Simulation analysis of a GTL process using ASPEN plus

摘要

Gas-to-liquid (GTL) processes are becoming attractive due to the increasing price of crude oil. Process simulation analysis on the integrated GTL process is essential as part of an extended process integration analysis of the research subjects. The two sub-process models for the GTL process, i.e., the syngas generation process and the Fischer Tropsch synthesis (FTS) process, are analyzed in detail with ASPEN Plus. The autothermal reforming process (ATR) is analyzed using Aspen Plus based on the Gibbs reactor model, while FTS is simulated with ASPEN Plus based on detailed kinetic models for industrial iron and cobalt catalysts. Integrated GTL processes with iron and cobalt-based catalysts were simulated using ASPEN Plus. The optimal flowsheet structures were selected for each catalyst based on the overall performance in terms of thermal and carbon efficiency and product distributions. For the cobalt-based catalyst, the full conversion concept without CO2 removal from the FT tail gas is optimal. On the other hand, the once-through concept with two series reactors and CO2 removal from raw syngas is considered optimal for the iron-based catalyst. The thermal efficiency to crude products is likely to be ca. 60 % for the cobalt-based catalyst, whereas it is in the range of 49-55 % for the iron-based catalyst. The carbon efficiency using the water-gas shift reaction is lower using the iron-based catalyst (61-68 %) than the cobalt-based catalyst (73-75 %). As expected, the cobalt-based catalyst is more active and selective, which offers better selectivity towards C-5+ (75-79 %). The selectivity towards C-5+ for the iron-based catalyst lies in the range 63-75 %.