Fabric filters have been used in flue gas cleaning systems for over 15 years. They are mainly used to separate solid as well as, to a small extent, gaseous components. Fabric filters are positioned downstream of a spray absorber/spray dryer or a dry gas cleaning system such as lime injection.
A fabric filter system consists of several chambers in series, which are separated from each other by closing flaps. Fabric bags made of glass, mineral, metal as well as natural or artificial fibres are suspended in the chambers. The flue gas diffuses through the solid layer deposited on the fabric bag.
In this way, not only fine dusts, but also gaseous pollutants can be removed. This is achieved by injection of dry lime or by means of the unreacted lime proportion after a lime milk operated spray absorber.
Fabric filters have recently gained importance in connection with entrained-bed adsorption methods such as injection of hearth-furnace coke or activated carbon for removal of dioxin and vaporous heavy metals.