Method and apparatus for cooling a hydrocarbon stream

Abstract

A method of cooling a hydrocarbon stream such as natural gas, the method at least comprising the steps of: (a) providing a feed stream; (b) passing the feed stream through a gas treatment stage comprising one or more (number: X) parallel gas treatment units, the feed stream being divided into two or more part-feed streams if there is more than one gas treatment unit, to provide one or more first treated streams; (c) passing the first treated stream or streams of step (b) through an NGL extraction stage comprising one or more (number: Y) parallel NGL extraction units, the first treated stream or streams being shared to match the number of NGL extraction units, to provide one or more second treated streams; and (d) passing the second treated stream or streams of step (c) through a cooling stage comprising one or more (number: Z) parallel cooling systems, the second treated stream or streams being shared to match the number of cooling systems, to provide a cooled hydrocarbon stream or streams.

1 . Method of cooling a hydrocarbon stream such as natural gas, the method at least comprising the steps of:
 (a) providing a feed stream;   (b) passing the feed stream through a gas treatment stage comprising one or more (number: X) parallel gas treatment units, the feed stream being divided into two or more part-feed streams if there is more than one gas treatment unit, to provide one or more first treated streams;   (c) passing the first treated stream or streams of step   (b) through an NGL extraction stage comprising one or more (number: Y) parallel NGL extraction units, the first treated stream or streams being shared to match the number of NGL extraction units, to provide one or more second treated streams; and   (d) passing the second treated stream or streams of step   (c) through a cooling stage comprising one or more (number: Z) parallel cooling systems, the second treated stream or streams being shared to match the number of cooling systems, to provide a cooled hydrocarbon stream or streams;   wherein Y>Z.   
     
     
         2 . Method as claimed in  claim 1 , wherein the feed stream is divided into two part-feed streams, and X is 2 and Z is 1. 
     
     
         3 . Method as claimed in  claim 1 , wherein Y is 2 and Z is 1. 
     
     
         4 . Method as claimed in  claim 1 , wherein the feed stream is divided into three part-feed streams, and X is 3 and Z is 1 or 2. 
     
     
         5 . Method as claimed in  claim 1 , wherein Y is 3 and Z is 1 or 2. 
     
     
         6 . Method according to  claim 1 , wherein the or each NGL extraction unit provides a second treated stream and one or more separate streams. 
     
     
         7 . Method as claimed in  claim 6 , wherein the one or more separate streams comprise one or more of a propane stream, a butane stream and a C 5 + stream. 
     
     
         8 . Method as claimed in  claim 6 , wherein the one or more separate streams are fractionated to provide one or more fractionated streams. 
     
     
         9 . Method as claimed in  claim 7 , wherein the one or more fractionated streams comprise one or more of a propane stream, a butane stream and a C 5 + stream. 
     
     
         10 . Method according to  claim 1 , wherein X is different from Z. 
     
     
         11 . Method according to  claim 1 , wherein the cooling step (d) liquefies the second treated stream or streams to provide a liquefied hydrocarbon stream or streams. 
     
     
         12 . Liquefied hydrocarbons comprising the liquefied hydrocarbon stream obtained from the method of  claim 11 . 
     
     
         13 . Apparatus for cooling a hydrocarbon stream such as natural gas, the apparatus at least comprising:
 (i) a gas treatment stage to receive a feed stream comprising one or more (number: X) parallel gas treatment units, the feed stream being divided if there is more than one gas treatment unit;   (ii) an NGL extraction stage to receive the treated feed stream or streams from the gas treatment stage,   comprising one or more (number: Y) parallel NGL extraction units; and   (iii) a cooling stage to receive the NGL extracted stream or streams from the NGL extraction stage, comprising one or more (number: Z) parallel cooling systems to provide a treated hydrocarbon stream or streams;   wherein Y>Z.   
     
     
         14 . Apparatus as claimed in  claim 13 , wherein X is 2 and Z is 1. 
     
     
         15 . Apparatus as claimed in  claim 13 , wherein Y is 2 and Z is 1. 
     
     
         16 . Apparatus as claimed in  claim 13 , wherein X is 3 and Z is 1 or 2. 
     
     
         17 . Apparatus as claimed in  claim 13 , wherein Y is 3 and Z is 1 or 2. 
     
     
         18 . Apparatus as claimed in  claim 13 , further comprising a fractionator to fractionate all of one or more separate streams provided by the NGL extraction units. 
     
     
         19 . Apparatus according to  claim 13 , wherein X is different from Z. 
     
     
         20 . Apparatus as claimed in  claim 13 , wherein the or each cooling system is a liquefying system. 
     
     
         21 . Method as claimed in  claim 2 , wherein Y is 2 and Z is 1. 
     
     
         22 . Method as claimed in  claim 4 , wherein Y is 3 and Z is 1 or 2. 
     
     
         23 . Method according to  claim 1 , wherein the cooling step (d) liquefies the second treated stream or streams to provide liquefied natural gas. 
     
     
         24 . Apparatus as claimed in  claim 14 , wherein Y is 2 and Z is 1. 
     
     
         25 . Apparatus as claimed in  claim 16 , wherein Y is 3 and Z is 1 or 2.