Reverse air
In reverse-air bag filters, the filter bags are fastened onto a cell plate at the bottom of the bag filters and suspended from an adjustable hanger frame at the top. Dirty gas flow normally enters the bag filters and passes through the filter bag from the inside, and the dust collects on the inside of the bags.
Reverse-air bag filters are compartmentalized to allow continuous operation. Before a cleaning cycle begins, filtration is stopped in the compartment to be cleaned. Bags are cleaned by injecting clean air into the dust collector in a reverse direction, which pressurizes the compartment. The pressure makes the bags collapse partially, causing the dust cake to crack and fall into the hopper below. At the end of the cleaning cycle, reverse airflow is discontinued, and the compartment are returned to the main stream.
The flow of the dirty gas helps maintain the shape of the bag. However, to prevent total collapse and fabric chafing during the cleaning cycle, rigid rings are sewn into the bags at intervals.
Space requirements for a reverse-air bag filters are comparable to those of a shaker bag filters; however, maintenance needs are somewhat greater.
