六棱柱滚筒冷渣机传热效率影响研究

冷渣机是CFB（circulating fluidized bed）锅炉的重要辅机，其传热效率对CFB锅炉的连续稳定运行发挥着重要作用，为了进一步分析颗粒传热效率的关系。以一种多管式六棱柱滚筒冷渣机为研究载体，冷渣管内高温灰渣颗粒为研究对象，基于离散元方法及其数值模型，运用商用软件EDEM（extended discrete element method）来模拟分析高温灰渣颗粒在冷渣管内的传热过程。将颗粒温度T规范化处理为量纲温度T?，以平均温度、温度概率密度函数T-PDF和颗粒运动规律为指标定量分析滚筒转速和颗粒直径对灰渣颗粒传热过程的影响。其中，六棱柱冷渣管边长L=200 mm，长500 mm，壁厚10 mm，管初始温度360 K，颗粒初始温度1200 K。结果表明：颗粒的传热效率随着转速的增加而增加，n=10 r/min相对于n=4 r/min的散热效率增加了61.1%；颗粒的传热效率随着粒径的增大而减小，d=5 mm相对于d=3 mm散热效率的下降了30.7%。转速是通过翻转次数来影响传热效率，粒径是影响接触点碰撞次数来影响传热效率。

Research on Heat Transfer Efficiency of Slag Cooler Based on Hexagonal Cylinder

Slag cooler is an important auxiliary machine of CFB (circulating fluidized bed) boiler, its heat transfer efficiency plays an important role in the continuous and stable operation of CFB boiler, in order to further analyze the relationship between particle heat transfer efficiency. Based on the discrete element method and its numerical model, the heat transfer process of high temperature ash particles in the cold slag tube was simulated and analyzed by using the commercial software EDEM. The particle temperature T is normalized to dimensional temperature T*, and the effects of roller speed and particle diameter on the heat transfer process of ash particles are quantitatively analyzed by taking the average temperature, temperature probability density function T-PDF and particle motion law as indexes. Among them, the side length of hexagonal cold slag tube is 200 mm, the length is 500 mm, the wall thickness is 10 mm, the initial temperature of tube is 360 K, and the initial temperature of particle is 1200 K. The results show that the heat transfer efficiency of particles increases with the increase of rotating speed, and the heat transfer efficiency of n=10 r/min is 61.1% higher than that of n=4 r/min; The heat transfer efficiency of particles decreases with the increase of particle size. The heat transfer efficiency of d = 5 mm is 30.7% lower than that of d = 3 mm. The rotational speed affects the heat transfer efficiency by the number of turns, and the particle size affects the heat transfer efficiency by the number of collisions at the contact point.