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ICESP VII CONFERENCE PAPER ABSTRACTS DE-2 SERIES

Held in Kyongju, Korea
September 20-25. 1998

The International Conference on Electrostatic Precipitation (ICESP) is the official conference of the International Society for Electrostatic Precipitation (ISESP).  

The following is a list of the Abstracts for the DE-2 Series papers from the VII ICESP Conference.  

DE06  Experimental Study of a Moving Electrode Electrostatic Precipitator
B.H. Ham, S.C.Moon, T.S.Byun,
Korea Heavy Industries
& Construction Co.,LTD., P.O.Box 77 Changwon
Y.J. Kim, S.H. Jeong, W.S. Hong, B.K. Ha, T.K.Hwang,
Combustion
& Environmental Engr. Group, Thermal & Fluid Environmental Department,
Korea Institute of Machinery
& Materials

Abstract
For the purpose of improving the collection efficiency of high resistivity dust, moving electrode electrostatic precipitator (MEEP) was developed.  It is well known that collection of high electrical resistivity dust in a EP have several problems such as back ionization, reentrainment, and excessive sparking.  Avoiding these problems some countermeasures are designed such as wide pitch EP, pulse power supply and MEEP were proposed.  Pulse energization was proposed in the 1950’s, and its industrial applications are expending these days.  MEEP was developed in 1979 and applied many industries such as Oil Refinery and Coal Fired Boiler to collect the high electrical resistivity dust.  MEEP has moving collection plate and brush which dislodges the collected dust layer on the collecting plate, therefore collecting plate can be maintained clearly.

In this study several parameter was investigated to know the characteristics of moving electrode electrostatic precipitator such as collecting plate velocity, applied voltage, gas velocity, particle load and applied voltage waveform.

The experimental results show that collection efficiency and V-I characteristics of MEEP for high resistivity fly ash are very stable. Thus collection efficiency is high in comparison with the conventional EP.  The effect of intermittent pulse discharge on the collection efficiency and specific corona power increase with pulse period in the experimental condition.

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DE07  Design of Electrostatic Precipitators after Pulverized Coat Boilers Firing Low Sulphur Coals
KjeJl Perle
ABB Environmental Systems AB
Srivats Srinivasachar and Benjamin R. Pease
ABB Combustion Engineering, Inc

Abstract
The ever-increasing concern of particulate emissions and the increasing demand for electricity call for higher collecting efficiencies from electrostatic precipitator (ESP).  One of the difficulties is meeting lower outlet emission limits with pulverized coal-fired boilers burning low sulphur coals, because the corresponding fly ash often has a high resistivity.  The high resistivity ash causes back-corona conditions within the ESP and lowers collection efficiency.  Larger precipitators have to be supplied to address this problem.

Predictions of severe corona suppression due to high concentration of ultra-fine ash (space charge effect) and of the dust cake resistivity can be improved with better knowledge of the characteristics of the particulate entering the ESP.  A more efficient and reliable ESP can then be designed even for the low emissions that are demanded now.

This paper briefly describes investigations that have been conducted by ABB to combat the problem of high resistivities in ESPs.  Various approaches to superior design such as flue gas cooling, use of spiral discharge electrodes and micro-second pulse energization are described.

Specifically, the performance behavior in the ESP for a large number of worldwide coals is presented in the context of the detailed ash particulate size and composition.  A drop-tube furnace was used to produce ash particles similar to those generated in a pulverized coal-fired boiler.  Particle size and fly ash composition distribution varied substantially even for coals with similar bulk ash composition.

The effect of different boiler conditions on the ash properties is also presented.  A high flame temperature generates a high amount of ultrafine particles, ~0.1.  The resulting high surface area of the ash, in some cases, may not be fully conditioned by the available sulphur trioxide in the combustion flue gas, resulting in high dust cake resistivity.

Measurements of the independent effects of flue gas temperature and humidity have been evaluated during controlled conditions in pilot-scale tests.  This provides a good basis for implementing designs with reduced ESP size.  A review of experience of ESP operation at low gas temperatures is presented in this context.



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DE08  Horizontal Discharge Electrodes in an Electrostatic Precipitator
Leif Lind
FLS milje a/s

Abstract
Traditional discharge electrodes in electrostatic precipitators with horizontal gas flow are vertical wires, sometimes weighted-wires, vertical barbed wires or strips, or vertical rigid tubes fitted with discrete emitter points.

Horizontally aligned discharge electrodes have advantages with respect to production, packing, transportation, erection and maintenance over vertically aligned electrodes.  Simple theories of the electrodynamic process mention the concept of “electrical sneakage”, which should exclude designs applying horizontally aligned discharge electrodes in horizontal gas flow precipitators.  Yet, it seems that reality is more complex, and laboratory experiments have revealed that such type of discharge electrode is at least as efficient as discharge electrodes of traditional design.

The present paper will report laboratory results with horizontal discharge electrodes and attempt to explain why the precipitator operates well in spite of “electrical sneakage” and in spite of the risk of provoking more intense secondary flow such as longitudinal rolls.


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DE09  The Collection of Fine Particles by an Electrostatic Precipitator with Quadruple Pre-chargers
J.5. Chang, P.C. Looy, C. Webster, A.A. Berezin
DepartmentofEngineering Physics,
A..Zukeran, T. Ito
Department of Electrical and Electronics Engineering

Abstract
The wire-plate type electrostatic precipitator (ESP) has been used to remove dust particles from industrial flue gases and high collection efficiency has been achieved PM 10 particles.  However, performances of ESP for submicron and ultrafine particles under high dust loading conditions are relatively low and pre-charging techniques are proposed to overcome this problem.  In this work, the effects of dust loading on the wire-plate electrostatic precipitator equipped with dc or pulse energized quadruple pre-chargers are experimentally investigated.  Four section electrostatic precipitator is used in the present set-up, where first, second and fourth sections are conventional wire-plate electrodes and the third section is quadruple pre-charger.  Aerosol particles are generated by a combustion of incenses and the dust loading is controlled by a number of incenses combusted in an upstream combustion chamber.  Size distribution of particles is measured by condensation nucleation particle counter and image analyses of the scanning electron microscope pictures after sampling of particles, where mean diameter is 0.2 µm.  Conventional dust monitor is used for dust leading measurements.  Experiments are conducted for the dust loading from 5 to 155 mg/m3 or 108 to 1010 particle/m3, the flue gas temperature, Tg from 23 to 100oC, the wire-plate applied voltage from 0 to 25 kV, the pre-charger applied voltage from 0 to 25 kV at flue gas flow rate Qg = 12 Nm3/h.  The result show that the collection efficiency of ESP decreases with increasing dust loading and flue gas temperature while increases with increasing applied dc pre-charger voltages and pre-charger cooling temperature.

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DE10  Electrostatic Lentoid Precipitator and its Performance
Chen Shixiu
Dept. of Electrical Engineering
Wuhan University of Hydraulic & Electric Engineering
Chen Xuegou
Dept. of Electrical AutomationWuhan University of Technology

Abstract
This paper briefly introduces some prominent merits and special performances of electrostatic lentoid precipitator (ESLP), then, gives the explanation why ESLP possesses these merits and performances.  In the end, a suggestion of applications is presented.

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