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利用数值模拟方法对余热锅炉中心供风烟道式补燃装置的气体扩散燃烧特性进行研究。在燃气流量为20 m3/h的工况下对比轴向温度分布和出口NOx浓度分布的数值模拟与试验结果,二者吻合良好,证明了计算模型的正确性。通过进一步的计算表明:随过剩空气系数增加、空气含氧量增大或空气温度的降低,气体主流最大速度上升,而主流最大速度区域、速度衰减特性及CH4组分的轴向和径向分布变化不大;在低过剩空气系数、高含氧量、高空气温度时,火焰呈“细长”型;反之,火焰呈“短粗”型;在低过剩空气系数、低含氧量、高空气温度时,火焰的温度分布更为均匀;增加过剩空气系数及降低空气含氧量和空气温度,可有效减少出口NOx排放;出口CO浓度仅与过剩空气系数(即空气流量)有关,与空气含氧量及空气温度无关。
The gas diffusion combustion characteristics of the air supply flue-type afterburner at the center of the waste heat boiler were studied by numerical simulation. Comparing the axial temperature distribution and the distribution of NOx concentration at the gas flow rate of 20 m3 / h, the numerical simulation and experimental results agree well with each other, which proves the correctness of the calculation model. Further calculations show that with the increase of excess air coefficient, the oxygen content of air increases or the air temperature decreases, the maximum velocity of gas increases, while the velocity attenuation characteristics of the maximum velocity region and the axial and radial distribution of CH4 components The results showed that the flame was “slender” in the condition of low excess air coefficient, high oxygen content and high air temperature. On the contrary, the flame was “stubby” Oxygen and high air temperature, flame temperature distribution more uniform; increase the excess air coefficient and reduce the air oxygen content and air temperature, can effectively reduce the export of NOx emissions; export CO concentration only with excess air coefficient (ie, air flow) Related to the oxygen content of the air and air temperature has nothing to do.