折流板脉冲萃取柱水力学性能研究

以体积分数30%三烷基氧膦(TRPO)煤油溶液和1 mol/L硝酸溶液为体系,在100 mm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(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。实验研究表明:液泛通量随着脉冲强度的减小而增大,与流比和板间距无关,并给出其关联式;操作参数和柱结构参数对液泛存留分数的影响均可忽略;正常操作时分散相存留分数与连续相的流速、流比成正比关系,而与脉冲频率无关,并随板间距和脉冲振幅的增大而增大,并给出了分散相存留分数的经验关联式。     

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.     

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。     

板波纹填料用于低界面张力萃取体系的操作特性研究

在内径为100 mm的玻璃萃取塔中,以具有较低界面张力的30%煤油(TBP)-醋酸-水为萃取体系,系统研究了板波纹规整填料的流体力学性能和传质性能。结果表明,随两相流量增加,存留分数皆增加;随流速比减小,液泛通量增大;理论级当量高度随连续相流速变化不大,但随分散相流速增加而降低。板波纹填料具有较高的液泛通量和传质效率,在实验范围内,液泛通量高达98～153 m3/(m2·h),理论级当量高度在0. 68～1. 05 m之间,对低界面张力萃取体系具有较好的效果。     

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.     

同向环流萃取装置的存留分数和液泛研究

在直径0.1 m,孔径3 mm的一种同向环流萃取装置中,针对煤油-水和30%磷酸三丁酯(TBP)/煤油-水两种体系,采用体积置换法和观察法分别对分散相存留分数和液泛速度进行了研究。实验结果表明了分散相存留分数随两相表观速度的增大而增大,且分散相速度的影响大于连续相速度。得出了在这两种体系下,连续相的流量范围分别为0～29和0～34 L×h~(-1),分散相的流量范围分别为10～166和16～125 L×h~(-1)。同时,采用无因次数群法拟合出存留分数和液泛速度的经验关联式。两个经验关联式都能在实验范围内很好地对存留分数和液泛速度进行预测,为工业过程放大和工程设计提供了重要的计算依据。     

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。     

气-液并流通过堆叠筛板填料的脉冲流特性

通过高速摄像机和压力传感器测量,对脉冲流的产生机理、筛板数的影响、液相脉冲传播速度及频率进行了系统的研究。实验发现：脉冲流是重力和气流曳力作用下,孔口液相波动在向下传播过程中被叠加放大的动力学过程,且与气、液流量及筛板数密切相关;一定气量下,脉冲流的产生需要有一个最小（临界）液相流量,且增加液量可促进局部脉冲的产生,并使液相脉冲传播速度与频率均增大;临界液量之上,增大气量,气相的扰动作用增强,局部脉冲越容易产生,从而导致脉冲传播速度与频率均增大;进一步增大气量,液相脉冲会被逐渐分散,导致脉冲传播速度与脉冲频率均减小。增加筛板数,有利于增强脉冲流强度,从而导致脉冲流范围变宽,当筛板数少于三块时不会出现脉冲流。最后,基于实验结果分析,提出了脉冲传播速度及频率的预测关联式。     

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.     

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.     

A physical model for the prediction of liquid hold-up in two-phase countercurrent columns

This contribution presents the determination of liquid hold-up in gas/liquid two-phase countercurrent columns filled with random or structured packings. The equations resulting from the established physical relationships are varified against the values for liquid hold-up determined experimentally on 56 different column packings and 16 gas/liquid systems. The experimental and calculated results agree well, with only slight deviations. This also applies to the range between the loading and flooding points for two-phase countercurrent flow.     

组合导向浮阀塔板的CFD模拟及反向流分析

精馏塔板上的气液两相流动对传质效率有重要影响。根据实验数据拟合得到平均气含率关联式,将其加入动量源项,采用Fluent软件对1.2 m直径的组合导向浮阀塔板上的气液两相流动进行CFD模拟,考察了塔板上的气液两相流动状况。清液层高度的模拟结果与实验数据关联式相吻合,验证了模拟的正确性。对塔板上液相的非理想流动进行了分析,通过对反向流进行量化和统计计算出反向流体积分数(即反向流体积占塔板总体积的百分比)。3块不同浮阀排布塔板的反向流体积分数时均值的计算结果表明,梯形浮阀和矩形浮阀的排布方式对反向流影响很大,通过合理排布能够使工业塔板的反向流体积分数时均值从22.0%下降到19.4%,降幅达到11.8%。本研究结果可望对塔板的设计和优化提供指导。     

A VERSATILE CORRELATION OF LIQUID HOLD-UP IN TWO-PHASE COUNTER-CURRENT TRICKLE BED COLUMN

A new definition of the flooding point in a two-phase counter-current trickle bed column has been proposed. Based on this point a versatile correlation of liquid hold-up has been formulated. The coefficients of this correlation are invariant to the change of physical properties of liquid, type and size of the packing forming the bed and gas velocity. This conclusion has been reached from the analysis of experiments with four different liquids irrigating the bed and three types of packing of various size. The versatile correlation can be used also re-currently to calculate flooding hold-up and flooding liquid rate from two known values of liquid hold-up for a given gas rate.     

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.     

STUDIES ON FLOODING POINT AND HOLD-UP IN A SOLVENT EXTRACTION COLUMN WITH RECIPROCATING SIEVE PLATES

The flooding point and hold-up of the dispersed phase in an extraction column with reciprocating-sieve plates of 32 mm inside diameter and 1960 mm effective column height have been investigated under thefollowing conditions:Percent perforation of the plates 40%,53.5% and 63.7%,diameters of perforatedholes 7.8,9.0 and 9.8 mm,and distances between plates 20 and 40 mm respectively.Experiments werecarried out with three different liquid-liquid systems covering a rather wide range of physical properties.The relative velocity of the two phases passing through the perforations of the plates is consideredin the present work to be related to the work done by the oscillating plates in the column on unit massof liquid in unit time.Therefore the flooding velocity and hold-up in extraction column with reci-procating sieve plates should be related to A~2F~3 instead of AF as reported before.Equations weredeveloped to correlate the experimental data of flooding point and hold-up respectively.     

导流管型鼓泡塔中带泡沫非牛顿型液体的气含率

在塔径０１１２ｍ的三组不同直径导流管装置中，采用液体溢出法测定了带泡沫的非牛顿型液体的气含率分析了表观气速Ｖｇ０和管径比（ＤＲ／Ｄ０）对气含率的影响     

Transition to pulsing flow,holdup and pressure drop in packed columns with cocurrent gas-liquid downflow

Trickle beds of 1 meter in length and resp. 5, 10 and 20 cm in diameter were operated in the so-called pulsing flow regime. The packing was 2.5 resp. 4 mm Raschig rings. Air was taken as the gas phase. Several liquids were used.In this contribution we describe the transition from gas-continuous to pulsing flow, the liquid holdup and the pressure drop over the column. The transition can be described by an effective Froude-number. Correlations are set up for the transition point as well as for the hold-up.Pressure drop is shown to be linearly dependent upon the pulse frequency. In a separate series of experiments the transition to pulsing flow was measured in a 5 mm capillary tube, used as a wetted wall column. It became clear, that the onset of pulsing flow in such a capillary is not determined by the same parameter as the onset of pulsing flow in a packed column.