Dynamic Optimization of the Flow Rate Distribution in Heat Exchanger Networks for Fouling Mitigation

Assis, Bruna C.G.; Lemos, Julia C.; Liporace, Fábio S.; Oliveira, Sérgio Adriano Moura; Queiroz, Eduardo M.; Pessoa, Fernando; Costa, André L.H.

doi:10.1021/acs.iecr.5b00453

Cited by 17 publications

(21 citation statements)

References 28 publications

(49 reference statements)

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“…The relation between fouling rate and the thermofluid dynamic conditions can be explored not only in the design phase, as presented in the current article, but also in the analysis of the operation of the exchanger. 47,48 2. The hydraulic impact of fouling can increase the pressure drop due to the reduction of the free flow area.…”

Section: Resultsmentioning

confidence: 99%

“…The examples where the performance of the proposed approach was tested in comparison of alternative solutions involving the fouling modeling that ignores the hydraulic impact and fixed fouling resistances showed that:The inclusion of the fouling modeling in the design can identify solutions with a considerable reduction of the heat transfer area because allows the optimization procedure to identify heat exchanger alternatives that mitigate the fouling problem (e.g., solutions in the no fouling region). The relation between fouling rate and the thermofluid dynamic conditions can be explored not only in the design phase, as presented in the current article, but also in the analysis of the operation of the exchanger 47,48 The hydraulic impact of fouling can increase the pressure drop due to the reduction of the free flow area.…”

Section: Discussionmentioning

confidence: 99%

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Design of shell and tube heat exchangers considering the interaction of fouling and hydraulics

2022

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We extend a formulation of the heat exchanger design optimization with fouling modeling to consider the effect of fouling on hydraulics. A shell-side fouling model was added so the optimization can consider cases with fouling in the tube and shell sides. The focus is the design of heat exchangers with fouling behavior associated with a threshold model, like in crude preheat trains. We solve the optimization problem by using a newly proposed Set Trimming technique. We compare our results with the traditional approach of using fixed fouling factors and the previous approach of not considering the hydraulic impact of fouling. We conclude that considering the deposit thickness leads to more realistic results that are different than the ones obtained using the previous approaches. Moreover, we show that previous approaches can render designs with larger pressure drops than the maximum imposed by the constraints, as well as exchangers with higher areas.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Design of shell and tube heat exchangers considering the interaction of fouling and hydraulics

2022

Self Cite

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“…Operationally, a practical alternative for fouling mitigation is to manipulate the flow rate distribution in the network over time, through use of by-passes of individual units and control of flow split between parallel branches in the HEN. Optimising such flow distribution profiles has also been formulated as a mathematical programming problem with the objective to minimize the operational cost 12 .…”

Section: Introductionmentioning

confidence: 99%

“…1,13,14 . On the other hand, some works tackle the second problem only from a dynamic optimization perspective ignoring the cleaning scheduling 12,15 .…”

Section: Introductionmentioning

confidence: 99%

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Integration of Optimal Cleaning Scheduling and Control of Heat Exchanger Networks Undergoing Fouling: Model and Formulation

Santamaria

Macchietto

2018

Ind. Eng. Chem. Res.

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The performance and operability of heat exchanger networks (HENs) is strongly affected by fouling, which involves the deposition of unwanted material, which reduces the heat-transfer rate and increases the pressure drop, the operational costs, and the environmental impact of the process. Periodical cleaning and control of the flow rate distribution in the HEN are used to mitigate the effects of fouling and restore the performance of the units. The optimal cleaning scheduling has been formulated as a mixed-integer linear programming (MILP) or mixed-integer nonlinear programming (MINLP) problem and is solved using various approaches. The optimal control has been formulated as a nonlinear programming (NLP) problem and is used to define the flow rate distribution of the network. Both problems share the same objective: minimization of the total cost of the operation. In principle, the simultaneous solution of the optimal control problem and the optimal cleaning scheduling problem should provide greater savings than the independent or sequential solution of the two problems, since the interactions of the two mitigation alternatives are considered. However, these two problems have been typically considered separately, because of modeling and solution challenges. Also, it is not quite clear what additional benefit a simultaneous solution may bring. The challenges for solving the integrated problem are the large scale of the associated optimization problem and the different time scales involved in each operational layer. Here, a general and efficient formulation is proposed, using a continuous time discretization scheme for the integrated problem of scheduling and control of HENs subject to fouling. A dynamic model of the heat exchangers is proposed that is sufficiently detailed to represent the physics of interest with novel modifications to address simultaneously their control and scheduling in a network. The problem is formulated as a MINLP and solved using deterministic optimization algorithms. The flexibility of the model and variations of the formulation are demonstrated with two small case studies. The formulation complexity versus scale and advantages are analyzed. The results show that considering the two problems simultaneously has a very strong synergistic effect, with over a 20% decrease in operational cost achieved, in comparison to using either fouling mitigation alternative individually.

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Fouling Mitigation in Heat Exchanger Network Through Process Optimization

Wang

Feng

2020

Process Intensification and Integration for Sustainable Design

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Dynamic Optimization of the Flow Rate Distribution in Heat Exchanger Networks for Fouling Mitigation

Cited by 17 publications

References 28 publications

Design of shell and tube heat exchangers considering the interaction of fouling and hydraulics

Design of shell and tube heat exchangers considering the interaction of fouling and hydraulics

Integration of Optimal Cleaning Scheduling and Control of Heat Exchanger Networks Undergoing Fouling: Model and Formulation

Fouling Mitigation in Heat Exchanger Network Through Process Optimization

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