Studies On Structural Design Optimization Of Low Calorific Value Coal-bed Gas Burner

Calorific value of coal bed methane that contains 30% methane concentration is lower, the use is difficult, when combusted with coal gangue in CFB or directly applied steam boiler, there will be many problems if apply conventional burner for example combustion instability, flame penetration is not enough and so on,this has resulted in lower combustion efficiency, larger pollutant emissions, unstable operation and other issues. Therefore, the research and development of low calorific value coal bed methane burner has important industrial application value and academic significance.On the basis of analyzing the advantages and disadvantages of burners, the burner is design for the low calorific value coal bed methane. Fluent numerical simulation is used,the optimal ratio of swirling wind and straight wind,the best guide vane angle and blade number are gained, and further analyze the advantages and disadvantages for both before and after improvement burner. The loss of flowing resistance with the change of load and the relationship between swirl intensity and excess air ratio are studied in cool state experiment. Burner flame characteristics and the distribution of temperature field are studied in hot state experiment.Adopting finite rate model, Realizable k-εturbulent model and the P-1 radiation heat transfer model to simulate burning of burner, the results show that when the swirling wind accounted for 20%, straight wind shared 80% of the wind, the air jet not only has strong strength, which improved the stiffness of the jet flame post, but has a strong swirl intensity, which improved mix of the gas and air; When guide vane angle is 60 degrees and the number of guide vane is 6, it is not only conducive to the protection of the burner nozzle, and mass fraction of methane decreased rapidly along the central axis, complete combustion. The temperature of the optimized burner increased faster along the central axis than the original burner. Temperature peak is closer from the nozzle, Effect of stable combustion is better than the original burner.The cold state experiment shows that as the load increases, the burner pressure loss and swirl intensity of the center of the burner nozzle exit are also increasing. In the same load, swirl intensity does not vary with excess air ratio changes. The hot state experiment shows that the optimized burner at different heat load can stably combust, flameout occur and no backfire; The temperature of the optimized burner increased faster along the central axis than the original, high temperature peak, high temperature region are widely distributed along the radial direction.The experimental results and numerical simulation results are basically consistent with the maximum error is 9%, indicating that the experimental results and numerical simulation results are reliable.