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Gas/liquid mass transport in falling film reactor versus theory

  • Introduction: Mass transport at gas/liquid interfaces depends on many factors including the gas and liquid properties and hydrodynamics. The mass transport of a gas through the liquid is a limiting step in many chemical reactions. To gain a fundamental understanding of multiphase interfaces, the rate of mass transfer has been measured for pure gases (H2, N2, O2, He) into a thin liquid film with a well-defined surface area and velocity profile. This enables the mass transfer rate to be broken down into one parameter, which is the gas/liquid interfacial area (a), and a second parameter, which is the mass transfer coefficient (kL). Using gases with varying diffusion coefficients enables a comparison of the measured rates of mass transport to the rates predicted by film theory and penetration theory. Method: A gravity-driven thin water film 0.000180 m in thickness flowing along the outer surface of a capillary was contacted with a gas phase inside a closed system. The liquid wasIntroduction: Mass transport at gas/liquid interfaces depends on many factors including the gas and liquid properties and hydrodynamics. The mass transport of a gas through the liquid is a limiting step in many chemical reactions. To gain a fundamental understanding of multiphase interfaces, the rate of mass transfer has been measured for pure gases (H2, N2, O2, He) into a thin liquid film with a well-defined surface area and velocity profile. This enables the mass transfer rate to be broken down into one parameter, which is the gas/liquid interfacial area (a), and a second parameter, which is the mass transfer coefficient (kL). Using gases with varying diffusion coefficients enables a comparison of the measured rates of mass transport to the rates predicted by film theory and penetration theory. Method: A gravity-driven thin water film 0.000180 m in thickness flowing along the outer surface of a capillary was contacted with a gas phase inside a closed system. The liquid was circulated continuously until it was saturated with gas and the equilibrium pressure was reached. In this device, there is laminar flow, and therefore, the hydrodynamics of the liquid film are well defined. Results: Penetration theory predicts a non-linear relationship between diffusion coefficient (DAB) and mass transfer coefficient (kL). by means of falling film reactor the actual rates of gas-liquid mass transfer are higher than those predicted by theory. Also, a linear relationship between DAB and kL is observed experimentally. The mass transfer coefficient can even, as a rule of thumb, be assumed to be relatively constant with a value of around 10-4 m/s for aqueous solutions.zeige mehrzeige weniger

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Metadaten
Autor*innen:N. Afraz
Koautor*innen:A. Adi, Kristin Hecht
Dokumenttyp:Vortrag
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2021
Organisationseinheit der BAM:2 Prozess- und Anlagensicherheit
2 Prozess- und Anlagensicherheit / 2.2 Prozesssimulation
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurbau
Freie Schlagwörter:Mehrphasenströmung; Stofftransport; Wasserstoff
Themenfelder/Aktivitätsfelder der BAM:Infrastruktur
Veranstaltung:13th European Congress of Chemical Engineering (ECCE)
Veranstaltungsort:Online meeting
Beginndatum der Veranstaltung:20.09.2021
Enddatum der Veranstaltung:23.09.2021
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:03.11.2021
Referierte Publikation:Nein
Eingeladener Vortrag:Nein
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