Simultaneous scrubbing process for desulphurisation and simultaneous denitrification of flue gases downstream of refuse incinerators

摘要

It is known to control sodium-based or calcium-based flue gas desulphurisation plants with an EDTA complex via a scrubbing water solution in such a way that SO2 and NOx are scrubbed out simultaneously. The difficulty in this scrubbing process is that it is as a rule difficult to keep the Fe2 complex in the scrubbing solution stable. High oxygen values of, for example, 7% and more lead to enhanced oxidation of the Fe2 value and hence to a steep decrease in the separation of NOx. In order to eliminate these disadvantages, it is proposed according to the invention that magnesium salts in the form of magnesium chloride or magnesium sulphate are added to the iron chelate complex solution in the scrubbing liquid, whereby an oxidation of iron II to iron III by the oxygen content of the flue gases being scrubbed is attenuated. The addition of magnesium chloride and/or magnesium sulphate suppresses the solubility of sodium sulphate and promotes a precipitation with lime.