MONITORING AND MEASUREMENT OF THE PROCESS VARIABLES IN UNDERGROUND COAL GASIFICTAION

Underground Coal Gasification (UCG) represents processes of thermic decomposition of coal in underground with use of injected oxidizer. Underground coal gasification is a mining method that utilizes injection and production wells drilled from the surface and linked together in the coal seam. The coal is transformed to syngas which can be used for the electricity production. By this technology is possible to mine coal seams which are not available for conventional mining and newly discovered coal seams with tectonic faults. In UCG can be monitored various process variables which can be used for evaluation of process behavior and for control. The paper deals with the analysis of such variables and especially solves indirect measurement of underground temperature from the syngas composition. Paper analyzes the possibility of indirect measurement by carbon isotopes and from ratio of CO and CO2 concentrations. Discussed is monitoring of gas leaks from underground to the surface of vulnerable area, monitoring of surface subsidence and cavity enlargement. This paper summarizes recent development in the field of the UCG monitoring and measurement and presents some results from academic research and experimental gasification.