Trickle‐bed reactors: Tracer study of liquid holdup and wetting efficiency at high temperature and pressure
ABSTRACT Liquid holdup and wetting efficiency were measured by means of stimulus-response (pulse-tracer) experiments in a trickle-bed reactor, packed with a commercial hydrodemetallization catalyst, and operated at 10 MPa and 330–370°C, with a superficial liquid velocity of 1.4 to 8.3 × 10−4 m/s. The total liquid holdup was obtained from the first moments, and the external wetting efficiency from the second moments, of the response curves. The dynamic holdup obtained from the total holdup lies within the range described by existing correlations, but wetting efficiency is significantly lower than literature data obtained at ambient conditions.On a mesuré la rétention du liquide et l'efficacité du mouillage par des expériences stimulus-réponse (traceur-impulsion) dans un réacteur à lit ruisselant, garni avec un catalyseur commercial d'hydrodémétalisation, et fonctionnant à 10 MPa et à 330–370°C, avec une vitesse liquide superficielle de 1,4 à 8,3 × 10−4 m/s. On a obtenu la rétention liquide totale des premiers moments de la courbe des réponses et l'efficacité du mouillage externe des deuxièmes moments. La rétention dynamique obtenue à partir de la rétention totale se situe dans la gamme couverte par les corrélations existantes, mais l'efficacité du mouillage est nettement inférieure aux données publiées aux conditions ambiantes.
01/2003; 19(6). DOI:10.1515/REVCE.2003.19.6.531
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ABSTRACT: Computational fluid dynamics is used to describe both wetting efficiency in simple configurations of stacked solid particles and catalyst efficiency inside such partially wetted catalyst particles. The volume of fluid (VOF) model used to describe hydrodynamics leads to realistic and promising results for surface wetted ratio. Catalyst efficiency simulations have been performed for different shapes of particles and different Thiele modulus values for a first order reaction rate. Results show that for all the shapes studied, catalyst efficiencies of partially wetted particles can be calculated by simply using a modified Thiele modulus defined as ratio of the actual Thiele modulus φφ to the wetting efficiency f.Chemical Engineering Science 01/2010; 65(1):255–260. DOI:10.1016/j.ces.2009.06.027 · 2.61 Impact Factor
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ABSTRACT: Hydrodynamics experiments with respect to supercritical and subcritical fluids were conducted in a laboratory-scale trickle bed reactor filled with relatively small particles of 0.67-1.32 mm in diameter. Residence time distribution was measured with tracer injection, and the results indicated that the supercritical fluids (SCF) have non-liquid-like features. From the pressure drop fluctuations, the pulsing flow was observed with the increase of the supercritical fluid mass flux; clearly, it shows that SCFs possess liquid-like property. Based on the empirical relationship proposed by Al-Naimi et al. (2011), the experimental data for subcritical fluids could be well correlated, which results in a new correlation in the predication of the pressure drop for fluids at subcritical conditions.Chemical Engineering Science 08/2013; 100:69-73. DOI:10.1016/j.ces.2013.03.042 · 2.61 Impact Factor