垂直上升气液两相弹状流模型

基于等效弹单元思想,改进了预测垂直上升管中充分发展气液弹状流流动特性的模型。 模型中考虑了界面切应力对液膜运动的影响;并在液弹空隙度预测中引入临界气体夹带速度的概念,以此来描述弹状流中大气泡尾部的混合特性。本文提出的模型还考虑了管径对液弹空隙度的影响。弹状流模型的计算结果得到本文及其他作者实验数据的验证。     

微通道内液-液两相流流型及传质的研究进展

微通道内液-液两相流流动在微化工系统中占有重要的地位,了解微通道内液-液两相流体流动和传质规律对推动其工业化应用有重要作用。本文以微通道内液-液两相流系统为研究对象,简述了不同工况下微通道内液-液两相流流型和混合传质效率,分析了微通道特征、流体性质和流体流动速度等对流型形成和传质效率的影响。指出目前对于微通道内液-液两相流的研究多处于定性研究,定量研究仅针对某一体系展开,所得结果具有一定的局限性。关于微通道内液-液两相流传质研究实验较多而数值模拟方法相对较少,接下来的研究工作中应该考虑建立微通道内液-液两相流基础研究的数据库,通过分析大量的数据获得有效的流型划分准则和相关经验式以此推动微通道内液-液两相流的工业化应用。同时在传质研究过程中应研究开发相应的数值模拟模型,保证实验和数值模拟相结合,提出有效的传质效率评价机制。     

实用温度函数型PR方程及其在低碳醇混合物中的应用——(Ⅱ)混合物的汽液平衡

本文将前文(I)报中提出的实用温度函数型PR方程推广到了流体混合物.根据前人工作,提出了一个总括性的混合规则,针对不同体系可得到其简化形式.非极性-非极性,非极性-极性,极性-极性体系,尤其是含醇体系的低、高压下的二元及三元汽液相平衡计算表明,本文的模型有较广的适用性.此外还提出了处理超临界组分的方法,较准确地推算了含氢系统的汽液平衡.总之,本文提出的一套描述复杂体系汽液平衡的方法,可望用于指导低碳酸及其他工业实际体系的分离过程开发.     

脉动条件下旋流场内气液两相流流型及其转变机理

运用高速摄像技术对流量脉动条件下旋流分离器内气泡动力学行为及气液两相流流型展开研究。研究发现,在完整脉动周期内,流量在3.62~4.18 m³/h范围内波动,流量增大段的气核整体向溢流口方向运移,流量减小段的气核整体向底流口方向运移,气核大小及形态变化呈现周期往复性。通过脉动周期内特殊帧的分析,得出流量脉动条件下旋流场内气液两相流流型主要包括：气泡流、塞状流、弹状流、丝状流及波状流等五种形式。根据实验得出的气液两相折算速度,确定了脉动条件下气液两相流流型转换界限图,而气泡间的聚并破碎行为是产生气液两相流型的主要原因,最终构建了表征截面含气量和分离效率之间关系的评价模型。     

脉动条件下旋流场内气液两相流流型及其转变机理

运用高速摄像技术对流量脉动条件下旋流分离器内气泡动力学行为及气液两相流流型展开研究。研究发现,在完整脉动周期内,流量在3.62~4.18 m³/h范围内波动,流量增大段的气核整体向溢流口方向运移,流量减小段的气核整体向底流口方向运移,气核大小及形态变化呈现周期往复性。通过脉动周期内特殊帧的分析,得出流量脉动条件下旋流场内气液两相流流型主要包括：气泡流、塞状流、弹状流、丝状流及波状流等五种形式。根据实验得出的气液两相折算速度,确定了脉动条件下气液两相流流型转换界限图,而气泡间的聚并破碎行为是产生气液两相流型的主要原因,最终构建了表征截面含气量和分离效率之间关系的评价模型。     

叶片式入口分离器气液流动及分离性能数值模拟

叶片式分离器是一种较新颖的气液两相流设备的入口分离及布气装置。为了给设计提供指导,本文采用离散相模型对其中的气液两相流动过程进行模拟,并通过分离效率测试对计算模型进行了验证;在此基础上研究了气速、液滴粒径、叶片倾角及流道入口宽度对分离性能的影响。结果表明:叶片式分离器具有良好的气液分离性能,对于粒径大于50μm的液滴分离效率能够达到85%以上,增大气速和液滴粒径有利于提高叶片式入口装置的分离效率;综合考虑分离效率和压降,叶片倾角宜设置为5～8°;在现有流道宽度设计建议的范围内,减小流道宽度可显著提高小液滴分离效率,但阻力也将增加。     

轴流式气液旋流分离器内气相流场的数值研究

应用RSM湍流模型对内径100mm的轴流导叶式气液旋流分离器内气相流场进行了数值研究,计算得到的气流时均速度分布和压力分布与实验测量结果基本吻合。根据分离器内气相流动分布的特点可知:(1)气流旋转强度与导向叶片出口角有关,出口角越大,切向速度越小;(2)排气管下口区域存在明显的短路流分布,容易卷吸夹带液滴进入排气管逃出,造成分离效率下降;(3)排气口和排液口附近的区域气流湍流脉动强度高,容易造成液滴破碎,直径减小,从而影响分离效率。以上研究结果为轴流导叶式气液旋流分离器的结构优化,进一步提高分离性能奠定了基础。     

筛孔塔板气液两相流动的速度场模拟

<正>由于气体的搅动,筛孔塔板上的流动是极其复杂的气液两相流。目前两相流理论尚不成熟,未见运用此理论对塔板流速场的研究报道,Zhang和Yu的研究虽考虑了气相对液相流动的影响,但由于利用单相流理论,计算结果与实际情况有较大偏差。本文利用Elghobashi等建立的两相流双流体模型,建立了塔板上气液两相流二维流速场计算模型。在此基础上,通过调整模型参数,考虑了液层高度对塔板上返流区二维流型的影响,建立了模型参数值与液层高度的关系,实现了考虑液层高度影响的二维流动——拟三维流动的模拟。计算结果与Porter的实验结果基本相符。     

填料塔气体分布器二相流场计算流体力学数值模拟

填料塔内气体分布器对进料气流的分布作用和填料塔的分离效率,特别是对低压降、高效填料有重大影响。文中运用计算流体力学(简称CFD),采用欧拉-拉格朗日二相流模型建立了填料塔内双切向气体分布器内三维瞬态气液二相流模型,气体的湍流运动采用k-ε湍流模型计算。模型中考虑了二相之间的作用力,包括液滴所受的曳力和虚拟质量力。求解时时间项采用隐式格式,时间步长取1×10-4s,对流项采用二阶迎风格式,压力-速度耦合方程的求解采用了S imp lec方法。在不同操作条件下,模型计算得到的压降、夹带、气体分布不均匀度和文献报道的实验值吻合较好。从而可以看出,CFD模型可以较为准确地描述双切向环流式气体分布器内瞬时气液二相流场。     

冲击型T形管处气液两相流分流特性研究进展

气液两相流流经T形管时,两相流流量通常在支管中分布不均,严重影响下游设备的运行效率和运行安全。截至目前,国内外学者对分支型T形管进行了大量研究,但是很少有人关注冲击型T形管处的分流特性。本文从实验、模型和理论等角度进行分析,详细回顾了冲击型T形管处两相流分流存在的问题,并展望了未来的研究方向。本文描述了不同角度的冲击型T形管以及水平冲击型T形管后连接不同角度的分支管路等实验,概述了以流线划分方法为基础的现象学模型和以管路压降为基础的机理模型,总结了分支管路的方向、T形管入口处气液两相流型、T形管下游管路对称性、T形管下游立管中两相流的流动状态以及下游管路中压降等重要因素对气液两相流分流特性的影响,阐明了未来的研究方向。提出下一步的研究工作可以从改进气液两相流分流模型以提高预测精度、将下游分支管路中的流动状态与动量平衡理论相结合来研究T形管处两相流分流等方面开展。     

Analytical study of type-1 facilitated transport through liquid surfactant membrane

In the present study, a mass transfer model for Type-1 facilitated transport in liquid surfactant membrane is developed by taking into consideration a size distribution of emulsion drops, and analytical solution of the model equations has been presented. The model takes into account the continuous phase and outer liquid membrane phase resistances along with diffusion through composite emulsion drop. Effort has been made to highlight the effect of the various system parameters on the extraction rate including computation of reaction front position. The results of this work are found to be in good agreement with the published experimental results on batch extraction of phenol using NaOH as internal reagent. The model would thus provide an insight of the separation mechanism involved in the mass transfer processes in this type of system.     

Separation and Concentration of Phenylalanine by Emulsion Liquid Membrane in a CSTR Extraction Process

Abstract

The extraction and concentration of phenylalanine by the continuous CSTR emulsion liquid membrane (ELM) separation process has been evaluated. We discussed the influence of operating conditions on the separation and concentration efficiencies of phenylanine. It was found that the extraction rate of phenylalanine increased as the amount of emulsion used and the internal concentration of H⁺ increased. However, the concentration ratio of phenylalanine increased as the emulsion amount and acid concentration increased only up to a certain limit and then declined with further increases of these. The reduction of the concentration ratio is due to the swelling of the emulsion drops. Two effects, swelling owing to osmotic pressure and swelling caused by the entrainment of water due to mechanical agitation, are responsible for the swelling of emulsion drops. A mass transfer model for analyzing the extraction of phenylalanine by liquid surfactant membrane is presented. The model assumes that the extraction and stripping reactions are reversible, and that the reaction equilibrium exists in both the internal and the external interfaces. The scheme for mass transfer is based on a hollow sphere model. The phenomena of osmotic swelling, mechanical entrainment, and breakage are all considered in the mathematical treatment. The effects of operation parameters on the extraction efficiency and concentration ratio are discussed by simulation.     

Polydispersity effect in facilitated transport through liquid surfactant membranes

An advancing reaction-front model has been proposed in the present study of facilitated transport through liquid surfactant membranes by taking into consideration a size distribution of emulsion drops. The model takes into account the continuous and outer liquid membrane phase resistances along with diffusion through composite emulsion drops. The effect of various dispersion phenomena on the mass transfer rate of solute has been discussed for two different operating conditions corresponding to different drop size distributions but having the same Sauter mean diameter. Membrane leakage is assumed to be negligible.     

A study on reactive extraction equilibrium between acetic acid and bis-succinimide of C9232

C9232 is a typical emulsifier of emulsion liquid membrane and its main component, bis-succinimide, has amine functional groups which react with carboxylic acids. The average numbers of secondary amine groups and isobutylene units in the bis-succinimide were determined through elemental analysis. Acetic acid was extracted by emulsion liquid membrane with use of C9232, and we verified that C9232 was suitable for its extractant in the emulsion liquid membrane systems. Equilibrium experiments for reactive extraction of acetic acid by C9232 were carried out by varying the overall acetic acid concentration and overall C9232 concentration in liquid-liquid extraction systems. Also, an equilibrium model for the reactive extraction of acetic acid was investigated for the purpose of analyzing the emulsion liquid membrane systems for separation of acetic acid from other carboxylic acids or sugars in the future. The calculated results from the equilibrium model were in good agreement with the experimental data.     

气泡循环流动型膜生物反应器流体力学特性研究

以气升式环流反应器和膜生物反应器为基础,提出气泡循环流动型膜生物反应器的概念.利用气液循环流动减缓膜污染,通过充压渗透的操作方式,降低水处理能耗与设备投资.实验研究了下降管内中空纤维膜填充率对反应器的平均气含率、循环液速等流体力学性能的影响,使用模拟体系考察膜分离性能. 研究结果表明:循环流动的气液两相能够明显缓解膜污染,提高膜渗透通量;利用充压渗透的操作方式可以实现膜分离过程,同时加压操作会导致平均气含率减小,循环液速降低.在理论分析基础上,导出平均气含率、循环液速随操作气速和压强的变化关系.     

乳化液膜技术研究进展

介绍了乳化液膜技术的分离机理及在金属离子的回收与提取、废水处理、发光粉与纳米材料制备和生物医学等方面的研究进展。详细叙述了各应用研究中所用的膜溶剂、表面活性剂、载体和内相试剂的种类以及分离效果。最后指出了制约乳化液膜技术工业化应用的问题及研究方向。     

Vergleich des Koaleszenzverhaltens ruhender und umströmter Wasser‐in‐Öl‐in‐Wasser‐Einzeltropfen

Phase inversion of a water‐in‐oil emulsion to a water‐in‐oil‐in‐water double emulsion is practically used for liquid/liquid separation. For successful separation in the water leg the coalescence of the internal droplets with the surrounding continuous water phase is decisive. The determination of this coalescence phenomenon is applied for the process design. Therefore, single water‐in‐oil‐in‐water drops are investigated under static and dynamic conditions by means of high speed imaging. The influence of physical and geometrical parameters on the coalescence time and partial coalescence is determined.     

A mass transfer model for the extraction of weak acids/based in emulsion liquid-membrane systems

A mathematical model for analysing the extraction of weak acids and weak bases from aqueous solution by liquid surfactant membrane has been presented. The model assumes that the reactions are reversible and the reaction equilibrium to exist in both the internal phase and the external continuous phase. The scheme for mass transfer analysis is based on an immobilized emulsion globule drop model and the classical film theory, i.e. the overall mass transfer resistance includes that due to the external turbulent boundary layer, the interfacial surfactant layer and the diffusion layer within the emulsion globule. The leakage effect of internal phase due to membrane rupture is also discussed in the mathematical treatment. The proposed model predicts satisfactorily the experimental results of the extraction of weak acids as well as weak bases in a batch separation system as presented in the literature.     

乳状液膜分离富集氟离子的应用研究

乳状液膜在分离富集溶液中的微量物质方面获得广泛的应用,本文研究了其对溶液中氟离子的分离富集效果,确定了制备稳定乳状液膜的条件：乳化剂（T-154）∶膜增强剂（液体石蜡）∶溶剂（煤油）=3∶2∶95（体积比）,内水相为3%的Al2(SO4)3溶液,油内比为1∶0.6;讨论了分离富集条件,包括乳水比、溶液pH值、搅拌速度和富集时间等因素;应用于环境水样中氟离子的测定,加标回收率为96%～103%,相对标准偏差RSD（n=6）为2.0%～4.8%,结果令人满意。指出该方法操作简单、成本低、效率高,可用于分离富集废水中的氟离子。     

表面活性剂液膜体系流体力学稳定性的研究

针对液膜的破裂问题,首次提出双重膜破裂机理.根据概率和流体力学有关理论,并在液膜稳定性研究中引入界面粘度的影响,推导了破裂率的数学模型.对模型的适用性进行了检验,计算值和实验值能很好吻合.