Cleaning with liquid gases

Abstract

A method for cleaning objects in a pressure vessel with liquefied gases is provided. The gas liquefied under pressure is conducted into the pressure vessel. The temperature of the liquefied gas then, or beforehand, is lowered below the critical temperature of the gas and cleaning is performed at least primarily below the critical temperature and below the critical pressure of the gas. Carbon dioxide at temperatures between −20° C. and +20° C. is especially suitable. The mechanical interactions produced by the increased density and viscosity of the liquefied gas reinforce cleaning. Reduced solvent capacity does not influence the effectiveness of the cleaning. Textiles or components can therefore be cleaned at lower pressure and temperature.

What is claimed is:  
     
       1. A method for cleaning objects in a pressure vessel using carbon dioxide, the method comprisingthe steps of : 
       conducting the carbon dioxide under pressure into the pressure vessel containing the objects to be cleaned, wherein the pressure vessel is only partially filled with liquid carbon dioxide;  
       maintaining or lowering the temperature of the carbon dioxide below the critical temperature; and  
       performing a cleaning operation at least primarily below the critical temperature and below the critical pressure of the carbon dioxide, wherein liquid and gas phases of the carbon dioxide are in equilibrium for a portion of the cleaning, ; 
       wherein the temperature is kept constant at a value between −20° C. and +20° C. and the pressure is raised to a value above the corresponding vapor pressure during a portion of the cleaning.  
     
     
       2. The method according to  claim 1 , wherein the cleaning operation further comprises the step of circulating at least one of the carbon dioxide and the objects to be cleaned in the pressure vessel. 
     
     
       3. The method according to  claim 2 , wherein said circulating step is carried out via a drum mounted at least one of rotatably and pivotably in the pressure vessel, and wherein said drum is operated at least one of intermittently and with a changing direction of rotation. 
     
     
       4. The method according to  claim 1 , wherein the carbon dioxide in the cleaning step is at a temperature of 5° C. to 15° C. 
     
     
       5. The method according to  claim 1 , wherein the carbon dioxide in the cleaning step is at a temperature of 15° C. 
     
     
       6. The method according to  claim 1 , further comprising the step of adding at least one of enzymes, emulsifiers, surfactants, and detergents to the carbon dioxide. 
     
     
       7. The method according to  claim 1 , wherein said method is used for cleaning textiles. 
     
     
       8. The method according to  claim 1 , wherein said method is used for cleaning components. 
     
     
       9. The method according to  claim 1 , wherein the pressure vessel is only partially filled with the carbon dioxide. 
     
     
       10. The method according to  claim 1 , wherein the pressure vessel is completely filled with the carbon dioxide. 
     
     
       11. The method according to  claim 1 , wherein the pressure of the carbon dioxide is below 60 bars. 
     
     
       12. The method according to  claim 2 , wherein the carbon dioxide in the cleaning step is at a temperature of  5 ° C. to  15 ° C. 
     
     
       13. The method according to  claim 4 , wherein the carbon dioxide in the cleaning step is at a temperature of  10 ° C. 
     
     
       14. The method according to  claim 2 , further comprising the step of adding at least one of enzymes, emulsifiers, surfactants, and detergents to the carbon dioxide. 
     
     
       15. The method according to  claim 4 , further comprising the step of adding at least one of enzymes, emulsifiers, surfactants, and detergents to the carbon dioxide. 
     
     
       16. The method according to  claim 1 , wherein the pressure of the carbon dioxide is between  45  and  70  bars. 
     
     
       17. The method according to  claim 4 , wherein the pressure of the carbon dioxide is between  45  and  70  bars. 
     
     
       18. The method according to  claim 12 , wherein the pressure of the carbon dioxide is between  45  and  70  bars. 
     
     
       19. The method according to  claim 15 , wherein the pressure of the carbon dioxide is between  45  and  70  bars. 
     
     
       20. The method according to  claim 1 , wherein the pressure of the carbon dioxide is above  45  bars. 
     
     
       21. The method according to  claim 4 , wherein the pressure of the carbon dioxide is above  45  bars. 
     
     
       22. A method according to  claim 1 , wherein the temperature of the carbon dioxide is maintained below the critical temperature. 
     
     
       23. A method for cleaning objects in a pressure vessel using carbon dioxide, the method comprising: 
       
         conducting the carbon dioxide under pressure into the pressure vessel containing the objects to be cleaned, wherein the pressure vessel is only partially filled with liquid carbon dioxide;  
       
       
         maintaining or lowering the temperature of the carbon dioxide below the critical temperature;  
       
       
         adding enzymes to the carbon dioxide; and  
       
       
         performing a cleaning operation at least primarily below the critical temperature and below the critical pressure of the carbon dioxide, wherein liquid and gas phases of the carbon dioxide are in equilibrium for a portion of the cleaning;  
       
       
         wherein the temperature is kept constant at a value between − 20 ° C. and + 20 ° C. and the pressure is raised to a value above the corresponding vapor pressure during a portion of the cleaning. 
       
     
     
       24. A method for cleaning objects in a pressure vessel using carbon dioxide, the method comprising: 
       
         conducting the carbon dioxide under pressure into the pressure vessel containing at least one of an electronic assembly or an object having a metal surface, wherein the pressure vessel is only partially filled with liquid carbon dioxide;  
       
       
         maintaining or lowering the temperature of the carbon dioxide below the critical temperature; and  
       
       
         performing a cleaning operation at least primarily below the critical temperature and below the critical pressure of the carbon dioxide, wherein liquid and gas phases of the carbon dioxide are in equilibrium for a portion of the cleaning;  
       
       
         wherein the temperature is kept constant at a value between − 20 ° C. and + 20 ° C. and the pressure is raised to a value above the corresponding vapor pressure during a portion of the cleaning.