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

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