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Liquid Hydrogen R&D test report
CM34 – 17/10/12
S WatsonP WarburtonM Courthold
Test programmeStated aim to produce 22 litres of LH2
1.Hydride bed charge2.H2 fill x 33.H2 empty x 34.Hydride bed empty
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Bottle ‘incident’• Small leak from H2 bottle when
connecting• Fixing resulted in a brief but rapid
release…vent system went above LEL• All procedures, alarms and interlocks
worked as expected!
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Hydride bed chargeManufacturer suggested 8 hour charge
• Started with heater-chiller at -15°C• Connected 2 H2 bottles (~16000l)• Regulator set to 1.5 bara• No flow meter in line so only indicator of
progress was bottle pressure• Dropped to <10 bar in ~2 hours
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First H2 fill• Commenced fill at 3am on 30th July• Cooldown rapid – pressure control loop
started after 16 hours• Hydride bed back pressure dropped
faster than expected...• …and heater loop did not initiate• Hydrogen began to freeze• Fill aborted
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Bed pressure starts to drop
H/C temp increased
Control valve stays open
Hydrogen starts to freeze
Second H2 fill• Restarted without empty sequence• Manual control of heater and hydride
bed temperature• Reached 10,000 litres of H2…• …equated to approx 12 litres of LH2
No graph…control system reset and overwrote data!
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Empty sequence• Sequence uses heater to boil off LH2
and return to hydride bed• Very conservative starting conditions,
gradually ramped up• LH2 boil-off completed in approx 15
hours
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Pressure setpoint changed
LH2 all boiled off
Final H2 fill• Automatic control of heater• Manual control of hydride bed temp• Realised that HX temperature must be
lower than expected to condense• Optimised setpoint resulted in steady
condensation rate• Heaters are critical when H2 flow slows
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Hydride bed temp increased Hydride bed temp
maxed
H2 flow beginning to slow; heater
loop now critical
Hydride bed empty• Purge of gas panel with helium• Set hydride bed to max temperature
and pumped directly on it• After approx 12 hours, pressure was
around 100 mbar• Filled with argon to 3 bar and closed
hand valve = back to original state
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Improvements• Sensors for flow in to hydride bed• Improve resolution of temp sensors• Procedural changes
• Vent hydrogen in fault condition• Increased N2 purge flow rate
• Do we need a hydride bed?
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Step IV plan• HAZOP • Design review• Modifications required by above• AFC interface manufacturing• Step IV operation• Commissioning
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End
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