Study Of Coal Mine Ventilation Air Regenerative Oxidization Device

Every year, about130-170billion m3methane is emited though the ventilation air of coal mines in our country. Ventilation air methane (VAM) has the characteristics of low methane concentration, huge volume flow and hard to concentrate. The conventional method to deal with it is discharging into the atomsphere directly. It is a great pollution and has a significant greenhouse effect to the environment. According to the above situation, in this paper a theoretical study and a numerical simulation of the VAM regenerative oxidation were carried out, a laboratory device for VAM oxidation is designed and constructed. The operating rules is explored by experimental study and the structure is optimize. By theoretical analysis and numerical simulation, the experimental data was analysed. The key parameters for the large-scale VAM oxidation device are determined. The heat extraction measure of a large-scale device is researched. The production and economy of the item is analysed.In this research, the theoretical analysis of the unsteady heat transfer process in the regenerative body was carried out, base on the regenerative heat exchanging theory, the self-sustained condition was analysed, and the volume factor as an important parameter of the self-maintenance performance was obtained.The calculation and design are made for a oxidation bed with a capacity of1000Nm3/h which consists of honeycomb ceramic. On the laboratory device, the certain temperature fields needed of oxidation bed is achieved within4hours by fuel gas heating system. The general starting mode of the experiment is also determined.Through the hot commissioning, the steady self-maintenance running of the device is realized which can persist more than200hours. The operating rules of the device are studied, including the performance on variable working condition, the working range and the influence of the parameters (inlet velocity, CH4concentration, switching time). Experimental results show that the device can keep steady self-maintenance running within inlet velocity from0.62to1.23m/s, CH4concentration from0.45%to0.9%. The average oxidation rate is more than95%. By the comparative experiment of regenerator's structures, the optimization of structures was attained.According to the experimental data, a calculation is made to prove the working condition by energy balance. The calculation results are close to the experimental data. The sensitivity of exhaust temperature, heat loss and oxidation rate to the floor level of CH4concentration for self-maintenance running is analysised. By the analysis of experimental results, the range of key parameters for the design and operation of demonstration device is determined.By dimensionless analysis, the floor levels of CH4concentration for self-maintenance running in various volume factor were calculated which was in accordance with the experimental results.Base on the experimental study, the value or the bound of the key parameters for large-scale VAM oxidation device are determined. The heat extraction measure of the large-scale device is researched. The production and economy of the item is analysed.