Direct Steam Generation

Transcription

1 International Workshop on: DESIGN OF SUBSYSTEMS FOR CONCENTRATED SOLAR POWER TECHNOLOGIES December Jodhpur (India) Direct Steam Generation Eduardo Zarza Moya Loreto Valenzuela Gutiérrez CIEMAT-Plataforma Solar de Almería

2 Direct Steam Generation Contents Introduction Advantages and disadvantages of the DSG process Current status of the DSG technology

3 Direct Steam Generation Contents Introduction Advantages and disadvantages of the DSG process Current status of the DSG technology

4 Solar Field Solar Field Steam Production with Linear Solar Concentrators T1 Steam Generator Steam T2 T1 T K P1 P1 >> P2 Expansion valve Saturated steam P2 Flash tank Process Water recirculation Process Feed pump Oil expansion tank Liquid water Feed water pump Liquid water a) using a Heat Transfer Fluid b) with Flashing

5 Solar Field Steam Production with Linear Solar Concentrators Steam Process Liquid water Feed water pump c) with Direct Steam Generation (DSG)

6 Direct Steam Generation Different sections in the rows of a DSG solar field Solar Radiation m L1 L2 L3 To Po Preheating Evaporation Sperheating

7 Solar Field Sperficial liquid velocity / (m/s) Steam Production with Linear Solar Concentrators Two-phase Flow Pattern Map for an horizontal pipe Steam 10 Bubbly Process 1 Intermittent 0,1 Liquid water 0,01 Estratified Annular Feed water pump c) with Direct Steam Generation (DSG) 0,001 0,01 0, Superficial steam velocity / (m/s) v l = m (1-x) / (A tubo l ) v g = (m x) / (Atubo g ) 100

8 Direct Steam Generation Two different Bubbly configurations A A Disperse-Bubbly Flow Section A-A A Foggy-Bubbly Flow Section A-A A Sección A-A

9 Direct Steam Generation Two different Bubbly configurations A A Plug-Intermittent Flow Section A-A A A Slow-Intermittent Flow Section A-A

10 Solar Field Sperficial liquid velocity / (m/s) Steam Production with Linear Solar Concentrators Two-phase Flow Pattern Map for an horizontal pipe Steam 10 Bubbly Process 1 Intermittent 0,1 Liquid water 0,01 Estratified Annular Feed water pump c) with Direct Steam Generation (DSG) 0,001 0,01 0, Superficial steam velocity / (m/s) v l = m (1-x) / (A tubo l ) v g = (m x) / (Atubo g ) 100

11 The Three Basic DSG Processes Feed pump Feed pump Solar Collectors Solar Collectors T u r b i n e Once-Through Boiler Lowest Costs Least complexity Best Performance Controllability? Flow Stability? Feed pump Injectors Solar Collectors Recirculation pump Separator T u r b i n e T u r b i n e Injection Process Better Controllability Flow stability equally good More complex Higher investment costs Recirculation Process Better Flow Stability Better Controllability More complex Higher investment costs Higher parasitics

12 Direct Steam Generation Contents Introduction Advantages and disadvantages of the DSG process Current status of the DSG technology

13 The Direct Steam Generation Process Comparison between the DSG and the HTF (oil) technologies Advantages of the DSG technology: Smaller environmental risks because oil is replaced by water Higher steam temperature (maximum steam temperature with oil = 385ºC)

14 Solar Field Typical HTF Solar Thermal Power Plant Thermal oils currently available have a thermal limits of 398ºC. There is a significant degradation above 400ºC 395 ºC Oil Superheated Steam (104bar/380ºC) Steam turbine Steam generator Condenser G G Deaerator 295 ºC Oil Reheater Oil expansion vessel Reheated steam 17bar/371ºC Scheme of a typical HTF plant with parabolic trough collectors Preheater

15 The Direct Steam Generation Process Comparison between the DSG and the HTF (oil) technologies Advantages of the DSG technology: Smaller environmental risks because oil is replaced by water Higher steam temperature (maximum steam temperature with oil = 385ºC) The overall plant configuration is more simple

16 Oil Circuit Direct Steam Generation versus HTF Technology Simplified Scheme of typical HFT and DSG solar thermal power plants Steam at104 bar/371 ºC Oil at 390 ºC Superheater Steam turbine Solar Field Condenser Steam Generator GDV Plant Steam at 104 bar/400 ºC Steam turbine Auxiliary heater Oil at 295 ºC Degasifier Reheater Oil expansion tank Auxiliary boiler HTF Plant Degasifier Condenser Liquid water at 114 bar / 120 ºC

17 The Direct Steam Generation Process Comparison between the DSG and the HTF (oil) technologies Advantages of the DSG technology: Smaller environmental risks because oil is replaced by water Higher steam temperature (maximum steam temperature with oil = 385ºC) The overall plant configuration is more simple Lower investment and O&M costs and higher plant efficiency

18 Lower LCOE of DSG versus HTF Plants A comparative study of HTF and DSG performed by DLR for a 100 MWe plant with a 9-hour TES has shown that: Scaling-up beyond a certain limit is not recommended for DSG plants (two 50 MWe plants together have a lower LEC than a single 100 MWe plant) The size and type of TES has a great impact on the LEC LEC changes by different DSG options compared to oil reference (TES = storage, OT = once-through, PCM = PCM storage).

19 The Direct Steam Generation Process Comparison between the DSG and the HTF (oil) technologies Advantages of the DSG technology: Smaller environmental risks because oil is replaced by water Higher steam temperature (maximum steam temperature with oil = 385ºC) The overall plant configuration is more simple Lower investment and O&M costs and higher plant efficiency Disadvantages of the DSG technology: Solar field control under solar radiation transients

20 The Direct Steam Generation Process Influence of solar radiation transients on feed-water flow distribution m Pi, Ti L1 Radiación solar L2 L3 To >Ti Po <Pi m Pi, Ti L1' Radiación solar L2' Radiación solar L3' T < To P > Po m Pi, Ti 1" L L 2" L3" T > To P < Po

21 The Direct Steam Generation Process Comparison between the DSG and the HTF (oil) technologies Advantages of the DSG technology: Smaller environmental risks because oil is replaced by water Higher steam temperature (maximum steam temperature with oil = 385ºC) The overall plant configuration is more simple Lower investment and O&M costs and higher plant efficiency Disadvantages of the DSG technology: Solar field control under solar radiation transients Instability of the two-phase flow inside the receiver tubes

22 Pressure drop, P The Direct Steam Generation Process Comparison between the DSG and the HTF (oil) technologies The Ledinegg instability Pressure drop versus mass flow in a row of PTC wit DSG at Constant intel temperature, outlet pressure and heat P Only Steam P P P ) E cte 0 m d Typical performance curve of a centrifugal pump Only liquid Mass flow, m

23 The Direct Steam Generation Process Comparison between the DSG and the HTF (oil) technologies Advantages of the DSG technology: Smaller environmental risks because oil is replaced by water Higher steam temperature (maximum steam temperature with oil = 385ºC) The overall plant configuration is more simple Lower investment and O&M costs and higher plant efficiency Disadvantages of the DSG technology: Solar field control under solar radiation transients Instability of the two-phase flow inside the receiver tubes Temperature gradients at the receiver pipes

24 Direct Steam Generation Uneven heat transfer at the steel absorber pipe h liquid Receiver pipe Parabolic trough concentrator h liquid

25 Direct Steam Generation Uneven heat transfer at the steel absorber pipe Temperature gradients in the steel absorber pipes

26 DSG with Linear Solar Concentrators DSG-related projects and studies since 1980 Theoretical studies by SERI (1982) The ATS (Advance Trough System) project by LUZ,( ) Experiments by ZSW at the HIPRESS test facility ( ) The GUDE project experiments at Erlangen ( ) The project PRODISS The project ARDISS ( ) R+D activities at UNAM (Mexico, up to date) The DISS project ( ) The INDITEP project ( ) The RealDISS project ( ) The DUkE project ( )

27 Direct Steam Generation Contents Introduction Advantages and disadvantages of the DSG process Current status of the DSG technology

28 DSG with Linear Solar Concentrators Curent Status Technical feasibility of the DSG process in linear solar concentrators has been proven. There are several DSG solar thermal power plants in operation

29 DSG with Linear Solar Concentrators Plant TSE-1, Thailand 5 MWe 34 bar, 340 C Technology by Solarlite

30 DSG with Linear Solar Concentrators Plant Puerto Errado-2, Spain 30 MWe 55 bar, 270 C Technology by Novatec&ABB

31 DSG with Linear Solar Concentrators Curent Status Technical feasibility of the DSG process in linear solar concentrators has been proven. There are several DSG solar thermal power plants in operation Accurate simulation&design tools for DSG solar fields have been developed Ball-joints for water/steam at 100bar/500ºC have been successfully tested. The best configuration for commercial DSG solar fields is a mixture of injection and recirculation. This configuration has been experimentally evaluated at PSA

32 DSG with Linear Solar Concentrators Scheme of a DSG row of collectors with Recirculation Preheating + Evaporation Steam superheating Feed water Water/steam separator Water recirculation ( 20%) Water inyection ( 7%)

33 DSG with Linear Solar Concentrators Curent Status Technical feasibility of the DSG process in linear solar concentrators has been proven. There are several DSG solar thermal power plants in operation Accurate simulation&design tools for DSG solar fields have been developed Ball-joints for water/steam at 100bar/500ºC have been successfully tested. The best configuration for commercial DSG solar fields is a mixture of injection and recirculation. This configuration has been experimentally evaluated at PSA Compact and cost-effective water/steam separators have been developed

34 Direct Steam Generation Water/steam separators for DSG Classic water/steam separator Compact water/steam separator

35 DSG with Linear Solar Concentrators Curent Status Technical feasibility of the DSG process in linear solar concentrators has been proven. There are several DSG solar thermal power plants in operation Accurate simulation&design tools for DSG solar fields have been developed Ball-joints for water/steam at 100bar/500ºC have been successfully tested. The best configuration for commercial DSG solar fields is a mixture of injection and recirculation. This configuration has been experimentally evaluated at PSA Compact and cost-effective water/steam separators have been developed A cost-effective thermal energy storage technology for DSG still to be developed Technical feasibility of the Once-Through option must be fully investigated

36 DSG with Linear Solar Concentrators Upgraded PSA DISS Facility for Once-Through mode View of the new DISS solar field for Once-Through at 500ºC /112bar

37 International Workshop on: DESIGN OF SUBSYSTEMS FOR CONCENTRATED SOLAR POWER TECHNOLOGIES December Jodhpur (India) Direct Steam Generation End of the Presentation Thank you very much for your attention!! Eduardo Zarza Moya Loreto Valenzuela Gutiérrez CIEMAT-Plataforma Solar de Almería