Experimental demonstration of pressurized chemical looping combustion in an internally circulating reactor for power production with integrated CO₂ capture

This study presents an experimental demonstration of pressurized chemical looping combustion (CLC) in an internally circulating reactor (ICR). The ICR concept is a novel alternative to the conventional interconnected fluidized bed CLC configuration as it eliminates all cyclones, loop seals and solids transport lines, and it can be pressurized in a single pressure shell. Stable operation with high fuel conversion was established for about 40 h of operation at pressures up to 6 bar, achieving reasonable CO₂ purity and capture efficiency (up to 97%). The solids circulation rate was found to increase with increasing the operating pressure at a constant fluidization velocity with no effect on CO₂ capture and purity. The experimental campaign also examined the effects of solids inventory and fluidization velocities in the air and fuel reactors. The CO₂ purity and capture efficiency were most sensitive to the solids inventory, whereas the solids circulation rate was most sensitive to the air reactor fluidization velocity and the solids inventory. A correlation for solids circulation rate was derived from the collected experimental data, thus providing a robust tool for designing an ICR system for pressurized operation. This correlation can assist in further scale-up and demonstration of the ICR concept in commercial scale.