Grants and Contracts Details
In the research program, the UKy-CAER team proposes a heat-integrated coal-based combined cycle for future power generation with overall thermal efficiency at approximately 48% (LHV) using a pressurized chemical looping combustor to produce high-temperature flue for electricity generation through a gas-turbine and a heat recovery unit for supercritical steam production to drive a conventional steam cycle. The first key aspect of our system is a PCLC that consists of two reactors: 1) an Oxidizer in which oxygen from air is selectively fixed into an oxygen-carrier structure, and 2) a Reducer (Redox) in which coal is burned by the oxygen carrier. The PCLC will generate two gas streams, (1) a high-temperature, high-pressure, alkali-free, clean gas from the oxidizer used to drive an aero-turbine (Brayton Cycle) followed by a heat-recovery steam generator for Rankie Cycle, and (2) a small-volume CO2-enriched stream from the Redox for sequestration. The second key aspect of our system is to use cost-effective abundant iron-based oxygen carrier. With the presence of water vapor in the CLC system, iron –based OCs show moderate reactivity and capacity, and high resistance to water vapor, ash and attrition. Additionally, the known technical obstacles that impede the application of CLC to solid fuels will be addressed including: (1) use of pulverized coal to increase reaction kinetics and facilitate separation of the spent oxygen carrier from the solid coal residues (ash/carbon); (2) use of a moderate-temperature pyrolyzer to suppress carrier agglomeration and reduce pollutants (~96% of the Hg and portions of the sulfur and alkali); and (3) division of the Redox into two chambers, a down-flow moving bed acting as a gasifier and a partial-reduction reactor for the oxygen carrier, and a low-velocity bubbling bed serving as a deep-reduction reactor and a device for separating the reduced oxygen carrier from the solid coal residues on the basis of density and particle size. Flue gas from the Redox, primarily CO2 and H2O with a limited quantity of CO and H2 will be compressed to CO2 critical point at which the H2O (condensation), CO & H2 (flashing/distillation) are then removed leaving a concentrated CO2 stream (>90%) for sequestration. Heat transfer units are not needed in the Oxidizer or Redox, thereby avoiding the corrosion and erosion associated with heat-transfer surfaces. Potential impacts from the proposed investigation include (1) provision of a higher-efficiency (~48% vs. ~36%) alternate technology for electricity generation with CO2 capture; (2) a cost-effective means to control pollutants such as sulfur, Hg and trace metals by their pre-removal into a relatively small volume, N2-free gas stream; and (3) deep reductions in NOx formation due to a coal-free combustion of OC to generate steam.
|Effective start/end date||10/1/12 → 12/31/13|
- Department of Energy: $599,687.00
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