United States
Environmental Protection
Agency
Industrial Environmental Research EPA-600/7-79-141
Laboratory August 1979
Cincinnati OH 45268
Research and Development
Environmental
Considerations of
Selected Energy-
Conserving
Manufacturing
Process Options
Volume XVI.
Sulfur Oxides
Summary Report
Interagency
Energy/Environment
R&D Program Report
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6 Scientific and Technical Assessment Reports (STAR)
7 Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from the
effort funded under the 17-agency Federal Energy/Environment Research and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects; assessments of, and development of, control technologies for energy
systems; and integrated assessments of a wide range of energy-related environ-
mental issues.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
-------
EPA-600/7-79-141
August 1979
ENVIRONMENTAL CONSIDERATIONS OF SELECTED
ENERGY-CONSERVING MANUFACTURING PROCESS OPTIONS
Volume XVI. Sulfur Oxides Summary Report
by
Arthur D. Little, Inc.
Cambridge, Massachusetts 02140
Contract No. 68-03-2198
Project Officer
Herbert S. Skovronek
Power Tec-hnology and Conservation Branch
Industrial Environmental Research Laboratory
Cincinnati, Ohio 45268
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
For sale by the Superintendent of Documents, U.S. Government
Printing Office, Washington, D.C. 20402
-------
DISCLAIMER
This report has been reviewed by the Industrial Environmental Research
Laboratory-Cincinnati, U.S. Environmental Protection Agency, and approved for
publication. Approval does not signify that the contents necessarily reflect
the views and policies of the U.S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
ii
-------
FOREWORD
When energy and material resources are extracted, processed, con-
verted, and used, the related pollutional impacts on our environment,
and even on our health, often require that new and increasingly more
efficient pollution control methods be used. The Industrial Environ-
mental Research Laboratory - Cincinnati (lERL-Ci) assists in developing
and demonstrating new and improved methodologies that will meet these
needs both efficiently and economically.
This report summarizes information on sulfur oxides from a study
of 13 energy-intensive industries. If implemented over the coming 10
to 15 years, these processes and practices could result in more effec-
tive utilization of energy resources. The study was carried out to
assess the potential environmental/energy impacts of such changes and
the adequacy of existing control technology in order to identify po-
tential conflicts with environmental regulations and to alert the
Agency to areas where its activities and policies could influence the
future choice of alternatives.
The results will be used by the EPA's Office of Research and De-
velopment to define those areas where existing pollution control tech-
nology suffices, where current and anticipated programs adequately ad-
dress the areas identified by the contractor, and where selected pro-
gram reorientation seems necessary.
Specific data will also be of considerable value to individual
researchers as industry background and in decision-making concerning
project selection and direction.
The Power Technology and Conservation Branch of the Energy Sys-
tems-Environmental Control Division should be contacted for additional
information on the program.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
iii
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ABSTRACT
Under EPA Contract No. 68-03-2198, Arthur D. Little, Inc.
undertook a study of the "Environmental Considerations of
Selected Energy-Conserving Manufacturing Process Options."
Some 80 industrial process options were examined in 13 industrial
sectors. Results were published in 15 volumes, including a
summary, industry prioritization report, and 13 industry
oriented reports (EPA-600/7-76-034 a through o).
This present report summarizes the information regarding
particulates in the 13 industry reports. Four parallel reports
treat sulfur oxides, nitrogen oxides, solid residues, and toxics/
organics. All of these pollutant-oriented reports are intended
to be closely used with the original 15 reports.
iv
-------
CONTENTS
Foreword ill
Abstract iv
Tables vi
English-Metric (SI) Conversion Factors viii
1. INTRODUCTION 1
BACKGROUND AND PURPOSE 1
APPROACH 2
2. FINDINGS AND R&D OVERVIEW 5
FINDINGS 5
R&D AREAS 21
3. PROCESSES AND SO EMISSIONS 25
BASES OF CALCULATIONS 25
SOX CONTROL METHODS 26
PETROLEUM REFINING 28
CEMENT 37
OLEFINS 40
AMMONIA 46
ALUMINA AND ALUMINUM 50
PULP AND PAPER 58
GLASS 62
COPPER 69
CHLOR-ALKALI 76
IRON AND STEEL 81
PHOSPHORUS/PHOSPHORIC ACID 85
FERTILIZERS 89
TEXTILES 95
REFERENCES 99
-------
TABLES
Number
1 Projected U.S. Production in Industries Studies 3
2 Summary of Estimated Annual SOX Emissions 6
3 SOX Nationwide Emission Estimates (1974) 15
4 Estimated Increase in Controlled SOX Emissions 1989-1974
Assuming Industry Expands Using Process Types Indicated 17
5 Estimated Range in Controlled SOX Emissions in 1989 for
New Processes Likely to be Implemented 19
6 Estimated SO Emission Factors - Petroleum Refining Industry 29
7 Estimated SO Emissions - Petroleum Refining Industry 32
8 Estimated SO Emissions - Cement Industry 41
9 Estimated SO Emissions - Cement Production 42
x
10 Sulfur Distribution and Estimated SO Emission Factors -
Olefin Industry 44
11 Estimated SO Emissions - Olefins Industry 47
12 Estimated SO Emissions - Ammonia Industry 49
X
13 Estimated SO Emission Factors - Alumina and Aluminum
Industry 55
14 Estimated SO Emissions - Alumina and Aluminum Industry 56
15 Uncontrolled Emissions of TRS and Proposed Emission Standards
for New Kraft Pulp Mills 59
16 Estimated SO Emission Factors - Pulp and Paper Industry 63
17 Estimated SO Emissions - Pulp and Paper Industry 64
X
18 Estimated SO Emission Factors - Glass Industry 70
x
VI
-------
TABLES (cont.)
Number
19 Estimated SO Emissions - Glass Industry 71
20 Estimated SO Emission Factors - Primary Copper Industry 77
X
21 Estimated SO Emissions - Copper Smelting 78
X
22 Estimated SO Emissions - Chlor-Alkali Industry 82
23 Estimated SO Emissions - Iron and Steel Industry 86
24 Estimated SO Emissions - Phosphorus/Phosphoric Acid
Production 90
25 Estimated SO Emissions - Fertilizer Industry 93
26 Estimated SO Emissions - Textile Industry 98
vii
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ENGLISH-METRIC (SI) CONVERSION FACTORS
To Convert From
To
Metre2
Pascal
Metre
Joule
Pascal-second
Degree Celsius
Degree Kelvin
Metre
3
Metre /sec
Metre3
2
Metre
Metre/sec
2
Metre /sec
3
Metre
Watt
Watt
Watt
Metre
Joule
Metre3
Metre
Metre
Metre
Pascal-second
Newton
Kilogram
Kilogram
Kilogram
Kilogram
Kilogram
Kilogram
Multiply By
4,046
101,325
0.1589
1,055
0.001
t° = (t° -32)/1.8
0.3048
0.0004719
0.02831
0.09290
0.3048
0.00002580
0.003785
745.7
746.0
735.5
0.02540
3.60 x 106
1.000 x 10"3
1.000 x 10~6
0.00002540
1,609
0.1000
4.448
0.4536
0.02916
1,016
1,000
907.1
1,000
Acre
Atmosphere (normal)
Barrel (42 gal)
British Thermal Unit
Centipoise
Degree Fahrenheit
Degree Rankine
Foot
3
Foot /minute
Foot
2
Foot
Foot/sec
Foot2/hr
Gallon (U.S. liquid)
Horsepower (550 ft-lbf/sec)
Horsepower (electric)
Horsepower (metric)
Inch
Kilowatt-hour
Litre
Micron
Mil
Mile (U.S. statute)
Poise
Pound force (avdp)
Pound mass (avdp)
Ton (Assay)
Ton (long)
Ton (metric)
Ton (short)
Tonne
Source: American National Standards Institute, "Standard Metric Practice
Guide," March 15, 1973, (ANS72101-1973) (ASTM Designation E380-72)
viii
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SECTION 1
INTRODUCTION
BACKGROUND AND PURPOSE
During 1975 and the first half of 1976, under EPA Contract No.
68-03-2198, Arthur D. Little, Inc., undertook a study of the "Environ-
mental Considerations of Selected Energy-Conserving Manufacturing Pro-
cess Options" in 13 energy-intensive industry sectors for the U.S. En-
vironmental Protection Agency (EPA). The results of these studies were
published in the following reports:
• Volume I — Industry Summary Report (EPA-600/7-76-034a)
• Volume II — Industry Priority Report (EPA-600/7-76-034b)
• Volume III — Iron and Steel Industry (EPA-600/7-76-034c)
• Volume IV — Petroleum Refining Industry (EPA-600/7-76-034d)
• Volume V — Pulp and Paper Industry (EPA-600/7-76-034e)
• Volume VI — Olefins Industry (EPA-600/7-76-034f)
• Volume VII — Ammonia Industry (EPA-600/7-76-034g)
• Volume VIII — Alumina/Aluminum Industry (EPA-600/7-76-043h)
• Volume IX — Textiles Industry (EPA-600/7-76-034i)
• Volume X — Cement Industry (EPA-600/7-76-034j)
• Volume XI — Glass Industry (EPA-600/7-76-034k)
• Volume XII — Chlor-Alkali Industry (EPA-600/7-76-0341)
• Volume XIII — Phosphorus/Phosphoric Acid Industry
(EPA-600/7-76-034m)
• Volume XIV — Copper Industry (EPA-600/7-76-034n)
• Volume XV — Fertilizer Industry (EPA-600/7-76-034o)
-------
In the course of this study, some 80 industrial process options
were examined, focusing on:
• Identification of any major sources and amounts of pollutants
(air, water and solid) expected from the processes,
• Development of estimated capital and operating costs for both
production and pollution control aspects of the processes,
• Estimation of the types and amounts of energy used in both
production and pollution control for the processes,
• Assessment of the economic viability and likelihood of im-
plementation of those alternative process options being
studied,
• Identification of areas where EPA's activities and policies
could influence the future choice of alternatives, and
• Identification of research and development areas in both
process and pollution control technology.
Because of the industry orientation of the study (encompassing
15 volumes and some 1,700 pages), it was felt that pollutant-specific
information across all the 13 sectors studied should be summarized.
Five such pollutants were identified to be of particular interest:
• Nitrogen oxide (NO ) emissions,
X
• Sulfur oxide (SO ) emissions,
X
• Fine particulate emissions,
• Solid residues, and
• Organic, and/or toxic pollutants.
A summary pollutant report in each of these areas has been pre-
pared. Although we did attempt some estimates and extrapolations on
pollutants where information was readily available, in general, we did
not attempt to go beyond the contents of the 15 original reports.
APPROACH
These summary pollutant reports are intended to be used closely
with the original 15 reports. Generally, information, such as detailed
descriptions of the processes, has not been duplicated in these pol-
lutant reports. Sections of the previous 15 reports in which this in-
formation can be found have been extensively referenced by volume num-
ber and page number (e.g., Volume VII, page 20, refers to page 20 of
the Ammonia Industry report).
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TABLE 1. PROJECTED U.S. PRODUCTION IN INDUSTRIES STUDIED
Commodity
Alumina
Aluminum
Ammonia
Cement
Chlorine
Coke
Copper
Fertilizers (HNO )
Glass (flat)
Iron
Olefins (ethylene)
Petroleum
Pulp (kraft)
Pulp (newsprint)
Phosphoric Acid
(detergent grade)
Phosphoric Acid
(wet acid grade)
Steel
Textiles (knit)
Textiles (woven)
Total U.S.
production
in 1974
(106 tons*)
7.7
5.0
9.2
79.0
11.0
62.0
1.6
8.2
29.0
100.0
13.0
740.0**
16.0
3.9
1.4
9.0
133.0
0.32
2.1
Projected
rate
of growth
(%/yr)
6.0
6.0
6.0
2.0
5.0
2.5
3.5
4.0
2.5
2.5
8.0
1.5
5.0
2.5
2.5
2.5
2.5
2.2
2.2
Increase in
Total annual
projected production
production in 1989 over
in 1989 that of 1974
(106 tons) (106 tons)
18.5
12.0
22.0
106.3
22.9
89.8
2.7
14.8
42.0
144.8
41.2
925.0***
33.3
5.6
2.03
13.0
193.0
0.44
2.91
10.75
7.0
12.8
27.3
11.9
27.8
1.1
6.6
13.0
44.8
28.2
185.0****
17.3
1.7
0.63
4.0
60.0
0.12
0.81
*A11 tons referred to in these reports are net tons, unless otherwise
indicated.
**Approximate equivalent of 30 quads (1 quad is equal to 10 Btu).
***Approximate equivalent of 37.5 quads.
****Approximate equivalent of 7.5 quads.
-------
In Section 2 of this report (Findings and R&D Overview), summary
information on generic, cross-industry problems that emerge and suggest-
ions for research and development work in the areas of both pollution
control technology and process technology are presented. In Section 3
of this report, availability and applicability of SO pollution control
technology is presented, and SO emissions and controls reported in our
previous study are summarized. Unless otherwise noted, the SO in gas
streams is largely S0? with only 1 to 3 percent of the sulfur values
reported as SO . All emissions are estimated unless specifically ref-
erenced, since we believe that actual data do not exist for many of the
processes described, which are frequently still under development.
To give the reader a sense of the size of the industries for which
the pollution problems covered in these summary pollutant reports are
considered, Table 1 lists these industries, their total production in
1974 (the baseline year for the study), and their projected incremental
production in 1989 — 15 years hence.
-------
SECTION 2
FINDINGS AND R&D OVERVIEW
FINDINGS
Eight of the 13 industries addressed in the original study have
process-related SO emissions that are affected by potential process
changes and are reviewed in this report. These industries are petro-
leum refining, cement, olefins, ammonia, alumina/aluminum, pulp and
paper, glass, and copper. In addition, process changes in the re-
maining five industries show changes for steam and/or electric energy
requirements and thus SO emissions are affected at the generating
source. Table 2-1 listsXthe estimated SO emissions from processes,
steam, and power boilers for both the base case and alternative pro-
cesses and process alternatives for these industries.
The SO emission shown in the table include both process and power
boiler emissions. Emissions from the power boiler were generally not
considered in the original study, but are included here because emis-
sions from the base case and alternative processes are compared in
this report. The power boilers include on-site power boilers for steam
and electricity generation. The emissions represent controlled emis-
sions from the process as further described in Section 3 where it is
seen that the emission factors vary from less than 1 Ib of SO /ton of
product to more than 1400 Ib of SO /ton of product as found in the
copper industry. The emission factors from the conventional smelter
in the copper industry are high because of both high sulfur content in
the ore and an absence of economical control technology for reverbera-
tory furnace off-gas. The emissions for the aluminum industry range
from an estimated 138 Ib of SO /ton to 200 Ib of SO /ton. These high
emissions result mostly from power boilers, because the production of
aluminum requires large quantities of electricity which we assume will
be generated largely from coal to meet incremental aluminum production
requirements.
As shown in Table 2, the petroleum industry was responsible for
the greatest volume of emissions of sulfur compounds from the base case
process in the year 1974, followed by copper, aluminum, kraft, pulp,
cement, and so forth. Table 2 also shows estimated incremental SO
emissions (1989 - 1974) based on the increase in annual production from
1974 to 1989. Incremental emissions are shown from both the base case
and alternative processes, assuming dedication of 100% of the incre-
mental production rather than a fraction to each process (base case and
alternative). Thus incremental SO emissions (1989 - 1974) are cal-
culated by multiplying the emission factors (Ib SO per ton of product
(e.g., copper) by the increase in production of product between 1974 to
-------
TABLE 2. SUMMARY OF ESTIMATED ANNUAL SOV EMISSIONS
Commodity Process
Controlled
SOX emissions
in 1974 from
base case process
(106 Ib/yr)
Controlled
SOX emissions
(1989-1974)**
(106 Ib/yr)
Change in SOX
emissions from
base case
(in 1989)***
(106 Ib/yr)
Petroleum Base case:
East Coast refinery
• Direct combustion of
asphalt in process
heaters and boilers
• Flexicoking
Base case:
Gulf Coast refinery
• On-site electric power
by combustion of
vacuum bottoms
Base case:
West Coast refinery
• Hydrocracking of heavy
bottoms
• High-purity hydrogen
via partial oxidation
of asphalt
3,030****
1,230****
2,580****
758****
840****
803****
308****
308****
545****
728****
653****
+82****
+45****
+83****
+8****
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TABLE 2. (continued)
Commodity
Cement
Olefins
Controlled
SO emissions
in 1974 from
Process base case process
(106 lb/vr)
Base case :
Long dry kiln 553
• Suspension preheater —
• Flash calciner
• Fluidized bed
• Coal as fuel instead
of gas in long dry kiln
Base Case :
Ethane- Propane Process 28.6
• Naphtha process —
• Gas-oil process
Controlled
SO emissions
(1989-1974)**
(106 Ib/yr)
191
183
183
134
516
62
102
361
Change in SO
emissions from
base case
(in 1989)***
(1()6 Ib/yr)
—
-8
-8
-57
+325
—
+40
+299
Ammonia
Base case :
Ammonia via natural gas
• Ammonia via coal
gasification
• Ammonia via heavy
fuel oil
5.5
7.7
30.7
20.5
+23
+12.8
-------
TABLE 2. (continued)
00
Commodity
Alumina
Aluminum
Controlled
SOX emissions
in 1974 from
Process Base Case Process
(106 Ib/yr)
Base case:
Bayer process 25.4
• Hydrochloric acid
ion exchange —
• Nitric acid
ion exchange —
• Toth alumina —
Base case:
Hall-Heroult 1,045
(current practice, C.P.)
• Hall-Heroult \.new)
• Alcoa chloride —
• Refractory hard
metal cathode —
Base case:
Bayer with
Hall-Heroult (C.P.) 1,070
• Clay Chlorination (Toth
Controlled
SOX emissions
(1989-1974)**
(106 Ib/yr)
36
18
663
153
1,463
1,113
966
1,183
1,505
1,043*****
Change in SOX
emissions from
base case
(in 1989)***
(106 Ib/yr)
—
-18
+627
4-117
—
-350
-497
-280
-462 *****
alumina) and Alcoa
chloride
-------
TABLE 2. (continued)
Commodity
Newsprint
pulp
Process
Base case:
Kraft pulping
• Alkaline oxygen
pulping
• Rapson effluent-
free Kraft pulping
Base case:
Controlled
SOX emissions
in 1974 from
base case process
(106 Ib/yr)
766
—
—
Controlled
SOX emissions
(1989-1974)**
(106 Ib/yr)
829
59
844
Change in SOY
A
emissions from
base case
(in 1989)***
(106 lb/vr)
0
-770
+15
Flat glass
Refiner mechanical 96
pulp (RMP)
• Thermo-uiechanical —
p'ulp (TMP)
• De-inking of old
news for newsprint
iaanufacture
Base case:
Regenerative furnace 27.3
• Coal gasification
• Direct coal firing
Coal-fired hot gas
generation
42
34
12
12.2
13.1
43.4
16.1
-8
-30
0
+0.9
+31.2
+3.9
-------
TABLE 2. (continued)
Commodity
Flat glass
(cont. )
Copper
Chlorine ,
NaOH
Controlled
SOX emissions
in 1974 from
Process base case process
(106 Ib/yr)
• Electric melting
• Batch preheat with
natural gas firing
Base case:
Conventional smelting 2,250
• Outokumpu flash —
smelting
• Noranda
• Mitsubishi
• Arbiter
Base case :
Graphite-anode 454
diaphragm cell
• Dimensionally stable —
anodes
• Expandable DSA
• Polymer modified
Controlled
SOX emissions
(1989-1974)**
Q0b Ib/yr)
129
10.4
1,550
152
152
152
68
491
472
424
455
Change in SOX
emissions from
base case
(in 1989)***
(106 Ib/yr)
+117
-1.8
0
-1,398
-1,398
-1,398
-1,482
—
-19.0
-67.0
-36.0
asbestor
-------
TABLE 2. (continued)
Commodity
Chlorine ,
NaOH (cont.)
Steel
Controlled
SOX emissions
in 1974 from
Process base case process
(106 Ib/yr)
• Polymer membrane
• Ion exchange
membrane
• Mercury cell
Base case:
No off-gas recovery
• Off-gas recovery
—
"
—
16.4
—
Controlled
SOX emissions
(1989-1974)**
(106 Ib/yr)
455
447
557
12.0
6.0
Change in SOX
emissions from
base case
(in 1989)***
(106 Ib/yr)
-36.0
-44.0
+ 66
—
-6.0
Blast furnace
hot metal
Coke
Base case:
Blast furnace
• Blast furnace with
external desulfur-
ization
Base case:
Wet quenching of
coke
• Dry quenching of
coke
30
N.A.
13.4
13.4
N.A.
-30.6 ******
0.0
-30.6******
-------
TABLE 2. (continued)
Commodity
Steel
(integrated)
Phosphoric
acid
(detergent
grade)
Fertilizers
(nitric *cid)
Controlled
SOX emissions
in 1974 from
Process base case process
(106 Ib/yr)
Base case:
Steelmaking coke 189
oven, blast furnace
BOP route
• Direct reduction, —
EAF route
Base case:
Electric furnace 100
• Chemical cleanup of —
wet-process acid
• Solvent extraction —
of wet-process acid
Base case:
No NOX control -3.3
• Catalytic reduction
• Molecular sieve —
• Grand paroisse —
• CDL/Vitak
Controlled
SOX emissions
(1989-1974)**
(106 Ib/yr)
138
540
45
8.4
5.9
-2.6
-4.0
75.2
0.66
209.0
Change in SOX
emissions from
base case
(in 1989)***
(106 Ib/yr)
—
+402.0
-36.6
-39.1
—
-1.4
+77.8
+3.26
+212.0
-------
TABLE 2. (continued)
Controlled Change in SOX
SO emissions Controlled emissions from
in 1974 from SOX emissions base case
Commodity Process base case process (1989-1974)** (in 1989)***
(106 Ib/yr) (106 Ib/yr) (1Q6 Ib/yr)
Fertilizers • Masar — 383.0 +386.0
(cont.)
Fertilizers (mixed): Converting fertilizer dryers (with baghouses) from natural gas to oil.
Base case:
Natural gas Nil Nil Nil
• Better equipment — 0.29 0.29
technique with
fuel oil
• Installing scrubbers — 0.22 0.22
Textiles Knit fabric:
• Base case— 2.9 1.1
conventional aqueous
• Advanced aqueous — 1.0 -0.1
• Solvent processing — 0.5 -0.6
Woven fabric:
• Base case 50.0 19.3
• Advanced aqueous — 8.8 -10.5
-------
TABLE 2. (continued)
"Except where denoted by superscript ****.
'""Based on incremental production from the year 1974 to 1989 derived from anticipated growth rates
(Table 1).
^""Assumes no retirement of existing facilities by 1989.
""National emission rates calculated as though the alternative process applies to all national
oil refinery production.
*** /\ >\ /\ &
" Bayer process, plus Hall-Heroult (new plant) orocess, is used for comparative analysis.
!L JL J- JL JU *!.
Change estimated from base case.
N.A. not available.
-------
1989. Total actual emissions from each process for the year 1989 would
be the sum of 1974 emissions from the base case process assuming no re-
tirement of existing facilities and the actual incremental emissions per
year from the base case and new processes installed between 1974 and 1989.
The estimated increase or decrease in emissions from the alterna-
tive processes in relation to the base case process is also shown in
Table 2 for the year 1989. This number shows the potential for emis-
sion reduction in 1989 using new process technology. It is seen that
the greatest potential for emission reduction by new processes exists
in the copper industry, followed by the kraft pulp and aluminum indus-
tries.
In the copper industry, alternative processes using smelters are
aimed at generating gas that has a sufficiently high concentration of
S0x> so that the SO can be controlled by installing sulfuric acid plants.
Thus, these processes would have lower SO emissions.
X
In the kraft pulp industry, compounds containing sulfur are not
used in alkaline oxygen pulping, which eliminates emissions that con-
tain sulfur compounds.
The alternative processes in the aluminum industry are aimed at
reducing power consumption, which results in lower SO emissions at
the power boilers.
Some of the processes studied are aimed at changing the form value
of fuel from natural gas or oil to coal or asphalt. These process
changes would generally result in increased SO emissions because of
higher sulfur content in the fuel. This is seen in the petroleum, ce-
ment, alumina, and glass industries. The effect of changing from low-
sulfur feedstock to high-sulfur feedstock is seen in the olefin indus-
try and results in increased SO emissions.
x
To give some perspective to the magnitude of SO emissions,
Table 3 shows the industrial processes category to be the second larg-
est emitter of SO after electric utilities.
x
TABLE 3 SOx NATIONWIDE EMISSION ESTIMATES (1974)
Emission source
Stationary fuel combustion
- Electric utilities
- Other
Industrial Processes
Transportation
Solid waste
Miscellaneous
TOTAL
106 Ib/yr
42,200
11,400
12,600
1,600
200
200
68,200
% of total
61.9
16.7
18.5
2.3
0.3
0.3
100.0
Source: National Air Quality and Emissions Trend Report, 1975,
EPA, Research Triangle Park, N.C.; NTIS PB-263 922
15
-------
Should U.S. industry expand using current (base case) technology,
Table 4 shows that estimated controlled SO emissions in 1989 would
increase by 5.6 x 10 Ib compared to Sf>r emissions of 12.6 x 10 Ib
from industrial processes and 42.2 x 10 ^Ib from utilities in 1974
(Table 3). However, if all U.S. industry expanded by implementing the
technologies considered here that emitted the largest amounts of SO ,
Table 4 shows that the increase in SO emissions in 1989 would be 8.0
x 10 Ib, or some 43% higher than using conventional technology. On
the other hand, if industry expanded by implementing the least SO -
emitting technology, SO emissions in 1989 are calculated to increase
by 2.6 x 10 Ib or somex54% less than by conventional technology. If
the national production growth rate projections shown in Table 1 are
accurate, then calculated emissions will probably lie somewhere be-
tween these extremes, with energy (Btu) saving processes with lower
SO emissions somewhat balancing the switch from natural and fuel oil
to coal. Thus, incentives for the implementation of energy conserving
technology can have a significant effect on future SO emissions in
the industrial sector. x
Table 5 shows our estimate of the types of processes likely to be
installed in the time period up to 1989 with related SO emissions
from new plants calculated for the year 1989 assuming no retirement
of existing facilities. For example, a reading of the industry reports
shows that in the copper sector incremental copper smelting capacity
will be effected by one of the newer oxygen or flash smelting processes
(e.g., Outokumpu 4, Noranda, Mitsubishi). If such capacitygis installed,
anticipated annual SO emissions in 1989 would be 152 x 10 Ib SO /yr
(Table 5) compared toxthe 1,550 x 10 Ib S0-/yr, if conventional rever-
beratory furnace technology were employed. Similar judgments were made
in other sectors to arrive at total calculated annual emissions of
2.4 to 5.6 x 109 Ib SO emitted in 1989 from new plant capacity in-
stalled in the period 1974 - 1989.
Examination of the last column in Table 2 shows that greatest
reduction compared to the base case process in Ib of SO emissions per
year can be achieved by selective implementation of new processes in -
• copper (oxygen or flash processes)
• aluminum (Alcoa chloride, refractory hard metal cathodes)
• pulp (alkaline-oxygen)
Process changes in some of the industries shown in Table 2 may be
implemented because of feed stock shortages (e.g., the manufacture of
olefins from low-sulfur naphtha rather than higher sulfur gas oil),
and fuel switching (e.g., use of coal in cement making). In other
cases, processes may be developed for other reasons, such as develop-
ment of a domestic alumina industry based on indigenous kaolin clays.
Such a process, based on using coal to the extent possible, would
16
-------
TABLE 4. ESTIMATED INCREASE IN CONTROLLED
SOX EMISSIONS
1989-1974
ASSUMING INDUSTRY EXPANDS USING PROCESS TYPES INDICATED
(106 lbS02/yr)
Commodity (vol tio)
Steel (III)
Petroleum (IV)
Kraft pulp (V)
Newsprint pulp (V)
Olefins (VI)
Ammonia (VII)
Alumina (VIII)
Aluminum (VIII)
Textiles-knit (IX)
Textiles-woven (IX)
Cement (X)
Flat glass (XI)
Chlorine, NaOH (XII)
Phosphoric acid (XIII)
Copper (XIV)
Fertilizers (HN03) (XV)
TOTAL
Base case
process
138
758**
829
42
62
8
36
1,463
1
19
191
12
491
45
1,550
-3****
5,642
Using process
with largest
potential S0x
emissions
540
840
844
42
361
31
663
1,463
1
19
516
129
557
45
1,550
383
7,984
Using process
with smallest
potential SOX
emissions
101***
758
59
12
62
8
18
966
< 1
9
134
12
424
6
68
-4
2,634
*Volume Number of Industry Report
17
-------
TABLE 4 (continued)
**Assumes East Coast Refinery model applied nationally
***Includes credit of 37 x 106 Ib S02 attributed to energy
saved in dry quenching and BOP off gas collection.
****Credit for steam raised: see coverage on fertilizers in
Section 3.
18
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TABLE 5. ESTIMATED RANGE IN CONTROLLED SOX EMISSIONS IN 1989
FOR NEW PROCESSES LIKELY TO BE IMPLEMENTED
Commodity
(vol no)*
Likely types of
processes to be
implemented in
new plants
Calculated range
in annual SOX
emissions for new
plant capacity-1989
(106Ib/vr)
Steel (III)
Petroleum (IV)
Kraft pulp (V)
Newsprint
pulp (V)
Olefins (VI)
Ammonia (VII)
Alumina**
(VIII)
Aluminum**
(VIII)
Textiles,
knit(IX)
Textiles,
woven (IX)
Cement (X)
Flat glass (XI)
Chlor-alkali
(XII)
Coke oven, blast furnace, BOP****,*** 132-138
Hydrocracking, flexicoking, etc. 308-803*****
Kraft, Rapson, alkaline-oxygen 59-844
RMP, TMP, De-inking
Naphtha, gas oil
Heavy fuel oil, coal
Bayer, leaching domes tic clays
Hall-Heroult, aluminum chloride
Advanced aqueous, solvent
Advanced aqueous
Preheaters, coal firing, etc.
Regenerative furnaces, preheaters,
electric furnaces
Dimensionally stable anodes, new
membranes
Phosphoric acid!
detergent grade
(XIII)
12-42
102-361
21-31
36-663
966-1050
1-1
9-9
134-516
12-129
424-472
Wet acid cleanup
8-8
19
-------
TABLE 5 (continued)
Commodity
(vol no)*
Likely types of
processes to be
implemented in
new plants
Calculated range
in annual SOX
emissions for new
plant capacity-1989
(106 Ib/yr)
Copper (XIV) Oxygen or flash processes*** 152-152
Fertilizers-
Nitric Acid (XV) Various NO control technologies (4)-383
X
TOTAL 2,372-5,602
*Volume Number of Industry Report
**A significant fraction of the incremental U.S. demand is
expected to be imported.
***In addition, electric furnaces are expected to be installed
based at least partially on scrap.
****With collection of CO from BOF's.
*****Base Case Gulf Coast Refinery model applied nationally.
20
-------
result in significantly higher SO emissions than a Bayer plant based
on natural gas, as described in tne Alumina/Aluminum Industry report.
Although the estimated change in emissions listed in Table 2 was based
on incremental capacity from 1974 to 1989 only, in some cases an alter-
native process, or a process modification, may replace existing capac-
ity. For example, in the aluminum industry, refractory hard metal cat-
hodes may be installed in existing Hall Heroult cells. The application
of alternative processes to existing plant capacity will increase the
potential effect on SO emissions, compared to the estimated effect
shown in Table 2. Further perspectives in each of these industry sec-
tors with descriptions of the processes can be obtained from the indi-
vidual industry sector reports (Volumes III through XV).
R&D AREAS
The following areas of potential R&D for industry, government, or
other institutions have been identified with regard to SO emissions
from the new technologies investigated:
SOYRelated
Better definition of the environmental, health, and ecologi-
cal impacts of SO emissions with respect to obtaining more
quantitative knowledge for establishing appropriate emission
regulations.
In going from gas to oil to coal, increased SO emissions may
be expected. Therefore, it would be desirable to promote
coal-cleaning methods to remove SO , coal gasification with
SO control, and flue gas desulfurlzation techniques which
would help to minimize the dispersal of SO and mitigate the
SO emission problems.
x
Promote process alternatives aimed at reducing energy re-
quirements. For a fuel containing a fixed amount of sulfur,
SO emissions are in direct proportion to the energy con-
sumption and, therefore, reduction in energy consumption
will result in lower SO emissions. Examples of such poten-
tial energy-conserving processes include:
a) Rapson, alkaline/oxygen and de-inking technologies
in the pulp sector;
b) advanced aqueous or solvent processes in textiles;
c) CO collection from basic oxygen furnaces;
d) aluminum production by refractory metal cathodes
or by the aluminum chloride (Alcoa) electrolysis
route;
21
-------
e) phosphoric acid (wet acid grade) by the strong
acid process;
f) detergent grade phosphoric acid by the chemical
clean-up of wet acid; and
g) flotation of copper values from copper smelting
slags.
In addition, similar energy conservation and SO reduction are achieved
by the generic technologies of solid preheating (e.g., in glassmaking,
or flash calcining in cement) or use of oxygen (e.g., flash smelting
in copper, or the Mitsubishi and Noranda oxygen-based processes).
Process-Related
Cement—
Develop and implement a comparative test program at a number
of cement plants with clinkering facilities employing long-
rotary-kiln, suspension preheater, or flash-calciner process-
es in which coal is burned as the fuel. Coal of various sul-
fur levels should be tested to determine the effect on oper-
ation of the level and nature of sulfur in gas, dust, and
clinker. The benefits which derive from the physical and/
or chemical cleaning of coal to reduce pyritic sulfur levels
in coal for cement manufacturing should also be quantified.
Develop and implement a commercial-scale test program on one
or more flash-calciner-equipped rotary-kiln, cement-making
facilities to characterize SO emissions. Of particular
interest would be the emissions from operating with a bypass
of a considerable amount of the combustion gases to eliminate
alkalies.
Olefins—
The olefins industry can benefit from additional research
on the removal of sulfur from the cracked gas stream. This
stream contains hydrogen sulfide, some carbonyl sulfide, and
varying percentages of diolefins and other reactive compounds
which tend to foul the acid-gas-removal system. This problem
is now being handled by depropanizing the cracked-gas stream
before acid gas is removed by scrubbing with diethanolamine.
A method for removing the sulfur compounds and acid gases
from the cracked-gas stream in the presence of diolefins
(i.e., before the depropanizer) would be of significant eco-
nomic benefit to the olefin producers.
Naphtha and atmospheric gas oil feedstocks produce signifi-
cant quantities of byproduct pyrolysis fuel oil. If the
22
-------
feedstock material to the olefins plant has a sulfur content
above a certain concentration, the byproduct pyrolysis fuel
oil has sulfur levels too high for its environmentally accept-
able use as a fuel without flue gas desulfurization. These
byproduct fuel oils also contain substantial amounts of un-
saturates as well as other reactive materials which tend to
polymerize and form gums on handling. These present problems
when attempting to desulfurize the oils. It would be desir-
able to develop an economically attractive process for desul-
furizing the pyrolysis fuel oil to a level where it would be
environmentally acceptable as a fuel. At present, most ole-
fin producers limit the sulfur content of their feedstock to
circumvent this problem. However, this limitation severely
restricts their choice of feedstocks.
Aluminum—
Consider materials research in the field of producing tita-
nium diboride cathodes suitable in quality to permit long
operating life in the Hall Heroult cell. This development
would have an effect on energy savings in the existing al-
uminum plants, thus reducing SO emissions at the power
boiler. x
Pulp and Paper—
Glass—
The alkaline oxygen process would alleviate the SO pollution
problems presently associated with the major alternative man-
ufacturing method—namely, kraft pulping and bleaching. Eval'-
uation of this process and process emissions is desirable.
The de-inking of old news for the manufacture of newsprint
presents an opportunity to save energy and reduce SO emissions
accompanying the pulping of an equivalent amount of virgin
feedstock. Broader commercial application should be support-
ed, because it also could reduce the amount of municipal sol-
id waste.
A proven system to control glass furnace emissions of SO and
particulates must be developed if cost-effective pollution
control is to be obtained. Such a system is required if any
of the coal-related processes is to be utilized. While sev-
eral systems have been developed, such as a coated fabric
filter built by Teller Environmental Systems, (Worcester,
Mass.), none has been generally accepted by the glass indus-
try as a proven cost-effective technology.
23
-------
Copper—
Methods ehould be developed for removing impurities (e.g., Bi)
from blister copper via modified fire-refining procedures.
If impurities can be removed from copper, one-step smelting
can be used. This would significantly decrease fugitive SO
emissions from smelters.
24
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SECTION 3
PROCESSES AND SO EMISSIONS
X
BASES OF CALCULATIONS
In Volume II (P19) describing the methodology used in this study,
we indicated that selected State air emission regulations along with
the Federal Government's stationary source performance standards and
effluent limitation guidelines were surveyed to:
• establish the most probable limits of air emissions, and
• obtain a perspective of the types of pollution control systems
to be considered.
While there are a large number of different regulations for airborne
emissions at the State regulatory level, we found that approximately
the same type of air pollution control systems would be required,
regardless of the State or Federal regulations to be met. Generally,
these air Pollution control systems included baghouses, venturi scrubbers,
inertial impact devices, and electrostatic precipitators for particulates
and chemical based systems for sulfur removal, such as alkaline-based
aqueous scrubbing for SO
X •
In this Section, SO emissions from the process industries
(Volumes III through XV) and specific control methods are reviewed.
There are two general sources of emissions: the processes themselves
and power boilers used for generation of steam and/or electricity.
While emissions from the power boiler generally were not considered in
the original study, they are included in the present analysis to show
the net change in emissions resulting from a process change. Both on-
site power boilers and electric utility power boilers are included.
It was found to be important to include power boilers in order to
meaningful compar:
alternative processes.
make meaningful comparisons on SO- emissions between the base case and
Power boilers are assumed to burn coal containing 3.5% sulfur, and
the uncontrolled SO emissions are estimated at 5.54 Ib of SO /10° Btu
(12,000 Btu/lb of coal), or 0.058 Ib of SO /kWh (based on an average
requirement of 10,500 Btu to generate 1 kwft). The uncontrolled SO
emissions assume 95% of the sulfur in the coal appearing as SO in the
flue gas largely as S0~ with only 1-3% as S0_. The controlled emissions
from new plants are assumed to meet the new source performance standard
(NSPS) of 1.2 Ib of SO /106 Btu, equivalent to about 0.0126 Ib of SO /kWh.
The SO emissions from the base case process and process alternatives
X
25
-------
are described and summarized for each industry. The SO emission
factors are estimated, and the effect of these factors on the incre-
mental production from 1974 to 1989 is calculated.
SO CONTROL METHODS
x
Control methods are limited to point sources only and fugitive
emissions are not discussed. Since SO control methods have been well
discussed in the literature, such methods are not described in detail
here but are only listed.
Uncontrolled SO emissions result from the sulfur present in the
fuel and in the feedstock which upon combustion results in SO air
•v
emissions from high-temperature processes. The control technology
for reducing emissions containing sulfur compounds are:
1) reduction of sulfur in the fuel and feedstock;
2) process modifications to prevent escape of sulfur compounds
to the atmosphere; and
3) removal of sulfur compounds in the tail gas before it is
exhausted to the atmosphere.
Other methods include use of tall stacks and controlling the sulfur
compounds concentration in the vicinity of the source. These methods
do not reduce the emissions of sulfur compounds to the atmosphere, but
are aimed at dispersing the emissions to the atmosphere and at using
production curtailment to control ground-level pollutant concentrations.
The production curtailment method, used when adverse weather conditions
prevail, has been referred to as a "supplementary control system (SCS),"
when it is based on the monitoring of sulfur compound concentration at
ground level at various sites in the areas surrounding the source,
knowledge of which is used to control the production rate.
Reduction of Sulfur Compounds in Feed Materials and Fuel
Sulfur emissions from a process may be reduced by using feed mat-
erials and fuel having lower sulfur or content, or by reducing sulfur
content in such materials before they are used. The first alternative
is not available in all cases, because of the limited supply of mater-
ials. Reducing the sulfur content of feed materials and fuel is widely
practiced for oil and, to limited extent, for coal.
The applicability of desulfurization of oil in the petroleum in-
dustry is determined principally by the characteristics of the oils to
be processed and the end-product sulfur specification. Sulfur removal
of 90+ % is technically feasible for most oil stocks. The important
feedstock properties with respect to influence on the desulfurization
of oil are: organometallic compounds (principally nickel and vanadium)
26
-------
and the asphaltene content of the feedstock. Lower organometallic com-
pounds and asphaltenes are desirable for desulfurization.
The desulfurization of coal is practiced to a lesser extent. Sul-
fur removal has been in the range of 10-50%. Part of the fuel value of
the coal is lost in the process and the loss increases with increased
sulfur removal. However, the heating value per ton of cleaned coal may
actually rise, especially if some inert materials are simultaneously
removed.
Process Modifications to Prevent Escape of Sulfur Compounds in Air
Emissions
This method of emission reduction has been applied, to a limited
extent, to coal combustion. An alkali such as limestone is added with
the coal to the boiler. The limestone reacts with sulfur to form cal-
cium-sulfur salts, which are removed along with the bottom ash. Lime-
stone may also be used to remove sulfur compounds in the generation of
gas from coal. A detailed description of this process is given in the
discussion of the glass industry found later in this Section.
In some cases, alkali materials, present in the process, help to
reduce SO emissions. For example, in cement kilns only a fraction of
the sulfur present in the feedstock and fuel appears in the flue gas,
since the remainder is removed by alkaline particles in the kiln feed.
Removal of Sulfur Compounds from Process Gaseous Emissions
The sulfur compounds in tail gas are present as reduced sulfur
compounds or as sulfur oxides. Reduced sulfur compounds, such as hy-
drogen sulfide, usually have associated odors and, therefore, their e-
missions are more obnoxious than those of the sulfur oxides. The SO
X
in the exhaust gas is generally present as S0_, except in some cases
(such as in glass manufacture) where sulfur emissions are generated
from sulfates in the raw materials and result in SO emissions. SO
also forms because of oxidation of SO and, similarily, S0« may form
because of reduction of SO .
The SO emissions are difficult to control because the SO is gen-
erally present in the form of submicronic mist at the operating temper-
ature of the pollution control equipment. As a result, a very efficient
de-mister is required for control.
In the pulp and paper mills, the sulfur compounds are present in
reduced form in combination with hydrogen or organic compounds. The
control method used involves incineration of the sulfur compounds to
convert to sulfur oxides often followed by a pollution control device
used to remove the SO .
x
In the petroleum industry, the sulfur compounds are present as COS,
H_S, etc. The gases are removed in an acid gas treatment system for
27
-------
process requirments. The acid gases are removed by amine absorption or
caustic scrubbing. The concentrated gases from the regeneration step
of systems, such as amine absorption, are treated in the Glaus plants,
followed by a tail gas cleanup system, such as the Stretford process.
In this way, the sulfur compounds are converted to elemental sulfur.
If the volume of the gas stream is small, the Stretford process may be
used directly to remove sulfur compounds after the acid gas has been
removed.
There are several methods available for removing SO from flue gas.
At low concentration (less than 1-2% SO ) and at low gas-flow rates,
alkaline scrubbing may be used to control SO emissions. At low con-
centrations (less than 0.5% SO.) and at high gas-flow rates, such as
from power boilers, flue gas desulfurization methods (FGD) are used.
Depending on the product stream, these methods are classified as fol-
lows :
• Waste salt process,
• Concentrated SO process,
• Direct sulfuric acid process, and
• Elemental sulfur process.
For processes that generate concentrated emissions (more than 4-6%
and large-volume gas streams (such as copper
acid plants are used to control the SO. emissions,
S0?) and large-volume gas streams (such as copper smelting), sulfuric
The SO emissions may also be removed by dry processes, as in bag
filters, if a coat of alkaline material is present. In cement kilns,
bag filters are used to control particulate emissions and, because of
the alkaline nature of the particles, a significant fraction of the SO
is removed. In some systems, such as in controlling the emissions from
glass furnaces, alkaline material is introduced upstream of the bag
filters to control SO emissions.
x
PETROLEUM REFINING
Base Case Process - 1985 Refinery
A description of the petroleum refining industry is presented in
Volume IV, page 9. In assessing the impact of process changes in the
refining industry, a 1985 refinery configuration was used as a base
case. The reasons for using this approach are given in Volume IV,
page 22. Three configurations were selected to represent the local con-
ditions: the East, Gulf, and West Coasts. Results of our analyses are
given in Table 6.
28
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TABLE 6. ESTIMATED SOX EMISSION FACTORS - PETROLEUM REFINING INDUSTRY
Emission factor* - no control Emission factor* - with control
(lb/10y Btu of refinery output) (lb/109 Btu"of refinery output) Control
Process Process Power boiler Total Process Power boiler Total 0/iency
^_ &
Base case:
East Coast refinery 84 80 164 84 17 101 38
• Direct combustion of 360 87 447 93 19 112 75
asphalt in process
heaters and boilers
• Flexicoking 364 80 444 90 17 107 76
Base case:
Gulf Coast refinery 31 46 77 31 10 41 47
• Onsite electric power 31 23 54 31 10 41 24
by combustion of
asphalt
Base case:
West Coast refinery 74 55 129 74 12 86 33
• Hydrocracking of 167 63 230 83 14 97 58
heavy bottoms
• High-purity hydrogen 119 59 178 74 13 87 51
production via partial
oxidation of asphalt
^Emissions reported as Ib SOo/lO Btu of refinery output.
-------
East Coast Refinery
Base Case Process—
The base case East Coast refinery is described in Volume IV,
page 23. The energy intake in this refinery (in terms of crude oil,
fuel oil, steam, and electricity) is 1.31 x 10 Btu/day and production
is equivalent to 1.19 x 101 Btu/day (Vol. IV, page 35).
The major airborne pollutants emitted by refineries have been pre-
viously identified in Volume IV, page 24. The emission factors sum-
marized in EPA's "Compilation of Air Emission Factors" (1973) were used
to determine SO emissions from the base case refinery. The SO emis-
sions are: 45,200 Ib SO /day from combustion sources (heaters^oil-
fired boilers); 52,800 1§ SO /day from fluid catalytic crackers; and
2,200 Ib SO /day from the Glaus plant. Uncontrolled emissions of
100,280 Ib §0 /day are equivalent to an emission factor of 84 Ib SO /10^
Btu of refinery output. The emissions from the combustion sources and
fluid catalvtic crackers are not controlled. Sulfur emissions from the
Glaus plant" are based on 99.5% recovery of the sulfur in the acid gas.
Purchased steam and electricity in the base case refinery are e-
quivalent to 8.2 x 109 Btu/day and 8.9 x 10 Btu/day, respectively. The
estimated emissions from the associated coal-fired power boiler are
94,700 Ib S0x/day, based on no control, and 20,500 Ib SO /day, assuming
control to meet the New Source Performance Standard (NSP*-). The esti-
mated emissions are equivalent to 79.8 Ib SOX/10^ Btu of refinery output
based on no control, and 17.3 Ib SOX/109 Btu of refinery output,
based on control to meet the NSPS resulting in total emissions of
101 Ib SO /109 Btu, as shown in Table 6.
X
Process Option 1 - Direct Combustion of Asphalt in Process Heaters and
Boilers—
A detailed description of this alternative appears in Volume IV,
page 32. Utilizating asphalt for combustion is intended primarily to
upgrade the overall form value of refinery products rather than to act-
ually increase the overall thermal efficiency within the refinery. Part
of the refinery gas (36.6%) and all of the fuel oil are displaced
by asphalt. The energy balances for the base case process and the al-
ternative are summarized in Volume IV, page 35. In the alternative
process, SO emissions are increased because of the increased sulfur in
the asphalt.
The emissions from the asphalt combustion are 15,395 Ib SO /hr
(Volume IV, page 38). The emissions from the combustion sources in
the base case process are eliminated in this alternative, because oil
is not used for combustion. Thus, the total refinery emissions are
425,000 Ib SO /day, equivalent to about 360 Ib SO /109 Btu of refinery
output. X x
*For discussion, see Vol. IV, p 152.
30
-------
The emissions from the asphalt combustion may be controlled by an
add-on FGD system. If the SO removal efficiency is 85% (Volume IV,
page 39), the emissions from the combustion sources will be reduced to
an estimated value of 55,400 Ib SO /day. The total emissions are est-
imated at 110,400 Ib SO /day, equivalent to 93 Ib SO /10 Btu of refin-
ery output, as shown in Table 6.
9 9
Purchased steam and electricity are 9.7 x 10 Btu/day and 8.9 x 10
Btu/day, respectively (Volume IV, page 35). Estimated emissions from
the power boiler are 87 Ib SO /10 Btu of refinery output, based on no
control, and 19 Ib SO /10 Btu of refinery output, based on control to
meet the NSPS. Thus, combining these figures results in about an 11%
increase in SO emissions compared with the base case, as shown in Ta-
ble 6 and 7 .
Process Option 2 - Flexicoking —
Flexicoking is the combination of fluid coking with coke gasifi-
cation. Although fluid coking is a commercially available technology,
there are no commercially operating flexicokers. A detailed process
description is given in Volume IV, page 52, with emissions discussed on
page 59.
The major air pollution problem associated with the Flexicoking
process is in controlling sulfur in the streams of fuel gas (light
hydrocarbons containing l^S) and flexigas (a low-Btu fuel gas contain-
ing N2» CO, C02» H2, and sulfur, and its compounds).
The sulfur in the fuel gas is removed using an amine scrubbing
system, and the exhaust of that scrubbing system is sent to the refin-
ery Glaus plant. The hydrogen sulfide in the low-Btu flexigas is too
low in concentration to be economically scrubbed out, and, therefore,
this process comes with an integral Stretford unit for sulfur removal.
The sulfur concentration in the product flexigas is approximately
170 ppm, which is within allowable standards for combustion without
sulfur control.
The emissions having sulfur compounds are 2,920 Ib SO /day from
the combustion of flexigas and 159,580 Ib sulfur /day, in tfie acid gas
stream. The total emissions from the refinery are equivalent to 364 Ib
SO /10 Btu of refinery output. If the sulfur emissions in the acid
gas stream are controlled, the total emissions from the refinery are
reduced to an estimated value of 90 Ib SO /10 Btu of refinery output,
as shown in Table 6.
*Some additional background on the Stretford process is found in
Volume XI, p 38, "Environmental Considerations of Selected Energy
Conserving Manufacturing Process Options: Petroleum Refining Industry
Report"
31
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TABLE 7. ESTIMATED SOV EMISSIONS - PETROLEUM REFINING INDUSTRY
u>
Emission factor
SOV Emissions
(Ib SOX/109 stu of refinery output) Change in (106 Ib/yr)
Process Process Power boiler Total emission factor 1974 1989-1974*
Base case:
East Coast refinery 84 17 101
• Direct combustion of 93 19 112 +11
asphalt in process
heaters and boilers
• Flexicoking 90 17 107 +6
Base case:
Gulf Coast refinery** 31 10 41
• Onsite electric power 31 10 41 0
by combustion of
vacuum bottoms
Base case:
West Coast refinery** 74 12 86
• Hydrocracking of 83 14 97 +11
3,030** 758
840
803
1,230** 308
308
2,580** 645
728
heavy bottoms
• High purity hydrogen 74
production Via partial
oxidation of asphalt
13
87
+1
653
-------
TABLE 7 (continued)
*Based on incremental national production from 1974 to 1989 equal to 7.5 quads (7.5 x 10 Btu)
multiplied by emission factor asssuming no retirement of existing facilities.
**Estimated 1974 emissions, based on the total emission factors and production of 30 quads are
3,030 X 106 ibs, 1,230 x 106 Ibs and 2,580 x 106 Ibs for East Coast, Gulf Coast and West
Coast models, respectively.
-------
The emissions from the power boiler are comparable to those in the
base case process, i.e., about 80 Ib SO /10 Btu of refinery output,
based on no control, and 17 Ib SO /IO §tu of refinery output, based on
control to meet the NSPS. Total SO emissions thus increase by about
6% as shown in Tables 6 and 7.
Gulf Coast Refinery
Base Case Process—
The base case refinery configuration in the year 1985, located on
the Gulf Coast is described in Volume IV, page 23. Total energy input
in the base case refinery is 1,358 x 10 Btu/day and production is
equivalent to 1,197 x 10 Btu/day. SO emissions from this base case
process were developed in a manner similar to that for the East Coast
refinery using oil-fired boilers.
The emissions include 27,600 Ib SO /day from combustion sources;
8,400 Ib SO /day from fluid catalytic crackers and 680 Ib SO /day from
the Glaus pfant. The total emissions of 36,680 Ib SO /day (Volume IV,
page 25) are equivalent to 31 Ib SO /IO Btu of refinery output. Sul-
fur emissions from the Claus plant are based on 99.5% recovery of the
sulfur in the acid gas.
Q
Based on electricity consumption equivalent to 9.2 x 10 Btu/day
and steam consumption equivalent to 0.7 x 10" Btu/day (Volume IV,
page 70), the estimated emissions from the power boiler are 46 Ib SO /
10" Btu, based on no control, and 10 Ib SO /IO" Btu, based on control!
to meet the NSPS, resulting in total discharges of 41 Ib SO /IO9 Btu.
Process Option - On-site Electric Power by Combustion of Vacuum Bottoms—
In this process alternative, electric power is generated within
the refinery rather than purchased from a local electric utility. The
fuel is assumed to be asphalt. A simplified flow sheet for this alter-
native is shown in Volume IV, page 69.
Generation of electric power within the refinery neither conserves
energy nor consumes more energy than when power is purchased, assuming
that the internal and external power plants would operate at the same
efficiencies. In effect, the form value of the asphalt is upgraded to
a higher form value of electric power for refinery use. The design
capacity of the generator, as shown in Volume IV, page 77, is 36.5 me-
gawatts.
This process alternative will result in increased on-site SOX
emissions. SO emissions from the on-site power boiler are 27,456 Ib
SO /day (Volume IV, page 73), equivalent to 23 Ib SO /IO9 Btu of refin-
ery products. The costs of sulfur control for on-site electric power
generation is shown in Volume IV, page 76. If the emissions are
34
-------
controlled to meet the NSPS, the resulting SO emissions will be about
10 Ib SO /109 Btu of refinery output. X
X
West Coast Refinery
Base Case Process—
The base case refinery configuration in the year 1985, located on
the West Coast, is described in Volume IV, page 23. Total energy input
in the base case refinery is 1,009 x 10 Btu/day and production is
equivalent to 950 x 10^ Btu/day. SOX emissions from the base case pro-
cess were developed in a manner similar to that for the East Coast
refinery using oil-fired boilers.
The emissions include 58,800 Ib SO /day from combustion sources;
7,600 Ib SO /day from fluid catalytic crackers; and 3,680 Ib S0x/day
from the Claus plant. The total emissions of 70,080 Ib SO /day (Volume
IV, page 26) are equivalent to 74 Ib SO /109 Btu of refinery output.
Sulfur emissions from the Claus plant are based on 99.5% recovery of
the sulfur in the acid gas.
g
Based on electricity consumption equivalent to 9.5 x 10 Btu/day
(Volume IV, gage 46), the estimated emissions from the power boiler are
55 Ib SO /109 Btu of refinery output, based on no control, and 12 Ib
SO /109 8tu based on control, to meet the NSPS, resulting in total dis-
charges of 86 Ib SO /109 Btu.
Process Option 1 - Hydrocracking of Heavy Bottoms—
In this option, asphalt is used as a feedstock for a hydrocracking
process such as H-Oil or Isomax in which the heavy bottoms are convert-
ed to lighter fuel oils and gaseous products. The H-Oil process was
chosen to exemplify a heavy-ends hydrocracking process. A detailed des-
cription of the process is given in Volume IV, page 43. The pollutants
of concern in this option are t^S, generated in the gaseous products,
and S02> generated from the combustion of a small amount of asphalt.
The gases from the H-Oil reactor will pass through an amine scrubbing
system to remove H£S and C02- These are sent to a Claus plant for sul-
fur control. Since a refinery normally would have a Claus plant,
the cost of control for this option is only the incremental cost re-
quired to expand the Claus plant to handle the additional sulfur load
(Volume IV, page 152).
In addition to the sulfur control costs for hydrotreating, the
equivalent of 900 BPD of asphalt also has to be burned in the process
heaters to free up refinery gas which can be used to generate the ad-
ditional hydrogen needed for the hydrotreater. Since the asphalt has
a sulfur content higher than the allowed maximum uncontrolled sulfur
content of a fuel, flue gas desulfurization will be required. If all
of the asphalt were burned in a single process heater, the size would
be approximately 240 x 106 Btu/hr.
35
-------
The incremental uncontrolled emissions include 715 Ib SO., /day from
purge gas, 54,530 Ib S/day from acid gas stream, and 12,748 Ib SOX per day
from asphalt combustion (Volume IV, page 48). Total emissions fiom the
refinery are about 192,600 Ib SO /day, equivalent to 167 Ib SO /109 Btu
of refinery output.
If the sulfur emissions from the tail gas are controlled by the
Glaus plant and the emissions from the asphalt combustion are controlled
by the wet scrubber, the incremental emissions will be reduced to an
estimated value of 8,170 Ib SO /day (to meet EPA standards). Therefore,
the total estimated controlled emissions from the refinery are about
83 Ib SO /l(r Btu of refinery output.
X
Based on electricity consumption of 10.8 x 10 Btu/day (Volume IV,
page 46), the estimated emissions from the power boiler are 63 Ib SO /Q
10 Btu of refinery output if no control is provided, and 14 Ib SO /$0
Btu of refinery output if the emissions are controlled to meet the^SPS.
The total SO emissions will then be 83 plus 14 or 97 lb/10 Btu of out-
v
put; an increase of 13%.
Process Option 2 - High-Purity Hydrogen Production via Partial
Oxidation of Asphalt—
This alternative is based on the production of high-purity hydro-
gen for hydrotreating from vacuum bottoms, using a partial oxidation
process. The feedstock freed up by this approach would then be avail-
able for sale outside the refinery in the form of pipeline gas or
naphtha. A detailed process description is given in Volume IV, page 78.
The major emission associated with this process change is the sul-
fur removed from the raw syngas in the form of I^S. This is removed
from the gas using an amine scrubber system. The exhaust from the amine
regenerator, which contains the sulfur as well as C02» is sent to a
Glaus plant for sulfur recovery and air pollution control. Several
states have emission standards regulating tailgas for sulfur recovery
plants so that tailgas cleanup will be required to limit emissions from
the plant to 250 ppm or less. The incremental uncontrolled emissions
are 21,200 Ib of S/hr, equivalent to 45 Ib of SO /109 Btu of refinery
output. If the emissions are controlled, the additional emissions are
estimated to be equivalent to 0.2 Ib SOX/109 Btu of refinery output.
The emissions from the power boiler (coal-fired) are estimated at
59 Ib SO /10 Btu of refinery output, based on no control, and 13 Ib
SO /10y Btu of refinery output, based on control to meet the NSPS. Ta-
bles 6 and 7 show that SO emissions are only 1% higher than those for
the base case process.
Summary
Table 6 shows that uncontrolled emissions are increased in all
alternatives, except for the case of on-site generation of electric
36
-------
power by combustion of asphalt. The sulfur content in the asphalt is
lower than that in the coal burned in the power boiler.
The emission control methods include removal of reduced sulfur in
acid gas cleaning followed by the Glaus and Stratford plants, and flue
gas desulfurization. As shown in Table 6, overall control efficiency
varies from 24 to 76 percent. Also, the controlled emissions in the
alternative processes are comparable or higher than those in the cor-
responding base case process. Based on the assumption that each proc-
ess option is considered individually for application in 100% of refin-
ery expansion, the controlled SO emissions from refinery industry are
summarized in Table 7. Examination of Table 2 shows that even small
percentage changes in the petroleum industry can have significant nat-
ional impact.
CEMENT
Base Case Process - Long Rotary Kiln
The production of finished cement from raw materials involves four
steps: crushing, grinding, clinkering, and finish grinding. From a
materials viewpoint hydraulic cement is a powder made by heating lime,
silica, alumina, iron oxide, and magnesia together in a kiln and then
pulverizing the product. The base case process selected for the cement
industry was the long rotary kiln with dry grinding. In the dry cement
process, grinding is performed dry, very much like wet grinding, except
that no water is added and the material is ground at 1% moisture con-
tent or less. A detailed description of the process is given in Volume
X, page 84.
The base case process is based on natural gas or oil as fuel. How-
ever, the emissions are estimated using natural gas as a fuel in the
cement kiln since more natural gas than oil was used in 1974 in the
cement industry (Volume X, page 92). Very little sulfur is present in
the natural gas, so all the emissions result from sulfur present in the
raw materials. The uncontrolled emission factor is 10.2 Ib SO /ton of
cement as reported in "Compilation of Air Emission Factors" (EPA, 1973).
In addition, gaseous emissions from the combustion of high sulfur fuel
in the kiln are usually not sufficient to create significant air pol-
lution problems. Most of the sulfur dioxide formed from the sulfur in
the fuel is recovered as it combines with the alkalies and also with
the lime when the alkali fume is low.
Usually bag filters are used to control particulate emissions from
the cement kilns (Volume X, page 101). With bag filters, approximately
50% of the SO is removed by passage through the alkaline particulate
filter cake. Other control methods include reduction of sulfur in the
feed and fuel to the kiln.
In addition to the process emissions, electricity consumed in the
37
-------
plant will result in emissions at the power boiler. The electricity
consumed in the long kiln is equivalent to 1.61 x 10" Btu/ton of cement
resulting in estimated uncontrolled emissions of 8.9 lb SO /ton of cem-
ent. If the emissions are controlled to meet the NSPS, the emissions
will be reduced to an estimated value of 1.9 lb SO /ton of cement. Con-
sequently, the total controlled SO emissions willxbe 7.0 Ib/ton.
X
Process Option 1 - Suspension Preheater
The suspension preheater is a modification of, or addition to, the
cement rotary kiln. It is attached to the raw feed inlet end of the
kiln, totally replacing the preheating zone. The suspension preheater
preheats the raw material and also accomplishes a considerable amount
of raw material calcination. Typical suspension preheaters heat cold
raw feed to approximately 1,400 F and accomplish 30-40% of the total
calcination or thermal decomposition of the calcium carbonate, the main
component of the raw feed. Consequently, with the suspension preheater,
the rotary kiln receives hot and partially calcined raw material. There
are several variations on the suspension preheater (described in Volume
X, page 19).
Raw material which has been partially calcined is highly reactive
with sulfur dioxide and oxygen, forming calcium sulfite and sulfate.
Any SO which might form in the combustion gases in a rotary kiln, even
using nigh-sulfur coal as fuel, contacts the raw material so intimately
that the use of a suspension preheater system should not present any
sulfur dioxide emission problems. However, no quantitative data are
available, so emissions cannot be estimated.
The electricity consumption is reduced to 1.32 x 10 Btu/ton of
cement, so the estimated emissions from the power boiler are 7.3 lb SO /
ton of cement, based on no control and 1.6 lb SO /ton of cement based x
on control to meet the NSPS. Overall, some reduction on SO emissions
can be expected.
Process Option 2 - Flash Calciner
Although designs of flash calcining systems vary, the main feature
which characterizes the flash calciner rotary kiln is the flash cal-
cining vessel added between the rotary kiln and the suspension pre-
heater. A detailed process description is given in Volume X, page 34,
The flash calciner arrangement (described in Volume X, page 23)
requires a considerable amount of excess combustion air in burning the
fuel in the rotary kiln so that enough air is present in the combustion
gases leaving the kiln to permit combustion of the fuel in the flash
calcining vessel.
By the time the combustion gases exit to the atmosphere, essential-
ly all of the SO should be absorbed and reacted with the raw feed.
X
38
-------
However, any gases which might be bypassed could be different in SO
content from suspension preheater bypass gases because the raw feed
entering the flash calciner kiln is almost completely calcined, and
also has a significantly lower kiln residence than in a suspension pre-
heater. However, no quantitative data are available, so the emissions
cannot be estimated but are thought to be lower than the long kiln.
The electricity consumption is comparable to that in the suspen-
sion preheater alternative and therefore the estimated emissions from
the power boiler are 7.3 Ib SO /ton of cement based on no control, and
1.6 Ib SO /ton of cement basedxon control to meet the NSPS.
x
Process Option 3 - Fluidized-Bed Cement Process
The only difference between the fluidized-bed cement process and
the conventional process is the high-temperature clinkering step. All
of the other steps are essentially identical. A detailed description
of the process is given in Volume X, page 40. Comparing the energy
consumption in the fluidized bed and in the long kiln (Volume X, page
46) , one finds the fuel consumption in the fluidized bed to be about
10% higher. No quantitative data regarding SC^ emissions are available
so emissions cannot be estimated but are thought to be lower than in
the long kiln.
There is a net recovery of energy in the form of electricity in
the fluidized bed process (0.15 x 10^ Btu/ton of cement; Volume X, page
46) resulting in a credit (i.e., negative emissions) at the power boil-
er estimated at 0.83 Ib SO /ton of cement, based on no control; and
0.18 Ib SO /ton of cement.^Sased on control to meet the NSPS.
X
Process Option 4 - Conversion to Coal Fuel from Natural Gas
The process description using coal as a fuel in the cement kiln is
described in Volume X, page 60. The use of coal as fuel in the cement
kiln will increase the SO emissions because there is more sulfur in
the coal than in the gas. The reported emission factor is 6.8 Ib SOX/
ton of cement per percent sulfur in the coal (EPA, 1973). Therefore,
for a 3.5% sulfur coal, emissions are estimated at 23.8 Ib SO /ton of
cement. The total emissions from the cement kiln, due to sulrur in
both the feed materials and the fuel, are 34 Ib SO /ton of cement.
Again, if bag filters are used to control particulate emissions, the SO
emissions are reduced by 50% to 17 Ib/ton of cement (EPA, 1973). The X
emissions from the power boiler are the same as those from the base
case process, giving a total controlled SO emission of 18.9 Ib/ton of
cement, a significant 170% increase.
Summary
SO control devices are generally not used in the cement industry.
However* bag filters used for particulate control can reduce SO
x
39
-------
emissions by 50% because of the alkaline filter cake. The controlled
emission factors are shown in Tables 8 and 9 for the base case and al-
ternative processes.
Controlled emissions from the use of coal as fuel (instead of nat-
ural gas) in the long-dry kiln alternative are highest because of the
higher sulfur content of the coal. The sulfur in the feed in other
processes is lower. Emissions from the fluidized bed should be lowest
because of higher SO removal in the fluidized bed.
x
OLEFINS
Ethylene Production
Base Case Process - Ethylene Production Based on Ethane and Propane
Cracking—
The base case technology selected for the assessment of the domes-
tic olefin industry was ethane and propane (E-P) cracking. A detailed
description of the process of producing ethylene from ethane and pro-
pane is given in Volume VI, page 17.
As a basis for calculation, a feedstock containing 10 ppm sulfur
is used. During the ethylene cracking process, sulfur is produced in
the form of I^S and COS. These gases and C02 (the acid gases) are re-
moved from the compressed cracked gases by a caustic (sodium hydroxide)
scrubber (Volume VI, page 103). The liquid effluent from the caustic
scrubber is contacted with naphtha to absorb entrained hydrocarbons.
The naphtha solution is decanted and then used as a fuel. The water
effluent from the naphtha wash is neutralized with sulfuric acid, re-
sulting in the following effects:
• Sulfides, such as Na2S or NaHS, are replaced by Na2SO^. This
sulfate can be discharged from the plant as dissolved solids
in water effluents unless local conditions prohibit;
• The acid gases are regenerated and must be incinerated to
convert H^S to SOo before venting to the atmosphere;
• In the base case process, a feed sulfur concentration of 10
ppm in E-P results in an S02 exhaust of about 0.04 Ib/ton of
ethylene (Volume VI, page 43).
The only other sulfur emission from an E-P cracker occurs during
the decoking operation. The quantity of sulfur emitted is very small.
Some SO emissions are expected from the fuel used in the power
boiler. The electricity consumed is equivalent to 900 Btu/lb of ethyl-
ene. The estimated uncontrolled emissions are 9.98 Ib SO /ton of ethyl-
ene and the emissions controlled to meet the NSPS are estimated at 2.13
40
-------
TABLE 8. ESTIMATED SO EMISSION FACTORS - CEMENT INDUSTRY
Emission factor - no control
(Ib/ton of cement)
Process Process Power boiler Total
Base case:
Long kiln (natural gas) 10.2
• Suspension preheater <10.2
8.9 19.1
7.3 <17.5
Emission factor - with control
(Ib/ton of cement)
Process Power Total
5.1
< 5.1
1.9 7.0
1.6 <6.7
Control
Efficiency
%
63
62
(natural gas)
• Flash calciner <10.2 7.3
(natural gas)
• Fluidized bed < 10.2 -0.8
(natural gas)
• Coal as fuel instead 34 8.9
of gas in long kiln
<17.5 < 5.1
< 9.4
5.1
42.9 17
1.6
-0.2
1.9
< 6.7
< 4.9
18.9
62
56
-------
TABLE 9. ESTIMATED CONTROLLED SOV EMISSIONS - CEMENT PRODUCTION
X
Process
Base case:
Long kiln (natural gas)
• Suspension preheater
(natural gas)
• Flash calciner
(natural gas)
• Fluidized bed
(natural gas)
• Coal as fuel instead of
gas in long kiln
SOjx^Emission factor
for
(Ib/ton of cement)
Process Boiler Total
5.1 1.9
< 5.1 1.6 <
< 5.1 1.6 <
< 5.1? -0.2 <
7.0
6.7
6.7
4.9
17 1.9 18.9
cement production
Change in
emission factor
—
-0.3
-0.3
,-2.1
+11.9
SOX emissions
(10b Ib/yr)
1974** 1989-1974*
553 191
183
183
VL34
516
*Based on the incremental production of cement from 1974 to 1989 of 27.3 x 106 tons (Table 1)
multiplied by total SOX emission factors; this assumes no retirement of existing facilitites.
**The SOX emissions in 1974 are based on the emission factor of 7.0 Ib S02/ton of cement are
7.0 x 79 x 106 = 553 x 106 Ibs.
-------
Ib SO /ton of ethylene. The total SO emissions are then about 2.2 lb/
x x
ton.
The process and boiler emissions are summarized in Table 10. Emis-
sions from alternative processes are also included in the table.
Process Option 1 - Ethylene from the Pyrolysis of Naphtha—
Pyrolysis of naphtha already accounts for 7% of domestic ethylene
production and is the predominant technology used in Europe and Japan.
This process alternative is described in Volume VI, page 22.
A sulfur concentration of 500 ppm in the naphtha feed was used as
a basis for calculation. This is equivalent to 6.1 lb SO /ton of ethyl-
ene. Sulfur in the feed is later found in the pyrolysis gas (typically
80% of the total sulfur is found in the hydrocarbon fraction containing
four carbon molecules or less, e.g., C'^s and lighter, equivalent to
4.9 lb SO /ton of ethylene); in the pyrolysis gasoline (8% of the sul-
fur equivalent to 0.45 lb SO /ton of ethylene); and in the fuel oil
(12% of the sulfur equivalent to 0.75 lb SO /ton of ethylene).
X
Two methods of l^S removal are available: simple caustic scrub-
ging, and regenerative amine scrubbing followed by a caustic wash to
remove the final traces of sulfur and C02 . In the Petroleum Refining
Industry Report (Vol. IV) a simple caustic scrubbing system was chosen
since such a system normally is used until sulfur levels in the €4 frac-
tion of the pyrolysis gases exceed 600 ppm.
All the fuel oil produced in the olefin plant is consumed in heat-
ers, so sulfur in the fuel oil will result in an estimated uncontrolled
emission of 0.75 lb SO /ton of ethylene; these are not currently con-
trolled.
SO emissions are expected from the fuel burned in the power boiler.
The electricity consumed is equivalent to 1,100 Btu/lb of ethylene.
The estimated uncontrolled emissions are 12.2 lb SO /ton of ethylene
and the emissions controlled to meet the NSPS are estimated at 2.6 lb
SO /ton of ethylene. The total controlled SOX emissions are then 3.6
Ibfton of ethylene; an increase of 64% over the base case.
Process Option 2 - Ethylene From the Pyrolysis of Gas-Oil —
Several plants now being constructed will use gas-oil as feed.
The design of such plants is well established at the commercial level
and the practice is clearly going to become common as ethylene produc-
ers move to assure themselves of some flexibility in their choice of
feedstock. A process description for ethylene production based on gas-
oil is given in Volume VI, page 27.
A sulfur concentration of 2,000 ppm in the feedstock (equivalent
to 32.2 lb S02/ton of ethylene) was used as the basis for calculation.
43
-------
TABLE 10. SULFUR DISTRIBUTION AND ESTIMATED S02 EMISSION FACTORS
OLEFIN INDUSTRY
(LB S02/ TON ETHYLENE)
Base case
Ethane-Propane Naphtha Gas oil
Feed* 0.03 6.1 32.2
Distribution
Acid gas** 0.03 4.9 8.7
Fuel oil — 0.75 21.0
Gasoline — 0.45 2.5
Total 0.03 6.1 32.2
Emissions (uncontrolled)
Acid gas 0.03 4.9 8.7
Heater exhaust*** — 0.75 8.82
Total process 0.03 5.65 17.52
Power boiler 9.98 12.2 16.64
Total 10.0 17.9 34.2
Emissions (controlled)
Acid gas removal
exhuaust
Heater exhaust***
Total process
Power boiler
Total
Control efficiency, %
0.03
—
0.03
2.13
2.2
78
0.26
0.75
1.01
2.6
3.6
80
0.39
8.82
9.21
3.54
12.8
63
*Feed does not include fuel for power boiler.
**Before acid gas recovery ,(sulfur is present as H2S and COS, but
sulfur weight is calculated on S02 basis.)
*** From combustion of fuel oil - 100% of the fuel oil produced is
consumed in the naphtha process and 42% of the fuel oil produced
is consumed in the gas oil process. These emissions are normally
not controlled.
44
-------
The S02 emission problems and control methods in this alternative are
identical to those in the ethylene from the pyrolysis of naphtha alter-
native. The uncontrolled and controlled emissions are shown in Table
10.
As in the base case process, the gas-oil cracker supplies its own
fuel needs. This is accomplished by a recycling of all the residue gas
and 42% of the fuel oil produced. Thus, estimated uncontrolled emis-
sions from the heaters are 8.82 Ib SO /ton of ethylene as shown in
Table 10. x
Additional SO emissions are expected from the fuel burned in the
power boiler. The electricity consumed is equivalent to 1,500 Btu/lb
of ethylene (or 3 million Btu/ton ethylene). The estimated uncontrolled
emissions are 16.6 Ib SO /ton of ethylene and the emissions controlled
to meet the NSPS are estimated at 3.54 Ib SO /ton of ethylene. The
total controlled emissions are 12.8 Ib/ton or ethylene, a 480% increase
over the base case, largely due to heater exhaust emissions.
Long-Term Process Options
The more active development programs in the area of olefin tech-
nologies which were not analyzed in depth in the original study include:
Cracking technology, such as
• Coil cracking of vacuum gas oil,
• Hydropyrolysis,
• Autothermic pyrolysis, and
• Fluid bed cracking, as well as
Coal-based technology, such as
• Plasma arc pyrolysis, and
• Clean coke process.
Since most of these advanced technologies are being developed and
commercialized during a period when environmental regulations are in
effect, the developers recognize the need to comply with existing en-
vironmental codes and are taking appropriate measures while developing
the process. Sulfur is an even more significant problem for these
advanced technologies than for the existing technologies, because of
the nature and sulfur content of the proposed feedstocks. However, for
all, the gaseous sulfur is in the form of hydrogen sulfide, for which
an abundance of control technology is available, although some of this
technology may require modifications to be effective. For example,
Union Carbide has had to do this to reduce the problem of butadiene
45
-------
polymerization in amine scrubbing systems. Again, the fuel oils and
pitch produced as byproducts will present internal use and marketing
problems if steps are not taken to reduce their sulfur contents. How-
ever, the problems of sulfur content in the byproducts are generally
recognized by the developers. Thus, to be acceptable, the commercial
versions of the processes must incorporate techniques for coping with
this problem.
Summary
The emission factors for the base case process and alternative
processes in the olefin industry are summarized in Table 10. The un-
controlled emissions from the alternative processes are significantly
higher than those from the base case process. The higher emissions are
mainly due to the higher sulfur content in the feedstocks (naphtha and
gas oil) and partly due to increased consumption of electricity. The
major fraction of the emissions is controlled by add-on control tech-
nology. The control efficiency varies from 60 to 80%. The estimated
SO emissions after control from the olefin industry are summarized
inXTable 11. Obviously, with the very high growth rate anticipated by
this industry (8%/yr) , careful attention will have to be given to all
forms of potential discharges, including sulfur, and to effective and
economical control. As shown in Table 11, use of the heavier gas-oil
feedstocks will very dramatically increase the controlled SO emissions.
X
AMMONIA
Base Case Process - Ammonia Production Based on Natural Gas
Ammonia is made by the reaction of nitrogen with hydrogen. All
processes manufacturing ammonia utilize air as the source of nitrogen.
Natural gas is generally used as the source of hydrogen. The four maj-
or operations in manufacturing ammonia are: gas preparation, carbon
monoxide conversion, gas purification, and ammonia synthesis. A de-
tailed description of the process is given in Volume VII, page 25.
There are no SO emissions from the process. The emissions from
a coal-fired power boiler are estimated at 2.6 Ib SO /ton of ammonia
with no control, and 0.6 Ib SO /ton of ammonia based on control to meet
the NSPS. The emissions are based on electricity consumption of 45.5
kWh/ton of ammonia (Volume VII, page 29).
Process Option 1 - Ammonia Production Based on Coal Gasification
Using coal as a feedstock for ammonia production involves freeing
the hydrogen that is present in the fuel, and reacting the carbon in
the fuel with water vapor to release more hydrogen. A detailed process
description is given in Volume VII, page 37, for a hypothetical plant
in Southern Illinois using coal with 4.33% sulfur.
46
-------
TABLE 11. ESTIMATED CONTROLLED SOY EMISSIONS - OLEFINS INDUSTRY
Process
Base case:
E-P process
• Naphtha process
• Gas-oil process
SOX Emission factor for olefin production
(Ib/ton ethylene) Change in
Process Power boiler Total emission factor
0.03 2.13 2.2
1.01 2.6 3.6 +1.4
9.21 3.54 12.8 +10.6
SOV Emissions
(106 Ib/yr)
1974 1989-1974*
28.6** 62
102
361
*Based on incremental production from 1974-1989 of 28.2 million tons (Table 1) multiplied by
total SOX emission factor. This assumes no retirement of facilities existing in 1974.
**Estimated 1974 emissions, based on the total emission factor of 2.2 Ib S0x/ton of ethylene,
are 2.2 x 13 x 106 = 28.6 x 105 Ib.
-------
o
The effluent stream from the CO shift-conversion step contains hy-
drogen sulfide, carbonyl sulfide, etc. These gases must be removed for
process reasons, and a number of different acid gas removal systems may
be used. The acid gas may be removed in a Rectisol process (Volume VII,
page 42) followed by a Glaus conversion plant.
Coal consumption is 1.57 tons per ton of ammonia (Volume VII, page
45). The uncontrolled emissions, based on 4.33% sulfur in Illinois
coal, are 136 Ib S/ton of ammonia. The controlled emissions from a
tail gas cleanup system in the Glaus unit are estimated at 0.4 Ib SO /
ton of ammonia (Volume VII, page 61). x
The estimated emissions from the power boiler are 9.4 Ib SO /ton
of ammonia with no control, and 2.0 Ib SO /ton of ammonia, basedxon
control to meet the NSPS, giving a total controlled emission of 2.4 Ib
SO /ton, which is 300% more than from the base case process.
X
Process Option 2 - Production of Ammonia from Heavy Fuel Oil
The production of ammonia from heavy fuel oil includes reacting
fuel oil with oxygen in the presence of steam at a temperature of 2,000
2,500 F to produce syngas, followed by shift reaction, heat recovery,
acid gas removal, final gas purification, compression, and synthesis.
An air separation plant is required to produce oxygen and nitrogen. A
detailed description of the process is given in Volume VII, page 67.
The air pollution problems in this alternative are similar to those
in the production of ammonia from coal. However, the uncontrolled emis-
sions are about two-thirds of those from an alternative process based
on coal (Volume VII, page 78). The estimated uncontrolled emissions
are 92 Ib S/ton of ammonia. The controlled emissions from the tail gas
system in the Glaus plant are 0.3 Ib SO /ton of ammonia.
The estimated emissions from the power boiler are 6.0 Ib SO /ton
of ammonia with no control, and 1.3 Ib SO /ton of ammonia, basedxon
control to meet the NSPS. Thus, the totaJ SO discharges are 1.6 Ib/ton
ammonia or 67% more than from the base case process.
Summary
The SO emissions from the base case process and process alterna-
tives are summarized in Table 12. The uncontrolled emissions are sig-
nificantly higher in the alternative process because of the increase in
the sulfur content of the feedstock and increased consumption of elec-
tricity. The sulfur emissions may be controlled by both Glaus plant and
FGD systems. The controlled sulfur emissions from the alternative pro-
cesses are two to four times those from the base case process, but re-
main relatively small in comparison to other national problems. The,
total SO emissions for the industry in 1989 would be only 13.2 x 10
Ib, using the current process, or 36.2 Ib, using the base process, plus
48
-------
TABLE 12. ESTIMATED CONTROLLED SOX EMISSIONS - AMMONIA INDUSTRY
Process
Ammonia production
based on
Base case:
Natural gas
• Coal gasification
• Heavy fuel oil
SOX emission factor for ammonia production
(Ib/ton ammonia) Change in
Process Power boiler Total emission factor
0 0.6 0.6
0.4 2.0 2.4 +1.8
0.3 1.3 1.6 +1.0
S0y Emissions
(10b Ib/yr)
1974 1989-1974*
5.5** 7.7
30.7
20.5
*Based on increment in production from 1974-1989 — 12.8 x 106 ton/yr.
**Estimated 1974 emissions, based on the total emission factor of 0.6 Ib S0x/ton of ammonia,
are 0.6 x 9.2 x 106 = 5.5 x 106 Ib/yr.
-------
the ammonia from coal process for all future expansion ("worst case").
Although this is small on a national basis when compared to current or
anticipated coal usage and SO generation for power utilities, there
may nevertheless be significant regional impacts because of the region-
al character of the ammonia industry.
ALUMINA AND ALUMINUM
Alumina Production
Base Case Process - Bayer Process for Producing Alumina—
The Bayer process for producing alumina is based on imported baux-
ite. The process includes digestion of ground bauxite, removal of im-
purities, precipitation of aluminum trihydrate, treatment of spent li-
quor to regenerate the caustic, and calcination of aluminum trihydrate
to produce pot feed alumina. A detailed description of the process is
given in Volume VIII, page 106, based on natural gas use in calcining.
There are no SO emissions from the process using natural gas.
Estimated SO emissions from the power boiler (based on electricity
consumption of 275 kWh/ton of alumina) are 16 Ib SO /ton of alumina, if
not controlled, and 3.3 Ib SO /ton of alumina, if controlled to meet
the NSPS. X
Process Option 1 - Hydrochloric Acid Ion Exchange Process—
This process includes dehydration of the raw clay, leaching with
hydrochloric acid, separation of residue, purification of the solution
by amine ion exchange, crystallization of aluminum chloride and decom-
position and calcination to obtain alumina. A detailed description of
the process is given in Volume VIII, page 22. No commercial plant em-
ploying this process has ever been built (Volume VIII, page 27); thus,
data for emissions are best estimates, based on natural gas for cal-
cining.
As in the base case process, SO emissions are not present in this
process. Estimated SO emissions from the power boiler are 8 Ib SO /ton
of alumina with no control and 1.7 Ib SO /ton of alumina, if controlled
to meet the NSPS — a 48% reduction.
Process Option 2 - Nitric Acid Ion Exchange Process—
This process includes calcining the kaolin clay, leaching the cal-
cined clay with hot nitric acid, separating the clay insolubles, remov-
ing the iron and other impurities, recovering the alumina by hydrolysis,
recovering the nitric acid, and calcining to obtain alumina.
In this process, coal and oil are used as fuel. SO is present in
several waste gas streams (Volume VIII, page 38) and in ihie flue gas
from the combustion processes. Most of the coal is used for calcination,
50
-------
Part of the SO will be removed in the alkaline dust present in the
kiln. It is expected that SO emissions may be comparable to those
from the coal combustion in tne cement kiln. If coal containing 3.5%
sulfur is used in the cement kiln, the SO emissions will be 23.8 Ib
SO , based on the emission factor reported* in "Compilation of Air Pol-
lution Emission Factors" (EPA, 1973). The fuel consumption in the ce-
ment kiln is about 4.6 x 10 Btu/ton of cement (Volume X, page 46).
The coal consumption in the nitric acid process is 24 x 10 Btu/ton of
alumina. Therefore, the estimated uncontrolled SO emissions are 120 Ib
SO /ton of alumina. x
x
In the operation of a cement kiln, about 50% of the SO emissions
are removed in the particulate collection device. Comparable collect-
ion efficiency may be expected in this alternative. The estimated emis-
sions from the particulate collection device will be 60 Ib SO /ton of
alumina.
The emissions from the power boiler are comparable to those in the
hydrochloric acid ion-exchange process alternative, about 8 Ib SO /ton
of alumina, if not controlled, and 1.7 Ib SO /ton of alumina, if con-
trolled to meet the NSPS. Consequently, at §1.7 Ib SO /ton, this route
will be a significantly larger contributor of SO than the conventional
bauxite process, largely because of coal use in fhese calculations.
Process Option 3 - Toth Alumina Process—
This process involves the chlorination of alumina-containing raw
materials in the presence of carbon to produce aluminum chloride vapor
and other volatile chlorides. These products are subsequently purified
to eliminate other metal chlorides and then oxidized to alumina and
chlorine for recycle. The details of the process are given in Volume
VIII, page 39.
Coal is the only source of sulfur in this process. Coal is used
in kilns, chlorinator, etc. The coal consumption in the process is
equivalent to 8.45 x 10 Btu/ton of alumina. If all the sulfur from
the coal (containing 3.5% sulfur) appears in the flue gas, it will re-
sult in an estimated uncontrolled emission of 49 Ib SO /ton of alumina.
x
The major sulfur source is the chlorinator. After chlorine is re-
moved, the gas contains carbon monoxide, carbon dioxide, hydrogen chlo-
ride, chlorine, and sulfur compounds, such as H~S, COS, etc. This gas
stream is burned in a CO boiler and then caustic scrubbed to remove SO .
The cost of SO control is shown in Volume VIII, page 46. If 80% of x
the SO is removed, the estimated emissions will be 10 Ib SO /ton of
x x
alumina.
The electricity consumption in this alternative is 333 kWh/ton of
alumina. Estimated emissions from the power boiler are 19 Ib SO /ton
of alumina, based on no control, and 4.2 Ib SO /ton of alumina, D"ased
on control to meet the NSPS. Combining all sources, the total control-
led SO emissions are 14.2 Ib/ton.
X
51
-------
Aluminum Production
Base Case Process - Hall-Heroult Process—
This process involves reduction of alumina to aluminum, using elec-
trolytic cells. The existing plants use Soderberg electrodes and the
new plants use prebaked electrodes which consume less energy. A de-
tailed description of the process is given in Volume VIII, page 52.
Electrolytic cell operation produces particulate, sulfur, and hydro-
carbon emissions, as well as fluoride emissions. The amount of emissions
depend upon the type of cell used.
Prebake Cells and Soderberg Cells—
The electrolytic reduction of aluminum produces a CO exhaust at
the anode of the cell. As the exhaust leaves the cell, it entrains
particulates including fluoride salts. The exhaust also contains
noxious gases such as HF and traces of I^S.
In a prebake plant the carbon anode, which is consumed as a part
of the reaction, is formed in a baking furnace. The manufacturing
process is similar to coke-making in that a paste made of pitch and coal
is devolatilized forming a solid carbon anode. This process emits large
amounts of hydrocarbons, sulfur compounds, and particulates.
Plants which use Soderberg cells do not require anode furnaces
because the anode is formed from a coke-based paste within the elec-
trolytic cell itself. In this case, the particulate, sulfur and hydro-
carbon emissions, common to the anode furnace of a prebake cell, will
be emitted in the electrolytic cell of the Soderberg process instead.
SOX Emissions--
Total SOX emissions are estimated to be 60 Ib/ton of aluminum, but
of course dependent upon the sulfur content of the pitch and coke used
to manufacture the anodes (Volume VIII, page 134) and cell type. Based
on 85% control efficiency using scrubbers, controlled emissions are esti-
mated to be 9 Ib SO,,/ton of aluminum.
A
When current aluminum technology is used, major SOX emissions are
from the power boiler used to generate electricity and are estimated at
900 Ib S0x/ton of aluminum, with no control, and 200 Ib S0x/ton of aluminum
based on control at the power plant to meet the NSPS. The newer plants
consume less electrical energy (12,000 kWh/ton of aluminum for the newer
plants versus 15,600 kWh/ton of aluminum for older plants) and therefore
the emissions from the power boiler are reduced to an estimated value
of 700 Ib S0x/ton of aluminum based on no control and 150 Ib S0x/ton of
aluminum based on control to meet the NSPS.
52
-------
Process Option 1 - Alcoa Chloride Process —
This process starts with pot feed alumina from the Bayer process.
The alumina is converted into aluminum chloride by chlorination in the
presence of carbon to form volatile aluminum chloride. This, in turn,
is purified and fed to the electrolytic cells to produce molten alumi-
num. Calculations below are Arthur D. Little estimates based on limited
published data.
Energy consumed by the process includes No. 6 fuel oil equivalent
to 24.8 x 106 Btu/ton of aluminum (Volume VIII, page 69). The estimated
emissions are 41 Ib S0x/ton of aluminum based on 1% sulfur in the
oil burned. The burned off gases from the coker must be treated to re-
move sulfur emissions. Because of the extremely high sulfur loadings
expected, the stack scrubbing process used should be regenerative. Most
of the scrubbing processes appropriate for this type of control were de-
veloped for utility boilers. Such systems include a scrubbing system
(for gas-liquid contact) and an alkali handling system (for regeneration
of caustic, for example). These systems have been proven effective on
pilot-scale systems, and several full-scale systems are now in operat-
ion.
The SO control costs are shown in Volume VIII, page 67. The es-
timated controlled emissions are 8 Ib SO /ton of aluminum based on 80%
efficiency. x
Based on the electricity consumption of 10,500 kWh/ton of aluminum
(Volume VIII, page 69), emissions from the power boiler are estimated
at 610 Ib SO /ton of aluminum, based on no control, and 130 Ib SO ,
based on control to meet the NSPS. The combined controlled emissions
are then 138 Ib SO /ton of aluminum, a slight improvement, achieved by
reduced electricity consumption.
Process Option 2 - Refractory Hard Metal Cathodes Process—
This process is based on Bayer alumina and uses titanium diboride
cathodes instead of conventional carbon cathodes. The cathodes are
assumed to be retrofitted in existing large cells to increase product-
ion and reduce energy consumption (Volume VIII, page 74). A detailed
process description is given in Volume VIII, page 68.
The emission loadings and control methods in this alternative are
the same as in the base case process.
The electricity consumed in the process is 12,480 kWh/ton of alu-
minum (Volume VIII, page 76). Estimated emissions from the power boil-
er are 720 Ib SO /ton of aluminum, based on no control, and 160 Ib SO /
ton of aluminum Eased on control to meet the NSPS. Total SO emissions
are thus reduced by about 20%. x
Process Option 3 - Combination of the Clay Chlorination Process and
the Alcoa Chloride'—
The details of the combined process are given in Volume VIII,
53
-------
page 79. Since intermediate alumina production is eliminated, there is
some reduction in emissions. The estimated emissions from the Toth pro-
cess include 49 Ib SO /ton of alumina. For aluminum production, 1.93
tons of alumina/ton or aluminum are required (Volume VIII, pages 50 and
81). Therefore, emissions are estimated to be 95 Ib SO /ton of alumi-
num. The controlled emissions are estimated at 19 Ib s6 /ton of alumi-
num.
The electricity consumed in the process is 10,637 kWh/ton of alu-
minum (Volume VIII, page 81), resulting in an estimated emissions of
620 Ib SO /ton of aluminum, based on no control, and 130 Ib of SO /ton
of aluminum based on control to meet the NSPS. The total controlled
emissions would then be approximately 149 Ib SO /ton, which is not sig-
nificantly different from other anticipated technology.
Summary
The estimated SO emission factors for the alumina and aluminum
•y
industry are summarized in Table 13.
The major difference in the SO emissions in alumina production
results from the use of coal in the nitric acid ion exchange and Toth
processes. Natural gas is assumed to be used as fuel in the remaining
alumina processes. Control methods include removal of SO in the bag
filters (because of the alkaline nature of the particulate cake) and
in wet scrubbers.
In the aluminum industry, the majority of the emissions come from
the power boiler because of the consumption of large quantities of
electricity. These emissions which are proportional to energy demand
may be controlled by flue gas desulfurization and coal cleaning methods.
The SO emissions in the alumina and aluminum industry are summar-
ized in Table 14. The process alternatives in aluminum production are
aimed at reducing the consumption of electricity and therefore do re-
duce power boiler emissions concurrently.
SO emissions from the aluminum production are significantly high-
er (about 40 times) than those from the alumina production (Table 14).
While a significant portion of aluminum manufacturing now relies on
hydroelectric power, we expect that much of the incremental aluminum
capacity to be installed in the next 15 years will be based on fossil
fuels and, to a lesser extent, on nuclear power. Thus we believe the
SO emissions calculated here are not unrealistic if the alumina/alumi-
num processes discussed are actually implemented and U.S. capacity
growth projections are realized.
54
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TABLE 13- ESTIMATED CONTROLLED SOX EMISSION FACTORS - ALUMINA AND ALUMINUM INDUSTRY
Process
Emission factor - no control Emission factor - with control
(Ib/ton product) (Ib/ton product) Control
Process Power boiler Total Process Power boiler Total efficiency (%)
Alumina
Base case:
Bayer 0
• Hydrochloric acid 0
ion exchange
• Nitric acid 120
ion exchange
• Clay chlorination 49
(Toth)
Aluminum
Base case:
Hall-Heroult 60
(current practice)
16
8
8
19
16
8
128
68
0
0
60
10
3.3
1.7
1.7
4.2
900
960
200
3.3
1.7
61.7
14.2
209
79
79
52
79
78
• Hall-Heroult (new)
• Alcoa chloride
• Refractory hard metal
cathode
• Combination of clay
chlorination (Toth)
and Aloca chloride
60
41
60
95
700
610
720
620
760
651
780
715
0,9
8
9
19
150
130
160
130
159
138
169
149
79
79
78
79
-------
TABLE 14. ESTIMATED CONTROLLED SOX EMISSIONS - ALUMINA AND ALUMINUM INDUSTRY
Controlled SOY emission factor SOV emissions
(Ib/ton product)
Process Process Power boiler
Product : Alumina
Base case:
Bayer
• Hydrochloric acid ion exchange
• Nitric acid ion exchange
• Clay chlorination
„ (Toth alumina)
[V
Product : Aluminum
Base case:
Hall-Heroult (current practice)
• Hall-Heroult (new)
• Alcoa chloride
• Refractory hard metal cathode
Base case:
Bayer and Hall-Heroult (c.p.)
• Toth alumina and Alcoa chloride
0
0
60
10
9
9
8
9
9
19
3.3
1.7
1.7
4.2
200
150
130
160
206***
130
Change in (10 6 Ib/yr)
Total emission factor 1974 1989-1974*
3.3
1.7
61.7
14.2
209
159
138
169
215
149
25.4** 35.5
-1.6 — 18.3
+58.4 — 663
+10.9 -- 153
1,045 1,463
-50 — 1,113
-71 — 966
-40 — 1,183
1,070** 1,505
-66 — 1,043
(continued)
-------
TABLE 14.(continued)
*
Based on multiplying emission factor by increments in production from 1974 to 1989 of 10.75
million tons alumina/year and 7.0 million aluminum tons. This assumes no retirement of
1974 facilities.
**
Estimated 1974 emissions, based on the emission factor of 3.3 Ib S0x/ton of alumina, are
3.3 x 7.7 x 10° = 25.4 x 10° Ib SO from alumina production; and, based on the emission
factor of 209 Ib SO /ton of aluminum, are 209 x 5 x 106 = 1,045 x 106 Ib SOX from aluminum
production; resulting in a total of 1,070 x 10" Ib SOX from alumina and aluminum.
***
Bayer process, plus Hall-Heroult process (current practice), is used for comparative analysis
based on 1.93 tons alumina per ton aluminum (Volume VIII, P. 116).
01 C.P. - current (1974) practice
-------
PULP AND PAPER
Chemical Pulp
Base Case Process - Kraft Pulping—
The base case process selected for chemical pulp was the Kraft
process, which includes cooking of wood chips at elevated temperature
and pressure in a digester. When cooking is completed, the contents of
the digester are forced into the blow tank where the spent cooking li-
quor is drained. After unreacted chunks of wood are removed, the pulp
is washed, bleached, pressed, and dried into the finished product. Fur-
ther details are found in Volume 5, page 55.
Recovery of both the inorganic cooking chemicals and the heat con-
tent of the spent liquor, which is separated from the cooked pulp in
the blow tank, is economical. Recovery is accomplished by first con-
centrating (in an evaporator) the liquor to a level that will support
combustion and then feeding it to a furnace (recovery boiler) where
heat recovery takes place. This is followed by chemical recovery in a
smelt dissolving tank.
The characteristic odor of the Kraft mill is partially caused by
hydrogen sulfide. The major source is the direct contact evaporator in
which the sodium sulfide in the black liquor reacts with the carbon di-
oxide in the furnace exhaust. In addition, the Kraft-process odor also
results from an assortment of organic sulfur compounds, all of which
have extremely low odor thresholds. These compounds are emitted from
many points within a mill; however, the main sources are the digester/
blow tank systems and the direct contact evaporator.
The lime kiln can also be a potential source as a similar reaction
occurs involving residual sodium sulfide in the lime mud. Lesser amounts
of hydrogen sulfide are emitted with the non-condensible off-gases from
the digesters and multiple-effect evaporators.
Sulfur dioxide emissions result mainly from oxidation of reduced
sulfur compounds in the recovery furnace. Sulfur dioxide may also be
present in the power boiler effluent gas, depending on the sulfur con-
tent of the fuel used.
The uncontrolled total reduced sulfur (TRS) emissions from the
Kraft process are shown in Table 15. The emissions are expressed as
equivalent weights of sulfur. The EPA is planning to establish air
pollution emission standards for new Kraft pulp mills with proposed
standards shown in Table 15. The control method for eliminating re-
duced sulfur compounds (TRS) is oxidation to SO . The uncontrolled TRS
emissions from the various process steps are 24 Ib TRS/ton of pulp
(Table 15) and will result in emissions of 48 Ib of SOX (as S02) per
ton of pulp.
58
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TABLE 15 UNCONTROLLED EMISSIONS OF TRS AND PROPOSED EMISSION
STANDARDS FOR NEW KRAFT PULP MILLS
Uncontrolled
emissions of TRS
Proposed standard for TRS
(Ib/ton of pulp*) (ppm) (Ib/ton of pulp)*
Recovery boiler
Lime kiln
Smelt tank
*****
Brown stock washer
*****
Black liquor oxidation
******
Condensate stripping
******
Digester
15
Trace
0.1
1.0
N.A.
N.A.
8
**
5
***
5^
*** ****
5
5
5
5
5
0.15
0.025
****
0.025
0.01
0.01
0.01
0.01
Multiple ejfg
evaporator
Bleaching
Lime slaker
TOTAL
N.A.
Negligible
Trace
•>. 24
5 0.01
5 0.01
Air-dried basis.
**
TRS corrected to 8% oxygen.
***
TRS corrected to 10% oxygen.
****
Fresh water will ensure compliance.
*****
Likely control method is utilization of gas stream as combustion
air in the recovery furnace.
******
Likely control method is utilization of gas stream as combustion
air in the lime kiln.
59
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Combination boilers (bark and oil, or bark and coal) or bark boil-
ers are used as on-site power boilers in the pulp and paper industry.
The discharge from a bark boiler consists of gaseous products of com-
bustion containing negligible sulfur compounds. The combination boil-
er (coal and bark) will have SO emissions in proportion to the con-
sumption of coal and the sulfur content of the-coal. The estimated
emissions based on the consumption of 1.4 x 10 Btu fossil fuel (con-
taining 3.5% sulfur in coal) per ton of pulp are 7.8 Ib SO /ton of pulp
from the boiler. If these emissions are controlled, the estimated con-
trolled emissions will be 1.7 Ib SO /ton of pulp.
x
The energy credits in the Kraft process include 140 kWh/ton of
pulp (Volume V, page 57). Thus, the estimated reduction in emissions
at the power boiler are 8.1 Ib SO /ton of pulp, with no control, and
1.8 Ib SO /ton of pulp, based on §0 controlled to meet the NSPS.
Therefore* the net estimated reduction in emissions from the above two
power boilers is 0.3 Ib SO /ton of pulp, with no control, and 0.1 Ib/
ton of pulp, based on control to meet the NSPS. Total SO controlled
emissions are estimated at 47.9 Ib/ton.
Process Option 1 - Alkaline-Oxygen Pulping—
The alkaline-oxygen (A-0) pulping process is receiving industry
interest because of its potential for a non-sulfur cooking step, which
would eliminate the air pollution due to sulfur compounds. The steps
in the A-0 process include an alkaline treatment to soften the wood
chips, mechanical disintegration, and treatment with oxygen under al-
kaline conditions to remove most of the lignin. This is followed by
the last three stages of the conventional multistage bleaching sequence:
chlorine dioxide, caustic extraction, and(chlorine dioxide). A detailed
description of the process is given in Volume V, page 84.
Because sulfur is not used in the process, chemicals containing
sulfur are not present in the air emissions. However, SO may be pres-
ent in the air emissions from the lime kiln and the powerxboiler because
of the sulfur present in the fuel. The emission factor for fuel com-
bustion in lime kilns is not available. It is expected that a major
fraction of the SO will be absorbed by the alkali dust in the kiln
and by the air pollution control device, provided wet scrubbers or bag
filters are used. The estimated emissions from the on-site power boil-
er are 18.3 Ib SO /ton of pulp and the estimated controlled emissions
are 4.0 Ib SO /ton of pulp. The emissions are based on consumption of
coal containing 3.5% sulfur at a rate equivalent to 3.3 x 106 Btu/ton
of pulp. The energy credits in the A-0 process include 50 kWh/ton of
pulp (Volume V, page 90). Thus, the estimated reduction in emissions
at the power boiler is 2.9 Ib S0x/ton of pulp and the estimated re-
duction in the controlled emissions is 0.63 Ib SO /ton of pulp.
X r r
The net total emissions from the A-0 process are 15.4 Ib SO /ton
of pulp, with no control, and the net total controlled emissionsxare
3.37 Ib SO /ton of pulp — a very significant improvement over the con-
ventional Kraft process.
60
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Process Option 2 - Rapson Effluent-Free Kraft Process—
A number of changes in the base case Kraft process have been made
to eliminate effluents in the Rapson process. These changes are des-
cribed in detail in Volume V, page 95, and include closing the water
cycle, use of chlorine dioxide rather than €!„, countercurrent washing,
etc.
The air emissions from the process are not affected by the above
changes and the emissions are 24 Ib TRS/ton of pulp (Volume V, page 104).
The emissions from the on-site power boiler are less because of reduced
consumption of purchased fuel (coal). The total energy consumed in the
process, excluding that required for the lime burning, is 0.7 x 10 Btu/
ton of pulp (Volume V, page 101). The estimated emissions are 3.88 Ib
SO /ton of pulp with no control, and the estimated controlled emissions
are 0.84 Ib SO /ton of pulp. Electricity from the on-site power boiler
is sufficient tor the process requirements in this alternative.
Newsprint Pulp
Base Case Process - Refiner Mechanical Pulping (RMP) Process—
RMP is a mechanical pulping process that is an improvement over
the conventional groundwood process. Wood chips, sawdust, and shavings
from sawmills or plywood mills can be used as raw materials for the RMP
process, but such materials cannot be used as raw materials for the
groundwood process. The wood particles are reduced to fibers in a
pressurized disc refiner which consists of two circular metal plates
that generally rotate in opposite directions. The RMP pulp (80%), to-
gether with Kraft pulp (20%), is used in newsprint paper production. A
detailed description of the RMP process is given in Volume V, page 60.
There are no emissions containing sulfur compounds from the RMP
process, except those from the power boiler. The purchased electricity
is 1,475 kWh/ton of pulp. Therefore, the estimated emissions from the
power boiler are 85.6 Ib SO /ton of pulp, with no control, and the es-
timated controlled emissions are 18.6 Ib SO /ton of pulp. Of course,
if hydroelectric power is used, no SO emissions would occur.
X
The newsprint pulp consists of 80% RMP pulp and 20% Kraft pulp
(Volume V, page 112). Therefore, the estimated uncontrolled emissions
are 4.8 Ib TRS/ton of newsprint pulp from the process and 68.4 Ib SO /
ton of newsprint pulp from the on-site and utility power boilers. Tn"e
estimated controlled emissions are 9.6 Ib SO /ton of newsprint pulp
(TRS converted to SO ) from the process and $4.9 Ib SO /ton of news-
print pulp from the power boilers for a total of 24.5 ¥b SO /ton.
Process Option 1 - Thermo-Mechanical Pulping (IMP)--•
The TMP process is similar to the base case process (RMP process),
except that the wood particles are preheated to 130 C for a short period
61
-------
and then reduced to fibers in a pressurized disc refiner. A detailed
process description is given in Volume V, page 104.
The emissions from the TMP process are identical to those from the
base case process, except that the newsprint pulp can be composed of
95% TMP pulp and 5% Kraft pulp. Therefore, the estimated uncontrolled
emissions are 1.2 Ib TRS/ton of newsprint pulp from the process and
81.3 Ib SO /ton of newsprint pulp from the on-site and utility power
boilers. The estimated controlled emissions are 2.4 Ib SO /ton of news-
print pulp from the process (TRS converted to SO ) and 17.? Ib SO /ton
of newsprint pulp from the power boilers, totaling 20.1 Ib/ton, an 18%
reduction per ton of newsprint pulp.
Process Option 2 - De-inking of Old News for Newsprint Manufacture—
The de-inking of old news for newsprint manufacture is a well-
established commercial practice and a detailed description of the process
is given in Volume V, page 113. The only emissions from the process
are those generated in the power boilers (on-site and utility). The
total energy required is 6.1 x 10 Btu/ton of newsprint pulp. There-
fore, the estimated emissions are 33.8 Ib SO /ton of newsprint pulp,
with no control, and 7.32 Ib SO /ton of newsprint pulp based on control
to meet the NSPS. X
Summary
The emission factors and total emissions for the base case pro-
cesses and alternative processes are summarized in Tables 16 and 17.
The emissions in the alkaline-oxygen pulping alternative are signifi-
cantly lowered due to elimination of compounds containing sulfur from
the process. The emissions from pulp and paper mills generally are not
controlled, except that the form of sulfur in the emissions is changed
from reduced sulfur to sulfur oxides. Newsprint based on TMP and RMP
processes results in smaller emissions than the base case process, larg-
ely because of the smaller fraction of Kraft pulp. De-inking benefits
from an absence of sulfur-containing compounds in the de-inking of old
news for newsprint manufacture.
On a national scale A-0 pulping would have the greatest impact in
reducing SO emissions.
x
GLASS
Base Case Process - Regenerative Furnace
The base case process selected was the natural gas-fired furnace
with cold charge. A detailed description of the furnace is given in
Volume XI, page 17. Operating conditions for the base case process are:
62
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TABLE 16. ESTIMATED SOX EMISSION FACTORS - PULP AND PAPER INDUSTRY
Emission factor* - no control
(lb/ton of pulp)**
Process Process Boiler Total
Base case:
Kraft pulping 48 -0.3 47.7
• Alkaline-oxygen pulping 0 15.4 15.4
• Rapson effluent-free 48 3.88 51.9
Kraft pulping
Base case:
Newsprint - RMP 9.6 68.4 78.0
i
• Newsprint - TMP 2.4 81.3 83.7
• De-inking of old 0 33.8 33.8
news for newsprint
manufacture
Emission factor* - with control Control
(lb/ton of pulp)** Efficiency
Process Boiler Total (%)
48 -0.1 47.9
0 3.37 3.4 -78
48 0.84 48.8 -6
9.6 14.9 24.5 -69
2.4 17.7 20.1 -76
0 7.3 7.3 -78
*Reported as Ib S02/ton of ADP. The uncontrolled process emissions are present as TRS compounds.
**Air-dried basis.
-------
TABLE 17 — ESTIMATED CONTROLLED S0v EMISSIONS: PULP AND PAPER INDUSTRY
X
Process
Base case:
Kraft pulping
• Alkaline-Oxygen (A-0)
Emission
(Ib/ton of pulp)*
Process Boiler Total
48
-0.1 47.9
3.37 3.4
factor
Change in
emission factor
-44.5
SOX emissions
(10°
1974
766***
lb/yr> **
1989-1974
829
58.8
pulping
Rapson effluent-free
Kraft pulping
48
0.84 48.8
+0.9
844
Base case:
***
Newsprint - RMP 9.6
• Newsprint - TMP 2.4
• De- inking of old news —
for newsprint manufacture
14.9
17.7
7.3
24.5
20.1
7.3
—
-4.4
-17.2
95.6 42
34
12
***
Air-dried basis.
Based on increment in production from 1974 to 1989: 17.3 x 10^ tons of Kraft pulp and
1.7 x 10" tons of newsprint pulp.
c
Estimated 1974 emissions, based on the total emission factor of 47.9 Ib/ton of Kraft pulp are
47.9 x 16 x 106 = 766 x 10° Ib SOX /yr from the Kraft pulp process and, based on the total
emission factor of 24.5 Ib/ton of newsprint pulp, are 24.5 x 3.9 x 106 = 95.6 x 10^ Ib S0x/yr
from the newsprint pulp process.
-------
Furnace type: - Side port, regenerative
Fuel: - Natural gas
Glass type: - Soda lime
Plant location: - East North Central
Pull rate: - 200 tons per day
Feed rate: - 240 tons per day
Efficiency: - 90%, or 180 tons per day.
The typical glass melting operation is described in detail in Vol-
ume XI, page 19. A glass-melting furnace has both particulate and gas-
eous emissions which must be controlled.
The sulfur oxide emissions arise from two sources: sulfur in the
fuel and decomposition of mineral sulfates in the glass melt. The
sulfur within the fuel (natural gas) is generally a minor source of
sulfur oxide emissions and generally results in the production of S0~.
The decomposition of mineral sulfates in the melt produces S0_. Al-
though some SO. decomposes to S0? at temperatures above 2790 F, some
will remain in the form of SO.. The emission factor for the glass fur-
nace is 3.0 Ib SO /ton of glass (Volume XI, page 27).
X
The emissions containing high concentration of SO- are expected to
increase the corrosion potential and make air pollution control more
difficult. The control techniques for SO and SO consist of contact-
ing the gases with caustic or lime to convert the gaseous emissions to
sulfate or sulfite salts of sodium or calcium. Scrubbers for this pur-
pose should utilize high-efficiency entrainment separators to avoid car-
ryover of sulfuric acid mist.
Other add-on control systems include Dry Tesisorb systems . The
Tesisorb X (chemical composition not available), which is added up-
stream of the bag filter, is capable of collecting gaseous pollutants.
The reaction products are solid inorganic particles and are removed in
the bag filter. The bag filter is operated at 200°F. The outlet SO
concentration is less than 50 ppm, equivalent to 0.7 Ib SO /ton of x
glass. x
The estimated emissions from the power boiler to generate electri-
city are 1.1 Ib SO /ton of glass with no control, and 0.24 Ib SO /ton
of glass based on control to meet the NSPS. x
Process Option 1 - Coal Gasification
Coal gasification processes include, with some variation, the fol-
lowing steps: coal handling and storage, coal preparation, gasifica-
tion, oxidant feed facilities, and gas cleaning. The gas produced from
coal gasification is used as a fuel source in the glass furnace. The
*
Marketed by Teller Environmental Systems, Worcester, Mass.
65
-------
details of the process are given In Volume XI, page 32.
When coal gasification is used to generate the gaseous fuel for
the glass melting furnace, the major environmental difference is not in
the glass-making process, but rather in the fuel-generating process.
The fuel gas produced in the coal gasifier will contain sulfur,
mainly in the form of l^S. So that excessive SC^ emissions do not oc-
cur, the sulfur must be controlled either before or after gas combus-
tion in the furnace. Two control technologies could be considered: a
sulfur-recovery process, such as the Stretford process, to remove lUS
from the fuel gas prior to burning the fuel in the furnace, or flue gas
desulfurization, such as the processes currently used on utility boil-
ers for removing SC^ from exhaust gases. The latter case is the same
as the control for direct coal firing (as discussed below).
The estimated emissions from burning of coal are 47.0 Ib S0x/ton
of glass based on no control. Thus, the total uncontrolled emissions
are 50.0 Ib S0x/ton of glass (includes 3.0 Ib S0x/ton of glass from
mineral sources). If the Stretford process (sulfur collection effi-
ciency of 90%) is used to collect sulfur compounds, the estimated
emissions from the glass furnace are 7.7 Ib S0x/ton of glass. The esti-
mated capital and operating costs for the Stretford process are given
in Volume XI, page 39.
The SO can be further removed in the wet scrubber or Tesisorb
systems. The estimated concentration of SOX in the tail gas will be
50 ppm, equivalent to 0.77 Ib S0x/ton of glass. The emission factor
is based on an estimated 10% higher gas flow rate compared to that in
the base case process.
The SOX emissions from the power boiler are comparable to those
from the base case process, and are about 1.1 Ib S0x/ton of glass with
no control, and about 0.24 Ib S0x/ton of glass based on control to meet
the NSPS. Therefore, the total SOX emissions after control are only
slightly increased to 1.01 Ib/ton.
Process Option 2 - Direct-Coal-Firing
In this option, pulverized coal is used directly in burners to
supply the energy. The details of the process are in Volume XI, page 35.
Coal is high-sulfur fuel (3.5% sulfur), so SO will be present in
the flue gas. The uncontrolled emissions in this alternative will be
comparable to those from a coal gasification process, and amount to
50 Ib S0x/ton of glass.
The emissions may be controlled in a wet scrubber. Calcium or
66
-------
sodium-based alkali may be used in the scrubber. The cost of alkali
will be significantly higher because of high concentrations of SO .
The SO concentration in the outlet gas may be reduced to about 200 ppm.
The gas flow rate in this alternative is about 10% higher than that from
the base case process. Therefore, the estimated controlled emissions
are 3.1 Ib SO /ton of glass.
X
The SO emissions from the power boiler in this alternative are
comparable to those from the power boiler in the base case process,
about 1.1 Ib SO /ton of glass with no control, and 0.24 Ib SO /ton of
glass based on control to meet the NSPS. The total then is a signifi-
cantly higher 3.3 Ib/ton.
Process Option 3 - Coal-Fired Hot Gas Generation (COHOGG)
This system generates a hot gas by separating char and volatiles,
burning the char, and then mixing the products of combustion with the
volatiles and burning them together. A pneumatic conveying system
feeds powdered coal to the pyrolyzer along with limestone or a mix of
limestone and sodium chloride. The outlet temperature of the gases
leaving the afterburner is 3,000 F. These hot gases are used in the
glass melting furnace to heat the glass batch. The details of the pro-
cess are given in Volume XI, page 48.
From one-third to one-half of the sulfur in the coal is expected
to come off in the pyrolyzer as hydrogen sulfide (H_S). The limestone,
in turn, reacts with the hydrogen sulfide, producing water and calcium
sulfide (CaS). Unreacted limestone, char, and calcium sulfide go to
the char burner, which is a fluidized-bed combustor, where the remain-
ing sulfur forms SO . There the remaining limestone from the pyrolyzer
step reacts with the SO , forming calcium sulfite which leaves the bed
along with the ash from the char.
The only difference between the coal gasification alternative and
that of heating the glass-melting furnace with a hot combustion gas is
that the sulfur control in the latter option is inherent within the
process itself and is not required as a part of the pollution control
apparatus. The gas volumes to the glass furnace are higher with the
COHOGG process because of the efficiency losses inherent in the system.
Except for the slight size difference, however, the pollution control
system for the glass melting furnace itself will be the same as for
coal gasification. The concentration of SO in the tail gas is about
the same as that in the coal gasification process with SO control
(Stretford process). However, because of the higher gas r"low rates
(25% higher compared to the gas flow rate from the coal gasification
process; see Volume XI, page 40 for details), the emission factor
with control will be about 1.0 Ib SO /ton of glass for COHOGG.
X
Some sulfates are also formed.
67
-------
The SO emissions from the power boiler in this alternative are
comparable £o those from the base case process, or about 1.1 Ib S0x/ton
of glass with no control, and about 0.24 Ib SO /ton of glass based on
control to meet the NSPS. Total controlled emissions, at 1.24 Ib/ton,
are 32% larger than the base case.
Process Option 4 - All-Electric Melting Process
Molten glass can be heated by the passage of an electric current.
Both the design and the operation of an all-electric, glass-melting
furnace differ greatly from those of the typical natural gas-fired, re-
generative furnace. The.electric furnace without its regenerative
checker structure is a much simpler design. The details of the electric
furnace are given in Volume XI, page 53.
The option to heat glass-melting furnaces electrically results in
a shift in the environmental problems irom the furnace to the electric
power generating plant. In this case, the only exhaust from the glass-
melting furnace is from the decomposition of carbonates, sulfates, ni-
trates, etc., in the glass batch. The exhaust will be almost entirely
CO with approximately 3 Ib SO /ton of glass (Volume XI, page 27).
^ X
The control system for this exhaust is identical to the one used
for the base case and for coal gasification, but the size of the system
is considerably smaller because of the greatly reduced exhaust volume.
If the SO emissions are assumed to be controlled to 200 ppm, the emis-
sions will* be reduced to 0.1 Ib SO /ton of glass.
X
The electricity consumption is increased in this alternative to
780 kWh/ton of glass. Therefore, the estimated emissions from the pow-
er boiler are 45.2 Ib SO /ton of glass, with no control, and 9.82 Ib
SO /ton of glass, based on control, to meet the NSPS. Total controlled
emissions are significantly increased, at 9.82 Ib/ton.
Process Option 5 - Batch Agglomeration/Preheating
The intent of preheating is to prereact the batch ingredients.
Batch preheating is an energy-conserving technology relating to a fur-
nace modification rather than a method of furnace heating. Hence, this
technology is applicable to all of the previously discussed methods of
heating, except for electric heating. The details of the process are
given in Volume XI, page 58.
The uncontrolled SO emissions from this process alternative are
comparable to those from the base case process, or about 3.0 Ib SO /ton
of glass. The gas flow rate is about 20% lower than that from the^Sase
case process.
The control methods used in the base case process may be used here.
If the SO emissions are controlled to a concentration of 50 ppm, the
68
-------
estimated emission rate is 0.56 Ib SO /ton of glass.
X
The SO emissions from the power boiler in this alternative are
comparable to those from the base case process, or about 1.1 Ib SO /ton
of glass, with no control, and 0.24 Ib SO /ton of glass, based on con-
trol to meet the NSPS. Thus applying preheating, even to the conven-
tional furnace, can reduce SO emissions by about 15%.
X
Summary
The emission factors and total emissions for the flat glass indus-
try are summarized in Tables 18 and 19.
The uncontrolled emissions from the base case process and process
alternative depend on the sulfur content of the fuel. Processes based
on natural gas obsiously have significantly lower emissions compared
to those from the processes based on coal, as expected.
The controlled emissions depend on the extent of control . The con-
trolled emissions range from 0.8 to 10 Ib SO /ton of glass. Also, the
SO emissions from the electric melting process alternative are the
highest because of emissions from the electric power generating site.
Preheating appears to be an attractive alternative because both energy
is saved and SO emissions are reduced.
X
COPPER
Base Case Process - Conventional Copper Smelting
Conventional smelting involves the smelting of sulfide concentrates
in the reverberatory furnace either directly or after roasting. The
mixture of molten sulfides from the reverb is converted to blister cop-
per in converters. A detailed description of this process is given in
Volume XIV, page 23. The capacity of the base case smelter is 100,000
tons of anode copper per year,
With over 30% sulfur, most copper concentrates contain more sul-
fur than copper. About 1-2% of the sulfur entering the smelter is lost
in the slag and perhaps 3-4% evolves as fugitive emissions. The remain-
ing sulfur is lost/discharged in gaseous emissions from roaster, reverb,
and converters. Typical sulfur distributions from conventional smelt-
ing are:
Source Calcine Smelting Green Charge Smelting
Roaster 20
Reverb 25 40
Converter 50 55
Slag and Fugitives _ 5 _ 5_
Total 100 100
69
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TABLE 18. ESTIMATED SOV EMISSION FACTORS - GLASS INDUSTRY
X
Emission factor* - no control Emission factor* - with control
(Ib/ton of glass) (Ib/ton of glass) Control
Process Process Power boiler Total Process Power boiler Total Efficiency
•
1.1 4.1 0.7 0.24 0.94 77
1.1 51.1 0.77 0.24 1.01 92
1.1 51.1 3.1 0.24 3.34 93
1.1 51.1 1.0 0.24 1.24 98
45.2 48.2 0.1 9.82 9.92 79
1.1 4.1 0.56 0.24 0.80 80
*Reported as Ib S0_/ton of glass.
-------
TABLE 19. ESTIMATED CONTROLLED SOY EMISSIONS - GLASS INDUSTRY
SOX emission factor for glass production
SOX emissions
(Ib/ton of glass) Change in (10b Ib/yr)
Process Process Boiler Total Emission factor 1974 1989-1974*
Base case :
Regenerative furnace** 0.7 0.24 0.94
• Coal gasification 0.77 0.24 1.01 +0.07
• Direct coal firing 3.1 0.24 3.34 +2.40
• Coal-fired hot 1.0 0.24 1.24 +0.30
gas generation
• Electric melting 0.1 9.82 9.92 +8.98
• Batch preheat with 0.56 0.24 0.80 -0.14
natural gas firing
27.3** 12.2
13.1
43.4
16.1
129
10.4
*Based on increment in production from 1974-1989 = 13 x 106 ton/yr. (see Table 1)
**Estimated 1974 emissions, based on the total emission factor of 0.94 Ib S0x/ton of glass,
are 0.94 x 29 x 106 = 27.3 x 106 Ib/yr.
-------
The estimated total uncontrolled emissions based on the 28.6% cop-
per and 33.4% sulfur in the copper sulfide concentrate are 2.31 tons of
S0_/ton of copper.
SO emissions from smelters are controlled by the New Source Per-
formance Standards (NSPS) as follows:
• Emissions from streams containing high concentrations of SO-
(converter and roaster gases) have to be controlled by tech-
nology such as sulfuric acid plants. Double absorption plants
(or equivalent) are mandatory for new sources. This combina-
tion of uncontrolled reverbs but controlled roasters and con-
verters can recover about 50-70% of the sulfur in the feed in
the form of sulfuric acid.
• New Source Performance Standards would allow the use of re-
verbs only for the smelting of "impure" concentrates (con-
centrates containing As, Sb, Bi, etc.), but reverb emissions
would not have to be treated for S0_ removal. About 30% of
the feed sulfur is emitted from the reverbs.
• Federal Ambient Air Quality Standards (AAQS's) which define
permissible ground level concentrations of S0_ have to be
met at all times by a combination of permanent controls (e.g.,
acid plants) and production curtailment. The issue — when
should production curtailment be used — has not been resolved.
The degree of permanent controls necessary to meet Ambient
Air Quality Standards varies greatly with location. The con-
trol of roaster or converter emissions is adequate for meet-
ing Ambient Air Quality Standards only in certain locations.
At present, there are three control methods in use at copper smel-
ters for reducing the sulfur dioxide concentrations in the vicinity of
a smelter: (1) the use of a tall stack to disperse dilute gas streams;
(2) the production of sulfuric acid by the contact process from con-
centrated gas streams to achieve a degree of reduction in emissions;
and (3) production curtailment.
The contact sulfuric acid process is well established for treating
SO -containing off-gases from metallurgical plants. Modern contact
acid plants require at least 4.5-5% sulfur dioxide in the feed gas to
operate autogenously (i.e., without external heat). For handling lower
concentrations of SO., an additional fuel input is required. Acid plant
size is primarily a function of the volume of gas handled. Thus, for
a constant acid output, an acid plant operating on more dilute gases is
much larger (and more expensive) than an acid plant operating on more
concentrated gases. With the currently used vanadium pentoxide cata-
lysts, the upper level of SO^ concentration in the feed gas to an acid
plant is between 7% and 9%. More concentrated gas streams require di-
lution.
72
-------
Conventional smelters are located in geographical areas where acid
markets are unavailable and where all SO^-containing gas streams are
vented to the atmosphere (after particulate control, if necessary).
Streams from the roaster and converter, handled to minimize air leakage,
contain SCL concentrations greater than 4-5%, which is adequate for
autogenous sulfuric acid manufacture—the most cost-effective control
technology for removing SO from such streams. The reverb gases are
a high-volume (up to 100,000 scfm) and low-concentration (0.5-2% SO )
stream, not amenable to autogenous sulfuric acid manufacture and have
to be discharged via tall stacks. In short, the emission sources of
SO from a controlled conventional smelter are:
x
• Reverb gas - 82,000 scfm with 0.5-2% S02
• Acid plant tail gas - 38,800 scfm with 0.2% SO
• Anode furnace gas - data not available, contains some S0_.
The above controlled emissions are equivalent to about 1,400 Ib
S0x/ton of copper, representing a 70% control efficiency.
The electricity consumed in the copper smelting varies from 347
to 441 kWh/ton of copper. The estimated uncontrolled emissions at the
power boiler are 20.0-25.6 Ib SO /ton of copper and the estimated con-
trolled emissions are 4.4-5.6 lbXSO /ton of copper.
X
Process Option 1 - Outokumpu Flash Smelting
The flash smelting alternative combines the separate roasting and
smelting operations of conventional copper extraction into one com-
bined roasting/smelting process. The major advantages of the method
are a reduction in fuel used for smelting and production of a gas stream
having a concentration of SO which is suitable for sulfuric acid manu-
facture. A detailed description of the process is given in Volume XIV,
page 41.
The concentration of SO in flash smelter gas is high, containing
up to 13% S0_. Conventional reverberatory furnace gas, on the other
hand, typically contains 0.5-2.0% SO-. The high-strength gases are
most suitable for the manufacture of sulfuric acid. The variable
strength/variable volume S0_ gas stream from converters can be mixed
with the steady stream of flash smelter gas to provide a stream high
enough in SO,, for acid manufacture. At high matte grades, a large
amount of sulfur is eliminated in the flash furnace. This improves acid
plant performance, because the volume and strength of the input stream
are more constant.
The emissions from the acid plant tail gas represent the major
source of pollutants from the Outokumpu smelter (55,000 scfm, 0.05% SO )
The sulfur loss in various process streams includes 0.07% in drying,
73
-------
1% each in smelting and converting, 0.1% in the anode furnace, and 1.2%
in slag. The total sulfur emissions to the atmosphere are 2.8% of the
sulfur in the feed (Volume XIV, page 216).
The estimated uncontrolled emissions from the copper smelter are
4,620 Ib S09/ton of copper, and the controlled emissions are 133 Ib
S0_/ton of copper.
The emissions from the power boiler are estimated at 21.1 Ib SO /
ton of copper with no control, and 4.6 Ib SO /ton of copper based onx
control to meet the NSPS. The emissions areXbased on the electricity
consumption of 366 kWh/ton of copper (Volume XIV, page 52). Obviously,
the use of flash smelting, facilitating and recovery, allows the dual
benefits of energy saving and SO reduction.
X
Process Option 2 - Noranda Process
The Noranda process combines the three operations of roasting,
smelting, and converting of copper concentrates in a single reactor.
The heat losses suffered during the transfer of concentrate from the
roaster to the reverberatory furnace, are suppressed, as well as those
occurring during the transfer of the matte from the reverberatory fur-
nace to the converter. A detailed description of the process is given
in Volume XIV, page 55.
The sulfur dioxide concentration in the reactor atmosphere is
around 23% on a dry basis. Because of air infiltration around the hood,
the gas stream entering the acid plant contains 10-13% SO-. This stream
is only interrupted 5% of the time during tapping, and can be mixed with
the off-gases of other reactors and Fierce-Smith converters. Air in-
leakage (thereby preventing atmospheric emissions) is high, but does not
affect the subsequent l^SO^ plant, because its operation is at or below
the 10-13% SO concentration. This steady, high-S02, gas-generation
level is a significant advantage over the conventional reverberatory
process.
After dry-gas cleaning, wet-gas cleaning equipment is required to
scrub out the remaining fine particulates. The gas can then be treated
in a double-contact acid plant. Total sulfur recovery is as high as
that achieved with the Outokumpu flash smelting process.
The SO emissions from the power boiler in this alternative are
the same asxin the Outokumpu flash smelter process, 21.1 Ib SO /ton of
copper, with no control, and 4.6 Ib SO /ton of copper, based on control
to meet the NSPS. X
Process Option 3 - Mitsubishi Process Alternative
The Mitsubishi process consists of three metallurgical stages,
each of which is carried out in a separate furnace. Thus, there is a
smelting furnace for concentrates, a converting furnace to oxidize iron
74
-------
in the matte and make blister copper, and a slag cleaning furnace. In-
termediate products in the molten state move continuously among the res-
pective furnaces, which are thus functionally connected with each other.
A detailed description of the Mitsubishi process is given in Volume XIV,
page 71.
On leaving any of the three furnaces, the mixed off-gases are ex-
pected to average over 10% SO when the smelting furnace is operated
with air enriched to 25% oxygen. This steady, high-SO gas generation
is a significant advantage over the conventional reveroeratory process,
as sulfur can be readily recovered as sulfuric acid. Since the molten
liquids flow continuously over very short distances, minimum air pol-
lution is generated in transfer operations, and "converter aisle losses"
typical of conventional operations are avoided. Thus, fugitive emis-
sions are expected to be lower than for conventional or for Outokumpu
and Noranda (matte) processes.
After cooling and dry cleaning in electrostatic precipitators (or
fabric filters operated above the dew point), the collected off-gases
usually require a wet cleaning stage to remove any fine particulates
and cool the gas to remove excess moisture. The cleaned gases are
then admitted to a double-contact acid plant for ^SO^ manufacture.
Total sulfur recovery is over 90%, as with all these advanced pyrometal-
lurgical processes.
The acid plant tail gas flow rate and SO concentrations in the
gas are comparable to those from the Outokumpu smelter. The emissions
from the power boiler are the same as in the Outokumpu flash smelter
process, or about 21.1 Ib SO /ton of copper, with no control, and 4.6 Ib
SO /ton of copper based on control to meet the NSPS.
Process Option 4 - The Use of Oxygen in Smelting Process Alternative
Copper smelting can be conducted with pure oxygen or by using oxy-
gen-enriched air. An increase in oxygen concentration will result in
higher process temperatures. A detailed description is given in Volume
XIV, page 82. The specific example selected for examination is Outokum-
pu flash smelting. Oxygen enrichment results in the reduction of ef-
fluent volume; however, the operating temperatures are generally in-
creased.
Use of oxygen will result in reduced effluent volumes. The total
uncontrolled SO emissions from the smelter will remain the same. If
the emissions are controlled to a constant exit concentration, the con-
trolled emissions will be reduced in direct proportion to the gas vol-
ume. The interplay between air preheat, oxygen enrichment, and fuel
use is extremely complex and is described in more detail in Volume XIV,
page 84. This report concluded that use of oxygen does not lead to any
significant energy savings in the copper sector.
75
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Process Option 5 - Metal Recovery from Slag Process Alternative
In conventional copper smelting, converter slag is recycled to the
reverb and all the slag tapped from the revert is discarded. The cop-
per contained in the discarded slag is lost. The amount of copper lost
in the slag is significant, at about 1.5 to 3% or more of the copper in
the feed materials. The processes for recovering metal from slag are
described in Volume XIV, page 89. Since there is little sulfur in the
slag, the process SO emissions are minor. The major source is the pow-
er boiler, but it is impossible to quantify these without a detailed
analysis. In the copper sector these SO emissions would be relatively
small.
Process Option 6 - The Arbiter Process Alternative
The Arbiter process is a hydrometallurgical process. A process
description is given in Volume XIV, page 95. The Arbiter process causes
little air pollution. The process is energy-intensive and uses large
quantities of electricity and steam. As reported in Volume XIV, page
104, steam consumption is 20,000 Ib/ton of copper, and electricity con-
sumption is 3,000 kWh/ton of copper. The estimated emissions for the
power plant are 284 Ib SO /ton of copper with no control, and 62 Ib SO /
ton of copper based on control to meet the NSPS. x
Summary
The emission factors and total emissions in the copper industry
are summarized in Tables 20 and 21. The uncontrolled emissions from
the pyrometallurgical processes are essentially the same. There are no
SO emissions from the Arbiter process. The emissions from the power
boiler in the Arbiter process are significantly higher than other pro-
cesses. However, the total uncontrolled emissions from the Arbiter
process are about 5% of those from other processes.
The emissions from the pyrometallurgical processes are controlled
by add-on control technology, mainly acid plants. The control efficien-
cy is only 70% in the conventional smelting process and over 90% in the
other newer technologies proposed in the options, which also offer en-
ergy advantages. Therefore, on these two bases, it can be expected
that the newer approaches will see rapid implementation as plants are
replaced or additional capacity installed.
CHLOR-ALKALI
Some process changes have little direct affect on SO emissions
and thus received little or no attention in the Industry Reports (Vo-
lumes I-XV). However, indirect SO emissions by differing electric
energy or steam requirements between base case and alternative techno-
logy may arise. Generally, such impacts are of a much smaller magni-
tude than in the industries mentioned above. Examples of such potential
changes in SO emissions, depending on the process implemented, are
found in the chlor-alkali industry and others subsequently discussed
in this report.
76
-------
TABLE 20. ESTIMATED S0x EMISSION FACTORS - PRIMARY COPPER INDUSTRY
Emission
factor* - no control
(Ib/ton of copper)
Process
Base case:
Conventional smelting
• Outokumpu flash smelting
• Noranda
• Mitsubishi
• Arbiter
j
j
Process
4,620
4,620
4,620
4,620
— »••
Power boiler
23
21
21
21
284
Total
4,643
4,641
4,641
4,641
284
Emission
factor*
(Ib/ton of
Process
1,400
133
133
133
^^
-with control
copper)
Power boiler Total
5
5
5
5
62
1,405
138
138
138
62
Control
Efficiency
7.
70
97
97
97
78
*Reported as Ib SO^/ton of anode copper.
-------
TABLE 21. ESTIMATED CONTROLLED SOV EMISSIONS - COPPER SMELTING
x
—4
00
Process
Base case:
Conventional smelting
• Outokumpu flash smelting
• Noranda process
• Mitsubishi process
• Arbiter
Controlled
(Ib/ton of
Si
Ox emission factor
anode copper)
Process Power
1,400
133
133
133
5
5
5
5
62
Change in
boiler Total Emission factor
1,405
138
138
138
62
—
-1,267
-1,267
-1,267
-1,343
SOX emissions
(10° Ib/yr)
1974 1989-1974*
2,250** 1,550
152
152
152
68
*Based on increment in production from 1974 to 1989 of 1.1 million ton/yr. (Table 1)
**Estimated 1974 emissions, based on the emission factor of 1,405 Ib S0x/ton of anode copper,
are 1,405 x 1.6 x 106 = 2,250 x 106 Ib/yr.
-------
Base Case Process - Graphite Anode Diaphragm Cell
The graphite anode diaphragm cell was selected as a basis for judg-
ing the energy and environmental effects resulting from the process
changes studied, i.e., conversion to modified anodes and conversion to
modified diaphragms, both changes being aimed at energy conservation.
Chlorine and caustic soda are produced by the electrolysis of brine.
In the diaphragm cell, chlorine is formed at the graphite anode, while
sodium ions migrate through the cell diaphragm to the cathode where a
dilute solution of NaOH is produced. A more complete description of
this process is presented in Volume XII, pages 21-25.
The electrolysis of brine is an energy-intensive process, requir-
ing about 3,274 kWh/ton of chlorine. In addition, the plant requires
7,368 Ib of low-pressure steam/ton of chlorine for caustic evaporation
and brine heating. Sulfur dioxide emissions from power generation are
estimated at 41.3 Ib SO /ton of chlorine if the NSPS for coal-fired
units is met. Without rlue gas desulfurization, emissions are estimat-
ed at 190 Ib/ton of chlorine. It was assumed (Volume XII, page 26) that
the steam would be generated with byproduct hydrogen supplemented with
natural gas. Hence, sulfur dioxide emissions from steam generation may
be assumed to be nil.
Process Option 1 - Dimensionally Stable Anode (PSA)
The dimensionally stable anode (DSA) constructed of titanium and
coated with precious metal/rare earth oxides offers numerous advantages
over the graphite anode which result in power savings of up to 20%. The
anode area and anode-cathode spacing of the DSA remains constant through
out use, thereby preventing increased voltage requirements over time.
Additional characteristics of the DSA are presented in Volume XII, pages
44-47. The DSA diaphragm cell process requires 3,151 kWh and 6,402 Ib
of steam/ton of chlorine. Steam is generated by the byproduct hydrogen
and natural gas; hence, SO emissions are assumed to be nil.
X
Sulfur Dioxide emissions from power generation are estimated at 39.7 Ib
SO /ton of chlorine, if the NSPS for coal-fired units is met and 183 Ib
-tr *
SO /ton of chlorine, if the emissions are uncontrolled, a slight improve-
ment over the base case.
Process Option 2 - Expandable DSA
Cell power consumption can be reduced further by decreasing the
gap between the anode and the cathode. With the rigid DSA, a "working"
space must be allowed to assemble the cell. The expanded DSA is con-
structed so that the electrodes can be moved inward after the cell is
assembled. This reduced spacing results in a reduction of about 325
kWh/ton of chlorine compared to the rigid DSA configuration. If emis-
sions are controlled to meet the NSPS, then this power savings reduces
79
-------
sulfur dioxide emissions to about 35.6 Ib SO /ton of chlorine from the
emissions estimated for the rigid DSA cells, a 14% reduction when com-
pared with the conventional graphite anode process. If emissions are
uncontrolled, then this power savings reduces emissions by 19 Ib/ton of
chlorine to 164 Ib SO /ton of chlorine.
x
Process Option 3 - Polymer-Modified Asbestors
By replacing the conventional asbestos diaphragm by one which is
polymer-treated and is baked into place on the cathode, power consump-
tion can be reduced because diaphragm swelling does not occur. Elec-
trical consumption may be reduced by as much as 280 kWh/ton if an extra
wide anode is used. Thus, if flue gas is treated at the power source
to meet the NSPS, then SO emissions are estimated to be 38.2 Ib/ton of
"V
chlorine, or 3.1 Ib/ton less than the emissions estimated for the rigid
DSA cells with standard diaphragms. Thus, compared to the base case,
the controlled SO emissions are reduced by 12%.
X
Process Option 4 - Polymer Membranes
Microporous Teflon-type polymer membranes which would replace the
asbestos diaphragm entirely are being developed. These would give an
energy performance equivalent to the polymer modified asbestor with
the "extra wide" anode. Hence, the controlled and uncontrolled emis-
sions would be identical to those of Process Option 3.
Process Option 5 - Ion Exchange Membranes
These membranes would separate the anode and cathode compartments
of the cell and would allow the diffusion of sodium ions to the cathode
but would not allow the diffusion of hydroxyl ions to the anode. Thus,
the ion exchange cell is capable of producing a 25 to 40% caustic so-
lution, whereas the standard cell produces a 10% caustic solution.
Energy use for a DSA with an ion exchange cell producing 40% NaOH
is 2,980 kWh and 1,466 Ib steam/ton of chlorine. Significantly less
steam is required since a rather concentrated NaOH solution is produced
directly from the cell.
Sulfur dioxide emissions from power generation are estimated to be
37.6 Ib/ton of chlorine if the NSPS for coal-fired boilers is met. If
flue gas is untreated, then emissions would be about 173 Ib/ton of chlo-
rine.
Process Option 6 - Mercury Cells
Chlorine and caustic can also be produced in a mercury cell. In a
mercury cell, brine flows through a slightly sloped trough. At the di-
mensionally stable anodes, located at the top cover of the trough, chlo-
rine is produced. A dilute sodium amalgam is produced at the cathode
(a thin layer of mercury which flows along the bottom of the trough).
80
-------
a 50% caustic solution is produced from the amalgam; and the mercury is
recycled to the cell. Energy requirements for the mercury cell include
3,714 kWh of power and 550 Ib of steam/ton of chlorine.
Sulfur dioxide emissions produced by power generation are estimat-
ed at 46.8 Ib/ton of chlorine if the NSPS for coal-fired boilers is met.
If flue gas is untreated, then emissions would be about 215 Ib/ton of
chlorine.
Summary
The emissions factor and total emissions for the base case and al-
ternative processes are presented in Table 22. The mercury cell is es-
timated to result in a 13% yearly increase from the base case because
of the relatively larger power requirements. The modified anodes and
modified diaphragm options offer a 4 to 14% yearly reduction in SO
emissions (up to 67 million Ib/hr) from the base case process. On a
national basis, these changes are small compared to those examined in
the aluminum sector which also depends, to a large extent, on electric
energy.
IRON AND STEEL
Recovery of Carbon Monoxide from BOP Vessels
Base Case Process - Complete Combustion System—
The base case process is a complete combustion system. The gases
issuing from the mouth of the furnace are collected in a hood with con-
siderable infiltration of air, burned in the hood, and cooled and cleanec
of particulates before being released to the atmosphere. A detailed
description of this system is presented in Volume III, page 18.
The combustion system consumes 14 kWh of electricity per ton of
steel; this electricity is required for the operation of the heat scrub-
ber system. Sulfur dioxide emissions from the power boiler are estimat-
ed at 0.8 Ib/ton of steel, if the emissions are uncontrolled, and 0.2
Ib/ton of steel, if the emissions are controlled to meet the NSPS.
Alternative Process - Non-Combustion BOP Off-Gas Recovery System~
In the alternative process, carbon monoxide is collected and re-
covered from the BOP off-gas. Two prominent systems, the OG process
and the IRSID-CAFL process, are quite similar and are discussed in Vol-
ume III, pages 19-22.
The off-gas (OG) process consumes about 8 kWh of electricity per
ton of steel. Energy consumptions are less than those for the combus-
tion system as a result of the lower gas volumes handled in the non-
combustion systems. Sulfur dioxide emissions from the power boiler are
estimated at 0.5 Ib/ton of steel, if the emissions are uncontrolled,
31
-------
TABLE 22. ESTIMATED CONTROLLED SOV EMISSIONS - CHLOR-ALKALI INDUSTRY
oo
ro
**
Process
Base case:
Graphite-anode^
diaphragm cell
• Dimensionally
stable anodes
• Expandable DSA
• Polymer-modified
asbestos
• Polymer membrane
• Ion exchange
memb rane
• Modern mercury
cell
Controlled SOV
emission
(Ib/ton of chlorine)
Process Power boiler Total
0 41.3
0 39.7
0 35.6
0 38.2
0 38.2
0 37.6
0 46.8
41.3
39.7
35.6
38.2
38.2
37.6
46.8
factor SOX. emission
Change in (10° Ib/yr) ^
emission factor 1974 1989-1974
**
454 491
-1.6 — 472
-5.7 — 424
-3.1 — 455
-3.1 — 455
-3.7 — 447
+5.5 — 557
Based on increment in
production from 1974 to
1989 of
*
Estimated 1974 emissions, based on the total emission
are 41.3 x 11.0 x 106 = 454 x 106 Ib.
11.9 million ton/yr. (Table 1)
factor of 41.3 Ib S0x/ton of chlorine,
-------
and 0.1 Ib/ton of steel, if the emissions are controlled to meet the
NSPS.
Blast Furnace
Base Case Process - Low Sulfur Blast Furnace Hot Metal—
The base case system is considered to include a blast furnace, cy-
clone, and venturi scrubber. The blast furnace sulfur content is com-
pletely controlled by adding limestone to form the sulfur-bearing slag
and by limiting the sulfur content of the metallurgical coke. This
process is further discussed in Volume III, page 29.
Most of the sulfur leaves the blast furnace in the liquid slag and
hot metal; the off-gases contain only a negligible portion of the sul-
fur. Hence, sulfur dioxide emissions from the process are estimated to
be nil.
Electricity consumed in the base case process is 0.25 kWh per ton
of hot metal. Estimated emissions from the power boiler are 1.5 Ib SO/
ton of hot metal if the emissions are uncontrolled, and 0.3 Ib S0x/ton
if the emissions are controlled to meet the NSPS.
Process Alternative - Blast Furnace with External Desulfurization—
Addition of an external desulfurization step is an alternative
method of controlling the sulfur content of blast furnace hot metal. Ex-
ternal desulfurization is achieved by injecting sulfur-reacting reagents
(e.g., calcium or magnesium compounds carried in an inert gas such as
nitrogen) into high-sulfur hot metal from a blast furnace. These com-
pounds form a sulfide slag that is skimmed off prior to charging the
hot metal to the BOP. Use of external desulfurization either permits
limestone and coke ratios to be reduced, or allows the sulfur content
in the coke to be increased without increasing the limestone charge to
the furnace. A detailed description of this process is given in Volume
III, page 31.
Sulfur dioxide emissions from the blast furnace off-gas are assumed
to be nil. Electricity consumption in this alternative process is the
same as the base case process, so power boiler emissions estimates are
also the same. In neither case, is the contribution significant.
Quenching of Coke
Base Case Process - Wet Quenching —
In the base case process, the hot coke is pushed from the oven into
a coke car where it is quenched with water. The steam which is produced
is vented to the atmosphere. Excess water is allowed to drain and is
often recirculated. Electricity consumed by the wet quenching process
is not estimated in the analysis presented in Volume III, but it can be
83
-------
assumed to be quite low.
Process Alternative Option - Dry Quenching—
In dry quenching of coke, the hot coke, pushed from the ovens, is
cooled in a closed system. "Inert" gases extract heat from incandescent
coke by direct contact. The heat is then recovered from the inert gas-
es in a waste heat boiler or by other techniques.
The incremental electrical requirements are estimated at 8.4 kWh/
ton of coke. Incremental emissions from the power boiler are estimated
at 0.5 Ib SO /ton of coke, if the emissions are uncontrolled, and 0.1
Ib SO /ton or coke, if the emissions are controlled to meet the NSPS.
x
In addition, if the recovered heat, estimated at 1.1 x 10 Btu/ton
of coke, is used in the plant, then an air emissions 'credit' may
be realized. This credit is estimated to be 6.1 Ib S0x/ton of coke,
if the emissions from the power boiler remain uncontrolled. The credit
would be 1.2 Ib SO /ton of coke, if the emissions were controlled to
meet the NSPS. x
Thus, the net incremental emissions credit is estimated to be 5.6
Ib SO /ton of coke, if the emissions are uncontrolled, and 1.1 Ib SO /
ton or" coke, if the emissions are controlled to meet the NSPS. x
Steelmaking
Base Case Process - Coke Oven, Blast Furnace (BF), and Basic Oxygen
Furnace (BOF) Route for Steelmaking—
The base case process is the conventional process for Steelmaking.
It is assumed, for our analysis, that 30% scrap metal is used in the
BOP. A detailed description of the process is given in Volume III, page
54.
Electricity consumed by the coke oven, BF, BOF, and pollution con-
trol equipment is estimated at 120 kWh/ton of steel (Volume III, pages
79, 82-84). SO emissions from the power boiler are estimated at 7.0
Ib/ton of steelx if the flue gas is untreated, and 1.5 Ib/ton of steel
if the NSPS is met.
Steam, consumed by the coke-making facilities, is required at about
670 Ib/ton of steel. If this steam is generated with coal, then SO
emissions are estimated at 3.7 Ib SO /ton of steel if the flue gas
emissions are uncontrolled, and 0.8 lx SO /ton of steel, if the flue gas
is treated to meet the NSPS. x
Process Option - Direct Reduction Route for Steelmaking—
Iron oxide pellets, ore lumps, and the like, can be partially re-
duced in the solid state by reaction with a reducing gas mixture. These
84
-------
prereduced materials can partially or entirely replace purchased scrap
in the steelmaking electric arc furnaces. In this alternative process,
it was also assumed that 30% scrap is used with 70% prereduced pellets
to make steel. A detailed process description is given in Volume III,
page 54.
Electricity consumed by the sponge iron facilities, the electric
furnace shop, and the pollution control equipment is estimated at 712
kWh/ton of steel. Sulfur dioxide emissions from the power boilers are
estimated at 41.3 Ib/ton of steel, if the emissions are uncontrolled,
and 9.0 Ib/ton of steel if the emissions are controlled to meet the
NSPS.
Summary
The emissions factor and total emissions for the base case pro-
cesses and the alternative processes are summarized in Table 23.
In the production of iron, it is seen that external desulfurization
offers no reduction in SO emissions from the base case process, large-
ly because most of the sulfur values leave the blast furnace area in
the slag.
In the production of steel, recovery of the low-sulfur off-gas from
the BOF offers a 50% reduction in emissions because of its waste heat
value, which can potentially reduce need for high-sulfur fuels. How-
ever, steelmaking by the direct reduction method will result in nearly
a three-fold increase in emissions over the conventional route because
of the high power requirements of this alternative route.
PHOSPHORUS/PHOSPHORIC ACID
Base Case Process - Electric Furnace Production of Phosphorus and
Conversion of Phosphorus to Phosphoric Acid
In this process, phosphate rock is reduced to elemental phosphorus
by coke in an electric furnace. Phosphorus vapor and carbon monoxide
are produced. The phosphorus is condensed and subsequently converted
to pure phosphoric acid. The details of this process are presented
in Volume XIII, pages 23-24.
Electric furnace production of phosphorus is a very energy-inten-
sive operation. Electrical energy requirements are estimated at 13,000
kWh per ton of phosphorus (P,). More than 90% of this energy is re-
quired by the furnace; the remainder is required for pumping operations.
In addition, 1.9 tons of coke/ton of P, are charged to the furnace,
where carbon monoxide is produced. The carbon monoxide is recovered
and fired in the rotary kiln where the furnace feed materials are pre-
pared. A small amount of natural gas (6 million Btu/ton of P.) is re-
quired to supplement the carbon monoxide gas.
85
-------
TABLE 23. ESTIMATED CONTROLLED SOV EMISSIONS - IRON AND STEEL INDUSTRY
X
Process
SOX emission factor
S0.y emissions
(Ib/ton of product) Change in (106 Ib/yr)
Process Power boiler Total emission factor 1974 1989-1974*
Base case:
BOP with no
off-gas recovery
• BOP with off-gas
recovery
Base case:
oo Blast furnace
• Blast furnace with
external desulfurization
Base case:
Wet quenching of coke
• Dry quenching of coke
Base case:
Coke oven, blast
furnace, BOP route
• Direct reduction,
EAF route
0.8
0.2
0.1
0.3
0.3
1.5
9.0
0.2
0.1
0.3
0.3
N.A. N.A.
-1.2*** 0.1*** -1
2.3
9.0
-0.1
0.0
-1.1
6.7
16.4** 12.0
6.0
30**
13.4
13.4
N.A. N.A.
-30.6***
189** 138
Small 540
(continued)
-------
TABLE 23 (continued)
Based on increment in production from 1974 to 1989 - 27.8 x 106 tons of coke, 44.8 x 106
tons of iron, and 60 x 10 tons of steel.
**
Estimated 1974 emissions based on multiplying emission factor by 1974 production: 62 million
tons coke, 100 million tons iron and 82 million tons BOP steel.
Emission factor is based on incremental requirements and credits of the dry-quench process
as it compares to the wet-quench process.
00
^ N.A.: Not available - see footnote *** for dry quenching of coke.
-------
Sulfur dioxide emissions result primarily from the coal-fired pow-
er boiler. It is estimated that 71.5 Ib SO /ton of P205 are emitted if
the NSPS for coal-fired units is met. Without flue gas desulfurization,
emissions are estimated at 329 Ib/ton of ^2^5"
Sulfur dioxide emissions from the furnace coke are negligible since
the sulfur in the coke would be removed with the slag by the calcium
from the phosphate ore.
Process Option 1 - Chemical Cleanup of Wet-Process Phosphoric Acid
In the wet process, phosphate ore is reacted with sulfuric acid.
Phosphoric acid (32% solution) is recovered from the undigested ore and
the gypsum byproduct. This acid is concentrated by evaporation to the
54% P2°5 Pr°duct. The wet process is described in more detail in Vol-
ume XIII, pages 35-37. However, there are a number of impurities in
the regular wet-process phosphoric acid which make it unsuitable for
use in certain applications. Wet acid is purified to sodium tripoly-
phosphate by a two-stage neutralization process (Volume XIII, page 49).
Steam is required to concentrate the acid solution. If the phos-
phoric acid plant is integrated with a sulfuric acid plant, then this
steam is generated when the sulfur is oxidized, yielding 13 x 10^ Btu/ton
of P20cj and controlled SC^ emissions of 10 Ib/ton of P205- Approximately
half of the steam heat is used in the sulfuric acid plant and the other
half is used by the phosphoric acid plant.
Electricity (250 kWh/ton of P2°5^ is recluired to drive pumps, ag-
itators, and filters in the wet-acid process. An additional 16 kWh/ton
of ?2®5 is required for the chemical cleanup of the acid. Sulfur di-
oxide emissions from power generation is estimated at 3.4 Ib SO /ton
]?2^5' if the steam is generated from a coal-fired boiler which complied
with the NSPS. Without sulfur dioxide control, emissions would be
about 15.4 Ib/ton of P 0 .
Process Option 2 - Solvent Extraction Cleanup of Wet-Process Phosphoric
Acid
Cleanup of wet-process phosphoric acid is based on the fact that
phosphoric acid can be transferred from solution in an aqueous phase to
solution in an organic phase and leave behind undesirable impurities,
such as calcium chloride, in the aqueous layer. The organic phase can
then be contacted in a separate unit with fresh water to yield a pure
solution of phosphoric acid. A detailed process description is given
in Volume XIII, page 60.
The solvent-extraction process requires about 10,000 Ib steam/ton
of ?2®5 f°r concentration of the acid from 15% as it is produced in
the extraction section to a concentration of about 60% Po^S' ^ t'ie
steam is generated with low-sulfur oil so that flue gas desulfurization
is not required, then emissions are estimated at 5.5 Ib SO /ton of P00,..
x z j
88
-------
Electricity requirements will be about 300 kWh/ton of ?2®5'
estimated SO emissions from power boilers are 3.8 Ib/ton of P2°
no control, and about 17.4 Ib/ton of P205 with control to meet the NSPS.
Summary
The emissions factor and total emissions for the base case process
and alternative processes are summarized in Table 24. Both of the pro-
cess options for "pure" phosphoric acid offer a significant reduction
in SO emissions over the base case process. This reduction is pri-
marily a result of the lower power requirements for both the chemical
cleanup and solvent extraction process options.
FERTILIZERS
Nitric Acid Production
The manufacture of nitric acid, described in Volume XV, pages 25-28,
generates significant emissions of nitrogen oxide and this area of pri-
mary interest is discussed in more detail in "Volume XV, NO Summary
Report". Adoption of air pollution control is a recent practice in the
industry. The process change considered in the nitric acid production
is the application of alternative NO abatement systems. These process-
es are described in Volume XV, pages 33-42.
Base Case Process - Nitric Acid Production without NO Emission Control—
X
Nitric acid is produced by the oxidation of ammonia, usually under
high pressure and temperature over a platinum catalyst. Waste heat re-
covered from the product gases is used to generate steam. The cooled
gases are subsequently sent to an absorption tower to form the acid
product.
Fuel requirements are satisfied by natural gas. Steam generated
by the waste heat is included as an energy credit. An analogous credit
for SO emissions was assumed, since the steam generated by the waste
heat would otherwise be generated by low-sulfur oil so that flue gas
desulfurization would not be required. This emissions credit is es-
timated to be 0.4 Ib SO /ton of nitric acid.
x
Process Option 1 - Catalytic Reduction—
In the catalytic reduction process, tail gas from the absorber
passes through a combustor where the nitrogen oxides are reduced to N»
and 0~. Natural gas is used as a fuel in the combustor. Steam is gen-
erated by waste heat recovered from the product gases.
Energy requirements for the process include natural gas and elec-
tricity. Although catalytic reduction is an energy-intensive process,
there is an SO emissions credit because steam, which would otherwise
X
89
-------
TABLE 24. ESTIMATED CONTROLLED SO EMISSIONS - PHOSPHORUS/PHOSPHORIC ACID PRODUCTION
X
Process
SOX emission factor
(Ib/ton
Process Boiler Total
Change in
emission factor
emissions
(10 Ib/yr) ~
1974 1989-1974
Base case:
**
Electric furnace
• Chemical cleanup of
wet-process acid
• Solvent extraction of
wet-process acid
0 71.5 71.5
10.0 3.4 13.4
5.5 3.8 9.3
-58.1
-62.2
100** 45.0
8.4
5.9
Based on the incremental production detergent grade phosphoric acid from 1974 to 1989 of
0.63 x 10° Ib/yr multiplied by total emission factor.
**
The SOX emissions based on the emission factor of 71.5 Ib/ton of detergent-grade phosphoric
acid in the year 1974 are 71.5 x 1.4 x 106 = 100 x 106 pounds.
-------
be generated by oil, is generated with waste heat from the process. The
net SO emissions credit is estimated to be 0.6 Ib SO /ton of nitric
. , x x
acid.
Process Option 2 - Molecular Sieve Method—
This method is based on the principles of adsorption, oxidation,
and regeneration of the molecular sieve. An oil-fired heater is used
to provide heat for regeneration of the sieve. The process has high
efficiency for removal of NO gases. A detailed description of the
method is given in Volume XV, page 36.
Energy requirements include fuel oil, steam, and electricity. High
power requirements (26 kWh/ton of acid) result from the added compres-
sion requirements and the need to regenerate the sieve. SO emissions
from power boilers without flue gas desulfurization are estimated to
be 1.5 Ib SO /ton of acid, and 0.3 Ib SO /ton of acid from power boil-
ers with flue gas desulfurization required to meet the NSPS. SO emis-
sions from the fuel oil (0.5% sulfur) used in the sieve regeneration
and steam production are estimated at 11.1 Ib/ton of acid, for a total
of 11.4 Ib.
Process Option 3 - Grand Paroisse or Extended Water Absorption—
In this process, tail gas from the existing absorption tower is
delivered to a second absorption tower for "extended absorption of ni-
trogen oxides by water".
The energy requirements for this process are small — only 7.2 kWh/
ton of nitric acid product are used. Power plant emissions are estimat-
ed at 0.1 Ib SO /ton of acid, if the NSPS for coal-fired units is met,
and 0.4 Ib SO /con of acid for plants without flue gas desulfurization.
X
CDL/Vitok Process—
In this process, the tail gas is scrubbed with nitric acid under
conditions which reduce the nitrogen oxides to the desired level. En-
ergy requirements include steam and electricity. The total steam re-
quirements will result in SO emissions of 31.5 Ib/ton of acid, if low-
sulfur fuel oil is used, so that flue gas desulfurization is not re-
quired. Electrical requirements (24 kWh/ton of acid) will result in
SO emissions of 0.3 Ib/ton of acid, if the flue gas is desulfurized to
meet NSPS for coal-fired, and 1.4 Ib/ton, if no desulfurization is per-
formed .
The Masar Process—
In this process, the tail gas is chilled and then scrubbed with an
urea-containing solution. As nitric acid is produced, urea hydrolyzes
and forms ammonium nitrate.
91
-------
Steam is consumed at 105,000 Ib/ton of acid, and electricity, at
1.5 kWh/ton of acid for this process. Steam generation by low-sulfur
fuel oil will result in 57.6 Ib SO /ton of acid. The electrical re-
quirement contributes essentially no SO emissions, whether or not the
power boilers meet the NSPS for coal-fired units.
Conversion to Fuel Oil in Mixed Fertilizer Plants Equipped with Bag
Filters
Base Case Process—
The base case operation is an ammoniation granulation plant which
uses a natural gas-fired dryer and is equipped with a baghouse filter
to control fertilizer dust produced during drying. Only 20 percent of
the estimated 200 plants is equipped with baghouses and would there-
fore be affected by this process change. Sulfur dioxide emissions from
the base case operation are essentially nil.
Installation of Scrubber on Baghouse-Equipped Plants when Converting
from Natural Gas to Fuel Oil—
When fertilizer dryers were converted from natural gas to oil, op-
erational problems sometimes resulted from the plugging of the baghouse
filters with ash from the oil. If these problems cannot be resolved by
the modification of the combustion process, then wet scrubbers will be
required for particulate control.
Incremental SO emissions result from conversion to fuel oil as-
sumed to contain 0.5% sulfur. If 20% of the sulfur dioxide is removed
in the wet scrubber, then SO emissions are estimated to be 0.14 Ib/ton
of fertilizer; no further specific control for SO is anticipated.
X
Continued Operation of the Baghouse Filter after Conversion from
Natural Gas to Fuel Oil—
If filter clogging problems can be alleviated by proper design and
operation of the fuel oil-fired dryer, the baghouses will not have to
be replaced by scrubbers. If the fuel oil contains 0.5% sulfur, and
since 0.3 million Btu of fuel are required to dry each ton of fertilizer
(Volume IV, page 54), then 0.18 Ib SO will be emitted per ton of pro-
duct by conversion to fuel oil. X
Summary
The emission factors and total emission for the base case and al-
ternative processes for NO abatement and fuel conversion in fertilizer
drying are presented in Table 25. For NO abatement in nitric acid pro-
duction, only the catalytic reduction process option offers a reduction
of SO emissions from the base case process. This is primarily a result
of the large power requirements for the NO control systems. On the
contrary, the molecular sieve, CDL/Vitok, and Masar processes for NO
X
92
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TABLE 25. ESTIMATED CONTROLLED SOY EMISSIONS - FERTILIZER INDUSTRY
A.
SOX emission factor SOX emissions
(Ib/ton of nitric acid) Change in (106 Ib/yr) ^
Process Process Power boiler Total emission factor 1974 1989-1974
Nitric acid production - With various processes to control NOX emissions
Base
•
•
•
•
•
case:
No NOX control
Catalytic reduction
Molecular sieve
Grand Paroisse
CDL/Vitok
Masar
Converting fertilizer dryers
Base
•
•
case :
Natural gas
Better equipment/
technique with
fuel oil
Installing scrubbers
-.4
-.7
11.1
0.0
31.5
57.6
(with
Nil
0.18
0.14
0.0
.1
.3
0.1
0.3
0.0
baghouses)
Nil
0.0
0.0
-.4 — -3.3** -2.6
-.6 -0.2 — -4.0
11.4 11.8 — 75.2
0.1 0.5 — 0.66
31.8 32.2 — 209.0
57.6 58.0 — 383.0
from natural gas to oil
Nil — Nil Nil
***
0.18 0.18 — 0.29
***
0.14 0.14 — 0.22
(continued)
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TABLE 25 (continued)
*
Calculated using 4% growth rate for 15 years based on 10 million tons/year in 1974 and rising
to 18 million tons/year in 1989; thus potential growth of 18 x 106 tons.
**
Estimated 1974 emissions based on total emission factor (credit) of -0.4 Ib S0x/ton of nitric
acid are 0.4 x 8.2 x 10" = -3.3 x 10^ ton/yr (SOX emissions credit since energy is recovered
in this process).
***
Based on 4% growth rate for 15 years based on 2 million tons/yr in 1974 and rising to 3.6
million tons in 1989; this potential growth of 1.6 million tons is multiplied by the
emission factor.
-------
control may significantly increase estimated SO emissions.
X
Fuel conversion for fertilizer dryers equipped with baghouse fil-
ters has a small impact on the total amount of sulfur dioxide emissions
on an industry-wide basis since only 20% of the fertilizer plants are
equipped with these air filters.
TEXTILES
Two textile mills, an integrated knitting mill and an integrated
weaving mill, were examined. The mill operation includes the knitting
of the greige yarn, or the weaving of greige fabric, and the subsequent
dyeing and finishing of the fabric.
Knit Fabrics Production
Base Case Process—
In the knitting mills, yarn is knitted into fabric in the greige
mill. The greige fabric is next scoured to remove knitting oil, and
is then dyed, washed, and spin-dried to remove as much water as pos-
sible before hot-air drying. A finish (softener/lubricant) is then ap-
plied to the fabric, which is dried and heat-set. Details of the knit-
ting mill operation are presented in Volume IX, page 33.
It is unlikely that natural gas, used for the hot-air drying and
heat-set operations, will be easily replaced, as it is required by all
of the equipment presently available for fabric drying and heat-setting
operations.
Steam is used for the heat input to the scouring, dyeing, and wash-
ing operations. In the base case process, it was assumed that the steam
would be generated with low-sulfur oil, so that flue gas desulfurization
would not be required. Since 4 Ib of steam/lb of fabric are required,
then about 4.4 Ib SO /ton of fabric would be emitted. Because of the
relatively small energy requirements of textile mills, it seems unlike-
ly that coal will be used as a fuel for steam production (Volume IX,
page 41).
Electricity is required to provide mechanical energy to transfer
fabric from the beginning to the end of the process line and for knit-
ting the yarn into the fabric. Electrical requirements of 0.18 kWh/lb
of fabric will result in SO emissions of about 4.5 Ib SO /ton of fab-
ric, if the NSPS is met. Without SO cleaning of the stack gas, SO
emissions would be 20.7 Ib/ton of fabric.
Advanced Aqueous Processing—
The sequence of operation is similar to the base case except that
(1) the hot air drier is replaced by an air/vacuum extractor, thereby
reducing natural gas requirements and increasing electrical requirements,
95
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and (2) the scouring, dyeing, and washing operations are modernized
with more efficient equipment, thereby reducing steam requirements.
The advanced process is described in detail in Volume IX, pages 35-37.
Steam requirements of 1.9 Ib/lb of fabric will result in 2.1 Ib
SO /ton of fabric, if the steam is generated by low-sulfur oil so that
flue gas desulfurization is not required. Electrical requirements of
0.25 kWh/lb of fabric will result in 6.3 Ib SO /ton of fabric, if the
NSPS are met. Without flue gas desulfurization, SO emissions would
be 29 Ib SO /ton of fabric. X
x
Solvent Case—
Solvent systems are assumed for the scouring, dyeing, and finishing
operations. The fabric is steam-stripped to remove residual solvent.
Clean solvent is recovered by distillation with steam. Details of a
solvent process are provided in Volume IX, pages 37-41.
Steam requirements of 1.1 Ib/lb of fabric will result in 1.2 Ib
SO /ton of fabric, if low-sulfur oil is used to generate the steam and
flue gas desulfurization is not required.
Electricity requirements of 0.12 kWh/lb of fabric will result in
3.0 Ib SO /ton of fabric, if the NSPS are met. Without SO removal
from the Boiler flue gas, emissions would be about 13.8 Ib SO /ton of
fabric. By comparison with current technology, the solvent processing
route can reduce SO emissions — after control — by some 53%.
x J
Woven Fabrics Production '
Base Case Process—
The operations of woven fabric preparation, dyeing, and finishing,
involve a much longer processing sequence than knit fabrics. These
steps are described in Volume IX, page 44.
Natural gas is used in the drying, setting, and curing operations;
hence there are no SO emissions in these steps. Steam (15 Ib/lb of
fabric) is used for process water heating in the dyeing, washing, and
finishing steps. Steam generation will result in 16.5 Ib SO /ton of
fabric, if low-sulfur oil is burned and flue gas desulfurization is not
required. Electrical energy requirements are estimated at 0.29 kWh/lb
of product. This will result in SO emissions of 7.3 Ib/ton of fabric,
if the NSPS are met. Otherwise, uncontrolled emissions are estimated
at 33.6 Ib/ton of fabric.
Advanced Process—
The advanced processing includes a polyvinyl alcohol (PVA) recov-
ery loop which recycles concentrated PVA solution back to sizing and
the hot water back to the desizing operation. Details of the advanced
96
-------
case sequence are presented in Volume IX, page 49.
Steam requirements have been reduced to 6.4 Ib/lb of fabric by re-
duction in overall process water use and recycling of wash waters. This
steam generation will produce 7.0 Ib SO /ton of fabric. These emissions
are not controlled. Electrical requirements have been reduced to 0.15
kWh/lb of steam, which will result in SO emissions of 3.8 Ib/ton of
X
fabric, if the NSPS are met. Without control, sulfur dioxide emissions
are estimated at 17.5 Ib/ton of fabric.
Summary
97
-------
TABLE 26. ESTIMATED SCI EMISSIONS - TEXTILE INDUSTRY
X
CO
SOV emission factor
SO-^, emissions
(Ib/ton fabric) Change in (10° Ib/yr) A
Process Process Power boiler Total emission factor 1974 1989-1974
Knit fabric
Base case - aqueous 4.4
• Advanced aqueous 2 . 1
• Solvent processing 1.2
Woven fabric
Base case - aqueous 16.5
• Advanced aqueous 7.0
4.5 8.9
6.3 8.4 -.5
3.0 4.2 -4.7
7.3 23.8
3.8 10.8 -13.0
**
2.9 1.1
1.0
0.5
***
50 19 . 3
8.8
**
***
Based on no retirement of existing facilities, incremental production from 1974 to 1989 of
1) 0.12 x 10° ton/yr (knit fabric) multiplied by total emission factor, and 2) 0.81 x 106 ton/yr
(woven fabric) multiplied by total emission factor.
Estimated 1974 emissions from knit fabric production based on the total emission factor of 8.9 Ib
S0x/ton of fabric are 8.9 x 0^32 x 106 = 2.85 x 106 Ib.
Estimated 1974 emissions from woven fabric production based on total emission factor of 23.8 Ib
S0x/ton of fabric are 23.8 x 2.1 x 106 = 50 x 106 Ib/yr.
-------
REFERENCES
U.S. Environmental Protection Agency, AP-42, Compilation of Air Pollution
Emission Factors, Second Edition, March 1975.
99
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TECHNICAL REPORT DATA
(/'/case read fmumctions on the reverse before completing)
1. REPORT NO.
EPA-600/7-79-141
3. RECIPIENT'S ACCESSI Of* NO.
4. TITLE ANDSUSTITLE
Environmental Considerations of Selected Energy-
Conserving Manufacturing Process Options
Volume XVI Sulfur Oxides Summary Report
5. REPORT DATE
August 1979 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Arthur D. Little, Inc.
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Arthur D. Little, Inc.
20 Acorn Park
Cambridge, MA 02140
10. PROGRAM ELEMENT NO.
INK 624R
11. CONTRACT/GRANT NO.
68-03-2198
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
-Cincinnati. Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
16. ABSTRACT
Arthur D. Little, Inc., undertook a study of the "Environmental Considerations
of Selected Energy-Conserving Manufacturing Process Options." Some 80 industrial
process options were examined in 13 industrial sectors. Results were published in 15
volumes, including a summary, industry prioritization report, and 13 industry oriented
reports (EPA-600/7-76-034 a through o).
This present report summarizes the information regarding sulfur oxide pollutants
in the 13 industry reports. Four parallel reports treat nitrogen oxides, particulates,
solid residues, and toxics/organics. All of these pollutant-oriented reports are
intended to be closely used with the original 15 reports.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
COSATI Field/Group
Energy, Pollution, Industrial Wastes
Manufacturing Processes,
Energy Conservation
68D
13. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (This Reportj
UNCLASSIFIED
21. NO. OF PAGES
108
20. SECURITY CLASS (Thispage)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
100
ft US GOVEKHMENTniMTIIIGOFFICE: 1979-657-060/5404
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