United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park 27711
Research and Development
EPA/600/S9-917015  July 1991
Project Summary
 Proceedings:   1990  SO2 Control
 Symposium
Charles B. Sedman
  This report compiles 110 presented
papers from the 1990 SO2 Control Sym-
posium held in New Orleans, LA, May
8-11,1990. Topics include: SO2 control
economics,  furnace sorbent injection,
byproduct utilization, spray dryer tech-
nology, wet flue gas desulfurization
(FGD) and combined SOx/NOx control
technologies, and post-combustion dry
sorbent injection. Many papers present
results from full-scale operational stud-
ies, while laboratory and pilot-scale re-
search on new technologies is also em-
phasized.
  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) and the Air and Energy Engineer-
ing  Research Laboratory, U.S. Environ-
mental  Protection Agency (AEERL/
USEPA)  is held periodically to transfer
technical information and advance tech-
nology development and application for
control of  SO2 emissions from fuel com-
bustion. The 1990 SO2 Control Sympo-
sium was  held in New Orleans, LA, May
8-11, 1990.  The proceedings  from  this
Symposium consist of four volumes, con-
taining 110 presented papers covering 14
technical sessions:
Session
          Subject Area
  1
  2
 3A

 3B
 4A
 4B
 4C
  5
 6A
 6B

 6C
 7A

 7B
International Overview
Economics
Furnace Sorbent Injection
 (FSI)
Byproduct Utilization
FSI Recycle
Wet FGD Reliability
Spray Dryers
Wet Full Scale Operation
Emerging Technologies
Combined SO|(/NOX
 Technologies
Wet FGD Vendor Designs
Post-Combustion Dry
 Technologies
Wet FGD Research
Poster Session  Misc. FGD Topics

International Developments
  Four papers on international SO2 con-
trol  at electric generating stations were
presented covering Japan, Canada, the
United Kingdom, and Europe. Flue gas
desulfurization (FGD) technology in Japan
dated  to 1973.  Currently wet FGD has
evolved with a fourth generation system
using  limestone, a single oxidation  and
absorption tower, and generating a gyp-
sum byproduct. A combined SO/NOx sys-
tem using activated coal char as the sor-
bent is scheduled for demonstration in
1990-91. Fluidized bed combustion is also
used in Japan but is not widespread.  The
author concludes that future systems of
choice will be the dry bed, combined SOx/
NO  removal system using char sorbent.
                                                  Printed on Recycled Paper

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                     United States
                     Environmental Protection
                     Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park 27711
                    Research and Development
EPA/600/S9-91/015  July 1991
v/EPA        Project Summary
                     Proceedings:   1990 SO2 Control
                     Symposium
                    Charles B. Sedman
                      This report compiles 110 presented
                    papers from the 1990 SO2 Control Sym-
                    posium held in New Orleans, LA, May
                    8-11,1990. Topics include: SO2 control
                    economics,  furnace sorbent injection,
                    byproduct utilization, spray dryer tech-
                    nology, wet flue gas desulfurization
                    (FGD) and combined SOx/NOx control
                    technologies, and post-combustion dry
                    sorbent injection. Many papers present
                    results from full-scale operational stud-
                    ies, while laboratory and pilot-scale re-
                    search on new technologies Is also em-
                    phasized.
                      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 SOa 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) and the  Air and Energy Engineer-
                    ing  Research Laboratory, U.S. Environ-
                    mental Protection  Agency  (AEERL/
                    USEPA)  is held periodically to transfer
                    technical information and advance tech-
                    nology development and application for
                    control of  SO2 emissions from fuel com-
                    bustion. The 1990 SO2 Control Sympo-
                    sium was  held in New Orleans, LA, May
                    8-11, 1990.  The proceedings from  this
                    Symposium consist of four volumes, con-
                    taining 110 presented papers covering 14
                    technical sessions:
Session
          Subject Area
  1
  2
 3A

 3B
 4A
 4B
 4C
  5
 6A
 6B

 6C
 7A

 7B
International Overview
Economics
Furnace Sorbent Injection
 (FSI)
Byproduct Utilization
FSI Recycle
Wet FGD Reliability
Spray Dryers
Wet Full Scale Operation
Emerging Technologies
Combined SO/NOx
 Technologies
Wet FGD Vendor Designs
Post-Combustion Dry
 Technologies
Wet FGD Research
Poster Session  Misc. FGD Topics

International Developments
  Four papers on international SO2 con-
trol  at electric generating  stations were
presented covering Japan,  Canada, the
United Kingdom, and Europe. Flue gas
desulfurization (FGD) technology in Japan
dated to  1973. Currently  wet FGD has
evolved with a fourth generation system
using limestone, a single  oxidation  and
absorption tower, and generating a gyp-
sum byproduct. A combined SOx/NOx sys-
tem using activated coal char a*s the sor-
bent is scheduled  for demonstration in
1990-91.  Fluidized bed combustion is also
used in Japan but is not widespread.  The
author concludes that future systems of
choice will be the dry bed, combined SO/
NO removal system using char sorbent."
                                                                     Printed on Recycled Paper

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   Canada  currently  has no  commercial
 add-on SO2 control technologies in place,
 but has  considerable developmental ac-
 tivities ongoing.  Individual  utility compa-
 nies have initiated research programs to
 comply with provincial SO reduction goals
 by the mid 1990s. The individual research
 programs for  Nova  Scotia Power,  New
 Brunswick  Electric  Power  Commission,
 Ontario Hydro (Saskatchewan) Power Cor-
 poration, and Alberta Power Limited were
 discussed.   A full array of  technologies,
 many of which are  detailed later in this
 Symposium, were cited as candidates for
 research and/or evaluation.
   The United  Kingdom has 70,000 MWe
 of electrical generating capacity, the ma-
 jority  being coal-fired.   Recent  legisla-
 tion targets  40% SO  reduction by 1998
 and  60% reduction  by 2003,  which  will
 result in considerable retrofit of  existing
 facilities.
   The West  German retrofit program
 (GFAVO) was enacted in 1983 and has
 resulted  in 150 units, over 30,000 MWe
 capacity, retrofitted  with FGD, along with*
 7400 MW of new capacity. Wet limestone,
 forced-oxidation scrubbers have accounted
 for 90% of FGD installations.

 FGD Economics
  The Economics Session emphasized the
 anticipated  costs of  FGD retrofit for acid
 rain  legislation.   One  paper  compares
 spray dryer and wet FGD system costs for
 hypothetical new  and retrofit  500  MW
 installations.  Another paper summarized*
 a comprehensive EPRI cost  study, includ-
 ing that (a) FGD costs were currently lower
 (when corrected for inflation) than for pre-
 vious studies,  (b) a number of technolo-
 gies were very close in  costs per ton  of
 SO2 removed, and (c) 30% reduction  in
 wet FGD costs were obtainable  by pro-
 cess simplification; e.g.,  no spare  mod-
 ules, single absorbers.
  A third paper detailed design changes
to reduce FGD retrofit costs,  while a fourth
 paper discussed the role of  economics in
 compliance planning strategies. The next
two papers discussed retrofit cost consid-
 erations specific to the Tennessee Valley
Authority system  and to 200  candidate
 retrofit boilers nationwide,  respectively.
The latter paper also  compared proposed
 U.S. retrofit economics to actual costs ex-
perienced in recent  West German retro-
fits.
  A seventh paper focused on second-
generation wet FGD technologies as ret-
rofit choices while the eighth  and final
paper discussed strategies to comply with
imminent acid rain legislative requirements.
 Furnace Sorbent Injection
   Emphasis was on design and operation
 of full-scale facilities.  The first paper de-
 scribed furnace lime injection  on a  65
 MWt stoker-fired boiler in West Germany
 followed by a second reaction stage with
 humid if ication upstream of an electrostatic
 precipitator (ESP)  for 90% SO2 removal.
 Three papers in this session which  de-
 scribed experimental studies for limestone
 and lime sorbents injected  into furnaces,
 while another paper detailed  large pilot
 furnace injection on a 15 MWt tangential
 prototype boiler. Three papers described
 activities at  three  demonstration sites.
 Results were presented for lime  injection
 at the 105  MW  Edgewater  and  61 MWe
 Whitewater Valley sites,  reporting up to
 50 and 72%  SO2  removal,  respectively.
 Plans for the  180  MWe demonstration at
 the Yorktown  No. 2 tangentially fired boiler,
 to start up in  1992, were discussed in the
 final paper  of this session.

 Byproduct Utilization
   In Session 3B,  Byproduct  Utilization,
 eight papers  were presented for waste
 handling, disposal and re-use in wet FGD,
 spray dryer FGD,  furnace sorbent injec-
 tion, and new technologies. Three papers
 dealt specifically with limestone/lime wet
 FGD sludge  utilization as  paving  materi-
 als,  aggregates, structural concrete, gyp-
 sum, and fertilizer. Other papers discussed
 potential byproducts from advanced new
 technologies such as gypsum and ammo-
 nium sulfite.  Two papers dealt with spe-
 cific experience in  byproduct/waste man-
 agement efforts: one for the  Ohio Edison
 system  and one covering  recent  experi-
 ence in West Germany.

 FSI Recycle
  The Furnace  Sorbent Injection (FSI)
 Recycle Session (4A) consisted of four
 presentations on the increased utilization
 of calcium  sorbents for  in-furnace injec-
 tion. One paper discussed dust collector
 recycle of dry sorbent with additives; an-
 other discussed similar recycle but by re-
 slurrying and  re-injection as  a slurry into
the furnace.  Two other papers discussed
 more novel reactivation schemes prior  to
 recycle—one  process (ARA) steam-treats
collected solids prior to  recycle into the
flue gas, while another (ADVACATE) con-
verts waste solids into calcium silicate prior
to reinjection into ductwork.

Wet FGD Reliability
  Session 4B, Wet FGD Reliability, con-
sisted of eight papers covering:
   • designing systems for load swing (cy-
     cling) service
    •  protective  linings for scrubber com-
      ponents
    •  corrosion prevention/control
    •  effects of  additives on  materials of
      construction
    •  duct conversion downstream of FGD
    •  alternatives to gas reheat for duct
      corrosion prevention

 Spray Dryers
   Session 4C focused on large pilot- and
 full-scale commercial applications of spray
 dryer technology.   Two  papers covered
 pilot experience at TVA's Shawnee facility
 and EPRI's High Sulfur Test Center. One
 paper described operating experience on
 an 865 MWe unit using eight absorbers; a
 second described vendor experience with
 spray dryers  worldwide.   The  effect of
 spray dryer operation on ESP performance
 was discussed in the remaining papers.

 Wet Full-Scale Operation
   Session  5 covered the mainstream topic
 of FGD symposia, that of full-scale oper-
 ating  experiences of wet lime/limestone
 scrubbers.   The session began with an
 overview  of chemical additives for im-
 proved operation by the Session  Chair-
 man.  Nine papers followed on :
    • thiosulfate  additives on  three com-
     mercial FGD  units
    • sodium formate addition on pilot- and
     full-scale scrubbers
    • performance  evaluation of magne-
     sium/lime,  limestone,  gypsum
     byproduct,  and limestone low sulfur
     coal FGD operations
    • evaluation  of a Chiyoda wet  scrub-
     ber system
    • scale  prevention  on a  commercial
     FGD  system
    • laboratory  evaluation of  additive
     losses in FGD
    • process  modifications to  improve
     FGD performance

 Emerging Technologies,
 Combined SO^NO,
 Technologies, and Wet  FGD
 Vendor Designs
  Sessions  6A,  6B, and  6C were  "mini-
 sessions" consisting of abbreviated pre-
 sentations  of new  developments in SO
control, specialized topics thought to be of
 less general interest than  conventional
 FGD technology. The purpose of  these
sessions  was  to expose new concepts,
while  minimizing the time, thus allowing

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many topics to be discussed.  Sessions
and topics covered were:
  Emerging Technologies:
   •  Parsons FGD process
   •  FGD process  using  cement kiln
     waste
   •  ISPRA Mark 13A process
   •  plasma-jet SO2 conversion
   •  CANSOLV FGD process
   •  anion-exchange resin dechlorini-
     zation
   •  synergistic reactor for SO2 control

  Combined SOx/NOx Technologies:
   •  overview report on  SOx/NOx control
   •  lime-urea  hydrate injection
   •  NOXSO process
   •  combined SOx/NOx control by cata-
     lytic system
   •  combined SOx/NOx control in a wet
     limestone scrubber
   •  combined SOx/NOx by fixed-bed dry
     sorbent
   • dry sorbent injection SOx/NO  con-
     trol
  Wet FGD Vendor Designs:
   • Flakt wet FGD systems
   • West German FGD systems
   • Babcock-Hitachi "Intelligent" scrub-
     ber
   • KRC-Noell wet FGD system
   • Pure air FGD process
   • Chiyoda wet FGD system

Post-Combustion Dry
Technologies
  Session 7A, Post-Combustion Dry Tech-
nologies, focused on efforts  to develop
lower cost retrofit technologies using dry
sorbents injected into the post-combus-
tion flue gas.  These papers included two
discussions of dry sodium injection, four
papers discussing calcium injection, one
paper documenting a combined calcium/
sodium dry injection system, and one pa-
per describing a spray dryer within an
ESP (E-SOJ.
Wet FGD Research
  Session 7B, Wet FGD Research, cov-
ers the laboratory- and small-pilot-scale
research on wet  FGD  being  conducted
primarily at EPRI and its member compa-
nies. Topics included mist eliminator per-
formance, limestone utilization, process ad-
ditives,  crystallization studies, combined
SOx/NOx control in wet scrubbers, and pro-
cess/economic models  developed for in-
dustry.

Poster Session
  Although not presented formally at the
podium, the 1990 SO2  Symposium  con-
ducted  a large poster session where FGD-
related subjects were discussed face to
face between the author and audience.
Of these,  13 submitted technical papers
which  are included  in  the proceedings.
These  topics are heavily oriented toward
research programs and  vary from fly ash
effects  on SO2 control,  process models,
improved FGD components, additives, and
corrosion control.  Also papers for non-
utility applications, especially waste incin-
erator FGD, were presented in this  ses-
sion.
                                                                    •&LI.S. GOVERNMENT PRINTING OFFICE: 1991 - 548-02H/40030

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