Method for liquefying a hydrocarbon-rich flow

Abstract

Disclosed is a method for liquefying a hydrocarbon-rich stream, in particular a natural gas stream, by indirectly exchanging hear with the coolant mixture of a coolant mixture circuit. In said method, the coolant mixture is condensed in two or more stages, is divided into at least one lower-boiling and at least one higher-boiling coolant mixture fraction, and the coolant mixture fractions are evaporated at different temperature levels against the hydrocarbon-rich stream that is to be cooled and liquefied and are then combined before being condensed once again. The coolant mixture fractions are not entirely evaporated during normal operation and are preferably not superheated. Preferably, at least 1 to 10 percent by weight of the total amount of the coolant mixture are not evaporated.

1 . A method for liquefying a hydrocarbon-rich flow through indirect heat exchange with the refrigerant mixture of a refrigerant mixture circuit, whereby the refrigerant mixture is compressed two-stage or multistage, is separated into at least one lower-boiling and at least one higher-boiling refrigerant mixture fraction and the refrigerant mixture fractions are vaporised at different temperature levels against the hydrocarbon-rich flow to be cooled and liquefied and are then unified prior to recompression, and whereby the refrigerant mixture fractions are not fully vaporised. 
   
   
       2 . A method according to  claim 1 , whereby at least 1 to 10% by weight of the total quantity of the refrigerant mixture is not vaporised. 
   
   
       3 . A method according to  claim 1 , whereby incomplete vaporising of the refrigerant mixture is achieved by the refrigerant mixture having a sufficiently large proportion of heavier hydrocarbons depending on the selected method parameters. 
   
   
       4 . A method according to  claim 1 , whereby the liquid accruing from incomplete vaporising of the refrigerant mixture fractions is separated off. 
   
   
       5 . A method according to  claim 4 , whereby the separated resulting liquid is forwarded to a suitable supply point inside the refrigerant mixture circuit. 
   
   
       6 . A method according to  claim 5 , whereby the forwarding is carried out by means of a pump 
   
   
       7 . A method according to  claim 1 , whereby the refrigerant mixture fractions are not superheated. 
   
   
       8 . A method according to  claim 2 , whereby incomplete vaporising of the refrigerant mixture is achieved by the refrigerant mixture having a sufficiently large proportion of heavier hydrocarbons depending on the selected method parameters. 
   
   
       9 . A method according to  claim 1 , whereby incomplete vaporising of the refrigerant mixture is achieved by the refrigerant mixture having a sufficiently large proportion of heavier hydrocarbons, preferably C 4 H 10 — and C 5 H 12 — hydrocarbons, depending on the selected method parameters, such as vaporising temperature and pressure. 
   
   
       10 . A method according to  claim 2 , whereby incomplete vaporising of the refrigerant mixture is achieved by the refrigerant mixture having a sufficiently large proportion of heavier hydrocarbons, preferably C 4 H 10 — and C 5 H 12 — hydrocarbons, depending on the selected method parameters, such as vaporising temperature and pressure. 
   
   
       11 . A method according to  claim 2 , whereby the liquid accruing from incomplete vaporising of the refrigerant mixture fractions is separated off. 
   
   
       12 . A method according to  claim 3 , whereby the liquid accruing from incomplete vaporising of the refrigerant mixture fractions is separated off. 
   
   
       13 . A method according to  claim 8 , whereby the liquid accruing from incomplete vaporising of the refrigerant mixture fractions is separated off. 
   
   
       14 . A method according to  claim 9 , whereby the liquid accruing from incomplete vaporising of the refrigerant mixture fractions is separated off. 
   
   
       15 . A method according to  claim 10 , whereby the liquid accruing from incomplete vaporising of the refrigerant mixture fractions is separated off. 
   
   
       16 . A method according to  claim 11 , whereby the separated resulting liquid is forwarded to a suitable supply point inside the refrigerant mixture circuit. 
   
   
       17 . A method according to  claim 12 , whereby the separated resulting liquid is forwarded to a suitable supply point inside the refrigerant mixture circuit. 
   
   
       18 . A method according to  claim 13 , whereby the separated resulting liquid is forwarded to a suitable supply point inside the refrigerant mixture circuit. 
   
   
       19 . A method according to  claim 14 , whereby the separated resulting liquid is forwarded to a suitable supply point inside the refrigerant mixture circuit. 
   
   
       20 . A method according to  claim 15 , whereby the separated resulting liquid is forwarded to a suitable supply point inside the refrigerant mixture circuit.