NOx scrubbing downstream of flue gas desulphurisation plants

摘要

It is known to use simultaneous SO2 and NOx scrubbing plants downstream of flue gas desulphurisation plants. In order to carry out, independently of the SO2 content in the untreated gas, the separation out of NOx, according to the invention it is proposed that, in a first scrubbing stage (2), preferably using a weakly acidic short-time scrubbing process, alkali metal bisulphite or alkaline earth metal bisulphite is prepared, for example calcium bisulphite or sodium bisulphite etc., this bisulphite formed being added to the NOx scrubbing (4) alone or also to the simultaneous scrubbing stage (3), which simultaneously scrubs SO2 and NOx, a polycarboxylic acid (EDTA included) and/or phosphonic acid being added to this scrubbing stage. <IMAGE>