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1
Todd, Heather Elizabeth. "Investigating catalyst performance in batch reactive distillation." Thesis, University of Newcastle Upon Tyne, 2011. http://hdl.handle.net/10443/1244.
Full textAbstract:
Reactive distillation (RD) combines chemical synthesis with separation by distillation, but this leads to a non-trivial system: the hardware selection, the system components, the mode of operation and the operating conditions all affect the performance of the RD process. A key process development issue is the identification of suitable catalysts that perform well under reactive distillation conditions, as catalysts are crucial for increasing reaction rate when operating temperature range is limited by evaporation. The main goal of this research is to develop a method, utilizing high throughput technology, which can be used to assess many candidate catalysts for batch RD systems. The identification of potentially suitable catalysts should be made as early as possible, but before experimental work begins the only information available is the catalyst composition and structure. The approach taken in this research is to correlate catalyst properties to the performance in RD tests and the outputs from the dynamic simulations. The case study used is a batch reactive distillation for the esterification of a long-chain fatty acid. Potential catalysts are studied at small scale in a high throughput platform, and further investigation if performaed in an experimental batch RD unit. The most active of the screened catalysts, sulfuric acid and MSA also have the highest initial activity under RD. Heteropoly acids appear to have a good activity level, while ferric sulfate gives intermediate but apparently increasing activity. Some outcomes of the RD experiments were unexpected: the strong homogeneous acid catalysts entail low distillate water yield, and some metal acetates had higher activity than anticipated in the RD tests. This demonstrates that pilot scale experiments currently remain necessary for the evaluation of catalyst performance for RD processes. The insights gained from this study lead to key recommendations for future studies: an increased scope of study with a larger number of candidates which preferable have similar structure; evaluation of additional catalyst performance indicators, performed over the full operating temperature range; use of the smallest suitable experimental column; and more focus on physical factors such as solubility. Use of a simulator with an established physical property calculation tool is essential for successful simulations of batch RD.
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Bahar, Almila. "Modeling And Control Studies For A Reactive Batch Distillation Column." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608344/index.pdf.
Full textAbstract:
Modeling and inferential control studies are carried out on a reactive batch
distillation system for the esterification reaction of ethanol with acetic acid to
produce ethyl acetate. A dynamic model is developed based on a previous study
done on a batch distillation column. The column is modified for a reactive system
where Artificial Neural Network Estimator is used instead of Extended Kalman
Filter for the estimation of compositions of polar compounds for control purposes.
The results of the developed dynamic model of the column is verified theoretically
with the results of a similar study. Also, in order to check the model
experimentally, a lab scale column (40 cm height, 5 cm inner diameter with 8
trays) is used and it is found that experimental data is not in good agreement
with the models&rsquo. Therefore, the model developed is improved by using different rate expressions and thermodynamic models (fi-fi, combination of equations of state (EOS) and excess Gibbs free energy (EOS-Gex), gama-fi) with different equations of states (Peng Robinson (PR) / Peng Robinson - Stryjek-Vera (PRSV)), mixing rules (van der Waals / Huron Vidal (HV) / Huron Vidal Original (HVO) / Orbey Sandler Modification of HVO (HVOS)) and activity coefficient models (NRTL / Wilson / UNIQUAC). The gama-fi method with PR-EOS together with van der Waals mixing rule and NRTL activity coefficient model is selected as the best relationships which fits the experimental data. The thermodynamic models
EOS, mixing rules and activity coefficient models, all are found to have very crucial roles in modeling studies. A nonlinear optimization problem is also carried out to find the optimal operation of the distillation column for an optimal reflux ratio profile where the maximization of the capacity factor is selected as the objective function. In control studies, to operate the distillation system with the optimal reflux ratio profile, a control system is designed with an Artificial Neural Network (ANN) Estimator which is used to predict the product composition values of the system from temperature measurements. The network used is an Elman network with two hidden layers. The performance of the designed network is tested first in open-loop and then in closed-loop in a feedback inferential control algorithm. It is found that, the control of the product compositions with the help of an ANN estimator with error refinement can be done considering optimal reflux ratio profile.
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Edreder, E. A. "Modelling and optimisation of batch distillation involving esterification and hydrolysis reaction systems. Modelling and optimisation of conventional and unconventional batch distillation process: Application to esterification of methanol and ethanol using acetic acid and hydrolysis of methyl lactate system." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4296.
Full textAbstract:
Batch distillation with chemical reaction when takes place in the same unit is referred to
as batch reactive distillation process. The combination reduces the capital and operating
costs considerably. Among many different types of batch reactive distillation column
configurations, (a) conventional (b) inverted (c) semi-batch columns are considered
here.
Three reaction schemes such as (a) esterification of methanol (b) esterification of
ethanol (c) hydrolysis of methyl lactate are studied here. Four different types of
dynamic optimisation problems such as (a) maximum conversion (b) maximum
productivity (c) maximum profit and (d) minimum time are formulated in this work.
Optimal design and or operation policies are obtained for all the reaction schemes.
A detailed rigorous dynamic model consisting of mass, energy balances, chemical
reaction and thermodynamic properties is considered for the process. The model was
incorporated within the dynamic optimisation problems. Control Vector
Parameterisation (CVP) technique was used to convert the dynamic optimisation
problem into a nonlinear programming problem which was solved using efficient SQP
(Successive Quadratic Programming) method available within the gPROMS (general
PROcess Modelling System) software.
It is observed that multi-reflux ratio or linear reflux operation always led to better
performance in terms of conversion, productivity for all reaction schemes compared to
that obtained using single reflux operation.
Feed dilution (in the case of ethanol esterification) led to more profit even though
productivity was found to be lower. This was due to reduction in feed price because of
feed dilution. Semi-batch reactive distillation opertation (for ethanol esterification) led
to better conversion compared to conventional batch distillation, however, the total
amount of acetic acid (reactant) was greater in semi-batch operation. Optimisation of
design and operation (for ethanol esterification) clearly showed that a single cloumn
will not lead to profitable operation for all possible product demand profile. Also
change in feed and /or product price may lead to adjust the production target to
maximise the profitability.
In batch distillation, total reflux operation is recommended or observed at the begining
of the operation (as is the case for methnaol or ethanol esterification). However, in the
case of hydrolysis, total reflux operation was obseved at the end of the operation. This
was due to lactic acid (being the heaviest) was withrawn as the final bottom product.Libyan Petroleum Institute
4
Edreder, Elmahboub A. "Modelling and optimisation of batch distillation involving esterification and hydrolysis reaction systems : modelling and optimisation of conventional and unconventional batch distillation process : application to esterification of methanol and ethanol using acetic acid and hydrolysis of methyl lactate system." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4296.
Full textAbstract:
Batch distillation with chemical reaction when takes place in the same unit is referred to as batch reactive distillation process. The combination reduces the capital and operating costs considerably. Among many different types of batch reactive distillation column configurations, (a) conventional (b) inverted (c) semi-batch columns are considered here. Three reaction schemes such as (a) esterification of methanol (b) esterification of ethanol (c) hydrolysis of methyl lactate are studied here. Four different types of dynamic optimisation problems such as (a) maximum conversion (b) maximum productivity (c) maximum profit and (d) minimum time are formulated in this work. Optimal design and or operation policies are obtained for all the reaction schemes. A detailed rigorous dynamic model consisting of mass, energy balances, chemical reaction and thermodynamic properties is considered for the process. The model was incorporated within the dynamic optimisation problems. Control Vector Parameterisation (CVP) technique was used to convert the dynamic optimisation problem into a nonlinear programming problem which was solved using efficient SQP (Successive Quadratic Programming) method available within the gPROMS (general PROcess Modelling System) software. It is observed that multi-reflux ratio or linear reflux operation always led to better performance in terms of conversion, productivity for all reaction schemes compared to that obtained using single reflux operation. Feed dilution (in the case of ethanol esterification) led to more profit even though productivity was found to be lower. This was due to reduction in feed price because of feed dilution. Semi-batch reactive distillation opertation (for ethanol esterification) led to better conversion compared to conventional batch distillation, however, the total amount of acetic acid (reactant) was greater in semi-batch operation. Optimisation of design and operation (for ethanol esterification) clearly showed that a single cloumn will not lead to profitable operation for all possible product demand profile. Also change in feed and /or product price may lead to adjust the production target to maximise the profitability. In batch distillation, total reflux operation is recommended or observed at the begining of the operation (as is the case for methnaol or ethanol esterification). However, in the case of hydrolysis, total reflux operation was obseved at the end of the operation. This was due to lactic acid (being the heaviest) was withrawn as the final bottom product.
5
Aqar, Dhia Y. "Modelling and Optimization of Conventional and Unconventional Batch Reactive Distillation Processes. Investigation of Different Types Batch Reactive Distillation Columns for the Production of a Number of Esters such as Methyl Lactate, Methyl Decanoate, Ethyl Benzoate, and Benzyl Acetate using gPROMS." Thesis, University of Bradford, 2018. http://hdl.handle.net/10454/17139.
Full textAbstract:
The synthesis of a number of alkyl esters such as methyl lactate, methyl decanoate, and ethyl benzoate via esterification in a reactive distillation is quite challenging. It is due to the complexity in the thermodynamic behaviour of the chemical species in the reaction mixture in addition to the difficulty of keeping the reactants together in the reaction section. One of the reactants (in these esterification reactions) having the lowest boiling point can separate from the other reactant as the distillation continues. This can result in a significant drop in the reaction conversion in a conventional reactive distillation whether it is a batch or a continuous column.
To overcome this challenge, new different types of batch reactive distillation column configurations: (1) integrated conventional (2) semi-batch (3) integrated semi-batch (4) integrated dividing-wall batch distillation columns have been proposed here.
Four esterification reaction schemes such as (a) esterification of lactic acid (b) esterification of decanoic acid (c) esterification of benzoic acid (d) esterification of acetic acid are investigated here. A detailed dynamic model based on mass, energy balances, chemical reaction, and rigorous thermodynamic (chemical and physical) properties is considered and incorporated in the optimisation framework within gPROMS (general PROcess Modelling System) software.
It is found that for the methyl lactate system, the i-SBD operation outperforms the classical batch operations (CBD or SBD columns) to satisfy the product constraints. While, for the methyl decanoate system, the i-DWCBD operation outperforms all CBD, DWBD and sr-DWBD configurations by achieving the higher reaction conversion and the maximum product purity. For the ethyl benzoate system, the performance of i-CBD column is superior to the CBD process in terms of product quality, and conversion rate of acid. The CBD process is found to be a more attractive in terms of operating time saving, and annual profit improvement compared to the IBD, and MVD processes for the benzyl acetate system.The Higher Committee for Education Development in Iraq (HCED)
6
Martinez, Claudio de Lima Miguel. "State estimation for improved control in batch reaction and distillation processes." Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339553.
Full text
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Demicoli, Daniel. "Novel batch distillation processes for the separation of systems with and without chemical reaction." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=978975030.
Full text
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Masoud, Aboubaker Z. "Dynamic optimisation of batch distillation with and without chemical reaction with emphasis on product demand and operating cost : modelling conventional and unconventional batch distillation in gPROMS and operation parameters to maximise profitability whi." Thesis, University of Bradford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.511386.
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Edreder, E. A., Iqbal M. Mujtaba, and M. Emtir. "Optimal Operation of Batch Reactive Distillation Process Involving Esterification Reaction System." 2015. http://hdl.handle.net/10454/9141.
Full textAbstract:
NoThe performance of batch reactive distillation process involving the esterification of acetic acid with methanol to produce methyl acetate and water is considered in this work. Two cases studies with varying amount of the reactants are considered. The reflux ratio (single time interval) is selected as the control variable to be optimised (treated as piecewise constant) for different but fixed batch time ranging from 5 to 15 h, so as to maximise the conversion of methanol subject to product purity of methyl acetate. The dynamic optimisation problem is converted to a nonlinear programming problem by Control Vector Parameterization (CVP) technique and is solved by using efficient SQP method. The optimisation results show that as the methanol and methyl acetate are wide boiling, the separation of methyl acetate is easier without losing much of methanol reactant. The conversion improves by 6.4 % due to sufficient amount of acetic acid being reacted with methanol. Moreover an excess of acetic acid leads to high operation temperature and therefore high reflux operation (to reduce loss of methanol from the top of the column) to maximise the conversion.
10
Qi, Wei. "Synthesis, design and operating strategies for batch reactive distillation." 2010. https://scholarworks.umass.edu/dissertations/AAI3427600.
Full textAbstract:
Batch reactive distillation (BRD), combines the flexibility of batch processing with the advantages of reactive distillation and can offer advantages over conventional batch processing for small to medium volume production. BRD is also important in process development for reactive distillation. The essence of reactive distillation is the integration between reaction and distillation. There are two limiting cases for integration between reaction and distillation, (1) no integration and (2) full integration. In this thesis, we have shown that by analyzing these two limiting cases, and combining the information obtained from two limiting cases in a novel way, we can develop a partial integrated design with an appropriate amount of integration and an appropriate operation mode, which can provide advantages over both conventional design without integration and a fully integrated design. We apply this approach in two realistic examples, i.e. (1) isopropyl acetate synthesis and (2) 1, 1-dimethoxyethane production. For the isopropyl acetate synthesis, we compare the vapor-liquid and liquid-liquid features of the phase equilibrium to nbutyl acetate and amyl acetate systems, and show the similarities and differences among them. In particular, we show why the isopropyl system is more difficult than the others and how to use the known information in two limiting cases to develop a semi-batch reactive distillation (SBRD) with partial integration, which overcomes the reactive azeotrope brought by full integration and results in a more efficient process for the production of isopropyl acetate than has been previously known. In SBRD, the loss of isopropanol can be substantially decreased, the purity of water can be improved, and the total refluxing or recycling of organic distillate can be avoided. The resulting SBRD can provide 20% higher production efficiency than BRD. For the example of 1, 1-dimethoxyethane (DMA) synthesis, following the approach, we develop a partially integrated BRD, which can take advantage of integration to overcome the reaction equilibrium limitation, meanwhile avoid a distillation boundary brought by over-integration. This leads to a high-purity product, which is unattainable in a fully integrated reactive distillation process without special and expensive treatment of the methanol/DMA azeotrope. In this thesis, we also address selectivity issues in BRD, and provide new results describing the impact of key operating parameters: the reflux or reboil ratio and the Damköhler number (Da). We show that selectivity improvements in BRD are limited for high values of Da or for high values of the reflux or reboil ratio and that selectivity is enhanced as Da or reflux or reboil ratio is decreased. However, decreasing Da will cause conversion loss, which can be mitigated by increasing reflux ratio (or reboil ratio) at expense of selectivity. Consequently, there is an optimum value of reflux or reboil ratio that gives a maximum yield for systems operated at low or moderate Da. We show sample results for a system of serial isomerization reactions and for the synthesis of ethylene glycol. For the isomerization, we show that for BRD with a constant heating rate, the additional heat released by reaction can improve selectivity at expense of conversion. For ethylene glycol synthesis, we show that at a low reboil ratio, integration between reaction and distillation has a negative impact on both conversion and selectivity by causing separation of the reactants. We also show that decreasing the reboil ratio near the end of the BRD can increase the removal rate of ethylene glycol and thereby improve selectivity. This operating strategy is different from the common practice in distillation of increasing the reboil ratio near the end of a batch or cut.
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Kuo, Chia-Hung, and 郭佳紘. "Design of Heterogeneous Batch Reactive Distillation for Acetic Acid Esterification." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/58802914036956965470.
Full textAbstract:
碩士國立臺灣大學
化學工程學研究所
98
Batch distillation process has been widely used for small scale productions in pharmaceuticals, fine chemicals, and specialty chemicals. The latest batch reactive distillation (abbreviated as BReaD) combines the flexibility of batch distillation and the advantages of reactive distillation. This research studies policies for operating a heterogeneous BReaD process which has a lightest azeotrope in a two phase region. The policies include total organic reflux and zero aqueous discharge in the productions of butyl, isopropyl and ethyl acetates. From the proposed BReaD, the objective is aimed to obtain the esters from the bottom and high purity water from the top decanter. This study also discusses the effects of partial aqueous reflux and decanter charging strategies on the product compositions；This latter study is motivated by a small two-phase region in the ethyl acetate that does not include the azetrope. The decanter charging strategy has an opportunity to push the top vapor composition into the two phase region, which will then enhance the production of qualified product from a heterogeneous BReaD.
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Aqar, D. Y., Nejat Rahmanian, and Iqbal M. Mujtaba. "Feasibility of Integrated Batch Reactive Distillation Columns for the Optimal Synthesis of Ethyl Benzoate." 2017. http://hdl.handle.net/10454/13170.
Full textAbstract:
YesThe synthesis of ethyl benzoate (EtBZ) via esterification of benzoic acid (BeZ) with ethanol in a reactive distillation is challenging due to complex thermodynamic behaviour of the chemical reaction and the difficulty of keeping the reactants together in the reaction zone (ethanol having the lowest boiling point can separate from the BeZ as the distillation proceeds) causing a significant decrease in the conversion of BeZ in a conventional reactive distillation column (batch or continuous). This might be the reason of not reporting the use of reactive distillation for EtBZ synthesis although the study of BeZ esterification reaction is available in the public literature. Our recently developed Integrated Conventional Batch Distillation (i-CBD) column offers the prospect of revisiting such reactions for the synthesis of EtBZ, which is the focus of this work. Clearly, i-CBD column outperforms the Conventional Batch Distillation (CBD) column in terms of product amount, purity and conversion of BeZ and eliminates the requirement of excess use of ethanol. For example, compared with CBD column, the i-CBD operation can yield EtBZ at a much higher purity (0.925 compared to 0.730) and can convert more benzoic acid (93.57% as opposed to only 74.38%).
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Kao, Yu-Lung, and 高玉龍. "Design, Operation and Optimization of Batch Reactive Distillation with Off-Cut." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/76331701514261624091.
Full textAbstract:
博士國立臺灣大學
化學工程學研究所
104
Batch reactive distillation (BREAD) is an integrated process which combines the advantages of reactive distillation and the flexibility of batch processes. Off-cut is commonly applied in non-reactive batch distillation to improve the performance. However, reports of the application of off-cut for BREAD are quite rare. In this thesis, several aspects of design and operation of BREAD processes with off-cut are studied. A hypothetical reaction system considered previously (Kao, Y. L. Effect of Relative Volatility Ranking on the Design and Operation of Batch Reactive Distillation System. Master Thesis. National Taiwan University, Taipei, Taiwan, 2010) is used to develop the optimal operation policy without off-cut. In addition, the effect of changing product purity specifications and reaction equilibrium constants is also investigated. Compared with the previous results, the new results show that using off-cut can improve performance in terms of batch capacity (CAP), especially when both reactants have boiling points between those of the two products, when the product purity is high, and when the reaction equilibrium constant is low. A real case study, hydrolysis of methyl lactate, is also investigated to validate the results from the ideal system study. Next, methods for improving the operation of BREAD with off-cut are presented. Although off-cut can improve the operation of batch reactive distillation, its usefulness is limited in some cases due to the relative volatility ranking of reactants and products. In these cases, performance can be improved by using a middle vessel column or by using an excess of one reactant. These methods are demonstrated with case studies of three processes with realistic reaction kinetics and vapor-liquid equilibrium models: hydrolysis of methyl lactate, esterification of formic acid, and production of 1,1-dimethoxyethane. CAP can be improved on average 41.9 percent if the appropriate method is employed. Off-cut recycling in BREAD processes is then studied. The strategy is to recycle off-cut to the next batch as a part of the initial feed. This transforms the operation problem from single batch problem into a batch-to-batch problem. The pseudo-steady-state concept is applied to BREAD processes to simplify the optimization problem. Optimization based on maximizing CAP for the batch-to-batch problem is demonstrated using three real chemistry processes. The results show that the optimal operating recipe and CAP when off-cut is recycled are similar to the case when off-cut is collected but not recycled, and the CAP is on average almost twice (93.3% more) the maximum that can be achieved when off-cut is not used. Therefore, recycling off-cut may not only save the trouble of processing the off-cut, but also make the process more economical. Last, simultaneous optimization of equipment design and process operation is investigated for BREAD processes. The minimal total annual cost problem is illustrated with two realistic chemical systems, hydrolysis of methyl lactate and esterification of formic acid. The effect of design and operating variables on TAC is investigated. The optimization results suggest that a reflux policy which maintains constant distillate composition can provide nearly optimal operation. The column should be designed with an adequate number of stages so that the CAP improvement by further increasing the number of stages is insignificant. Vapor boilup rate should be specified to make the best use of the available operating time, and the optimal vapor boilup rate is primarily affected by the catalyst loading. The insight into the effect of process design variables on design performance is used to develop an efficient algorithm for determining simultaneously the optimal column design and operating policy.
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Aqar, D. Y., Nejat Rahmanian, and Iqbal M. Mujtaba. "Integrated Batch Reactive Distillation Column Configurations for Optimal Synthesis of Methyl Lactate." 2016. http://hdl.handle.net/10454/8802.
Full textAbstract:
YesAlthough batch reactive distillation process outperforms traditional reactor-distillation processes due to simultaneous reaction and separation of products for many reaction systems, synthesis of Methyl lactate (ML) through esterification of lactic acid (LA) with methanol in such process is very challenging due to difficulty of keeping the reactants together when one of the reactants (in this case methanol) has the lowest boiling point than the reaction products. To overcome this challenge, two novel reactive distillation column configurations are proposed in this work and are investigated in detail. These are: (1) integrated conventional batch distillation column (i-CBD) with recycled methanol and (2) integrated semi-batch and conventional batch distillation columns (i-SBD) with methanol recovery and recycle. Performances of each of these configurations are evaluated in terms of profitability for a defined separation task. In i-SBD column, an additional constraint is included to avoid overflow of the reboiler due to continuous feeding of methanol into the reboiler as the reboiler is initially charged to its maximum capacity. This study clearly indicates that both integrated column configurations outperform the traditional column configurations (batch or semi-batch) in terms of batch time, energy consumption, conversion of LA to ML, and the achievable profit.
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Aqar, D. Y., Nejat Rahmanian, and Iqbal M. Mujtaba. "Synthesis of methyl decanoate using different types of batch reactive distillation systems." 2017. http://hdl.handle.net/10454/11701.
Full textAbstract:
YesMethyl Decanoate (MeDC) is a Fatty Acid Methyl Ester (FAME) and is an important chemical compound with global production of 31 million tons per year. However, synthesis of methyl decanoate (MeDC) via esterification of Decanoic Acid (DeC) with methanol by reactive distillation is operationally challenging due to difficulty of keeping the reactants together in the reaction zone as methanol being the lightest component in the mixture can separate itself easily form the other reactant deteriorating significantly the conversion of DeC using either conventional batch or continuous distillation column. This is probably the main reason for not applying the conventional route for MeDC synthesis. Whether Semi-batch Distillation column (SBD) and the recently developed Integrated Conventional Batch Distillation column (i-CBD) offer the possibility of revisiting such chemical reactions for the synthesis of MeDC is the focus of this paper. The minimum energy consumption (Qtot) as the performance measure is used to evaluate the performances of each of these reactive column configurations for different range of methyl decanoate purity and the amount of product. It is observed that the use of i-CBD column provides much better performance than SBD column in terms of the production time and the maximum energy savings when excess methanol is used in the feed. However, the SBD column is found to perform better than the i-CBD column when both reactants in the feed are in equal amount. Also, the optimization results for a given separation task show that the performance of two-reflux intervals strategy is superior to the single-reflux interval in terms of operating batch time, and energy usage rate in the SBD process at equimolar ratio.
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Aqar, D. Y., Nejat Rahmanian, and Iqbal M. Mujtaba. "Methyl lactate synthesis using batch reactive distillation: Operational challenges and strategy for enhanced performance." 2015. http://hdl.handle.net/10454/7968.
Full textAbstract:
YesBatch reactive distillation is well known for improved conversion and separation of desired reaction products. However, for a number of reactions, the distillation can separate the reactants depending on their boiling points of them and thus not only reduces the benefit of the reactive distillation but also offers operational challenges for keeping the reactants together. Methyl lactate (ML) synthesis via the esterification of lactic acid (LA) with methanol in a reactive distillation falls into this category and perhaps that is why this process has not been explored in the past. The boiling points of the reactants (LA, methanol) are about 490 K and 337 K while those of the products (ML, water) are 417 K and 373 K respectively. Clearly in a conventional reactive distillation (batch or continuous) methanol will be separated from the LA and will reduce the conversion of LA to ML significantly. Here, first the limitations of the use of conventional batch distillation column (CBD) for the synthesis of ML is investigated in detail and a semi-batch reactive distillation (SBD) configuration is studied in detail where LA is the limiting reactant and methanol is continuously fed in excess in the reboiler allowing the reactants to be together for a longer period. However, this poses an operational challenge that the column has to be carefully controlled to avoid overflow of the reboiler at any time of the operation. In this work, the performance of SBD for the synthesis of ML is evaluated using model based optimization in which operational constraints are embedded. The results clearly demonstrate the viability of the system for the synthesis of ML.
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Zhang, Hong Qi, and 張鴻琦. "Batch Reactive Distillation of Quaternary SystemLactic Acid–N-Butanol–Water–N-Butyl Lactate." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/14388953153561168848.
Full textAbstract:
碩士東海大學
化學工程與材料工程學系
101
Reactive distillation can be an effective means for purification of crude lactic acid. It can be achieved by esterification of crude lactic acid with n-butanol, followed by hydrolysis of butyl lactate. In this study, the feasibility of reactive distillation for esterification and hydrolysis reactions was evaluated through batch reactive distillation experiments. Esterification process was accomplished by batch reactive distillation using different n-butanol to lactic acid feed ratios, while hydrolysis process was conducted at vacuum condition (4.5kPa) with different water to butyl lactate feed ratios. In both esterification and hydrolysis experiments, part of the condensate of overhead vapor was recycled to the column via a decanter. It was in the form of an organic-phase reflux in the former case. In the batch hydrolysis column, it was in the form of an aqueous-phase reflux. Experimental data were collected every 0.5~1 hour. On the other hand, Chen’s (2010) experimental vapor-liquild equilibrium (VLE) data were employed, and high lactic-content VLE data for the lactic acid/n-butanol/water/n-butyl lactate system were obtained and regressed with the NRTL model to yield binary interaction parameters for the system, which were subsequently used in simulating the batch reactive distillation processes with Aspen Plus, and simulation results agreed well with the experimental results, thereby verifying the applicability of the thermodynamic parameters and the feasibility of the purification of lactic acid by reactive distillation.
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Hsu, Li-Wen, and 徐立文. "Semi-batch Reactive Extractive Distillation for Production of Acetic Acid Esters with Different Alcohols." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/24113827747931879406.
Full textAbstract:
碩士國立臺灣大學
化學工程學研究所
101
Batch reactive distillation (BRD) is an integrated process which combines the advantages of reactive distillation and the flexibility of batch processes. Semi-batch reactive extractive distillation (SBRED) is a design alternative for BRD in which one reactant is continuously fed into the column during the batch. Esterifications of low molecular weight alcohols (methanol-amyl alcohol) with acetic acid have been studied as model systems for the design and optimization of BRD and SBRED processes. For n-butyl acetate and amyl acetate system, the lowest-boiling point (unstable node) is a ternary heterogeneous azeotrope located in a two-liquid region. The phase split naturally provides high purity of water (99.5%) in aqueous phase. A BRD process is feasible in these two systems because water can be removed from the reflux drum (decanter) at the top of the column. For isopropyl acetate system, the lowest-boiling point (unstable node) is also a ternary heterogeneous azeotrope located in a two-liquid region. However, the aqueous phase only provides 95% of water. It showed that SBRED can improve the production efficiency. The concentration of isopropyl alcohol in the distillate can be efficiently reduced by feeding acetic acid as an entrainer into the column continuously so that the distillate composition is closer to the water-acetate edge. High purity of water can be collected in aqueous phase and binary mixture of water and acetate can be collected in organic phase. Then a non reactive inverted batch distillation column with a decanter is used to withdraw high purity of acetate from the organic phase. For ethyl acetate system, the lowest-boiling point (unstable node) is a ternary azeotrope which is not located in a two-liquid region. Therefore, unlike previous systems, BRD with a decanter is not feasible. In our work, we consider the application of SBRED similar to isopropyl acetate system. For methyl acetate system, the lowest-boiling point (unstable node) is a binary azeotrope (of methanol and methyl acetate) which is not located in a two-liquid region. The SBRED system is preferable because methanol is much more volatile than acetic acid. The concentration of methanol in the distillate can be efficiently reduced by using a side feed entrainer. Eventually high purity methanol (97.5%) can be achieved within a single column. In this thesis, the esterifications of acetic acid with three different alcohols (methanol, ethanol, isopropanol) using SBRED are studied. All three systems use acetic acid as a side feed entrainer to drag the alcohol down, thereby preventing the alcohol from going up as a distillate. For ethyl acetate and isopropyl acetate system, the organic phase product needs to be further purified by using a nonreactive inverted batch distillation column. For methyl acetate system, we study the preliminary optimization to show that how we adjust the parameters to improve the dynamic process while the parameters are highly interdependent with each other.
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Kao, Yu-Lung, and 高玉龍. "Effect of Relative Volatility Ranking on the Design and Operation of Batch Reactive Distillation Systems." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/03971606304933965483.
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碩士國立臺灣大學
化學工程學研究所
98
Batch reactive distillation (BREAD) is an attractive process alternative which combines the advantages of reactive distillation and the flexibility of batch processes. There are three basic batch distillation column configurations: (1) Conventional batch distillation column (CBD): Feeds are charged at the bottom and products are taken out at the top. (2) Inverted batch distillation column (IBD): Feeds are charged at the top and products are taken out at the bottom. (3) Middle-vessel column (MVC): Feeds are charged in a middle-vessel of the column and products are withdrawn at the top and the bottom. Tung and Yu (AlChE J., 53, 1278-1297, 2007) used an ideal system to study the effect of relative volatility ranking on the design of column configuration for continuous RD systems. A reversible reaction A+B <=> C+D is considered and constitutes a quaternary system which has 24(4!) possible rankings according to the relativity volatility among reactants and products. They further grouped these 24 possibilities into 6 (24/2!/2!) distinct categories since the two reactants and two products are interchangeable. In this work, these 6 distinct volatility rankings are applied to the 3 basic BREAD column configurations to study the effects of relative volatility ranking on BREAD process design. The process design focuses on the choice of column configuration and the optimal collection policy including when and where to collect products and off-cuts and the corresponding reflux profile. The designs are optimized based on the batch capacity (CAP) defined as the total quantity of products meeting the purity specification produced divided by the total batch time. The results indicate that if one of the reaction products is the lightest key, a CBD column can achieve the separation objective. On the other hand, if one of the reaction products is the heaviest key, an IBD column can achieve the separation objective. Moreover, a MVC with a proper collection policy shows better performances in most of the cases. Furthermore, we investigate a new column configuration: a modified MVC in which the location of the reaction vessel is not exactly in the middle of the column. We consider the general case where the reaction vessel can be connected to the column at any point. If the reaction vessel is connected all the way at the bottom, we recover the CBD process whereas if it is connected all the way at the top, we recover the IBD. Finally, for each relative volatility ranking, we propose the most suitable column configuration and the collection policy with corresponding reflux profile which give the highest CAP.
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Edreder, E. A., M. Emtir, and Iqbal M. Mujtaba. "Energy saving in conventional and uncoventional batch reactive distillation: application to hydrolysis of methyl lactate system." 2014. http://hdl.handle.net/10454/10623.
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NoIn this work, energy consumption in a middle vessel batch reactive distillation (MVBRD) column is considered for the production of lactic acid via hydrolysis of methyl lactate. A dynamic optimization problem incorporating a process model is formulated to minimize the batch time which consequently minimizes the total energy consumption. The problem is subject to constraints on the amount and purity of lactic acid. The optimisation variables are reflux ratio and/or reboil ratio which are treated as piecewise constant. The earlier work of the authors on energy consumption in conventional batch reactive distillation column (CBRD) for the same reaction system is used for comparative analysis with the energy consumption in MVBRD. As an example, for a given separation task, the optimization results show that MVBRD is capable of saving over 23 % energy compared to energy consumption in CBRD column for the same task.
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Weerachaipichasgul, W., P. Kittisupakorn, and Iqbal M. Mujtaba. "Improvement of multicomponent batch reactive distillation under parameter uncertainty by inferential state with model predictive control." 2013. http://hdl.handle.net/10454/9752.
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yesBatch reactive distillation is aimed at achieving a high purity product, therefore, there is a great deal to find an optimal operating condition and effective control strategy to obtain maximum of the high purity product. An off-line dynamic optimization is first performed with an objective function to provide optimal product composition for the batch reactive distillation: maximum productivity. An inferential state estimator (an extended Kalman filter, EKF) based on simplified mathematical models and on-line temperature measurements, is incorporated to estimate the compositions in the reflux drum and the reboiler. Model Predictive Control (MPC) has been implemented to provide tracking of the desired product compositions subject to simplified model equations. Simulation results demonstrate that the inferential state estimation can provide good estimates of compositions. Therefore, the control performance of the MPC with the inferential state is better than that of PID. In addition, in the presence of unknown/uncertain parameters (forward reaction rate constant), the estimator is still able to provide accurate concentrations. As a result, the MPC with the inferential state is still robust and applicable in real plants.
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Aqar, D. Y., Nejat Rahmanian, and Iqbal M. Mujtaba. "Feasibility of novel integrated dividing-wall batch reactive distillation processes for the synthesis of methyl decanoate." 2018. http://hdl.handle.net/10454/15361.
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YesThe production of methyl decanoate (MeDC) through esterification of decanoic acid (DeC) with methanol by reactive distillation is operationally challenging and energy-intensive due to the complicated behaviour of the reaction system and the difficulty of retaining the reactants together in the reaction region. Methanol being the lightest component in the mixture can separate itself from the reactant DeC as the distillation proceeds which will cause a massive reduction in the conversion of DeC utilizing either a batch or continuous distillation process. Aiming to overcome this type of the potential problem, novel integrated divided-wall batch reactive distillation configuration (i-DWBD) with recycling from the distillate tank is established in this study and is examined in detail. This study has clearly demonstrated that the integrated divided-wall batch reactive distillation column (i-DWBD) is superior to the traditional conventional batch distillation (CBD) and both the divided-wall (DWBD), and split reflux divided-wall (sr-DWBD) batch reactive distillation configurations in terms of maximum achievable purity of MeDC and higher conversion of DeC into MeDC. In addition, significant batch time and energy savings are possible when the i-DWBD is operated in multi-reflux mode.
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Lee, Po-Hsien, and 李柏賢. "The Optimization of Semi-batch Reactive Distillation for Isopropyl Acetate and Ethyl Acetate and Ethyl Acetate Synthesis." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/02312628877417674515.
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碩士國立臺灣大學
化學工程學研究所
103
Batch reactive distillation (BRD) is an integrated process which combines reaction and distillation in a batch processes. Semi-batch reactive distillation (SBRD) is an alternative design from BRD in which reactant or entrainer is added as a side feed continuously. Besides the advantages of BRD, SBRD can circumvent limitations due to azeotropes. In the synthesis of isopropyl acetate by BRD, the lowest-boiling point is a ternary heterogeneous azeotrope located in a two-liquid region. After separation the organic phase still contains 3% reactant and the aqueous phase contains only 95% H2O. According to Qi, Wei; Malone, M. F. (Semi-batch Reactive Distillation for Isopropyl Acetate Synthesis. Ind. Eng. Chem. Res. 2011, 50, 1272-1277), batch reactive distillation requires an additional entrainer, a large reflux ratio and a large number of stages. They also show that by using acetic acid as a side feed into the column continuously the concentration of isopropyl alcohol in the distillate can be reduced efficiently. A second non-reactive inverted batch distillation (IBD) can be employed to separate the product IPAC from water. Hence, SBRD has the potential to improve the production efficiency. For the ethyl acetate synthesis, the lowest-boiling point is a ternary azeotrope, but it is not in two-liquid region. Therefore, a BRD is not feasible in this case. However, for the SBRD, using HAC as a side feed can drag the distillate composition into two-liquid region, closer to the ETAC-H2O edge. It also needs a second non-reactive IBD to separate the product ETAC from water. A similar design to the IPAC system is used. For both systems, we study the optimization of this process to find the values of parameters that minimize the energy consumption. Since the acetic acid and the alcohol are impurities in first column (SBRD) product and the second column (IBD) can only reduce alcohol impurity, in the SBRD we set a constraint on acetic acid impurity and adjust the constraint on the alcohol impurity which is the most important variable affecting both columns. When increasing the constraint on the isopropyl alcohol impurity, the energy required for the SBRD decreases and the energy required for the IBD increases. Therefore, we can find the optimal value of the isopropyl alcohol constraint that minimizes total energy consumption.
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Aqar, D. Y., Nejat Rahmanian, and Iqbal M. Mujtaba. "A novel split-reflux policy in batch reactive distillation for the optimum synthesis of a number of methyl esters." 2019. http://hdl.handle.net/10454/16937.
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YesThe production of a number of methyl esters such as methyl decanoate (MeDC), methyl salicylate (MeSC), and methyl benzoate (MeBZ) by esterification reactions of several carboxylic acids such as decanoic acid (DeC), salicylic acid (ScA), and benzoic acid (BeZ) with methanol, respectively, through a reactive distillation system (batch or continuous) is cost-intensive and operationally challenging operation. It is difficult to keep the reaction species together in the reaction section due to wide boiling point differences between the reactants. Methanol (in those esterification processes) having the lowest boiling temperature in the reaction mixture can separate easily from carboxylic acid as the distillation progresses, resulting in a severe drop in the reaction conversion ratio of the acid employing batch/continuous distillation system. In order to overcome this type of challenge and to increase the overall reaction conversion, a novel split-reflux conventional batch reactive distillation configuration (sr-BRD) is proposed/studied in detail in this investigation. The optimal performance of BRD/ sr-BRD column is determined in terms of maximum achievable conversion of acids, and highest concentration of the esters produced for each chemical reaction scheme. The results for given separation tasks are compared with those obtained using conventional batch distillation (BRD) process. The optimization results clearly show that the sr-BRD process significantly improves the process efficiency, the conversion ratio of acid, and the product purity of methyl esters compared to that obtained via the BRD process.
The full-text of this article will be released for public view at the end of the publisher embargo on 26 Mar 2020.
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Edreder, E. A., Iqbal M. Mujtaba, and M. Emtir. "Comparison of Conventional and Middle Vessel Batch Reactive Distillation Column: Application to Hydrolysis of Methyl Lactate to Lactic Acid." 2013. http://hdl.handle.net/10454/9643.
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NoComparison of optimal operation between conventional batch reactive distillation column (CBRD) and middle-vessel batch reactive column (MVBRD) for the production of lactic acid via hydrolysis of methyl lactate has not been considered in the past. Therefore, it is the main focus in this work. A dynamic optimization problem incorporating a process model is formulated to minimize the batch time subject to constraints on the amount and purity of lactic acid. Control variables (reflux ratio or/and a reboil ratio) are treated as a piecewise constant. Optimization results indicate that MVBRD is more effective than CBRD in terms of saving in batch time which can be as high as of 20 %.
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Mujtaba, Iqbal M., E. A. Edreder, and M. Emtir. "Significant thermal energy reduction in lactic acid production process." 2012. http://hdl.handle.net/10454/6110.
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Demicoli, Daniel [Verfasser]. "Novel batch distillation processes for the separation of systems with and without chemical reaction / Daniel Demicoli." 2005. http://d-nb.info/978975030/34.
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