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SOLAR THERMAL POWER!GEEN 4830 – ECEN 5007!
Manuel A. Silva Pé[email protected]!
6. Parabolic trough technology!
12/7/10 1 GEEN 4830 – ECEN 5007
Solar Thermal Power Plant. Basic configuration
Beam irradiance
Concentrator
Receiver
Thermal Storage
Concentrated irradiance Electricity
Power conversion system
Thermal energy
Boiler Fossil fuel Biomass
12/7/10 2 GEEN 4830 – ECEN 5007
PT power plant configuration
12/7/10 3 GEEN 4830 – ECEN 5007
The collector
12/7/10 4 GEEN 4830 – ECEN 5007
Collector
12/7/10 5 GEEN 4830 – ECEN 5007
Main Concentrating Technologies
Central Receiver / Heliostats
Parabolic troughs
Parabolic dishes
Linear Fresnel Reflectors
Types of collectors
Process heat STP plant
12/7/10 7 GEEN 4830 – ECEN 5007
Main elements of the collector
Reflector (mirror) Receiver tube Structure Tracking system Connecting elements Control system
12/7/10 8 GEEN 4830 – ECEN 5007
The reflector
Thin glass mirror (0.8 mm) Thick glass mirror (3 -5 mm)
12/7/10 9 GEEN 4830 – ECEN 5007
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
12/7/10 GEEN 4830 – ECEN 5007 10
Alternative reflector materials: Alanod Miro-SUN
12/7/10 GEEN 4830 – ECEN 5007 11
Structure
12/7/10 12 GEEN 4830 – ECEN 5007
Structure
Bending resistance Torsional resistance
Torque Tube design
LS3 Design
Torque Box Design
12/7/10 13 GEEN 4830 – ECEN 5007
The receiver tube
Selective coated steel tube Glass envelope
'Getter‘ for vacuum maintenance Expansion bellow
Glass pin for evacuation of gases Vacuum between glass and steel tubes Glass – metal welding
12/7/10 14 GEEN 4830 – ECEN 5007
Receiver tubes
Schott PTR-70 Solel UVAC-2 and UVAC-3
12/7/10 15 GEEN 4830 – ECEN 5007
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
12/7/10 16 GEEN 4830 – ECEN 5007
Tracking mechanisms
Electrical motor - gearbox Hydraulic
12/7/10 17 GEEN 4830 – ECEN 5007
Connecting collectors
Flex hoses Rotating joints
12/7/10 18 GEEN 4830 – ECEN 5007
Control elements
Shadowband sensor
Controller
12/7/10 19 GEEN 4830 – ECEN 5007
Cleaning the mirrors
12/7/10 20 GEEN 4830 – ECEN 5007
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)
Cold Oil
Hot Oil
End Pylon
Drive Pylon Middle Pylon
Shared Pylon SCE
150 m
150 m
12/7/10 21 GEEN 4830 – ECEN 5007
Solar field configuration (2)
Cross Over Pipes
1379 m
1248
m
Loop of 6 SCA’s
Headers SEGS Power Block 80 MW Rankine Cycle
12/7/10 22 GEEN 4830 – ECEN 5007
A) Direct return B) Inverse return
C) Central
h
h
h
h
Thermal losses Higher cost ΔP balanced Lower consumption
Thermal losses unbalanced ΔP Higher consumption
Shorter pipelines Better access to collectors unbalanced ΔP
Solar field configuration (3)
12/7/10 23 GEEN 4830 – ECEN 5007
X
Y N
S E
O
Z
S C
Sol
X
Y N
S E
O
Z
S
C
Sol
b) N-S tracking a) E-W tracking
Solar field orientation
12/7/10 24 GEEN 4830 – ECEN 5007
Diámetro , D
Rayo solar
Angulo de apertura , φ
Angulo de aceptancia , θ Reflector Parabolic
External receiver diameter D
Sun rays
Aperture angle φ
Acceptance angle , θ
b) Acceptance angle, θ b) Concentration ratio, C
Aperture, A
Absorber tube
C =.A /Π.D
Basic parameters
12/7/10 25 GEEN 4830 – ECEN 5007
Beam irradiance interception factor, γ,
Selective-coated steel tube (Absortivity = α)
Glass envelope (Transmissivity = τ)
Parabolic mirror (Reflectivity = ρ)
ηo,peak = γ·τ·α·ρ
Energy balance. Optical losses
12/7/10 26 GEEN 4830 – ECEN 5007
Sun
Sun
Side view
Plant view Shaded area
ϕ Reflecting surface
Absorber tube
L = concentrator length ϕ = incidence angle
ϕ
F = focal length Sol
F
ED
L
b) Loss of effective collector length a) Shading losses
Af = W x ED = W x F x tan(ϕ)
Geometrical losses
12/7/10 27 GEEN 4830 – ECEN 5007
Loss of effective collector length
W
ED
12/7/10 28 GEEN 4830 – ECEN 5007
[W/m2abs ºC]
UL)col = UL)abs / C
Qv,abs.
Qabs,rad.
Qabs,cond/conv. Qamb,rad
Qamb,conv
Glass envelope
Absorber tube
Thermal losses
12/7/10 29 GEEN 4830 – ECEN 5007
eff eff
Energy balance (solar to thermal)
12/7/10 30 GEEN 4830 – ECEN 5007
0%
10%
20%
30%
40%
50%
60%
70%
Effic
ienc
y [%
]
0
200
400
600
800
1000
1200
Dire
ct N
orm
al R
adia
tiom
[W/m²]
05:00 07:00 09:00 11:00 13:00 15:00 17:00 19:00 21:00
Solar to Electric Efficiency (gross)
Direct Normal Radiation
Thermal Solar Field Efficiency
-
Solar Efficiencies Measured at SEGS VI on July 1997 by KJC Operating Company
Typical operation curve (clear day, no thermal storage)
12/7/10 31 GEEN 4830 – ECEN 5007
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.
12/7/10 32 GEEN 4830 – ECEN 5007
Andasol-type plants (thermal storage and auxiliary boiler)
12/7/10 33 GEEN 4830 – ECEN 5007
Dispatchable STP Plant
Continuous and stable operation is guaranteed by TES and / or hybridization
MW
0 2 4 6 8 10 12 14 16 18 20 22 24
Hours
50
40
30
20
10
0
50
40
30
20
10
0
50
40
30
20
10
0
12/7/10 34 GEEN 4830 – ECEN 5007
TES
12/7/10 35 GEEN 4830 – ECEN 5007
Hybridization options
12/7/10 36 GEEN 4830 – ECEN 5007
SEGS 30 MW
12/7/10 37 GEEN 4830 – ECEN 5007
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)
12/7/10 38 GEEN 4830 – ECEN 5007
Costs CCP – Spain. 8h TES
12/7/10 39 GEEN 4830 – ECEN 5007
Costs – Spain. No TES
12/7/10 40 GEEN 4830 – ECEN 5007
O&M Costs – Spain (8h TES)
12/7/10 41 GEEN 4830 – ECEN 5007
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
12/7/10 42 GEEN 4830 – ECEN 5007
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…
12/7/10 43 GEEN 4830 – ECEN 5007