Coupling Euler–Euler and Microkinetic Modeling for the Simulation of Fluidized Bed Reactors: an Application to the Oxidative Coupling of Methane

Abstract

We propose a numerical methodology to combine detailed microkinetic modeling and Eulerian–Eulerian methods for the simulation of industrial fluidized bed reactors. An operator splitting-based approach has been applied to solve the detailed kinetics coupled with the solution of multiphase gas–solid flows. Lab and industrial reactor configurations are simulated to assess the capability and the accuracy of the method by using the oxidative coupling of methane as a showcase. A good agreement with lab-scale experimental data (deviations below 10%) is obtained. Moreover, in this specific case, the proposed framework provides a 4-fold reduction of the computational cost required to reach the steady-state when compared to the approach of linearizing the chemical source term. As a whole, the work paves the way to the incorporation of detailed kinetics in the simulation of industrial fluidized reactors.

Computational Fluid Dynamics of Reacting Flows at Surfaces: Methodologies and Applications

“…However, the segregated resolution of the two phases usually introduces numerical errors when long time steps, i.e., above 5 Á 10 -6 s, are used. Consequently, the resolution of the reactivity by means of the OC can limit the performances of the Euler-Euler model approach hindering the solution of detailed chemical kinetics along with the whole dynamics of pilot or industrial units [77].…”

“…The multiphase operator splitting (MOS) [77], schematized in Fig. 3, has been developed to overcome the issues highlighted in the aforementioned strategies to treat the reactive multiphase flows.…”

“…In doing so, the time splitting of the phenomena proposed by the MOS leads to a solution only slightly dependent on the time step [77] since the segregation of the strongly coupled phenomena is not performed. Consequently, this numerical approach allows to perform the reactive simulations with the same Courant conditions as for the nonreactive ones enabling the management of detailed description of the chemical kinetics along with the whole dynamics of industrial units by adopting a Eulerian-Eulerian description of the multiphase flow.…”

“…( 34)-( 36)) which represent the convection of species, temperature, and adsorbed species in the solid phase, which are mandatory since the discrete nature of the solid is lost. Additionally, no diffusive transport is considered in the solid due to the granular nature of this phase [75][76][77].…”

Productivity Enhancement for the Oxidative Coupling of Methane in Adiabatic Layered-Bed Reactors

“…18 Bringing together these figures, it can be calculated that 12 million tubes would be required for 1 Mton/year C 2 H 4 , 19 this being equal to 200 multitubular reactors of the largest size possible (50 000 tubes/ reactor 20 ), just for a single plant. It then becomes clear why the industrial implementation of OCM in cooled packed beds is considered unfeasible, which led to a shift in research toward more advanced reactor technologies pursuing isothermal operation, including fluidized beds 21 and membrane reactors. 22 Given the challenges above, the concept of exploiting the heat generated by the reaction, instead of just considering it as a nuisance, steered the interest toward adiabatic operation of OCM reactors.…”