United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/SR-95/015
February 1995
EPA Project Summary
Proceedings: 1993 SO2 Control
Symposium
Brian K. Gullett
This report compiles over 100 pa-
pers presented at the 1993 Sulfur Diox-
ide (SO2) Control Symposium held in
Boston, MA, August 24-27, 1993. Pa-
pers in this symposium covered a
wide range of topics: industry's strat-
egies for dealing with the Clean Air
Act Amendments of 1990, including
Phase I strategies, the emission al-
lowance trading system, and retrofit
construction; additives, materials, and
operating issues for wet flue gas des-
ulfurization (FGD); clean coal demon-
stration programs; the effect of FGD
systems on air toxics; dry FGD tech-
nologies of spray drying and furnace
sorbent injection; applied SO2 con-
trol research results and emerging
acid rain control technologies; and
waste disposal issues. Papers cov-
ered results obtained from full-scale
demonstration/operation to pilot- and
bench-scale work.
This Project Summary was developed
by EPA's Air and Energy Engineering
Research Laboratory, Research Tri-
angle Park, NC, to highlight key topics
on SO2 control. Full documentation of
the report of the same title is available
(see Project Report ordering informa-
tion at back).
Introduction
The symposium was jointly sponsored
by the Air and Energy Engineering Re-
search Laboratory, U.S. Environmental
Protection Agency (AEERL/EPA), the Elec-
tric Power Research Institute (EPRI), and
the U.S. Department of Energy (DOE). It
is held approximately every 18 months to
transfer technical information from labora-
tory research, pilot-scale tests, and field
demonstrations on technologies for reduc-
tion of SO2 emissions from fossil fuel com-
bustion. This symposium was held in Bos-
ton, MA, August 24-27, 1993. The pro-
ceedings from the symposium are avail-
able in four volumes, covering over 100
papers in 13 technical sessions:
Session Subject Area
1 Clean Air Act Regulatory Strat-
egies
2 Phase I Designs
3A Additives for High Efficiency
FGD
3B Materials for FGD
4A Clean Coal Demonstrations
4B Applied Research
5A Dry FGD Technologies
5B Wet FGD Process Issues
(Part I)
6A Air Toxics Removal in FGD Sys-
tems
6B Wet FGD Process Issues
(Part II)
7 Poster Papers
8A Emerging Technologies
8B Waste Utilization and Disposal
Clean Air Act Regulatory
Strategies
Four papers comprised the introductory
session, Session 1, to the symposium.
The first paper presented the potential
synergies and conflicts that have arisen
between the acid rain provisions of the
Clean Air Act Amendments of 1990
(CAAA) and the other titles involving haz-
ardous air pollutants. These conflicts may
lead to inefficient decisions by utilities as
their risk-averse posture and the structure
of the CAAA discourage integrated deci-
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sions in reaching the goals of all titles of
the CAAA. Another paper presented a
model based on four utilities' data that
estimates key factors regarding the SO2
allowance trading system. An interactive
multidimensional analysis for risk assess-
ment was described by 1) a risk-based
methodology for setting detection limits
for field testing and 2) a framework for
analyzing health risks from mercury emis-
sions. The last paper of the session de-
scribed the Clean Air Technology,
Workstation™*, a tool for determining the
economics of methods for systemwide
emission reduction. This system allows
commercial and emerging technologies to
be evaluated and allows users to vary
system parameters of unit configurations,
technologies, and fuels.
Phase I Designs
This session (Session 2) contained eight
papers that discussed system designs for
meeting Phase I requirements of the
CAAA. Wet lime or limestone FGD sys-
tems were or will be installed or retrofitted
by Indiana Power & Light Company, Ten-
nessee Valley Authority (TVA), the
Conemaugh Station owners, Kentucky
Utilities (with fuel switching), Henderson
Municipal Power and Light, Navajo Gen-
erating Station, and PSI Energy Inc. Guide-
lines for economics decisions, design, and
retrofit concerns for duct injection systems
were also presented.
Additives for High Efficiency
FGD
Wet FGD systems' SO2 removal can
often be improved by use of additives. In
this session (Session 3A), papers were
presented discussing the effect of organic
acid additives (dibasic acid, formate) on
pilot- and full-scale facilities both in terms
of SO2 removal and solids disposal prop-
erties. A model was developed and tied
into EPRI's FGD Process Integration and
Simulation Model ( FGDPRISM) that esti-
mates consumption rates of dibasic acid
and formate ion in wet limestone FGD
systems. A new ammonia-based process
on a pilot plant using ammonium sulfate
liquor for SO2 absorption was described.
The process produces high purity ammo-
nium sulfate crystals with market value.
Materials for FGD
Eight papers in Session 3B covered
topics related to materials of construction
for FGD systems. Topics covered included
* Mention of trade names or commercial products does
not constitute endorsement or recommendation for
use.
economics, comparative technical perfor-
mance, and design considerations. Struc-
tural materials and coatings used in ducts,
towers, stacks, sumps, tanks, and pumps
were discussed for a PSI Energy, Inc.,
unit. An EPRI research program investi-
gating a wide variety of construction ma-
terials for FGD systems was presented
with feedback from operating FGD plants.
Finally, a failure analysis of FGD materi-
als from 33 different investigations was
reported, showing that 31% of failures re-
sulted from quality control breakdown and
27% resulted from inadequate material
selection.
Clean Coal Demonstrations
Results from DOE's Clean Coal Tech-
nology program were presented for eight
implementations in Session 4A. Bechtel's
Confined Zone Dispersion Technology,
Pure Air's demonstration at the Bailly Gen-
erating Station, Ohio Edison's SNOX tech-
nology, the Passamaquoddy Technology,
L.P. potassium or sodium process,
Babcock & Wilcox's SOX -NOx-ROx BOx™
(SNRB) process, the Chiyoda CT-121
project at Georgia Power's Plant Yates
(Unit #1), Tampella Power Corporation's
LIFAC sorbent injection technology, and
the Air Pol, Inc., demonstration of Gas
Suspension Absorption FGD were all dis-
cussed in papers from this session.
Applied Research
This session (4B) covered research-ori-
ented topics in eight papers. A paper from
University of Lund, Sweden, reviewed the
limits and potential of furnace sorbent in-
jection, finding that small particles (< 3 m)
with sufficient mixing can achieve 95%
SO2 removal at a residence time of 2s
and at a calcium/sulfur ratio of 2/1. The
application of gas-phase ionic chemistry
for pollution control was discussed, in-
cluding a look at the equipment, experi-
mental results, applications, and costs.
Work from the Universidad de Cantabria,
Spain, was presented on kinetic modeling
of the low temperature, humidified reac-
tion of hydrated lime in an FGD system.
Production of the ADVAnced siliCATE
(ADVACATE) sorbent utilizing fly ash was
examined, where researchers at the Uni-
versity of Texas at Austin related batch-
and flow-reactor-derived sorbents and
found that grinding the ash dramatically
increased the reaction rate. Researchers
at Lawrence Berkeley Laboratory pre-
sented development of a catalyst capable
of >90% sulfur yield for a process that
would catalytically reduce SO2 to elemen-
tal sulfur. The University of Kentucky and
TVA presented results on pilot scale tests
of a circulating bed absorption system,
covering effects of stoichiometry, gas tem-
perature, fuel chloride, gas residence time,
and total sulfur capture. The University of
Cincinnati's work on sorbents for spray
dryers slurried fly ashes with quicklime
and determined reactivity, suggesting that
the compressive strength of the material
may be a reactivity indicator. Other work
at the university studied the economizer
temperature reactivity of injected calcium
hydroxide and dolomitic hydroxide sor-
bents.
Dry FGD Technologies
Several varieties of dry sorbent sys-
tems for FGD were covered in eight pa-
pers in Session 5A. Furnace sorbent in-
jection (FSI) processes were discussed in
papers on full-scale results. A paper by
Combustion Engineering, Inc., Virginia
Power Company (VPC), and EPA dis-
cussed optimization (in progress) of the
combined SO2/NOX demonstration at
VPC's Yorktown Power Station. A com-
bined SO2/NOX retrofit program at the
Bastardo power plant in Italy was dis-
cussed. Combining gas reburning with
FSI (GR-SI), a Clean Coal Technology
Round I demonstration project was dis-
cussed, along with results from an earlier
project. An overview of supported sorbents
technology (magnesia or lime coated on
vermiculite or perlite substrates) and dem-
onstration results was presented. Pilot-
scale work on spray dryers with fabric
filters achieving 95% SO2 removal was
discussed for medium- and high-sulfur
coals. The final three papers presented
commercial operating results for dry FGD
technologies in Canada, Japan, and Ger-
many.
Wet FGD Process Issues (Part I)
This session (5B) contained seven pa-
pers on various issues related to wet FGD
processes. Several papers compared and
discussed inhibited and fully oxidized op-
erating modes of wet lime and limestone
FGD systems. Topics of operating guide-
lines for cyclic FGD systems, high effi-
ciency pilot plant results, control of a lime-
stone grind circuit, design of mist elimina-
tors, and economics of chloride removal
were covered.
Air Toxics Removal in FGD
Systems
With the passage of the CAAA, control
of toxic or hazardous air pollutant emis-
sions may become an issue of concern
for facilities burning fossil fuels. Eight pa-
pers in this session (6A) covered various
topics related to air toxics control and the
interrelationship with control of SO2. EPRI's
program on reviewing air toxics literature
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coupled with its pilot wet FGD tests for
mercury removal were presented. Other
topics included the ability of available con-
trol technologies to deal with organic and
metallic pollutants; performance of three
spray dryer pilot plants at removal of mer-
cury, selenium, and boron; reduction of
submicrometer metal emissions of arsenic,
selenium, mercury, and antimony by FSI;
performance of SNRB versus electrostatic
precipitators for collection of air toxics;
effect of a semi-dry FGD system in Ger-
many to remove heavy metals; and the
use of Fourier Transform Infrared technol-
ogy as a continuous emission monitor.
The session closed with a summary of
research needs in air toxics determined
from a workshop sponsored by EPRI and
DOE.
Wet FGD Process Issues (Part
II)
This session (6B) continued papers on
this topic started in Session 5B. Seven
papers were presented, covering devel-
opment of a plume opacity engineering
workbook, reduction of sulfur trioxide by
sorbent injection to lower plume opacity,
optimization of the FGD system at the
Bruce Mansfield Plant, the magnesium-
enhanced lime scrubber at the Zimmer
Generating Station, development of a clear
liquor scrubbing process, development of
a test facility for studying wet scrubber
fluid mechanics, and an update on
FGDPRISM. The last paper in this ses-
sion discussed the European view of FGD
applications and new advances and top-
ics in flue gas cleaning systems.
Poster Papers
Session 7 included 19 papers that were
also presented as posters at a special
session. These papers covered a variety
of subjects, encompassing the major top-
ics of the symposium. The poster papers
included a mixture of field demonstration
and pilot- and bench-scale reports on both
wet and dry FGD processes, multipollutant
control processes, foreign and domestic
authors, and modeling efforts.
Emerging Technologies
Seven papers were presented in Ses-
sion 8A on developments in new FGD
processes. They included a report on a
moving limestone bed process, pilot plant
results of several new technologies,
ADVACATE studies at a TVA plant, dem-
onstration of a sodium-based scrubber and
membrane separation for sulfur recovery,
and optimization of the Advanced Coolside
technology, which uses sorbent injection
and flue gas humidification.
Waste Utilization and Disposal
The last session of the symposium, Ses-
sion 8B, included seven papers on topics
including economics of FGD waste dis-
posal, use of FGD waste as a saleable
gypsum product, application of FGD
wastes to agricultural production, waste
stabilization, and use of FGD as a compo-
nent of a landfill liner.
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Brian K. Gullett (also the EPA Project Officer see below) is with the U.S.
Environmental Protection Agency, Research Triangle Park, NC 27711.
The complete report, entitled "Proceedings: 1993 SO2 Control Symposium," con-
sists of four volumes:
Volume I (Order No. PB95-179222, Cost: $52.00, subject to change) consists of
Sessions 1, 2, 3A, and 3B.
Volume 11 (Order No. PB95-179230, Cost: $52.00, subject to change) consists of
Sessions 4A, 4B, and 5A.
Volume III (Order No. PB95-179248, Cost: $44.50, subjectto change) consists of
Sessions 5B, 6A, and 6B.
Volume IV(OrderNo. PB95-179255, Cost: $61.00, subjectto change) consists
of Sessions 7, 8A, and 8B.
The complete set, consisting of all four volumes, can be ordered using Order No.
PB95-179214. The cost is $178.50 (subject to change).
All documents 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
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/SR-95/015
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