Particulate control techniques Gravity settling chamber Mechanical collectors Particulate wet scrubbers Electrostatic precipitators Fabric filters

Gravitational Settling chambers Settling chamber: –Useful for large particulates (> 50  m) –Often in conjunction with a filter or precipitator to reduce overall system and operation costs (pre-collector) –May also contain baffles to serve as impingement devices –Low overall pressure drop and efficiency

GSC Very low terminal air velocity The velocity of a falling particle when the gravitational force downward is balanced by the air resistance (or drag) force upward Efficiency < 50 %

Cyclone separators use the inertia of the particles for collection The particulate- laden gas stream is forced to spin in a cyclonic manner.

More efficient than gravity settling chambers under heavier loads in Particle range: mm Efficiency requires cut diameter, dc, at which 50% of the particles with diameter dc can be removed.

Efficiency improvement if you want to increase the efficiency of a cyclone you can: reduce the cyclone diameter, reduce the outlet diameter, reduce the cone angle, or increase the body length.

Efficiency improvement However, if you want to increase the capacity of a cyclone, you can: increase the cyclone diameter, increase the inlet diameter, increase the outlet diameter, or increase the body length.

Efficiency improvement Increasing the pressure drop will also result in: an increase in separation efficiency higher capacity decrease the underflow to throughput ratio more concentrated underflow cleaner overflow.

Wet Scrubbers

Fabric Filters Filters can be made of a variety of natural and synthetic materials, such as cloth, glass fiber and paper. Particles in the gas stream are removed by interception and interaction with fibers in the filter media; once particle attaches to the fiber it effectively increases the fiber size and collection ability Common to monitor pressure drop across filter and change filter media at pre-determined value

ESP