撞击流反应器中液相传质特性的实验研究

发布时间：2018-05-04 09:31

本文选题：搅拌槽 + 撞击流反应器　；参考：《北京化工大学》2015年硕士论文

【摘要】：撞击流(Impinging Jets)是由Elperin首次提出的一种过程强化方式,通过将两股或多股高速流动的流体沿着同一轴线相向流动并最终在某一区域发生撞击,使得撞击之后高速流体的轴向速度转变为脉动速度,产生出一个湍动非常剧烈的撞击区域。在这个区域内,流场湍流作用明显,强烈的剪切作用将流体微团粉碎的十分微小。这样不仅增大了固定流体体积下流体的接触面积以及传质推动力,改善了流体的混合状态,强化了过程的质量以及热量传递效果；而且减小了生产设备的体积。基于撞击流具有的诸多优点,科研人员对其进行了大量的研究,使得撞击流在许多化工生产过程中得到了研究和应用。使用撞击流技术对有机羧酸的络合萃取过程进行强化是撞击流技术在化工生产领域的应用之一。撞击流过程流场能量大,湍动作用强烈,可以明显地促进流体的混合,弥补了传统萃取操作相间接触面积小,传质系数小、反应时间过长的缺点。正丁酸(butyric acid)是一种常用化工原料,具有类似于腐败奶油的难闻气味,极低的浓度就会被人类察觉,严重影响环境。丁酸合成工业的废水中含有含量很低的丁酸,如果直接排放这些含有丁酸的废水,既会严重污染环境,又会导致额外的经济损失。因此对这些极稀浓度的丁酸废水进行萃取具有很重要的意义。本实验在撞击流反应器内以及传统机械搅拌槽内对磷酸三丁酯萃取丁酸过程的萃取性能进行研究,并将二者的结果进行了比较,旨在考察撞击流萃取对快速反应羧酸萃取过程的强化性能。主要从以下方面开展了实验研究：1、在撞击流反应器中进行实验,考察了丁酸的浓度Caq、TBP的浓度Corg、撞击速度V、撞击区上方空间L、两相的流速比Vorg/Vaq以及管径di对丁酸的萃取率E和质量传递系数KLa的影响。发现丁酸浓度、TBP浓度、撞击速度、两相流速比以及管径大小对萃取过程的效果影响较大,而撞击区上方空间的变化对过程的影响较小,可以忽略。最后,将实验数据进行了拟合,得到了质量传递系数KLa与主要影响因素之间的拟合关系,并具有较好的预测效果。2、在传统的标准搅拌槽中展开实验,考察了丁酸的浓度Caq、TBP的浓度Corg、萃取时间t、萃取相比P、搅拌桨转速S以及萃取温度T对萃取过程传质性能的影响。发现丁酸的萃取效果受丁酸浓度、TBP浓度、萃取时间、相比、搅拌桨转速变化的影响较大,而对温度的变化不敏感。最后将撞击流反应器的传质效果与搅拌槽进行了对比,发现对于快速反应体系,撞击流反应器的传质效果要略微的优于搅拌槽,对快速络合反应体系的传质效果具有一定的强化作用。
[Abstract]:Impinging jetsis a process strengthening method proposed by Elperin for the first time, by moving two or more high-speed flowing fluids along the same axis and finally striking in a certain area. The axial velocity of the high velocity fluid changes to the pulsating velocity after impact, resulting in a very violent turbulence zone. In this area, the turbulent effect of the flow field is obvious. This not only increases the contact area and mass transfer force of the fluid under the fixed fluid volume, but also improves the mixing state of the fluid, strengthens the quality of the process and the heat transfer effect, and reduces the volume of the production equipment. Based on the many advantages of impinging stream, researchers have done a lot of research on it, and the impinging stream has been studied and applied in many chemical production processes. The enhancement of complexation extraction of organic carboxylic acids by impinging flow technology is one of the applications of impinging flow technology in chemical production. The impinging flow process is characterized by large energy and strong turbulence, which can obviously promote the mixing of fluid, and make up for the shortcomings of traditional extraction operation, such as small contact area between phases, small mass transfer coefficient and long reaction time. Butyric acidis is a common chemical raw material, which has a bad smell similar to corrupted cream, and the very low concentration will be detected by human beings, which will seriously affect the environment. Butyric acid is contained in the wastewater of butyric acid synthesis industry. If the wastewater containing butyric acid is discharged directly, it will not only pollute the environment seriously, but also lead to extra economic loss. Therefore, it is of great significance to extract these extremely dilute concentrations of butyric acid wastewater. In this experiment, the extraction performance of tributyl phosphate in butyric acid was studied in impinging flow reactor and in the traditional mechanical stirred tank, and the results were compared with each other. The purpose of this study was to investigate the enhancement performance of impinging stream extraction for rapid reaction carboxylic acid extraction. Mainly from the following aspects of the experimental study: 1, in the impinging flow reactor to carry out the experiment, The effects of the concentration of butyric acid, the impact velocity V, the space L above the impact zone, the flow rate ratio Vorg/Vaq of two phases and the diameter di on the extraction rate E and mass transfer coefficient (KLa) of butyric acid were investigated. It is found that the concentration of butyric acid (TBP), the impact velocity, the velocity ratio of two phase flow and the diameter of the tube have great influence on the extraction process, but the change of the space above the impact zone has little effect on the extraction process, which can be neglected. Finally, the experimental data are fitted, and the fitting relationship between the mass transfer coefficient (KLa) and the main influencing factors is obtained. The experiment is carried out in the traditional standard stirred tank. The effects of concentration of butyric acid, concentration of Caqn TBP, extraction time t, extraction ratio P, stirring speed S and extraction temperature T on the mass transfer properties of the extraction process were investigated. It was found that the extraction effect of butyric acid was influenced by the concentration of butyric acid (TBP), the extraction time, and the speed of agitator, but was not sensitive to the change of temperature. Finally, the mass transfer effect of impinging flow reactor is compared with that of stirred tank. It is found that the mass transfer effect of impinging flow reactor is slightly better than that of agitating tank for rapid reaction system. It can strengthen the mass transfer of the rapid complexation reaction system.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ021.4

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