ø50折流板脉冲萃取柱水力学性能

以30%TRPO煤油溶液和1 mol·L-1硝酸溶液为体系,在ø50折流板脉冲萃取柱中考察了折流板脉冲萃取柱的操作参数(脉冲振幅、脉冲频率、流速和流比)和结构参数(开孔率和板间距)对其水力学性能(液泛通量、液泛存留分数和正常操作时分散相存留分数)的影响.结果表明在乳化操作区,液泛通量随着开孔率增加、脉冲强度和流比的减小而增大,与板间距无关;根据液泛存留分数的结果,给出了最优开孔率为23%;此时正常操作时分散相存留分数与连续相的流速、流比和脉冲振幅呈正比,而与脉冲频率无关,浸润性的影响造成了板间距对以硝酸溶液和30%TRPO煤油溶液为连续相时的分散相存留分数影响规律不同.     

φ50折流板脉冲萃取柱水力学性能

以30％TRPO煤油溶液和1 mol·L^-1硝酸溶液为体系,在φ50折流板脉冲萃取柱中考察了折流板脉冲萃取柱的操作参数（脉冲振幅、脉冲频率、流速和流比）和结构参数（开孔率和板间距）对其水力学性能（液泛通量、液泛存留分数和正常操作时分散相存留分数）的影响.结果表明：在乳化操作区,液泛通量随着开孔率增加、脉冲强度和流比的减小而增大,与板间距无关;根据液泛存留分数的结果,给出了最优开孔率为23％;此时正常操作时分散相存留分数与连续相的流速、流比和脉冲振幅呈正比,而与脉冲频率无关,浸润性的影响造成了板间距对以硝酸溶液和30%TRPO煤油溶液为连续相时的分散相存留分数影响规律不同.     

梯形波脉冲筛板萃取柱流体力学性能

本文以HNO_3-30％TBP(KO)为实验体系,进行了梯形波脉冲筛板柱流体力学实验。实验中测量了不同脉冲振幅、频率、流比及两相流量时分散相(水相)的存留分数。测量了不同振幅、频率、流比时的液泛通量。初步分析了脉冲上、下冲程的平均速度对萃取柱流体力学行为的影响。分析了脉冲气源压力对存留分数和液泛通量的影响。     

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.     

脉冲筛板萃取塔CFD-PBM模型研究

脉冲筛板萃取塔是核工业等领域中最常用的萃取设备之一，为深入了解脉冲筛板萃取塔中两相流行为规律，使用CFD-PBM模型对脉冲筛板萃取塔中由有机相(30%TBP-正十二烷)、水相(HNO₃水溶液)组成的体系进行两相流过程模拟分析，模拟结果与实验数据吻合较好，分散相存留分数和Sauter平均液滴直径的相对偏差仅为8.28%和5.54%；随脉冲速度增加，Sauter平均液滴直径减小，液滴直径分布更均匀，分散相存留分数增加，特性速度减小；两相表观速度对液滴直径影响较小，分散相表观流速增加有利于提高分散相存留分数，而连续相表观流速影响不大；发生液泛时分散相液泛表观速度随连续相液泛表观速度增大而减小，随脉冲速度增加液泛通量先增后减，存在极值。     

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。     

折流板脉冲萃取柱的结构参数对孔收缩因子的影响

利用吹气法研究了折流板脉冲萃取柱的结构参数（板间距、柱径和板开孔率）对预测摩擦压降模型中孔收缩因子Co的影响。研究结果表明：当实验体系为硝酸溶液时,Co值随柱径、板间距和板开孔率的增加而减小;当实验体系为30％三烷基氧膦-煤油溶液且柱径不大于0．05m时,Co值与脉冲雷诺数ReAf和板开孔率有关,与板间距无关,而当柱径为0．1m时,Co值与板间距和板开孔率有关,而与操作参数ReAf无关。     

50mm折流板脉冲萃取柱吹气法测量存留分数

在柱径为50mm的折流板脉冲萃取柱中,首先利用吹气法研究了硝酸水溶液和30%TRPO煤油水溶液体系的单相流时均摩擦压降Δpf特性.实验结果表明当A′ω≠0,且uc=0时,Δpf可以忽略;而当A′ω=0时,Δpf与uc满足Noh模型的线性关系.在Noh模型的基础上,给出了计算A′ω≠0时单相流时均摩擦压降的模型,实验结果与模型预测相一致.在单相流摩擦压降的基础上,又研究了连续相分别为硝酸溶液和30%TRPO煤油溶液体系的两相流时均摩擦压降Δpf特征.实验结果表明:两相流时均摩擦压降Δpf可用于计算分散相存留分数,其近似由连续相所对应的Noh单相流模型求得,并可用于折流板脉冲萃取柱分散相存留分数的确定.     

φ50 mm折流板脉冲萃取柱吹气法测量存留分数

在柱径为50 mm的折流板脉冲萃取柱中,首先利用吹气法研究了硝酸水溶液和30％TRPO-煤油水溶液体系的单相流时均摩擦压降Δp_f特性.实验结果表明当A′ω≠0,且u_c＝0时,Δp_f可以忽略;而当Aω＝0时,Δp_f与u_c满足Noh模型的线性关系.在Noh模型的基础上,给出了计算Aω≠0时单相流时均摩擦压降的模型,实验结果与模型预测相一致.在单相流摩擦压降的基础上,又研究了连续相分别为硝酸溶液和30％TRPO-煤油溶液体系的两相流时均摩擦压降Δp_f特征.实验结果表明：两相流时均摩擦压降Δp_f可用于计算分散相存留分数,其近似由连续相所对应的Noh单相流模型求得,并可用于折流板脉冲萃取柱分散相存留分数的确定.     

Determination of holdup by air purge in φ50 mm discs and doughnuts pulsed extraction column

在柱径为50 mm的折流板脉冲萃取柱中,首先利用吹气法研究了硝酸水溶液和30％TRPO-煤油水溶液体系的单相流时均摩擦压降Δp_f特性.实验结果表明当A′ω≠0,且u_c＝0时,Δp_f可以忽略;而当Aω＝0时,Δp_f与u_c满足Noh模型的线性关系.在Noh模型的基础上,给出了计算Aω≠0时单相流时均摩擦压降的模型,实验结果与模型预测相一致.在单相流摩擦压降的基础上,又研究了连续相分别为硝酸溶液和30％TRPO-煤油溶液体系的两相流时均摩擦压降Δp_f特征.实验结果表明：两相流时均摩擦压降Δp_f可用于计算分散相存留分数,其近似由连续相所对应的Noh单相流模型求得,并可用于折流板脉冲萃取柱分散相存留分数的确定.     

Axial dispersion,holdup and flooding characteristics in pulsed extraction columns

The effects of interactions between the perforated and baffle plates, of pulse amplitude and of pulse frequency on axial dispersion in the continuous phase, on the dispersed phase holdup and on the flooding condition have been determined for a 10.2 cm 1D pulsed extraction column. The axial dispersion coefficient increased with both the pulse amplitude and the frequency, but it decreased with the decrease in baffle spacing in the unit module. Dispersed phase holdup increased with the number of perforated plates in the unit module at the lower pulsation velocities and increased with the pulse velocity. The baffle plate reduced the total throughputs, but baffle spacing did not have any significant effect on the total throughput.     

Dependence of Holdup on Height in a Pulsed Plate Column Based on Binary Liquid‐Liquid Equilibrium Data

Holdup has been measured at various frequencies, amplitudes, continuous and dispersed phase flow rates for binary systems in a pulsed plate column capable of providing samples at various heights. The binary systems have been so selected as to cover a wide spectrum of interfacial tensions. Dispersed phase holdup was found to increase with height in a logarithmic fashion at conditions away from the flooding point and to become almost invariant with height near flooding conditions. The interfacial tension of the binary system has a large effect on the dispersed phase holdup. In systems having low interfacial tension, a small increase in any of the parameters can increase the holdup significantly and lead to flooding. In systems having high interfacial tension, on the other hand, variations in system parameters do not affect system performance significantly.     

Comparison of normal phase operation and phase reversal studies in a pulsed sieve plate extraction column

The hydrodynamic characteristics of a pulsed sieve plate extraction column (PSPEC) was studied experimentally using two different liquid phase systems, namely water/kerosene and 30%TBP (tributyl phosphate) in NPH (normal paraffin hydrocarbon)/0.3 M HNO₃. The aqueous phase as the dispersed phase and the organic phase as the continuous phase (phase reversal) and vice versa (normal phase operation) studies in a pulsed sieve plate extraction column 0.076 m in diameter and 1 m height are presented in this paper. The hydrodynamic properties like drop size and holdup are characterized as a function of various operating parameters namely pulse velocity, dispersed phase and continuous phase velocity and duty cycle of pulsing. Flooding in the column was also investigated for the changes involving flow ratio of continuous phase to that of the dispersed phase for both insufficient and excessive pulsing. It has been observed that phase reversal mode of operation is not efficient as compared to normal phase operation for the PSPEC.     

Droplet velocity,size, and local holdup measurements in an extraction column by tri‐sensor optical probe

The tri‐sensor optical probe was applied to study the hydrodynamic characteristic in a pulsed sieve plate extraction column. Two immiscible liquids consisting of the dispersed phase (kerosene) and continuous phase (water) were introduced in countercurrent operation. Local parameters such as droplet velocity, drop size, and holdup of the dispersed phase were obtained. It was found that the tri‐sensor optical probe could be used as an efficient and convenient technique for measuring local hydrodynamic parameters inside the pulsed sieve plate extraction column. Furthermore, the results indicated that pulsation intensity imposed more influence on these hydrodynamic parameters than two‐phase superficial flow rates in the investigated ranges. Experimental results were found to be in good agreement with the empirical correlations reported in literature. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3958–3963, 2015     

Dispersed Phase Holdup in a Tall and Low Plate Free Area Liquid Pulsed Sieve-Plate Extraction Column

Dispersed phase holdup is studied in a tall and low plate free area pulsed sieve-plate extraction column. The 5.0 cm internal diameter column consists of 80 number of plates with percent free area of 13.5. The effects of pulse velocity (product of amplitude and frequency), superficial phase velocities, and solute addition are studied for five liquid-liquid systems with a wide range of interfacial tensions. The experimental holdup data is tested against the most widely recommended correlations and a new correlation has been developed that best fits the data.     

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。     

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.     

Dispersed phase holdup and slip velocity of phases in a pulsed packed column in conditions with and without mass transfer

Dispersed phase holdup and slip velocity of phases were measured in a pilot plant pulsed packed column with a diameter of 76.2 mm for two different chemical systems in conditions with and without mass transfer. The effects of pulsation intensity, dispersed and continuous phases flow rates, interfacial tension and solute concentration on dispersed phase holdup and slip velocity of phases were investigated. A new empirical correlation in terms of the above‐mentioned parameters developed from the measurements is given for the prediction of slip velocity. The dispersed phase holdup was calculated by means of this correlation and very good agreement between calculated and experimental values was obtained.