Air distillation method with argon production and the corresponding air distillation unit

Abstract

A method and apparatus for air distillation which makes it possible to deliver relatively large flow rates of oxygen-enriched and nitrogen-enriched fluid at a low cost, is provided. The apparatus has at least two double distillation columns and at least two argon columns that operate in parallel. The argon-enriched fluid which is formed are then mixed downstream of the argon columns, and directed through a common compressor, deoxygenation unit, or drying unit, and more than one of which may be common to both streams.

1 - 20 . (cancelled).  
     
     
         21 . An air distillation method, comprising the steps of: 
 a) distilling air in at least two double distillation columns, which operate in parallel, in order to form at least a first oxygen-enriched fluid and a first nitrogen-enriched fluid, wherein the double distillation columns comprising a higher-pressure column and a lower-pressure column;    b) drawing off argon-rich fluid from the lower-pressure columns;    c) distilling the argon-rich fluid in at least two argon columns, which operate in parallel, in order to form at least two streams of argon-enriched fluid and a second oxygen-enriched fluid;    d) mixing the argon-enriched fluid streams downstream of the argon columns,    e) compressing the argon-enriched fluid in at least one compressor, thereby producing a first compressed fluid;    f) reacting hydrogen, with the oxygen contained in the first compressed fluid, in at least one deoxygenation unit, in order to deoxygenate it while producing water;    g) passing the deoxygenated fluid through at least one drying unit in order to dry it, thereby producing a first dried fluid, wherein at least one element selected from the group consisting of the compressor, the deoxygenation unit, and the drying unit, is a common element which is used in order to compress or deoxygenate or dry the mixed fluids together, and    h) distilling the first dried fluid in at least one denitrogenation column in order to form argon and a second nitrogen-enriched fluid.    
     
     
         22 . The method as claimed in  claim 21 , wherein the common element is the deoxygenation unit.  
     
     
         23 . The method as claimed in  claim 21 , wherein the common element is the drying unit.  
     
     
         24 . The method as claimed in  claim 23 , wherein the drying unit comprises a device for drying by adsorption.  
     
     
         25 . The method as claimed in  claim 23 , wherein the drying unit comprises a phase separator.  
     
     
         26 . The method as claimed in  claim 21 , wherein the common element is the compressor.  
     
     
         27 . The method as claimed in  claim 26 , wherein the mixed fluids are heated together in a common heat exchanger upstream of the compressor.  
     
     
         28 . The method as claimed in  claim 23 , wherein the dried fluids are cooled together in a common heat exchanger downstream of the drying unit.  
     
     
         29 . The method as claimed in  claim 21 , wherein the common elements are the drying unit and the compressor.  
     
     
         30 . The method as claimed in  claim 29 , wherein the mixed fluids are heated upstream of the compressor, and the dried fluids are cooled downstream of the drying unit, in a common heat exchanger.  
     
     
         31 . The method as claimed in  claim 21 , wherein a dedicated denitrogenation column, in which the respective deoxygenated and dried fluid is distilled, is used for each double distillation column and each argon column.  
     
     
         32 . An air distillation plant comprising: 
 a) at least two double distillation columns, which operate in parallel, for distilling air while forming at least a first oxygen-enriched fluid and a first nitrogen-enriched fluid, the double distillation columns comprising a higher-pressure column and a lower-pressure column;    b) means for drawing off an argon-rich fluid from the lower-pressure columns;    c) at least two argon columns, which operate in parallel, for distilling the argon-rich fluid while forming at least two argon-enriched fluid streams and a second oxygen-enriched fluid;    d) means for mixing the argon-enriched fluids downstream of the argon columns;    e) at least one compressor for compressing the argon-enriched fluid;    f) at least one deoxygenation unit for reacting hydrogen with the oxygen contained in the compressed fluid, in order to deoxygenate it while producing water;    g) at least one drying unit for the deoxygenated fluid to be passed through in order to dry it, wherein at least one element selected from the group consisting of: the compressor, the deoxygenation unit and the drying unit, is a common element designed to compress or deoxygenate or dry the mixed fluids together; and    h) at least one denitrogenation column for distilling the dried fluid while forming argon and a second nitrogen-enriched fluid.    
     
     
         33 . The plant as claimed in  claim 32 , wherein the common element is the deoxygenation unit.  
     
     
         34 . The plant as claimed in  claim 32 , wherein the common element is the drying unit.  
     
     
         35 . The plant as claimed in  claim 34 , wherein the drying unit comprises a device for drying by adsorption.  
     
     
         36 . The plant as claimed in  claim 34 , wherein the drying unit comprises a phase separator.  
     
     
         37 . The plant as claimed in  claim 32 , wherein the common element is the compressor.  
     
     
         38 . The plant as claimed in  claim 37 , further comprising a common heat exchanger, arranged upstream of the compressor, for heating the mixed fluids together.  
     
     
         39 . The plant as claimed in  claim 34 , further comprising a common heat exchanger, arranged downstream of the drying unit, for cooling the dried fluids together.  
     
     
         40 . The plant as claimed in  claim 32 , wherein the common elements are the drying unit and the compressor.  
     
     
         41 . The plant as claimed in  claim 40 , further comprising a single common heat exchanger, for heating the mixed fluids upstream of the compressor and cooling the mixed and dried fluids downstream of the drying unit.  
     
     
         42 . The plant as claimed in  claim 32 , further comprising, for each double distillation column and each argon column, a dedicated denitrogenation column for the respective deoxygenated and dried fluid to be distilled in it.