United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S7-85/040 Nov. 1985
&EFW Project Summary
Recent Developments in
S02 and NOX Abatement
Technology for Stationary
Sources in Japan
Jumpei Ando
This report is a compilation of infor-
mation on the current status of abate-
ment technology used to control major
air pollutants (including SO2, NOX, and
particulates) in Japan. It focuses on flue
gas desulfurization (FGD), combustion
modification (CM), and selective cata-
lytic reduction (SCR) of NO>. Informa-
tion in this report was gathered from
utility company representatives and
FGD, CM, and SCR process developers,
as well as from the author's research in
this field. Current air pollution regula-
tions in Japan, related problems, opera-
tional parameters of commercial FGD
and SCR plants, FGD and SCR eco-
nomics, and the author's evaluation of
the processes also are described.
This Project Summary was developed
by EPA's Air and Energy Engineering
Research Laboratory. Research Triangle
Park, NC, 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 infor-
mation at back}.
Introduction
To attain stringent Japanese ambient
air quality standards of 0.04 ppm (daily
average)for S02 and 0.04-0.06 ppm (daily
average) for NO2, the emission regulations
have been tightened, requiring further
S02 and NOX abatement. In 1984, the
total number of FGD plants in Japan
reached 1,400, with a total capacity of
130 x 106 NmVh (42,000 MW equiva-
lent). About 62% (total capacity) of the
FGD plants use a wet lime/limestone
process. Another 28% use sodium scrub-
bing. About 8% (total capacity) of the FGD
plants use processes that produce sulf uric
acid, elemental sulfur, or ammonium
sulfate by-products.
Nitrogen Oxides
For NO* abatement, extensive combus-
tion modifications (CMs)—including flue
gas recirculation (FGR), staged combus-
tion, and use of low-NO, burners—have
been applied to numerous combustion
facilities. The NO,concentrations in utility
boiler flue gases have been lowered to
150-300 ppm for coal-fired boilers, 80-
130 ppm for oil-fired boilers, and 40-60
ppm for gas-fired boilers. For additional
NOX abatement, about 160 selective
catalytic reduction (SCR) plants have been
constructed. Total SCR capacity reached
90 x 108 NmVh (29,000 MW) equivalent
by the end of 1984; of this capacity,
24,000 MW was applied to utility boilers.
About 60% of the SCR plants are used
with oil-fired utility boilers, 21 % are used
with coal-fired boilers, and 19% for gas-
fired boilers.
Sulfur Dioxide/Nitrogen Oxides
In 1983 and 1984, 14 coal-fired utility
boilers either began operation or were
scheduled to go into operation. All of
these boilers use FGD to remove about
85-98% of SO2 and produce a by-product
gypsum. Thirteen boilers use combustion
modification and SCR to remove 68-85%
of NOX. The emission concentrations
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produced by these 14 coal-fired boilers
are 30-100 ppm SO2 and 20-200 ppm
NOX with 20-100 mg/Nm3 of dust. All
FGD and SCR plants for coal-fired boilers
have been operated with over 99% reli-
ability.
Results
Due to these air pollution control
efforts, ambient S02 concentrations in
Japan have been lowered to meet the
stringent standard in virtually all regions
of the country including large industrial
areas. The ambient N02 concentrations
have been decreasing since 1983 in spite
of the rapid increase in the number of
automobiles. Japan's N02concentrations
have met the stringent standard in most
regions, even in large cities. Photochem-
ical smog has been reduced as a result of
the abatement of NO, and hydrocarbons.
Virtually no acid rain has been experi-
enced due to effective S02 and NOx
abatement and Japan's topography.
Economics
The cost of both FGD and SCR has been
lowered, due mainly to technology im-
provements. The investment cost for
limestone-gypsum process FGD plants
for coal-fired boilers has been lowered
from about 30,000 yen/kW in 1979-
1980 to about 20,000 yen/kW in 1983-
1984. The power consumption of FGD
processes was also reduced from 2.0-
2.5% to 1.4-2.1 %. The annualized cost of
the wet limestone gypsum process is
currently about 1.5 yen/kWh including 7
years depreciation and 10% interest.
The investment cost of SCR for utility
boilers in yen/kW is 5,000-7,000 for
coal-, 4,000-5,000 for oil-, and about
2,500 for gas-firing. The annualized SCR
cost in yen/kWh including 7 years depre-
ciation and 10% interest is 0.5-0.6 for
coal-, 0.2-0.3 for oil-, and about 0.15 for
gas-firing.
The cost of generating power by coal
combustion—including the cost for ash
disposal, SCR, and FGD—is lower than
that for burning low sulfur oil, although
both fuels produce a similar quality flue
gas. Several large combined-cycle power
plants (700-1,000 MW) that burn natural
gas (either existing or planned) use SCR
to remove 80-85% of NOX.
Conclusions
SCR is simple and easy to operate but is
much more costly than combustion modi-
fication. FGD and combustion modifica-
tion may be used to prevent acid rain, and
SCR can be used when further NOx
abatement is needed.
Selective noncatalytic reduction (ther-
mal DeNOx) has been used commercially
but has not become' popular in Japan
because of its low efficiency and high
ammonia leakage. Many other NO* re-
moval and simultaneous SO2/NOX re-
moval processes have been tested and
are used commercially in small plants.
Most of these processes are not used at
large plants because of their high cost or
by-product disposal problems.
Although Japan has succeeded in
controlling SO2 and NOX emissions to a
considerable extent, additional research
is underway to improve the cost effec-
tiveness of emission control technology.
Jumpei Ando is with the Faculty of Science and Engineering, Chuo University,
Kasuga, Bunkyo-ky, Tokyo 112, Japan.
J. David Mobley is the EPA Project Officer (see below).
The complete report, entitled "Recent Developments in SOZ and NO* Abatement
Technology for Stationary Sources in Japan," (Order No. PB 86-110186/AS;
Cost: $22.95, 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:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S7-85/040
0000329 PS
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