Gas-to-Liquid Process Optimization for Different Recycling Configurations and Economic Evaluation

Synthesis gas production by the steam methane reforming process and its subsequent use in Fischer-Tropsch synthesis for gas-to-liquid applications is studied in this work. A base case of synthetic crude oil production is developed and is compared with three different alternative designs. Common tail gas recycling configurations from the Fischer-Tropsch products to the upstream units are investigated with and without carbon dioxide separation prior to the Fischer-Tropsch reactor in the three alternates. A kinetic model proposed for a nickel based catalyst is used for synthesis gas production and a cobalt based model is used for Fischer-Tropsch synthesis in the process simulation. Process optimization was carried out, for economic evaluation of different designs, subject to a well-defined and concise set of constraints. Economics of all four designs are evaluated by the Aspen Process Economic Analyzer for a comprehensive and meaningful comparison.