3) outlet:
Emission Rate inlet:
(g/min) outlet:
Emission Factor inlet:
( g/kg) outlet:
Collection Efficiency (")
I
08-22-79
124.1
1044
b
b
b
22.26
b
355
b
73.1
b
b
b
b
b
< 0.196
b
< 262.1
b
< 0.00605
b
b
483.5
b
646496
b
14.86
b
b
b
b
b
b
b
b
2
08-22-79
132.6
1044
b
b
b
21.01
b
344
b
74.1
None
b
b
b
b
b
<0.169
b
<213.4
b
< 0.00490
b
b
500.4
b
631514
b
14.53
b
b
b
b
b
b
b
b
3
08-22-79
130.7
1087
b
b
b
20.95
b
344
b
73.9
b
b
b
b
0
<0.164
b
< 206.1
b
< 0.00455
b
b
' 501.3
b
631968
b
13.94
b
b
b
b
b
b
b
b
Ave.
129.2
1059
b
b
b
21.41
b
344
b
73.7
b
b
b
b
b
<0.176
b
.226.5
b
<0. 00515
b
b
495.1
b
636962
b
14.44
b
b
b
b
b
b
b
b
c - Concentrations were at the threshold of detection
A-53
-------
TABLE A-49. SUMMARY OF RESULTS OF UREA, AND AMMONIA TESTS
ON GASES EXITING THE SOLUTION SYNTHESIS TOWER
MAIN VENT AT PLANT D. (English Units)
Test No.
General Data
Date
Isokinetic (%)
Production Rate (Tons/day)
Ambient Temp. °F (Ave. Dry bulb)
Relative Humidity (")
Exhaust Characteristics
Flowrate inlet:
(dscfm) outlet:
Temperature inlet:
(F°) outlet:
Moisture (% Vol .) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (in. W.G.) ,
Liquid/Gas Ratio (gal/1000 ftj)
Liquor pH (Ave.)
Liquor Urea Cone. (%} inlet:
outlet:
Urea Enissionsc
Particulate Cone. inlet:
(ar/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency (",)
Arnmoma Emissions
Ammonia Cone. inlet:
(gr/dscfN outlet:
Emission Rdte inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet
Collection Efficiency (%)
Formaldehyde Emissions
Formaldehyde Con. inlet
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency
A
08-22-79
124.9
1150
b
b
b
786.4
b
180
b
73.1
b
b
b
b
b
b
< 0.0858
b
< 0.578
b
<3.0121
b
b
211.3
b
1424
b
29.73
b
b
b
b
b
b
b
b
2
08-22-79
132.6
1150
b
b
b
742.4
b
181
b
74.1
None
b
b
b
b
b
b
<0.0738
b
-------
TABLE A-50. SUMMARY OF INLET PARTICLE SIZING TEST RESULTS ON SCRUBBER 'A'
DURING AGRICULTURAL GRADE UREA PRODUCTION AT PLANT D
cn
en
Sampling Test Test
Location Date Time
A Inlet 08-14-79 1252
A Inlet 08-15-79 0955
A Inlet 08-15-79 1126
Aerodynamic
Size Range, \m
>13.3
9.17-13.3
6.22-9.17
4.24-6.22
2.72-4.24
1.36-2.72
0.84-1.36
0.57-0.84
<0-57
>14.5
10.0-14.5
6.8-10.0
4.63-6.8
2.97-4.63
1.5-2.97
0.93-1.5
0.63-0.93
< 0.63
> 1.53
10.6-15.3
7.16-10.6
4.89-7.16
3.14-4.89
1.58-3.14
0.98-1.58
0.67-0.98
< 0.67
Mass In
Size Range, %
48.5
3.4
3.2
2.3
13.8
4.0
7.3
6.6
10.9
24.9
9.2
1.8
12.8
6.4
10.7
0
20.9
13.3
17.2
3.0
11.5
7.9
17.1
3.0
21.4
14.7
4.2
Cumulative
Percent
51.5
48.1
44.9
42.6
28.8
24.8
17.5
10.9
75.1
65.9
64.1
51.3
44.9
34.2
34.2
13.3
82.8
79.8
68.3
60.4
43.3
40.3
18.9
4.2
-------
TABLE A-51.
SUMMARY OF INLET PARTICLE SIZING TEST RESULTS ON SCRUBBER
DURING AGRICULTURAL GRADE UREA PRODUCTION AT PLANT D
'C1
en
CTt
Sampling
Location
C Inlet
C Inlet
C Inlet
Test Test Aerodynamic
Date Time Size Range, ym
08-16-79 1122 >12.3
8.5-12.3
5.76-8.5
3.92-5.76
2.52-3.92
1.26-2.52
0.78-1.26
0.53-0.78
<0.53
08-16-79 1543 >12.2
8.4-12.2
5.69-8.4
3.88-5.69
2.49-3.88
1.25-2.49
0.77-1.25
0.52-0.77
< 0.52
08-17-79 1430 >13.0
8.93-13.0
6.05-8.93
4.13-6.05
2.65-4.13
1.33-2.65
0.82-1.33
0.56-0.82
< 0.56
Mass In
Size Range, %
49.0
0.0
0.4
3.0
1.2
11.5
19.5
10.8
4.6
21.2
0
1.4
2.5
3.1
22.8
22.2
21.2
5.6
66.5
3.7
0.0
0.0
1.5
0.0
15.0
6.0
7.3
Cumulative
Percent
51.0
51.0
50.6
47.6
46.4
34.9
15.1
1.6
78.8
78.8
77.4
74.9
71.8
49.0
26.8
5.6
33.5
29.8
29.8
28.3
28.3
13.3
7.3
-------
TABLE A-52 SUMMARY OF INLET PARTICLE SIZING TEST RESULTS ON SCRUBBER 'C1
DURING FEED GRADE UREA PRODUCTION AT PLANT D
Sampling
Location
C Inlet
C Inlet
C Inlet
Test Test Aerodynamic
Date Time Size Range, ytn
08-20-79 1555 >15.10
10.4-15.1
7.04-10.4
4.8-7.04
3.08-4.8
1.54-3.08
0.95-1.54
0.65-0.95
<0.65
08-21-79 1018 >13.40
9.22-13.4
6.25-9.22
4.26-6.25
2.73-4.26
1.36-2.73
0.84-1.36
0.57-0.84
<0.57
08-22-79 0935 >16.7
11.5-16.7
7.81-11.5
5.32-7.81
3.42-5.32
1.72-3.42
1.07-1.72
0.73-1.07
<0.73
Mass In
Size Range, %
71.8
0
6.0
3.5
4.9
3.4
5.0
0
5.4
36.0
5.4
11.9
8.7
5.7
7.2
7.6
7.0
10.5
78.3
0.0
0.7
9.4
0.0
6.8
0.0
0.0
4.8
Cumulative
Percent
28.2
28.2
22.2
18.7
13.8
10.4
5.4
5.4
64.0
58.6
46.7
38.0
32.3
25.1
17.5
10.5
21.7
21.7
21.0
11.6
11.6
4.8
4.8
4.8
-------
TABLE A-53. SUMMARY OF INLET PARTICLE SIZING TEST RESULTS ON SCRUBBER 'A1
DURING FEED GRADE UREA PRODUCTION AT PLANT D
cn
00
Sampling
Location
A Inlet
A Inlet
A Inlet
Test Test Aerodynamic
Date Time Size Range, ym
08-21-79 1605 >15.9
10.9-15.9
7.4-10.9
5.05-7.4
3.24-5.05
1.63-3.24
1.00-1.63
0.69-1.00
< 0.69
08-22-79 0935 >16.3
11.2-16.3
7.0-11.2
5.18-7.0
3.33-5.18
1.67-3.33
1.03-1.67
0.71-1.03
< 0.71
08-22-79 1430 >14.7
10.1-14.7
6.87-10.1
4.87-6.87
3.0-4.68
1.5-3.0
0.93-1.5
0.63-0.93
< 0.63
Mass In
Size Range, %
88.6
0.0
0.0
0.0
0.0
5.3
6.1
0.0
0.0
84.4
0.1
0.0
7.9
0.0
1.9
0.0
0.0
5.7
98.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
1.9
Cumulative
Percent
11.4
11.4
6.1
0.0
0.0
15.6
15.5
15.5
7.6
7.6
5.7
5.7
5.7
9.1
1.9
-------
TABLE A-54. VISIBLE EMISSIONS FROM SCRUBBER 'C1OUTLET DURING
AGRICULTURAL GRADE UREA PRODUCTION AT PLANT D
(CONT)
6- Mi nute
Date Time Period
08-17-79 1126
i
1132
1138
1144
1215
1221
1227
1233
1239
1249
1255
1301
1311
1317
1329
1335
1341
1347
1353
1359
1408
1414
1420
1131
1137
1143
1147
1220
1226
1232
1238
1242
1254
1300
1306
1316
1322
1334
1340
1346
1352
1358
1405
1413
1419
1424
Average
Opacity
11.5
16.3
15.4
10.3
25.6
28.3
20.6
27.9
28.3
14.0
23.1
31.0
25.3
30.7
32.0
40.1
38.2
38.0
36.6
36.7
39.1
34.0
37.9
A-59
-------
TABLE A-55. VISIBLE EMISSIONS FROM SCRUBBER'C'OUTLET DURING
AGRICULTURAL GRADE UREA PRODUCTION AT PLANT D
6-Minute
Date Time Period
08-16-79 1030
1036
1042
1048
1054
1100
1106
1112
1118
1124
1215
1221
1227
1233
1239
1245
1251
1257
1303
1309
1315
1321
1327
1333
1339
1415
1421
1427
1433
1439
1445
1451
1457
1503
1509
1515
1521
1527
1533
r 1539
1035
1041
1047
1053
1059
1105
1111
1117
1123
1129
1220
1226
1232
1238
1244
1250
1256
1302
1308
1314
1320
1326
1332
1338
1344
1420
1426
1432
1438
1444
1450
1456
1502
1508
1514
1520
1526
1532
1538
1544
Average
Opacity
25.5
17.7
16.7
20.2
17.9
19.4
22.1
20.6
19.4
18.8
26.9
27.7
26.9
26.9
29.4
28.1
24.2
26.7
24.2
35.0
32.9
33.8
31.2
23.3
23.8
30.8
21.8
28.9
30.6
34.8
28.3
37.5
29.8
21.3
34.4
35.0
34.4
30.4
31.5
34.4
A-60
-------
TABLE A-56. VISIBLE EMISSIONS FROM SCRUBBER'A'OUTLET
DURING FEED GRADE UREA PRODUCTION AT PLANT D
6-Minute
Date Time Period
08-20-79 1055
i
1101
1107
1113
1119
1125
1131
1137
1143
1149
1155
1201
1207
1213
f 1219
08-21-79 0845
,
0851
0857
0903
0909
0915
0921
0927
0933
0939
0950
0956
1002
1008
1014
1020
1026
1032
, 1038
V 1044
1100
1106
1112
1118
1124
1130
1136
1142
1148
1154
1200
1206
1212
1218
1224
0850
0856
0902
0908
0914
0920
0926
0932
0938
0944
0955
1001
1007
1013
1019
1025
1031
1037
1043
1049
Average
Opacity
19.0
16.5
15.9
17.9
12.7
13.5
10.9
7.5
5.0
3.3
5.8
9.6
7.1
8.1
13.1
22.3
26.3
29.6
24.0
22.3
20.2
-
20.8
21.7
26.5
15.4
16.4
20.0
21.5
21.7
21.9
28.1
24.6
26.7
22.7
A-61
-------
TABLE A-57. VISIBLE EMISSIONS FROM SCRUBBER 'A'OUTLET
DURING FEED GRADE UREA PRODUCTION AT PLANT D
(CONT)
6-Minute
Date Time Period
08-21-79 1112
>
1118
1124
1130
1136
1142
1148
1154
1200
1206
1212
1218
1224
1230
1236
1117
1123
1129
1135
1141
1147
1153
1159
1205
1211
1217
1223
1229
1235
1241
Average
Opacity
13.8
17.7
28.8
28.3
25.0
22.1
20.0
20.4
25.2
23.3
23.1
23.1
20.0
24.0
21.9
A-62
-------
TABLE A-58. VISIBLE EMISSIONS FROM SCRUBBER'A'OUTLET
DURING FEED GRADE UREA PRODUCTION AT PLANT D
6-Minute
Date Time Period
08-20-79 1447
1453
1459
1505
* 1511
08-22-79 0950
i
0956
1002
1008
1014
1020
1026
1032
1038
1044
1050
1056
1102
1108
1114
1120
1126
1132
1138
1144
1452
1458
1504
1510
1516
0955
1001
1007
1013
1019
1025
1031
1037
1043
1049
1055
1101
1107
1113
1119
1125
1131
1137
1143
1149
Average
Opacity
6.0
8.0
7.0
10.0
5.0
14.8
12.9
23.5
26.3
28.3
29.8
33.1
30.2
32.3
31.9
31.3
31.9
29.6
27.3
26.5
26.5
28.8
25.0
24.4
23.8
A-63
-------
TABLE A- 59.
VISIBLE EMISSIONS FROM SCRUBBER 'A' OUTLET DURING
FEED GRADE UREA PRODUCTION AT PLANT D
(CONT)
6-Minute
Date Time Period
08-23-79 0930
i
0936
0942
0948
0954
1000
1006
1012
1018
1024
1010
1016
1022
1028
1034
1040
1046
1052
1058
1104
1110
1116
1122
1128
1134
1140
1146
1152
, 1158
v 1204
0935
0943
0947
0953
0959
1005
1011
1017
1023
1029
1015
1021
1027
1033
1039
1045
1051
1057
1103
1109
1115
1121
1127
1133
1139
1145
1151
1157
1203
1209
Average
Opaci ty
14.0
13.1
15.4
9.0
9.6
18.5
13.8
11.0
12.9
19.0
24.0
24.0
21.7
27.5
25.6
29.8
30.0
28.8
29.4
26.3
24.8
25.0
24.2
25.0
25.8
25.4
24.8
26.3
23.8
15.6
A-64
-------
TABLE A-60. SUMMARY OF VISIBLE EMISSIONS FROM
BAGGING OPERATIONS AT PLANT D
Test 6-Minute
Location Date Time Period
Baghouse 12-18-79 0845
0851
0857
0903
0909
0915
0921
0927
0933
0939
12-18-79 1030
1036
1042
1048
1054
1100
1106
1112
1118
1124
12-18-79 1135
1141
1147
1153
1159
1205
1211
1217
1223
1229
Baghouse 12-18-79 1340
1346
1352
1358
1404
0850
0856
0902
0908
0914
0920
0926
0932
0938
0941
1035
1041
1047
1053
1059
1105
1111
1117
1123
1129
1140
1146
1152
1158
1204
1210
1216
1222
1228
1234
1345
1351
1357
1403
1409
Average
Opacity
0
0
0
0
0
0
0
0
0
0
0
0
0
0.2
0
1.0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.6
A-65
-------
TABLE A-61. SCRUBBER INLET FLOWRATES AT PLANT D
cr>
en
Total
Scrubber Time
A During
B Before8
Afterb
Average
C During
D Before
After
Average
E Before
After
Average
F Before
After
Average
G Before
After
Average
H Before
After
Average
lc
1
65680
59150
54980
57065
62360
57970
57250
57610
65330
60010
62670
60950
59480
60215
72230
68450
70340
56410
56210
56310
492000
FEP.IHI
2
68880
50320
56890
53605
53660
48350
54370
51360
59000
60900
59950
61890
61030
61
-------
TABLE A-62. SCRUBBER INLET FLOWRATES AT PLANT D
:c»
CTl
FERTILIZER
Scrubber Time
A During
B Before3
After
Average
C During
D Before
After
Average
E Before
After
Average
F Before
After
Average
G Before
After
Average
H Before
After
Average
Total0
1
1861
1676
1558
1617
1767
1643
1622
1632
1851
1700
1775
1727
1686
1706
2046
1940
1990
1599
1592
1596
13900
2
1950
1426
1612
1519
1520
1370
1541
1455
1672
1725
1699
1754
1730
174T
1983
1988
1985
1656
1704
1682
13500
3
1987
1268
1437
1353
1673
1455
1467
1461
1736
1661
1693
1760
1638
1699
1962
1837
1899
1659
1568
T611
13400
Average
1934
1457
1536
1496
1654
1489
1544
1516
1749
1696
1723
1747
1684
1716
1997
1922
1959
1639
1622
1630
13600
\
1465
981
969
"975
1251
1393
1295
1343
5000
FEED
2
1466
989
1045
1018
1385
1305
1272
1288
5200
3
1502
1110
1127
me
1329
1296
1312
T304
5200
Ave ra g_e
1478
1027
1047
1037"
1321
1331
1293
T3T2
5200
at:i t 1 t- A r i •» t t tut ti-j-kj
Flowrates calculated from velocity traverses performed after the indicated runs at scrubbers A and C.
cSum of averages, rounded to nearest 100 DSCH.
*Dry standard cubic meters per minute 0 293°K, 29.92 inch Hg.
-------
A.1.6 Plant E7
Testing was conducted at Plant E to determine the urea and ammonia
emissions in gases entering and exiting a nonfluidized bed prill tower
scrubber. The testing was done during agricultural grade urea production.
(Plant E produces agricultural grade only). The prill tower operates at
a production rate of approximately 272 Mg/day (300 tons/day) on a 24
hr/day, 7 day/week basis. The prill tower exhaust is ducted through a
downcommer and then passed into a wetted fiber filter scrubber before
being exhausted to the atmosphere. A preconditioning liquor spray is
located in the downcommer prior to the entrance of the scrubber. Testing
on April 15, 16, and 17 on the gases exiting the scrubber as well as the
simultaneous inlet and outlet testing were performed with the
preconditioning spray partially on. Testing on April 18, 21, and 22 on
the gases exiting the scrubber was performed with the preconditioning
spray fully on.
Particle size distributions were determined for the prill tower
exhaust entering the scrubber with the preconditioning sprays partially
off. Visible emissions were determined for the gases exiting the
prill tower scrubber stack and rotary drum cooler scrubber stack.
Samples were analyzed for their urea content by the
p-dimethylaminobenzaldehyde colorimetric (with preliminary distillation)
analysis method. Samples were analyzed for their ammonia content by the
specific ion electrode analysis method.
Because of the relatively short (320 min.) sampling time and low
emissions in the first exiting test on April 15, 1980, the amount of
urea collected was below the direction limit for the analytic method.
In order to detect the urea in this sample, a larger aliquot was
concentrated during the preliminary ammonia removal step. For the
subsequent test runs, the sampling time was extended to 400 minutes.
A-68
-------
TABLE A-63.
SUMMARY OF RESULTS OF UREA AND AMMONIA TESTS
ON GASES ENTERING AND EXITING THE PRILL TOWER
SCRUBBER AT PLANT E (English Units)
Test No.
General Data
Date
Isokinetic (*.)
Production Rate ('Tons/day)
Ambient Temp.(°F)
Relative Humidity (")
Exhaust Characteristics
Flowrate inlet:
(dscfra) outlet:
temperature inlet:
(T) outlet:
Moisture (5 Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (in W.G.) ,
Liquid/Gas Ratio, (gal/ 1000 ftj)
Liquor pH (Ave.)°
Liquor Urea Conc.(%} (Ave. )°
Urea Emissions
Parti cul ate Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency (?)
Ammonia Emissions
Ammonia Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
pb/hr) outlet:
tmission Factor inlet:
(Ifa/ton) outlet:
Collection Efficiency (%)
Formaldehyde Emissions
Formaldehyde Con. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) outlet:
Collection Efficiency (5)
1
04-15-30
101
293
62
42
68010
72910
105
99
0.58
4.31
14.7
b
8.7
11.4
0.0721
b
42.03
b
3.5
b
b
0.0178
0.103
10.39
64.51
0.87
5.29
<0
a
a
a
a
a
a
a
2
3
Ave.
04-16-80 04-17-30
102
290
67
48
76100
84200
101
97
1.46
4.98
102
290
64
55
709170 •
86590
98
96
1.17
5.06
Wet Scrubber
12.1 12.2
b
8.8
10.8
0.0466
0.000839
30.42
0.606
2.4
0.050
97.9
0.0167
0.112
10.38
80.77
0.87
6.68
<0
a
a
a
a
a
a
a
0
8.8
12.8
0.0954
0.00128
54.75
0.534
5.4
0.0782
98.6
0.0151
0.0896
10. 24
66.49
0.86
5.50
<0
a
a
a
a
a
a
a
102
291
64
48
74430
80903
101
97
1.07
4.74
13.0
b
8.8
11.7
0.0716
0.00119
45 . 71
0.570
3.8
0.0641
98.3
0.0169
0.102
10.75
70.59
0.87
5.82
<0
a
a
a
a
a
a
a
a 3 not available
b = This average is for the scrubber liquor sumo.
A-69
-------
TABLE A-64.
SUMMARY OF RESULTS OF UREA AND AMMONIA TESTS
ON GASES ENTERING AND EXITING THE PRILL TOWER
SCRUBBER AT PLANT E (Metric Units)
Test No.
General Data
Date
Isokinetlc (?)
Production Rate (Mg/day)
Ambient Temp (K) (Dry Bulb)
Relative Humidity (%}
Exhaust Characteristics
Flowcate inlet:
(dsm /min) outlet:
Temperature inlet:
(K) outlet:
Moisture (% Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (kPa) ,
Liquid/Gas Ratio (1/nr)
Liquor pH (Ave.) b
Liquor Urea Cone. (%) (Ave.)
Urea Emissions
Participate Cone. inlet:
(g/dsmj) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (%)
Ammonia Emissions
Ammonia Cone. inlet:
(g/dsm ) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (%}
Formaldehyde Emissions
Formaldehyde Con. inlet:
(g/dsnT) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (%)
1
04-15-80
101
266
290
42
1926
2065
313
310
0.58
4.81
2
04-16-80
102
264
287
48
2155
2385
312
309
1.46
4.98
3
04-17-80
102
264
289
55
2242
2452
311
309
1.17
5.06
Ave.
102
265
289
48
2108
2304
312
309
1.07
4.95
Wet Scrubber
3.7
b
8.7
11.4
0.165
b
19081
b
1.75
b
b
0.0410
0.236
4717
29290
0.435
2.6
<0
a
a
a
a
a
a
a
3.0
b
8.8
10.8
0.107
0.00192
13810
0.275
1.20
0.0250
97.9
0.0382
0.256
4939
36640
4.435
3.3
<0
a
a
a
a
a
a
a
3.1
b
8.8
12.8
0.218
0.00292
29396
0.429
2.70
0.0390
98.6
0.0345
0.205
4649
30160
0.430
2.7
<0
a
a
a
a
a
a
a
3.3
b
8.8
11.7
0.154
0.00247
21603
0.352
7.95
0.0320
98.3
0.0387
0.233
4881
32030
0.435
2.9
<0
a
a
a
a
a
a
a
a » Not available
b = This ave. is for the scrubber liquor sump.
A-70
-------
TABLE A-65. SUMMARY OF RESULTS OF UREA AND AMMONIA TESTS
ON GASES EXITING THE PRILL TOWER SCRUBBER AT
PLANT E. (English Units)
Test No.
General Data
Date
Isokinetic (*)
Production Rate (Tons/day)
Ambient Temp. (?F)
Relative Humidity (%)
Exhaust Characteristics
Flow rate inlet:
tlscfm} outlet:
Temperature inlet:
{ °F) outlet:
Moisture (2 Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop ( in W.G.) ,
Liquid/Gas Ratio. ( gal/ 1000 ftj)
Liquor pH (Ave.)c c
Liquor Urea Conc.(%) (Ave.)
Urea Emissions
Parti cul ate Cone. inlet:
(gr/dscf} outlet:
Emission Rate inlet:
(ib/hr) outlet:
Emission Factor inlet:
(lo/ton) outlet:
Collection Efficiency (%)
Ammonia Emissions
Ammonis Cone. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
Ob/hr) outlet:
Emission Factor inlet:
Ob/ton) outlet:
Collection Efficiency (*)
Formaldehyde Emissions
Formaldehyde Con. inlet:
(gr/dscf) outlet:
Emission Rate inlet:
(Ib/hr) outlet:
Emission Factor inlet:
(Ib/ton) ~ outlet:
Collection Efficiency (%)
1
04-18-80
101
295
b
b
b
82610
b
98
b
5.16
12.0
b
8.62
13.6
b
0.000732
b
0.518
b
0.0421
b
b
0.124
b
87.61
b
7.72
b
b
b
b
b
b
b
b
2
04-21-80
98
286
b
b
b
85400
b
95
b
4.
Wet
12.
b
8.
14.
b
0.
b
0.
b
0.
b
b
0.
b
72.
b
6.
b
b
b
b
b
b
b
b
3
04-22-80
99
300
b
b
b
84210
b
97
b
.32 4.74
Scrubber
,0 12.0
b
64 8. 77
1 13.8
b
000730 0.000775
b
534 0.560
b
0450 0.0448
b
b
0984 0.0839
b
03 60.52
b
05 4.84
b
b
b
b
b
b
b
b
Ave.
99
293
b
b
b
84070
b
97
b
4.74
12.0
b
8.68
13.3
b
0.000745
b
0.537
b
0.0440
b
b
0.102
b
73.56
b
6.00
b
b
b
b
b
5
b
b
b = not available
c = This average is for scrubber liquor sump.
A-71
-------
TABLE A-66. SUMMARY OF RESULTS OF UREA AND AMMONIA TESTS
ON GASES EXITING THE PRILL TOWER SCRUBBER
AT PLANT E. (Metric Units)
Test No.
General Data
Date
Isokinetic I",)
Production Rate (Mg/day)
Ambient Temp. (K)
Relative Humidity (%}
Exhaust Characteristics
Flowwte inlet:
(dsn /min) outlet:
Temperature inlet:
(K) outlet:
Moisture (% Vol.) inlet:
outlet:
Control Device Characteristics
Device Type
Pressure Drop (kPa) -,
Liquid/Gas Ratio, (1/m )
Liquor pH (Ave.)C
Liquor Urea Conc.(") (Ave.)1"
Jrea Emissions
Participate Cone. inlet:
(g/dsm ) outlet:
Emission Rate inlet:
(g/hr) outlet:
Enission Factor inlet:
'g/kg) outlet:
Collection Efficiency (?)
Ammonia Emissions
Ammonia Cone. inlet:
f g/dsm ) outlet:
Emission Rate inlet:
(g/hr) outlet:
Enission Factor inlet:
(g/kg) outlet:
Collection Efficiency ("»)
Formaldehyde Emissions
Formaldehyde Con. inlet:
(g/dsm ) outlet:
Emission Rate inlet:
(g/hr) outlet:
Emission Factor inlet:
(g/kg) outlet:
Collection Efficiency (*)
1
04-18-30
101
268
b
b
b
2340
b
310
b
5.16
3.0
b
3.62
13.6
b
0.00167
b
234.9
b
0.0209
b
b
0.283
b
3974
b
3.5
b
b
b
b
b
b
b
b
2
04-21-80
98
260
b
b
b
2419
b
308
b
4.
Wet
3.
b
8.
14.
b
0.
b
242.
b
0.
b
b
0.
b
3267
b
3.
b
b
b
b
b
b
b
b
3
04-22-80
99
272
b
b
b
2385
b
309
b
32 4.74
Scrubber
0 3.0
b
64 8.77
1 13.3
b
00167 0.00177
b
3 253.8
b
0224 0.0225
b
b
225 0.192
b
2745
b
0 2.4
b
b
b
b
b
b
b
b
Ave
99
266
b
b
b
2291
b
309
b
4.
3.
b
8.
13.
b
0.
b
243.
b
0.
b
b
0.
b
3329
b
3.
b
b
b
b
b
b
b
b
.
74
0
68
3
00171
5
0225
234
0
b * Not available
c » This average is for the scrubber liquor sump.
A-72
-------
TABLE A-67. SUMMARY OF RESULTS OF THE DOWNCOMER
PARTICLE SIZE TESTS AT PLANT E
^-j
CO
Test Test
Date Time
04-16-80 1513-1520
04-17-80 0844-0904
04-17-80 1357-1411
Aerodynamic Size
Range, (ym)
> 3.8
1.71-2.81
1.08-1.71
0.58-1.08
< 0.58
> 6.4
2.22-3.64
1.41-2.22
0.76-1.41
< 0.76
>14.0
5.15-13.00
3.15-5.15
2.01-3.15
1.10-2.01
< 1.10
Mass In
Size Range (%)
80.0
5.8
8.8
4.1
1.3
67.1
2.3
8.2
10.2
12.2
66.8
0.8
2.3
5.6
9.2
15.3
Cumulative
(Percent)
20.0
14.2
5.4
1.3
32.9
30.6
22.4
12.2
33.2
32.4
30.1
24.5
15.3
-------
TABLE A-68. SUMMARY OF OPACITY READINGS ON THE
SCRUBBER OUTLET AT PLANT E
6-Minute
Date Time Period
04-15-80 1543
1549
y
1555
1601
1607
1613
1619
1625
1631
1637
1645
1651
1657
1703
1709
1715
1721
1727
1733
1739
04-16-80 0925
0931
>
0937
0943
0949
0955
1001
1007
1013
1019
1034
1040
1046
1052
1058
1104
f
1548
1554
1600
1606
1612
1618
1624
1630
1636
1642
1650
1656
1702
1708
1714
1720
1726
1732
1738
1744
0930
0936
0942
0948
0954
1000
1006
1012
1018
1024
1039
1045
1051
1057
1103
1109
Average
Opacity
0
0.4
0.2
0.4
0
0
0.2
0.2
0.2
0.2
0
0
0
0
0
0.2
0.2
0
0.2
0
9.2
11.7
11.9
6.3
5.6
5.0
4.4
2.5
3.8
4.0
3.5
3.3
7.1
8.5
6.5
7.5
A-74
-------
TABLE A-69. SUMMARY OF OPACITY READINGS ON THE
SCRUBBER OUTLET AT PLANT E
6-Minute
Date Time Period
04-16-80 1110
>
1116
1122
1128
1158
1204
1210
1216
1248
1254
1300
1306
1312
1318
1324
04-17-80 1104
1110
1116
1122
1128
1134
1140
1146
1152
1158
1205
1211
1217
1253
1259
1305
1311
1317
1323
1329
1115
1121
1127
1133
1203
1209
1215
1220
1253
1259
1305
1311
1317
1323
1325
1109
1115
1121
1127
1133
1139
1145
1151
1157
1203
1210
1216
1223
1258
1304
1310
1316
1322
1328
1334
Average
Opacity
7.7
4.4
7.9
9.2
3.8
3.5
6.0
5.3
4.0
5.0
4.6
7.7
6.7
8.8
6.4
9.6
9.2
8.1
6.9
7.5
6.3
6.3
4.6
7.9
8.8
7.1
7.1
9.6
11.5
9.0
6'. 5
9.2
11.7
13.8
15.5
A-75
-------
TABLE A-70.
SUMMARY OF OPACITY READINGS ON THE
SCRUBBER OUTLET AT PLANT E
6-Minute
Date Time Period
04-17-80 1340
1346
i
1352
1358
1404
1410
1416
1422
1428
1434
1541
1547
1553
1559
1605
1610
1617
1623
' 1629
04-18-80 0900
0906
>
0912
0918
0924
0930
0936
0942
0948
0954
1010
1016
1022
1028
1034
1040
1046
1052
1058
r 1104
1345
1351
1357
1403
1409
1415
1421
1427
1433
1439
1546
1552
1558
1604
1609
1613
1622
1628
1631
0905
0911
0917
0923
0929
0935
0941
0947
0953
0959
1015
1021
1027
1033
1039
1045
1051
1057
1103
1109
Average
Opacity
14.4
11.0
19.6
32.9
10.0
10.8
11.0
11.9
12.9
11.7
16.3
17.1
27.1
20.8
13.8
5.4
9.8
6.5
5.8
—
—
--
--
--
--
--
12.8
11.5
14.0
13.1
10.8
17.9
12.7
11.9
12.3
19.4
11.3
11.0
12.9
A-76
-------
TABLE A-71.
SUMMARY OF OPACITY READINGS ON THE
SCRUBBER OUTLET AT PLANT E
6-Mi
Date Time
04-18-80 1115
)
1121
1127
1133
1139
1145
1151
1157
1203
1209
1
04-21-80 1005
>
1011
1017
1023
1029
1035
1041
1047
1053
1059
1120
1126
1132
1138
1144
1150
1156
1202
1208
1214
04-22-80 0845
^
0851
0857
0903
0909
0915
0921
0927
nute
Period
1120
1126
1132
1138
1144
1150
1156
1202
1208
1214
1010
1016
1022
1028
1034
1040
1046
1052
1058
1104
1125
1131
1137
1143
1149
1155
1201
1207
1213
1219
0850
0856
0902
0908
0914
0920
0926
0932
Average
Opacity
10.8
9.0
9.2
12.1
11.7
9.6
10.0
13.8
13.3
14.8
13.5
12.5
17.9
16.5
12.3
13.8
8.8
13.8
12.7
9.6
11.5
9.1
15.4
10.0
8.8
14.0
9.8
12.5
12.1
14.6
23.7
26.9
21.9
19.0
23.3
13.5
14.2
12.1
A-77
-------
TABLE A-72. SUMMARY OF OPACITY READINGS ON THE
SCRUBBER OUTLET AT PLANT E
6-Minute
Date Time Period
04-22-80 0933
0939
1
1010
1016
1022
1028
1034
1040
1046
1052
1058
1104
1110
1128
1134
1140
1146
1152
1158
1204
1210
1216
1222
1300
1306
1312
1318
1324
1330
1426
1432
' 1438
1444
04-23-80 0920
1 0926
0932
0938
0944
1015
1021
1027
1033
1039
1045
1051
1057
1103
1109
1115
1133
1139
1145
1151
1157
1203
1209
1215
1221
1227
1305
1311
1317
1323
1329
1335
1431
1437
1443
1447
0925
0931
0937
Average
Opacity
13.3
14.2
12.3
13.1
5.8
10.0
15.0
12.3
10.0
8.0
4.2
5.7
7.6
9.5
11.1
9.8
5.0
6.1
5.2
6.1
2.5
5.3
10.0
5.0
13.1
9.0
6.5
4.4
4.8
6.1
5.0
7.7
12.0
13.1
19.0
18.1
A-78
-------
TABLE A-73.
SUMMARY OF OPACITY READINGS ON THE
SCRUBBER OUTLET AT PLANT E
6 -Minute
Date Time Period
04-23-80 0938
0944
>
0955
1001
1007
1013
1019
1036
1042
1048
1054
1100
1110
1116
1122
f 1128
1134
0943
0949
1000
1006
1012
1018
1024
1041
1047
1053
1059
1105
1115
1121
1127
1133
1139
Average
Opacity
26.0
27.9
31.3
29.8
18.8
16.9
19.0
14.8
11.3
11.7
11.0
15.8
23.1
23.2
24.4
18.8
12.3
A-79
-------
TABLE A-74. VISIBLE EMISSIONS FROM ROTARY DRUM COOLER
SCRUBBER OUTLET AT PLANT E.
Test Date Time Avg. Opacity for 6 min,
10-16-80 900 - 905 3.1
10-16-80 906 - 911 2.5
10-16-80 912 - 917 3.8
10-16-80 918 - 923 4.0
10-16-80 924 - 929 3.5
10-16-80 930 - 935 4.4
10-16-80 936 - 941 3.1
10-16-80 942 - 947 2.9
10-16-80 948 - 953 1.5
10-16-80 954 - 959 1.0
A-80
-------
A. 2 REFERENCES
1. Urea Manufacture: Agrico Chemical Co panv Emission Test Report
EMB Report 79-NHF-13a, September 1980. "
2. Urea Manufacture: Agrico Chemical Company Emission Test Report
EMB Report 78-NHF-4, April 1979.
3. Urea Manufacture: CF Industries Emission Test Report, EMB Report
78-NHF-8, May 1979.
4. Urea Manufacture: Union Oil of California Emission Test Report,
EMB Report 78-NHF-7, October 1979.
5. Urea Manufacture: Union Oil of California Emission Test Report
EMB Report 80-NHF-15, September 1980.
6. Urea Manufacture: W.R. Grace & Company Emission Test Report, EMB
Report 78-NHF-3, December 1979.
7. Urea Manufacture: Reichhold Chemicals Emission Test Report, EMB
Report 80-NHF-14, August 1980.
A-81
-------
APPENDIX B
UREA EMISSION MEASUREMENT
AND CONTINUOUS MONITORING
B.I Emission Measurement Methods
B.I.I Background
The standard method for determining particulate emissions form
stationary sources is EPA Mehtod 5, whereby a particulate sample is
extracted isokinetically from a source and is collected on a heated
filter. The particulate mass is then determined gravimetrically.
Initial evaluations by EPA and others of the applicability of Method 5
for urea sampling indicated that the standard procedures of Method 5
would not be practical.1 Factors that affected the sampling and analysis
procedures of Method 5 included the following:
• High water-solubility of urea (greater than 1 gram per ml water);
• Relatively high vapor pressure and volatility of urea melts at 133°
C and will begin to decompose at lower temperatures).
As a result of these factors, major modifications to Method 5 were
adopted. A summary of these modifications and the reasons for each are
presented in the remainder of Section B.I.
B.I.2 Brief Summary of Urea Method Development
Industry and EPA assessments in 1977 of the applicability of Method
5 for urea sampling and analysis determined that the following modifications
were necessary:
• Use of water-filled impingers as the primary urea collection devices.
• Use of a urea-specific analytical procedure for measurement of urea
collected in the impinger water.
Emission tests to develop new source performance standards (NSPS)
for the urea industry were begun in October 1978, using sampling and
analytical procedures incorporating these Method 5 modifications. The
sampling train for the first program included five impingers in series,
B-l
-------
with water in the first impinger (for urea capture), sulfuric acid in
the second and third impingers (for ammonia capture), the fourth impinger
empty, and the fifth impinger containing silica gel. A heated filter
(filter temperature not exceeding 71°C was positioned in front of the
first impinger. The filter catch was weighed and then dissolved in the
water impinger contents which was then analyzed for urea with the p-
dimethylaminobenzaldehyde (PDAB) procedure. Water and acid impinger
contents were analyzed for ammonia by direct nesslerization.
The urea sampling and analytical procedures were further modified
during the seven EPA emission tests conducted from October 1978 through
April 1980. Each of these tests provided information that helped to
clarify and simplify the procedures. The modifications were the result
of pertinent questions raised by industry as well as investigations
performed by EPA and its contractors. The in-train filter was eliminated,
and urea analyses were performed by the Kjeldahl procedure, the Kjeldahl
and PDAB procedures together, and eventually just the PDAB procedure.
Urea, ammonia, and formaldehyde emissions were measured during
these testing programs at urea solution formation process units, solid
urea formation process units (prill towers and granulators), and solid
urea coolers. The results of these programs demonstrated the applicability
of the recommended Method 28 for urea sampling and analysis. The modifications
to Method 5 that are incorporated into the recommended method are as
follows:
Sampling
• Five impingers in series with the following sequence: impingers
1, 2 and 3 each contain 100 ml water, impinger 4 contains 100
ml IN sulfuric acid, and impinger 5 contains silica gel.
• Elimination of an in-train filter.
Analysis
• Sample Recovery: Combine the probe washes with contents of
impingers 1, 2 and 3. Measure the volume of the contents of
impinger 4 for moisture gain and then discard. Weigh the
contents of impinger 5 for moisture gain.
B-2
-------
• Sample Analysis: Dilute a 100 ml aliquot of the combined
probe wash and water impinger contents to 500 ml, adjust the
pH to greater than 9.5, then boil this solution down to about
75 ml. Dilute up to 100 ml, add PDAB cooler reagent to a 10
ml aliquot and measure color intensity in a spectrophotometer.
The PDAB procedure was determined to be the simplest and most
direct procedure for urea analysis. The interfering effects of ammonia
on the PDAB analysis procedure are eliminated through the boiling step,
whereby ammonia is removed from the sample. Ammonia and formaldehyde
sampling and analytical procedures are not included in the recommended
method. The acid impinger is used to protect sampling train equipment
from ammonia corrosion.
B.I.3 Detailed Development of Urea Sampling and Analysis Method
B.I.3.1. Initial Method Development
Urea sampling modifications to Method 5 were needed because of the
following source conditions:
• Urea has a substantial vapor pressure even as a solid, and if a
sampling is heated in a probe or on a filter for extended periods
of time it would tend to decompose.14'15
• The high water-solubility of urea implied that a water medium in
the sampling train would be an efficient urea particualte collector.
• Ammonia and formaldehyde are additional pollutants emitted from
urea manufacturing processes, and both were considered secondary
pollutants in the NSPS work plan. Ammonia cannot be efficiently
collected in the Method 5 sampling train water impingers, so additional
impingers containing acid would be required. Formaldehyde can be
efficiently collected in water.
Factors that would affect urea analysis procedures were the following:
• With water impingers as the primary particulate collector, the
sampling train water would have to be analyzed for urea.
• The volatility of urea would preclude rapid heating of the samples
B-3
-------
to dryness in order to do a gravimetric analysis. At the same
time, evaporating large quantities of water without heating would
be inefficient and tedious.
• The insoluble fraction of particulate emitted form urea sources was
considered to be insignificant.
Through literature surveys and discussions with industry sources, EPA
determined that only three procedures were routinely used for urea
analysis. These were the urease procedure, the Kjeldahl procedure, and
the PDAB procedure. With the urease procedure, urea is hydrolyzed to
ammonium carbonate, the sample solution is acidified and then back-
titrated with standard base. This procedure is applicable only for high
concentration urea analyses, such as for scrubber liquors. The Kjeldahl
procedure can be applied for urea measurement in one of two ways:
direct or indirect. With the direct procedure, ammonia is boiled from a
sample and the urea in the residue is converted to ammonia; this converted
ammonia is distilled off and the distillate is analyzed for ammonia by
either nesslerization or titration. With the indirect procedure, one
sample portion is distilled and the distillate is then analyzed for
ammonia. The urea in a second sample portion is converted to ammonia
and this solution is distilled. This distillate is then analyzed for
ammonia and the ammonia measured in the first portion is subtracted from
the ammonia measured in the second portion. For both the indirect and
the direct Kjeldahl procedures, urea is calculated by applying a stoichiometric
conversion factor to the final ammonia measurement.
With the PDAB procedure, color reagent is added to a sample aliquot
and color intensity is then related to urea concentration. This analytical
procedure was chosen for the initial urea sampling and analysis method
because it is simple and easy to use in the field and it will measure
low levels of urea (less than 10 mg/1). The interfering affect of
o
ammonia on the PDAB procedure was of concern, and for this reason the
Kjeldahl procedure was evaluated with the PDAB procedure in the early
stages of the EPA emission test program.
B-4
-------
The urea sampling and analytical procedures recommended for the EPA
program included the following specific Method 5 modifications:
Sampling
•Use of five impingers in series: impinger 1 contains 100 ml deionized,
distilled water; impingers 2 and 3 each contain 100 ml IN sulfuric
acid; impinger 4 is empty, and impinger 5 contains silica gel. The
heated filter was retained in its position just before the first
impinger.
• The probe and filter temperatures should not exceed 160°F.
Sample Recovery
Place filter in jar 1; the distilled water wash of the probe,
nozzle and front half of the filter holder in jar 2; the silica gel
in jar 3; and contents of impinger 1 and its distilled water wash
in jar 4; the contents of impingers 2, 3, and 4 and their acid wash
in jar 5.
Sample Analysis
Jar 1 - Desccate and weigh the filter, then place in 50 ml water in
an ultrasonic bath. Combine this solution with jar 4.
Jar 2 - Measure the volume, then evaporate the liquid and weigh the
residue. Redissolve in water and combine with jar 4.
Jar 3 - Weigh for moisture gain.
Jar 4 - Analyze for urea with the PDAB procedure.
Jar 5 - Analyze for ammonia by direct nesslen'zation.
Two acid impingers were employed to ensure capture of ammonia and
to protect downstream sampling train equipment form the corrosive effects
•3
of ammonia. Direct nessleration0 is a widely used ammonia colorimetric
analytical procedure.
B.I.3.2 First EPA Emission Tests
At the first urea plant tested in October 1978, urea, ammonia, and
formaldehyde were measured at a rotary drum granulator scrubber inlet
and outlet and at a solution tower vent.4 Formaldehyde sampling and
analysis results are discussed in Section B.I.6. Sampling at the solution
B-5
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tower was performed with a train modified to handle the high moisture
and ammonia levels in the off-gas vent: eight impingers were used (four
with water, one empty, two with ION sulfuric acid, and one with silica
gel) along with an in-stack orifice.
Urea analyses were performed by the contractor using the PDAB
procedure within 15 days of sample collection, and by plant personnel
using the Kjeldahl indirect procedure within 24 hours of sample collection.
The analyses by plant personnel were performed in order to address
questions of sample stability raised by industry. The results of this
testing program show the PDAB urea results exceeding the Kjeldahl results
by about 8% at the granulator scrubber inlet (where ammonia concentrations
were much less than the urea concentrations). At the outlet however,
(where ammonia concentrations greatly exceeded the urea concentrations),
the PDAS results were 48% lower than the Kjeldahl results. Urea audit
sample analyses of urea standards containing varying concentrations of
ammonia did indicate approximately a 2% positive interference with a
17.6 ammonia-to-urea molar ratio. The positive interference increased
as the molar ratio increased. These results generally corroborated
earlier evaluations of the interfering effect of ammonia on the PDAB
p
method. Other analyses of urea standards performed periodically over
10 days showed no urea degradation with time. The large difference
between the PDAB and Kjeldahl analyses of the outlet samples is considered
to be due to analytical errors and limitations in the Kjeldahl analysis.
The PDAB procedure is more accurate than the Kjeldahl procedures at low
urea concentrations.
The sampling train water impingers were purged with ambient air for
15-20 minutes at the end of each test run to flush most ammonia into the
acid impingers where it would not interfere with the PDAB urea analyses.
A significant amount of ammonia still remained in the water impingers,
so this flushing technique was discontinued after these tests.
The results of this emission testing program showed that the amount
of urea collected in the acid impingers was insignificant, indicating
that nearly all sampled urea was caught in the water impinger and on the
B-6
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filter. Solution tower vent emissions were shown to consist primarily
of water vapor and ammonia and very little urea.
B.I.3.3 Method Modifications
As a result of these first tests, EPA further modified the sampling
and analytical procedures. An additional water impinger was added to
insure the complete capture of urea. The filter was deleted to simplify
the method (since any filter catch had been merely added to the water
impinger contents) and to eliminate the possibility of an accidently
overheated filter decomposing any collected area. The urea analytical
procedure was changed to the Kjeldahl direct procedure (with preliminary
distillation to remove ammonia). This was due to the high levels of
ammonia collected in the controlled granulator emissions and the susceptibility
of the PDAB procedure to ammonia interference. These modifications are
summarized as follows:
Sampling
• Six impingers in series: impingers 1 and 2 each contain 100 ml
water, impingers 3 and 4 each contain 100 ml IN sulfuric acid,
impinger 5 is empty, and impinger 6 contains silica gel.
• Elimination of the in-train filter.
Analysis
• Sample Recovery: Combine the probe and nozzle washes with the
contents of impingers 1 and 2. Combine the contents of impingers
3, 4, and 5 in a separate container. Weigh the silica gel for
moisture gain.
• Sample Analysis: Add buffering agents to the samples and distill
into a boric acid solution. Analyze this distillate solution for
ammonia by nesslerization. Add digestion reagents to the residue,
converting organic nitrogen (urea) to ammonia. Distill and analyze
this distillate solution for ammonia by nesslerization:, calculate
urea concentration stoichiometrically from the indicated ammonia
concentration.
B-7
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Several of these modifications to the urea sampling and analytical
procedures were applied during the next three emission tests in December
1978, January 1979, and April 1979.
B.I.3.4 Second EPA Emission Tests
The December 1978 tests were performed at the same facility as the
October 1978 tests, and consisted of emission measurements at the outlet
of one granulator scrubber. A major purpose of this test was to
provide field samples for time stability evaluations and to attempt to
establish the validity of the Kjeldahl indirect procedure analyses
performed during the previous test program. The December 1978 samples
were analyzed on-site for urea by the contractor using the Kjeldahl
direct procedure and by plant personnel using the Kjeldahl indirect
procedure.
The sampling train used in the December 1978 tests contained only 5
impingers (impingers 1, 2, and 3 contained water, impinger 4 was empty,
and impinger 5 contained silica gel) because the primary concern was
with urea; ammonia capture was of secondary importance. The combined
contents of impingers 1 through 4 were filtered for insoluble particulate,
and the filtrate was then analyzed for urea by the Kjeldahl procedures
as described above and for formaldehyde as described in Section B.I.6.
Ammonia analyses were also performed, by direct nesslerization and by
nesslerization with preliminary distillation. The insoluble particulate
catch averaged about 1.4% of the total particulate catch.
The Kjeldahl indirect analyses performed by plant personnel on the
scrubber outlet samples yielded results that averaged 30% higher than
the kjeldahl direct analysis results. Audit sample analyses by the
contractor using the Kjeldahl direct procedure (ending with a final
ammonia analysis by nesslerization) agreed within 6% of the actual urea
sample weights. These same audit samples were analyzed by plant personnel
using the Kjeldahl direct method ending with titration, and the results
averaged 93% higher than the actual sample weights. EPA concluded that
the Kjeldahl analyses performed by plant personnel during this testing
program and the previous program (October 1978) were unreliable.
B-8
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A complication with the use of the Kjeldahl procedures for urea
analyses is the need to correct indicated urea and ammonia concentrations
in order to account for the conversion of some urea to ammonia during
the preliminary distillation step.10 The standard correction factor is:
7% of the sample urea content is converted to ammonia during distillation.
There is evidence, however, that this correction factor is not constant,
but may vary with absolute urea concentration or with the ratio of urea
to ammonia concentrations in the sample.6'7 Use of the 7% factor
produces difficulties with samples containing relatively high urea
concentrations compared to ammonia concentrations; for example, with
uncontrolled emission samples or scrubber liquor samples, negative
corrected ammonia concentrations can be calculated. The granulator
scrubber outlet samples from the December 1978 program contained relatively
small amounts or urea, and no problems were encountered.
The granulator outlet samples from the December 1978 emission
testing program and specially prepared urea laboratory samples were
periodically analyzed over a 20-day period subsequent to the completion
of the program. The purpose of these time analyses was to determine if
the urea content of samples deteriorated over time. These analyses were
performed with the Kjeldahl direct procedure, and the results showed no
detectable change in urea content of the samples.9 EPA concluded that
there would be no problems with the stability of urea samples analyzed
up to 20 days after the sample collection.
B.I.3.5 Third and Fourth EPA Emission Tests
The January 1979 and April 1979 emission tests were performed with
the modified urea sampling and analytical procedures (6 impingers,
Kjeldahl direct analysis procedure). Emissions at a granulator scrubber
inlet and outlet and at a solution tower vent were measured during the
January 1979 tests. Ammonia analyses were performed by both the
direct nesslerization and the nesslerization with preliminary distillation
procedures. The granulator inlet samples contained relatively large
urea concentrations and, as a result of the urea to ammonia conversion,
the two ammonia analytical procedures differed greatly in indicated
B-9
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ammonia concentrations. No significant difference occurred with the
outlet samples. Formaldehyde analyses were also performed, as described
in Section B.I.6. The urea content of the acid impingers was less than
0.2% of the total urea caught at the granulator scrubber inlet and near
the threshold of detection at the outlet.
During the April 1979 tests, prill tower uncontrolled and controlled
Q
emission samples were analyzed by both the Kjeldahl and the PDAB procedures.
Procedural difficulties during the analyses, however, prevented any
reliable evaluation of the results.
B.I.3.6 Method Modification
At this time, the urea sampling and analytical procedures were
further modified, based on the results of these three recent emission
tests. Ammonia and formaldehyde sampling was discontinued because no
immediate need for emission standards for these pollutants was foreseen.
The PDAB procedure was retained for the urea analyses because of its
advantages (its simplicity and the fact that it measures urea directly)
and because of the disadvantages of the Kjeldahl procedure. Its complexity,
the number of reagents and amount of apparatus needed, as well as the
problems associated with the urea to ammonia conversion during distillation,
were the major reasons for deleting the Kjeldahl procedure.
The problem of ammonia interference in the PDAB procedure was
Q
investigated in more detail at this time. The interfering effects of
2
ammonia as initially described in the literature and as discussed above
were corroborated. Investigations with prepared laboratory standard
solutions showed a slight (less than 2%) positive interference for
approximately a 20:1 ammonia to urea molar ratio. Higher molar ratios
increased the interference. To eliminate the ammonia interference
during the field sample analyses, a preliminary distillation step was
included in the PDAB procedure, whereby ammonia is boiled off prior to
the actual analysis.
The modifications to the urea sampling and analytical procedures
made at this time are summarized as follows:
B-10
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Sampling
• Five impingers in series: impingers 1 and 2 each contain 100 ml
water, impinger 3 contains 100 ml IN sulfuric acid, impinger 4 is
empty, and impinger 5 contains silica gel.
Analysis
• Sample Recovery: Combine the nozzle and probe washes with the
contents of impingers 1 and 2. Mesaure the voluje of the contents
of impingers 3 and 4, then discard. Weigh the silica gel for
moisture gain.
• Sample Analysis: Dilute a 100 ml aliquot to 500 ml, adjust the pH
to greater than 9.5, then boil sample down to about 75 ml. Dilute
up to 100 ml, and add PDAB color reagent to a 10 ml aliquot and
measure color intensity in a spectrophotometer.
The one acid impinger was retained to protect the downstream sampling
train equipment from the corrosive effects of ammonia. During the final
three emissions tests, ammonia sampling and analysis was continued in
order to accumulate background data for potential future use. An dditional
acid impinger was therefore added to the train immediately preceding the
empty impinger, making a total of six impingers in the train.
B.I.3.7 Fifth, Sixth, and Seventh EPA Emission Tests
The fifth emission tests were performed in August 1979 on uncontrolled
and controlled prill tower emissions and on emissions from a solution
tower vent. The sampling and analytical procedures described immediately
above were used (6 impingers, PDAB procedure). The water impinger
contents were filtered prior to urea, ammonia, and formaldehyde analyses
to retain any insoluble particulate. Water and acid impingers were
analyzed for urea by PDAB procedure with preliminary distillation, and
for ammonia by both direct nesslerization and specific ion electrode.
The two ammonia analysis results agreed with each other within 10%. The
urea content of the acid impingers was negligible (at the threshold of
detection) for both controlled and uncontrolled prill tower emissions
samples.
B-1T
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During the urea analysis of the first series of the first series of
water and acid impinger samples, the analyst determined that sulfuric
acid was acting as a negative interference to the PDAB urea analysis.
In order to compensate for this interference, urea standards used to
establish absorbance vs. concentration calibration curves were prepared
911
with the same acid concentrations as the samples being analyzed. *
The effect of the preliminary distillation step (boiling ammonia
off) was investigated during this field program as part of the audit
sample analyses. The investigation results indicate that the extent of
urea loss during the distillation step is 12 to 14 percent. This urea
loss can be compensated for as long as both samples and standards are
handled in the same way (both undergo distillation).
Prior to the sixth emission tests, the absolute threshold of detection
for the PDAB urea analysis procedure was investigated with laboratory
Q
standard solutions and was determined to be 5 to 7 mg/1. The sixth set
of emission tests were performed in April 1980 on uncontrolled and
12
controlled prill tower emissions. It was known beforehand that the
controlled prill tower emissions would be very low, so an unusually long
sampling time was planned (320 minutes). Even with this extended sampling
time the first samples yielded urea concentrations near the threshold of
detection. Consequently, sampling times were further extended (400
minutes) to collect more urea, and the PDAB analysis procedure was
modified in order to assess the low concentrations. Instead of diluting
a 100 ml sample aliquot to 500 ml and then boiling down to 75 ml, larger
sample aliquots (500 to 700 ml) were taken and boiled down without
dilution. In this way, 5 to 7 times as much urea was concentrated in
the same volume and the sensitivity of the analysis method was effectively
Q 1 O
increased. '
The urea content of the acid impingers was about 2.5% (less than 10
mg) of the total urea catch at the scrubber inlet (uncontro"led emissions)
and at or below the threshold of detection at the scrubber outlet (controlled
emissions). Ammonia analyses were performed with the direct nesslerization
procedure and with the specific ion electrode (SIE) procedure. The
results of both analysis procedures agreed within 6 percent.
B-12
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The stability of urea field samples was further documented during
this emission testing program. The urea analyses of the scrubber outlet
samples were performed in the field within 24 hours of sample collection
and at the contractor's laboratory within 16 days of sample collection.
No significant difference existed between the results.
The last EPA emission tests were conducted in April 1980 on the
outlet of a prill tower scrubber and on the inlet of a prill cooler
1 o
scrubber. One purpose of this program was to document the urea
collection efficiency of the sampling train (six impingers: 1 and 2
water, 3 and 4 acid, 5 empty, and 6 silica gel). The nozzle and probe
wash, the contents of impinger 1, the contents of impinger 1, the contents
of impinger 2, and the combined contents of impingers 3, 4, and 5 were
analyzed separately for urea (PDAB procedure with ammonia removal) and
ammonia (SIE procedure). The analysis results showed that 70% of the
urea is caught by the probe and first water impinger, and the remaining
30% is caught by the second water impinger. The urea content of the
acid impingers was below the threshold of detection. The ammonia analysis
results showed that about half the ammonia is caught in the water impingers
Q 1 O
and half in the acid impingers. »
During several of the EPA emission tests, acid impinger samples
turned turbid when the PDAB color reagent was added, due perhaps to the
amount of sodium hydroxide added to adjust the sample pH. In all cases,
however, the turbidity was removed with the addition of a small amount
(1 or 2 ml) of concentrated hydrochloric acid.11'12'13
B.I.3.8 Recommended Method
The recommended urea sampling and analysis method (Method 28)
incorporates an additional modification to the sampling train, based on
the results from all the EPA emission tests and the urea method development
investigations. These final method modifications are summarized as
follows:
B-13
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Sampling
• Five impingers in series with the following sequence: impingers 1,
2, and 3 each contain 100 ml water, impinger 4 contains 100 ml IN
sulfuric acid, and impinger 5 contains silica gel.
Analysis
• Combine the probe washes and the contents of the three water impingers
and analyze for urea by the PDAB procedure with ammonia removal.
• Measure the volume of the contents of impinger 4 for water gain and
discard. Weigh the contents of impinger 5 for water gain.
The third water impinger is included to ensure capture of all sampled
urea and to eliminate the need to make up separate urea standards for
acid impinger sample analysis. (As discussed above, the acid content of
samples and standards should be the same.) The acid impinger is included
to protect the sampling train equipment from ammonia.
In situations where ammonia sampling is desired, an additional
impinger (containing 100 ml IN sulfuric acid) can be added to the train
directly preceding the silica gel impinger. In this case, the combined
contents of the first three impingers are analyzed for urea (by PDAB)
and ammonia (by SIE or direct nesslerization), and the combined contents
of impingers 4 and 5 are analyzed for ammonia only.
The results of the urea EPA emission tests have demonstrated the
utility and economy of the recommended method. The urea (and ammonia)
analytical procedures require a minimum amount of equipment and field
laboratory space. All analyses can be performed on-site and immediately
after each individual test run. The ability to perform sampling analyses
quickly in the field allows for rapid evaluation of emission values and
sampling technique.
B.I.4 Potential Problems with the Recommended Method
Two difficulties may be encountered with the use of the recommended
Method 28:
• Decomposition of urea in the probe at elevated temperatures;
• Incomparability of Method 28 data and Method 5 data.
B-14
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By maintaining probe temperatures at about 6°C above stack temperature,
sample decomposition and moisture condensation in the probe can be
avoided. Most emission control devices operate at or near saturation
and with outlet gas stream temperatures less than 49°C. Solid urea
melts at about 133°C but will decompose at temperatures below the
melting point. Routine analyses of the urea product by industry that
show the presence of biuret indicate that decomposition does take place.
Industry procedures for drying solid urea specify heating at 70°C
overnight. Therefore, to ensure the integrity of a sample, a reasonable
upper limit on probe temperature is approximately 71°C.
A source subject to particulate emission regulations normally
undergoes periodic compliance tests. Method 28 would be used specifically
to verify the particulate emission compliance of a new urea source. The
results of a Method 28 urea compliance test could not be directly compared
to the results of a Method 5 urea compliance test because of the factors
discussed in Section B.I.3. In addition, the relationship between
Method 5 urea collection and Method 28 urea collection is not established.
This relationship would depend on the type of emission source, the
operating conditions of that source, and the amount of urea particulate
caught. Small amounts of particulate (for example, less than 10 mg) can
be analyzed accurately by Method 28, but are difficult to assess with a
Method 5 gravimetric analysis.
B.I.5 Relationship of Data Gathered Under EPA Tests to Data Gathered
with the Recommended Test Method
The majority of the EPA emission tests were conducted using the
same sampling and analytical procedures as contained in the recommended
Method 28. The first tests and the last three tests (all utilizing the
PDAB analysis method) differed from each other in that the first tests
did not include an ammonia removal step and did utilize an in-train
filter. Since the ammonia-to-urea molar ratio in the samples of the
first tests did not exceed 20, the urea analysis results of these samples
would not be in error by more than approximately 2 percent due to ammonia
interference. The in-train filter catch was redissolved in the water
B-15
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impinger contents and so was included in the urea analysis results. The
second, third, and fourth emission tests utilized the Kjeldahl urea
analytical procedure. The data gathered during these three tests may be
in error by approximately 7 percent due to the urea-to-ammonia conversion
that occurs during distillation. Urea audit sample analyses performed
during these tests showed that the Kjeldahl procedure produced results
within the required accuracy (+10 percent). The results of the fourth
tests are not considered valid, as noted in Section B.I.3.
B.I.6 Formaldehyde Sampling and Analysis During the EPA Tests
A formaldehyde-based additive is often used in urea production
processes to coat solid urea prills. Formaldehyde emissions were sampled
and analyzed through the August 1979 EPA emission tests. Formaldehyde
emissions were very low, and subsequently formaldehyde sampling was
discontinued.
During the first EPA test, formaldehyde at the granulator scrubber
inlet and outlet was sampled with a sampling train separate from the
c
train used for the urea and ammonia sampling. The procedure in the EPA
document "Tentative Method for Isokinetic Determination of Pollutant
Levels in the Effluent of Formaldehyde Manufacturing Facilities" was
followed, which utilized the impinger sequence of Method 5 but without a
filter. Formaldehyde analysis was performed with the chromotropic acid
procedure. The analytical results showed that formaldehyde emissions at
the granulator scrubber inlet and outlet were about 0.045 and 0.023 kg
per hour, respectively.
During the second EPA test in December 1978, the urea sampling
train impinger contents were analyzed for formaldehyde with the chromotropic
acid procedure. Formaldehyde emissions from this granulator outlet
averaged less than 0.36 kg per hour.
The same formaldehyde sampling and analysis procedures that were
followed in the second EPA test were followed in the third and fifth
tests (an aliquot from the urea sampling train impingers were analyzed).
During the third test, formaldehyde emissions in the granulator scrubber
B-16
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inlet and outlet were approximately 0.09 and 0.045 kg per hour, respectively.7
During the fifth test, prill tower scrubber inlet and outlet formaldehyde
emissions averaged less than 0.045 and 0.0045 kg per hour, respectively.11
B-17
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TABLE 1
MANTIME BREAKDOWN FOR COMPLIANCE TEST
Task
Site Visit
Field Work
Preparation and Cleanup
Lab Analysis
Data Reduction
Report Preparation
Management
Number
of People
1
2
1
1
1
1
1
Number
of Days
1
1
2
2
0.5
2
0.5
Total
Man-Days
1
2
2
2
0.5
2
0.5
Total 10
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REFERENCES
1. Grove, J. D., "Prill Tower Sampling Approahces: Urea and Ammonia
Nitrate Processes". Entropy Environmentalists, Inc., Prepared for
U.S. EPA under Contract 68-01-4148, Task No. 32. October 1977.
2. Watt, G. W. and J. D. Chrisp, "Spectrophotometric Method for Determination
of Urea", Analytical Chemistry. Volume 26, 1974, pp. 452-453.
3. Standard Methods of Water and Wastewater Analysis. APHA, AWWA,
WPCF, 14th Edition, 1975, p. 412.
4. EPA Report 78-NHF-4, "Emission Test Report, Agrico Chemical Company,
Blytheville, Arkansas". Prepared by TRC-Environmental Consultants,
Inc. under EPA Contract 68-02-2820, Work Assignment 6.
5. Standard Methods of Water and Wastewater Analysis. APHA, AWWA,
WPFC, 14th Edition, 1975, p. 437
6. EPA Report 79-NHF-13a, "Emission Test Report, Agrico Chemical
Company, Blytheville, Arkansas". Prepared by TRC-Environmental
Consultants, Inc., under EPA Contract 68-02-2820, Work Assignment
I I •
7. EPA Report 78-NHF-8, "Emission Test Report, CF Industries Inc.,
Donaldsonville, Louisiana". Prepared by TRC-Environmental Consultants,
Inc., under EPA Contract 68-02-2820, Work Assignment 10.
8. EPA Report 78-NHF-7, "Emission Test Report, Union Oil Company,
Brea, California". Prepared by Engineering-Science under EPA
Contract 68-02-2915, Work Assignment 26.
9. EPA Report 79-NHF-13, "Development of Analytical Procedures for the
Determination of Urea from Urea Manufacturing Facilities". Prepared
by TRC-Environmental Consultants, Inc., under EPA Contract 68-02-
2820, Work Assignment 11.
10. Standard Methods of Water and Wastewater Analysis. APHA, AWWA,
WPCF, 14th Edition, 1975, p. 408.
11. EPA Report 79-NHF-3, "Emission Test Report, W. R. Grace and Co.,
Memphis, Tennessee". Prepared by TRC-Environmental Consultants,
Inc., under EPA Contract 68-02-2820, Work Assignment 9.
12. EPA Report 80-NHF-14, "Emission Test Report Reichhold Chemicals,
Inc., St. Helens, Oregon". Prepared by TRC-Environmental Consultants,
Inc., under EPA Contract 68-02-2820, Work Assignment 19.
B-19
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13. EPA Report 80-NHF-15, "Emission Test Report, Union Oil Company,
Brea, California". Prepared by TRC-Environmental Consultants,
Inc., under EPA Contract 68-02-2820, Work Assignment 20.
14. The Condensed Chemical Dictionary, 9th Edition, Van Nostrand
Company, 1977 p. 905.
15. Cramer, J. H., "Urea Prill Tower Control - Meeting 20% Opacity".
Presented at the Fertilizer Institute Environmental Symposium, New
Orleans, Louisiana, April 1980.
B-20
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TECHNICAL REPORT DATA
(f 'lease read Instructions on the reverse before completing}
EPA-450/3-81-001
3. RECIPIENT'S ACCESSION NO.
Technical Document for the Urea Industry
S. REPORT DATE
Janaury 1981
6. PERFORMING ORGANIZATION COO6
3H
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