风幕代替中心筒的旋风分离器性能研究

Performance of cyclone separator replacing vortex finder with air curtain

旋风分离器是循环流化床锅炉中的重要设备之一,具有结构简单、造价便宜等优点,然而在循环流化床锅炉运行过程中容易发生旋风分离器中心筒变形、裂隙、下移甚至脱落等失效事故,造成了严重的经济损失。鉴于此,提出一种无中心筒旋风分离器,在原有中心筒位置引入无尘新风形成风幕用于调节旋风分离器的分离效率,避免中心筒失效事故且能灵活调整旋风分离器分离效率。采用冷态试验和数值模拟相结合的方法研究该无中心筒分离器的性能。研究发现:旋风分离器中心筒缺失后分离效率降低,在中心筒脱落后分别通入3、6、9、12 m/s风幕,分离效率先升高后降低,风幕速度为9 m/s时分离效率最高,较不通入风幕的分离效率提高3.17%;中心筒脱落后对于粒径小于6μm的颗粒影响较小,与中心筒存在时的分级分离效率相差不大,而对粒径大于6μm的颗粒影响较明显,远低于中心筒存在时的分级分离效率;形成风幕后能极大提高旋风分离器对粒径小于6μm颗粒的分级分离效率。旋风分离器中心筒脱落后,压降略降低,在原有中心筒处通入无尘新风形成风幕后压降会升高,且压降随着风幕速度的提高而升高。

Cyclone separator is one of the important equipment in circulating fluidized bed boiler,which has the advantages of simple struc⁃ture and low cost.However,many accidents such as deformation,crack,downward movement and even falling off of the vortex finder of the cyclone separator are easy to occur during the operation of the circulating fluidized bed boiler,resulting in serious economic losses.A cyclone separator without vortex finder was presented,and the dust free fresh air was introduced into the original vortex finder to form an air curtain to adjust the separation efficiency of cyclone separator,which could avoid the failure accident of vortex finder and flexibly adjust the separation efficiency of cyclone separator.The separation performance of the cyclone separator was studied by cold state experiment and numerical simulation.The results show that the separation efficiency of the cyclone separator decreases after the vortex finder falls off.Then the separation efficiency of the wind behind 3,6,9 and 12 m/s respectively increases first and then decreases.When the air curtain veloci⁃ty is 9 m/s,the separation efficiency is the highest,which is 3.17%higher than that of the cyclone separator without air curtain.After the shedding of the vortex finder,the fractional separation efficiency of particles with particle size less than 6μm shows little change compared with that in the presence of the vortex finder.However,the fractional separation efficiency of particles with particle size greater than 6μm is significantly lower than that in the presence of the vortex finder.The separation efficiency of cyclone separator for particles with particle size less than 6μm can be greatly improved behind the wind.After the vortex finder of cyclone separator falls off,the pressure drop will decrease slightly.When the fresh air is introduced into the original vortex finder,the pressure drop behind the wind will increase,and the pressure drop will increase with the increase of the wind curtain speed.