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Overview on Direct Steam Generation (DSG) and
Experience at the Plataforma Solar de Almería (PSA)
Parabolic Trough 2007 Workshop
Eduardo Zarza CIEMAT-Plataforma Solar de Almería, Apartado 22, Tabernas, E-04200 Almería, Spain Phone (+34) 950387931 Fax: (+34) 950365015 E-mail: [email protected]
March 8-9, 2007 (Denver)
Parabolic Trough 2007 Workshop
Overview on Direct Steam Generation &
PSA experience
) Advantages and disadvantages of the DSG process
) R+D activities related to DSG since 1980
) State-of-the-art of the DSG technology
March 8-9, 2007 (Denver)
The Direct Steam Generation Process
Comparison between the DSG technology and the HTF (oil) technology
Advantages of the DSG technology: & Smaller environmental risks because oil is replaced by water
& Higher steam temperature (maximum steam temperature with oil = 380ºC)
& The overall plant configuration is more simple
& Lower investment and O&M costs and higher plant efficiency
DSG-related potential problems:¾ Solar field control under solar radiation transients
¾ Instability of the two-phase flow inside the receiver tubes
¾ Temperature gradients at the receiver pipes
March 8-9, 2007 (Denver)
The Direct Steam Generation Process
DSG-related projects and studies since 1980
) Theoretical studies by SERI (1982)
) The ATS (Advance Trough System) project by LUZ,(1987-1991)
) Experiments by ZSW at the HIPRESS test facility (1992-1994)
) The GUDE project experiments at Erlangen (1992-1995)
) The project PRODISS
) The project ARDISS (1994-1997)
) R+D activities at UNAM (Mexico, 1976- up to date)
) The DISS project (1996-2001)
) The INDITEP project (2002-2005)
March 8-9, 2007 (Denver)
The Direct Steam Generation Process
State-of-the-art of the DSG technology
¾ Technical feasibility of the DSG process in horizontal PTs has been proven. More than 5500 hours of operation have been accumulated at the DISS test facility
¾ Accurate simulation&design tools for DSG solar fields have been developed
¾ Ball-joints for water/steam at 100bar/400ºC have been successfully tested. Testing of ball-joints for steam at 100bar/550ºC currently underway.
¾ The best configuration for commercial DSG solar fields is a mixture of injection and recirculation. This configuration has been experimentally evaluated at PSA
¾ It is easy to keep the temperature gradients in the receiver pipes within safe limits. Maximum stress obtained at PSA during operation has been 47% of the limit allowed
¾ Compact and cost-effective water/steam separators have been developed
¾ A Spanish Consortium is promoting a 3 MWe DSG power plants to be installed at PSA
¾ Several projects related to DSG are currently underway in Europe
¾ A suitable thermal energy storage technology for DSG still to be developed
March 8-9, 2007 (Denver)
End of Presentation
! Many thanks for your attention ¡
Overview on DSG
March 8-9, 2007 (Denver)
Direct Steam Generation
Typical Temperature profile in a HTF Solar thermal Power Plant
Steam generator
Re-heater Oil expansion tank
Auxiliary heater
Solar Field
Condenser
Oil at 390 ºC
Steam at 104 bar/371 ºC
Oil
circ
uit
Steam at 17 bar/371 ºC
G
Pre-heater
Evaporator
Sobrecalentador
Steam Turbine
Oil at 295 ºC
March 8-9, 2007 (Denver)
Direct Steam Generation
Simplified Scheme of typical HFT and DSG solar thermal power plants
Solar field
De-gasifier
DSG Plant Steam at 104 bar/400 ºC
Water at 114 bar / 200 ºC
.
Degasifier
Re-heater
Auxiliary heater
Condenser
Oil at 295 ºC
Oil at 390 ºC
Steam at 104 bar/371 ºC O
il ci
rcui
t
HTF Plant Auxiliary heater
Condenser
Steam turbine
Super-heater
Steam Generator
Oil expansion tank
Solar Field
Steam turbine
March 8-9, 2007 (Denver)
Direct Steam Generation
The Ledinegg instability P
ress
ure
drop
, ∆ P
Characteristic curve of a row of DSG Parabolic troughs (constant Tin, Pout and Ed)
P” • ∂(∆ P) )P < 0
• ∂ q Ed = cte m
P’100% steam • Characteristic curve of
a centrifugal pump
100% liquid
Mass feed flow
March 8-9, 2007 (Denver)
Direct Steam Generation
Different sections in the rows of a DSG solar field
Solar Radiation
2L 3L1L
T
P
•
mq Preheating Evaporation Sperheating
March 8-9, 2007 (Denver)
Direct Steam Generation
Uneven heat transfer at the steel absorber pipe
Parabolic trough concentrator
h
h
Receiver pipe
liquid
liquid
March 8-9, 2007 (Denver)
Direct Steam Generation
The DSG test facility implemented by LUZ for the ATS project
March 8-9, 2007 (Denver)
Direct Steam Generation
The HIPRESS test facility implemented by ZSW to study the DSG process
March 8-9, 2007 (Denver)
Direct Steam Generation
The DSG test facility implemented by SIEMENS for the GUDE project
March 8-9, 2007 (Denver)
Direct Steam Generation The DISS test facility implemented at the PSA
(south)
B.O.P. buildingRow of collectors
March 8-9, 2007 (Denver)
The DISS solar field
Aerial view of the DISS facility
Direct Steam Generation The DISS test facility implemented at the PSA
Water
0º to 8º
Recirculation pump
0º0º
l ll
1 2 3 4 5 6 7 8 9 10 11
Water/steam separator
Control valves
of evaporation
Water injection circuit
Feedwater
Feedwater pump
0º 0º
B A
TK-4
March 8-9, 2007 (Denver)
(40-108 bar) (30 - 100 bar)
Superheated steam
0º-2º-4º 0º-2º-4º 0º-2º-4º 0º-2º-4º 0º-2º-4º 0º-2º-4º 0º-2º-4º 0º-2º-4º
Power Block
Specia test co ector
Water pre-heating and beginning
valve
100 m 100 m
Water evaporation (Cont.) Steam superheating
Direct Steam Generation
Scheme proposed for commercial DSG solar fields
Feedwater
Water injectorV1
V2
Water recirculation
Water preheating (3 collectors) + boiling ( 5 collectors)
March 8-9, 2007 (Denver)
March 8-9, 2007 (Denver)
Steam Production at 100bar/350ºC (05/07/2001)
10:00 12:00 14:00 16:00 18:00 20:000
100
200
300
400
500
600
700
800
900
1000
Beam solar radiation
Inlet temperature
Outlet temperature
Sol
ar R
adia
tion
(W/m
2 )
Inle
t and
Out
let T
empe
ratu
res
(ºC
)
Local time (hh:mm)
0
10
20
30
40
50
60
70
80
90
100
110
Outlet steam pressure (bar)
Steam flow *100 (kg/s)
Ste
am p
ress
ure
(bar
)
Ste
am fl
ow *
100
(kg/
s)
Direct Steam Generation
Experimental data collected at the DISS facility
Direct Steam Generation
Water/steam separators for DSG
Classic water/steam separator Compact water/steam separator
March 8-9, 2007 (Denver)
Direct Steam Generation
Simplified Scheme of the DSG Solar Field to be installed at PSA 505 m
Power Bolck
•
125
m
17.5 m
17.5 m
• •
•
•
• lat
•
•
•
Recircu ion pump
Feed pump
Technical parameters
• Number of parallel rows: 4 • Number of collectors per row: 10 ET-100 collectors • Lenght of every collector: 98,5 m • Parabola width: 5.76 m • Total aperture area: 21934 m2 • Peak Thermal power (Ed=1kW/m2): 14,3 MW
March 8-9, 2007 (Denver)
Direct Steam Generation
Simplified Scheme of the Power block for the PSA DSG plant
GSolar field
Generator
HP LP
Aero-condenser
Hot air
Steam turbine
P = 65 bar T = 400ºC
P = 5,6 bar T = 172 ºC
P = 0,1 bar T = 46 ºC
P = 85 bar T = 126 ºC
Degasifier + Storage water tank
P = 2,44 bar T = 127 ºC
P = 80 bar T = 115 ºC
P = 70 bar T = 411ºC
March 8-9, 2007 (Denver)
Direct Steam Generation
Temperature gradients in the steel absorber pipes
March 8-9, 2007 (Denver)