Modeling of CH4 combustion with NiO/NiAl2O4 in a 10 kWth CLC pilot plant

This paper presents a reactor model for combustion of CH4 with NiO/NiAl2O4 oxygen carriers in the Fuel Reactor of Chemical Looping Combustion (CLC) process. The model hydrodynamics is based on the two phase bubble - emulsion concept of bubbling fluidized beds, validated by residence time distribution tests conducted in a 10 kWth equivalent cold flow prototype. The model kinetics is based on the literature and adjusted based on experimental results from a 10 kWth CLC pilot plant. Results show the necessity of including both non-direct catalytic and non-catalytic direct reaction of gases on the oxygen carriers. The model shows good agreement with experimental results if some kinetic and hydrodynamic modifications are considered, including impact of gas adsorption by falling particles in the bubble phase on the gas exchange coefficient and thermodynamic limitation of CO and H2 combustion.