Development of a Molten Carbonate Process for Removal of Sulfur Dioxide from Power Plant Stack Gases. Part II. Process Chemistry - Regeneration

摘要

The regeneration of sulfide-bearing melts with carbon dioxide and water vapor was studied. The regeneration reaction, M2S(l) + CO2(g) + H2O(g) = M2CO3(l) + H2S(g) could be carried to completion at 500C in a batch process within practical time limites (20 to 30 min.). The time required to complete the reaction was found to be limited by the imput gas flow rate to melt volume ratio and the effective equilibrium constant for the regeneration reaction. Foreign metal impurities (Fe, V, Mo, sn, Ge) in the melt reduced the sulfide activity in varying amounts causing a reduction in the hydrogen sulfide content in the off-gas stream. The decrease in the effective equilibrium constant for the regeneration process with increase in carbon dioxide pressure was postulated to be due to the interaction of carbon dioxide with sulfide to form a series of thiocarbonates. Cycle tests showed that the sulfur can be removed completely and revealed no problems due to cycling on the quality of the carbonate melt. (Author)