Energy recovery evaluation method of underground coal gasification process based on stoichiometry theory

The evaluation on the energy recovery of underground coal gasification (UCG) process is of great significance to the effective control of entire underground coal gasification process. The evaluation includes the design, monitoring, calculation and analysis of key parameters required for the evaluation of underground coal gasification, such as coal consumption, coal gas production rate and rate, calorific value of gasification products and gasification efficiency. In this paper, through UCG simulation experiment on selected coal samples, the influence of different linking hole methods and operation parameters are studied, and the evaluation method of energy recovery based on stoichiometry theory is established, and the energy recovery rate is defined. The experimental results show that the average heat value of the gas generated by the linked hole model is 10.26 MJ/m 3 (V-shaped channel) and 11.11 MJ/m 3 (L-shaped channel). The experimental results of the axial hole model were 7.38 MJ/m 3 and 4.70 MJ/m 3. The cavity volume of the link hole model experiment after gasification is about twice that of the coaxial hole model experiment. The results show that the type of gasification channel and the flow rate of gasification agent affect the coal consumption and the calorific value of generated gas. The type of linked hole gasification passage has great impact on the development of oxidation surface and fracture of subsequent gasification combustion in gasification zone. The evaluation method of gas energy JP2recovery based on stoichiometry proposed in this study is simple and reliable, and the error between the calculated results and the actual measured values is within 10%, which can effectively evaluate the amount of coal gasification, coal gas production and calorific value in the gasification process.