Process for controlling sulfur oxides in coal gasification

Claim 1

In the gasification of carbonaceous solids with steam to give product gas containing carbon monoxide and hydrogen wherein the gasification is effected by feeding a stream of said solids and steam into a gasification reaction zone and wherein there is produced in conjunction with said gasification a sulfur dioxide containing flue gas formed in a combustion zone in which recycle solids are heated to provide the thermal requirements of the gasification reaction zone, the improvement of removing the sulfur dioxide from said flue gas comprising the steps of: (1) contacting said flue gas with at least a portion of said stream of carbonaceous solids so as to adsorb said sulfur dioxide thereon and produce carbonaceous solids charged with sulfur dioxide and purified flue gas; (2) venting the purified flue gas; (3) introducing the so charged carbonaceous solids into said gasification reaction zone whereby the adsorbed sulfur dioxide is reduced to free hydrogen sulfide whereby there is formed a gaseous mixture of said hydrogen sulfide with product gas; (4) introducing said gaseous mixture into a separation zone wherein the hydrogen sulfide is removed from said gaseous mixture; and (5) recovering said product gas substantially free of sulfur.