界面湍动对气液传质的影响

气液传质过程中经常伴有界面湍动。界面湍动由传质的不均匀性引起,反过来又极大地促进传质。介绍了界面湍动的产生机理和形成条件,对4种不同Ra和Ma准数的情况分别进行了分析。讨论了界面湍动强度对气液传质系数的影响关系。传质系数与Man成正比,其中n随着Marangoni对流胞类型的不同而在1/3和1之间变化。在气液系统中,液相与气相阻力比越大,由界面湍动引起的传质的增强效应越显著。     

气液传质过程的界面湍动

界面湍动对相际传质具有重要影响。利用显微激光全息干涉技术研究了 CO2 在乙醇 -水溶液中吸收过程的界面湍动情况 ,实验观察了界面湍动强度与溶液浓度的关系 ,结果表明 ,乙醇浓度越高 ,界面湍动强度越大 ,文中对此进行了分析和讨论。     

湍球塔吸收低浓度尾气NH_3的传质系数研究

脱除尾气低浓度氨是氨法烟气碳减排不可缺少的环节。采用湍球塔(TCA)进行实验研究,测定总体积传质系数(Kga),考查化学吸收和流化数等因素的影响。结果表明:化学吸收比物理吸收Kga增大63%。随流化数增大成比例增大,但流化数不能过大,否则会因气体在塔内停留时间太短而降低脱除效率。     

尾气脱氨湍球塔临界流化速度研究

根据湍球塔流体动力学试验数据,得到临界流化速度、最佳操作气速及带出速度随静止床高H0和喷淋密度Ld的变化关系,计算的干塔临界流化速度与实测值对照基本吻合。根据试验数据回归了有喷淋液时临界流化速度的关联公式。     

气液两相流壁面剪应力及传质系数测试方法探讨

探讨了不加支持电解质条件下，液固传质系数及壁面剪应力的测试方法及测量垂直管中弹状流区上升液体段和下降液膜段的双电极测试技术，并尝试用空气作为测试体系的气相。     

界面性质对气液传质的影响

界面性质对气液传质有重要影响。分子通过界面时需克服界面自由能，界面两侧的浓度不一致。本文导出了两者之间的关系     

气液传质界面湍动现象投影观察

In gas-liquid mass transfer processes,interfacial turbulence may occur due to the surface tension gradient and the density gradient produced by mass transfer near the interface.The interfacial turbulence can enhance the mass transfer since it intensifies the movement of interfacial fluid.By means of the shadowgraph optical method,the interfacial turbulence patterns vertical to the interface were observed directly in the volatilization process of binary systems.The images of the amplified interfacial turbulence showed the variation of concentration and the fluid movement under the interface.Two patterns of interfacial turbulence were observed in the experiments：plume and vortex.With the plume,the interfacial fluid moved slowly and penetrated the liquid deeply.With the vortex,the interfacial turbulence occurred in the vicinity of the liquid interface and the fluid moves quite fast.A qualitative analysis was carried out based on the mechanism of Rayleigh-Bénard convection induced by density gradient and Marangoni convection induced by surface tension gradient.     

湍球塔流体动力特性分析及设计研究

本文主要介绍了湍球塔的基本构造和工作流程并对湍球塔的流体动力学特性进行了理论分析,结合室内实验条件和要求确定了湍球塔的结构参数和流体动力学参数,完成了室内实验条件下的湍球塔的设计计算。通过试验测试可知,在本文设计参数下运行的湍球塔系统流态化性能稳定,脱硫效果好,可为实现工业规模的设计应用提供参考依据。     

三相循环流化床中的气液相界面积和传质系数

采用溶氧法测量了三相循环流化床中液相溶氧浓度的轴向分布,并按轴向扩散模型处理实验数据,优化得到气液体积传质系数kLa,同时用光纤探头测量了体系中的气含率和气泡大小分布,计算得到了气液相界面积a和气液传质系数kL,并研究了主要操作条件(表观气速、表观液速和固含率)对气液传质系数的影响规律.     

提升管三相流化床内的气液传质系数

采用溶氧电极法测定了以牛顿和非牛顿流体为液相的提升管三相流化床的气液传质系数（ｋｌａ）。证明其值受床层流动特性的影响显著，那些能提供高气含率和增大液体循环速率的操作条件也有助于ｋｌａ的提高。通过引入广义雷诺数得出了计算牛顿和非牛顿流体内ｋｌａ的关联式     

Flow Regime Maps for Flow of Liquid Through Downcomer in a Turbulent Bed Contactor

The provision of a downcomer to classical turbulent bed Contactor (TBC) increases the gas treating capacity of the equipment. When the downcomer is provided, it is expected that all the liquid passes through the downcomer only without any liquid flow through the distributor. In the present study, the operational regime for the flow of liquid only through the downcomer is experimentally evaluated for various geometric parameters and particle characteristics. It is observed that the preferred operational regime without dumping and weeping increases with an increase in Archimedes number and downcomer diameter, and decreases with an increase in static bed height and downcomer weir height. Correlations are proposed to satisfactorily predict experimentally observed operational regime.     

三相生物流化床的相含率及气液传质性能研究

采用内循环三相生物流化床,用清水进行了在不同活性炭载体加入量下,当进气量改变时流化床内的气液传质性能的实验,认为当Ug≥0.75m^3/h时,随着气体流量增加,可改善流化床的氧传质效率,缩短循环时间和混合时间,提高气含率,但过高的气体流量（Ug≥1.1m^3/h）并不利于流化床的操作。载体加入量增加,会导致氧传递性能下降,循环时间和混合时间缩短,气含率减小。     

Comparative Modeling and Analysis of the Mass Transfer Coefficient in a Turbulent Bed Contactor using Artificial Neural Network and Adaptive Neuro-Fuzzy Inference Systems

This study deals with predicting the gas film volumetric mass transfer coefficient (K_oga) in a turbulent bed contactor (TBC), using both artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) techniques. The networks have been trained and evaluated with the experimental data available in the literature. Input variables to the networks are process variables such as gas and liquid phase concentration, gas and liquid superficial velocities and also specific area of packings. The results obtained the ability of developed ANN and ANFIS for prediction of K_oga. Although it was observed that both ANN and ANFIS models provided a good statistical prediction in terms of coefficient of determination (R²), mean relative error (MRE) and root mean square error (RMSE), the accuracies of ANFIS predictions were better than those of ANN predictions.     

乳状液膜分离Zn^2＋的界面传质阻力及传质模型

用Ｌｗｅｉｓ恒界面传质池对乳状液膜分离Ｚｎ＾２＋的传质阻力进行实验研究，结果表明由于表面活性剂单分子层的形成，使界面传质阻力占整个传质阻力的８５％。在此基础上所建立的既考虑界面传质阻力又考虑膜破碎的液膜传质模型能使用理论计算值与实验测定值符合较好。     

Ozone Mass Transfer in the Mixing Zone of a Confined Plunging Liquid Jet Contactor

In a Confined Plunging Liquid Jet Contactor (CPLJC) a jet of liquid is introduced into an enclosed cylindrical column (downcomer) that generates fine gas bubbles that are contacted with the bulk liquid flow. The region where the liquid jet impinges the receiving liquid and expands to the wall of the downcomer is called the Mixing Zone (MZ). In the MZ, the energy of the liquid jet is dissipated by the breakup of the entrained gas into fine bubbles, and the intense recirculation of the two-phase mixture. The study presented here was undertaken to quantify the ozone-water mass transfer performance of the MZ through the determination of the volumetric mass transfer coefficient, k_La (s^?1), and to produce a model for predicting k_La based on the specific energy dissipation rate. It was found experimentally that k_La in the MZ increased with increasing superficial gas velocity. A maximum experimental k_La value of 0.84 s^?1 was achieved which compares well to other contactors used in water treatment. Such a large k_La value combined with the small volume of the reactor, favorable energy requirements and safety features of the system, suggests that the CPLJC provides an attractive alternative to conventional ozone contactors. The relatively large mass transfer rates were found to be a function of the high gas holdup and fine bubble size generated in the MZ, which results in an almost froth-like consistency. A model based on the specific energy dissipation rate of the water jet, E (kg · m^?1· s^?3), and MZ bubble size was used to predict k_La in the MZ. Using E, the number average bubble size was predicted which was then used to calculate the liquid phase mass transfer coefficient k_L. The bubble size was also used with the predicted mixing zone gas holdup to calculate the specific interfacial area, a (m^?1), which was then combined with k_L to determine a predicted value of k_La. The average deviation between experimental and predicted k_La was 6.2%.