ELECTROSTATIC PRECIPITATORS Presented by-Deepak keshri IEC -CET Section-ee 1

Introduction Particulate Collection Device used in industries to minimize air pollution. Principle of operation Electrostatic attraction. Efficiency of 99% in many industries. Can handle large gas volumes with a wide range of inlet temperatures, pressures, dust volumes, and acid gas conditions . Can collect particles of varying sizes in dry and wet states .

Theory of Precipitation: Theory of PrecipitationCharging, Collecting & Rapping. Particle charging Discharge & Collection Electrodes Corona Discharge Avalanche Multiplication Ionization of gas molecules Particle Collection Particle Removal

Particle Charging

*Ionization of Gas Molecules *Particle Charging Field charging, Diffusion charging, Electron charging

*Particle Removal by rapping *Particle collection *Particle Removal by rapping

Components of an Electrostatic Precipitator Discharge electrodes Collection electrodes High voltage electrical systems Rappers Hoppers Shell

Discharge Electrodes: Typical wire discharge electrodes Rigid frame discharge electrode design

Typical rigid discharge electrode Flat-plate discharge electrode

Collection Electrodes:

High Voltage Electrical system *Transformer-rectifier (T-R) sets *Primary voltmeter *Primary ammeter *Secondary voltmeter *Secondary ammeter Spark meter

Rappers: *Typical hammer/anvil rappers for collection plates *Typical magnetic-impulse rappers for collection plates

Hoppers: *Strike plates *Poke holes *Vibrators *Rappers Hopper Rotary airlock discharge device Double-dump discharge device

Conveyors: Pneumatic conveyor for transporting dust from ESP Drag conveyor Screw conveyor

Types of Electrostatic Precipitators *Tubular Precipitators *Plate Precipitators

Cold-side ESPs Cold side ESPs 1) volume of flue gas that is handled is less 2) less costly 3) overall size of the unit is smaller 4) used to remove fly ash from boilers that burn high sulfur coal

Hot Side ESPs *used in high-temperature applications (Cement kiln) *the gas volume treated in the ESP is larger *the overall size of the precipitator is larger making it more costly *structural and mechanical problems occur in the precipitator shell

Wet Side ESPs *Wet ESPs are used for industrial applications where the potential for explosion is high . *When dust is very sticky, corrosive, or has very high resistivity . *It does not have problems with rapping rentrainment or with back corona .

Dry Side ESPs *Particles are charged and collected in a dry state . *Dust particles collected are removed by rapping. *Used in steel furnaces, cement kilns and fossil-fuel-fired boilers.

Conclusion All ESPs, no matter how they are grouped, have similar components and operate by charging particles or liquid aerosols, collecting them, and finally removing them from the ESP before ultimate disposal in a landfill or reuse in the industrial process. The precipitator should be designed to provide easy access to strategic points of the collector for internal inspection of electrode alignment, for maintenance, and for cleaning electrodes, hoppers, and connecting flues during outages.

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