This paper introduces the situation of microwave modification technology for underground coal, analyzes the response characteristics of coal in a microwave field, describes common equipment, layout methods, and parameters, and discusses the technology's application scenarios. From the perspectives of basic research, equipment development, and field application, future research needs are proposed.

Abstract

Coal serves as the primary energy source in China. With mining challenges intensifying, alternative coal utilization pathways are crucial. However, high pressure, slow desorption, low permeability, and other characteristics of coal beds make it hard to ensure high and stable yield, so the coal modification is vital. Microwave technology features strong penetration, high efficiency, and pollution-free heating, which can enhance heat–mass transfer capacity and reaction efficiency in coal beds. This paper briefly introduces the response characteristics of coal in a microwave field, based on both physical experiments and simulation studies. It then articulates common microwave modification devices, arrangements, and key parameters. The application scenarios are discussed, including gas extraction, underground gasification, and in situ pyrolysis of coal in several major fields. Finally, addressing uncertainties in microwave response mechanism and the need for enhanced equipment and industrial application, this paper guides microwave coal seam modification efforts, emphasizing basic research, equipment innovation, and practical implementation for efficient coal utilization in China.