INTRODUCTION TO ELECTROSTATIC PRECIPITATORS
Electrostatic precipitators (ESPs) are the most commonly used, effective, and reliable particulate control devices; they are employed mostly in power plants and other process industries. The particle-laden flue gas from the boiler flows through the ESP before it enters the environment. The ESP works as a cleaning device, using electrical forces to separate the dust particles from the flue gas. A typical ESP consists of an inlet diffuser known as an inlet evase, a rectangular collection chamber, and an outlet convergent duct known as an outlet evase. Perforated plates are placed inside the inlet and the outlet evase for the purpose of flow distribution. Inside the collection chamber there are a number of discharge electrodes (DEs) and collection electrodes (CEs). A set of discharge electrodes is suspended vertically between two collection electrodes in a typical wire-plate ESP channel. While the flue gas flows through the collection area, electrostatic precipitators accomplish particle separation through the use of an electric field in the following three steps. The electrical field does the following:
Imparts a positive or negative charge to the particles by means of discharge electrodes
Attracts the charged particles to oppositely charged or grounded collection electrodes
Removes the collected particles by vibrating or rapping the collection electrodes or spraying them with liquid