Separating argon/oxygen mixtures using a structured packing

Abstract

The present invention relates to improvements to a process and apparatus for the cryogenic distillation of mixtures, which comprise oxygen, nitrogen and argon, e.g. air. The improvement comprises effectuating intimate contact of the liquid and vapor phase streams utilizing a structured packing to effectuate the intimate contact in at least .[.those.]. .Iadd.one of the .Iaddend.regions of the distillation column system where argon concentration is within the range from about 0.6 to about 75 volume percent.[.,.]. and .[.operating the process such that.]. the densimetric superficial gas velocity .[.in those regions.]. is at least 0.06 feet per second. .[.The present invention also relates to a method for improving a cryogenic distillation apparatus having at least one distillation column for the separation of mixtures containing oxygen and argon, comprising the step of replacing the distillation trays with a structured packing in at least those regions of the distillation column system where the concentration of argon is in the range from about 0.6 to about 75 volume percent..]. .Iadd.The present invention also relates to the use of structured packing to reduce the HETP (height of packing equivalent to a theoretical plate) in a region of a distillation column system separating oxygen and argon by intimately contacting a liquid phase stream containing oxygem and argon, and a vapor phase stream containing oxygen and argon at an argon concentration within the range from 0.6 to 75 volume percent and a densimetric superficial gas velocity of at least 0.06 feet per second. .Iaddend.

We claim: .[.1. In a process for the separation of mixtures, which comprise oxygen, nitrogen, and argon, by cryogenic distillation, wherein in certain regions of a distillation column system having at least one column, a liquid phase stream containing oxygen, argon and nitrogen, and a vapor phase stream containing oxygen, argon and nitrogen, are intimately contacted thereby allowing mass transfer which enriches the liquid phase stream with oxygen and strips argon from the liquid phase stream, and enriches the vapor phase stream with argon and strips oxygen from the vapor phase stream, the improvement comprising effectuating intimate contact of the liquid and vapor phase streams utilizing a structured packing in at least those regions of the distillation column system where argon concentration is within the range from about 0.6 to about 75 volume percent, and operating the process such that the densimetric superficial gas velocity in those regions is at least 0.06 feet per second..]. .[.2. The process of claim 1 wherein the mixture is air..]. .[.3. In a process for the separation of mixtures, which comprise oxygen and argon, by cryogenic distillation, wherein in certain regions of a distillation column system having at least one column, a liquid phase stream containing oxygen and argon, and a vapor phase stream containing oxygen and argon, are intimately contacted thereby allowing mass transfer which enriches the liquid phase stream with oxygen and strips argon from the liquid phase stream, and enriches the vapor phase stream with argon and strips oxygen from the vapor phase stream, the improvement comprising effectuating intimate contact of the liquid and vapor phase streams utilizing a structured packing in at least those regions of the distillation column system where argon concentration is within the range from about 0.6 to about 75 volume percent, and operating the process such that the densimetric superficial gas velocity in those regions is at least 0.06 feet per second..]. .[.4. A method for improving a cryogenic distillation apparatus having at least one distillation column for the separation of mixtures containing oxygen and argon, comprising the step of replacing the distillation trays with a structured packing in at least those regions of the distillation column system where the concentration of argon is in the 
     
        range from about 0.6 to about 75 volume percent..]. .Iadd.5.  A process for the separation of mixtures, which comprise oxygen and argon, by cryogenic distillation, wherein, in a distillation column system having at least one column, a liquid phase stream containing oxygen and argon and a vapor phase stream containing oxygen and argon are intimately contacted in at least one region of the distillation column system where argon concentration is within the range from 0.6 to 75 volume percent, thereby allowing mass transfer which enriches the liquid phase stream with oxygen and strips argon from the liquid phase stream, and enriches the vapor phase stream with argon and strips oxygen from the vapor phase stream, characterized in that intimate contact of said liquid and vapor phase streams in said region is effected utilizing a structured packing and the densimetric superficial gas velocity in said region is at least 0.06 feet per second (1.8 cm/sec)..Iaddend. .Iadd.6. A process as claimed in claim 5, wherein said mixture to be separated further comprises nitrogen. .Iaddend. .Iadd.7. A process as claimed in claim 6, wherein said mixture is air. .Iaddend. .Iadd.8. A process as claimed in claim 7, wherein the distillation column system comprises a high pressure column, a low pressure column and an argon column and said region is in the low pressure 
     
     
        column. .Iaddend. .Iadd.9.  A process as claimed in claim 7, wherein there is more than one region having said argon concentration and all of said regions utilize structured packing and operate within said densimetric superficial gas velocity range. .Iaddend. .Iadd.10. A process as claimed in claim 7, wherein the structural packing is limited to the said region(s) in which the argon concentration is in the range 0.6 to 75 volume percent and the densimetric superficial gas velocity is at least 
     
     
        0.06 feet per second (1.8 cm/sec). .Iaddend. .Iadd.11.  A process as claimed in claim 6, wherein there is more than one region having said argon concentration and all of said regions utilize structured packing and operate within said densimetric superficial gas velocity range. .Iaddend. .Iadd.12. A process as claimed in claim 6 for the separation of a mixture comprising oxygen, nitrogen, and argon, wherein the distillation column system is an integrated multi-column distillation system having a low pressure column and an argon sidearm column integrally communicating with the low pressure column and said regions are in the low pressure column and the argon sidearm column. .Iaddend. .Iadd.13. A process as claimed in claim 12, wherein the integrated multi-column distillation system is a three column distillation system comprising a high pressure column in addition to the lower pressure column and the argon sidearm column. .Iaddend. .Iadd.14. A process as claimed in claim 13, wherein the high pressure column is packed with a structured packing. .Iaddend. .Iadd.15. A process as claimed in claim 6, wherein the structural packing is limited to the said region(s) in which the argon concentration is in the range 0.6 to 75 volume percent and the densimetric superficial gas velocity is at 
     
     
        least 0.06 feet per second (1.8 cm/sec). .Iaddend. .Iadd.16.  A process as claimed in claim 5, wherein there is more than one region having said argon concentration and all of said regions utilize structured packing and operate within said densimetric superficial gas velocity range. .Iaddend. .Iadd.17. A process as claimed in claim 5, wherein the structural packing is limited to the said region(s) in which the argon concentration is in the range 0.6 to 75 volume percent and the densimetric superficial gas velocity is at least 0.06 feet per second (1.8 cm/sec). .Iaddend. 
     
     
        .Iadd.     The use of structured packing to reduce the HETP (height of packing equivalent to a theoretical plate) in a region of a distillation column system separating oxygen and argon by intimately contacting a liquid phase stream containing oxygen and argon, and a vapor phase stream containing oxygen and argon at an argon concentration within the range from 0.6 to 75 volume percent and a densimetric superficial gas velocity of at least 0.06 feet per second (1.8 cm/sec). .Iaddend.