United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/SR-93/064 August 1993
v^EPA Project Summary
Proceedings: 1991 SO2
Control Symposium
Brian K. Gullett
These proceedings document the
1991 SO2 Control Symposium, held De-
cember 3-6, 1991, in Washington, DC.
The symposium focused attention on
recent improvements in conventional
sulfur dioxide (SOJ control technolo-
gies, emerging processes, and strate-
gies for complying with the Clean Air
Act Amendments (CAAA) of 1990. It
provided an international forum for the
exchange of technical and regulatory
information on SO2 control technology.
More than 800 representatives of 20
countries from government, academia,
flue gas desulfurization (FGD) process
suppliers, equipment manufacturers,
engineering firms, and utilities attended.
In all, 50 U.S. utilities and 10 utilities in
other countries were represented. In 11
technical sessions, speakers presented
111 technical papers on development,
operation, and commercialization of wet
and dry FGD, clean coal technologies,
and combined sulfur oxide/nitrogen
oxide (SO^NOJ processes.
This Project Summary was developed
by EPA's Air and Energy Engineering
Research Laboratory, Research Tri-
angle Park, NC, to highlight key topics
of interest on SO2 control that are fully
documented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
The Symposium, jointly sponsored by
the Electric Power Research Institute
(EPRI), the Air and Energy Engineering
Research Laboratory of the U.S. Environ-
mental Protection Agency (AEERL/EPA),
and the U.S. Department of Energy (DOE),
is held periodically to transfer technical
information and advance technology de-
velopment application for control of sulfur
dioxide (SO2) emissions from fuel com-
bustion.
The proceedings from this Symposium
are five volumes, containing 111 presented
papers covering 14 technical sessions:
Session Subject Area
I Opening Remarks (EPRI,
EPA, and DOE guest speak-
ers)
1 Emission Allowance Panel
Discussion
2 Clean Air Act Compliance
Strategies
3A Wet FGD Process Improve-
ments
3B Furnace Sorbent Injection
4A Wet FGD Design Improve-
ments
4B Dry FGD Technologies
5A Wet FGD Full Scale Opera-
tions
5B Combined SO,/NOX Tech-
nologies
6A Wet FGD Operating Issues
6B Clean Coal Demonstrations/
Emerging Technologies
Printed on Recycled Paper
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8A
8B
Poster Session (papers on
all aspects of SO2 control)
Commercial FGD Designs
FGD By-Product Utilization
These proceedings also contain open-
ing remarks by the co-sponsors and com-
ments by the three guest speakers. The
guest speakers were Shelley Fidler - As-
sistant, Policy Subcommittee on Energy
and Power, U.S. Congress; Jack S. Siegel
- Deputy Assistant Secretary, Office of
Coal Technology, U.S. DOE; and Michael
Shapiro - Deputy Assistant Administrator,
Office of Air and Radiation, U.S. EPA.
Clean Air Act Compliance issues were
discussed in a panel discussion on emis-
sion allowance trading and a session on
compliance strategies for coal-fired boil-
ers.
Key Points
• To comply with Title IV of the CAAA
in Phase I, wet limestone and lime
FGD systems will dominate a very
competitive scrubber market. By
Phase II, a total of 40-50 GW of scrub-
bing will be in place.
• Additives are increasing wet FGD sys-
tem performance to >95% SO2 re-
moval. Methodologies are being de-
veloped to evaluate an abundance of
wet FGD design improvements.
• The $5 billion Clean Coal Technology
Program has demonstrated and is
continuing to demonstrate the com-
mercial feasibility of technologies that
have already reached proof-of-con-
cept stage.
• In the area of dry FGD systems, fur-
nace, economizer, and duct injection
are low-capital-cost emerging tech-
nologies for retrofit of older coal-burn-
ing boilers. Newly developing simul-
taneous SOj/NO,, technologies expand
the choices available to boiler opera-
tors and ease operational problems
with a combined system.
• In addition to SO2 control technolo-
gies, the symposium highlighted the
many uncertainties surrounding com-
pliance with the CAAA. These unre-
solved issues include EPA's pending
decision on NOX regulation for Phase
I Group 1 units under Title IV, visibil-
ity, a short-term ambient air standard
for SO2, air toxics, and air standards
for NOX emissions in ozone
nonattainmerit areas. Present operat-
ing issues include continuous emis-
sion monitoring systems, mist elimi-
nator system problems, and acid mist
emissbns. Key regulatory uncertain-
ties include accounting issues, taxa-
tion concerns, and planning questions.
Several presenters encouraged ac-
tive utility participation in the resolu-
tion of many of these issues.
Opening Remarks
Since the previous SO2 Control Sympo-
sium in May 1990, Congress passed the
Clean Air Act Amendments of 1990. To
comply with the CAAA, EPRI expects
scrubbing of 12-15 GW of utility capacity
in Phase I, a 40-50 GW scrubbing total by
Phase II, and extensive coal switching in
both phases.
Wet limestone and lime FGD systems
are dominating the market in Phase I, and
limestone forced oxidation systems are
the most often selected technologies. Ad-
ditives and enhanced designs are increas-
ing performance to >95% SO2 removal.
Dry FGD systems are a niche market, and
air toxics are becoming a factor in select-
ing scrubbers because of potential up-
coming air toxics legislation.
Various unresolved issues will signifi-
cantly impact how utilities control SO2.
These issues include EPA's pending deci-
sion on NOX regulation in Phase I, plume
visibility, and a short-term ambient air stan-
dard for SO2.
One year after passage of the CAAA,
numerous questions relating to the role of
50 to 70% removal technologies, coal
cleaning versus control technologies, and
emerging technologies still remain unan-
swered. Many utilities have announced
they may choose compliance strategies
that rely on low-sulfur coal or fuel switch-
ing and may defer a decision on technol-
ogy options until the tougher Phase II
requirements in the year 2000.
Clean Air Act Amendments
Overview
Two featured luncheon speakers pro-
vided overviews of the Clean Air Act
Amendments of 1990. Shelley Fidler, As-
sistant, Policy Subcommittee on Energy
and Power, encouraged active participa-
tion by all in the industry in shaping CAAA
implementation.
Michael Shapiro of EPA, characterized
the CAAA as environmentally aggressive,
the first use of a cap on total emissions,
and a test of a novel market-based ap-
proach to allowance trading.
Emission Allowance Trading
Utilities are reluctant to buy or sell emis-
sion allowances, according to EPRI, until
the rules are clearer and the market is
favorable. Although there are no trades
yet, many utilities are planning to trade if
appropriate.
Alice LeBlanc of the Environmental De-
fense Fund stated that the CAAA man-
dates tough environmental goals,
introduces a market-based trading sys-
tem, motivates innovation in the utility in-
dustry, and sets a key precedent for future
legislation.
Craig Glazer, Chairman of the Ohio Pub-
lic Utility Commission, suggests a proactive
approach to promoting an active emission
allowance trading market. He suggested
that utilities follow a planning approach
that includes listing all feasible plant op-
tions, ranking these by cost-effectiveness,
inputting them to a production costing
model, and then calculating revenue re-
quirements for each option.
Compliance Strategies
CAAA compliance strategies were dis-
cussed from a variety of perspectives, in-
cluding the impact of scrubbing in Phase
I, roles of scrubbing and emission allow-
ance trading, methodologies for determin-
ing strategies, costs for use in these
methodologies, and international impacts.
C.E. Fink of Consolidation Coal Com-
pany indicated that up to 50 % of total
Phase I SO2 reductions could be achieved
with scrubbing and gave reasons why
scrubbers are a low-cost compliance strat-
egy-
Regarding the costs of various scrub-
bing technologies, a recently completed
EPRI-sponsored project updated the costs
of 26 FGD processes to 1990 dollars and
also analyzed the technical merit and com-
mercial status of currently available and
emerging SO2 control technologies.
Future Issues
Several issues will impact the way elec-
tric utilities comply with the CAAA. These
include air toxics, NOX emissions in ozone
nonattainment areas, waste minimization,
and water quality. Most of these will be
the subject of legislation in the next few
years.
The CAAA requires several detailed
studies of the risks associated with fossil-
fuel combustion. Based on these studies,
EPA will determine whether further con-
trols are needed. Ongoing studies by EPRI,
DOE, and others will provide information
to assist in this evaluation of air toxics.
New Developments In Wet FGD
In the area of process improvements to
wet FGD, increasing SO2 removal effi-
ciency was the focus of several presenta-
tions. In an attempt to dispel the negative
connotation of using additives that is preva-
lent in the industry, R.E. Moser of EPRI
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provided an overview of the current status
of additive use in wet FGD systems and
the functions they may perform in future
designs.
The session on wet FGD design im-
provements emphasized both increasing
SO2 removal efficiency and reducing costs.
Improvements in new as well as retrofit
designs were discussed. EPRI is investi-
gating a range of design options, includ-
ing the use of trays and packing, additional
liquid flow rate, and performance addi-
tives, for limestone and magnesium-en-
hanced lime systems to determine SO2
collection capability and relative costs.
Wet FGD Operation
Two presentations summarized wet FGD
technology currently used in many operat-
ing plants. A. Saleem of General Electric
Environmental Services covered the de-
sign and operation of single-train open
spray tower FGD systems, and P. Rader
of ABB Environmental Systems described
the design of advanced limestone wet FGD
systems in retrofit applications. While fu-
ture operating issues include control of air
toxics, present operating issues include
continuous emission monitoring systems
(CEMs), mist eliminator system problems,
and acid mist emissions.
Clean Coal Demonstrations/
Technologies
In 1986, the U.S. DOE initiated the
Clean Coal Technology (CCT) Program to
demonstrate the commercial feasibility of
technologies that have already reached
the proof-of-concept stage. Status reports
on several CCT projects were presented
later in the afternoon. R. Bolli of Ohio
Edison presented current design features
and recent test results from various Ohio
Edison CCT projects.
Results from the Limestone Injection
Multistage Burner (LIMB) extension test-
ing at Edgewater were presented by T.
Goots of B&W. LIMB combines furnace
sorbent injection (FSI) of lime with
humid if ication after the air heater and use
of low-NOx burners to reduce both SO2
and NOX emissions. FSI, in which sorbent
injected in the furnace reacts with SO2
and is removed by particulate controls,
can achieve moderate SO2 reduction (ap-
proximately 50%) at a cost per ton of
sulfur removed claimed to be lower than
for wet FGD.
Dry FGD Technologies
Dry FGD processes include FSI, duct
injection, and spray drying (dry scrubbing).
Some of these technologies can signifi-
cantly reduce capital costs, compared to
conventional wet scrubbing. Dry processes
can be divided into two categories: highl-
and low-temperature processes.
High-Temperature Processes
Two utility-scale generating unit appli-
cations of FSI with low NOX burners (LIMB)
were presented. One of these, LIMB, lo-
cated at Ohio Edison's Edgewater Sta-
tion, is discussed in the section on Clean
Coal Technologies. The second, an EPA-
sponsored LIMB installation at the 180-
MW Yorktown Unit 2 of Virginia Power
Company, was reviewed by J. P. Clark of
ABB Combustion Engineering Systems.
Clark detailed plans for an 8-month test
scheduled for 1992.
Low-Temperature Processes
The Limestone Emission Control (LEG)
process removes SO2 using a moving bed
of quarry-sized limestone, as covered by
M.E. Prudich of Ohio University. DOE's
duct injection technology program , funded
through the Pittsburgh Energy Technol-
ogy Center, will result in a duct injection
design handbook.
The EPA-developed advanced silicate
(ADVAGATE) technology is a lime-based,
duct injection process, in which silica-con-
taining ash is reacted with lime at modest
temperature to remove SO2. EPA's C.
Sedman outlined recent ADVACATE pro-
cess optimization in a pilot plant and re-
ported plans for a 10-MW field evaluation
at TVA's spray dryer/ESP pilot plant at
the Shawnee Test Facility in 1992.
Combined SCyNOx
Technologies
EPRI has evaluated the potential for
developing combined SOj/NOx technolo-
gies to provide attractive alternatives to
conventional wet FGD and selective cata-
lytic reduction (SCR). For new plants, the
NOXSO, Copper Oxide, Zinc Oxide, and
SNOX processes were rated equivalent
or preferable to wet FGD/SCR.
Various combined SO2/NOX processes
were also discussed. Pilot-scale results of
a furnace urea/sorbent slurry injection tech-
nology were reviewed by EPA's B. K.
Gullett. This EPA-sponsored project dem-
onstrated the successful combination of
Ca-based sorbent injection and selective
non-catalytic reduction (SNCR) technolo-
gies in a slurry process. D. Helfritch of R-
C Environmental Services & Technologies
presented results of subscale tests for use
in a proof-of-concept demonstration of an
integrated dry injection process consisting
of combustion modification using low NO,
burners, dry injection of hydrated lime at
the economizer, dry injection of sodium
bicarbonate at the air heater exit for addi-
tional SO2 and NOX removal, and flue gas
humidification for ESP conditioning.
Conclusion
To comply with the CAAA in Phase I,
wet limestone and lime FGD systems will
dominate a very competitive scrubber mar
ket. By Phase II, a total of 40-50 GW of
scrubbing will be in place.
The 1991 EPRI/EPA/DOE SO2 Control
Symposium presented many improve
ments in SO2 control technology that will
help utilities cost-effectively attain these
levels of scrubbing. Additives are increas
ing wet FGD system performance to >95%
SO2 removal. The $5 billion CCT Program
has demonstrated and is continuing to
demonstrate the commercial feasibility of
technologies that have already reached
proof-of-concept stage.
In the area of dry FGD systems, fur-
nace, economizer, and duct injection are
low-capital-cost emerging technologies for
retrofit of older coal-burning boilers. Dry
technologies like EPA's ADVACATE, cur-
rently undergoing larger scale demonstra-
tion, show promise for >90% SO2 removai.
Newly developing simultaneous SOg/NO,
technologies expand the choices available
to boiler operators and ease operational
problems with a combined system.
In addition to SO2 control technologies,
the symposium highlighted the many un-
certainties surrounding CAAA compliance.
Various unresolved issues will significantly
impact how utilities control SO2. These
issues include EPA's pending decision on
NOX regulation in Phase I, visibility, a short-
term ambient air standard for SO2, air
toxics, NOX emissions in ozone
nonattainment areas, waste minimization,
and water quality. Present operating is-
sues include CEMs, mist eliminator sys-
tem problems, and acid mist emissions.
Key regulatory uncertainties include ac-
counting issues, taxation concerns, and
planning questions. Several presenters
encouraged active participation in the reso-
lution of many of these issues.
•ffV.3. GOVERNMENT PRINTING OFFICE: 1993 - 750-07I/UO044
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Brian K. Gullett is the EPA Project Officer (see below).
The complete report, entitled "Proceedings: 1991 SO2 Control Symposium, Vol-
umes 1, 2, 3, 4, and 5," (Order No. PB93-196095/AS; Cost: $52.00; 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:
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
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PERMIT No. G-35
EPA/600/SR-93/064
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