垃圾衍生燃料流化床掺混流动过程数值研究
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垃圾衍生燃料流化床掺混流动过程数值研究
从图3可以看出,浓度较高的phase一2均呈现出 【5】Xu B,Yu A.Numerical Simulation of the Gas-solid Flow in a
一
定的环流特性,即近壁区颗粒浓度高于核心区,以及 Fluidized Bed By Combining Discrete Particle Method with
近壁区颗粒向下运动的运动状态。在较低位置处,颗 Computational H uyna cS【 J- 。 ca。Engineering
粒浓度较低,受流场作用力较小因此分布比较均匀。 l6]S
zchiaenngceY,,J19in97B,,z5h2。(1n6g):w
27,8e5t-a2{8.0。9
e
.
m simu 。n。f PartIcle
随着高度的增加,近壁区颗粒受到的流体作用力较小, ; : +~+r^~。….+ 。,、 ,、 一:
并且由于气泡的排挤作用形成了逆向返混。然而气流
速度的增加增强了曳力作用,使得近壁区较浓颗粒运
动更为剧烈,因此双组份颗粒的轴向掺混要好于低气
速条件。
4结论
在流化床中,较高颗粒掺混程度可以保证床层温
度均匀。而颗粒掺混程度受到多种因素的影响,其中
颗粒粒度密度和流化速度均可以改变颗粒混合的质
量。在计算结果中,小而重的颗粒的平均分布高度要
略低于粗而轻的颗粒,重颗粒在床下部空隙率较低,因
此流体流速较大,会将轻颗粒夹带至床层上部。
流态化速度对颗粒掺混特性也有着重要影响。颗
粒掺混的根本动力是颗粒运动差异。气固流体在流化
床中心部位形成稀相向上运动,在近壁区域形成密相
向下运动。不同区域的相对运动越剧烈,颗粒的掺混
程度就越高。
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 ̄"on the RDF mixingumerica analysis on the m Drocess
with bed material in fluidized bedd materia dized ed
(Collage of
)and bed materiaI in the fluidized bed
;rian two-fluid mode1.The particles
e considered for a certain distinctions
e e仟ect of the superficiaI gas velocity
 ̄ixing;two-component particles
一 (收稿日期2015—04—27)
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