United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S7-81-132 Mar. 1982
Project Summary
Energy Use Patterns and
Environmental Implications of
Direct-Fired Industrial
Processes
Benjamin L. Blaney, Jay R. Hoover, James R. Blacksmith, and Paul W. Spaite
Energy consumption patterns and
environmental impacts of direct-fired
processes in the industrial sector were
identified. The potential effects of fuel
switching in several of these processes
were determined.
Annual energy consumption in the
United States has totalled approxi-
mately 75 quads (1 quad = 101S Btu) in
recent years. Direct-fired processes in
the industrial sector consume 10
percent of this energy, or seven quads
per year. Most of the direct-fired
energy consumption occurs in the
manufacture of chemicals, petroleum
products, primary metals, and mineral
products (cement, glass, brick, etc.).
An estimated 60 percent of all
direct-fired fuel is burned in processes
whose only emissions are products of
combustion. However, the more
important environmental impacts are
associated with the firing of the
remaining 40 percent of the fuel. This
energy is consumed in processes that
commingle combustion gases with
materials being processed. These
materials include volatile metals from
blast furnaces, dust from cement
kilns, and fine particulate from glass
furnaces.
Switching of some direct-fired
processes to coal has proven feasible.
Fuel switching would have a more
pronounced environmental impact on
those processes emitting only products
of combustion.
This Project Summary was devel-
oped by EPA's Industrial Environmen-
tal Research Laboratory, Cincinnati,
OH, to announce key findings of the
research project that is fully docu-
mented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
The Environmental Protection Agency
is in the process of compiling a data
base of energy consumption by indus-
trial processes and of the associated
pollutant emissions. The purpose of the
study summarized here was to quanti-
tatively characterize energy consump-
tion and emissions of direct-fired*
processes. These data will allow re-
searchers to determine the environ-
mental implications of future energy
consumption trends in industry as well
as the consequences of switching of
process fuel.
'For the purposes of this study direct-fired
industrial processes are defined as those which
burn fossil-fuel based fuels to supply thermal
energy from the flame and/or products of
combustion. Steam generation was not included in
this category for this study because it has been
extensively investigated elsewhere
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The study had three principal objec-
tives.
1. Determine the amount of direct-
fired energy consumed by individ-
ual industrial processes and
associated equipment.
2. Evaluate the environmental im-
pacts associated with these
processes and equipment, and
3. Determine whether future altera-
tions in present energy consump-
tion patterns for direct firing would
have significant environmental
impact.
The study focused on six major
industrial manufacturing groups: food;
paper; chemicals; petroleum; stone,
clay and glass; ahd primary metals.
Seventy percent of the energy consumed
by direct-fired processes in industrial
manufacturing can be accounted for by
specific processes within these six
industries. This amounts to 4.8 quads(1
quad= 1016 Btu), or about seven percent
of total United States energy consump-
tion in 1974.
In addition to determining industrial
energy consumption on a process-
specific basis, the study estimated the
total energy consumed in direct-fired
processes in these six industries as well
as in all other manufacturing industries.
This was done indirectly by taking the
difference between total manufacturing
energy consumption and energy con-
sumption in other than direct-fired end
uses (i.e. electricity production, process
steam, feedstocks and metallurgical
reduction). By comparing the resulting,
indirectly determined, overall direct-
fired energy use for a given industry
with a total consumed by all direct-fired
processes identified for that industry, an
independent check was obtained on
whether all significant direct-fired
processes had been identified for that
industry.
The data points used for process-
specific annual energy consumption
spanned the period from 1971-1977; it
was not possible to create a complete
data set for one calendar year. However,
with one exception, there was less than
a 10 percent variation in the total energy
consumed by the six major industries
during this period, and therefore the
data collected should be adequate for
identifying the trends sought by this
project. The one exception was the
chemical industry where a 20 percent
increase in total energy consumption
and a 17 percent increase in direct-fired
energy consumption occurred between
1971 and 1977. This increase in the
chemical industry parallels the growth
in products from this industry, especially
in the organic chemicals segment.
Therefore, the energy consumed per
unit of product during the 1971-1977
period was assumed to remain fairly
constant.
The pollution profiles for the direct-
fired processes are only described
qualitatively in the report. There are two
reasons for this. First, the study was
intended to emphasize the collection of
energy consumption data. Secondly, as
noted below, it was difficult to obtain
quantitative factors for all the processes
involved, frequently because these
factors varied widely for a given process
depending upon operating conditions.
Therefore, only a qualitative discussion
of emissions is provided. However, even
this qualitative discussion concludes
that changes in process fuel type will
have little impact on emissions except in
a very limited number of cases.
Results
Energy Consumption
Table 1 shows the amounts of energy
consumed annually for various end
uses within the six major manufacturing
groups investigated, as well as for other
manufacturing industries. Direct-fired
processes account for 7 quads of
consumed energy. This is 30 percent of
all energy consumed by manufacturing
industries and 10 percent of all energy
consumed annually in the United
States. It can be seen from the table that
four of the major manufacturing indus-
trial groups (SIC's 28, 29, 32 and 33)
account for practically all of the direct-
fired energy consumption. Also, direct
firing supplies a large portion of all the
process energy requirements for these
four groups.
An energy analysis was also per-
formed on the major processes within
these six industrial groups. Table 2
presents the amounts of energy con-
sumption which could be accounted for
within each industry based on this
process-specific analysis. The table
shows that over 60 percent of the
energy consumed in all manufacturing
operations was accounted for by specific
processes and that the energy accounted
for in specific end-use categories ranged
from 42 to 89 percent.
Of the greatest interest to this project
was the association of 69 percent of the
direct-fired energy consumption by all
manufacturing industries with a specific
process within the six major industrial
groups. This amounts to 4.8 quads of
annual energy consumption and is
accounted for by 200 direct-fired
processes. Further analysis showed
that 27 of these processes accounted
for 61 percent (4.3 quads) of all direct-
fired energy consumption. These pro-
cesses are listed in Table 3. Each
consumes at least 0.03 quads of energy
per year.
Pollutant Impacts
Approximately 60 percent of all
industrial direct-fired fuel (4.2 quads) is
fired in processes that emit only
products of combustion. This amount is
small compared to the 15 quads/year
burned by utility boilers and the 10
quads/year burned in industrial and
commercial boilers. In addition, direct-
fired processes burn mostly gas or oil.
Therefore, they do not appear to be
serious contributors to the national
burden of pollution from combustion
products. However, actual emission
data are limited, and local effects from
operations such as refineries or other
installations with large fuel consump-
tion may be significanteither for the
operations' generation of NOX and SOX
or because the operations emit products
of incomplete combustion.
The remaining 40 percent of direct-
fired fuel (2.8 quads/year) is fired in
processes, such as cement kilns and
reverberatory furnaces, which permit
commingling of the combustion products
with dust and volatiles evolved by
materials charged to the process.
Discharges of these process contam-
inants do not appear to have been fully
characterized.
For example, copper smelting opera-
tions discharge large quantities of dust
and SO, and other contaminants, such
as volatile metals. Hydrocarbons, origi-
nating from ore flotation agents and
introduced with the ore concentrate, are
also believed to be present in the off-
gases in significant amounts. While it is
not known whether hydrocarbons or
trace metals such as arsenic and
cadmium are present in quantities that
constitute an environmental threat,
further investigation is felt to be
necessary. Also, better knowledge of
the content of raw materials being fed to
direct-fired processes would be useful
in understanding the potential for
impacts from such processing.
Major environmental impacts result
from direct firing of fuel in the primary
metals industry group, especially in
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Table 1. Fuel Use and Purchased Electricity for the Six Major Manufacturing Industry Groups, W2 Btu/Yr
Industry group
Purchased Self-generated Direct- Feed- Metallurgical
SIC Year electricity electricity Steam fired stocks reductant
Total
Food
Paper
Chemicals
Petroleum
Stone, clay, and glass
Primary metals
Other
Total
20
26
28
29
32
33
1971
1977
1971
1977
1971
1977
1971
1977
1971
1977
1971
1977
1971
1977
1971
1977
371.7
448.4
367.5
454.7
1,046. 1
1.602.3
248.8
324.6
260.9
336.9
1.285.3
1.632.6
1,855.9
2.299.8
5.436.2
7,099.3
27.3
24.6
266.5
287.4
205.4
138.7
56.7
46.5
9.4
4.6
258.4
139.6
45.2
22.7
868.9
664.1
720.3
775.4
1.631.1
1.602.2
680.4
729.9
758.6
667.6
110.9
100.7
200.5
355.0
1.047.4
1.142.0
5.149.2
5.372.8
53.5
45.9
54.5
51.1
1.348.0 1,891.8
1.583.4 2,177.0
2,169.4
1,943.6
1,029. 1
1.051.7
1,556.5
1,493.0
717.1
794.2
6,928.1 1.891.8
6.962.9 2.177.0
1,172.8
1,294.3
2.319.6
- 2,335.4
5,171.7
6.231.3
3,233.5
2.982.3
1.410.3
1.493.9
1.975.0 5,275.7
1,845.6 5,465.8
3.665.6
4.258.7
1.975.0 22.249.2
1.845.6 24.121.7
Table 2. Summation of Process Energy Analysis for the Six Major Industry Groups! W2 Btu/Yr
Industry group
Food
Paper
Chemicals
Petroleum
Stone, clay, and glass
Primary metals
Total4
% of Total Manufacturing
Energy Consumption5
SIC
20
26
28
29
32
33
Electrical2
471.0
634.0
530.0
175.4
199.8
1,210.0
3.220.2
42%
Process
steam
671.4
1.645.8
720.7
486.5
240.5
3.764.9
70%
Direct-
fired
155.0
39.7
494.4
2.010. 1
829.0
1.300.6
4,828.8
69%
Feed-
stocks
1,945.8
1,945.8
89%
Metallurgical
17.43
1.353.5
1,370.9
74%
Total4
1,297.4
2,319.6
3,708,3
2,672.0
1.028.9
4,104.5
15.130.7
63%
'Methodology and sources are presented in Appendix B of project report.
2Estimate includes purchased and self-generated electricity converted at 1O.500 Btu/kWh.
3Estimate includes coke used in the production of elemental phosphorus and sodium metal.
'Numbers may not add to exact totals due to independent rounding.
5Based on 1977 totals in Table 1.
iron and steel industry. One of the most
significant sources of pollution in the
iron and steel industry is the coke oven
process. Emissions from this process
include unburned hydrocarbons and
SO,. Other significant polluting processes
in the iron and steel industry are blast
furnace pig iron production, steel-
making, and sintering. The metal
emissions from these processes include
participates, volatile metal fumes, CO
and SO,.
The most important pollutant resulting
'rom direct-fired processes in the
mineral processing industries is fine
particulate from cement, lime, and glass
production. These particulates are
primarily from processed material and
are affected only slightly by type of fuel
used.
Finally, the impact of fuel change on
emissions from direct-fired processes
are likely to be small in most cases.
There are several reasons for this. First,
oil and gas will continue to be the
principal fuels of choice because in
many cases they are available as by-
products from other processes, such as
in the petroleum industry, or they are
required because of their cleanliness.
The use of gas for alumina calcining is
an example of the latter situation. There
is little likelihood of switching to coal in
this process because the alumina
product from the kiln must be fairly
pure.
Second, the impact of fuel switching
on emissions in the cases where the
emissions from the fuel are commingled
with those from the raw material being
processed (e.g. in lime calcining) are
expected to be minor because the
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Table 3. Summary of Major Energy Consuming Direct-Fired Processes
Raw Material
SIC
Industry
Process/Operation
Limestone
Iron ore
Oil and gas
Oil and gas
Iron ore
Iron ore
3274
331/332
2873
2911
331/332
331/332
Oil and gas
Clays
Oil and gas
Oil and gas
Iron ore
Oil and gas
Copper ore
Bauxite
2911
3251
2865
2911
331/332
2895
3331
3334
Lime
Iron and steel
Agricultural chemicals
Petroleum refining
Iron and steel
Iron and steel
Petroleum refining
Brick
Organic chemicals
Petroleum refining
Iron and steel
Carbon black
Primary nonferrous metals
Primary nonferrous metals
(thermal cracking)
Calcining
Coking
Ammonia steam reforming
Gas/oil hydrotreating
Heat treatment
Steelmaking
- open hearth furnace (71.8)
- basic oxygen furnace (14.4)
Naphtha hydrotreating
Drying/firing
Benzene
Alkylation
Cast iron melting
- cupola furnace (21.7)
- induction furnace (16.1)
Furnace process
Copper smelting
Alumina calcining
1012 Btu/yr
Oil and gas
Iron ore
Oil and gas
Limestone
Oil and gas
Iron ore
Oil and gas
Oil and gas
Sand and
gravel
Oil and gas
2911
331/332
2911
3241
2911
331/332
2911
2911
3211/3221
73223
2869
Petroleum refining
Iron and steel
Petroleum refining
Hydraulic cement
Petroleum refining
Iron and steel
Petroleum refining
Petroleum refining
Glass
Organic chemicals
Atmospheric distillation
Slabbing and blooming
- reheat furnaces (271.5)
- soaking pit (156.3)
Catalytic reforming
Calcining
Vacuum distillation
Blast furnace
Coking (delayed)
Fluid bed catalytic cracker
Melting
Ethylene/propylene
529.3
427.8
407.1
324.5
296.5
267.3
266.2
229.2
227.2
194.5
145.9
144.8
139.0
119.9
111.5
86.2
77.8
52.8
44.8
42.8
37.8
35.7
34.7
30.0
4,273.3
principal pollutant is usually particulates
from that material. Therefore a switch to
coal in such a situation will not have a
large impact on paniculate emissions,
although emissions of SOX would
increase.
There are several processes where
future fuel switching could occur with
significant impacts on process emis-
sions. The furnaces used for heating of
semi-finished steel in slabbing and
blooming and in heat treatment processes
have emissions which are solely products
of combustion. Therefore, firing of fuels
other than conventional fuels (natural
gas, fuel oil, and coke oven gas) could
have significant effect on type and
amounts of emissions. The fact that
these furnaces account for 0.54 quads
of energy consumption makes their
potential impact of particular concern.
Similarly, a switch in fuel for copper
reverberatory smelting from oil or gas to
coal could result in significantly in-
creased SOX and NOX emissions.
In at least one case, emissions may be
decreased by a change in the process
which results in fuel switching. At
present there are two furnaces used for
cast iron melting: cupola and induction
furnaces. Cupola furnaces are controlled
sources of trace and volatile metals. The
recent trend toward increased electric
induction melting has the effect of
lowering emission levels at the facility,
while improving product quality. While
increased emissions will result at the
electric power plant which powers the
induction furnaces, these emissions
can be controlled more cost-effectively
than at the cast iron melting operation
itself.
4
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Benjamin L. Blaney is the EPA author and also the EPA Project Officer (see
below): Jay R. Hoover and James R. Blacksmith are with Radian Corporation.
Austin, TX 78766; Paul W. Spaite is a consultant, 6315 Grand Vista Avenue,
Cincinnati, OH 45213.
The complete report, entitled "Energy Use Patterns and Environmental Implica-
tions of Direct-Fired Industrial Processes," (Order No. PB 81-234 221; Cost:
$9.50, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
U. S. GOVERNMENT PRINTING OFFICE: 1982/559-092/3380
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