reactor. ⢠Residence time. : 180 s. ⢠Enlarged reactor bottom diameter. : 450 mm. ⢠DI-Iodine loading. : ~ 550 kg. Entrée iode. Entrée eau. Entrée. SO2. Sortie.
COUPLING A HYDROGEN PRODUCTION PROCESS TO A NUCLEAR REACTOR
P. Anzieu, P. Aujollet, D. Barbier, A. Bassi, F. Bertrand, A. Le Duigou, J. Leybros, G. Rodriguez CEA, France
NEA 3rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct. 2005
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Basic Options (1/2) •
Co-generation is often proposed, but: – Operation of a co-generation plant seems to be difficult – Relative power of H2 and electricity production is an open parameter – Detailed coupling circuit is complicated
•
A dedicated VHTR is studied to deliver heat to a Sulfur/Iodine chemical process – It reduces the number of difficulties – Outlet temperature of the VHTR is adapted to the needed temperature of the process – Electricity comes from the grid – A detailed scheme for the coupled plant should be obtained – Optimization can be done
NEA 3rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct. 2005
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Basic Options (2/2) • • •
A dedicated 600 MWth VHTR Temperature is above 900°C H2 production is around 1 kmol/s H2 storage
Reactor building
Heat exchange
Thermo-chemical Water splitting process
NEA 3rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct. 2005
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Towards a Hydrogen Production Plant •
A reference flow-sheet – With present thermodynamic data – Using chemical engineering techniques – Assessed by expert judgment
• • •
Very detailed flow-sheet based on a conceptual design for an experiment Thermo-chemical analysis of each component Design of each main component – Heat exchangers – Reactive columns
•
Finally a plant layout is drawn
NEA 3rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct. 2005
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A reference flow-sheet • •
Each section is clearly defined in detail Example : Section I (Bunsen) – Excess of water and Iodine (to be optimized in the future) – Elimination of outlet Sulfur dioxide 20bars
C101
3bars
128
133
123
H2O de section II
T101
125
2bars 15bars
124
H2O de section III
O2
1bar
C102
T102 E104
116
D103
115
E103
129
15bars
15bars
117
127
105
121a D101
106
126
122b
E103
121b E104
15bars
F101
E102
E105
111
110
103
F102
131
113 H2SO4 vers section II
3bars
119
SO2
H2O
120
112
107
E101
121d
122a
O2 102
121c
P103
130
114
D102
101 104
108
R101 132
7bars
118
P101 SO2 + O2 + H2O De section II
109 P102
I2 de section III HIx + H2O Vers section III
NEA 3rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct. 2005
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Component design : Bunsen reactor Scaling for a 1 mol/s unit • • • • • •
6200 8100
• • •
900
Entrée SO2 Zone séparation DN 4500
•
1900
Corps réacteur DN 2200 Serpentins 3 nappes Agitateur Rushton 6 pales
2600
Entrée eau
Entrée iode
1300
Sortie H2SO4
1300
1000
REACTEUR DE BUNSEN R101
• • •
Diameter : 300 mm Total Height : 2,100 mm Reactive zone : 1,350 mm Thermal Power : 95 kW Liquid-liquid heat exchange Degraded heat transfer coef. : 540 W.m-2.K-1 Water Coolant : 15 °C – 0.2 MPa (E = 140 °C) Log Pinch Temp. : 98 °C, S = 2.1 m2 Serpentin : 38 spires - DN 25 – D = 0,25m – Pinch 30mm 9 compartments of 150 mm in the reactor Residence time : 180 s. Enlarged reactor bottom diameter : 450 mm DI-Iodine loading : ~ 550 kg
Sortie HIx
NEA 3rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct. 2005
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Component design : H2SO4 / SO3 convertor Scaling 1 mol/s 2 Evaporators (KESTNER type )
SO2 + SO3 + H2O
E207 - Bundle : 9 tubes DN38/34 mm - Height 7,000 mm - Thermal Power 105 kW - Operating temperature : 250 to 370 °C -Operating pressure : 0.4 MPa
E208 - Bundle : 18 tubes DN38/34 mm Height 7,000 mm - Thermal Power : 270 kW - Operating temperature : 370 to 800 °C - Operating pressure : 0.4 MPa
Coupe réacteur H2SO4 87,7%
Hélium
E207
E208
E209
NEA 3rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct. 2005
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Hydrogen Production Plant layout • • •
1 kmol/s = 80 000 m3/h 599 MWth + 100 MWe from the grid 10 shops
NEA 3rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct. 2005
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Coupling the HYPP with a VHTR • • • •
Heat is delivered to High Temperature stage Then to Medium Temperature stage The intermediate circuit includes 1 IHX and 1 Process HX Heat Exchanger temperature pinch must be at least 30°C
NEA 3rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct. 2005
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Transferring heat •
Optimization of the heat transfer piping – Heat loss less than 0.001°C/m (1kW/m) – Pressure drop = 400 Pa /m – Steel tube no more than 400°C
•
Allows several 100 m length of circuit Air e=0.1 m
•
Low temperature Thermal screen
D=0.51m
D=0.2 D=1.2 m
• Inside Ceramic isolation • Ash60 E < 0.5 m
• Hot Helium
Outer Ceramic isolation Ash60 E = ±0.5 m
Finally the needed minimum temperature from the VHTR is calculated 870°C in the process 2 X 30°C temperature drop in IHX > 930°C at the outlet of the core
Liner
Steel Tube 9Cr T= 420°C e= 16 mm
NEA 3rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct. 2005
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Safety Rules for Coupling •
Plants Safety Classing VHTR = Regulated Nuclear Plant Regulations Safety Approach
HYPP = Seveso II Regulations …
Safety of the Coupling = Regulated NP Rules
•
4 levels of sates are studied 1. Normal operation • Respect operating constraints, Master dangerous materials ¾ Heat transfer stability, Hydrogen transfer limitation (T, H2)
2. Abnormal operation • Control, to limit deviations, Protection, to come back to a safe state ¾ Rapid decrease of thermal exchanges,Chemical burst, Abnormal Tritium concentrate, IHX leakage,Isolation valve default
3. Accidents • Uncoupled the facilities, Emergency shutdown systems, Heat removal systems ¾ Loss of elec. Supply, coupling failure, limited HYPP leakages
4. Severe accidents • Impact from one plant on the other, Safety arrangements ¾ Hydrogen risk NEA 3rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct. 2005
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VHTR-HYPP Coupling : Operation Verify compatibility of VHTR and HYPP states –
•
During normal operation, start up, shut down
Heat transfer stability 1. Hot towards HYPP 2. Cold back to VHTR
•
Hydrogen transfer limitation 3. Respect Tritium regulations - Limit H2 permeation
•
1 et 2 : Procedure & system for coupling/decoupling when nominal T° is achieved : – – –
•
Isolation valves VHTR heat removal systems : Self Operating System Possibly, auxiliary heating system on HYPP
3 : Tritium/H2 management – Purification of primary and intermediate circuits – Low IHX permeation Achievable 0,05% transferred = respect 10 pCi/g H2 produced
NEA 3rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct. 2005
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VHTR-HYPP Coupling - Incidents Objectives : • Avoid significant impact from one on the other • Maintain each plant under safe state Incidents to be studied – – – – – –
•
Rapid decrease of thermal exchanges Chemical burst (Bunsen) Abnormal Tritium concentrate IHX leakage Intermediate circuit leakage Isolation valve default : shut-off - rejection
Introduce a tank for heat transfer inertia – Stabilizing SG on intermediate circuit, coupled to HYPP through steam pre-heating
NEA 3rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct. 2005
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VHTR-HYPP Coupling - Accidents • •
Analysis of each plant : internal hazard + coupling Probability/consequences approach : scenario evaluation, acceptance
•
Only concern in a first step : HYPP Accident Products release Explosion - Fire cumulative with VHTR Fission Products release
Provisions • Reduce H2 risk on HYPP + Protect VHTR • Prevention – Detection on production column – Cut off incoming flow in various sections • Back stream on HI distillation column - Stop electrolysis
– Continuous evacuation of H2 production – Non explosive production of H2+H2O – Leakage dilution : HYPP at open air
•
Protection – Separating hill – VHTR underground – Distance • Distant H2 production zone, located in the HI section. Far from the high temperature zone.
NEA 3rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct. 2005
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Hydrogen Risk Mitigation Separating hill
Flow regulation
Distant storage
Reactor building underground
Safe Distance
Leak detection on producing tank
NEA 3rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct. 2005
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Coupling a HYPP to a VHTR : Conclusion • • •
Work is underway to determine the layout of a first S/I chemical facility coupled to a VHTR Using a dedicated plant simplifies the study One needs to iterate between – – – –
• •
Basic data Detailed Flow-sheet Component design Safety needs
For the chemical facility For the coupling circuit – That are new complex systems
• •
Key points are progressively identified Economic evaluation will end the study
Comparative work on other processes is scheduled NEA 3rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct. 2005
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