As is known to all, the methane concentration in the ventilation air of coal mine is very low, which cannot be directly utilized, with a huge total amount of methane, resulting in significant greenhouse effect. Data show that China's annual greenhouse gas effect from methane released into the atmosphere from ventilation air methane (VAM) is about 200 million tons of carbon dioxide equivalent. Therefore, it is of great significance to study how to increase the concentration of methane economically and to make energy utilization. In particular, the Paris agreement put forward by the 21st conference of the parties to the United Nations framework convention on climate change recently requires the world to reach the peak of greenhouse gas emissions as soon as possible. The Chinese government has also made the commitment of reducing emissions from climate change. The only way for the coal industry to survive and develop is to popularize the technology of the scavenging gas concentration, destruction and utilization. This paper systematically summarizes the realization approach, technical objective and current situation of the utilization technology of VAM enrichment technology at home and abroad, and prospects its application prospect and new research direction.

In this study, three-dimensional numerical simulations were established for a honeycomb ceramic conduit, and the effects of the inlet methane volume fraction, inlet velocity, and the conduit length on the gas temperature and flow resistance in the conduit were investigated. The simulation results indicate that the mean gas temperature first rises rapidly and then slowly, with an increasing inlet methane volume fraction. The mean gas temperature increases slightly with an increasing inlet velocity, and first increases and then decreases with an increasing conduit length. As the inlet methane volume fraction increases, the conduit pressure loss increases, but the increase rate gradually slows down. The conduit pressure loss increases approximately linearly with an increasing inlet velocity and conduit length. A prediction model for the pressure loss in the conduit was obtained by a theoretical analysis. The theoretical results agree well with the simulation results, and the deviations between the theoretical and simulation results were in the range of 3.7% to 12.3%. When the mean gas temperature in the conduit was less than 1000 K, the deviations were less than 6.5%.

In order to solve the problem of low concentration coal mine methane (CMM) emission and low utilization rate in coal mine and the underground refrigeration demand of coal mine, this paper puts forward a technology of regenerative thermal oxidation (RTO) to provide waste heat vapor for lithium bromide refrigeration unit, which can effectively solve the problem of low concentration CMM utilization and provide stable heat source output for the refrigeration unit. The integrated process of oxidizing heat supplying to refrigerating unit includes low concentration CMM transportation security system, CMM RTO system and waste heat utilization system. The designed methane concentration is 1.2%, with flow rate 100, 000 Nm³/h, and steam heat of 7537kW. The expected effect of project operation is analyzed, and the economy of the project is demonstrated. The technology of CMM RTO supplying steam for underground refrigeration, through the destruction of methane, and the output of heat for underground refrigeration, has multiple meanings of energy saving and emission reduction, improving the utilization efficiency of coal bed gas in coal mine area, and promoting the safe production of coal mine.

Based on coal mine methane (CMM) emission policy in China and other main coal-mining countries in the world, a status quo of dilute methane (such as ventilation air methane (VAM) or similar concentration methane) reverse flow reactor (RFR) technology was looked back and the principal of the reverse flow reactor for dealing with dilute methane was introduced in detail. The development of the dilute methane RFR technology was carded and the main research directions and processes in this field were described, including reaction kinetics mechanism of dilute methane in the inert homogeneous channel, reaction heat front reverse movement rule in the RFR, numerical simulation of the RFR mathematical model, NOx emission of the RFR process, large-scale RFR experiments, and so on. The contradictions existed in the relative research of dilute methane RFR technology were discussed, and the evolution of the dilute methane RFR technology was predicted. And it would be necessary guidance for the scientific study, numerical simulation, optimization design and engineering application of the dilute methane RFR technology.