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…     

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。     

脉冲筛板萃取塔在湿法磷酸工艺中的试验研究

依据溶剂萃取湿法磷酸的物性和脉冲筛板萃取塔的特性,设计脉冲筛板萃取塔,并进行盐酸法制取湿法磷酸的试验,得到萃取、洗涤、反萃3个过程的操作条件.在脉冲筛板萃取塔中,在萃取时相比为3:1,反应级为2～3,洗涤时相比为6:1,反萃时相比为3:1的条件下,所得磷酸及各项杂质含量指标均达到或优于老式萃取设备.试验表明,在初步间歇性试验中,用脉冲筛板萃取塔萃取磷酸,萃取效率高,操作简单,为进一步开发和完善新设备提供了基础数据.     

搅拌筛板萃取塔液泛特性研究

为明确萃取塔对不同体系、不同操作条件下的性能,在内径为50 mm的三级搅拌筛板萃取塔中,针对7个不同物性特点的体系进行了液泛特性研究,液泛点采用观察法判断.实验结果表明,穿流式筛板的过孔阻力和过度搅拌是液泛产生的两个原因;萃取塔的两相总空塔流速与搅拌转速关系曲线将塔的操作区域分为搅拌不足液泛区、正常操作区、搅拌过度液泛...     

筛板塔萃取中影响萃余的因素探讨

简单介绍了筛板塔在过氧化氢生产过程中萃取的原理,着重讨论了萃余液中过氧化氢含量高的影响因素及优化操作方法。     

筛板萃取塔液滴行为及其影响因素

为研究筛板萃取塔中的液滴行为,采用实验和模拟相结合的方法对液滴通过筛板的形态和筛板对液滴的聚并-破碎特性进行研究,定义筛板聚并-破碎指数。结果表明,液滴在不同实验条件下以不同的方式通过筛孔,主要可分为直接通过筛孔、破碎后通过筛孔和在筛板上聚并后通过筛孔。体系界面张力较低时,筛板对液滴主要起破碎作用,筛板聚并-破碎指数随着孔径的增大而减小;体系界面张力较高时,筛板对液滴主要起聚并作用,筛板聚并-破碎指数随着孔径的增大而增大。同时,筛板聚并-破碎指数随着筛板浸润性变差而增大。基于实验数据提出估算筛板聚并-破碎指数的关联式,关联式平均偏差为0.114 4,偏差较小,表明关联式可用于评估筛板对液滴的聚并-破碎特性。     

多降液管筛板萃取塔内流动特性和塔效率的研究

选择正丁醇－丁二酸－水作为实验体系，以有机相为分散相，在φ１００ｍｍ的塔内系统地研究了单降液管、双降液管和三降液管三种塔板的两相流动特性和传质效率，并对其进行了比较。研究结果表明，在相同的操作条件下，多降液管大孔筛板塔比单降液管塔内的动态存留分数大，板下静液层高度小的特点，同时多降液管筛板塔比单降液管筛板塔具有更高的塔效率。     

我国新型垂直筛板塔的性能研究与进展状况

综述了我国对新型垂直筛板塔的流体力学性能与传质性能的研究情况及取得的最新进展。     

优选筛板孔径提高泡沫塔的干燥效果

基于泡沫干燥塔吸收氯气水份的原理，为了提高泡沫塔的干燥效果，在进行泡沫塔设计过程中，优选筛板孔尺寸，使之于接近最佳流速。     

往复振动筛板萃取塔萃取机理研究进展

介绍了往复振动筛板萃取塔（RPEC）流体力学性能和传质性能研究现状。     

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.     

液-液-固三相脉冲筛板塔萃取棉仁 1.塔安全操作范围的确定

确定了脉冲筛板塔在无实际萃取存在时甲醇 石油醚体系的安全操作曲线 ,认为比较安全和萃取效率较高的操作条件为持液量为 2 4 %。     

大孔径导向筛板流体力学性能研究

在长为500mm,宽为300mm冷模塔内,测定了φ9 mm大孔径导向筛板的流体力学性能参数.对实验数据进行了关联,得出计算塔板压降公式,可供大孔径导向筛板设计与研究使用.     

Axial mixing and mass transfer in a vibrating perforated plate extraction column

The axial mixing and countercurrent mass transfer characteristics of a 5 cm diameter extraction column agitated by vibrating perforated Teflon plates have been investigated. The dispersed phase was an organic liquid (usually kerosene) and the continuous phase was water. Axial mixing was measured in both phases using pulse tracer techniques; in the continuous phase the axial mixing was estimated to have a significant effect on mass transfer, but axial mixing in the dispersed phase had a negligible effect. Mass transfer was measured for several different solutes; n-butyric acid, benzoic acid and phenol. The overall heights of a transfer unit (cont. phase) were in the order of 10-20 cm for the organic-acids but higher for transfer of phenol from very dilute solutions. The characteristics of the vibrating plate column have been compared with those of other types of extractor and suggestions are made for further development.     

CFD and experimental studies of single phase axial dispersion coefficient in pulsed sieve plate column

This paper intends to study the single phase axial dispersion in pulsed sieve plate column using a combination of computational fluid dynamics (CFD) simulations and experimental measurements. Experiments and CFD simulations were conducted on 0.076 m diameter pilot scale column having standard geometry of 0.05 m plate spacing, 0.003 m hole diameter and 0.21 fractional free area. The effect of density of tracer solution and radial probe position on axial dispersion coefficient has been studied to ensure precision of the experimental measurement method. The effect of pulse velocity from 0.01 to 0.025 m/s and superficial velocity of water from 0.01 to 0.03 m/s has been studied. Simulations were carried out using commercial CFD software, FLUENT 6.2.16, with standard k–? model for turbulence. An unsteady state tracer injection technique was used for axial dispersion measurement. The range of velocity ratio (ψ = Re_o/Re_n) employed in this work was 1–4 which is very low. Therefore the effect of superficial velocity, V_c was found to be greater than pulse velocity. These results were critically compared with published data and it has been found that single phase axial dispersion coefficient is directly proportional to effective velocity (Af + 0.5 V_c). The presented CFD predictions and validation with experimental data will provide useful basis for further work on single phase axial dispersion with various geometrical parameters and understanding the two phase flow patterns in pulsed sieve plate column.     

湿法磷酸净化中往复式振动筛板塔的应用研究

研究在往复式振动筛板萃取塔中用有机溶剂萃取湿法磷酸的性能,考察振动筛板萃取塔结构参数和操作条件对磷酸萃取率的影响。结果表明:筛板开孔率53%,筛板间距7cm,振动频率150r/min时,萃取率可达84%;结合洗涤和反萃可以得到合格的工业级磷酸。     

多级鼓泡塔内液体速度分布的实验研究

液体循环流动是多级鼓泡塔重要流体力学特征之一,文中在内径为282 mm,高2000 mm的鼓泡塔内,采用不同类型的筛板将普通鼓泡塔分割成双级气液鼓泡塔.采用Pavlov管测液速的方法考察了不同筛板、不同表观气速下该鼓泡塔中上下二侧的液体速度分布.根据实验结果得出了液体速度在塔中心处最大,且与表观气速有关,随着表观气速的...     

往复振动筛板塔对低界面张力体系萃取过程的强化

对低界面张力体系正丁醇-丁二酸-水在往复振动筛板塔中的萃取性能进行研究,体系中水为萃取剂,萃取正丁醇中的丁二酸。实验考察了两相流速、相比、传质方向和筛板振动速率对流体力学性能和传质性能的影响,并且与相同操作条件下固定筛板萃取塔的性能作对比。结果表明,筛板振动速率不高于3.5 cm/s的情况下体系没有发生乳化现象,相比增大到2.8时接近液泛点,实验稳定性较差。流速和相比增大能够获得更好的液滴分布和更大的体积传质系数,但增大的幅度要综合考虑设备的最大通量和两相在塔内的停留时间。分散相到连续相的传质方向传质相界面积大,更有利于提高传质效率。相同操作条件下,连续相中的轴向混合远大于分散相的轴向混合。与固定筛板塔的萃取性能相比,振动筛板改善液滴分布、增大处理能力和强化传质的作用都很明显。     

A study on hydrodynamic characteristics in a Φ38 pulsed extraction column by four‐sensor optical fiber probe

Accurate prediction of dispersed phase droplet behavior is crucial to the design and scaling‐up of an extraction column. In this article, the dispersed droplet velocity algorithm and the diameter algorithm in a liquid–liquid two‐phase flow have been developed based on the bubble velocity model in gas–liquid two‐phase flow of Lucas [Measurement Science & Technology. 749, 758(2005)] and Shen [International Journal of Multiphase Flow. 593, 617(2005)]. Hydrodynamic characteristics, including droplet diameter, holdup and droplet velocity, were measured using a self‐made four‐sensor optical fiber probe in a 38 mm‐diameter pulsed sieve‐plate extraction column. Water and kerosene were used as continuous and dispersed phases, respectively. The influences of the pulsed intensity, the continuous and dispersed phase superficial velocities on the hydrodynamic characteristics were investigated. The experimental results show that it is reliable to use a four‐sensor optical probe to measure the hydrodynamic characteristics of a pulsed extraction column. © 2016 American Institute of Chemical Engineers AIChE J, 63: 801–811, 2017