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Distillation Column (distillation + column)
Kinds of Distillation Column Selected AbstractsA Short Note on Steady State Behaviour of a Petlyuk Distillation Column by Using a Non-Equilibrium Stage ModelTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2006Erika Fabiola Abad-Zarate Abstract A Petlyuk distillation column, considering equilibrium and non-equilibrium stage models, was studied. Rigorous simulations were conducted using Aspen PlusÔ RATEFRAC Module for the separation of ternary mixtures. According to the equilibrium model, the energy-efficient design of the Petlyuk column requires that the intermediate component be extracted from the maximum point in the composition profile in the main column. It was found that, for the intermediate component, mass transfer occurs from the vapour to the liquid phase from the top of the column to the stage where the side stream is extracted, from this point mass transfer occurs in the opposite direction. This point, considering the non-equilibrium model, corresponds to the stage in which the net mass transfer rate is zero. For the case of two segments per stage, it was found that the heat duties predicted by the equilibrium model are significantly lower than those obtained by using the non-equilibrium model, which is consistent with previous reported results. However, it is important to say that despite the higher energy duty predicted by the non-equilibrium model; both models predict significant energy savings. On a étudié une colonne de distillation de Petlyuk en considérant des modèles d'étage en équilibre et hors équilibre. Des simulations rigoureuses ont été menées au moyen du module RATEFRAC d'Aspen PlusÔ pour la séparation de mélanges ternaires. Selon le modèle en équilibre, une conception énergétiquement efficace de la colonne Petlyuk nécessite que le composant intermédiaire soit extrait du point maximum du profil de composition dans la colonne principale. On a trouvé que, pour le composant intermédiaire, le transfert de masse se produisait de la vapeur vers le liquide de la tête de la colonne jusqu'à l'étage où le courant secondaire est extrait; à partir de ce point le transfert de masse se produit dans la direction opposée. Ce point, en considérant le modèle hors équilibre, correspond à l'étage où le taux de transfert de masse net est nul. Dans le cas où il y a deux segments par étage, on a trouvé que les rendements thermiques prédits par le modèle en équilibre étaient significativement plus faibles que ceux obtenus à l'aide du modèle hors équilibre, ce qui est cohérent avec les résultats existants. Cependant, il est important de préciser que malgré le rendement énergétique plus élevé prédit par le modèle hors équilibre, les deux modèles fournissent des économies d'énergie significatives. [source] A Study on Increasing Separation Efficiency of an Industrial, Compound Distillation ColumnASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1-2 2002Shengjing Mu Simulation of a multistage distillation column is often required for its design and operation A debottieneck study for an acetic acid (HAc) dehydration column is presented in this paper. The column is consists of 4 structured packing sections at the top, a sieve tray section with smaller diameter in the middle, and a sieve tray section with larger diameter at the bottom By using steady-state simulation, the bottleneck to increasing the efficiency of separation is identified to be the middle sieve tray section with smaller diameter and smaller tray spacing Renovation schemes without any additional investment on equipment are proposed [source] Operational Optimization of Ideal Internal Thermally Coupled Distillation ColumnsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1-2 2001Xing-Gao Liu Lack of the optimal operation parameters in operation is one of major difficulties associated with the use of advanced energy saving distillation methods. In this paper, the operational optimization of the ideal Internal Thermally Coupled Distillation Column (ITCDIC) is considered. An optimization model and the related simulation algorithm are proposed. An optimization and the related result analysis are carried out, which pave the way for further design studies and its practical application. [source] Dynamic Simulation and Control of an MTBE Catalytic Distillation ColumnASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3-4 2000H. Lin A dynamic model of an MTBE (methyl tert butyl ether) catalytic distillation column was developed using the SpeedUp simulation package. Experimental kinetic rate data, rigorous thermodynamics, vapour-liquid nonidealities and tray hydraulics were incorporated in the simulation. The steady state results from the dynamic model were compared with the steady state results from a steady state model developed using the AspenPlus simulation package. The steady state results from the two simulations were in perfect agreement with each other. Open hop step tests were performed on the dynamic model of this process and the process model indicated a non-linear, self-regulating behaviour and did not exhibit any multiplicities. Multiloop linear control systems were designed and PI, PID and Dynamic Matrix Control (DMC) controllers were tested on the simulation for load disturbances and setpoint changes. All controllers performed adequately; the DMC controller consistently resulted in better dynamic control performance than the other two controllers. [source] Operational Optimization of Ideal Internal Thermally Coupled Distillation ColumnsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1-2 2001Xing-Gao Liu Lack of the optimal operation parameters in operation is one of major difficulties associated with the use of advanced energy saving distillation methods. In this paper, the operational optimization of the ideal Internal Thermally Coupled Distillation Column (ITCDIC) is considered. An optimization model and the related simulation algorithm are proposed. An optimization and the related result analysis are carried out, which pave the way for further design studies and its practical application. [source] Dividing Wall Distillation Columns: Optimization and Control PropertiesCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 9 2008F. I. Gómez-Castro Abstract The optimal design of dividing wall columns is a non-linear and multivariable problem, and the objective function used as optimization criterion is generally non-convex with several local optimums. Considering this fact, in this paper, we studied the design of dividing wall columns using as a design tool, a multi-objective genetic algorithm with restrictions, written in MatlabTM and using the process simulator Aspen PlusTM for the evaluation of the objective function. Numerical performance of this method has been tested in the design of columns with one or two dividing walls and with several mixtures to test the effect of the relative volatilities of the feed mixtures on energy consumption, second law efficiency, total annual cost, and theoretical control properties. In general, the numerical performance shows that this method appears to be robust and suitable for the design of sequences with dividing walls. [source] Effects of Liquid Holdup in Condensers on the Start-Up of Reactive Distillation ColumnsCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 11 2006H.-X. Wu Abstract Compared with start-ups in conventional distillation columns, those in reactive distillation (RD) columns are much more time and energy consuming, and generate a large amount of by-products which are not easy to deal with together. For several years, researchers have been trying out different methods to shorten the time required to lower the cost of the start-up. In this work, a rigorous dynamic model in the ChemCAD simulator is applied to model the start-up process for the esterification of ethyl acetate in a reactive distillation column. In the model, two sets of equations are employed: one for the fill-up and heating stage and the other for the equilibration process which follows. In the fill-up and heating stage, fluctuation curves of the reboiler temperatures with respect to time which are similar to those for conventional distillation columns are observed, while in the equilibration process it is found that the increase of the liquid holdup volume in the condenser reduces the time required to reach steady state for the reactive column and decreases the liquid holdup volume in the reboiler at the equilibrium state. This shows that the liquid holdup volume in the condenser has an important effect on the start-up of reactive distillation columns. [source] Performance improvements for olive oil refining plantsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 6 2010Elif Bozoglan Abstract The main objective of this study, which is conducted for the first time to the best of the authors' knowledge, is to identify improvements in olive oil refinery plants' performance. In the analyses, the actual operational data are used for performance assessment purposes. The refinery plant investigated is located in Izmir Turkey and has an oil capacity of 6250,kg,h,1. It basically incorporates steam generators, several tanks, heat exchangers, a distillation column, flash tanks and several pumps. The values for exergy efficiency and exergy destruction of operating components are determined based on a reference (dead state) temperature of 25°C. An Engineering Equation Solver (EES) software program is utilized to do the analyses of the plant. The exergy transports between the components and the consumptions in each of the components of the whole plant are determined for the average parameters obtained from the actual data. The exergy loss and flow diagram (the so-called Grassmann diagram) are also presented for the entire plant studied to give quantitative information regarding the proportion of the exergy input that is dissipated in the various plant components. Among the observed components in the plant, the most efficient equipment is found to be the shell- and tube-type heat exchanger with an exergy efficiency value of 85%. The overall exergetic efficiency performance of the plant (the so-called functional exergy efficiency) is obtained to be about 12%, while the exergy efficiency value on the exergetic fuel,product basis is calculated to be about 65%. Copyright © 2009 John Wiley & Sons, Ltd. [source] Single stage and double absorption heat transformers used to recover energy in a distillation column of butane and pentaneINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 14 2003W. Rivera This paper presents the theoretical analysis of the use of single stage and double absorption heat transformers operating with the water,lithium bromide mixture coupled to a butane and pentane distillation column in a Mexican refinery. A mathematical model of the heat transformers was developed in FORTRAN and integrated as a user model to the Aspen Plus simulation code. Both components coupled to the column were modelled on steady-state conditions. The results show that it is theoretically possible to reduce the energy consumed in the reboiler between 26 and 43% by the use of single stage heat transformer at specific conditions, and between 28 and 33% with double absorption heat transformers for a wide range of operating conditions. Copyright © 2003 John Wiley & Sons, Ltd. [source] Modelling of an ethanol-water distillation column assisted by an external heat pumpINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 12 2002S. B. M. Oliveira Abstract This paper presents a simulation of an ethanol,water distillation column assisted by a vapour-compression heat pump. The heat pump is of the external type, i.e., it uses a working fluid (refrigerant) different from that of the column. A simulation model was developed and four different working fluids were studied: R-11 and R-114 and, as substitutes, the column own fluids, water and ethanol. Results from the simulation model have shown that considerable reduction in energy consumption can be achieved with the installation of a heat pump. Copyright © 2002 John Wiley & Sons, Ltd. [source] Internal heat integration , the key to an energy-conserving distillation column,JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2-3 2003Z Olujic Abstract This paper illustrates the thermal energy conservation potential of the so-called heat integrated distillation column (HIDiC), which combines advantages of direct vapour recompression and diabatic operation at half of the normal column height. In a typical close boiling mixture separation, compared with a column utilising the usual vapour recompression scheme, HIDiC halved the consumption of exergy at approximately the same capital cost, indicating a strikingly short pay-off time. The complexities of integrating the heat transfer equipment in the stripping section with proven gas/liquid contacting devices, which may work adversely to practical implementation of HIDiC concept, are also addressed. © 2003 Society of Chemical Industry [source] Methodology for the design and evaluation of distillation systems: Exergy analysis, economic features and GHG emissionsAICHE JOURNAL, Issue 7 2010Hajnalka Kencse Abstract This work presents a process design methodology that evaluates the distillation systems based on exergetic, economic, and greenhouse gas (GHG) emission aspects. The aim of the methodology is to determine how these three features should be applied in process design to obtain information about the accuracy of the design alternatives. The methodology is tested and demonstrated on three different energy-integrated distillation systems: the direct sequence with backward heat-integration (DQB), fully thermally coupled distillation column (FTCDC), and sloppy distillation system with forward heat-integration (SQF). The average relative emission saving is the highest for the DQB scheme and this sequence shows the most flexible range of use. The case studies prove the accuracy of our evaluation methodology. On the other hand, it highlights and demonstrates that the exergy analysis can predict the results of the economic study and the environmental evaluation to make the decisions, associated with process design, much simpler. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Control of a high-purity ethylene glycol reactive distillation column with insights of process dynamicsAICHE JOURNAL, Issue 8 2009Kejin Huang Abstract Inventory control is often regarded as less important than product quality control in the operation of reactive and nonreactive distillation columns (i.e., often detuned considerably in control system design). For the high-purity ethylene glycol reactive distillation column, the inventory control of top condenser is, however, an exception and plays actually a crucial role in the stable and effective process operation, reminding the necessity to thoroughly investigate the intricate dynamic mechanism and its complicated implications on control system synthesis and design. In this article, the dynamics of a high-purity ethylene glycol reactive distillation column is examined, and it is found that the complicated dynamics, for example, the nonminimum phase behavior and process nonlinearity, can be suppressed considerably with the tight inventory control of the top condenser. Moreover, an extremely low controllability is detected, implying the potential difficulties in process operation and thus the need of process design modification. In terms of these insights obtained, two control schemes are devised and studied. It is demonstrated that sharp improvement could be acquired in control system performance when the tight inventory control has been implemented in the top condenser. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Computation of an extractive distillation column with affine arithmeticAICHE JOURNAL, Issue 7 2009Ali Baharev Abstract The need of reliably solving systems of nonlinear equations often arises in the everyday practice of chemical engineering. In general, standard methods cannot provide theoretical guarantee for convergence to a solution, cannot reliably find multiple solutions, and cannot prove nonexistence of solutions. Interval methods provide tools to overcome these problems, thus achieving reliability. To the authors' best knowledge, computation of distillation columns with interval methods have not yet been considered in the literature. This article presents significant enhancements compared with a previously published interval method of the authors. The proposed branch-and-prune algorithm is guaranteed to converge, and is fairly general at the same time. If no solution exists then this information is provided by the method as a result. Power of the suggested method is demonstrated by solving, with guaranteed convergence, even the MESH equations of a 22 stage extractive distillation column with a ternary mixture. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Approximate dynamic programming based optimal control applied to an integrated plant with a reactor and a distillation column with recycleAICHE JOURNAL, Issue 4 2009Thidarat Tosukhowong Abstract An approximate dynamic programming (ADP) method has shown good performance in solving optimal control problems in many small-scale process control applications. The offline computational procedure of ADP constructs an approximation of the optimal "cost - to - go" function, which parameterizes the optimal control policy with respect to the state variable. With the approximate "cost - to - go" function computed, a multistage optimization problem that needs to be solved online at every sample time can be reduced to a single-stage optimization, thereby significantly lessening the real-time computational load. Moreover, stochastic uncertainties can be addressed relatively easily within this framework. Nonetheless, the existing ADP method requires excessive offline computation when applied to a high-dimensional system. A case study of a reactor and a distillation column with recycle was used to illustrate this issue. Then, several ways were proposed to reduce the computational load so that the ADP method can be applied to high-dimensional integrated plants. The results showed that the approach is much more superior to NMPC in both deterministic and stochastic cases. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Backstepping-based cascade control scheme for batch distillation columnsAICHE JOURNAL, Issue 9 2004Rosendo Monroy-Loperena Abstract Nonstationary dynamics, finite-time operation, large thermodynamical uncertainty and delayed composition measurements make the control of batch distillation processes a challenging and interesting problem. In this paper, a cascade control design to regulate the overhead composition of a batch distillation column is presented. The controller is designed within the framework of robust nonlinear control with modeling error compensation techniques in conjunction with a backstepping approach. The result is a cascade controller with a master loop that, driven by the composition regulation error, produces a time-varying set point for the temperature in a certain tray; and with a secondary controller that manipulates the internal reflux ratio to track the time-varying set point determined by the master composition loop. How to extend the controller design to have multiple slave temperature controllers, to improve the regulation of the overhead composition in a batch distillation column, is also presented. The proposed control approach is illustrated by numerical simulations on a full dynamical model. © 2004 American Institute of Chemical Engineers AIChE J, 50: 2113,2129, 2004 [source] New approach to refinery process simulation with adaptive composition representationAICHE JOURNAL, Issue 3 2004Heiko Briesen Abstract The established technique for simulation of refinery processes is the use of pseudocomponents. However, in order to increase the economical benefit of plant operation, it seems inevitable to include molecular information in petroleum mixtures characterization. This will lead to a strong increase of problem size. For this new class of models, there currently seems to be no special algorithms available. The classic pseudocomponent approach is compared with a newly developed solution strategy, which is explicitly developed to efficiently solve simulation problems with a high detail in composition representation. The new solution strategy is an adaptive multigrid method based on a wavelet,Galerkin discretization. With the wavelet,Galerkin discretization the model can easily be formulated on various levels of detail. In an iterative procedure the multigrid concept exploits these different formulations to construct correction-term approximations to the true solution. The discretization of these correction-term models is now done with a detail in composition representation that is determined by a residual-based adaptation strategy. The proposed method has been implemented for a simple 9-stage distillation column and tested for a variety of feed mixtures. In all investigated tests the proposed method proved to be superior to the conventional pseudocomponent approach in terms of accuracy and efficiency. © 2004 American Institute of Chemical Engineers AIChE J, 50: 633,645, 2004 [source] Input design for model order determination in subspace identificationAICHE JOURNAL, Issue 8 2003Pratik Misra Subspace identification methods require that the inputs to the process being identified be persistently exciting. This may be inadequate for subspace identification of ill-conditioned multivariable processes, because the process model order may be underestimated, leading to subsequent identification of poor models. To remedy the problem, it is proposed that inputs must be used that excite a process to be identified in a way that produces as uncorrelated process outputs as possible. This can be accomplished either in open or in closed-loop fashion. Simulations on a high-purity distillation column and on a heat exchanger illustrate the merit of the proposed approach. [source] Multicomponent thermally coupled systems of distillation columns at minimum refluxAICHE JOURNAL, Issue 12 2001Zbigniew T. Fidkowski A method for calculating the minimum vapor flow in a ternary fully thermally coupled system of distillation columns was developed earlier by Fidkowski and Krolikowski. This method was developed further for fully thermally coupled systems separating four or more components. For multicomponent mixtures having constant relative volatilities and equal latent heats, the method leads to the identification of all of the minimum vapor flow rates in each distillation column that provide the same overall minimum heat duty in the reboiler. The quaternary fully coupled system of columns requires less heat energy than conventional configurations. These savings are often on the order of 20,50%. [source] Effect of number of fractionating trays on reactive distillation performanceAICHE JOURNAL, Issue 12 2000Muhammad A. Al-Arfaj Sneesby et al. recently suggested that adding trays in the stripping and rectifying sections of a reactive distillation column can degrade performance. This effect, if true, is not only counterintuitive, but very disturbing because it suggests that the design of reactive distillation columns cannot use conservative estimates of tray numbers, that is, we cannot simply add excess trays, as in conventional distillation. The problem is compounded by the uncertainty in vapor,liquid equilibrium data and tray efficiencies. This implies that developing reactive distillation columns would require extensive experimental work at the pilot-plant and plant stages to find the numbers of stages offering the best performance. Such a scenario would mean long and expensive development programs. This article explores the effect of the number of trays in the rectifying and/or stripping sections of reactive (catalytic) distillation columns. Three reactive distillation systems are used: an ideal hypothetical system, the ETBE system, and the methyl acetate system. Contrary to the published results, it is demonstrated that additional trays do not degrade performance. Two degrees of freedom available in all cases must be carefully chosen for fair comparisons. [source] Two-step procedure for data-based modeling for inferential control applicationsAICHE JOURNAL, Issue 10 2000Raja Amirthalingam A two-step procedure for building an inferential control model, which uses both historical operation data and plant test data, is proposed. Motivation for using the two types of data is given, and a systematic way to combine them in the model-identification step is proposed. Some potential problems associated with the procedure in practice and their solutions are discussed. The efficacy of the procedure is demonstrated in a case study involving a multicomponent distillation column simulated in HYSYS. [source] A Short Note on Steady State Behaviour of a Petlyuk Distillation Column by Using a Non-Equilibrium Stage ModelTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2006Erika Fabiola Abad-Zarate Abstract A Petlyuk distillation column, considering equilibrium and non-equilibrium stage models, was studied. Rigorous simulations were conducted using Aspen PlusÔ RATEFRAC Module for the separation of ternary mixtures. According to the equilibrium model, the energy-efficient design of the Petlyuk column requires that the intermediate component be extracted from the maximum point in the composition profile in the main column. It was found that, for the intermediate component, mass transfer occurs from the vapour to the liquid phase from the top of the column to the stage where the side stream is extracted, from this point mass transfer occurs in the opposite direction. This point, considering the non-equilibrium model, corresponds to the stage in which the net mass transfer rate is zero. For the case of two segments per stage, it was found that the heat duties predicted by the equilibrium model are significantly lower than those obtained by using the non-equilibrium model, which is consistent with previous reported results. However, it is important to say that despite the higher energy duty predicted by the non-equilibrium model; both models predict significant energy savings. On a étudié une colonne de distillation de Petlyuk en considérant des modèles d'étage en équilibre et hors équilibre. Des simulations rigoureuses ont été menées au moyen du module RATEFRAC d'Aspen PlusÔ pour la séparation de mélanges ternaires. Selon le modèle en équilibre, une conception énergétiquement efficace de la colonne Petlyuk nécessite que le composant intermédiaire soit extrait du point maximum du profil de composition dans la colonne principale. On a trouvé que, pour le composant intermédiaire, le transfert de masse se produisait de la vapeur vers le liquide de la tête de la colonne jusqu'à l'étage où le courant secondaire est extrait; à partir de ce point le transfert de masse se produit dans la direction opposée. Ce point, en considérant le modèle hors équilibre, correspond à l'étage où le taux de transfert de masse net est nul. Dans le cas où il y a deux segments par étage, on a trouvé que les rendements thermiques prédits par le modèle en équilibre étaient significativement plus faibles que ceux obtenus à l'aide du modèle hors équilibre, ce qui est cohérent avec les résultats existants. Cependant, il est important de préciser que malgré le rendement énergétique plus élevé prédit par le modèle hors équilibre, les deux modèles fournissent des économies d'énergie significatives. [source] Enhancing Controller Performance via Dynamic Data ReconciliationTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2005Shuanghua Bai Abstract Measured values of process variables are subject to measurement noise. The presence of measurement noise can result in detuned controllers in order to prevent excessive adjustments of manipulated variables. Digital filters, such as exponentially weighted moving average (EWMA) and moving average (MA) filters, are commonly used to attenuate measurement noise before controllers. In this article, we present another approach, a dynamic data reconciliation (DDR) filter. This filter employs discrete dynamic models that can be phenomenological or empirical, as constraints in reconciling noisy measurements. Simulation results for a storage tank and a distillation column under PI control demonstrate that the DDR filter can significantly reduce propagation of measurement noise inside control loops. It has better performance than the EWMA and MA filters, so that the overall performance of the control system is enhanced. Les valeurs mesurées des variables de procédé sont affectées par les bruits de mesure. La présence de bruit de mesure force de régler à la baisse les régulateurs afin de prévenir des mouvements excessifs des variables manipulées. Des filtres numériques, tels que les filtres à moyenne mobile pondérée exponentiellement (EWMA) et les filtres à moyenne mobile (MA), sont communément utilisés pour atténuer le bruit de mesure avant les régulateurs. On présente dans cet article une autre approche, soit un filtre dynamique de réconciliation de données (DDR). Ce filtre emploie des modèles dynamiques discrets qui peuvent être phénoménologiques ou empiriques comme contraintes pour réconcilier les mesures bruitées. Les résultats de simulation pour un réservoir de stockage et une colonne à distiller utilisant un régulateur PI montrent que le filtre DDR peut réduire de manière significative la propagation du bruit de mesure dans les boucles de régulation. Sa performance est meilleure que celles des filtres EWMA ou MA, et par conséquent la performance globale du système de commande s'en trouve accrue. [source] Experimental validation of a high-gain observer for composition estimation in an ethanol,water distillation columnASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2009A. C. Téllez-Anguiano Abstract In this paper a high-gain observer used to estimate the product compositions in a distillation column for a non-ideal mixture (ethanol,water) through the tray temperature measurements is presented. The design of this observer is based on a simplified mathematical model. One of the main advantages of this observer is its constant gain, therefore its tuning depends only on choosing a few constant parameters satisfying some simple algebraic inequalities. The effectiveness of the proposed method is demonstrated through on-line experiments in a distillation pilot plant. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] A Study on Increasing Separation Efficiency of an Industrial, Compound Distillation ColumnASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1-2 2002Shengjing Mu Simulation of a multistage distillation column is often required for its design and operation A debottieneck study for an acetic acid (HAc) dehydration column is presented in this paper. The column is consists of 4 structured packing sections at the top, a sieve tray section with smaller diameter in the middle, and a sieve tray section with larger diameter at the bottom By using steady-state simulation, the bottleneck to increasing the efficiency of separation is identified to be the middle sieve tray section with smaller diameter and smaller tray spacing Renovation schemes without any additional investment on equipment are proposed [source] Dynamic Simulation and Control of an MTBE Catalytic Distillation ColumnASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3-4 2000H. Lin A dynamic model of an MTBE (methyl tert butyl ether) catalytic distillation column was developed using the SpeedUp simulation package. Experimental kinetic rate data, rigorous thermodynamics, vapour-liquid nonidealities and tray hydraulics were incorporated in the simulation. The steady state results from the dynamic model were compared with the steady state results from a steady state model developed using the AspenPlus simulation package. The steady state results from the two simulations were in perfect agreement with each other. Open hop step tests were performed on the dynamic model of this process and the process model indicated a non-linear, self-regulating behaviour and did not exhibit any multiplicities. Multiloop linear control systems were designed and PI, PID and Dynamic Matrix Control (DMC) controllers were tested on the simulation for load disturbances and setpoint changes. All controllers performed adequately; the DMC controller consistently resulted in better dynamic control performance than the other two controllers. [source] Analysis of Energy-Efficient Complex Distillation Options to Purify BioethanolCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 4 2008S. Hernández Abstract Three complex extractive distillation options were studied for the purification of a dilute mixture of ethanol and water. The first option uses an extractive distillation column and the other two options use thermally coupled extractive distillation sequences. The results indicate that the fully thermally coupled extractive option can reduce energy consumption by ca. 30,% compared to the scheme that uses an extractive distillation column. This fully thermally coupled extractive distillation sequence can produce ethanol as distillate with a mass fraction of 0.995, the entrainer as the bottoms product and a mixture of ethanol and water as the sidestream. [source] Effects of Liquid Holdup in Condensers on the Start-Up of Reactive Distillation ColumnsCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 11 2006H.-X. Wu Abstract Compared with start-ups in conventional distillation columns, those in reactive distillation (RD) columns are much more time and energy consuming, and generate a large amount of by-products which are not easy to deal with together. For several years, researchers have been trying out different methods to shorten the time required to lower the cost of the start-up. In this work, a rigorous dynamic model in the ChemCAD simulator is applied to model the start-up process for the esterification of ethyl acetate in a reactive distillation column. In the model, two sets of equations are employed: one for the fill-up and heating stage and the other for the equilibration process which follows. In the fill-up and heating stage, fluctuation curves of the reboiler temperatures with respect to time which are similar to those for conventional distillation columns are observed, while in the equilibration process it is found that the increase of the liquid holdup volume in the condenser reduces the time required to reach steady state for the reactive column and decreases the liquid holdup volume in the reboiler at the equilibrium state. This shows that the liquid holdup volume in the condenser has an important effect on the start-up of reactive distillation columns. [source] Online-Analytik zur Prozessführung,CHEMIE-INGENIEUR-TECHNIK (CIT), Issue 10 2004G. Dünnebier Dr. Abstract Sichere, leistungsfähige und damit auch wirtschaftlich optimale Prozessführung in der chemischen Industrie ist mehr denn je auf Messdaten aus den betreffenden Prozessen angewiesen. Zunehmend werden zur Regelung stoffspezifische Informationen, z.,B. Sätze von Einzelstoffkonzentrationen, eingesetzt. Die Online-Analytik birgt in Kombination mit Prozessführung ein enormes wirtschaftliches Potenzial. Es ist jedoch ein steiniger Weg, der zur Ausschöpfung dieses wirtschaftlichen Potenzials führt, weshalb die Zahl der realisierten Anwendungen erst in den letzten Jahren stetig wächst. Der zentrale Teil dieses Beitrags veranschaulicht an Beispielen die Möglichkeiten, Online-Analytik und Prozessführung zu kombinieren, u.,a. anhand einer Batch-Destillationskolonne, einer kontinuierlichen destillativen Isomerentrennung sowie der Automatisierung einer kompletten Feinchemieanlage. Aus den Erfahrungen und Problemen der bisherigen Projekte lassen sich Wünsche und Regeln sowohl für die Definition und Abwicklung solcher Projekte in einem interdisziplinären Team als auch für die systemtechnische Anbindung der Online-Analytik an das Leitsystem ableiten. Online Analyzers for the Process Control Save, efficient, and economical operation of chemical processes more and more relies on online analyzers. The use of component properties (e.g., concentrations) for control becomes even more common. The combination of online analyzers and advanced control technologies holds an enormous economic potential, though a rocky path is leading there. As a result the number of existing applications is only growing slowly, but steadily. The main part of this contribution shows the potential of the combination of advanced control technologies and online analyzers using some illustrative examples like a batch distillation column, a continuous isomer distillation unit and the automation of a complete fine chemicals unit. Based on the experiences and problems encountered in the past projects, some guidelines and requests are formulated to optimize the definition and implementation of these projects in an interdisciplinary team and the integration of the online analyzers in a distributed control system. [source] Statistical analysis of catalyst degradation in a semi-continuous chemical production processJOURNAL OF CHEMOMETRICS, Issue 8 2001Eleftherios Kaskavelis Abstract The effect of decaying catalyst efficacy in a commercial-scale, semi-continuous petrochemical process was investigated. The objective was to gain a better understanding of process behaviour and its effect on production rate. The process includes a three-stage reaction performed in fixed bed reactors. Each of the three reaction stages consists of a number of catalyst beds that are changed periodically to regenerate the catalyst. Product separation and reactant recycling are then performed in a series of distillation columns. In the absence of specific measurements of the catalyst properties, process operational data are used to assess catalyst decay. A number of statistical techniques were used to model production rate as a function of process operation, including information on short- and long-term catalyst decay. It was found that ridge regression, partial least squares and stepwise selection multiple linear regression yielded similar predictive models. No additional benefit was found from the application of non-linear partial least squares or Curds and Whey. Finally, through time series profiles of total daily production volume, corresponding to individual in-service cycles of the different reaction stages, short-term catalyst degradation was assessed. It was shown that by successively modelling the process as a sequence of batches corresponding to cycles of each reaction stage, considerable economic benefit could be realized by reducing the maximum cycle length in the third reaction stage. Copyright © 2001 John Wiley & Sons, Ltd. [source] | ||||||||||