下喷式环流反应器流动特性研究

发布时间：2018-08-17 16:09

【摘要】：下喷式环流反应器(Reverse Jet Loop Reactor,简称RJLR)借助高速的射流和环流的相互作用,因而强化了流体的混合效果,提高了传热及传质速率,改善了反应条件,是一种新型的高效多相反应装置。基于其结构简单、投资廉价、无转动部件、密封性好及混合传质传热性能好、操作维修以及工业放大容易等优点,下喷式环流反应器特别适合于液-液、气-液及气-液-固等多相反应体系中。在化学化工、生物工程、环境保护等领域很快得到广泛应用,具有良好的发展前景。但由于研究者在研究方法、测试手段、研究内容方面的不系统,导致目前对该反应器的放大设计和优化缺乏依据,对环流反应器的操作规律更是缺乏研究。因此本文对下喷式环流反应器的流动特性进行了研究,主要的研究内容和结论如下：(1)空气-水体系为研究对象,实验研究了下喷式环流反应器的结构参数及操作参数对气含率ε、吸气量QG的影响规律。实验结果表明,气含率随着表观液速及表观气速的增加而增加；气体吸入量随着液体流量的增加和喷嘴位置的上升而增加。并根据实验结果回归了气含率的关联式如下：(2)在空气-水体系下,实验研究了下喷式环流反应器的启动规律(环流启动的最小液体流量弛以及环流维持的最小液体流量QLd等)。实验结果表明,随着喷嘴位置及导流筒直径的升高,环流启动的最小液体流量QLu以及环流维持的最小液体流量QLd都不断的升高。随着导流筒位置的下降,QLu稍微升高,而QLd逐渐降低。在气体流量较低时(QG1.5m3/h),随着气体流量的增加,Qu以及QLd迅速下降,而在气体流量较高时(QG1.5m3/h),气体流量的变化对QLu以及QLd影响不大。并利用实验数据对QLu以及QLd进行了关联,关联式如下：(3)将粒子图像测速法(Particle Image Velocimetry,简称PIV)和计算流体动力学(Computational Fluid Dynamics，简称CFD)相结合,研究下喷式环流反应器内部的速度场分布规律,并将速度的测量值与k-ε湍流模型模拟值进行了对比。结果表明,导流筒内速度呈抛物线分布,随着喷嘴位置的下降,抛物线图形越陡,环隙的速度先降低后升高；随着喷嘴的速度升高时,反应器内各位置的速度值均升高,实验和模拟的结果的一致,证明了模型的正确性。(4)将下喷式环流反应器应用于2,4-二硝基甲苯(2,4-dinitrotoluene,简称DNT)催化加氢合成2,4-甲苯二胺(2,4-tolylene diamine，简称TDA)反应,对反应器的体积、循环量以及换热进行了设计,并与相同反应条件下的搅拌釜式反应器进行了比较。实验表明,采用下喷式环流反应器的体积约为搅拌釜式反应器的10%。同时模拟了反应器的体积和换热器的面积随着循环比的变化规律,最后确定了反应系统的循环比为80,换热器面积为355m2。
[Abstract]:Reverse Jet Loop Reactor (RJLR) is a new type of multiphase reactor with high efficiency, which is characterized by its simple structure, low investment, no rotating parts and sealing. Down-jet loop reactor is especially suitable for liquid-liquid, gas-liquid and gas-liquid-solid systems. It has been widely used in chemical, biological engineering, environmental protection and other fields, and has a good development prospect. The unsystematic research methods, testing methods and research contents lead to the lack of basis for the scale-up design and optimization of the reactor, and the lack of research on the operating rules of the loop reactor. The experimental results show that the gas holdup increases with the increase of superficial liquid velocity and superficial gas velocity, and the gas suction increases with the increase of liquid flow rate and nozzle position. According to the experimental results, the correlation of gas holdup was regressed as follows: (2) In the air-water system, the start-up law of the downspout loop reactor (the minimum liquid flow relaxation and the minimum liquid flow QLd maintained by the circulation) was experimentally studied. The minimum liquid flow rate QLu and the minimum liquid flow rate QLd maintained by the circulating current both increase continuously. With the decrease of the position of the guide tube, QLu increases slightly, but QLd decreases gradually. At the lower gas flow rate (QG1.5m3/h), Qu and QLd decrease rapidly with the increase of gas flow rate, but at the higher gas flow rate (QG1.5m3/h), the change of gas flow rate is obvious. Qlu and QLd have little effect. The experimental data are used to correlate Qlu and QLd. The correlations are as follows: (3) The particle image velocimetry (PIV) and computational fluid dynamics (CFD) are combined to study the velocity field distribution in the downspout loop reactor. The measured velocity was compared with the simulated value of k-e turbulence model. The results show that the velocity in the draft tube is parabolic. With the decrease of the nozzle position, the parabolic figure becomes steeper, and the velocity in the annulus first decreases and then rises. (4) The downjet loop reactor was applied to the catalytic hydrogenation of 2,4-dinitrotoluene (DNT) to synthesize 2,4-tolylene diamine (TDA), and the reactor volume, circulating capacity and heat transfer were designed. The experimental results show that the volume of the down-jet loop reactor is about 10% of that of the stirred tank reactor. Simultaneously, the variation of the reactor volume and the area of the heat exchanger with the circulation ratio is simulated. Finally, the circulation ratio of the reaction system is 80 and the area of the heat exchanger is 355m2.
【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ052

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