超超临界锅炉水冷壁的压降特性分析

Analysis of Pressure Drop of Water Wall of Ultra Supercritical Boiler

水动力特性是影响锅炉安全可靠运行的重要因素，水动力循环不稳定会导致水冷壁系统出现热偏差、传热恶化等问题。为保证锅炉良好的水动力特性，探索水冷壁内压降分布，分析了设计锅炉水冷壁的结构特点，研究了水冷壁系统各段的压降损失。采用了均相流体阻力数学模型，并编写了计算系统压损的C＋＋程序。对设计的2950t／h锅炉75％～100％最大连续蒸发量工况下的压降进行了计算。得出了不同负荷下水冷壁中不同形式压降的具体数据。通过计算出的压力变化分析，得出随质量流量增大，螺旋管和垂直管内压力损失均增大，螺旋管的压损变化幅度大于垂直管。在75％额定负荷以上时。摩擦压损最大，占总压损的85％以上，重力压损和局部压损很小，占总压损的15％以下。水冷壁系统压降变化的研究，有助于锅炉的可靠性和经济性研究。

As an important factor who affects the safe and reliable operation of the boiler, hydrodynamic characteristic is of great value of the research for the power plant. The instability of hydrodynamic circulation can lead to the problem of thermal deviation and heat transfer deterioration. In order to guarantee the good hydrodynamic characteristic of boiler, the structure characteristics of the water wall were studied and the pressure drop of water wall system was analyzed. A homogeneous fluid resistance mathematical model was adopted, and the C ＋ ＋ program for calculating the pressure loss of the system was also developed. The pressure drop of 2 950 t/h boiler with 75% - 100% maximum continuous evaporation was calculated, and the specific data of different pressure drop in different load were obtained. Through the analysis of the pressure change, it was concluded that with the increase of mass flow rate, the pressure loss of the spiral pipe and the vertical tube increased as well, and the pressure loss of the spiral pipe was larger than that of the vertical pipe. With the load of more than 75% rated, the frictional pressure loss was the largest, accounting for more than 85% of the total pressure loss, and the gravity pressure loss and local pressure loss were very small, accounting about 15% of the total pressure loss. The study on the pressure drop of water wall system was helpful to enhance the reliability and economic effect of the boiler.