CFD-DEM Investigation of a Gas-Solid Vortex Reactor Geometry for the Oxidative Coupling of Methane

Process intensification (PI) is essential for a sustainable future since these techniques aid in increasing energy and process efficiency. One possibility to induce PI is via advanced reactor design. Oxidative coupling of methane (OCM) converts methane catalytically to ethylene, the most important bulk chemical in industry. As such, it could contribute to a sustainable carbon economy. One of the main hurdles in OCM reactor design is temperature control due to the high exothermicity linked to the overall reaction scheme. The gas-solid vortex reactor (GSVR) is a new vortex-type reactor that can aid in solving the challenges related to OCM due to its intense mixing characteristics. In the GSVR, a bed of fluidized particles is obtained in a centrifugal field by introducing the feed gas via tangential inlet slots. Momentum is transferred from the injected gas to the granular particles, leading to the rotation and fluidization of the particles. In this work, Euler-Lagrangian CFD modelling (CFD-DEM) is applied to study the mixing phenomena at reactive conditions, particularly segregation and dispersion, in detail within the GSVR. The high degree of dispersion, and related thermal back-mixing, within the GSVR could allow for autothermal operation of OCM, while segregation would allow operation with multiple catalyst types. These characteristics aid in improving future design of the GSVR and in understanding the bed hydrodynamics. Specifically, for segregation, the effect of particle distribution within the polydisperse bed, gas inlet velocity, particle diameter, particle density, and a combined effect is investigated. Dispersion within the bed is evaluated in both the radial and azimuthal direction. Herein, the effect of the gas flow rate and particle diameter is assessed