In the reforming section, GTL starts with NG, water and CO2. In the pre-reformer, all the carbon components are converted to CO and CH4. 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 2.0 -2.2 in the reformer outlet.