缝式低NO_x燃烧器结构的优化模拟

Structure optimization simulation of slit burner with low NO_x

天然气作为燃料具有效率高、污染物排放少等特点,但其燃烧时易产生局部高温,同时生成NO_x。因此天然气燃烧器的优化设计,对于天然气的清洁高效利用具有非常重要的作用。针对现有新型缝式低NO_x燃烧器进行结构改进,对改进后的结构进行模拟分析和实验验证,结果表明:在天然气管道上斜开圆孔,在降低NO_x排放方面有一定的效果,温度分布均匀性也得到了保证;当开孔方向与切缝方向一致时,高温区有所减小,烟气出口NO_x平均浓度降幅较大,且随着开孔角度的增大,烟气出口NO_x平均浓度逐渐减小;细缝左侧加挡板时烟气NO_x平均浓度降低,且随着挡板角度增加,烟气出口NO_x平均浓度先降低后增加,细缝左侧加30°挡板是最佳结构。与切缝方向一致时开孔50°是最佳结构。

Natural gas has the characteristics of high heat value,high efficiency,low cost and low emission when used as fuel.However,when natural gas is burned,the local high temperature region can easily appear,and NOx is generated.Therefore,the optimized design of natural gas burner has a very important role for cleanly and effectively use of natural gas.The structure of the existing new type of slit burner with low NOx is optimized.There are two ways to improve the structure:the oblique air holes are opened on natural gas pipeline,the diversion baffles are added next to the small slit.The software Fluent is used for numerical simulation,and the experiment on the optimized burner is carried out.The simulation results are well verified by the data measured in the experiment.The results on the optimized structure are obtained as following:round holes are oblique opened on the natural gas pipeline,compared with the original burner,the temperature distribution is more uniform and NOx emission is reduced.Round opening at the same direction with slit is better.When round holes are opened the same direction with slit in the natural gas pipeline,the average concentration of NOx in the flue gas outlet dropped a lot,and the average concentration of NOx decreases gradually with the increase of the opening angle.The effect of diversion baffles added on the right side of slits is not as good as the original structure.When the diversion baffles are added on the left side of the slits,the average NOx emissions in the flue gas outlet is reduced,and the NOx emissions decreases first and then increases with the increase of the angle of the flap.Holes at the same direction with slit angle of 50°on natural gas pipeline are the best choice in all cases.