气液搅拌体系中宏观气含率的预测

采用压差法和电阻探针测定了空气-水混合体系的气含率,用扭矩仪测量扭矩和转速,计算输入功率.将气体分成进出停留气体A和内循环气体B两部分,建立宏观气含率的物理模型.结果表明,针对不同气液混合流型,将宏观气含率分成两个阶段是合理的,εtotal=αVsβ适用于气泛状态,εtotal=αVsβ+χPVγVsθ适用于载气和气体完全分散状态,对于DT+DT组合桨α=6,β=1,χ=0.32,γ=0.56,θ=1.模型对文献数据的预测较合理,且具有一定的适应性,χ取决于搅拌桨类型.     

气液两相并流体系气含率的表达式及其应用

本文基于气液两相分相流模型和动量守恒原理,并结合若干假定,建立了气液两相并流流动体系的气含率一般表达式,给出了由测定压降利用该表达式在确定管内气液垂直向下并流体系气含率中的应用,验证表明Ｈｉｌｌ提出的气液两相垂直向上并流流动体系的气含率表达工为本文建立一般公式当θ＝９０°时的特例。     

不同温度下空气-聚醚多元醇的搅拌特性

在直径为0.28 m椭圆底搅拌釜内,以空气-聚醚多元醇为实验物系,对20～120℃范围内不同温度下两种三层组合桨的搅拌功率及气含率特性进行了实验研究,并获得了不同组合桨的相对功率消耗及气含率关联式。结果表明：随着通气流量和搅拌转速的增大,两种组合桨的气含率均升高,相对功率消耗均减少;随着温度的升高,两种组合桨的气含率和相对功率消耗均减小。但组合桨Ⅰ（底HEDT＋中WHu＋上WHu）的综合性能要优于组合桨Ⅱ（底6XYK＋中6XDT＋上HEDT）,有利于获得较高的气含率和通气搅拌功率,更适合用于聚合体系气-液两相混合操作过程中。     

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。     

双层桨自吸式搅拌槽气-液分散性能

对一双层桨自吸式搅拌槽内气液分散性能进行了研究,在有无定子两种情况下,对比了不同桨型组合的搅拌功率、相对功率消耗、气含率和容积传氧系数。结果表明:自吸式搅拌槽可以有效降低功率消耗;6P-6PDTU(抛物线型桨与六叶上斜叶桨)组合的功率消耗小于6DT-6PDTU(六直叶圆盘桨与六叶上斜叶桨)组合,相对功率消耗更接近于1;气含率和容积传氧系数小于6DT-6PDTU组合。研究表明,虽然6DT-6PDTU组合的搅拌功率较大,且不利于气液分散和混合,但吸气量和气液两相之间的传质效果较好。     

搅拌槽内温度对气含率的影响

Gas holdups in ambient gassed and hot sparged systems with multiple modern impellers and the effect of temperature on gas holdup are reported,The operating temperature has a great impact on gas holdup though the gas dispersion regime in the hot sparged system is similar to the ambient gassed condition,The gas holdup under the elevated temperature and the ambient gassed operation is successfully correlated.With the sarme total gas flow rate and power input,the gas holdup in the hot sparged system(say near the boiling point)is only about half of that in the ambient system ,The results imply that almost all existing hot sparged reactors have been designed on the basis of incorrect estimates of the gas holdup during operation.     

非标准釜中双层桨的搅拌功率和气含率

在装有单层或双层蛇管换热器的搅拌釜中，分别以六直叶圆盘涡轮（ＤＴ）、四叶（４５°）折叶桨（４ＩＢＴ）或六叶（４５°）折叶桨（６ＩＢＴ）为上层桨，ＤＴ为下层桨，测定了不同双层桨的搅拌功率和气含率。结果表明，搅拌功率随蛇管层数、液位高度和桨间距的增加而增大，但气含率随液位的上升而下降。在装有双层蛇管换热器的搅拌釜中，ＤＴ与６ＩＢＴ双层桨的通气搅拌功率Ｐａ和气含率α的关联式为Ｐａ＝２．４９（Ｐ０２ＮＤ３／ＱＧ（０．５６））（０．３７）及α＝０．０２９Ｐ＿ｖ￣（０．４８）ｕ＿ｓ￣（０．４７）。     

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，...     

低含液率气-液两相流研究现状分析

在石油天然气工业中,低含液率气-液两相流动广泛存在于湿天然气管道中。湿气输送管道内经常含有水和天然气凝析液,这些液体的存在会导致沿管线的压降明显增加。而压力梯度的预测对于选择合适的管材和确定管道尺寸有直接的影响。因此,在湿天然气输送过程中,研究低含率气-液相流动的流动特性是非常重要的。本文针对低含液率气-液两相流动的研究现状进行了综述和分析。     

基于截面气含率的文丘里湿气压降模型

运用两相流理论对湿气中的气相与液相流动进行分析,在分层流与环雾状流的条件下推导了两相流通过水平标准文丘里流量计的理论模型.通过分别考虑截面气含率、相间摩擦以及液滴夹带等因素,在文丘里轴向对湿气流动中的气相动量方程进行求解.通过对水平直管中的截面气含率公式进行修正,建立了适用于收缩管道的截面气含率模型,并在此基础上模拟了湿气流经标准文丘里时其两个取压孔之间的轴向静压分布.实验证实,使用修正后的截面气含率公式将使模型对文丘里压降的预测准确度明显提升,其相对误差在15%以内.该模型以湿气两相流在水平文丘里中的流动形态为依据,具有较充分的物理背景,而且在推导过程中较少依赖特定实验装置与数据,为建立具有一定普适性的文丘里湿气计量模型奠定了基础.     

气泡细化过程中气含率的实验研究

应用压差法测定局部气含率,用膨胀法测定平均气含率.分别讨论了中心和偏心搅拌模式下气体流量、搅拌转速等因素对局部气含率和平均气含率的影响,以及局部气含率沿径向的变化规律.结果表明,中心双向搅拌和偏心单向搅拌均可显著提高气含率,且后者更有效;在筒内壁附近的气含率无论何种搅拌方式均随着气体流量的增大而增大;中心搅拌下的气含率随着径向距离的增大而下降,但偏心搅拌则在不同的位置气含率沿径向的变化表现出不同的变化趋势:平均气含率无论中心和偏心搅拌均随流量增加,但随转速的增加中心搅拌模式下气含率变小而偏心搅拌模式下的则增大.     

齿边导向浮阀塔板局部气含率的研究

自制双探头电导探针,并用该电导探针在内径300 mm×400 mm的矩形有机玻璃塔内,以空气-水为物系,对塔板的局部气含率进行了测试,研究齿边导向浮阀的结构对塔板局部气含率的影响。结果表明:齿边导向浮阀塔板的导向孔对增大塔板底部的气含率有着重要作用;齿边导向浮阀周边齿形的结构使得浮阀周边气含率的分布呈现齿形状;齿边导向浮阀的齿边结构使得浮阀阀面上的气含率增大。     

Experimental Investigation of Gas Holdup and Slug Lengths in an Upflow Monolith Reactor

A new non‐invasive visualization technology was successfully developed to determine the hydrodynamics parameters of Taylor flow in monolith channels. With the developed method, the gas and liquid slug lengths as well as the gas holdup in channels of different radial positions were measured. Accordingly, the average gas holdup in different radial zones and the mean slug lengths over the monolith cross‐section were calculated with varying superficial gas and liquid velocities. By defining the maldistribution factor, the degree of non‐uniform distributions of these parameters over the monolith cross‐section was investigated quantitatively. The results showed that a moderate gas‐to‐liquid velocity ratio can result in uniform distribution for both gas holdup and slug lengths. In addition, the obtained mean slug lengths were well correlated with simplified Qian and Lawal correlations.     

加压环流反应器气含率分布实验研究

在Φ600mm×6000mm的中心气升式不锈钢环流反应器内,选用水、氮气、氩气作为实验介质,在连续进料的操作条件下,表观液速UL为0.008m·s-1,表观气速Ug范围是0.02~0.12m·s-1,在体系压力0~2.0MPa的压力条件下进行实验,测量了各个区域的气含率。结果表明环流反应器各个区域的气含率各不相同,但均随空塔气速以及体系压力的增加而增大。相同的工况下,添加正丁醇的体系气含率明显高于纯水体系,对于确定体系的环流反应器,循环液速不会随体系压力和空塔气速增大而一直增大,当体系压力和空塔气速大过某一个值时,循环液速基本不再变化。     

中心气升式三相强化环流反应器内局部气含率分布的实验研究

在连续操作的状况下,在φ300mm×1700mm 的中心气升式三相强化环流反应器内,测量了 0.0059m·s~(-1)≤Ugr≤0.1895m·s~(-1)、Ucir=0、0.0307、0.0511m·s~(-1)、ε_(Ls)=5%、10%、15%时反应器内不同轴、径向位置处的气含率。实验发现,连续操作的中心气升式强化内环流反应器可以分为 6 个不同的流动区域:内环分布器下部区、分布器区、中心下料管影响区、导流筒上行区、气液分离区和环隙区,各区域内的气含率分布各不相同,但均随着 Ugr 的增加而增加。外循环液体的引入使气含率在导流筒内沿径向的分布更趋于均匀。在本实验范围内固体颗粒装载量对整体气含率影响较小,在内、外环间循环的气泡量可以忽略不计。测量了不同 Ucir时的气泡穿透深度,得出了气泡实现循环的临界气速。     

Novel Aerosol/Gas Inlet for Aircraft-Based Measurements

A novel inlet has been designed for selective sampling of gas and aerosol phases of volatile species from high-speed aircraft. A multistage flow system brings the flow nearly isokinetically towards the sampling port. Two small airfoil-shaped "blades" are placed close to the sample port to provide the flow conditions required for aerosol and gas sampling. Aerosols are sampled when these blades are positioned to operate the inlet as a counterflow virtual impactor (CVI). The design enables sampling of particles as small as 0.1 w m from a high-speed aircraft under stratospheric conditions, a substantial improvement over that possible with previous CVI designs. For gas sampling, one of the blades is moved by a stepper motor to occlude the inlet opening and gas is sampled perpendicular to the bulk flow. Boundary layer suction is used to prevent the sampled gas from coming in contact with the impactor walls. This is one of the first designs of an inlet that enables gas sampling free of wall contact. The inlet was flown on the NASA ER-2 aircraft during the SOLVE 2000 campaign to study aerosol/gas partitioning of nitric acid in the lower stratosphere. Data from the flight tests show that the inlet flow characteristics are broadly in agreement with computational fluid dynamics (CFD) simulations.     

Intrinsic Hydrodynamic Investigation of Three-Phase Bubble Column: Comparative Experimental Study on Gas Holdup

Theoretical Foundations of Chemical Engineering - A comprehensive experimental study of the hydrodynamic behaviors for the specific system of air/paraffin oil/silica particles in a slurry bubble...     

基于搅拌功率公式法的浮选浓度对粘度和搅拌功率影响研究

通过检测出不同浓度的矿浆粘度值,进而计算出对应的搅拌功率;通过比较搅拌功率大小和浓度大小的变化,从节能的角度选择合适的浮选矿浆浓度.矿浆浓度对搅拌功率影响试验研究发现,随着矿浆浓度的增加搅拌平均功率逐渐减小且矿浆浓度的增加幅度远大于搅拌功率增大的幅度.     

Studies of Gas Holdup in Bubble Column Reactors

Gas holdup in bubble columns has been investigated over a wide range of operational and geometrical parameters. A criterion has been developed for the prediction of the transitional velocity from the homogeneous to heterogeneous flow regime. Correlations for gas holdup in both regimes are developed and verified against experimental data.