Regeneration of calcium oxide or calcium carbonate from waste calcium sulphide
OwnerEdward J. Anthony, Kuanrong Qiuinventors
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Abstract
An alternative process whereby the calcium sulphide formed in an IGCC system from calcium oxide and/or calcium carbonate can be safely and more or less quantitatively converted by reaction with carbon dioxide to calcium carbonate and/or calcium oxide together with sulphur dioxide. The calcium oxide and/or calcium carbonate can be reused in the IGCC system, and the sulphur dioxide can be converted to a useful product, such as sulphuric acid. One result of this process is that since the furnace ashes do not contain a significant level of calcium sulphide, they can be safely disposed of in a land fill site.
Claims8
A process for removing sulphide compounds from an exhaust gas flow from a first gasifier furnace in which a carbon containing fuel is consumed under reducing conditions, which process comprises:
- (a) providing in the furnace fuel an amount of limestone or calcium oxide sufficient to trap the sulphide compounds in the gas flow as calcium sulphide;
- (b) recovering the calcium sulphide as part of a first ash product from the furnace;
- (c) reacting the first ash product in a second furnace with sufficient carbon dioxide at a partial pressure and at a temperature sufficient to convert the calcium sulphide in the ash product to calcium carbonate and/or calcium oxide and to provide a gas flow containing sulphur dioxide;
- (d) recovering the sulphur dioxide;
- and
- (e) recovering a substantially calcium sulphide free second ash product.
Dependencies are inferred from the claim text.