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C4-1
Precipitation Characteristics of Fly Ash With High Percentage of
Aluminum
Zhang
Dexua
Abstract
While we purify the flue gas from
coal-fired power plant by ESP, we often not only come across the
high resistance dusts, but also encounter those dusts which is
specially sensitive to the gas velocity.
However, through retrofitting and testing research on the ESP
which is complied with two 200t/h boilers of HH power plant and also
compared with operating conditions of other power plants, we find
that gas velocity will greatly influence the collection efficiency
while content of AL2O3 in fly-ash is over 45% (esp. appearance of
pure AL2O3 through Mineralogy analysis for fly-ash).
Here we analyzed the ash samples collected iso-kinetically in
outlet and inlet of ESP, got the physical/chemical characteristics
and mineral structures of collected ashes from different electrical
fields. Finally
differences and influence factors under these situations were found
out. Through
comparisons, we also testified that if the total percentage of SiL2,
AL@O3 reaches to about 93% of fly-ash composition, not only very
large SCA are needed, but also the operation of ESP will change
greatly with different percentages of these three compositions.
Fly ash with very high percentage of AL2O3 may not bring
clear back corona, but it may be very sensitive to gas velocity,
result in heavy re-entrainment.
Nevertheless, for those fly ashes, mainly compose of SiO2
provisions to prevent back corona will be necessary.
As for Fe, it exists in form of Fe2O3 or form of Fe3O4 and
their percent ration in fly-ash will also give different ESP’s
operation.
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C4-2
Typical Kinds of Coal in
China
and Some Special Coals with Their Fly Ash Difficult to Precipitate
by ESP
Precipitators.
Wang
Liqian, Li Rongbao
Abstract
China
, vast in territory, has manifold of
coal. The
characteristics of typical
China
coals, especially which influence
the operation of ESP, are briefly described at first.
Among them, there are some very special coals.
For examples, some kinds of coal in
Southwest China
have sulfur contents as high as 5
percent, gave high ESP efficiencies but serious corrosion problems.
Coal of Dawukou,
Ningxia
Province
, has 53% ash in which Al2O3
and SiO2 totally occupied 91.4%, so that high dust
concentration and very high resistivity gave ESP a lot of troubles.
Fly ash from boiler burn mixed coal of Haibowan and Zhunger,
Inner Mongalia District has 47.7% of Al2O3 and
42.8% of SiOs while Na2O content only 0.01%.
Perhaps this is the worst case for ESP in
China
, because a large amount of Al2O3
appears in the form of very fine kaolin clay results in serous
reentrainment, while the remainder alumina and silicon give high
resistivity hence very low collection efficiency.
Problem analysis, countermeasures and discussions for these
situations are given finally.
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C4-3
The Impact on
ESP
Efficiency and Counter Measures When Low Sulfur Coal Begin to be
Used in Coal-fired Boilers
Weixue
Wang, Yabin Jiang, Dahong Yang, Qiang Wang, Xiaohua Zhu, Zhenyu Wang
Abstract
In this paper the electrostatic
precipitator for a 300MW generator coal-fired boiler is adopted as
an object to expound the impact on the dust removal efficiency of
the original ESP and the counter measures to overcome the bad
effects.
Owing to more
and more strict governmental regulations of pollutants discharge, a
good many large coal-fired power station change to burn low sulfur
coal so as to decrease Sox emission in flue gas.
As a result, Sox emission is decreased, but the dust removal
efficiency of the ESP is also decreased remarkable, which leads to
remarkable increase of dust emission.
Aiming at this problem, the writers select a typical 300MW
generator boiler as an object and make some beneficial exploration
in the impact on dust removal efficiency of ESP as well as
improvement measures as the boiler changes to burn low sulfur coal.
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C4-4
Improvements in Predicting the Effects of Sulfur Trioxide Vapor on
Fly Ash Resistivity
Joseph
D. McCain, Kenneth M. Cushing, Southern Research Institute and Ralph
F. Altman, Electric Power Research Institute
Abstract
No Abstract
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C4-5
Flue Gas Conditioning for Enhancing the Performance of Older ESPs to
Provide Fuel Flexibility
Michael
Durham, PH.D., C. Jean Bustard, Richard Schlager, and Ken Baldrey,
ADA
Environmental Solutions
Abstract
New and emerging regulations such
as PM2.5 and restrictions on emission of air toxics have created a
demand for new technologies to reduce the emissions of fine
particles from large industrial sources.
ADA-ES has commercialized a family of proprietary, flue gas
conditioning agents that decrease particle resistivity and improve
the performance of ESPs with resistivity related performance
problems. The new
additives are effective on a wide range of coal-ash chemistries,
which allows the utility flexibility to select the most economical
coal. These alternative
conditioning agents are less toxic than SO3 and NH3
and are capable of improving performance at conditions under which
the conventional technology is not effective, such as at high
temperature or with either highly alkali or highly acidic ashes.
ADA_ES has
enhanced its product line through an R&D program granted by the
Department of Energy National Energy Technology Laboratory (NETL).
The goal of this program is to develop a family of non-toxic
flue gas conditioning agents to improve the cohesivity and
agglomeration of the flyash particles.
The specific niche is the developing market of older
cold-side ESPs that are relatively small in size and were designed
to operate at higher velocities than modern ESPs.
Because of high gas velocities in these ESPs, the collected
particles can be blown off the collector plates and result in
increased emissions. This
paper provides an update on full-scale performance of ADA_ES
conditioning agents at several coal-fired boiler installations.
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