反应精馏合成乙酸丁酯的实验和模拟(英文)

In this paper, a reactive distillation (RD) column was applied for synthesis n-butyl acetate from n-butanol and acetic acid. The Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetic model and an equilibrium stage model for separation were employed to study the RD process. The results obtained from the equilibrium stage model agreed well with the experiments. The effects of operating variables on the n-butanol conversion and n-butyl acetate purity were further investigated. The optimal column configuration for the production of n-butyl acetate was designed with 5 rectifying stages, 8 reaction stages and 13 stripping stages by the simulation study. According to the simulation results, n-butanol conversion and n-butyl acetate purity all reached greater than 96%.     

用离子液体作催化剂和夹带剂时在反应萃取精馏塔中乙酸甲酯和正丁醇酯交换反应的模拟

A new reactive and extractive distillation process with ionic liquids as entrainer and catalyst (RED-IL) was proposed to produce methanol and n-butyl acetate by transesterification reaction of methyl acetate with n-butanol. The RED-IL process was simulated via a rigorous model, and high purity products of methanol and n-butyl acetate can be obtained in such a process. The effects of reflux ratio, feed mode, holdup, feed location, entrainer ratio and catalyst concentration on RED-IL process were investigated. The conversion of methyl acetate and purities of products increase with the holdup in column, entrainer ratio and catalyst content. An optimal reflux ratio exists in RED-IL process. Comparing to the mixed-feed mode, the segregated-feed mode is more effective, in which the optimal feed locations of reactants exist.     

Experimental and simulation of the reactive dividing wall column based on ethyl acetate synthesis

Reactive dividing wall column(RDWC) is a highly integrated unit which combines reaction distillation(RD) with dividing wall column separation technology into one shell, and it realized the chemical reaction and the separation of multiple product fractions simultaneously. In this paper, the reaction of esterification with acetic acid and ethanol to produce ethyl acetate was used as the research system, experiments and simulations of the RDWC were carried out. This system in the traditional process mostly used the homogeneous catalyst(e.g. sulfuric acid). However, in view of the corrosion of the equipment caused by the acidity of the catalyst, we used the heterogeneous catalysts – iron exchange resins – Amberlyst15 and proposed a novel catalyst loading method. Firstly,the reliability of the model of the simulation was verified by the experimental study on the change of liquid split ratio and reflux ratio. After that, the four-column model was established in Aspen Plus to analyze the effects of the amount of azeotropic agent, reflux ratio and acetic acid concentration. Finally, for a fair comparison, the economic analysis was conducted between traditional RD column and RDWC. The results showed that RDWC can save34.7% of total operating costs and 18.5% of TAC.     

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.     

工业PTA溶剂脱水过程动态模拟与分析

Dynamic model for dehydration process of industrial purified terephthalic acid solvent is investigated to understand and characterize the process.A temperature differential expression is presented,which ensures the equation to convergence and short computation time.The model is used to study the dynamic behavior of an azeotropic distillation column separating acetic acid and water using n-butyl acetate as the entrainer.Responses of the column to feed flow and aqueous reflux flow are simulated.The movement of temperature front is also simulated.The comparison between simulation and industrial values shows that the model and algorithm are effective.On the basis of simulation and analysis,control strategy,online optimization and so on can be implemented effectively in dehydration process of purified terephthalic acid solvent.     

矿物均相酸催化剂催化甲醇和乙酸酯化反应动力学(英文)

In this work, esterification of acetic acid and methanol to synthesize methyl acetate in a batch stirred reactor is studied in the temperature range of 305.15–333.15 K. Sulfuric acid is used as the homogeneous catalyst with concentrations ranging from 0.0633 mol·L?1 to 0.3268 mol·L?1. The feed molar ratio of acetic acid to methanol is varied from 1:1 to 1:4. The influences of temperature, catalyst concentration and reactant concentration on the reaction rate are investigated. A second order kinetic rate equation is used to correlate the experimental data. The forward and backward reaction rate constants and activation energies are determined from the Arrhenius plot. The developed kinetic model is compared with the models in literature. The developed kinetic equation is useful for the simulation of reactive distillation column for the synthesis of methyl acetate.     

三氯氢硅歧化反应精馏生产硅烷的模拟简

The reactive distillation process for producing high purity monosilane via trichlorosilane redistribution reaction was simulated. Rigorous RadFrac block was employed in Aspen Plus simulation package. Accurate results could be given when the chemical kinetics was taken into account in the equilibrium stage model. A single column process was used for the verification of previous studies. The results showed that 99.9% purity monosilane could be achieved in the reactive distillation. A pumparound block was employed to reduce the condenser duty with inexpen- sive coolant. The effects of operating pressure, feed stage location, liquid holdup per stage and pumparound loca- tion were also investigated. The energy consumption was limited, but the refrigerant temperature was too low, which is the fatal disadvantage. Therefore, a double columns process was developed to increase the condenser tem- perature. The simulation results demonstrated that a reasonable temperature could be achieved by varying the recy- cle stream location.     

ABSTRACTS

Simulation and Optimization of Extraction Dislillation Separation Process for Methyl Acetate - Methanol
In this paper, the simulation software ASPEN PLUS is used for the simulation calculation of methyl acetate - methanol extraction distillation process. Using NRTL thermodynamic model and RADFKAC rigorous method calculates the number of theoretical plates, the impact of feed location, solvent ratio, extraction solvent temperature, reflux ratio of extraction distillation process so as to find the optimum operating oarameters.     

Study on Hydrolysis of Methyl Acetate in a Catalytic Distillation Column

A nonequilibrium stage model was used to simulate countercurrent multicomponent catalytic distillation processes for methyl acetate hydrolysis. Computations of stage efficiencies or height equivalent to a theoretical plate (HETP) were entirely avoided by this model. The consistency of simulated results and experimental data in conversions and concentration of each component along a column indicates that the model predicts the actual process well. The influences of operating parameters on hydrolytic conversions, such as feed molar ratios, feed locations, feed and reflux rates, heights of reactive and stripping sections, were analyzed adequately by simulating calculations. A good operating mode was then obtained, which is helpful to the development of a new process.     

催化精馏塔中乙酸甲酯水解的研究

A nonequilibrium stage model was used to simulate countercurrent multicomponent catalytic distillation processes for methyl acetate hydrolysis. Computations of stage eiliciencies or height equivalent to a theoretical plate (HETP) were entirely avoided by this model. The consistency of simulated results and experimental data in conversions and concentration of each component along a column indicates that the model predicts the actual process well. The influences of operating parameters on hydrolytic conversions, such as feed molar ratios, feed locations, feed and reflux rates, heights of reactive and stripping sections, were analyzed adequately by simulating calcuiations. A good operating mode was then obtained, which is helpful to the development of a new process.     

用于生产TAEE的反应精馏和全蒸发的混合过程

In this study, a reactive distillation column in which chemical reaction and separation occur simultaneously is applied for the synthesis of tert-amyl ethyl ether （TAEE） from ethanol （EtOH） and tert-amyl alcohol （TAA）. Pervaporation, an efficient membrane separation technique, is integrated with the reactive distillation for enhancing the efficiency of TAEE production. A user-defined Fortran subroutine of a pervaporation unit is developed, allowing the design and simulation of the hybrid process of reactive distillation and pervaporation in Aspen Plus simulator. The performance of such a hybrid process is analyzed and the results indicate that the integration of the reactive distillation with the pervaporation increases the conversion of TAA and the purity of TAEE product, compared with the conventional reactive distillation.     

反应精馏过程中的多稳态分析

Reactive distillation processes for synthesis of ethylene glycol （EG） and ethyl tert-butyl ether （ETBE） were modeled with the simulation package ASPEN PLUS. The input multiplicity and output multiplicity were discussed with the method of sensitivity analysis for both cases. In EG production process, steady state multiplicities were studied in terms of effective liquid holdup volume and boil-up ratio. In ETBE synthesis process, the user kinetic subroutine was supplied into ASPEN PLUS firstly, and then the composition, temperature and reaction-rate profiles within the reactive distillation column were presented in detail. A set of stable solution branches based on distinct initial guesses for a range of boil-up ratio were found in EG synthesis. Input multiplicities were observed for a range of reboiler duty at several values of reflux ratio for ETBE synthesis process. These results can be used to avoid excessive energy consumption and achieve optimum design of reactive distillation column.     

用新离子交换树脂催化剂优化连续催化精馏塔中乙基叔丁基醚的合成(英文)

Liquid phase synthesis of one of the important fuel oxygenate, ethyl tert-butyl ether （ETBE）, from etha-nol and tert-butyl alcohol （TBA） has been studied in catalytic distillation column （CDC） using ion exchange resin catalyst CT-145H. A packed CDC of 1.2 m height and 50 mm diameter with indigenously developed reactive sec-tion packing was used to generate experimental data. Effect of different key variables on product purity in distillate, was investigated to find the optimum operating conditions for ETBE synthesis. The optimum conditions for 0.2 kg·s-1 of ethanol feed were found：reboiler duty of 375 W, molar feed ratio of 1︰1.3 of reactants, and reflux ratio of 7. Concentration profiles for each component along each column section at optimum conditions were also drawn. Neither output nor input multiplicity was observed at experimental conditions.     

Reactive dividing wall column for hydrolysis of methyl acetate:Design and control☆

Reactive distillation and dividing wall column distillation are two kinds of effective separation technologies, and their integrated configuration, reactive dividing wall column (RDWC), presents attractive advantages. In this study, the rigorous simulation of RDWC for methyl acetate hydrolysis is performed, and sensitivity analysis is conducted to obtain the minimum reboiler duty. Then a comparison is made between the conventional process and RDWC process, and it shows that 20.1%energy savings can be achieved by RDWC process. In addition, the dynamic characteristic of RDWC is studied and an effective control strategy is proposed. The simple PI control scheme with three temperature loops can obtain reasonable control performance and maintain products at de-sired purities. It is proved that this RDWC process is an energy efficiency alternative with good controllability. ? 2016 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. Al rights reserved.     

MPC of distillation column with side reactors for methyl acetate

This paper focuses on the dynamic control of distillation column with side reactors(SRC)for methyl acetate pro-duction.To obtain the optimum integrated structure and steady state simulation,the systematic design approach based on the concept of independent reaction amount is applied to the process of SRC for methyl acetate produc-tion.In addition to the basic control loops,multi-variable model predictive control modular with methyl acetate concentration and temperature of sensitive plate is designed.Then,based on process simulation software Aspen Plus,dynamic simulation of SRC for methyl acetate production is used to verify the effectiveness of the control scheme.     

Investigation of energy-efficient heat pump assisted heterogeneous azeotropic distillation for separating of acetonitrile/ethyl acetate/n-hexane mixture

The conventional distillation is hard to accomplish the separation of acetonitrile/ethyl acetate/n-hexane mixture. Herein, a heterogeneous azeotropic distillation(HAD) without adding entrainer is proposed to separate ternary mixture. The proposed scheme is optimized via the simulated annealing algorithm and minimum total annual cost(TAC) is used as objective functions. To minimize energy consumption,heat pump is added on the basis of optimal heterogeneous azeotropic distillation and heat integra...     

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.     

乙酸与甲醇的催化酯化

Esterification of methyl alcohol with acetic acid catalysed by Amberlyst-15 (cation-exchange resin) was carried out in a batch reactor in the temperature ranging between 318-338 K, at atmospheric pressure. The reaction rate increased with increase in catalyst concentration and reaction temperature, but decreased with an increase in water concentration. Stirrer speed had virtually no effect on the rate under the experimental conditions. The rate data were correlated with a second-order kinetic model based on homogeneous reaction. The apparent activation energy was found to be 22.9kJmol-1 for the formation of methyl acetate. The methyl acetate production was carried out as batch and continuous in a packed bed reactive distillation column with high purity methyl acetate produced.     

内部热耦合精馏塔基于非理想物系的最优评价

Internal thermally coupled distillation column(ITCDIC) is a frontier in energy saving distillation research. In this paper, the optimal assessment on the energy saving and the operating cost for ITCDIC of nonideal mixture is explored. An evaluating method is proposed, and the pertinent optimization model is then derived. The ethanol-water system is studied as an illustrative example. The optimization results show that the maximum energy saving in ITCDIC process is about 35% and the maximum operating cost saving in ITCDIC process is about 30%,as compared with a conventional distillation column(CDIC) under the minimum reflux ratio operating; the optimal operating pressure of the rectifying section is found to be around 0.25 MPa; the effects of the feed composition,operating pressure and the heat transfer rate on operation are also found and analyzed. It is revealed that ITCDIC process possesses high energy saving potential and promising economical prospect.     

乳酸提纯反应精馏新工艺非平衡级稳态模拟

Purification of lactic acid by reactive distillation (RD) is a novel technology which has many excellent characteristics compared with traditional technologies. This paper presented a non-equilibrium model for lactic acid purification RD pilot column. An Improved Separation Efficiency Function (ISEF) was proposed based on de-coupling and pseudo-homogenous assumptions, which greatly improved the solving efficiency and made this model suitable for practical application. Simulation results were consistent with the experiments in different conditions, and the simulation results outperformed the simulator ASPEN PLUS in which the equilibrium stage assumptions were adopted. The static characteristics of the pilot setup were also investigated. The analysis result could help to accelerate the commercialization of the lactic acid purification RD technology.