旋转填充床反应器流体流动可视化研究进展

旋转填充床反应器是一种典型过程强化装置,对化工过程中的传质与混合过程具有较好的强化作用。流体流动作为旋转填充床反应器中最为基础的性质,对研究、优化旋转填充床反应器的结构和性能至关重要。光学成像技术与数值模拟作为研究旋转填充床反应器中流体力学性质的重要手段在近年来得到了飞速发展。对近三十年来,旋转填充床反应器可视化研究进行了综述,从早期光学成像开始,在此基础上引入早期计算流体力学模拟,直至现在高速数码摄像可视化和基于真实结构的模拟。对旋转填充床的可视化观测从填料表面逐渐向填料内部发展,对其数值模拟从初步的数学模型发展到包含详细填料几何结构、详细流体特性的流动模拟。现有研究已对填料区、空腔区中的流体流动有了较为详细的描述。     

旋转填充床CFD模拟研究进展

旋转填充床（RPB）反应器凭借填料对液体的切割破碎作用，可以显著强化多相流之间的质量传递，大幅度减少反应时间。但是旋转填充床内部结构和流体力学规律极为复杂，即便使用高速摄像机也很难准确描述填料内的流动和传质规律。计算流体动力学（CFD）凭借其能够有效模拟多相流动过程中的流动和传质规律的独特优势，近年来已被许多研究人员用来模拟RPB反应器中的流动和反应特性。本文综述了近些年来学者利用CFD技术模拟旋转填充床反应器的研究进展，并着重总结了多相流模型的选取、边界条件的确定以及旋转填充床的简化方法等CFD计算中的关键部分。     

旋转填充床基础研究及工业应用进展

超重力技术突破了地球重力场的限制,是强化传递和混合过程的一项突破性新技术,其核心装置是旋转填充床。回顾前人几十年的不懈努力,旋转填充床已经在基础研究和工业应用中取得了长足的进展。本文主要介绍了旋转填充床的基础研究最新成果及工业应用案例。阐述了旋转填充床填料的种类和特点以及旋转填充床内部流体流动、传质与微观混合的研究进展,研究了不同填料的优缺点及适用环境,指出了各种可视化技术手段的优势及局限性,并提出了进一步强化旋转填充床的传质和微观混合性能的新思路。应用研究综述了近些年来旋转填充床的工业应用案例,包括高端化学品制造、海洋天然气净化、纳米材料制备、环保等领域,并展望了旋转填充床的工业应用前景。     

分层填料旋转床气相流场的CFD模拟研究

分层填料旋转床(SP-RPB)是一种新型高效的化工过程强化设备,对气相阻力控制的吸收、精馏等传质过程有明显的强化作用。文中采用计算流体力学方法(CFD)对该结构旋转床内的气相流场进行了模拟研究,分析了流体流速、转子转速及填料转动形式对SP-RPB内部压力场、速度场和湍动能分布的影响规律。计算使用RNG k-ε湍流模型和SIMPLE算法,填料层用多孔介质(Porous Media)模型,模拟结果与实验数据吻合良好。结果表明:SP-RPB内气相压降主要产生在填料区,切向速度远大于径向速度,流场以旋转场为主,湍动程度高于普通的旋转填料床,且湍动能沿径向的分布更为均匀,表明分层填料旋转床在强化气相传质方面比普通旋转填料床更具优势。     

计算流体力学在填充床反应器中的应用进展

在使用计算流体力学(CFD)方法模拟填充床反应器时,为了描述填充床中的气液流动情况,目前主要运用基于体积平均法的双流体数学模型,辅以空隙率分布,填料润湿效率以及轴向扩散等经验关联式来计算填充床中的压降、持液量、停留时间分布等重要参数。近年来填充床反应器CFD数学模型韵几个研究重点是动量交换系数、毛细管压力以及床层空隙率的非均匀分布性。简要介绍了涓流床、固定床、填料塔等填充床反应器及其内部构件研究中CFD软件模拟的应用进展情况和发展趋势。     

旋转床内液体流动的实验研究

旋转床是一种强化传质与反应的高效分离设备。本文首次利用高速频闪摄影的办法对旋转床内液体流动进行了实验研究，得到了不同操作条件下，液体在填料空间呈现出的液滴、液膜和液线等形态照片，并测得填料主体区液滴尺寸，为旋转床流体流动和传质模拟及基础研究打下了基础。     

《化工学报》 2005年第56卷第7期目次

[HT5H]热力学含(CH4+CO2+H2S)酸性天然气水合物形成条件实验与计算离子交换纤维吸附儿茶素的热力学氧气(1)-乙酸(2)-水(3)三元系平衡溶解度的测定及关联[HT5H]传递现象结构化金属填充床传递特性的数值模拟梯度磁场作用下自然对流换热强化超临界流体增强聚酯薄膜中的质量传递铝电解槽用矩形燃烧器燃烧过程的数值模拟[HT5H]多相流DSMC-LES方法研究循环流化床内颗粒团聚物的流动特性射流稀疏颗粒图像PIV算法应用气溶胶在毛细管中输运Monte Carlo模拟三相环流反应器流体力学行为[HT5H]催化、动力学与反应器旋转填充床内微观混合化学…     

超重力旋转填充床氧解吸过程的数值模拟

基于旋转填充床流体流动的可视化结果,建立了超重力旋转填充床气液传质过程的数学模型,模拟氮气解吸水中溶解氧的传质过程。模拟结果表明,缩短液相停留时间、提高液相扩散系数都能增大液相传质分系数k_L;总体积传质系数K_La随超重力因子的增加而增大、随温度的上升而增大、随气相流率的增加略有下降、随液相流率的增加明显增大;空腔区传质贡献率随空腔区的增大而增大,随超重力因子的增大而减小;且短暂的停留时间是超重力旋转填充床对传质过程强化的本质原因。模型较好地符合文献的实验数据,误差在±16%以内。     

超重力旋转填充床氧解吸过程的数值模拟

基于旋转填充床流体流动的可视化结果,建立了超重力旋转填充床气液传质过程的数学模型,模拟氮气解吸水中溶解氧的传质过程。模拟结果表明,缩短液相停留时间、提高液相扩散系数都能增大液相传质分系数kL;总体积传质系数KLa随超重力因子的增加而增大、随温度的上升而增大、随气相流率的增加略有下降、随液相流率的增加明显增大;空腔区传质贡献率随空腔区的增大而增大,随超重力因子的增大而减小;且短暂的停留时间是超重力旋转填充床对传质过程强化的本质原因。模型较好地符合文献的实验数据,误差在±16%以内。     

纤维填充滴流反应器的流体力学

<正> 1 引言 近期的研究表明,无机纤维催化剂(玻璃纤维、碳纤维、氧化铝纤维等)具有较高的活性、选择性和稳定性,如氧化铝纤维为载体的裂解汽油加氢。但到目前为止,有关纤维滴流床的化工数据几乎未见报道。本工作的目的是对纤维滴流床进行流体力学研究,考察操作条件、填料性质、填充方式变化时流体流动性质如压降、持液量等的变化规律,以求建立计算压降和持液量的关联式,为纤维滴流床反应器的设计和放大提供基础数据。     

Liquid-solid mass transfer in a rotating packed bed reactor with structured foam packing

A rotating packed bed (RPB) reactor has substantially potential for the process intensification of heterogeneous catalytic reactions. However, the scarce knowledge of the liquid-solid mass transfer in the RPB reactor is a barrier for its design and scale-up. In this work, the liquid-solid mass transfer in a RPB reactor installed with structured foam packing was experimentally studied using copper dissolution by potassium dichromate. Effects of rotational speed, liquid and gas volumetric flow rate on the liquid-solid mass transfer coefficient (k_LS) have been investigated. The correlation for predicting k_LS was proposed, and the deviation between the experimental and predicted values was within ±12%. The liquid-solid volumetric mass transfer coefficient (k_LSa_LS) ranged from 0.04-0.14 1^-1, which was approximately 5 times larger than that in the packed bed reactor. This work lays the foundation for modeling of the RPB reactor packed with structured foam packing for heterogeneous catalytic reaction.     

A review on computational fluid dynamic simulation for rotating packed beds

A rotating packed bed (RPB) is one of the cutting-edge process intensification technologies due to its high mass transfer and mixing efficiency. Nevertheless, owing to the complex structure and hydrodynamic characteristics of RPBs, valuable data inside the reactor is hard to obtain by conventional experimental methods. Computational fluid dynamics (CFD) owing to its unique advantages of low cost, completeness of data and ability to simulate real and ideal conditions, has been adopted by many researchers to carry out fundamental research and practical application of RPBs in recent years. This paper therefore elaborates on the research progress on CFD simulation of RPBs. The building of a physical model of these reactors as well as selection of mathematical models are described, then applicability and accuracy of these models are compared and discussed. Simulation results for gas and multiphase flow in reactors are also presented. Additionally, the application of CFD to mixing and mass transfer between phases and processes in rotating packed beds is introduced. Optimum designs of reactors by the CFD method are also described. Finally, problems remaining with CFD simulation of rotating packed beds and future development directions are discussed. © 2018 Society of Chemical Industry     

Computational fluid dynamic simulation of gas-liquid flow in rotating packed bed:A review

The rotating packed bed (RPB) has been widely used in gas-liquid flow systems as a process intensifica-tion device,exhibiting excellent mass transfer enhancement characteristics.However,the complex inter-nal structure and the high-speed rotation of the rotor in RPB bring significant challenges to study the intensification mechanism by experiment methods.In the past two decades,Computational fluid dynam-ics (CFD) has been gradually applied to simulate the hydrodynamics and mass transfer characteristics in RPB and instruct the reactor design.This article covers the development of the CFD simulation of gas-liquid flow in RPB.Firstly,the improvement of the simulation method in the aspect of mathematical mod-els,geometric models,and solving methods is introduced.Secondly,new progress of CFD simulation about hydrodynamic and mass transfer characteristics in RPB is reviewed,including pressure drop,veloc-ity distribution,flow pattern,and concentration distribution,etc.Some new phenomena such as the end effect area with the maximum turbulent have been revealed by this works.In addition,the exploration of developing new reactor structures by CFD simulation is introduced and it is proved that such new struc-tures are competitive to different applications.The defects of current research and future development directions are also discussed at last.     

Liquid-solid mass transfer in a rotating packed bed reactor with structured foam packing

A rotating packed bed (RPB) reactor has substantially potential for the process intensification of heterogeneous catalytic reactions. However, the scarce knowledge of the liquid–solid mass transfer in the RPB reactor is a barrier for its design and scale-up. In this work, the liquid–solid mass transfer in a RPB reactor installed with structured foam packing was experimentally studied using copper dissolution by potassium dichromate. Effects of rotational speed, liquid and gas volumetric flow rate on the liquid–solid mass transfer coefficient (k_LS) have been investigated. The correlation for predicting k_LS was proposed, and the deviation between the experimental and predicted values was within ± 12%. The liquid–solid volumetric mass transfer coefficient (k_LSa_LS) ranged from 0.04–0.14 1⁻¹, which was approximately 5 times larger than that in the packed bed reactor. This work lays the foundation for modeling of the RPB reactor packed with structured foam packing for heterogeneous catalytic reaction.     

超重力旋转床中水脱氧过程的模型化研究

超重力旋转床是一种高效的强化传质和混合的新型设备。今提出了超重力旋转床中的水脱氧过程的传质模型,分别采用欧拉方法和拉格朗日方法对超重力旋转床中的气相和液滴的运动行为进行了数值模拟;在此基础上计算了液滴的传质系数,计算结果和实验结果符合较好,平均误差为7．9％。当超重力旋转床中液体存在的主体形式更接近于液滴时,模型计算结果误差减小。进一步讨论分析了液体和气体流量、转速以及填料内径的变化对于超重力旋转床体积传质系数的影响,分析表明旋转填料对液体剧烈地剪切破碎分散作用是强化传质过程的主要原因。     

旋转填充床内微观混合的数值模拟

旋转填充床作为新型的高效反应传质设备,广泛应用于快速反应过程,如制备纳米粉体材料.对旋转填充床内微观混合进行研究,有助于进一步认识旋转填充床内高度分散液体微元在填料丝网中的流动行为和分散混合机制,为旋转填充床内液液反应混合制备纳米材料提供理论基础.基于公开文献报道的实验观测结果,通过合理假设,建立了旋转填充床内微元流动的物理模型.在该物理模型的基础上,结合此前提出的湍流混合与反应模型,模拟计算了液体微元经过实验条件下50层丝网填料最终流出填料空间的浓度分布.由浓度分布得到的微观混合特征指数与实验值进行了对比,吻合良好.     

旋转床超重力环境下多相流传递过程研究进展

旋转填充床作为一种高效的传质、分离与反应设备,在化工、环境保护、纳米材料制备、能源、制药等工业过程得到广泛应用。本文对旋转填充床超重力环境下,流体力学特性、传质性能、微观混合、多尺度传递特性等方面的研究进行了总结归纳。近年来,随着计算机科学与多相流传递过程的研究进展,对传递过程的研究也由实验手段为主转变为实验与数值模拟相结合的手段,对有关的数值模拟研究以及相应的多相流模型也予以总结描述。在此基础上,对旋转填充床超重力环境下多相流研究的未来发展提出了有关设想。