Dynamic operation with non-aqueous solvent at Technology Centre Mongstad for natural gas combined cycle post-combustion CO2 capture

Abstract

Without increased electricity storage, thermal power generation will supplement deficits in intermittent renewable electricity. Power-integrated, post-combustion CO2 capture plants (PPCPs) must be capable of treating variable flue gas flowrates. Dynamic process models will be necessary to validate PPCP operation and control structures but require experimental pilot data from realistic scenarios.
In 2022, RTI International demonstrated its non-aqueous CO2 capture solvent (NAS) at Technology Centre Mongstad, including dynamic operation with natural gas combined cycle (NGCC) conditions. This is the first reported dynamic study with a water-lean solvent. The testing included load following, cold start-ups with lean and rich solvent, and hot start-ups with varied steam supply timing.
Maintaining low lean solvent CO2 loading, primarily governed by regenerator temperature, was crucial for consistent CO2 capture under load variation. Constant L/G ratio during load ramping gave reasonably consistent capture but could be improved by well-tuned steam supply. Cold-lean startup marginally improved the time to reach steady state compared to cold-rich startup—in both cases the cold regenerator initially minimized the solvent working capacity. Hot-lean start-up reduced the time to reach 90% capture by 70%, achieving an average capture rate of 82.3% compared to 63.5% for the cold-lean start. Applying steam 20 min earlier further reduced the time to 90% capture by 95% with no penalty in SRD due to the improved average capture rate of 88.5%. Low-quality steam from NGCC plants should be utilized to preheat the regenerator if available. Process intensified equipment (flash tanks, rotating packed beds) may further improve dynamic response.