Onset of pulsing in trickle beds: Critical
assessment
and state-of-the-art correlation
Faïçal LARACHI*, Ion
ILIUTA§, Min CHEN and Bernard P.A. GRANDJEAN
Department
of Chemical Engineering & CERPIC,
Laval
University, Québec, Canada G1K 7P4
§On
leave from Department of Chemical Engineering
Faculty
of Industrial Chemistry
University
Politehnica of Bucharest, Polizu 1, 78126 Bucharest, Romania.
Can. J. Chem. Eng., 77 (1999) 751-758
Abstract:
The transition between trickle flow and pulse flow regimes in cocurrent
trickle-bed reactors is not properly predicted by existing phenomenological,
semi-theoretical and empirical tools. Based on the most complete flow
regime transition data base (700 measurements, 30 gas-liquid systems, 18
columns diameters, 38 packing materials, high pressure conditions, coalescing,
non-coalescing and pseudoplastic non-Newtonian aqueous and organic liquids), a
state-of-the-art explicit correlation of trickle-to-pulse flow changeover was
derived relying on neural network modeling. Robustness of the proposed
correlation was verified, and the limitations of the literature correlations
and models were demonstrated through systematic statistical testing over the
constructed data base. The overall result was a net improvement in predicting
the trickle-to-pulse flow regime transition.
Résumé: La transition ruisselant-pulsé dans les réacteurs à lit
fixe arrosé est mal estimée par tous les outils de prédiction développés à ce
jour, qu’ils soient phénoménologiques, semi-théoriques ou simplement
empiriques. Partant d’une vaste base de données expérimentale sur cette
transition (700 mesures expérimentales, 30 couples gaz-liquide, 18 diamètres de
colonne différents, 38 garnissages, des données à haute pression, des liquides
coalescents, non-coalescents, pseudoplastiques nonNewtoniens, oganiques et
aqueux), nous avons élaboré une corrélation explicite générale basée sur les
réseaux neuronaux à couches. La robustesse de la corrélation proposée a été
vérifiée, ainsi que les limitations des modèles et corrélations de la
littérature discutées au moyen de tests statistiques. Le résultat global est un
nouvel outil amélioré pour prédire le mieux possible l’ensemble des données
expérimentales de la littérature publiées entre 1964 et 1997.
You
can get the transul.zip file to compute
the liquid velocity at the trickle-pulse flow transition.
The zip file contains the following source codes:
-
Fortran
-
QuickBasic
You may
also download our Excel worksheet Trickle-bed simulator to simulate mass transfer, pressure
drop, liquid holdup and flow regime transition.
The neural correlation was
developped with the software NNFit