循环流化床锅炉新型悬吊屏周边气固流动特性实验研究

Experimental Study on the Gas-solid Hydrodynamics Around a Novel Suspended Heat Transfer Surface in a CFB Boiler

针对循环流化床炉膛中一种新型＂□＂形悬吊换热屏（＂□＂形屏）,采用光纤探针测试其周边气固流动特性,研究空截面气速、静止床料高度、＂□＂形屏宽和出口尺寸对其周边气固流动的影响。结果表明,＂□＂形屏内上部颗粒体积分数径向呈＂~＂型分布,中、下部呈＂∪＂型分布;屏内上、中、下部颗粒轴向速度径向均呈＂∩＂型分布,中、上部屏内壁面颗粒基本向下流动,下降流下降速度随空截面气速的增大而增大;屏周边颗粒体积分数随空截面气速和静止床料高度的增大而增大;＂□＂形屏出口尺寸对相应屏内区域颗粒流动有影响;对于循环流化床锅炉,＂□＂形屏宽对应有一合理范围。

This paper presented an experimental research on the gas-solid hydrodynamics around novel □-shaped suspended heat transfer surfaces（□-wall） in a CFB test rig. The solids volume fraction and velocity around the □-wall were measured by using a fiber optical probe. Effects of the superficial gas velocity, static bed height and width and exit size of the □-wall on the gas-solid hydrodynamics were studied. Results show that the solids volume fraction radially shows a ＂~＂ shape profile at the upper section while ＂∪＂shape profiles at the middle and lower sections in the □-wall. The solids vertical velocity at the upper, middle and lower sections in the □-wall show ＂∩＂ shape profiles radially. Particles flow downward on the □-wall inner surface at the upper and middle sections, and the falling velocity increases with the superficial gas velocity. The solids volume fraction around the □-wall increases as the superficial gas velocity and static bed height increase. Effects of the □-wall exit on the gas-solid hydrodynamics are mainly performed in the exit region of the □-wall. For a CFB boiler, there exists a reasonable range for the width of the □-wall.