(162b) Tuning Process Parameters for Enhanced Low CO2 concentration Capture at a 0.7 MWe Post-Combustion Pilot Plant

A post-combustion CO₂ capture technology at the 0.7 MWe scale implemented at the E.W. Brown Generating Station at Harrodsburg, Kentucky, a PPL Corporation facility, primarily funded by the U.S. Department of Energy, National Energy Technology Laboratory (DOE NETL) employs multi-pronged technological approaches developed over several years of experience to continue to lower the cost of carbon capture. The University of Kentucky (UK) CO₂ capture technology is applicable to any second-generation advanced solvent and can be adapted for a wide array of CO₂ concentrations such as for coal-fired or natural gas plants and has been demonstrated for several solvent campaigns where tailored conditions are used to maximize solvent carbon loading at absorber outlet to ultimately reduce the associated energy penalty of the process.

In this work, process insights will be shared on how CO₂ absorption is enhanced in a solvent campaign with a low inlet CO₂ concentration of about 4%, indicative conditions for capture from natural-gas plants. To obtain the desired low inlet concentration, a modified process draws in a stream of ambient air to dilute the flue gas generated at the plant from coal which typically have CO₂ concentrations at ~12-14%. While the reduced driving force for CO₂ transfer from the gas phase into the solvent is a limitation that results in associated high energy of the process from rigorous solvent regeneration conditions, our experimental work has shown that with appropriate systematic tuning of process parameters such as ensuring adequate wetting of packing and maintaining appropriate temperature profile in the absorber, the absorption of CO₂ can be significantly improved to reduce the energy penalty. With reduced liquid-gas (L/G) circulation rates for the low CO₂ concentration, it is necessary process conditions are tuned for increased wetted area. Results for impacts of different solvent circulation rates, steam flow rates with particular emphasis on absorber bulge temperatures in improving capture by ~20% will be discussed. Additionally, the contribution of the effect of reducing the absorber bottom temperature from a cooled flue gas feed to the bottom of the absorber to an overall reduced energy of regeneration for the process will also be highlighted.