SEPA
INDUSTRIAL
ENVIRONMENTAL
RESEARCH
LABORATORY
FGD
QUARTERLY
REPORT
VOL. 3, NO. 4
WINTER 1979-80
RESEARCH TRIANGLE PARK, NC 27711
IN THIS ISSUE
This issue of the FGD Quarterly Report announces the Sixth
FGD Symposium, sponsored by EPA's Industrial Environmental
Research Laboratory at Research Triangle Park, North Carolina
(IERL-RTP). The symposium will be held in Houston, Texas, in
October of this year. This symposium, like those that have preceded
it, will serve as a forum for the exchange of FGD information.
This issue also describes the results from several recent EPA-
sponsored studies. Topics covered include cost evaluations of
various FGD processes, parameters affecting the formation of
calcium sulfite crystals in FGD wastes, limestone type and grind
studies, and an update on IERL-RTP's FGD utility survey.
Also featured in this issue is a special summary of present and
projected U. S. consumption patterns of elemental sulfur, an
important by-product of many FGD processes.
The FGD Quarterly Report is distributed without charge to
persons interested in FGD. Those wishing to initiate or cancel their
subscriptions to the FGD Quarterly Report may do so by contacting
the EPA Project Officer or Radian Project Director named on page
7 of this issue. Any change of address should also be reported.
SIXTH FGD SYMPOSIUM SCHEDULED FOR FALL 1980
The Shamrock Hilton in Houston, Texas, will be the site for the
Sixth FGD Symposium, scheduled for October 28-31. 1980. As
with previous symposia, the intent of these meetings will be to
provide a forum for the exchange of new information on commercial
and developing FGD technologies.
The Sixth FGD Symposium will be sponsored by EPA's
Industrial Environmental Research laboratory at Research Triangle
Park, North Carolina (IERL-RTP). The symposium format and
agenda are now being planned. Further information will be
published, as available, in subsequent issues of the FGD Quarterly
Report.
The most recent symposium in this series was held in Las
Vegas, Nevada, in March 1979. A detailed summary of this
symposium was presented in the FGD Quarterly Report, Vol. 3,
No. 2. The proceedings are now available (EPA-600/7-79-167a, b.
see "FGD Reports and Abstracts").
Comments on previous symposia or suggestions for the sixth
symposium may be directed to symposium Chairperson Michael A.
Maxwell, Chief of the Emissions and Effluent Technology Branch,
MD-61, USEPA/IERL-RTP. Research Triangle Park, NC 27711;
telephone (919) 541-2578 or (FTS) 629-2578.
SURVEY OF DRY FGD PROCESSES NOW AVAILABLE
The Survey of Dry SOŁ Confrol Systems summarizes the
status of dry FGD processes, as applied to the utility and industrial
sectors in the U. S. This report also discusses RD&D activities and
the commercial activities of the various vendors of dry systems.
IERL-RTP is distributing the survey report, which includes
information collected from 1969 through October 1979. Future
semiannual updates are forthcoming.
In recent years, dry FGD processes have received substantial
commercial interest. Dry scrubbing appears to be a promising
technology, especially for application to western power plants
burning low sulfur coal.
The dry FGD technologies considered by the Survey of Dry
SO2 Control Systems include:
• Systems using spray dryers for a contactor with subsequent
baghouse or electrostatic precipitator (ESP) collection of
waste products.
• Systems involving dry injection of alkaline material into the
flue gas with subsequent baghouse or ESP collection of
waste products.
Other varied dry systems using such approaches as adding
alkaline material to or with the fuel prior to combustion or
contacting the flue gas with a fixed bed of alkaline material.
According to the survey, five commercial spray dryers have
been sold for Industrial and utility coal-fired boilers. Of these, two
are being applied to industrial boilers firing eastern coal, while the
remaining three are being installed at utility boiler systems firing
western coal.
Sections of the report address current and past dry scrubbing
activities of various vendors and researchers. A summary also
shows the current status of each process surveyed. Those contacted
during the survey and sources for additional information are given.
Survey information also includes principles and terminology of
the dry scrubbing processes as well as process flow diagrams.
The Survey of Dry SC>2 Control Systems is available by
contacting the EPA Project Officer, Ted G. Brna; (919) 541-2683 or
(FTS) 629-2683. (For background information on dry FGD systems,
see the FGD Quarterly Report, Vol. 3, Nos. 1 and 2.)
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FGD QUARTERLY REPORT/WINTER 1979-80
FINE GRINDING OF LIMESTONE MAY REDUCE FGD COSTS
Studies at lERL-RTP's lime/limestone pilot plant are
examining the effects of varied grinds of limestone on SC>2 removal
efficiencies. To date, test runs using coarse and fine grinds of three
different types of limestone-Fredonia, Stone Man, and Georgia
Marble — have been completed. During these tests limestone
makeup slurry was fed to the scrubber at different rates in order to
vary the stoichiometric ratio, defined as: moles CaCC>3 fed/moles
SC>2 absorbed. Variables monitored, in addition to SOg removal,
were percent solids in the Alter cake, the settling rate, and the
settled density of the scrubber slurry.
Cost studies carried out in 1977 by the Tennessee Valley
Authority have shown that economics favor fine grinding. The
higher capital investment required by the grinding equipment is
more than offset by the lower costs for waste disposal and raw
limestone makeup. An important goal of the IERL-RTP studies was
to test, at the pilot plant scale, the magnitude of the effect of grind
on limestone stoichiometric ratio which was assumed in the TV A
economic study.
Some results of these tests are listed below:
• The RTF tests confirm that both type and grind of the
limestone feed can significantly affect SO2 removals
obtained in a high-performance scrubber (TCA) of the
single-loop type.
The observed effects of limestone grind support the premise
of TVA's economic study which showed clear benefits for
fine grinding.
• The relative performance of the three stones tested was:
Fredonia > Stone Man >Georgia Marble. This ranking was
valid for both fine and coarse grinds.
* For the three stones tested, sludge quality was also related
to the type of limestone used. The settling rate and
filterability of the scrubber slurry increased as SOj
reactivity of the limestone decreased.
• With 6.6 percent QZ and 3000 ppm SC>2 in the flue gas, the
propensity of the scrubber to operate in the unsaturated
mode was unaffected by limestone type or grind.
For additional information, contact the IERL-RTP Project
Officer Robert H. Borgwardt; (919) 541-2336, or (FTS) 629-2336.
See also Vol. 3, No. 3 of the FGD Quarterly Report.
STUDY IDENTIFIES FACTORS IN CALCIUM SULFITE FORMATION
Sludge disposal represents a significant operating cost in most
applications of lime/limestone or dual alkali scrubbing. In systems
where calcium sulfite (CaSC>3) is the major product the waste
sludge generally settles more slowly, has a low settled density, and
is difficult to dewater. Two types of CaS(>3 crystal forms occur in
large-scale FGD systems: one is a flat platelet; the other is granular
and spherical. Platelets are preferred because they are more dense
and settle more rapidly.
A recent study was conducted by Radian Corporation to
characterize the key parameters affecting the formation of CaSC>3
crystals in FGD systems. The final report. Calcium Sulflte Crystal
Sizing Studies (EPA-600/7-79-192, see "FGD Reports and
Abstracts"), describes and compares various methods used to
determine the crystal size distribution in these waste materials.
CaSC*3 nucleation mechanisms were also studied to characterize
parameters affecting the formation of CaSO3 sludge. The need for
such investigation was identified in an earlier Radian study aimed at
Improving sludge quality. Development of a Mathematical Basis for
Relating Sludge Properties to FGD-Scrubber Operating Variables
(EPA-600/7-78-072).
The methods assessed by the study were visual and
instrumental. Of these, the instrumental (Coulter) approach was
most effective. The Coulter method measures particle volume and
reports it in terms of equivalent spherical diameter (ESD). This
method is fast, reliable, and well suited for determining the particle
ESD. It Is also excellent for comparing the particle (granule) size
distribution between samples obtained from the same source.
The study recommends visual methods (light and electron
microscopy) only for a quick survey of CaSO3 crystals. By these
methods, the general size and geometry of the particles are readily
apparent. Visual methods also reveal the presence of any significant
impurities or different particle types. The drawbacks to visual sizing
derive from the physical characteristics of the CaSO3 granules
themselves: they are nearly transparent at their edges, they
frequently clump together, and numerous voids render true particle
volume uncertain.
Visual methods did show that the CaSOj granules are actually
hundreds of small platelets growing out of a common center. These
granules are nearly spherical and contain many internal void
spaces. This explains why they are less dense, settle more slowly,
and dewater more poorly than the Individual platelets.
Nucleation studies monitored the effects of pH, Impeller speed,
concentration, temperature, kinetics, and seeding on both crystal
morphology (platelets or granules) and size. Results showed that
the granules form when rapid growth occurs; individual platelets
grow slowly and only in slightly supersaturated solutions of
CaSO3- Thus, even the definition of a "single" granule, which is
composed of many small platelets, may be uncertain. Other
findings were:
* Solution temperature and stirring speed have little effect
upon crystal type or size.
* CaSO3 crystals do not form at a pH below 3.2, where
bisulfite is the dominant ionic form.
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FGD QUARTERLY REPORT7WINTER 1979-80
In very supersaturated solutions (greater than three times
saturation), granules invariably form.
Whenever spontaneous nucleation occurs the resultant
crystalline form is granular.
Platelet CaSC>3 crystals can only be grown (in batches) at
low supersaturation levels with platelet seeding.
The resultant size (area) of crystals grown by using seeds
appears to be independent of the size of the seed crystals.
• Granules dissolve more readily than do platelets in mild
acid, probably because the granules have a much larger
relative surface area. Hence, SC>2 scrubber contactors
may be preferentially destroying the granular forms.
The nucleation studies support other findings that Initial growth
occurs preferentially along the length and width coordinates. Later,
the crystals thicken in the middle, and further growth occurs
primarily in thickness. Thus, judging crystal size by examining only
platelet area is ill-advised.
For additional information, contact the EPA/IERL-RTP Project
Officer. Robert H. Borgwardt; (919) 541-2336 or (FTS) 629-2336.
COST COMPARISON FAVORS LIMESTONE FGD
A recent study conducted by EPA and the Tennessee Valley
Authority (TVA) concludes that lime/limestone scrubbing is still the
simplest and cheapest wet FGD process available today for most
applications. The final report (EPA-600/7-79-177, see "FGD
Reports and Abstracts") is one in a series of FGD studies sponsored
by EPA to determine comparative costs of some of the more
prominent wet SO2 removal systems offered by vendors today.
The study. Definitive SOX Control Process Evaluation:
Limestone, Double Alkali, and Citrate FGD Processes, determined
the capital investments, annual revenue requirements, and lifetime
revenue requirements for each process and compared them with
one another. The base case for the study was a new, 500-MW coal-
fired power unit located in the Midwest. Revenue requirements were
estimated in mid-1980 dollars.
Capital Investment
In order of increasing investment, the base case ranking was
(1) limestone slurry, (2) dual alkali, and (3) citrate. However,
because ponding costs for the limestone process may offset the
additional equipment needs of the dual alkali process, the difference
between these two processes Is not great. The capital investment for
the citrate process is considerably higher; although since citrate Is
a recovery system and inherently more expensive. It should also be
compared with other recovery processes.
Annual Revenue Requirements
The study found a similar cost ranking for the annual revenue
requirements of the three processes; requirements were lowest for
limestone scrubbing and highest for the citrate process. For all case
variations estimated in this study, projected 1980 FGD revenue
requirements ranged from 3.25 to 8.78 mills/kWh. The largest
component of revenue requirements for all three processes was
represented by the capital charges. Electrical demand was
significantly greater for the limestone and citrate processes than for
the dual alkali process. Raw material costs were 19 and 22 percent
of the total annual revenue requirements for base case citrate and
dual alkali, respectively, while raw material cost for limestone was
only 8 percent of the total.
Lifetime Revenue Requirements
The relative rankings in lifetime revenue requirements were
similar to those projected for annual requirements. Because of the
declining operating profile of the power unit, the lifetime revenue
requirements were slightly higher than the corresponding average
annual revenue requirements. The average on-stream time over
the life of the plant was 4,250 hr/yr. compared with the higher first-
year on-stream time of 7,000 hr/yr used for the annual revenue
requirements.
The lime/limestone FGD process is the best known and most
completely developed FGD system in the U. S. today. The study
evaluation of limestone scrubbing was based on the considerable
data available. Although limestone is the cheapest FGD method
available for most applications, it does have certain disadvantages.
It requires intensive maintenance efforts and also produces a waste
sludge of questionable stability and environmental effect.
Dual alkali FGD is a competitive alternative to limestone,
especially when trucking Is used for disposal of the waste filter cake.
Dual alkali systems produce less waste solids than do limestone
systems. Hence, a smaller disposal area is required by dual alkali
processes. In addition, the dual alkali system requires less
maintenance than limestone scrubbing.
The citrate system is inherently more expensive since if is a
recovery system as compared with the throwaway processes
evaluated in the report. In addition, less is known about the citrate
process as an integrated operating system than is known about the
limestone or dual alkali processes. More information on large-scale
citrate operation is necessary in order to answer completely the
questions of real cost and operability.
Processes to be evaluated in future studies include lime
scrubbing, magnesia scrubbing, the Wellman-Lord process, and the
aqueous carbonate process. For further information, contact the
EPA/IERL-RTP Project Officer, J. E. Williams, (919) 541-2483 or
FTS 629-2483.
UTILITY FGD SURVEY IS EXPANDED AND UPDATED
An updated and expanded version of the EPA Utility FGD
Survey (EPA-600/7-79-022f, see FGD Reports and Abstracts),
prepared by PEDCo. Environmental, Inc., has recently been
released. The EPA Utility FGD Survey, an ongoing series of
compiled information on utility FGD systems in the United States,
will now be issued on a quarterly instead of a bimonthly basis.
These survey reports, including the most recent July-
September 1979 version, have now been expanded to include
information on energy consumption of some FGD systems. In
general, the current report gives additional design data, fuel sulfur
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FGD QUARTERLY REPORT/WINTER 1979-80
content, operating history, and actual SC>2 removal performance
data where those data are reported by the utilities. In addition, a
new section includes information on operational particle scrubbers.
The utility survey report Is generated by a new computerized
data base system and contains summaries of information
contributed by the utility industry, process suppliers, regulatory
agencies, and consulting engineering firms. It includes unit by unit
dependability parameters and discusses problems and solutions
associated with the boilers and FGD systems.
Additional information is available from EPA/IERL-RTP
Project Officer; N. Kaplan, (919) 541-2556 or (FTS) 629-2556.
SULFUR MARKET ADJUSTS TO INCREASED APPLICATION OF FGD PROCESSES
The production of elemental sulfur by various FGD processes is
receiving substantial attention. Although elemental sulfur is more
costly to process than other FGD by-products, it does have certain
advantages. Elemental sulfur is easily stored and can be marketed
as a solid. Thus it presents neither the disposal problems associated
with limestone-gypsum sludges nor the transportation difficulties of
sulfuric acid.
Approximately 60 percent of the sulfur consumed in the U. S.
today is used in various agricultural applications, especially in the
production of phosphate fertilizers. In addition, small amounts of
elemental sulfur or gypsum are used as soil conditioners and plant
nutrients. The remaining 40 percent of the sulfur is used by such
industries as petroleum refining, nonferrous metals smelting,
plastics and synthetics production, wood pulp manufacture, iron
and steel production, and paint manufacture.
As the application of FGD technology increases in this country,
the production of elemental sulfur will also grow. This will have a
significant effect on the U. S. sulfur market in the years to come. In
order to adjust to this new source, many innovative ways of using
elemental and other forms of sulfur are now being developed. Some
of these options for the future are described in the following
paragraphs, along with a summary of the U. S. sulfur market
today.
U.S. Supply and Demand Pattern
Much U. S. elemental sulfur occurs in deposits over salt
domes along the Gulf Coast, and current U. S. sulfur production is
located mainly in Louisiana and Texas. Most of this elemental sulfur
is mined by the Frasch process, a direct method of sulfur recovery
which involves pumping hot water into wells drilled in buried sulfur
deposits. The heated water contacts the sulfur which is then moved
to the surface as molten elemental sulfur.
According to the U. S. Bureau of Mines, however, the supply
pattern of sulfur will change dramatically in the coming years.
Frasch production will decrease, while by-product recovery from
various FGD and coal gasification processes will increase. The ulti-
mate effect of these changes in sulfur production will be to break
down the sulfur market into independent regional segments, each
having its own supply and demand characteristics.
The Sulphur Institute in Washington, D.C. estimates an
oversupply of elemental sulfur totaling 3.7 Tg (4.0 x 10^ tons) by
1985. By then the annual U. S. sulfur consumption may reach 14
Tg (15 x 10" tons); Canadian consumption may be as high as 2.3 Tg
(2.5 x 10" tons). This compares with an estimated sulfur production
of 20 Tg (22 x 10& tons) for 1985 from several sources, including
FGD, coal gasification, and Frasch recovery.
Several new uses for elemental and other forms of sulfur are
being developed in anticipation of this potential oversupply. The
two basic use catagories--agriculture and construction—are
described below.
Potential Role in Plant and Animal Nutrition
New agricultural uses of sulfur for plant and animal nutrition
could increase current annual consumption by 4.5 Tg (5 x 10° tons)
per year. Considerable attention is now focused on fertilizers with
high levels of sulfur as a means for improving crop quality. Sulfur is
an important plant nutrient with a major role in protein and
chlorophyll synthesis. Most fertilizers used since the 1950's have
not contained adequate amounts of sulfur, and sulfur deficiencies
are now common in soils throughout the world.
Accordingly, new fertilizers are being developed for the purpose
of supplying sulfur as a plant nutrient. These include granular
sulfur-bentonlte materials containing 90 percent elemental sulfur,
triple superphosphate-elemental sulfur, ammonium thiosulphate,
and sulfur slurries. Slurries, which are used in suspension fertilizers,
contain up to f>0 percent sulfur and provide a good method for
increasing fertilizer sulfur content without decreasing the
concentration of other nutrients.
Sulfur can also be applied to soils in the form of gypsum,
elemental sulfur, and some of Its acid-forming compounds. This
enhances water absorption and percolation, and is especially
valuable in arid regions. Acid-forming sulfur compounds, such as
sulfuric acid and ammonium and calcium polysulfide, lower soil pH
values, increasing the availability of phosphorous and some
micronutrients.
Studies are now examining the use of sulfur as a dietary
supplement for ruminant animals. Sufficient levels of sulfur in the
ruminant diet result in increased digestion of cellulose, improved
nitrogen retention, and increased microbial protein synthesis in the
rumen. Other benefits Include enhanced production of meat, milk,
and wool, and a lower cost of feed per pound of gain.
Sulfur as a Material for Construction
With the increased costs of asphalt, attention is now focused on
sulfur as a partial substitute for asphalt. Currently, this is one of the
most promising large-scale alternatives for sulfur consumption.
Research shows that as much as 50 percent of the asphalt in paving
materials can be replaced by sulfur. The Sulphur Institute estimates
that this method could save the U. S. 1.6 to 4.1 km3(10to26x 10<»
bbl) of oil per year, and at the same time improve the quality of
pavement.
Sulfur-asphalt mixtures have already demonstrated successful
commercial application. A material of this type was used on a
Texas highway constructed in 1975. Sulfur was dispersed In asphalt
and formed a sulfur-asphalt binder which was mixed with aggregate
to form the pavement mixture. This method demonstrated several
advantages over traditional processes, including improved
pavement characteristics, replacement of 30 percent of the asphalt
with sulfur, and a 30 percent decrease in the cost of materials
preparation. The performance of the sulfur section of the highway
has been excellent. Similar material has also been used on a
Nevada highway for 2 years without significant deterioration.
Sulfur can also be used to recycle asphalt, with subsequent
savings in both energy and raw materials costs. This method
involves mixing sulfur with old oxidized pavement and, according to
the U. S. Bureau of Mines, can save up to 120 kg (264 tb) of asphalt
and 880 kg of aggregate per Mg (1800 Ib per ton) of recycled
pavement.
Investigators have developed successful methods for preparing
stable, high-strength sulfur concretes. These materials are
especially suitable as replacements for Portland cement in acid and
brine environments. U. S. Bureau of Mines studies have shown that
sulfur concrete is resistant to acid and salt. Several potential
applications for sulfur concrete are now being tested, including
leach tanks, electrolytic cells, industrial flooring, and piping.
Additional new uses for sulfur are as coatings and foams. When
applied, these materials provide enhanced protection against
erosion and corrosion. To be used, these materials must be mixed
with such additives as plasticizers, fibers, viscosity control agents,
and wetting agents.
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FQD QUARTERLY REPORT/WINTER 1979-80
One use for sulfur coating is as a replacement for conventional
mortar in building construction. A hot sulfur coating can b« surface-
bonded to stacked blocks in place of mortar. Several buildings in
the U. S. and a number of structures in developing countries have
been constructed using this method. The sulfur coating is
waterproof, stronger than mortar, and can be used successfully with
low quality block materials. It Is also less costly than conventional
mortar. According to the Sulphur Institute, the estimated labor cost
for constructing a 12 x 8 x 2 m (40 x 25 x 8 ft) block house is $180 for
sulfur bond construction. This compares with $520 required for
mortar construction. Material costs are estimated to be
comparable. A drawback to the sulfur coating is that it is
flammable and is not accepted by existing building codes in some
countries.
Sulfur foam may be used for insulation. For instance, sulfur
foams can be placed under road beds in frost zones to prevent
freeze-thaw damage. At this time, however, sulfur foams are not
economically competitive with existing insulation foams.
Other new possibilities for sulfur use are in the very early stages
of development. One of these is a sodium sulfur storage battery for
use in electric cars.
In view of the many proven and potential uses of elemental and
other forms of sulfur, U.S. agricultural and industrial consumption
of these materials is expected to increase substantially in coming
years. This trend will have a positive effect on the marketability of
sulfur by-products derived from FGD.
FGD REPORTS AND ABSTRACTS
This section of the FGD Quarterly Report contains abstracts of
recently completed reports relating to flue gas desulfurization. Each
listing includes date of the report, National Technical Information
Service (NTIS) accession number, and other identifying numbers
when available.
Each report with an NTIS number can be ordered from
NTIS. The cost of paper copies varies by page count ($4.00
minimum); microfiche copies are $3. Payment must accompany
order. The address is:
National Technical Information Service
U.S. Department of Commerce
Springfield, Virginia 22161
(703) 557-4650; (FTS) 557-4650
EPA/IERL-RTP reports are available, as supplies permit,
through the EPA-RTP library. The address is:
U.S. Environmental Protection Agency
OA/Library (MD-35)
Research Triangle Park, NC 27711
(919) 541-2777
(FTS) 629-2777
EPA Utility FGD Survey: July-September 1979
M. Smith and M. Melia, PEDCo Environmental, Inc., Cincinnati,
Ohio, October 1979. EPA-600/7-79-022f. (NTIS No. Unavailable)
EPA Project Officers: N. Kaplan, IERL-RTP; and J. D. Herlihy,
DSSE.
The report is the last of three supplements updating the December
1978 - January 1979 report (EPA-600/7-79-022c) and should be
used in conjunction with it. The report was generated by a new
computerized data base system and differs from those of the
previous series in that the scope of design data for operating FGD
systems is vastly expanded, section formats are revised somewhat,
and a new section includes operational paniculate scrubbers. The
report gives a survey of utility flue gas desulfurization (FGD)
systems in the U. S. It summarizes information contributed by the
utility industry, process suppliers, regulatory agencies, and
consulting engineering firms. Systems are tabulated alphabetically
by development status (operational, under construction, or In
planning stages), utility company, process supplier, process, and
waste disposal practice. It presents data on boiler design, FGD
system design, fuel characteristics, and actual performance. It
includes unit by unit dependability parameters and discusses
problems and solutions associated with the boilers and FGD
systems. Process flow diagrams and FGD system economic data
are appended to the report.
Proceedings: Symposium on Flue Gas
Desulfurization--Las Vegas, Nevada, March 1979;
VolumesI and II
F. Ayer, Compiler, Research Triangle Institute, Research Triangle
Park, North Carolina, July 1979. EPA-600/7-79-167a, b. (NTIS
No. Unavailable). EPA Project Officer: C. J. Chatlynne, IERL-RTP.
The publication, in two volumes, contains the text of all papers
presented at EPA's fifth flue gas desulfurization (FGD) symposium,
March 5-8, 1979, at Las Vegas, Nevada. Papers cover such subjects
as health effects of sulfur oxides, impact of FGD on the economy
and the energy problem, energy and economics of FGD processes,
actual operating experience, waste disposal and by-product
marketing, and industrial boiler applications.
Definitive SOx Control Process Evaluation:
Limestone, Double-Alkali, and Citrate FGD Processes
S. V. Tomlinson, F. M. Kennedy, F. A. Sudhoff, and R. L. Torstrick,
Tennessee Valley Authority, Muscle Shoals, Alabama, August
1979. EPA-600/7-79-177. (NTIS No. PB 80-105828). EPA Project
Officer: C. J. Chatlynne, IERL-RTP.
The report gives results of a detailed comparative technical and
economic evaluation of limestone slurry, generic double alkali, and
citrate flue gas desulfurization (FGD) processes. Assuming proven
technology and using representative power plants, process design,
and economic projections were made: for a base case (500 MW, 3.5
percent sulfur coal, new unit) and for case variations in power unit
size, fuel type, sulfur in fuel, new and existing power units, waste
slurry ponding and filter cake trucking, and SOj removal (1.2 Ib
SOj allowable emission per million Btu heat input vs 90 percent).
Depending on unit size and status, fuel type and sulfur content,
solids disposal method, and overall project scope, ranges in
estimated capital costs in 1979 dollars are $71 to $127/kW for
limestone slurry, $80 to $130 kW for generic double alkali, and
$105 to $194/kW for citrate (recovery process). Results can be
scaled or altered to reflect other site-specific conditions. Capital
investment, annual revenue requirements (7000 hr/yr), and lifetime
revenue requirements over a 30-year declining operating profile
were estimated for the base case and each variation. Investment
costs were projected to mid-1979; annual revenue requirements
were calculated in projected mid-1980 dollars. Effects of variations
in various cost parameters were studied.
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FGD QUARTERLY REPORT WINTER 1979-80
Calcium Sulflte Crystal Sizing Studies
L. O. Edwards, Radian Corporation, Austin, Texas, August 1979.
EPA-600/7-79-192. (NTIS No. PB 80-128689). EPA Projecl Officer:
R. Borgwardt, 1ERL-RTP.
The report describes a reliable experimental method that can be
used routinely to determine the crystal size distribution function, a
measure that is required for a mathematical representation of the
nucleation and growth processes involved in the settling,
dewatering, and disposal of calcium sulfite sludge from
lime/limestone or dual alkali scrubbers, a major problem
associated with coal burning. (A recent EPA report presented a
mathematical description of the S(>2 scrubbing process, but found
discrepancies in the particle size distribution function when
measured by different techniques.) Optical and instrumental crystal
sizing methods were compared and the merits of each discussed;
Coulter counting is recommended. The two primary crystal forms,
platelets and granules, were shown to be related; granules are
clusters of platelets. Platelets, the preferred shape, form only in
slow growth conditions and require seeding. Particle clusters
complicate the crystal definition and counting processes. The
crystal size distribution was shown to be the sum of several
exponential population curves. Fly ash, if present, will dominate
counts for particles smaller than 1 micron.
Survey of Flue Gas Desullurization Systems:
Lawrence Energy Center, Kansas Power and Light Co.
B. A. Laseke, Jr., PEDCo Environmental Inc., Cincinnati, Ohio,
August 1979. EPA-600/7-79-199b. (NTIS No, Unavailable). EPA
Project Officer: N. Kaplan, IERL-RTP.
This report describes the results of a survey of operational flue gas
desulfurteatlon (FGD) systems on coal-fired utility boilers In the
United States. The FGD systems installed on Units 4 and 5 at the
Lawrence Energy Center of the Kansas Power and Light Company
are described In terms of design and performance. The FGD system
installed on each unit consists of two parallel two-stage scrubber
modules, each of which includes a rectangular variable-throat rod-
deck venturi scrubber arranged in series with a spray tower
absorber. Each system is also equipped with slurry-hold tanks,
mist eliminators, and in-line reheaters, as well as Isolation and
bypass dampers. The two systems share a common limestone
storage and preparation facility and waste disposal facility. These
FGD systems represent a second generation design replacement of
limestone furnace-injection and tailend scrubbing systems which
were originally installed on Units 4 and 5 in 1968 and 1971,
respectively. The original systems operated approximately 27,000
hours and 23,000 hours on coal-fired flue gas for Units 4 and 5,
respectively. The redesigned FGD system on Unit 4 went into
service in early January 1977. The Unit 5 FGD system went into
service on April 14, 1978.
Survey of Flue Gas Desulfurization Systems: Duck
Creek Station, Central Illinois Light Co.
B. A. Laseke, Jr., PEDCo Environmental, Inc., Cincinnati, Ohio,
August 1979. EPA-600/7-79-199a. (NTIS No. PB 80-126279K EPA
Project Officer: N. Kaplan, IERL-RTP.
The report presents the results of a survey of operational flue gas
desulfurization (FGD) systems on coal-fired utility boilers in the
United States. The FGD system installed on Unit 1 at the Duck
Creek Station of Central Illinois Light Company is described in
terms of design and performance. The system consists of four
parallel, wet-limestone, rod-deck scrubber modules designed for 25
percent capacity,each providing a total sulfur dioxide removal
efficiency of 85 percent. The bottom ash, fly ash, and scrubbing
wastes are disposed of in a sludge pond lined with a natural
impermeable material. The first module of this four module FGD
system was placed in service on July 1,1976, and operated
intermittently throughout the remainder of the year and for
approximately 1 month in early 1977. On July 23, 1978, the three
remaining modules were completed and all four modules were
placed In the gas path for treatment of high sulfur flue gas.
Survey of Flue Gas Desulfurization Systems:
Sherburne County Generating Plant, Northern States
Power Co.
B. A. Laseke, Jr., PEDCo Environmental Inc., Cincinnati, Ohio,
August 1979. EPA-600/7-79-199d. (NTIS No. PB 80-126287). EPA
Project Officer: N. Kaplan, IERL-RTP.
This report gives results of a survey of operational flue gas
desulfurization (FGD) systems on coal-fired utility boilers in the
United States. The FGD systems installed on Units 1 and 2 at the
Sherburne County Generating Station of the Northern States Power
Company are described in terms of design and performance. Each
unit is equipped with an alkaline fly ash/limestone two-stage wet
scrubbing system for the control of particulates and sulfur dioxide.
Each FGD system Includes 12 modules, 11 of which are required for
full-toad operation. The flue gas cleaning wastes are forcibly
oxidized, concentrated in a thickener, and discharged for final
disposal in a plant-site clay-lined settling pond. The Sherburne 1
and 2 systems were certified commercial on May 1, 1976 and April
1, 1977, respectively. Operation has been accompanied by a
number of problems, most of which have been or are being resolved
through system design modifications. Designed for a minimum
availability of 90 percent, the modifications have increased
availabilities to the low- to mid-90 percent range. The systems have
demonstrated compliance with particulate and sulfur dioxide
emission regulations.
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FGD QUARTERLY REPORT/WINTER 1979-80
Survey of Flue Gas Desulfurization Systems: Bruce
Mansfield Station, Pennsylvania Power Co.
B. A, Laseke, Jr., PEDCo Environ mental, Inc., Cincinnati, Ohio,
August 1979. EPA-600/7-79-199e. (NT1S No. PB 80-126295). EPA
Project Officer: N. Kaplan, IERL-RTP.
This report gives the results of a survey of operational flue gas
desulfurization (FGD) systems on coal-fired utility boilers in the
United States. The FGD systems installed on Units 1 and 2 at the
Bruce Mansfield Station of the Pennsylvania Power Company are
described in terms of design and performance. Each unit is fitted
with a wet magnesium-modified lime scrubbing system consisting
of six parallel, two-stage scrubbing trains arranged in two groups of
three. Ftue gas from each group of three scrubbing trains flows
together into an oil-fired reheater and is discharged through a
separate flue contained in a 290 m (950 ft) stack. The waste
disposal system is a three-part process consisting of a pumping and
treatment facility, transportation facility, and containment area.
Bruce Mansfield 1 commenced commercial operation on June 1,
1976. Bruce Mansfield 2 commenced commercial operation on
October 1,1977.Initial operation of these FGD systems was
characterized by problems with the reheaters, induced-draft fan
housing, and stack flue liners.
Sulfur Oxides Control Technology Series: Flue Gas
Desulfurization-.Wellman- Lord Process
Radian Corporation, Austin, Texas, February 1979. EPA-625/8-79-
001. EPA Project Officer: R. M. McAdams, IERL-RTP.
The new U. S. EPA Summary Report Series presents a summary of
engineering alternatives that can be used to solve existing
environmental problems. The first report in the series discusses the
Weilman-Lord FGD process. It includes a process description,
design considerations, environmental considerations, status of
development, raw material and utility requirements, and
installation space requirements. An errata is available to previous
recipients of this report upon request.
The Ability of Electric Utilities with FGD to Meet
Energy Demands
E. P. Hamilton, H. J. Williamson, J. B. Riggs, and T. J. An-
derson, Radian Corporation, Austin, Texas, January 1978. EPA-
650/3-78-002. (NTIS No. PB 284 098.) EPA Project Officer:
K. R. Durkee. OAQPS.
Impacts of FGD on U.S. electric: reliability and adequacy through
the year 2000 were evaluated. Coal-fired units on-line before
1986 and between 1985 and 2000 were considered for the nine
National Electric Reliability Council (NERC) regions. Each
region's ability to meet power demand (with reasonable and
typical reserves) as a power pool with and without FGD was
assessed. Different FGD model configurations and assumed avail-
abilities were considered. Power interchange capabilities which
might be used during FGD-induced outages were also evaluated,
as were reserves. It was concluded that a revised NSPS would
have little effect on system adequacy before 1985. By 2000, how-
ever, the NSPS would have significant impact on reliability and
adequacy requiring large amounts of additional generation to
offset the effects of FGD. Sensitivity of these results was analyzed
and mitigating measures were determined.
FGD Sludge Disposal Manual
Michael Baker, Jr., Inc., Beaver, Pennsylvania, January 1979.
EPRI-FP-977.
This manual provides suggestions and guidance to electric utility
operators of lime, limestone, alkaline flyash. and double-alkali
wet scrubbers in the processing and disposal of the waste
product. A decision path diagram is given to illustrate the options
available to the operators, and explain the steps necessary to
select a disposal system. Current practices in the U.S. and other
countries are briefly covered to illustrate trends and to supply
possible sources of information for the utility industry.
Major and trace components of the sludge are discussed along
with their effects on processing and disposal. Three different
methods are presented to determine the quantity of waste which
will be produced under a set of assumed conditions. Both wet
(ponding) and dry (landfill) disposal alternatives are described,
along with site selection and design recommendations for both
types. The problem of leachate from such areas is considered and
means of prevention or control are evaluated.
Options available for processing and disposal and the question of
fixation/stabilization are considered in view of the existing regula-
tions and the possible requirements of the Resource Conservation
and Recovery Act (RCRA) of 1976. Methods and equipment for
transporting the waste to the disposal area are also described.
Finally, the important subject of processing/disposal cost and the
prospects for utilization are considered. The various factors af-
fecting cost are discussed and procedures are suggested for esti-
mating the components of total cost under different sets of condi-
tions.
The FGD Quarterly Report is part of a comprehensive EPA Engineering Application/ Information Transfer (EA/IT) Program on flue gas
desulfurization (FGD). The report is designed to meet four objectives: (1) to disseminate information concerning EPA sponsored and conducted
research, development, and demonstration (RD&D) activities in FGD; (2)to provide progress updates on selected ongoing contracts; (3)to report
final results of various FGD studies; and (4)to provide interested persons with sources of more detailed information on FGD. The EA/IT Program is
sponsored by EPA's Industrial Environmental Research Laboratory, Research Triangle Park, North Carolina (IERL-RTP).
The FGD Quarterly Report is prepared by Radian Corporation under EPA Contract No. 68-02-2608. The EPA Project Officer is J. E Williams,
MD-61, USEPA. IERL-RTP, Research Triangle Park, NC 27711, (919) 541-2483, (FTS) 629-2483. The Radian Project Director is Elizabeth D.
Gibson, P. O. Box 9948, Austin, Texas 78766 (512) 454-4797. Contributors to this issue were N. S. Gates and E. D. Gibson.
The FGD Quarterly Report is distributed, without charge, to persons interested in FGD. Those wishing to report address changes, or initiate or
cancel their free subscriptions to the FGD Quarterly Report may do so by contacting the EPA Project Officer or Radian Project Director named
above.
The views expressed in the FGD Quarterly Report do not necessarily reflect the views and policies of the Environmental Protection Agency.
Mention of trade names or commercial products does not constitute an endorsement or recommendation for use by EPA.
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