This thesis work is included into the ERC INTENT research project (Grant n. 694910), aimed at the intensification of industrial chemical processes through the development of new structured reactors characterized by a better material and thermal exchange. A mathematical model for the simulation of a packed-foam reactor for the methane steam reforming reaction has been developed for the first time. In this configuration the catalytic pellets are loaded inside open-cell metallic foams. This solution allows to load high quantities of catalytic material inside the reactor and exploits the high thermal conductivity of the metallic structure to intensify the thermal exchange. This characteristic makes the packed-foam reactor very effective for the synthetic gas production by steam reforming, being the process characterized by highly endothermic reactions. The first chapter of the work is devoted to the state of the art of the main processes of synthetic gas production, focusing on the steam reforming. The second chapter shows the metallic foams properties and analyzes the concept of structured reactor presenting the advantages and disadvantages of different potential configurations. In the third chapter the developed bidimensional catalytic reactor model is fully described. It can be considered heterogeneous, as it takes into account two different phases: the metallic foam and the pseudo-homogenous phase composed of gas stream and catalytic packed bed. In the fourth chapter, through a sensitivity analysis, evaluating the methane conversion and the temperature profiles variations, it has been possible to obtain an evaluation of the impact of the fundamental parameters of the catalytic bed and of the metallic foam on the reactor performances. Moreover, two correlations taken from literature for the evaluation of the thermal exchange properties have been compared. In the last chapter the model behavior has been investigated simulating the experimental data coming from a lab-scale reactor at different temperatures, in order to better understand model issues and potential.
Questo lavoro di tesi si inserisce nel progetto di ricerca ERC INTENT (Grant n. 694910), finalizzato all’intensificazione di processi chimici industriali attraverso lo sviluppo di nuove possibili configurazioni di reattori strutturati caratterizzati da un migliore scambio termico e di materia. È stato sviluppato per la prima volta un modello matematico per la simulazione di un reattore a schiuma impaccata per la reazione di steam reforming di metano. In questa tipologia di reattore i pellet catalitici vengono impaccati all’interno di schiume metalliche a cella aperta. Questa soluzione permette di caricare elevate quantità di materiale catalitico all’interno del reattore e sfrutta l’alta conducibilità termica della struttura metallica per intensificare lo scambio termico. Questa caratteristica rende il reattore packed-foam molto interessante per il processo di produzione del gas di sintesi mediante steam reforming, essendo caratterizzato da forte endotermicità. Il primo capitolo dell’elaborato è stato dedicato allo stato dell’arte dei principali processi di produzione di gas di sintesi, soffermandosi in particolare sullo steam reforming. Il secondo capitolo approfondisce il concetto di reattori strutturati confrontando i vantaggi e svantaggi delle diverse configurazioni. Nel terzo capitolo viene dettagliatamente descritto il modello bidimensionale di reattore catalitico qui sviluppato. Esso può essere considerato eterogeneo, poiché considera due fasi distinte: la schiuma metallica e una fase pseudo-omogenea composta dalla portata gassosa e dal letto impaccato. Nel quarto capitolo, attraverso un’analisi di sensitività, condotta valutando la conversione di metano e la variazione dei profili di temperatura, è stato possibile avere una stima dell’impatto che i parametri fondamentali del letto catalitico e della schiuma hanno sulle performance del reattore. Inoltre, sono state anche verificate alcune correlazioni presenti in letteratura per il calcolo delle proprietà di scambio termico. Nel quinto capitolo il comportamento del modello è stato analizzato simulando dei dati sperimentali ottenuti in un reattore di laboratorio a diverse temperature al fine di comprenderne meglio problemi e potenzialità.
Modeling study of a packed-foam reactor for methane steam reforming
VALTULINI, GIORGIO
2017/2018
Abstract
This thesis work is included into the ERC INTENT research project (Grant n. 694910), aimed at the intensification of industrial chemical processes through the development of new structured reactors characterized by a better material and thermal exchange. A mathematical model for the simulation of a packed-foam reactor for the methane steam reforming reaction has been developed for the first time. In this configuration the catalytic pellets are loaded inside open-cell metallic foams. This solution allows to load high quantities of catalytic material inside the reactor and exploits the high thermal conductivity of the metallic structure to intensify the thermal exchange. This characteristic makes the packed-foam reactor very effective for the synthetic gas production by steam reforming, being the process characterized by highly endothermic reactions. The first chapter of the work is devoted to the state of the art of the main processes of synthetic gas production, focusing on the steam reforming. The second chapter shows the metallic foams properties and analyzes the concept of structured reactor presenting the advantages and disadvantages of different potential configurations. In the third chapter the developed bidimensional catalytic reactor model is fully described. It can be considered heterogeneous, as it takes into account two different phases: the metallic foam and the pseudo-homogenous phase composed of gas stream and catalytic packed bed. In the fourth chapter, through a sensitivity analysis, evaluating the methane conversion and the temperature profiles variations, it has been possible to obtain an evaluation of the impact of the fundamental parameters of the catalytic bed and of the metallic foam on the reactor performances. Moreover, two correlations taken from literature for the evaluation of the thermal exchange properties have been compared. In the last chapter the model behavior has been investigated simulating the experimental data coming from a lab-scale reactor at different temperatures, in order to better understand model issues and potential.File | Dimensione | Formato | |
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https://hdl.handle.net/10589/145787