Subject :- Environmental Engineering II

Topic :- Municipal Solid Waste Management

Difficulty :- Medium

Gravitational settling chamber:

• Used to remove particles with size greater than 50µm.
• Velocity of fuel gas reduced in large chamber.
• Particles settle under gravitational force.

Advantages: Low initial cost, easy to design, low pressure drop, low maintenance cost.

Disadvantages: Require large space, less collection efficiency etc.

Cyclone separator :

• Centrifugal force is utilized to separate the particulate matter.

• It can remove 10 to 50 µm particle size.

• Used mostly in industries.

Advantages : Low initial cost, less floor area require, can handle large volume of gas at high temp, simple construction and maintenance.

Disadvantages: Require large head room, less efficiency for small particles (<10 µm). Sensitive to variable dust load & flow rate.

Electrostatic precipitator :

• Works on principle of electrical charging of particulate matter (-ve) and collecting it in a +ve charged surface.
• 99% efficiency
• Can remove particle size range of 0.1to 1 µm

Advantages: - High collection efficiency, particles may be collected dry or wet - Can be operated at high temp (300-450 C).

Disadvantages: - High initial cost, require high voltage, collection efficiency reduce with time. - Space requirement is more.

Fabric filter:

• Fuel gas is allowed to pass through a woven fabric which filters out particulate matter.
• Small particles are retained on the fabric.
• Remove particles up to 1 µm, its efficiency up to 99%.

Advantages: - High collection efficiency for smaller than 10 µm particle size. - Performance decrease becomes visible giving pre-warning. - Normal power consumption.

Disadvantages: - High temp gases need to be cooled - High maintenance and fabric replacement cost. - Large size equipment. - Fabric is liable to chemical attack.