Gas stream filtering system using filtered gas for reverse flow cleaning

Abstract

A fabric-filter baghouse using heated, filtered exhaust gas for reverse-flow cleaning of fabric filter bags. The baghouse includes a housing having an inlet chamber and an outlet chamber therein, a number of fabric filter bags mounted between the inlet chamber and the outlet chamber and an exhaust fan for drawing a stream of gases through the baghouse. The interior of the filter bags communicate with the outlet chamber and the exterior of the filter bags are disposed in the inlet chamber. The filter bags are constructed to prevent particulate from passing from the exterior to the interior of the filter bags, while allowing the gas stream to do so. Particulate which collects on the exterior of the filter bags is removed by passing a reverse flow of gases through the filter bags. One or more rotary valves are provided to direct a reverse flow of gases to one group of filter bags at a time. A reverse flow supply duct extends from the exhaust duct to the rotary valves to provide heated, filtered exhaust gases for reverse flow cleaning of the filter bags. In one embodiment, the reverse flow supply duct communicates with the inlet chamber to effect a continuous, trickle gas flow through the reverse flow supply duct. In another embodiment, a return duct extends to reverse flow supply duct back to the exhaust duct to effect a continuous gas flow through the reverse flow supply duct.