工业异构化反应器建模及仿真

将3个二甲苯异构体集总为一个组分,提出一个新的异构化三角反应网络,建立工业异构化反应器模型.基于多组平衡的工业数据,采用传统的优化方法估计动力学参数,然后对不同操作条件下的大量工业数据进行仿真,结果表明模型估计值与观测值相当吻合.与其他模型相比,文中开发的模型在相对误差、相对均方误差和参数估计时间等性能指标上均体现出优...     

Kinetic model for hydroisomerization reaction of C-aromatics

Based on the reported reaction networks, a novel six-component hydroisomerization reaction network with a new lumped species including C₈-naphthenes and C₈-paraffins is proposed and a kinetic model for a commercial unit is also developed. An empirical catalyst deactivation function is incorporated into the model accounting for the loss in activity because of coke formation on the catalyst surface during the long-term operation. The Runge-Kutta method is used to solve the ordinary differential equations of the model. The reaction kinetic parameters are benchmarked with several sets of balanced plant data and estimated by the differential variable metric optimization method (BFGS). The kinetic model is validated by an industrial unit with sets of plant data under different operating conditions and simulation results show a good agreement between the model predictions and the plant observations.     

八碳芳烃临氢异构化反应动力学模型

针对某实际工业异构化装置,在已开发的八碳芳烃临氢异构化反应网络的基础上,将系统中的八碳环烷烃和八碳链烷烃作为一个集总组分,提出新的六组分异构化反应网络,由此建立了适用于工业生产的八碳芳烃临氢异构化反应动力学模型.考虑结焦对催化剂活性的影响,提出了一种经验形式的催化剂失活函数,能够合理地描述催化剂失活过程.采用四五阶Runge-Kutta法对模型方程进行数值求解,基于多套稳态平衡数据采用差分变尺度优化算法(BFGS)对动力学参数进行估计,进而在不同操作条件下对模型进行验证.结果表明估计值与工业标定值相当吻合,达到了工业应用的模拟精度要求.     

用于甲苯歧化与C9芳烃烷基转移过程先进控制的反应动力学模型

针对某实际工业装置,建立了甲苯歧化和C₉芳烃烷基转移反应简化机理模型,用于反应过程的监控、优化及大型轴向流反应器内各物料组成分布的预测;采用四-五阶Runge-Kutta法对模型方程进行了数值求解,并基于多套稳态平衡数据,采用Broyden-Fletcher-Goldfarb-Shanno(BFGS)优化算法对动力学模型参数进行了估计;针对不同的进料组成和操作条件,对工业装置进行模拟仿真。结果表明,模型估计值与工业标定值相当吻合,达到了工业应用的模拟精度要求。所建立的模型形式简单、参数估计方便,适用于工业装置的离线仿真和在线软测量。     

大庆重石脑油蒸汽热裂解集总动力学模型

通过对自建小型裂解装置实验数据的分析,建立了大庆重石脑油蒸汽热裂解反应8集总动力学物理模型,并用Matlab语言对Marquardt⁺⁺ 法进行编程求取了该物理模型的动力学参数。通过对模型计算值与实验值的相对误差分析表明：原料集总因分得较少,相对误差较大,约为10%,但主要产品产率的最大相对误差不超过7%,其中乙烯产率的平均相对误差为1.62%,说明所建模型较好地反映了大庆重石脑油蒸汽裂解反应规律,可以较好地预测主要产品分布。     

Kinetic model for hydroisomerization reaction of C8-aromatics

Based on the reported reaction networks, a novel six-component hydroisomerization reaction network with a new lumped species including C₈-naphthenes and C₈-paraffins is proposed and a kinetic model for a commercial unit is also developed. An empirical catalyst deactivation function is incorporated into the model accounting for the loss in activity because of coke formation on the catalyst surface during the long-term operation. The Runge-Kutta method is used to solve the ordinary differential equations of the model. The reaction kinetic parameters are benchmarked with several sets of balanced plant data and estimated by the differential variable metric optimization method (BFGS). The kinetic model is validated by an industrial unit with sets of plant data under different operating conditions and simulation results show a good agreement between the model predictions and the plant observations. __________ Translated from Journal of Chemical Engineering of Chinese Universities, 2007, 21(3): 429–435 [译自: 高校化学工程学报]     

绝热加速量热无模型方法动力学预测

绝热加速量热主要采用基于单一实验数据的模型拟合方法进行动力学预测,难以应用于未知机理反应和复杂反应。为此,通过数值模拟方法在绝热条件下产生n级反应与Kamal自催化反应数据,采用Vyazovkin和Friedman等转化率方法进行动力学求解;然后在不同起始温度和等温条件下,采用无模型动力学参数进行绝热和等温动力学预测,并与模拟数据对比。结果表明,绝热加速量热采用Vyazovkin方法预测最大相对误差为39.9%,Friedman方法预测最大误差超100%,前者更适合进行预测;建议在预测温度±40℃范围内进行实验测量。这为未知化学物质和复杂反应热失控风险评估及化工事故模拟等提供了有效手段。     

甲苯歧化与C9芳烃烷基转移反应动力学模型和模拟分析

A new kinetic model for commercial unit of toluene disproportionation and C9-armatiocs transalkylation is developed based on the reported reaction scheme.A time based catalyst deactivation function taking weight hourly space velocity（WHSV）into account is incorporated into the model,which reasonably accounts for the loss in activity because of coke deposition on the surface of catalyst during long-term operation.The kinetic parameters are benchmarked with several sets of balanced plant data and estimated by the differential variable metric optimiza- tion method.Sets of plant data at different operating conditions are applied to make sure validation of the model and the results show a good agreement between the model predictions and plant observations.The simulation analysis of key variables such as temperature and WHSV affecting process performance is discussed in detail,giving the guidance to select suitable operating conditions.     

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.     

Modelling of catalytic naphtha reformers

A simple kinetic model has been used to simulate catalytic naphtha reformers. The model idealises naphtha to three constituents, namely, paraffins, naphthenes and aromatics, with average properties assigned to each class. Out of the many reactions the mixture can undergo, four major reactions have been considered for which the kinetic parameters have been estimated using plant production data. The reactor model is validated against two different sets of plant data. The agreement between predicted results and observations is generally good. A sensitivity analysis of operating parameters on reactor performance revealed that, while temperature affects the aromatics production significantly, the effect of pressure is negligible.     

添加晶种的间歇结晶器数学模型

动力学参数是设计结晶器和优化过程操作的主要依据。针对添加晶种的二次成核结晶过程，采用经验方程将反映结晶固相信息的透光率数据与CSD的二阶矩量进行关联，建立了包含透光率、液相浓度和相对过饱和度的动力学模型。并以KNO3-H2O为对象，运用该模型求取了结晶成核和生长动力学参数，结果与文献值相近。     

Kinetic model for the hydrolysis of sterilized palm press fibre

In this study, a kinetic model for enzymatic hydrolysis of oil palm residues considering the effect of sterilization was proposed and validated. Experiments were performed in batch reactor using palm oil mill effluent (POME) supplemented with sterilized and non-sterilized pressed pericarp fibers (PPF) as substrates. Kinetic parameters were estimated by fitting the experimental data to the models. It was found that the sterilization process as well as the variety in substrate particle size exerted an effect on the apparent rate constant (k), but no effect on the apparent Michaelis constant (K_M) and apparent competitive inhibition constant (K_I). When compared with the experimental data, the kinetic model provided good prediction to the oil palm residues hydrolysis with mean square error less than 10%.     

A new generic approach for the modeling of fluid catalytic cracking (FCC) riser reactor

A new kinetic model for the fluid catalytic cracking (FCC) riser is developed. An elementary reaction scheme, for the FCC, based on cracking of a large number of lumps in the form of narrow boiling pseudocomponents is proposed. The kinetic parameters are estimated using a semi-empirical approach based on normal probability distribution. The correlation proposed for the kinetic parameters’ estimation contains four parameters that depend on the feed characteristics, catalyst activity, and coke forming tendency of the feed. This approach eliminates the need of determining a large number of rate constants required for conventional lumped models. The model seems to be more versatile than existing models and opens up a new dimension for making generic models suitable for the analysis and control studies of FCC units. The model also incorporates catalyst deactivation and two-phase flow in the riser reactor. Predictions of the model compare well with the yield pattern of industrial scale plant data reported in literature.     

规模化聚酯装置酯化过程的机理模型化

聚对苯二甲酸乙二醇酯(PET)酯化反应体系的热力学物性计算、动力学常数的整定是实现聚酯工业生产装置模型化的2个重要部分。对聚酯酯化过程的各主副反应——酯化反应、缩聚反应、水解反应、醇解反应、二甘醇生成反应进行机理分析和参数比较,确定了聚酯生产全流程模拟的动力学常数的合理范围。通过动力学参数对目标产物对苯二甲酸、二甘醇、乙二醇、PET质量流量影响的灵敏度分析,修正了反应动力学常数使之适应特定的工业装置,结合物性计算方程建立了规模化聚酯装置酯化工段的机理型数学模型。利用不同生产负荷的工业数据对模型进行了验证,其误差在3%以内。     

蜡油加氢脱硫集总动力学模型研究

以减压蜡油（VGO）加氢脱硫（HDS）小试实验数据为基础,针对VGO HDS反应速率快慢,将原料中硫化物划分为快反应速率、中反应速率、慢反应速率3个集总,建立VGO HDS反应三集总动力学模型,并采用Levenberg-Marguardt算法对模型参数进行了求解。结果表明,该模型平均相对误差仅为5.18%,预测值可靠,外推性良好,模型参数计算结果符合加氢反应规律。通过模型计算,分析了液时空速、反应温度、反应压力对VGO HDS过程的影响,得到了HDS详细的反应规律,可为VGO HDS反应集总动力学研究和实验分析提供参考。     

ADDITION OF PORE DIFFUSION LIMITATION TO THE “UCKRON-I” KINETIC RATE OF METHANOL SYNTHESIS

Kinetic data with pore diffusion limitation on methanol synthesis were generated by extending the “UCKRON-I” kinetic rate expression. The best fit model and the extended “true” model were compared using their respective rates to simulate temperature profiles in a non-isothermal plug flow tubular reactor.

The objective of this work was to add pore diffusion resistance to the UCKRON-1 kinetic rate for methanol synthesis (Berty, et al. 1983). Kinetic modeling of the data with 5% experimental error added, showed the best model to be that developed from a previous kinetic model (Shalabi, et al. 1983) with apparent activation energy approximately one-half the activation energy at no pore diffusion.

Methods used in this work to determine and evaluate pore diffusion parameters can be utilized for other reaction systems where pore diffusion may play a role in reaction rate.

Temperature profiles estimated from reactor simulation studies showed good argeement between ideal and predicted models for temperature.     

基于联立法的乙烯淤浆聚合牌号切换过程动态模拟

以乙烯淤浆聚合流程为研究对象,建立了包含动力学和热力学的动态机理模型,采用有限元正交配置法对控制变量和状态变量同步离散化,实现了全联立动态模拟。热力学物性计算采用Kriging函数估计,可适用于多个工况,最大误差不超过2%。利用Aspen Plus 5个牌号工况的数据,进行了模型稳态验证,并实现了牌号切换动态模拟,计算了平均分子量等质量指标,与Aspen Dynamic曲线吻合较好,为牌号切换的优化奠定了基础。     

用于TS-1催化苯酚羟基化的一体式催化/膜过滤系统的模型研究

This research is focused on the development of a simple design model of the submerged catalysis/ membrane filtration (catalysis/MF) system for phenol hydroxylation over TS-1 based on the material balance of the phenol under steady state and the reported kinetic studies. Based on the developed model, the theoretical phenol conversions at steady state could be calculated using the kinetic parameters obtained from the previous batch ex-periments. The theoretical conversions are in good agreement with the experimental data obtained in the submerged catalysis/MF system within relative error of ±5%. The model can be used to determine the optimal experimental conditions to carry out the phenol hydroxylation over TS-1 in the submerged catalysis/MF system.     

Sensitivity analysis applied to independent parallel reaction model for pyrolysis of bagasse

The independent parallel reaction model (IPR model) is applied in this work to study the slow dynamic pyrolysis of sugarcane bagasse, based on a thermogravimetric analysis of three ranges of particle diameters. The kinetic parameters and mass fraction of each principal pseudo-component of biomass (hemicellulose, cellulose and lignin) are estimated using the Differential Evolution Algorithm. A comparison of the estimated mass fractions and Arrhenius parameters against experimental values reported in the literature shows good agreement. The influence of various kinetic parameters of the model is also analyzed by means of sensitivity studies using derivative methods based on the DASPK 3.0 code. The results of the relative parametric sensitivity indicate that activation energies affect bagasse conversion more strongly than other parameters, followed by the pre-exponential factors of Arrhenius equation and mass fractions. The sensitivity of the IPR kinetic model to the orders of reaction is very slight.     

大庆常压渣油催化裂解反应动力学模型研究

针对大庆常压渣油催化裂解反应体系,建立了大庆常压渣油催化裂解五集总动力学模型,推导出了各集总组分在反应器出口处的浓度表达式,给出了一种用于求取集总模型参数的简单方法。结合实验数据,编程计算求取了该五集总反应网络的速率常数、指前因子和活化能,并对所建集总模型的预测效果进行了初步检验,结果表明该模型对催化裂解汽柴油、气体烷烃和气体烯烃具有较好的预测能力,短停留时间有利于多产低碳烯烃。