Thermodynamic Simulation Of Entrained Flow Gasification Process With Different Transmission Media

China is short of petroleum and nature gas but rich in coal resource. It is very important to increase utilization of coal for making up the energy require. Coal gasification technology is critical for modern coal chemical technologies. The products of coal gasification provide feeds for downstream chemicals and chemical process as syngas, fuels or reducing gas. So it is meaningful to develop coal gasification technology for improving deep, clean and efficient utilization of coal.Entrained flow gasification has a wide application range of raw materials, large gasification capacity and carbon conversion efficiency. It was suitable for large-scale utilization and was developed most at home and abroad. Nowadays, entrained flow gasification includes pulverized coal gasification and coal-water slurry （CWS） gasification. Pulverized coal gasification has large carbon conversion and low oxygen consumption, but weak coal feeding stability and high gasification temperature. The total energy consumption of pulverized coal gasification is larger than CWS gasification. CWS gasification has high coal feeding stability, low gasification temperature. But due to the heat loss of water evaporation, the thermal efficiency of CWS gasification is lower than the former. In order to reduce the quantity of gasification process and improve the thermal efficiency of CWS gasification, liquid carbon dioxide are used as the coal slurry transport medium instead of water which study has get a great attention.In this paper, entrained flow bed gasification was studied based on Aspen Plus through the Gibbs free energy minimization method with water and liquid CO₂ as the transport medium of coal, respectively. Cold gas efficiency and syngas compositions were investigated under difference percentages of feeds. Ternary diagram was adopted to draw O2-H2O（CO₂）-Coal diagram with isolines of cold gas efficiency. It was found that the region where cold gas efficiency of CO₂-coal slurry gasification （CCS） was higher than CWS was in the center of the diagram. Regions where cold gas efficiency of CCS was less than CWS were more close to the edges. From the influences analysis of slurry concentration, oxygen-coal ratio, gasification temperature and the carbon conversion rate, it was found that relative to CWS gasification, CCS gasification products had more CO but less H2. Under the situation of slurry concentration 66.5%, oxygen-coal ratio 0.86, carbon conversion 99% and thermal loss 2%, the cold gas efficiency of CCS gasification was 0.56% higher than CWS gasification. When changing the oxygen-coal ratio to maintain gasification temperature 1488℃, the cold gas efficiency of CCS gasification was 4.33% higher than CWS with a lower oxygen-coal ratio 0.78. It was found by exergy efficiency calculation analysis that exergy efficiency of CCS was 1.4% higher than CWS at the same original situation. As slurry concentration increasing from 58% to 74%, exergy efficiency of CWS gasification increased 1.44% and CCS gasification 3.21%. With the increase of the oxygen-coal ratio, exergy efficiency of CCS decreased first and then increased while exergy efficiency of CWS reduced gradually with slowing down speed.