75 t/h循环流化床锅炉气固流动与燃烧的数值模拟

Numerical Simulation on the Gas-Solid Flow and Combustion in a 75 t/h Circulating Fluidized Bed Boiler

以75 t/h循环流化床锅炉为研究对象,采用数值模拟方法,对其物料流动与燃烧时NO_x排放特性进行研究。通过计算分析燃料颗粒轨迹和改变过量空气系数来研究炉膛出口污染物NO_x的生成分布情况,给出了入炉颗粒球形度对流态化的动态影响。数值模拟结果表明,以污染物NO_x生成量为主要考虑因素时,该锅炉炉膛的过量空气系数宜选在1.10~1.15之间,最佳燃烧工况宜选一、二次风比例为1∶1,过量空气系数为1.12。该数值模拟结果为优化循环流化床锅炉燃烧提供了实际参考,具有一定的工程应用价值。

The numerical simulation method was used to study the material flow and NOx emission characteristics of a 75 t/h circulating fluidized bed（CFB） boiler. The formation and distribution of the pollutant NOx at the furnace outlet was studied by calculating the trajectory of fuel particles and changing the excess air coefficient. At the same time, the dynamic effects of sophericity of particles on the fluidization were given. The numerical simulated results show that the excess air coefficient of the boiler furnace should be selected between 1.10 and 1.15, and the optimized combustion condition is further determined. The ratio of primary air to the second air should be 1：1, and the excess air factor should be chosen as 1.12. The results provide a practical reference to the combustion optimization in a CFB boiler, and are valuable for engineering applications.