United States
                    Environmental Protection
                    Agency
 Industrial Environmental Research
 Laboratory
 Research Triangle Park NC 27711
                    Research and Development
 EPA-600/S7-84-001  Mar. 1984
&ERA         Project  Summary
                    Control  of Criteria  and  Non-
                    Criteria  Pollutants  from
                    Coal/Liquid  Mixture Combustion
                    J.H.E. Stalling and S.J. Call
                     As the availability and cost of oil has
                    become uncertain in recent years, the
                    need for the United States to reduce its
                    dependence on oil has prompted signifi-
                    cant efforts by government and industry
                    in finding  alternate fuel sources. This
                    posture has been strengthened by the
                    Powerplant and Industrial Fuel Use Act
                    of 1978 that prohibits the use of gas
                    and oil in  new boilers without special
                    exemption. The Department of Energy
                    (DOE) has taken  an active role in
                    developing two such alternate fuel
                    technologies:  coal/oil mixture (COM)
                    and coal/liquid mixture (CLM) combus-
                    tion.
                     Recognizing that environmental con-
                    siderations must be addressed in any
                    evaluation of fuel conversion to COM or
                    CLM, DOE and the  EPA's  Industrial
                    Environmental Research Laboratory-
                    RTP (IERL-RTP) contracted with Radian
                    Corporation to identify and assess the
                    effectiveness of currently available
                    methods of controlling the  release of
                    criteria and non-criteria (trace elements)
                    pollutants from the combustion of
                    COMs and CLMs. This report  gives
                    results of this assessment and compares
                    the costs and  effectiveness of various
                    control technologies found to be appli-
                    cable  to emissions from boilers firing
                    CLM.  A previous report (EPA-600/7-
                    83-040) gave results of  a similar
                    assessment of boilers firing COM.
                     To date, the combustion of coal/wa-
                    ter mixtures (CWMs) has received the
                    most attention, and is thus the focus of
                    this report. Coal/alcohol  mixtures
                    (CAMs) represent another fuel alternative
                    which could potentially replace  oil or
                    natural gas in existing boilers, although
                    there is currently limited activity in the
 development of CAMs as fuels. This
 report briefly summarizes activities and
 advances made in the development of
 CAMs as fuels.
  Emissions from CLM  combustion
 were characterized using data from
 various tests. In the absence of data for
 CLM-firing, the discussion focuses on
 data from coal- and COM-firing, with
 corollaries to CLM combustion. The
 pollutants examined most closely were
 paniculate matter, sulfur dioxide (SO2),
 and nitrogen oxides (NO,). Trace element
 emissions and emissions of polynuclear
 organic material  (POM) were also
 examined. Conventional emission con-
 trol techniques were determined to be
 the most effective in reducing emissions
 from CWM  combustion. Cleaned coal
 must be  used  in the  preparation of
 CWMs, and it has been determined that
 coal cleaning can also significantly
 reduce particulate matter and SOz
 emissions from CWM combustion.
  Emission rates and associated costs
 for emissions control of particulate
 matter and SO2 were assessed for four
 CWM compositions and various boiler
 sizes. Physical coal cleaning was
 considered for pre-combustion control
 of particulate matter and SO2.
  This Project Summary was developed
 by EPA's Industrial Environmental
 Research Laboratory, Research Triangle
 Park, NC, to announce key findings of
 the research project that is fully docu-
 mented in a separate report of the same
 title (see Project Report ordering
 information at back).

 Introduction
  Coal/water mixtures (CWMs) have
been combusted successfully in Depart-

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 ment of Energy (DOE) research in small,
 test combustion  units, and full-scale
 testing is planned for the near future.
 Coal/alcohol mixtures (CAMs)arenotyet
 well-developed as a slurry fuel; further-
 more, they are still more expensive than
 CWMs or coal/oil mixtures (COMs).
  As CLM combustion technology becomes
more widespread, DOE and the Environ-
mental Protection Agency (EPA) recognize
that certain environmental considerations
will  have  to be addressed in order to
expand the use of CLM in an environmen-
tally acceptable way. Specifically, it  will
be necessary to determine the potential
emissions from sources burning CLMs
and evaluate,  assess, and compare the
effectiveness of control technologies in
limiting criteria and non-criteria pollutant
emissions. Radian Corporation has been
under  contract  to  EPA and  DOE to
conduct a study aimed at identifying and
assessing  the effectiveness of currently
available  methods  of  controlling  the
release of criteria and non-criteria (trace
elements) pollutants from the combustion
of CLMs.
  The  report generated from  this study
contains several chapters that focus on
the various considerations and assessments
necessary in making a conversion from
oil  or  gas to CLM. This report focuses
primarily on CWM combustion in existing
oil- or  gas-fired boilers. The report  also
briefly discusses CAMs and their potential
advantages  and disadvantages. Chapter
2  presents  some of the  technical  and
economic factors that determine  the
suitability of CWM as a fuel and identifies
boilers that might be candidates for CWM
conversion.
  Chapter 3 discusses the emissions that
 have been measured to date on combustion
units burning CWMs. The criteria pollutant
emissions that are discussed are panicu-
late matter, sulfur dioxide (SO2>,  and
oxides  of  nitrogen N0«). Non-criteria
pollutant  emissions discussed are the
selected trace elements, arsenic (As),
 beryllium (Be), cadmium (Cd), chromium
(Cr), nickel (Ni), selenium (Se), vanadium
(V), and mercury (Hg), as well as polynuclear
 organic matter (POM) emissions. Chapter
 3 also briefly discusses control technologies
 that are applicable to boilers that could be
 converted to burn  CWMs. Several of
 these  control techniques, as discussed
 later in this Summary, were the subject of
 further technical and  economic study
 presented in the remainder of the report.
   Chapter 4 presents the environmental
 impacts of the selected control technologies,
 including the primary pollutant control
 capability and any secondary environmental
impacts. The potential for multipollutant
control is also discussed. Chapter 5 address-
es the cost  impacts of the technologies
discussed in Chapter 4 in terms of capital
costs, annual operation and maintenance
(O&M) costs, annualized costs, and cost
effectiveness. Multipollutant  controls,
add-on controls, and  low-sulfur CWMs
are also compared in this chapter.

Use of CWMs in Existing
Boilers
  CWMs, also referred to as coal/water
slurries, consist of 65-75 weight percent
coal in water with minor percentages of
additives. Bituminous coals are most
frequently  used in the  preparation of
CWMs, but some lignite and subbitumi-
nous  coals may also be  used. Because
coals vary  widely  in  ash and sulfur
content, only cleaned coals or low-sulfur,
low-ash coals are used in the preparation
of CWMs to ensure a more consistent fuel
quality. Due to the  economics of CWM
preparation facilities, it is most likely that
these  mixtures  will be prepared in
centralized off-site facilities rather than
at the boiler site.
  The suitability of converting  a boiler
currently firing oil or gas to CWM de-
pends on several technical and economic
factors.  The  likelihood of a specific
boiler's being a candidate for CWM will
depend on the age of the boiler (remaining
useful  life), boiler design, size and
capacity factor, geographical location
(proximity to  CWM fuel  supply),  site-
specific boiler modifications required,
existing emission control equipment,  if
any, and emission controls required by
applicable environmental  regulations.

Technical Considerations
  Three basic factors must be evaluated
in determining the technical suitability of
converting existing  oil- or gas-fired
boilers to CWM:  CWM fuel properties,
CWM combustion characteristics, and
boiler modifications required to accommo-
date CWM-firing.
  Other than combustion characteristics,
the most important CWM fuel properties
to be considered are viscosity, stability
and abrasiveness. Viscosities of CWMs
range from about 450 to 2,000 cP, or from
a paint-like consistency to that of a thick
gel. The desired high  solids loading and
decreased viscosity can be brought about
by utilizing bimodal particle size distribu-
tions and/or by the use of additives in the
preparation of CWMs. Generally, conven-
tional pumping methods are adequate to
handle CWMs, although  there may be
potential  erosion  problems. Chemical
stabilizing additives, typically emulsifying    _
agents,  gelling agents, or  surfactants,   M
have  been developed to improve COM   ^
stability by  keeping the coal particles
suspended  in  the oil. The increased
abrasiveness of CWM relative to oil can
poteritially cause erosion in pipe bends,
pumps, valves, and  burners.  These
potential problems can be minimized by
selecting proper materials, reducing fuel
velocities, and using more finely ground
coal.
  The boiler modifications  required in
converting from oil or  gas  to CWM are
site-specific, and depend on such boiler
design factors as  tube  spacing,  burner
design,  furnace size,  and  bottom  ash
removal capability. Boilers originally
designed for oil- or gas-firing commonly
have narrower tube spacmgs than boilers
originally designed for coal-firing, making
coal-fired  boilers more ideally suited, in
that respect,  for  conversion to  CWM
combustion. In converting to CWM, the
potential exists for ash deposition  and
slagging (if the furnace temperature is
not maintained below  the ash fusion
temperature). Bridging of  molten  ash
between the tubes  leads to impaired heat
transfer and,  possibly,  boiler derating.
Soot blowers would generally be required
to prevent these  problems; although   ^
some existing oil-fired  boilers have  soot   fl
blowers, additional soot blowing capacity   ~
may be needed to accommodate CWM
combustion. Since most CWM combustion
studies have found air or steam atomiza-
tion preferrableto mechanical atomization
burners may have to be modified or, in
some cases, replaced.  To facilitate
switching from CWM- to oil-firing with
maximum flexibility, careful consideration
of burner design or  modification is
necessary. Combustion of CWM requires
a larger combustion  space  relative to oil
to allow for  the longer residence time
needed for complete combustion  of the
coal particles. Refitting for CWM combus-
tion will require provisions for a  bottom
ash handling facility in most cases, since
units designed for oil-  and gas-firing do
not  often have bottom  ash removal
capability.
  In addition to modifications  made
directly to the boiler, other changes to the
facility may be required in converting to
CWM. These  changes are primarily
associated with the fuel handling system
(including pumps, piping, valves, and flow
measurement devices). Storage tanks for
CWM received from a centralized off-site
preparation plant may have to be modified
to include agitators and  temperature

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controls. New storage equipment will be
required if dual fuel capability (CWM and
oil) is desired.

Economic Considerations
  Several economic factors will also
impact the desirability of converting to
CWM firing.  Paramount  among  these
considerations of the  use of CWM in
general  is the cost of coal relative to that
of oil. Currently, widespread use of CWM
is limited by the low price of oil.
  The economic considerations of convert-
ing a particular boiler to CWM firing may
be somewhat complex, particularly for
utility applications. However, the  econom-
ic impacts  of the following factors are
important in every case: capital availabili-
ty; boiler modifications required; difference
between oil (or gas)  and coal prices and
the  predicted rates of escalation of the
fuel costs; security of oil or gas supply;
availability, composition,  and  price of
CWM; boiler  size and  capacity factor;
remaining useful  life of the boiler; and
emission controls required.
  The economics of conversion  are also
affected by the composition of the CWM
(percent coal, sulfur content,  and  ash
content), the  CWM  fuel  cost,  and the
source of the CWM (on-site or off-site
centralized preparation plant). CWM fuel
cost is determined primarily by the cost of
coal,  although coal  cleaning costs and
CWM preparation costs also impact fuel
cost.

CWM  Emissions
  Most  often, when an existing oil-fired
boiler  is to  be  converted to  CWM
combustion, the uncontrolled emissions
of particulate matter (PM) and  nitrogen
oxides (NOx) will  be greater for CWM-
firing than for oil-firng.  The increased
emissions result from the contribution of
coal ash and nitrogen to the combustion
emissions. Emissions of SOz from CWM
combustion may  be less than or greater
than oil-only SOa emissions, depending
on the  relative sulfur contents of the
CWM and the  oil. Trace  elements
emissions (except Ni and  V) from CWM
combustion may  also be greater than
those for oil-only firing.

PM  Emissions
  Measured emissions of PM fly  ash
from boilers firing CWM are a function of
the  percentage of coal in the CWM, the
ash content of the coal used, and, to some
degree,  the amount of ash deposition in
the  boiler. Although test data on small
test boilers suggest that most of the CWM
ash (75 to 95 percent) is  emitted as fly
ash, some combustion tests on coal
slurries have shown significantly lower
fly ash emissions. Ash deposition in the
boiler may cause the reduced  measured
PM emissions.

SO2 Emissions
  Emissions of SOzfrom CWM combustion
are a direct function of the fuel sulfur
content. The  CWM  sulfur content is in
turn determined by the sulfur content of
the coal used to make the CWM and the
percentage of coal present in the CWM.
At least 95 percent of the fuel sulfur is
typically emitted as S02. But CWMs made
with coal that has highlyalkalineash may
emit slightly less than 95 percent of the
fuel sulfur since the alkaline ash retains
some of the fuel sulfur.

/VOx Emissions
  Emissions of NOX from boilers firing
CWM are more difficult to quantify for all
potential applications than are SOz and
PM  emissions.   For any  boiler NOx
emissions can vary  not only with CWM
fuel composition,  but  also  with the
amount of combustion air  (excess air)
and, in some cases, with  boiler load.
Properties of the CWM fuel that influence
NOx emissions are the nitrogen content of
the coal used to make the CWM and the
percent coal in the CWM. For a given fuel
composition,  NOx emissions can vary
significantly from  boiler to boiler due to
differences in burner and furnace design
and the use of combustion  air preheat.
Although limited test data are available
for NOx emissions from CWM-f iring, they
indicate that emissions from CWM
combustion  should follow the same
trends  as those noted for the parent coal.

Trace Element Emissions
  Trace elements  in the CWM fuel exit
the  boiler  either with the bottom ash or
with the flue gas, if ash deposition in the
boiler is not significant. Most of the trace
elements emitted  with the flue gas are
associated with the fly ash, though some
may remain in the vapor phase.
  The amount of trace elements emitted
from a particular boiler depends on:
combustion  temperature, fuel feed
mechanism, characteristics  of the flue
gas, and CWM properties (trace element
concentration).
  The combustion temperature determines
the extent to which  specific trace
elements  are  volatilized and thus the
extent to which they may be emitted with
the  fly ash or flue  gas. The  fuel feed
mechanism influences the partitioning of
non-combustible trace elements between
the bottom  ash and  the  fly ash.  The
temperature of the flue gas  affects the
relative amounts of volatile trace elements
which  are emitted condensed on the fly
ash particles compared to being emitted
as a vapor.
  Data on three coals show that coal has
higher concentrations of As,  Be, Cr, Hg,
and Se than does  oil.  Residual oil has
higher concentrations of Cd, Ni, and V.
Thus, combustion of CWMs would likely
result in higher emissions  of As, Be, Cr,
Hg, and Se, but lower emissions of Cd, Ni,
and V, than would the combustion of oil
alone.

Polynuclear Organic Material
(POM)
  The amount of POM emitted from any
combustion source is dependent on the
formation and the transformation mecha-
nisms of the POM. POM is formed in the
combustion zone either by the breakdown
of larger molecules or by the building up of
smaller ones.  Evidence is available to
indicate that POM forms  in the vapor
phase and later condenses on flue gas
particulate matter.  POM  formation is
related to combustion efficiency, and
POM transformations are related to boiler
and downstream flue gas temperatures.
POM emissions from CWM combustion
were not quantified in the recent studies.
However,  when properly fired,  oil-only
combustion has been shown to contribute
almost no POM emissions to the environ-
ment while coal-only combustion produces
POM emissions in unpredictable patterns.

Applicable Control
Technologies

Pre-combustion Techniques for
PM/SOz: Physical Coal
Cleaning
  Physical coal cleaning is a pre-combus-
tion control technique employed by
coal/CWM producers to reduce the ash
and  sulfur  content  of coals  used to
prepare CWMs, and consequently reduce
the PM and SO2 emissions resulting from
CWM  combustion.  It is expected that
physical coal cleaning will be applied to
all coals used  in CWMs.
  Physical coal cleaning can  be defined
generally as the separation of waste or
unwanted "refuse" materials from coal
by techniques based on differences in the
physical properties of coal and refuse.
Each coal cleaning facility is unique in its
treatment of coal. Each cleaning process
depends on the characteristics of the coal
to be treated and the desired specifications
for the cleaned coal. The sulfur removal

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efficiencies of  physical coal cleaning
processess range from about 13 percent
for simple crushing  and  screening
separation processes to about 70 percent
for the most intensive cleaning processes.
The sulfur removed by these processes is
pyritic sulfur. The organic sulfur can only
be removed by chemical modification of
the coal structure.  Thus, the amount of
sulfur removal possible by  physical coal
cleaning  is  limited by the presence of
organic sulfur.  Similarly,  ash removal
capabilities range from about 10 to 75
percent.
  It is unlikely that physical  coal cleaning
alone will reduce ash content to levels
such that no post-combustion PM controls
are required to meet air pollution regulations.
In many  cases, however, physical coal
cleaning can reduce the sulfur content of
the coal to a level such that no additional
controls for SO2 emissions  are required.
Even if physical  coal cleaning alone
cannot achieve adequate PM and SC>2
control, it can substantially reduce the
amount of costly post-combustion control
required. It also reduces the variability of
the CWM composition, permitting tighter
boiler and control design specifications.
  One disadvantage  of physical coal
cleaning is that, although it reduces the
quantity of fly ash/bottom ash and wet
sludge generated at the boiler site, it has
a net effect of increasing the amount of
solid waste generated. In  any cleaning
process,  some valuable  combustible
matter is  lost  as refuse, along with
undesired  inorganic  materials. The
amount of valuable coal lost as  refuse
ranges from about  5 to  50 percent,
depending on the cleaning process and
coal composition. Liquid waste impacts
are  also associated with  physical coal
cleaning  processes; some  facilities are
minimizing liquid waste disposal require-
ments by recycling process  water.
Physical  coal  cleaning facilities are
subject to EPA standards for air (fugitive
emissions) and water quality, and MSHA/
OSHA regulations for refuse disposal.


Combustion Modifications for
NOX Reduction
  Combustion modification techniques
for N0« control include: low excess air
(LEA) operation, staged combustion, flue
gas  recirculation (FGR),  and low-NO*
burners. Limited data are available on the
effectiveness of these combustion modifi-
cation techniques in reducing NOX
emissions from CWM combustion. How-
ever, NOx emissions from CWM combus-
tion are expected to be similar to those
from combustion of moist coal.
  Low-NOx burners are the most effec-
tive of the candidate NOX control techno-
logies examined  in this study.  Low-NOx
burner designs typically incorporate LEA,
staged combustion, and/or internal FGR.
Low-NO, burners available for pulverized
coal  service can potentially reduce
uncontrolled NO* emissions by 65 to 90
percent. Staged combustion is a relatively
effective NOx control technology.  The
effectiveness of  staged  combustion in
reducing NOx emissions results from the
formation of localized fuel-rich conditions
in the primary combustion zone  which
minimize formation of both thermal and
fuel  NOX.  Staged combustion has been
shown  to  achieve 40 to  50 percent
reductions  in  NOx emissions  when
applied  to coal units.  Operation at low
excess  air  (LEA) levels is  primarily
effective in reducing thermal NOX. LEA is
generally incorporated as a design and
operating feature in new boilers since it
increases  boiler efficiency and thus
reduces fuel consumption. FGR is most
effective in reducing thermal NOx and is
therefore not a very effective NOx control
technique for coal firing due to the  high
fuel  nitrogen content of coal relative to
other fuels. FGR  will likely be ineffective
for CWM firing as well.

Post-Combustion  Control
Techniques for PM
  The emission reduction capabilities of
two  PM control  technologies  were
examined in this study: electrostatic
precipitators (ESPs), and fabric filters.
  High paniculate  matter control efficiencies
(98 percent or greater) have been widely
demonstrated with ESPs and fabric
filters. In general, these technologies can
reduce fly ash emissions to 43 ng/J (0.1
lb/108 Btu), and in most  cases to 21.5
ng/J (0.05 lb/106 Btu) or  less.  Fabric
filters, generally more  effective than
ESPs, are not as  sensitive to changes in
fly ash resistivity,  particle size distribution,
or inlet grain loading.

Post-Combustion Control
Techniques for PM/SOz
  Two post-combustion control techniques
for combined PM/S02 removal evaluated
in this study are: wet flue gas desulfuriza-
tion  (FGD), and spray drying FGD. These
control technologies are  used  primarily
for S02 control, but also achieve moderate
to substantial reductions in PM emissions.
  Wet FGD systems can achieve 90 per-
cent removal of SOz or greater if they are
designed and maintained properly.  Two
types of dry FGD systems appear to be
promising for CWM applications: spray
drying FGD and dry injection of sodium-
based compounds. Although these systems   ^
are not as widely demonstrated as wet   •
FGD systems, SOa removal efficiencies of
up to 90 percent have been reported for
coal-fired boilers.
  Wet FGD systems are quite suitable for
combined SOa and PM removal. Combined
SOa/PM control with this system favors
venturi scrubbers, possibly preceded by a
mechanical collector. Substantial combined
SO2/PM control  is also achievable with
dry scrubbing systems; e.g., spray drying
(since they include a  fabric filter or an
ESP) and dry injection of sodium-based
alkali compounds into  a fabric filter.
The disposal of highly soluble sodium-based
wastes from  dry  injection may present
more serious solid waste disposal prob-
lems than the disposal of calcium-based
wastes from spray drying or wet FGD sys-
tems.
Post- Combust/on
Techniques for NO* Control
  Post-combustion control techniques
for NOx include ammonia injection (e.g.,
Exxon's "thermal De-N0x") and flue gas
treatment (FGT) techniques. These
control techniques have not been applied
widely to sources in  the U.S. since
existing emission limits can be met by fuel   ^
switching or by combustion modification.   •
NOx FGT is, however, well developed in
Japan  where  NOX emission limits are
more stringent.
  NOX FGT processes can be classified as
either dry or wet. The major wet FGT
processes include absorption-reduction,
absorption-oxidation,  and oxidation-
absorption; the major dry FGT processes
are selective catalytic  reduction (SCR) and
selective  non-catalytic reduction with
ammonia (or thermal De-NOx, as developed
by Exxon). NOx emission reductions of up
to 90 percent may be achievable with
these FGT processes.


Trace Element Control
Technologies
  The  technologies that  achieve the
greatest degree of fine paniculate control
are the most efficient for trace element
collection, since many of the  trace
elements  tend to be enriched on the
smaller fly ash  particles.  Thus, fabric
filters  and ESPs achieve the greatest
degree of trace element control. In
addition,  physical  coal  cleaning can
reduce emissions by reducing  trace
element concentrations in the fuel prior
to combustion.

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Cost Impact of Control
Technologies
  The cost impacts of various PM, SO2,
and NOx control technologies for boilers
firing CWM were evaluated in terms of (1)
capital costs, (2)  annual operating and
maintenance (O&M) costs, (3)annualized
costs, and (4)  cost  effectiveness. The
impacts of various PM and SO2 control
technologies  were evaluated for three
CWM boiler sizes and four CWM fuels.
The boiler sizes examined were: 8.8 MW
(30  x 10s Btu/hr), 73 MW (250 x  106
Btu/hr), and  205  MW (700 x 106
Btu/hr).The CWM fuels for which control
technology costs  were calculated were
selected  from typical cleaned coal.
Uncontrolled SC>2 and PM emission rates
were calculated assuming that (1) all of
the fuel sulfur is emitted as SO2, and (2)
80 percent of the CWM ash is emitted as
fly ash. Each CWM fuel was assumed to
be a 70:30 mixture of coal and water. The
costs of PM and S02 control technologies
presented in the  report are based
primarily on the technology costs used in
the  EPA's development of Industrial
Boiler New Source Performance Standards
(NSPS).

Comparison of FGD System
Costs
  The costs of dual alkali, spray drying,
and  dry  injection FGD systems are
compared in Figure 1 as a function of
boiler size for units firing various CWM
fuels. The costs are based on a 70percent
SO2 removal efficiency and a 60 percent
annual capacity factor. The relative costs
of the three FGD systems for  specific
applications may be altered due to site-to
site  variations in SO2  removal, boiler
capacity,  reagent costs, or availability of
existing equipment to reduce retrofit costs.
  Dry injection  FGD has  the lowest
capital costs up to a boiler size of about
100 x 106 Btu/hr.  However, wet FGD has
the  lowest capital  cost of the three
systems for boilers larger than this size.
The  result  is  due  primarily  to  the
increased paniculate  matter collection
associated with the use  of a fabric filter
in the spray dryer  and dry injection
systems. The lower PM emission control
levels achievable with fabric filters,
relative to a wet  FGD system  used for
combined SOz/PM  removal, result in
higher waste  disposal  costs.  An ESP
would likely be required  upstream of the
wet  FGD to achieve  the  same  PM
emission level.
  In comparing the annualized costs for
three FGD systems,  wet FGD  had the
lowest annualized cost for boilers above
   4,000
5  3,ooo
«>
$
t>
I
"5
c
   2,000
   7,000
  60% Annual Capacity Factor
  70%SOzFtemoval

(NOTE: Costs shown here are
for specific CWMs and do not
represent all possible
control system costs.
Control costs may
differ from other CWMs.
combustion systems, and
control techniques.)
                                  Dry Injection .
                                          Dual Alkali
Figure 1.
            59              116            174             232
           (200)            (400)           (600)            (800)
                     Boiler Size. MW (10s Btu/hr)
  Annualized costs of three FGD systems applied to boilers firing a high ash, high
  sulfur CWM.
about 100 x 106 Btu/hr. Below 100 x 106
Btu/hr, dry injection is the least expensive
alternative, but its costs  increase rapidly
as a function of  boiler size and it is the
most costly alternative at the larger boiler
sizes.
   J. H. E. Stalling and S. J. Call are with Radian Corp., Durham, NC 27705.
   Robert E. Hall is the EPA Project Officer (see below).
   The complete report, entitled "Control of Criteria and Non-Criteria Pollutants from
     Coal/Liquid Mixture Combustion," (Order No. PB 84-137 231; Cost: $20.50.
     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

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Center for Environmental Research
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Cincinnati OH 45268
                                                                                                      
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