Low pressure drop purifier for nitrogen, methane, and argon removal from syngas

Abstract

An apparatus for purifying a raw syngas stream containing excess nitrogen and an ammonia process plant for manufacturing ammonia from syngas with excess air for reforming and nitrogen removal with low pressure losses is disclosed. Auto-refrigeration for cooling the syngas for cryogenic hydrogen enrichment is provided by expansion of a hydrogen-lean waste fluid stream from a distillation column

1 ) An apparatus for purifying a raw syngas stream containing excess nitrogen comprising: 
 means for introducing the raw syngas stream to a feed zone in a distillation column;    means for expanding a liquid bottoms stream from the distillation column through a liquid expander with a work output to form a cooled waste fluid stream;    means for rectifying vapor from the feed zone in the distillation column to form an overhead vapor stream of reduced nitrogen and inerts content;    means for cooling the overhead vapor stream in indirect heat exchange with the cooled waste fluid stream to form a partially condensed overhead stream and a relatively warm waste fluid stream;    means for separating the partially condensed overhead stream into a condensate stream and a purified syngas vapor stream of reduced nitrogen and inerts content; and    means for refluxing the distillation column with the condensate stream.    
   
   
       2 ) The apparatus of  claim 1 , further comprising means for cooling and expanding the raw syngas stream across a Joule-Thompson valve in advance of the introduction to the feed zone.  
   
   
       3 ) The apparatus of  claim 2 , wherein the means for expanding the liquid bottoms stream comprises a hydraulic turbine.  
   
   
       4 ) The apparatus of  claim 1 , wherein the relatively warm waste fluid stream from the overhead vapor cooling consists of a vapor phase.  
   
   
       5 ) The apparatus of  claim 1 , wherein the relatively warm waste fluid stream from the liquid expander comprises mixed vapor and liquid.  
   
   
       6 ) The apparatus of  claim 1 , wherein a liquid level in the distillation column is controlled by adjusting flow the expansion to the liquid bottoms stream.  
   
   
       7 ) The apparatus of  claim 1 , further comprising means for producing the raw synthesis gas by reforming a hydrocarbon, wherein the means for producing the raw synthesis gas comprises autothermal or secondary reforming with excess air.  
   
   
       8 ) The apparatus of  claim 1 , further comprising means for supplying the purified syngas vapor stream to an ammonia synthesis loop to form ammonia.  
   
   
       9 ) An ammonia process plant comprising: 
 means for reforming a hydrocarbon to form syngas, wherein the reforming means include an autothermal or secondary reformer and means for supplying excess air to the autothermal or secondary reformer to form a raw syngas stream containing excess nitrogen for ammonia synthesis;    cross-exchanger means for cooling the raw syngas stream;    means for expanding the cooled raw syngas stream from the cross-exchanger;    means for introducing the expanded raw syngas stream to a feed zone in a distillation column;    means for expanding a liquid bottoms stream from the distillation column through a liquid expander with a work output to form a cooled waste fluid stream;    means for rectifying vapor from the feed zone in the distillation column to form an overhead vapor stream of reduced nitrogen and inerts content;    means for cooling the overhead vapor stream in indirect heat exchange with the cooled waste fluid stream to form a partially condensed overhead stream and a partially warmed waste fluid stream;    means for separating the partially condensed overhead stream into a condensate stream and a purified syngas vapor stream of reduced nitrogen and inerts content;    means for refluxing the distillation column with the condensate stream;    means for heating the purified syngas vapor stream in the cross-exchanger;    means for heating the partially warmed waste fluid stream in the cross exchanger;    means for supplying the purified syngas vapor stream from the cross-exchanger to an ammonia synthesis loop.    
   
   
       10 ) The ammonia process plant of  claim 9 , further comprising means for cooling and expanding the raw syngas stream across a Joule-Thompson valve in advance of the introduction to the feed zone.  
   
   
       11 ) The ammonia process plant of  claim 10 , wherein the means for cooling of the raw syngas stream includes cross-exchange against the partially warmed waste fluid stream and against the purified syngas vapor stream.  
   
   
       12 ) The ammonia process plant of  claim 9 , wherein the means for expanding the liquid bottoms stream comprises a hydraulic turbine.  
   
   
       13 ) The ammonia process plant of  claim 9 , wherein the partially warmed waste fluid stream from cooling of the overhead vapor stream consists of a vapor phase.  
   
   
       14 ) The ammonia process plant of  claim 9 , wherein waste fluid from the liquid expander comprises mixed vapor and liquid.  
   
   
       15 ) The ammonia process plant of  claim 9 , wherein a liquid level in the distillation column is controlled by adjusting flow the expansion to the liquid bottoms stream.  
   
   
       16 ) The ammonia process plant of  claim 9 , further comprising means for producing the raw synthesis gas by reforming a hydrocarbon, wherein the means for producing the raw synthesis gas comprises autothermal or secondary reforming with excess air.  
   
   
       17 ) The ammonia process plant of  claim 9 , further comprising means for supplying the purified syngas vapor stream to an ammonia synthesis loop to form ammonia.