Numerical Simulation Of Low Concentration Coal Mine Methane Combustion In Porous Media Based On Local Non Thermal Equilibrium

Porous media combustion technology which is a new kind of combustion technology. It has great advantages in the energy recycling, extending the lean flammability limit, reducing pollution emissions and improving combustion efficiency and so forth. Burning low concentration coal mine methane(CMM) with porous medium combustors is an effective method. This thesis aims at effectively utilizing the low concentration CMM, and the theoretical study Based on local non thermal equilibrium on premixed burning property of low concentration gas in ceramic foam was conducted.According to a newly designed porous medium burner of low concentration gas, the physical and mathematical models for CMM combustion were established, and its governing equations were developed as well as their corresponding parameters were set. In the thesis, we simulated the combustion in two different conditions, that is, with or without internal heat source. The simulation results show that under the same initial condition, the combustion with internal heat source is superior to that without internal heat source, the maximum flame temperature increases, the lean flammability limit expands to 0.24, and the stable burning velocity range as well as the lean burning limit expand. Meanwhile, the flame front moves upstream gradually and the chemical reaction rate becomes faster. The heat quantity of the inner heat source increased, the stable burning velocity range is widened.Besides, we took advantage of numerical simulation to predict the combustion temperature at different preheating temperature and different pressures. The numerical simulations show that, with the increase of the initial temperature of, the maximum temperature of the combustion rises, the combustion zone has the trend of moving to the upstream of porous medium. When elevating the initial pressure of the premixed gas, the maximum combustion temperature increased, but the increase amplitude is small, and the flame has the trend to move downstream, but flame becomes more stable with the increase of pressure, temperature distribution becomes more even, combustion in porous is opposite to it in free space.