Removal method of organic pollutants in fly ash

摘要

Recycling of fly ash is effected as a function of special combustion conditions in which additional organic pollutants such as polychlorinated dibenzo dioxine (PCDD) and polychlorinated dibenzo furane (PCDF) and/or their precursor compounds arise. Fly ash recycling is undertaken in accordance with values measured from the flue gas using on-line analysis. These values are influenced by the combustion process. Recycling occupies a set interval of 10 minutes to 6 hours, once special combustion conditions are established. The duration is a function of the measured values. Fly ash is recycled into the high temperature region; when using a grate-firing process, recycling is directed into the main combustion zone of the bed. Recycling is carried out after establishing the special combustion conditions. It takes place during or after boiler cleaning by beating, brushing or soot-blowing. Additional fly ash is recycled from a flue gas cleaning plant following the steam generator.