United States
Environmental Protection
Agency
Industrial Env ironmental Research E PA - 600 / 7 - 7 9 -14 2
Laboratory July 1979
Cincinnati OH 45268
Research and Development
Environmental
Considerations of
Selected Energy-
Conserving
Manufacturing
Process Options
Volume XVII
Nitrogen 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-600/7-79-142
July 1979
ENVIRONMENTAL CONSIDERATIONS OF SELECTED
ENERGY-CONSERVING MANUFACTURING PROCESS OPTIONS
Volume XVII. Nitrogen Oxides Summary Report
by
Arthur D. Little, Inc.
Cambridge, Massachusetts 02140
Contract No. 68-03-2198
Project Officer
Herbert S. Skovronek
Power Technology 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 »al* by the Superintendent of Document*, U.S. G
Printing Office, Washington, D.C. 20402
,ov eminent
-------
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 nitrogen 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
-------
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
solid residues in the 13 industry reports. Four parallel reports
treat sulfur oxides, nitrogen oxides, particulates, and toxics/
organics. All of these pollutant-oriented reports are intended
to be closely used with the original 15 reports.
iv
-------
CONTENTS
Foreword iii
Abstract iv
Tables vi
English-Metric (SI) Conversion Factors vii
1. INTRODUCTION 1
BACKGROUND AND PURPOSE 1
APPROACH 2
2. FINDINGS AND R&D OVERVIEW 5
FINDINGS 5
IDENTIFICATION OF CROSS-INDUSTRY TECHNOLOGY 20
R&D AREAS 20
3. PROCESSES AND POTENTIAL NITROGEN OXIDE EMISSIONS 23
BASES OF CALCULATIONS 23
NO CONTROL METHODS 23
PETROLEUM REFINING INDUSTRY 25
CEMENT INDUSTRY 27
OLEFINS INDUSTRY 32
ALUMINA AND ALUMINUM INDUSTRY 37
GLASS INDUSTRY 41
COPPER INDUSTRY 45
FERTILIZER INDUSTRY 50
AMMONIA 56
IRON AND STEEL 59
PHOSPHORUS/PHOSPHORIC ACID 63
TEXTILES INDUSTRY 68
PULP AND PAPER INDUSTRY 70
CHLOR-ALKALI INDUSTRY 76
REFERENCES 80
-------
TABLES
Number
1 Projected U.S. Production in Industries Studied 4
2 Summary of Estimated Annual NO Emissions 6
3 NO Nationwide Emission Estimates (1974) 15
X
4 Estimated Increase in Controlled NO Emissions
1989-1974 Assuming Industry Expands Using Process
Types Indicated (10 Ib NO /yr) 16
X
5 Estimated Range in Controlled NO Emissions in
1989 for New Processes Likely to be Implemented 18
6 How Current NO Control Methods Fare with Fossil
Fuels X 24
7 Estimated NO Emissions - Petroleum Refinery Industry 28
8 Estimated NO Emissions - Cement Industry 33
9 NO Emission Factors - Olefins Industry 34
X
10 Estimated NO Emissions - Olefins Industry 36
X
11 Estimated NO Emissions - Alumina and Aluminum
•\r
Industry 42
12 Estimated NO Emissions from Glass Furnaces 46
X
13 Estimated NO Emissions - Copper Smelting 51
X
14 Estimated NO Emissions from Nitric Acid Plants 53
15 Estimated NO Emissions - Nitric Acid Industry 57
X
16 Estimated NO Emissions - Ammonia Industry 60
17 Estimated NO Emissions - Iron and Steel Industry 64
x
18 Estimated NO Emissions - Phosphorus/Phosphoric
Acid Production 67
19 Estimated NO Emissions - Textile Industry 71
20 Estimated NO Emissions - Pulp and Paper Industry 74
X
21 Estimated NO Emissions - Chlor-Alkali Industry 79
X
VI
-------
ENGLISH-METRIC (SI) CONVERSION FACTORS
To Convert From
T£
Metre2
Pascal
Metre
Joule
Pascal-second
Multiply By
4,046
101,325
0.1589
1,055
0.001
Acre
Atmosphere (normal)
Barrel (42 gal)
British Thermal Unit
Centipoise
Degree Fahrenheit
Degree Rankine
Foot
Foot /minute
Foot3
2
Foot
Foot/sec
2
Foot /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)
Degree Celsius
Degree Kelvin
Metre
Metre /sec
Metre3
2
Metre
Metre/sec
2
Metre /sec
Metre3
Watt
Watt
Watt
Metre
Joule
Metre3
Metre
Metre
Metre
Pascal-second
Newton
Kilogram
Kilogram
Kilogram
Kilogram
Kilogram
Kilogram
t° = (tj -32]
c F
o o
'K = CR
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
vii
-------
SECTION I
INTRODUCTION
BACKGROUND AND PURPOSE
During 1975 and the first half of 1976, under EPR Contract No,
68-03-2198, Arthur D. Little, Inc., undertook a study of the "Environ-
mental Considerations of Selected Energy-Conserving Manufacturing
Process Options" in 13 energy-intensive industry sectors for the
U.S. Environmental 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-600/7076-034h)
• 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
implementation 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 infor-
mation can be found have been extensively referenced by volume number
and page number (e.g., Volume VII, page 20, refers to page 20 of the
Ammonia Industry report).
-------
In Section 2 of this report (Findings and R&D Overview), summary
information on generic, cross-industry problems that emerge and sugges-
tions 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 NO pollution control
technology are presented, and NO emissions and controls reported in
our previous study are summarized. Unless otherwise noted, the factional
percent of NO in gas streams is reported as NO. equivalent. All
emissions are estimated unless specifically referenced, 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.
-------
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.
projection
in 1974
(10b 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
(10 tons) (10 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
***Approximate equivalent of 37.5 quads.
****Approximate equivalent of 7.5 quads.
15
Btu).
-------
SECTION 2
FINDINGS AND R&D OVERVIEW
FINDINGS
Seven of the 13 industries addressed in the original study have process-
related NO pollution problems and are therefore covered in this report.
These industries are alumina/aluminum, cement, copper, fertilizers, flat
glass, olefins, and petroleum refining. Industries which do not have
NO emission problems or industries in which the emissions are not altered
by the process change are not included here because these process changes
are not important from the point of view of NO emissions. Table 2 pre-
sents a summary of the estimated NO 'emissions from both the base case
processes and process alternatives In these seven industries.
The emission factors shown in the table include both process and power
boiler emissions. Emissions from the power boilers were generally not
estimated in the original study but are included here because emissions
from the base case and alternative processes are compared in this report
by considering the total system. The power boilers include on-site power
boilers for steam and electricity generation and utility power boilers
(off-site power plants) for electricity generation. The emission factors
vary in the range of 3.0 to 15.0 Ib/ton of product. The exceptions are:
• Processes in the aluminum industry which have high emissions
due to consumption of large quantities of electricity;
• The nitric acid industry without NO control which has
high emissions (emission factor 52.0 Ib of NO /ton of acid);
X
• The nitric acid industry with NO emissions controlled
catalytically using hydrogen or molecular sieve methods
which has low emissions (0.1 to 1.1 Ib of NO /ton of acid);
and
• Processes in which combustion is controlled and therefore
emissions are low, such as the fluidized bed process in
place of a kiln in the cement industry (emission factor
0.65 Ib of NO /ton of cement).
X
As is shown in Table, the greatest volume of NO emissions from base
case processes in the year 1974 was estimated to come from petroleum
refining operations, followed by aluminum, fertilizers, cement, flat glass,
etc. Table 2 also shows estimated incremental NO emissions (1989 - 1974)
based on the increase in production from 1974 to 1989 as determined from
Table 1. Incremental emissions are shown from both the base case and
alternative processes assuming dedication of 100% of the incremental pro-
duction rather than a fraction to each process (base case and alternative).
-------
TABLE 2. SUMMARY OF ESTIMATED ANNUAL NO EMISSIONS
x
Commodity
Process
NO emissions in
V
1974 from base case
-process
(10" Ib/yr)
Incremental
NO emissions
1989-1974
(10b Ib/yr)
Change
from base case
in 1989
(106 Ib/yr)
Petroleum Base case:
East Coast refinery 1,244
• Direct combustion of
asphalt in process
heaters and boilers
• Flexicoking
Base case:
Gulf Coast refinery 1,343
• 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
(b)
(b)
(b)
311
373
311
336
319
(b)
(b)
(b)
+ 62
0
- 17
(continued)
-------
TABLE 2. (continued)
Commodity
Olefins
Cement
NO
1974
Process
Base case:
Ethane-propane process
• Naphtha process
• Gas-oil process
Base case:
Long dry kiln
• Suspension preheater
• Flash calciner
• Fluidized bed
emissions in
from base case
process
(10b lb/yr)
169
—
300
—
—
—
Incremental
NO emissions
$9*9-1974
(10b lb/yr)
389
358
369
104
82
82
18
Change
from base case
in 1989
(10° lb/yr)
-
- 31
- 20
-
- 22
- 22
- 86
Alumina
• Coal as fuel instead
of gas or oil in long
dry kiln
Base case:
Bayer process
• Hydrochloric acid
ion exchange
• Nitric acid
ion exchange
• Toth alumina
72.9
104
102
267
108
90
+165
+ 6
- 12
(continued)
-------
TABLE 2. (continued)
Commodity
Aluminum
NO
1974*
Process
Base case:
Hall-Heroult
(current practice, C, P.)
• Hall-Heroult (new)
• Alcoa chloride
emissions in
from base case
process
(10b Ib/vr)
628
—
. —
Incremental
NO emissions
$989-1974
(106 Ib/vr)
879
680
592
Change
from base case
in 1989
(10b Ib/yr)
- 199
- 287
Flat Glass
• Refractory hard
metal cathode
Base case:
Bayer with
Hall-Heroult (C,P.)
• Clay chlorination (Toth
Alumina) and alcoa
chloride
Base case:
Natural gas firing
• Coal gasification
• Direct coal firing
• Coal-fired hot gas
generation
701
236
705
1,007
664
106
116
132
148
- 174
- 343
+ 10
+ 26
+ 42
(continued)
-------
TABLE 2. (continued)
Commodity
Flat Glass
(cont. )
Copper
NO emissions in
1974 from base case
Process process
(105 Ib/yr)
• Electric melting —
• Batch preheating with
natural gas firing
Base case:
Conventional smelting 19.4
• Outokumpu flash
smelting - —
• Noranda • —
• Mitsubishi —
• Arbiter —
Incremental
NO emissions
$989-1974
(106 Ib/yr)
93
85
13
.9
6
5 + 2
34
Change
from base case
in 1989
(106 Ib/yr)
- 13
- 21
—
4
7
8
+ 21
Fertilizers
(Nitric acid)
Base case:
Uncontrolled*
• Catalytic reduction
• Natural gas fired
• Hydrogen fired
• 75% Hydrogen/25%
natural gas
426
343
27
.7
- 316
- 342
.7 - 342
(continued)
-------
TABLE 2. (continued)
Commodity
Fertilizers
(cont. )
Ammonia
Iron and Steel
NO emissions in
1974 from base case
Process process
(106 Ib/yr)
• Molecular sieve > —
• Grande Paroisse
• CDL/Vitok
• Masar
Base case:
Ammonia via natural gas 91
• Ammonia via coal
gasification — -
• Ammonia via heavy fuel oil —
Base case:
No off gas recovery 30
• Off gas recovery —
Incremental
HO emissions
$989-1974
(106 Ib/yr)
7.3
24
21
17
127
344
155
22
11
Change
from base case
in 1989
(106 Ib/yr)
- 336
- 319
- 322
- 326
-
+ 217
+ 28
-
- 11
Base case:
Blast furnace
• Blast furnace with
external desulfurization
Base case:
Wet quenching of coke
(a)
3.1
3.1
(a)
(continued)
-------
TABLE 2. (continued)
Commodity
Process
NO emissions in
2£
1974 from base case
process
(106 lb/yr)
Incremental
NO emissions
$989-1974
(10b Ib/yr)
Change
from base case
in 1989
(105 lb/yr)
Iron and steel
(cont.)
• Dry quenching of
coke
Base case:
Steelmaking coke oven,
blast furnace, BOP route
• Direct reduction,
EAF route
Phosphorus/
phosphoric acid Base case:
Electric furnace
• Chemical cleanup of
wet-process acid
• Solvent extraction of
wet-process acid
Textiles
Knit fabric:
• Base case:
Conventional aqueous
• Advanced aqueous
• Solvent processing
148
67
2.5
- 21
108
336
30.1
2.9
4.2
.95
.65
.34
- 21
+ 228
- 27
- 26
.30
.61
(continued)
-------
TABLE 2. (continued)
Commodity
Textiles
(cont.)
Process
Woven fabric:
• Base case
• Advanced aqueous
NO emissions in
•y
1974 from base case
process
(106 Ib/yr)
39.5
Incremental
NO emissions
¥989-1974
(1(T Ib/yr)
15.2
6.5
Change
from base case
in 1989
(106 Ib/yr)
- 8.7
Pulp and paper Chemical pulp:
• Base case:
Kraft pulp
Chloro-alkali
• Alkaline-oxygen pulping
• Rapson effluent free
pulping
Newsprint pulp:
• Base case:
Refinery mechanical pulping
• Thermo-mechanical pulping
• Deinking of old newsprint
for newsprint manufacture
Base case:
Graphite-anode
diaphragm cell
• Dimensionally stable
anodes
90
41
313
97
71
55
17.9
19.4
5.6
- 26
- 42
+ 1.5
- 12.3
339
323 - 16
(continued)
-------
TABLE 2. (continued)
Commodity
Chloro-alkali
(cont. )
NO emissions in
v
1974 from base case
Process process
(10b Ib/yr)
• Expandable DSA
• Polymer modified
asbestos
• Polymer membrane —
• Ion exchange
membrane
• Mercury cell
Incremental
NO emissions
$989-1974
(19& Ib/yr)
293
297
297
283
351
Change
from base case
in 1989
(10° Ib/yr)
- 46
- 42
- 42
- 56
+ 12
Calculation based on change from base case.
No change from base case process.
-------
Thus, for each process incremental NO emissions (1989-1974) are calculated
by multiplying the emission factor (Ib NO /ton of product) by the estimated
increase in product production between 19/4 and 1989. Total actual emis-
sions from each process in the year 1989 would be the sum of 1974 emissions
from the base case process, assuming no retirement at existing facilities,
and actual incremental emissions (Ib NO /year) from the base case and new
processes installed between 1974 and 1989.
The estimated increase or decrease in emissions from the alternative
processes in relation to the base case process is also shown in Table 2
for the year 1989. This number shows the potential for emission reduc-
tion in 1989 using new process technology. It is seen that the greatest
potential for emission reduction by new processes exists in the nitric
acid industry, followed by the aluminum and cement industries.
All of the process alternatives studied (Volumes III-XV) were aimed at
reduction in energy consumption or conversion to less scarce fuel forms.
Since fuel consumption usually is directly related to NO emissions,
these energy-conserving process changes will result in reduction in MO
emissions. Also, processes aimed at changing the form value of fuel x
from natural gas or oil to coal were studied. These process changes
will generally result in increased NO emissions. In alumina production,
NO emissions may increase if the hydrochloric acid ion exchange method
isxused, and in the petroleum refining industry, if asphalt combusion
is incorporated.
Although the estimated change in emissions shown in Table 2 was based
on incremental capacity from 1974 to 1989 only, in some cases as alter-
native process may be retrofitted on the existing process. For example,
NO control may be achieved by installing control systems in existing
nixric plants or by use of refractory hard metal cathodes installed in
existing Hall-Heroult cells in the aluminum industry. The application
of new processes as present-day facilities are retired will further
increase or decrease the potential effect on the NO emissions shown
in Table 2. X
To give some perspective to the magnitude of HO emissions, Table 3 shows
the industrial processes category to be a relatively small emitter of
NO after electric utilities, other stationary fuel combustion sources,
ana transportation.
Should U.S. industry expand using current (base case) technology, Table A
shows that estimated controlled NO emissions in 1989 would increase by
3.0 x 10 Ib compared to NO emissions of 1.4 x 109 Ib from industrial
processes and 13.8 x 109 Ib from electric utilities in 1974 (Table 3).
However, if all U.S. industry expanded by implementing the technologies
considered here that emitted the largest amounts of NO , Table 4 shows
that the increase in NO emissions in 1989 would be 3.7 x 10 Ib, or
some 23% higher than using conventional technology. On the other hand,
if industry expanded by implementing the least HO -emitting technology,
14
-------
TABLE 3. NO NATIONWIDE EMISSION ESTIMATES (1974)
Emission source
Stationary fuel combustion
- Electric utilities
- Other
Industrial processes
Transportation
Solid Waste
Miscellaneous
TOTAL
106 Ib/yr
13,800
12,800
1,400
21,200
400
400
50,000
% of total
27.6
25.6
2.8
42.4
0.8
0.8
100.0
Source: National Air Quality and Emissions Trend Report, 1975,
EPA, Research Triangle Park, N.C.; NTIS PB-263-922.
15
-------
TABLE 4. ESTIMATED INCREASE IN CONTROLLED
NO EMISSION 1989-1974 ASSUMING
INDUSTRY EXPANDS USING PROCESS TYPES
INDICATED (10° Ib NO /yr)
A Base case
Commodity (vol no) process
Steel (III)
Petroleum3 (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
108
311
97
18
389
127
102
879
< 1
15
104
106
339
30
13
343
2,982
Using process
with largest
potential NO
emissions
336
373
97
19
389
344
267
879
< 1
15
104
148
351
30
34
343
3,730
Using process
with smallest
potential NO
x
emissions
97b
311
55
6
358
127
90
664
< 1
7
18
85
283
3
5
< 1
2,111
Volume number of industry report
•a
Assumes East Coast Refinery model applied nationally
Includes credit of 11x10 Ib NO attributed to energy saved
in dry quenching and BOP off gas collection.
°Credit for steam raised: see discussion on fertilizers in
Section 3.
16
-------
NO emissions in 1989 are calculated to increase by 2.1 x 10 Ib or
X
some 30% 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 between these extremes, with energy
(Btu) saving processes with lower NO 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 NO emissions in the industrial sector.
x
Table 5 shows our estimate of the types of processes likely to be instal-
led in the time period up to 1989 with related NO emissions from new plants
calculated for the year 1989 assuming no retirement of exisiting 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,
Noranda, Mitsubishi). If such capacity is installed, anticipated annual
NO emissions in 1989 would be 5.0 to 9.0 x 10 Ib NO /yr (Table 5) com-
pa£ed to the 13 x 10 Ib NO /yr if conventional reverberatory furnace
technology were employed (Table 4). Similar judgments were made in
other sectors to arrive at total calculated annual emissions of 2.0 to
2.8 x 10 Ib NO emitted in 1989 from new plant capacity installed in
the period 1974-1989.
Examination of the last column in Table 2 shows that greatest reduction
compared to the base case processes in Ib of NO emissions per year can
be achieved by selective implementation of new processes in:
• nitric acid manufacture NO control
x
• copper (oxygen or flash processes)
• aluminum (Alcoa chloride, refractory hard metal cathodes)
Process changes in some of the industries shown in Table 2 may be imple-
mented because of feed stock shortages (e.g., 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 development of a domestic
alumina industry based on indigenous kaolin clays. Many such processes,
based on using coal to the extent possible, would result in significantly
higher NO emissions, such as ammonia manufacture based on coal. Although
the estimated change in emissions listed in Table 2 was based on incre-
mental capacity from 1974 to 1989 only, in some cases an alternative
process, or a process modification, may replace existing capacity. For
example, in the aluminum industry, refractory hard metal cathodes may
be installed in existing Hall-Heroult cells. The application of alter-'
native processes to existing plant capacity will increase the potential
effect on NO emissions, compared to the estimated effect shown in Table
2. Further perspectives in each of these industry sectors with des-
criptions of the processes can be obtained from the individual industry
sector reports (Volumes III through XV).
17
-------
TABLE 5. ESTIMATED RANGE IN CONTROLLED NO EMISSSIONS
IN 1989 FOR NEW PROCESSES LIKELY*™ BE IMPLEMENTED
Commodity
(vol no)
Likely types of
processes to be
implemented in
new plants
Calculated range
in annual NO
x
emissions for new
plant capacity-1989
(10b Ib/yr)
Steel (III)
Petroleum (IV)
Kraft pulp (V)
Newsprint pulp (V)
Olefins (VI)
Ammonia (VII)
Alumina3 (VIII)
Coke oven, blast furnace, BOP
Various refinery options
Kraft, Rapson, alkaline-oxygen
RMP, TMP, de-inking
Naphtha, gas oil
Heavy fuel oil, coal
Bayer, leaching domestic clays
c,d
Aluminum (VIII) Hall-Heroult, aluminum chloride'
Textiles,
knit (IX)
Textiles,
woven (IX)
Cement (X)
Flat glass (XI)
Chlor-alkali (XII)
Phosphoric acid:
detergent grade
(XIII)
Copper (XIV)
Fertilizers-
nitric acid (XV)
TOTAL
Advanced aqueous, solvent
Advanced aqueous
Preheaters, coal firing
Regenerative
electric furnaces
preheaters,
Dimensionally stable anodes, new
membranes
Wet acid cleanup
Oxygen or flash processes
Various NO control technologies
97-108
311-373
55-97
6-18
358-369
155-344
90-267
592-680
< 1
6-6
18-104
85-93
283-323
3-3
5-9
1-27
2066-2822
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.
(continued)
18
-------
TABLE 5. (continued)
CWith collection of CO from BOF's.
Base case Gulf Coast Refinery model applied nationally.
19
-------
IDENTIFICATION OF CROSS-INDUSTRY TECHNOLOGY
Within the industry sectors investigated in this study, the fol-
lowing are the generic findings.
• All things being equal, HO emissions can be expected to
decrease from many processes for a variety of reasons
including:
Decreased fuel consumption in the process and
the power boiler;
Operation of processes involving combustion at
uniform and lower temperatures requiring less
excess air; and
Fuel firing with oxygen in place of air which
leads to elimination of the nitrogen coming
from the air. (For details see report on copper
industry, Volume XIV.)
• On the other hand, NO emissions may increase in several
process industries for a variety of reasons including:
Fuel switching from gas to oil to coal. (Coal
contains some fixed nitrogen and generally
requires a greater amount of excess air. Both
factors will normally lead to higher NO emissions.
For tangentially fired boilers, emission factors
calculated from data in AP-421 are 0.29 lb/10" Btu,
0.33 lb/106 Btu and 0.75 lb/10 Btu based on gas,
oil, and coal burning, respectively.);
Fuel firing with air preheating which leads to
higher flame temperature and greater NO emissions;
and x
Fuel firing with oxygen-enriched air which generally
leads to higher flame temperature and greater NO
emissions. x
R&D AREAS
With regard to NO emissions from the new technologies investigated,
the following potential areas for R&D have been identified as being
worthy of attention by industry, government agencies, or other insti-
tutions:
NO^-Related
• Develop better quantitative data on concentration and gas
flow rates from high-temperature operations involving com-
bustion, focusing on sources such as kilns, heaters, etc.
20
-------
At present, very little information is available on sources
other than power boilers, and even there the bulk of the
information is for utility boilers.
• Promote NO emission reduction at the power boiler by process
modifications, by switching to low-nitrogen feedstocks, or
by add-on controls. Of particular interest would be
fluidized bed combustion.
• Develop better definition of the environmental, health,
and ecological impacts of NO emissions with respect to
obtaining more quantitative Knowledge for establishing
appropriate emission regulations.
• Promote process alternatives aimed at reduction in energy
(Btu) requirements. Energy consumption is related to NO
emissions and therefore reduction in energy consumption
will result in lower NO emissions.
x
Process-Related
Aluminum—
• Consider materials research in the field of producing titanium
diboride cathodes suitable in quality to permit long operating
life in the Hall-Heroult cell. This development would effect
energy savings in the existing aluminum plants, thus reducing
NO emissions.
x
Fertilizers—
• For nitric acid plants, it would be beneficial in terms of energy
conservation to use processes other than catalytic reduction for
NO control. Fortunately, such other pcoesses require less capi-
tal and lower operating costs. Thus, the industry will likely
opt for such alternatives of free choice and will not require
outside influence. However, in the process examined, control
appears adequate at steady state, but not adequate during start-
up and shutdown. Also, the NO pollution control devices are
complex and may have to be shut down, even though the basic
plant continues to operate. Methods of alleviating these pro-
blems are worthy of further study. Moreover, it would be useful
to study the applicability of these new processes to control NO
emissions from sources other than nitric acid plants.
Cement—
Develop and implement a program to sample and analyze NO emis-
sions from the fluidized bed which are lower compared to those
from conventional long cement kilns. It will be useful to have
more data, particularly as a function of operating conditions.
21
-------
Moreover, it will be beneficial to study the applicability of
the fluidized bed in place of kilns in other industries and
in the place of power boilers.
Petroleum—
• Develop and implement a test program to characterize NO
emissions from asphalt combustion. Combustion in both
process heaters and in steam generators is important.
22
-------
SECTION 3
PROCESSES AilD POTENTIAL NITROGEN OXIDE EMISSIONS
BASES OF CALCULATIONS
In Volume II (page 19) where the methodology used in this study is
described, we indicated that selected State air emission regulations,
along with the Federal Government's stationary source performance stan-
dards and effluent limitation guidelines, were surveyed to:
• Establish the most probably limits of air and water
emissions, and
• Obtain a perspective of the types of pollution control
systems to be considered.
In this Section, NO control methods and emissions from the process
industries (Volumes III to XV) are reviewed. There are two general
sources of emissions: the processes ^hemselves and power boilers.
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.
Power boilers are assumed to burn coal and their NO emissions are
estimated at 18 Ib/ton of coal burned or 0.75 lb/10 Btu (12,000
Btu/lb of coal) or 7.875 x 10 Ib/kWh (based on the conversion
factor of 10,500 Btu/kWh). The New Source Performance Standard
(NSPS) limits emissions to 0.7 Ib of NO /10 Btu and may be further
lowered to 0.6 Ib of NO /10 Btu. The $0 emissions from the base
X X
case process and process alternatives are described and are summarized
for each industry. The NO emission factors are estimated, and the
effect of these factors on the incremental production from 1974 to
1989 is calculated.
NO CONTROL METHODS
x
Two approaches are available for NO control: process modifications,
including change to feed containing low nitrogen, and add-on controls,
which are further discussed below.
Power boilers are used for generation of steam and electricity. Both
on-site power boilers and utility power boilers are included.
23
-------
Process Modifications
Process modifications, generally limited to combustion processes,
include reducing flame temperature, starving the fuel for oxygen, or
both. Typical techniques for power boilers, which account for almost
50% of the NO emissions from stationary sources, include staged
combustion, fJue gas recirculation, reduced air preheat, steam or
water injection, and low excess air firing. With these techniques,
reduction in NO emissions typically range from 20 to 60% (Table 6).
While NO emissions are reduced, operating problems generated in these
systems include:
• Increased CO concentrations in flue gas,
• Lower boiler efficiency, and
• Increased corrosion in the boiler.
A further process modification which reduces NO emissions is the use
of fluidized beds. Combustion in fluidized beds occurs at more uniform
temperatures which are well below the peak temperatures found in con-
ventional boilers and occurs at low excess air. Both factors result
in lower NO^ concentrations. At present, fluidized beds have not been
developed for power boiler applications but are increasingly used in
the process industries.
.TABLE 6. HOW CURRENT NO CONTROL METHODS FARE WITH FOSSIL FUELS
X " ~^ ' . - - . . ,
N0__ Reduction
x —
Method Gas Oil Coal
Flue Gas Recirculation 60 20 Not Effective
Reduced Combustion-Air Preheat 50 40 Not Competitive
Steam or Water Injection 60 40 Not Competitive
Staged Combustion 55 40 40
Low Excess Air 20 20 20
Reduced Heat-Release Rate 20 20 20
Combined Staging, Low Excess
Air and Reduced Heat Release 50 35 40
Change to Fuel with Low % N Not Effective 40 20
Source: Assessment Overview Matrix, Monsanto Research Corp.,
EPA Contract 68-02-1874, September 1976.
24
-------
A detailed description of the use of the fluidized bed in the cement
industry (in place of the long dry kiln) is given in Volume X, page 40.
Add-On Technology
In the United States, add-on iIO control technology is in the develop-
ment stage, except for application to sources such as nitric acid
plants. Thus except for nitric acid plants, NO emissions in this report
are estimated on the basis of no add-on technology. NO concentrations
in the untreated tail gas from a nitric acid plant are In the range
of 3,000 ppm compared to a 100-600 ppm concentration in the flue gas
from combustion processes. NO control methods for nitric acid plants
are described in detail in Volume XV, page 24.
PETROLEUM REFINING INDUSTRY
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 baseline.
The reasons for using this approach are given in Volume IV, page 22.
Three configurations were selected to represent the local conditions:
East Coast, Gulf Coast, and West Coast. Among the process options
analyzed, two affect NO emissions from the refineries. These are:
X
• use of asphalt in process heaters (evaluated within
the context of the East Coast refinery cluster model); and
• use of asphalt to generate on-site electricity and
process steam (evaluated within the context of the
Gulf Coast refinery cluster model).
Further details are presented below.
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, steam
and electricity) is 1.31 x 10 Btu/day and production is equivalent to
1.19 x 101Z Btu/day (Volume IV, page 35).
The major airborne pollutants emitted by refineries have been pre-
viously identified in Volume IV, page 22. The emission factors summarized
in AP 42 were used to determine NO emissions from the base case refinery.
The NO emissions are: 10,129 Ib o? NO /day from gas-fired heaters and
boilers; 27,956 Ib of NO /day from oil-r"ired heaters and boilers; and
4,416 Ib of NO /day from fluid catalytic crackers. The total emissions
of 42,501 Ib of NO /day are equivalent to an emission factor of 35.84 Ib
A
25
-------
Q
of NO /10 Btu of refinery output. These emissions are not controlled
and no add-on control technology is available at this time.
Estimated emissions from the power boiler (off-site utility boiler)
are 6,675 Ib of NO /day, equivalent to 5.63 Ib of NO /10 Btu of refinery
x x
output.
Process Option 1 - Direct Combustion of Asphalt in Process Heaters and Boilers—
A detailed description for this alternative appears in Volume IV,
page 32. Utilizing asphalt for combustion is intended primarily to upgrade
the overall thermal efficiency within the refinery. Part of the refinery
gas (36.6%) and all of the fuel oil is displaced by asphalt. The energy
balances for the base case process and the alternative are summarized in
Volume IV, page 35. In the alternative process NO emissions are increased
due to the higher nitrogen content of the asphalt. However, the NO
emission factor for asphalt combustion is assumed to be equal to the
emission factor for oil combustion due to lack of data. The estimated
NO emissions based on this assumption from the asphalt combustion, as
shown in Volume IV, page 38, are 1,729 Ib/hour, or 41,496 Ib/day. Emissions
from the gas burned in the process heaters will be equal to 6,422 Ib of
NO /day. The emissions from the catalytic crackers (4,416 Ib of NO /day)
are not affected by the process change. The total emissions, 52,33^ Ib
of NO /day, are equivalent to 44.13 Ib of NO /10 Btu of refinery output.
X •"•
Electricity consumption in the alternative process is the same as in
the base case process and therefore the power boiler emissions are the
same, 5.63 Ib of NO /10 Btu of refinery output.
Gulf Coast Refinery
Base Case Process—
The base case refinery configuration in the year 1985 located at the
Gulf Coast is described in Volume IV. page 23. Total energy input in
the base caseqrefinery is 1,358 x 10 Btu/day and production is equivalent
to 1,197 x 10 Btu/day.
NO emissions from this base case process were developed in a similar
way as £hose for the East Coast base case refinery.
The emissions include 40,999 Ib of NO /day from heaters and boilers
and 5,694 Ib of NO /day from fluid catalytic crackers. The total emissions
of 46,693 Ib of NOX/day are equivalent to 39.01 Ib of NO /10 Btu of
refinery output.
9
Based on electricity consumption equivalent to 9.2 x 10 Btu/day
(Volume IV, page 70) the estimated emissions from the power boiler are
5.76 Ib of NO /10 Btu of refinery output.
X
26
-------
Process Option 1 - On-Site Electric Power Generation by Combustion of Asphalt—
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 alternative
shown in Volume IV, page 69.
Generation of electric power within the refinery neither conserves
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 megawatts.
This process alternative will result in increased on-site NO emissions.
NO emissions from the power boiler are 4,234 Ib/day (Volume IV, page 73),
equivalent to 3.56 Ib of NO /10 Btu of refinery products. NO emissions
from the process are not affected (39.01 Ib of NO /10 Btu of refinery
products).
Summary
WO emissions from the base case processes and the alternatives are
summarized in Table 7. There are no significant changes in the emissions.
In the direct combustion of asphalt in process heaters and boilers, the
emissions are increased by 20% as compared to the base case process.
The emissions in the alternative processes are based on the assumption
that the emission factor for asphalt combustion is equal to the emission
factor for oil combustion.
CEMENT INDUSTRY
Base Case Process - Long Dry Rotary Kiln
The base case process selected for the cement industry was the long dry
rotary kiln. Hydraulic cement is a powder made by burning lime, silica,
alumina, iron, and magnesia together in a kiln and then pulverizing
the product. The production of finished cement from raw materials
involves four steps: crushing, grinding, clinkering, and finish grinding.
In the dry process, dry grinding is done. This is very much like wet
grinding, except that no water is added and the material is ground dry,
usually at 1% moisture content or less. A detailed description of the
process is given in Volume X, page 84.
nitrogen oxides can form at combustion temperatures during clinkering
in the kiln (2,600-3,000°F). The emission factor for NO reported in
AP-42 is 2.6 Ib/ton of cement produced. A kiln producing 80 tons of
cement clinker/hour will produce about 240,000 Ib of outlet gas/hour,
or about 92,000 acfm. Based on this, the NO concentration in the exit
gas will be about 150 ppm. NO emissions from cement kilns are not
27
-------
NJ
CO
TABLE 7. ESTIMATED NO EMISSIONS - PETROLEUM REFINERY INDUSTRY
BASIS: NO ADl>-ON TECHNOLOGY FOR NO CONTROL
x
Process
(lb/109 Btu
Process
Base case:
East Coast refinery 35.84
• Direct combustion of
asphalt in process
heaters and boilers 44.13
• Flexicoking 35.84f
Base case:
Gulf Coast refinery 39,01
• Onsite electric power
by combustion of vacuum
bottoms 39.01
Base case:
West Coast refinery (a)
• Hydrocracking of
heavy bottoms (a)
• High purity hydrogen
production via partial
oxidation of asphalt (a)
Estimated
of refinery
Power boiler
5.63
5,63
5.63
5.76
3.56
(a)
(a)
(a)
emission factor
output) Change from
Total base case
41.47 0
49.76 + 8.29
41. 471" 0
44,77 0
42.57 - 2.2
(a) (a)
(a) (a)
(a) (a)
NO emissions3 (1Q6 lb/yr)_
1974 * 1989-1974__
1,244 311
373
311f
1,343 336
319
Based on increment in production from 1974-1989 =7.5 quads.
(continued)
-------
TABLE 7. (continued)
** 9
Estimated 1974 emissions, based on the total emission factor of 41.47 Ib of NO /10 Btu of
refinery output are 41.47 x 30 x 10 = 1,244 x 10 Ib and based on the emission factor of
44.77 Ib of N0x/10y Btu of refinery output are 44.77 x 30 x 10 = 1,343 x 10 Ib for East
Coast and Gulf Coast models, respectively.
Calculation assumes same emissions as base case: East Coast refinery model
No change from base case
K>
-------
controlled and no add-on control technology is available. The emissions
from the power boiler are estimated at 1.2 Ib of NO /ton of cement.
X
Process Option 1 - Suspension Preheater Process Alternative—
The suspension preheater is a modification 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 cal-
cination. Suspension preheaters typically heat cold raw feed to approximately
1,400°F and accomplish 30-40% of the total calcination or thermal decom-
position 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 and these are described in Volume X, page 19.
As reported in Volume X, page 7, the energy consumption with the
suspension preheater is lower than that of the base case process, primarily
due to a significantly lower fuel energy requirement. About 20-25% energy
is saved overall.
The concentration of nitrogen oxide found in the combustion gas from
both the long dry rotary kiln and the preheater system will probably be
equivalent because fuel is burned in the same way in both systems.
However, the quantity of nitrogen oxide generated per ton of cement
clinker produced by the suspension preheater kiln will be about 20-25%
less than that produced by the long kiln, because of the higher thermal
efficiency of the suspension preheater. Thus, the NO emissions from
the suspension preheater kiln will be about 2.0 Ib/ton of cement produced.
The electrical power consumed in the alternative process is also
reduced by 15-20% from that of the base case process due to the energy
recovery (Volume X, page 30), and therefore the emissions from the power
boiler are reduced to an estimated value of 1.0 Ib of NO /ton of cement.
X
Process Option 2 - Flash Calciner Process Alternative—
Although the design of flash calcining systems varies, the main
feature which characterizes the flash calciner rotary kiln is the flash
calcining 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) uses
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.
30
-------
The several advantages of slash calciners cited in Volume X, page 36,
include reduced nitrogen oxide emissions. Since 50-60% of the total
fuel burned in this system is burned in the flash calciner and the
temperature of the flash calciner is maintained at only about 1,500 °F,
the nitrogen oxides formed in this vessel are reported to be considerably
less than those formed in the high-temperature, free-standing flame
which is burned in a rotary kiln. Also, the flash calciner operates
at a low and uniform temperature and oxygen content. The NO emissions
are estimated in the range of 50-100 percent of those from tfte suspension
preheater alternative.
The electrical power consumed in the process is comparable to that con-
sumed in the suspension preheater alternative and therefore the estimated
emissions from the power boiler are the same — 1.0 Ib of NO /ton of
cement. x
Process Option 3 - Fluidized-Bed Process Alternative--
The only difference between the fluidized-bed, cement-making process
and the conventional process occurs in 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. If the energy
consumption in the fluidized bed and in the long kiln (Volume X, page 46)
is compared, the fuel consumption in the fluidized bed is seen to be about
10% higher. However, there is a net electricity generation in the fluidized
bed process.
Combustion conditions in the rotary cement kiln favor NO formation due
to peak flame temperatures associated with the combustion of fuel in
suspension as well as the existence of regions of high oxygen concen-
tration due to the absence of good fuel-air mixing, further enhanced by
in-leakage of ambient air to the rotary kiln seal. By contrast, the
fluidized-bed reactor operates with both a uniform temperature (constant
at 2,400°F) and oxygen distribution which prevents conditions for high
NO production from occurring.
Volume X, page 58, shows NO emissions from a fluidized-bed reactor and
a rotary kiln both being operated at 2,400°F to produce solid products.
The fuel used during this test was oil and the percent stoichiometric
air was the independent variable. The fluidized bed clearly generates
significantly lower NO emissions than the rotary kiln. At high excess
air the flue gas from thie rotary kiln contains 150 ppm of NO and the
flue gas from the fluidized bed contains 45 ppm NO . The 155 ppm N0x
concentration in the flue gas from the rotary kiln zs consistent with
the emission factor of 2.6 Ib of NO /ton of cement produced. The fuel
consumed in the fluidized bed is approximately 10% higher. Based on
the decreased NO concentration in the flue gas and 10% increase in fuel
consumption, it can be expected that the N0x emissions from the fluidized
bed will be about one-third those from the rotary kiln. Therefore, the
emissions in the flue gas from the fluidized bed will be about 0.7-0.8
Ib of NO /ton of cement produced.
X
31
-------
Since there is a net electricity generation in the fluidized bed
process, emissions at the power boiler are reduced by an estimated 0.1 Ib
of NO /ton of cement.
X
Process Option 4 - Conversion to Coal Fuel from Oil and Natural Gas
Process Alternative—
The process description using coal as a fuel in the cement kiln is
described in Volume X, page 60. NO emissions from coal combustion can-
not be estimated in this process but are expected to be higher than those
in the base case process.
NO emissions from the power boiler are not affected by switching
the fuef from oil or gas to coal in the cement kiln.
Summary
NO emissions from the base case process and the alternatives are
summarized in Table 8. The emissions are uncontrolled, and no add-on
control technology is available. Emissions from the base case process
and from the conversion to coal from natural gas and oil alternative
are essentially the same and are somewhat lower than those from the sus-
pension preheater and flash calciner alternatives. The emissions are
significantly reduced in the fluid bed alternative due to reduced emis-
sions from both the process and the power boiler. The process emissions
are reduced due to the uniform temperature distribution in the fluid bed.
OLEFINS INDUSTRY
Ethylene Production
Base Case Process - Ethylene Production Based on Ethane and Propane Cracking—
The base case technology selected for the assessment of the domestic
olefin industry was ethane and propane (E-P) cracking. A detailed des-
cription of the process of producing ethylene from ethane and propane is
given in Volume VI, page 17.
There are no NO emissions as such from the process. However, some
NO emissions are expected from the fuel used in heaters, steam generators,
ana power boilers. Natural gas is used as a fuel in the heaters and steam
generators. The NO emission factor in the olefin industry can be esti-
mated based on the ruel and electricity consumption (Volume VI, page 28).
As shown in Table 9, the emission factor is estimated at 12,45 Ib of NO /ton
of ethylene produced. Emissions from the power boiler are estimated toX
be 1.35 Ib of NO /ton of ethylene.
X
Process Option 1 - Ethylene from the Pyrolysis of Naphtha Alternative—
Pyrolysis of naphtha already accounts for 7% of domestic ethylene pro-
duction and is the predominant technology used in Europe and Japan. This
process alternative is described in Volume VI, page 22.
32
-------
u>
OJ
TABLE 8. ESTIMATED NO EMISSIONS - CEMENT PRODUCTION
BASIS: NO A§D-ON TECHNOLOGY FOR NO CONTROL
x
Process
Base case:
Long dry kiln
• Suspension preheater
• Flash calciner
• Fluidized bed
• Coal as fuel instead
of gas or oil in long
dry kiln
(lb
Process
2.6
^ 2.0
< 2.0
-v/ 0.7-0.8
2.6
Estimated
of NO /ton
Boiler
1.2
1.0
1.0
(-0.1)
1.2
emission
cement)
Total
3,8
3.0
< 3.0
~ 0,65
3.8
factor
Change from
base case
0
-0.8
-0.8
-3.15
0
NO emissions (10 Ib/yr)
x ** *
1974 1989-1974
300 104
82
82
18
104
* 6
Based on the incremental production of cement from 1974 to 1989; 27.3 x 10 tons.
**
The NO emissions based on the emission factor of 3.8 Ib/ton of cement in the year
1974 are 3.8 x 79 x 106 = 300 x 10 lb.
-------
TABLE 9. NO EMISSION FACTORS - OLEFINS INDUSTRY
BA§ES: 1 TON OF ETHYLENE AND NO ADD-ON
TECHNOLOGY FOR NO CONTROL
Ethylene production
Ethane propane Naphtha Gas-oil
cracking pyrolysis pyrolysis
Process heaters:
Natural gas, 10 Btu^
Combustion emissions
lb/106 ftJ
NO emissions, Ib/ton
ethylene
15.6
120
1.78
20.6
120
2.35
29.
120
3.
4
36
Steam regenerators:
Natural gas, 10 Btu^
Combustion emissions
lb/10^ ft
Oil, 106 Btu ^
Combustion emissions
lb/10J gal
NO emissions, Ib/ton ethylene
NOX emission factor, Ib/ton
ethylene
Boiler emissions:
Electric power, 10 Btu
NO emissions, Ib/ton ethylene
X
Total NO emissions, Ib/ton of
ethylene
16.0
700
0
10.67
12.4
1.8
1.35
13.8
0
12.
105
8.
11.
2.
1.
12.
4
68
0
2
65
7
0
11.
105
7.
11.
3.
2.
13.
0
7
1
0
0
1
*
Compilation of Air Pollution Emission Factors, Second Edition,
AP-42, published by USEPA, March 1975.
Source: Arthur D. Little, Inc., estimates.
34
-------
As in the base case process, NO is not present in the process
emissions but occurs in heaters, steam generators, and power boilers.
The emission factor is estimated at about 11.0 Ib of NO /ton of ethylene
produced (Table 9). The emissions from the power boiler are estimated
to be 1.65 Ib of NO /ton of ethylene.
X
Process Option 2 - Ethylene from the Pyrolysis of Gas-Oil Alternative—
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 producers 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.
As in the above two methods for the production of ethylene, NO
emissions are not generated by the process. However, NO emissions will
be present in the gases from the heaters, steam generators, and power
boilers. The estimated emission factor (Table 9) is about 11.1 Ib of
NO /ton of ethylene. The emissions from the power boiler are estimated
tobe 2.0 Ib of NO /ton of ethylene.
X
Gas-Oil Cracking
Base Case Process - Vacuum Gas-Oil Cracking with Conventional Technology—
The base case process, vacuum gas-oil cracking with conventional
technology, is described in Volume VI, page 109. There are no NO
emissions from this process. Emissions from the power boiler cannot be
estimated because energy consumption data are not available.
Process Option 1 - Fluid Bed Cracking of Petroleum Residues (AIST)—
This process employs a twin fluidized-bed reactor system. The thermal
cracking of heavy oils is accomplished in a fluidized bed of coke particles.
After providing the heat for cracking, the coke is transferred to the
regenerator where a portion of it is burned with air to reheat the fluidized
bed before being returned to the reaction vessel. The cracking reactor
operates at 1,290-1,560°F and the coke regenerator at 1,470-1,700°F. Both
units are operated under atmospheric pressure conditions. A description
of the process is given in Volume VI, page 119.
Since air is used in this process. there is an excellent probability
that NO formation will occur. The temperature distribution in the regen-
erator should be highly uniform which is typical of a fluidized state.
In the cement industry, NO emissions in the flue gas from the fluidized-
bed reactor operated at 2,*00°F and at high excess air are 45 ppm (Volume X,
page 58). The coke regenerator is operated only at 1,470-1,700°F. There-
fore, NO concentration in the regenerator flue gas is expected to be much
lower than 45 ppm.
35
-------
U)
OS
TABLE 10. ESTIMATED NO EMISSIONS - OLEFINS INDUSTRY
BASES: NO A&D-ON TECHNOLOGY FOR NO CONTROL
x
Estimated emission factor
(Ib NO /ton ethylene) Change from
Process Process Power boiler Total base case
Base case:
E-P process 12.4 1.4 13.8 0
• Naphtha process 11.0 1.7 12.7 - 1.1
• Gas-oil process 11.1 2.0 13.1 - 0,7
NO emissions (10 Ib/yr)
A& &
1974 1989-1974
169 389
358
369
Based on increment in production from 1974-1989 - 28,2 million tons.
**
Estimated 1974 emissions, based on the total emission factor of 13.8 Ib of NO /ton
of ethylene, are 13.0 x 13 x 105 Ibs. X
-------
Summary
The NO emissions for theylene production are summarized in Table 10.
Emissions from the base case process and alternative processes are com-
parable. The emissions are not controlled and no add-on control tech-
nology is currently available.
ALUMINA AND ALUMINUM INDUSTRY
Alumina Production
Base Case Process - Bayer Process for Producing Alumina—
The Bayer process for producing alumina is based on imported bauxite.
The process includes: digestion of ground bauxite, removal of impurities,
precipitation of aluminum trihydrate, treatment of spent liquor 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.
NO emissions may result from calcination of limestone and of aluminum
trrdydrate. NO concentrations in the flue gas may be comparable to the
concentrations ¥n the flue gas from the long dry (rotary) kiln (150 ppm)
in the cement industry (Volume X, page 58). The flue gas flow rate is
in the proportion to the rate at which fuel is consumed in a kiln. The
fuel consumed in the long dry cement kiln is equivalent to about
4.6 x 10 Btu/ton (Volume X, page 30) and estimated emissions are
2.6 lb of NO^/ton of cement. The fuel consumed in lime calcination
(0.21-0.43 x 10 Btu/ton of alumina) and alumina calcination (2.8-3.0 x 10
Btu/ton of alumina) is about 4.3 x 10 Btu/ton of alumina (Volume VIII,
page 111). Therefore, the estimated emissions from the kilns are 2.43 lb
of NO /ton of alumina.
x
Fuel consumed in the steam generators associated with the Bayer process
is equivalent to 4.4-11.3 x 10b Btu/ton of alumina (Volume VIII, page 111).
The expected emissions based on natural gas as fuel (average consumption
of 7.3 x 10 Btu/ton of alumina) are then 4.87 lb of NO /ton of alumina
(based on 275 kWh/ton of alumina, as reported in VolumexVIIl, page 19).
Process Option 1 - Hydrochloric Acid Ion Exchange Process Alternative—
This process includes dehydration of the raw clay, leaching with hydro-
chloric acid, separation of residue, purification of the solution by anine
ion exchange, crystallization of aluminum chloride, decomposition and cal-
cination to obtain alumina. A detailed description of the process is given
in Volume VIII, page 22. No commercial plant embodying this process has
ever been built (Volume VIII, page 27) and therefore the estimated emissions
represent crude numbers.
NO emissions would result from the combustion of fuel in the kilns,
ste'am generators, and power boiler. The total natural gas consumed by
the process (excluding the power boiler) is equivalent to 37.8 x 10 Btu/ton
of alumina (Volume VIII, page 31). A breakdown of fuel consumption by
37
-------
operation is not available. Assuming NO emissions to be in proportion
to the fuel consumed, we estimate the emissions would be equal to 21.4 lb
of NO /ton of alumina (NO emissions are slightly less from steam genera-
tors £han from the kilns-abased on equal fuel consumption—see base case
process for comparison). Estimated emissions from the power boiler are
1.06 lb of NO /ton of alumina (based on 134 kWh/ton of alumina, as
reported in Volume VIII, page 31).
Process Option 2 - Nitric Acid Ion Exchange Process Alternative—
This process includes: calcining the kaolin clay, leaching the cal-
cined clay with hot nitric acid, separating the clay-insolubles, removing
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. NO is present in several
waste gas streams (Volume VIII, page 38) and in the flue gas from the
combustion processes.. Again, assuming that NO emissions are in propor-
tion to the 25.3 x 10 Btu of fuel used (Volume VIII, page 40) estimated
emissions would be 14.3 lb NO /ton alumina. It should be recognized that
it has been claimed that NO emissions may be reduced somewhat by alkali
scrubbing; used for SO removal (since coal is assumed to be the fuel in
this option).
Emissions from the power boiler are estimated to be 1.1 lb of HO /ton of
alumina, based on consumption of electrical power equal to 139 kWh/ton*
of alumina (Volume VIII, page 40).
Process Option 3 - Toth Alumina Process Alternative—
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.
Gaseous emissions from the process which may include NO are off-gases
from the dehydration step and from feed and product calcination. There
is no existing plant or large pilot plant (Volume VIII, page 43), and
therefore emission data are not available. The total fuel consumed in
the process is equivalent to 9.09 x 10 Btu/ton of alumina. Assuming
an NO formation rate in proportion to the fuel consumed (comparing with
the base case process), we estimate the emission rate would be 5.72 lb
of NO /ton of alumina. Estimated emissions from the power boiler are
2.62 lb of NO /ton alumina, based on electrical consumption of 333 kWh/ton
of alumina (Volume VIII, page 50).
38
-------
Aluminum Production
Base Case Process - Hall-Heroult Process—
This process involves reduction of alumina to aluminum using electrol-
ytic cells. Many existing plants use Soderberg electrodes while new plants
are expected to use prebaked electrodes which consume less energy. A
detailed description of the process is given in Volume VIII, page 52.
The major NO emissions from this process are from the power boiler and
are estimated at 123 Ib of NO /ton of aluminum, based on the consumption
of electrical energy in existing plants (Volume VIII, page 116). 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 94.5 Ib of NO /ton of aluminum. The process emissions
from fuel combustion are difficuft to estimate from the information pre-
sented in Volume VIII (Appendix B) but are expected to be small at the
expected flame temperatures of 2000°F to 2400°F. For example, for a
copper reverberatory furnace operating in this temperature range we
estimate about 8 Ib of NO /ton of copper (see "Copper Industry" in this
report) requiring 19 to 2^ million Btu of fuel (Volume XIV, page 37).
This amounts to about 0.4 Ib NO /million Btu. Assuming NO emissions
are proportional to fuel used, £he estimated 6.6 x 10 million Btu of
fuel required in the Hall-Heroult process (Volume VIII, page 115)
would result in 2.6 Ib NO /ton aluminum.
X
Process Option 1 - Alcoa Chloride Process Alternative—
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 aluminum.
Energy consumed by the process includes No. 6 fuel oil equivalent to
24.85 x 10 Btu/ton of aluminum (Volume VIII, page 69. Part of the fuel
is used in the coking step (fluid bed operated at 1650°F), (Volume VIII,
page 57). The expected NO emissions from this source are expected to
be minor. A breakdown of £he fuel consumption is not available and,
therefore, NO emissions from other sources, such as the dryer and calciner,
cannot be estimated. However, because of the relatively low temperature
of these operations ( 1600°C, Volume VIII, page 61) the emissions
should be small compared to those from the power boiler. Energy for
casting should be comparable to the base case of about 4 x 10 Btu/ton
aluminum (Volume VIII, page 115). Assuming emissions to be proportional
to fuel used as in the base case above, we calculate 1.6 Ib NO /ton
aluminum for casting. Based on electricity consumption of 1,500 kWh/ton
of aluminum (Volume VIII, page 69) we estimate emissions from the power
boiler to be 83 Ib of NO /ton of aluminum.
39
-------
Process Option 2 - Refractory Hard Metal Cathodes Process Alternatives—
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 production and reduce
energy consumption (Volume VIII, page 74). A detailed process description
is given in Volume VIII, page 68.
NO emissions are expected from combustion processes and the power
boiler. The fuel consumption is equivalent to 6.1 x 10 Btu/ton of
aluminum (Volume VIII, page 76). Assuming as we did for the base case,
0.4 Ib NO /10 Btu of fuel, we calculate process emissions to be 2.4 Ib
of NO /ton aluminum. Estimated emissions based on power consumption of
12,488 Btu/ton of aluminum (Volume VIII, page 76) are 98.3 Ib of NO /ton
of aluminum from the power boiler.
Process Option 3 - Combination of the Toth Clay Chlorination Process and
the Alcoa Chloride Process Alternative—
The details of the combined process are given in Volume VIII, page 79.
This combined process has all of the effluent probelms of the Toth alumina
process plus some of the effluent problems of the Alcoa process.
The estimated emissions from the Toth process include 5.72 Ib of NO /ton
of alumina. For aluminum production, 1.93 tons of alumina/ton of aluminum
are required (Volume VIII, pages 50 and 81). Therefore, emissions are
estimated to be 11.0 Ib of NO /ton of aluminum.
We estimate the consumption of electrical energy in the combination
process to be 10,637 kWh/ton of aluminum (Volume VIII, page 81), resulting
in emissions of 83.8 Ib of NO /ton of aluminum.
X
Thus, the total emissions from the alternative process are 11.0+83.8=
94.8 Ib of NO /ton of aluminum. These emissions are lower than the
emissions from combined Bayer & Hall process (112.8 Ib of NO /ton of
aluminum for new plants and 141.3 Ib of NO /ton of aluminum for existing
plants).
Summary
The NO emissions from the base case processes and alternatives are
summarized in Table 11. In the alumina industry, a significant fraction
of the emissions result from fuel combustion either in a process or in
steam generators, except in the case of the nitric acid leaching process.
(The emissions from this process cannot be estimated.) Emissions are
considerably increased in the hydrochloric acid leaching process. NO
emissions from this process are not controlled and no add-on control x
technology is available.
In the aluminum industry, the process emissions are small compared to
those from the power plant. The electrical energy used per ton of
aluminum is significantly higher compared to electrical energy consumption
40
-------
in other industries. NO emissions from the power boiler are estimated
to range from 80 to 125 Ib/ton of aluminum (Table 11). In the alternative
processes, the NO emissions are reduced by 20 to 30%.
GLASS INDUSTRY
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 as
follows:
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 Volume XI,
page 19. A glass-melting furnace has both particulate and gaseous emissions
which must be controlled.
The major gaseous pollutant is nitrogen oxide which is formed during the
combustion of natural gas. Because of the high temperatures required in
the furnace, the gas combustor must be operated at temperatures favorable
to nitrogen oxide formation. The highest temperature in the melter is
about 2,920°F. The NO emission factor for the glass melting furnace is
8 Ib/ton of glass produced, as shown in Volume XI, page 27. The estimated
NO emissions from the power boiler to generate electricity are 0.15 Ib/ton
ofxglass.
The only viable control technique for nitrogen oxide at the present time
is maintaining the proper combustion conditions in the furnace. For
example, low-excess air firing and no air preheating both produce minimum
nitrogen oxide emissions. As is the case with utility boilers, the control
of nitrogen oxides is based or modification of combustion conditions.
Process Option 1 - Coal Gassification Alternative—
Coal gasification processes include, in some variation, the following
steps: coal handling and storage, coal preparation, gasification, oxidant
feed facilities, and gas cleaning. The gas produced from coal gasification
is used as a fuel source in the glass furnace. The 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 gas
produced in the coal gasifier is expected to contain very little or no
NO . Most of the nitrogen is in the reduced form as NH, and is scrubbed
41
-------
TABLE 11. ESTIMATED NO EMISSIONS - ALUMINA AND ALUMINUM INDUSTRY
BASIS: NO A$D-ON TECHNOLOGY FOR NO CONTROL
X
N)
Estimated emission factor
Process
Alumina
Base case:
Bayer
• Hydrochloric acid
ion exchange
• Nitric acid ion
exchange
• Clay chlorination
(toth)
Aluminum
Base case:
Hall-Heroult
(current practice)
• Hall-Heroult (new)
• Alcoa chloride
• Refractory hard metal
cathode
Base case: A
Bayer and Kall-Heroult
• Clay chlorination (toth)
and aloca chloride
(lb
Process
7.3
21.4
14.3
5,72
^ 2.6
^ 2.6
^ 1.6
% 2.4
M.6.7
11.0
NO /ton of product) Change from
?ower boiler Total base case
2.17
1.06
1,09
2.62
123
94,5
83.0
98.3
127.2
83.8
9.47 0
22.46 + 12.99
15.39 5,92
8,34 - 1.13
125.6 0
97.1 - 28,5
84.6 - 41.0
100.7 - 24.9
143.9 701f
94.8 - 49.1
NO emissions* (106 Ib/yr)
x ** *
1974 1989-1974
72.9 102
267
108
90
628 879
680
592
705
1007
664
(continued)
-------
TABLE 11. (continued)
*
Based on increments in production from 1974 to 1989 — 10,75 million tons of alumina/year or
7.0 million tons of aluminum/year.
**
Estimated 1974 emissions for,alumina, based on the emission factor of 9.47 Ib of NO /ton of
alumina, are 9.47 x 7.7 x 10 = 72.9 x 10 Ib of NO from alumina production; for aluminum
NO emissions based on the emission factor of 125,6 Ib of NO /ton of aluminum, are 125.6 x
5 x 10 = 628 x 10 Ib of NO from aluminum production. The ratio of Al 0 and Al production,
1.54 is different from 1.93 (reported in Volume VIII, p. 54) because imported alumina is used
for production of Al at some plants.
Bayer Process plus Hall-Heroult (existing) is used for comparative analysis based on 1.93
tons alumina used per ton aluminum.
-------
out in the gas-cleaning system. The only difference between the base case
process and the heating of the glass furnace using gas from a coal gasifier
is that the exhaust gas from the coal gasifier case will be slightly
greater in volume than that of the base case. There is about a 10% dif-
ference in the gas flows between the coal gasification case and the base
case. As a consequence, the NO emissions will be increased by about 10%
compared to those from the basexcase process and will amount to an
estimated 8.8 Ib NO /ton glass. The NO^ emissions from the power boiler
are comparable to tftose from the base case process, about 0.15 Ib/ton of
glass.
Process Option 2 - Direct Coal-Firing Process Alternative—
In this option, pulverized coal is used directly in burners to supply
the energy. The details of the process are given in Volume XI, page 45.
The main difference between the base case process and direct coal firing
is that coal is a slightly more difficult fuel to burn and will require
a greater amount of excess air to achieve proper combustion. The volu-
metric gas flow rate of the effluents is expected to be the same as the
volumetric flow rate from the coal gasifier system. Thus we estimate that
will be more than 8.8 Ibs NO found in process option 1. However, we
believe it should be less than the 11.2 Ib NO /ton glass found in process
option 3. As a result we use an average value of 10 Ib NO /ton glass
for process emissions in this option. The NO emissions from the power
boiler are comparable to those from the boilers in the base case process
about 0.15 Ib/ton of glass.
Process Option 3 - Coal-Fired Hot Gas Generation (COHOGG) Process Alternative
This system generated 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 mixture 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 process are given in Volume XI, page 48.
The gas volume to the glass furnace is higher with the COHOGG process
because of the efficiency losses inherent in the system. The operating
temperatures in the glass furnaces are the same, and therefore pollution
control problems will be the same. The NO emissions are expected to
increase directly with the gas volume and nitrogen in the coal. The
volumetric gas flow from the COHOGG process is estimated to be 40%
higher than the volumetric gas flow rate from the base case process.
Consequently, estimated NO emissions of at least 11.2 Ib of NO /ton
of glass are generated. Tn*e NO emissions from the power boiler are
comparable to those from the base case process, about 0.15 Ibs/ton
glass.
44
-------
Process Option 4 - All-Electric Melting Alternative—
Molten glass can be heated by the passage of an electric current.
Both the design and the operation of an all-electric, glass-melting fur-
nace differ greatly from those of the typical natural gas-fired, regenerative
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 electrically heat glass-melting furnaces results in a
shift in the environmental problems from the furnace to the electric
power plant. In this case the only exhaust from the glass-melting furnace
is from the decomposition of carbonates, sulfates, nitrates, etc., in
the glass batch. The NO emissions will be greatly reduced. In the
fiberglass industry, for example, NO emissions have been reduced from
4.5 Ib/ton to 0.25 Ib/ton (ADL, 1976^. Data for the emissions from the
glass industry are not available. However, the emissions are estimated
to be less than 1.0 Ib/ton of glass. The NO emissions from the power
boiler are increased to 6.14 Ib/ton of glassxdue to the increased use
of electricity.
Process Option 5 - Batch Agglomeration/Preheating Alternative—
Batch preheat is an energy-conserving technology relating to a furnace
modification rather than a method of furnace heating. Hence, this techno-
logy 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.
By improving the thermal efficiency of the furnace, this technology
reduces the fuel requirement per ton of glass, thereby reducing the
exhaust volume from the glass melting furnace. The reduction in gas
volume correspondingly reduces NO emissions. The gas flow rate is
decreased by about 20% and therefore the NO emissions are reduced by
about 20% to approximately 6.4 Ib/ton of glass. The NO emissions from
the power boiler are comparable to those from the base case process,
about 0.15 Ib/ton of glass.
Summary
The NO emissions from the base case process and the selected processes
are summarized in Table 12. In general, NO emissions from the
furnace remain essentially the same, except in the case of the COHOGG
process alternative. In the electric furnace alternative, there is a
shift in the source of NO emissions from furnace to power boiler. The
NO emissions from the glass furnace are not controlled and no cost-
efiective control technology currently exists.
COPPER INDUSTRY
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
45
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TABLE 12. ESTIMATED NO EMISSIONS FROM GLASS FURNACES
BASIS: NO Affo-ON TECHNOLOGY FOR NO CONTROL
x
Estimated emission
Process
Base case :
Natural gas firing
• Coal gasification
• Direct coal firing
• Coal-fired, hot gas
generation
• Electric melting
• Batch preheat with
natural gas firing
(lb
Process
8.0
% 8.8
10.0
11.2
< 1.0
* 6.4
NO /ton of
x Boiler
0,15
0,15
0.15
0.15
6.14
0,15
glass)
Total
8.15
8.95
10.15
11.35
7.14
6.55
factor
Change from
base case
0
+ 0.8
+ 2.0
+ 3,2
- 1.01
- 1,6
* ft
NO emissions (10 Ib/yr)
** *
1974 1989-1974
236 106
116
132
148
93
85
Based on increment in production from 1974 to 1989 - 13 million tons/year.
** 6
Estimated 1974 emissions, if all plants emit 8,15 lb of NO /ton of glass are 8.15 x 29 x 10 =
236 x 106 Ib/year. X
-------
of molten sulfides from the reverb is converted to blister copper in
converters. A detailed description of this process is given in Volume
XIV, page 23.
Large volumes of gas are produced in the reverberatory furnace and con-
verter. NO emissions data from these sources or from alternative pro-
cesses are not available. However, approximate estimates have been
developed based on comparison with other processes.
The melting temperature of the matte in the reverberatory furnace is
2,000°F. The average gas temperature in the reverberatory furnace is
2,250°F, varying from 2,100°F to flame temperature. There is about 100%
excess air. Temperature distribution in the furnace is not uniform,
and therefore NO formation may be promoted except that reducing conditions
are present. The NO concentration in the flue gas from the long dry
cement kiln operating at an average temperature of 2,400°F, with 100%
excess air, and nonuniform temperature distribution is 150 ppm (Volume X,
page 58). The gas flow rate from the reverberatory furnace is 82,000
scfm (Volume XIX, page 26) and the smelter capacity is 100,000 tons of
anode copper/year. Therefore, assuming 150 ppm NO concentration in
the flue gas from the reverberatory furnace, we estimate the emissions
to be equivalent to 7.85 Ib of NO /ton of copper.
X
The melting point of the copper is 2,129°F and the average operating
temperature of the converter is 2,300°F. Air is blown through the
metal for oxidation. The temperature distribution in the gas phase is
very uniform. NO emissions from the converter are again not available,
but may be estimated by comparing it with other processes. The NO con-
centration in flue gas from a fluidized bed in the cement industry
operating at 2,400°F uniform temperature and high excess air is 45 ppm
(Volume X, page 58). The gas flow rate from the converter is 38,800
scfm (Volume XIV, page 26), assuming that all acid plant tail gas is
from the converter and that smelter capacity is 100,000 tons of anode
copper/year. Therefore, assuming 45 ppm NO concentration in the flue
gas from the converter, we estimate emissions to be equivalent to 1.11
Ib of NO /ton of anode copper.
X
Both types of roasters (multiple hearth and fluidized bed) usually
operate at around 1,200°F. We expect that NO concentration in the gas
from the roaster will be very low.
The estimated emission factor based on the above method is 7.85+1.11=
8.96 Ib of NO /ton of copper from the process. The electricity consumed
in conventional smelting varies from 347 kWh/ton in green feed smelting
to 441 kWh/ton in calcine smelting. This will result in emissions at
the power boiler equal to 2.73 to 3.47 Ib of NO /ton of anode copper.
X
47
-------
Process Option 1 - Outokumpu Flash Smelting Process Alternative—
The flash smelting alternative combines the separate roasting and
smelting operations of conventional copper extraction into one combined
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 manufacture.
A detailed description of the process is given in Volume XIV, page 41.
A direct oil-fired rotary kiln is used to dry the charge thoroughly before
it is fed to the concentrate burner. The NO concentration in the flue
gas from the kiln should be comparable to the NO concentration in the
flue gas from the wet kiln in the cement industry. However, the gas flow
rate per ton of feed should be higher in the cement kiln, because there
the material is not only dried but preheated, calcined, and sintered.
As an approximation, the difference in energy consumption in the wet and
dry kilns in the cement industry may be assumed to be equal to the energy
required for drying. This is roughly 20 to 50% of the energy consumed in
the kiln (Volume X, page 98). Some 1.6 tons of feed to the cement kiln
is required per ton of cement. The concentration of copper in the feed
is only 15 to 30% and, therefore, 3 to 7 tons of feed to the kiln are
required per ton of copper. The NO emissions from the wet cement kiln
are 2.6 Ib/ton of cement. Consequently, the emissions from the kiln in
the alternative process are estimated at 2.6 Ib of NO /ton of anode
copper.
The gas temperature in the concentrate burner is about 2,500°F and the
oxygen concentration in the flue gas is about 0.5%, but it may be as
high as 2%. Conditions in the burner are reducing, as was the case in
the conventional reverberatroy furnace. The NO concentration in the
flue gas should be low. The NO concentration in the flue gas from a
cement kiln (Volume X, page 58)Xoperating at 2,400°F and low excess air
is 45 ppm. The NO concentration in the flue gas from the concentrator
may be on the same order (operating at reducing conditions but at a
slightly higher temperature). Using a gas flow rate from the concentrator
of 55,000 scfm (based on 100,000 tons of anode copper/year), the emission
rate from the concentrator is estimated as 1.581b of NO /ton of anode
copper.
The emissions from the converter in the flash smelting alternative would
be comparable to or less than the emissions from the converter in the base
case process, because the gas volume may be reduced due to the high grade
matter (Volume XIV, page 43). Emissions from the converter in the base
case process are 1.11 Ib of NO /ton of anode copper.
X
The total emissions from the flash smelting process alternative are esti-
mated at approximately 5.3 Ib of NO /ton of anode copper. The NO emissions
from the power boiler are estimated at 2.88 Ib of NO /ton of anode copper
(based on 366 kWh/ton of anode copper, Volume XIV, page 52).
48
-------
Process Option 2 - Noranda Process Alternative—
The Noranda process combines in a single reactor the three operations
of roasting, smelting, and converting of copper concentrates. 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 furnace to the converter. A
detailed description of the process is given in Volume XIV, page 55.
The gaseous emissions from the Noranda process include 55,000 scfm
from the acid plant (based on 100,000 tons of anode copper/year, Volume
XIV, page 61). The acid plant tail gas includes 75% dilution air
(Volume XIV, page 60). Therefore, the gas flow from the reactor is
31,500 scfm and contains 7.5% oxygen (Volume XIV, page 56). The reactor
operates on air (without enriching with oxygen). Operating conditions
favor NO formation (see the figure in Volume XIV, page 56). The NO
concentration in the reactor flue gas would be comparable to the NO
concentration of 150 ppm in the flue gas from a long dry cement kiln
having 7.5% oxygen (Volume X, page 58). Thus, the NOX emissions are
estimated at 3.0 Ib of NO /ton of anode copper.
The NO emissions from the power boiler are the same as in the
Outokumpu flash smelter process, 2.88 Ib of NO /ton of anode copper.
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 in the
matte and make blister copper, and a slag-cleaning furnace. Intermediate
products in the molten state move continuously among the respective
furnaces which are thus functionally connected with each other. A detailed
description of the Mitsubishi process is given in Volume XIV, page 71.
The total gas flow rate from the smelting, slag-cleaning, and con-
verting furnaces is 55,000 scfm (based on 100,000 tons of anode copper/
year). Oxygen is used to enrich the air in this process. The operating
temperatures and the breakdown of gas flow rates from individual furnaces
are not reported, and therefore, NO emissions cannot be estimated but
will probably be of the same order of magnitude as in the Noranda or
Outokumpu processes namely about 3 to 5 Ib NO /ton copper.
X
The emissions from the power boiler are comparable to those from the
power boiler for the Outokumpu flash smelting process—about 2.88 Ib of
NO /ton of anode copper.
Process Option 4 - The Use of Oxygen in Smelting—
Copper smelting can be conducted with pure oxygen or by using oxygen-
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 Outokumpu
49
-------
flash smelting. Oxygen enrichment results in the reduction of emission
volume; however, the operating temperatures are generally increased.
Also, the total NO formation rate is increased (Volume XIV, page 84).
The emission rates due to oxygen enrichment in this alternative cannot
be estimated due to the limited data.
If pure oxygen is used, then NO emissions are reduced to zero,
except those formed due to nitrogen in the fuel and fuel materials.
Process Option 5 - Arbiter Process—
The Arbiter process is a hydrometallurgical leaching process (dis-
cussed in Volume XIV, page 95-106). N0x process emissions are estimated
to be neglible. However, 2.5 tons of oxygen and 3,000 kWh of electric
energy are used per ton of copper. Since oxygen generation requires
about 360 kWh/ton of oxygen, total electric energy requirements are
3,900 kWh/ton copper (=3000 + 2.5 x 360). Thus, NO emissions from the
power boiler are estimated to be 30.71 Ib per ton or copper. In addition,
20,000 Ib of purchased steam are required. If we assume that low pressure
process steam for the Arbiter process is obtained as a byproduct from the
power boiler, there would, of course, be no incremental NO emissions,
since more than enough steam is available. (If the steam is generated
from a separate on-site boiler, additional NO emissions will be created
from raising 20,000 Ib of process steam requiring 1.22 x 10 Btu of
fuel/1000 Ib of steam (Volume II, page 17). These NO emissions are cal-
culated to be 18.3 Ib/ton copper, based on 0.75 Ib of NO emissions per
million Btu.)
Summary
The NO^ emissions from the base case copper smelting process and the
selected alternative processes are summarized in Table 13. The use of
oxygen-enriched air in furnaces is not included in the summary table
because emission data from the oxygen enrichment alternative are not
available. The recovery of slag alternative (Volume XIV, page 85) is
also not included in the summary table because it has no NO emissions.
The alternative processes for smelting reduce NO emissions3^ 30-50
percent. The NO emissions from the Mitsubishi process are not available
but would probably be lower than those from the base case process. These
estimates are based on comparison with other processes and, therefore,
represent first approximations only.
FERTILIZER INDUSTRY
Base Case Process - Nitric Acid Industry Without NO Emission Control
The base case process in the nitric acid industry was a process with
no NO emission control. Nitric acid is produced by oxidation of ammonia
in a reactor, usually under high pressure and high temperature over a
platinum catalyst, forming nitric oxide. The gaseous products from the
reactor and oxygen are cooled to form NO and are sent to an absorption
tower to form the acid product. In the pressure process (base case
50
-------
TABLE 13. ESTIMATED NO EMISSIONS - COPPER SMELTING
BASIS: NO A&>-ON TECHNOLOGY FOR NO CONTROL
Process
Base case:
Conventional smelting
• Outokumpu flash
smelting
• Noranda process
• Mitsubishi process
• Arbiter process
Estimated emission factor ^ ,
rih NO /ton nf inodr rcrancr1) rhanot f V ™ N°T.- emissions (10 Ib/yr)
V.LD "i"* / LUII uo. aiiuuc i_uppi_Ly cnange ii om x . . '
Process Power boiler Total base case 1974 1989-1974
^ 9.0 2.7-3.5 ^12 0 19,4 13
% 5.3 2.9 ^8.2-4 — 9
^ 3.0 2,9 ^5.9-6 -- 6
^3 to 5 2.9 ^6-8 - 4 to 6 ~ 4-7
small 30.7 30,7 19 — 34
*
Based on increment in production from 1974 to 1989 "1.1 million ton/year.
**
Estimated 1974 emissions,
are 12.1 x 1.6 x 10b = 19
based on the emission factor of 12.1 lb of NO /ton of anode copper
.4 x 10b Ib/year. X
-------
process), the gas is reheated for power recovery purposes and discharged
to the atmosphere at 400-500°F. In the atmospheric system, tail gas
discharged to the atmosphere is cold. The tail gas is reddish-brown.
The intensity of the color depends on the concentration of nitrogen
dioxide present. Concentrations of 0.13% to 0.19% and higher by volume
of nitrogen dioxide produce a definite color in the exit plume.
Effluent gas containing less than .03% nitrogen dioxide is essentially
colorless.
Uncontrolled and controlled NO emissions from nitric acid plants are
given in Table 14 and are shown in Figure 1. Emissions are in the range
of 50-55 Ib/ton of 100% acid. The tail gas from the pressure process
may be considered to have the following average composition.
Total Nitrogen Oxides, NO + NO^ 0.3%
Oxygen: 3%
H20: 7%
Nitrogen: Balance.
In the pressure process, steam is generated from the tail gas, and there-
fore emissions at the power boiler are reduced by 0.53 Ib of NO /ton of
acid, provided this steam is used elsewhere in the plant.
In the United States, the limits on nitric oxide and nitrogen dioxide
(commonly considered together as NO ) emitted from nitric acid plants
are 3 Ib/ton of 100% acid for new plants (Federal standard) and 5.5 Ib/ton
of 100% acid on the average (state standards) for old plants (Volume XV,
page 29). This is equivalent to approximately 200 and 400 ppm, res-
pectively, by volume in the tail gas.
Process Option 1 - Catalytic Reduction Process Alternative—
In the catalytic reduction process, the residue tail gas from the
absorber, essentially nitrogen, is demisted and then reheated with steam.
The hot tail gas is then further heated by passing it through the shell
side of the heat exchanger train utilized to cool the hot process gas.
Before being introduced into the hot gas expander, the reheated tail gas
is passed through a chamber that contains a catalyst. The oxides of
nitrogen are reduced to N and 0^ in the combustor. Natural gas or
hydrogen is used as a fuel. A detailed description of the process is
given in Volume XV, page 33. The stack effluent is usually clear and
colorless, indicating reduction in all nitrogen dioxide to nitric oxide
at least to less than 300 ppm. The emission factor is less than 7 Ib of
NO /ton of acid and varies with the fuel used in the combustor, as shown
inxTable 15. Part of the energy consumed in the combustor is recovered
in the expander. Therefore, as in the base case process, emissions at
the power boiler are reduced by 0.87 Ib of NO /ton of acid, provided the
steam generated is used elsewhere in the plant.
52
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TABLE 14. ESTIMATED NO EMISSIONS FROM NITRIC ACID PLANTS
X.
Control Emission NO
Process efficiency (%) (ppm in flue gas) (Ib/ton)
Uncontrolled
Catalytic reduction
(natural gas-fired)
Catalytic reduction
(hydrogen-fired)
Catalytic reduction
(75% hydrogen, 25%
natural gas)
Molecular sieve method
Extended water absorption
(Grande Paroisse)
CDL/Vitok process
Masar process
NaOH-water absorber
0
78-97
97-99.8
98-98.5
> 98.5
> 93
> 94
93-97
91
3,000
200-300
0-100
45-65
< 50
< 200
< 175
100-200
270
50-55
2-7
0-1.5
0.8-1.1
< 0.9
< 3.5
< 3.0
1.75-3.5
4
Based on 100% acid production.
53
-------
1.200
1.000
800
O _
LU D
t- O
< f
D a
O ^
si
o> a
LU
9S
ss
LU Q
S 2
O LU
£§ 400
< 2
>— u}
o <
K 200
BASED ON H!) sclm OF EFFLUENT
PER DAILY TON OF ACID
100
200
300
400
PRODUCTION OF MITRIC ACID, ions/day
(100% HN03 BASIS!
Source: "Atmospheric Emissions fiom Nitric Acid Manufacturing Processes,'
USHEW. Publication No. 99.9-AP 27. I960.
Figure 1. Total NO (Calculated as NO )/Hour vs Daily
Production of Nitric Acid
54
-------
Option 2 - Molecular Sieve Method Alternative—
This method is based on the principle of absorption, oxidation, and
regeneration of the molecular sieve. An oil-fired heater is used to pro-
vide heat for regeneration. The process has high efficiency for removal
of NO gases. The NO outlet concentration is generally below 50 ppm
(0.9 $b of NO /ton ofXacid). A detailed description of the method is
given in Volume XV, page 36.
Steam and electrical energy are used in the molecular sieve process.
The estimated NO emissions generated from the power boiler are 0.22 Ib/ton
of acid.
Option 3 - Extended Water Absorption, or Grande Paroisse, Process Alternative—
In the extended water absorption, or Grande Paroisse, process, tail
gas from the primary absorption tower which typically contains between
1,500 and 5,000 ppm NO is routed to the secondary absorber for additional
extended absorption of NO . The tail gas is contacted countercurrently
with the process water and additional acid produced in the secondary
absorber is pumped to the primary absorber. A startup acid pump is
included to circulate a large quantity of weak acid through the secondary
absorber to fill the absorber tray as quickly as possible during startup.
A detailed description of the process is given in Volume XV, page 37.
The process may be used in a new plant, or may be retrofitted in an
existing plant, and will meet the NO standard.
x
The estimated emissions from the Grande Paroisse process are 3.5 Ib
of NO /ton of acid (200 ppm NO in the flue gas). The emissions from the
power ooiler are 0.06 Ib of NO /ton of acid.
Option 4 - CDL/Vitok Process Alternative—
This process uses the principle of scrubbing tail gas with nitric
acid under conditions which reduce the nitrogen oxides to the desired
level. Both physical absorption and stripping and chemical oxidation
absorption are used. The reaction may be catalyzed in some applications to
reduce the size of the equipment required. No chemicals other than water
and nitric acid are required for the process, thus avoiding additional new
waste disposal problems. The detailed description of the process is given
in Volume XV, page 38. The N0x content in the tail gas is less than 3 Ib/
ton of nitric acid (175 ppm NO in the flue gas). The emissions from the
power boiler are estimated at 0.21 Ib of NO /ton of acid.
X
Option 5 - Masar Process Alternative—
The Masar process, as applied to nitric acid plants, takes the tail
gas from the exit of the absorption tower and passes it through a gas chiller
before it is cooled. During the cooling operation, condensation occurs
with the formation of nitric acid. The chilled gas and condensate passes
into the Masar absorber where additional N0x is removed from the gas. A
detailed description of the process is given in Volume XV, page 39. The
55
-------
tail gas meets regulatory standards with regard to NO abatement. The
NO in the exhaust tail gas from one operating plant has been reported to
be between 100-200 ppm for a one-year period (1.75-3.5 Ib of NO /ton of
acid). The estimated emissions from the power boiler are 0.09 Ib of
NO /ton of acid.
X
The spent Massar solution contains urea and ammonium nitrate in the
form of a weak solution. The solution can be utilized in preparing liquid
fertilizers. Companies that do not make liquid fertilizers may sell the
solution to companies that do or to farmers for direct application.
Option 6 - Alkali Scrubbing Process—
Alkaline scrubbers also reduce the emission of nitrogen oxides effec-
tively. As reported in Volume XV, page 42, in the two-stage sodium hydroxide
water scrubber, NO can be reduced by 91%. This method of control is used
only if production of sodium nitrate is desirable.
Summary
The NO emissions from the base process and alternative processes are
summarized in Table 15. All the NO control methods can be used to
reduce the emissions to less than 5 Ib/ton of nitric acid produced, or
equivalent to 300 ppm of NO in the flue gas. (The emissions from the
power boiler are small.) Tn*e economics, as reported in Volume XV, page
34, favor the CDL/Vitok and Masar processes. Also, the energy require-
ments in the extended water absorption, CDL/Vitok process, and the Masar
process are reduced compared to energy consumed in the catalytic com-
bustor. In general, the NO emissions are reduced by more than 90% in
each of the above alternative processes.
AMMONIA
The base case technology is the production of ammonia, based on steam
reforming, using natural gas as the feedstock. In the alternative
processes, ammonia is produced via coal and heavy oil feedstocks.
Base Case Process; Ammonia Production Based on Gas Feedstock
The four major operations in the manufacture of ammonia include: gas
preparation, hydrogen production, gas purification, and ammonia synthesis.
Gas preparation is typically done by steam reforming of
natural gas to produce carbon monoxide and water. In the second step,
the product gases are catalytically shifted to carbon dioxide and hydrogen,
and the carbon dioxide is removed from the gas stream. Ammonia is then
synthesized by the reaction between hydrogen and nitrogen (produced from
atmospheric air) at elevated temperatures and pressures in the presence
of a catalyst. The ammonia synthesis loop purge gas is recycled to the
reformer where it is burned with natural gas fuel. A detailed description
of the base case technology is presented in Volume VII, page 25.
56
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TABLE 15. ESTIMATED NO EMISSIONS - NITRIC ACID INDUSTRY
BASIS: NO A$D-ON TECHNOLOGY FOR NO CONTROL
Estimated emission factor
Process
Base case:
Uncontrolled NO
emissions
• Catalytic combustor
Natural gas-fired
Hydrogen- fired
75% hydrogen 25%
natural gas
• Molecular sieve
• Grande Paroisse
• CDL/Vitok
• Masar
(Ib/NO /ton of acid)
Process Power boiler Total
52.5
5
'X* 1
*v/ 1
•x- 0.9
* 3.5
* 3.0
•\» 2.5
- 0.5
- 0.9
- 0.9
- 0.9
0,2
0.1
0,2
0.1
52.0
4.1
0,1
0.1
1.1
3.6
3.2
2.6
NO emissioi
Change £10111 x ^
base case 1974
426
- 47.9
- 51.9
- 51.9
- 50.9
- 48.4
- 48.8
- 49.4
is* (106 Ib/vr
1989-1974*
343
27
0.7
0.7
7.3
24
21
17.2
* 6
Based on the incremental production of acid from 1974 to 1989; 6.6 x 10 tons.
**
The NO emissions based on the emission factor of 52.0 Ib/ton of acid in the year 1974
are 52?0 x 8.2 x 10b = 426.4 x 10° Ib.
-------
Process fuel requirements include 12.6 MM Btu/ton of natural gas which
is used to fire the steam reformer (Volume VII, page 27). Steam is
generated by heat recovered from the flue gas leaving the primary reformer
and from the process gas leaving the secondary reformer. Auxiliary gas-
fired boilers are used to generate steam only during startup. Power
requirements are estimated at 95 kWh/ton of ammonia (Volume VII, page 27).
NO emissions from the natural gas-fired reformer—based on the
emissions factor of 0.29 lb/10 Btu of natural gas—are estimated to be
0.95 Ib/ton of ammonia. This emissions factor includes NO from the
natural gas utilized as fuel for the reformer and includes "NO gas used
as feedstock, since the ammonia synthesis loop purge gas which contains
the NO from the feedstock is burned in the primary reformer.
NO emissions from the coal-fired power boiler are estimated to be
0.36 Ib/ton of ammonia.
Process Option 1 - Ammonia Production Based on Coal Gasification—
Synthesis gas for ammonia production is obtained from the coal feed-
stock by freeing the hydrogen that is present in the coal and by reacting
the carbon in the coal with steam to produce additional hydrogen and carbon
monoxide. As in the base case process, the synthesis gas is shifted to
a hydrogen and carbon dioxide product; the gases are purified; and ammonia
is synthesized from nitrogen and hydrogen gases. The details of this process
option are described in Volume VII, page 37.
An auxiliary coal-fired boiler is required for this process alternative.
Fuel requirements (coal) are estimated at 5.22 x 10 Btu/ton of ammonia.
In addition, electrical power requirements have been estimated to be
1.70 x 10 Btu/ton, equivalent to 162 kWh/ton (Volume VII, page 95).
NO emissions from the auxiliary boiler, based on the emission factor
of 0.75Xlb/NOx x 10 Btu, are estimated to be 3.92 Ib/ton. In addition,
NO is also produced during gasification from the nitrogen contained by
the coal. Since about 1.33 tons of,coal feedstock are required per ton
of ammonia (equivalent to 28.9 x 10 Btu/ton of ammonia), then NO emissions
are estimated at 21.68 Ib/ton of ammonia.
NO emissions from the coal-fired power boiler are estimated at
1.28 Ib/ton of ammonia.
Process Option 2 - Production of Ammonia from Heavy Fuel Oil—
In the production of ammonia from heavy fuel oil, synthesis gas is
produced from the fuel oil by the partial oxidation and steam reformation
of the hydrocarbon. The carbon monoxide and steam in the product gases is
subsequently reacted catalytically to produce additional hydrogen. The
acid gases, carbon dioxide, and other impurities are removed from the hydro-
gen stream. Ammonia is finally synthesized from the hydrogen and nitrogen.
An air separation plant supplies nitrogen for the ammonia synthesis step,
58
-------
and oxygen for the partial oxidation of the fuel oil. This process option
is described further in Volume VII, page 67.
Residual oil feedstock requirements are estimated to be about 4.27 bbl/ton
of ammonia. Process fuel requirements which include fuel oil and naphtha
are estimated to be approximately 7.26 x 10 Btu/ton of ammonia (Volume VII,
page 71).
Resulting NO emissions from the feedstock and fuel, based on an emis-
sions factor of 0*33 lb/10 Btu of oil, are estimated to be 11.28 Ib/ton of
ammonia.
These NO emissions result during both the combustion of the fuel oils
and the gasification of the feedstock.
Power requirements for this process are estimated to be 103 kWh/ton
(Volume VII, page 71). NO emissions from the power boiler are estimated
to be 0.81 Ib/ton of ammonia.
Summary
The estimated NO emission factors for the base case and alternative
V
processes are summarized in Table 16. NO emissions created by the pro-
duction of ammonia from coal and heavy fuel oil are estimated to be, res-
pectively, over 170% and 20% greater than the NO emissions from the base
case. This increase is presumably a result of the higher nitrogen content
of the coal and heavy fuel oil.
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 a con-
siderable infiltration of air, burned in the hood, and cooled and cleaned
of particulates before being released to the atmosphere. Approximately
.88 x 10 Btu of heat/ton of steel are lost to the atmosphere (Volume III,
page 26). A detailed description of this system is presented in Volume III,
page 18.
It is estimated that 0.26 Ib of NO is produced/ton of steel by the
combustion of the BOP vessel off-gassesx This estimate is based on the
assumption that the NO formation during carbon monoxide combustion is
approximately 0.29 lb/10 Btu, i.e., the amount produced during the com-
bustion of natural gas. (NO emissions from BOP off-gas combustion are
not given in either Volume l¥l or in AP 42.)
The combustion system consumed 14 kWh of electricity/ton of steel;
this electricity is required for the operation of the gas scrubber system.
NO emissions from the power boiler are estimated at 0.11 Ib/ton of steel.
X
59
-------
TABLE 16. ESTIMATED NO EMISSIONS - AMMONIA INDUSTRY
BASIS: NO ADll-ON TECHNOLOGY FOR NO CONTROL
x
Estimated emission factor
Process
Ammonia production based
Base case :
Natural gas
• Coal gasification
• Heavy fuel oil
(Ib
Process
on
9.57
25.6
11.28
NO /ton of ammonia) Change from
Power boiler Total base case
0.36
1.28
0.81
9.93
26.88 +• 16.95
12.09 4- 2.16
NO emissions (106 Ib/yr)
A jt &
1974 1989-1974
91 127
344
155
* 6
Based on increment in production from 1974-1989 of 12,8 x 10 ton/year.
**
Estimated 1974 emissions, based on the total emission factor of 9.93 Ib of NO /ton of
ammonia are 9.93 x 9.2 x 10 = 91 x 106 Ib/year. X
-------
Alternative Process: Non-Combustion BOP Off-Gas Recovery System—
In the alternative process, carbon monoxide is collected and recovered
from the BOP off-gas. Approximately one-half of the carbon monoxide
(0.44 x 10 Btu/ton of steel) is recovered; the remainder is flared
(Volume III, page 26). Two recovery systems, the OG process and the
IRSID-CAFL process, and discussed in Volume III, page 19-22. About 0.13 Ib
of NO is produced/ton of steel during the flaring of the unrecovered
off-gases. The OG process, non-combust ion system, consumes about 8 kWh
of electricity/ton of steel (Volume III, page 26). Energy consumptions
are less than those for the combustion system as a result of the lower gas
volumes handled. NO emissions from the power boiler are estimated to be
0.06 Ib/ton of steel.
Blast Furnace
Base Case Process - Desulfurization Hot Metal in the Blast Furnace—
The base case system is considered to include a blast furnace, cyclone,
and venturi scrubber. The sulfur content of the blast furnace gas is
completely 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.
NO emissions from the process have not been estimated in Volume III.
Power requirements are estimated to be 46 kWh/ton of hot metal (Volume III,
page 41). Estimated emissions from a coal-fired power boiler are 0.36 Ib
of NO /ton of hot metal.
x
Process Option 1 - Blast Furnace with External Desulfurization—
Addition of an external desulfurization tip is an alternative method
of controlling the sulfur content of blast furnace hot metal. External
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 compounds 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 of the coke to
be increased without increasing the limestone charge to the furnace. A
detailed description of thie process is given in Volume III, page 31.
NO emissions from the blast furnace have not been estimated in
Volume III. Electricity consumption in this alternative process is the
same as the base case process, so power boiler emissions estimates are
also the same.
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. Steam which is produced is
61
-------
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 study presented in Volume III.
Process Option 1 - 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 gases
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 0.07 Ib of NO /ton of coke. In
addition, the recovered heat, estimated at 1.1 x 10 Btu (105 kWh) per
ton of coke may be used to generate electricity. A credit for NO emis-
sions which would otherwise be produced from a coal-fired power boiler is
estimated to be 0.83 Ib of NO /ton of coke. Thus, the net incremental
emissions credit is estimated to be 0.76 Ib of NO /ton of coke.
X
Steel-Making
Base Case Process - Coke Oven, Blast Furnace (BF), and Basic Oxygen Furance
(EOF) Route for Steel-Making—
The base case process is the conventional process for steel-making.
For our analysis we assumed that 30% scrap metal would be 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 control
equipment is estimated at 120 kWh/ton of steel (Volume III, page 79, 82-84).
NO emissions from the power boiler are estimated at 0.95 Ib/ton of steel.
X
Steam consumed by the coke-making facilities is required at about
670 Ib/ton of steel. If this steam is generated with coal, then NO emis-
sions are estimated at 0.65 Ib/ton of steel. x
Process Option 1 - Direct Reduction Route for Steel Making—
Iron oxide pellets, ore lumps, etc., can be partially reduced in the
solid state by reaction with a reducing gas mixture. These prereduced
materials can partially or entirely replace purchased scrap in the steel-
making electric arc furnaces. In this alternative process, it was 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. NO emissions from the coal-fired power boilers are estimated
at 5.6 Ib/ton of steel.
62
-------
Summary
The emissions factor and total emissions for the base processes and
the alternative processes are summarized in Table 17. In the basic oxygen
process, recovery of off-gas from the EOF offers a 50% reduction in NO
emissions, since only one-half of the off-gases is flared. In the pro-
duction of iron, external desulfurization offers no reduction in NO
emissions from the base case process.
Steel-making by the direct reduction method will result in nearly a
three-fold increase in emissions over the conventional route because of
the higher power requirements of direct reduction process.
PHOSPHORUS/PHOSPHORIC ACID
Phosphoric Acid Production
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,
page 23-2A.
Electric furnace production of phosphorus is a very energy-intensive
operation. Electrical energy requirements are estimated at 13,000 kWh/ton
of phosphorus (?,)• More than 90% of this energy is required 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 £iln where the furnace feed materials are prepared. Natural gas
(6 x 10 Btu/ton of P ) is required to supplement the carbon monoxide
gas (Volume XIII, pagl 33).
110 emissions from the electric arc furnace have not been quantified in
either Volume XIII or in AP 42; these emissions are assumed to be
negligible.
HO is produced by the .combustion of natural gas. and carbon monoxide in
the rotary kiln; emissions are estimated to be 2.76 Ib/ton of P 0
(6.3 Ib/ton of P ). The NO emission factor for carbon monoxide combustion
was not available from either Volume XIII or AP 42 (EPA, 1975). However,
it was expected that NO production during carbon monoxide combustion
would be similar to NO production during natural gas combustion; hence,
the emission factor, 0?29 Ib of NO /10 Btu of gas, was used for both
fuels.
NO emissions from the coal-fired power boiler are estimated to be
45 Ib/ton of P205 (103 Ib/ton of P^) .
63
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TABLE 17. ESTIMATED NO EMISSIONS - IRON AND STEEL INDUSTRY
BASIS: NO Afo-ON TECHNOLOGY FOR NO CONTROL
x
,,„ ^ , . ,- Incremental NO .
NO estimated emission factor . . -,n-,/x in or,
? r *—T\ ^ c emissions for 1974 - 1989
'ton of product) Change from ^ ^~
Process Process Power boiler Total base case 1974 1989-1974
Base case:
BOP with no off-gas
recovery 0.26 0.11 0.37 — 30 22
• BOP with off-gas
recovery 0.13 0,06 0.19 - 0.18 — 11
Base case:
Blast furnace (BF) — 0.07 0.07 — 7 3
• Blast furnace with
external desulfurization — 0,07 0.07 0.0 — 3
Base case: ,
Wet quenching of coke 0.0 NA NA — NA NA
• Dry quenching of coke - 0.83ft 0.07tf - 0.76ft - 0.76ft NA - 21ft
Base case:
Steel-making
• Coke oven, BF, BOP route 0.8 1.0 1.8 — 148 108
• Direct reduction EAF
route — 5.6 5.6 3.8 -- 336
(continued)
-------
TABLE 17. (continued)
Estimated 1974 emissions (based on the emission factor of 0.07 Ib/ton of iron) are 0.07 x 100 x 10 =
7 x 10 Ibs from iron production; estimated,1974 emissions based on the emission factor of 0.37 Ib/ton
of BOP steel, are 0.37 x 82 x 10 = 30 x 10 Ibj and estimated 1974 emissions, based on emission factor
of 1.8 Ib NO /ton of steel from coke oven, blast furnace, BOP route, are 1.8 x 82 x 10 = 148 x 10 Ib.
X
** 66
Based on increment in production from 1974-1989 — 27,8 x 10 tons of coke, 44.8 x 10 tons of iron,
and 60 x 10 tons of steel.
NA = not available
Emission factor is based on incremental requirements of the dry quench process as it compares to the
wet quench process.
Ln
-------
Process Option 1 - Wet-Process Phosphoric Acid with Chemical Cleanup —
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% P?0 product. The wet process is more completely described in
Volume XIII, page 35-37. There are a number of impurities in wet-
process phosphoric acid which make it unsuitable for use in certain appli-
cations. Wet acid is purified to sodium tripolyphosphate by a two-stage
neutralization process (Volume XIII, page 49).
Steam is required to concentrate the acid solution. Steam may be gen-
erated by oil, or if the phosphoric acid plant is integrated with a sulfuric
acid plant, then this steam may be generated from heat released by the
oxidation of sulfur. About 13 million Btu/ton of P 0 is recovered;
approximately half of the steam heat is used in the sulfuric acid plant,
and the other half is used by the phosphoric acid plant.
If the phosphoric plant is not integrated with a sulfuric acid plant
and the steam is generated from oil, then NO emissions are estimated to
be 2.52 Ib/ton of P20 . X
Electricity (250 kUh/ton of P?0,) is required to drive pumps, agitators,
and filters in the wet-acid process. An additional 16 kWh/ton of P?0
is required for the chemical cleanup of the acid (Volume XIII, page 57).
NO emissions from a coal-fired power boiler are estimated to be 2.10 Ib/ton
Wet-Process Phosphoric Acid with Solvent Extraction Cleanup —
This method of wet-process phosphoric acid cleanup 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 impuri-
ties, 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 of steam/ton
of Pj0!- f°r concentration of the acid from 15% as it is produced in the
extraction section to a concentration of about 60% P 0 (Volume XIII,
page 70). If the steam is generated with fuel oil, Che NO emissions
are estimated to be 4.30 Ib/ton of P 0 . x
Electricity requirements for the solvent extraction process are about
300 kWh/ton of P 0 (Volume XIII, page 70). The estimated NO emissions
from a coal-fired power boiler are 2.36 Ib/ton of P 0 . X
Summary
The emissions factor and total emissions for the base case process and
alternative processes are summarized in Table 18. Both of the process
options offer a significant reduction in NO emissions over the base case
X
66
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TABLE 18. ESTIMATED NO EMISSIONS - PHOSPHORUS/PHOSPHORIC ACID PRODUCTION
BASIS: NO A^D-ON TECHNOLOGY FOR NO CONTROL
x
Process
NO estimated emission factor
'ton P?0,.) Change from
Process Boiler Total base case
* 6
NO emissions (10 Ib/yr)
1974
**
1989-1974
Base case:
Electric furnace
2.8
45.0
47.8
67
30.1
• Chemical cleanup of
wet-process acid
2.5
2,1
4,6 - 43.2
2.9
Solvent extraction of
wet-process acid
4.3
2.4
6,7 - 41.1
4.2
Based on the incremental production detergent grade phosphoric acid from 1974 to 1989
0.63 x 10° Ib/yr.
**
NO emissions based on the emission factor of 47.8 Ib/ton of detergent-grade phosphoric
acid in the year 1974 are 47.8 x 1.4 x 10 = 67 x 10 Ib.
-------
decrease. This reduction is primarily a result of the lower power
requirements for wet-process phosphoric acid production.
TEXTILES INDUSTRY
Two textile nills, 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, before being dyed,
washed, and spun dry to remove as much water as possible before hot-air
drying. A finish (softener/lubricant) is applied to the fabric, which is
then dried and heat-set. Details of the knitting mill operation are pre-
sented in Volume IX, page 33.
Natural gas is used for the hot-air drying and heat-set operations.
It is unlikely that the natural gas will be supplemented, as it is
required by all of the equipment presently available for fabric drying
and heat-setting operations. NO emissions from these operations—based
on the emissions factor of 0.29 Ib of NO /10 Btu of natural gas—are
estimated to be 2.42 Ib/ton of fabric. X
Steam is used for the heat input to tha scouring, dyeing, and washing
operations. In the base case process, it was assumed that the steam
would be generated with low-sulfur residual fuel oil. Estimated NO
emissions—based on the emission factor of .33 lb/10 Btu of oil burned
in the boiler (EPA, 1973)—are estimated to be 2.65 Ib/ton of fabric.
Because of the relatively small energy requirements of textile mills,
it seems unlikely 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 knitting the
yarn into the fabric. Electrical requirements of 360 kWh/ton of fabric
will result in NO emissions of about 2.84 Ib of NO /ton of fabric.
x x
Advanced Aqueous Processing—
The sequence of operation is similar to the base case, except that the
hot air drier is replaced by an air/vacuum extractor, thereby reducing
natural gas requirements and increasing electrical requirements. Secondly,
the scouring, dyeing, and washing operations are modernized with more effi-
cient equipment, so that steam requirements are reduced. Advanced aqueous
processing is described in detail in Volume IX, page 535-537.
68
-------
Natural gas is used for the heat-setting operation. NO emissions—
based on the emissions factor of 0.29 lb/10 Btu of natural gas—are
estimated to be 0.24 Ib NO /ton of fabric.
x
Steam requirements of 3800 Ib/ton of fabric will result in 1.25 Ib of
NO /ton of fabric if the steam is generated by fuel oil. Electrical
requirements of 500 kWh/ton of fabric will result in controlled emissions
at the power boiler of 3.94 Ib of NO /ton of fabric.
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 this
solvent system are provided in Volume IX, page 37-41.
Natural gas is used for the heat-setting operation. NO emissions
are estimated to be 0.24 Ib/ton of fabric. Steam requirements of 2200 Ib/
ton of fabric will result in 0.73 Ib of NO /ton of fabric. Electricity
requirements of 240 kWh/ton of fabric will result in controlled emissions
of 1.89 Ib of NO /ton of fabric.
x
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.
NO emissions are estimated to be about 4.34 Ib/ton of woven fabric.
x
Steam (15 Ib/ton of fabric) is used for process water heating in the
dyeing, washing, and finishing steps. Steam generated by fuel oil will
produce controlled emissions of about 9.9 Ib of NO /ton of fabric. Elec-
trical energy requirements are estimated at 580 kWn/ton of product This
will result in controlled NO emissions of 4.57 Ib/ton of fabric.
x
Advanced Process—
The advanced processing includes a polyvinyl alcohol (PVA) recovery
loop which recycles concentrated PVA solution back to sizing and the hot
water back to the desizing operation. Details of the advances case sequence
are presented in Volume IX, page 49.
Natural gas is used in the drying, setting, and curing operations.
NO emissions are estimated to be 1.47 Ib/ton of fabric.
Steam requirements have been reduced to 6.4 Ib/ton of fabric by reduc-
tion in overall process water use and recycling of wash waters. This steam
generation will produce 4.22 Ib of NO /ton of fabric if these emissions
X
69
-------
are not controlled. Electrical requirements have been reduced to 300 kWh/
Ib of steam. This will result in NO emissions of 2.36 Ib/ton of fabric.
X
Summary
The emissions factors and total emissions for the base case process
and alternative processes for both knit and woven fabric production are
summarized in Table 19.
Both alternative processes for knit fabric production offer a decrease
in NO emissions. The advanced aqueous process shows a more modest
decrease since electric power consumption for this alternative is higher
than the base case. The solvent process shows a more pronounced decrease
(58%) in NO emissions, since natural gas, steam, and electrical power
consumption is lower than in the base case.
The alternative process for woven fabric production also offers more
than a 50% reduction in NO emissions, since natural gas, steam, and
electrical power consumption are only about 50% of what is consumed in
the base case process.
PULP AND PAPER INDUSTRY
Chemical Pulp
Base Case Process - Kraft Pulping—
In the Kraft process, chemical pulp is produced by cooking the wood
chips at an elevated temperature and pressure in a digester. When cooking
is completed, the contents of the digester are forced into a blow tank.
The major portion of the spent cooking liquor which contains the dissolved
lignin is drained and the pulp enters the initial stage of washing. From
the blow tank the pulp passes through the knotter where chunks of wood are
removed. The pulp is then washed and bleached before being pressed and
dried into the finished product.
It is economical to recover both the inorganic cooking chemicals and the
heat content of the spent liquor which is separated from the cooked
pulp in the blow tank. Heat recovery is accomplished by first concen-
trating the liquor to a level that will support combustion and then feeding
it to a furnace (recovery boiler) where heat and chemical recovery take
place.
Steam is produced by both process wastes and fossil fuel. Waste organic
solids from the pulping process are burned in the recovery boiler, and
wood bark from wood preparation operations are burned with the fossil
fuel boilers. The steam is delivered from the boilers to the turbines
which extract energy from the steam for electric power generation. The
steam is then used predominantly in the pulping, bleaching, and chemical
recovery operations.
70
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TABLE 19. ESTIMATED NO EMISSIONS - TEXTILE INDUSTRY
BASIS: NO ADTJ-ON TECHNOLOGY FOR NO CONTROL
x
Process
Knit fabric
Base case:
• Advanced case
• Solvent case
Woven fabric
Base case:
• Advanced case
NO
Process
5.06
1.49
0.97
14.24
5.69
estimated emission factor
tlb/ton fabric)
Power boiler
2.84
3.94
1,89
4.57
2.36
Change from
Total base case
7.90
5.43 - 2.47
2,86 - 5,04
18.81
8.05 -10.76
NO emissions
for 197^-1989 (10 Ib/yr)
1974 1989-1974*
**
2.5 0.95
0.65
0.34
39. 5f 15.2
6.5
Based on increment in production from 1974-1989 - 0.12 x 10, ton/year (knit fabric)
- 0,81 x 10 ton/year (woven fabric)
**
•v
Estimated 1974 emissions from knit fabric production based on the total emission factor of
7.90 Ib of NO /ton of fabric are 7.90 x 0.32 x 106 = 2.5 x 106 lbt
x
Estimated 1974 emissions from woven fabric production based on total emission factor of
18.81 Ib of NO /ton of fabric are 18.81 x 2.1 x 10 = 39.5 x 10 ton/year.
X
-------
Fossil fuels, which supplement the process waste fuels include natural
gas, fuel oil, and a small amount of coal (Volume V, page 21, 44). In
view of the relatively even distribution of gas and oil users, and in
view of the uncertainty of the future availability of fossil fuels,
it was assumed that fuel requirements would be satisfied by oil.
NO emissions are estimated to be 1.0 Ib/air dry ton of pulp from the
recover^ furnace and an equal amount from the lime kiln (EPA, 1975).
NO emissions from bark waste are estimated to be 10.0 Ib/ton of bark
(E?A, 1975 page 1.6-2). The NO emission factor for the Kraft process
is estimated to be 5.1 Ib/ton of pulp. This includes NO produced from
the lime kiln and NO produced by steam generation in both the recovery
boiler and the bark £oiler. The emission factor for power generation,
0.5 Ib/ton of pulp, is seen to add about 10% to the process emissions,
resulting in a total emission factor of 5.6 Ib NO /ton of pulp.
X
Process Option 1 - Alkaline-Oxygen Pulping Process Alternative—
The alkaline-oxygen (A-0) pulping process is receiving industry atten-
tion because of its potential for a non-sulfur cooking step, which would
eliminate the air pollution due to sulfur compounds.
The steps in the alkaline-oxygen process include an alkaline treatment
to soften the wood chips, mechanical disintegration, and treatment with
oxygen under alkaline conditions to remove most of the lignin, 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).
Steam and power are produced in this alternative in the same manner
as they were produced in the base case. The NO emissions from the lime
kiln and steam generation are estimated at 3.8 fb/ton of pulp, and NO
emissions from the power generation are estimated at 0.3 Ib/ton of pufp.
Process Option 2 - Rapson Effluent-free Kraft Process Alternative—
A number of changes in the base case pulping process have been made
to eliminate effluents. The modified process is called the Rapson effluent-
free Kraft process. (It is described in detail in Volume V, page 93.)
Steam and power are produced in this alternative in the same manner
as they were produced in the base case. The NO emissions from the lime
kiln and steam generation are estimated at 3.0 fb/ton of pulp, and NO
emissions from power generation are estimated at 0.2 Ib/ton of pulp.
Newsprint Pulp
Base Case Process - Refiner Mechanical Pulping (RMP) Route for Newsprint Pulp-
RMP is a mechanical pulping process that is an improvement over the
conventional groundwood process since wood chips, sawdust, and shavings from
sawmills or plywood mills can be used as raw materials. The wood particles
are reduced in a pressurized disc refiner which consists of two circular
72
-------
metal plates that generally rotate in opposite directions. RMP pulp (80%)
is used with Kraft pulp (20%) in newsprint paper production. (A detailed
description of the RMP process is given in Volume V, page 60.)
Fuel requirements for the RMP process are estimated at 0.3 x 10
Btu/air-dried ton (ADT) of pulp (Volume X, page 60). Resulting NO emis-
sions are estimated at 0.1 Ib/ADT of pulp produced solely by the RMP
process. If 80% of the pulp is produced by the RMP process and 20% of
the pulp is produced by the Kraft process, then the NO emissions are
estimated to be 1.1 Ib/ADT for the process and 9.4 Ib/^DT for the power
boiler.
Power requirements for the RMP process are estimated at 1475 kWh/ADT
of pulp (Volume X, page 60). Resulting NO emissions based on a coal-
fired power boiler are estimated at 11.6 ID/ADT of newsprint pulp.
Process Option 1 - Thermo-Mechanical Pulping (IMP) Process Alternative—
The TMP process is similar to the base case process (RMP process),
except the wood particles are preheated to 130°C for a short period and
then reduced to fibers in a pressurized disc refiner. (A detailed process
is given in Volume V, page 98.)
Fuel and power requirements for the TMP process are identical to the
requirements for the RMP process; hence the NO emission factors are the
same; i.e., 0.1 Ib/ADT from the process and 11X6 Ib/ADT from the power
boiler. If 95% of the pulp is produced by the TMP process, then the NO
emissions are estimated to be 0.4 Ib/ADT for the process and 11.0 Ib/AD?
for the power boiler.
Process Option 2 - De-inking of Old Newsprint for Newsprint Manufacture—
The de-inking of old newsprint for newsprint manufacture is a well-
established commercial practice. A detailed description of the process
is given in Volume V, page 113. Fuel oil requirements for the de-inking
process are estimated at 3.3 x 10 Btu/ADT; hence NO emissions are esti-
mated to be 0.4 Ib/ADT of newspaper pulp. x
Power requirements are estimated at 280 kWh/ADT; hence NO emissions
are estimated at 2.2 Ib/ADT. X
Summary
Estimated particulate emissions factors for the pulp and paper industry
are shown in Table 20. In the chemical pulp industry, both alternatives
to the Kraft process offer a means of NO reductions. The emissions in
the alkaline-oxygen pulping alternative process are about 27% lower than
for the base case process. The emissions in the Rapson process are about
43% lower than the base case process. These reductions in NO emissions
from the base case process result from the reduction in steam and power
consumptions.
73
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TABLE 20. ESTIMATED NO EMISSIONS - PULP AND PAPER INDUSTRY
BASIS: NO A§D-ON TECHNOLOGY FOR NO CONTROL
x
Process
NO estimated emission factor
X T
of pulp) Change from
Process Power boiler Total base case
* 6
NO emissions (10 Ib/yr)
X J.J. JL*
1974
1989-1974
Chemical pulp
Base case: ,
Kraft pulp
• Alkaline-oxygen
pulping
• Rapson effluent-
free Kraft
5.1
3.8
3.0
0,5
0.3
0.2
5,6
4.1
3.2
- 1.5
- 2.4
90
97
71
55
Newsprint Pulp
Base case:
Refiner mechanical
pulping
• Thermo-mechanical
pulping
• De-inking of old
newsprint for news-
print manufacture
1.1
0.4
1.1
9.4
11.0
2.2
10.5
11.4
3.3
+ .9
- 7.2
41
17.9
19.4
5.6
Air-dry basis.
k
Based on increment in emissions from 1974-1989
tons of newsprint pulp/year.
17.3 x 10 tons of chemical pulp/year and 1.7 :; 10
(continued)
-------
TABLE 20. (continued)
Estimated 1974 emissions,(based on the total emission factor of 5.6 Ib/ton of pulp) are
5.6 x 16 x 10b = 90 x 10° Ib/year.
Estimated 1974 emissions (based on the total emissions factor of 10.5 Ib/ton of pulp) are
10.5 x 3.9 x 106 = 41 x 10 Ib/year.
-------
In the newsprint pulp industry, NO emissions are the lowest for the
de-inking process option. The RMP and TMP processes produced more than
three times the amount of NO emissions generated by the de-inking process.
This can be attributed to the higher fuel and power consumptions of the
RMP and TMP processes. The RMP pulp has slightly lower NO emissions than
the TMP pulp since the RMP pulp contains more pulp from the Kraft process.
CHLOR-ALKALI INDUSTRY
Chlorine and Caustic Production
Base Case Process - Graphite Anode Diaphragm Cell—
The graphite anote diaphragm cell was selected as a basis for judging
the energy and environmental effects resulting from the process changes
studies, 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, page 21-25.
The electrolysis of brine is an energy-intensive process, requiring
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. Steam is generated by natural gas and byproduct hydrogen.
Based upon 1,100 Btu/lb of low-pressure steam and an 85% boiler efficiency,
the fuel requirement is 9.15 x 10 Btu/ton of chlorine (Volume XII, page 27).
NO emissions from the coal-fired power boiler are estimated at
25.80 l!>/ton of chlorine. NO emissions produced from the gas-fired steam
generator—based on 0.29 Ib of NO /10 Btu of fuel—are estimated to be
2.65 Ib/ton of chlorine. X
Process Option 1 - Dimensionally Stable Anode—
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 remain constant throughout
use, thereby preventing increased voltage requirements over time. Additional
characteristics of the DSA are presented in Volume XII, page 44-47.
The DSA diaphragm cell process requires 3,151 kWh and 6,402 Ib of
n/ton of chlorine. Steam is gi
ral gas. Approximately 7.94 x
of chlorine (Volume XII, page 46).
steam/ton of chlorine. Steam is generated by the byproduct hydrogen and
natural gas. Approximately 7.94 x 10 Btu of fuel is required per ton
76
-------
NO emissions from power generation are estimated at 24.83 Ib/ton of
chlorine. NO emissions from steam generation are estimated to be 2.30 lb/
ton of chlorine.
Process Option 2 - Expandable DSA—
Cell power consumption can be reduced by decreasing the gap between
the anode and the cathode. With the rigid DSA, a "working" space must be
allowed in which to assemble the cell. The expanded DSA is constructed 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. This power savings reduces NO
emissions by about 2.55 Ib/ton of chlorine from the emissions estimated
for the rigid DSA cells.
Process Option 3 - Polymer Modified Asbestos—
By replacing the conventional asbestos diaphragm by one which is
polymer-treated and is baked into place on the cathode, power consumption
can be reduced because diaphragm swelling does not occur. Electrical
consumption may be reduced by as much as 280 kWh/ton if an extra wide
anode is used. Thus, NO emissions are estimated to be 2.21 Ib/ton of
chlorine less than the emissions estimated for the rigid DSA cells with
standard diaphragms.
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 asbestos with the
"entra-wide" anode. Hence, the NO emissions 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 solution,
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 lb of steam/ton of chlorine (Volume XII, page 59).
Significantly less steam is required since a rather concentrated NaOH
solution is produced directly from the cell. Steam is generated by
natural gas and byproduct hydrogen. Approximately 1.81 x 10 Btu of gas
fuel are required per ton of chlorine (Volume XII, page 59).
NO emissions from power generation are estimated to be 23.24 Ib/ton
of chlorine. NO emissions from steam generation are estimatad to be
approximately 0.52 Ib/ton of chlorine.
77
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Process Option 6 - Mercury Cells—
Chlorine and caustic may also be produced in a mercury cell. In this
type cell, brine flows through a slightly sloped trough. At the dimen-
sionally stable anodes, located at the top of the trough, chlorine is
produced. A dilute sodium amalgam is produced at the cathode (a thin
layer of mercury which flows along the bottom of the trough). A 50%
caustic solution is produced from the amalgam, and the mercury is recycled
to the cell.
Energy requirements for the mercury cell include 3,712 kWh of power
and 550 Ib of steam/ton of chlorine (Volume XII, page 56). Steam is
generated by natural gas and byproduct hydrogen. Approximately 0.72 x 10
Btu of fuel gas/ton of chlorine are required (Volume XII, page 56).
NO emissions from steam generation by natural gas and byproduct
hydrogen are estimated to be 0.21 Ib/ton of chlorine. NO emissions pro-
duced by a coal-fired power boiler are estimated to be 29.25 Ib/ton of
chlorine.
Summary
The emissions factor and total emissions for the baseline and alter-
native processes are presented in Table 21. The modified anodes and
modified diaphragm options offer between a 5% to 16% yearly reduction
in NO emissions from the base case process.
The mercury cell, however, is estimated to result in a 4% yearly
increase from the base case because of the relatively larger power
requirements.
78
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VO
TABLE 21. ESTIMATED NO EMISSIONS - CHLOR-ALKALI INDUSTRY
BASIS: NO ADD-ON TECHNOLOGY FOR NO CONTROL
X
Process
Base case:
Graphite- anode^
diaphragm cell
• Dimensionally stable
anodes
• Expandable DSA
• Polymer-modified
asbestos
• Polymer membrane
• Ion exchange membrane
• Mercury cell
NO
estimated emission factor
(Ib/ton of chlorine)
Process Power boiler Total
2.65
2.30
2.30
2.30
2.30
0.52
0.21
25.80
24.83
22.28
22.62
22.62
23.24
29.25
28,45
27,13
24.58
24,92
24,92
23.76
29.46
Change from NO emission
base case 1974
313
- 1.32
- 3.87
- 3.53
- 3,53
- 4.69
+ 1.01
(106 Ib/yr)
1989-1974
339
323
293
297
297
283
351
Based on increment in production from 1974 to 1989 = 11.9 x 10 ton/year.
**
Estimated 1974 emissions, based on the total emission factor of 28.45 Ib of NO /ton of
chlorine are 28.45 x 11.0 x 106 = 3^3 x io6 Ib.
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REFERENCES
U.S. Environmental Protection Agency, AP-42, Compilation of Air Pollution
Emission Factors, Second Edition, March 1975.
U.S. Environmental Protection Agency, National Air Quality and Emissions
Trend Report, 1975, Research Triangle Park, N.C., NTIS PB-263922.
Chemical Engineering, February 14, 1977, p. 36.
Monsanto Research Corporation, Source Assessment Overview Matrix,
EPA Contract NO. 68-02-1874, September 1976.
Arthur D. Little, Inc., Screening Study to Determine Need for Standards
of Performance for New Sources in the Fiberglass Manufacturing Industry,
EPA Contract No. 68-02-1332, Task 23, December 1976.
80
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-600/7-79-142
TITLE ANDSUBTITLE
Environmental Considerations of Selected Energy-
Conserving Manufacturing Process Options - Volume
XVII Nitrogen Oxides Summary Report
5. REPORT DATE
July 1979 issuing date
6. PERFORMING ORGANIZATION CODE
. RECIPIENT'S ACCESSION-NO.
AUTHOR(S)
Arthur D. Little, Inc.
8. PERFORMING ORGANIZATION REPORT NO.
PERFORMING ORGANIZATION NAME AND ADDRESS
Arthur D. Little, Inc.
20 Acorn Park
Cambridge, MA 02140
10. PROGRAM ELEMENT NO.
1NE 624B
11. CONTRACT/GRANT NO.
68-03-2198
2. 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
5. SUPPLEMENTARY NOTES
16. 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 nitrogen oxide
pollutants in the 13 industry reports. Four parallel reports treat sulfur
oxides, particulates, solid residues, and toxics/organics. All of these pollutant
oriented reports are intended to be closely used with the original 15 reports.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
. cos AT I Field/Group
Energy, Pollution, Industrial Wastes
Manufacturing Processes,
Energy Conservation
68D
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisReport)
UNCLASSIFIED
21. NO. OF PAGES
89
20. SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
81
4 U.S. EOVUNMENTntmTMGOFJICE: 1979 -657-060/5405
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