Vapor stripping process
OwnerRobert C. Petterson, Roger C. Loubierinventors
Life of this patent
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Abstract
Coatings, such as paint or oil, are stripped from the surface of a coated object by circulating a stream of a stripping composition in a gaseous state at ambient temperature and pressure into contact with the surface. The stripping composition is normally a liquid at ambient temperature and pressure and has a partial pressure of at least 5 mm. Hg. at ambient conditions. The contacting procedure is conducted substantially in the absence on the surface of liquid condensate of the stripping composition. Alternatively, contacting is carried out with neither the stripping composition nor the surface being above ambient temperature and with at least one of them being cooled below ambient temperature.
Claims33
A method for stripping an organic coating selected from a member of the group consisting of asphalt, heavy fuel oil distillation residue and vegetable oil from the surface of a coated object comprising circulating a stream of a coating stripping composition in a gaseous state at about ambient temperature and pressure into contact with said surface for a time sufficient to destroy the adhesion between said organic coating and said surface, and substantially in the absence on said surface of liquid condensate of said stripping composition, said stripping composition being normally a liquid and having a partial pressure of at least about 5 mm. Hg at ambient temperature and pressure.
In a method of stripping an organic coating selected from the group consisting of asphalt, crude oil and vegetable oil from interior coated surfaces of large constructions, including in particular the interiors of storage tanks on land and holds, and ballast tanks of ships, the steps comprising:
- sealing said interior surface from the atmosphere to form a stripping zone,
- forming a stream of stripping composition in the gaseous state capable of destroying the adhesion between said coating and said interior surface at about ambient temperature and pressure, said stripping composition being normally liquid at about ambient temperature and pressure and having a partial pressure of at least about 5 mm. Hg at ambient temperature, and at the same time,
- introducing said stripping composition in the gaseous state into said stripping zone into contact with said interior surface, and at the same time,
- withdrawing at least a portion of said air from said stripping zone so that said gas phase in said stripping zone is enriched with said stripping composition,
- circulating said stripping composition within said stripping zone and,
- maintaining said stripping composition in the gaseous state in contact with said coated surface at about ambient temperature and pressure and substantially in the absence of liquid stripping composition condensate on said surface until the adhesion between said coating and said surface is substantially destroyed.
A method for stripping an organic coating from the surface of a coated object comprising circulating a stream of a stripping composition in a gaseous state into contact with said surface for a period of time sufficient to destroy the adhesion between said organic coating and said surface, said stripping composition being normally liquid and having a partial pressure of at least about 5 mm. Hg. at ambient temperature and pressure, said contacting being carried out with neither said stripping composition nor said surface above about ambient temperature and with at least one of said surface or said stripping composition being cooled below ambient temperature.
Dependencies are inferred from the claim text.