Impact of Wall Heat Transport on Formation of Transversal Hot Zones in Shallow, Non-adiabatic Packed-Bed Reactors

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• 作者：K. Narendiran ; Ganesh A. Viswanathan
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2015
• 出版时间：August 5, 2015
• 年：2015
• 卷：54
• 期：30
• 页码：7352-7363
• 全文大小：630K
• ISSN：1520-5045

文摘

Transversal hot zones have been reported to form in packed-bed reactors used to conduct exothermic reactions. Packed-bed reactors are usually operated under non-adiabatic conditions. Previous attempts to predict the formation of transversal hot zones have been made on both shallow and long reactors under adiabatic conditions; that is, wall heat transport is zero. We show that a rich variety of slowly oscillating transversal hot zones, such as rotating patterns, targets, and spirals, may form in shallow, non-adiabatic reactors. Under certain conditions, azimuthally symmetric target patterns coexist with azimuthally non-symmetric rotating patterns. Surprisingly, a small wall heat transport can force a traveling wave or band motion observed under adiabatic conditions into a rotating pattern. A transition from the rotating patterns and/or target patterns to spiral waves depends on the residence time, the reactor length scale, and the wall heat transfer coefficient. A shallow reactor model predicts that the spatiotemporal patterns oscillate at a very low frequency (order of 10^鈥? Hz), which is in agreement with predictions based on laboratory experiments.