Development of High Efficiency Hot Gas Turbo- Expander for Optimized CSP Supercritical CO 2 Power Block Operation

Transcription

1 Development of High Efficiency Hot Gas Turbo Expander for Optimized CSP Supercritical CO 2 Power Block Operation Chiranjeev Kalra, Doug Hofer, Edip Sevincer GE Global Research Jeff Moore, Klaus Brun Southwest Research Institute The 4th International Symposium Supercritical CO 2 Power Cycles September 910, 2014, Pittsburgh, Pennsylvania Title Only This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of the authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

2 Sunshot Program Overview Team: Southwest Research Institute, GE, KAPL, & Thar 3year, $8.5M program to develop & test an expander & recuperator for sco2 power generation from CSP. Schedule: Expander final design complete. System targets: 10MWe net module size 50% net thermal efficiency Expander targets: ~14MW shaft power >700C inlet temp >85% aero efficiency Multistage axial Not to scale 2

3 Prior Experience GE Global Research sco2 Systems Thermal Management GE Oil & Gas CO2 Compressors Dry Gas Seals Rotordynamics SWRI Test Loop Design Turbomachinery Design Advanced Analysis GE Power & Water USC steam materials High pressure casing Highpower density flowpath GE Aviation Manufacturing 3

4 Target Power Cycle 4

5 Turbomachine layout options Option Generator Compressor Turbine RPM High speed, Optimal High speed, expander only High speed, Geared 3600 rpm integrated 3600 rpm expander only A. IC B. PM A. IC B. PM A. IC B. PM C rpm A. Single stage centrifugal B. Multi stage pump None A. Single stage centrifugal B. Multi stage pump 3600 rpm Multi stage pump or compressor A. Radial B. Axial A. Radial B. Axial A. Radial B. Axial Multi stage Axial at 3600 rpm 3600 rpm None Multi stage Axial at 3600 rpm Optimized for compressor Optimized for expander Both expander and compressor run at optimal speed 3600 rpm 3600 rpm IC: Inductively coupled, PM: Permanent magnet, 3600 / 1800 rpm synchronous generator 5

6 Preliminary Layouts & Downselect: 6

7 Overall design & modeling philosophy 1. Correlations & methods originally developed for steam & air will be valid for conceptual design for CO2 in expander region because it is nearly an ideal gas. Ideal Gas: PV RT = 1 Calorically Perfect Gas: Cp=const T=700C T=700C P=240 bar P=85 bar T=550C 2. Need to include higher margins, particularly for nonideal gas regions (end seals) and fluidstructure interactions. 3. Validate results with CFD. 7

8 11 Aerodynamics Meanline 1D: Excel GE proprietary loss model Ideal gas CO 2 properties 2D/3D: TP3, CAFD GE proprietary design tools Ideal gas CO 2 properties CFD: TACOMA, ANSYS CFX Real gas tabular CO2 properties Used to validate meanline and 2D/3D design code predictions Good agreement for efficiency and flow function GDS: /users/ /hofer_grc/projects/doe_sunshot_sco2_expander/turbine_study_jan_2013/alternate_cycle_conditions/cafd/design6_731 STREAM SHEET jsl Imm carea throt Tmin/T ThrtArea stagger te thick LE Rad Imin Phys Tip Out E03 Pitch plt_angl plt_over tmax pctz betam1 1D delta1 Meanline betam2 ovt ugt flow wedge path Cross Root In 0.00 ******* Mult suctn surf 1% peak suctn M# ~1.2*mexit blade score= 54. % Move_an_ESP X OF TE= 0.0 Y OF TE= 0.0 TETHCK= 0.0 TEALPH= 0.0 CAREA = < knob > THROT = < knob > STAGGR = < knob > DELTA1 = < knob > RAD_LE = < knob > WEDGE = < knob > control points undo add/del points OVT = < knob > UGT = < knob > TMAX = 0.0 PCTZ = 0.0 ZOFF = 0.0 THOFF = 0.0 reset blade reset options reset throat zero crv US TE zero crv LS TE fit old Rel 0.400E+00 Isentropic 0.350E+00 Mach 0.300E E E D Airfoil shapes CFD Analysis CG Save best Load best Auto Conf Dat Optimize Table on/off: curv solver prefs thick adjust scale zoom blade Run Solver update display 18:46 08/01/13 mh bdf @NSK D WOGL PLOT 1 EGS LIB 6.1a 2009/03/06 (egsrep_wmf /01/29 on NSK D) BBP ver test /01/ ref1 ref2 old adj ref1 adj ref2 2 toggle mode CAREA THROT STAGGR DELTA RAD_LE WEDGE OVT UGT

9 Seals Labyrinth: Labflo, ANSYS CFX GE proprietary model validated for steam & air Applied CO2/air scaling factors CFD predicts significantly higher leakage Need conservatism in conceptual design phase (aero & rotordynamics) CFD analysis of interstage laby seal flow in CO2 Dry Gas Seals Commercially available at the required pressure but limited to low temperature and small diameter. GE developing tools to predict performance & lifing under the PREDICTS program DGS Face Pressure Distribution from CFD 9

10 Heat Transfer Challenges Need to cool shaft from turbine exit (>500C) to DGS & bearing max T (<200C) in short axial span sco2 has high convective heat transfer Empirical Correlations Shaft FEA model in ANSYS Gazley HTC correlation applied as boundary conditions Conjugate Heat Transfer Coupled CFD, heat transfer, and shaft FEA in ANSYS Result Agreement within 10% FOCUS program to develop & test advanced thermal management techniques to maintain gradients Shaft Temperature Contours Gazley HTC Boundary Condition Conjugate HT 10

11 CSR Rotordynamics 4 Challenges High gas density High operating speed Low critical speed (large L/D) Interstage laby seals Texas A&M code Real gas CO2 properties Balance piston seal Texas A&M code Perfect gas properties Region B Sunshot Region A Average Gas Density (lbm/ft3) Operating Speed CSR = 1st Undamped Critical Speed Result Due to uncertainty in seal damping, we used a factor of safety 10x API level II minimum (final logdec > 1.0) PREDICTS program developing midspan gas bearing Not to scale 11

12 Final Rotor Design 12

13 Summary sco 2 turbine design completed by the SunShot project team to meet the program objectives The design demonstrates key sco 2 turbine design features compact & low cost Design tools & prior experience in various products cover the operating range of a sco 2 turbine Integration of these diverse technologies into a single machine is challenging but required to achieve high efficiency High power density enables compact design and requires development of custom high performance turbomachinery components 13

14 Title Only