ABSTRACT
This chapter presents a review of the literature on underground coal gasification (UCG) field trials and fine details of various aspects including reactions and physical properties and their relevance in process modeling. It summarizes important aspects of UCG, like coal gasification reactions, spalling, and flow patterns. The chapter discusses the status of UCG technology and different methods of UCG with their development history. It describes the different processes that occur underground inside the UCG cavity. At high temperature and with a high degree of pyrolysis, the coal particles from the coal seam above the cavity get affected in such a way that they start falling onto the floor of the cavity. The chapter also describes the field-scale experimental studies that provide insight into the UCG process and a better understanding of the important fundamental aspects. A moderate coal-seam depth and thickness are also important for a highly successful UCG trial.
