Purification of gases, in synthesis gas production process

Abstract

A purifier process, includes supplying a first stream of a feed gas containing hydrogen and nitrogen in a MOL ratio of about 2/1, and also containing methane, and argon, then cryogenically separating the feed gas into the following: a) a second stream of a synthesis gas containing hydrogen and nitrogen in a MOL ratio of about 3/1, b) waste gas containing principally nitrogen, and also containing substantially all of the methane supplied in the first stream, and splitting the waste gas into: c) a third stream of nitrogen rich gas d) a fourth stream of methane rich gas useful as a fuel, or as a feed to a subsequent process.

I claim:  
     
         1 . In a purifier process, the steps that include 
 1) supplying a first stream of a feed gas containing hydrogen and nitrogen in a MOL ratio of about 2/1, and also containing methane and argon,    2) cryogenically separating the feed gas into the following: 
 a) a second stream of a synthesis gas containing hydrogen and nitrogen in a MOL ratio of about 3/1,  
 b) waste gas containing principally nitrogen, and also containing substantially all of the methane supplied in the first stream,  
   3) and splitting the waste gas into: 
 c) a third stream of nitrogen rich gas  
 d) a fourth stream of methane rich gas useful as a fuel, or as a feed to a subsequent process.  
   
     
     
         2 . The process of  claim 1  including delivering said second, third and fourth streams as product streams.  
     
     
         3 . The process of  claim 2  wherein said second, third and fourth streams are passed through a cold box.  
     
     
         4 . The process of  claim 1  including delivering said second stream of synthesis gas to an ammonia synthesis process.  
     
     
         5 . The process of  claim 1  including providing an expander turbine in series with said third stream, to produce refrigeration.  
     
     
         6 . The process of  claim 3  including: 
 i) providing a Joule Thompson valve through which the methane rich gas is passed, to drop the gas pressure and produce refrigeration, and  
 ii) then passing the waste gas to a heat exchanger for cooling of said second stream,  
 iii) then passing the waste gas to said cold box.  
 
     
     
         7 . The process of  claim 1  including recompressing the waste gas prior to said splitting step.  
     
     
         8 . The process of  claim 7  including passing the recompressed waste gas through a cold box before said splitting, and also passing the second, third and fourth stream through the cold box.  
     
     
         9 . The process of  claim 8  wherein the waste gas is also passed through the cold box prior to said re-compressing.  
     
     
         10 . The process of  claim 8  including providing a separator column to which the recompressed waste gas is passed after its passage through the cold box, and operating said separator column to produce said splitting.  
     
     
         11 . The process of  claim 10  including re-cycling gas from said column to and through the cold box, to lower its temperature, and returning the re-cycled gas to the column.