ELECTRO STATIC PRECIPITATOR [ESP]

1 ELECTRO STATIC PRECIPITATOR [ESP]Donnerstag, 12. September 2013Fu zeilentext1 Controlling Air PollutionClean Air is an essential resource to the people surrounding theindustrial belts. Air pollution is one of the major contributorforEnvironmental Pollution. The industrial gases have pollutantsthat directly impacts on health and restrict in , 12. September 2013Fu zeilentext2 TodayElectrostaticPrecipitatorshavecomea longwayandarewidely used in all major Power Plants, Chemical , Cement andSteel Industries. They absorbs more than 99% of dust particlesand other substances while passing through the ESP and theexhaust gasses coming out of the chimney are with in line of theEmission Standards prescribed by Central Pollution is ESP Particulate Collection Device used inindustries to minimize air pollution Principle of operation Electrostaticattraction Efficiency of 99% in many industriesDonnerstag, 12.

2 September 2013Fu zeilentext3 Can handle large gas volumes with awide range of inlet temperatures,pressures, dust volumes, and acid gasconditions Can collect particles of varying sizes indry and wet statesComponents of an electrostatic PrecipitatorDonnerstag, 12. September 2013Fu zeilentext4 Gas Distribution ScreenThese screens are of modular design manufactured out of steel sheets andhang within a framework in the ESP inlet casing to maintain uniformdistribution pattern of gas flow throughout the cross section of ESPD onnerstag, 12.

3 September 2013Fu zeilentext5 Support and Shaft InsulatorThe whole emitting frame system is suspended from the roof throughSupporting Insulator to avoid any short Rapping Mechanism Shaft for electrodes is connected to the drivingmechanism through shaft , 12. September 2013Fu zeilentext6 Discharge ElectrodesDischarge electrodes emit charging currentand provide voltage that generates anelectrical field between the dischargeelectrodes and the collecting plates. Theelectrical field forces dust particles in the gasstream to migrate toward the collecting particles then precipitate onto thecollecting plates.

4 Common types of dischargeelectrodesinclude:Donnerstag, 12. September 2013Fu zeilentext7electrodesinclude: Straight round wires Twisted wire pairs Rigid masts Rigid frames Rigid spiked pipes Spiral wires Barbed discharge wiresWire discharge electrodesRigid frame Rigid discharge electrodeFlat-plate Discharge Electrodes (Contd.)Discharge electrodes are typically supportedfrom the upper discharge frame and are heldin alignment between the upper and lowerdischarge frames. The upper dischargeframe is in turn supported from the roof of , 12.

5 September 2013Fu incorporated into the support system. Inweighted wire systems, the dischargeelectrodes are held taut by weights at thelower end of the ElectrodesCollecting plates are designed to receive andretain the precipitated particles until they areintentionally removed into the plates are also part of theelectrical power circuit of the baffles shield the precipitated particlesfrom the gas flow while smooth , 12. September 2013Fu are suspended from the precipitatorcasing and form the gas passages within plates are connected at or nearthe center by rapper beams which serves asan impact point for rapping system.

6 Top,center or bottom spacer bars may be used tokeep the plates aligned for maintainingelectrical clearances to the and Rapping MechanismCollecting plate rapping must remove thebulk of the precipitated dust. The collectingplates are supported from anvil beams ordirectly with hooks from the precipitatorcasing. With anvil beam support, the impactof the rapping system is directed into thebeams located at the leading and/or , 12. September 2013Fu support, the impact is directed into therapper beams located at or near the center ofthe top of the collecting plates.

7 The rapping iscarried out in a regular programmed intervalsand guaranteed removal of deposited dustfrom the electrodes to the rappers Magnetic-Impulse rappersHoppersPrecipitator hoppers are designed tocompletely discharge their dust load ondemand. Usually the hoppers are rectangularin cross section with sides of at least 60 Degslope. They are insulated from neck abovethedischargeflangewiththeinsulation Donnerstag, 12. September 2013Fu zeilentext11thedischargeflangewiththeins ulationcovering the entire hopper area.

8 Lower partof the hopper (usually 1/3 to of height) isheated to avoid caking of ash and to ensurefree of electrostatic Precipitators Tubular precipitators are generally used forcollecting mists or fogs, and are mostcommonly used when collecting particles thatare wet or sticky. Tubular ESPs have beenused to control particulate emissions fromsulfuric acid plants, coke oven byproduct gascleaning (tar removal), and iron and steelsinterplantsDonnerstag, 12. September 2013Fu zeilentext12sinterplants Plate electrostatic precipitators primarilycollect dry particles and are used more oftenthan tubular precipitators.

9 Plate ESPs canhave wire, rigid-frame, or occasionally, platedischarge PrecipitatorsPlate PrecipitatorsTypes of electrostatic Precipitators (Contd.)Cold side ESPs is used where: Volume of flue gas that is handled is less Cost involvement is less. Overall size of the unit is smaller Used to remove fly ash from boilers thatburn high sulfur coalDonnerstag, 12. September 2013Fu zeilentext13 Hot side ESPs is used where: In high-temperature applications (Cementkiln) The gas volume treated in the ESP islarger The overall size of the PRECIPITATOR is largermaking it more costly Structural and mechanical problems occurin the PRECIPITATOR shellCold side ESPs Hot side ESPs Types of electrostatic Precipitators (Contd.)

10 Wet side ESPs is used where: Wet ESPs are used for industrialapplications where the potential for explosionis high . When dust is very sticky, corrosive, or hasvery high resistivity. ItdoesnothaveproblemswithrappingreDonner stag, 12. September 2013Fu zeilentext14 Itdoesnothaveproblemswithrappingreentrai nment or with back side ESPs is used where: Particles are charged and collected in adry state . Dust particles collected are removed byrapping. Used in steel furnaces, cement kilns andfossil-fuel-fired side ESPs Dry side ESPs Principles of ESP OperationElectrostatic precipitation removes particles fromthe exhaust gas stream of an industrial the process involves combustion, but it canbe any industrial process that would otherwise emitparticles to the atmosphere.