Divided pressure vessel apparatus for carbon dioxide based systems and methods of using same

Abstract

A method of utilizing a divided pressure vessel in a processing system employing a carbon dioxide based solvent includes transferring a first carbon dioxide based treating solution from a first liquid chamber in a divided pressure vessel having a plurality of liquid chambers to a processing vessel, returning the first treating solution from the processing vessel to the divided pressure vessel, transferring a second carbon dioxide based treating solution having a composition different from the first treating solution from a second liquid chamber in the divided pressure vessel to a processing vessel, and returning the second treating solution from the processing vessel to the divided pressure vessel. A divided pressure vessel may allow multiple solvent baths each having a different chemical composition to be stored and/or processed in a single pressure vessel while maintaining the different chemical compositions of the multiple solvent baths. Thus, such divided pressure vessels may provide the improved operational efficiency of a carbon dioxide based system having multiple solvent baths while decreasing the capital costs that may be associated with such systems.

1 . A dry cleaning system employing a carbon dioxide based solvent, said system comprising: 
 a divided working tank configured to store a plurality of liquid carbon dioxide based treating solutions having different compositions, said divided working tank including: 
 an exterior wall defining an interior volume, said exterior wall capable of withstanding an internal pressure of at least about 500 psig; and  
 a first dividing member extending from an interior surface of the exterior wall and defining a first and a second liquid chamber in the divided pressure vessel, wherein the first and the second liquid chambers share a common vapor space;  
 a first carbon dioxide based dry-cleaning solution consisting essentially of liquid carbon dioxide positioned in the first liquid chamber; and  
 a wash tank configured to contact a dry-cleanable article to be cleaned with one or more of the plurality of treating solutions, the wash tank in fluid communication with the divided working tank.  
   
   
   
       2 . The system according to  claim 1 , wherein the working tank further includes a second dividing member defining a third liquid chamber, the third liquid chamber sharing the common vapor space with the first and the second liquid chambers.  
   
   
       3 . The system according to  claim 2 , wherein the second liquid chamber is positioned between the first liquid chamber and the third liquid chamber.  
   
   
       4 . The system according to  claim 3 , further comprising a single operating level sensor positioned within the divided working tank, wherein the single level sensor is positioned within the second liquid chamber, and wherein the level sensor is capable of sensing the level of carbon dioxide based dry-cleaning solution in the second liquid chamber.  
   
   
       5 . The system according to  claim 3 , further comprising a heating element operatively associated with the third liquid chamber.  
   
   
       6 . The system according to  claim 5 , further comprising: 
 a liquid transfer system providing liquid communication between the divided working tank and the wash tank; and    a vapor transfer system providing vapor communication between the divided working tank and the wash tank.    
   
   
       7 . The system according to  claim 6 , further comprising: 
 a first opening in the exterior wall adjacent the first liquid chamber for liquid transfer between the first liquid chamber and an environment external to the divided working tank;    a second opening in the exterior wall adjacent the second liquid chamber for liquid transfer between the second liquid chamber and the environment external to the divided working tank;    a third opening in the exterior wall adjacent the third liquid chamber for liquid transfer between the third liquid chamber and the environment external to the divided working tank; and    a fourth opening in the exterior wall adjacent the common vapor space for fluid transfer between the common vapor space and the environment external to the divided working tank;    wherein the first, the second, and the third openings are in liquid communication with the liquid transfer system, and wherein the fourth opening is in fluid communication with the vapor transfer system.    
   
   
       8 . The system according to  claim 7 , further comprising a condenser positioned in the vapor transfer system, wherein the condenser is in fluid communication with the fourth opening of the exterior wall of the divided working tank, and wherein the fourth opening in the exterior wall is positioned above the first liquid chamber.  
   
   
       9 . The system according to  claim 2 , further comprising: 
 a second carbon dioxide based dry-cleaning solution positioned within the second liquid chamber, the second dry-cleaning solution having a second composition and;    a third carbon dioxide based dry-cleaning solution positioned within the third liquid chamber, the third dry-cleaning solution having a second composition, wherein the first, the second, and the third compositions are different.    
   
   
       10 . A divided pressure vessel for use in a carbon dioxide based system, said pressure vessel comprising: 
 an exterior wall defining an interior volume, said exterior wall capable of withstanding an internal pressure of at least about 500 psig;    a first dividing member extending from an interior surface of the exterior wall and defining a first and a second liquid chamber in the divided pressure vessel, wherein the first and the second liquid chambers share a common vapor space; and    a first carbon dioxide based treating solution consisting essentially of liquid carbon dioxide positioned in the first liquid chamber.    
   
   
       11 . The pressure vessel according to  claim 10 , further comprising a single operating level sensor positioned within the divided pressure vessel, wherein the single level sensor is positioned within the first liquid chamber, and wherein the single level sensor is capable of sensing the level of carbon dioxide based treating solution in the first liquid chamber.  
   
   
       12 . The pressure vessel according to  claim 10 , further comprising a second carbon dioxide based treating solution having a second composition positioned in the second liquid chamber, wherein the compositions of the first and the second treating solutions are different.  
   
   
       13 . The pressure vessel according to  claim 10 , further comprising a second dividing member defining a third liquid chamber, the third liquid chamber sharing the common vapor space with the first and the second liquid chambers.  
   
   
       14 . The pressure vessel according to  claim 13 , wherein the second liquid chamber is positioned between the first liquid chamber and the third liquid chamber.  
   
   
       15 . The pressure vessel according to  claim 14 , further comprising a heating element operatively associated with the third liquid chamber.  
   
   
       16 . The pressure vessel according to  claim 15 , further comprising: 
 a first opening in the exterior wall adjacent the first liquid chamber for liquid transfer between the first liquid chamber and an environment external to the divided working tank;    a second opening in the exterior wall adjacent the second liquid chamber for liquid transfer between the second liquid chamber and the environment external to the divided working tank; and    a third opening in the exterior wall adjacent the third liquid chamber for liquid transfer between the third liquid chamber and the environment external to the divided working tank.    
   
   
       17 . The pressure vessel according to  claim 16 , further comprising a fourth opening in the exterior wall adjacent the common vapor space for fluid transfer between the common vapor space and the environment external to the divided working tank.  
   
   
       18 . The pressure vessel according to  claim 17 , wherein the fourth opening in the exterior wall is positioned above the first liquid chamber.