Filter Bags: Reverse Air Baghouse

Reverse air baghouses are typically found in medium to large airflow processes such as cement kilns and steel furnaces. Air to cloth ratios are low (1-2 ft/min) and the collectors are compartmentalized to allow off-line cleaning of the filter bags. Normally a compartment is taken off-line, the flow is reversed to crack the filter cake which causes it to drop down into the hopper below. Dust evacuation is handled by screw conveyor, rotary airlock or slide gates.

Many reverse air bags are characterized by anti-collapse rings sewn onto the bag body to prevent the bag from collapsing when the flow is reversed. The majority of reverse air bags are 5”, 8” or 11 ½”dia and may be as long as 35’-40’ overall. These bags are installed under tension to minimize movement. Sonic horns may also be used to assist dust release.

Normally, reverse air bags are made from woven fabrics including fiberglass, but felts are also used with cake release surfaces and chemical treatments. Felts offer greater flow at comparable efficiencies or higher efficiencies at comparable flows.