Fundamental Research on the Efficient, Clean and Safe Characteristics of Underground Coal Gasification Based on Microwave Heating

This study addresses issues such as suboptimal product quality and combustion control difficulties encountered during underground coal gasification by employing non-focused microwave technology to pre-treat coal pillars, thereby enhancing gasification efficiency. With Zhangminggou bituminous coal as the research subject, an underground gasification experimental system for non-focused microwave-modified coal bodies′ is established. The investigation systematically examined the impact of varying microwave parameters on the efficiency, cleanliness, and safety of underground coal gasification. Experimental results demonstrate that non-focused microwave radiation effectively improves coal gasification performance. Under optimized modification parameters, the average syngas content is increased from 42.39% to 44.67%, while the effective gas production time is extended from 0.90 h to 1.00 h. Meanwhile, minimal impact is exerted on tar concentration. Furthermore, analysis of the syngas explosion risk revealed that the duration within the explosive limits increased following modification. This indirectly indicates a more sustained and stable gasification process alongside improved product quality. This research provides experimental evidence for optimizing the underground gasification process through non-focused microwave modification, thereby enhancing product quality.