Evaluation of synthetic gas harmful effects created at the underground coal gasification process realized in laboratory conditions

Underground coal gasification (UCG) is an industrial process that provides an alternative to conventional underground mining at coal seams that are located especially deep underground. This process converts coal into product gas (syngas). The product gas composition depends on the coal geology and the gasification parameters. The coal (coal seam) and oxidant (a mixture of the oxygen and air) are input to the gasification process, and their valid combination should provide better conditions of gasification. The fracturing, cracks and also operating failures occur inside the gasification zone and surrounding rocks during the underground coal gasification process as the underground coal cavity evolves. There was only a little research focused on their effects to date, although these causes directly affect the gasification efficiency and have the environmental impacts. The paper describes the analysis of the harmful impact of the produced gas on the vulnerable area in terms of possible poisoning and potential explosion by using a mathematical model for mixing gasses. The analysis is performed using four laboratory experiments realized on two gasifiers. The harmful effects of the produced gas are compared for the different gasification method of the individual experiments by taking into account the low and high heat capacity obtained. The obtained heat capacity is determined by a mathematical model for the heat balance of the output components.