利用压力影响恒沸点由反应精镏精制THF

研究压力如何影响恒沸点,探索改变操作压力由反应精镏精制四氢呋喃（THF）可行性。模拟计算考察了压力对THF/水体系恒沸点的影响,结果表明体系压力增加,恒沸物中THF摩尔分率减少。通过两塔在不同压力下操作,利用反应精镏;恒沸物;四氢呋喃     

二元恒沸物系若干特征的计算机预报

用模式识别和人工神经网络方法讨论了二元有机化合物恒沸物系的循环，总结了最低沸纱和最高恒沸点系的形成规律，并对最低恒沸点系或最高恒沸点系沸点处的组成及温度进行了预报，结果与实验基本相符。     

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.     

EXCEL实现恒回流比间歇精馏的计算机仿真

对于恒回流比操作方式的间歇精馏,过程计算量大且公式应用相对复杂,用计算机完成间歇精馏的过程计算及操作仿真已经成为许多国内外学者的研究课题。为了满足系统的响应速度,提高动态釜液量误差,用Excel的VBA、函数、图表及重算等功能,实现间歇精馏的计算机仿真的新方法。在Excel中,建立了间歇精馏过程的数学模型与“数据处理表”,完成多项式拟合,由递推公式确定塔内各塔板液相组成xn与时间t的动态响应关系。获得的六次拟合曲线接近于实测的平衡数据,其相关系数达到0．999,各塔板液相组成xn与时间t的动态响应关系与实际计算吻合较好,获得了较满意的结果,为设计提供有效依据。     

基于UNIFAC模型的碳酸二甲酯-甲醇-恒沸剂三元体系汽液平衡数据的推算

运用Visual Basic计算机语言，用UNIFAC方程模拟推算了碳酸二甲酯－甲醇－恒沸剂（分别为正己烷、环己烷、正庚烷、正辛烷）三元体系在常压下的汽液平衡。为采用恒沸精馏法分离DMC与甲醇共沸体系提供了汽液平衡数据。     

恒沸精馏乙酸丁酯和正丁醇过程的优化

乙酸丁酯和正丁醇是两种重要的有机化工原料,广泛应用在化工和制药行业中.在青霉素提取过程中产生大量的含乙酸丁酯、正丁醇、水的混合物,如何将其分离,有实际的意义.本文介绍皂化处理方法和恒沸精馏分离方法,通过利用3A分子筛优化恒沸精馏工艺过程,从而达到节能降耗20%的目的.     

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。     

热集成变压精馏分离甲缩醛和甲醇工艺模拟及优化

在分析甲缩醛和甲醇二元体系共沸特性基础上,提出热集成变压精馏分离甲缩醛和甲醇共沸体系的工艺方法。利用AspenPlus软件对该分离过程进行模拟计算,采用NRTL方程作为物性计算模型,其二元交互作用参数由汽液相平衡数据回归,详细分析了加压塔和常压塔的理论板数、进料位置和回流比对分离过程的影响,并进行能耗比较。结果表明,采用热集成变压精馏分离工艺,可很好地实现甲缩醛与甲醇的分离,较佳的操作条件为:加压塔操作压力1.0MPa,理论板数28,第18块板进料,回流比3.2,塔釜甲缩醛含量可达99.9%;常压塔操作压力0.1 MPa,理论板数24,第14块板进料,回流比2.6,塔釜甲醇含量可达99.5%。与常规变压精馏相比较,热集成变压精馏可节省能耗达35.5%,为共沸物分离过程的设计和改造提供依据。     

乙酸丁酯反应精馏过程模拟设计

反应精馏偶合了反应和精馏两种单元操作,通过精馏促进反应,可以提高反应转化率和收率,为可逆反应的化工过程生产提供了新的设计途径。基于严格热力学分析计算,利用计算机模拟和优化手段。提出了乙酸丁酯反应精馏、分离纯化的生产流程。采用UNIQUAC方程表征乙酸-正丁醇-乙酸丁酯-水四元非理想体系的汽液平衡,首先,根据实验数据回归了热力学模型中的交互作用参数,并预测了体系中5个共沸物组成,模型的计算结果与实际数据吻合。基于平衡级模型,提出了由平衡反应器、反应精馏塔、倾析器和纯化塔构成的可行流程,对提出的设计流程进行了模拟、优化,得到了操作工艺参数。模拟结果对工业过程的设计和改造具有一定的指导意义。     

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。     

Experimental investigation of conventional control strategies for a heterogeneous azeotropic distillation column

In this work, a laboratory scale sieve plate distillation column was constructed to investigate the conventional control strategies of an isopropyl alcohol (IPA), cyclohexane (CyH) and water (H₂O) heterogeneous azeotropic distillation column. Steady state process analysis showed that the optimal operation point should be located at a critical reflux, a transition point at which the distillation path switches from a route that passes through IPA+H₂O azeotrope to one that passes through IPA+CyH azeotrope. At this critical reflux, a high purity IPA product can be obtained with minimum energy consumption and maximum product recovery. However, the steady state is extremely sensitive to feed disturbances. A good control strategy must be able to maintain a steady column temperature profile that shows a plateau near 70°C to ensure passage around IPA+CyH azeotrope. In this study, an inverse double loop control strategy is recommended. Through experimental testing, the proposed control strategy was demonstrated to keep the product IPA purity at the desired high-purity level under all feed disturbance changes while other conventional control strategies fail.     

Two-point control of a reactive distillation column for composition and conversion

Reactive distillation is a hybrid process with dual process objectives: reactant conversion and product composition. Control schemes for reactive distillation frequently neglect the effect of the principal operating parameters on the reactant conversion, and this has a detrimental effect on the overall process profitability. An ETBE reactive distillation column has been used as a case study to show how a two-point control configuration, which recognises the importance of both composition and conversion, can be developed and implemented for a reactive distillation process. The combined composition and conversion control configuration was tested using SpeedUp dynamic simulations and proved to be effective in maintaining a high isobutylene conversion despite process disturbances. The two-point control scheme also had superior disturbance rejection capability, especially for feed rate changes, and composition set-point sensitivity compared with a one-point control scheme.     

Comparison of pressure-swing distillation and extractive distillation with varied-diameter column in economics and dynamic control

Pressure-swing distillation and extractive distillation are two common methods for azeotrope separation. The economics and controllability are two crucial factors for evaluating the feasibility of a separation process. A varied-diameter column (VDC) was used in the process design to evaluate its economics and controllability. Five azeotropic systems were investigated in order to compare the economics of pressure-swing distillation and extractive distillation with a VDC. Results indicate that pressure-swing distillation with a VDC saves more money than extractive distillation. The dynamic control were evaluated in the acetone-methanol system for both processes with a VDC. The improved control structure for pressure-swing distillation with a VDC can handle ±20% disturbances effectively, while the improved control structure for extractive distillation with a VDC can only handle ±10% disturbances. A comparison of the two methods from the viewpoint of economics and controllability demonstrates that pressure-swing distillation is more suitable when using a VDC.     

Plant-wide design and control of acetic acid dehydration system via heterogeneous azeotropic distillation and divided wall distillation

Energy-saving plant-wide design and plant-wide control of an acetic acid dehydration system with the feed containing methyl acetate and p-xylene are investigated in the study. A heterogeneous azeotropic distillation using isobutyl acetate as an entrainer is designed to obtain high-purity acetic acid at the column bottom and to keep a small acetic acid loss through the top aqueous draw. The accumulation of p-xylene in the column is avoided by adding a side product stream. The mixture in the aqueous phase of decanter, containing mostly water, methyl acetate, and isobutyl acetate is separated using a divided wall distillation column. The whole acetic acid dehydration system includes a heterogeneous azeotropic distillation column and a divided wall distillation column.The control strategies using temperature loops are proposed for this acetic acid dehydration system. For the heterogeneous azeotropic distillation column, the requirements for acetic acid compositions in both the aqueous phase of the decanter and the column bottom can be satisfied by designing entrainer inventory temperature control and cascade temperature control simultaneously. The stages of controlled temperatures are chosen by singular value decomposition and closed-loop analysis methods based on the criteria of minimum entrainer makeup. For the divided wall distillation column, steady-state analysis methods are used for the selection of proper controlled and manipulated variables and the determination of their pairings. Dynamic simulation results demonstrate that the proposed plant-wide control strategy can maintain product purities and reject external disturbances in feed flow and composition changes as well as internal disturbances such as changes in liquid and vapor splits.     

Adaptive dynamic matrix control of a distillation column with closed-loop online identification

This paper presents an online identification technique where a process is identified in terms of pseudo impulse response coefficients and subsequently used to update convolution type models to accommodate process-model mismatch. As an example, dynamic matrix control has been applied adaptively to control the top product composition of a distillation column for both servo and regulatory problems. The algorithm automatically detects a large step-like disturbance requiring fresh identification of the process and subsequently adapts the controller to the new model. Simulation studies using an analytical dynamic full order model of a distillation column demonstrated the usefulness of the adaptation scheme. Experimentation on a pilot scale distillation unit vindicated the simulation results.     

Control of reactive distillation production of high-purity isopropanol

The process characteristics and control strategy of a high-purity IPA reactive distillation column were investigated. A robust nominal operation was found by maintaining an excess of propylene feed to the column and recycling the unreacted propylene to the feed instead of the top stage. Stage temperature and propylene composition with one-to-one relationship with reboiler duty and propylene feed are selected as controlled variables for maintaining bottom purity and feed ratio in the presence of possible measurement bias respectively. High nonlinearity between selected input–output pair was reduced by using variable transformation. Dynamic simulations demonstrated that such a control scheme with nonlinear transformed variable was capable of providing much superior control performance than the one using natural variable.     

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。