Pressure-swing absorption based cleaning methods and systems
First Claim
1. A method of cleaning articles by pressure swing absorption with a solvent composition comprising a supercritical fluid, the method comprising:
- loading a pressure vessel with articles to be cleaned;
pressurizing and heating the solvent composition to a supercritical state of the solvent composition;
removing soluble contaminants from the articles by maintaining contact between the articles and the solvent composition in the supercritical state;
depressurizing and cooling the solvent composition within the pressure vessel to a subcritical state of the solvent composition;
removing particulate contaminants from the articles by agitating the articles and the solvent composition in the subcritical state within the pressure vessel;
removing the solvent composition from the pressure vessel; and
unloading the cleaned articles from the pressure vessel.
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Accused Products
Abstract
The cleaning process according to the present invention includes three main steps including supercritical extraction of soluble contaminants with a solvent composition, subcritical removal of particulate material with agitation, and solvent recovery and recycle. The supercritical extraction of soluble contaminants is performed by pumping a solvent composition into a cleaning vessel containing articles to be cleaned and pressurizing and heating the fluid in the vessel to a supercritical state. Then the subcritical phase is begun to remove particulate material from the articles by reducing the pressure and temperature of the solvent composition in the cleaning vessel to a subcritical state and reforming the liquid/gas interface. Agitation of the articles in the cleaning vessel is provided by recirculation of the solvent composition or by motion of a mechanical device within the cleaning vessel. Due to a density difference between gas and liquid in the subcritical phase, the degree of agitation and resultant particulate removal is maximized. The solvent composition recovery step preferably includes further depressurization of the fluid to separate and remove soluble and insoluble contaminants from the fluid, allowing this solvent composition to be reused. The system may be operated with any gas with suitable solvent properties such as carbon dioxide, carbon dioxide based mixtures, or other known solvents.
124 Citations
43 Claims
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1. A method of cleaning articles by pressure swing absorption with a solvent composition comprising a supercritical fluid, the method comprising:
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loading a pressure vessel with articles to be cleaned; pressurizing and heating the solvent composition to a supercritical state of the solvent composition; removing soluble contaminants from the articles by maintaining contact between the articles and the solvent composition in the supercritical state; depressurizing and cooling the solvent composition within the pressure vessel to a subcritical state of the solvent composition; removing particulate contaminants from the articles by agitating the articles and the solvent composition in the subcritical state within the pressure vessel; removing the solvent composition from the pressure vessel; and unloading the cleaned articles from the pressure vessel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A cleaning apparatus for cleaning articles with a solvent composition comprising a supercritical fluid, the system comprising:
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a pressure vessel; a solvent composition supply; pressurization and heating means for pressurizing and heating the solvent composition to a supercritical state; depressurization and cooling means for depressurizing and cooling the solvent composition to a subcritical state; agitation means for agitating the solvent composition within the pressure vessel; recovery means for recycling at least a portion of the solvent composition by removing contaminants from the solvent composition; and control means for controlling the pressurization and heating means, the depressurization and cooling means, and the agitation means such that the system provides a first supercritical cleaning stage for removal of soluble contaminants and a second subcritical agitation cleaning stage for removal of particulate contaminants. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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43. A cleaning apparatus for cleaning articles with a solvent composition comprising a supercritical fluid, the is system comprising:
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a pressure vessel; a solvent composition supply; pressurization and heating means for pressurizing and heating the solvent composition to a supercritical state; depressurization and cooling means for depressurizing and cooling the solvent composition to a subcritical state; agitation means for agitating the solvent composition within the pressure vessel; and control means for controlling the pressurization and heating means, the depressurization and cooling means, and the agitation means such that the system provides a first supercritical cleaning stage for removal of soluble contaminants and a second subcritical agitation cleaning stage for removal of particulate contaminants.
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Specification