茂金属加合物技术首次工业试验

采用中国石油化工股份有限公司茂金属加合物技术制备茂金属加合物,并进行负载化研究;完成了茂金属加合物催化剂催化乙烯聚合以及乙烯与α-烯烃共聚合的淤浆、环管淤浆、气相流化床工艺的中试;在中试的基础上,茂金属加合物催化剂于60kt／a气相流化床聚乙烯生产装置上成功进行了工业试验。探索了茂金属催化剂与Ziegler催化剂的切换技术,研究了催化剂组成和聚合工艺参数对聚乙烯树脂性能的影响。用所得茂金属聚乙烯树脂加工成的薄膜具有较好的透明性,并表现出了优异的落镖冲击强度和撕裂强度。     

Spheripol工艺丙烯聚合质量模型

针对Spheripol工艺,根据Z-N催化剂聚合机理,对不同牌号聚丙烯产品(包括均聚聚丙烯、无规共聚聚丙烯和抗冲聚丙烯)分别建立了熔融指数和乙烯质量分率的预测模型.并应用实际生产数据,对模型进行优化拟合,得到了模型参数.结果表明,熔融指数和乙烯质量分率预测模型的计算值与分析值之间的平均相对误差分别为3.86%和13.5%,模型可以较为准确地预测树脂质量,对聚合产品质量的软测量及牌号切换的研究有很大帮助.     

茂金属加合物技术的工业应用试验

根据中国石化集团公司开发的茂金属加合物专利技术,进行了活性组分负载化研究,完成了茂金属加合物催化剂催化乙烯以及乙烯与α-烯烃共聚的淤浆、环管淤浆、气相流化床工艺的中试试验.在中试的基础上进行了茂金属加合物催化剂气相流化床聚乙烯工艺的工业应用试验,探索了茂金属催化剂与Ziegler催化剂之间的切换技术,开发了催化剂结构和配方以及聚合工艺参数对聚乙烯树脂牌号的调控技术.得到百吨级薄膜牌号的茂金属聚乙烯树脂,并对工业应用试验产品进行了加工研究.     

乙烯气相聚合工艺研究与技术进展

聚乙烯已成为全球产量最大、用途最广的合成材料。由于生产流程短和设备投资低的优势,流化床气相聚合工艺是聚乙烯的主要生产路线,得到了广泛而深入的研究和开发。本文综述了国内外乙烯气相聚合工艺技术的研发历程,特别是中国在气相法聚乙烯技术方面做出的重要贡献。总结了气相聚合工艺的七种操作模式,即干法气相聚合、超干法气相聚合、气相冷凝聚合、气相超冷凝聚合、气液固云雾聚合、露点聚合以及交替交变聚合。分析了各操作模式所涉及的关键科学问题和工程技术解决方案,例如反应器时空产率模型、冷凝态聚合操作点优化、溶剂的作用、黏性流化颗粒熔融温度预测、流化质量监控与声发射、多流型复合以及一器多用等,并重点介绍了气-液-固云雾聚合流化床反应器中颗粒团聚、气泡运动的新特征,云雾聚合流化床运行的新稳定机制,以及实现聚合物产品结构调控的新途径——乙烯的露点聚合和交替交变聚合技术。指出聚合反应工程学科正从聚焦传统的过程强化,发展到过程强化与产品多样化相互兼顾的变化趋势。     

影响LDPE树脂熔融指数的因素及调整方法

根据高压聚乙烯（LDPE）树脂的生产机理,分析在生产过程中影响LDPE树脂熔融指数的因素,并结合分子量调节剂在生产过程中对LDPE树脂熔融指数的调节原理,以丙醛为例,阐述了生产过程中LDPE树脂熔融指数的调整方法。     

浅析影响聚乙烯单耗的因素

分析了气相流化床聚乙烯生产过程中影响聚乙烯单耗的因素，提出了通过改变有关工艺操作条件以降低乙烯单耗的措施。     

气相法乙烯高效催化聚合和共聚合的研究(Ⅱ)新型高效催化剂中各组分对聚合反应的影响

本文研究以MgCl_2-SiO_2为载体的钛系乙烯气相聚合高效催化剂中各组分及配制条件对乙烯浆液聚合及气相乙烯均聚合和共聚合的影响。研究催化剂组分对聚合反应的控制规律。详细考察了气相催化剂重要组分SiO_2、锌化合物、醚、格氏试剂等组分对聚合及分子量控制的影响。阐述了催化剂组分的重要作用.在1.275MPa反应压力下。乙烯气相均聚合催化效率290～470kgPE/gTi,0.883MPa反应压力下,乙烯—1-丁烯共聚合催化效率210～310kgPE/gTi,测定了均聚物和共聚物的有关性能如分子量、熔体指数、熔点、结晶度、密度等.     

气相法高抗冲产品的开发

抚顺石化公司烯烃厂30万t/a线聚丙烯气相法装置开发了一种高抗冲产品。测试结果表明:产品拥有优异的低温抗冲性能、高熔融指数和高抗冲强度、可控流变学、领先市场的高抗冲/刚度的平衡。本产品生产难度较高,第一反应器树脂为高熔指的均聚物,熔融指数为69,二甲苯可溶物1.6%,产品的最终熔融指数35。本产品以乙烯为共聚单体,橡胶含量为17%,橡胶中的乙烯含量42%,总乙烯含量7.1%。     

茂金属聚乙烯催化剂工业应用研究

北京化工研究院合成了50余种新型茂金属化合物,在茂金属催化剂均相乙烯聚合的系统研究基础上,深入研究了载体茂金属催化剂的制备方法和制备条件等因素与载体催化剂性能的关系,研制出性能优异的载体茂金属催化剂。采用载体茂金属催化剂进行了浆液法和气相法乙烯聚合中试研究,还进行了茂金属聚乙烯树脂的加工应用研究,树脂性能与国外同类产品相当。     

带路径约束的聚烯烃牌号切换操作优化方法

产品多样化需求使得聚烯烃生产过程中经常需要进行牌号切换操作。以往关于牌号切换优化的研究大多只关心切换过程结束后聚合物质量指标是否达到目标牌号值,对过渡过程中质量指标及状态变量的波动情况缺少关注,而过程的波动会影响到最终产物的质量性质和操作平稳性。为此,本文以聚乙烯气相流化床反应器为对象,通过在牌号切换优化命题中加入关于熔融指数等的路径约束,防止过渡过程中的状态变量剧烈波动影响聚合物树脂质量。为求解此类带路径约束的动态优化问题,对常规的控制变量参数化方法进行了改进,通过求解微分代数方程(DAE方程)将路径约束转化为控制变量约束。仿真结果表明,加入路径约束可以有效避免牌号切换中变量的剧烈波动,增强过程平稳性。     

Drying of solids in vacuum fluidized bed

A drying process in a fluidized bed under vacuum conditions is experimentally and theoretically studied. A fluidized bed operating in reduced pressure presents a possibility for a better quality of production, with safer process conditions. A mathematical model is developed for the reduced‐pressure drying process in a fluidized bed. Some parameters were analyzed by comparing experimental results with model predictions. The predictions from the model agreed quite closely with the experimental data. The results showed that a decrease in pressure reduces the interparticular resistance. A good agreement was also found applying the model to data, at atmospheric pressure, from other authors.     

DYNAMIC OPTIMAL CONTROL OF BATCH CRYSTALLIZATION PROCESSES

The estimation of the solids circulation rate in a dual fluidized bed gasifier is essential as it influences the gasification performance. However, such estimation requires experimental data input, which is often not available during the design phase of a fluidized bed. In this work, a correlation was developed based on literature and experimental data (from a cold model dual fluidized bed gasifier) to estimate the solids circulation rate at high solids-to-gas density ratios. The correlation was then validated with literature data from a dual fluidized bed steam gasifier under hot conditions, yielding maximum discrepancies of ±25%.     

气固流化床中声发生机理及在工业装置中的应用

利用声测量技术,结合频谱分析,建立了颗粒碰撞的声波频率模型,可定量描述声波主频随颗粒粒径、弹性模量和密度的变化规律.通过改变流化颗粒的粒径、弹性模量参数和密度,发现声波主频与频率模型计算值之间的最大偏差为8.3%,说明声波主频可以代表颗粒在壁面的碰撞频率.讨论了热态和冷态条件下声波主频之间变化规律,通过对弹性模量参数的校正,声测量技术可以用于预测工业装置中物料的平均粒径变化,并将该模型应用于线性低密度聚乙烯、高密度聚乙烯和双峰聚乙烯工业生产装置中的平均粒径测量,发现与传统的取样筛分方法所得测量结果十分接近.同时,发现当系统产生聚合物颗粒结块时,声波主频将急剧降低,声波频谱的能量分布将明显集中增大,这可作为判断流化床稳定运行的一个判据.     

Experimental and computational study of the bed dynamics of semi‐cylindrical gas–solid fluidized bed

With computational fluid dynamics (CFD) it is possible to get a detailed view of the flow behaviour of the fluidized beds. A profound and fundamental understanding of bed dynamics such as bed pressure drop, bed expansion ratio, bed fluctuation ratio, and minimum fluidization velocity of homogeneous binary mixtures has been made in a semi‐cylindrical fluidized column for gas–solid systems, resulting in a predictive model for fluidized beds. In the present work attempt has been made to study the effect of different system parameters (viz., size and density of the bed materials and initial static bed height) on the bed dynamics. The correlations for the bed expansion and bed fluctuations have been developed on the basis of dimensional analysis using these system parameters. Computational study has also been carried out using a commercial CFD package Fluent (Fluent, Inc.). A multifluid Eulerian model incorporating the kinetic theory for solid particles was applied in order to simulate the gas–solid flow. CFD simulated bed pressure drop has been compared with the experimental bed pressure drops under different conditions for which the results show good agreements.     

Batch Drying Kinetics in a Two-Zone Bubbling Fluidized Bed

This article deals with investigation and modeling of batch drying process of solids in fluidized bed apparatus. There has been used model of fluidized bed drying, which consists two zones: emulsion zone and bubbling zone with taking into consideration the presence of solid particles in the bubbles. The results of theoretical expectations that arise from simulation calculations have been verified with experimental data obtained with the use of fluidized bed dryer 0.225 m in diameter. A drying process of silica gel, sand, and ammonium sulfate has been tested. To verify the model, the concept of a generalized drying curve has also been employed.     

A population model of quartzite particles in a lab-scale fluidized bed due to the thermal fragmentation

A population model has been developed to simulate the size distribution of quartzite particles in a lab-scale fluidized bed. While quartzite particles as a kind of bed materials in the differential density circulating fluidized bed were loaded into the high temperature bed, the size distribution of quartzite particles would be changed due to the thermal fragmentation, which could significantly influence fluidization characteristics and heat transfer.With the purpose of comprehending the population of quartzite particles after thermal fragmentation, a fragmentation experiment of quartzite particles has been carried out in a lab-scale circulating fluidized bed. The results show that the fragmentation of particles mainly occurred on particles surface. Based on this experimental phenomenon, a mathematical population model was established to estimate the particle size distribution. The predicted value from the population model is close to the experimental value.     

Numerical simulation of horizontal jet penetration in a three-dimensional fluidized bed

The introduction of reactant gas as a jet into a fluidized bed chemical reactor is often encountered in various industrial applications. Understanding the hydrodynamics of the gas and solid flow resulting from the gas jet can have considerable significance in improving the reactor design and process optimization. In this work, a three-dimensional numerical simulation of a single horizontal gas jet into a cylindrical gas-solid fluidized bed of laboratory scale is conducted. A scaled drag model is proposed and implemented into the simulation of a fluidized bed of FCC particles. The gas and particles flow in the fluidized bed is investigated by analyzing the transient simulation results. The jet penetration lengths of different jet velocities have been obtained and compared with published experimental data as well as with predictions of empirical correlations. The predictions by several empirical correlations are discussed. A good agreement between the numerical simulation and experimental results has been achieved.     

有内构件工业湍动流化床反应器的模型化——反应器模型的开发

引　言湍动流化床反应器因具有良好的气固接触氛围和传热性能、高固含率以及有限的轴向返混等优点 ,在工业生产中被普遍采用 ,但对于湍动流化床的模型化工作和反应器性能的报道较少[1] .Thompson等在 1999年提出的一般性鼓泡 /湍动流化床模型最有特色 ,该模型实现了从鼓泡区域到湍动区域的平滑过渡 ,与其他模型相比模型预测值与Sun于 1991年报道的实验数据能更好地吻合[2 ] .但是对于这些模型都缺少更多的工业数据去检验它们应用于工业模拟时的可靠性[1,3] ,对于具有垂直内构件的工业湍动流化床的模型化文献中未见报道 .秦霁光等人[4 ] 提…     

CFD modelling of liquid fluidized beds in slugging mode

Computational Fluid Dynamics (CFD) modelling has been used to simulate a liquid fluidized bed of lead shot in slugging mode. Simulations have been performed using a commercial code, CFX4.4. The kinetic model for granular flow, which is already available in CFX, has been used during this study. 2D time-dependent simulations have been carried out at different water velocities. Simulated aspects of fluidization such as voidage profiles, slug formation, pressure drop and pressure fluctuations have been analysed. The fluid-bed pressure drop was found to be greater than the theoretical one at all velocities, in agreement with experimental observations reported for fully slugging fluidized beds. Power spectral density analysis of the pressure signal was used to investigate the development of the flow pattern and the structure of the fluid-bed with increasing fluidizing velocity. A comparison between experimental and simulated results is also reported.