Electrostatic Precipitators use electrostatic forces to separate dust particles from exhaust gases. A number of high-voltage, direct-current discharge electrodes are placed between grounded collecting electrodes. The contaminated gases flow through the passage formed by the discharge and collecting electrodes.

The airborne particles receive a negative charge as they pass through the ionized field between the electrodes. These charged particles are then attracted to a grounded or positively charged electrode and adhere to it.

The collected material on the electrodes is removed by rapping or vibrating the collecting electrodes either continuously or at a predetermined interval. Cleaning a precipitator can usually be done without interrupting the airflow.

The four main components of all electrostatic precipitators are:

• Power supply unit, to provide high-voltage, unidirectional current
• Ionizing section, to impart a charge to particulates int he gas stream
• A means of removing the collected particulates
• A housing to enclose the precipitator zone

The following factors affect the efficiency of electrostatic precipitators:

• Larger collection-surface areas and lower gas-flow rates increase efficiency because of the increased time available for electrical activity to treat the dust particles.
• An increase in the dust-particle migration velocity to the collecting electrodes increases efficiency. The migration velocity can be increased by-
  • Decreasing the gas viscosity
  • Increasing the gas temperature
  • Increasing the voltage field