乙烯精馏塔模拟分析与运用

乙烯精馏塔分离出产品乙烯,该塔控制的好坏直接影响乙烯产品质量和回收率,利用Aspen Plus模拟软件对乙烯装置的乙烯精馏塔进行了分析,确定了乙烯精馏塔进料塔板、灵敏板位置,并通过灵敏度分析得到各工艺参数对乙烯产品规格的影响.通过模拟指导,乙烯精馏塔增加灵敏板温度控制,塔釜液位控制,优化乙烯精馏塔压与回流量的控制,实现...     

投用先进控制对乙烯精馏塔操作的影响

乙烯精馏塔直接分离出产品乙烯,该塔控制的好坏直接影响乙烯的产品质量和收率。主要介绍了乙烯精馏塔流程,投用先进控制对乙烯精馏塔操作的影响。先进控制系统的投用不仅确保了乙烯精馏塔侧线最大限度地采出合格的乙烯产品,而且保证了塔釜出料中损失的乙烯浓度最小,达到了增加乙烯装置产量、降低能源消耗,提高装置的总体经济效益之目的。     

GK6技术在国内乙烯裂解炉改造中的应用(上)

通过对国内乙烯装置现状和乙烯裂解炉改造必要性的分析,提出了国内早期各类乙烯裂解炉的改造方案,并对改造后的效果进行了说明,印证了乙烯裂解炉改造的必要性。     

GK6技术在国内乙烯裂解炉改造中的应用(下)

通过对国内乙烯装置现状和乙烯裂解炉改造必要性的分析,提出了国内早期各类乙烯裂解炉的改造方案,并对改造后的效果进行了说明,印证了乙烯裂解炉改造的必要性。     

关于优化乙烯裂解原料的探讨

对我国乙烯原料构成变化进行了论述,提出了当今乙烯原料的多样化、优质化、轻质化的发展趋势;详述了裂解原料对乙烯装置经济性的影响,吉林石化公司在乙烯原料优化方面所做的主要工作及取得的显著经济效益;并提出了乙烯原料优化方案。     

甲烷制乙烯技术研究进展

为了改变乙烯生产原料过分依赖于石油资源的状况,各国积极开展了对原油、生物资源、煤和甲烷等原料制乙烯新工艺的研究开发,乙烯生产原料多样化的趋势日渐明朗。对甲烷直接制乙烯技术——甲烷氧化偶联制乙烯和甲烷无氧催化制乙烯技术进行综述,并对其关键技术进行分析。     

节能技术在乙烯存储系统中的比较和应用

乙烯是石油化学工业中最重要的基础有机原料之一。通常乙烯采用低温常压存储,因此存储的能耗对乙烯储运的运行成本影响较大。本文通过对低温乙烯存储系统中不同的工艺能耗进行了分析和比较,发现节能技术的应用能回收乙烯冷量,有效的降低乙烯存储的能耗,为低温乙烯存储系统中的节能技术的应用提供参考。     

国外乙烯装置扩能改造典型分析

对国外90年代中期3套乙烯装置扩能改造进行了详细了介绍和典型分析,所选的3套乙烯装置基本符合国内正在进行和将要进行的乙烯改造规模,其经验对;国内现有乙烯装置的第二轮改造具有直接的现实参考价值。在此基础上还提出了国内乙烯装置扩能改造的建议。     

乙烯法合成醋酸乙烯反应尾气的回收技术探讨

通过设置乙烯回收塔,对醋酸乙烯合成反应尾气进行综合回收和利用,提高了原材料的利用率,降低了原材料和能源的消耗,且极大地减少尾气排放对环境的污染。对中压法聚醋酸乙烯-乙烯共聚乳液生产中排放的乙烯尾气进行回收处理,可降低循环乙烯中杂质的含量,提高系统乙烯纯度。     

乙烯装置无乙烯开车方案浅析

介绍了某乙烯装置无乙烯(有丙烯)的开工过程。通过优化开工过程中的物料流程,尽快完成乙烯制冷压缩机和乙烯精馏塔系统的充压充液工作,在没有乙烯库存的情况下最大限度的减少开工时间,实现了乙烯装置无乙烯开工的一次成功。结合现场实际情况及其它乙烯装置的开工经验,提出了完整的开车方案。并针对具体的操作条件,分析了开工阶段可能出现的问题,对实施方案进行了进一步细化和完善。     

A comparative study of tetraisobutyldialuminoxane and methylaluminoxane as cocatalysts for Cp2ZrCl2 catalyzed ethylene polymerization

Summary The effect of [A1]/[Zr] mol ratio and temperature on the cocatalytic effects of tetraisobutyldialuminoxane (TIBDAO) and methylaluminoxane (MAO) for ethylene polymerization using Cp₂ZrCl₂ catalyst were studied. The decay type kinetic profile was observed for both TIBDAO and MAO cocatalyzed ethylene polymerizations. Catalytic activity and rate of polymerization were found to be low for TIBDAO cocatalyzed ethylene polymerization when compared to MAO cocatalyzed ethylene polymerization. The differences in catalytic activity and rate of polymerization for ethylene polymerization catalyzed by Cp₂ZrCl₂-TIBDAO and Cp₂ZrCl₂-MAO were discussed with respect to the structures of MAO and TIBDAO. An active species for Cp₂ZrCl₂-MAO and Cp₂ZrCl₂-TIBDAO catalyzed ethylene polymerizations was also discussed. The polyethylene was characterized by intrinsic viscosity measurements.     

Influence of steric length in electrosteric surfactants on emulsion polymerization

Four PPG Avanel Series S surfactants (sodium alkyl polyether sulfonates) with varying ethylene oxide content (n = 3, 7, 9, and 15) were used to investigate the influence of the steric length in this type of electrosteric stabilizers on emulsion polymerization. The polymerization studies employing potassium persulfate as an initiator with styrene, methyl methacrylate, and vinyl acetate monomers showed no apparent change in particle size, number of particles, and polymerization rate with the changing steric length of the surfactant. Steric influences were observed in the redox-initiated systems of styrene, butyl acrylate, and methyl methacrylate. Increasing the ethylene oxide unit content from three to nine units decreased the rate of polymerization, the particle size and number in the polystyrene latexes. Polymerizations with the acrylates displayed the same trend except that the polymerization rate reached a minimum value at nine ethylene oxide units and increased when the surfactant containing 15 ethylene oxide units was used.     

气相法聚乙烯高效催化剂的进展

综述了国内外气相法聚乙烯高效催化剂研究进展概况,以及各种新型高效催化剂制备技术和性能,并对开发我国新型高效推化剂提出了看法。     

Polymerization of ethylene oxide by the activated monomer mechanism

The Polymerization of ethylene oxide catalysed by protonic acids and proceeding via the activated monomer mechanism differs from the polymerizations of substituted epoxides like propylene oxide and epichlorohydrin. The kinetics of ethylene oxide polymerization were investigated and compared with the kinetics of model reactions, namely addition of oligomers of ethylene oxide to ethylene oxide. The mechanism of polymerization involves, besides the addition of monomer to the terminal hydroxyl groups, the addition to the polymer ether groups. This reaction does not take place for substituted oxiranes, most probably because of steric hindrance.     

Heterogeneous Catalytic Polymerization of Ethylene in Microtubular Reactor Systems

The feasibility of using a microtubular reactor for heterogeneous polymerization of ethylene was investigated experimentally. Chemically inert polymer tubing of 800–2300 μm in inner diameter was fabricated and used as a polymerization reactor. Nonporous silica nanoparticles with a diameter of 400 nm were synthesized and used as support for the high‐activity rac‐ethylene(indenyl)₂ZrCl₂ catalyst with methylaluminoxane as cocatalyst and toluene as diluent. Large‐diameter microtubular reactors were also successfully used to conduct heterogeneous polymerization of ethylene in continuous reaction operations. High initial catalyst activity was obtained and the overall polymerization activity per volume or reactor length was quite high. No particle fragmentation occurred and the polymer particles were covered with small subgrains or nanofibrils with a diameter of 30 nm.     

Modeling of ethylene polymerization with difunctional initiators in tubular reactors

The severe thermodynamic conditions of the high‐pressure ethylene polymerization process hinder ethylene from going to full conversion. One remedy to improve the monomer conversion is to make effective use of difunctional peroxides. Multifunctional peroxides can accelerate the polymerization rate, produce branching, and modify the rheological properties of molten polymers. This article proposes a kinetic model based on a postulated reaction mechanism for ethylene polymerization initiated by difunctional initiators in a high‐pressure tubular reactor. Three peroxides suitable for ethylene polymerization were compared for their effectiveness. Compared to dioctanoyl peroxide, the two difunctional peroxides considered performed much better for the higher temperature regions of the reactor and gave ethylene conversions nearly twice as high for only half of the initial amount of dioctanoyl. They also generated low‐density polyethylene polymer with a broader molecular weight distribution and longer chain branching. These two important polymer characteristics can influence the end‐product rheological properties. Injecting fresh ethylene at different points along the reactor improved the conversion and produced more branched polymer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

串级催化聚合制备线性低密度聚乙烯/聚烯烃热塑性弹性体

通过齐聚催化剂和共聚催化剂的有机结合和相互协同,可实现以乙烯为唯一单体的串级催化聚合,合成乙烯与α-烯烃共聚的线性低密度聚乙烯和聚烯烃热塑性弹性体,但开发高选择性、高共聚能力、适合高温聚合的串级聚合催化体系仍极具挑战。本文围绕不同类型的乙烯齐聚/聚合反应,评述了乙烯二聚、三聚、四聚及聚烯烃大单体合成技术及其相应的串级催化聚合的研究进展。迄今,大部分串级催化聚合是在较低的聚合反应温度下进行的,有限的串级催化体系适合高温聚合;乙烯二聚和三聚串级催化聚合可合成短支链较均一的乙烯与α-烯烃共聚物,但在乙烯四聚串级催化聚合中1-辛烯的选择性亟待提高;此外,通过聚烯烃大单体的串级催化聚合,可为具有特殊链拓扑结构的高性能聚烯烃热塑性弹性体的开发开拓新途径。     

亚乙基苊镍催化剂催化乙烯溶液聚合制备超支化聚乙烯

以一种亚乙基苊(α-二亚胺)镍配合物为主催化剂,研究了温度、压力、助催化剂及其用量等对乙烯溶液聚合制备超支化聚乙烯(HBPE)的影响,并对HBPE的结构与性能进行分析。结果表明:随着温度或压力的升高,催化剂活性均呈现先升高后下降的趋势;HBPE的相对分子质量随温度的升高而下降,而支化度与温度呈正比,与压力呈反比;二氯乙基铝、三乙基铝和甲基铝氧烷均可作为该催化剂的助催化剂,使用二氯乙基铝时的催化剂活性最高,所制HBPE的支化度也最高。     

Cs-对称胺芴二甲基钛络合物催化的乙烯活性聚合

研究了对丙烯的高速间规活性聚合有效的Cs-对称胺芴二甲基钛络合物-干燥修饰甲基铝氧烷(dMMAO)催化剂体系对乙烯的聚合行为的影响。结果表明:乙烯常压聚合表现出稳定的聚合速率,聚合活性达到282 kg-PE/(mol-Ti·h);利用间歇聚合法进行乙烯聚合的单体转化率均达到99%以上,说明催化体系无失活现象,但得到的聚乙烯在135℃下不溶于GPC溶剂邻二氯苯中;采用先加入定量丙烯单体聚合完全结束后,再加入定量乙烯单体进行聚合的方法合成了sPP-b-PE嵌段共聚物。嵌段共聚合的结果说明乙烯聚合是以活性聚合的方式进行的。利用该催化体系还合成了丙烯-乙烯丙烯双嵌段共聚物(sPP-b-E/P)以及丙烯-乙烯丙烯-丙烯(sPP-b-E/P-b-sPP)三嵌段共聚物。     

Influence of the nature of monomers on the activity of supported titanium catalysts in the α-olefin polymerization

Summary Ethylene and propylene co-polymerization and sequential polymerization with high activity supported titanium catalysts were studied. Specific rate of homopolymerization and copolymerization constants for ethylene and propylene were determined by using the derived values of the solubility constants for monomers in nascent polymers. The reason of the increased rate of co-polymerization upon enriching the monomers mixture with propylene, the effect of activation of ethylene polymerization upon preliminary polymerization of propylene may be in the increasing number of active sites due to enlarged content of amorphous phase in the nascent polymer product.