Multi-objective optimization of a gas-to-liquids (GTL) process with staged Fischer-Tropsch reactor

摘要

In the present research, multi-objective optimization (MOO) was applied to a natural gas-to-liquids (GTL) process with a multi-stage Fischer-Tropsch (FT) reactor. A CO2 stream was fed into the GTL plant's endothermic steam reformer (SMR) to adjust the H-2 to CO ratio of the SMR effluent. Three objective functions were considered in this paper; minimizing the amount of CO2 released to the atmosphere, maximizing carbon efficiency, and maximizing wax production. The degrees of freedom for the GTL process with single-stage FT reactor were recycle ratio to process and recycle ratio to the FT reactor. In addition, for the GTL process with two-stage FT reactor, the synthesis gas split ratio between the stages was considered as another degree of freedom. Maximizing wax production rate results in lower carbon efficiency and higher CO2 emission to the atmosphere. The amount of CO2 intake to the SMR in all cases was 256 tons/hr.