Producing purified hydrocarbon gas from a gas stream comprising hydrocarbons and acidic contaminants

Abstract

Process for producing purified hydrocarbon gas from a gas stream comprising hydrocarbons and acidic contaminants, which process comprises the steps: (a) cooling the gas stream to a temperature to form a mixture comprising solid and optionally liquid acidic contaminants and a vapour containing gaseous hydrocarbons; (b) separating the solid and optionally liquid acidic contaminants from the mixture in a vessel, yielding the purified hydrocarbon gas; (c) providing heat to at least a part of the solid and optionally liquid acidic contaminants to melt at least part of the solid acidic contaminants, yielding a heated contaminant-rich stream; (d) withdrawing the heated contaminant-rich stream from the vessel; wherein the process further comprises: (e) reheating at least a part of the heated contaminant-rich stream to form a reheated recycle stream; and (f) recycling at least a part of the reheated recycle stream to the vessel.

1 . Process for producing purified hydrocarbon gas from a gas stream comprising hydrocarbons and acidic contaminants, which process comprises the steps:
 (a) cooling the gas stream to a temperature to form a mixture comprising solid acidic contaminants and a vapour containing gaseous hydrocarbons;   (b) separating the solid acidic contaminants from the mixture in a vessel, yielding the purified hydrocarbon gas;   (c) providing heat to at least a part of the solid acidic contaminants to melt at least part of the solid acidic contaminants, yielding a heated contaminant-rich stream;   (d) withdrawing the heated contaminant-rich stream from the vessel;   (e) reheating at least a part of the heated contaminant-rich stream to form a reheated recycle stream; and   (f) recycling at least a part of the reheated recycle stream to the vessel.   
     
     
         2 . Process as claimed in  claim 1  in which the part of the heated contaminant-rich stream that is reheated to form the reheated recycle stream is heated to form a liquid stream. 
     
     
         3 . Process as claimed in  claim 1 , in which the part of the heated contaminant-rich stream that is reheated to form the reheated recycle stream is heated to such a temperature that the stream becomes at least partly vaporous. 
     
     
         4 . Process as claimed in  claim 1 , in which a part of the heated contaminant-rich stream is separated and this part of the heated contaminant-rich stream is reheated to form the reheated recycle stream. 
     
     
         5 . Process as claimed in  claim 4 , in which the part of the heated contaminant-rich stream that is separated is selected such that the reflux ratio ranges from 0.5 to 10. 
     
     
         6 . Process as claimed in  claim 1 , in which substantially the entire heated contaminant-rich stream that is withdrawn from the vessel is reheated to form the reheated recycle stream, and a part of the thus obtained reheated recycle stream is recycled to the mixture. 
     
     
         7 . Process as claimed in  claim 6 , in which the part of the reheated recycle stream that is recycled to the mixture is selected such that the reflux ratio ranges from 0.5 to 10. 
     
     
         8 . Process as claimed in  claim 1 , in which the reheating of at least part of the heated contaminant-rich stream is conducted via heat exchange, in which the heat exchange is preferably conducted with at least part of the gas stream. 
     
     
         9 . Process as claimed in  claim 1 , in which the reheating of at least part of the heated contaminant-rich stream is conducted by adding thereto a warm fluid, preferably natural gas condensate. 
     
     
         10 . Process as claimed in  claim 1 , in which the cooling of the gas stream utilises one or more heat exchange steps. 
     
     
         11 . Process as claimed in  claim 1 , in which the cooling of the gas stream utilises one or more expansion steps. 
     
     
         12 . Process as claimed in  claim 1 , in which the gas stream has been dehydrated, preferably to a water content of less than 50 ppmw, based on the total gas stream. 
     
     
         13 . Process as claimed in  claim 12 , in which gas stream is expanded from a pressure ranging from 40 bar to 200 bar, to a pressure of 10 bar to 40 bar. 
     
     
         14 . Process as claimed in  claim 1 , wherein the purified gas is purified natural gas and the process further comprises the steps of cooling the purified natural gas to obtained liquefied natural gas. 
     
     
         15 . (canceled)