Characterization of Chemical Looping Pilot Plant Performance via Experimental Determination of Solids Conversion

Abstract

Chemical looping combustion (CLC) is a novel combustion process with inherent CO2 separation. A CLC reactor system consists of an air reactor (AR) and a fuel reactor (FR). An oxygen carrier (OC) that circulates between the two reactors transports the necessary O2 for combustion. Because the solids conversion of the OC has an impact on total solids inventory, it is an important parameter for the performance of a CLC combustor. In this study, the solids conversion of a Ni-based OC in a dual circulating fluidized bed (DCFB) reactor system is determined. The pilot rig is fueled with H2 or CH4 at a fuel power of 65−140 kW. FR temperature, air/fuel ratio, and solids inventory are also varied. From the results obtained, the global solids circulation rate (GS) is calculated. GS shows a linear trend with the gas velocity in the AR and is nearly independent of the total solids inventory in the reactor system. It is shown that, in all cases, the solids conversion in the FR (XS,FR) is very low; in most cases, XS,FR is even <0.15. The active NiO content in the particle is experimentally found to be at least 35−36 wt %. Despite the very low H2O/CH4 ratio, no carbon formation has been detected.