Conceptual gas turbine modeling for oxyfuel power cycles
Conceptual gas turbine modeling for oxy-fuel power cycles
Who are we • Klas Jonshagen, started my Ph. D work at Lund University in 2006. Plan on presenting my thesis in December 2010 • Hanna Persson will start her Ph. D work the 1 st of June 2010 at Lund University • Egill Maron Thorbergsson, started my Ph. D work at Chalmers University in January Lund University / Chalmers University of Technology
Project objectives • • Cycle analysis of Graz cycle and SCOC Conceptual turbomachinery design Component optimization Full cycle optimization Lund University / Chalmers University of Technology
Graz cycle Lund University / Chalmers University of Technology
Graz model • Collaboration in NEWAC with Graz University – Received IPSEpro model from Wolfgang Sanz (Institute for Thermal Turbomachinery and Machine Dynamics) Cycle efficiency 54. 2% 54. 0% 53. 8% 53. 6% 53. 4% 53. 2% 53. 0% 52. 8% 52. 6% 52. 4% 52. 2% 1623 1633 1643 1653 1663 1673 1683 1693 1703 1713 1723 Inlet turbine temperature [K] Oxygen production and compression, and compression of CO 2 taken into account Lund University / Chalmers University of Technology
Cooling of turbine • The Graz cycle uses a simple stage-by-stage cooling model. * • The cycle efficiency is dependent on gas turbine cooling flow • The Stanton number depends on the conceptual gas turbine design – Blade chord => Re number => Stanton number => Cooling flow => Cycle efficiency *Sanz, W. , Jericha, H. , Bauer, B. , Göttlich, E. , 2007, "Qualitative and Quantitative Comparison of Two Promising Oxy-Fuel Power Cycles for CO 2 Capture“, ASME Paper GT 2007 -27375, ASME Turbo Expo 2007, Montreal, Canada Lund University / Chalmers University of Technology
Cooling of turbine • Validity of Graz cooling model was questioned: • In particular sensitivity towards design choices was feared (Fixed St number was used in Graz publication) • Conceptual design of a large range of turbines resulted in +/-20% variation in Stanton number • Impact on cycle efficiency was +/-0. 3% • It is, at the time of writing , considered that a cooling system predicted by the simple expression can in general be designed Lund University / Chalmers University of Technology
Extend thermodynamic modelling of gases • One of the aspect of oxy-fuel cycles is the high pressure • Beyond 30 -35 bars gases no longer follow the ideal gas law • IPSEpro (heat and mass balance program) limit is 30 bars • To be able to calculate cycle at high pressures we are working on implementation of REFPROP to IPSEpro • REFPROP is an acronym for REFerence fluid PROPerties, program from NIST. Lund University / Chalmers University of Technology
SCOC H 2 O CO 2 H 2 O Fuel H 2 O Lund University / Chalmers University of Technology
SCOC – Turbine design § LUAX-T modified for SCOC/OXUFUEL adaption ü Power density driven by SOT ü High SOT results is advanced cooling and 4 th generation materials ü Radiation issues? ü High effectiveness levels results in careful optimization of V 1 aspect ratio, loading, flow fcn and reaction (Aero 1) – modified m-star model required for cooling assessment. ü Penultimate cooling feed for rotor #1 – some SAS modeling required. § REFPROP Lund University / Chalmers University of Technology
Exhaust gas composition GT SCOC GRAZ AR 1. 3 % 4. 8 % 0% (kg/kg) O 2 11 % ~0 % CO 2 8. 1 % 88 % 23 % H 2 O 6. 4 % 6. 2 % 76 % N 2 73. 2 % 1% 1% Isentropic exp 1. 28 1. 17 1. 19 Gas constant 0. 29 0. 20 0. 40 Lund University / Chalmers University of Technology
EGT versus firing- and pressure level SCOC EGT PR 18, 5 COT 1500 ºC Lund University / Chalmers University of Technology 825 ºC GT EGT 640 ºC
Specific Gas Constant • A reduced specific gas constant corresponds to an increased density • For a specific component a increased density will increase the mass flow Lund University / Chalmers University of Technology
Oxy-fuel cycle Issues • Cooling with CO 2 / steam, radiation • High pressure ratios requires real gas calculations • How much gas dissolves in H 2 O in the exhaust gas condenser? • And so forth… Lund University / Chalmers University of Technology
Near future work • Establish a conceptual design tool for the turbomachinery components of the gas turbine topping cycle Lund University / Chalmers University of Technology
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