Production method of liquid hydrocarbons from natural gas

Abstract

In a so-called GTL process for producing liquid hydrocarbons containing fuel oil by producing synthesis gas from natural gas, subsequently producing Fischer-Tropsch oil from the obtained synthesis gas by way of Fischer-Tropsch synthesis and upgrading the produced Fischer-Tropsch oil, the synthesis gas produced from a synthesis gas production step is partly branched at a stage prior to getting to a Fischer-Tropsch oil production step and high-purity hydrogen is separated and produced from the synthesis gas entering the branch line. All the separated high-purity hydrogen is supplied to an upgrading reaction step and consumed as hydrogen for an upgrading reaction. Additionally, the synthesis gas entering the branch line is subjected to a water gas shift reaction to raise the hydrogen concentration before the step of separating and producing high-purity hydrogen and the residual gas left after the separation may be circulated to the synthesis gas production step as raw material for producing synthesis gas.