Air pollution control system
Gases containing SO/sub 2/ from a furnace are contacted in the scrubbing zone of a scrubber with an aqueous scrubbing medium containing solid alkaline earth metal carbonate, seed crystals of alkaline earth metal sulfate and dissolved alkaline earth metal carbonate and sulfate and having a pH of from 6.0 to 6.5. The SO/sub 2/ reacts to form sulfites and bisulfites. The scrubbing medium is then withdrawn from the scrubbing zone and discharged to a reaction tank. Air is blown through the scrubbing medium in the reaction tank and then up into and through the scrubber and scrubbing zone. The oxygen reacts with sulfite to form sulfate in both the reaction tank and the scrubbing zone. The amount of oxygen is controlled so that the pH in the scrubber will not drop below about 4.5 and so as to oxidize not more than about 30 to 50% of the sulfite. Fresh additives, in the form of alkaline earth metal carbonate or alkaline earth metal oxide which has been formed by calcining alkaline earth metal carbonate in the furnace, are also introduced into the reaction tank and the pH returned to 6.0 to 6.5. A portion of the medium from the reaction tank is returned to the scrubbing zone and the remainder is further treated with oxygen to convert the remaining sulfite to sulfate which is precipitated and separated from the liquid. The liquid is then returned to the scrubbing cycle. 7 claims, 3 drawing figures.
- Assignee:
- Combustion Engineering, Inc.
- Patent Number(s):
- US 3980756
- OSTI ID:
- 7227973
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400105* -- Separation Procedures
500200 -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
AIR POLLUTION CONTROL
ALKALINE EARTH METAL COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
DESULFURIZATION
GASEOUS WASTES
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PH VALUE
POLLUTION CONTROL
REMOVAL
SULFUR COMPOUNDS
SULFUR DIOXIDE
SULFUR OXIDES
WASTES