Analysis of reduction stage of chemical looping packed bed reactor based on the reaction front distribution

Abstract

Traditional combustion of syngas derived from biomass has incurred numerous environmental problems, and syngas chemical looping combustion is environmentally friendly for syngas energy conversion. As a key part of chemical looping combustion, reactor configuration is noticeable. The dynamically operated packed bed reactor is an emerging conception applied to chemical looping combustion. Our attention is paid to the conversion of the oxygen carrier in the packed bed as the limited maximum conversion of the oxygen carrier in a packed bed is unclear. In this paper, the reaction front distribution during iron oxide reduced by CO is firstly proposed on the basis of chemical equilibrium and then validated by the effluent gas profile. Based on the reaction front distribution, the detail of the reduction stage in iron-based chemical looping combustion is analyzed to obtain the characteristics of reaction fronts. The reaction rates of reduction from Fe2O3 to Fe3O4, Fe3O4 to Fe0.947O and Fe0.947O to Fe are 5.280, 3.329 and 4.379 mol m−3 s−1, respectively. And the velocities of reaction front I, II, III are 0.605, 0.326, 0.044 cm min−1, respectively, which demonstrate the reaction front distribution. The methodology established in this paper can be used to study multiple reaction front system in the packed bed reactor.