Carbon Capture

Application of Transformational UKy 3 Tonne/day CO₂ Capture System at A Steel Process Plant

The goal of the proposed work is to test the University of Kentucky (UK) transformative technology with the three synergistic techniques proven at the bench scale using the Department of Energy (DOE)-funded existing (3 tonne CO₂/day for 1.5 vol% CO₂ gas stream) pilot CO₂ capture system (CCS) at the Nucor Steel Gallatin (NSG) Plant, treating evolved gas from a steel galvanizing line. To minimize the CO₂ capture cost associated with the low CO₂ concentration (~1.5 vol%), four objectives will be met via two process intensification techniques and one just-in-time advanced process control protocol: 1) Packing with advanced low liquid to gas mass flow ratio will demonstrate robust wettability for various solvent physical properties and a controlled absorber temperature profile to enhance mass transfer; 2) Advanced stripping with a split-rich feed will result in ~25% reboiler steam savings. Two-phase flow with 2~5% vapor phase, is fed to the middle of the stripper acting as a second source of carrier gas for CO₂ stripping; 3) A model-based feed-forward process control strategy with in-line solvent performance characterization will reduce reboiler specific duty during cyclic operation and dynamic ambient conditions; 4) Finally, a techno-economic analysis (TEA), technology maturation plan (TMP) and environmental, health and safety (EH&S) assessment will be completed. These new technologies work together with any aqueous post-combustion CO₂ process to lower the associated costs and reduce secondary environmental impact.

UK Press Release

Dual-loop Solution-based CCS for Net Negative CO₂ Emissions with Lower Costs

To address the technical challenge from the low CO₂ (~4 vol%) and high O₂ (~12 vol%) concentrations in natural gas combined cycle (NGCC) flue gas along with a very high CO₂ capture efficiency (95+%) and 20% cost reduction from National Energy Technology Laboratory (NETL) reference case B31B in baseline report Rev. 4, the University of Kentucky (UK) is developing a dual loop solution process to lower the capital cost by 50% and offset the operating cost with negative CO₂ emissions and H₂ production. The objectives are to: 1) design, retrofit and research a dual solvent CO₂ capture system (CCS) on the existing UK 0.1 MWth bench-scale facility using natural gas-derived flue gas, augmented to match NGCC CO₂ and O₂ concentrations with 99+% CO₂ capture efficiency; 2) conduct a techno-economic analysis (TEA) to document the benefits of the proposed technology and identify technology gaps for the next scale of development; 3) assess environmental, health and safety (EH&S) issues relating to the solvent and electrodes and their degradations during long-term operation and extrapolate to commercial-scale application; 4) conduct a life cycle analysis (LCA) to document the practical lifetime; 5) develop a technology maturation plan (TMP) for future technology development.

Enhancement of Carbon Capture Reactor Performance

University of Kentucky (UKy) will develop high-efficiency absorber reactor components for natural gas combined cycle (NGCC) carbon dioxide (CO₂) capture plants. Research, design, and assembly of materials with targeted functionality will be combined with advanced additive manufacturing techniques toward the development of enhanced CO₂ capture reactors. The novel components will improve CO₂ mass transfer for highly viscous solvents through increased turbulence on the gas-liquid interface and improved solvent wetting on the packing surface, while maximizing the volumetric productivity of the absorber column. By shortening the packing requirement through enhanced solvent wetting and CO₂ mass transfer via the use of micro-structured packing, the capital cost will be reduced. In collaboration with the Electric Power Research Institute (EPRI), a techno-economic analysis (TEA) will be completed to validate a decrease in capital costs and provide a cost estimate of the technology to achieve 97% carbon capture efficiency. In addition to the technologies making significant progress toward a reduction in the cost of CO₂ capture for NGCC, they also can be broadly applied to most advanced non-aqueous and water-lean solvents. A technology maturation plan will also be developed to describe the current technology readiness level and examine the additional research and development needed to advance these components for NGCC CO₂ capture plants.

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CO₂ Capture at LG&E Cane Run NGCC Power Plant 

To complete a front-end engineering design study (FEED) for the University of Kentucky (UKy) solvent-agnostic low-cost CO₂ capture process retrofitted to the LG&E-KU Cane Run #7 (CR7) natural gas combined cycle (NGCC) power generation unit to capture approximately 1,700,000 tpy CO₂  at >95% capture rate, $49.0/t CO₂, and a regeneration energy of 2.46 GJ/t CO₂. EPRI, UKy, Bechtel, and LG&E-KU propose a FEED for capture of >95% of the CO₂ from CR7 in Jefferson County, KY. This unit is representative of power plants in the Midwest and Midsouth of the US where intermittent renewable power and geographical storage for CO₂ is limited.  An optimized aqueous amine absorption capture process developed by UKy will be applied. NGCC power plants now play a leading role in electricity generation for the U.S. The FEED package developed will provide engineering and cost information that are relevant to retrofitting a carbon capture process on NGCC units. The proposed FEED study is a critical step to deploying economical, high capture-rate carbon capture on NGCCs and could lead to deployment of one of the world’s largest carbon capture processes on a power plant. EPRI will lead and manage the overall project, LG&E-KU will lead the FEED Scope, UKy will lead the design basis, Bechtel will lead the FEED Study and provide engineering and costing, University of Michigan will conduct the Life Cycle Analysis, and Vogt Power will provide cost and performance guidance for the HRSG retrofit.

Ash Fouling Free Regenerative Air Preheater for Deep Cyclic Operation

UK IDEA proposed the In Situ Auto-Cleaning (ISAC) technique that eliminates ash fouling at regenerative air preheater, to improve coal-fired power plant efficiency and reliability for load following deep cyclic operation, which takes place commonly due to the use of alternative energy sources. All season operation of SCR (Selective Catalytic Reduction) for NOx removal at partial loads led to significant ABS (ammonia bisulfate) induced ash fouling. The proposed technique enables the metal surface temperature to be periodically maintained above 400 °F to remove and break down the ABS and ash deposition.

This project is co-funded by DOE and LG&E-KU (a PPL company) in 2019 with total over 2.2 million US dollars. A 250 kWth test unit equipped with commercial heating elements was designed, built, and operated at the E.W. Brown coal-fired power generation station. Up to now, the test unit has been operated over 4500 accrual hours, and 3300 of which was operated with ISAC mode on. Pressure drops across heating elements were maintained low and no performance losses on efficiency have been detected. Current result verifies the ISAC technique helps achieve ash free operation of regenerative air preheater. The 1-year long term campaign is undergoing and expected to be completed in the late summer of 2024.

With the success of this project, potential benefit to existing coal-fired power plants will be threefold with (1) the turn-down ratio of a coal-fired power plant could be as low as 25-30% of baseload to better position itself for grid load handling; (2) 2-3% boiler efficiency improvement could be realized due to low air leaks, low gas pressure drop across the air preheater, and reduced or eliminated use of an in-line gas heater. (3) De-NOx efficiency improvements can be achieved and maintained with relatively high ammonia injection flowrates without the concern of air preheater blockage resulting from ammonia bisulfite/bisulfate formation due to high ammonia slip.

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Fog and Froth-Based Post Combustion CO₂ Capture in Fossil Fuel Power Plants

The main technology under study in the proposed work is an open-tower compact absorber. Flue gas enters the bottom of the absorber and first encounters solvent in a counter-current fashion in a structured packed section where a small portion of the total CO₂ is captured, then passes through a riser to the top of the absorber. Here, the gas encounters a lean amine mist in a co-current fashion in a temperature-controlled environment with 5 times the liquid/gas contact area. Last, the gas and liquid are forced through a froth section where in-situ heat removal increases the mass transfer with a liquid film of <10 µm, which eliminates the CO₂-amine diffusion resistance. This diffusion resistance is the dominant factor impeding overall mass transfer for second-generation CO₂ capture technology. The vastly increased liquid/gas contact area and minimized diffusion resistance allows the column size to be reduced by 70% from a standard absorber design. The in-situ heat rejection will minimize the aerosol formation by erasing the amine quench at the top of the conventional counter-flow packed bed absorbers resulting from the temperature bulge and cooled lean solvent entering the absorber. Combined with other University of Kentucky (UK) Center for Applied Energy Research (CAER) CO₂ Capture System (CCS) features, the proposed study could potentially reduce the CCS capital cost by 57%.

The proposed objectives are to: (1) fabricate, integrate, and research a compact absorber with internal fog and froth formation on the Recipient’s bench post-combustion CO₂ capture facilities with both simulated and coal-derived flue gas; (2) develop and finalize the atomizing nozzle and gas/liquid contactor and operating conditions for the fog and froth formation and destruction; (3) determine preferable location(s) for the in-situ heat rejection and aerosol reduction heat exchanger configuration inside the absorber; (4) conduct a long-term campaign to investigate the effects of solvent degradation on fog and froth formation; (5) assess issues of environmental, health and safety (EH&S) relating to the solvent and its degradation during long-term operation, and extrapolate to commercial-scale application; (6) conduct a techno-economic analysis (TEA) to document the benefits of the proposed technology and identify technology gaps for next step development; (7) prepare and submit a State Point Data Table and Technology Maturation Plan (TMP); and (8) evaluate the performance of the compact absorber when operated with a low bottom temperature (<95 ºF). 

Development of Novel Process Intensification Device, Acoustic Driven Packing Material

The goal of this project was to further research and development of acoustic driven packing material to the relevant environment and bench-scale stage. This technology has shown promising results in the proof of concept and laboratory testing phases and is showing potential for being a transformative technology. Not only for CO₂ capture but for the field of process engineering. Being novel, acoustic-driven packing material has several hurdles in its developmental path before it can be established as a proven technology. It must demonstrate effectiveness at increasing mass transfer in a relevant environment. Scalability must be shown, and its overall process enhancements must outweigh its costs.

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