Study of Conditions of Binary Particle Mixture Motion Applied to Chemical Looping Combustion of Fuel with Carbon Dioxide Capture

Аннотация

Chemical looping combustion and gasification of fuels with using metal oxides as oxygen carriers is a rapidly developing technology for capturing carbon dioxide. This technology is based on the use of interconnected reactors with a fluidized bed and circulating fluidized bed. Crucial in the technology is the reliable security of a high solid circulation rate between the reactors to maintain the desired temperature. When burning solid fuels, ash particles inevitably enter the metal oxide stream. This can lead to a change in the hydrodynamic parameters of an interconnected reactor system. In this paper, we present the results of an experimental study of fluidization conditions and hydrodynamics of a reactor with a circulating fluidized bed under motion conditions of binary mixtures of particles with different density. We also justified the conditions for simulating the particle sizes of heavy and light fractions as well as their mass in the reactor and a portion of a light fraction. We showed that, at a small addition of a light fraction, the minimum fluidization rate decreases markedly. Particle segregation was observed for large metal oxide particles, while light particles were found to be near the layer surface. The addition of a light fraction with a mass fraction of 3–12% does not significantly affect the mass flow profile of particles in a circulating fluidized bed reactor. The fractional composition of the particles in both the upward flow in the center and the downward stream near the walls of reactor is approximately the same. In the central part of the riser, the concentration of the light fraction was found to be slightly higher than its average value. The obtained results support the possibility of using the previously developed dependences for the calculation of hydrodynamics under motion conditions of binary mixtures of particles of different densities in the presence of a light fraction of 3–12%.