An Energy-Saving Carbon Dioxide Capture Using a Circulating Fluidized Bed

Carbon dioxide capture and storage (CCS) technology has attracted recent attention for the mitigation of greenhouse gas (GHG) emissions and global warming. CCS comprises the separation of carbon dioxide (CO2) from industrial and energy-related sources, its transportation to a storage location, and its long-term isolation from the atmosphere. It is well known that CO2 separation is the most energy-intensive component among these components. Thus, to facilitate its commercial implementation, its capture cost should be further decreased. Recently, the most widely used CO2 capture technologies in industries is chemical absorption using amine-based solutions. In the conventional absorption process using amine solutions, thermal energy is supplied from the bottom of the regenerator, which utilizes reaction heat for regeneration of the solutions and heat of vaporization for stripping. Thus, it is necessary to recover this heat or to develop a new process in order to reduce its capture cost. This research proposes an innovative energy-saving process using chemical absorption by a solid in a circulating fluidized bed. In this process, the reaction heat that accompanies absorption is successfully supplied through a heat pump to achieve thermal decomposition in a regenerator, thereby leading to recirculation of all process heat without heat addition for regeneration of the solutions and vaporization for stripping. Furthermore, absorption experiments were conducted to determine the separation performance. An energy balance of the proposed process was simulated using the experimental data with a commercial process simulator. The simulation results indicate that the proposed CO2 separation process has large energy-saving potential when compared with conventional approaches.