附加鳍片对CFB锅炉膜式水冷壁管屏热变形影响的数值分析

Numerical Analysis on Influence of Extra Fin on Thermal Deformation of Membrane Water Wall Tubes in a CFB Boiler

基于世界首台600 MW超临界循环流化床(CFB)锅炉实炉实验数据,采用ANSYS软件建立高度×宽度为4.6 m×2 m的膜式水冷壁管屏计算模型,开展了100%BMCR(锅炉最大连续蒸发量)工况下水冷壁管屏热变形的数值模拟,分析了背火侧附加鳍片及其尺寸对水冷壁管屏热变形的影响。结果表明:由于炉内热负荷分布不同,随着炉膛高度的增加,水冷壁管屏向火侧热变形先增大后减小,在炉膛高度39.5 m处达到最大值,最大热变形量为1.43 mm;在水冷壁管背火侧焊接一块附加鳍片,可有效减小水冷壁管屏热变形,当附加鳍片尺寸为6 mm×4 mm时,水冷壁管屏向火侧热变形量减至0.57 mm。

Based on the experimental data of the first 600 MW supercritical circulating fluidized bed(CFB)boiler in the world,the calculation model of 4.6 m×2 m membrane water wall tubes was established by ANSYS software.Numerical simulation of the thermal deformation of water wall tubes under 100%BMCR(boiler maximum continuous evaporation)condition was carried out,and the influence of extra fin on the backfire side and their sizes on the thermal deformation of the tubes was analyzed.Results show that due to different heat load distribution in the furnace,with the increase of the furnace height,the thermal deformation of water wall tubes towards the fire side firstly increases and then decreases,reaching the maximum value(1.43 mm)at the furnace height of 39.5 m.Welding an extra fin on the backfire side of the water wall tube can effectively reduce the thermal deformation of water wall tubes.When the size of the extra fin is 6 mm×4 mm,the thermal deformation of the water wall tube towards the fire side is reduced to 0.57 mm.