Investigation Of Preheat Catalytic Oxidation Characteristics Of Coal Mine Ventilation Air Methane

The ventilation air methane (VAM) has the characteristics of huge air volume flow, low methane concentration and the methane resource is dilute. It is difficult to be utilized and most of VAM is emitted to atmosphere directly. This treatment has caused huge energy waste and air pollution. It is significant to utilize VAM in a reasonable way.In response to this situation, the thesis tried to build up a preheat catalytic oxidation laboratory device to oxidize the VAM. The major components of the laboratory device were gas supply system, preheating system, heating starting system, reaction chamber, exhaust system and measurement and control system. The operating principle of the device, various components of those systems and the main parameters operating principle were introduced, and the experiments were designed.The starting characteristics of the preheat catalytic oxidation device were studied. The effects of air volume flow, heating power and the concentration of methane to the device’s starting characteristics were studied, and the best starting method is determined in the last. The results showed:under a certain air volume flow, the greater the heating power, the shorter the start-up time; under a certain heating power, the smaller the air volume flow, the shorter the start-up time, the less the consumption of electrical; under a certain air volume flow and the heating power, bubbling methane could help to reduce the start-up time; the best starting method of the device were heating power of20kW and the air volume of350Nm3/h.The combustion characteristics of ultra-low concentration of methane in the preheat catalytic oxidation device were experimental studied. The effects of inlet methane concentration, air volume flow and catalytic oxidation bed inlet temperature on methane conversation rate were studied, and the effects of inlet methane concentration and air volume flow on the temperature of methane complete conversion were also studied. The results showed:under the air volume flow and the bed inlet temperature were certain, as the inlet methane concentration increase, the methane conversion rate increase as well; under the inlet methane concentration and the bed inlet temperature were certain, as the increase of the air volume flow, the methane conversion rate decrease; under the inlet methane concentration and the air volume flow were certain, as the increase of the bed inlet temperature, the methane conversion rate increase as well; under the inlet methane concentration was certain, as the increase of the air volume flow, the temperature of complete conversion significantly increase as well; under the air volume flow was certain, as the increase of the inlet methane concentration, the temperature of complete conversion significantly decrease.Some energy balance of theoretical calculation was made of the laboratory device, and the feasibility of the device’s self-maintenance running was verified. The exhaust temperature and heat loss to the lowest of methane concentration for self-maintenance running was studied, and the result showed that:it is possible to improve the methane conversion rate by decrease the exhaust temperature and heat loss, so decreasing the lowest methane concentration of the device’s self-maintenance running is also feasible.