气液固三相环流反应器的研究进展

综述了气液固三相环流反应器的类型及工作原理、气液固三相环流反应器的特性参数(气含率、固含率、循环液速、液相体积传质系数、轴向分散系数)的测量方法和影响因素，介绍了特性参数的数学模型。并对现有模型进行了评述。对今后的研究提出一些建议。     

高长径比气液固三相内环流反应器的流体动力学

在高径比为22的三相内环流反应器中,常温常压下,根据动量平衡原理建立了空气-水-石英砂三相物系的循环液速模型,并建立了上升区气含率、上升区固含率和底部换向区阻力系数模型;考察了在不同颗粒粒径下,表观气速对上升区固含率和液体循环速度的影响。结果表明:当粒径(ds)≤0.3mm时,上升区固含率随表观气速的增加变化呈平缓趋势,当0.3mmds≤1.2mm时,上升区固含率随表观气速的增加而呈先下降后增加的趋势;不同粒径下上升区循环液速均随表观气速的增加而增加;气含率、固含率和循环液速的计算值和实验值吻合较好,其平均相对误差分别为6.32%、4.56%和11.97%。     

高长径比三相内环流反应器中细颗粒相含率和循环液速的分布研究

在高径比为22的三相内环流反应器中,在常温常压下以空气-水-石英砂为物系,研究了在不同粒径下上升区固含率、下降区固含率和上升区循环液速随表观气速的变化规律和不同粒径下轴向固含率的分布情况,以及在固体体积分数不同的条件下,平均气含率和上升区气含率随表观气速的变化情况。结果表明:当粒径(ds)≤0.3 mm时,上升区固含率随表观气速的增加呈平缓变化趋势,下降区固含率随表观气速的增加而增加;当0.3 mm相似文献   

气升式环流反应器在不同体系下的循环液速和局部气含率

在气升式环流反应器中,分别研究了空气—水、空气-0．1％乙醇水溶液和空气-水-活性污泥体系中的循环液速以及气含率随操作条件的变化规律。实验结果表明,循环液速随着表观气速的增加而增大,不同体系中的循环液速差别不大;导流筒内、外不同高度处的局部气含率均呈自下向上增大的趋势,且导流筒内部气含率高于导流筒外部的气含率。体系的聚并特性对平均气含率和局部气含率有较大影响。     

强制浆液外循环三相气升式内环流反应器的气含率特性

在有机玻璃制成的组合反应器(φ0.284×3.0 m)内,采用空气、水和玻璃微珠(密度为2420 kg/m3和平均粒径为5.92×10-4 m)的气液固三相体系考察了不同表观气速下环流反应器内不同流动区域的径向局部气含率和内、外环轴向平均气含率分布特性.局部气含率采用电导探针法测定,轴向平均气含率由局部气含率的截面积分得出.结果表明气含率均随表观气速的增大而增大;外环循环流入内环的气泡量少;在相同条件下外环的气含率远远低于内环的气含率.浆液外循环的引入和新型气体分布器的采用可以增大导流筒内气体与浆液两相的接触面积和湍动强度,从而使传递过程得到了强化.     

气升式环流反应器特性参数的研究进展

介绍了气升式环流反应器的工作原理、分类及流型,综述了气升式环流反应器的流体力学特征参数(主要包含气含率和循环液速)、混合及传质特性参数的测量方法和影响因素。介绍了气含率和循环液速的数学模型,并评述了现有模型。展望了气升式环流反应器进一步的研究方向与发展前景。     

气升式环流反应器特性参数的研究进展

介绍了气升式环流反应器的工作原理、分类及流型,综述了气升式环流反应器的流体力学特征参数(主要包含气含率和循环液速)、混合及传质特性参数的测量方法和影响因素。介绍了气含率和循环液速的数学模型,并评述了现有模型。展望了气升式环流反应器进一步的研究方向与发展前景。     

电导探针法测量高固含体系循环液速和气含率

基于电导探针和示踪法,开发了一种利用电导探针同时测量环流反应器中高固含体系下循环液速和局部气含率的方法. 利用2个单针电导探头测量脉冲注入KCl饱和溶液后两路电导信号的先后响应,测得两路液体的停留时间分布曲线. 通过对单路信号进行幅值分析可以得到气含率,与压差法相比测量值误差小于5%;通过对过滤气泡信号后的液体的停留时间分布曲线进行相关处理可得到循环液速,测量值与超声多普勒(UDV)的测量结果一致. 实验研究了外环流反应器中操作条件对气含率和循环液速的影响. 结果表明,低表观气速下气含率沿径向分布较均匀,高于0.1 m/s后逐渐呈抛物线型分布,整体随表观气速增加而增大;循环液速随表观气速增加近似线性增大,随固含率增加而减小.     

底部间隙对多室环流反应器流动特性的影响

在空气-水-石英砂三相多室气升式环流反应器(MALR)中,调节底部转角连接处间隙高度分别为18,28,38mm,在表观气速1.2～4.2cm/s范围内,实验研究了底部阻力系数、相含率、循环液速随反应器底部间隙的变化规律。结果表明,随着底部间隙的增大,底部转角处的局部阻力系数减小,循环液速增大,流体夹带进入下降室的气泡和固体颗粒均增多,下降室的气含率和固含率均增大。     

连续内环流三相反应器局部流动特性

在φ200 mm×2500 mm连续内环流三相反应器内,考察了空气 水 玻璃珠体系反应器内局部流动参数随操作条件的变化规律。结果表明,导流筒内截面平均气含率随表观气速的增大而增大,较之气液两相流,在低固含率时,加入固体对气含率影响不明显,而在较高固含率下,气含率有明显降低,但固体再增加时对气含率变化影响不大。在较低表观气速下,进料浆速对导流筒内气含率轴向分布趋势有一定的影响,但在较高表观气速下影响不大,导流筒内的气含率大于环隙内的气含率且随气速增大差别更加明显,浆相连续有利于气相分散并增大环隙内的气含率。导流筒内循环浆速径向分布呈抛物状,中心高、近壁处低,受进料浆速和入口固含率影响都不大。浆相循环强度最低为20,高可达180。固含率轴、径向分布受表观气速和进料浆速的影响,固含率轴、径向分布基本均匀,随进料浆速增加,反应器内固含率降低。     

Radial Profiles of Gas Bubble Behavior in a Gas‐Liquid Bubble Column Reactor under Elevated Pressures

The effects of operating conditions on radial variation of gas holdups, bubble swarm rising velocity, and Sauter mean diameter were investigated in a bubble column reactor under elevated pressures using a conductivity probe method. Air served as gas phase and tap water as liquid phase with varying gas velocity and pressure. All three parameters increased constantly with higher superficial gas velocity. Maximum holdup, velocity, and Sauter mean diameter were found at the center of the cross section. Two different cases for Sauter mean diameter distribution were observed. The gas holdups increase continuously with higher system pressure, but decrease for bubble swarm rising velocity and Sauter mean diameter. According to experimental results, an empirical correlation of the gas holdup profiles is presented.     

低含液率多相管路平均持液率

The experimental study on average holdup in multiphase pipelines with low loads of liquids was conducted on a large multiphase flow loop. The average holdup increased with increasing liquid load and decreased with increasing gas velocity, and also depended on the undulation of pipeline and flow patterns in the pipeline. The effects of eight dimensionless parameters on average holdup were seriated with grey relational degree analysis so as to find the most important factors affecting the average holdup in multiphase pipelines with low loads of liquids. An average holdup correlation based on low liquid loads was also developed and the correlation related the most important three factors including superficial gas velocity number (Ngw), superficial liquid velocity number (Nlw) and liquid Reynolds number (Rel) to the average holdup. Finally the correlation was tested with the field data and the result was satisfying.     

环流反应器流体力学参数测定技术研究

介绍了环流反应器流体力学参数的测定方法,这些参数包括气含率、循环液速、固含率、气泡大小及速度。综述了这些参数测量方法的原理、设备及优缺点,评价了它们目前的发展状况及动向,提出了参数测定方法今后工作的重点,对于环流反应器的流体力学研究具有重要的指导意义。     

Effects of internals on phase holdup and backmixing in a slightlyexpanded-bed reactor with gas-liquid concurrent upflow

Five different internals were designed, and their effects on phase holdup and backmixing were investigated in a gas-liquid concurrent upflow reactor where the spherical alumina packing particles of three diameters (3.0, 4.5 and 6.0 mm) were slightly expanded under the conditions of varied superficial gas velocities (6.77×10^-2-3.61×10^-1 m·s^-1) and superficial liquid velocities (9.47×10^-4-2.17×10^-3 m·s^-1). The experimental results show that the gas holdup increases with the superficial gas velocity and particle size, opposite to the variational trend of liquid holdup. When an internal component is installed amid the upflow reactor, a higher gas holdup, a less liquid holdup and a larger Peclet number characterizing the weaker backmixing are obtained compared to those in the bed without internals under the same operating conditions. Additionally, the minimal backmixing is observed in the reactor equipped with the internals with a novel multi-step design. Finally, empirical correlations were proposed for estimating gas holdup, liquid holdup and Peclet number with the relative deviations within 11%, 12% and 25%, respectively.     

Hydrodynamics in an Internal Loop Airlift Reactor with a Convergence‐Divergence Draft Tube

Gas holdup and liquid circulation of one conventional draft tube and three different convergence‐divergence draft tubes in an internal loop airlift reactor were investigated. Experiments were carried out in two‐phase systems with air‐water and air‐CMC (carboxyl methyl cellulose) solution and three‐phase system with air‐water‐resin particles. The two‐phase drift‐flux model was used to estimate gas holdup for three‐phase Newtonian and two‐phase non‐Newtonian systems. It is shown that gas holdup in convergence‐divergence draft tubes is higher than that in a conventional draft tube and increases with superficial gas velocity. Variation of the structural parameters of convergence‐divergence draft tubes has little effect on gas holdup in the two‐phase and three‐phase system. The mathematical model, which is based on a drift‐flux model, was developed to describe the liquid circulation velocity in the reactor satisfactorily.     

Flow regimes and mass transfer in counter-current bubble columns

Counter current bubble columns have the feature that specific gas-liquid interfacial area and gas holdup are larger than those for standard and cocurrent bubble columns. In this study, three different flow regimes, churn-turbulent flow, bubble flow and bubble down-flow, have been observed in a counter-current bubble column and correlations of gas holdup and volumetric liquid-phase mass transfer coefficient have been proposed as functions of operating variables such as the superficial velocities of gas and liquid, the gas-liquid slip velocity and the liquid properties.     

气升式环流反应器数值模拟研究进展

介绍了计算流体力学在气升式环流反应器(二相、三相)中的应用,汇总并介绍了气升式环流反应器的气含率和循环液速的二维与三维数值模拟结果,提出今后进一步的研究方向。     

气升式环流反应器中的流体动力学研究(Ⅱ)——实验及模型结果分析

建立了一直径为0.186m、高3m的内环流气升式反应器。通过电化学方法测得了反应器中的气含率和速度。本文以文(Ⅰ)所得气升式环流反应器的一维两流体模型为基础,推导出了反应器的能量方程。分析了反应中的功耗分配规律,并以此对反应器中的流动规律作了较合理的解释。本文还从理论和实验上较全面地讨论了反应器操作参数和结构参数对气含率和循环液速等的影响。