Managing the process of underground coal gasification

Abstract

Purpose. The research purpose is to determine the efficiency parameter of the coal gasification process based on the analysis of the composition of combustible gases (Н2, СН4, СО) and the producer gas calorific value, depending on the methods of supplying the blast mixtures to the gasifier oxidative zone. Methodology. A laboratory setup is used to perform experimental research into underground coal seam gasification. Its constituent segments are a stand, branches for supplying blast and gas-outlet mixtures, as well as a flow control system. This setup makes it possible to model the coal seam occurrence according to the mining-geological conditions of its occurrence. When determining the gasification process efficiency, two methods of supplying the blast mixture are tested: through a blast injection well and combined method (blast injection well + controlled pipeline). The generated producer gas calorific value has been determined analytically according to the “additivity rule”, taking into account the concentration of each combustible gas and its calorific value. Findings. The underground gasifier efficiency when changing the method of supplying the air mixture has been substantiated. Based on qualitative data on the concentration of combustible gasifier gases at the outlet of a modeled underground gasifier, conditions for increasing their concentration have been characterized and time intervals have been determined, through which their decrease occurs with increasing outgassed space. Originality. It has been revealed that the use of combined blast method in an underground gasifier causes a double supply of oxidizing agent to the gasification zone. This intensifies the gasification process by expanding the gasification reaction zones both along the length of the gasification column and along the seam thickness. Also, the combined method of supplying the blast mixture is characterized by improved thermal stability and gas formation parameters. Practical value. The research results make it possible to quickly make technological decisions for changing the operating modes of the underground gasifier, as well as determine the optimal method for supplying air mixtures, which improves the quality and calorific value of the producer gas. When changing the blast supply method to a combined method, the average concentration of Н2, СН4 and СО combustible gases increases by 3.85 %, and the calorific value increases by an average of 0.53 MJ/m3.