The Theory And Experimental Investigation Of Ventilation Air Methane Catalytic Oxidation And Carbon Dioxide Fixation

Ventilation air methane(VAM), emitted from coalmines, cause serious environment pollution and exacerbate the greenhouse effect. VAM have high airflow volume, low concentrations of methane gas and flow instability characteristics, which limit its application in industry. Direct oxidation processing of VAM is a great waste of energy. Thus, designing a new technology for VAM, which can be applied to production, is important for environmental protection and sustainable development of energy resources.This paper describes the status of VAM emissions, reviewes the result researchers get in the study, and introduces the typical technologies which use VAM as the main fuel: thermal flow reversal reactor(TFRR), catalytic flow reversal reactor(CFRR) and catalytic monolith reactor(CMR). Compared the advantages and lack of these techniques. Choose catalytic monolith reactor and design new combustion system on the basis of the analysis. Through the selection and arrangement of catalysts and carbon sequestration, test reduction effect for VAM.Based on the chemical reaction software CHEMKIN, simulate catalytic oxidation process carried out in a honeycomb ceramic for VAM, compare methane conversion rate of change, further analysis of preheating temperature, intake air density, flow velocity, catalyst specific surface area and catalyst pore density on the influence of the oxidation process. The results showed that the catalyst can reduce the complete conversion temperature of methane. Through improve the methane inlet concentration, concentration is increased to facilitate the reaction zone forward, as well as decreases the affect of the flow velocity, reaction is more stable. Under the same operating conditions, increase the surface area or catalyst pore density contribute to improved the conversion rate.Pd/Al2O3 monolithic catalysts and LaMnO3/MgO monolithic catalysts were prepared by sol-gel and impregnation methods. The structures and properties of these catalysts were studied by XRD and SEM. The catalytic combustion activity and the thermal stability of these catalysts were investigated. The experimental results show that, the catalytic activity of Pd/Al2O3 monolithic catalysts performs better than LaMnO3/MgO monolithic catalysts for catalytic combustion of lean methane(0.5%) at low temperature. Calcine these catalysts for 24?h at 800??, the methane conversion rate of Pd/Al2O3 monolithic catalysts drops to 87.15%, while the methane conversion rate of LaMnO3/MgO monolithic catalysts reaches 97.12%. LaMnO3/MgO monolithic catalysts has better thermal stability. Staged combustion for ventilation air methane can reduce ignition temperature to promote reaction and to guarantee the thermal stability at high temperature. Set Pd/Al2O3 monolithic catalysts as the first stage and LaMnO3/MgO monolithic catalyst as the second. Set CaO at the final section and preheat the lean methane(below 1%) to 500??. The concentration of CO2 in the exhaust gas is less than 0.2%, which achieve near-zero emissions of greenhouse gases.Design ventilation air methane staged catalytic oxidation and carbon dioxide fixation of heating systems, analyzes the reaction temperature of each device and each process, through the utilization of waste heat, improve the economic efficiency. Analysis of carbon reduction benefits and thermal economic benefits, the system still short payback period and high return on investment, and has broad market prospects.