Dry absorption systems
In waste incineration-, wood incineration-, melting- and sintering plants originate flue gases, which have to be cleaned usually the limits of the german 17. BImSchV have to be observed. In dry absorption systems, usually conditioned dry absorption processes, the hot flue gases are cooled down to about 130 - 180 °C by injection of water. To absorb the acid pollutants fluoride, chloride and SOX highly reactiv lime products with or without sulfuric endowment are used.
Heavy metals, especially mercury, and organic pollutants like dioxines, furanes and organic hydrocarbons are separated by sulfuric endowed clay minerals or/and endowed activated carbons. Such adsorbents, called Walhalla-Dioxorb® or Walhalla-Dioxorb®-AK, are especially produced for each plant and flue gas cleaning system.
Dioxorb®-products produced from lime products, sulfides and clay minerals or activated carbons form a very effectiv filter coating at the fabric, which has to be passed by the flue gases. In this way exists a very close contact between the mixed adsorbents and the pollutants. They become absorbed by the lime and adsorbed by the clay or the activated carbon. While the cleaned flue gases leave the plant, the mixed adsorbents alternativly is pulsed down from the fabric. Pulsing the fabric is controlled by Δp. To utilize the adsorbents it makes sense to recirculate most of the adsorbent and to complete a small part of fresh adsorbent.