Dry flue gas cleaning (dry absorption, conditioned dry absorption)
In the process of dry flue gas cleaning, the flue gas, if necessary, is moistened and cooled upstream of the actual reaction stage. This is done, on the one hand, for protecting the filter (temperature) and, on the other hand (if lime is used), for moistening the flue gas up to the dew point range.
In order to bind the pollutants contained in the flue gas flow, such as hydrochloric acid (HCl), sulphur dioxide (SO2), organic pollutants (e.g., PCDD/-DF, PCB) as well as ecotoxic heavy metals (e.g., mercury), in the downstream reaction line sorbents, such as NaHCO3 or lime hydrates and hearth furnace cokes are a metered addition.
The reaction products are efficiently separated by means of a downstream filter and recirculated, if necessary.
Diagram of a conditioned 2-stage dry absorption:
Schema einer (kond.) Trockenabsorption mit NaHCO3: