Patent ID: 6912962

Claim:
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 SO 2 sorbent into the combustion chamber, a portion of the SO 2 sorbent and SO 2 producing a reaction product, a portion of the SO 2 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 SO 2 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 SO 2 sorbent at a reaction temperature of 60° to 100° and at atmospheric pressure, whereby the unreacted SO 2 sorbent is converted into a hydration product; means for returning the ash, the reaction product, and the hydration product from the mixing unit into the combustion chamber; and means for regulating the reaction temperature of the mixing unit; wherein in the combustion chamber the hydration product is reactivated into an SO 2 sorbent at a combustion temperature of 700° to 950° C.