Measurement of dust resistivity and back corona in ...Mechanische Verfahrenstechnik technische...

Fakultät Bio- & ChemieingenieurwesenMechanische Verfahrenstechnik

technische universität dortmund

Measurement of dust resistivity and back corona in electrostatic precipitators

D. Pieloth, M. Majid, H. Wiggers, P.Walzel

PiKo Workshop Universität Bremen / 31st March 2011

Fakultät Bio- und ChemieingenieurwesenLehrstuhl Mechanische Verfahrenstechnik

D. Pieloth, M. Majid, H. Wiggers, P. Walzel | 31.03.11


PiKo Workshop Uni Bremen31st March 2011

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Motivation

ElectroStatic Precipitators (ESP)

Dust resistivity measurement

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•Experimental setup

• New measurement chamber

• Summary and Outlook

Particle diameter and dust resistivity

Measurement program

Dust resistivity

Outline

Back corona and the collection efficiency of electrostatic precipitators

Design





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Electrostatic precipitator•

Dust deposition pattern within an electrostatic precipitator





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Dust resistivity•

I = electric currentρ = resistivitys = layer thicknessA = area of collecting electrodej = current density

Decrease of E-Field strength in electrostatic participator due to voltage drop within the dust layer

Back discharge of already absorbeddust particles

Back corona due to overriding the E-Field strength within the dust layer

Drop of collection efficiency of electrostatic precipitators

Mean E-Field strength within the dust layer:





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Dust resistivity and the collection efficiency of electrostatic precipitators

Definition of dust resistivity ρ:•

R = resistance (Ohm’s law: I = U/R)s = layer thicknessA = area of collecting electrodeρ = dust resistivity

Source: Weber/Brocke

Influence of resistivity ρ on collection efficiency of electrostatic precipitators e.g. migration velocity

-> increase of resistivity ρ-> drop of migration velocity-> collection efficiency decreases





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Measurement of dust resistivity•

Experimental setup





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Measurement of dust resistivity•

Electrode arrangement





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Back discharge of already separated dust particles due to air flow•

Dust collecting plate within an electrode of an electrostatic precipitator

Adhesion of the upper dust layer within E-Field?

Influence of current density, dust properties, gas conditions?





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Particle diameter and dust resistivity•

Particles used in dust resistivity measurement(scanning electron microscope pictures)





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Particles used in dust resistivity measurement(scanning electron microscope pictures)





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New dust resistivity measurement chamber•

Design aims

max. air temperature 500º Cstainless steeldefined dust layer thicknessbetter visibility of processes within chamberlower heat lossadhesion of dust (gas stream velocities)

new measurement chamber





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Schematic of new dust resistivity measurement chamber•

adhesion of dust (different gas stream velocities will be applied)





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Detection of particle morphology effects on resistivity ρ and back corona under definedair conditions (Glass, γ- Al2O3, Limestone)

Experiments with dust layers collected with collecting plate during operation of an electrostatic precipitator(electrostatic precipitator, TU Dortmund)

Adhesion of dust particles on top layer of dust, detection of release of those particles into gasstream (Laser beam experiments)

Measurement program





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Summary and Outlook•

First results for dust resistivity measurement (dust particle diameter, air conditions)

Construction of new dust resistivity measurement chamber almost finished

Infrastructure for dust resistivity measurement in place(experience, measurement methods, electrostatic participator)

Vielen Dank for the financial support by

Thank you for your attention!

Measurement program with new measurement chamber will start soon

Measurement of dust resistivity and back corona in ...Mechanische Verfahrenstechnik technische...

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