共查询到18条相似文献,搜索用时 687 毫秒
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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.据此,本文在气-液-液萃取条件下对不同填料的传质性能进行了测定.实验表明,通入气相后分散相液滴呈现稳定的“油包气”空心状态,这种结构大大降低了分散相液滴的传质层厚度,减小了传质距离,极大地强化传质效率.在适宜气速下,气-液-液萃取效率较传统萃取效率提高20%~40%.通过与散装填料对比,发现规整填料更利于强化萃取效果,传质效率提高约50%. 相似文献
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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。 相似文献
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搅拌槽中液-液-固三相传质的实验研究 总被引:2,自引:0,他引:2
选择欧洲化学工程师协会(EFCE)推荐的典型液-液萃取体系正丁醇-丁二酸-水,加入不同粒径的玻璃珠构成液-液-固三相传质,以去离子水为连续相,正丁醇为分散相,溶质丁二酸从分散相向连续相传质. 利用电导率法测定液-液相传质系数,并考察了搅拌转速、固体质量百分含量、不同桨型(标准Rushton桨、上推式和下推式45°六折叶涡轮桨)、桨中心平面距槽底距离以及固体颗粒粒径对相间传质的影响. 结果表明,在高转速时,惰性固体粒子的存在强化液-液体系的传质. 随着惰性固体含量增大,液-液-固三相传质有一极大值. 粒径大于100 μm 的固体粒子对液-液体系传质系数影响很小. 三种桨中Rushton桨的对流传质效果最好. 相似文献
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以CO2-H2O为模型体系,实验考察了当量直径为667 μm的单通道和16个并行通道内的气-液传质行为.实验发现,液体表观速度增加,单通道内液侧体积传质系数明显提高;同一液体表观速度下,液侧体积传质系数随气体表观速度增加而增加;在实验数据基础上关联了液侧体积传质系数与气-液两相流参数间的关系.微通道内的液侧体积传质系数较常规尺度气-液接触设备至少高1~2个数量级.并讨论了并行微通道内气-液两相流分配特性对整体传质性能的影响,表明合理设计气、液流动分布结构,可保证微通道内优异的传质特性. 相似文献
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使用双T型微通道,以体积分数为30%的磷酸三丁酯(TBP)的环己烷溶液-乙酸水溶液为萃取体系,研究了不同油水两相流量比及油水两相总流量条件下,气相的引入及气相流量分率α对流型及传质的影响,并获得总体积传质系数kLa与油水两相流量比q、气相雷诺数Reg、液相平均雷诺数ReM的关系式。研究结果表明,第1个T型接口处气相的引入所带来的气相剪切作用能促进第2个T型接口处分散相液滴的形成,可使液-液并行流转化为气-液-液三相弹状流;同时,由于气-液-液弹状流具有较高的相接触面积及内循环作用,传质系数kLa得到显著提高。 相似文献
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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… 相似文献
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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. 相似文献
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Fractional dispersed phase hold-up and dispersed side mass transfer coefficients for amyloglucosidase were measured in a 56 mm i.d. packed extraction column using a sodium sulphate-polyethylene glycol 4000 system. Raschig rings (3 to 13.3 mm), Berl saddles (12 mm), Pall rings (12.6 mm), glass spheres (5.2 mm) and structured wire gauze were used as packings. The effect of packing size was investigated in the case of ceramic Raschig rings. The effect of phase composition of the aqueous phase system also was studied. Correlations have been developed for fractional dispersed phase hold-up and volumetric mass transfer coefficient with packing voidage, dry surface area of packings, superficial dispersed phase velocity and the liquid phase physical properties. 相似文献
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Mostafa Keshavarz Moraveji Elmira MohsenzadehMona Ebrahimi Fakhari Reza Davarnejad 《Chemical Engineering Research and Design》2012
The effects of three types of surface active agents (containing SDS, HCTBr and Tween 40) with various concentrations (0–5 ppm) on the hydrodynamic and oxygen mass transfer characteristics in a split-cylinder airlift bioreactor with and without packing were investigated. It was observed that in the surfactant solutions, surface tension of the liquid decreased and smaller bubbles were produced in comparison with pure water. So, surfactants presence strongly enhanced mixing time and gas hold-up although oxygen mass transfer coefficient and the liquid circulation velocity reduced. Furthermore, the packing installation enhanced the overall gas–liquid volumetric mass transfer coefficient by increasing flow turbulency and Reynolds number compared to an unpacked column. The packing increased gas hold-up and decreased bubbles size and liquid circulation velocity. 相似文献
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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. 相似文献
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In this work mass transfer phenomenon of liquid–liquid extraction process with structured packing was modeled. The model was validated by means of fluid-dynamic and mass transfer tests, for mass transfer from the continuous to the disperse phase with n-butanol/succinic acid/water system. The effect on hold-up and outlet concentration profiles of each phase were evaluated when the incoming flow of the disperse phase was disturbed between 10 and 30%. Surface velocity of each phase and hold-up were considered in the model as functions of time. The continuous phase dispersion phenomenon was also taken into account. Deviation percentage average of 8% between the experimental data and the simulation results of the disperse phase composition in steady state were obtained. For the dynamic model the inclusion of the dispersion effect of the disperse phase and more experimental tests are recommended. 相似文献