粒子群优化算法在催化裂化模型参数估计中的应用

参数估计是化工模型工业应用中的重要课题,有相当的难度。针对催化裂化八集总模型的动力学参数估计问题,考察了不同类型优化算法的应用效果,结果表明,粒子群优化算法简单、容易实现,而且可以避免传统方法对初始值的依赖,并进一步提出用结合Levenberg-Marquardt算法的混合粒子群优化算法提高参数估计效果。工业实例表明,用混合粒子群优化算法得到的动力学参数可以保证模型的预测精度。     

The inverse methodology of parameter estimation for model adjustment,design, simulation,control and optimization of fluid catalytic cracking (FCC) risers

BACKGROUND: A simple model is required to produce a fast computational code that is sufficiently precise to be used for the design, simulation, control and optimization of fluid catalytic cracking (FCC) risers. This work experimentally validates and adjusts a simplified FCC riser model using available experimental data, and proposes utilization of the inverse problem of the parameter estimation method to fit any existing kinetic model to a specific feedstock/catalyst set for general application. RESULTS: The model adjustment procedure was repeated for nine different experimental sets and the best fitting parameters were obtained statistically. The fitting parameters were utilized to predict the riser output conditions for the other 18 data sets. The numerical results are in good quantitative and qualitative agreement with the experimental data. The model was then utilized to simulate an industrial FCC riser, predicting concentrations and temperature profiles from the bottom to the top of the riser. CONCLUSIONS: The results suggest that the simplified model, combined with the proposed inverse methodology could produce accurate results for any feedstock/catalyst set, once the kinetic model is known for a particular feedstock/catalyst set. Therefore, a low computational time and accurate tool is made available for simulation, control, design and optimization of FCC risers. Copyright © 2008 Society of Chemical Industry     

Kinetic studies of alkyl formate hydrolysis using formic acid as a catalyst

BACKGROUND: The hydrolysis of methyl formate is the major industrial process for the production of formic acid. The aim of the work is to determine the reaction kinetics quantitatively in the presence of formic acid catalyst, develop a mathematical model for the reaction system and estimate the kinetic parameters for the purpose of optimization. RESULTS: Liquid phase hydrolysis kinetics of alkyl formates (ethyl and methyl formate) was studied in an isothermal batch reactor at 80–110 °C and 20 bar nitrogen pressure. The catalyst of choice was formic acid. The reaction rate was enhanced but the formic acid product yield was slightly suppressed relative to the uncatalysed system. A kinetic model comprising mass balances and rate equations was developed and the kinetic and equilibrium parameters included in the rate equations were estimated from the experimental data with non‐linear regression analysis. CONCLUSION: The model was able to predict the experimental results successfully. The results obtained were compared quantitatively with an earlier model involving alkyl formate hydrolysis in a neutral aqueous solution. Copyright © 2011 Society of Chemical Industry     

超细粒子Fe-Mn工业催化剂F-T合成集总机理动力学(Ⅱ)参数估算与模型筛选

为获得真实、准确的动力学参数,设计和安排了动力学实验,在参数估算过程中建立了CO转化率和CO₂选择性两个目标函数.用传统的Levenberg-Maquardt方法,通过对文（Ⅰ）建立的超细Fe-Mn工业催化剂F-T合成集总机理动力学模型参数的优化,得到最终的估算值.依据参数的物理意义、拟合程度和统计检验对建立的动力学模型进行模型筛选,最终获得的动力学模型可较好地描述CO转化率和CO₂选择性,估算值与实验值相对残差一般小于25%.同时,所得模型可较好地解释催化剂反应性能.     

用阳离子交换树脂催化酯化合成乙酸异丙酯动力学研究

在间歇反应釜中,采用强酸型阳离子交换树脂(Amberlyst 15-Wet)作催化剂,在液-固两相体系中对乙酸异丙酯合成反应过程进行了研究,系统地考察了搅拌速度、催化剂粒径、温度、催化剂浓度、酸醇比对酯化反应速率的影响。同时通过拟均相动力学模型对反应过程进行了模拟,计算得到了相关的动力学参数。计算结果与与实验值吻合良好,能较好地描述乙酸和异丙醇合成乙酸异丙酯的酯化反应过程。     

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.     

Open-loop optimization for batch reaction systems: a case study

A comparison of the results obtained from deterministic and stochastic model-based optimization approaches for the determination of the optimal open-loop operating policy for a semi-batch reaction system are presented. The commercial synthesis of an intermediate in the production of the hypertension agent Eprosartan is considered in this case study. Identification of the reaction mechanism and estimation of the kinetic model parameters from experimental data are carried out as part of the development of a detailed semi-batch reaction system model that is used with the optimization approaches. The results of this study indicate that conversion optimization of the operating conditions can provide a good approximation to the economic optimum in the case of high conversion operation. This study also indicates that the optimal operating policy for the catalyst and reactant are batch, with the catalyst addition occurring prior to the reactant, and that a reduction in the amount of reactant from current practice is possible.     

Mechanism and kinetics of esterification of adipic acid and ethylene glycol by tetrabutyl titanate catalyst

An eight-step mechanism of esterification reaction between adipic acid (AA) and ethylene glycol (EG) catalyzed by tetrabutyl titanate [Ti(OBu)₄] was studied in detail. The kinetic data for the esterification reaction between AA and EG catalyzed by tetrabutyl titanate [Ti(OBu)₄] were measured in the temperature range of 403 K-433 K. A second-order kinetic model was established, and the model parameters were obtained through an optimization procedure by minimizing the value differences between the simulated component concentrations in the reaction system with the experimental ones. The results demonstrate that the model is suitable for the esterification reaction between AA and EG catalyzed by tetrabutyl titanate [Ti(OBu)₄]. Furthermore, the esterification reaction rate increases with the increase of reaction temperature, concentration of catalyst and the initial reactant ratio of EG to AA.     

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]     

Ni—Mo／TiO2-Al2O3催化剂上柴油加氢脱硫反应动力学研究

以混合柴油为原料,采用高压滴流床反应器,在反应温度280—360℃、氢分压5-7MPa、氢油体积比300～900、液时空速1—6h。的条件下,考察了柴油在Ni-Mo／TiO2-Al2O3催化剂上的加氢脱硫反应规律,并建立了柴油加氢脱硫经验型模型。采用Levenberg—Marquard优化方法,对实验数据进行回归,确定了反应动力学模型中的有关参数,得到的反应级数为2．9,加氢脱硫反应的表观活化能为143613J／mol,同时得到了在实验条件范围内Ni—Mo／TiO2-Al2O3催化剂上柴油的加氢脱硫动力学方程。经检验,模型计算结果与实验数据吻合良好。     

大庆常渣催化裂解反应动力学模型

An 8-lump kinetic model was proposed to predict the yields of propylene,ethylene and gasoline in the catalytic pyrolysis process of Daqing atmospheric residue.The model contains 21 kinetic parameters and one for catalyst deactivation.A series of experiments were carried out in a riser reactor over catalyst named LTB-2.The kinetic parameters were estimated by using sub-model method,and apparent activation energies were calculated according to the Arrhenius equation.The predicted yields coincided well with the experimental values.It shows that the kinetic parameters estimated by using the sub-model method were reliable.     

Combined experimental and kinetic modeling studies for the conversion of gasoline range hydrocarbons from methanol over modified HZSM-5 catalyst

The reaction was carried out in fixed bed reactor. The effect of process variables on the activity of oxalic acid treated 0.5 wt% ZnO/7 wt% CuO/HZSM5 catalyst for the conversion of methanol to gasoline range hydrocarbons was studied. The catalyst was prepared by incipient wetness impregnation method. After impregnation the catalyst was treated with oxalic acid. The validity of kinetic model proposed for the methanol to gasoline range hydrocarbon process at zero time on stream was studied, from the experimental results obtained in a wide range of operating conditions. The kinetic parameters for various models were calculated by solving the equation of mass conservation in the reactor for the lumps of the kinetic models. The kinetic model fitted well for simulating the operation in the fixed bed reactor in the range of 635 to 673 K, with regression coefficient (R²) higher than 0.96.     

甲苯甲醇烷基化制对二甲苯动力学模型

采用固定床反应器,在消除内外扩散影响的基础上,在反应温度480~560℃、甲苯甲醇总质量进料空速2 h-1、甲苯甲醇物质的量之比为1~6、水与甲苯物质的量之比为2~6和氢气与甲苯物质的量之比为2~8的条件下,研究了在自制沸石分子筛催化剂上甲苯甲醇烷基化反应的本征动力学,建立了包括甲苯甲醇烷基化制对二甲苯、二甲苯间异构化、二甲苯深度烷基化生成三甲苯和甲醇生成烯烃等7个反应的完整反应网络。采用非线性优化方法进行参数估算,并对模型的适用性进行了误差分析和统计检验。结果表明,甲醇生成烯烃反应的加入使模型能较好地反映出甲苯甲醇物质的量比对反应结果的影响,甲苯甲醇烷基化制对二甲苯的表观活化能为76.66 k J/mol,通过误差分析和统计检验表明,动力学模型是适用的。     

Optimization of an operating domestic wastewater treatment plant using elitist non-dominated sorting genetic algorithm

Multi-objective optimization of an operating domestic wastewater treatment plant is carried out using binary coded elitist non-dominated sorting genetic algorithm. Activated sludge model with extended aeration is used for optimization. For optimal plant operation, two different optimization problems are formulated and solved. The first optimization problem involves single-objective function to estimate kinetic parameters in activated sludge model using available plant data by minimizing the weighted sum-of-square errors between computed and plant values. The second optimization problem involves single-, two- and three-objective functions for efficient plant monitoring. In second category problem, objective functions are based on plant performance criteria (i.e., maximizing the influent flow rate of wastewater and minimizing the exit effluent concentration) and economic criteria (i.e., minimizing the plant operating cost). The important decision variables are: mean cell-residence time, mixed liquor suspended solid concentration in the reactor and underflow sludge concentration. Unique solution is obtained for the single-objective function optimization problem whereas a set of non-dominated solutions are obtained for the multi-objective optimization problems. A set of optimal operating conditions are proposed based on the present optimization study, which enhances the plant performance without affecting the discharge effluent quality. Finally, sensitivity analyses of the model results to the kinetic parameters and the kinetic parameters to the GA parameters are carried out to know the sensitivity of the obtained results with changes in the input parameter space.     

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.     

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.     

CS-1型聚丙烯催化剂的聚合动力学行为

采用聚合实验并结合理论模拟技术对CS-1型高效聚丙烯催化剂的聚合动力学进行了研究。对通过聚合实验所获取的聚丙烯凝胶渗透色谱(GPC)进行解析,得到CS-1型聚丙烯催化剂的最可几活性中心数目。以此为基础,通过理论模型耦合实验结果确定了各活性中心的聚合动力学方程及各自动力学参数取值。此外,采用扩充的实验结果对模型进行了考核。结果表明,文中所建立的多活性中心动力学方程可以用来表征CS-1型聚丙烯催化剂的聚合动力学行为。     

1,6-己二醇二丙烯酸酯合成动力学

以固体酸SO_4~(2-)/TiO_2-SnO_2-ZnO为催化剂,丙烯酸和1,6-己二醇为原料,考察了催化剂加量、转速以及催化剂粒径对酯化反应速率的影响。在消除内外扩散影响的前提下,建立了固体酸催化合成1,6-己二醇二丙烯酸酯拟均相反应动力学模型,得到了相应的动力学方程参数,动力学模型预测的结果与实验结果吻合良好。     

Study of the effect of BDMA catalyst in the epoxy novolac curing process by isothermal DSC

Epoxy novolac/anhydride cure kinetics has been studied by differential scanning calorimetry under isothermal conditions. The system used in this study was an epoxy novolac resin (DEN431), with nadic methyl anhydride as hardener and benzyldimethylamine as accelerator. Kinetic parameters including the reaction order, activation energy and kinetic rate constants, were investigated. The cure reaction was described with the catalyst concentration, and a normalized kinetic model developed for it. It is shown that the cure reaction is dependent on the cure temperature and catalyst concentration, and that it proceeds through an autocatalytic kinetic mechanism. The curing kinetic constants and the cure activation energies were obtained using the Arrhenius kinetic model. A suggested kinetic model with a diffusion term was successfully used to describe and predict the cure kinetics of epoxy novolac resin compositions as a function of the catalyst content and temperature. Copyright © 2003 Society of Chemical Industry