Bench Scale Development of a High-Performance Drop-in Solvent for Flue Gas CO2 Capture

Abstract

Susteon has developed a drop-in high performance, water-lean, mixed amine solvent (trademarked as Sustenol™) with fast absorption and desorption kinetics for significantly improved CO¬2 capture efficiency for flue gas streams with a low CO2 concentration (~4 vol%) such as flue gas from natural gas combined cycle (NGCC) power plants. Amine-based solvent absorption technology is the most mature and reliable technology for CO2 capture at a large scale such as from a power plant flue gas; however, the amine absorption process requires large absorption columns which result in high capital costs and energy requirements (typically >3.0 GJ/tonne of CO2). Using a design of experiments methodology, Sustenol™ solvent was optimized for a significantly lower energy for regeneration. Furthermore, the solvent exhibits significantly lower sensible heat in addition to having three times higher absorption kinetics compared to 30 wt% monoethanolamine (MEA) solvent. The optimized Sustenol™ also shows a higher dynamic CO2 absorption capacity of ~0.5 molCO2/molamine compared to 0.25 molCO2/molamine for 30 wt% MEA. Additionally, the solvent exhibits high oxidative, thermal and hydrothermal stability leading to lower solvent loss and emissions compared to the current leading solvents. These advancements have resulted in a solvent regeneration energy of 2.16 GJ/tonne of CO2 which is >30% lower than current state-of-the-art commercial and emerging solvents. A rate-based thermodynamic process model developed in Aspen Plus™ was experimentally validated with bench and pilot-scale testing results. This process model was used to develop a high-fidelity technoeconomic analysis (TEA) for post-combustion CO2 capture from a 687 MWe NGCC power plant. This TEA indicated the cost of CO2¬ capture by Sustenol™ for 97% CO2 removal at $54/tonne and for 90% removal at $49/tonne, with a pathway to achieve $45/tonne of CO2 with continued process and solvent advancements.

Keywords: water-lean solvent; NGCC flue gas; CO2 capture; absorber efficiency; CO2 desorption, specific regeneration duty, thermal and oxidative stability.