关于Unipol气相法聚乙烯工艺的几点思考

针对Unipol工艺而言,气相流化床反应技术与催化剂技术是其最核心的技术。在经过了长期的发展与创新之后,Unipol工艺通常都是将催化剂技术的发展与工艺的发展紧密联系,并以此来确保技术能够实现工业化应用。针对Unipol气相法聚乙烯工艺进行简单分析,以供参考。     

气相法聚乙烯中试装置流化床反应器的改进

运用流化力学的观点对流化床反应器进行分析和研究,并对影响流化状态的设备部件进行改进,解决了中试装置小反应器的运行问题。     

Unipol气相法聚乙烯技术进展与启示

综述了Unipol催化剂技术中典型的4类聚乙烯(PE)催化剂的特性,介绍了气相法PE装置扩能技术的进展。指出国内PE企业应加快催化剂的国产化进程,装置扩能改造增加生产能力,产品结构定位与调整要适时而变,从而缩短与世界先进水平的差距。     

气相法聚乙烯工艺静电产生及控制

气相法聚乙烯装置运行中,静电造成的反应器内结片是导致反应器停车的最主要原因.通过分析树脂颗粒性质、流化床操作参数、系统内杂质水平、原辅材料输送带电等影响静电产生的主要因素,围绕降低流化床主体电荷量的途径,结合理论和实际生产经验,提出反应器器壁沉积光滑涂层、开车期间彻底置换反应器并进行床层预处理、进入冷凝态运行、控制系统内杂质水平、控制反应器运行参数稳定、外加介质抑制静电等控制手段,减少了静电造成的反应器内结片、结块,有利于装置的长周期运行.     

气相法聚乙烯反应器结块原因及预防措施

分析了气相法聚乙烯装置中反应器结块的各种原因,针对反应器扩大段处的结块、反应器内静电引起的结块、因催化剂活性太高导致的爆米花料以及反应器分布板下部的结块等提出了有效的预防措施。以确保气相法聚乙烯装置能够安全、稳定、长周期运行。     

气相法聚乙烯中试流化床操作规律的研究

通过冷模实验确定气相法聚乙烯中试装置流化床流化特性的一些基本参数,由床层压降与气体流速的关系确定流化床操作的起始流化速度和气体流速,由气体流速对床层膨胀比的影响得出床层的初始装料高度。     

Unipol气相聚乙烯反应器结块问题研究进展

对Unipol工艺气相流化床聚乙烯反应器生产运行过程中生成的块料形态和特征进行了分类与总结;对反应器结块现象、结块原因、结块部位及防结块措施研究进展进行了归纳。结果表明：结块的原因为静电因素、反应器设计因素、工艺条件控制因素和物料性质因素。实际生产运行过程中,严格落实与各种影响因素相对应的防结块措施,能从一定程度上缓解结块现象,但不能彻底消除结块。建议从控制原料质量、优化防结块控制条件和深入研究聚合反应动力学三个方面同时着手,探究结块本质原因和开发抑制结块技术。     

Unipol气相法聚乙烯装置风险分析与控制

本文从Unipol气相法工艺聚乙烯装置原料风险、职业卫生风险、人员风险和某聚乙烯装置工艺操作过程安全事件,对装置中存在的风险因素进行分析,并提出对策。     

气相流化床法聚乙烯工艺技术比较

通过对引进气相流化床法LL/HD聚乙烯工艺技术比较,提出适合我国国情的工艺技术路线。     

Pressure drop through multiorifice gas distributors in fluidized bed columns

Good grid design is essential for the satisfactory performance of large gas fluidized beds and requires the accurate prediction of the grid pressure drop. Experiments conducted with various perforated plate distributors in a 0.6 m I.D. fluidized bed column showed that the presence of fluidized solids could increase the grid pressure drop by more than 100%. This increase was around 25% for a grid pressure drop to bed pressure drop ratio of 0.4. It was greatly affected by the bed height. An investigation of various possible causes for this increase demonstrated that it is primarily caused by the backflow of fluidized solids into the grid holes under the influence of waves at the bed surface.     

Two-phase modeling of a gas phase polyethylene fluidized bed reactor

A two-phase model is proposed for describing the behavior of a fluidized bed reactor used for polyethylene production. In the proposed model, the bed is divided into several sequential sections where flow of the gas is considered to be plug flow through the bubbles and perfectly mixed through the emulsion phase. Polymerization reactions occur not only in the emulsion phase but also in the bubble phase. Voidages of the emulsion and bubble phases are estimated from the dynamic two phase structure hydrodynamic model. The kinetic model employed in this study is based on the moment equations. The hydrodynamic and kinetic models are combined in order to develop a comprehensive model for gas-phase polyethylene reactor. The results of the model are compared with the experimental data in terms of molecular weight distribution and polydispersity of the produced polymer. A good agreement is observed between the model predictions and actual plant data. It has been shown that about 20% of the polymer is produced inside the bubble phase and as such cannot be neglected in modeling such reactors.     

土工膜专用气相法聚乙烯DQTG3912的结构与性能

利用旋转流变仪、核磁共振仪等研究了采用Unipol气相工艺生产的聚乙烯DQTG3912的结构与性能,并与同类产品进行了对比.结果表明:DQTG3912为乙烯与1-己烯共聚的中密度聚乙烯,相对分子质量较高,相对分子质量分布较宽,并有较多的长支链;DQTG3912的加工性能优异,可生产双糙面土工膜,制品各项性能符合GB/T...     

气相法mPE的性能剖析

茂金属聚乙烯（mPE)具有优越的力学性能和光学性能,这与茂金属催化剂的催化性能及其聚合物特殊的链结构形式密切相关。对国内开发的mPE进行了结构表征,结果表明：mPE薄膜的力学性能和光学性能明显优于线型低密度聚乙烯产品,其耐穿刺性能明显好于其他聚乙烯产品。     

错流旋转填料床气相压降特性

旋转填料床的气相压降是旋转填料床应用和设计的一项重要指标。在气液两相错流流动条件下,利用空气-水系统对错流旋转填充床的气相压降进行分段模型化和实验研究。按照错流旋转填料床气体流动的路径将气相压降分为进口压降、填料层压降、集气段旋转动能转化压降和出气段压降。推导出压降与操作工况的关联式,其计算值与实测值吻合较好。实验表明错流旋转填料床的气相总压降与气体流量、旋转床转速、液体流量有关。在高转速和小气量的条件下,气相压降随气量增大先下降后上升;其他情况随气量增大而上升。错流旋转填料床气相压降随转速上升而下降,在小气量情况下转速对气相压降有明显影响。气相压降随进液量的增大而增大,当旋转填料床在低转速时进液量对气相压降有明显影响。     

Unipol气相法聚烯烃液体催化剂技术进展

介绍了Unipol气相法聚烯烃工艺液体催化剂的成分、加入反应器的方式和喷嘴结构及控制催化剂液滴尺寸方法等方面的最新进展情况。     

气相聚乙烯BCG催化剂的工业应用

介绍了BCG催化剂在Unipol气相法聚乙烯装置上的工业应用。工业试用表明,BCG催化剂的流动性能、氢调和共聚合性能良好,活性较高,综合性能优良;树脂性能测试表明,用BCG催化剂生产的薄膜级线型低密度聚乙烯树脂的加工性能良好,产品物理、机械性能达到优级品标准。     

A comparative study of a fluidised bed reactor and a gas lift loop reactor for the IBE process. Part II: Hydrodynamics and reactor modelling

A fluidised bed reactor with liquid recycle (FBR) and an external loop gas lift reactor (GLR) were designed for the production of isopropanol—butanol mixtures by immobilised Clostridium spp. and scaled down to laboratory scale (part I). Hydrodynamic models were set up for the two laboratory scale reactors. Liquid mixing in the 10 dm³ FBR was described by 10 tanks in series. Fluidisation velocities, bed expansions and axial dispersion coefficients agreed well with literature data. Liquid mixing in the 15 dm³ GLR was described by 100 tanks in series. The gas hold-up and circulation velocity were found to decrease with increasing hold-up of solids, in accordance with literature indications. No influence of the hold-up of solids on the axial dispersion coefficient was determined. An integrated reactor model was set up for both reactors, using the hydrodynamic and kinetic model. Actual fermentation data are presented and compared with model predictions in part III of this study; this part will also include a comparison of reactor performances and scale up aspects.