填料塔分离乙醇-异丁醇的条件研究及优化

本文用填料塔分离乙醇-异丁醇的条件进行了初探,对乙醇-异丁醇溶液乙醇的提纯条件(如:塔釜加热温度,塔釜液乙醇的浓度,回流比等)进行了实验研究,得到一些有效的数据关系,实现了乙醇的提纯和异丁醇浓度的提高,结果较满意,为乙醇与异丁醇的回收提供了有用的操作参数。     

常压下正丁醇-异丁醇-醋酸丁酯-水体系汽液平衡测定与关联

文章采用单级循环汽液平衡釜测定了常压条件下正丁醇-异丁醇-醋酸丁酯-水混合液中的二元体系的汽液平衡数据,运用试差法关联Wilson方程中六对二元体系的模型参数,并计算出相应的汽相组成;测定了常压条件下正丁醇-异丁醇-醋酸丁酯-水四元体系的汽液平衡数据,并由六对二元体系模型参数关联出四元体系的汽液平衡数据。比较实验和计算值,结果表明:实验值与计算值的相对偏差均≤5%,说明实验值与计算值一致。文章研究结果为正丁醇、异丁醇、醋酸丁酯及水混合液的分离提供了一定基础数据。     

由液液平衡数据预测部分互溶物系的汽液平衡

本文用浊点滴定法测定了部分互溶二元体系正丁醇-水和异丁醇-水在恒沸温变以下的液液平衡数据,由该实验数据求取了NRTL常数,用求得的二元常数预测了正丁醇-异丁醇-水三元体系的汽液平衡数据。计算值与文献实验值符合良好,可由沸点以下的二元液液平衡数据预测部分互溶物系的汽液平衡关系。     

水-异丙醚-苯酚和水-异丁醇-苯酚体系的液液平衡研究

水-异丙醚-苯酚体系的研究在工业上和环境保护上具有重要意义,但至今未见到液液平衡(LLE)数据的报导今报导了这一系统在两个工作温度的LLE数据.为了寻找萃取剂异丙醚的替代物,我们同时进行了水-异丁醇-苯酚体系的液液平衡研究. 在常压下使用GC-14B气相色谱仪,测定了319 K和329 K时水-异丙醚-苯酚体系的液液平衡(LLE)数据以及水-异丁醇-苯酚体系在319 K和333 K时的LLE数据.用内标法测定了这些体系中除水以外的各组分浓度.在水-异丙醚-苯酚体系中,异丙醚测量的根均方误差为1.4%;苯酚测量的根均方误差为4.6%.在水-异丁醇-苯酚体系中,异丁醇测量的根均方误差为3.1%:苯酚测量的根均方误差为4.6%. 文中给出了上述四个等温截面的LLE数据,同时也给出了相应示意图.2003年我们用工作曲线法(外标法)给出了水-异丙醚-苯酚在319K的等温截面图.两者比较,总体上是类似的,但内标法结果更可靠.这次的研究,还纠正了当时的一个错误估计.对于水-异丁醇-苯酚体系的液液平衡研究表明,异丁醇也是从废水中萃取苯酚的良好萃取剂.但是异丁醇的再生及其循环利用并不如异丙醚那样容易.     

探讨UNIFAC法推算正、异丁醇精制系统中若干体系的汽液平衡——增补a_(CCOH,CHO)和a_(CHO,CCOH)基团相互作用参数

本文通过异丁醇-异丁醛体系汽液平衡的文献数据,增补了用于UNIFAC法的一对a_（CCOH,CHO）和a_（CHO,CCOH）基团相互作用参数。用UNIFAC法推算有关正、异丁醇精制系统的各类相平衡数据,其计算精确度接近或达到NRTL等方程的关联结果。由于此法基于基团性质加和性的假定,因此在具体应用时必须慎重地选择参数值,并用实验数据进行检验。     

101.3kPa下异丙醇-异丁醇-正丁醇汽液平衡的测定与关联

用改进的Rose釜测定了101.3 kPa下异丙醇-异丁醇、异丙醇-正丁醇、异丁醇-正丁醇3个二元体系及异丙醇-异丁醇-正丁醇1个三元体系的汽液平衡数据。3组两元汽液平衡数据均通过了Herington热力学一致性检验,三元汽液平衡数据也通过了McDermett-Ellis热力学一致性检验。分别用Wilson、NRTL和UNIQUAC方程对二元汽液平衡数据进行了关联,得到了相应的模型参数及关联偏差。对于3个二元体系而言,Wilson和UNIQUAC模型方程比NRTL模型方程的关联效果好。最后运用关联得到的Wilson二元交互作用参数预测了三元体系的汽液平衡数据,平衡温度的平均绝对偏差为0.52℃,异丙醇的汽相摩尔组成平均绝对偏差为0.0057,异丁醇的汽相摩尔组成平均绝对偏差为0.0048,实验值与预测值基本吻合。     

在0.7MPa压力下甲醇-异丁醇,乙醇-异丁醇体系气液相平衡

本研究采用改进的中压流动法不锈钢装置测定了甲醇-异丁醇,乙醇-异丁醇体系在0.7MPa下的气液平衡组成。并对测定数据应用PR状态方程进行了关联处理,结果较好。     

基于剩余曲线的三元物系分离研究

通过实验绘制了异丁醇-水-苯三元物系的剩余曲线,利用流程模拟软件绘制了异丁醇-水-甲醇和二氯甲烷-水-甲醇两个三元物系的剩余曲线,基于精馏剩余曲线研究了异丁醇-水-甲醇和二氯甲烷-水-甲醇等物系的分离.     

发酵酒精中微量杂质的三元减压汽液平衡数据的测定和关联

<正>1 引言 发酵酒精中以甲醇、正丙醇、异丁醇为代表的杂醇含量是酒精质量的重要标志,为有效地去除这些杂质,以得到高纯食用酒精.本文应用目前国内开发和设计的较新颖的节能型酒精蒸馏流程——差压精馏流程,测定了减压汽液平衡数据,并进行了基础研究. 有关甲醇-乙醇-水、正丙醇-乙醇-水、异丁醇-乙醇-水的三元汽液平衡关系文献早有报道’‘’,他们测定了常压下有大量水时各醇类对乙醇的相对挥发度.本文结合实际生产情况,测定减压下低浓度甲醇、正丙醇、异丁醇和全浓度范围的乙醇-水的3组三元汽液平衡数据,经热力学关联和计算,以期获得Wilson、NRTL、UNIQUAC交互作用参数值.2 实验2.1 试剂 甲醇、乙醇、正丙醇、异丁醇均为分析纯试剂,水为二次蒸馏水.2.2 实验装置’“ 采用改进的汽液双循环型Rose平衡釜及自制的二级真空稳压系统,其精度为0.skPa,测温用1/10分度的实验室H级标准水银温度计,并考虑了露点校正”‘.2·3 组成分析 用配有C-R3A色谱数据处理机的GC-gA岛津气相色谱仪分析汽、液相组成,色谱柱为装有天津试剂二厂生产的GDX-102担体的玻璃柱.分别以氢焰和热导为检测手段,用修正百分率法处理数据.3 数据处理和实验结果3.二 热力学一致性校验 为证实实验装置的可靠性,首先对常压下乙醇-水和53.32kPa     

异丁醇脱水制备异丁烯反应热力学

异丁醇脱水制备异丁烯是又一条增产高纯异丁烯的可行性技术路线,文章采用平衡常数法计算异丁醇脱水制备异丁烯反应过程的反应热力学数据,如标准摩尔焓变Δ_rH~■_m、标准摩尔吉布斯自由能变Δ_rG~■_m和标准平衡常数K~■_P。采用吉布斯自由能最小化法,系统探讨了反应温度、压力、稀释剂对异丁醇脱水平衡转化率和异丁烯平衡产率的影响规律。热力学平衡计算结果说明:温度高于150℃时异丁醇脱水反应平衡转化率高于99.5%,温度和压力变化对异丁烯平衡产率的影响较大,异丁醇原料含水量对异丁烯平衡产率有促进作用。以热力学角度而言,开发异丁醇脱水制备高纯异丁烯工业化技术,无需对异丁醇原料进行脱水处理,原料异丁醇中添加适量的水有利于提高异丁烯产率。     

A theoretical study of mass transfer with chemical reaction in drops

A model has been developed for the preparation of mass transfer by forced convection inside drops for mass transfer with and without simultaneous first-order chemical reaction. Solutions of the forced convection equation have been obtained using finite difference methods for Reynolds number and viscosity ratio ranges of 0 ≤ Re ≤ 90 and 0 ≤ μ₁/μ_o ≤ ∞, respectively. The effect of circulation rate inside the drop on the mass transfer rate has also been studied. The model is believed to be generally applicable as evidenced by a comparison with existing analytical models. Thus the results for physical mass transfer approached the Kronig and Brink solution when the viscosity ratio tended towards zero in the Stokes' flow regime. However, as the viscosity ratio increased, the results approached the Newman solution. The model also agreed with those of Johns and Beckmann for physical mass transfer. Similarly, the results for mass transfer with first-order chemical reaction agreed with Dankwerts' generalization of the Kronig and Brink and the Newman models.     

Transient rise velocity and mass transfer of a single drop with interfacial instabilities - experimental investigations

An experimental study of transient drop rise velocities and mass transfer rates was carried out in the system toluene/acetone/water which is known to show interfacial instabilities. The rise velocity of toluene drops was studied without added solute (acetone) in the diameter range 1-3 mm and with added solute for 2 mm drops. The initial concentration of the transferred solute was varied from 0 to 30 g/L. The transient drop rise velocities were used to quantify the Marangoni effect since the drag coefficient depends on the strength of the Marangoni convection patterns caused by interfacial tension gradients. In addition, mass transfer measurements were carried out in order to determine the modification of the mass transfer rate due to Marangoni convection. Velocity and mass transfer measurements were then correlated via the contact time. Results reveal the existence of a range in which a critical value for the solute concentration can be defined for Marangoni convection.     

Extraction of rare earth metals with a multistage mixer-settler extraction column

Extraction behavior of rare earth metals within a mixer-settler extraction column has been analyzed with the stage efficiency calculated from mass transfer coefficients and interfacial area. The mass transfer coefficient within the dispersed drops is determined from a rigid sphere model by taking into account the residence time distribution of drops, and the coefficient around the drops is calculated by Ranz-Marshall's correlation with the terminal settling velocity of a rigid sphere. The interfacial area of dispersed drops is calculated by the use of correlations for the drop diameter and the holdup of dispersed phase in the mixer-settler extraction column. The calculated results for the separation of samarium and gadolinium with a five-stage mixer-settler extraction column are compared with the experimental results at various agitation speeds and flow ratios between two phases. The extraction behavior in the multistage column is explained by a model based on the hydrodynamics and the mass transfer within the mixer. Effects of the pH value in aqueous phase, the extractant concentration in organic phase and the number of stages on the extraction behavior in the mixer-settler column are also shown.     

Modelling mass transfer coefficient for liquid-liquid extraction with the interface adsorption of hydroxyl ions

A combined model was used for prediction of overall mass transfer coefficient of drops in the liquid-liquid extraction process, prone to the deleterious effect of adsorbed hydroxyl ions onto the interface. The importance is due to the use of different pH waters as aqueous phase. The work is based on single drop experiments with a chemical system of toluene-acetone-water where the pH of the continuous aqueous phase was within the range 5.5–8, appropriate to most industrial waters, and can lead to rigid behavior of circulating drops. The combined model in conjunction with the correlation developed here for the ratio of interfacial velocity to drop terminal velocity that links the film mass transfer coefficients of both sides can be used satisfactorily for design purposes. This model gives a maximum relative deviation of less than ±10% for the mass transfer directions of dispersed to continuous phase and vice versa.     

On motion of bubbles and drops

Dynamically interacting effects of surfactant impurities and neighbor particles on the transfer mechanism of momentum and terminal velocities of spherical bubbles, drops, or solid particle assemblages at low Reynolds numbers are analysed and formulated. The steady-state equations of viscous fluid motion and continuity (one set for each phase) have been solved simultaneously with a conservation equation for diffusing surfactant impurities. By employing a cell model with zero vorticity at its outer boundary, and modified interfacial conditions the terminal relative velocity of an ensemble of fluid particles is evaluated and compared with some available experimental data. The analysis of solid-fluid mixture is shown to become a special case of the analysis of fluid-fluid mixtures where adventitious surfactant impurities stop internal circulation thereby causing drop and bubble assemblages to behave as suspension of solid particles.     

Studies of drop break-up in liquid-liquid systems in a rotating disc contactor. Part II: Effects of mass transfer and scale-up

The number fraction of drops of a given size which break up at rotor level in a rotating disc contactor has been observed during mass transfer in either direction to or from solvent or aqueous drops. Critical rotor speeds for a given drop size undergoing mass transfer can be used to find an effective interfacial tension. Using this interfacial tension value, the break-up fractions are correlated within experimental uncertainties in the same manner as for no mass transfer. Drop break-up fractions depend on column size and relevant empirical correlations of the data are presented. The results may be used to estimate the effect of mass transfer on drop size distributions in an RDC.     

The effect of electric field on mass transfer from drops dispersed in a viscous liquid

Mass transfer of benzoic acid from drops dispersed into a continuous phase of mineral oil with high viscosity has been investigated both with and without an imposed non-uniform d.c. electric field. Total mass transfer efficiency was significantly enhanced in the presence of the high voltage electric field. The results indicate that the application of the electric field to the drop formation process does not change the fundamental mass transfer mechanisms and the mass transfer during drop free fall can also be described by existing mass transfer models. The results also suggest that the high viscosity of the continuous phase inhibits the drops oscillation as well as circulation when the drop sizes become smaller under the applied high voltage electric field. Therefore the significant enhancement of mass transfer efficiency in the present work is mainly due to the increased specific interfacial area.     

液滴凝并端效应对单液滴传质测定的影响及消除

For the mass transfer to single drops during the stage of steady buoyancy-driven motion, experimental measurement is complicated with the terminal effect of additional mass transfer during drop formation and coalescence at the drop collector. Analysis reveals that consistent operating conditions and experimental procedure are of critical significance for minimizing the terminal effect of drop coalescence on the accuracy of mass transfer The novel design of a totally-closed extraction column is proposed for this purpose, which guarantees that the volumetric rate of drop phase injection is exactly equal to that of withdrawal of drops. Tests in two extraction systems demonstrate that the experimental repeatability is improved greatly and the terminal effect of mass transfer during drop coalescence is brought well under control.     

Salt Effects on Single Aqueous Drops Falling through an Immiscible Organic Liquid

Drop settling (or rising) is crucial to the breaking of liquid-liquid dispersions. Most of the empirical correlations for terminal velocity of drops are formulated based on experimental data for systems of dispersed organic phase and continuous aqueous phase using pure and nearly pure liquids. Because the presence of the various third components in one or both of the phases mayaffect the settling of the drops, the terminal velocity and the onset of oscillation of aqueous drops containing various concentrations of electrolytes falling through n-dodecane were studied in this work. The applicability of existing empirical correlations to these reversed systems of continuous organic phase and dispersed aqueous phase was also examined. Dissolved electrolytes have the effect of causing the terminal velocities and their peak velocities at the onset of drop oscillation to become faster and the peak diameters to become smaller when their concentrations are high enough to cause sufficient changes of physical properties. Existing correlations for drop terminal velocity in pure systems are shown to be adequate in the presence of electrolytes. For high interfacial tension systems, the Hu-Kinter correlation predicts the terminal velocity of organic drops in water and aqueous drops in organics equally well, independent of the presence of electrolytes. The criteria of Hu-Kintner can be used to estimate the peak velocities and peak diameters at the onset of oscillation within a deviation of 3.7%.     

CONTINUOUS PHASE MASS TRANSFER COEFFICIENTS FOR SINGLE DROPLETS MOVING IN AN INFINITE DROPLET CHAIN

Continuous phase mass transfer coefficients have been measured for a stream of drops falling freely in a stagnant liquid. Drop streams were produced by a dripping method and by a jet breakup method. Water and isobutanol, mutually saturated, were used as the dispersed and the continuous phases, respectively. Sodium hydroxide was used as solute and was transferred from the bulk solution of isobutanol to water drops which was initially free of solute. Resistance to the mass transfer was observed to be on the continuous phase side. The mass transfer coefficient and terminal velocity of drop streams were measured experimentally. The experimental results show that the mass transfer coefficient in the drop stream is affected by the shielding effect of the previous drops. An approximate analysis was conducted for the shielding effect of a drop stream on mass transfer coefficient caused by the superposing wakes produced by each drop in the stream. The resulting equation describes the effect of interdrop distance on mass transfer coefficient in the continuous phase side and the experimental data have been correlated as K,/U_t ^0.5 versus interdrop distance /. Good results were achieved and also can be applied to other liquid-liquid systems.