工业醋酸脱水系统多稳态模拟与分析(英文)

In this work, an industrial acetic acid dehydration system via heterogeneous azeotropic distillation is simulated by Aspen Plus software. Residue curves are used to analyze the distillating behavior, and appropriate operating region of the system is determined. Based on steady states simulation, a sensitivity analysis is carried out to detect the output multiple steady states in the system. Different solution branches are observered when the flow rates of the feed stream and the organic reflux stream are selected as manipulated variables. The performance of the column under different steady states is different. A method is proposed to achieve the desired steady state.     

甲苯液相催化氧化过程模拟与优化

Liquid-phase oxidation of toluene with air has become the main technology for producing benzoic acid in a reactor at present. Based on the kinetic model of the toluene oxidation process obtained from laboratory and mass balance of key component, a novel model is established to simulate the industrial toluene oxidation process, in which the effects of benzaldehyde and benzyl alcohol are considered and the kinetic parameters are revised by industrial data. The simulation results show that the error of benzoic acid yield is within 3.5%. Based on the simulation model, to maximize the benzoic acid yield, an optimization model is proposed to optimize the operating parameters, including toluene feed-in mass flux and temperature. The optimization result indicates that on the allowable operating conditions the maximum benzoic acid yield obtained with the reaction temperature at 167.2 C an the mass flux at 104.1 t·h^- 1 is greater than the current one, which can be used to guide industrial reactor s operation.     

工业PTA氧化过程4-CBA浓度的模糊神经网络模型

A fuzzy neural network (FNN) model is developed to predict the 4-CBA concentration of the oxidation unit in purified terephthalic acid process. Several technologies are used to deal with the process data before modeling.First,a set of preliminary input variables is selected according to prior knowledge and experience. Secondly,a method based on the maximum correlation coefficient is proposed to detect the dead time between the process variables and response variables. Finally, the fuzzy curve method is used to reduce the unimportant input variables.The simulation results based on industrial data show that the relative error range of the FNN model is narrower than that of the American Oil Company (AMOCO) model. Furthermore, the FNN model can predict the trend of the 4-CBA concentration more accurately.     

拟稳态模型用于间歇萃取精馏的数值模拟

Batch extractive distillation (BED) is a special method used in the distillation process by adding a solvent into the batch distillation column to alter the relative volatility of the components and improve the separation. A comprehensive design and simulation method is required due to the complexity of BED. In this study, a quasi-steady-state model for BED is proposed, the derivation and solution of the model are presented. This shortcut model can be used to simulate the composition and temperature of the reboiler, the top and other plates of the column in a batch extractive distillation operation. The calculated values are in good agreement with the experi-mental data. The results show that the quasi-steady-state model is a practical method because of some advantages such as high precision and fast calculation.     

规整填料塔吸收NOx过程的模拟和实验研究

A mathematical model of nitrogen oxide （NOx） absorption is adopted and solved for adiabatic operation of a column with structured packings on the basis of the film theory. Removal rate, outlet concentration, oxidation degree of NOx and outlet acid concentration, liquid acid temperature are simulated and tested. The gas phase reactions and equilibria, gas phase mass transfer, interracial equilibria, and liquid phase reactions are considered in the model. Absorption of nitrogen oxides is studied in packed with Mellapak 250Y columns in series in an industrial process of 20000 t oxalic acid per year. Favorable agreement is shown between the model predictions and the on-site observations.     

NO_x Absorption in Full Scale Plant Columns with Structured Packings

A mathematical model of nitrogen oxide(NO_x)absorption is adopted and solved for adiabatic operation of a column with structured packings on the basis of the film theory.Removal rate,outlet concentration,oxidation degree of NO_x and outlet acid concentration,liquid acid temperature are simulated and tested.The gas phase reactions and equilibria,gas phase mass transfer,interracial equilibria,and liquid phase reactions are considered in the model.Absorption of nitrogen oxides is studied in packed with Mellapak 250Y columns in series in an industrial process of 20000 t oxalic acid per year.Favorable agreement is shown between the model predictions and the on-site observations.     

A Reynolds mass flux model for gas separation process simulation:I. Modeling and validation

Separation process undertaken in packed columns often displays anisotropic turbulent mass diffusion. The aniso-tropic turbulent mass diffusion can be characterized rigorously by using the Reynolds mass flux (RMF) model. With the RMF model, the concentration and temperature as well as the velocity distributions can be simulated numerical y. The modeled Reynolds mass flux equation is adopted to close the turbulent mass transfer equation, while the modeled Reynolds heat flux and Reynolds stress equations are used to close the turbulent heat and mo-mentum transfer equations, so that the Boussinesq postulate and the isotropic assumption are abandoned. To val-idate the presented RMF model, simulation is carried out for CO2 absorption into aqueous NaOH solutions in a packed column (0.1 m id, packed with 12.7 mm Berl saddles up to a height of 6.55 m). The simulated results are compared with the experimental data and satisfactory agreement is found both in concentration and temper-ature distributions. The sequel Part II extends the model application to the simulation of an unsteady state ad-sorption process in a packed column.     

表面活性素集成生产过程(Ⅲ)吸附柱的模型

The study is focused on modeling of separation process and optimization.An adsorption separation process is simulated.The surfactin production process by Bacillus subtilis ATCC 21332 followed by surfactin adsorption in a fixed-bed column packed with commercial active carbon is studied in laboratory.The adsorption column achieves high surfactin recovery(94%)by up-flow methanol elution at 25°C.The adsorption column is simulated with a complex one-dimensional plug flow dispersion model coupled with nonlinear adsorption equilibrium,based on the assumption that the adsorption of surfactin is monomolecular layer and no micelle is formed.The molecular diffusion coefficient of surfactin in water solution with electric neutrality is estimated to be 0.428×10 -5 cm 2 ·s -1 by molecular dynamics simulation.The model developed can describe the complex interplay of adsorption kinetics,fluid dynamics,and mass-transfer phenomena based on the assumption of no radial temperature and concentration gradients,and is of adequate precision.The work involved in this paper is valuable for the optimization of the production process of surfactin.     

合成气制二甲醚三相淤浆床反应器的数学模型研究

A mathematical model for a bubble column slurry reactor is presented for dimethyl ether synthesis from syngas. Methanol synthesis from carbon monoxide and carbon dioxide by hydrogenation and the methanol dehydration are considered as independent reactions, in which methanol, dimethyl ether and carbon dioxide are the key components. In this model, the gas phase is considered to be in plug flow and the liquid phase to be in partly back mixing with axial distribution of solid catalyst. The simulation results show that the axial dispersion of solid catalysts, the operational height of the slurry phase in the bubble column slurry reactor, and the reaction results are influenced by the reaction temperature and pressure, which are the basic data for the scale-up of reactor.     

A Reynolds mass flux model for gas separation process simulation:II. Application to adsorption on activated carbon in a packed column☆

Simulations of adsorption process using the Reynolds mass flux model described in Part I of these serial articles are presented. The object of the simulation is the methylene chloride adsorption in a packed column (0.041 m id, packed with spherical activated carbon up to a length of 0.2 m). With the Reynolds mass flux model, breakthrough/regeneration curves, concentration and temperature as well as the velocity distributions can be obtained. The simulated results are compared with the experimental data reported in the literature and satisfactory agreement is found both in breakthrough/regeneration curves and temperature curves. Moreover, the anisotropic turbulent mass diffusion is characterized and discussed.     

对二甲苯鼓泡塔氧化过程的实验研究

以醋酸为溶剂,醋酸钴、醋酸锰为催化剂,溴化物为促进剂,在实验室鼓泡塔式反应器中,进行了对二甲苯(PX)氧化生成对苯二甲酸(TA)的工艺过程的研究,考察了氧化反应温度、压力、催化剂浓度、溶剂比等条件对粗对苯二甲酸(TA)产品中对甲基苯甲酸(p-TA)和对羧基苯甲醛(4-CBA)两种主要杂质含量以及产品粒度的影响。为工业装置对苯二甲酸产品粒度的改善和杂质含量的降低提供基础实验数据。     

PTA装置溶剂脱水塔模拟及塔板效率分析

精对苯二甲酸装置溶剂脱水塔在去除氧化反应生成水,保持整个氧化单元水含量稳定,减少醋酸消耗中起到核心作用。基于ASPEN PLUS流程模拟软件,以模型计算偏差最小为目标,通过调整板效率,实现溶剂脱水塔的模拟,为溶剂脱水塔的优化调整提供了基础。同时,分析主要参数之间的相关性,以及对各塔板成分板效率的影响,结果表明:塔负荷与塔压降之间存在线性相关;塔压降对夹带剂醋酸正丙酯的板效率影响较大,对水、对二甲苯、醋酸和醋酸甲酯的影响很小。     

PX氧化反应过程多变量预测控制

精对苯二甲酸(purified terephthalic acid,PTA)是我国最重要的化工原料之一。对二甲苯(p-xylene,PX)氧化反应器是PTA装置的核心运行设备,PX氧化反应是高温高压下的固液相催化反应,其关系到整个装置的产量和消耗。目前,PX氧化反应过程的常规控制虽然可以满足工业装置的生产,但关键产品指标粗对苯二甲酸中对羧基苯甲醛(4-carboxybenzaldehyde,4-CBA)含量和尾气氧浓度波动范围较大,不利于工业装置的进一步优化操作。本文利用FRONT-Suite先进控制软件进行了工业PTA装置PX氧化反应过程的多变量预测控制,稳定优化了关键控制指标反应器尾氧浓度和第一结晶器尾氧浓度以及质量指标4-CBA含量的控制,取得了显著的控制效果。     

PTA装置氧化单元结晶器的模拟研究

利用PRO/II模拟软件,对精对苯二甲酸(PTA)装置对二甲苯(PX)氧化单元结晶器进行了模拟研究,建立了对苯二甲酸(TA)晶体的结晶动力学模型以及第一结晶器、第二结晶器和第三结晶器的模拟模块,并进行了其应用分析。结果表明:模拟结果与设计数据的偏差在可接受的范围内,可以应用于PTA装置的工程设计;利用结晶器模拟模块,可得到结晶器的TA晶体生成量和TA粒径随结晶器温度和体积的变化规律;对于采用的BP-AMOCO工艺的PTA装置,在最优温度和压力条件下以单个结晶器代替串接的3台结晶器进行生产不一定具有优势。     

对苯二甲酸和对羧基苯甲醛在醋酸水溶液中的溶解度

测定了420-505K温度范围内,对苯二甲酸和对羧基苯甲醛在醋酸水溶液中溶解度。在70%-100%醋酸水溶液中,70%醋酸使对苯二甲酸的溶解度对温度最敏感,随着醋酸浓度增加,对苯二甲酸的溶解度减少。当温度低于470K时,对苯二甲酸在水中的溶解性低于醋酸中的溶解度;温度高于470K时,对苯二甲酸在水中的溶解性对温度敏感明显提高。40%醋酸使对羧基苯甲醛的溶解度对温度最敏感, 随着醋酸浓度增加, 对羧基苯甲醛的溶解度增加。实验数据用修正的Apelblat方程进行了对苯二甲酸和对羧基苯甲醛在醋酸水溶液中溶解度关联,计算与实验值吻合良好。     

PTA生产中4-CBA浓度的影响因素分析和软测量

根据济南化纤公司75 kt／a精对苯二甲酸(PTA)的生产工艺,建立了对二甲苯(PX)氧化反应器的数学模型,模型能够较好地预测不同工艺条件下的对羧基苯甲醛(4-CBA)浓度。在此模型基础上,对现有工艺过程进行了数值模拟,结果发现,4-CBA浓度与尾气CO_2浓度和单位液相体积耗氧速率具有很强的相关性。通过数据回归得到了4-CBA软测量模型,该软测量模型结果与工业运行实测结果基本一致     

丙烯酸甲酯-甲醇-水体系逆流萃取过程的模拟

基于某丙烯酸甲酯厂甲醇萃取过程的实际运行数据与实际转盘塔的形式结构,计算了实际转盘塔的理论级数。使用Aspen Plus流程模拟软件,通过对进料组分合理的简化,建立了能够良好描述该萃取设备实际运行工况的模型,并实现了丙烯酸甲酯生产工艺中的萃取塔T303的流程模拟。结果表明,在逆流萃取级数n=3时,模拟结果与实际数据基本吻合。在所建模型基础上,研究了温度、萃取相比、理论级数等操作条件对萃取结果的影响。通过分析和比较不同条件下的模拟结果,提出了能够提高产品质量的建议,也为丙烯酸甲酯生产工艺改造与扩大生产提供了理论依据。     

反应与精馏耦合水解醋酸甲酯(英文)

A process composed of a fixed-bed and a distillation column with a side withdraw, mainly methanol, is developed to hydrolyze methyl acetate (MA) as a typical byproduct in polyvinyl alcohol (PVA) and pure terephthalic acid (PTA) factory. The process is simulated by employing the equilibrium stage model RadFrac and plug flow model Rplug in Aspen Plus. Experiments are also carried out in a lab-scale to evaluate the process. The results show that at the molar ratio of water to methyl acetate about 4.0-5.0 in the feed stream and the volume ratio of distillate to feed MA above a critical value, the side product contains more than 80% (by mass) (MeOH) and less than 2% (by mass) MA, while the bottom contains more than 46% (by mass) acetic acid (HAc) and less than 0.5% (by mass) methanol with almost complete conversion of MA. Compared with the old catalytic distillation process we proposed before, this process can cut down 47.6% energy consumption and a distillation column.     

A kinetic study of the reaction between terephthalic acid and ethylene oxide at atmospheric pressure

The kinetics of the reaction of terephthalic acid with ethylene oxide, in n-butanol solvent, catalysed by triethyl amine, were investigated in a semi-batch reactor under atmospheric conditions. It was found that the reaction occurred in the liquid phase and that mass transfer effects were absent. The reaction was found to be pseudo-zero order in terephthalic acid and first order in ethylene oxide and in catalyst concentration. The effects of reaction temperature, catalyst concentration, particle size of terephthalic acid, ethylene oxide flow rate, stirrer speed and terephthalic acid to ethylene oxide ratio were studied. Particle size of terephthalic acid, stirrer speed and flow rate of ethylene oxide did not affect the reaction rate. The Arrhenius activation energy of the reaction was found to be between 19.2 and 23.5 kcal/mol.