Bag Filter - An Industrial Filter

Bag filter is an industrial filter that is used to collect particulate from the exhaust gas and unwanted particulates from liquid.. The recovery of particulate actually lessen the pollution problem and increases the plant yield. Although there are many other options of collecting particulates like Venturi, Cyclones, Electrostatic Precipitators but the bag filter is the best choice in the following circumstances

You want to recover the material in a powdered form rather than solution form

• Particulate size is very small
• Material is expensive

Filter bags for dry as well as liquid filtration are available. The filter bags are developed as per the specifications of the industry. For liquid filter bags the media can be multi-filament, monofilament or needle-felt. High viscous fluids are filtered through these and has less filtration problems.

Parts of Bag Filter

• Bag filter housing
• Filter bags
• Bag cages
• Filter bag-Venturi assembly
• Pulse-jet air cleaning assembly
• Air bleeding assembly

Bag filter housing size should be large to have more filtering area but you can always pick the size as per the requirement as it varies. More the area lower will be the CAN Velocity. This will not allow the powder to re-enter in the filters bags that will reduce the filter choking.
Pick the filter bag fabric as per the requirement of temperature, air-to-cloth ratio and pressure of the air. The fabric can be woven as well as non-woven.
Pick the fabric that has anti-stick coating on it to avoid choking.
 

Bag Filter Working
The dust loaded air enters into the bag filters and uniformly distributed all across except for the channeling. Any material form or particulate is then make the first coat over the filter bag making the filter medium. With the passing of air in and out the dust material gets accumulated on the filter bag layer. Then with the help of reverse pulse-jet air the accumulated dust is removed from the bag filter which then falls on the bottom cone and get out from the powder discharge valves. With the help of induced draft fan the dust free air is sucked in.

Disadvantages of Bag Filter

• Use of bag filter result in the frequent bag choking
• Higher plant shut down time and reduced plant capacity because of bag filter choking
• High blow electrical power because of higher drop in the pressure across the filter bag

Application of Filter Bags

• Auto Industry
• Water Treatment Plants
• Pharmaceutical Industry
• Petro-Chemical Industry
• Chemical Industry