Apparatus for the cleaning of flue gases containing sulfur dioxide

Apparatus for the cleaning of flue gases containing ash and sulfur dioxide produced by burning sulfur-containing coal in the combustion chamber of a circulating fluidized-bed firing system by the addition of air at a temperature of 700° to 950° C., the apparatus comprising:

• means for delivering a particulate SO2 sorbent into the combustion chamber, a portion of the SO2 sorbent and SO2 producing a reaction product, a portion of the SO2 sorbent remaining unreacted;
• a mixing unit;
• means for feeding a mixture comprising a portion of the ash, a portion of the reaction product, and a portion of the unreacted SO2 sorbent from the combustion chamber to the mixing unit;
• means for supplying water or an aqueous sodium-containing solution to the mixing unit, the water or aqueous sodium-containing solution mixing together with the mixture of ash, reaction product, and unreacted SO2 sorbent at a reaction temperature of 600 to 100° and at atmospheric pressure, whereby the unreacted SO2 sorbent is converted into a hydration product;
• and
• means for returning the ash, the reaction product, and the hydration product from the mixing unit into the combustion chamber;
• wherein in the combustion chamber the hydration product is reactivated into an SO2 sorbent at a combustion temperature of 700° to 950° C.