SFERA-2 Summer School (Almería 9-10 June, 2016) HEAT TRANSFER FLUIDS FOR CONCENTRATING SOLAR THERMAL SYSTEMS Eduardo Zarza Moya CIEMAT-Plataforma Solar de Almería E-mail: [email protected]Direct Steam Generation in Linear Receivers: overview and key issues
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SFERA-2 Summer School School... · The ATS (Advance Trough System) project by LUZ,(1987-1991) Experiments by ZSW at the HIPRESS test facility (1992-1994) The GUDE project experiments
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SFERA-2 Summer School (Almería 9-10 June, 2016)
HEAT TRANSFER FLUIDS FOR CONCENTRATING SOLAR THERMAL SYSTEMS
Eduardo Zarza Moya CIEMAT-Plataforma Solar de Almería
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Contents
Introduction
Advantages and disadvantages of the DSG process
Thermo-hydraulic issues
Current status of the DSG technology
Direct Steam Generation in Linear Receivers
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Contents
Introduction
Advantages and disadvantages of the DSG process
Thermo-hydraulic issues
Current status of the DSG technology
Direct Steam Generation in Linear Receivers
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Steam Production with Linear Solar Concentrators
Steam production with linear solar concentrators
a) using a Heat Transfer Fluid
Sol
ar F
ield
Steam Generator
Feed pump
Oil expansion tank
Process
T1 T2
T1 ≈ T2 + 10 K
Steam
Liquid water
b) Flashing
Sol
ar F
ield
Proceso Industrial
Feedwater pump
Expansion valve
P1 P2 P1 >> P2
Process
Flash Tank
Water recirculation
P1 P2 P1 >> P2
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Liquid water
Feed water pump
c) with Direct Steam
Generation (DSG)
Steam
Sol
ar F
ield
Process
Steam Production with Linear Solar Concentrators
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Different sections in the rows of a DSG solar field
Solar Radiation
To
Po
Direct Steam Generation
•
m
Preheating Sperheating Evaporation
L1 L2 L3
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
0,1 1 10 Superficial steam velocity / (m/s)
vl = m · (1-x) / (Atube · ρl)
vg = (m · x) / (Atube · ρg)
Two-phase Flow Pattern Map for an horizontal pipe
0,01
1
0,1
0,001
0,01
10
100 Supe
rfic
ial l
iqui
d ve
loci
ty /
(m/s
)
Annular
Intermittent
Stratified
Bubbly
Steam Production with Linear Solar Concentrators
c) with Direct Steam Generation (DSG)
Feed water pump
Steam
Liquid water
Sol
ar F
ield
Process
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Two dif ferent “Bub b ly” confi gu rations
Disperse-Bubbly Flow
A
A’
SSeecccciióónn AA--A’A’
A
A’
Foggy-Bubbly Flow Section A-A’
Section A-A’
Direct Steam Generation in Linear Receivers
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Slow-Intermittent Flow
Plug-Intermittent Flow
Section A-A’
Section A-A’
A
A’
A
A’
Two dif ferent “Intermittent” confi gu rations
Direct Steam Generation in Linear Receivers
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
0,1 1 10 Superficial steam velocity / (m/s)
vl = m · (1-x) / (Atubo · ρl)
vg = (m · x) / (Atubo · ρg)
Two-phase Flow Pattern Map for an horizontal pipe
0,01
1
0,1
0,001
0,01
10
100 Supe
rfic
ial l
iqui
d ve
loci
ty /
(m/s
)
Annular
Intermittent
Estratified
Bubbly
c) with Direct Steam Generation (DSG)
Feed water pump
Steam
Liquid water
Sol
ar F
ield
Process
Direct Steam Generation in Linear Receivers
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Contents
Introduction
Advantages and disadvantages of the DSG process
Thermo-hydraulic issues
Current status of the DSG technology
Direct Steam Generation in Linear Receivers
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Comparison between the DSG and the HTF (oil) technologies
Advantages of the DSG technology:
Smaller environmental risks because oil is replaced by water
The Direct Steam Generation Process
Higher steam temperature (maximum steam temperature with oil = 385ºC)
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Oil expansion vessel Scheme of a typical HTF plant with parabolic trough collectors
Thermal oils currently available have a thermal limits of 398ºC. There is a significant degradation above 400ºC
Typical HTF Solar Thermal Power Plant
295 ºC Oil
395 ºC Oil
Steam generator
Deaerator
Reheater
Steam turbine
GG Condenser
Sola
r Fie
ld
Preheater
Superheated Steam (104bar/380ºC)
Reheated steam 17bar/371ºC
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
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
The Direct Steam Generation Process
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Simplified Scheme of typical HTF and DSG solar thermal power plants
Direct Steam Generation versus HTF Technology
Auxiliary boiler
Degasifier
Liquid water at 114 bar / 120 ºC
Condenser
Steam turbine
GDV Plant Steam at 104 bar/400 ºC
Superheater
Condenser Steam Generator
Degasifier
Reheater Oil expansion tank
Auxiliary heater
Solar Field
Steam turbine
Oil at 295 ºC
Oil at 390 ºC
Steam at104 bar/371 ºC O
il C
ircui
t
HTF Plant
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
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
The Direct Steam Generation Process
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Lower LCOE of DSG versus HTF Plants
LEC changes by different DSG options compared to oil reference (TES = storage, OT = once-through,
PCM = PCM storage).
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
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
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 is more complex
The Direct Steam Generation Process
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Influence of solar radiation transients on feed-water flow distribution
The Direct Steam Generation Process
'1L
Radiación solar
2L 3L1Lm T
Radiación solar
m
P
T’ < T
P’ > P '3L
Radiación solar
"1L "2L "3Lm
T > T
P” < P
'2L
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
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 is more complex
Instability of the two-phase flow inside the receiver tubes
The Direct Steam Generation Process
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
The Direct Steam Generation Process
Mass flow, m
Pre
ssur
e dr
op, ∆
P
( ) 0) <∂∆∂
=cteEdmP
Comparison between the DSG and the HTF (oil) technologies The Ledinegg instability Pressure drop versus mass flow in a row of linear collectors with DSG at constant intel temperature, outlet pressure and heat gain
Steam only
Liquid only
Characteristic curve of a centrifugal pump
P
P’
• P”
• •
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
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
The Direct Steam Generation Process
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Uneven heat transfer at the steel absorber pipe
Receiver pipe
Parabolic trough concentrator
Direct Steam Generation in Parabolic Troughs
hliquid
hliquid
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Temperature gradients in the steel absorber pipes
Uneven heat transfer at the steel absorber pipe
Direct Steam Generation
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
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)
The RealDISS project (2009-2011)
The DUKE project (2012-2015)
DSG with Linear Solar Concentrators
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Contents
Introduction
Advantages and disadvantages of the DSG process
Thermo-hydraulic issues
Current status of the DSG technology
Direct Steam Generation in Linear Receivers
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Assessment of pressure drop, ∆P, in pipes with two-phase flow Experimental results gathered at the PSA DISS test facility within the pressure range 3-10 MPa have shown that correlation proposed by Friedel in 1975¹ provides pressure drop values with an acceptable accuracy.
The basic concept of Friedel´s model is the application of a 2-phase-multiplier, R, to the single phase pressure drop that would occur if the total mass flow would pass as liquid through the pipe, ∆Pl : ∆P2F = R · ∆Pl
DSG Thermo-hydraulic Issues
(fl = Moody´s friction factor assuming that total mass flow is liquid) ∆Pl =
ρ l x (d/2) 2 mtotal v = l
Rel = vl x ρ ·l x d /µl
= total water mass flow (liquid+steam) = inner diameter of pipe = dynamic viscosity of liquid phase = density of liquid phase = fluid velocity if total mass flow is in liquid phase
mtotal
d
l
ρ l vl
µ
¹ Friedel , L. “Modellgesetz für den Reibungsdruckverlust in der Zweiphasenströmug”. VDI-Forschungsheft 572, 1975
dLv
fll
l ××× 2
2ρ
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Moody´s diagram (friction factor)
DSG Thermo-hydraulic Issues
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Assessment of pressure drop, ∆P, in pipes with two-phase flow Once the single phase pressure drop that would occur if the total mass flow would pass as liquid through the pipe has been calculated, the 2-phase-multiplier, R, has to be calculated also. For this, the auxiliary parameter A, and the Froude, Frl, and Weber, Wel, numbers must be previously calculated:
x = steam quality σ = surface tension between water and steam
= dynamic viscosity of steam phase = density of steam phase
g = acceleration by gravity = 9.81 m/s2
= Moody´s friction factor assuming that total mass flow is steam f g
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Assessment of pressure drop, ∆P, in two-phase flow pipes Practical consideration concerning Friedel´s correlation: Since for high steam quality values, Friedel´s correlation can deliver pressure drop values that are higher than the pressure drop when all the mass flow is in steam phase, ∆Pg , a limit must be imposed to the values obtained with Friedel´s correlation for high steam quality values:
≤ ∆Pg ∆P2F
DSG Thermo-hydraulic Issues
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Assessment of pressure drop, ∆P, in bends with two-phase flow Experimental results gathered at the PSA DISS test facility within the pressure range 3-10 MPa have shown that correlation proposed by Chisholm in 1980¹ provides pressure drop values with an acceptable accuracy.
The basic concept of Chisholm´s model is the application of a 2-phase-multiplier, R, to the single phase pressure drop that would occur if only the liquid mass flow
¹ Chisholm, D. “Two-phase flow in bends”, International Journal of Multiphase Flow, Vol. 6, 1980, pp.363-367
would pass through the pipe, ∆Pl,only : = F · ∆Pl,only ∆P2F
ζ = the pressure loss coefficient usually known as a function from the ratio between radius, R, of the bend and its inner diameter, di. For standard 2,5” 90º elbows with R/d =3
∆Pl,only =
ζ = 0.17
DSG Thermo-hydraulic Issues
( ) ζρ
π ⋅⋅
⋅li
ml
dq4
228
)/2(2,21
idRB
+⋅+=
ζ
2
2
)1())1(()1/(1
xxxxB
F gl
−
+−⋅⋅⋅−+=
ρρ
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Assessment of pressure drop, ∆P, in bends with two-phase flow
Practical consideration concerning Chisholm´s correlation: For high steam quality values (X>0.85), Chisholm´s correlation can deliver pressure drop values that are too low. To overcome this problem for x >0.85 it is recommended to use the pressure drop value ∆p ' according to the following correlation:
·(1− x) + ∆pg· x ∆p = ∆p 2 F '
Where:
∆p2 F
∆pg = = Pressure drop calculated according to Chislhom´s correlation
Pressure drop assuming that the total mass flow is in steam phase
DSG Thermo-hydraulic Issues
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Contents
Introduction
Advantages and disadvantages of the DSG process
Thermo-hydraulic issues
Current status of the DSG technology
Direct Steam Generation in Linear Receivers
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Curent Status
Current Status of DSG with Linear Collectors
Technical feasibility of the DSG process in linear solar concentrators has been proven. There are several DSG solar thermal power plants in operation
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Plant TSE-1, Thailand 5 MWe 34 bar, 340 °C Technology by Solarlite
Current Status of DSG with Linear Collectors
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Plant Puerto Errado-2, Spain 30 MWe 55 bar, 270 °C Technology by Novatec&ABB
Current Status of DSG with Linear Collectors
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
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
Current Status of DSG with Linear Collectors
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Comparison between experimental and simulation results for the PSA DISS test facility
Test day at 10 MPa.
0 1 2 3 4 5 6 7 Collector #
8 9 10 11
Date: 17/07/2001
225
250
275
300
325
350
375
Temperature (experimental data) Temperature (simulation results)
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
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
Current Status of DSG with Linear Collectors 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
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Scheme of a DSG row of collectors with Recirculation
Water recirculation
(≈ 20%)
Water inyection (≈ 7%)
Feed water
Water/steam separator
Preheating + Evaporation Steam superheating
Current Status of DSG with Linear Collectors
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Compact and cost-effective water/steam separators have been developed
Current Status of DSG with Linear Collectors
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
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
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Current Status of DSG with Linear Collectors
A cost-effective thermal energy storage technology for DSG still to be developed
Technical feasibility of the Once-Through option must be fully investigated
Compact and cost-effective water/steam separators 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
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
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Upgraded PSA DISS Facility for Once-Through mode (The DUKE project)
Current Status of DSG with Linear Collectors
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Curent Status (II) Liquid water stratification is not so dangerous as initially assumed, because
the maximum temperature difference in a cross section of the receiver tubes is always <70ºC within the usual range of operational parameters
Current Status of DSG with Linear Collectors
7th SFERA-II Summer School CIEMAT-PSA. Almería , June 9th-10th, 2016
Circumferential heat conduction in the DSG receiver tubes
Receiver tube
Receiver tube cross section
Current Status of DSG with Linear Collectors
R1
R2 T • T2 •T1
Parabolic trough concentrator
Direct Steam Generation in Linear Receivers: overview and key issues
End of the Presentation
Thank you very much for your attention !!
Eduardo Zarza Moya CIEMAT-Plataforma Solar de Almería