气固搅拌流化床内的压力脉动特性

Pressure fluctuation in gas-solid agitated fluidized bed

为考察搅拌桨的转动作用对流化特性的影响,研究了不同转速和气速下搅拌流化床的压力脉动行为.采用188 mm的内径和400 mm的静床高,以Geldart B类和D类颗粒为实验物料,进行了压力脉动信号的统计分析和功率谱分析.实验结果表明,搅拌桨的转动对最小流化速度没有影响,但使B类和D类颗粒呈现了A类颗粒特有的散式流态化现象.随搅拌转速的增大,压力脉动的标准偏差减小,最小鼓泡速度增加.最小鼓泡速度与最小流化速度之比与搅拌转速成正比.当搅拌转速增加到一定程度后,压力脉动的功率谱主频等于搅拌桨转动频率,流化床从鼓泡流态化状态转化为散式流态化状态.

To observe the influences of stirrer blade＇s agitation on the fluid characters, pressure fluctuation behaviors at different rotation speeds and gas velocities were investigated in an agitated fluidized bed. A static bed height of 400 mm and an inner diameter of 188 mm were adopted, and particles of Geldart B and D were taken as fluidized materials. Pressure fluctuation signals were analyzed with statistics and power spectrum researches. Experimental results show that the minimum fluidization velocity has no effects on the rotation of stirrer blades, while particle B and D appear inherent particulate fluidization of kind A. The minimum bubbling velocity increases and the standard warp of pressure fluctuation decreases with the increasing rotation speeds of stirrer blade. The ratio of the minimum bubbling velocity to the minimum fluidization velocity is proportional to the rotation speeds of stirrer blade. Main frequency of the power spectrum is equal to the rotation frequency of stirrer blade, and the fluidized bed transits from the bubbling fluidization regime to the particulate fluidization regime with the increasing rotation speeds of stirrer blade.