Underground coal gasification (UCG) is an important technique for future coal utilization. It has the potential to be a clean technology and to tap un-mineable, deep coal deposits across the world. Commercialization of UCG has been riddled with a variety of issues, including public perception and a lack of clear comprehension about underlying physicochemical phenomena. This book will bridge the gap in knowledge and highlight the modern findings related to the complex interactions in UCG. With a focus on the chemical reactions in UCG and treating the underground coal cavity as “nature’s own chemical reactor”, various mathematical modeling studies that serve to unravel some of the mysteries of this decades-old technique will be revealed.

The book deals with development of comprehensive computational models for simulating underground coal gasification (UCG). It starts with an introduction to the UCG process and process modelling inputs in the form of reaction kinetics, flow patterns, spalling rate, and transport coefficient that are elaborated with methods to generate the same are described with illustrations. All the known process models are reviewed, and relative merits and limitations of the modeling approaches are highlighted and compared. The book describes all the necessary steps required to determine the techno-economic feasibility of UCG process for a given coal reserve, through modeling and simulation.

The book deals with development of comprehensive computational models for simulating underground coal gasification (UCG). It starts with an introduction to the UCG process and process modelling inputs in the form of reaction kinetics, flow patterns, spalling rate, and transport coefficient that are elaborated with methods to generate the same are described with illustrations. All the known process models are reviewed, and relative merits and limitations of the modeling approaches are highlighted and compared. The book describes all the necessary steps required to determine the techno-economic feasibility of UCG process for a given coal reserve, through modeling and simulation.

The following report is a description of a 7 year effort to develop a theoretical understanding of the underground coal gasification process. The approach used is one of the mathematical model development from known chemical and principles, simplification of the models to isolate important effects, and through validation of models to isolate important effects, and through validation of models with laboratory experiments and field test data. Chapter I contains only introductory material. Chapter II describes the development of two models for reverse combustion: a combustion model and a linearized model for combustion front instability. Both models are required for realistic field predictions. Chapter III contains a discussion of a successful forward gasification model. Chapter IV discusses the spalling-enhanced-drying model is applicable to prediction of cavity growth and subsidence. Chapter VI decribes the correct use of energy and material balances for the analysis of UCG field test data. Chapter VII shows how laboratory experiments were used to validate the models for reverse combustion and forward gasification. It is also shown that laboratory combustion tube experiments can be used to simulate gas compositions expected from field tests. Finally, Chapter VII presents results from a comprehensive economic analysis of UCG involving 1296 separate cases. 37 refs., 49 figs., 12 tabs.