600MW锅炉热态下水冷壁流量分配特性研究

Flow distribution characteristics of water wall in a 600MW unit boiler in thermal state

在建立管壁受热模型的基础上,通过对炉内进行区域分段,研究了炉膛内水冷壁沿高度方向上的热负荷分布情况。通过以在水平方向上的热负荷分配系数为媒介,将沿高度方向上的热负荷转变为沿水平方向上的热负荷分布,以水冷壁区段在水平方向上所受热负荷最大和最小两极限位置处为例,进行在热态下水冷壁入口处调节阀开度的计算,提出了通过工质传热系数对工质进行饱和水、汽水混合物、过热蒸汽相态区段的划分,以沿炉周最高负荷位置处(即相对宽度0.54处)水冷壁管为计算基准,计算各相态区段的压降,从而相应调整其他相对位置处阀门的开度使水冷壁各管压差相同,使水冷壁管的水流量带走与之相应的热负荷,保证了热态下水冷壁的水动力稳定性。

By establishing the water wall heated model,furnace regional segmentation was conducted to study the heat load distribution of water wall in height direction.Regarding the heat load distribution coefficient in horizontal direction as the medium,the heat load in height direction was transformed into the one in horizontal direction.Taking the two extreme positions where the heat load of the water wall in horizontal direction was the maximum and the minimum as the examples,calculation on opening degree of control valve at inlet of the water wall in hot state was performed.The heat transfer coefficient of the working fluid was applied to conduct the phase section division,like the saturated water,steam-water mixtures and superheated steam.Considering the water wall tubes at the position where the heat load was the highest in furnace circumferential direction(i.e.the relative width is 0.54)as the calculation criterion,the pressure drop in each phase section was obtained.Thus,the opening degree of valves at other relative positions was adjusted correspondingly to ensure the pressure difference in each water wall tube was the same and the water flow took away the heat load associated with its quantity,ensuring the hydrodynamic stability of water wall in hot state.