聚酯（PET）反应过程研究：Ⅱ.酯化反应过程动力学研究

对乙二醇和对苯二甲酸直接酯化反应过程的主反应动力学和生成ＤＥＧ副反应的动力学进行了研究，得到了不同温度下的反应速率，进而获取了各反应的活化能和频率因子。     

A simulation study on continuous direct esterification process for poly(ethylene terephthalate) synthesis

A mathematical model for a continuous direct esterification reactor has been developed. The solid-liquid equilibrium of terephthalic acid (TPA) was considered in our modeling, and the characteristic dissolution time, an adjustable parameter, was introduced to account for the mass-transfer effect in the dissolution of TPA. The effects of the characteristic dissolution time, monomer feed ratio, temperature, and pressure on the reactor performance at different residence times were investigated through simulation. It was observed that the behavior of the first reactor strongly depends on whether the solid TPA is completely dissolved in the reaction mixtures. From the dynamic simulations, it was found that a sudden change in the operating conditions affects the ethylene glycol (EG) vapor flow rate instantly. For the esterification process having two reactors in series, the strategy for time distribution and recycling of EG is also discussed. © 1997 John Wiley & Sons, Inc.     

PET连续聚合工艺流程优化改造

采用将五釜流程改为四釜流程的方法,即以酯化预聚塔一个反应器取代五条工艺流程的第二酯化釜和第一预缩聚釜两个反应器,对PET聚合工艺流程优化,改造后的PET单线生产能力由160t/d提高到200 t/d,其单耗PTA由改造前的865 kg/t降至863 kg/t,EG由338 kg/t降至334 kg/t,降低了成本,提高了产品质量。     

聚酯（PET）反应过程研究：Ⅲ酯化反应过程中传质研究

对酯化反应过程中发生的传质分别进行了分析和研究，得到了ＴＰＡ溶解度关联式；ＥＧ，水和齐聚物的汽液平衡数据；反应器内ＥＧ和水的气液传质速率关联式以及工艺塔的简化模型     

TPA和EG连续生产PET的第一酯化反应器操作模拟

对乙二醇(EG)和对苯二甲酸(TPA)连续生产对苯二甲酸乙二酯(PET)的第一酯化反应器进行了数学模拟。数学模型中包括了反应动力学方程、气液平衡和气液传质方程,使模拟结果接近于工厂实践。此外对不同停留时间、不同的反应器操作温度及压力、不同的进料 EG/TPA 的 mol比,进行了模拟计算,得出了反应器出口各种产物的组成随操作参数的变化,并对各操作参数的范围和对反应的影响进行了评述。     

DMT间歇装置的PTA半连续工艺改造

通过对 2种工艺路线的热负荷计算 ,确定改造后的设备变动情况。合理地增加酯化釜的加热面积、酯化塔的高度 ,保证了酯化反应的正常进行及EG和水的分离效果。在其他设备相应配套改动后 ,PTA路线的产品质量比DMT路线有较大的改善。     

酯化分馏控制的影响因素及改进措施

通过实例介绍酯化反应产生的水、游离EG的气速和回流液流量对分馏的影响及几种干扰分馏控制的因素。改变操作方法,用控制分馏柱中温、检测,保证柱顶温代替原控制柱顶温,用计量泵更换调节阀来控制回流量,建立适用于本装置的酯化内、外温及进料速度和酯化分馏标准曲线,对出现故障的分馏柱及时整改,定期校验测量仪表等可以提高产品质量,保证生产连续稳定。     

A mathematical model for computer simulation of a direct continuous esterification process between terephthalic acid and ethylene glycol: Part 1. Model development

A new mathematical model has been developed for the continuous esterification process of terephthalic acid (TPA) and ethlene glycol (EG) with consideration of oligomer characteristics. The liquid weight fraction in the reaction mixture, β, has been selected as a principal parameter in this model. The solubility of TPA in EG and bis β-hydroxyethyl terephthalate (BHET) has been measured in order to estimate more precisely the concentration of each component. Good agreement has been obtained by plotting the log of solubility data of TPA in EG and BHET against the reciprocal of the absolute temperature with correlation coefficients of 0.998 and 0.989, respectively. The validity of these data has been verified in comparison with other data.     

聚酯生产中的乙二醇回用试验

由聚酯生产过程中污乙二醇回用的模拟研究结果,说明了污乙二醇中所含二甘醇、齐聚物、水和醛等杂质对聚酯工艺有影响。齐聚物的存在有利于对苯二甲酸的溶解,加快了酯化反应速度,较高含水量会引起酯化反应过程中压力的波动,并会增加乙二醇脱水塔的负荷,醛在反应过程中大部分被分馏出,而残留的醛会使产品色相变差。试验给果表明:直接法生产聚酯过程中,从缩聚真空系统中排出的污乙二醇完全可以返回酯化段直接参与配料。考虑到醛含量对产品色相的影响,回用的乙二醇配比不宜超过50%。乙二醇直接回用的经济效益预计每吨聚酯切片可降低乙二醇消耗约2.5kg,对苯二甲酸约1.1kg。     

Modeling of poly(ethylene terephthalate) reactors: 5. A continuous prepolymerization process

A mathematical model for the continuous prepolymerization of BHET to PET, carried out in a series of stirred tank reactors, has been developed. The influence of process and operational variables on productivity, as well as the side-product formation (which controls the product quality), have been studied in a range as close to industrial practice as possible. The overall conclusions concerning the productivity profile, as well as some side products, appear to be substantiated from the available data in the open literature. The results of the mathematical model have been used to highlight the key process and operational variables that are likely to give the best productivity and product quality in industrial practice.     

影响聚酯切片中二甘醇含量的因素

探讨了 PTA质量、EG/ PTA摩尔比、酯化温度、酯化压力、生产负荷和缩聚真空度等因素对聚酯切片中二甘醇 (DEG)含量的影响。指出要控制 DEG含量 ,必须视生产情况及时采取调整工艺参数 ,调节 EG/ PTA摩尔比 ,降低酯化温度及酯化压力以及提高生产负荷等措施     

EG精制间歇和连续流程对比选择

介绍了PET生产中粗EG精制常用的连续化和间歇精制的流程,针对年产1.5万t改性PET的粗EG处理项目,从工艺复杂性、设备配置、可操作性、产品品质及投资等方面进行比较,间歇精制为适合该项目的流程。     

A mathematical model for a continuous esterification process with recycle between terephthalic acid and ethylene glycol

A new mathematical model for a continuous recycle esterification process has been derived by basically the same procedure as the continuous process of a cascade type, reported earlier, which includes material and heat balances. Such a model can give extensive information about the optimum design of a new plant through the predictions of oligomer characteristics (concentrations of carboxyl and hydroxyl end groups, number average molecular weight, number average degree of polymerization, esterification and saponification degree, DEG content, melting point of oligomer, etc.), distillate properties (concentrations of EG and water in the vapor phase), heat transfer area, mass flow rate of heating medium, amount of heat supplied by heating medium, enthalpy moving with recycle, and amount of heat removed from each reactor. © 1992 John Wiley & Sons, Inc.     

基于CS3000平台的酯化过程模拟培训系统设计

以CS3000为开发平台,阐述了聚酯生产中酯化过程模拟培训系统的设计。文中以浆料配置和酯化过程为例,根据所建立的数学模型,讨论了液位控制、PTA流量控制、n(EG)/n(TPA)计算模块和酯化釜品质检测指标计算模块的CS3000实现。     

Hydroformylation of formaldehyde to glycolaldehyde:An alternative synthetic route for ethylene glycol

Hydroformylation of formaldehyde to glycolaldehyde (GA),as a vital reaction in both direct and indirect process of syngas to ethylene glycol (EG),shows great advantages in the aspects of the process complex-ity and clean production.The hydroformylation of formaldehyde to GA is thermodynamically unfavour-able,requiring the development of highly efficient hydroformylation catalytic systems,appropriate reaction conditions and in-depth understanding of the reaction mechanisms.In this review,we have made a detailed summary on the reaction in terms of the reaction network,thermodynamics,metal com-plex catalysts (including central metals and ligands),reaction conditions (e.g.,temperature,pressure,formaldehyde source and solvent) and promoters.Furthermore,the reaction mechanisms,involving neu-tral and anionic complex in the catalytic cycle,have been summarized and followed by a discussion on the impact of the crucial intermediates on the reaction pathways and product distribution.A brief over-view of product separation and catalyst recovery has been presented in the final part.This review gives new insights into the factors that impact on the formaldehyde hydroformylation and reaction mecha-nisms,which helps to design more efficient catalytic systems and reaction processes for EG production via the hydroformylation route.     

聚酯(PET)反应过程研究⒇Ⅳ酯化反应过程数学模拟

通过对酯化反应器流动模型的分析结合酯化反应化学平衡、反应动力学和反应器内传质的研究建立了适用于多种工业酯化反应器的数学模型     

Optimization for the minimum reaction time of pet esterification

We have investigated the direct esterification reaction between terephthalic acid (TPA) and ethylene glycol (EG) in semi-batch reactors, the first stage process for making polyethylene terephthalate (PET), to get optimum conditions for the minimum reaction time. An independent-variable-minimization problem, i.e., a free-end-time/fixed-end-point problem, has been formulated for the system, and then converted to a dependent-variable-minimization (fixed-end-time/ free-end-point) problem by a coordinate transformation, for the latter problem readily yields to established solution methods. We have solved this reformulated problem to obtain the optimal temperature profiles in the reactor required for the minimum reaction time, by iteratively improving the temperature (manipulating variable) profile using the Pontryagin’s minimum principle. The results prove that the method employed here successfully finds an optimal solution for the PET esterification process. The reduction of the reaction time realized following this optimal temperature profile in the reactor was, however, found to be smaller than expected, due to the approximating assumptions of neglecting the solubility equation of TPA in the model. The results obtained using a more improved model of the system will be reported in the future.     

PET装置EG降耗的措施

对EG损耗影响因素进行分析后,通过改进酯化水分离塔,增大酯化釜,平衡原料量比,缓和工艺反应条件来降低酯化中的裂解副反应,降低EG单耗,减少对大气的污染,进一步推进装置清洁化生产。     

PET全消光预取向丝毛丝/网丝问题的解决

以涤纶125 dtex/72 f预取向丝(POY)为例,针对直熔纺POY半消光改纺全消光过程中遇到的毛丝/网丝问题进行探讨。通过对聚合及纺丝卷绕工艺的调整和分析,采用降低酯化段液位及乙二醇的回用量,提高环吹风冷却效果,增加油剂浓度,适当减小卷绕角及增大接触压力,合理分配纺程张力,最终解决了全消光POY生产中遇到的毛丝/网丝问题。     

PTT连续生产工艺设计

重点分析了聚对苯二甲酸丙二醇酯(PTT)直接酯化法连续生产的工艺特点,结合这些特点,详细介绍了PTT直接酯化法连续生产工艺技术的开发及工艺流程的创新点。