SFERA-2 Summer School School... · The ATS (Advance Trough System) project by LUZ,(1987-1991)...

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

mailto:[email protected]

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


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


Liquid water

Feed water pump

c) with Direct Steam

Generation (DSG)

Steam

Sol

ar F

ield

Process



Different sections in the rows of a DSG solar field

Solar Radiation

To

Po

Direct Steam Generation

•

m

Preheating Sperheating Evaporation

L1 L2 L3


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


c) with Direct Steam Generation (DSG)

Feed water pump

Steam

Liquid water

Sol

ar F

ield

Process


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’



Slow-Intermittent Flow

Plug-Intermittent Flow

Section A-A’

Section A-A’

A

A’

A

A’

Two dif ferent “Intermittent” confi gu rations



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



Contents

Introduction






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)


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






The overall plant configuration is more simple



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







Lower investment and O&M costs and higher plant efficiency



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







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



Influence of solar radiation transients on feed-water flow distribution


'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








Solar field control under solar radiation transients is more complex

Instability of the two-phase flow inside the receiver tubes




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”

• •








Solar field control under solar radiation transients

Instability of the two-phase flow inside the receiver tubes

Temperature gradients at the receiver pipes



Uneven heat transfer at the steel absorber pipe

Receiver pipe

Parabolic trough concentrator

Direct Steam Generation in Parabolic Troughs

hliquid

hliquid


Temperature gradients in the steel absorber pipes

Uneven heat transfer at the steel absorber pipe

Direct Steam Generation


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


Contents

Introduction






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


Moody´s diagram (friction factor)



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

)4/()4/(

)1( 22

lg

gl

ff

xxA⋅

⋅⋅+−=ρρ

522

216

il

ml dg

qFr⋅⋅⋅

⋅=

ρπ

li

ml d

qWeρσπ ⋅⋅⋅

⋅= 32

216

0334.0047.089.022.08.024.0685.0 )1()()()1(43.3 −− ⋅⋅−⋅⋅⋅−⋅⋅+= lll

g

l

g

g

l WeFrxxARµµ

µµ

ρρ

µg ρg



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



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


( ) ζρ

π ⋅⋅

⋅li

ml

dq4

228

)/2(2,21

idRB

+⋅+=

ζ

2

2

)1())1(()1/(1

xxxxB

F gl

−

+−⋅⋅⋅−+=

ρρ


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



Contents

Introduction






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


Plant TSE-1, Thailand 5 MWe 34 bar, 340 °C Technology by Solarlite



Plant Puerto Errado-2, Spain 30 MWe 55 bar, 270 °C Technology by Novatec&ABB



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



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)

Tem

pera

ture

/ (

ºC)

6,6 6,4

6,2

6,0

5,8

5,6

5,4

5,2

5,0

7,0

6,8 Pressure (experimental data) Pressure (simulation results)

Pre

ssur

e / (

MP

a)

0 1 2 3 4 5 6 Collector #

7 8 9 10 11

Date 05/04/2001

250

275

300

325

350

375

Fluid temperature(experimental data) Fluid temperature (simulated data)

Tem

pera

ture

/ (º

C)

11,0

10,8

10,6

10,4

10,2

10,0

9,8

9,6

9,4

9,2

9,0

Pressure (experimental data) Pressure (simulated data)

Pres

sure

/ (M

Pa)



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



Scheme of a DSG row of collectors with Recirculation

Water recirculation

(≈ 20%)

Water inyection (≈ 7%)

Feed water

Water/steam separator

Preheating + Evaporation Steam superheating



Compact and cost-effective water/steam separators have been developed







Water/steam separators for DSG

Classic water/steam separator Compact water/steam separator




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






Upgraded PSA DISS Facility for Once-Through mode (The DUKE project)



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



Circumferential heat conduction in the DSG receiver tubes

Receiver tube

Receiver tube cross section


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

E-mail: [email protected]

SFERA-2 Summer School (Almería 9-10 June, 2016)

HEAT TRANSFER FLUIDS FOR CONCENTRATING SOLAR THERMAL SYSTEMS
















SFERA-2 Summer School School... · The ATS (Advance Trough System) project by LUZ,(1987-1991)...

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Transcript of SFERA-2 Summer School School... · The ATS (Advance Trough System) project by LUZ,(1987-1991)...