Modeling of Surface-bed Reactor for Endothermic and Exothermic Reactions Coupling

Catalytic Combustion for Supplying Energy for Endothermic Reaction

“…Among all these parameters, the authors recognized that the variables that have greatest influence on the reactor performance are in the order: the difference in the activation energies between the exothermic and endothermic reactions, the inlet temperatures, the velocities and composition of the inlet streams and, finally, the reactor geometric characteristics and the thermal conductivity of the walls. Further insights in the role played by the geometrical characteristics of the system were provided by Vaccaro and Ciambelli [89] who showed that at constant inlet flow rates, no significant variation occurred in the performance of a microstructured reactor when the height of the reactor channel (i.e. the distance between the catalytic layer and the facing wall) was varied in the range 0.5-2.0 mm.…”

“…The coupling of the Navier-Stokes equations with the energy and mass balances wasconsideredto simulate the behaviour of several reacting systems. They include the use of methane as fuel both for the steam reforming and combustion reactions [36,38,45,51,67,89], the dehydrogenation of ethane associated with the combustion of methane [34] and the combustion of hydrogen coupled with the steam reforming of methane [40]. Several modelling works dealing with the methane steam reforming occurring in plate reactors are reported in the literature [30,34,42,53,99,101,133]; additionally, Zanfir and Gavriidilis [30] proposed a quite exhaustive study on the combination of exothermic and endothermic reactions both from an experimental and a modelling perspective.…”

“…However, a one-dimension approach may fail in correctly predict the reactant conversion rates in systems where the mass transport is the rate-limiting stage of the process [134]. In these cases the use of 2D models wasshown to be beneficial [30,34,99]; furthermore, it has also the advantage to investigate the effect of geometric parameter (such as the wall thickness and the channel height) on the reactor performance and to substitute the calculation of the heat and mass transfer coefficients with the direct resolution of the fundamental transport equation [36][37][38]89]. However, Zanfir and Gavriilidis [30] showed that a reactive system can be successfully modelled considering a mixed dimensional approach: two dimensions for describing variations occurring in the gas phase and in the solid walls and one dimension to model the temperature change in the catalyst layers, which due to their small thickness, were assumed isothermal in the direction normal to that of the fluid stream.…”

“…Knowing how the temperature changes inside a reactor is essential in order to properly design the catalyst shape and distribution. In microstructured reactors, where flow is mostly laminar [31,34,36,38,44,89], directed, and highly symmetric, the catalytic material is arranged as washcoat layers on the wall of the reactor channels. Several studies were carried out to figure out the effect of the configuration of the washcoat on theprocess rate [141][142][143] pointing out that its thickness may greatly influence the rate of the mass transport and, then, the rate of the process [143].…”

“…Several studies were carried out to figure out the effect of the configuration of the washcoat on theprocess rate [141][142][143] pointing out that its thickness may greatly influence the rate of the mass transport and, then, the rate of the process [143]. Such a consideration highlights the importance of considering the diffusion of species inside the layer of solid catalyst [36,38,89] without the approximation that the catalytic layer has zero thickness and the reaction occurs only on the flat external surface [45,139]. On the other hand, deep washcoats may result unnecessary.…”