Bag Filters

Fabric filter bags are used to separate particle from the dust laden air in bag filter unit. They are one of the most efficient and cost effective types of dust collectors available and can achieve a collection efficiency of more than 99% for very fine particulates. Mechanical shaking Dust-laden gases enter the bag filter unit and pass through fabric bags that act as filters. The bags can be of woven or felted cotton, synthetic, or glass-fiber material in either a tube or envelope shape. The high efficiency of these collectors is due to the dust cake formed on the surfaces of the bags. The fabric primarily provides a surface on which dust particulates collect through the following four mechanisms: Inertial collection - Dust particles strike the fibers placed perpendicular to the gas-flow direction instead of changing direction with the gas stream. Interception - Particles that do not cross the fluid streamlines come in contact with fibers because of the fiber size. Brownian movement – Sub micrometre particles are diffused, increasing the probability of contact between the particles and collecting surfaces. Electrostatic forces - The presence of an electrostatic charge on the particles and the filter can increase dust capture.