Aqueous carbonate process design study. Final report

The Aqueous Carbonate Process (ACP) Design Study involved an experimental investigation of the regeneration subsystem of the Rockwell International Corporation Energy Systems Group closed cycle flue gas desulfurization process. The process involves a spray dryer in which the flue gas is scrubbed and its sulfur removed as a dry sodium sulfite/sulfate plus sodium carbonate mixture. This is followed by a regeneration process which involves the reduction of the sulfite/sulfate to sulfide in a molten salt bed. Then, using the CO/sub 2/ produced in the molten salt bed, the sulfide is stripped from an aqueous solution of the melt as H/sub 2/S which is oxidized to elemental sulfur in a Claus plant. The sodium salts are concurrently converted to a sodium carbonate solution which is recycled to the spray dryer as the absorbent solution. This program involved studies of the molten salt reduction step and the aqueous regeneration steps plus a corrosion study of the aqueous process liquors. A process flow diagram and a material balance were developed based on coal-reduction process data developed in the study. It was observed that the reduction process was more difficult to operate with coal than with coke. The greater ash content of the coalmore » and thus of the reducer melt, is a major factor in determining the operating temperature of the reducer, with the result that the coal-reduction required a bed temperature about 55/sup 0/C (100/sup 0/F) higher than that for coke-reduction. It is concluded that the ACP closed cycle process can operate effectively using coal as the reductant, although the use of coke offers more operational flexibility.« less