Process economics optimization based on process simulators is an attractive and largely exploited tool. Its use, however, is limited by some factors: optimizers implemented in commercial process simulators are often non-reliable or non-robust, due to the presence of unfeasibility regions and multiple minima. In addition, several oversimplified and conceptually-wrong approaches to the economic optimization have been noted, like the optimization of operating costs (OPEX) only and the successive determination of fixed costs (CAPEX), or the neglect of some factors affecting CAPEX and OPEX: the obvious consequence is that the designed process configuration doesn’t correspond to the real optimum configuration from the economic point of view. The aim of the present thesis work is, consequently, to develop a dedicated program in C++ language to be coupled with a commercial process simulator (PRO/II, commercialized by Schneider Electric) to perform a robust and simultaneous CAPEX and OPEX optimization. Among the characteristics of the obtained program, named CORO (CAPEX and OPEX Robust Optimizer), two can be underlined: the possibility to optimize every project independently of the process scheme and the ability to adapt distillation columns to the operating conditions (i.e. to change number of trays and position of feed tray). In particular, the second characteristic allows to solve problems that traditional process simulation based optimizers cannot solve, since they cannot change the number of trays. To compute fixed and operating costs, CORO implements two different economic libraries (Turton, 2012 and Peters & Timmerhaus, 2002), in order to guarantee higher flexibility and to provide the possibility to compare the results obtained. The developed program was tested in demonstrative case studies, created ad hoc to emphasize some critical issues and verify the proper working of the program. After that program was applied to an industrial case study (FAT 1MW), in order to provide a preliminary economic assessment, a first optimization and to evaluate the performance of the program on a complex flowsheet.
L’ottimizzazione economica di processo basata sui simulatori di processo risulta essere uno strumento largamente sfruttato e dall’alto potenziale. Il suo utilizzo, tuttavia, è limitato da alcuni fattori: gli ottimizzatori implementati nei simulatori di processo sono spesso poco affidabili o non robusti, a causa della presenza di regioni di infattibilità e di diversi possibili punti di ottimo. A questo si sommano degli approcci all’ottimizzazione economica concettualmente sbagliati o eccessivamente semplificati, come quello di ottimizzare esclusivamente i costi operativi (OPEX) e determinare di conseguenza i cost fissi (CAPEX), oppure quello di non tenere conto di tutti i fattori che possono influenzare CAPEX e OPEX: l’ovvia conseguenza è che le condizioni operative così determinate non corrispondono al vero ottimo economico dell’impianto. Lo scopo del presente lavoro di tesi è stato, dunque, quello di sviluppare un apposito programma in linguaggio C++ da accoppiare a un simulatore di processo (PRO/II, distribuito da Schneider Electric) per garantire un’ottimizzazione simultanea e robusta di CAPEX e OPEX. Tra le caratteristiche del programma ottenuto, chiamato CORO (CAPEX and OPEX Robust Optimizer), spiccano la possibilità di adattarsi a qualunque problema indipendentemente dallo schema di processo implementato nel simulatore e la possibilità di adattare le colonne di distillazione alle condizioni operative (cambiando iterativamente numero di piatti e posizione del piatto di alimentazione). Ciò permette di risolvere problemi che coi comuni simulatori di processo non potrebbero essere risolti. Per calcolare CAPEX e OPEX sono state inserite le correlazioni di due diverse librerie economiche (Turton, 2012 e Peters & Timmerhaus, 2002) in modo da garantire una maggiore flessibilità e poter confermare i risultati ottenuti. Il programma ottenuto è stato testato in alcuni casi studio dimostrativi, costruiti ad hoc per enfatizzare alcune criticità e certificarne il corretto funzionamento. Infine, il programma è stato testato su un caso studio industriale (FAT 1MW) di cui sono state condotte un’analisi economica preliminare e una prima ottimizzazione.
Generalized framework for robust and simultaneous CAPEX/OPEX optimization
COLOMBI, DAVIDE
2017/2018
Abstract
Process economics optimization based on process simulators is an attractive and largely exploited tool. Its use, however, is limited by some factors: optimizers implemented in commercial process simulators are often non-reliable or non-robust, due to the presence of unfeasibility regions and multiple minima. In addition, several oversimplified and conceptually-wrong approaches to the economic optimization have been noted, like the optimization of operating costs (OPEX) only and the successive determination of fixed costs (CAPEX), or the neglect of some factors affecting CAPEX and OPEX: the obvious consequence is that the designed process configuration doesn’t correspond to the real optimum configuration from the economic point of view. The aim of the present thesis work is, consequently, to develop a dedicated program in C++ language to be coupled with a commercial process simulator (PRO/II, commercialized by Schneider Electric) to perform a robust and simultaneous CAPEX and OPEX optimization. Among the characteristics of the obtained program, named CORO (CAPEX and OPEX Robust Optimizer), two can be underlined: the possibility to optimize every project independently of the process scheme and the ability to adapt distillation columns to the operating conditions (i.e. to change number of trays and position of feed tray). In particular, the second characteristic allows to solve problems that traditional process simulation based optimizers cannot solve, since they cannot change the number of trays. To compute fixed and operating costs, CORO implements two different economic libraries (Turton, 2012 and Peters & Timmerhaus, 2002), in order to guarantee higher flexibility and to provide the possibility to compare the results obtained. The developed program was tested in demonstrative case studies, created ad hoc to emphasize some critical issues and verify the proper working of the program. After that program was applied to an industrial case study (FAT 1MW), in order to provide a preliminary economic assessment, a first optimization and to evaluate the performance of the program on a complex flowsheet.| File | Dimensione | Formato | |
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2018_12_Colombi.pdf
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https://hdl.handle.net/10589/145246