SO2 and/or SO2 and NOx scrubber with upstream calcium chloride recovery

摘要

It is known to scrub out SO2 from the dirty gas stream downstream of fossil-fuelled combustion plants by means of an aqueous solution which is enriched with lime. The aim is to free from gaseous pollutants the dirty gas loaded with SO2 and NOx and other acidic constituents and to achieve gypsum as an end product. In order to create a waste water-free process of the abovementioned type, according to the invention it is proposed that the scrubbing water which is used for gypsum scrubbing is collected and fed to a spraying and quenching absorber stage upstream of the flue gas desulphurisation scrubbing plant. The gypsum is scrubbed in a centrifuge or vacuum filter in such a way that it complies with the specification of low chloride-containing constituents. In the spraying and quench absorber stage, the flue gas at an acidic pH is brought down from for example 140 DEG to 100 DEG C, the chloride-containing gases, by means of the wash water from the gypsum scrubbing station, already also enriched with chloride, serving for scrubbing out the chloride-containing constituents in the gas with simultaneous flue gas cooling.