Thermodynamic Analysis and Optimization for the Coal-Based Clean Liquid Fuel Synthesis Process

Abstract

This work makes thermodynamic analysis and optimization for the coal-based Fischer-Tropsch (FT) process. The thermodynamic analysis results show that under standard conditions the maximum effective carbon conversion is 50% from raw coal (CH0.8O0.1) to hydrocarbon products, and at least 50% carbon is converted into CO2 emission in the coal-based FT process. Subsequently, a new coal-based FT synthesis process is proposed to get minimum water consumption, minimum wastewater emission and maximum energy efficiency. The process contains a pulverized coal gasification unit, water-gas-shift unit and iron-based FT synthesis unit with 50% CO2 selectivity. The H2/CO molar ratio of fresh syngas to the FT synthesis unit is 0.5. The carbon and water footprints analysis results indicate that the effective carbon conversion from raw coal to hydrocarbon products is about 46.0%, and it only consumes 0.102 molar water and generates 0.032 molar wastewater when converts 1 molar coal to hydrocarbon products in the process.