particulate control techniques gravity settling chamber mechanical collectors particulate wet...
TRANSCRIPT
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: 15 - 50 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 efficiencyhigher capacitydecrease the underflow to throughput ratiomore concentrated underflowcleaner 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