Effect of system properties on the performance of liquid-liquid extraction columns—1: Packed column

Mean drop size, fractional hold-up of dispersed phase, and axial mixing have been determined in a 72 mm dia. packed column, packed with 8 mm glass Raschig rings, using the systems toluene-acetone-water and MIBK-acetic acid-water, in an attempt to assess the effects of the solute transfer processes on column operation.For the MIBK-system, where the packing size corresponded to the normal recommended conditions d_p > d_FC (packing size greater than the critical size of packing), solute presence and the direction of solute transfer was found to affect drop size, fractional hold-up and the axial mixing in the dispersed phase appreciably, in a manner which was consistent with either suppressed or enhanced coalescence characteristics according to the appropriate changes in solute system.For the toluene system, however, with the packing size corresponding to the condition d_p < d_FC, the drop behaviour was dominated by the action of the packing void spaces and mean drop size was independent of solute presence and direction of transfer.In both cases, axial mixing in the continuous phase was independent of solute effects, except in so far as these changes modified hold-up of the dispersed phase.     

Active surface of the elements of irregular heat and mass transfer packings

The mechanisms of active surface formation in irregular heat and mass transfer packings were analyzed. The packings under study included Raschig, Pall, and GIAP-N3 rings and Intallox saddles. The efficiencies of GIAP-N3 packings of different sizes under different gas and liquid loads were compared. The packing designs were compared in terms of the useful factor of packing.     

Hydrodynamics and mass transfer in a pulsed packed column

The hydrodynamics and mass transfer characteristics of a pulsed packed column (PPC) filled with a stainless steel super mini ring (SMR), ceramic and stainless steel Raschig rings have been studied using a 30% tributyl phosphate‐kerosene (dispersed phase)/acetic acid/water (continuous phase) system. Experiments were performed in a 100 mm internal diameter column with 1.0 m height of packing. The mass transfer and axial mixing parameters were estimated simultaneously from the measured concentration profiles of two‐phase based on the backflow model. It was found that pulsation has great influence on hydrodynamics and mass transfer characteristics of PPC with the SMR. H_oxp and H_ox decrease significantly with pulsation, whereas flooding velocity decreases only slightly. Comparison among the three types of packing showed that the SMR has superior characteristics both in terms of capacity and mass transfer efficiency. The influence of mass transfer on characteristics of PPC was also studied. New empirical equations of characteristic velocity, H_oxand H_oxd were proposed and good agreement between calculated and experimental data was obtained.     

Static Sheet-Metal Packing for Liquid-Liquid Extraction

Results of investigations of sheet-metal packing, type Montz Bl-300, for liquid-liquid extraction processes are presented. Equations for hold-up of the dispersed phase and for the height of the unit of mass transfer, D°C, are confirmed by using the systems: toluene (D)/water, toluene (D)-acetic acid/water and toluene (D)-acetone/water under normal conditions. According to the results sheet-metal packings of the investigated type have good prospects for industrial applications, particularly for large raffinate streams provided the height of the packing elements is less than 50 mm.     

ENZYME MASS TRANSFER COEFFICIENT IN AQUEOUS TWO PHASE SYSTEMS: SPRAY EXTRACTION COLUMNS

Fractional dispersed phase hold-up and overall dispersed phase side mass transfer coefficients were measured in 34, 50, 70 and 95 mm i.d. spray columns using an aqueous two phase system. Sodium sulphate-polyethyleneglycol (PEG) (4000)-water formed the aqueous two phase system and amyloglucosidase was used as a solute for the estimation of mass transfer coefficient.

The dispersed phase hold-up (e_D) and volumetric dispersed phase side mass transfer coefficient (K_D) both increased with increasing PEG-rich phase velocity. The e_Dand K_Dawere found to be independent of the column diameter and column height above a certain critical value. An increase in the phase concentration of sodium sulphate and PEG was found to reduce e_Dand K_DEmpirical and semi-empirical correlations for e_D and K_Dahave been developed.     

Prediction of liquid phase hold-up in random packed beds

Experimental data on liquid phase hold-up in packed beds consisting of Raschig rings, Lessing rings and spheres are presented. A generalized correlation has been proposed for predicting the liquid phase hold-up in terms of packing density equivalent spherical diameter, liquid viscosity, density and flow rate.     

Kon─Tane填料流体力学和传质性能研究

介绍了Ｋｏｎ─Ｔａｎｅ填料的特点，对其进行了流体力学与传质性能的测试，并回归了ＳＯ＿２吸收的传质系数方程。通过与φ３×３及φ６×６拉西环填料的对比表明，Ｋｏｎ─Ｔａｎｅ填料具有优良的流体力学和传质性能。     

Performance of Spray,Sieve Tray,and Packed Contactors for High Pressure Extraction

Abstract

The performance of various contactors in high pressure extraction service was studied. The mass transfer efficiency of a spray column and columns filled with sieve trays, 1.27 cm ceramic Raschig rings, and no. 15 metal Intalox saddles were obtained from a “windowed” high pressure extraction column with an internal diameter of 9.88 cm and a column height of 168 cm. The extraction column has an internal diameter of 9.88 cm and a contacting height of 168 cm. Glass windows in the extractor allowed visual observation and photography. Supercritical and liquid carbon dioxide were used to extract isopropanol from water at pressures of 81 to 150 atmospheres and 297 to 318 [ddot]K. The sieve tray extractor yielded the highest mass transfer efficiency followed closely by Raschig rings and metal Intalox saddles. The spray column was by far the least efficient. The mass transfer efficiency was observed to be independent of the operating conditions studied in this work. Sauter mean drop diameters and dispersed phase (free) hold-up were also obtained in this work. These data will provide a reliable high pressure mass transfer and hydraulic database for future correlation and design efforts.     

Mass transfer in packed liquid—liquid extraction columns

The mass transfer characteristics of 3·5, 7·3, 10·16 and 15·6 cm i.d. packed liquid—liquid extraction columns were studied with a variety of packings such as, $\text{3}\text{8}$, $\text{1}\text{2}$ and 1 in. ceramic Raschig rings, $\text{5}\text{8}$ in. stainless steel Raschig rings, $\text{1}\text{2}$ and 1 in. ceramic Intalox saddles, $\text{5}\text{8}$ and 1 in. stainless steel Pall rings, and 1 in. polypropylene Intalox saddles and Pall rings. Some data were also obtained for the co-current mode of operation (up-flow) for packed columns, and without packings. In addition the mass transfer charactersitics of a packed extraction column with film flow were studied.The theory of extraction accompanied by a fast pseudo-first order reaction was employed to measure the values of effective interfacial area. The values of overall (continuous and/or dispersed phase) mass transfer coefficient were measured by the Colburn—Welsh technique. A fairly wide range of physical properties of the two phases was covered.The values of overall (continuous phase) mass transfer coefficient and effective interfacial area for new packings such as Pall rings and Intalox saddles, under otherwise similar conditions, are only about 10 and 35 per cent higher, respectively, than those provided by the conventional packings of the same nominal size. However, the flooding velocities for the newer packings are as much as 80 per cent higher than those for the conventional packings of the same nominal size.     

Hydrodynamique et transfert gaz-liquide dans un réacteur verlifix rempli de différents garnissages

This study concerns several Verlifix three phase reactors formed by the association of a jet venturi upper on a column filled with different solid packings. The gas and liquid flows are downstream cocurrent. Four packings are studied: glass Raschig rings, Coming's monolithic ceramics, microporous alumina pellets and glass beads. For these packings and gas and liquid flow rates fixed, we measure the hydrodynamic characteristics (flow regime, liquid dynamic retention, pressure drop) of the fixed bed and gas-liquid mass transfer conductance of the whole reactor, then we specify the influence of the operative conditions and the type of packing.     

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…     

Liquid/Solid Mass Transfer in Fixed Beds

The liquid/solid mass transfer behavior of a fixed bed of cylinders was studied using the diffusion‐controlled dissolution of copper in acidified potassium dichromate. Variables studied were solution velocity and cylinder diameter. For a steady flow, the data were correlated for the conditions 25 < Re < 600 and Sc = 990 by the equation Sh = 2.65 Sc^0.33 Re^0.5. A comparison between the present data and previously obtained data for a fixed bed of Raschig rings has revealed that cylinder packing produces higher rates of mass transfer than Raschig rings.     

Process Engineering Evaluation of Modern High Performance Packings for Mass Transfer Apparatus

Modern packing technology is presented in terms of correlations and criteria for an extensive evaluation of up-to-date packing design used in current mass transfer operations. The corresponding basic information covers the process engineering aspects, e.g. volumetric effectiveness and optimum geometry of the packing, and the techno-economic aspects, e.g. when selecting a packing adopted in practice for a certain application task. The correlations required for this investigation are derived and evaluated on the basis of a comprehensive experimental research by testing and comparison of modern packings, such as Raschig Super-Rings and reference packings. The results thus obtained are correlated and presented in graphic presentation of diagrams, figures and tables.     

Ergebnisse einer Untersuchung der Gasverteilung über dem Querschnitt einer Füllkörperkolonne

The gas distribution has been investigated over a cross-section of a 472 mm diameter column assembled with two types of inlet devices with and without equalizing packing layer, respectively. The minimum height of Raschig rings, Pall rings, Intalox saddles and four types of horizontal expanded sheet packing, at which a uniform velocity profile can be obtained, was found. It is shown that when applying these packings no increase occurs in the velocity of the nearwall layer.     

新型组合式规整填料在液液萃取中的传质性能

采用质量分数30%磷酸三丁酯-煤油-醋酸-水物系,对一种新型萃取用组合式规整填料的传质性能进行了测定,考察了连续相流速和分散相流速对其传质效率的影响。实验结果表明:在相同的二相流速下,组合式规整填料的表观传质单元高度比16 mm鲍尔环平均低约54%。固定连续相流速,随着分散相流速的增加,填料的表观传质单元高度降低,传质效率提高;固定分散相流速,随着连续相流速的增加,填料的表观传质单元高度增大,传质效率降低。     

Raschig Super‐Ring Operating Characteristics in Unpulsed Liquid‐Liquid Extraction Columns

Raschig Super‐Rings are well‐established in the field of rectification and absorption. Instead, the efficiency of these packings in liquid‐liquid extraction was not investigated till now. The application of Raschig Super‐Ring No. 0.3 and Raschig Super‐Ring No. 1 packings in unpulsed liquid‐liquid extraction columns of diameters DN 80 and DN 150 is investigated with respect to flooding point and efficiency. As a comparative study, 15‐mm and 25‐mm Pall‐Ring packings are used. The hydrodynamic studies indicate that the Raschig Super‐Ring offers a 9–10 % higher load capacity compared to the Pall‐Rings. In addition, the mass transport investigations performed using the test system toluene/acetone/water reveal that the height of transfer units (HTU) for the Raschig Super‐Ring No. 0.3 is higher than for the comparable 15‐mm Pall‐Ring. On average, the achieved difference of the HTU unit is 0.26 m.     

气-液-液萃取的流体力学研究

在液-液萃取过程中,提高分散相的表面更新速率可有效提高萃取的传质效率。研究发现,在萃取过程中使用气体搅拌可以增加液液之间的接触面积,促进液相内的湍动和循环。本文研究了气-液-液三相下油滴的流动形态,并对不同填料的流体力学性能进行了测定。实验结果表明,气相速度的增加可导致气含率、液含率的增加,从而提高分散相在填料萃取塔中的停留时间,在一定的速度范围内明显降低萃取的表观传质单元高度,极大地强化传质效果。通过与散装填料对比,发现规整填料更利于强化萃取效果,其液泛速度平均增加25%。     

Effect of system properties on the performance of Liquid—Liquid extraction columns—II: Oldshue—Rushton column

Mean drop size, fractional hold-up of dispersed phase and axial mixing characteristics have been determined in a 72 mm diameter mechanically agitated extraction column of Oldshue—Rushton type, using the two liquid—liquid mass transfer systems, toluene—acetone—water and MIBK-acetic acid—water. As for normal conditions of packed column operation described in Part I, solute presence and the direction of mass transfer has a significant effect on mean drop size, fractional hold-up and to a lesser extent, axial mixing in the dispersed phase. Probably the most dramatic effect however is the manner in which solute transfer affects dispersed phase behaviour. Highly coalescing conditions with transfer from the dispersed to the continuous phase can make the column practically unoperable. As for the packed column, axial mixing in the continuous phase is unaffected except in so far as solute presence and direction of mass transfer affect the hold-up of dispersed phase.