METHOD AND ARRANGEMENT FOR THE PRODUCTION OF ALPHA CALCIUM SULFATE SEMI-HYDRATE USING THE FOSS OF WET SMOKE GAS DESULFURATION (REA)

摘要

The invention relates to a method and an arrangement for producing alpha -calcium sulphate hemihydrate using the gypsum suspension produced during the wet flue gas desulphurization process of a fossil-fired thermal power station. The aim of the invention is to carry out a continuous process of converting and further processing gypsum to produce highly pure end products which is directly linked to the flue gas desulphurization process of a coal-fired power station. To this end, a partial flow is removed from the gypsum suspension taken from the flue gas desulphurization process (1) before dehydration and the solid parts are separated into dihydrate and unwanted constituents by one or more hydrocyclones (5). The thus purified suspension is heated, then mixed with a dispersion of crystallizers and nucleators (11), guided via the outer pipe (13) of a longitudinal, upright double-pipe heat exchanger (14) and after being heated again, is released to an optionally coil-shaped reactor (19) which is located underneath which has mixing screws, using the hydrostatic pressure. The suspension is then delivered to the inner pipe (21) of the double-pipe heat exchanger (14). The resulting alpha -calcium sulphate hemihydrate suspension in this inner pipe (21) is caused to rise to the exit level (22) and then dehydrated, the resulting powder then being dried and screened or ground. The invention also relates to an arrangement for producing alpha -calcium sulphate-hemihydrate using the gypsum suspension produced in the wet flue gas desulphurization plant of a fossil-fired thermal power station.