Bag house filters in waste processing

A compressed air cleaned bag house filter is a highly efficient dry filter system to purify air from suspended solids. In the waste processing industry, for example, bag house filters are used to clean flue gases. Often a reagent such as lime, sodium bicarbonate or active carbon is added to the bag house filter. These substances adsorb or neutralize the harmful substances, then they are collected together in the bag house, thanks to micro-perforated textile in the form of cylindrical bags supported by metal cages. The cages are attached to the filter housing and can be changed at the top of the filter on the clean side. The design of the installation (round or rectangular) allows the treatment of a wide range of pollutants and air volumes.

The aerodynamic filter inlet consists of a pre-chamber, which reduces the air velocity by widening and thereby minimizes bag wear. A series of plates ensures that the larger coarse dust particles are separated immediately. Depending on the degree of contamination and particle size, a cyclone can also be used as a pre-separator. The air flow is distributed over the entire filter element surface and crosses it from outside to inside. Once filtered and cleaned, the air is transported to the filter outlet. The dust deposited on the external surface of the filter elements produces a uniform layer of dust that improves filtration efficiency. In order to achieve extra low dust emissions, the filter bags can be additionally equipped with a HEPA (H13) absolute filter. A bag house filter in the waste processing industry is therefore assembled and configured according to customer specific requirements.

The pressure drop will gradually increase due to the contamination, a sensor measures the differential pressure over the filter elements and controls the filter cleaning system. This periodic cleaning of the filter elements is done by a strong compressed air pulse, this way the differential pressure stays within the selected limits. This compressed air pulse cleaning system blows the bags clean from the inside out. As a result, less compressed air is consumed and the bags will last longer.

The waste material is separated from the filter element surface and falls by gravity to the bottom of the filter funnel where it is collected in a bin, which is emptied periodically. Depending on the application, the hopper at the bottom of the filter can be equipped with a rotating sluice to continuously discharge the powder and collect it in a big-bag, for example. It is also possible to use a screw conveyor to continuously discharge the dust into a container.

An Air Solutions bag house filter is equipped with a high filter surface, is compact, easy to install, move and transport. Because in the waste processing industry a lot of work is done with explosive substances, our bag house filters are also available in an ATEX version. The installation is then equipped with additional earthing lugs, anti-static filter bags, non-return valve, explosion venting panel and optionally a flame arrestor. It is also possible to equip the filters with an explosion suppression system. Explosion suppression is an active system that works with optical and pressure sensors, a control box and extinguishing units. In many cases where passive explosion protection does not succeed, this is possible with the HRD system. The HRD system can be used for explosion suppression and as an explosion barrier.

The complete housing of the filter can be executed in :

- Steel coated in the desired RAL colour

- Galvanized steel

- Stainless steel - AISI 304

- Stainless steel - AISI 316

Air Solutions Holland engineers, builds, assembles and carries out maintenance on bag filter installations in the waste processing industry varying in size from 2.000 to 200.000 m3/h. Besides bag house filters, Air Solutions Holland also offers compressed air cleanable cartridge filters and static filters: