PLANTWIDE CONTROL STUDY OF A VINYL ACETATE MONOMER PROCESS DESIGN

ABSTRACT

A simulation of a vinyl acetate monomer (VAM) process design was developed and compared with the work of Luyben and Tyreus (1998 Luyben , M. L. and Tyreus , B. D. ( 1998 ). An industrial design/control study for the vinyl acetate monomer process , Comput. Chem. Eng. , 22 , 867 – 877 . [CSA] [CROSSREF] [Crossref], [Web of Science ®] , [Google Scholar]). Two incremental changes were made to the two main control substructures. Specifically, the two schemes focus on improving the liquid inventory system control and controllability of the azeotropic distillation column. The level control strategy was tested and found to produce a faster response with less oscillatory behavior. Two alternative control techniques for the azeotropic distillation column were tested, a feed-forward model predictive controller and a static feed-forward ratio controller. The model predictive controller results illustrated the large difference between the water composition analyzer sample time and the controller step size. The static feed-forward ratio controller showed excellent disturbance rejection of large feed flow variations to the azeotropic distillation column. Simulation results are presented to illustrate the effectiveness of the new control strategies.     

乙烯基吡咯烷酮与乙酸乙烯酯共聚的研究

以偶氮二异丁腈 (AIBN)为引发剂 ,乙醇为溶剂 ,采用自由基溶液聚合方法研究了乙烯基吡咯烷酮 (VP)—乙酸乙烯酯 (VAC)共聚反应。研究了引发剂质量分数及单体质量分数与转化率和分子质量的关系 ,还研究了聚合反应温度对转化率与分子质量的影响 ,同时探索了控制共聚物组成分布均匀的方法     

醋酸乙烯共聚物碱醇解研究

本文以氢氧化钠 NaOH 为催化剂,甲醇为溶剂进行醋酸乙烯(VAC)——不饱和二元羧酸共聚物的醇解反应,研究了各种因素对醇解反应速率的影响,得到了宏观动力学规律,为制备共聚改性聚乙烯系列高分子表面活性剂工艺配方的确定,以及醇解度的控制提供了基础数据。     

醋酸乙烯酯—丙烯酸丁酯共聚乳液的合成研究

采用半连续法和间歇法合成了醋酸乙烯酯、丙烯酸丁酯共聚乳液。通过对不同聚合方法合成的乳液胶膜性能的研究,表明半速续法合成的乳液腹膜性能优于间歇法并讨论了其原因。采用半连续法合成不同单体配比的共聚乳液,研究结果表明,胶膜的耐水性、初始粘接强度等性能随丙烯酸丁酯含量的增加而提高。     

用改变加料速率研究VAc-BA半连续乳液共聚

研究了 70℃ ,VAc-BA的种子半连续乳液共聚反应 ,考察其动力学规律 ,对实验结果用作者已建立的简化动力学模型进行处理 ,模拟结果较好 ,说明简化模型有较好适用性。     

KSP引发醋酸乙烯酯与海藻酸钙小球接枝共聚反应

笔者以过硫酸钾为引发剂，研究了醋酸乙烯酯（VAc）与海藻酸钙（Calcium alginate）小球的接枝共聚反应；利用FTIR表征了接枝产物；并探讨了单体用量、反应时间和小球粒径对接枝率的影响；5g初始粒径为2．5mm的小球与浓度为3．62mol/L的VAc单体在48℃反应3h，接枝率可达1074％。     

醋酸乙烯酯—丙烯酸丁酯矫正批量法乳液共聚合

在自由基共聚反应中,随反应进行,共聚物组成一般会发生变化,尤其是当共聚单体竞聚率差异较大时,如自由基乳液共聚合中,批量法(Batch)合成的醋酸乙烯酯(VA)与丙烯酸丁酯(BA)的共聚合乳液胶粒常具有“类核壳结构”,即胶粒内核与外壳高分子组成差异很大,为了合成具有均匀结构与组成的共聚物,本文采用了矫正批量法(Corrected batch)乳液共聚合,对VA-BA共聚体系进行了研究。结果表明选择恰当的投料速率,即使对于VA-BA这样况聚率相差很大的共聚单体对采用本过程也能够合成组成较为均一的共聚物,粒径小于批量法合成的胶粒,胶粒分散度较批量法中大,但优于半连续过程,矫正批量法中胶粒平均自由基数目在反应过程中基本保持恒定,与批量法中对本体系的研究结果形成鲜明对比,由于VA的水溶性,水相聚合在该反应过程中占有一定比重。     

合成醋酸乙烯催化剂制备条件的研究

采用过量浸渍法制备乙炔气相法合成醋酸乙烯催化剂醋酸锌/活性炭,对制备条件进行了研究.结果表明,较合适的浸渍条件为醋酸锌浓度0.8mol/L,平衡时间60min,浸渍温度55℃.120℃下干燥30min水分就完全烘干,而90℃下干燥70min催化剂才达到恒重.由比表面积分析可知,随着干燥温度的升高,中孔被堵塞,催化剂的平均孔半径减小;干燥温度高于110℃后,比表面积和平均孔半径变化不明显.由SEM可以看出,催化剂表面明显存在醋酸锌晶体.     

羰化法制醋酸乙烯

本文着重对羰化法制醋酸乙烯的催化技术进行了评述。此法不需要乙烯（或乙炔）及醋酸，而只使用甲醇和合成气即可同时制取醋酸乙烯和醋酐。本文还对醋酸乙烯传统生产方法的生产过程和催化技术进行了简要的评述。     

MULTIVARIABLE PROCESS IDENTIFICATION AND CONTROL OF CONTINUOUS FLUIDIZED BED DRYERS

Dynamic models that rigorously describe fluidized bed dryers based on the fundamental principles of the process are usually so complex to be employed in control system design. To obtain simple reduced-order models for such systems, a sequence of step changes in the manipulated and load variables is introduced into the rigorous model. The obtained input-output dynamic response data are used for off-line model identification. Different types of linear models are generated, which are shown to be adequately representing the fluidized bed drying dynamics. The derived models are useful to develop model-based control algorithms such as Internal Model Control (IMC) and Model Predictive Control (MPC). Performance and robustness properties of these controllers are analyzed. Simulation results demonstrate a good performance in terms of tracking and load rejection capabilities.     

DYNAMIC PERFORMANCE-BASED DESIGN FOR PLANTWIDE CONTROL STRUCTURE

This article presents a plantwide control structure design using dynamic performance-based optimization. The controlled and manipulated variable sets were obtained heuristically. The main plantwide control structures were established via dynamic optimization and the rest established via heuristic rules. The optimization problem was formulated as dynamic mixed integer nonlinear programming with objective function of measuring the control performance (ITAE of CVs) and the cost of manipulated variables (ITAE of MVs). The integer matrix in the formulation represents the plantwide control structure explicitly. The Tennessee Eastman (TE) process was selected to illustrate the proposed design procedure. The obtained control structures were evaluated via dynamic simulation in the face of various disturbances and set-point changing. The results were then compared with the control structure proposed by Luyben et al. (1999 Luyben , W. L. , Tyreus , B. D. , and Luyben , M. L. ( 1999 ). Plantwide Process Control , McGraw-Hill , New York . [Google Scholar]).     

MULTIVARIABLE PROCESS IDENTIFICATION AND CONTROL OF CONTINUOUS FLUIDIZED BED DRYERS

ABSTRACT

Dynamic models that rigorously describe fluidized bed dryers based on the fundamental principles of the process are usually so complex to be employed in control system design. To obtain simple reduced-order models for such systems, a sequence of step changes in the manipulated and load variables is introduced into the rigorous model. The obtained input–output dynamic response data are used for off-line model identification. Different types of linear models are generated, which are shown to be adequately representing the fluidized bed drying dynamics. The derived models are useful to develop model-based control algorithms such as Internal Model Control (IMC) and Model Predictive Control (MPC). Performance and robustness properties of these controllers are analyzed. Simulation results demonstrate a good performance in terms of tracking and load rejection capabilities.     

RADICAL DESORPTION IN EMULSION POLYMERIZATION OF VINYL ACETATE

In the present paper a model equation for calculating the radical desorption rate constant,k_0,in the emulsion polymerization of vinyl acetate was suggested and the various parameters forevaluating k_0 were determined.Effects of reaction temperature,emulsifier concentration,initiator con-centration,monomer conversion and phase ratio on k_0 were studied.It indicates that the desorptionof radicals from latex particles to aqueous phase must be taken into account in the modelling ofemulsion polymerization for the monomers with higher hydrophilicity such as vinyl acetate.     

DENSITIES AND DERIVED THERMODYNAMIC PROPERTIES OF THE BINARY SYSTEMS OF BENZENE WITH BUTYL METHACRYLATE, ALLYL METHACRYLATE, METHACRYLIC ACID, AND VINYL ACETATE AT 298.15K

Densities of the binary systems of benzene with butyl methacrylate, allyl methacrylate, methacrylic acid, and vinyl acetate have been measured as a function of the composition, at 298.15 K and atmospheric pressure, using an Anton Paar DMA 5000 oscillating U-tube densimeter. The calculated excess molar volumes were correlated with the Redlich-Kister equation and with a series of Legendre polynomials. The excess molar volumes are positive for the four binaries studied.     

氯乙烯－二烯类单体悬浮共聚物凝胶点前的分子量模型

从氯乙烯（ＶＣ）两相聚合的特点出发，根据拟动力学常数法和分子量分布矩理论，建立了ＶＣ－微量二烯类单体悬浮共聚物凝胶点前的分子量模型，求得悬挂双键表现活性。结果表明：模型可很好地描述反应过程中分子量变化，悬挂双键表现活性下降一个数量级，物理效应对交联反应有较大的影响。     

硅烷偶联剂改性醋丙乳液的研究

介绍了硅烷偶联剂改性醋丙乳液的制备方法,并对涂膜性能进行了探讨。     

二氯乙烷裂解过程模拟研究

建立了二氯乙烷裂解制氯乙烯过程的数学模型，进行了裂解过程的模拟研究；为实现生产操作条件的优化，考察了操作参数对裂解过程的影响。模拟结果不仅可以计算沿裂解反应管的物料分布，能同时得到裂解管壁温度分布、管内物流温度分布及压力分布等，可作为设计、操作分析及优化的依据。     

氯乙烯废水AOPs过程及其反应动力学

研究了含氯乙烯废水AOPs(O3/H2O2)氧化降解过程及其反应动力学,实验研究了不同的操作条件如不同的反应物浓度、不同pH值对氧化物反应的影响。     

二氯乙烷裂解过程研究

研究了二氯乙烷裂解制氯乙烯过程的影响因素。确定了二氯乙烷裂解生成氯乙烯及副产物的反应过程为串连反应模型，研究结果可用于工业裂解炉操作优化分析，为裂解炉模拟计算提供基础数据。     

醋酸乙烯和聚乙烯醇产品需求预测

详细介绍和分析了醋酸乙烯和聚乙烯醇的用途及国内外市场需求，生产装置和生产能力的变化趋势。