开孔转盘塔分散相滞存率及液滴直径分布的研究

本文在无传质条件下研究了开孔转盘塔(RPDc)内乳液—水体系(W/O/W)的流体力学性能。测定了塔内分散相滞存率x,考察了塔几何条件及操作条件对分散相滞存率x及特性速度U_o的影响。采用因次分析法,建立了x及U_o与塔几何条件及操作条件间的经验关联式。并采用摄影法,对分散相液滴直径及其分布进行了初步研究。实验结果表明,分散相液滴直径的分布可用上限对数正态分布来描述。     

应用开孔转盘塔进行液膜分离

本文通过无传质条件下油—水、乳化液膜—水体系开孔转盘塔连续操作试验,考察了塔型改变对x～n、u_0～n及n_γ的影响。通过乳化液膜一含酚水体系的传质试验,考察了传质对滞存率χ的影响和连续相pH值及两相密度差(△ρ)的变化对塔传质性能的影响。试验结果表明:开孔转盘塔的液液分散性能远远优于无孔转盘塔,盘上的小孔对经过小孔而上升的液滴有着良好的切割分散作用;除酚试验时,连续相的pH值及两相密度差(△ρ)对传质有影响,传质对滞存率x的影响也十分显著。     

开孔转盘塔(RPDC)分散相滞存率及液滴直径分布的研究

本文在无传质条件下研究了RPDC内乳液-水体系的流体力学性能。测定了塔内分散相滞存率x,考察了塔几何条件及操作条件对x及特性速度u_6的影响。采用因次分析法,建立了x及u_o与塔几何条件及操作条件间的经验关联式。并采用摄影法,对分散相液滴直径d_滴及其分布进行了初步研究。实验结果表明,d_滴的分布可用上限对数正态分布来描述。     

填料萃取塔流体力学特性的研究

本文用三种物系:煤油-水、煤油-26.1％甘油水溶液,二乙基己醇-水。填料塔的直径是75mm,用三种类型的填料:瓷拉西环、瓷矩鞍环、瓷θ环。在无传质的情况下,对填料萃取塔的分散相滞存率和压降进行研究。根据实验数据用线性回归法得到可预测泛点条件下的压降和分散相滞存率的关联式。     

液-液分散性质的研究概况

多相接触器,如反应器、萃取器,其性能无不与相分散的性质有关。分散相尺寸及其分布、相界面积,必然影响两相的流体力学性质、分散相滞存率(hold up)分布和停留时间分布。对于液-液系统而言,液滴的破碎及凝聚速率,对传质效果有重要影响。近年来,溶剂萃取塔的数学模型已有很大进     

搅拌萃取塔特性速度的研究

在内径 φ90的搅拌萃取塔中 ,对分散相特性速度进行了研究。试验用的物系为煤油 -水、煤油 -15 %甘油水、锭子油 -水、2 -乙基己醇 -水。根据试验结果 ,确定了求取特性速度的流体力学模型 ;数据结果还表明 ,搅拌萃取塔的特性速度随转速的变化分两个区域 ,并得到了特性速度及临界转速的估算式     

搅拌萃取塔引入气体后滞液率和气含率的研究

本文在搅拌萃取塔中,对气-液-液三相体系的流体力学进行了研究,讨论了气速与液速对分散相滞液率和气含率的影响,提出了分散相滞液率和表观液速、表观气速及气含率间的关系式。在给定的实验条件下,得到了气含率的关联式。根据实验确定的临界转速,将塔的操作区分为区域Ⅰ和区域Ⅱ,从而为工程放大设计提供理论依据。     

填料特性对鼓泡填料萃取塔性能影响

填料的结构与表面性能对鼓泡填料萃取塔性能有直接影响。利用空气 煤油 (苯甲酸 ) 水体系 ,测定了未装填料和分别装填板波填料、丝网填料、压延孔环填料的鼓泡萃取塔水力学性能和传质性能。实验表明 ,对未装填料和装有填料的萃取塔 ,气相搅拌都可以显著提高液液两相的接触与传质性能 ;液泛速度随表观气速的增大而下降 ;流道设计合理的规整填料传质性能明显高于散装填料 ;表面光滑的填料分散相滞存率低 ,因而液泛速度较高 ;填料的作用有利于降低轴向返混 ,明显提高萃取塔传质性能。     

振动筛板萃取柱操作特性的研究

用煤油(内含30%磷酸三丁酯)-水体系研究了内径为50mm的振动筛板萃取柱的操作特性,其中包括以有机相为连续相时分散相的存留分数,以水为连续相时分散相的存留分数及连续相的纵向混合.实验表明,这种萃取柱在高频率、小振幅的条件下有较好的操作特性.对另外二个工业上的实际体系,即醋酸异丙酯-水(内含10%醋酸、7%硫酸钠)体系和重苯-氨水(内含0.2%酚)体系在振动筛板萃取柱中的流动特性也进行了研究,并给出了液泛特性关联式.     

空气-水/PPG体系的搅拌功率与气含率实验测定

在直径为0.28 m三层组合桨椭圆底圆柱形搅拌釜内,研究了搅拌转速、通气流量及温度对不同体系(空气-水、空气-聚醚多元醇)通气功率特性及气含率特性的影响.结果表明,在相同的条件下,随着通气流量和搅拌转速的增大,两种体系的气含率均升高,相对功率消耗(Pg/P0)均减小;随着温度的升高两种体系的气含率均减小,空气-水体系中相对功率消耗增加,但空气-聚醚多元醇体系中相对功率消耗却减小.并通过多元线性回归得到气含率和相对功率消耗经验关联式,为高温条件下不同气-液体系搅拌釜的设计和放大提供理论参考.     

HYDRODYNAMICS IN YORK-SCHEIBEL COLUMNS

Dispersed phase hold-up, hold-up profile, drop-size distribution and phase inversion were investigated in a third type of Scheibel column (7.6 cm diameter, 18 stage) with toluene-water as the liquid-liquid system. The concept of characteristic drop velocity was used to describe the relationship between dynamic hold-up and two phase flow rates. The axial dispersed phase hold-up and the mean drop size varied significantly with rotor speed and column height. In addition, the characteristics of phase inversion was explained by Sarkar's model.     

HYDRODYNAMICS OF LIQUID-LIQUID-SOLID SYSTEM IN OPEN TURBINE ROTATING DISC CONTACTOR

A number of experiments regarding hydrodynamics have been carried out in the open turbinerotating disc contactor using quartz particles as solid phase,tap water and kerosene as liquid phase.Flooding phenomenon has been observed.The variables studied include the rotor speed,compartment heigh,stator ring opening,column diameter and the superficial velocity of eachphase Correlations for predicting the solid phase holdup and characteristic velocity have been devel-oped.In comparison with liquid-liquid system,the presence of solid particles will result in higherdispersed phase holdup but lower characteristic velocity and total throughput.     

Hydrodynamics and mass transfer performance of rotating sieved disc contactors used for reversed micellar extraction of protein

The extraction of protein by continuous liquid-liquid extraction was investigated in a rotating disc contactor (RDC) and a rotating sieved disc contactor (RSDC) with and without stators. Hydrodynamics and mass transfer performance for reversed micellar extraction of lysozyme in RDC/RSDC I and RSDC II have been investigated. The dispersed phase holdup has increased with the increase of rotor speed. Pratt's equation was used for calculating the characteristic velocity. An inverse relation was observed between the characteristic velocity and rotor speed. The estimated overall mass transfer coefficient was increased by increasing the rotor speed. For an extraction column, the overall hydrodynamics and mass transfer performance can be judged by a volumetric utilization factor. At high rotor speeds, volumetric utilization factor for RSDCs is higher than that of RDC. The RSDC II has been successfully applied in reversed micellar extraction of protein.     

DISPERSED PHASE HOLDUP AND DROP SIZE DISTRIBUTION IN A ROTATING PERFORATED DISK CONTACTOR

Hydrodynamic characteristics of rotating perforated disk contactor(RPDC)were studied with emulsionwater system.The emulsion was dispcrsed in water and its holdup was measured.The effects of columndimensions and operating conditions on holdup and characteristic velocity were studied.By using the methodof dimensional analysis,the authors obtained two experimental correlations for estimating holdup and characteristic velocity respectively.Drop size distribution was studied photographically.The experimental results showedthat drop size distribuiion could be described by upper-limit log-normal distribution.     

Hydrodynamics and mass transport in rotary disk contactors

This paper reports a detailed study of the hydrodynamics involved in the operation of rotary disk contactors (RDC). New information is presented regarding the ‘critical rotor speed’ which divides the two hydrodynamic regimes of near constant and varying characteristic velocity of the dispersed droplet phase. Generalized correlations for prediction of characteristic velocity both above and below the critical rotor speed have been proposed under conditions of no solute transfer as well as solute transfer between the dispersed and continuous phases. Experimental data on mass transfer obtained in the two hydrodynamic regimes of RDC operation have also been correlated by the application of mass transport theory taking into account the factors affecting the interfacial area of contact, drop size, characteristic velocity and dispersed phase holdup.     

Prediction of mass transfer coefficients in an asymmetric rotating disk contactor using effective diffusivity

Mass transfer characteristics have been investigated in a 113 mm diameter asymmetric rotating disk contactor of the pilot plant scale for two different liquid–liquid systems. The effects of operating parameters including rotor speed and continuous and dispersed phase velocities on the volumetric overall mass transfer coefficients are investigated. The results show that the mass transfer performance is strongly dependent on agitation rate and interfacial tension, but only slightly dependent on phase flow rates. In this study, effective diffusivity is used instead of molecular diffusivity in the Gr?ber equation for estimation of dispersed phase overall mass transfer coefficient.The enhancement factor is determined experimentally and there from an empirical expression is derived for prediction of the enhancement factor as a function of Reynolds number. The predicted results compared to the experimental data show that the proposed correlation can efficiently predict the overall mass transfer coefficients in asymmetric rotating disk contactors.     

振动筛板萃取塔的液泛点和塔藏量的研究

在塔径32mm,高1960mm的振动筛板萃取塔中,用叔胺N_(235)-TBP-煤油/水等三个无传质体系,进行了液泛点和塔藏量的研究.作者认为两相流过筛孔的实际相对速度,与塔板在单位时间内对单位质量液体所做的功有关,并与体系物性及板间距相关.由于这种想法,建议用A~2F~3代替常用的AF,可以较好地关联本实验数据,和较简明地反映各参数对液泛点和塔藏量的影响,得到了一个新关联式.研究结果指出:①振幅和频率对液泛点和塔藏量的影响是不同的;②分散相的选择无显著影响,③塔板开孔率和板间距是肯定有影响的.实验的振动强度及体系物性参数的范围较宽,塔板开孔率大,板间距小,并采用金属萃取广泛应用的叔胺及二(2-乙基己基)磷酸苹取剂以及煤油稀释后作为有机相.因此,本工作对推广这种塔于金属萃取将有一定的促进作用.     

新型脉冲萃取塔存留分数与特性速度

为测试锥形穿流塔板的性能,在内径为75mm的脉冲萃取塔中,以煤油-水和10%磷酸三丁酯/煤油-水为实验体系,在无传质条件下,研究脉冲强度与两相表观流速对分散相存留分数和特性速度的影响。结果表明,在实验范围内,存留分数与分散相流速近似成正比,与连续相流速无关。而随着脉冲强度的增大,存留分数先减小,当脉冲强度达到临界值(Af)_t后,存留分数迅速增大。将此临界值与脉冲筛板塔临界值进行对比,两种体系分别减小约9.7%和41.4%,此外,特性速度随着脉冲强度的增大而减小,且界面张力较低的体系减小幅度更大。在实验结果分析的基础上,利用量纲分析方法得到了存留分数与特性速度的工程经验关联式,预测值与实验值符合较好,相对误差均小于20%,可以应用于脉冲萃取塔的设计计算。