Parabolic Trough

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Parabolic Trough

  1. 1. SOLAR THERMAL POWER! GEEN 4830 – ECEN 5007! 6. Parabolic trough technology! Manuel A. Silva Pérez ! silva@esi.us.es !
  2. 2. 1 GEEN 4830 – ECEN 5007 12/7/10
  3. 3. Solar Thermal Power Plant. Basic configuration Beam irradiance Concentrator Concentrated irradiance Electricity Receiver Thermal energy Thermal Storage Power Fossil fuel conversion Boiler Biomass system 2 GEEN 4830 – ECEN 5007 12/7/10
  4. 4. PT power plant configuration 3 GEEN 4830 – ECEN 5007 12/7/10
  5. 5. The collector 4 GEEN 4830 – ECEN 5007 12/7/10
  6. 6. Collector 5 GEEN 4830 – ECEN 5007 12/7/10
  7. 7. Main Concentrating Technologies
  8. 8. Types of collectors Process heat STP plant 7 GEEN 4830 – ECEN 5007 12/7/10
  9. 9. Main elements of the collector   Reflector (mirror)   Receiver tube   Structure   Tracking system   Connecting elements   Control system 8 GEEN 4830 – ECEN 5007 12/7/10
  10. 10. The reflector Thin glass mirror (0.8 mm) Thick glass mirror (3 -5 mm) 9 GEEN 4830 – ECEN 5007 12/7/10
  11. 11. Alternative reflector materials: Reflectech mirror film   Specular Reflectance 94% At 25 mrad, 660 nm   Solar-Weighted Hemispherical Reflectance 94%   Durability: approx. 10 yrs.   Thickness: 0.1 mm 10 GEEN 4830 – ECEN 5007 12/7/10
  12. 12. Alternative reflector materials: Alanod Miro-SUN 11 GEEN 4830 – ECEN 5007 12/7/10
  13. 13. Structure 12 GEEN 4830 – ECEN 5007 12/7/10
  14. 14. Structure  Bending  resistance   Torsional   resistance   Torque  Tube  design     LS3  Design     Torque  Box  Design     13 GEEN 4830 – ECEN 5007 12/7/10
  15. 15. The receiver tube Glass pin for evacuation of gases and steel tubes Vacuum between glass Glass – metal welding Selective coated steel tube 'Getter‘ for vacuum maintenance Expansion bellow Glass envelope 14 GEEN 4830 – ECEN 5007 12/7/10
  16. 16. Receiver tubes Schott PTR-70 Solel UVAC-2 and UVAC-3 15 GEEN 4830 – ECEN 5007 12/7/10
  17. 17. Heat transfer fluid   Thermal oils   Caloria (SEGS I and II, <300ºC)   Therminol VP-1 (<400 ºC)   Syltherm (Dow Chemical, >400ºC)   Water / Steam   >400 ºC   DISS Project   Molten salts   ENEA facility   Gases   PSA Research Facility 16 GEEN 4830 – ECEN 5007 12/7/10
  18. 18. Tracking mechanisms Electrical motor - gearbox Hydraulic 17 GEEN 4830 – ECEN 5007 12/7/10
  19. 19. Connecting collectors Flex hoses Rotating joints 18 GEEN 4830 – ECEN 5007 12/7/10
  20. 20. Control elements Shadowband sensor Controller 19 GEEN 4830 – ECEN 5007 12/7/10
  21. 21. Cleaning the mirrors 20 GEEN 4830 – ECEN 5007 12/7/10
  22. 22. Solar field configuration (I) 1 SCA 150 m 12 SCE 1 Drive Pylon 10 Middle Pylon 1 End Pylon 1 Shared Pylon (shared with next SCA) 150 m Shared Pylon SCE 150 m Middle Pylon Drive Pylon End Pylon Hot Oil Cold Oil 21 GEEN 4830 – ECEN 5007 12/7/10
  23. 23. Solar field configuration (2) Loop of 6 SCA’s 1248 m SEGS Power Block 80 MW Rankine Cycle Headers Cross Over Pipes 1379 m 22 GEEN 4830 – ECEN 5007 12/7/10
  24. 24. Solar field configuration (3)   Thermal losses   Thermal losses   unbalanced ΔP   Higher cost   Higher consumption   ΔP balanced   Lower consumption A) Direct return B) Inverse return h h h h   Shorter pipelines   Better access to collectors   unbalanced ΔP C) Central 23 GEEN 4830 – ECEN 5007 12/7/10
  25. 25. Solar field orientation Z Z Sol O S C Y N O C N Y Sol S X X S S E E a) E-W tracking b) N-S tracking 24 GEEN 4830 – ECEN 5007 12/7/10
  26. 26. Basic parameters Aperture, A Parabolic Acceptance angle, θ Angulo aceptancia θ de Reflector Rayorays Sun solar Absorber tube Aperture angle , φ Angulo aperturaφ de External receiver diameter , D Diámetro D C =.A /Π.D b) Concentration ratio, C b) Acceptance angle, θ 25 GEEN 4830 – ECEN 5007 12/7/10
  27. 27. Energy balance. Optical losses Beam irradiance interception factor, γ, Glass envelope (Transmissivity = τ) Selective-coated steel tube (Absortivity = α) Parabolic mirror (Reflectivity = ρ) ηo,peak = γ·τ·α·ρ 26 GEEN 4830 – ECEN 5007 12/7/10
  28. 28. Geometrical losses Sun L = concentrator length ϕ = incidence angle Sol F = focal length Side view Absorber tube Reflecting surface ϕ ϕ Shaded F area Plant view ED L Sun Af = W x ED = W x F x tan(ϕ) a) Shading losses b) Loss of effective collector length 27 GEEN 4830 – ECEN 5007 12/7/10
  29. 29. Loss of effective collector length ED W 28 GEEN 4830 – ECEN 5007 12/7/10
  30. 30. Thermal losses Absorber tube Qabs,cond/conv. Qamb,rad Qamb,conv Qabs,rad. Qv,abs. [W/m2abs ºC] Glass envelope UL)col = UL)abs / C 29 GEEN 4830 – ECEN 5007 12/7/10
  31. 31. Energy balance (solar to thermal) eff eff 30 GEEN 4830 – ECEN 5007 12/7/10
  32. 32. Typical operation curve (clear day, no thermal storage) Solar Efficiencies Measured at SEGS VI on July 1997 by KJC Operating 70 Company % 1200 60 Direct Normal % Radiation 1000 Direct Normal Radiatiom [W/m²] 50 % Thermal 800 - 40 Solar Efficiency % Field Efficiency 600 30 % [%] 20 400 % 10 Solar to Electric 200 % Efficiency 0 (gross) % 0 05:00 07:00 09:00 11:00 13:00 15:00 17:00 19:00 21:00 31 GEEN 4830 – ECEN 5007 12/7/10
  33. 33. Dispatchability of STP Plants   Integration of RES on the grid:   Dispatchability is a key factor.   STP Plants have the potential to be dispatchable by:   Including a Thermal Storage System (TES)   Hybridization with fossil or renewable fuels. 32 GEEN 4830 – ECEN 5007 12/7/10
  34. 34. Andasol-type plants (thermal storage and auxiliary boiler) 33 GEEN 4830 – ECEN 5007 12/7/10
  35. 35. Dispatchable STP Plant   Continuous and stable operation is guaranteed by TES and / or hybridization 50 40 MW 30 20 10 0 0 2 4 6 8 10 12 14 16 18 20 22 24 Hours 34 GEEN 4830 – ECEN 5007 12/7/10
  36. 36. TES 35 GEEN 4830 – ECEN 5007 12/7/10
  37. 37. Hybridization options 36 GEEN 4830 – ECEN 5007 12/7/10
  38. 38. SEGS 30 MW 37 GEEN 4830 – ECEN 5007 12/7/10
  39. 39. Costs   Difficult to evaluate   Confidentiality of contracts   Volatility of prices   Only 2 – 3 providers of key elements   O&M experience restricted to US (SEGS Plants) 38 GEEN 4830 – ECEN 5007 12/7/10
  40. 40. Costs CCP – Spain. 8h TES 39 GEEN 4830 – ECEN 5007 12/7/10
  41. 41. Costs – Spain. No TES 40 GEEN 4830 – ECEN 5007 12/7/10
  42. 42. O&M Costs – Spain (8h TES) 41 GEEN 4830 – ECEN 5007 12/7/10
  43. 43. PT Technology today, pros & cons.   Pros:   Mature technology;   Comercially proven, over 500 MW installed capacity;   Extensive operational record: 9 plants operating for 15+ years   Easier to finance   Cons:   Few manufacturers of key elements (recievers, mirrors…) -> limited competence   Limited maximum temperature -> limited efficiency   Costly, hazardous HTF   Limited TES options 42 GEEN 4830 – ECEN 5007 12/7/10
  44. 44. More…   http://www.nrel.gov/csp/troughnet/   Sargent & Lundy Assessment of CSP http://www.nrel.gov/csp/troughnet/pdfs/34440.pdf   Look for movies at youtube, e.g:   http://www.youtube.com/watch? v=ysDXwvNGHeM&feature=related   http://www.youtube.com/watch?v=3OLjooHY1VA   http://www.youtube.com/watch? v=mDWSW8BAM3U&feature=related   And more… 43 GEEN 4830 – ECEN 5007 12/7/10

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