Study On The Process And Kinetics For The Deoxygenation Of Coal Mine Methane With Heating Coal Gangue

Coal mine methane (CMM) is a new kind of clean energy stored in coal seams and surrounding rocks during formation of coal. The explosion limit of methane in the air changes from5%to15%at ordinary temperature andpressure and expands rapidly as the temperature or pressure increases, so the utilization of coal mine methane severely limited as it mixed with air. Deoxygenation becomes the most technically challenging and expensive process in the utilization of CMM. There are many kinds of deoxidization methods. In this study we adopted the coal gangue as deoxidization material, which can not only reduce the cost, but also can make full use of coal gangue and reduce the pollution to the environment.In this paper, we studied the technologies of coal mine methane deoxidization by tube furnace and microwave heating furnace heating coal gangue. We optimized the process by controlling the temperature, gas flow rate, coal gangue particle size, and investigated the kinetics of combustion of coal gangue in the coal mine methane atmosphere, which will provide a reference for deoxidization process in industrial application, the main research contents and conclusions are as follows: (1)The temperature and gas flow rate are important factors influenced the deoxidization effect in the deoxidization process. With the increase of temperature, the O2concentration in outlet gas gradually reduced, but the methane loss rate also increased when the temperature is too high. Low flow rate lead to the increase of methane loss rate, but the efficiency of the deoxidization decreased when the flow rate is too high. The size of the coal gangue has little influence on the efficiency of the deoxidization.(2) In the process of deoxidization, higher temperature is benefite to the reaction of O2with carbon in coal gangue, but also can enhanced the cracking reaction of CH4, which reduced the recovery rate of CH4as the loss of methane is mainly caused by the cracking reaction.(3) The best technological conditions in the tube furnace deoxidization experiment is the heating temperature650℃, the flow rate of250ml/min,while650℃and300ml/min for the microwave heating coal gangue experiment. Heating coke has higher deoxidization efficiency than that of heating coal gangue when compared the in the deoxidization experiments, but the loss rate of methane is relatively larger.(4) When coal gangue combustion in CMM atmosphere, the Ti, Tb, and Tmax decreased with the increasing of oxygen concentration, but (dW/dt)max and (dW/dt)mean show the opposite rule. When compare the combustion of the coal gangue in the coal bed methane atmosphere and at the same oxygen concentration of O2/N2atmosphere, we found the mass loss was smaller under coal mine methane atmosphere beacause of the existence of CH4.(5) When coal gangue combustion in the atmosphere of coal mine methane, the combustion of combustible components with oxygen is the main reaction under the low temperature, the methane with oxygen and the H2cracked from methane react with oxygen become the primary reaction when the temperature is higher. The E values of coal gangue combustion vary from117.6to137.4kJ/mol under different atmospheres. It is slightly higher in the CMM atmosphere than in the O2/N2mixture with equivalent oxygen concentration.