In the reforming section, GTL starts with NG, water and CO2. A typical composition of NG can be referred to Bao's work (Table ). The water is heated to steam before reforming. In the prereformer, all the carbon components are converted to CO and CH4. In the reformer, CH4 is converted to syngas with the assistance of CO2 and steam. The reforming is performed at a high temperature between 700 and 1000 ℃, so it is assumed to reach equilibrium. In Aspen Plus, the reformer is modelled by an RGibbs reactor, where the total Gibbs energy is minimized to the reach the equilibrium ('Restricted Chemical Equilibrium' is set for the combined reforming reactions). A flowsheet option is set to vary the flowrate of H2O and NG to guarantee the ratio of CO : H2 falls in a range of 2 -2.2 in the reformer outlet. Before the FT section, the mixed stream is cooled down and split into a gas stream (mainly syngas and CO2) and a liquid stream (primarily water).