Reducing Regeneration Energy and Capital Costs in an Advanced Pccc System

With regard to post combustion CO₂ capture (PCCC) processes, the cost of capture is of vital importance to mitigating emissions. In order to meet the goal of reducing the cost of capture set forth by the U.S. Department of Energy to <$40/tonne of CO₂ captured¹, the University of Kentucky Center for Applied Energy Research (UKy-CAER) has designed and constructed a 0.7 MWe CO₂ capture system integrated with a coal-fired power plant. This novel CO₂ capture system has been in operation since May 2015 at Kentucky Utilities E. W. Brown Generating Station located in Harrodsburg, KY.

The UKy-CAER PCCC process utilizes several advanced features compared to conventional post-combustion CO₂ capture technologies. First, a dual stage stripping arrangement utilizing a conventional steam-driven stripper and an air-swept column as a secondary stripper provides for a leaner CO₂ solvent return to the absorber. Thus, the solvent working capacity is increased and the solvent regeneration energy requirement is reduced. Second, a dual-stage cooling tower is used to provide lower cooling water temperatures by removing moisture from the cooling air via a liquid desiccant. With these features, the UKy-CAER technology has been shown to have regeneration energy requirements lower than a standard PCCC process. The UKy-CAER PCCC process with a 30 wt% MEA solvent regeneration energy was found to be approximately 1350 BTU/lb-CO₂; 12% lower than DOE Reference Case 10. Utilization of an advanced solvent resulted in a solvent regeneration energy of 1000 BTU/lb-CO₂; 35% lower than DOE Reference Case 10.

Furthermore, throughout the testing campaigns, material corrosion studies were completed to evaluate performance of bare carbon steel, stainless steel, and coated carbon steel in various locations of the process. It was found that the corrosion rates of all materials were low in the cool lean solvent return piping and absorber, <0.01 mm/yr². Thus, significant cost savings could be achieved by using carbon steel in these locations. Solvent degradation and emission studies were also performed with degradation and emission rates in parallel with previous publications for MEA solvents.

REFERENCES

1. DOE/NETL, “DOE/NETL CO₂ Capture R&D Program,” presented at 2014 NETL CO₂ Capture Technology Meeting, Pittsburg, PA, July 2014.
2. “Use of Carbon Steel for Construction of Post-Combustion CO2 Capture Facilities: A Pilot-Scale Corrosion Study” W. Li, J. Landon, B. Irvin, L. Zheng, K. Ruh, L. Kong, J. Pelgen, D. Link, J. D. Figueroa, J. Thompson, H. Nikolic, K. Liu, Ind. Eng. Chem. Res., 2017, accepted. http://dx.doi.org/10.1021/acs.iecr.7b00697