Chemical Engineering

Chemical-looping combustion (CLC) is a next generation combustion technology that has shown great promise in addressing the need for high-effi ciency low-cost carbon capture from fossil fueled power plants to address rising carbon emissions. A computational fl uid dynamics (CFD) simulation is developed using the Eulerian approach based on a laboratoryscale experiment with a dual fl uidized bed CLC reactor. Th e salient features of the fl uidization behavior in the air reactor and fuel reactor beds are accurately captured in the simulation. Th e results highlight the need for more accurate empirical reaction rate data for future CLC simulations. Th e spouted fl uidized bed setup provides several advantages when solid coal is used as fuel for CLC. Th e Lagrangian approach known as Discrete Element Method (DEM) coupled with the CFD solution of the fl ow fi eld provides an eff ective means of simulating the behavior of such a bed. Th e overall results using Fe-based oxygen carriers reacting with gaseous CH4 confi rm that chemical reactions have been successfully incorporated into the coupled CFD-DEM simulations. The results indicate a strong dependence of the fl uidization behavior on the density of bed material and provide important insight into selecting the right oxygen carrier to improve performance. Th is work provides a basis for future simulations of CD-CLC systems using solid coal as fuel. Given the high computing cost of CFD-DEM, it is necessary to develop a scaling methodology based on the principles of dynamic similarity that can be applied to a CFD-DEM simulation to expand the scope of this approach to larger CLC systems up to the industrial scale. A new scaling methodology based on the terminal velocity is proposed for spouted fl uidized beds. Simulations of a laboratory-scale spouted fl uidized bed are used to characterize the performance of the new scaling law in comparison with existing scaling laws in the literature. It is shown that the proposed law improves the accuracy of the simulation results compared to the other scaling methodologies while also providing the largest reduction in the number of particles.