填料萃取塔的研究现状及进展

综述了填料萃取塔的特点、国内外对填料萃取塔中填料的选择与开发并且详述了部分填料的工业应用,同时详细阐述了研究者使用不同的理论模型和方法对填料萃取塔的传质特性和流体动力学特性的研究。其中研究方法包括实验方法、经验公式方法及模拟方法。通过实验,能获得准确的液滴直径、分散相体积分数、液泛速度与滑移速度等数据,再通过计算机模拟则能获得详细的流场、温度场、浓度场等微观信息。可以预见,实验方法、经验公式、计算机模拟的有机结合将成为解决填料萃取塔传质和流体动力学问题的有效手段。     

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…     

导向格栅规整填料萃取塔的操作性能

对一种新开发的导向格栅规整填料萃取塔的水力学特性和传质性能进行了系统的实验研究。结果表明,新型导向格栅填料萃取塔的通量比传统萃取塔有了大幅度的提高,当流速比L_R(分散相:连续相)为1:5时,液泛通量达到150 m³·m^-2·h^-1。该填料萃取塔同时具有较好的传质性能,在石油炼制溶剂脱沥青、煤化工废水萃取脱酚等工业过程有良好的应用前景。     

丝网波纹填料塔液泛水力学特征

在炼油、石油化工、精细化厂、食品及医药等部门,塔器均属量大面广的重要单元设备,其投资-般占投资总额的20%左右,有些甚至高达50%,塔器广泛应用于蒸馏、吸收、萃取、洗涤、传热等单元操作中。因此塔器的研究一直受到国内外学者普遍关注。由于规整填料塔具有效率高、压降低、放大效应不明显等优点,使其应用越来越广泛^[1-2]。同时填料塔也是过程工业中能量消耗最大的单元操作之一。在设计填料塔时,一般按液泛气速的60%~70%确定载点气速,按液泛气速的50%~60%确定操作气速。尤其在工业实际应用中,大部分操作都是依据长期积累的操作经验使填料塔工作在所谓的"最优化"操作状态,因此填料塔的操作状态都比较保守,目的都是为了避免塔器在长周期运行过程中发生液泛而停产,给企业带来经济损失。液泛现象一直以来都是制约填料塔设计和提高填料塔能量利用率的瓶颈问题,所以关于预测控制填料塔液泛性能的研究是填料塔优化节能研究的关键^[3-4]。只要能对填料塔的操作状态进行实时监控,根据填料塔工作监控的特征参数,可以实时和及时地调整填料塔的操作性能,从而避免填料塔发生液泛,同时根据工艺和生产的需要实时改变填料塔的操作性能,使得填料塔工作在最优化的状态,也符合节能减排的目的。有关填料塔液泛水力学方面的研究已经有很长一段时间。早期的很多研究者都是从散堆填料的研究推广到规整填料的研究,Sherwood等^[5-6]在测定填料塔水力学压降实验的基础上,讨论了填料塔的载液和液泛现象,并提出了压降通用关联图(GDPC)。Eckert等^[7-9]得到了不同填料类型填料塔水力学压降液泛曲线图。Kuzniewska-Lach^[10]以量纲1方法对填料塔流体物性和填料几何参数进行了分析,提出了基于填料类型的泛点预测。Ondracek等^[11]通过填料塔气体或液体入口速度周期性波动操作,进行了液泛滞后效应的实验研究,对工业塔操作更接近液泛点有一定的指导作用。根据上面的这些研究,分析预测填料塔液泛特征的规律,需要从不同方面进行深入的研究。本文以空气和水为实验介质,研究了规整填料塔在各个操作阶段的水力学特征及区别,得到了填料塔液泛水力学压降离散特征分布规律和压降频率分布规律,为预测控制填料塔液泛现象提供了指导。     

气相扰动下高效萃取填料的开发及性能研究

针对气液液三相萃取,开发出一种新型高效开窗导流式规整填料,该填料片是在板波纹规整填料片的波峰、波谷处开设导流窗口,从而增加气相的流通空间和扰动频率,进而增加液滴的破碎-聚并频率。实验测定了新型填料的流体力学性能及传质性能。实验结果表明:随气相速度的增加,填料的液泛速度降低,传质单元高度先减小后增加。新型开窗导流式规整填料可有效提高分散相的滴膜交替流动频率,增加传质效果,在相同的操作条件下,新型规整填料的流体力学效果和传质效果较超级扁环填料平均提高11%和44.7%。     

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.     

填料类型对脉冲填料萃取塔性能的影响

采用３０％ＴＢＰ（煤油）／ＨＡｃ／水体系研究了脉冲填料萃取塔的流体动力学和传质特性,考察了脉冲强度和填普类型对塔性能的影响。实验表明装填ＱＨ－１型扁环的脉冲填料 性能明显优于装填陶瓷和不锈钢拉西环的脉冲塔。文中给出了装填ＱＨ－１型扁环的脉冲填普塔的特性速度和Ｈｏｘｐ的经验计算式。     

一种新型单体填料性能的研究

一种新型单体填料性能的研究陈伟琳，肖如亭（天津理工学院天津３００１９１）１．前言填料塔是应用在化工生产中的塔型之一，它已成为主要的气、液传质的设备之一。而填料塔的发展和改进，主要反映在填料的发展和改进上。填料是填料塔的核心组成部分，为塔内气、液两相接...     

金属矩鞍环填料的流体力学与传质性能的研究

在TDBY-300多功能填料塔实验装置中,以空气-氨气-水为物系,对金属矩鞍环填料的流体力学与传质性能进行了研究,获得了该填料的几何特性参数和P/Z～Fv、H0～Fv、Hoc～G、HETP～G及KGa～G等关系曲线.结果表明,该填料具有压降适中、通量高、气液分布均匀及传质性能稳定等优点,比较适用于清洁、碱腐蚀性流体的气-液吸收、精馏和萃取等传质分离工业过程.     

聚乙烯扁环填料的流体力学与传质性能研究

在TDBY - 30 0多功能填料塔实验装置中 ,以空气 -氨气 -水为物系 ,对Φ2 5mm聚乙烯扁环填料的流体力学及传质性能进行了研究。获得了该填料的几何特性参数和ΔP/Z～Fv、H0 ～Fv、HOG～G、HETP～G及KGa～G等关系曲线。结果表明 :该填料具有压降适中、通量高、气液分布均匀及传质性能稳定等优点 ,比较适用于清洁、腐蚀性流体的气 -液吸收、精馏和萃取等传质分离工业过程     

Effects of Gas‐Agitation and Packing on Hydrodynamics and Mass Transfer of Extraction Column

The effects of gas‐agitation and packing on hydrodynamics and mass transfer were investigated through experiments with air‐kerosene (benzoic acid)‐water system and corrugated‐packing of calendering plate with hole. The holdup of gas, holdup of dispersed liquid phase and mass transfer coefficient increase and the flooding velocity decrease with the increase in superficial gas velocity. Over‐agitation of gas causes over‐dispersion and emulsification of dispersed liquid phase, reduction of mass transfer performance and even flooding. The mass transfer performance of a packed column is far better than that of an unpacked column.     

Mass transfer in bubble columns packed with motionless mixers

The cocurrent upward mode was employed to absorb pure oxygen into water in bubble columns packed with Koch (Sulzer) motionless mixers. The liquid-side volumetric mass transfer coefficient, K_La, in the packed bubble column was found to be always larger than that in the unpacked bubble column. In the range of liquid velocities from 6.7 cm/sec to 39.9 cm/sec, the value of K_La in the packed bubble column increased with the increasing liquid velocity while that in the unpacked bubble column was almost independent of the liquid velocity. The equation of the formK_La= mν_l^β? was successfully adopted to correlate the K_La data.     

Axial dispersion in a rectangular bubble column

This paper presents the results of an experimental study on the gas holdup and the liquid phase axial dispersion coefficient in a narrow packed and unpacked rectangular bubble column. In both cases the gas and liquid flow rates were varied and the data were obtained by employing standard tracer technique. The gas holdup and the axial dispersion coefficient for both the packed and unpacked columns were found to be dependent on the gas and liquid flow rates. For given gas and liquid velocities and a given packing size in the case of the packed column, the rectangular column gave significantly higher dispersion coefficients than a cylindrical column of the equivalent cross sectional area. This result agrees very well with the one predicted by the velocity distribution model. The correlations for the Peclet number, the axial dispersion coefficient, and the fluid holdup for both the unpacked and packed bubble columns are presented.     

气体搅动的筛板萃取塔性能实验研究

在筛板萃取塔中引入气体搅动,既能明显提高装置的传质效率,又能大幅提高装置处理能力。筛板塔的通量随气速的变化规律与填料塔有显著区别,其性能研究有重要意义。利用煤油(苯甲酸)-水-空气体系,考察了气体搅动和筛孔直径对萃取塔流体力学和传质性能的影响。结果表明,随着表观气速的增加,气含率、分散相含率、液泛速率和传质效率均明显增加。但过高的气速也会导致分散相的过于分散和乳化,传质性能下降,直至液泛。不同直径的筛孔相比,较小的筛孔使分散相停留时间延长,分散相含率和传质效率提高,但液泛速率和处理能力降低。     

复合萃取剂提取林可霉素机理及填料萃取塔中试研究

以中试填料萃取塔为设备研究了复合萃取剂（正辛醇和煤油）萃取林可霉素的宏观特性及传质强化。使用斜率法确定萃合物的结构和反应平衡常数以指导改进设备和强化传质;为了提高林可霉素萃取效果,考察了溶液pH值、相比（W/O）、填料类型、分布盘的使用等因素对提取林可霉素效果的影响。结果表明：以正辛醇为萃取剂萃取林可霉素的过程中,反应平衡常数K为0.072;复合萃取剂中正辛醇最佳含量为0.8（体积分数）;萃取林可霉素的最佳pH值为10～11,最佳相比（W/O）为3;规整填料和散装填料萃取效果有限,分布盘可以大大加强传质,同时加装分布盘的填料萃取塔的单位体积处理量是混合澄清槽的12.8倍,萃取剂循环量大大减少。研究结果对复合萃取剂的萃取机理和填料萃取塔提取林可霉素的实际应用具有一定指导意义。     

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.     

Investigation of hydrodynamic and mass transfer of mercaptan extraction in pulsed and non-pulsed packed columns

We investigated the hydrodynamic behavior and mass transfer characteristics of a pilot-scale conventional packed bed extraction column of mercaptan removal from liquid propane. The extraction column was filled with pall rings structured packing where mercaptan was extracted from the continuous phase to the dispersed phase, accompanied by a chemical reaction in propane-mercaptan-caustic system. The pulsing was introduced into the column to enhance the mass transfer rate. Hydrodynamic parameters such as hold up, flooding velocity and mean drop size were studied together with the effect of chemical reaction on increasing mass transfer performance. Finally, the mass transfer and axial mixing coefficients were obtained from the optimization of data by ADM. It was found that at the pulsation intensity from 0.003 to 0.007 m/s, the maximum mass transfer and minimum axial mixing occurred and it can be concluded that pulsation improves the efficiency of mass transfer just at low intensities.     

PREDICTION OF MASS TRANSFER COEFFICIENTS IN REGULAR PACKED COLUMNS

Developments in the area of packed columns, particularly structured packed columns, are ongoing, specifically in the area of liquid-liquid extractions. Accurate predictions of mass transfer coefficients lead to more accurate design of columns. In the present study, mass transfer coefficients were measured experimentally for packed columns of different heights to study the effect of packing height and specific area. Two experimental pilot regular packed extraction columns were examined using toluene/acetic acid/water and n-butyl acetate/acetic acid/water systems. Based on the results, a novel model for prediction of effective diffusivity has been proposed that is a function of column height and specific area. The mass transfer coefficients obtained by this prediction were compared with other models. The results of this new model are in good agreement with the experimental data. Therefore, this new model can be used to design better regular packed columns.