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Ammonia bottoming cycle
projectFranck David –EDF R&D
July 8th and 9 th 2008 EPRI Workshop on Advanced Cooling Technology – July 8th and 9 th 20082
Nuclear power plants : 58 plants + EPR Flamanville
EDF nuclear power plants
19 nuclear sites58 plants
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Water needs and consumption
EDF’s water needs
Water needs : 25 g / Kwh
River only
Needs : 15 g/kwh
Evap : 0,45 g/kwh
domestic Industry Agriculture electricitySurface water
underground water
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Review of EDF’s CYBIAM Project (Cycle Binaire Ammoniac)
Binary cycle overview
Experiments with the CYBIAM pilot
Economical studies
Modelling the cycle
Discussion…
*Based on review of documents available at EDF
Binary Cooling System
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Motivation for the R&D program
Context in France at the end of the 70th •An increase in electrity demand was expected•Reduction of investment costs larger Units
• 250 900 1300 Mwe
• major Limitation : sizes of the turbines• limitation with « direct cooling » capacities
Aim : To reduce turbine size by changing steam with a more dense vapor in the lowest pressure stages
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The H2O/NH3 cycle
The lowest pressure turbine stages in the vapor cycle and steam condenser are replaced with a NH3 cycle
Three specific components :
• Condenser/boiler
• NH3 turbine
• Dry cooling system (Air cooled condenser)d for
450mbar
20% PN80% PN
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Fluid selection
NH3 was selected among a lot of potential candidates•condensation at a higher pressure than external (ambiant) pressure• freezing Temp lower than any expected ambient Tre• relatively high critical point
•« Good » thermal hydraulic parametershigh heat capacity (latent heat)High density of vapor at ambient temperature
•Cost and availability•Risk and operation
EPRI ACT project used (on cooling technology) selected NH3
Tre (35°C) H20 R11 R12 NH3Psat (bar) 0,056 1,49 8,46 13,5Vvap(m
3/kg) 25,3 0,12 0,021 0,096L=Hv-Hl (kJ/kg) 2418 178 135 1123
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Additional advantagesNo water needs (dry cooling)Meet a general issue if limited cooling
capacity on french riversLarger choice for Plant constructions
Extra power supply capabilitycompared to steam cycle
Expected gain of efficiency : 0,45% / °C in winter (cold Temp.)
Power enhancement factor / ambient temperature
Design point
Binary cycle
Steam/water cycle
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Historic of the studies at EDF1970 1982 :
Preliminary studies : technical issues
Assesment of NH3 / no dissociation risks / heat exchange coefficient
Construction of a small pilot plant 600 kW and tests
1978 1979 and 1987 1989
Economical studies
Including
Cycle modelling
Contract with manufacturers / help from EDF Engineering Division
Value of electricity produeced during winter
1979 1987 : Pilot CYBIAM (CYcle BInaire à AMoniac)
Pilot experiment of 22MWe
Construction : 1980 1985
Operation and testing 1986 1989
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The Cybiam experiment feedback
Main features of the experiment
22 Mwe
Heat suply : 400°C et 18bars
Air cooled condenser
Technical aspects
Production of relevant and validated results / comparison with modelling
Know-how on NH3 risk managment
Operation : no particular difficulties for operating the 2 cycles
The gain of power during cold days has been (more or less) demonstrated
Main difficulties
Pump of NH3 (rapid degradations) as vapor can be entrained
prenvented by additional cooling system
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Economic studies (ref. year 1989) 1/3Economic studies include 3 main lines
Research / Development
Investment Costs
Exploitation expected returns
1 – R & Development Costs (1989!!!) MF M€
500 MF (75 M€) for development and for operating Cybiam 500 75
An intermediate step 250 Mwe is requiered (estimation 40 M€) 250 40
But : the Cybiam mock up has been dismantled and technical know-how has partially disapeared
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Economic studies (ref. year 1989) 2/3
2 – Investment Costs (compared with 1300 Mwe)
Two major factors of uncerntainties
Dry cooling system (air cooled condenser of NH3) (textile + natural draft)
Gain due to reduction of buildings for Turbine (reduction factor : 4)
More recent informations would requiere to ask manufacturer
Estimated costs (MF) 1300MW 1300MW Bin Diff
Turbine 762 524 -240 (-33%)
Cond/boiller 88 210 +122 (+120%)
CT/ACC 202 460 +258 (+130%)
Buildings 230 66 - 164 (-70%)
-22 (3,3 M€)
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Economic studies (ref. year 1989) 3/3
3 – Operation
Value of extra power was evaluated in a french (80’s) context
0,45% / °C
Gain of 1000MF (150M€) through the life of 1 Unit 1300 MWe
If cold Tre are available
Uncertainties
Disponibility of the Unit operating with NH3 : 0,8 / 0,85(H20)
Evolution of turbine capabilities (?)
Conclusion after 15 years of R&D
In 1990 : number of expected future plants were very little
Potential Interest for a minimun of 3 Units
R&D effort was stopped (more than 330 documents in reference)
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Current simulations with Thermoptim (1/3)
Objectives
Better understanding of the system / in addition to the review
Capacity to reproduce efficiency of a plant
Evaluate the interest of using Thermoptim
Thermoptim Tool
Capacity to model and design thermodynamic cycles
Optimisation capabilities / Library of numerous fluids
Helpfull for « pre design »
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Simulations (2/3) EPR plant
EPR plant combined with Binarybottoming cycle
Sensitivity to low steam pressure
Sensitivity to exchangers pinch
Sensitivity to ambiant temperature
Comparison with wet or dry cooling
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Puissance fournie
1690
1695
1700
1705
1710
1715
1720
0 100 200 300 400 500 600 700 800
Pression de coupure (mbar)
Puis
sanc
e (M
W)
Débit NH3
3820
3830
3840
3850
3860
3870
3880
3890
0 100 200 300 400 500 600 700 800
pression de coupure (mbar)
débi
t (kg
/s)
Puissance fournie
1200
1300
1400
1500
1600
1700
1800
-10 -5 0 5 10 15 20 25 30 35
Température éxterieure (C)
puis
sanc
e (M
W)
Pression aval turbine BP
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
-10 -5 0 5 10 15 20 25 30 35
Température Exterieure (C)
Pres
sion
(bar
)
Power delivered / steam turbine backpressure
Power delivered / air temperature
Simulations (3/3) EPR plant
1%
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ConclusionAs a conclusion
Previous studies at EDF show the interest of the binary cycle
It is difficult to get more accurate information on costs (how to extrapolate ?)
Technical know how is partially lost (but experiments are well documented)
The context has changed :
the system is economicaly interesting and needs no water
there is an increase in Plant developments (scaling factor)
Next possible steps
Assesment of costs with current and actual values
Combining the H2O/NH3 cycle with heat transfer improvments tested at Kern Station (25 yearsago)
opportunity to engaged new pilot ??