角管式蒸汽锅炉预分离装置汽液分离数值模拟研究

Numerical Simulation of Vapor-liquid Separation for Pre-separation Device of Corner-tube Steam Boiler

采用数值模拟的方法研究了角管式蒸汽锅炉预分离装置不同运行参数下汽水两相的分离效率,分析了压力、入口干度、入口质量流速及引出管内径对预分离装置汽水分离效率的影响。模拟结果表明:当压力升高,汽水密度差和液滴直径减小,导致水滴的重力小于蒸汽对它的浮力及摩擦力之和,使得更多水滴被蒸汽带入引出管内,从而分离效率降低;分离效率随入口干度的增高而增大;增大入口质量流速不利于汽液两相的分离;增加引出管内径会使预分离装置分离效率降低。

The numerical simulation method was used to study the separation efficiency of vapor-water under different operating parameters for the pre-separation device of the corner-tube steam boiler.The effects of pressure,inlet dryness,inlet mass flow rate,and inside diameter of the outlet pipe on the vapor-water separation efficiency of the pre-separation device were analyzed.The simulation results show that when the pressure increases,the vapor-water density difference and the droplet diameter decrease,resulting in more droplets having a smaller gravity than the sum of the buoyancy and friction of the steam,causing more droplets to be brought into the outlet tube.As a result,the separation efficiency decreases;the increase of the inlet dryness increases the separation efficiency;increasing the inlet mass flow rate is not conducive to the separation of the two phases of the vapor;increasing inside diameter of the outlet pipe,the separation efficiency of the pre-separation device is reduced.