Method for removing sulfur dioxide from a combustion exhaust gas
Abstract
Abstract A method for effectively removing sulfur dioxide in the form of calcium sulfite from a combustion exhaust gas, comprising the steps of (1) feeding a portion of the combustion exhaust gas to a dilute sulfuric acid solution to produce sulfurous acid in the solution and oxidizing the resultant sulfurous acid with use of air or oxygen in the presence of an oxidizing catalyst to produce sulfuric acid; (2) feeding a residue of the combustion exhaust gas and the gas exhausted from the step (1) to an alkali sulfite aqeuous solution to produce an alkali bisulfite aqueous solution; (3) mixing a major portion of the alkali bisulfite aqueous solution produced in the step (2) with slaked lime or limestone for reaction to give a calcium sulfite-containing reaction solution; (4) separating calcium sulfite from the reaction solution obtained in the step (3); and (5) circulating the filtrate of the step (4) to the step (2) and mixing a minor portion of the alkali bisulfite aqueous solution produced in the step (2) with sulfuric acid produced in the step (1) and with a portion of calcium sulfite separated in the step (4), thereby to convert an alkali sulfate, which is secondarily produced in the alkali bisfulfite aqueous solution, into gypsum.
Inventors
- 👤 Tomijiro Morita
- 👤 Isao Funahashi
Bibliographic Details
Claims Analysis
Total Claims: 7References Cited (Backward Citations)
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