Prepared by:- Gaurav

ELECTROSTATIC PRECIPITATOR

Electrostatic precipitator (ESP)- PRINCIPLE :- An electrostatic precipitator (ESP) is a device that removes dust particles from a flowing gas (such as air) using force of an induced electrostatic attraction (i.e. like charges repel; unlike charges attract)

Electrostatic precipitators are highly efficient filtration devices that allow flow of gases through device, and can easily remove fine particulate matter such as dust and smoke from air stream.

environment protection has become a crucial problem and the authorities are requested to set increasingly more stringent limits , one of which is the emissions from the industrial plants of solid particulate and other gaseous pollutants.

ELECTROSTATIC PRECIPITATOR

HOW IT WORKS!!

SCHEMATIC OF WIRE-PLATE ESP

Schematic of wire-plate electrostatic precipitator

Components used in electrostatic precipitator

Electrodes

440V 50HZ 3φ AC supply

High voltage transformer

Rectifier

insulators

Hooper

20 – 80 KV DC

Basic diagram of an electrostatic precipitator

AC supply

Control cabinet High voltagetransformer

Rectifier Dust gas

Clean gas

Hooper

Discharge electrode

Collectorelectrode

Control cabinetControl cabinet is used to interconnect the 3φ ac supply and transformer through cables

Transformer

Transformer is used to step up or step down voltage asper design of Electrostatic precipitator.

Rectifier

Rectifier is used to convert ac supply into dc supply.

HooperHooper is used to store dust particles and ash content coming out from the Electrostatic precipitator.

Electrodes : -Based on DC current flow terminals electrodes can be divided as below:-

Discharge electrode :-

Electrodes wire which carries negatively charged high voltage (between 20 to 80KV) act as discharge or emitting electrodes.

Collector electrode :-

Electrode plate / wire which carries positively charged high voltage act as Collecting electrodes.

Collector electrodes

Discharge electrode

Processes of electrostatic precipitator are in three main stages:

particle charging,

transport

collection.

Main process of ESP

MECHANISM OF ESP

Mechanism of electrostatic precipitator

WORKING OF ELECTROSTATIC PRECIPITATOR

Several things happen very rapidly (in a matter of a millisecond) in the small area around the discharge electrode. Electric field is emerged due to dc terminalarrangement. The applied (-) voltage in discharge electrode is increased until it produces a corona discharge, which can be seen as a luminous blue glow around discharge Electrode.

Due to the formation of corona discharge, free electrons are emitted with high velocity from discharge electrode.

Stage - 1

This fast moving free electrons strikes gas molecule thus emission of free electron from gas molecules takes place.

The positive ion molecule move towards discharge electrode by electrostatic attraction

As a result with gas molecule more free electrons are emitted near the discharge electrode.

Stage - 2As electrons leave strong electrical field area around discharge electrode, they start slowing down. This free electron again strikes gas molecule but this time they are captured by gas molecule and become negatively charged ion.

As gas molecule are negatively ionized they move towards (+) electrode (i.e. collector electrode).

This negative gas ion fills space of Dust particle and becoming negatively charged particle.

This particle are captured by collector electrode using electrostatic attraction.