Method for removing sulfur dioxide from a combustion exhaust gas
A method is described for removing sulfur dioxide in the form of calcium sulfite from a sulfur dioxide-containing combustion exhaust gas, comprising the steps of: feeding a portion of the combustion exhaust gas to a sulfuric acid solution to produce sulfurous acid in the solution and a gas exhaust and then oxidizing the sulfurous acid with air or oxygen in the presence of an oxidizing catalyst to produce sulfuric acid; feeding the remaining portion of the combustion exhaust gas and the gas exhausted to an aqueous solution of alkali sulfite to produce an aqueous solution of alkali bisulfite and alkali sulfate; mixing a major portion of the aqueous solution of alkali bisulfite produced with slaked lime or limestone for reaction to give a reaction solution containing calcium sulfite; and separating calcium sulfite from the reation solution obtained in step (3), the filtrate separated in step (4) being circulated to step (2), and the minor portion of the aqueous solution of alkali bisulfite produced in step (2) being mixed with sulfuric acid produced in step (1) and with a portion of calcium sulfite separated in step (4) thereby to convert the alkali sulfate, which is secondarily produced in the aqueous solution of alkali bisulfite, into gypsum.
- Assignee:
- Kureha Kagaku Kogyo Kabushiki Kaisha
- Patent Number(s):
- US 3935296
- OSTI ID:
- 7358195
- Resource Relation:
- Patent Priority Date: Priority date 10 Nov 1972, Japan
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
GASEOUS WASTES
WASTE PROCESSING
SULFUR DIOXIDE
REMOVAL
AIR POLLUTION
CHEMICAL REACTIONS
DESIGN
OPERATION
OXIDATION
POLLUTION CONTROL EQUIPMENT
CHALCOGENIDES
EQUIPMENT
MANAGEMENT
OXIDES
OXYGEN COMPOUNDS
POLLUTION
PROCESSING
SULFUR COMPOUNDS
SULFUR OXIDES
WASTE MANAGEMENT
WASTES
200202* - Fossil-Fueled Power Plants- Waste Management- Noxious Gas & Particulate Emissions
500200 - Environment
Atmospheric- Chemicals Monitoring & Transport- (-1989)
400105 - Separation Procedures