Staged combustion concept for increased operational flexibility of gas turbines

Transcription

1 Staged combustion concept for increased operational flexibility of gas turbines Dieter Winkler, Antony Marrella, Janine Bochsler, Geoffrey Engelbrecht, Timothy Griffin, Peter Stuber Tagung Verbrennungsforschung, 9. Sept. 2015, ETH Zürich Project Partners: Bundesamt für Energie BFE

2 Content Motivation for staged combustion concept 2 nd Stage: improved design CFD simulation Combustion test results (atmospheric test rig) Conclusions 2

3 Motivation: Operational Flexibility Load Flexibility Renewable energy sources (solar, wind) lead to unpredictable fluctuations in the grid to be balanced Fuel Flexibility Different Natural Gas (C 2+ ) Renewable fuel sources (biogas, syngas, hydrogen etc.) SCCER relevant Goals Rapid power turndown 1:5 (CO < 20 ppm) Operation up to 20 % C 2+ or 20 % H 2 content in fuel Co-firing with biogas (50 % CO 2 ) and gasified biomass (Syngas) Pressure drop < 5 % Adiabatic flame temperature up to 1800 K (NO X < 10 ppm) 3

4 00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00 00:00 Power requirement for GT Operation concept Example of operation a gas turbine plant for fluctuating network requirement during one day 100% 75% Network requirement for GT only 50% GT: 2nd stage 25% GT: 1st stage Time

5 Staged Conventional Operation Concept Piloted Combustion UHC CO NO x Tad Lean Premixed Combustion GT Load (electric) Piloted Combustion NO x first stage Tad CO global Tad Lean Premixed Combustion UHC GT Load (electric)

6 Development of GT combustion system Design specification concept design detailed design engine integration 1D Tools stoichiometry kinetics jet penetration pressure drops CFD cold flow details of fuel injection complete model, with combustion and heat transfer Tests water channel cold flow, air atmospheric combustion pressure combustion engine tests scope of present project

7 COBRA test rig atmospheric, 150 kw Second Stage First Stage 7

8 Staged Combustor Configuration 1 Second Stage Injection Design: «Annular Injection» fuel 2 fuel 1 T.ad T.ad_ pos. gas probe

9 Staged Combustor Configurations Configuration 1: annular Stage1 Stage2 Configuration 2: radial jets ( jets in cross flow )

10 Number of jets Holdeman Correlation For a straight cylindrical duct: optimal number of jets: n 2J J jet cross 2 v jet 15 2 v cross Holdeman et al, ASME-96-GT-482, 1996

11 Configuration 2 Second Stage Injector CAD part SLM part radial injection for better mixing with first stage hot gas 7 jets, 20 with 100 m/s 50 mbar pressure drop J = 15 11

12 Configuration 2 Second Stage Injector CFD 12

13 Configuration 2 7 Jets, Angle Variation Mass fraction Second Stage 13

14 Spatial unmixedness of fuel mass fraction Comparison of Configurations U spatial = (Z 2 ) A (Z ) A 2 (Z ) A (1 Z A) 14

15 Definitions m air _2 Air m m air _1 air _ total Fuel ST 1 ST 2 air split m m air _2 air _ total Tad 1 T ad 2 T ad 15

16 config2 config1 Test Results: stage2 flame pictures Test conditions: burner pos.: 250 mm T ad1 : 1750 K vel 1 : 60 m/s air split: 50 % COBRA, atmospheric test rig flame temp. 1650K 1750K 1850K 16

17 config2 config1 Test Results: stage2 flame pictures Test conditions: burner pos.: 250 mm T ad1 : 1750 K vel 1 : 60 m/s air split: 50 % COBRA, atmospheric test rig OH Chemiluminescence flame temp. 1650K 1750K 1850K 17

18 Test Results: Variation of Geometry CO emissions second stage off 18

19 Test Results: Variation of Geometry NOx emissions 19

20 Test Results: Variation of air split CO emissions 20

21 Test Results: Variation of T ad,1 Configuration 2 CO NOx 21

22 2 [ppm] 2 [ppm] Test Results: Turn Down Ratio NOx first stage only Configuration Thermal Power config 2 burner pos.: 250mm s T.vBr_1: 450 C T.vBr: 450 C lance pos.: 390mm 50% air split vel_ CO first stage only NOx CO: 40m/s, first stage only CO: 40m/s CO: 50m/s CO: 60m/s NOx: 40m/s, first stage only NOx: 40m/s NOx: 50m/s 20 1 NOx: 60m/s 10 CO thermal power [kw] 23

23 Fuel Flexibility Objective: Combustion system shall be capable of burning fuels with wide range of composition and reactivity Tested fuel compositions: Natural gas + Propane (C 3 H 8 ) Natural gas + Hydrogen (H 2 ) Syngas (CH 4 + CO + H 2 ) Biogas (50% CH % CO 2 ) -> low reactivity Wood gas (50% H % CO) -> high reactivity 24

24 CO [ppm] NOx [ppm] Test Results: Fuel Variation (Propane) Propane addition fuel power fraction burner pos.: 250mm T.ad_1: 1750K T.vBr_1: 450 C T.vBr: 450 C T.ad: 1750K lance pos.: 390mm vel_1: 60m/s 50% air split 25 CO config CO: C3H8_fuel2 CO: C3H8_fuel2, config1 NOx: C3H8_fuel2 NOx: C3H8_fuel2, config1 10 NOx config propane power fraction [ ] 25

25 CO [ppm] NOx [ppm] Test Results: Fuel Variation (Hydrogen) Hydrogen addition config fuel power fraction burner pos.: 250mm T.ad_1: 1750K T.vBr_1: 450 C T.vBr: 450 C T.ad: 1750K lance pos.: 390mm vel_1: 60m/s 50% air split 25 CO CO: H2_fuel2 CO: H2_fuel2, config1 NOx: H2_fuel NOx config NOx: H2_fuel2, config hydrogen power fraction [ ] 26

26 Influence of Fuel Type at Load Reduction Configuration2 27

27 Conclusions Staging concept provides high load and fuel flexibility. System performance has been significantly improved by optimization of 2 nd stage injection geometry. Jet in cross flow type mixing of 2 nd stage enables lower CO, higher turn-down ratio and lower NOx in co-firing mode with bio-fuels. Further configurations will be investigated. 28

28 29