Process for removing sulfur dioxide from flue gases

Patent · Tue Feb 26 00:00:00 EST 1991

OSTI ID:5543830

Stowe, Jr, D H; Benson, L B

This patent describes improvement in a process for removing sulfur dioxide from flue gases in a wet scrubber, wherein an aqueous slurry formed from calcium hydroxide and magnesium hydroxide is contacted in the wet scrubber with the flue gases, and the slurry, after the contact, contains calcium sulfite solids and dissolved magnesium sulfite, and is discharged from the wet scrubber and passed to a thickener wherein a thickened aqueous sludge containing calcium sulfite solids is separated from an overflow liquor. The improvement comprises: returning at least a portion of the overflow liquor to the wet scrubber; concentrating the thickened aqueous sludge by removal of a sulfite solution, comprising water containing dissolved magnesium sulfite, therefrom; returning a first portion of the sulfite solution to the thickener; oxidizing magnesium sulfite in a second portion of the sulfite solution to form a sulfate solution containing magnesium sulfate; adding lime to the sulfate solution following the oxidation, to precipitate calcium sulfate and form an aqueous magnesium hydroxide suspension; and separating precipitated calcium sulfate from the aqueous magnesium hydroxide suspension.

• Assignee: Dravo Lime Co., Pittsburgh, PA (USA)
• Patent Number(s): US 4996032; A
• Application Number: PPN: US 7-454271
• OSTI ID: 5543830
• Resource Relation: Patent File Date: 21 Dec 1989
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
20 FOSSIL-FUELED POWER PLANTS
54 ENVIRONMENTAL SCIENCES
FLUE GAS
SCRUBBING
SULFITES
OXIDATION
SULFUR DIOXIDE
REMOVAL
AIR POLLUTION CONTROL
CALCIUM HYDROXIDES
CALCIUM SULFATES
DESULFURIZATION
MAGNESIUM HYDROXIDES
MAGNESIUM SULFATES
PRECIPITATION
SCRUBBERS
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
CONTROL
EQUIPMENT
GASEOUS WASTES
HYDROGEN COMPOUNDS
HYDROXIDES
MAGNESIUM COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
POLLUTION CONTROL
POLLUTION CONTROL EQUIPMENT
SEPARATION PROCESSES
SULFATES
SULFUR COMPOUNDS
SULFUR OXIDES
WASTES
010800* - Coal
Lignite
& Peat- Waste Management
200202 - Fossil-Fueled Power Plants- Waste Management- Noxious Gas & Particulate Emissions
540120 - Environment
Atmospheric- Chemicals Monitoring & Transport- (1990-)