Variations of Fabric Filters
Fabric filters are devices for air pollution control which help to clear air or gases of particulate matter by trapping the particulate matter on the fabric and the clean air goes through the fabric. Filtration is the technique employed in the this particular technology of air pollution control since the fabric filters the air or gases leaving the particles on the fabric and the air or gas passing through it. This technique of air and gas pollution control is mostly applied in the type of industries that emit fumes and smoke which could contain harmful particulate matter. The industrial requirements of the fabric filters will vary due to a number of factors such the quantity of the fumes and smoke generated by a particular industry hence whereas some industries will require tiny and simple fabric filters, others might require bulky fabric filters. A typical baghouse consists of an inlet which allows the dirty gas into the filter system and an outlet which allows the filtered gas out, an opening at the bottom which drops the collected particles and a tube that attaches to the fabric filters. The manner in which the fabric filters are cleaned or cleared of the particles is the basis of classification of the house bags. This classification of the fabric filters according to the dirt removal mechanism from the surface of the filter fabric yield three types of fabric filters namely, reverse air housebags, shaker housebags, and pulse jet housebags. In reverse air housebags, the bags are suspended, from a hanger at the top which is freely adjustable and the dirty gas enters the bag through the inlet and exits through an outlet from the inside hence the particles or dirt is left on the inside of the housebags. They are referred to as reverse air because for cleaning purposes, the cleaning air is blown into the fabric filter in a reverse direction which leads to the collapsing of the housebags which automatically forces the dirt which had collected at the surface to crack and fall off. Before this cleaning cycle is begun, the filtration process is first stopped vin the housebags to be cleaned and after the cleaning process the reverse air flow is stopped and the system gets back to normal. The shakers type of housebags allow for the removal if the collected dirt by shaking and for this cleaning mechanism to occur the filtration process is first stopped. Pulse durations of compressed air are utilized in the pulse jet housebags hence the name.