Enhancement of a Model for a Bayonet Reactor for Syngas Production by Solar Reforming of Natural Gas or Biogas

Abstract

Enhancement options were considered for an existing steady-state two-dimensional (quasi) homogeneous continuum model of a solar-driven bayonet-type reactor for the mixed reforming of methane that was implemented in MATLAB and Cantera. To improve the model's computation efficiency and stability, the solution strategy for the underlying system of partial differential equations in MATLAB, which combined a self-programmed method of lines discretisation with the ode15i solver, was compared with two alternative approaches involving the Partial Differential Equation Toolbox and the pdepe function. Neither was suited for the implementation of the full chemical model with its algebraic constraints describing the stationary surface chemistry laws. However, a thermal version of the model for the flow of nitrogen through the reactor was successfully solved in pdepe and shows very good correlation with inert experiments and with the previous model. An additional carbon formation submodel was developed, which computes the time-dependent catalyst deactivation function from a theoretically approximated irreversible carbon formation rate for the methane cracking reaction. A qualitative comparison of the submodel with statements from literature revealed inconsistencies, which can be lead back to a lack of connection between the modelling scales. To properly model the carbon-induced deactivation effects on the entire reactor, a full multi-scale approach is required instead.