Process for scrubbing SO2 and NOx in a multi-stage scrubber having multiple scrubbing liquid discharge and oxidising and reducing scrubbing liquid vessels

摘要

It is known to separate out SO2 and NOx simultaneously in scrubbing apparatuses. For this purpose, alkalis and hydrated lime or limestone are added to the scrubbing liquid and EDTA is additionally added. In order to have to use the lowest possible chemical addition to maintain the iron chelate such as EDTA and a chemical addition to maintain the reducing phase, according to the invention it is proposed that, preferably in the case of flue gases having a relatively high NOx content and relatively low SO2 content, the gas (1) is first introduced into a scrubbing stage (2) and here, for simultaneous scrubbing of SO2 and NOx, is impinged with a reducing scrubbing liquid at (7), which transfers the discharging scrubbing liquid stream via a descending pipe (11) to the scrubbing liquid reservoir (6), and a scrubbing liquid stage (3) is situated downstream of the scrubbing liquid stage (2), which scrubbing liquid stage (3) preferably serves for scrubbing out SO2 and this scrubbing stage is provided with a scrubbing liquid reservoir vessel (5) which maintains the scrubbing water circulation with oxidising scrubbing liquid, via a pump, in the region (3) for SO2 scrubbing and the gas, which is partly freed from NOx and largely freed from SO2, is passed via a gas pipe (10) having a demister shielding to the scrubbing stage (4), in this scrubbing stage, according to the invention, a scrubbing liquid having reducing properties being produced, which [lacuna] the NOx scrubbing with the addition of limestone ... Original abstract incomplete. <IMAGE>