Question

What is the overall efficiency for the removal with the fabric filter for a distribution of particles where 0.05% of the particles are of 0.1 microns diameter, 0.2% of particles are of 0.3 microns diameter, 2.8% of the particles are 0.7 microns and remaining particles are in the particle diameter range of 1 to 50 microns.

	A.	99%
	B.	92%
	C.	37%
	D.	89%

Answer 1

Fabric filter unit consists one or more isolated compartments containing rows of Fabric filter bags or tubes. Particle-laden gas passes up along the surface of the bags, then radially through the fabric. Particles are retained on the upstream face of the bags while the cleaned gas stream is vented to the atmosphere. The filter is operated cyclically, alternating between relatively long periods of filtering and short periods of cleaning. During cleaning, dust that has accumulated on the bags is removed from the fabric surface and deposited in a hopper for subsequent disposal.

Fabric filters will collect particle sizes ranging from sub-micron to several hundred microns in diameter at efficiencies generally in excess of 99 or 99.9 percent.

(Sub-micron is the size less than a micron)

Since in the question particles sizes ranges in between sub-micron to hundred microns , the overall removal efficiency is 99%