Method for the liquefaction of a hydrocarbon-rich fraction

Abstract

A method for the liquefaction of a hydrocarbon-rich fraction is described, wherein the hydrocarbon-rich fraction is liquefied against an open expander refrigeration circuit. According to the invention, that partial stream ( 6 - 14 ) of the hydrocarbon-rich fraction ( 3 ) to be liquefied which circulates in the expander refrigeration circuit is expanded in two stages so as to perform work (X 1 , X 2 ), wherein the partial stream ( 9 ) expanded in the first expansion stage (X 1 ) is cooled (E) and subsequently supplied ( 10 ) to the second expansion stage (X 2 ).

1 . Method for the liquefaction of a hydrocarbon-rich fraction, wherein the hydrocarbon-rich fraction is liquefied against an open expander refrigeration circuit, characterized in that that partial stream ( 6 - 14 ) of the hydrocarbon-rich fraction ( 3 ) to be liquefied which circulates in the expander refrigeration circuit is expanded in two stages so as to perform work (X 1 , X 2 ), wherein the partial stream ( 9 ) expanded in the first expansion stage (X 1 ) is cooled (E) and subsequently supplied ( 10 ) to the second expansion stage (X 2 ). 
     
     
         2 . Method according to  claim 1 , characterized in that the partial stream ( 6 ) which circulates in the expander refrigeration circuit is additionally supplied to a third expansion stage (X 3 ), wherein said third expansion stage is positioned upstream of the two-stage expansion (X 1 , X 2 ). 
     
     
         3 . Method according to  claim 1 , characterized in that the liquefied hydrocarbon-rich fraction ( 4 ) is expanded (a) and the gaseous fraction formed during said expansion is separated off (D) and admixed again to the hydrocarbon-rich fraction ( 1 ) to be liquefied. 
     
     
         4 . Method according to  claim 1 , wherein the hydrocarbon-rich fraction to be liquefied and/or at least one other process stream is subjected to a compression, characterized in that at least one of the expansion stages (X 1 , X 2 , X 3 ) and the or at least one of the compressions are realized in a compander.