摘要
在错流区高度为430 mm,横向宽度分别为400 mm,200 mm,105 mm的三种不同尺寸的矩形二维移动床内对贴壁现象进行了研究。实验结果表明,随着错流气速的增加床层压降也增加,当压降超过一定值时,移动床内近下流面的部分颗粒将停止下移,发生贴壁;贴壁颗粒层的厚度与床层压降呈线性关系,在相同错流气速下宽床层的贴壁厚度大于窄床层,但无因次化贴壁厚度大致相同。通过力平衡分析建立了贴壁现象的数学模型,可计算不同压降下贴壁颗粒层的厚度,并获得贴壁临界压降值的计算式,模型计算值与实验值基本相符。
The pinning phenomenon was investigated respectively in three kinds of two-dimensional rectangular moving beds, their cross-flow sections of the gas flow have the same height of 430 mm and their widths are 400 mm, 200 mm and 105 mm separately. The experiments show that the bed pressure drop produced by the gas flow increases with the increase of gas velocity, and when the pressure drop is increased to a value high enough -- the critical pressure drop causing pinning, some particles close to the downstream face of the gas flow would stick together on the face and stop moving downwards, then the pinning occurs. Experiments also show that the pinning thickness increases linearly with the increase of pressure drop, and under the same gas velocity, the pinning thickness in the bed with wider cross-flow section of the gas flow is larger than that in the bed with narrower cross-flow section, while the dimensionless pinning thicknesses are almost equal for moving beds with different widths mentioned above. Base on the force balance, a mathematic model of pirming phenomenon was proposed, using it, the critical pressure drop causing pinning and the thickness of the pinning can be predicted. The calculating results of the model agree well with the experimental data.
出处
《高校化学工程学报》
EI
CAS
CSCD
北大核心
2007年第3期404-410,共7页
Journal of Chemical Engineering of Chinese Universities
关键词
错流
移动床
贴壁
空腔
力平衡
cross flow
moving bed
pinning
cavity
force balance
