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

MODELLING OF PERIODIC OPERATION IN TRICKLE BEDREACTORS: INFLUENCE OF THE UNSTEADY STATEHYDRODYNAMICSPP-III-20María A. Ayude 1 , Osvaldo M. Martínez 2 , Miryan C. Cassanello 3 , Patricia M. Haure 11 INTEMA, CONICET, UNMdP. J.B. Justo 4302, 7600 Mar del Plata, Argentina.E-mail: mayude@fi.mdp.edu.ar2 Dep. Ing. Química, FI-UNLP–CINDECA, Calle 47 No 257, 1900 La Plata, Argentina.3 PINMATE, Dep. Industrias, FCEyN–UBA Int. Güiraldes 2620, C1428BGA Buenos Aires,ArgentinaKeywords: liquid flow modulation, trickle bed reactors, modeling at the reactor scaleAbstractTrickle Bed Reactors (TBRs) provide flexibility and simplicity of operation, as well ashigh throughputs and low energy consumption. They are widely used in the chemical,petrochemical and petroleum industries, in biochemical and electrochemical processing and inwaste water treatments. In most of the applications, the reaction is gas-limited, thereforesteady-state operation of TBRs is usually controlled by mass transport of the gaseous reactant.Reactor performance may be enhanced by an appropriate liquid feed strategy such as ON-OFF Liquid Flow Modulation (LFM). In this Process Intensification technique, the liquidflow rate is periodically interrupted while the gas phase passes continuously during the entireperiod. Therefore, the external surface coverage of the catalyst particles varies periodically, sothe supply of the gaseous reactant is enhanced. Pulsation of the liquid phase can be imposedwith a simple modification of the existing plant at very low costs and benefits could be quiteprofitable. For this reason, in the last few years, many researchers are exploring thisalternative. (Silveston and Hanika, 2002).Performance enhancement in terms of production capacity and/or conversion andhydrodynamic studies has been reported by several authors. However, a cycling strategy isstill not being applied commercially mainly due to the lack of an established methodology ofdesign. Hence, rigorous experimental and modeling efforts are still necessary to understandthe phenomena underlying periodic operation before commercial implementation.In this context, Ayude et al. (2005) have formulated and solved a comprehensive model,aimed at the particle scale, to describe the course of a gas liquid reaction taking place withinan isothermal porous catalyst subjected to ON-OFF cycling. The model allows deciding apriori if a cycling strategy would modify TBR performance for a given reaction system.341