Boiler/ Kiln-> Dust Collector-> Induced Draft Fan-> Absorption Tower-> Chimney<br />
The flue gas from the boiler or kiln enters the absorption tower after dust removal under the action of the induced draft fan. The absorption tower is a countercurrent spraying empty tower structure, which integrates the absorption and oxidation functions. The upper part is the absorption zone, the lower part is the oxidation zone, and the flue gas after dust removal is in reverse contact with the circulating slurry in the absorption tower. The system is generally equipped with 3-5 sets of slurry circulating pumps, and each circulating pump corresponds to an atomized spray layer. When only one unit is running or the load is low, 1-2 spray layers can be stopped. At this time, the system still maintains high liquid-gas ratio, thus achieving the required desulphurization effect. The secondary demister is installed in the upper part of the absorption zone, and the free water in the flue gas of the demister outlet is not more than 75mg/Nm3. The slurry after absorbing SO2 enters the circulating oxidation zone, in which calcium sulfite is oxidized into gypsum crystals by the blown-in air. At the same time, fresh limestone slurry is supplied from the absorbent preparation system to the absorption oxidation system to supplement the depleted limestone so as to make the absorbent slurry maintain at a certain pH value. When the reaction product slurry reaches a certain density, it is discharged into the desulphurization by-product system, and then dehydrated to form gypsum.