Recovery of particulate matter from exhaust gas is vital for any industry from two aspects:
- To avoid pollution problems
- Recovery of finished product-increasing the plant yield
For recovering particulate matter different options available are - cyclones, venturi, scrubbers, bag air filter, pollution control bag filter, electrostatic precipitates etc. Out of these bag filter becomes the best choice if following are dominant selection criterias:
- Material is expensive and hence high collection efficiency is desired.
- Particulate size is very fine.
Material recovery in powder form is desirable & not in solution form.Working Principle of Bag Filter
- The dust-laden air enters the bag filter.
- The dust /powder separates inside the bag filter chamber.
- The air is uniformly distributed avoiding channelling while the powder is separated.
- Initially a coat of material forms on the bags. Subsequently, the coat acts as the filtering medium.
- The dust is accumulated on filter elements while the air passes through the filter bags from outside to inside.
- The accumulated powder is dislodged from the bags by reverse pulsejet air intermittently.
- The dislodged powder falls on bottom cone and is discharged through powder discharge valves.
- The dust free air is sucked by induced draft fan and is exhausted to atmosphere.