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On synthesis and optimization of steam system networks. 1. / Thokozani Majozi in Industrial & engineering chemistry research, Vol. 49 N° 19 (Octobre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 19 (Octobre 2010) . - pp. 9143–9153 Titre : On synthesis and optimization of steam system networks. 1. : Sustained boiler eficiency Type de document : texte imprimé Auteurs : Thokozani Majozi, Auteur ; Tim Price, Auteur Année de publication : 2010 Article en page(s) : pp. 9143–9153 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Optimization  Steam  system Résumé : The traditional steam system comprises a steam boiler and the associated heat exchanger network (HEN). Most research published in literature tends to address both the elements of the steam system as separate entities instead of analyzing, synthesizing, and optimizing the overall system in a holistic manner. True optimality of the steam system can only be achieved if the analysis is conducted within an integrated framework. Process integration has proven to be a powerful tool in similar situations. This paper presents a process integration technique for network synthesis using conceptual and mathematical analysis without compromising boiler efficiency. It was found that the steam flow rate to the HEN could be reduced while maintaining boiler efficiency by utilizing sensible heat from the high pressure steam leaving the boiler. In the event of too little sensible energy being available, a compromise in either minimum steam flow rate or boiler efficiency must be made. A dedicated preheater can also be added to the HEN so as to guarantee the boiler efficiency is maintained; however, this will compromise the minimum steam flow rate. It was found that the flow rate could be reduced by 29.6% while still maintaining the boiler efficiency for an example problem. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1007008 [article] On synthesis and optimization of steam system networks. 1. : Sustained boiler eficiency [texte imprimé] / Thokozani Majozi, Auteur ; Tim Price, Auteur . - 2010 . - pp. 9143–9153. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 19 (Octobre 2010) . - pp. 9143–9153 Mots-clés : Optimization  Steam  system Résumé : The traditional steam system comprises a steam boiler and the associated heat exchanger network (HEN). Most research published in literature tends to address both the elements of the steam system as separate entities instead of analyzing, synthesizing, and optimizing the overall system in a holistic manner. True optimality of the steam system can only be achieved if the analysis is conducted within an integrated framework. Process integration has proven to be a powerful tool in similar situations. This paper presents a process integration technique for network synthesis using conceptual and mathematical analysis without compromising boiler efficiency. It was found that the steam flow rate to the HEN could be reduced while maintaining boiler efficiency by utilizing sensible heat from the high pressure steam leaving the boiler. In the event of too little sensible energy being available, a compromise in either minimum steam flow rate or boiler efficiency must be made. A dedicated preheater can also be added to the HEN so as to guarantee the boiler efficiency is maintained; however, this will compromise the minimum steam flow rate. It was found that the flow rate could be reduced by 29.6% while still maintaining the boiler efficiency for an example problem. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1007008

On synthesis and optimization of steam system networks. 3. / Tim Price in Industrial & engineering chemistry research, Vol. 49 N° 19 (Octobre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 19 (Octobre 2010) . - pp. 9165–9174 Titre : On synthesis and optimization of steam system networks. 3. : Pressure drop consideration Type de document : texte imprimé Auteurs : Tim Price, Auteur ; Thokozani Majozi, Auteur Année de publication : 2010 Article en page(s) : pp. 9165–9174 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Optimization  steam  system Résumé : Heat exchanger networks in steam systems are traditionally designed to operate in parallel. Coetzee and Majozi (Ind. Eng. Chem. Res. 2008, 47, 4405−4413) found that by reusing steam condensate within the network the steam flow rate could be reduced. This was achieved by restructuring the networks into a series design, with the consequence of greatly increasing the pressure drop of the system. The boiler return condensate temperature was also reduced, which was found to decrease the boiler efficiency. Maintaining the boiler efficiency has been considered in the first two papers in this series, and pressure drop is introduced in this paper. The formulations from the previous two papers are used to find the minimum steam flow rate for a HEN while maintaining the boiler efficiency. The network exhibiting the minimum pressure drop for this flow rate is then designed using the critical path algorithm. The boiler efficiency is maintained using the constraints explored in papers I (Ind. Eng. Chem. Res. DOI: 10.1021/ie1007008) and II (Ind. Eng. Chem. Res. DOI: 10.1021/ie1008579) of this series. The minimum pressure drop for the network exhibiting the minimum flow rate found in paper I was 344.4 kPa; however, the flow rate was reduced by 29.6% as shown in paper I. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1008585 [article] On synthesis and optimization of steam system networks. 3. : Pressure drop consideration [texte imprimé] / Tim Price, Auteur ; Thokozani Majozi, Auteur . - 2010 . - pp. 9165–9174. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 19 (Octobre 2010) . - pp. 9165–9174 Mots-clés : Optimization  steam  system Résumé : Heat exchanger networks in steam systems are traditionally designed to operate in parallel. Coetzee and Majozi (Ind. Eng. Chem. Res. 2008, 47, 4405−4413) found that by reusing steam condensate within the network the steam flow rate could be reduced. This was achieved by restructuring the networks into a series design, with the consequence of greatly increasing the pressure drop of the system. The boiler return condensate temperature was also reduced, which was found to decrease the boiler efficiency. Maintaining the boiler efficiency has been considered in the first two papers in this series, and pressure drop is introduced in this paper. The formulations from the previous two papers are used to find the minimum steam flow rate for a HEN while maintaining the boiler efficiency. The network exhibiting the minimum pressure drop for this flow rate is then designed using the critical path algorithm. The boiler efficiency is maintained using the constraints explored in papers I (Ind. Eng. Chem. Res. DOI: 10.1021/ie1007008) and II (Ind. Eng. Chem. Res. DOI: 10.1021/ie1008579) of this series. The minimum pressure drop for the network exhibiting the minimum flow rate found in paper I was 344.4 kPa; however, the flow rate was reduced by 29.6% as shown in paper I. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1008585

Synthesis and optimization of steam system networks. 2. / Tim Price in Industrial & engineering chemistry research, Vol. 49 N° 19 (Octobre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 19 (Octobre 2010) . - pp. 9154–9164 Titre : Synthesis and optimization of steam system networks. 2. : Multiple steam levels Type de document : texte imprimé Auteurs : Tim Price, Auteur ; Thokozani Majozi, Auteur Année de publication : 2010 Article en page(s) : pp. 9154–9164 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Optimisation  steam  system  multiple Résumé : The use of steam in heat exchanger networks (HENs) can be reduced by the application of heat integration with the intention of debottlenecking the steam boiler and indirectly reducing the water requirement [Coetzee and Majozi. Ind. Eng. Chem. Res. 2008, 47, 4405−4413]. By reducing the steam flow rate, the return condensate temperature to the boiler is compromised which adversely affects the boiler operation. A means of maintaining efficient boiler operation is to reheat the return flow to the boiler. Steam systems typically employ turbines of which the exhaust is frequently used as a heating utility in the background process. Since turbines operate at various steam levels, a means for incorporating these steam levels into the HEN optimization framework is necessary. Consequently this paper concerns the restructuring of all steam system heat exchangers using conceptual and mathematical analysis to create a series HEN with the aim of reducing the overall steam flow rate, while maintaining the boiler efficiency. In an example problem, it was found that the steam flow rate could be reduced by up to 26.3% while still maintaining the boiler efficiency. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1008579 [article] Synthesis and optimization of steam system networks. 2. : Multiple steam levels [texte imprimé] / Tim Price, Auteur ; Thokozani Majozi, Auteur . - 2010 . - pp. 9154–9164. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 19 (Octobre 2010) . - pp. 9154–9164 Mots-clés : Optimisation  steam  system  multiple Résumé : The use of steam in heat exchanger networks (HENs) can be reduced by the application of heat integration with the intention of debottlenecking the steam boiler and indirectly reducing the water requirement [Coetzee and Majozi. Ind. Eng. Chem. Res. 2008, 47, 4405−4413]. By reducing the steam flow rate, the return condensate temperature to the boiler is compromised which adversely affects the boiler operation. A means of maintaining efficient boiler operation is to reheat the return flow to the boiler. Steam systems typically employ turbines of which the exhaust is frequently used as a heating utility in the background process. Since turbines operate at various steam levels, a means for incorporating these steam levels into the HEN optimization framework is necessary. Consequently this paper concerns the restructuring of all steam system heat exchangers using conceptual and mathematical analysis to create a series HEN with the aim of reducing the overall steam flow rate, while maintaining the boiler efficiency. In an example problem, it was found that the steam flow rate could be reduced by up to 26.3% while still maintaining the boiler efficiency. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1008579