ABSTRACT
This chapter focuses on thermodynamic models and reaction engineering models for underground coal gasification (UCG). It discusses thermodynamic equilibrium calculations made by using equilibrium constants. The application of thermodynamic models is valuable at the initial stages of analysis as it predicts the thermodynamic limits of the gasification process. The predictions from the thermodynamic models are computationally inexpensive and faster. The predictions of the thermodynamic models become more accurate for the bigger isothermal reactors as they provide more residence time to reach equilibria. The high residence time and higher temperature may not be a reality in all cases, and therefore the thermodynamic models should be used very carefully. The chapter also discusses the development of general modeling strategies for packed bed models, cavity models, and coal block models. It presents the results of solving the equations and compares them with the published experimental and simulation results as reported in A. Singan.
