五釜工艺聚酯工业装置的稳态模拟

针对大型连续PTA直接酯化法PET工艺过程装置,以Aspen Plus和Polymers Plus为模型开发工具,建立了以反应和传质过程机理为基础的稳态模型。结果表明:该模型中包括了酯化反应、缩聚反应、二甘醇生成反应、链降解反应和乙醛生成等主副反应,且考虑了端羧基对酯化反应的自催化效应;更重要的是模型考虑了酯化阶段PTA在酯化反应器中的溶解过程和终缩聚阶段小分子的脱挥,并建立了小分子脱挥的传质系数与缩聚反应器内聚合度、黏度、温度和搅拌器转速等的关联;在此模型基础上模拟研究了第一酯化反应操作温度对各反应器出口指标的影响,指出酯化段的酯化率有一个适宜的控制范围。     

PET固相缩聚反应器动态模型

PET固相缩聚过程涉及反应固体颗粒和反应器床层两个空间尺度的传质,是一个复杂的多维多相对象。以反应过程控制为目标,在已有的反应动力学模型基础上,同时考虑可逆化学反应和小分子产物内外扩散两个控制因素,并借用固定床拟均相模型的建模思想,将小分子产物在颗粒内外扩散形成的浓度梯度用一个有效系数来表示,从而建立了简化的PET固相缩聚反应器一维动态模型。在相关文献的实验条件下求解分布参数模型的数值解,并进行启动过程仿真和过程动态分析,计算反应器出口质量指标,与文献曲线和数据对照,验证了模型的正确性。     

有机蒙脱土对PET后缩聚反应的影响

实验研究了有机蒙脱土对PET后缩聚反应过程的影响。结果表明有机蒙脱土对PET缩聚反应的前期有加速作用，但由于对气液传质过程有阻碍作用，导致了PET后缩聚反应的速度下降。蒙脱土的存在还使缩聚过程中二甘醇(DEG)基团及端羧基基团浓度上升。根据缩聚反应机理建立了PET后缩聚过程的数学模型，并依据实验结果拟合出缩聚反应动力学参数及气液传质系数。模型计算结果能较好地反映PET后缩聚过程中特性粘数的变化及DEG基团的生成规律，但对端羧基浓度的变化存在较大的偏差。     

PET缩聚过程反应与传质Ⅰ反应动力学研究

聚对苯二甲酸乙二醇酯缩聚过程是反应－传质耦合过程,本文利用静止膜实验在排除传质影响情况下研究了ＰＥＴ缩聚过程反应规律,建立了链增长,链降解反应动力学模型,并利用可逆反应极限的概念确定了小分子界面浓度。     

聚酯（PET）反应过程研究：Ⅶ后缩聚反应过程研究和数学模拟

对聚酯的后缩聚反应过程进行了分析，把该过程分解为反应动力学和反应器内各种传质；对后缩聚反应进行了实验研究。建立了适用于工业装置的后缩聚反应过程的数学模型     

PET/PEG共聚酯连续熔融终缩聚过程两相稳态模型分析

针对高性能共聚酯PET/PEG缩聚过程,建立了圆盘反应器中连续熔融聚合两相稳态模型,模拟分析了缩聚反应温度、压力、停留时间以及传质系数对气相组成、共聚酯数均分子量、端羧基浓度以及副产物二甘醇和水浓度的影响。结果表明：挥发组分主要在反应器的前半部分产生,在z > 0.4后气相挥发总量已经很小;乙二醇占气相组成的比例极高,约为90%,而二甘醇的含量极低,只为0.5%左右;随反应器温度、真空度、停留时间、传质系数的增加,共聚酯产物的分子量增大,当传质系数大于0.1 s^-1后,反应器出口的共聚酯分子量几乎不再变化,此时已不受传质控制,最终产物的分子量约26000。     

聚酯缩聚工艺及反应器优化分析

根据聚酯缩聚热模、冷模试验数据建立的关联式计算 ,剖析了聚酯的缩聚工艺及几种不同结构型式的反应器 (槽式反应器、圆盘反应器、笼式反应器 )结构及其反应特点。强调聚酯缩聚过程速率控制步骤的判定对聚酯缩聚工艺和反应器设计的优化起关键作用。     

基于ISR-UKF的PET固相缩聚过程参数和状态估计

连续式PET固相缩聚移动床反应器具有显著的分布参数特性,由于建模简化或过程时变等原因使得所建模型参数不精确,导致反应器状态的估计失真。首先采用正交配置方法离散PET固相缩聚过程的偏微分方程模型,然后基于改进的平方根不敏Kalman滤波算法(ISR-UKF),设计自适应联合估计器,同时获得参数和状态估计值。实验结果表明,参数估计结果合理,状态估计精度较高且稳定性好;并获得了频率因子、活化能近似值和有效系数随反应温度动态变化的规律,表明所提出的联合估计器能获得较好的实际应用效果。     

聚酯(PET)反应过程研究Ⅴ预缩聚反应过程分析和反应动力学研究

对乙二醇和对苯二甲酸预缩聚反应过程进行了分析，把该过程分解为反应动力学和反应器内各种传质，对预缩聚反应过程的反应动力学进行了实验研究。得到了不同温度下的反应速率及其参数     

基于Aspen Polymer的聚酯生产四釜工艺流程建模

基于Aspen Polymer工艺流程模拟软件对以对苯二甲酸和乙二醇为单体生成聚酯的逐步加成聚合反应体系进行了建模。采用链段法定义反应体系各组分,物性方法采用非随机二液相活度系数模型和Flory-Huggins模型组合的Poly NRTL模型;工艺建模考虑了反应过程中的传质,包括小分子的脱挥过程以及固相对苯二甲酸在乙二醇和对苯二甲酸二乙二醇酯中的溶解过程;传质模型以fortran程序通过asplink连接到反应器模型中;在此基础上建立聚酯生产四釜工艺流程模型,模拟结果与实际操作值吻合较好,后缩聚反应器出口熔体的特性黏数达到0.69 dL/g;建立的聚酯四釜工艺流程模型能够方便的进行灵敏度分析,可指导新装置的设计和优化,有工业应用价值。     

Modeling of a continuous rotating disk polycondensation reactor for the synthesis of thermoplastic polyesters

A dynamic multicompartment model is proposed for a continuous flow rotating disk reactor for the finishing stage melt polycondensation of poly(ethylene terephthalate). In the multicompartment reactor model, ethylene glycol is removed from both the bulk melt phase and the film phase formed on the rotating disks. The specific interfacial area for the film phase is estimated using the empirical correlation for polymer film thickness, and the mass transfer coefficient is calculated using the penetration theory. The mass transfer enhancement factor is introduced to account for the increased interfacial area due to ethylene glycol bubbles. The effects of reactor design and operating parameters on molecular weight and ethylene glycol removal have been investigated through model simulations. In particular, a detailed analysis is presented on the ethylene glycol removal rate from the two phases. © 1996 John Wiley & Sons, Inc.     

Intensification of hydrodesulphurization process with a structured bed spiral mini-reactor

The procedure followed for the study of the characteristics of the intensification of catalytic hydrodesulphurization process with a structured bed spiral reactor is presented in the current work. This procedure consists of two parallel experimental methods investigating the mechanisms involved in the operation of the reactors. The first method aims at the study of the process mechanisms with mock up experiments at ambient conditions using systems with inorganic or organic liquids, water or heptane, and oxygen or nitrogen as gas phase. The second one focuses on the mechanisms at reaction conditions using simple model reactions, like benzene hydrogenation. The studied mechanisms with the methods followed are the fluid dynamic characteristics of the operation of spiral reactor, flow regime, axial dispersion and mass transfer limitations. The mass transfer limitations were also studied with desulphurization experiments taking into account the impact of the inhibitors hydrogen sulphide and ammonia on the desulphurization reaction.     

外环流氨化反应器数学模型及其放大

研究了外环流氨化反应器的流动模型、传质模型和放大规律 .结果表明 ,在工业条件下 ,此反应器中的液相流动接近于全混流 ,传质模型为kGa =0 61W0 3a q1 2a应用此模型已将反应器放大到年产 60kt固体磷酸一铵规模 .     

EXPERIMENTAL DETERMINATION AND MODELLING OF LIQUID-SOLID MASS TRANSFER COEFFICIENTS IN A THREE-PHASE REACTOR

Apparent mass transfer coefficients for solid dissolution in a liquid with and without a chemical reaction were experimentally determined in a fixed bed three phases reactor with downward cocurrent gas and liquid flows. The chemical system selected was benzoic acid, sodium hydroxide in aqueous solution, and atmospheric air. Continuous gas, pulse and dispersed bubble regimes were studied and the results were correlated obtaining apparent mass transfer coefficient as a function of liquid and fluid volumetric flow. It was found that gas flow effect on mass transfer coefficient was small over continuous gas and dispersed bubble regimes, but appreciable over pulse regime. Additionally, it was found that the mathematical model that best described the mass transfer process under pulse regime, by using the increment factor due to the instantaneous chemical reaction, is the film theory     

Continuous post-polycondensation of high-viscosity poly(ethylene terephthalate) in the molten state

Time-resolved rheometry and size exclusion chromatography system [advanced polymer chromatography (APC)-multi-angle laser light scattering (MALLS)-refractive index detector (RID)] were employed to investigate post-polycondensation process of nonstirred high-viscosity poly(ethylene terephthalate) (PET) of molten film forming by high-flow inert gas sweeping at atmospheric pressure. In view of chemical reaction kinetics together with mass transfer to adjust reactive parameters, including moisture content of the sample, temperature, concentration of the active groups, residence time, and mass transfer factor, this work aims to distinguish the different reactions in reprocessing of high-viscosity PET. Results indicated that hydrolysis is observed initially before thermal degradation and polycondensation reactions on remelting process. Promotion of thermal degradation is stronger than polycondensation with the increase in temperature. Fiber-grade PET exhibits polycondensation as the dominant reaction at 275 °C in a reasonable reaction time, which leads to the increase of average molecular weight and the phenomenon of double distribution proved by APC-MALLS-RID system. However, the average molecular weight of industrial yarn-grade PET is very difficult to improve when the thermal degradation reaction is not effectively inhibited. Importantly, the experimental study of the interfacial mass-transfer area and mass-transfer intensification demonstrated that mass transfer is the rate-determining factor for the overall post-polycondensation of high-viscosity melt. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47484.     

Film reaction kinetics for melt postpolycondensation of poly(ethylene terephthalate)

Melt polycondensation has recently been reported to prepare high-viscosity poly(ethylene terephthalate) (PET), the reaction efficiency is greatly improved in over 10-folds compared with conventional solid state polycondensation (SSP). Melt postpolycondensation of common PET chips was conducted in specified film thickness to obtain industrial PET. Based on the investigation of reaction conditions, film reaction kinetics were determined in the principle of end groups analysis. It was positively regulated that the intrinsic viscosity of PET could be achieved in condition of high vacuum, thin melt film and proper temperature, degradation reaction would be increased at exorbitant temperature. An apparent reaction kinetic model was proposed and was verified by experiments. Results indicated the activation energy of melt postpolycondensation of PET was 88.22 kJ/mol and the reaction rate constant was significant higher than that of solid state polycondensation.