ANS:B - electrostatic precipitator

The most suitable equipment for removing fine dust particles (< 1 micron diameter) from air below its dew point is a wet scrubber.

Explanation:

• Wet Scrubber: A wet scrubber is an air pollution control device that uses a liquid (often water) to remove pollutants from air streams. Fine dust particles, including those smaller than 1 micron in diameter, can be effectively captured by wet scrubbers through mechanisms such as absorption, impaction, and condensation.
• Operation: In a wet scrubber:
  • Air laden with dust enters the scrubber and passes through a wetted surface or spray where the dust particles come into contact with water.
  • Fine particles adhere to the water droplets through condensation or absorption processes.
  • The dust-laden water is collected and treated separately, while the cleaned air is discharged.
• Advantages:
  • Effective for capturing fine particulate matter, including particles smaller than 1 micron, due to the intimate contact between particles and water.
  • Suitable for applications where air may be below its dew point, as the wet scrubbing process can handle moisture in the air stream.
• Other Options:
  • Bag Filter: Typically used for capturing larger particles and may not be as effective for very fine particles (< 1 micron) or for conditions where moisture is present.
  • Electrostatic Precipitator: Effective for removing larger particles and some smaller particles through electrostatic attraction, but may not be as efficient for particles < 1 micron or in moist air conditions.
  • Cyclone Separator: Primarily used for larger particles and may not effectively capture particles < 1 micron or handle conditions below the dew point.