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Abstract

A process for cleaning flue gases containing ash and sulfur dioxide produced by burning sulfur-containing coal in the combustion chamber of a circulating fluidized-bed firing system includes delivering a particulate SO.sub.2 sorbent into the combustion chamber. A mixture including portions of the ash, the reaction product produced in the reaction of the SO.sub.2 sorbent with the sulfur dioxide, and unreacted SO.sub.2 sorbent is fed from the combustion chamber to a mixing unit. In the mixing unit, water or an aqueous sodium-containing solution is mixed with this mixture and the unreacted SO.sub.2 sorbent is converted into a hydration product (for example Ca(OH).sub.2) at a reaction temperature of 60.degree. to 100.degree. and at atmospheric pressure. The ash, the reaction product, and the hydration product is returned from the mixing unit into the combustion chamber, and the hydration product is reactivated to an SO.sub.2 sorbent at a combustion-chamber temperature of 700.degree. to 950.degree. C.

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First Claim