脉冲填料萃取塔性能强化的研究

针对己内酰胺等工业装置脉冲填料萃取塔扩能改造的迫切要求,在(φ)100mm的实验塔中用四种体系研究了填料类型、脉冲强度、体系物性和操作条件等对脉冲填料萃取塔流体力学和传质性能的影响.实验结果表明,QH-1型扁环填料的处理能力和传质效率明显高于拉西环填料.脉冲强度对塔内分散相的液滴平均直径、存留分数和塔性能具有重要影响.因此,填料的选型和脉冲强度的调优是脉冲填料萃取塔强化的关键因素.     

一种新型高粘性物料萃取设备

本文讨论了多种形式塔盘结构对粘度高达187～2426cP物料萃取效果的影响。对塔内径为142mm及500mm的萃取塔,分别对转盘、栅板塔盘、齿形塔盘、多孔转盘以及网格塔盘进行静态传质实验。结果说明,网格塔盘传质效果最好。此外,还对塔内径为152mm、高为2m的转盘塔和网格塔进行两相逆流传质实验并进行比较,证明新型网格塔传质效率可提高一倍以上。并获得网格塔传质单元高度与转速、流率、粘度及滞存率等各因素的关联式。     

转盘塔的纵向混合

<正> 一个成功的逆流萃取塔应该满足生产能力大、界面传质速率高、纵向混合低三个要求,而这三个因素又是和塔型、生产规模和有无外加机械能的输入有关的。本文研究的转盘塔是一种有外加机械能输入的微分型萃取装置。该器有回转平盘与在萃取操作中两逆流液相之间紧密接触。故而,通常界面传质速率主要与液相在塔内的回转速度有关。调节此独立变数会增大两相界面积,从而有利于界面传质速率。但却会因降低轴向浓度梯度的纵向混合程度的显     

基于CFD的搅拌萃取塔结构优化与流场分析

为降低搅拌萃取塔内轴向返混并增大通量，在搅拌筛板萃取塔基础上改进内部结构，设计了返混相对较轻的搅拌萃取塔。通过停留时间分布模拟，结合返混模型和流场分析，研究了通道面积、环隙位置、开孔方式和澄清段高度等因素对流体流动特性的影响。结果表明，级间转动挡板可以有效抑制塔内轴向返混，且挡板直径越大，塔内通道面积越窄，抑制返混效果越好；固定环开孔和级间挡板开孔均会带来一定程度的返混，尤以搅拌桨下方的级间挡板开孔影响最为严重；设立澄清段可以降低塔内返混，且澄清段高度越高返混越小，实际应用时考虑到设备成本，澄清段高度与塔径之比以0.7左右为宜。     

中空纤维更新液膜在己内酰胺精制中的应用

研究了中空纤维更新液膜技术用于己内酰胺精制时的传质性能,考察了两相流速、萃取剂用量对传质的影响,并与大块液膜技术以及萃取塔技术进行了对比。在实验范围内,中空纤维更新液膜过程总传质系数随两相流速的增大而增大,且壳程流速对传质的影响较大。中空纤维更新液膜过程传质通量可达大块液膜的1．5倍,总体积传质系数可达工业萃取塔的2．3倍,萃取剂用量相比于大块液膜、工业萃取塔大幅度降低,具有很大的应用潜力。     

多锥孔转盘塔在液膜萃取中的应用

液膜分离技术是一项崭新的工艺。本文在探索分离设备转盘塔设计的基础上,通过改进塔内构件—采用了多锥孔转盘,提高了传质速率,避免了返混和液泛现象,使转盘塔分离效果得到了显著提高。通过二级处理,使含酚废水含酚量达到排放标准。     

糠醛精制转盘塔的瓶颈分析及其技术改造

本文分析了糠醛精制转盘萃取塔的现状和局限性,介绍了新型填料萃取塔的研究和应用进展,提出了采用ＱＨ－１型扁环填料的技术改造方案。通过对上海炼油厂糠醛精制转盘塔技术改造的实践,　说明ＱＨ－１型扁环填料萃取塔用于糠醛精制具有突出优点。     

空气搅动的填料萃取塔性能实验研究

引　言气体搅动是一种外加能量的萃取方法 .与机械搅拌相比 ,气体搅动的萃取塔内无运动部件 ,操作稳定 ,结构简单 ,能耗低 .过去已有数篇关于气体搅动的混合 -澄清槽[1] 、喷洒塔[2～ 4 ] 、多级连续萃取器[5] 等无填料的萃取过程水力学性能和传质性能的文献报道 .而在填料塔萃取过程中加入气体搅动技术 ,一方面继承了填料可以有效地降低轴向返混的优越性能 ;另一方面 ,通过外加能量进一步强化液 -液两相接触与传质 ,提高传质系数 ,综合了外加能量的萃取技术和填料萃取技术的优点 .关于这方面的内容目前少有报道[6] .1　实验装置与实验方法…     

萃取塔数学模型及过程强化的若干研究进展

萃取塔因生产能力大、占地面积小、密闭性好等优点,在石油、化工、生物、医药和环境工程等多领域被广泛应用。本文从以下几个方面介绍了萃取塔近些年的研究进展：综述了传统萃取塔（脉冲萃取塔、转盘塔与Kühni塔等）的水力学、轴向扩散与传质模型的发展,分析比较了表面张力、传质方向、放大效应等因素对模型的影响;介绍了计算流体动力学（CFD）在萃取塔中单液滴、单相流模拟、液-液两相流模拟、外加能量模拟、与群体平衡模型（PBM）耦合模拟中的应用进展;介绍了国内外设计开发的新型萃取塔,包括改变传统塔的内构件和引入多种外场能量等方式来强化相间传质。研究表明,将先进实验研究方法、准确经验模型和可靠理论计算相结合,将会是萃取塔研究的重要手段和方向。     

转盘式萃取塔在氧化蜡水洗中的应用

转盘塔是一种高效液一液萃取设备。国内外在石油、化工等行业已迅速推广。它多应用于丙烷脱沥青、润滑油糠醛精制、己内酰胺的三氯乙烯萃取和水萃取、水洗丁二酸等。转盘塔是一个立式圆筒。筒内壁装有等距离的固定环,中心轴上于固定环正中间装有动盘,可随中轴旋转。整个装有转盘的部分为萃取段,另于塔上下部有沉降段,由栅板与萃取段隔开。轻相液(氧化蜡)由塔下部萃取段进。     

转盘萃取塔的改进

引　言转盘塔 (ＲＤＣ)具有结构简单、通量大、造价低、操作维修方便等优点 ,得到广泛应用 .但ＲＤＣ靠平滑转盘在全塔上、下一致地对连续相(ｃ)和分散相 (ｄ)整体输入能量造成以下问题 .( 1 )转速ＮＲ 较高 ,导致ｃ相轴向混合严重、能耗大、转轴晃动厉害 ,塔内界面张力σ大的物系更是如此 ;( 2 )液滴平均直径ｄｐ、持液率轴向分布过宽 .即进口端液滴不能被最初几块转盘充分分散 ,ｄｐ 大上升快 ,小 ,较长一塔段 (约 0 .5ｍ左右 )不能发挥有效作用 .而液滴上升过程中会被转盘不断分散 ,以至出口端分散过度 ,ｄｐ 过小、偏大 ,易过早出…     

应用多孔转盘的转盘塔进行液膜分离的初步研究

采用带多孔转盘的转盘塔作为液膜分离的连续操作装置,进行了流体力学和传质特性的初步研究.实验表明:开有小孔的转盘塔板具有良好的液液分散性能和传质性能,适用于液膜分离的连续操作.     

A PRELIMINARY STUDY ON LIQUID MEMBRANE SEPARATION IN ROTATING DISK CONTACTORS WITH PERFORATED DISKS

A rotating disk contactor (RDC) with perforated disks was employed for liquid membrane separation. Hydrodynamic characteristics and rate of mass transfer in the contactor were studied. Experimental results indicated that the rotating perforated disks contributed tremendously to liquid-liquid dispersion as well as to the rate of mass transfer. It is claimed, therefore, that contactors equiped with perforated disks is well adaptable to the continuous processing of liquid membrane separations     

开式涡轮转盘塔用于液液固体系的性能研究

由转盘塔改型的开式涡轮转盘塔是一种新型的搅拌萃取塔,它适用于固含量较高的体系.其特点是每个转盘下方有3条叶片.选用水-煤油-石英砂体系,以丁酸为溶质,在内径52mm的塔中作流体力学和传质实验.结果表明,传质方向对液体分散相滞留率、固相滞留率和体积传质系数都有一定影响.固体颗粒的存在可降低扩散单元高度,但对传质并不总是有利.     

Liquid—liquid extraction column (rotating disc contactor)—model parameters from drop size distribution and solute concentration measurements

The practical application of an extraction column model which takes into account the influence of drop-size distribution (i.e. the ‘forward mixing’ model) is brought forward by the generation, from experimental data, of values of the mass transfer and axial dispersion coefficients required by the model. Values of these coefficients were generated from drop-size distribution and solute concentration profile measurements in a 22 cm diam. rotating disc contactor. The use of the Handlos-Baron drop mass transfer model is justified. The resulting continuous phase transfer coefficients were found to be dependent only on disc speed. Continuous phase axial dispersion coefficients were much higher than tracer-correlation predicted values at higher flows, and larger drop sizes. An explanation for this is presented.     

A NEWLY DEVELOPED LIQUID-LIQUID EXTRACTION COLUMN——The Open Turbine Rotating Disc Contactor(OTRDC)

The experimental study on hydrodynamics,axial mixing and mass transfer has been carried out in anewly developed liquid-liquid contactor,the open turbine rotating disc contactor(OTRDC).It has been foundthat the OTRDC is possible to be operated with higher hold-up of dispersed phase,larger interface and hencehigher efficiency of mass transfer comparing with the ordinary RDC.In correlating axial mixing data,a combinedmodel has been used in which both forward mixing due to the drop size distribution and backmixingof droplets are taken into account.The RTD curves of dispersed phase predicted by the model were fit wellwith the experimental data.The comparison of the experimental mass transfer data with thosc predicted by theaxial mixing model and theoretical single drop models shown they are in good agreement.     

Use of axial dispersion model for determination of Sherwood number and mass transfer coefficients in a perforated rotating disc contactor

The mass transfer process in a perforated rotating disk contactor (PRDC) using a toluene-acetone-water system was investigated.The volumetric overall mass transfer coefficients are calculated in a PRDC column.Both mass transfer directions are considered in experiments.The influences of operating variables containing agitation rate,dispersed and continuous phase flow rates and mass transfer in the extraction column are studied.According to obtained results,mass transfer is significantly dependent on agitation rate,while the dispersed and continuous phase flow rates have a minor effect on mass transfer in the extraction column.Furthermore,a novel empirical correlation is developed for prediction of overall continuous phase Sherwood number based on dispersed phase holdup,Reynolds number and mass transfer direction.There has been great agreement between experimental data and predicted values using a proposed correlation for all operating conditions.     

Modelling of liquid-liquid extraction columns: Use of published model correlations in design

Design of several liquid-liquid extraction columns — packed, pulsed-packed, pulsed-plate, Oldshue-Rushton columns and the rotating disc contactor — was attempted utilizing available correlations for drop size, holdup of dispersed phase, flooding velocities, mass transfer coefficients and axial mixing coefficients. Correlations in many cases were vaguely defined and often based on very limited data. Results indicated that for given flow rates and extraction efficiency, the height of a packed or Oldshue-Rushton column must be considerably greater than the predicted minimum heights of the other three columns, which were comparable considering the limited data utilized in the developed correlations. A critical evaluation of the correlations should be carried out to guide the further experimental effort required to confirm the utility of the axial dispersion model in liquid-liquid extraction column design. Extension of the theory to include drop size variation is highly desirable.     

New Approach in the Prediction of RDC Liquid‐Liquid Extraction Column Parameters

The liquid‐liquid extraction process is well‐known for its complexity and often entails intensive modeling and computational efforts to simulate its dynamic behavior. This paper presents a new application of the Genetic Algorithm (GA) to predict the modeling parameters of a chemical pilot plant involving a rotating disc liquid‐liquid extraction contactor (RDC). In this process, the droplet behavior of the dispersed phase has a strong influence on the mass transfer performance of the column. The mass transfer mechanism inside the drops of the dispersed phase was modeled by the Handlos‐Baron circulating drop model with consideration of the effect of forward mixing. Using the Genetic Algorithm method and the Numerical Analysis Group (NAG) software, the mass transfer and axial dispersion coefficients in the continuous phase in these columns were optimized. In order to obtain the RDC column parameters, a least‐square function of differences between the simulated and experimental concentration profiles (SSD) and 95 % confidence limit in the plug flow number of the transfer unit prediction were considered. The minus 95 % confidence limit and sum of square deviations for the GA method justified it as a successful method for optimization of the mass transfer and axial dispersion coefficients of liquid‐liquid extraction columns.     

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.