Relevance of plant design on CLC process performance using a Cu-based oxygen carrier

Abstract

Previously validated mathematical CLC models were used to simulate the process performance of CLC methane combustion using an impregnated Cu-based material and to analyse the effect of the fuel reactor design; being either a bubbling fluidized bed or a circulating fluidized bed. The CLC models considered both the fluid dynamic of the fluidized beds at the specific regime and the corresponding kinetics of oxygen carrier reduction. From the model outputs, the performance of the different systems was assessed by calculating the methane conversion in the fuel reactor. Main results highlights that the selection of a suitable particle size of the oxygen carrier and cross section area are key factors to achieve complete combustion with low solids inventory in the fuel reactor. In addition, the growing of bubbles should be limited in order to achieve high CH4 conversion with low solids inventory values, mainly in the bubbling regime with low cross section areas. Complete combustion was predicted with solids inventory in the fuel reactor of 250 kg/MWth (1 m2/MW and particle size of 0.25 mm) or 125 kg/MWth (0.2 m2/MW and a particle size of 0.15 mm) in the bubbling and turbulent regime, respectively. Considering the pressure drop related to these conditions, conclusions for the optimization design of a CLC unit using the Cu-based oxygen carrier are drawn based on the results of the modelling and simulation.