丙烯酸分离装置的流程模拟与优化

运用Aspen Plus软件,对某公司8万t/a丙烯酸分离装置进行了流程模拟,模拟结果与实际值吻合良好。在此基础上,分别对急冷塔、脱轻组分塔、醋酸塔和丙烯酸提纯塔的工艺参数进行了模拟优化,确定了优化后的工艺参数:急冷塔液气比为0.103,脱轻组分塔甲苯回流量为2.8×104kg/h,醋酸塔塔顶采出率为0.778,丙烯酸提纯塔回流比为1.20。此外,还对脱轻组分塔的流程进行了优化,将塔顶水相部分循环用作急冷塔吸收剂,节约了36%的新鲜用水量。通过工艺参数和流程优化,不仅丙烯酸产品质量分数达到99.96%,而且使脱轻组分塔、醋酸塔和丙烯酸提纯塔的总能耗降低9.81%。     

硫黄回收装置流程模拟及优化

硫黄回收装置外排尾气指标受多方面的影响,主要包括克劳斯反应温度、加氢反应温度、溶剂吸收系统参数等,为提高装置整体运行效率,同时兼顾尾气排放指标与装置能耗的平衡,利用Aspen Plus软件对硫黄回收装置进行建模,并利用模型对装置在不同条件下的运行情况进行模拟,根据运行结果分析各运行条件对主要工艺参数的影响,拟定装置运行的优化方案.     

基于Aspen Plus醋酸乙烯精馏塔的模拟优化

利用Aspen Plus软件,选择NRTL活度系数方程和Hayden-O′connell逸度系数方程的热力学模型,应用系统中的RadFrac精馏模块对醋酸乙烯精馏塔进行模拟,模拟值与实际值基本吻合。讨论了进料位置、回流比、塔顶侧线采出量等参数对精馏分离精度与能耗的影响,提出优化方案为：进料板为第62块,回流比为32,侧线采出质量流量为37.5 t/h。此参数下,重新进行计算,结果显示,塔顶冷凝器和塔釜再沸器的热流量分别降低了15.5%和16.9%,塔顶侧线采出液中醋酸乙烯和塔釜采出液中醋酸的质量分数分别上升了0.4%和0.13%。     

基于Aspen Plus的氨吸收制冷流程模拟

通过对氨吸收制冷工艺的深入研究,运用Aspen Plus软件模拟氨吸收制冷流程,并研究分析吸收器操作压力对出口氨水浓度和液氨蒸发温度的影响。     

DEF精馏系统的模拟与优化

利用Aspen Plus V8.6模拟软件,对第一精馏塔(T1)和第二精馏塔(T2)进行模拟与优化.经分析确定了T1塔和T2塔最佳工艺条件为:理论板数分别26块和35块,进料位置分别在10块塔板和13块塔板,回流比分别为19和0.5,此时DEF质量分数≥99.9％,二乙胺质量分数≤0.015％,重组分质量分数≤0.01...     

Aspen Plus化工流程模拟软件学习和使用的几点体会

Aspen Plus是一款功能强大的集化工设计、动态模拟及各类计算与一体的模拟软件。介绍了Aspen Plus化工流程模拟软件的学习方法和使用的几点体会,化工流程软件的应用提高了学习兴趣,加深了对相关专业课程的理解和实践动手能力。同时Aspen Plus软件模拟比较接近实际工况,使化学工程与工艺专业的课程设置和学习内容更符合社会实际需要。     

Aspen Plus软件模拟CO变换流程的研究

运用Aspen Plus软件中3种不同反应器模型组合成RPlug-RPlug-RPlug,RPlug-RPlug-RGbbis和RPlug-RPlug-RCSTR模型,分别对CO变换流程进行模拟。对3个组合模型的模拟结果进行分析发现:RPlug-RPlug-RPlug组合模型模拟经过整个变换炉后CO的总转化率为68.5%,比实际结果低7%左右;RPlug-RPlug-RGbbis组合模型模拟经过整个变换炉后CO的总转化率为99.33%,是不可能实现的过程;RPlug-RPlug-RCSTR组合模型模拟经过整个变换炉后CO的总转化率为74.2%,与实际情况的结果最相近,为最适宜的CO变换流程模拟模型,能够真实客观地模拟出整个变换流程。     

冰片副产物粗品白轻油及小茴香油的资源化回收工艺模拟与优化

合成冰片在医药、化妆品以及香料中应用广泛。本文用Aspen Plus软件设计处理冰片生产工艺中产生的白轻油与小茴香油废液体系的分离提纯工艺。为高效回收副产物小茴香油及白轻油中经济价值较高的组分,以葑醇、冰片、莰烯和蒎烯等物质的回收率、产品纯度为目标,对工艺参数进行优化。结果表明,在优化操作参数下,莰烯和蒎烯产品回收率高达97.66%,葑醇回收率93.85%。为冰片的大规模连续化工业生产提供了参考。     

氯醋共聚树脂生产中未反应单体回收工艺优化

针对氯醋共聚后未反应单体直接采用压缩冷凝回收技术存在的问题进行了技术改造,采用常压蒸馏技术分离氯乙烯和醋酸乙烯酯,并增加了乙醛在线监测装置和碱洗塔,改造后氯乙烯回收率可达98%~99%,醋酸乙烯酯回收率可达95%~96%。     

Interactions of polyvinyl alcohol and vinyl acetate monomer in aqueous solution in relation to emulsion polymerisation of vinyl acetate

Polyvinyl acetate (PV-OAc) emulsions made from vinylacetate (V-OAc), using polyvinylalcohol(PV-OH) as the protective colloid, have different viscosities depending on the degree of interaction between the aqueous solution of V-OAc and PV-OH. This interaction increased when the PV-OH samples, prepared by addition of various amounts of benzene to a methanolic solution of PV-OAc, had a higher content of residual acetyl groups with a more blocklike distribution. The mechanism of heterogeneous distribution of residual acetyl groups in PV-OH and effect of branching of PV-OH on the PV-OAc emulsion are also discussed.     

Effect of alkalies on suspension polymerization of vinyl acetate monomer,properties of poly(vinyl acetate) beads and poly(vinyl alcohols)

The use of weak alkalies such as sodium carbonate (Na₂CO₃), sodium bicarbonate (NaHCO₃) and their 1 : 1 molar mixture, and strong alkalies such as sodium hydroxide (NaOH) and sodium methoxide (NaOMe) as pH controllers in suspension polymerization of vinyl acetate monomer (VAM) has shown to have diverse effects on the yield of resulting poly(vinyl acetate) (PVAC) beads. Carbon dioxide as such or the carbonate seems to influence the yield. Further, these alkalies have a deep-seated effect not only on properties like viscosity, stereoregularity, glass transition temperature (T_g), and swelling coefficient (Q) of the PVAC beads but also on those of poly(vinyl alcohol) (PVA) obtained by alcoholysis of PVAC beads. The PVAC beads obtained using Na₂CO₃ showed higher viscosity, higher swelling coefficient (Q), and the PVA derived from these beads had higher Q, higher syndiotacticity/isotacticity ratio, and lower T_g.     

Effects of poly(vinyl acetate) suspending agents on suspension polymerisation of vinyl chloride monomer

Abstract

When partially hydrolysed poly(vinyl acetate) (PVAc) is used as a suspending agent in the suspension polymerisation of vinyl chloride monomer, it has significant effects on the morphology of the resulting poly(vinyl chloride) (PVC) particles. At the initial step of polymerisation, PVC molecules are grafted onto the molecules of the suspending agent forming a PVC–PVAc membrane. The properties of this membrane depend on the type of suspending agent, the polymerisation temperature, the mixing efficiency, and other factors. The morphology of the growing PVC particles and the properties of the PVC resin obtained depend in turn on the characteristics of the membrane. A model has been developed relating to the connection between the polymerisation conditions and the characteristics of the suspending agent on one hand, and on the PVC properties on the other hand. The model is based on an analysis of the characteristics of the PVC–PVAc membrane and their effect on PVC properties.     

乙酸乙烯精馏过程的模拟优化与工业应用

利用化工流程模拟软件对乙酸乙烯精馏过程进行模拟优化,通过模型对比得到了适用于计算该物系的物性方法;分析了各工艺参数对分离过程的影响,得到了最佳进料板位置、回流比和采出量。同时在原有塔体不变的情况下,利用高效导向筛板对乙酸乙烯精馏过程进行改造,并得到了工业应用。改造后工厂的运行结果表明,结合计算机优化的高效精馏技术能有效地提高产品纯度,降低原料和能量消耗,从而取得了很好的经济效益。     

Reactivity ratios and monomer partitioning in the microemulsion copolymerization of vinyl acetate and butyl acrylate

The true monomer reactivity ratios for the vinyl acetate/butyl acrylate system were determined with experimental data from the cumulative copolymer composition at low, intermediate, and high conversions and with the monomer partitioning among the aqueous, microemulsion droplet, and polymer particle phases taken into account. A mixture of sodium dodecyl sulfate and poly(ethylene oxide) (23) dodecyl ether (Brij‐35; 3 : 1 w/w) was used as a stabilizer. Potassium persulfate was used as an initiator. The true values of the monomer reactivity ratios were 0.028 ± 3.2 × 10^?3 for vinyl acetate and 6.219 ± 3.1 × 10^?1 for butyl acrylate, and these were in agreement with those reported in the literature for bulk copolymerizations but differed from values reported for other compartmentalized copolymerizations. Thus, these results indicate that the monomer partitioning and cumulative copolymer composition throughout the reaction have to be duly accounted for in the determination of monomer reactivity ratios in heterogeneous polymerizations. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis of vinyl phenyl acetate and an evaluation of vinyl chloride/vinyl phenyl acetate copolymers

The synthesis of vinyl phenyl acetate, by an ester interchange reaction between phenyl acetic acid and vinyl acetate and utilizing a catalyst, is described. Copolymerization with vinyl chloride, in a suspension system and using a peroxide catalyst, is described on a laboratory and pilot plant scale. Monomer/copolymer compositions, for an initial charge consisting of vinyl chloride/vinyl phenyl acetate (80/20 by weight) are presented over a range of conversions, as an indication of reactivity ratios. Discs, molded from unstabilized copolymers, show very good clarity and color stability, which improve with increased comonomer loading. Some retention of unpolymerized vinyl phenyl acetate monomer occurred, and some increase in softening points resulted following two reprecipitations from acetone into excess methanol. Compound from a 96/4 vinyl chloride/vinyl phenyl acetate copolymer has better color stability than does an equivalent vinyl chloride/vinylidene chloride copolymer compound. The enhanced color and heat stability of the copolymers is attributed to the aromatic character of the comonomer vinyl phenyl acetate.     

Thermodynamics of copolymerization of vinyl acetate and vinyl pivalate

Vinyl pivalate (VPi) and vinyl acetate (VAc) were copolymerized at low temperature using 2,2′-azobis(2,4-dimethylvaleronitrile) as an initiator. Copoly(VPi/VAc) was prepared in a broad range of chemical composition, from 0/10 to 10/0 of VPi/VAc molar feed ratio. A statistical treatment of the ¹H NMR peak intensities brought to the determination of the reactivity ratios of the comonomers. A thermodynamic study of the molecular dynamics simulation data led to the estimation of number-average sequence lengths of comonomers and Gibbs free energy change over VPi content. From this result, the retardation of copolymerization rate at about 5/5 composition was also explained. Enthalpies of -VAc-VPi^∗, -VPi-VAc^∗, and -VPi-VPi^∗ formation were calculated as −12.07, −5.57, and −18.33 kcal/mol, respectively.     

氯乙烯-醋酸乙烯酯共聚糊树脂中醋酸乙烯酯含量的测定

采用红外光谱法测定了氯乙烯-醋酸乙烯酯共聚糊树脂中醋酸乙烯酯的含量,并与热重法、化学分析法等分析方法进行了比较。指出氯乙烯-醋酸乙烯酯共聚糊树脂中醋酸乙烯酯含量的多种测定方法各有其特点,需要根据实际情况选用;红外光谱法快速、准确,可满足企业科研和生产所需。     

Kinetics of vinyl chloride and vinyl acetate emulsion polymerization

The kinetics of vinyl chloride and vinyl acetate emulsion polymerization are reexamined. The validity of Ugelstad's model for systems with high desorption rate is confirmed by simulating conversion histories for both systems at different initiator concentrations and particle numbers. On the basis of the model, it is shown that at ordinary initiation rates, termination reactions are unimportant with respect to molecular weight development in both systems, and as a consequence, molecular weight development is independent of number and size distribution of polymer particles and of initiator and emulsifier level. Based on this conclusion, it is shown that in accordance with experimental facts, the molecular weight distribution obtained in vinyl chloride emulsion polymerization is the most probable distribution, and it is concluded that the number of long-chain branch points per repetition unit is less than 2 × 10^?4 at high conversions. In vinyl acetate emulsion polymerization, an almost logarithmic normal distribution is obtained. The distribution is strongly broadened by branching reactions with the number of long-chain branch points increasing rapidly with monomer conversion. The increase of M_n with increasing conversion is due to terminal double-bond polymerization, while the increase in M_w is due mainly to transfer to polymer.