November 2020
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7 Reads
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November 2020
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7 Reads
November 2019
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4 Reads
March 2019
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39 Reads
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5 Citations
Computers & Chemical Engineering
The effectiveness of stochastic online process optimization strongly depends on the choice of the uncertain parameters, which are used to characterize the uncertainty embedded in the process model. This contribution presents a framework for rapid identification of the optimal set of uncertain parameters, needed for the formulation of stochastic online optimization problems. This algorithm relies on a combination of approximate statistical analysis, multi-point/global sensitivity analysis and ad-hoc ranking indices, and is tailored for applications in the field of stochastic dynamic optimization/optimal control of campaigns of batch cycles. To demonstrate the potential of the proposed approach, we apply it within the optimization of a batch campaign, in the presence of equipment fouling and of dynamic variations in the campaign targets. The process model, utilized in all of these studies, is a batch adaptation of the Tennessee Eastman Challenge problem.
November 2018
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3 Reads
December 2017
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127 Reads
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13 Citations
Computers & Chemical Engineering
This contribution presents a framework for addressing the campaign scheduling, dynamic optimization and optimal control of batch processes in an integrated fashion. The strategy is comprised of an offline and an online phase. The first involves solving a conventional campaign scheduling problem and serves to generate key information needed in the second. The latter consists of a modified dynamic optimization/optimal control algorithm and serves to update the offline campaign schedule in real time as well as to provide the batch process with optimal control actions to achieve maximum campaign profit/performance. As a result of this two-phase architecture, the algorithm avoids the solution of a mixed-integer optimization problem online and can support virtually any process recipe structure including any type of recycle. To demonstrate its potential, we test the proposed methodology to solve the integrated campaign scheduling, dynamic optimization and optimal control of a batch plant for the production of nopol.
November 2017
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3 Reads
November 2017
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2 Reads
January 2017
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3 Reads
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6 Citations
Chemical Engineering Transactions
This contribution investigates the extent to which dynamic optimization and optimal control can provide reliable prediction and insure prevention of runaways under uncertainty. We limit our analysis to batch systems because both the issue of model uncertainty and that of hazardous loss of control are widespread within this type of processes. The paper shows that, surprisingly, a specific class of deterministic dynamic optimization and optimal control algorithms allows us to easily identify and prevent runaways, even when no accurate process model is available. The production process of 2-butyl propanoate via acid-catalyzed esterification of 2-butanol serves as case study to substantiate our claims.
January 2017
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24 Reads
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1 Citation
Computer Aided Chemical Engineering
The performance obtained from the use of stochastic online optimization and control frameworks strongly depends on the choice of the set of uncertain parameters, characterizing the model uncertainty. This contribution presents a method for batch-to-batch identification of the best set of uncertain parameters with the aim of improving the reliability/effectiveness of stochastic online optimization/control methods. To demonstrate the potential of the proposed approach, we apply it to a batch version of the Tennessee Eastman challenge.
December 2016
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55 Reads
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2 Citations
Computer Aided Chemical Engineering
We propose a novel integrated methodology for taking into account model uncertainty, in the form of uncertain parameters, within a previously published real time dynamic optimization and optimal control strategy. The combined approach, designed for batch processes, is scenario-based and consists of two interacting layers: one, which computes the optimal operating conditions and takes control actions in response to disturbances, and the other, which executes the dynamic scenario updating strategy. The approach is applied to a fed-batch reactor to demonstrate its effectiveness and flexibility.
... In chemical engineering, optimization is a practical choice for designing and operating systems to maximize performance while minimizing operational expenses, environmental impact, and energy consumption [9]. Rossi et al. (2017) presented a study using dynamic optimization and chemical process control to detect runaway reactions where unstable peak temperatures may lead to severe reactor explosions. Their approach ensures uncertainty management with dynamic optimization. ...
January 2017
Chemical Engineering Transactions
... Dans le domaine "voisin" des centrales solaires thermodynamiques (CSP) utilisant des technologies solairesà concentration et produisant de l'électricité, les stratégies de contrôle et la gestion du stockage sont des sujets d'actualité qui font l'objet de nombreuses publications et qui peuvent nous intéresser dans notre recherche d'un fonctionnement optimal. Ainsi, Manenti et al. [105,106] ont simulé le fonctionnement dynamique de la centrale CSP Archimède en Italie. Ils ont représenté de manière simplifiée le fonctionnement de cette centrale et ont pu obtenir une simulation dynamique suffisante pour analyser les phases de démarrage et d'arrêt ainsi que la possible stratégie de contrôle de la centrale. ...
January 2012
... However, there are developments in the integration under uncertainty, which are of consequence here as noted in [56]. One example is the dynamic identification of the optimal description of model uncertainty from batch to batch in [99]. They emphasize the importance of the choice of uncertain parameters to characterize uncertainty in process models and present a framework for rapid identification of the optimal set of uncertain parameters needed for formulation of stochastic online optimization problems using a combination of approximate statistical analysis and multipoint sensitivity analysis. ...
March 2019
Computers & Chemical Engineering
... Otherwise, a huge number of experimental points close to 50 bar would have negatively impacted the refit performance, forcing the minimization solver to better predict close to the 50 bar region by neglecting other portions of the investigation domain where observations were less dense. 96,97 As a last consideration, we decided to limit the number of experimental data in the database so as to reduce the computational time and effort. We believe that 159 observations are sufficient to perform a kinetics refit. ...
April 2011
... Yet, the association of an offline and an online phase could benefit to the operation 1020 of a solar system and has been implemented previously for other processes. optimization of multi-unit batch processes (Rossi et al., 2017). Distinct objective functions were used in the two steps, with an economic objective present in each of the two layers. ...
December 2017
Computers & Chemical Engineering
... 50 complete scheme Graaf et al. 51 Lim et al. 36 Park et al. 35 CO + 2H 2 ⇆ CH 3 OH Seidel et al. 34 CO 2 + 3H 2 ⇆ CH 3 OH + H 2 O Nestler et al. 52 CO 2 + H 2 ⇆ CO + H 2 O Slotboom et al. 44 Lacerda de Oliveira Campos et al. 43 Bisotti et al. 13 Skrzypek guarantee that influential observations are completely removed and these have not affected the refitting procedure. 57,59,60 In the cross-validation method, the entire dataset is divided into an arbitrary number of subsets (N). The regression procedure is repeated N times using N − 1 subsets for the minimization procedure (training folder), while the last one is then used as a validation. ...
November 2013
... The application of statistical techniques to the quantification of model uncertainty is a new paradigm, which has recently emerged due to the growing interest of industry and of the PSE community in stochastic optimization frameworks, robust design strategies and quantitative risk assessment. Specifically, strategies for uncertainty quantification are commonly applied in areas such as robust process/product design (especially within the pharmaceutical sector) , drug delivery and robust optimization/control of industrial processes (Rossi et al., 2016). ...
December 2016
Computer Aided Chemical Engineering
... 18,19 The main advantage of the SIP method is that it guarantees rigorous global optimality for certain categories of nonlinear problems. Another approach is the multiscenario-based method, [20][21][22] which generates scenarios within the uncertainty set and iteratively adds more scenarios as model constraints. However, this method cannot theoretically examine and ensure the feasibility of all scenarios over the whole uncertainty set. ...
May 2016
... In a second optimization, the reactor volume is minimized which is achieved via maximization of the reaction rates. For this purpose, the adiabatic reactor edges are priced with kinetic rate expressions obtained from the kinetic model 2 for CH 3 OH synthesis by Villa et al. (1987) ...
January 1987
Industrial & Engineering Chemistry Research
... When the goal of the experiment is to distinguish between multiple models that encode competing hypotheses, MBDOE techniques generally select the experimental perturbation and measurements to maximize the predicted variance between the different model simulations. [43][44][45] Kreutz and Timmer 19 briefly describe these approaches and point out that parameter estimation is an integral part of model discrimination. Given the new data, the best approximating model can be selected from an information theoretic perspective. ...
January 1986