1. MICE Hydrogen System Tom Bradshaw Yury Ivanyushenkov Elwyn Baynham Collaboration Meeting RAL October 2004

2. Baseline layout Pressure gauge Non-return valve - PP VP Vacuum pump Bursting disk Pressure relief valve Valve Pressure Coolant Out In Metal Hydride storage unit (20m 3 capacity) Purge valve 0.5 bar 0.9 bar H 2 Detector P P VP1 VP2 Purge valve Chiller/He ater Unit 1 bar P P 0.5 bar 0.9 bar Helium supply Hydrogen supply High level vent Buffer vessel Vent outside flame arrester Extract hood H 2 Detector P P Nitrogen supply P P P P 1 m 3 Hydrogen zone 2 Vent manifold P1 PV1 PV7 PV8 PV2 PV3 PV4 HV1 Fill valve Tbed HV2 HV3 P3 P P2 PV6 High level vent Non return valve 0.1 bar - PP VP Vacuum pump Bursting disk Pressure relief valve Valve Pressure regulator Coolant Out In Absorber window Metal Hydride storage unit (20m 3 capacity) Purge valve 0.5 bar 0.9 bar H 2 DetectorH 2 P P VP1 VP2 Purge valve Chiller/He ater Unit 1 bar P P 0.5 bar 0.9 bar Helium supply Hydrogen supply High level vent Buffer vessel Vent outside flame arrester Extract hood H 2 DetectorH 2 P P Nitrogen supply P P P P 1 m 3 Hydrogen zone 2 Vent manifold P1 PV1 PV7 PV8 PV2 PV3 PV4 HV1 Fill valve Tbed HV2 HV3 P3 P P2 PV6 High level vent Non return valve 0.1 bar Safety window

3. Hydride bed Checked that there are no safety issues if there is a catastrophic ingress of air. Activation procedure: a)Pump out absorber b)Heat to 60-80C c)Add H2 to about 1.2 bar d)Leave to soak for 8 hours Tanks need to be horizontal Air ingress reduces capacity and oxidises material – oxidation rate is low. Alloy will become flammable after activation but it needs an ignition source.

4. Hydride Bed Black lines absorbtion Dotted lines desorbtion 20l liquid = 16,000 normal litres gas – will absorb this in under 4 hours Hydride Characteristics If we operate at constant pressure e.g. 1 atm, start at 0C and end up at 17C

5. Specification for the Hydride Bed Hydrogen Storage Capacity 20 Nm 3 Tank number/system 1 Tank Description: Heat Transfer Medium Water MH Weight 155kg Tank Structure Shell & Tube type Dimensions φ216.3×L1600 （ mm ） ( not include attachments ) Tank Total Weight 220 Kg Operating Condition: Charging Gas Component Hydrogen of 99.99% purity Charging Gas Pressure 1.2 barA Hydrogen Charging Rate 70NL/min (up to 90% of Storage Capacity) Discharging Gas Pressure 1.2 barA Hydrogen Discharging Rate 70NL/min (up to 90% of Storage Capacity) Utility Requirements: Cooling Medium Water Below -10 ℃ （ At 20L/min ） Heating Medium Above 20 ℃ （ At 20L/min ） Design Code AD Merkblaetter Certification Declaration of Conformity to Pressure Equipment Directive 97/23/EC Certified by a Notified Body ）

6. Stillwater News - Montana Stillwater Mine goes for a first For the first time anywhere in the world a Hydrogen powered engine is being tested in an underground mine. The project was to demonstrate that hydrogen could be used safely in mining. To do this hydrogen had to be stored as a solid in what is referred to as a hydride bed. In this state, tests conducted at a US Army firing range showed that even bullets, shot through the bed, would not cause a fire or explosion. A water-cooled Caterpillar 3304 diesel engine was modified to use hydrogen, replacing the factory installed air-cooled engine. As a hydrogen internal combustion engine, it has spark plugs with individual coils, and an engine-driven magneto to provide spark and timing. The hydrogen gas is injected into the cylinders, much as an engine converted to run on natural gas or liquid petroleum.

7. Effectiveness of Buffer Volume Assumes mixing of gas - cold from absorber + buffer volume Temp in buffer calc on basis of constant Cv - this is optimistic for Tgas ~50K but pretty good for Tgas >100K For large outflow through relief valve the algorithm is not correct because the valve essentially shuts Buffer volume gives a huge safety margin over just the pipe system with vol ~ 0.1m^3 for 50m of 50mm dia pipe The buffer vessel will keep the gas warmer due to its thermal mass - this is not included - it will increase the pressure rise Typically with 1m^3 Tgas ~100K pressure rise rate is 0.1 bar/sec valve opening time of 0.1-0.2 sec would be OK Expected boil-off rate Latent heat446000J/kg Power into liquid10179W Hydrogen boiled off (kg/s) 0.0228 23kg/s Start mass of liquid1.544kg Liquid density70.288 Start pressure (bar)0.5 Rgas4157 dt0.2 Buffer vol1m^3 density 300K0.08 kg/m^ 3 relief valve pressure 1.60E+ 05Pa outlet mass flow 1.20E- 02kg/s

8. Pressure relief valves They also manufacture bursting discs and flame arrestors Feel confident that we have a solution for this. Tyco (Crosby) valves – key points: Pilot valves – quick acting 3% tolerance on set pressure Closes at 95% of set pressure Response time is <0.5s Valves re-seat on elastomers 91&94 valves usable to 20K (although situated at RT)

9. Loss of Vacuum In the event of a catastrophic loss of vacuum the sequence indicated in the previous slide takes place In the event of a moderate vacuum leak the system pressure will rise until 1 bar is reached when the pressure relief valve to the hydrogen bed will open and the gas will be absorbed by the hydride bed without any increase in pressure.

10. Prototyping Main issue is what will the funding profile allow ?…… Aim is to duplicate the absorber/cryocooler system without the windows, possibly reduced capacity. Using a cryocooler we will perform tests on the control system,condensation rate etc… We are developing a prototype control system logic Next steps are to design layouts in the hall, pipework – test area Installation of venting system Design and order cryostat and cryocooler Order hydride bed Pressure relief valves Control system Issue of the test area is still not finalised – is it sensible to test while other work is going on ? May have to make a safety case or find somewhere else.

11. Safety Review Process

12. Conclusions  We have made good progress on the definition of the hydrogen supply system for the absorber.  The safety issues are under control.  Need to define more carefully the development plan – recent cost review.  Test area is still a slight issue. Should be possible to start work on venting in the hall.  Need to start design work to get approvals – meet design codes head on.  Many of the critical components are defined.

13. END SourceD:\MICE\Cryogenics\HydrogenSystem\[Pressure rise buffer.xls]press buffer-2