循环流化床锅炉后补燃风掺混的试验与数值模拟

Experiment and numerical simulation of air mixing for post-combustion at circulating fluidized bed boiler

针对冷态模拟试验台,利用计算流体力学方法研究后补燃风喷嘴布置高度、喷嘴数量以及后补燃风比例对后补燃风与一次风掺混效果的影响;采用Realizable k-ε湍流模型计算不同截面上的速度,并与冷态模拟试验台上的试验结果进行比较。结果表明:计算值与试验结果吻合;后补燃风喷嘴布置在试验段烟道下部、中部及以上时掺混相关系数稳定在0.6左右;喷嘴布置在试验段烟道下部时减少喷嘴数量,布置在上部时增加喷嘴数量,底部和上部增加后补燃风比例会均能提高掺混效果。

Factors of influencing mixing effect of post-combustion air, such as the position of post-combustion air nozzles, the number of nozzles, and the proportion of post-combustion air were studied using computational fluid dynamics method. The velocity in different section planes with Realizable k-ε turbulent model was compared with the experimental data on a cold simulation test platform. The results indicate that the numerical results agree well with the experiments. When the post-combustion nozzle is arranged on the lower part of the test section flue and above of it, the mixing correlation coefficient is about 0.6. When the nozzles are arranged on the lower part of the flue, they are better to reduce the nozzles number to increase the momentum ratio. To the upper part of the flue, it needs to increase the number of nozzles to increase the jet area. Increasing the proportion of the post-combustion air in the bottom and the upper part of the flue will improve the mixing effect.