基于渣层增长模型的水冷壁背火侧温度表征特性

Characterization of the Temperature on the Back Side of the Water Wall Based on Slag Layer Growth Model

以某台600 MW超临界锅炉为研究对象,提出了渣层增长模型,考虑焊脚结构对导热的影响建立了结渣水冷壁物理模型,并采用Fluent模拟了不同工况下结渣水冷壁的温度分布,根据240组工况模拟结果,分析了背火侧温差与锅炉关键运行参数的关系。结果表明:渣层表面温度主要取决于炉膛烟温的变化,背火侧温差(背火侧管壁中点与背火侧鳍片中点之间的温差)受结渣影响明显,可作为诊断结渣厚度的特征参数;背火侧温差与炉膛烟温呈接近线性的正相关关系,其随管内工质对流传热系数的增大而减小,并趋近于一个恒定的温度;在锅炉正常负荷范围内,管内工质对流传热系数对背火侧温差的影响要小于炉膛烟温,但工质温度对其影响基本可以忽略。

Taking a 600 MW supercritical boiler as the research object,the slag layer growth model was proposed,and the slagging water wall physical model was established considering the influence of the weld foot structure on the heat conduction.Fluent was used to simulate the temperature distribution of the slagging water wall under different working conditions.According to the simulation results of 240 sets of working conditions,the relationship between the temperature difference on the back side and the key operating parameters of the boiler was analyzed.Results show that the surface temperature of the slag layer mainly depends on the change of the furnace flue gas temperature,and the temperature difference(the temperature difference between the midpoint of the pipe wall and the midpoint of fins on the back side)is obviously affected by slagging,which could be used as a characteristic parameter for diagnosing slagging thickness.The temperature difference of back side and the furnace flue gas temperature is close to a linear positive correlation,which decreases with the increase of the convective heat transfer coefficient of the working medium in the tube and approaches a constant temperature.Within the normal load range of the boiler,the influence of the convective heat transfer coefficient of the working fluid on the back side temperature difference is smaller than that of the furnace flue gas temperature,but the influence of working fluid temperature on it is basically negligible.