螺旋桨搅拌槽中液体的流动结构

在直径１６００ｍｍ的平底柱形有机玻璃槽中，利用热膜风速仪测量了２个搅拌浆－槽体系中流体的时均速度，脉动速度的均方根值，湍流强度，纵向积分尺度，纵向微分尺度和能谱函数。研究了时均速度及湍流微结构在搅拌槽中的分布规律及搅抖转速的影响。     

螺旋桨搅拌槽内湍流参数

在直径494和1600mm的平底有机玻璃槽内,利用一维恒温热膜风速仪测量了7种不同搅拌桨-槽体系中流体的时均速度、脉动速度、能谱函数、微分尺度以及湍流耗散等,对螺旋桨搅拌槽内湍流参数分布进行了详细的描述,研究了叶轮叶端安放角及离底距离对流动场的影响,并分析了放大过程对流动场的影响。     

应用热膜风速仪检测塔板上气液两相流的局部气含率

<正>蒸馏塔板上气、液两相流局部气含率的测定对于研究塔板上流体的流动状态、塔板清液层高度、两相传质性能和设备优化设计等具有重要意义。过去,测量塔板上气液两相流的气含率主要采用γ射线吸收法。该法能检测总体的气含率,但无法测局部气含率,且使用复杂。热膜风速仪是检测气、液两相流速度和气含率的先进仪器,本文采用先进的智能热膜风速仪(IFA-100),并配以微机采样系统,用于测量大型塔板上两相流的局部气含率。     

搅拌槽内局部气含率及其分布规律的研究

搅拌槽内局部气含率及其分布规律的研究高正明，王英琛，施力田，傅举孚（北京化工大学化学工程系，北京１０００２９）关键词：局部气含率，气－液搅拌槽，搅拌１前言气－液搅拌槽反应器在石油化工、生物化工等领域内都得到了极为广泛的应用。但由于受到测试手段的限制，...     

多层新型桨搅拌槽内气-液两相流动的实验与数值模拟

对三层新型组合桨气-液两相搅拌槽内的流体流动进行了实验研究,并采用计算流体力学(CFD)的方法对气-液两相搅拌槽的通气搅拌功率、流场、局部气含率及总体气含率进行了数值模拟,数值模拟采用了欧拉-欧拉方法,数值模拟结果与实验值吻合良好,同时考察了通气流量和搅拌转速对通气搅拌功率和气含率的影响规律. 研究结果表明,欧拉-欧拉方法能较好地模拟搅拌槽内气-液两相流的流动状况.     

多层桨搅拌槽内非常温体系局部气含率分布

引　言局部气含率是气 -液分散的重要特征参数 ,它广泛应用于反映器的分析、选择及设计 .局部气含率与槽内的流型密切相关 ,它能够反映槽内局部的分散及传质特性 ,因此受到研究者的广泛关注[1] .由于受测试手段的限制 ,仅有部分学者对常温下单层桨通气搅拌槽进行了研究[2～ 6] ,而对于工业中广泛应用的多层桨搅拌槽则研究甚少 .许多工业过程是在较高的温度下进行的 ,而已有的研究几乎都是在常温下进行 ,忽视了液体的温度对气 -液两相体系流体力学性能的影响 .常温下的气 -液分散体系 (气体 -常温液体 )主要常见于耗氧性生物发酵、水处理等工…     

挡板进气多级搅拌槽内的气－液分散特性

研究了挡板进气多级搅拌槽内的气－液分散流型、临界分散转速、搅拌功率、气含率和气泡停留时间。试验证明，这种结构的搅拌槽，比标准通气式搅拌槽具有更优良的气－液分散特性，并回归得到了搅拌功率、气含率和气泡停留时间的关联式。     

挡板进气多级搅拌槽内的气—液分散特性

研究了挡板进气多级搅拌槽内的气－液分散流型、临界分散转速、搅拌功率、气含率和气泡停留时间。试验证明，这种结构的搅拌槽，比标准通气式搅拌槽具有更优良的气－液分散特性，并回归得到了搅拌功率、气含率和气泡停留时间的关联式。     

搅拌槽内气液两相混沌混合及分散特性

传统Rushton刚性桨常应用于过程工业中搅拌反应器内的气液分散过程,但由于桨叶背后易形成较大的气穴,气液混合效果较差。为了提高搅拌槽内气液两相的混合效果,提出了一种刚柔组合桨强化气液两相的分散过程。利用Lab VIEW软件处理刚性桨和刚柔组合桨体系中气液混合过程的压力脉动信号,通过Matlab软件编程计算最大Lyapunov指数(LLE),分析气液混合体系的混沌混合行为,同时,对刚性桨和刚柔组合桨体系中的相对搅拌功耗、整体气含率、局部气含率进行测量。结果表明,在功耗为170 W,通气量为10 m3?h-1条件下,与刚性桨相比,刚柔组合桨能够通过刚-柔-流的耦合作用促进桨叶能量的传递过程,提高搅拌体系的混沌混合程度,刚柔组合桨体系的LLE提高了8.89%。同时,在相同操作条件下,与刚性桨相比,刚柔组合桨能够有效提高相对搅拌功耗以及搅拌槽内的整体气含率和局部气含率,且搅拌槽内气体分散更为均匀。     

搅拌槽内气液两相混沌混合及分散特性

传统Rushton刚性桨常应用于过程工业中搅拌反应器内的气液分散过程,但由于桨叶背后易形成较大的气穴,气液混合效果较差。为了提高搅拌槽内气液两相的混合效果,提出了一种刚柔组合桨强化气液两相的分散过程。利用LabVIEW软件处理刚性桨和刚柔组合桨体系中气液混合过程的压力脉动信号,通过Matlab软件编程计算最大Lyapunov指数（LLE）,分析气液混合体系的混沌混合行为,同时,对刚性桨和刚柔组合桨体系中的相对搅拌功耗、整体气含率、局部气含率进行测量。结果表明,在功耗为170 W,通气量为10 m³·h^-1条件下,与刚性桨相比,刚柔组合桨能够通过刚-柔-流的耦合作用促进桨叶能量的传递过程,提高搅拌体系的混沌混合程度,刚柔组合桨体系的LLE提高了8.89%。同时,在相同操作条件下,与刚性桨相比,刚柔组合桨能够有效提高相对搅拌功耗以及搅拌槽内的整体气含率和局部气含率,且搅拌槽内气体分散更为均匀。     

二氧化碳与环己烷,环己酮的二元气液平衡

利用气液双循环的高压气液平衡装置,测定了二氧化碳-环己烷在313.45K和323.3K以及二氧化碳-环己酮在313.25K和323.3K下的二元气液平衡数据。用作图检验法考察了实验数据的热力学一致性。马丁-侯(81)状态方程用于关联两个二元体系的气液平衡数据,计算值与实验值吻合良好。     

Experimental investigation of gas-liquid distribution in monolith reactors

The present work investigates the influence of gas and liquid flow rates on inlet liquid distribution across monoliths operating in gas-liquid cocurrent downflow mode. Gas and liquid superficial velocities range from 0 to 68 and 1.4 to 8.5 cm/s, respectively. Gas-liquid distribution was studied using a packed bed liquid distributor and a pipe distributor for the aforementioned range of operating conditions. To determine the liquid distribution over the monolith, gravimetric, time-averaged liquid collection method was applied using a customized collector apparatus. Quantification of the distribution is reported using a suitably defined maldistribution factor. For each liquid velocity, gas velocities are varied and corresponding maldistribution factors are calculated. The results are reported in view of the varying operating conditions.     

微分散法连续制备微气泡的研究进展

微气泡的尺寸介于1~1000 μm之间。相比于传统大气泡,微气泡具有体积小、比表面积大、上浮速度慢和传质效率高等优点,被广泛应用于石油、化工、食品、化妆品、医学和废水处理等领域。相比于传统的微气泡制备方法,气液微分散法制备微气泡生产效率高、可控性好、灵活性高和易于放大,受到了学者们的广泛关注。鉴于微气泡的广泛应用,快速准确的对气泡的大小和尺寸分布的表征也至关重要。本工作对常用的微气泡尺寸表征方法进行了归纳总结,比较了不同的微气泡制备方法的优缺点,并重点阐述了微通道法和膜分散法制备微气泡的研究现状。在此基础上对微分散法制备微气泡的未来研究方向进行展望。     

SEMIBATCH PRECIPITATION ACCOMPANYING GAS-LIQUID REACTION

To obtain large particles of insoluble product by precipitation accompanying a gas-liquid reaction, a sparged stirred vessel was operated continuously for the gaseous and liquid reactants but batchwise for the product particles. Except at the beginning of run, most particles formed floes. With increasing concentration of product particles, the average size of floes increased for CaC0₃ but remained unchanged or decreased slightly for SrCO₃ and BaC0₃The effect of agitation on the floc size was significant for CaC03 but scarcely observed for SrC0₃ and BaC0₃ The mass per unit volume of sedimented floes of the three species increased with increasing concentration of product particles, and under the same conditions, they decreased in the following order: CaC0₃ SrC0₃ BaC0₃     

水平气固两相高浓度输送流动机理

本文通过水平气固两相分层流动模型，分析了高浓度、高混合比、连续低速气力输送流动机理研究表明，稳定分层流动输送时，悬浮颗粒易集中于滑动床表面；层问颗粒剪切力是滑动床移动的上要驱动力；滑动床高度大于管道半径时将出现不稳定输送     

ATOMIZATION IN A VENTURI SCRUBBER

High speed motion pictures were made or the breakup of a single jet of water in the throat of a venturi scrubber for various air and water jet velocities and different nozzle diameters. Atomization seemed to occur as the result of several different mechanisms, depending on the flow conditions, the most common mechanisms being breakup due to either capillary or acceleration waves and also breakup by “steady shear,” all of which have been observed by other investigators. The so-called “cloud-type” atomization proposed by Hesketh (1970) was not observed despite several attempts to achieve it. Measured values of pressure drop across the test section of the scrubber compare well with previously published results.     

GAS-LIQUID AND MISCIBLE LIQUID MIXING IN A PLANT-SCALE VESSEL MONITORED USING ELECTRICAL RESISTANCE TOMOGRAPHY

A large-scale electrical tomography system has been designed and set-up at UMIST to study imperfect mixing and improve the design of stirred vessels and their impeller configuration at plant-scale. The sensing system was constructed with 8-planes of sensing rings, each containing 16-electrodes and installed into a 2.7 m³ polypropylene vessel fitted with a standard Rushton turbine. Images were reconstructed using the sensitivity theorem algorithms. Some illustrative results for pseudo-stationary gas-liquid mixing and unsteady semi-batch mixing of miscible fluids are reported. Issues related to qualitative and quantitative reconstruction in 2-D and 3-D are discussed.     

THE DIFFUSIONAL LIMITATION ON THE TEMPERATURE RISE IN THE ABSORPTION OF CHEMICALLY REACTIVE GASES

The interfacial temperature is important in gas absorption because it sets the solubility. If the gas undergoes an exothermic reaction this temperature ordinarily exceeds the bulk liquid temperature. For a bimolecular reaction the pseudo-first-order approximation leads to a serviceable model; yet it must overestimate the temperature rise under fast reaction conditions. We correct this estimate by accounting for the depletion of the liquid-phase reactant near the surface. To do this we use an enhancement factor based on the van Krevelen-Hoftijzer approximation. This implies a simple formula for the temperature rise not unlike that based on the pseudo-first-order approximation. We investigate this formula and show that it exhibits either one or three solutions. We deduce criteria for predicting, a priori, both what the multiplicity is and whether or not the maximum temperature rise corresponding to instantaneous reaction obtains.     

A Review of: “THERMAL CHARACTERISTICS OF TUMORS”, edited by R.K. Jain and P.M. Gullino (Volume 335 of the Annals of the New York Academy of Sciences,New York,New York 10021, 1980, 542 pp. $95.00, ISBN 0-89766-046-3).

A relationship has been derived for diffusion of an associating solute forming a dimer complex. Experimental data reported in this investigation for diffusion of acetic acid in carbon tetra chloride, benzene and toluene indicate dimer formation of acetic acid molecules while diffusing into the non-associating solvents.     

滴流床中的气液传质

本文提出了同时估算滴流床内气液传质系数和持液量的阶跃响应S域分析法,着重讨论了液体表面张力对床内气液传质系数的影响,并给出了计算床内气液传质系数和持液量的关联式。