Process and apparatus for removing sulfur from stack gases in the form of elemental sulfur

摘要

Process and apparatus for removing sulfur dioxide from gases such as stack gases. The gases are scrubbed with an alkali metal compound in an aqueous solution to form alkali metal sulfite/sulfate salts which are then reacted with barium sulfide to precipitate barium sulfite/sulfate and form alkali metal sulfide/bisulfide in solution. The alkali metal sulfide/bisulfide is oxidized to form elemental sulfur and regenerated wash liquid; and the barium sulfite/sulfate is reduced by roasting to form the barium sulfide required. In a preferable embodiment, coal is used as both the reductant and fuel in the roasting of the barium sulfite/sulfate and the stack gases from the roasting are scrubbed along with the primary stack gases. As an optional step a portion of the alkali metal sulfite salts may be oxidized to sulfate prior to reaction with barium sulfide.