Method for Separating Trace Components from a Nitrogen-Rich Stream

Abstract

A method for separating hydrogen, helium and/or neon from a nitrogen-rich liquid fraction present at a pressure of at least 10 bar is disclosed. The nitrogen-rich liquid fraction is expanded and undergoes phase separation where expansion takes place at a pressure which allows separation of hydrogen, helium and/or neon except for residues of less than 20 ppmV.

1 - 7 . (canceled) 
     
     
         8 . A method for separating hydrogen, helium and/or neon from a nitrogen-rich liquid fraction present at a pressure of at least 10 bar, wherein the nitrogen-rich liquid fraction is expanded and undergoes phase separation where expansion takes place at a pressure which allows separation of hydrogen, helium and/or neon except for residues of less than 20 ppmV. 
     
     
         9 . A method for separating hydrogen, helium and/or neon from a nitrogen-rich liquid fraction present at a pressure of at least 10 bar, wherein from a starting stream containing at least methane, nitrogen, helium and hydrogen, a pure helium and nitrogen fraction is extracted by:
 partially condensing the starting stream and separating it into a helium-rich gas fraction and into a first nitrogen-rich liquid fraction,   conducting the helium-rich gas fraction to a post-cleaning stage in which by adsorption, permeation and/or rectification a pure helium fraction is obtained where a helium-depleted fraction accumulating in the post-cleaning stage is returned to the starting stream,   separating the first nitrogen-rich liquid fraction into a helium-depleted gas fraction which is similarly returned to the starting stream, and into a second nitrogen-rich liquid fraction, and   taking at least one partial stream of the second nitrogen-rich liquid fraction to a rectificatory pure nitrogen fraction extraction,   wherein a nitrogen-rich liquid fraction drawn off from the rectificatory pure nitrogen fraction extraction is at least partially expanded and subjected to phase separation, wherein the expansion takes place at a pressure which allows a separation of hydrogen, helium and/or neon except for residues of less than 20 ppmV.   
     
     
         10 . The method according to  claim 8 , wherein a nitrogen-rich liquid fraction extracted in the phase separation is evaporated to provide refrigerant. 
     
     
         11 . The method according to  claim 10 , wherein the nitrogen-rich liquid fraction extracted in the phase separation is delivered as a gaseous pure nitrogen product. 
     
     
         12 . The method according  claim 8 , wherein a hydrogen-rich gas fraction extracted in the phase separation is admixed to an expanded bottom product of a rectificatory pure nitrogen fraction extraction and the mixed fraction thus formed is heated to provide refrigerant. 
     
     
         13 . The method according to  claim 12 , wherein the mixed fraction is discharged as fuel gas. 
     
     
         14 . The method according to  claim 12 , wherein the hydrogen-rich gas fraction extracted in the phase separation undergoes pressure maintenance. 
     
     
         15 . A method for separating hydrogen, helium and/or neon from a nitrogen-rich liquid fraction, comprising the steps of:
 expanding the nitrogen-rich liquid fraction to a pressure; and   phase separation of the expanded nitrogen-rich liquid fraction in a precipitator;   wherein the pressure is such that the phase separation separates the hydrogen, helium and/or neon such that a residual content of hydrogen, helium and/or neon is less than 20 ppmV in the nitrogen-rich liquid fraction.   
     
     
         16 . The method according to  claim 15 , wherein the nitrogen-rich liquid fraction is drawn from a liquid stream of nitrogen. 
     
     
         17 . The method according to  claim 16 , wherein the liquid stream of nitrogen is drawn from a separation column. 
     
     
         18 . The method according to  claim 17 , wherein the pressure is at least 10 bar. 
     
     
         19 . The method according to  claim 18 , wherein the phase separated nitrogen-rich liquid fraction is in a form of a liquid nitrogen (LIN) product stream, and further comprising the step of heating the LIN product stream to form a gaseous nitrogen (GAN) product stream. 
     
     
         20 . The method according to  claim 19 , further comprising the step of controlling a hydrogen content in the LIN product stream by adjusting a pressure of a hydrogen-rich gas fraction extracted in the phase separation. 
     
     
         21 . The method according to  claim 20 , wherein the hydrogen-rich gas fraction includes hydrogen, helium and/or neon that is phase separated from the nitrogen-rich liquid fraction.