Process for separating off nitrogen

Abstract

A process for separating off a nitrogen-rich fraction from a feed fraction containing essentially nitrogen and hydrocarbons, wherein the feed fraction is separated by rectification a nitrogen-rich fraction and a methane-rich fraction, is described. According to the invention, during an interruption of the supply of the feed fraction, at least temporarily, the nitrogen-rich fraction ( 4″ ) and the methane-rich fraction ( 5″ ) are compressed and jointly supplied to the process as feed fraction, wherein the compression of the nitrogen-rich fraction ( 4″ ) and the methane-rich fraction ( 5″ ) can be performed separately and/or jointly.

1 . Process for separating off a nitrogen-rich fraction from a feed fraction containing essentially nitrogen and hydrocarbons, wherein the feed fraction is separated by rectification a nitrogen-rich fraction and a methane-rich fraction, characterized in that, during an interruption of the supply of the feed fraction, at least temporarily, the nitrogen-rich fraction ( 4 ″) and the methane-rich fraction ( 5 ″) are compressed and jointly supplied to the process as feed fraction, wherein the compression of the nitrogen-rich fraction ( 4 ″) and the methane-rich fraction ( 5 ″) can be performed separately and/or jointly. 
     
     
         2 . Process according to  claim 1 , wherein at least one compressor (methane compressor) which compresses the methane-rich fraction in standard operation to the desired delivery pressure is provided, characterized in that the nitrogen-rich fraction ( 4 ″) and the methane-rich fraction ( 5 ″) are compressed by means of the methane compressor (V). 
     
     
         3 . Process according to  claim 1 , wherein the feed fraction, upstream of the supply into the process, is compressed by means of at least one compressor (feed compressor), characterized in that the nitrogen-rich fraction ( 4 ″) and the methane-rich fraction ( 5 ″) are compressed by means of the feed compressor. 
     
     
         4 . Process according to  claim 1 , characterized in that the nitrogen-rich fraction ( 4 ″) and/or the methane-rich fraction ( 5 ″) are compressed using a compressor which is without function in standard operation.