Method of removing heavy hydrocarbons

Abstract

Heavy hydrocarbons contained in FT off gas of a GTL process are removed by bringing the FT off gas into contact with absorption oil, by introducing the FT off gas into a distillation tower, by cooling the FT off gas or by driving the FT off gas into an adsorbent. A burner tip for heating a reformer tube, using FT off gas as fuel, is prevented from being plugged by the deposition of heavy hydrocarbons contained in the FT off gas.

1 . A method of producing various hydrocarbon oils from natural gas comprising:
 a synthesis gas production step of producing synthesis gas containing hydrogen and carbon monoxide as main components by causing natural gas containing methane as main component to react with steam and/or carbon dioxide in a heated reformer tube filled with a reforming catalyst;   a Fischer-Tropsch synthesis step of producing Fischer-Tropsch oil by subjecting the synthesis gas produced in the synthesis gas production step to a Fischer-Tropsch synthesis reaction and subsequently separating FT off gas containing gaseous products and unreacted synthesis gas; and   an upgrading step of producing various hydrocarbon oils by subjecting the Fischer-Tropsch oil to a hydrotreating, hydroisomerization and hydrocracking process, wherein   the FT off gas is recycled as a fuel for heating the reformer tube after heavy hydrocarbons contained in the FT off gas is removed.   
     
     
         2 . The method according to  claim 1 , wherein the heavy hydrocarbons are hydrocarbons having five or more carbon atoms per molecule. 
     
     
         3 . The method according to  claim 1 , wherein the heavy hydrocarbons are removed by bringing the FT off gas into contact with absorption oil directly. 
     
     
         4 . The method according to  claim 3 , wherein the absorption oil is one of kerosene and gas oil. 
     
     
         5 . The method according to  claim 1 , wherein the heavy hydrocarbons are removed by distilling the FT off gas. 
     
     
         6 . The method according to  claim 1 , wherein the heavy hydrocarbons are removed by cooling the FT off gas. 
     
     
         7 . The method according to  claim 1 , wherein the heavy hydrocarbons are removed from the FT off gas by adsorption. 
     
     
         8 . The method according to  claim 7 , wherein an adsorbent used for the adsorption is active carbon.