Thermodynamic analysis of coal gasification processes

Abstract

Thermodynamic analysis for evaluating and improving coal gasification process efficiency requires estimation of enthalpy, entropy, and availability transformations in various process steps. A compilation of procedures and data relevant to coal gasification processes is presented for calculating the above thermodynamic properties. Enthalpy and availability transformations are estimated for significant process steps in the HYGAS ® process for ptoducing substitute natural gas from coal. The thermal efficiencies based on the first law of thermodynamics are compared with the availability efficiencies based on the second law. Work intensive process steps, such as gas compression and separation, are shown to have extremely low thermal efficiencies and fairly high availability efficiencies. Heat intensive process steps, such as steam generation, have high thermal efficiencies but generally poor availability efficiencies.