INVESTIGATION OF CHEMICAL-LOOPING COMBUSTION OF COAL WITH IRON ORE AS OXYGEN CARRIER UNDER PRESSURIZED CONDITION

摘要

Pressurized chemical-looping combustion combined cycle (PCLC-CC) has the potential to enhance the overall system efficiency and lower the cost for CO2 capture and storage (CCS) in comparison with atmospheric CLC system.In this context, experiments on coal-fuelled CLC process with low-cost iron ore as oxygen carrier were conducted under pressurized conditions in a laboratory-scale fluidized bed reactor and a pressurized thermogravimetric analyzer (PTGA) with the pressure ranged from 0.1 MPa to 1.0 MPa.The results from the fluidized-bed reactor were also compared with the published results in a pressurized laboratory-scale fixed-bed reactor to demonstrate the performance difference with respect to reactor arrangement.The results indicated that both reactor arrangements showed similar behaviors under pressurized conditions, the CO2 yield and carbon conversion reached their maximum at 0.5 MPa with the pressure increasing from 0.1 MPa to 0.6 MPa, but lower of these values were observed under fluidized-bed condition due to the gasification products bypassing the oxygen carrier bed leading to relatively poor mixing between coal and oxygen carrier particles.The TGA experiments confirmed the decrease in the reaction performance between coal and oxygen carrier over 0.5 MPa was mianly ascribed to suppression of devolatilization process under high pressure leading to the decreased char reactivity.Overall, the results laid a foundation for the PCLC process operated under interconnected fluidized-bed conditions.