Numerical Investigation of Sorption Enhanced Steam Methane Reforming Process Using Computational Fluid Dynamics Eulerian−Eulerian Code

Abstract

This paper highlights the use of a fluidized bed reactor of 10 cm i.d. for producing hydrogen by sorption-enhanced steam methane reforming (SE-SMR). The model used for the hydrodynamic behavior of the bed is Eulerian-Eulerian. The kinetics of the steam methane reforming, water-gas shift, and carbonation reactions are based on literature values. Intra- and extraparticle mass transfer effects are considered together with the kinetics in the chemical models. The bed is composed of an Ni catalyst and calcined dolomite. A static bed height of 20 cm is investigated. A volume ratio of dolomite/catalyst is varied from 0-5 during the simulation. Dry hydrogen mole fraction of >0.93 is predicted for temperatures of 900 K and a superficial gas velocity of 0.3 m/s with a dolomite/catalyst ratio >2. Furthermore, the bubble formation in the fluidized bed influence product yields and product oscillations are observed. Another important aspect is that when the dolomite/catalyst ratio is higher than 2 the necessary heat for the reforming endothermic reaction can be almost entirely supplied by the exothermic reaction of carbonation

A heterogeneous dynamic model for the simulation and optimisation of the steam methane reforming reactor

“…This assumption can be bypassed by adding dynamic terms with consistent initial conditions. In the corresponding literature the initial conditions of the partial pressures in the particle (when dynamic heterogeneous problems are considered) are absent [7,62,63] leading to a segmental treatment of the problem. In this work the particle equations are initialised (t ¼ 0) by solving Eqs.…”

Modelling of binary fluidized bed reactors for the sorption‐enhanced steam methane reforming process

“…In the present study, the effectiveness factors are used in order to consider the pore diffusion resistance and surface phenomena in a simple manner. The values suggested by Lindborg and Carlo et al . are applied, they are , , .…”

“…The gas species formation rates used in the gas species mass transport equations are modelled in accordance with Equations (63–67) in Table as given by Carlo et al . and Xu and Froment …”

“…The CFD models presented by Lindborg [21] and Wang [29] were designed for monoparticles (1 pellet-2 properties), whereas the simplified reactor model presented by Johnsen [15] does not consider the complex binary particle mixing/segregation flow behaviours, therefore this type of model cannot be applied for modelling a binary particle fluidized bed reactor for the SE-SMR process. Carlo et al [2] investigated the binary particle flow behaviours for a laboratory-scale SE-SMR fluidized bed using a three-fluid model, but no particle segregation effect was found in their studies. In the literature, it is generally accepted that for a three-fluid model, the binary particleparticle drag is the key term coupling the binary particles in the mixture.…”

Hydrogen-Rich Gas Production by Sorption Enhanced Steam Reforming of Woodgas Containing TAR over a Commercial Ni Catalyst and Calcined Dolomite as CO2 Sorbent

“…The removal of CO 2 shifts the thermodynamic equilibrium of the water gas shift (WGS) reaction to the hydrogen product. Using Ni as metal catalyst, good results have been reported in the sorption enhanced steam methane reforming [9][10][11][12] with hydrogen molar fractions higher than 95% and CH 4 almost completely reformed with an operative temperature that varied between 600 °C and 700 °C. In recent years several papers have reported gasification processes that include CO 2 capture with calcium oxide-based sorbents [13].…”