Support vector clustering (SVC) is an effective data-driven method to construct uncertainty sets in robust optimization (RO). However, it cannot appropriately address varying uncertainty in a contextually uncertain environment. In this work, we propose a new contextual RO (CRO) scheme, where an efficient contextual uncertainty set called kNN-SVC is developed to capture the correlation between covariates and uncertainty. Using the k-nearest neighbors (kNN) to select a subset of historical observations, contextual information can be integrated into SVC uncertainty sets, thereby alleviating conservatism while inheriting merits of SVC such as polytopic representability and ease of manipulating robustness. Besides, using only a fraction of data samples ensures low computational costs. Numerical examples demonstrate the performance improvement of the proposed kNN-SVC uncertainty set over conventional sets without considering contextual information. An industrial case of gasoline blending shows the usefulness of the proposed approach in producing robust decisions against linearization errors in nonlinear blending.
{"title":"Data-driven contextual robust optimization based on support vector clustering","authors":"Xianyu Li , Fenglian Dong , Zhiwei Wei , Chao Shang","doi":"10.1016/j.compchemeng.2025.109004","DOIUrl":"10.1016/j.compchemeng.2025.109004","url":null,"abstract":"<div><div>Support vector clustering (SVC) is an effective data-driven method to construct uncertainty sets in robust optimization (RO). However, it cannot appropriately address varying uncertainty in a contextually uncertain environment. In this work, we propose a new contextual RO (CRO) scheme, where an efficient contextual uncertainty set called kNN-SVC is developed to capture the correlation between covariates and uncertainty. Using the k-nearest neighbors (kNN) to select a subset of historical observations, contextual information can be integrated into SVC uncertainty sets, thereby alleviating conservatism while inheriting merits of SVC such as polytopic representability and ease of manipulating robustness. Besides, using only a fraction of data samples ensures low computational costs. Numerical examples demonstrate the performance improvement of the proposed kNN-SVC uncertainty set over conventional sets without considering contextual information. An industrial case of gasoline blending shows the usefulness of the proposed approach in producing robust decisions against linearization errors in nonlinear blending.</div></div>","PeriodicalId":286,"journal":{"name":"Computers & Chemical Engineering","volume":"195 ","pages":"Article 109004"},"PeriodicalIF":3.9,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143348529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-17DOI: 10.1016/j.compchemeng.2024.108993
Daniel Ovalle , David A. Liñán , Albert Lee , Jorge M. Gómez , Luis Ricardez-Sandoval , Ignacio E. Grossmann , David E. Bernal Neira
Optimization of chemical processes is challenging due to nonlinearities arising from chemical principles and discrete design decisions. The optimal synthesis and design of chemical processes can be posed as a Generalized Disjunctive Programming (GDP) problem. While reformulating GDP problems as Mixed-Integer Nonlinear Programming (MINLP) problems is common, specialized algorithms for GDP remain scarce. This study introduces the Logic-Based Discrete-Steepest Descent Algorithm (LD-SDA) as a solution method for GDP problems involving ordered Boolean variables. LD-SDA transforms these variables into external integer decisions and uses a two-level decomposition: the upper-level sets external configurations, and the lower-level solves the remaining variables, efficiently exploiting the GDP structure. In the case studies presented in this work, including batch processing, reactor superstructures, and distillation columns, LD-SDA consistently outperforms conventional GDP and MINLP solvers, especially as the problem size grows. LD-SDA also proves superior when solving challenging problems where other solvers encounter difficulties finding optimal solutions.
{"title":"Logic-Based Discrete-Steepest Descent: A solution method for process synthesis Generalized Disjunctive Programs","authors":"Daniel Ovalle , David A. Liñán , Albert Lee , Jorge M. Gómez , Luis Ricardez-Sandoval , Ignacio E. Grossmann , David E. Bernal Neira","doi":"10.1016/j.compchemeng.2024.108993","DOIUrl":"10.1016/j.compchemeng.2024.108993","url":null,"abstract":"<div><div>Optimization of chemical processes is challenging due to nonlinearities arising from chemical principles and discrete design decisions. The optimal synthesis and design of chemical processes can be posed as a Generalized Disjunctive Programming (GDP) problem. While reformulating GDP problems as Mixed-Integer Nonlinear Programming (MINLP) problems is common, specialized algorithms for GDP remain scarce. This study introduces the Logic-Based Discrete-Steepest Descent Algorithm (LD-SDA) as a solution method for GDP problems involving ordered Boolean variables. LD-SDA transforms these variables into external integer decisions and uses a two-level decomposition: the upper-level sets external configurations, and the lower-level solves the remaining variables, efficiently exploiting the GDP structure. In the case studies presented in this work, including batch processing, reactor superstructures, and distillation columns, LD-SDA consistently outperforms conventional GDP and MINLP solvers, especially as the problem size grows. LD-SDA also proves superior when solving challenging problems where other solvers encounter difficulties finding optimal solutions.</div></div>","PeriodicalId":286,"journal":{"name":"Computers & Chemical Engineering","volume":"195 ","pages":"Article 108993"},"PeriodicalIF":3.9,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143348531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nowadays, the management of natural gas networks primarily relies on the expertise gained by operators over the years. Nevertheless, the need to reduce energy consumption and the progressive installation of electric compressors call for the adoption of systematic optimization tools. This study proposes a Mixed Integer Linear Programming (MILP) model for optimizing the operation of complex real-world gas networks to minimize the environmental impact of the compression work in presence of both gas-turbine driven and electric compressors. The operational problem includes the gas transport dynamic equations, detailed modeling of compressor stations and control valves, while handling complex branch and looped networks with possible reverse flow. To address large-scale problems, a graph reduction procedure and a novel bilevel decomposition algorithm are developed. This methodology, validated with real data, enables the optimization of the nationwide Italian network, comprising 51 compressors and 9727 km of pipes.
{"title":"A detailed MILP model and an ad hoc decomposition algorithm for the operational optimization of gas transport networks","authors":"Lavinia Marina Paola Ghilardi , Francesco Casella , Daniele Barbati , Roberto Palazzo , Emanuele Martelli","doi":"10.1016/j.compchemeng.2025.109006","DOIUrl":"10.1016/j.compchemeng.2025.109006","url":null,"abstract":"<div><div>Nowadays, the management of natural gas networks primarily relies on the expertise gained by operators over the years. Nevertheless, the need to reduce energy consumption and the progressive installation of electric compressors call for the adoption of systematic optimization tools. This study proposes a Mixed Integer Linear Programming (MILP) model for optimizing the operation of complex real-world gas networks to minimize the environmental impact of the compression work in presence of both gas-turbine driven and electric compressors. The operational problem includes the gas transport dynamic equations, detailed modeling of compressor stations and control valves, while handling complex branch and looped networks with possible reverse flow. To address large-scale problems, a graph reduction procedure and a novel bilevel decomposition algorithm are developed. This methodology, validated with real data, enables the optimization of the nationwide Italian network, comprising 51 compressors and 9727 km of pipes.</div></div>","PeriodicalId":286,"journal":{"name":"Computers & Chemical Engineering","volume":"195 ","pages":"Article 109006"},"PeriodicalIF":3.9,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143348535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-13DOI: 10.1016/j.compchemeng.2025.109003
Venkata Reddy Palleti
Water Distribution Networks (WDNs) are one of the most important critical infrastructures in any nation. WDNs are often prone to either accidental or intentional contamination. Intentional contamination, like terrorist attacks on WDNs, can lead to poisoned water, causing many fatalities and large economic consequences. In order to protect against these attacks, an efficient sensor network design is required by placing a limited number of sensors in the network. In this work, we will design sensor networks to satisfy two criteria, namely, observability (ability to detect the contamination) and identifiability ability to detect and identify the contamination source). Hydraulic simulations are performed on a WDN subjected to variable demand conditions. We will map the problem of the sensor network to a minimum set cover problem. A greedy heuristic algorithm is used to obtain the sensor network design under variable demand conditions. The proposed methodology is illustrated on a real life WDN.
{"title":"Optimal sensor placement for contamination detection and identification in water distribution networks under demand uncertainty","authors":"Venkata Reddy Palleti","doi":"10.1016/j.compchemeng.2025.109003","DOIUrl":"10.1016/j.compchemeng.2025.109003","url":null,"abstract":"<div><div>Water Distribution Networks (WDNs) are one of the most important critical infrastructures in any nation. WDNs are often prone to either accidental or intentional contamination. Intentional contamination, like terrorist attacks on WDNs, can lead to poisoned water, causing many fatalities and large economic consequences. In order to protect against these attacks, an efficient sensor network design is required by placing a limited number of sensors in the network. In this work, we will design sensor networks to satisfy two criteria, namely, observability (ability to detect the contamination) and identifiability ability to detect and identify the contamination source). Hydraulic simulations are performed on a WDN subjected to variable demand conditions. We will map the problem of the sensor network to a minimum set cover problem. A greedy heuristic algorithm is used to obtain the sensor network design under variable demand conditions. The proposed methodology is illustrated on a real life WDN.</div></div>","PeriodicalId":286,"journal":{"name":"Computers & Chemical Engineering","volume":"194 ","pages":"Article 109003"},"PeriodicalIF":3.9,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-11DOI: 10.1016/j.compchemeng.2025.109001
Hyojin Jung, Yuchan Ahn
The widespread use of plastic products and inadequate waste management systems have rendered plastic waste a major source of environmental pollution, thereby necessitating effective plastic recycling methods. In this study, we propose two pyrolysis processes for recycling plastic waste using Aspen Plus: a base process and an alternative process. The main difference lies in the condensation and separation methods used to produce pyrolysis oil. In the base process, condensation is carried out using a cooler, followed by decomposition with a flash drum. In contrast, the alternative process utilizes a distillation column for both condensation and separation. The results showed that PS achieved the highest oil yield of 81.3 %, while PS/PE exhibited the greatest improvement, with a 27.34 % increase in oil production yield in the alternative process compared to the base process. However, the alternative process incurs higher operating and capital costs due to the precise control requirements, particularly for feedstocks like PS/PE/PP/PET, which had the highest energy production cost at 31.07×10 −4 $/ MJ compared to 27.85×10 −4 $/ MJ in the base process. Despite these higher costs, the alternative process significantly improved oil production, especially for plastics such as PS and PS/PE. These findings underscore the importance of selecting pyrolysis processes based on feedstock composition and specific recycling goals, highlighting the trade-off between higher yields and increased energy production costs and emphasizing the need for balance.
{"title":"Process design for plastic waste pyrolysis: Yield analysis and economic assessment","authors":"Hyojin Jung, Yuchan Ahn","doi":"10.1016/j.compchemeng.2025.109001","DOIUrl":"10.1016/j.compchemeng.2025.109001","url":null,"abstract":"<div><div>The widespread use of plastic products and inadequate waste management systems have rendered plastic waste a major source of environmental pollution, thereby necessitating effective plastic recycling methods. In this study, we propose two pyrolysis processes for recycling plastic waste using Aspen Plus: a base process and an alternative process. The main difference lies in the condensation and separation methods used to produce pyrolysis oil. In the base process, condensation is carried out using a cooler, followed by decomposition with a flash drum. In contrast, the alternative process utilizes a distillation column for both condensation and separation. The results showed that PS achieved the highest oil yield of 81.3 %, while PS/PE exhibited the greatest improvement, with a 27.34 % increase in oil production yield in the alternative process compared to the base process. However, the alternative process incurs higher operating and capital costs due to the precise control requirements, particularly for feedstocks like PS/PE/PP/PET, which had the highest energy production cost at 31.07×10 <sup>−4</sup> $/ MJ compared to 27.85×10 <sup>−4</sup> $/ MJ in the base process. Despite these higher costs, the alternative process significantly improved oil production, especially for plastics such as PS and PS/PE. These findings underscore the importance of selecting pyrolysis processes based on feedstock composition and specific recycling goals, highlighting the trade-off between higher yields and increased energy production costs and emphasizing the need for balance.</div></div>","PeriodicalId":286,"journal":{"name":"Computers & Chemical Engineering","volume":"194 ","pages":"Article 109001"},"PeriodicalIF":3.9,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-09DOI: 10.1016/j.compchemeng.2025.109002
Jialiang Zhu, Wangwang Zhu, Yi Liu
Chemical processes with distributed outputs are characterized by various operating conditions, and the scarcity of labeled data poses challenges to the prediction of product quality. An ensemble transfer Gaussian process regression (ETGPR) model is developed for prediction of different quantities of distributed outputs. First, for each test instances from target domain, just-in-time learning is adopted to select distance-based similar instances from source domain in related operating conditions. Mutual information helps create various local models by building diverse input variable sets. Subsequently, Bayesian inference is used to produce the posterior probabilities relative to the test instance, then set as the weights of local prediction. The instance transfer is thus completed via distance-based similar instance selection from source domain for local model construction, and the model performance is improved by the ensemble weighting strategy, concerning the target domain, under diverse operating conditions. Therefore, by utilizing and transferring information from source domain, unsupervised transfer can be implemented with available unlabeled target data. The superiority of ETGPR model is confirmed in the case of modeling the polymerization process with distributed outputs.
{"title":"Ensemble transfer learning assisted soft sensor for distributed output inference in chemical processes","authors":"Jialiang Zhu, Wangwang Zhu, Yi Liu","doi":"10.1016/j.compchemeng.2025.109002","DOIUrl":"10.1016/j.compchemeng.2025.109002","url":null,"abstract":"<div><div>Chemical processes with distributed outputs are characterized by various operating conditions, and the scarcity of labeled data poses challenges to the prediction of product quality. An ensemble transfer Gaussian process regression (ETGPR) model is developed for prediction of different quantities of distributed outputs. First, for each test instances from target domain, just-in-time learning is adopted to select distance-based similar instances from source domain in related operating conditions. Mutual information helps create various local models by building diverse input variable sets. Subsequently, Bayesian inference is used to produce the posterior probabilities relative to the test instance, then set as the weights of local prediction. The instance transfer is thus completed via distance-based similar instance selection from source domain for local model construction, and the model performance is improved by the ensemble weighting strategy, concerning the target domain, under diverse operating conditions. Therefore, by utilizing and transferring information from source domain, unsupervised transfer can be implemented with available unlabeled target data. The superiority of ETGPR model is confirmed in the case of modeling the polymerization process with distributed outputs.</div></div>","PeriodicalId":286,"journal":{"name":"Computers & Chemical Engineering","volume":"194 ","pages":"Article 109002"},"PeriodicalIF":3.9,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-09DOI: 10.1016/j.compchemeng.2024.108983
Jiyizhe Zhang , Daria Semochkina , Naoto Sugisawa , David C. Woods , Alexei A. Lapkin
Multi-objective Bayesian optimization (MOBO) has shown to be a promising tool for reaction development. However, noise is usually inevitable in experimental and chemical processes, and finding reliable solutions is challenging when the noise is unknown or significant. In this study, we focus on finding a set of optimal reaction conditions using multi-objective Euclidian expected quantile improvement (MO-E-EQI) under noisy settings. First, the performance of MO-E-EQI is evaluated by comparing with some recent MOBO algorithms in silico with linear and log-linear heteroscedastic noise structures and different magnitudes. It is noticed that high noise can degrade the performance of MOBO algorithms. MO-E-EQI shows robust performance in terms of hypervolume-based metric, coverage metric and number of solutions on the Pareto front. Finally, MO-E-EQI is implemented in a real case to optimize an esterification reaction to achieve the maximum space-time-yield and the minimal E-factor. The algorithm identifies a clear trade-off between the two objectives.
{"title":"Multi-objective reaction optimization under uncertainties using expected quantile improvement","authors":"Jiyizhe Zhang , Daria Semochkina , Naoto Sugisawa , David C. Woods , Alexei A. Lapkin","doi":"10.1016/j.compchemeng.2024.108983","DOIUrl":"10.1016/j.compchemeng.2024.108983","url":null,"abstract":"<div><div>Multi-objective Bayesian optimization (MOBO) has shown to be a promising tool for reaction development. However, noise is usually inevitable in experimental and chemical processes, and finding reliable solutions is challenging when the noise is unknown or significant. In this study, we focus on finding a set of optimal reaction conditions using multi-objective Euclidian expected quantile improvement (MO-E-EQI) under noisy settings. First, the performance of MO-E-EQI is evaluated by comparing with some recent MOBO algorithms <em>in silico</em> with linear and log-linear heteroscedastic noise structures and different magnitudes. It is noticed that high noise can degrade the performance of MOBO algorithms. MO-E-EQI shows robust performance in terms of hypervolume-based metric, coverage metric and number of solutions on the Pareto front. Finally, MO-E-EQI is implemented in a real case to optimize an esterification reaction to achieve the maximum space-time-yield and the minimal E-factor. The algorithm identifies a clear trade-off between the two objectives.</div></div>","PeriodicalId":286,"journal":{"name":"Computers & Chemical Engineering","volume":"194 ","pages":"Article 108983"},"PeriodicalIF":3.9,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-05DOI: 10.1016/j.compchemeng.2025.109000
Seen Ye Lim , Nishanth G. Chemmangattuvalappil , John Frederick D. Tapia , Ianatul Khoiroh , Pui Vun Chai , Lik Yin Ng
Oleochemical industry generates palm process residue during hydrogenation of fatty acids or methyl esters. This residue, comprising fatty alcohols and alkanes with overlapping boiling points, is challenging and costly to separate using conventional distillation. Efficient recovery of fatty alcohols for commercial use, while alkanes for jet fuel, lubricants, and gasoline are beneficial. A promising solution involves halogenating fatty alcohols into derivatives with distinct boiling points from alkanes, enabling efficient distillation. Thus, identifying chemical reaction pathways for fatty alcohols and halogenating agents that occurs spontaneously under optimal conditions is crucial for cost-effectiveness and sustainability. Utilizing P-graph framework with SSG + LP algorithm, 116 thermodynamically feasible pathways were generated and analyzed using Aspen Plus. The optimal pathway successfully separated C12H25OH from C14H30 and achieved a high conversion of 90.40% for C12H25Br. This pathway also produced valuable by-products such as C4H8BrOH and C5H11OH, generating higher revenue and demonstrating industrial feasibility.
{"title":"Optimal chemical reaction pathway for palm process residue recovery using Process Graph (P-graph) framework","authors":"Seen Ye Lim , Nishanth G. Chemmangattuvalappil , John Frederick D. Tapia , Ianatul Khoiroh , Pui Vun Chai , Lik Yin Ng","doi":"10.1016/j.compchemeng.2025.109000","DOIUrl":"10.1016/j.compchemeng.2025.109000","url":null,"abstract":"<div><div>Oleochemical industry generates palm process residue during hydrogenation of fatty acids or methyl esters. This residue, comprising fatty alcohols and alkanes with overlapping boiling points, is challenging and costly to separate using conventional distillation. Efficient recovery of fatty alcohols for commercial use, while alkanes for jet fuel, lubricants, and gasoline are beneficial. A promising solution involves halogenating fatty alcohols into derivatives with distinct boiling points from alkanes, enabling efficient distillation. Thus, identifying chemical reaction pathways for fatty alcohols and halogenating agents that occurs spontaneously under optimal conditions is crucial for cost-effectiveness and sustainability. Utilizing P-graph framework with SSG + LP algorithm, 116 thermodynamically feasible pathways were generated and analyzed using Aspen Plus. The optimal pathway successfully separated C<sub>12</sub>H<sub>25</sub>OH from C<sub>14</sub>H<sub>30</sub> and achieved a high conversion of 90.40% for C<sub>12</sub>H<sub>25</sub>Br. This pathway also produced valuable by-products such as C<sub>4</sub>H<sub>8</sub>BrOH and C<sub>5</sub>H<sub>11</sub>OH, generating higher revenue and demonstrating industrial feasibility.</div></div>","PeriodicalId":286,"journal":{"name":"Computers & Chemical Engineering","volume":"194 ","pages":"Article 109000"},"PeriodicalIF":3.9,"publicationDate":"2025-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-04DOI: 10.1016/j.compchemeng.2025.108998
Hongqiu Zhu, Yixin Lv, Minghui Liu, Can Zhou
The flow of hydrogen sulfide is a crucial factor influencing the precipitation of heavy metals in acid wastewater. However, flow regulation in industrial environments often demonstrates lag. The oxidation–reduction potential (ORP) is closely linked to the flow of hydrogen sulfide. Consequently, this paper proposes an ORP prediction model that employs a double-layer improved particle swarm optimization (DLIPSO) and extreme learning machine (ELM). To overcome the limitation of particle swarm optimization (PSO) easily getting trapped in local optima, the oppositional-based learning (OBL) strategy and time-varying inertia weights are introduced to improve the search performance of the particles. Additionally, a double-layer particle swarm structure is utilized to identify the most effective combination of optimal structure and parameters for the ELM, maximizing its predictive performance. The proposed model is validated on a real dataset and compared with five other models. Experimental results indicate that the root mean square error (RMSE) of the proposed model decreased by 9.40 % to 49.76 % compared to the other models.
{"title":"An ORP prediction model for acid wastewater sulfidation process based on improved extreme learning machine","authors":"Hongqiu Zhu, Yixin Lv, Minghui Liu, Can Zhou","doi":"10.1016/j.compchemeng.2025.108998","DOIUrl":"10.1016/j.compchemeng.2025.108998","url":null,"abstract":"<div><div>The flow of hydrogen sulfide is a crucial factor influencing the precipitation of heavy metals in acid wastewater. However, flow regulation in industrial environments often demonstrates lag. The oxidation–reduction potential (ORP) is closely linked to the flow of hydrogen sulfide. Consequently, this paper proposes an ORP prediction model that employs a double-layer improved particle swarm optimization (DLIPSO) and extreme learning machine (ELM). To overcome the limitation of particle swarm optimization (PSO) easily getting trapped in local optima, the oppositional-based learning (OBL) strategy and time-varying inertia weights are introduced to improve the search performance of the particles. Additionally, a double-layer particle swarm structure is utilized to identify the most effective combination of optimal structure and parameters for the ELM, maximizing its predictive performance. The proposed model is validated on a real dataset and compared with five other models. Experimental results indicate that the root mean square error (RMSE) of the proposed model decreased by 9.40 % to 49.76 % compared to the other models.</div></div>","PeriodicalId":286,"journal":{"name":"Computers & Chemical Engineering","volume":"194 ","pages":"Article 108998"},"PeriodicalIF":3.9,"publicationDate":"2025-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-04DOI: 10.1016/j.compchemeng.2025.108999
Ricardo A.de O. Lima, Reginaldo Guirardello
This study presents a discrete-time mixed-integer linear programming (MILP) model to optimize long-term maintenance turnaround scheduling in an oil refinery focused on fuel production. Refineries are complex networks of integrated process units, and maintenance turnarounds, involving temporary shutdowns for inspection and repair, can significantly disrupt production and reduce revenues. The MILP model aims to minimize these disruptions by optimizing turnaround schedules while maintaining product supply and maximizing economic performance. The model incorporates flow, labor, resource, and planning constraints, allowing for different unit groupings and scenario simulations. Key outputs include the maintenance schedule, unit utilization rates, intermediate stock levels, production, manpower, and maintenance costs. The model serves as a decision-support tool for refining managers, enabling them to plan maintenance interventions that maximize operating profit while adhering to operational constraints.
{"title":"Long term turnaround planning for an oil refinery using a MILP model","authors":"Ricardo A.de O. Lima, Reginaldo Guirardello","doi":"10.1016/j.compchemeng.2025.108999","DOIUrl":"10.1016/j.compchemeng.2025.108999","url":null,"abstract":"<div><div>This study presents a discrete-time mixed-integer linear programming (MILP) model to optimize long-term maintenance turnaround scheduling in an oil refinery focused on fuel production. Refineries are complex networks of integrated process units, and maintenance turnarounds, involving temporary shutdowns for inspection and repair, can significantly disrupt production and reduce revenues. The MILP model aims to minimize these disruptions by optimizing turnaround schedules while maintaining product supply and maximizing economic performance. The model incorporates flow, labor, resource, and planning constraints, allowing for different unit groupings and scenario simulations. Key outputs include the maintenance schedule, unit utilization rates, intermediate stock levels, production, manpower, and maintenance costs. The model serves as a decision-support tool for refining managers, enabling them to plan maintenance interventions that maximize operating profit while adhering to operational constraints.</div></div>","PeriodicalId":286,"journal":{"name":"Computers & Chemical Engineering","volume":"194 ","pages":"Article 108999"},"PeriodicalIF":3.9,"publicationDate":"2025-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}