Offshore gas separation process

Abstract

A process for the selective absorption of normally gaseous acid components from hydrocarbon gas mixtures containing both the acidic components and gaseous non-acidic components which is carried out in a gas separation unit located at an offshore marine production installation. The sorbent used in the process comprises a severely sterically hindered amino ether. The process is capable of selectively removing H 2 S from gas mixtures which also contain CO 2 in addition to the hydrocarbon components.

1 . A marine offshore petroleum fluid production installation including a cyclic amine absorption natural gas purification unit for separating acidic gases from produced petroleum gas, the unit comprising an absorption tower and a regeneration tower through which an aqueous amine absorbent solution is circulated to absorb acidic gases from the gas in the absorption tower and to desorb acidic gases in the regeneration tower to produce a stream of purified gas and at least one stream of acidic gas removed from the gas, the aqueous amine absorbent solution comprises an aqueous solution of a severely sterically hindered amino ether of the formula:
   R 1 —NH—[C n H2 n -O-] x -OY
   
       where R 1  is a secondary or tertiary alkyl group of 3 to 8 carbon atoms, Y is H or alkyl of 1 to 6 carbon atoms, n is a positive integer from 3 to 8 and x is a positive integer from 3 to 6. 
     
     
         2 . A marine offshore petroleum fluid production installation according to  claim 1  in which R 1  is a branched secondary or tertiary alkyl group of 3 to 9 carbon atoms. 
     
     
         3 . A marine offshore petroleum fluid production installation according to  claim 2  in which R 1  is tertiary butyl. 
     
     
         4 . A marine offshore petroleum fluid production installation according to  claim 3  in which n is 2. 
     
     
         5 . A marine offshore petroleum fluid production installation according to  claim 1  in which x is 3. 
     
     
         6 . A marine offshore petroleum fluid production installation according to  claim 1  in which Y is H 
     
     
         7 . A marine offshore petroleum fluid production installation according to  claim 6  in which the amino ether is tert-butylamino ethoxyethoxyethanol. 
     
     
         8 . A marine offshore petroleum fluid production installation according to  claim 1  in which Y is methyl. 
     
     
         9 . A marine offshore petroleum fluid production installation according to  claim 1  in which the amino ether is tert-butylamino methoxy-ethoxyethoxyethanol. 
     
     
         10 . A marine offshore petroleum fluid production installation according to  claim 1  in which the absorbent solution also comprises a diamino ether of the formula:
   R 1 —NH—[C n H 2n —O—] x —NHR 2  
 
 
       where R 1 , n and x are as defined in  claim 1  and R 2 , which may the same or different to R 1 , is a secondary or tertiary alkyl group of 3 to 8 carbon atoms. 
     
     
         11 . A marine offshore petroleum fluid production installation according to  claim 1  in which the absorbent solution also comprises bis-(t-butylamino ethoxy)ethane. 
     
     
         12 . A marine offshore petroleum fluid production installation according to  claim 11  in which the absorbent solution comprises tert-butylamino methoxy-ethoxyethoxyethanol and bis-(t-butylamino ethoxy)ethane. 
     
     
         13 . A process for the selective absorption of normally gaseous acidic components from hydrocarbon gas mixtures containing both the acidic component and gaseous non-acidic components, which process is carried out in a gas separation unit located at an offshore marine petroleum fluid production installation in which an aqueous amine absorbent solution is circulated in a cyclic amine absorption natural gas purification unit to absorb acidic gases from the hydrocarbon gas in an absorption tower and to desorb acidic gases in a regeneration tower to produce a stream of purified hydrocarbon gas and at least one stream of acidic gas removed from the hydrocarbon gas, the aqueous amine absorbent solution being an aqueous solution of a severely sterically hindered amino ether of the formula:
   R 1 —NH—[C n H 2n —O—] x —OY
   
       where R 1 , Y, n and x are as defined in  claim 1 . 
     
     
         14 . A process according to  claim 13  in which H 2 S is selectively removed from a produced natural gas stream which contains H 2 S and CO 2 . 
     
     
         15 . A process according to  claim 13  in which the amino ether comprises tert-butylamino-ethoxyethoxy ethanol. 
     
     
         16 . A process according to  claim 13  in which the absorbent solution also comprises a diamino ether of the formula:
   R 1 —NH—[C n H 2n —O—] x —NHR 2  
 
 
       where R 1 , Y, n and x are as defined in  claim 1  and R 2  is as defined in  claim 10 . 
     
     
         17 . A process according to  claim 16  in which the absorbent solution also comprises bis-(t-butylaminoethoxy)ethane. 
     
     
         18 . A process according to  claim 17  in which the absorbent solution comprises tert-butylamino methoxy-ethoxyethoxyethanol and bis-(t-butylaminoethoxy)ethane. 
     
     
         19 . A process for purifying a stream of natural gas produced at a marine offshore petroleum fluid production installation including a cyclic amine absorption natural gas purification unit for separating acidic gases from produced natural gas, the unit comprising an absorption tower and a regeneration tower through which an aqueous amine absorbent solution is circulated to absorb acidic gases from the natural gas in the absorption tower and to desorb acidic gases in the regeneration tower to produce a stream of purified gas and at least one stream of acidic gas removed from the natural gas, the aqueous amine absorbent solution being an aqueous solution of a hindered. 
     
     
         20 . A process according to  claim 19  which selectively absorbs H 2 S from the natural gas. 
     
     
         21 . A process according to  claim 19  in which the amino ether comprises tert-butylamino-ethoxyethoxy ethanol. 
     
     
         22 . A process according to  claim 19  in which the absorbent solution also comprises a diamino ether of the formula:
   R 1 —NH—[C n H 2n —O—] x —NHR 2  
 
 
       where R 1 , Y, n and x are as defined in  claim 1  and R 2  is as defined in  claim 1 . 
     
     
         23 . A process according to  claim 22  in which R 1  is tertiary butyl, n is 2 and x is 3. 
     
     
         24 . A process according to  claim 22  in which the absorbent solution also comprises bis-(t-butylaminoethoxy)ethane. 
     
     
         25 . A process according to  claim 22  in which the absorbent solution comprises tert-butylamino methoxy-ethoxyethoxyethanol and bis-(t-butylaminoethoxy)ethane.