Many chemical processes are characterized by strong exothermicity, which makes them subjected to the well-known phenomenon of thermal runaway. In order to mitigate the effects due to the high rate of heat release, historically, these processes have been studied and developed in a discontinuous operating mode. Recently, with the increased need to intensify processes, more and more technologies and solutions have been proposed to switch an industrial production from discontinuous to continuous, while maintaining safe conditions. This work proposes a configuration, on a laboratory scale, to study the discontinuous-to-continuous transition of three reactive processes: the nitration of FAM to give NIM, the nitration of 4-Chlorobenzotrifluoride and the acid-catalysed esterification of propionic anhydride with butanol. The proposed method consists in the practical application of the Lateral Injection Reactor method (LIR): this method allows to carry out, in a kinetic-free way and knowing only the process recipe, the shift of a synthesis from a semi-batch reactor to a LIR-type reactor, which is PFR with the introduction of theoretically infinitive side injections. This solution, which is difficult to apply in practice, is finalized with the more practical solution offered by d-LIR (discrete LIR), or a series of CSTRs (s-CSTR). The d-LIR basically consists of a series of PFRs, in which the injections envisaged by the LIR are discretized in several finite dosages. In this study, solutions were proposed to shift from semi-batch recipes, carried out within RC1 calorimeters, to d-LIRs, physically realized using glass coils inserted into a heat exchanger, and to CSTRs, physically realized using an EasyMax workstation. Starting from the laboratory-scale recipes for each reactive system, various configurations were obtained, which were theoretically tested via mathematical simulations. Results, estimated with simulations in a MATLAB® environment, reveal d-LIR and s-CSTR (4-4 stages) which provide the desired products at high conversions (up to 99%), while maintaining the same productivity as the original system.
Molti processi chimici sono caratterizzati da una forte esotermicità, che li rende soggetti al fenomeno termico noto come runaway termico. Essi sono stati storicamente studiati e sviluppati in modalità discontinua al fine di mitigare gli effetti dovuti all'elevata velocità di rilascio di calore. Recentemente, l'incremento della necessità di intensificare i processi ha portato a proporre sempre più tecnologie e soluzioni per rendere le produzioni industriali da discontinue a continue, operando sempre in condizioni di sicurezza. In questo lavoro si propone una configurazione su scala di laboratorio per studiare la transizione da discontinuo a continuo di tre processi reattivi: la nitrazione della FAM a NIM, la nitrazione del 4-Clorobenzotrifluoruro e l’esterificazione acido-catalizzata dell’anidride propionica con butanolo. Il metodo proposto consiste nell’applicazione pratica del metodo dei reattori ad iniezione laterale (LIR), che consente di ottenere in maniera analitica il passaggio da una sintesi semi-batch a reattori di tipo LIR, ovvero dei PFR che prevedono infinite iniezioni laterali, conoscendo solo la ricetta e la politica di dosaggio. Tale soluzione è di difficile applicazione reale, pertanto si concretizza nelle soluzioni più pratiche offerte dal d-LIR (LIR discreto) o da una serie di CSTR (s-CSTR). Il d-LIR consiste fondamentalmente in una serie di PFR in cui le iniezioni previste dal LIR vengono discretizzate in più dosaggi finiti localizzati in punti opportuni. Questo studio propone soluzioni per passare da ricette semi-batch, condotte all’interno di calorimetri RC1, a d-LIR, realizzato attraverso serpentine in vetro, e CSTR, rappresentati da calorimetri EasyMax. Partendo dalle ricette in scala di laboratorio per ciascun sistema reattivo, si sono ottenute diverse configurazioni che sono state testate attraverso simulazioni matematiche. Dai risultati, stimati attraverso simulazioni in ambiente MATLAB®, si ottengono d-LIR e s-CSTR (4-4 stadi) che consentono di avere i prodotti desiderati ad elevate conversioni (fino al 99%), mantenendo però la stessa produttività del sistema originale.
A theoretical study for a lab-scale setup for the practical application of linear injection reactors
Di Figlia, Roberta
2019/2020
Abstract
Many chemical processes are characterized by strong exothermicity, which makes them subjected to the well-known phenomenon of thermal runaway. In order to mitigate the effects due to the high rate of heat release, historically, these processes have been studied and developed in a discontinuous operating mode. Recently, with the increased need to intensify processes, more and more technologies and solutions have been proposed to switch an industrial production from discontinuous to continuous, while maintaining safe conditions. This work proposes a configuration, on a laboratory scale, to study the discontinuous-to-continuous transition of three reactive processes: the nitration of FAM to give NIM, the nitration of 4-Chlorobenzotrifluoride and the acid-catalysed esterification of propionic anhydride with butanol. The proposed method consists in the practical application of the Lateral Injection Reactor method (LIR): this method allows to carry out, in a kinetic-free way and knowing only the process recipe, the shift of a synthesis from a semi-batch reactor to a LIR-type reactor, which is PFR with the introduction of theoretically infinitive side injections. This solution, which is difficult to apply in practice, is finalized with the more practical solution offered by d-LIR (discrete LIR), or a series of CSTRs (s-CSTR). The d-LIR basically consists of a series of PFRs, in which the injections envisaged by the LIR are discretized in several finite dosages. In this study, solutions were proposed to shift from semi-batch recipes, carried out within RC1 calorimeters, to d-LIRs, physically realized using glass coils inserted into a heat exchanger, and to CSTRs, physically realized using an EasyMax workstation. Starting from the laboratory-scale recipes for each reactive system, various configurations were obtained, which were theoretically tested via mathematical simulations. Results, estimated with simulations in a MATLAB® environment, reveal d-LIR and s-CSTR (4-4 stages) which provide the desired products at high conversions (up to 99%), while maintaining the same productivity as the original system.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/169802