COUPLING A HYDROGEN PRODUCTION PROCESS TO A NUCLEAR REACTOR

Transcription

1 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 3 rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct

2 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 3 rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct

3 Basic Options (2/2) A dedicated 600 MWth VHTR Temperature is above 900 C H 2 production is around 1 kmol/s H 2 storage Reactor building Heat exchange Thermo-chemical Water splitting process NEA 3 rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct

4 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 3 rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct

5 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 2bars C bars T101 15bars 3bars H 2 O de section II H 2 O de section III 115 E103 D101 15bars D103 15bars T102 C102 E a 121b E b E104 1bar O 2 15bars 117 F101 E102 E c 121d P a O E101 F H 2 SO 4 3bars vers section II 119 SO H 2 O 114 D R bars P101 I 2 SO de section III 2 + O 2 + H 2 O 109 De section II P102 HI x + H 2 O Vers section III NEA 3 rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct

6 Component design : Bunsen reactor Scaling for a 1 mol/s unit REACTEUR DE BUNSEN R101 Sortie H 2 SO 4 Entrée eau Corps réacteur DN 2200 Serpentins 3 nappes Agitateur Rushton 6 pales Entrée SO 2 Zone séparation DN 4500 Entrée iode 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 (E = 140 C) : 15 C 0.2 MPa 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 Iodine loading : ~ 550 kg Sortie HI x NEA 3 rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct

7 Component design : H 2 SO 4 / SO 3 convertor SO 2 + SO 3 + H 2 O Scaling 1 mol/s 2 Evaporators (KESTNER type ) 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 H 2 SO 4 87,7% Hélium E207 E208 E209 Coupe réacteur 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 NEA 3 rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct

8 Hydrogen Production Plant layout 1 kmol/s = m 3 /h 599 MWth MWe from the grid 10 shops NEA 3 rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct

9 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 3 rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct

10 Transferring heat Optimization of the heat transfer piping Heat loss less than C/m (1kW/m) Pressure drop = 400 Pa /m Steel tube no more than 400 C Allows several 100 m length of circuit Hot Helium D=1.2 m D=0.51m D=0.2 Air e=0.1 m Low temperature Thermal screen Inside Ceramic isolation Ash60 E < 0.5 m Liner 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 Outer Ceramic isolation Ash60 E = ±0.5 m Steel Tube 9Cr e= 16 mm T= 420 C NEA 3 rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct

11 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 Heat transfer stability, Hydrogen transfer limitation (T, H 2 ) 2. Abnormal operation Control, to limit deviations, Protection, to come back to a safe state 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 Loss of elec. Supply, coupling failure, limited HYPP leakages 4. Severe accidents Impact from one plant on the other, Safety arrangements Hydrogen risk NEA 3 rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct

12 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 H 2 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/H 2 management Purification of primary and intermediate circuits Low IHX permeation Achievable 0,05% transferred = respect 10 pci/g H 2 produced NEA 3 rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct

13 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 3 rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct

14 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 H 2 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 H 2 production Non explosive production of H 2 +H 2 O Leakage dilution : HYPP at open air Protection Separating hill VHTR underground Distance Distant H 2 production zone, located in the HI section. Far from the high temperature zone. NEA 3 rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct

15 Hydrogen Risk Mitigation Separating hill Flow regulation Distant storage Reactor building underground Safe Distance Leak detection on producing tank NEA 3 rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct

16 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 3 rd Meeting on Nuclear Production of Hydrogen, OARAI, Japan, 5-7 Oct