Direct FuelCell/Turbine Power Plant

Hossein Ghezel-Ayagh

关键词: BRAYTON CYCLE;    CARBON DIOXIDE;    COMBINED-CYCLE POWER PLANTS;    DESIGN;    EFFICIENCY;    ELECTRIC POWER;    ELECTRICITY;    FUEL CELLS;    GAS TURBINES;    HYBRID SYSTEMS;    MANAGEMENT;    NATURAL GAS;    PERFORMANCE;    POWER GENERATION;    POWER PLANTS;    STABILITY;    TURBINES;   

DOI  :  10.2172/973558
RP-ID  :  None
PID  :  OSTI ID: 973558
Others  :  TRN: US201007%%259

美国|英语

来源: SciTech Connect

【 摘 要 】

This report summarizes the progress made in development of Direct FuelCell/Turbine (DFC/T{reg_sign}) power plants for generation of clean power at very high efficiencies. The DFC/T system employs an indirectly heated Turbine Generator to supplement fuel cell generated power. The concept extends the high efficiency of the fuel cell by utilizing the fuel cell's byproduct heat in a Brayton cycle. Features of the DFC/T system include: electrical efficiencies of up to 75% on natural gas, minimal emissions, reduced carbon dioxide release to the environment, simplicity in design, direct reforming internal to the fuel cell, and potential cost competitiveness with existing combined cycle power plants. Proof-of-concept tests using a sub-MW-class DFC/T power plant at FuelCell Energy's (FCE) Danbury facility were conducted to validate the feasibility of the concept and to measure its potential for electric power production. A 400 kW-class power plant test facility was designed and retrofitted to conduct the tests. The initial series of tests involved integration of a full-size (250 kW) Direct FuelCell stack with a 30 kW Capstone microturbine. The operational aspects of the hybrid system in relation to the integration of the microturbine with the fuel cell, process flow and thermal balances, and control strategies for power cycling of the system, were investigated. A subsequent series of tests included operation of the sub-MW Direct FuelCell/Turbine power plant with a Capstone C60 microturbine. The C60 microturbine extended the range of operation of the hybrid power plant to higher current densities (higher power) than achieved in initial tests using the 30kW microturbine. The proof-of-concept test results confirmed the stability and controllability of operating a fullsize (250 kW) fuel cell stack in combination with a microturbine. Thermal management of the system was confirmed and power plant operation, using the microturbine as the only source of fresh air supply to the system, was demonstrated. System analyses of 40 MW DFC/T hybrid systems, approaching 75% efficiency on natural gas, were carried out using CHEMCAD simulation software. The analyses included systems for near-term and long-term deployment. A new concept was developed that was based on clusters of one-MW fuel cell modules as the building blocks. The preliminary design of a 40 MW power plant, including the key equipment layout and the site plan, was completed. The process information and operational data from the proof-of-concept tests were used in the design of 40 MW high efficiency DFC/T power plants. A preliminary cost estimate for the 40 MW DFC/T plant was also prepared. Pilot-scale tests of the cascaded fuel cell concept for achieving high fuel utilizations were conducted. The tests demonstrated that the concept has the potential to offer higher power plant efficiency. Alternate stack flow geometries for increased power output and fuel utilization capabilities were also evaluated. Detailed design of the packaged sub-MW DFC/T Alpha Unit was completed, including equipment and piping layouts, instrumentation, electrical, and structural drawings. The lessons learned from the proof-of-concept tests were incorporated in the design of the Alpha Unit. The sub-MW packaged unit was fabricated, including integration of the Direct FuelCell{reg_sign} (DFC{reg_sign}) stack module with the mechanical balance-of-plant and electrical balance-of-plant. Factory acceptance tests of the Alpha DFC/T power plant were conducted at Danbury, CT. The Alpha Unit achieved an unsurpassed electrical efficiency of 58% (LHV natural gas) during the factory tests. The resulting high efficiency in conversion of chemical energy to electricity far exceeded any sub-MW class power generation equipment presently in the market. After successful completion of the factory tests, the unit was shipped to the Billings Clinic in Billings, MT, for field demonstration tests. The DFC/T unit accomplished a major achievement by successfully completing 8000 hours of operation at the Billings site. The Alpha sub-MW DFC/T power plant unit was returned to the factory for post-operation inspection and analysis. The success of the Alpha Unit operation in the field and achievement of the ultra-high efficiency of 58%, triggered the establishment of a MW-scale commercial product design and development program. Design of a 3 MW (nominal rating) DFC/T Power Plant was completed with an electrical efficiency approaching 60+% LHV of natural gas depending on the design and performance of the gas turbine. Development efforts incorporated lessons learned from the Alpha sub-MW DFC/T power plant demonstration, as well as design features from FCE's commercial product offerings, the DFC1500 and DFC3000 MW-class simple cycle power plants. The 3 MW DFC/T power plant is anticipated to be a superb alternative for large distributed generation applications in locations with high cost-of-electricity.