Liquid-induced pulsing flow in trickle-bed reactors
Liquid-induced pulsing flow in trickle-bed reactors
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DOI：
10.1016/s0009-2509(02)00210-5
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发表时间：
2002-08-01
影响因子：
4.7
通讯作者：
Drinkenburg, AAH
中科院分区：
文献类型：
--
作者：
Boelhouwer, JG;Piepers, HW;Drinkenburg, AAH
本文介绍了在3.2米高的塔中循环液体进料进行脉冲诱导的实验。基于方波循环液体进料，开发了两种进料策略，涉及自然脉冲的人工诱导和润湿效率在时间上的分离。进料策略的目的是增加限制反应物的传质速率，并防止流动分布不均和热点形成。进料策略根据液体进料的相对快速和缓慢的循环来分类。评价了所开发的进料策略对反应器性能的潜在影响。循环液体进料导致在塔中形成连续性冲击波。冲击波通过在尾部留下液体而衰减。这种衰减过程将循环液体进料的频率限制到相当低的值，因为在相对高的频率下，发生冲击波的完全崩溃。因此，可以应用更短的冲洗，并优化通常遇到的周期性操作。第二种进料策略称为液体诱导脉冲流的快速模式，可以看作是自然脉冲流的延伸。在外部设置的脉冲频率小于1 Hz时，诱发单个自然脉冲。由于脉冲在冲击波衰减时是稳定的，因此这种馈送策略是唯一可能的周期性操作的快速模式。在等效气体流量下，诱导脉冲的特性等于自然脉冲流的脉冲特性。脉冲之间的临界持液率对于诱导脉冲保持稳定是必要的。(C)2002爱思唯尔科技有限公司。保留所有权利。
This contribution describes the experiments on pulse induction by cycling the liquid feed in a column of 3.2 m height. Based on a square-wave cycled liquid feed, two feed strategies are developed that involve the artificial induction of natural pulses and a separation of the wetting efficiency in time. The feed strategies aim at increasing the mass transfer rate of the limiting reactant and to prevent flow maldistribution and hot spot formation. The feed strategies are categorized upon a relatively fast and slow cycling of the liquid feed. The potential consequences of the developed feed strategies on reactor performance are evaluated.Cycling the liquid feed results in the formation of continuity shock waves in the column. The shock waves decay by leaving liquid behind their tail. This decaying process limits the frequency of the cycled liquid feed to rather low values since at relatively high frequencies, total collapse of the shock waves occurs.By the induction of natural pulses inside the shock waves, the integral mass and heat transfer rates during the liquid flush will be improved. Shorter flushes can therefore be applied and the usual encountered periodic operation is optimized. This feed strategy is termed the slow mode of liquid-induced pulsing flow.The second feed strategy termed the fast mode of liquid-induced pulsing flow may be viewed as an extension of natural pulsing flow. Individual natural pulses are induced at an externally set pulse frequency less than 1 Hz. This feed strategy is the only fast mode of periodic operation possible since pulses are stable while shock waves decay. The characteristics of the induced pulses equal the pulse characteristics of natural pulsing flow at equivalent gas flow rates. A critical liquid holdup in between pulses is necessary for the induced pulses to remain stable. (C) 2002 Elsevier Science Ltd. All rights reserved.