Dynamic operation of a bench-scale CO2 capture system with non-aqueous and monoethanolamine solvents in process-intensified equipment

Abstract

Power-integrated CO2 capture plants must operate flexibly to match fossil-based power generation balanced by fluctuating renewable energy and variable electricity demand. Process intensification (PI) offers improved capture plant responsiveness and economics through optimized equipment and solvents. This study presents the first reported dynamic testing in a PI system, consisting of a rotating packed bed (RPB) absorber and a two-stage flash (2SF) coupled with RTI International’s non-aqueous solvent (NAS). NAS performance in the PI system was compared to equivalent scale conventional equipment and 30 wt% monoethanolamine (MEA) in the RPB absorber. Dynamic testing consisted of load-following with 10% throughput per minute (%/min) ramp-sequences representative of natural-gas combined cycle operation. NAS effectively rejected ramp disturbances during initial tests with conventional equipment.
NAS CO2 capture rate (CR) in the PI system was stable and only 8.5% lower in the non-optimized PI equipment compared to the conventional system. In the PI system, MEA CR was 18.9% lower than NAS, highlighting NAS’ enhanced kinetics and suitability for PI systems. RPB optimization is projected to allow equivalent CR in ∼90% smaller equipment compared to a conventional absorber. The 2SF regenerator performed equivalently to the conventional regenerator with NAS, with the benefit of ∼60% smaller equipment and reduced compression equipment size resulting from higher pressure regeneration. PI equipment size reductions can significantly reduce capital costs and the overall cost of capture. Process intensification, aided by proactive controls systems, is expected to provide greater benefits during start-up and shut-down scenarios by reducing thermal inertia and hydrodynamic lag.