Critical analysis of underground coal gasification models. Part I: Equlibrium models – literary studies

Purpose
Underground coal gasification is a very difficult process due to changes in the parameters over time and within the space of the reactor and a variety of phenomena that occurs there. Consequently, it is necessary to create appropriate mathematical models, which simplify the optimization and forecast of future results (especially final gas properties). The purpose of this work was the detailed critical analysis of the simplest coal gasification simulations methods, based on thermodynamic calculations of the process. These models, called equilibrium models, can be divided into two groups: stoichiometric and non-stoichiometric. The other aim of this paper was to characterize various engineering methods used in the calculation of equilibrium gasification processes.
Methods
Literary studies, concerned with general aspects of underground coal gasification modeling and the modeling of coal gasification in the manner of equilibrium calculations, were used as a research method applied in presented in work.
Results
The critical analysis of equilibrium models of coal gasification and the characterization (including mathematical formulation of process, range of required parameters, rate of convergence of calculations and methodology of searching solutions) of stoichiometric and non-stoichiometric methods were results of numerous considerations presented in this article.
Practical implications
The presented work describes practical issues connected with equilibrium models – their advantages, limitations and possible problems (for example with the determination of required constants) and potential applications (preliminary analysis, point of reference to more complex simulations etc.).
Originality/ value
This paper presents state of art in filed of coal gasification modeling used equilibrium approach. This article also attempts to elaborate on the most important problems connected with thermodynamic models of coal gasification.