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A26 Electrostatic
Precipitators, Bag Filters and Emission Standards for Coal-fired
Power Plants in China
Wang
Liqian,
Zhang Dexuan, Yang
Xiuyun
Abstract
From 1980 to 2003, power installed capacity in
China
grown from 65,869 MW to 384,500 MW, near 6-foldes increased. By the
end of 2003, coal-fired power increased
to 285,640 MW, thus induced continuosly increased air pollutions.Accompanying
the emission
standards from
tolerant to
stringent, high efficiency
dust collectors
gradually played
dominative role.
From 1955,
precipitators went into Chinese power plant
and by 2003 it already shared 82% of the total coal power capacity.
For precipitators, very difficult coals and rather favorable coals were encountered. In 2001,
first “successful” bag filter put into operation,
after that, it grown very rapidely. From January
2004, new coal power emission standard of 50mg/m3
implements,
considering the big variety of
Chinese coal, the choose between precipitator or bag filter will be
worth considering. An primary economic coparison is given.
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A27 SO3
Injector Fouling In Flue Gas Conditioning Systems
Michael
Vukmir & Michael W. Rollock, BS ChE.
Abstract
SO3 injection probe fouling is a major concern in the operation and
maintenance of SO3 flue gas fly ash conditioning
systems. The
source of the problem is moisture in the combustion air used
by the sulfur burning SO3
gas generator systems.
Proper SO3
injector probe operating temperature control and operation can alleviate many of the problems.
The use of dry combustion
air in combination with conventional SO3 flue gas conditioning systems has the potential
of reducing
both the
quantity of
sulfuric acid
generated and
the dew
point temperature of the sulfuric acid mist formed in the hot
gas piping and SO3
injection probes.The advantages of dry combustion air will be in
reduced injector fouling - resulting in lower maintenance
costs and improved fly ash conditioning performance.
The lower sulfuric acid dew
point temperature of the SO3
gas will offset the additional operating costs associated with
producing the
dry combustion
air and
can also
reduce the
capital costs
for new
installations when combined with SO3 gas flow splitting and biasing technology.
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A28 FLUE
GAS
CONDITIONING
-
SO3
INJECTION
RATES
FOR
SOUTH AFRICAN
COAL ASHES
Frans
Bosch
Abstract
Flue gas conditioning at some Eskom power
stations has required lower SO3
injection rates than those predicted by models or FGC vendor
experience. The
required injection rates were about a third of predicted, which was an unexplained
anomaly. The
paper offers an explanation and proposes a method for determining whether a coal
ash will behave “conventionally” with SO3
FGC or will require a lower than expected injection rate.
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A29
The
Newest Technical Results Capable of Remarkably
Increasing
ESP Efficiency
Wang
Weixue,
Fang Aimin,
Cao Feng
Abstract
Since
the middle of 1980s, State Power Environmental Protection Research
Institute
has
been
dedicating
its
efforts
to
the
research
in increasing
efficiency of ESPs, especially those operating under the worst
conditions
or
in
collecting
dusts
with
high
specific
resistance.
The profound
research is developed in the respects of improvements of power supply’s
characteristics, adoption of more ideal modes of energization,
elimination
of
back
corona
hazards
etc.
and
a
series
of
essentially practical
technical results have been achieved.
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A30 Improved
Control of Primary Fine Particulate
Emissions
with Electrostatically Augmented Fabric Filtration
Robert
F. Heaphy, Kenneth M. Cushing, Wallis A. Harrison
Abstract
Southern
Research Institute (SRI), under a cooperative agreement with the
United States Environmental Protection Agency (USEPA), is reporting
the results of an investigation of electrostatically stimulated
fabric filtration (ESFF) for particulate control on a utility boiler
fired with pulverized coal (2001-2003). In pilot-scale testing at
the SRI Combustion Research Facility and in a long-term, pilot-scale
demonstration of ESFF at a full-scale utility boiler, ESFF
consistently outperformed conventional fabric filters
(2001-2002).For these tests particle charging was accomplished with
high voltage electrodes mounted outside of, but co-axially, with the
pulsejet filter bags. With ESFF, total mass emissions without
cleaning were one-fourthto one-fifth of those for a conventional
pulse-jet fabric filter (FF).
Penetration of particles smaller than one micrometer was
about one order of magnitude less with ESFF. In addition, pressure
drop increased about one-third as fast with ESFF as compared with
FF, reducing the frequency of bag cleaning.
Since a significant fraction of the total particulate
emissions occur as a consequence of cleaning, the reduced cleaning
schedule in itself leads to lower emissions of all particle sizes.
Recently, additional testing (2003) has been completed using a
cooled-pipe precharger to impart charge to the fly ash particles.
The previous high voltage electrodes were replaced with large
diameter electrodes intended to produce only a collection field.
Improved baghouse performance was observed with this
arrangement, producing filter drag values 50 to 60% lower than those
experienced during normal baghouse operation. Of special note was
the observation that significant performance improvement was
measured with only the collection field energized (no precharging of the fly ash).
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