恒回流比多组分间歇精馏计算

采用"瞬间稳态"法计算恒回流比多组分间歇精馏过程.提出操作初始态馏出液组成的设定依据,减少回流比和理论板数设计的盲目性.程序完善多组分间歇精馏回流比和理论板数的计算方法,简化馏出液瞬间组成、平均组成及釜残液瞬间组成的计算过程.     

恒馏出液组成间歇精馏回流比的控制和调节

计算及模拟间歇精馏过程已成为国内外许多学者的研究课题.以恒馏出液组成操作方式的间歇精馏,调节与控制回流比十分重要,过程计算复杂,计算量也很大.在Excel中,递推公式结合VBA编程求取了初始回流比Ro和最终回流比Re;VBA程序与Excel图表的数据通讯获得了各塔板气液组成的动态数据;Excel与VBA的混合编程得到了蒸馏时间与塔釜组成、塔釜组成与回流比的动态函数关系;为间歇精馏的动态调节、控制回流比和计算机模拟等问题提供了解决的途径.     

费萨姆工艺无水氨精馏塔的模拟计算

本文以ＮＨ３－Ｈ２Ｏ系统Ｇｉｂｂｓ自由能、熵、焓和汽液相平衡的热力学模型为基础，用松弛法进行了无水氨精馏塔的模拟计算。改变无水氨采出比、回流比（直汽量）和进料板位置均影响蒸馏效果。     

萃取抽提混合二乙苯中间二乙苯的研究

采用单级循环汽液平衡釜测定混合二乙苯不同组分与溶剂之间的汽液平衡数据,计算间二乙苯与主要组分之间的相对挥发度,并与模拟结果进行对比,确定萃取精馏分离的最佳溶剂。采用Aspen Plus软件进行模拟研究,考察了理论板数、塔顶采出比、溶剂比、回流比等因素对分离过程的影响。模拟结果表明,在理论板数为80块、进料位置为第40块、塔顶采出料比为0.7:1、溶剂比为5:1及回流比为5:1的优化条件下,间二乙苯质量含量由59.00%提高到79.00%,收率达到93.73%以上。本文研究为进一步萃取和结晶提取间二乙苯提供条件。     

基于Mathematica的二元连续精馏塔理论板层数新计算方法

本文提出用数学软件Mathematica计算连续二元精馏塔理论板层数的新方法。该法编程简单,函数关系式与一般数学公式的形式极为接近,计算过程快捷,结果精确。既得到理论板的层数,又得到各理论板上气液组成的准确数据,绘制有关函数图形非常方便。利用此方法,讨论塔顶、塔釜、进料组成x_D、x_W、x_F、进料热状况q值、回流比R、相对挥发度α等因素对连续二元精馏塔理论板层数和加料板位置的影响,用图示的方法分析其原因,从而得出规律,免去复杂、繁琐、耗时的手工计算,成为教师授课和工程技术人员得心应手计算的工具,又可提高学生利用计算机解决精馏塔理论板层数的能力。     

间歇精馏设计软件的开发

利用Visual Basic 6.0语言开发间歇精馏常规设计及优化设计软件。软件可用于不同物系(二元理想及非理想溶液)，采用不同操作方式(恒馏出液组成操作和恒回流比操作)间歇精馏的常规设计和优化设计(包括单变量优化和多变量优化)计算。软件采用面向对象的编程技术，对精馏组分的物性参数、汽液相平衡数据实行数据库操作，界面友好，使用方便。     

回流比恒定的间歇精馏工艺计算方法改进

以正庚烷-正辛烷体系为例,根据R=f(n,XD)=nRmin,以假定最初的馏出液组成XD,0和n值,交替进行两次迭代试差,最终确定最小回流比和适宜回流比,修正了文献所给出的不妥之处。另外,用解析计算取代面积积分,求解釜液量。     

模拟甲基叔丁基醚反应精馏的过程

为揭示反应精馏过程的耦合特性,从而为进一步开发新的反应精馏设计方法提供理论支持,采用Gibbs自由能平衡级模型,应用Aspen Plus软件模拟分析MTBE的反应精馏过程,研究了回流比与理论板数对反应和分离效果的影响。结果表明由于反应和精馏的相互作用,在固定回流比改变理论板数(或固定理论板数改变回流比)的情况下,存在最佳理论板数(或回流比)使产品组成最高,这种特性与普通精馏有所不同。     

进料位置对双组分精馏过程耗能原因的分析

利用Aspen Plus软件对正庚烷-正辛烷双组分物系的精馏过程进行模拟计算。通过灵敏度分析确定最小回流比和理论板数的基础上,考察精馏塔的进料板位置、回流比等因素对分离精度、塔内气液相组成、温度分布和能耗的影响,结果表明,固定总板数和进料板位置,随着回流比的增加,塔顶产品组成随之增加;回流比改变,最优进料板位置也会发生变化;在达到分离要求的情况下,随着进料板位置的下移,塔顶热负荷、塔底热负荷和总热负荷先降低后升高;在最优进料板进料时,进料气液相组成和温度分布与进料板上的气液相返混程度和温度返混最小,每块塔板均为有效板,具有较高的分离能力,此时能耗最小。     

间歇精馏常规设计和优化设计的模型及算法

建立了板式间歇精馏塔在恒馏出液组成操作状况下常规设计及优化设计的数学模型。常规设计模型用数值方法编程求解，对二元理想及非理想溶液均适用。优化设计模型以间歇精馏系统年效益最大为优化目标，用菲波那契法求解单变量优化问题，用复合形法求解多变量优化问题。模型同时考虑对整个间歇精馏系统(包括塔主体、塔顶冷凝器及塔底再沸器)进行优化，更符合工程实际情况。求解模型可得到间歇精馏过程最优的一系列设计和操作参数(如理论板数，塔径，操作回流比，塔釜蒸发量，釜残液组成，冷凝器传热面积及冷却水出口温度，再沸器传热面积及加热蒸汽温度等)。算例表明，对恒馏出液组成间歇精馏单变量及多变量优化设计比常规设计分别提高年效益2．6％和18．9％。     

复合萃取精馏分离乙酸乙酯-乙醇-水的研究

介绍了乙酸乙酯在工业生产中的应用；在前人的研究基础上，采用合适的萃取剂，在萃取塔上考察了不同溶剂比、回流比等因素对产品纯度的影响，并摸索复合萃取分离乙酸乙酯－乙醇－水三元体系的适宜操作条件，在溶剂比为1：1：1，R=4时，能一次得到高浓度（99．5％）的乙酸乙酯，同时得到95％的乙醇溶液，得率高、能耗低，为工业试验提供了基础数据。     

稀醋酸共沸精馏脱水工艺的模拟

醋酸是一种重要的化工原料,其水溶液广泛存在于各类工业过程中。由于醋酸与水会缔合使得两者的相对挥发度不大,生产中用于分离醋酸/水的工艺能耗较高,因此研究者和工业界都在寻求更好的分离方法。本文以醋酸正丙酯做挟带剂,应用Aspen Plus流程模拟软件,汽相逸度采用Hayden-O’Connell方程,液相活度系数采用NRTL方程计算,实现了稀醋酸共沸精馏脱水工艺的模拟。本文详细讨论了全塔理论板数、进料位置、回流比等因素对脱水塔性能的影响。结果表明,在理论板数50块,回流比3.2,醋酸进30块板,挟带剂与进料比0.15条件下,塔釜得到醋酸浓度高于95%。模拟结果对醋酸脱水工艺的设计和改造具有重要的指导意义。     

用热敏液晶粒子实现流体温度场的可视化

热敏液晶是图象测量技术研究中采用的新型敏感材料，针它密封装入圆球形微型胶囊中，要实现流体温度场的可视化定量计量。热敏液晶的ＲＧＢ值与温度之间的特性具有严重的非线性，而且因实验条件不同而异。本文介绍了它的色／温转换特性和摄影视角对该特性测量时的影响及其解决方法。     

Systematic search of low melting point alloys in the Fe–Cr–Mn–Mo–C system

In ternary systems, the liquidus surface is usually represented by a group of constant temperature contours projected onto a composition plane, i.e. the liquidus projection. The liquidus univariant lines indicate the conditions under which two solid phases coexist with the liquid phase. Those lines intersect at eutectics and peritectics. The univariant lines can also be projected onto a temperature vs. composition plane; this diagram allows easy identification of the lowest liquidus temperature on the system, covering the whole composition range of each component. This type of representation can also be used in quaternary and multicomponent systems, as a systematic tool to identify low melting point alloys as well as the solid phases involved at that temperature. This approach has been used in the present work to search low melting point alloys in the Fe–Cr–Mn–Mo–C system, using univariant line projections calculated with Thermo-Calc software and selected thermodynamic databases. The analysis covered the whole quinary system as well as the related binaries, ternaries and quaternaries. Some selected alloys of this system were prepared by mixing the elemental powders; the liquidus temperature was checked using calorimetric methods. The agreement between calculations and experiments is satisfactory.     

A lattice Boltzmann equation method for real fluids with the equation of state known in tabular form only in regions of liquid and vapor phases

We propose several simple interpolations of the isotherms for real fluids in the region below the binodal curve, where data concerning the equation of state is absent, especially in the thermodynamically prohibited region. All interpolations satisfy the boundary conditions at the points on the binodal curve. The Maxwell rule is also fulfilled. As an example, we construct several isotherms for real water. The data for the isotherms of water, in the liquid and vapor states, is given in tabular form. All smooth interpolations of the isotherms show similar hydrodynamic behavior of two-phase systems in LBE simulations. The reduced specific volumes of the liquid and vapor phases and the reduced pressure on the binodal curve obtained in the LBE simulations for the different interpolations agree well with the experimental data for real EOS of water. The surface tension depends on the form of the interpolation of the isotherm under the binodal curve. Hence, the value of surface tension can be varied in some range by changing the interpolation curve. Actually, our variant of the LBE method allows one to obtain the values of the liquid and vapor densities at the interface corresponding to the saturation curve of real fluids with high accuracy. At low temperatures, the large values of the liquid-to-vapor density ratio can be obtained, in accordance with the EOS of real fluids.     

State estimation and inferential control for a reactive batch distillation column

An optimal reflux ratio profile is obtained for a reactive batch distillation system utilizing the capacity factor as the objective function in a nonlinear optimization problem. Then, an Artificial Neural Network (ANN) estimator system, which utilizes the use of several ANN estimators, is designed to predict the product composition values of the distillation column from temperature measurements inferentially. The network used is an Elman network with two hidden layers. The designed estimator system is used in the feedback inferential control algorithm, where the estimated compositions and the reflux ratio information are given as inputs to the controller to see the performance of the ANN. In the control law, a scheduling policy is used and the optimal reflux ratio profile is considered as pre-defined set-points. It is found that, it is possible to control the compositions in this dynamically complex system by using the designed ANN estimator system with error refinement whenever necessary.     

Effect of interaction multiplicity on control system design for a MTBE reactive distillation column

The control strategy of a reactive distillation for synthesis of MTBE is investigated. Although steady state multiplicities occur in the column, a linear control is still possible since a controlled and manipulated variable-pairing scheme that exhibits a sufficiently large range of near linear relations can be found, if we operate at constant reflux ratio. Reboiler duty is used to control the temperature of a stage just below the reaction section and near the top of the stripping section. Stoichiometric balance is controlled by a feed ratio plus internal composition control scheme, using a control valve installed on the C4 feed-line as the manipulated variable. Such a scheme is capable of maintaining the desirable steady state that achieves high product purity and reactant conversion. However, a similar scheme that uses a control valve installed on the methanol feed-line as the manipulated variable shows severe oscillation. It is caused by multiplicity in the interaction between the temperature and stoichiometric control loops.     

基于塔板组成线的反应精馏图解设计

图解设计法，可以相对较少的已知数据快速、直观地获得反应精馏塔的结构和操作参数。本文在转换组成变量的基础上，系统地推导了反应精馏塔板组成线方程及设计可行性判据，提出了基于塔板组成线进行反应精馏图解设计的策略，并对理想反应体系进行了实例设计计算。研究结果表明：利用塔板组成线进行反应精馏设计可同时获得多组可行设计方案，比现有精馏线和剩余曲线设计方法更为有效，并有利于设计的优化和经济效益评价。