An electrostatic precipitator (ESP) is a device that removes particulate matter from exhaust gases using electrostatic forces. It is commonly used in industries such as power plants, cement factories and steel mills to control air pollution.

The basic principle of an ESP is to use an electric field to charge the solid particles in the gas stream, and then collect them on a charged surface.

1. The gas stream is first passed through a series of electrodes, which are typically made of metal wires or plates. These electrodes are charged with a high voltage, usually in the range of tens of thousands of volts.

2. As the gas stream passes through the electrodes, the solid particles in the gas become charged, either positively or negatively depending on the polarity of the electrodes. The charged particles are then attracted to an oppositely charged collection electrode, which is usually a flat metal plate or a series of plates.

3. As the particles collect on the collection electrode, they form a layer of solid deposits that can be removed periodically. This is done by rapping on the collection plates, which causes the solid deposits to fall into a hopper or other collection device.