Bechtel Marine Propulsion Corporation Bettis Atomic Power Laboratory West Mifflin, PA Steady-State Power Operation of a Supercritical Carbon Dioxide Brayton Cycle Eric Clementoni Timothy Cox Page 1
Presentation Summary S-CO 2 Brayton Cycle Integrated Systems Test (IST) Overview System Operational Overview Loop startup Normal Operating Conditions Operational Test Results Normal Power Generation Maximum Power Operation Page 2
100 kweist has been main S-CO 2 development focus of BMPC Simple Braytoncycle IST Overview Single variable speed turbine-compressor Single constant speed turbine-generator Single recuperator Focus on system control Rapid startup Power changes Shutdown Heat Source Generator Turbine Turbine Recuperator Compressor Page 3 Sea Water Cooling Water Precooler
IST Physical Layout Hot Oil System Turbine Throttle Valves Turbo-Compressor Compressor Recirculation Valve Recuperator Turbo-Generator Precooler Leakage Collection Compressors Page 4
IST Physical Layout Turbo-Generator Turbo-Compressor(not visible) Recuperator Precooler Page 5
IST Turbomachinery Turbo-Generator Thrust Bearing Turbo-Compressor Compressor/Diffuser Turbine Page 6
Loop Startup Heat up system to supercritical conditions and achieve normal system mass Start up both turbomachines to 37,500 rpm Heat up system to normal turbine inlet temperature Transition TG from motoring to generating Establish normal compressor inlet conditions Page 7
Normal Power Operation Turbine-generator operates at fixed speed with load regulated to maintain speed Turbine-compressor thermal-hydraulically balanced Turbine power = compressor power + losses Power level changed by position of compressor recirculation valve Valve nearly full closed at maximum system power Page 8
IST Power Limitations TG output voltage droops as power is increased Voltage droop affects speed and rotor position algorithm causing delay in firing of IGBTs and degradation of power factor Limited to 24 kwedc (~30 kweac) @ 55,000 rpm Permanent magnet rotor remagnetizedto increase output voltage Resulted in higher power capability New target ~50 kweac @ 60,000-65,000 rpm Page 9
Maximum Power Operation November 2013 **40 kw on power analyzer Page 10
50 System Up-Power Power (kw) or Effieciency (%) 40 30 20 10 0 TG Power TC Power Brayton Power Brayton Efficiency -10 60000 Speed (rpm) 55000 50000 45000 40000 35000 500 1000 1500 2000 2500 3000 3500 4000 Time (seconds) TC Speed Page 11
12 System Mass Flow Rates 10 Flow (lbm/s) 8 6 4 TG Turbine TC Turbine Compressor Compressor Recirc 2 0 60000 Speed (rpm) 55000 50000 45000 40000 35000 500 1000 1500 2000 2500 3000 3500 4000 Time (seconds) TC Speed Page 12
Compressor Map Model Prediction for Design Operating Conditions Test Data Page 13
Summary IST continuing to make progress towards the purpose of demonstrating controllability of the S-CO2 Brayton cycle System operation up to 40 kweac has been demonstrated with good agreement with model predictions Normal power operation over range of power levels up to ~50 kweplanned Page 14
Acknowledgements This paper summarizes work that has been performed a number of devoted engineers, scientists, technicians, and support personnel at the Bechtel Marine Propulsion Corporation and our subcontractors. This paper would not be possible without the efforts of this team. Page 15