Numerical Simulation Of Coal Mine Ventilation Air Preheating Catalytic Oxidation

China is a county with much more coal energy,and the methane discharged into atmosphere annually by the coal mine VAM not only cause a huge waste of clean energy,but also pollute the atmospheric environment.Because of low concentration,wide fluctuation range,huge volume flow and other characteristics,it is difficult to utilize the coal mine VAM in traditional ways.Based on the preheating catalytic oxidation device designed and built by Shandong university of Technology,the catalytic oxidation process and equilibrium state of ventilation air methane were numerically simulated.The main contents include:Three-dimensional single-channel model was established by experimental ceramic model,the size of the model was 1.8*1.8*350mm and wall thickness of the model was 0.2mm.Although methane reaction in ceramic surface with Pd-based catalysts includes complex series of physical and chemical reactions,it still complies with the basic equations of continuous,energy and momentum.Concrete form of equations was given.Kinetics model needs to be imported in the course of a single-channel analog methane catalytic oxidation reactions,the establishment of a kinetic model was described.The catalytic oxidation process of ventilation air methane was numerically simulated,and compared with the experimental data.As a result of the simulation conditions are idea and may also existed local air leakage in the experiment lead to simulated data is slightly higher than the experimental data.But in terms of ceramic axial temperature distribution,the simulation results are basically identical with the experimental result.As the coal mine VAM flow,catalytic oxidation of methane occurs continually and the axial temperature of oxidation bed increased.Simulation and calculation method can be considered to choose the right model.After verifying the model is correct,effect of various operating parameters including preheating temperature,space velocity on the concentration of methane oxidation bed temperature and methane conversion rate was studied.It concluded that as the preheat temperature and methane concentration increasing,bed temperature of the field oxide is increased and the methane conversion rate is increased too.With the space velocity increasing,the temperature field and the oxidation bed methane conversion rate is reduced.Three-dimensional model was established on the base of experimental device to simulate the self-heating maintain status.To simplify the model,the preheater with complex structures was eliminated.Processing the preheater is fitted the corresponding experimental data according to the formula.The corresponding relationship was established between the temperature of the gas and the preheating temperature.Then the gradual iterative method was used to simulate the methane catalytic oxidation.The self-heating maintain status of the catalytic oxidation of methane at various conditions was simulated,and compared with the experimental result.It can be seen from the comparison that the results of the self-heating thermal simulation and experiment was basic agreement.Therefore,it can be considered that the methods to simulate self-heating maintain status is reasonable.Energy calculation was made about the self-heating maintain status.To calculate the energy of the flue gas energy that the device can be recycled using heat energy = heat loss + smoke catalytic oxidation reaction of methane released.Using simulated from the heat while maintaining the same calculation method for the expansion of the state coal mine ventilation air preheat section of the catalytic oxidation unit increase deflector when the numerical simulation,simulation studies spoiler increases the catalytic oxidation of methane to achieve self-heating to maintain the state of,and give some suggestions experiment.Using the same methods with the self-heating maintain status to simulate the self-heating maintain status with deflector in the expansion and give some suggestions to experiment.Compared with the self-heating maintain status without deflector,it showed that the temperature of reaction chamber with deflector was higher and can reduce the waste of energy.