A fixed-bed reactor for energy storage in chemicals (E2C): Proof of concept

A new type of fixed-bed reactor for endothermic reforming, e.g. steam-methane reforming (SMR) or dry reforming of methane (DRM), is proposed. The reactor consists of two sorts of spherical particles: electrically conductive particles (large) and non-conductive catalyst particles (small). The main feature of this reactor is the application of electric resistance heating using the electrically conductive particles, which heat the non-conductive catalyst particles and reacting gas inside the reactor. In this work we consider a cylindrical fixed bed, which is 50 cm tall and has a bottom diameter of 10 cm, filled with electrically conductive particles made of nickel and with 1 cm in diameter. The open-source discrete-element method (DEM) software Yade is used to generate cylindrical fixed beds with binary dispersion. Steady-state particle temperatures are calculated based on a new 1D Euler - 3D Lagrange discrete heat transfer model that includes conduction between particles, forced convection and radiation. The design parameters of the fixed beds are calculated numerically based on the current distribution, temperature uniformity and amount of catalytic sites. The ideal catalyst radius is selected to be 0.4 of the radii of the conductive particles, based on the maximum radius at octahedral sites of closed packing. Analysis of simulations based on the electrical current and 3D temperature distribution revealed that the optimal volume fraction of the catalyst is determined to be between 0.27 and 0.30.