Process for removing HCl, HF, SO3, SO2 and oxides of nitrogen from combustion exhaust gases by a simultaneous wet scrubbing

摘要

It is known to clean SO2 and NOx out of combustion exhaust gases by use of a wet circulation scrubbing, the scrubbing water of which contains ironII-EDTA or ironII-NTA complex. To keep the ironII complex within the scrubbing solution, reducing agents are added or scrubbing water treatments are carried out in the by-pass in order to reduce the iron oxidized by atmospheric oxygen from ironII to ironIII in the chelate complex and thus to minimize the use of expensive reducing agents. In order to further improve this process technically and economically, and in particular to reduce the consumption of reducing agent, according to the invention it is proposed that a water having the following constituents 1.) ironII-EDTA or NTA complex = 3-60g/l, preferably = 30-50g/l 2.) sodium formate = 3-150g/l, preferably = 30-50g/l 3.) sulphite or hydrogen sulphite (alkali metal sulphites) = 1.50g/l, preferably = 10-20g/l 4.) sulphate (alkali metal sulphate) = 5-90g/l, preferably = 30-60g/l 5.) glycol, preferably ethylene glycol = 5-30g/l, preferably = 18g/l is used, in order thereby to impinge the scrubber (1) via the scrubbing water pipe (4). IMAGE