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Pressure drop data for all four pressures are shown in Figure 7 and listed in Table 2. On the basis of these data plus the methods for calculating the values of hd and hL described earlier, the fraction of the total tray pressure drop due to the collector elements is shown in Figure 8.
APPLICATIONS
The cocurrent tray is suitable for applications involving high gas and liquid flows, such as pressure fractionations of light hydrocarbon mixtures. While its pressure drop is not excessive, when compared with conventional crossflow trays, the liquid collectors create a pressure loss that might be considered too high for vacuum distillations. Its potential economics have been reviewed by Seibert and Fair, 199514 , who found that the cost of fabrication of the cocurrent tray could be as much as three times that of a conventional tray, but that its capacity advantages could more than offset this additional cost.
CONCLUSIONS
The contacting device described in this paper has the potential for doubling the throughput capacity exhibited by conventional crossflow sieve trays and valve trays. Since the device operates on a concurrent flow basis, the usual limits of entrainment for countercurrent or crossflow devices are absent. The simple collector system is remarkably efficient for removing entrained liquid from vapour. The height of a downcomer is much greater than a tray spacing, and the liquid entering the downcomer has been de-aerated. The test data presented here were taken on a column much larger than those used for presenting device data under distillation conditions.
The model presented here is mechanistic in nature, and appears to give a good representation of measured mass transfer efficiency data. The models for pressure drop can be related to those of conventional trays, and for the present purposes appear to fit well the measured data. A key to the design is an efficient device for separating the entrained liquid from the vapour and the simple impact-type separator shows high efficiency, not only for the tests reported here but also for separate air-water tests.
传统蒸馏托盘的横向气流通常被倾向气体限制。只能少量的雾沫夹带才能保证传热效率不严重下降。这里描述的盘式联系设备设计能使所有的液体进入托盘,然后分液设备位于托盘区。因此,相当多的气体流量可以被容纳在塔盘区内。
关键词： 精馏；气-液系统；塔盘；改进；消除瓶颈 论文网
Debottling蒸馏塔是一个希望节约大量资金的项目工程，但是在通常意义上有严重的局限性。在这个问题上最近的一篇论文表明, 当前可改进设备，为了使其达到增加产量的且不失分离能力，将提供能力增加要求的25 - 30%相比,现代设计的横向气流筛或者浮阀塔盘(Fair and Seibert, 1996)1。摘要操作特征和性能结果将被描述为一个新的设备称为直流托盘。该设备已被证明气生产能力高于传统横向气流的托盘50 -100%。论文中还包括一个模型的细节,它可以用于进一步的研究和预测设备的水力特性和传质效率。
直流托盘操作原则是使蒸汽和液体接触,这样所有的液体夹带蒸汽向上。分散过程发生在每个阶段接触阶段。完整的过程是气-液在一个塔盘上面分离，分离后液流到下一个塔盘降液管。托盘的示意图如图1所示。
直流盘的主要优势是它的产量较高。从阶段流直接进入接触区，流体的逆流接触不发生。因此,传统的局限性是极限能力差被作为分馏研究提出。所以最终成品设备抽验证明不适用于这个设备。夹带清液在设备中从蒸汽中分离出来因此不会产生蒸汽夹带的问题或传统泡沫处理中出现的降液现象。另一方面,塔盘在渗出液和倾倒液的影响下在低蒸汽载荷下性能不佳，这种现象也会发正在传统的横向气流筛和浮阀塔盘上。
三大系列的直流盘进行了大规模的测试分离试验。在奥斯丁德克萨斯大学研究项目,每个系列有不同的几何特征。前两组测试数据已报告之前 (Fair and Seibert,1994)2; 将在这里强调第三组测试的结果。试验是在四个压力条件下进行测试环己烷/正庚烷混合物的。自从对其他设备也做了相似的研究以来,使用相同的测试混合物和设备,准备的比较。本文的目的有三点:描述设备,提出目前的性能测试的数据, 概述机械建模工作背后的方法论以允许其测试数据推广到其他的情况的计算中。