CO2 CAPTURE FROM FLUE GAS BY POTASSIUM-BASED SORBENT IN CIRCULATING-TURBULENT FLUIDIZED BED

Abstract

The purpose of this research is to study the carbon dioxide capture process using solid sorbent in a circulating fluidized bed reactor. From previous research work, it was found that the hydrodynamics under circulating turbulent fluidized bed (CTFB) regime can promote the solid sorbent for CO2 capture process, due to the combination of advantages of fast fluidization and turbulent regimes. The solid sorbent being used in this study was potassium carbonate on alumina supporter. The study started with finding the operating condition in the riser so that the particles flow in the reactor fell in the circulating turbulent fluidization regime. The experiment showed that when the gas velocity is 1 m/s, the flow will be performed in the CTFB regime and it was confirmed by the uniform distribution of solid volume fraction along the riser. The solid volume fraction in this case was 0.15. Then, the kinetic of the adsorption under several operating flow regimes in the riser was studied and the kinetic parameters corresponding to each regime were determined using deactivation kinetic model. The estimated parameters showed that the kinetic of the circulating turbulent fluidized bed and the bubbling fluidized bed were quite similar. For the completion of the system, the research also studied the downer reactor which functions to regenerate the spent sorbent by studying the hydrodynamics and kinetic inside the reactor. The hydrodynamic was studied by using 2D computational fluid dynamic model. The adjustment of pressure drop (0.90 – 0.99 atm) and recirculating rate of the particles (250 – 1000 kg/m2.s) were simulated and the results showed that the particles have higher mean free path when the recirculating rate of the particles was lower. For the kinetic of KHCO3 sorbent regeneration, the thermogravimetric method was conducted under nonisothermal condition to determine the kinetic parameters and the analytical method model was selected to represent the regeneration model.