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ICESP VII CONFERENCE PAPER ABSTRACTS FP-3 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 FP-3 Series papers from the VII ICESP Conference.  

FP11 In-situ Measurement of Local Particle Fluxes in a Laboratory-scaled ESP
Hans-Joachim Schmid and Heinz Umhauer
Insititute of Mechanical Process Engineering and Mechanics University of Karlsruhe

Abstract
An earlier investigation on grade efficiencies of ESPs yielded significantly higher separation efficiencies for small particles with a diameter of less than 2 m than predicted by any model.  Therefore, several experiments were conducted in a lab-scaled type model precipitator with flat plates and smooth wires with monodisperse 1 m particles to verify and understand this phenomenon:  An optical in-situ measurement yields local particle flux profiles.  By integrating these profiles balances for several small parts of the precipitator can be made giving deeper insight in local particle precipitation.  Furthermore particle change measurements for an aerosol sample directly from the precipitator channel were done.

The flux profiles show the development of a concentration profile along the duct which gets steeper towards the wall.  These profiles are very similar, if for different operating parameters the Duetsch-number is kept constant.  On the other hand the local balances always show a much higher separation efficiency that predicted the Deutsch theory and partly even higher than predicted by laminar flow mode.  The charge measurements yielded significantly higher particles charges than predicted by common charge models

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FP12 Influence of Dust Particles on V-I Characteristics in an Electrostatic Precipitator
Joon-Ho Ko, Dong-Goo Kang, Hyoung-Kuen Park and Cha-Seok Mun
Energy & Environment Research Department
Hyundai Industrial Research Institute
Hyundai Heavy Industries, Co. Ltd.
Cheonha-don, Dong-ku Ulsan, Republic of Korea

Abstract
A new model was developed in the wire-plate type electrostatic precipitators (ESPs) for estimating the electric performance in the presence of dust particles.  To solve corona current distribution in diverging field, two interactive methods were used.  In small particles, the turbulent flow interaction has an influence on the removal efficiency by the diffusion force.  Accordingly higher particulate space charge gave strong suppression of corona due to the inhibition of ions flow from wire to plate.  It reduced the average corona current and the collection efficiency in the electrostatic precipitator.

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FP13 A Preliminary Study on the Adhesive Forces of Precipitated Dust Layer
Tang Minkang and Chen Guofang
Department of Construction Engineeering Southern Institute of Metallurgy

Abstract
The mechanical properties of precipitated dust layer on the collection electrode in ESP have a direct effect on rapping and removing dust layer.  The properties and their effect are discussed in detail in electrostatic forces produced by dust particles which carry free charges or by polarizing dust particles or by contacting closely between particles or between particles and the collection surface of the electrode.

The results indicate when dust particles carrying free charge reach the collection electrode the direction of the electrostatic forces acted on the particles point towards the electrode and this direction can be changed with the time.  The resistivity of particles is on of effecting factors for this change.  The polarizing electrostatic force produced by fetter charge makes the dust particle arrange along the lines of the electric field and closely agglomerate together.  The contacting electrostatic force between particles has a significant effect on rapping and removing dust from the plate, and the one between particles and collecting plate take advantage of agglomeration and collection of the particle.  To change work function of the contacting materials is an important way to improve result of rapping and removing dust layer.

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FP14 A Preliminary Study on the Adhesive Forces of Precipitated Dust Layer
Yuan Yongtao and Zhao Yi
environmental Engineering Department

Abstract
The dielectric properties of Li, K and Na et al in FA were verified by many experiments.  The clear and identical conclusions of electrical conduction for Fe and C have had been obtained.  It is found by tests in this paper that the electrical conduction of carbon not only depends on the total content of carbon, but also more depends on the coalification. The electrical conduction of high coalification carbon particles is greatly different from that of low coalification carbon particles; the electrical conduction of Fe depends on its speciation.  The specific resistivity and the field strength of electrical breakdown were affected by FecO4 greatly, and by F32O3 slightly.  The initial theory analysis for the conclusions of the above two test is done in the paper.

The dielectric properties are shown using the specific resistivity and the field strength of electrical breakdown.  The study of dielectric properties of FA has a special significance in the field of electrostatic precipitation.  The dielectric properties of FA depend on both outside conditions (flue gas parameter) and inside factors (chemical component of FA).  The charge conduction of Na2O, LiO and K2O et al in FA has been verified by some experiments.  But the experimental study on the components of iron and carbon is very little, and the results are relative different, even the some viewpoints are opposite.  In this paper, the investigation of the dielectric properties of iron and carbon in FA was carried out by experiment, and some advances were obtained.


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FP15 An Experimental Study of Electrostatic Precipitator Plate Rapping and Reentrainment
Jae-Keun Lee, Jae-Hyun Ku, Jung-Eun Lee, Seong-Chan Kim, You-Chull Ahn, Jin-Hyouk Shin, and Seok-Heui Choung
School of Mechanical Engineering

Abstract
An electrostatic precipitator is useful for the removal of the particulate emissions from industrial power plants.  However, few research papers related to the rapping process to separate fly ash from the collecting plates have been published.  In this research, the physical, chemical, and electrical characteristics of fly ash generated from coal fired power plants were analyzed using a particle counter, a filter sampler, a scanning electron microscope, and a resistivity meter.  The evaluation of the rapping process and reentrainment in a laboratory scale electrostatic precipitator is performed using a plate rapping system, an ash feeder, and a power supply.  The principal ingredients of fly ash used at present in the coal fired power plant were SiO2(65.5%), Al2O3(24.0%), and Fe2O3(5.0%).  The mass median diameter was measured about 20 ~ 30 m.  Fly ash resistivity at 150OC was measured of 1010 Ω cm and it was expected that the collection efficiency might decrease due to back-corona phenomena.  The rapping efficiency was found to increase with increasing the thickness of ash layer and rapping acceleration.  Also the rapping efficiency at power-off in a discharger was higher than that at power-on.  The ash size of reentrainment  at rapping were smaller than that of the fly ash supplied.  The optimal rapping condition was found to be 3.5mm thick in fly ash layer deposited in the collecting plates.  Therefore, collection efficiency, rapping efficiency, and reentrainment to design the high efficiency electrostatic precipitator should be considered.

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