A Hydrodynamic Study of Chemical Looping Combustion System for Gaseous Fuel

Chemical looping combustion (CLC) is a promising technology for fossil fuel combustion with inherent CO2 capture and sequestration that is able to mitigate greenhouse gases (GHGs) emission. The CLC process employs metal oxide as an oxygen carrier circulating between fuel reactor, where the fuel is combusted to CO2 and H2O, and air reactor, where the oxygen carrier returned to its oxidized form by aeration. In order to demonstrate and investigate the CLC concept experimentally, several previous studies have been carried out with the aim of improving the performance of oxygen carrier. The performance of the oxygen carrier, which circulate between the air reactor and the fuel reactor to transfer oxygen and heat, is the most important factor that determines the efficiency of the CLC process. In order to evaluate the reactivity of the oxygen carrier, the fuel conversion and CO2 selectivity of oxygen carrier have been investigated using thermogravimetric analyzer, batch type bubbling fluidized bed, etc. However, the hydrodynamic study for the solid circulation of oxygen carrier should be preceded to ensure the steady state operation of CLC process. In this study, the characteristics of solid circulation between the air reactor and the fuel reactor was examined in the bench scale CLC unit made of Plexiglas, and the effects of change of fuel reactor configuration and cyclone on the solid circulation between the two reactors were investigated. Ni based oxygen carrier was used as the bed material and the optimal fluidizing gas flow rate capable of maintaining stable solid circulation were investigated.