- Electrostatic Precipitator Definition: An electrostatic precipitator is a device that removes pollution-causing particles from a gas using an electrostatic charge.
- Types of Electrostatic Precipitators: There are two main types: dry and wet electrostatic precipitators.
- Dry Electrostatic Precipitator: Collects dry particles by charging them and trapping them on oppositely charged electrodes.
- Wet Electrostatic Precipitator: Collects wet particles by charging them and using continuously sprayed liquid collectors to form sludge.
- Applications: Used in thermal power plants and industrial settings to clean air and reduce pollution.
The world is slowly but continually moving towards a greener future. There is much excitement among engineers about the prospects of greener technology. However, coal-based power plants are still the primary source of electrical power in many countries. Baring few countries in the world like Norway or Iceland, all other countries depend heavily on coal to produce the bulk of the electricity demand. Coal necessitates that we use some technology to reduce the pollution that is caused by such power plants. Electrostatic precipitator does exactly that. Electrostatic precipitator uses an electrostatic field to remove pollution causing particles from a flowing gas such as air. They are one of the best filtration devices and can remove fine particulate matter such as dust and smoke from the air stream. They have now become mandatory in a thermal power plant.
Particles in the air are charged by ionization and then made to flow between charged electrodes. The particles and electrodes have opposite charges, causing the pollutant particles to be attracted to the electrode plates, where they are collected. Clean air moves out of the electrostatic precipitator, and the pollutants are separately collected in a hopper by hammering the plates.
There are different types of electrostatic precipitators, and we will study each of them one by one:
Dry Electrostatic Precipitator
This type collects pollutants like ash or cement in a dry state. It collects dust particles from the air stream by first ionizing them to make them electrically charged. These charged particles then flow through oppositely charged electrodes, where they are collected. The dust is gathered by hammering the electrodes and collected in a hopper for extraction. Dry electrostatic precipitators are used in thermal power plants to remove dirt from flue gases and in ventilation and air conditioning systems to clean the air.
Wet Electrostatic Precipitator
Wet electrostatic precipitators remove wet particles like resin, oil, paint, tar, and acid. They are used in industrial applications where there is a high risk of explosion and for particles with high resistivity or corrosiveness. In wet ESPs, particles are charged by passing through a corona, similar to dry ESPs. The main difference is in the collectors, which are continuously sprayed with liquid, usually water, forming sludge. This sludge is collected and treated separately. Wet ESPs are used for particles that dry ESPs can’t handle and are more efficient. The continuous or intermittent liquid washing prevents particle re-entrainment due to rapping, which can occur in dry ESPs.
