CCS and Power Systems
Advanced Energy Systems - Advanced Combustion Systems
Solid-Fueled Pressurized Chemical Looping with Flue-Gas Turbine Combined Cycle for Improved Plant Efficiency
Performer: University of Kentucky
Project No: FE0009469
The University of Kentucky Center for Applied Energy Research (CAER) is developing a heat-integrated coal-based combined cycle for power generation using a pressurized chemical looping combustor (PCLC). The PCLC system may achieve an overall plant thermal efficiency of approximately 48 percent [lower heating value (LHV)] by passing the high-temperature flue gas through a gas turbine for electricity generation and a heat recovery steam generator (HRSG) for supercritical steam production used to drive a conventional steam cycle.
The PCLC system contains an oxidizing reactor, in which oxygen from air is selectively fixed into an oxygen-carrier structure, and a reducer reactor 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 stream from the oxidizer used to drive a gas turbine followed by a HRSG, and (2) a small-volume CO2-enriched stream from the reducer for sequestration. Advantages of the PCLC system include lower power requirements for compression of the enriched CO2 stream, reduced reactor size due to elevated operation pressure, and significant reduction to cost of electricity (COE) of a commercialized CLC power plant by using a relatively high-performance and cost-effective iron-based oxygen carrier. The PCLC system holds potential to meet DOE’s target of limiting the energy penalty with no more than a 35 percent increase in the COE, while capturing at least 90 percent of the CO2 released during the combustion of fossil fuels.
A design basis and final design package will be developed in Phase I. The major equipment will be sized using data obtained from previous thermogravimetric analyses and bench- and pilot-scale apparatuses operated at CAER and Southeast University (SEU), respectively. The data will be used to determine suitable reaction kinetics, oxygen carrier make-up rate, carbon slip ratio between air and fuel reactor, as well as temperature and pressure profiles along the reactors. A rate-based Aspen Plus® process model will be built for the heat-integrated combined cycle to provide the necessary stream table for technical analysis. A detailed process design basis and engineering flow chart with appropriately sized equipment will be provided for an economic analysis of a commercial-scale PCLC system.