Methods for producing sterile cryogenic fluids

Abstract

A method for producing a sterile cryogenic fluid is disclosed. A warm gas stream is sterilized by filtration and fed to a heat exchanger resulting in a cryogenic sterile fluid being formed. The waste gas stream from the heat exchanger is fed to a second filtration unit and the warm sterile waste gas stream is fed to a second heat exchanger to produce more cryogenic sterile fluid, resulting in a more efficient use of gases employed in the sterilization process.

1 . An improved method for producing sterile cryogenic fluids by feeding a gas stream to a filtration system to produce a sterile warm gas and feeding said sterile warm gas to a heat exchanger thereby cooling and condensing said sterile warm gas to produce a sterile liquid, the improvement comprising feeding a waste gas stream from said heat exchanger to a second filtration system for producing sterile warm gas. 
     
     
         2 . The method as claimed in  claim 1  wherein said gas stream is selected from the group consisting of a cryogenic fluid having a normal boiling point below −50° C. 
     
     
         3 . The method as claimed in  claim 2  wherein said cryogenic fluid is selected from group consisting of nitrogen, oxygen, air and argon, and mixtures thereof. 
     
     
         4 . The method as claimed in  claim 1  wherein said first and said second filtration system removes microorganisms and other particulates from said gas stream. 
     
     
         5 . The method as claimed in  claim 1  wherein said heat exchanger employs cryogenic fluids to provide heat exchange. 
     
     
         6 . The method as claimed in  claim 5  wherein the pressure of said cryogenic fluids to provide heat exchange is less than the pressure of said gas stream. 
     
     
         7 . The method as claimed in  claim 1  wherein said sterile cryogenic fluids are recovered. 
     
     
         8 . The method as claimed in  claim 1  wherein said waste gas stream is a cryogenic fluid selected from the group consisting of nitrogen, oxygen, air and argon. 
     
     
         9 . The method as claimed in  claim 1  wherein said gas stream and said waste gas stream are both cryogenic fluids. 
     
     
         10 . The method as claimed in  claim 1  further comprising feeding a gas stream from said second filtration system to a second heat exchanger. 
     
     
         11 . A method for producing a sterile cryogenic fluid comprising feeding a waste gas stream from a first heat exchanger to a filtration system thereby producing a warm sterile gas and feeding said warm sterile gas to a second heat exchanger wherein said warm sterile gas is reduced to cryogenic temperature. 
     
     
         12 . The method as claimed in  claim 11  wherein said gas stream is selected from the group consisting of a cryogenic fluids having a normal boiling point below −50° C. 
     
     
         13 . The method as claimed in  claim 12  wherein said cryogenic fluid is selected from group consisting of nitrogen, oxygen, air and argon, or mixtures thereof. 
     
     
         14 . The method as claimed in  claim 11  wherein said first and said second filtration system removes microorganisms and particulates from said gas stream. 
     
     
         15 . The method as claimed in  claim 11  wherein said heat exchanger employs cryogenic fluids to provide heat exchange. 
     
     
         16 . The method as claimed in  claim 15  wherein the pressure of said cryogenic fluids to provide heat exchange is less than the pressure of said gas stream. 
     
     
         17 . The method as claimed in  claim 11  wherein said sterile cryogenic fluids are recovered. 
     
     
         18 . The method as claimed in  claim 11  wherein said waste gas stream is a cryogenic fluid selected from the group consisting of nitrogen, oxygen, air and argon, and mixtures thereof. 
     
     
         19 . The method as claimed in  claim 11  wherein said gas stream and said waste gas stream are both cryogenic fluids. 
     
     
         20 . A method for producing a sterile cryogenic fluid comprising the steps:
 a) feeding a waste gas stream from a first heat exchanger unit to a filtration unit, whereby said waste gas stream is sterilized;   b) feeding said sterilized waste gas stream to a second heat exchanger wherein said sterilized waste gas stream is reduced in temperature, thereby producing a sterile cryogenic fluid;   c) recovering said sterile cryogenic fluid; and   d) feeding the waste gas stream from said second heat exchanger to a second filtration unit whereby said second waste gas stream is sterilized and feeding the second sterilized waste gas stream to a third heat exchanger.   
     
     
         21 . The method as claimed in  claim 20  wherein said gas stream is selected from the group consisting of a cryogenic fluids having a normal boiling point below −50° C. 
     
     
         22 . The method as claimed in  claim 20  wherein said cryogenic fluid is selected from group consisting of nitrogen, oxygen, air and argon, and mixtures thereof. 
     
     
         23 . The method as claimed in  claim 20  wherein said first and said second filtration system removes microorganisms from said gas stream. 
     
     
         24 . The method as claimed in  claim 20  wherein said heat exchanger employs cryogenic fluids to provide heat exchange. 
     
     
         25 . The method as claimed in  claim 24  wherein the pressure of said cryogenic fluids to provide heat exchange is less than the pressure of said gas stream. 
     
     
         26 . The method as claimed in  claim 20  wherein said sterile cryogenic fluids are recovered. 
     
     
         27 . The method as claimed in  claim 20  wherein said waste gas stream is a cryogenic fluid selected from the group consisting of nitrogen, oxygen, air and argon. 
     
     
         28 . The method as claimed in  claim 20  wherein said gas stream and said waste gas stream are both cryogenic fluids. 
     
     
         29 . The method as claimed in  claim 20  further comprising feeding a sterilized gas stream from said third heat exchanger to a third filtration unit.