LOCAL OVERALL GAS-LIQUID VOLUMETRIC MASS TRANSFER COEFFICIENTS IN A GAS-LIQUID TWO-PHASE REVERSED FLOW JET LOOP REACTOR

Local overall gas-liquid volumetric mass transfer coefficient profiles at the specified point were experimentally investigated in a gas-liquid two-phase reversed flow jet loop reactor with Newtonian and non-Newtonian systems. It was observed that the local overall gas-liquid volumetric mass transfer coefficient profiles of this reactor with Newtonian and non-Newtonian systems increase with increase in gas jet flow rates and liquid jet flow rates, and with decrease in nozzle diameter and CMC concentration.     

喷射式气-液反应器传质特性的研究

为改善鼓泡塔的传质性能,气体和液体以喷射形式进料,这是喷射式气-液反应器的显著特征。本文对这种反应器的传质特性进行了实验测定和计算,着重考察了喷射对全塔传质效果的影响。研究结果表明,反应器内明显地存在着两个不同的区域,即喷射区和主体区。而且,喷射区的传质作用十分强烈,其传质系数K_Lα比一般鼓泡塔或搅拌釜高出1～2个数量级。     

液体中气—液射流特性的研究

在气-液两相喷射式装置中气体或/和液体是经由单个(或多个)喷咀射入塔内的。本研究用频闪摄影技术对气、液向上共同喷射时液体中的气-液射流特性进行了实验研究,并建立了气泡直径分布函教及射流特征尺寸的关联式。同时,对射流两相区内两相的流动用一两相模型进行模拟,考察了喷咀直径、初始条件、液体压头和气泡直径对器内两相流动的影响。     

DISENGAGEMENT ENERGETICS AT THE SURFACE OF AERATED REACTORS

Aerated reactors are widely used in cell culture processes. The bubbles that are introduced into such reactors provide essential mixing and oxygen, but the disengagement of those bubbles can result in the imposition of undesirable stresses upon fluid-borne cells. This occurs because some of the energy associated with interfacial tension is converted to high-velocity motions in the form of film rupture, droplet ejection and bubble cavity collapse. Obviously these effects would be amplified if there was an affinity between the cells and the gas-liquid interface. The present work was carried out in an effort to better characterize the energy, frequency of occurrence, and periodicities of these phenomena. This investigation examined the effects of fluid (medium) properties, bubble size, and gas rate upon both film and jet droplet ejection processes, as well as upon pressure disturbances measured at the reactor wall just beneath the free surface     

气液固三相循环流化床气液传质行为

<正>气液固三相流化床反应器在石油化工、湿法冶金、环境工程和煤的液化等工业领域得到了广泛应用,其基础研究也取得了很大进展.但是,传统三相床主要应用于低液速(U_L<     

GAS-LIQUID MASS TRANSFER IN JET BUBBLE COLUMN

The jet bubble column consists of a conical entrance section which expands to a cylindrical column. Gas and liquid are co-currently introduced at the bottom of the column by a small diameter inlet pipe which acts like an ejector. The kinetic energy of the gas and liquid jet together with the conical geometry at the lower section of the column cause the formation and dispersion of small bubbles.

Gas-liquid mass transfer in the jet bubble column (61 cm diameter) was measured by a dynamic response technique, in which a step change was made in the gas phase oxygen concentration and the aqueous dissolved oxygen concentration response was measured at various axial and radial locations. It was found that a continuous stirred tank reactor model could be used to evaluate experimental results. The volumetric mass transfer coefficient in this type of system was found to increase with increasing gas flow rate and was about 1.5 times larger than the values obtained at similar conditions in conventional bubble columns. Preliminary measurements and calculations indicate negligible effects of liquid velocity and bed height on the mass transfer coefficient.     

VOLUMETRIC MASS TRANSFER COEFFICENTS OF GAS LIQUID JET LOOP REACTORS BY OXIDATION OF HYDRAZINE

Oxidation of hydrazine in the presence of a homogeneous catalyst (CuTeSP) has been proved as a suitable reaction for the determination of volumetric mass transfer coefficients k_La of stirred tank reactors. This method is applied to a gas liquid jet loop reactor (JLR).At power inputs of N/V_R≤ 8 kW/m³ k_La values of about 0·1 and 0·4s^-1 were achieved. The evaluated values agree well with those determined by a stationary physical method.     

PREDICTION OF A GAS-PARTICLE TURBULENT JET WITH THE FLUCTUATION-SPECTRUM-RANDOM-TRAJECTORY MODEL

A numerical treatment for determining the particle velocity and the trajectories in a two-phase flow is described herein and this new fluctuation-spectrum-random-trajectory (FSRT) model is proposed to account for the turbulent diffusion of particles. It is predicted for the flow of a turbulent axisymmetric gaseous jet laden with spherical solid particles of nonuniform size. The particle velocity and the concentration field are obtained by the revised volume average method. The predictions are compared with experiment.     

GAS INDUCTION AND HOLD-UP CHARACTERISTICS OF LIQUID JET LOOP REACTORS

Gas induction and hold-up characteristics of liquid jet loop reactors (LJLR) have been studied. From the results of these investigations with various diffuser geometries the effect of various parts of the diffuser on the rate of induction, Q_G, and the gas hold-up, E_G, have been discerned. Two different diffuser designs yield highest E_G and Q_G, respectively. The use of draft tube has been found to increase the gas hold-up by 25-60% over those in its absence. Correlations for Q_G and E_G involving the main geometrical parameters of the nozzle-diffuser combinations and the liquid jet power input have been developed.     

气液撞击流洗涤脱硫的实验研究

以石灰石悬浮液为吸收剂,在气液撞击流洗涤器内进行了烟气脱硫实验,着重研究了液气比、循环浆液的pH值、进气SO2浓度和吸收剂质量浓度对脱硫效率的影响,分析了各因素对脱硫效率产生影响的原因.实验结果表明,在浆液pH值大于6.1,进气SO2浓度小于1657mg/m3的条件下,较低的液气比L/G和较低的吸收剂浓度就能达到95%以上的脱硫效率,增大液气比L/G和吸收剂浓度,脱硫效率可达99%以上.本实验结果在单喷头中试装置上得到了进一步的验证.     

THE MASS BALANCE FOR GAS PHASE REACTIONS IN TUBULAR REACTORS

In this paper we discuss the use of an approximated form of the mass balance equation for a tubular reactor in which a gas phase reaction is carried out. By means of three examples it is shown that if density variations are not taken into account in a correct way, surprisingly high errors can occur. More specifically, if the mass balance is written down in a generally applied approximate form, i.e. using udc/dz instead of d(uc)/dz—u, c and z respectively being the gas velocity, concentration and length coordinate—even for density variations as low as 5%, errors of a magnitude higher than 5% can be introduced. This is particularly true for multiple reaction systems. The inexpediency of approximating d(uc) by udc is stressed: the approximation is in no way a simplification. Therefore, this commonly seen approximation should never be applied.     

改善高氯卤化银乳剂的高照度性能

本实验制备了高氯卤化银立方体系列乳剂和高氯卤化银（100）晶面T颗粒乳剂，对高氯卤化银立方体乳剂进行了不同种类掺杂剂的掺杂试验。通过测定以上各乳剂在常规曝光和高照度曝光下的照相性能，表明了在高氯卤化银乳剂中掺杂碘化物、掺杂铱络合物和掺杂浅电子陷阱杂剂都可以不同程度地改善乳剂的高照度性能，几种改进措施的结合效果更好。     

整装反应器起燃阶段传热的数学模拟

整装反应器已经广泛地应用于催化领域,其暂态传热特性对反应器的起燃有重要作用。本文研究了整装反应器在反应点火前起燃阶段的传热,通过对绝热反应器建立的简单一维传热数学模型的求解,分析了固相轴向导热、气流性质、催化剂性质及反应器设计参数对传热的影响,比较了用金属体和陶瓷体时基体热响应的不同。     

下喷式环流反应器的气含率特性

本文以空气-水和空气-CMC 水溶液为实验体系,研究了气速、液速、体系物性以及反应器结构尺寸等参数对下喷式环流反应器全塔平均气含率的影响,得出最优的导流筒直径与反应器直径之比为0.57,提出了牛顿型与粘度较低的非牛顿型流体体系中气含率的计算关联式:■_G=0.3157[(D_E/D_R)~2-1.14D_E/D_R+0.55]~(-3.312)·n~(0.9142)·((ρ_G·μ_G)/(ρ_L·μ_L))~(0.01899)·Fr_■~(0.3884)·Fr_L~(0.2918)     

Investigation of extraction fraction in confined impinging jet reactors for tri-butyl-phosphate extracting butyric acid process☆

The extraction fraction E and overall volumetric mass transfer coefficient kLa of TBP extracting butyric acid pro-cess in confined impinging jet reactors (CIJR) with two jets were investigated. The main variables tested were the concentration of tri-butyl-phosphate (TBP) and butyric acid, the impinging velocity V, the impinging velocity ratio of two phases Vorg/Vaq, the nozzle inner diameter di and the distance L between the jet axes and the top wall of the impinging chamber. The results showed that E and kLa increase with an increase of the impinging ve-locity V, the concentration of TBP Corg, and the impinging velocity ratio Vorg/Vaq. However, E and kLa decrease with an increase of the inner diameter di from 1 to 2 mm, the concentration of butyric acid Caq from 0.5%(v/v) to 2%(v/v). The factor L ranging from 3 to 11 mm has a negligible effect on E and kLa. A correlation on these variables and kLa was proposed based on the experimental data. These results indicated good mass transfer performance of CIJR in the extraction operation.     

下喷自吸环流反应器中气-液局部相际传质模型

引言 下喷自吸环流反应器是在结合喷射、环流、自吸等优点基础上而开发出的一种新型高效反应器,开展该反应器内局部气液传质模型的研究,对于该反应器的优化设计及放大具有极重要的理论意义.多年来,经典传质理论的不足与局限都在经历不断的修正与改进.其中,激光多普勒测试在传质研究中的应用使得人们对湍流在传质中的重要性有了     

EFFECT OF SPREADING COEFFICIENT ON GAS-LIQUID MASS TRANSFER IN GAS-LIQUID-LIQUID DISPERSIONS IN A STIRRED TANK

Gas-liquid mass transfer in an aerated stirred tank containing two liquid phases (a heptane/dodecane solution dispersed in water) was investigated by measuring the saturation of heptane in the exit gas. Heptane saturation as a function of organic phase composition in a gas-liquid-liquid system supports the view that the organic phase spreading coefficient, S, is an extremely important factor in the mass transfer rate in gas-liquid-liquid systems. When the spreading coefficient of the organic solution changes from negative to positive, the outlet gas becomes saturated, corresponding to a severalfold increase in mass transfer coefficient. This clearly reinforces the hypothesis that the mass transfer pathways between organic and gas phase change depending on the sign of S, leading to a different structure of mass transfer resistances: when S > 0, there is direct contact between gas and organic phase; when S < 0, there is not. At S close to 0, the situation is intermediate, there being some evidence that turbulent kinetic energy may play a role in determining the amount of direct contact between gas and organic phase.     

射流撞击过程中的高频压力脉动特性

引　言利用两束射流相互撞击或单射流撞击靶在微细颗粒制备、多相流快速微观混合及团聚颗粒单分散过程中具有特殊优点。用作预混合器或反应器 ,能够强化微细颗粒的成核与生长环境在微观尺度上的均匀性 ,尤其对于快速反应体系 ,可实现液液或液固多相流快速微观混合 ,有效控制反应过程和产物指标 .Ｍａｈａｊａｎ等[1] 利用两束撞击流实现流体的快速微观混合以合成超细微粉 ,并用萘酚与重氮苯磺酸两步反应表征两束撞击流体数十毫秒的微观混合时间 ,关联微观混合时间与射流速度的关系 ,通过控制射流的微观混合时间控制合成超细微粉的粒度分布 .…     

滴流床反应器的脉冲特性

滴流床中气液流速较高时会产生脉冲流。脉冲特性可表示为：脉冲频率、脉冲速度、脉冲持液与脉冲间持液。这些参数可用气液流速、填料特性及气液物性来度量。在宏观物料衡算基础上推得脉冲速度的模型。脉冲持液就是反应器的动持液；脉冲持液与脉冲间持液之比近于1．5。发现脉冲频率完全受表观液速与临界液速的差值所控制。获得了三个关联式，涉及不同系统，也包含文献数据。     

高反差显影机理

在前文中,我们从高反差与乳剂颗粒群体的还原方式以及与乳剂颗粒间显影诱导期分布的关系出发分析了Lith显影的特点。Lith显影只是高反差显影的一点特例。由于Lith显影液保存性不好,实际上人们常用的是一些其它提高反差的方法,例如在乳