German scrubber yields gypsum, won't scale
The Saarberg--Holter process was developed as a joint venture between West Germany's second largest coal producer and a large engineering firm specializing in pollution control. Key to the process chemistry is the use of a clear scrubbing solution--not a slurry. Flue gas, with some of the particulate removed in a mechanical separator, is first passed through the absorption reaction vessel, called the ''rotopart.'' The active compounds in the scrubbing solution are calcium hydroxide, calcium formate, and calcium chloride. These compounds are formed by adding lime and formic acid to the solution. There is a sufficient amount of free chloride available in the flue gas from most coal types to provide enough for the reaction. If not, it can be added. These compounds all react with sulfur dioxide in the absorber to form soluble calcium bisulfite. The pH of the solution is 10.5 at the beginning of the absorber reaction and 4.0 at the end. The washing fluid then flows to the oxidizer, where air is bubbled through it. The calcium bisulfite is oxidized to form insoluble calcium sulfate dihydrate or gypsum. Addition of calcium hydroxide regenerates calcium formate and calcium chloride. The slurry containing 15% gypsum (by weight) is filtered to produce a cake containing 80% solids (95% of which is gypsum.) The clean filtrate is recycled.
- OSTI ID:
- 6765348
- Journal Information:
- Electr. Light Power (Boston); (United States), Journal Name: Electr. Light Power (Boston); (United States) Vol. 56:12; ISSN ELLPA
- Country of Publication:
- United States
- Language:
- English
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200104* -- Fossil-Fueled Power Plants-- Components
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320305 -- Energy Conservation
Consumption
& Utilization-- Industrial & Agricultural Processes-- Industrial Waste Management
AIR POLLUTION CONTROL
ALKALINE EARTH METAL COMPOUNDS
BY-PRODUCTS
CALCIUM COMPOUNDS
CALCIUM SULFATES
CHALCOGENIDES
CHEMICAL REACTIONS
DESULFURIZATION
ELECTRIC UTILITIES
ELECTROSTATIC PRECIPITATORS
EQUIPMENT
FLUE GAS
GASEOUS WASTES
GERMAN FEDERAL REPUBLIC
GYPSUM
MANAGEMENT
MATERIALS RECOVERY
MINERALS
OXIDES
OXYGEN COMPOUNDS
PERFORMANCE
POLLUTION CONTROL
POLLUTION CONTROL EQUIPMENT
PROCESSING
PRODUCTION
PUBLIC UTILITIES
RECOVERY
RECYCLING
SCALING
SCRUBBERS
SLUDGES
SULFATES
SULFUR COMPOUNDS
SULFUR DIOXIDE
SULFUR OXIDES
WASTE MANAGEMENT
WASTE PROCESSING
WASTE PRODUCT UTILIZATION
WASTES