The modelled GTL system has two flowsheet options (design specifications) to vary the flow rates of H2O and NG, as well as two recycle streams flowing to reforming/FT sections. As a result, the flowsheet convergence can be pretty tricky. After trails and errors, we would suggest a two-stage strategy for a fast convergence for this case. In the first stage, the convergence of mass flows is performed. Newton algorithm is selected to converge the two design specifications, while Broyden or Wegstein algorithm is used to tear the stream FTIN. Because the recycle loop and design specifications can interact with each other in our case, the tear stream has to be solved simultaneously with the two design specifications (Outside-Simultaneous is recommended for sequencing). After the mass flow is converged, the heat flow is then converged in the second stage.