Numerical Simulation On Catalytic Combustion Of Coal Mine Ventilation Methane

Coal mine ventilation air methane is a kind of coal mine methane which emitted from mine ventilation air for safety mining. It's difficult to as the methane resource in it is dilute and variable,so it's discharged directly to the air usually and conducting energy wasted and environment pollution. It has double meanings with both energy conservation and environmental protection to develop the direct utilization technology of coal mine ventilation air methane.This paper study combustion characteristics of coal mine ventilation air methane in a honeycomb combustor by using CFD Fluent coupled surface reaction mechanisms of methane oxidation. The study is divided into two parts. The first part is the numerical simulation of coal mine ventilation methane in a honeycomb combustor loaded by Pd and Pt catalysts in the steady and constant wall temperature conditions. Comparing the catalytic performance of these two catalysts while the catalytic wall temperature, inlet velocity and inlet CH4 concentration changes in a certain range. Then choose a more suitable catalyst for coal mine ventilation air methane. On the basis of the first part, I study the starting situations of a simple combustion system in the non-steady and adiabatic conditions. Then research the influence of inlet fuel temperature, initial temperature of flow field, inlet fuel velocity, inlet CH4 concentration on the combustion system after it's stable.The study results of first part show that: Pd has a better catalytic activity then Pt in the same catalytic wall temperature. If the wall temperature is high enough, Pd can be better adapted to higher air velocity. At the case of significant reduction of inlet methane concentration, the two catalysts show comparable stability, both in the acceptable range. Integrated a number of catalytic activity performance, Pd is more suitable for the follow research. In addition, this part also optimizes the combustor structure, combustor length should be appropriate to shorten and the cell destiny could properly reduce.The study results of follow part show that: it can be calculated that CH4 conversion rate is 85%, temperature of outlet gas is 1140K in the boundary conditions for the initial flow field temperature is 300K, inlet fuel temperature is 850K, inlet velocity is 0.1m/s, inlet CH4 volume concentration is 1% as the starting operational conditions. The reduction of inlet fuel temperature has some negative effect on combustion efficiency. However, while the initial temperature of flow field is 1000K, the inlet fuel temperature down to 700K, the methane conversion rate is still 81%. The initial temperature of flow field is an important factor to determine overall performance of combustion system, should be maintained at more than 950K. Although the increase of inlet velocity can raise some power of system, but will result in a significant reduction in combustion efficiency. While the inlet volume methane concentration is 0.2%, as the minimum value in this calculation, although the efficiency of combustor is low, but response hasn't stagnation, the power is still able to maintain the combustion system operated stably.Results of this paper provide theoretical foundation to the experimental and reference to research and design of industrial technology.