1. MICE Hydrogen System Tom Bradshaw Yury Ivanyushenkov Elwyn Baynham Meeting October 2004 – Coseners House

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

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. 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

7. 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)

8. R&D Process Main issue is what will the funding profile allow ?…… We will be using a cryocooler and perform tests on the control system,condensation rate etc… 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.

9. Safety Review Process

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