Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

PP-III-20Furthermore, Ayude et al. (2007) has carried out a systematic characterization of the timeevolution of the liquid holdup at different axial positions within a mini-pilot scale cold mockup of a trickle bed reactor operated with ON-OFF liquid flow modulation.The objective of the present contribution is to include the acquired hydrodynamicinformation into the model at the particle scale for examining the response of an isothermalTBR to a liquid flow modulation ON-OFF strategy. Additionally, we proposed to extend themodel towards the reactor scale for analyzing the actual reactor output and to validate themodel robustness and capability of prediction against experimental results reported inliterature.Slow ON-OFF modulation is described in the model as induced by a cyclic square-waveof the liquid velocity in the top of the reactor. The model assumes that, during the ON cycle,the external surface of the particle is completely wet. Likewise, once the liquid flow rate is cutoff, the liquid drains and the liquid holdup diminishes progressively up to the static holdupvalue, if the dry time is long enough. External wetting efficiency and mass transportcoefficients are linked to the liquid holdup value obtained during each operation stage, ONcycle or OFF cycle.Total internal wetting is considered during the whole cycle. The kinetic is assumed to befirst order with respect to both, gas and liquid reactants. Non steady state mass balances forthe gas and liquid reactants inside an spherical catalyst particle and for the bulk liquid areformulated and solved by the alternating direction implicit method.Reactants radial and angular profiles within the catalyst, as well as axial variation in thereactor can be evaluated with the model for any moment during the cycle.References1. Ayude M., Cassanello M., Martinez O., Haure P. (2005) Chemical Engineering Science, 60, 6262-6269.2. Ayude M., Martinez O., Haure P., Cassanello M. (2007) Chemical Engineering Science. 62, 6002 – 60143. Silveston, P., Hanika, J. (2002) Chemical Engineering Science, 57, 3373 - 3385.342