S-EPA
United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S7-81-015 Apr. 1981
Project Summary
Interagency Flue Gas
Desulfurization Evaluation
Final Report
J. C. Dickerman, D. H. Brown, W. R. Menzies
This report presents the results of a
six-month study of flue gas desul-
furization (FGD) technology conducted
by an interagency team in 1977. The
study was mandated by President
Carter in his April 1977 National
Energy Plan (NEP). The purpose of this
study was to determine whether addi-
tional Federal funding would acceler-
ate the commercialization and accept-
ance of FGD technology. This report
concludes that FGD is the most viable
short-term approach to meeting in-
creased coal-use objectives of the
NEP, and it identifies specific FGD
research, development and demon-
stration priorities. This report also
presents a background of FGD tech-
nology (as of 1977) and the methodol-
ogy used in the study to select the
most promising FGD processes and
subsystems.
This Project Summary was devel-
oped by EPA's Industrial Environ-
mental Research Laborabory in Re-
search Triangle Park, N.C., to an-
nounce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
Since the early 1970's, U.S. energy
policy has focused on the goal of reduc-
ing the country's reliance on dwindling
reserves of natural gas and costly sup-
plies of foreign oil. This policy has
gradually increased the use of coal as a
primary energy source in the U.S., and
the 1977 National Energy Plan was
designed to accelerate this increase in
coal utilization. The projected effect of
the NEP was to raise total coal con-
sumption in 1985 by about 20 percent
over the 1985 base levels. The most
dramatic increase will occur in the
industrial sector, where coal use is
expected to triple over the predicted
1985 base levels.
Because coal will continue to be
burned directly in the near-term, this
projected increase in coal utilization
generates concern over emissions,
particularly of sulfur dioxides, to the
atmosphere. Projected utility and in-
dustrial SOz emissions, including base-
line emissions for 1985 (without accel-
erated coal utilization) and projected
emissions assuming implementation of
the NEP are presented in Table 1. These
emission estimates were constructed
under two regulatory scenarios. The
first, in compliance with current
standards, assumed that:
1. All sources will be governed by
present SOa emission regulations
through 1985.
2. Full compliance with these regula-
tions will be achieved by 1985.
-------
Table 1. Utility and Industrial SOz Emissions
(Millions of Tons per Year)
1975 1985
Actual Baseline
Compliance with Current Standards'
Industry 10.8 12.4
Utility 18.6 20.2
Total 29.4 32.6
Use of Best Available Control Technology (BACTJ2
Industry 10.8 10.8
Utility 18.6 20.2
Total 29.4 31.1
1985
President's
Program
15.9
18.2
34.1
11.7
18.3
30.1
Percentage
Change
Over 1985
Baseline
+28%
f- 10%)
(+ 5%)
(+ 8%)
(- 9%)
(- 3%)
'Assumes full compliance with current standards by 1985: NSPS for new large boilers
and SIP's for new small (10-25 MW) boilers. SIP's govern existing sources not subject
to NSPS.
'Assumes BACT applied to all new utilities which begin operation after 1974 and to
new industrial sources, after 1979.
Source: "Air Pollution Impacts of the Oil and Gas Replacement Program in the
Utility and Industrial Sectors." Executive Office of the President. Energy Policy and
Planning and the U.S. Environmental Protection Agency. June 20, 1977.
The second scenario, use of Best Avail-
able Control Technology (BACT), as-
sumed that:
1. BACT will achieve 80% S02 emis-
sion reduction as a result of 90%
removal efficiency with 90% avail-
ability of local coal.
2. BACT will be applied to all new
utility sources after 1984, and all
new industrial sources after 1979.
3. A revised New Source Performance
Standard (NSPS) of 1.5 lbSC-2/106
Btu for small sources (10-25 MW)
will be promulgated.
4. Existing sources regulated by State
Implementation Plans (SIP's) will
reach full compliance by 1985.
As of June 1977, there were a total of
119 FGD units, including 7,800 MW of
FGD capacity which EPA considered
operational, 12,600 MW under con-
struction, and 30,000 MW planned.
This was a total potential scrubbing
capacity of roughly 51,000 MW out of a
total coal-fired generating capacity of
275,000 MW. Despite the growing use
of FGD systems, controversy still ex-
isted over several key issues such as
reliability, cost, secondary pollutants,
and the ability of vendors to meet
expanded market demands.
Because of the controversy surround-
ing FGD technology, one of the specific
elements included in the NEP was a
"six-month review" to determine which,
if any, FGD systems under development
offered sufficient environmental, cost,
and reliability advantages to merit an
accelerated research, development, and
demonstration (RD&D) program.
In response to the mandate for a
review of FGD technology, an "Inter-
agency Flue Gas Desulfurization Evalu-
ation Study" was initiated to guide
government RD&D and help accelerate
the application of the technology. A
draft report was produced in late 1977.
Although a variety of circumstances
have delayed publication of the final
report, the methodology developed as
part of this study is still useful in
comparing and evaluating processes at
the different stages of development.
This study, which has been widely used
in shaping government funding priori-
ties for FGD research and development,
also provides useful data and conclu-
sions regarding the prospects of near-
term progress in improving FGD effi-
ciency, reliability, and costs.
The major conclusions of this study
remain valid, even if some of the mate-
rial is dated. In fact, the need to bring
new FGD systems and processes on-
stream is even more pressing today
than it was in 1977. During the period
from 1977 to 1979, several developments
occurred that underscore the need for
increased coal utilization over the short-
term and continued progress in reducing
emissions from coal combustion. These
include the promulgation of more strin-
gent NSPS for utility boilers, the disrup-
tion of foreign crude oil supplies, sharp
increases in OPEC oil prices, the enact
ment of legislation prohibiting the useo
oil and gas in many new utility am
industrial facilities, and the growing
uncertainty of nuclear energy.
A total of 138 processes, both nations
and international, were surveyed anc
then screened as to their potential for
offering technological and/or economic
advantages over the following six com-
mercial and developing FGD processes:
• Lime/Limestone Wet Scrubbing
• Magnesia Slurry Scrubbing
• Wellman-Lord
• Sodium/Lime Double Alkali
• Citrate Buffered Absorption
• Rockwell International - Aqueous
Carbonate Process
The process evaluators felt that the
screening criteria provided an effective
means of comparing FGD processes.
However, some processes received high
ratings even though they had limited
acceptability due to some unique process
characteristics. Also, some processes
received low ratings due to their devel-
opment status even though they were
judged to have more potential than
some of the processes with higher
ratings so that engineering judgement
was used as a screening criteria as well
as evaluation criteria.
Recommendations
The most effective way to advance
FGD technology would be through
RD&D funding to find near-term solu-
tions to problems faced by commercial
and near-commercial processes. A
secondary priority should be assigned to
processes and process developments
that provide longer-term benefits. The
following recommendations were devel-
oped to meet both of these objectives.
Evaluation and use of magnesium as
a mass transfer additive along with the
use of organic and inorganic chemicals,
such as adipic acid and sodium carbon-
ate, is one of several methods for
improvement of S02 removal from
lime/limestone systems. Forced oxida-
tion could reduce sludge disposal prob-
lems. Contactors could significantly
reduce the cost and complexity of scrub-
bing, particularly the Chiyoda 121
system. Hardware improvements in
instrumentation, mist eliminators, re-
heaters, and stack liners could greatly
reduce recent FGD system failures.
. Sulfur production with carbon instead
of a reducing gas could significantly
enhance FGD applicability due to its 4
potential for reducing cost, complexity, *
-------
and secondary pollution. Moreover,
RD&D efforts on the Rockwell Inter-
national Molten Carbonate Regenera-
tion System would demonstrate direct
conversion of SOz to sulfur also without
a reducing gas. Application of a low-Btu
gas as a reductant in FGD systems could
also eliminate this system's dependence
on costly and scarce supplies of natural
gas. Lastly, sulfur production in the
calciner and sustained sulfuric acid
production from a full-scale system,
both aspects of magnesia slurry scrub-
bing, could enhance process applicability.
Limestone use in double-alkali sys-
tems as a regenerant can potentially
improve operating costs because it is
less expensive than lime as a raw mate-
rial. Furthermore, methods for evaluat-
ing and testing regeneration of sodium
sulfide by-products would further reduce
raw material costs as well as eliminate
disposal problems.
Studies of alternative or improved
energy production technologies would
be of great value to the industry. For
instance, the Sorption/Steam Stripping
concept has potential for more reliable,
lower cost operation than some other
regenerable systems. The Dowa Process
appears to have significant advantages
over current double-alkali FGD tech-
nology because it uses limestone as a
regenerant and produces a marketable,
quality gypsum by-product. The Inte-
grated Cat-Ox system also shows cost
advantages over current FGD technology
at the 100 MW level. Finally, the Sulf-X
process has potential as a SOx/NO* flue
gas treatment process.
Conclusions
The results of this study showed that
significant benefits can be derived by
increasing Federal funds for FGD RD&D
programs. Increased funding should
also be used for research and develop-
ment projects to improve both throw-
away and regenerable systems that
have been demonstrated on large-scale
equipment. With adequate funding,
process and subsystem evaluations of
potential solutions to common FGD
problems and new developments in
FGD technology could be assessed and
promulgated with greater economy,
efficiency, and accuracy to the entire
industry.
J. C. Dickerman, D. H. Brown, and W. R. Menzies are with Radian Corporation.
Austin, TX 78766.
R. D. Stern is the EPA Project Officer (see below).
The complete report, entitled "Interagency Flue Gas Desulfurization Evaluation:
Final Report," (Order No. PBS 1-152 043; Cost: $33.50, subject to change) will
be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
(, US. GOVERNMENT PRINTING OFFICE: 1M1 757-012/7057
-------
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Fees Paid
Protecton
Agency
EPA 335
Official Business
Penalty for Private Use S300
RETURN POSTAGE GUARANTEED
Third-Class
Bulk Rate
0000329
------- |