Effect of Orifice Surface Roughness on the Liquid Weeping in Bubble Columns

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• 作者：Md. Iqbal Hossain ; Qing Xi Pang ; Si Qi Pang ; Yanhui Yang ; Raymond Lau
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2011
• 出版时间：January 5, 2011
• 年：2011
• 卷：50
• 期：1
• 页码：389-397
• 全文大小：425K
• 年卷期：v.50,no.1(January 5, 2011)
• ISSN：1520-5045

文摘

Liquid weeping at the orifices of a gas distributor plate is one problem commonly encountered in bubble column operations. The effect of orifice surface roughness on the liquid weeping phenomenon in a bubble column is investigated over a superficial orifice gas velocity range of 143鈭?03 cm/s. High-speed images of the bubbling and liquid weeping process are analyzed using a computer-aided image analysis algorithm. Pressure fluctuation in the plenum is also monitored. The liquid weeping rate is found to decrease with an increase in orifice surface roughness at low superficial orifice gas velocities while it increases with an increase in surface roughness at high superficial orifice gas velocities. Analysis indicates that the orifice surface roughness affects liquid weeping indirectly by changing the bubbling behaviors at the orifice. At low superficial orifice gas velocities, an increase in orifice surface roughness reduces the bubble size at bubble detachment. The reduction in pressure fluctuation in the plenum thus decreases the liquid weeping rate. On the other hand, as the superficial orifice gas velocity is approaching the bubbling/jetting regime transition, an increase in orifice surface roughness increases the transition velocity and hence the liquid weeping rate increases. Nonetheless, a modification of the orifice surface roughness is a viable solution to the liquid weeping problem in industrial bubble columns.