DESIGN AND IMPLEMENTATION OF STATE OBSERVERS IN REACTIVE DISTILLATION

This study demonstrates that state observers can be developed and applied to infer the composition profiles of reactive distillation columns from noise-contaminated temperature measurements. The design and implementation of a Kalman filter (KF) and a Luenberger observer (LO) are carried out, and their performances are quantitatively assessed. The reliability, accuracy, and robustness of the two designs method are examined and compared quantitatively. The design and implementation of a Luenberger observer are simpler and easier to carry out than those of a Kalman filter. On the other hand, a Kalman filter is found to be more robust to a noisy measurements, erroneous initial estimates, and model uncertainties. A Luenberger observer could be used for composition estimation of reactive distillation when an ideal model of the system can reasonably approximate the real system; otherwise, a Kalman filter is recommended to be applied in more practical situations.     

反应精馏工艺流程的合成

反应精馏工艺是近年来倍受重视的研究领域之一,但反应精馏工艺流程的选择目前仍然靠人们的经验和实验探索．本文通过对传统化工工艺流程的理论分析,阐明了传统工艺流程与反应精馏工艺流程的相互关系,从而提出了一种反应精馏工艺流程的构成方法．     

精馏过程专家系统用数据库系统的设计与实现

化工物性数据内容庞杂，数据库的设计是化工软件的重点和难点，本文提出一种用ＴＵＲ－ＢＯＰＲＯＬＯＧ语言外部数据库技术实现基于磁盘的数据库管理系统的设计方法，解决了数据库庞大与微型机内存不够的矛盾，通过接口计算模块可方便地从本数据库中调用数据；实现了友好的用户界面，提高了数据库管理的效率和透明性。     

CLASSIFICATION OF REACTIVE DISTILLATION PROCESSES BY DIMENSIONLESS NUMBERS

In the present paper a comparative consideration is given for the physico-chemical phenomena involved in homogeneously and heterogeneously catalyzed reactive distillation processes (RDP). The processes are classified qualitatively by dimensionless parameter groups derived from the balances for vapor, liquid and solid phases according to the principles of irreversible thermodynamics. The groups are applied to analyze industrial processes and experimental data for esterification, etherification and alkylation regarding different catalysts, operating conditions and configurations of plants. The mathematical models published until today and the experimental results are contrasted taking the parameter groups as a basis. This gives a discrimination of the models and some recommendations for their applicability.     

DYNAMIC BEHAVIOR OF REACTIVE DISTILLATION COLUMNS. EQUILIBRIUM SYSTEMS

This paper deals with the dynamic behavior of simultaneous reaction-separation systems which operate at or near the chemical equilibrium in the liquid phase. The process under study comprises a whole set of “instantaneous”, and very fast reversible reactions where the difference in volatilities favors both the progress of reaction and product separation. The main aim of our study is to gain a deeper understanding of the dynamic behavior of distillation columns by using a model that is simple and efficient, yet informative. This kind of model is outstanding for synthesis and design of control schemes which require a careful modelling and understanding of process response to different changes in the environment. We use a suitable transformation of variables (after Barbosa and Doherty, 1988b) in order to define a new set of state variables; as a result, the balance equations become identical to those for conventional distillation. Also, an efficient physicochemical algorithm that can handle both the original and new state variables is used. Thus, a composition-holdup dynamic model is simulated in the “transformed field” using a stage-by-stage approach. To further reduce computational time, the transformed problem has also been solved by means of a reduction procedure based on approximating by orthogonal polynomials the transformed composition and flow profiles in the column. The performance of the two proposed methods are compared by using the top section of a quaternary reactive column. The results obtained shown that reactive distillation dynamics has certain peculiarities derived from superimposing reaction and separation phenomena.     

GRAPHICAL PROCEDURE FOR REACTIVE DISTILLATION SYSTEMS

In this paper we analyze a ternary reactive distillation system, where an equilibrium chemical reaction occurs in the liquid phase. By using a set of transformed variables proposed by Barbosa el al. (1988b) and well known graphical procedures for non-reactive systems; the minimum reflux ratio, minimum number of equilibrium stages, mass and energy balances for a reactive column and flash can be easily obtained. The procedures developed in this paper are applied to ISOBUTYLENE-METHANOL-MTBE system.

The main objective in developing this model is to obtain, as much as possible, rigorous information for the analysis of one reactive distillation column in a Process Simulator with capability of handling this type of new operation.     

连续反应精馏合成正硅酸乙酯的研究

讨论了连续反应精馏合成乙酯的新工艺,将反应和精馏在一个设备中完成,考察了釜温、进料温度、进料速度、回流量及进料口位置对连续反应精馏的影响,筛选较佳的工艺条件。     

A REACTIVE DISTILLATION PROCESS FOR AN AZEOTROPIC REACTION SYSTEM: TRANSESTERIFICATION OF ETHYLENE CARBONATE WITH METHANOL

A reactive distillation process is proposed for manufacturing dimethyl carbonate (DMC) through the transesterification reaction of ethylene carbonate (EC) with methanol. Modeling and simulation of the reactive distillation column have been carried out to study the effects of operating conditions, such as the reflux ratio, the number of theoretical plates, the feed ratio, the top effluent, the liquid holdup, and the feed location, on EC conversion and product composition at the top of the reactive distillation column. The calculated results show that a complete EC conversion can be achieved. The model reliability is analyzed under different Murphree tray efficiencies, showing no considerable difference between the equilibrium and nonequilibrium models for this system. And the calculated results are verified by experimental data and commercial operation of a dimethyl carbonate plant of 10,000 tons per year.     

DESIGN OF BATCH DISTILLATION COLUMNS FOR BINARY MIXTURES

In this note analytical equations are presented that describe the separation obtained for binary batch distillation. Formulas are obtained for both the constant distillate composition and constant reflux methods of operation. The results are strictly for distillation with an infinite number of stages ( corresponding to minimum reflux) however, it is shown that the equations derived closely describe the operation with a small finite number of stages.     

乙烯装置丙烯精馏系统设计方案优化

介绍了丙烯精馏系统传统设计流程及改进设计流程,并对其流程特点进行了分析,明确指出了各自的优缺点。针对改进设计双塔流程,利用流程模拟计算PRO-Ⅱ软件平台,分别研究了无中间再沸器和设置中间再沸器两个流程方案,在能耗相同的条件下,计算出不同塔盘数时的丙烯损失,并对其增加塔盘数后的可实施性、投资增加与多回收丙烯的经济性进行了初步分析。无中间再沸器流程在投资及年收益方面均优于设置中间再沸器流程,在装置急冷水热量充足的情况下,应首先推荐应用。     

反应精馏合成2-羟丙基甲醚的研究

以甲醇和环氧丙烷为反应物,采用均相连续反应精馏法合成了２－羟丙基甲醚。对三乙胺、氢氧化钠、氢氧化钾、碳酸钠和碳酸钾五种催化剂的催化活性和选择性进行了研究。考察了以三乙胺为催化剂时进料摩尔比和环氧丙烷进料速率对环氧丙烷转化率、２－羟丙基甲醚选择性及收率的影响,并对反应精馏塔的温度分布进行了讨论     

REVIEW OF SIMULATION METHODS OF THE DISTILLATION COLUMN AND THERMODYNAMIC MODELS IN THE HI DECOMPOSITION SECTION OF THE IODINE-SULFUR PROCESS

The iodine-sulfur thermochemical water-splitting process (I-S process) is one of the most promising and efficient mass hydrogen production methods without greenhouse gas emissions. To a large extent, distillation in the HI decomposition section of the I-S process affects the efficiency of the entire process. This article summarizes the simulation methods for HI distillation in the iodine-sulfur process, including thermodynamic models, design schemes, and parameter analyses. The performance of the thermodynamic models and heat duties of different flow sheets were compared, and the preferable model and flow sheet are recommended. This study can provide a reference for the selection of thermodynamic models and it is also meaningful for the design and simulation of the HI distillation column.     

DESIGN OF A COMPOSITION ESTIMATOR FOR INFERENTIAL CONTROL OF DISTILLATION COLUMNS

In distillation column control, secondary measurements such as temperatures and flows are widely used in order to infer product composition. This paper addresses the design of the linear static estimators using the secondary measurements for estimating product compositions of distillation columns. Based on the unified framework for the estimator design, the relationships among various static estimators are discussed in terms of the estimator structure. Il is shown that the projection estimator is equivalent to the regression estimators in the special cases. Since the projection estimator heavily depends on the measured inputs such as reflux flow and heat input to the reboiler due to its structural characteristic, the estimation performance is far more sensitive to measurement noise and nonlinearity of them, compared wiih the regression estimators based on the PCR or PLS method. It is also found that the use of the measured inputs leads to performance deterioration of both the projection and regression estimators because of their nonlinear effects on the product compositions especially in high-purity columns. Design guidelines for the PCR and PLS estimators are presented by analyzing the results of the simulation studies on a high-purity column example. The estimator based on the guidelines is robust to sensor noise and has a good predictive power     

反应式挤出机的设计及应用

介绍了自设计的反应式挤出机的组成和技术特点,将其用于聚乙烯接枝马来酸酐的生产上效果良好。实验表明,它不但能够提高接枝效率,而且能将绝大部分的游离态马来酸酐分离法,可得到无色,无味,无气泡,表面光滑、纯净的ＰＥ－ｇ－ＭＡＨ产品。     

A DIRECT NONLINEAR ADAPTIVE CONTROL OF STATE FEEDBACK LINEARIZABLE SYSTEMS

A direct nonlinear adaptive control of state feedback linearizable single-input single-output systems is proposed in the case when parametric uncertainties are represented linearly in the unknown parameters. The main feature of the proposed nonlinear adaptive control system is that the linearizing coordinate transformation and the state feedback are updated by parametric adaptive law, derived using the second method of Lyapunov. The proposed adaptive control scheme is relatively straightforward and simple in the sense that it does not use the concept of augmented error. This adaptive control scheme is numerically applied to an exothermic chemical reactor system and is compared with the nonadaptive stale feedback linearization which has an integral action. The simulation shows that the proposed adaptive control scheme can be applied effectively to highly nonlinear, uncertain chemical systems.     

反应性聚合物微凝胶的合成及应用

反应性聚合物微凝胶是一种具有反应活性、分子内交联的高分子,它具有优良的施工性能,涂膜的力学性能及耐久性也十分优异,主要应用于制备高档涂料或对涂料进行改性。本文着重介绍了反应性聚合微凝胶的合成方法及其在涂料改性方面的应用。