煤粉炉内弥散介质辐射传热的综合模拟

本文基于辐射传热计算的DT法和颗粒运动计算的随机轨道法，并结合单颗粒的辐射特性模型，构造了能够详细考虑颗粒燃尽、湍流弥散诸因素对炉内空间局部辐射特性及总体辐射传热影响的弥散介质辐射传热计算模型，并将其耦合到炉内过程的总体数值模型中。采用该程序，比较计算了几种颗粒辐射特性模型对某300MW锅炉炉内温度场的预报结果，结果表明：通常采用的均匀颗粒辐射特性模型会导致温度场的极大误差；由于炉内颗粒浓度的不均匀分布，炉内的温度分布呈现高度非均匀状态，在炉膛轴线上有大面积的高温烟气区存在；考虑残炭存在时，温度分布的不均匀性更显著．

RADIATIVE HEAT TRANSFER OF PARTICULATE MATTERS IN PULVERIZED COAL FURNACE

A set of numerical codes were constructed to investigate the effect of different radiative properties model of particulate matters, such as char, ash and unburned char, on global radiative heat transfer in pulverized coal furnaces. The radiative heat transfer equation was solved by DT method. The radiative properties models of a single particle were based on Mie theory and effective optical constant of the particle. The radiative properties of dispersed media were gained by a sheme based on SSF model of particle motion.Three radiative properlies model of particulate matters were considered: (1) uniform model (2) char-ash model and (3) char-unburned char-ash model. The predicted result of a 300 MW pulverized furnace shows that great errors may caused by assuming the radiative properties of particle as uniform. A highly nonuniform temperature field were gained because of the nonuniform concentration of particles, which is enhanced by the existence of unburned char.