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US 4,738,206 AGranted
Apparatus and method for low temperature thermal stripping of volatile organic compounds from soil
AssigneeRoy F. Weston, Inc.
InventorJohn W. Noland
Life of this patent
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Abstract
Apparatus and method for removing volatile and semi-volatile organic contaminants from natural soil containing moisture by sealing the soil in a stripping conveyor against contact with air and vapor stripping the contaminants at a temperature below the boiling temperatures of the contaminants.
Claims27
In a method of removing volatile and semi-volatile hazardous organic contaminants from natural soil containing moisture and such contaminants the steps which comprise:
- (a) removing the soil from the earth and placing it in a soil container;
- (b) sealing the soil against substantial contact with air and conveying the soil in sealed condition to a stripping conveyor with heated flights,
- (c) vapor stripping said hazardous organic contaminants from said soil in said conveyor at a temperature below the boiling temperatures of said contaminants by driving said moisture out of said soil by volatilization of said moisture;
- (d) separately by combustion of fuel firing a heater for heating said stripping conveyor and thereby generating non-oxidizing combustion gases;
- (e) sweeping said combustion gases countercurrently over the soil subjected to vapor stripping in said stripping conveyor;
- and
- (f) controlling the temperature and flow rate of said countercurrent sweep to maintain moisture continuously present at the surface of the soil as and after said soil enters said stripping conveyor.
4 more elements
Apparatus for removing volatile and semi-volatile hazardous organic contaminants from natural soil containing moisture and such contaminants, comprising:
- (a) a soil container for the earth;
- (b) sealing means for sealing the soil against substantial contact with air;
- (c) a stripping conveyor comprising a screw conveyor with internally heated intermeshing flights;
- (d) means for conveying soil in sealed condition, including a sealed soil conveyor provided to transport soil from the soil container to the stripping conveyor;
- (e) means for applying a negative pressure over soil in said sealed conveyor in a manner to prevent fugitive emissions of the hazardous organic constituents;
- (f) means for heating the moisture contained in the soil by intimate contact with heated surfaces in said stripping conveyor, thereby vapor stripping said hazardous organic contaminants from said soil in said conveyor;
- (g) a fuel burner connected for heating said stripping conveyor and thereby generating non-oxidizing combustion gases;
- (h) means for conveying said combustion gases countercurrently over the soil subjected to vapor stripping in said stripping conveyor;
- and
- (i) control means connected for controlling the temperature and flow rate of said countercurrent sweep to maintain moisture continuously present at the surface of the soil as and after said soil enters said stripping conveyor.
7 more elements
Dependencies are inferred from the claim text.