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Hydrogen R&D System Operational Procedures and Test Plan

This outline provides operational procedures and a test plan for setting up, purging, and testing the hydrogen R&D system, including the hydride bed, before normal operation. It includes steps such as system purge and retest with helium, hydride bed preparation for service, and filling with liquid hydrogen.

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Hydrogen R&D System Operational Procedures and Test Plan

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  1. Hydrogen R&D SystemOperational Procedures and Test Plan M Courthold

  2. Outline • Hydrogen R&D System Set-Up • Test Plan • System Purge and Full System Retest with Helium • Hydride Bed • Preparation for Service • Purge Fill-Line and Charge Hydride-Bed • Absorber • Cool-down • Fill with Liquid Hydrogen • Normal Operation • Warm-up, and Return Hydrogen to Hydride Bed • Test Objectives • Operational Procedures • Fault Procedures

  3. R&D System Set-Up 1 Vacuum Pump Enclosure Relief lines Gas Panel Enclosure Fans Test Cryostat Ventilation ducts 3

  4. R&D System Set-Up 2 4 Gas Panel: • In “position 3” and connected to hall air supply • Final wiring in place • Transfer line jacket in place, with nitrogen purge Cryocooler: • Compressor in final MICE running location and connected to hall cooling water supply • Lines stored in reel as they will be for the AFC Helium Supply: • System filled from BIP grade helium pack outside the hall Control System: • Final wiring in place, with PLC logging temperatures, pressures and levels; and now in full control of pumps, valves, cryo-compressor, hydride-bed chiller, heaters, and all control loops. Vacuum System: • Dedicated turbo-pump System now used for cryostat vacuum • System purge pump now relocated in external vacuum enclosure Cryostat: • All sensors now fully operational

  5. System Purge and Retest with Helium Following Helium commissioning of the Hydrogen R&D system and subsequent integration of the following: hydrogen bottle-store hydride bed and chiller unit ventilation system dedicated pumping systems the R&D system will undergo a retest as follows: Leak-testing of an new or disturbed compontents Thorough purge of whole system: by successive helium & vacuum purges to include all new pipe-work but excluding the hydride bed The system will then undergo a retest with helium that will include: Cool-down Liquefaction with helium Warm-up and purge This will ensure that all system components are fully tested before introducing hydrogen

  6. Hydride BedPreparation for Service The hydride bed has been filled with Argon gas, to a pressure of approximately 4 bar, since manufacture, and the Argon will only be removed from the hydride bed when the hydrogen system has been cleaned of all contaminants (especially air), and ready for charging with hydrogen for the first time.

  7. Hydride BedPurge Fill-Line and Charge Hydride-Bed The hydrogen fill-line is vacuum & helium purged each time the hydride bed needs to be charged/recharged with hydrogen, and also between any bottle changes. To minimise purging operations, the hydrogen filling point will be equipped with a regulator and manifold, allowing two bottles to be fitted to the fill-line and then purged – which should be sufficient for a complete charge of the hydride bed. The hydride bed is charged with hydrogen gas, by setting the chiller unit to -10 degC, setting the hydrogen supply regulator to 1.3 bar, then opening the fill-line valve, followed by the hydride-bed isolation valve The hydride bed is charged when 8 hours have elapsed, or 2 bottles have been emptied into the bed As soon as hydrogen filling operations are complete, the fill-line will be purged, the hydrogen bottles removed from the hall, and the filling ports locked closed.

  8. AbsorberCool-down and Fill with LH2 The hydrogen fill sequence is used to fill the absorber with liquid hydrogen. The pipework and cryostat insulating volume are evacuated, then the system is pressurised with gaseous hydrogen from the hydride bed using the heater-chiller system. The hydrogen is then liquefied using a gravity-feed cryogenic circuit. Hydrogen is evolved from the hydride bed by initially setting the heater-chiller temperature sensor (TS1) set point to 50°C (TBC), and then initiating the hydride bed pressure control loop, using the hydride bed temperature sensor (TS1) and hydrogen system pressure gauge (PG1). The cryo-cooler is switched on, with the balancing heaters (HTR2) under PID control to keep TS6 at 15K. The hydrogen system valve (PV02) and buffer tank valve (PV03) are opened, and the control valve (CV04) gradually opened, allowing hydrogen to enter the buffer tank. When the absorber pot level sensor (LS1) reaches its set point, the hydrogen system, buffer tank and control valves (PV02; PV03; PV04) are closed. The hydride bed pressure control loop is then stopped, and the hydride bed heater-chiller temperature sensor (TS1) set point is set to -10°C (TBC), which ensures that any excess hydrogen will be absorbed back into the hydride bed.

  9. Warm-up Absorberand Return Hydrogen to Hydride Bed The hydrogen empty sequence is used to empty the absorber of liquid hydrogen following a hydrogen fill sequence, and normal operations. The sequence opens the bypass line to the hydride bed and slowly heats up the absorber pot, allowing boiled-off hydrogen to return to the bed. Once all the liquid hydrogen has boiled off, the hydride bed is isolated.

  10. Test Objectives Measure Absorber cool-down period: 1 day anticipated with LN2 pre-coolSave the cool-down characteristics for future system-integrity checks Measure Helium liquefaction rate: Liquefaction should be possible, but will take many days Check operation of liquid level meters with hydrogen,then measure Hydrogen liquefaction period: 8 days anticipated Save the liquefaction characteristics for future system-integrity checks Measure actual Hydride Bed absorption and desorption rates: Manufacturer measured 50L/min Repeat control sequences as required to confirm operational procedures, control loop parameters, etc. Perform other tests as required by MICE TB and/or MICE/ISIS Safety Committee

  11. System Purge The sequence cycles between vacuum and 1.1 bar helium in the hydrogen circuit three times to clear pipework and valves of contaminants. Hydrogen system purge pump (VP1) is switched on, and kept isolated (PV19) until vacuum gauge (VG5) reads < 5 mbar. The system is prepared by opening valves to the H2 buffer tank, relief line and bypass line (PV03; PV05; PV07), whilst keeping control valve (CV04) and H2 system valve (PV02) closed to limit the initial volume to be pumped, then helium bottle hand-valve (HV16) is opened. The hydride bed, hydrogen bottle, vent line and helium bottle remain isolated by their respective valves (PV01; PV14; PV17; PV18). Purge pump valve (PV19) is opened, and the line between control valve (CV04) and H2 system valve (PV02) evacuated, then control valve (CV04) is gradually opened, followed by H2 system valve (PV02), and the system evacuated. When pump vacuum gauge (VG5) and buffer tank pressure gauge (PG2) read < 1 mbar and < 500 mbar respectively, then purge pump valve (PV19) and control valve (CV04) are closed, after which H2 system valve (PV02) is closed, and helium bottle valve (PV18) is opened. Control valve (CV04) is gradually opened to fill the system with helium. When H2 system pressure gauge (PG1) and buffer tank pressure gauge (PG2) both read between 1.1 and 1.3 bar, helium supply valve (PV18) and control valve (CV04) are closed. The purge sequence is repeated twice more.

  12. Hydrogen Fill-Line Purge The sequence vacuum purges, then helium purges the hydrogen fill-line three times, to clear the pipework and valves of contaminants, prior to and following a hydride-bed charge, or following a bottle change. Prior to starting this sequence, a standard helium purge will have been performed. The hydrogen bottle(s) are connected to the charging station, ensuring that the bottle valve (s) are kept closed. Valve HV24 is then opened. The system valves are set to isolate the buffer tank and absorber from the hydrogen fill-lines Purge pump (VP01) is started, and as soon as vacuum gauge VG5 reads < 5 mbar, valve PV19 is opened to evacuate the hydrogen line as far as the bottle After a minimum of 60 seconds, and when VG5 < 1mbar, PV19 is closed. PV18 is then opened to fill the lines with helium until PG01 is > 1.3bara, after which it is closed again. The vacuum and helium purges are repeated twice more to ensure that all contaminants have been removed. Valves PV02 and PV14 are then closed

  13. Helium Fill The helium fill sequence is used to fill the absorber with helium for testing purposes. The pipework and cryostat insulating volume are evacuated, then the system is pressurised with helium gas from a bottle via a control valve. The helium is then liquefied using a gravity-feed cryogenic circuit. The system is purged and left under vacuum following a helium purge sequence. With cryostat valve (PV20) closed, turbo pump (VP2a) and backing pump (VP2b) are switched on until the pump outlet vacuum gauge (VG6) reads < 5 mbar. Cryostat valve (PV20) is then opened, and the cryostat evacuated, until both the cryostat vacuum gauge (VG3) and pump outlet vacuum gauge (VG6) read < 5 mbar. The system is prepared by opening H2 buffer-tank valve (PV03) and helium bottle hand-valve (HV16). Control valve (CV04) is set to 5%. The valves to the hydride bed, H2 system, relief line, various bypass lines, hydrogen bottle, vent line, helium bottle and purge pump (PV01; PV02; PV05; PV07; PV08; PV11; PV14; PV17; PV18; PV19) are all closed. The helium bottle regulator is set to 1.3 bara, then helium-bottle valve (PV18) is opened and helium-flow throttled through control valve (CV04), until buffer-tank pressure-gauge (PG2) reads between 1.1 and 1.3 bar. This pressure is maintained using a PID pressure control loop during subsequent operations. The cryocooler is started, with all heaters off

  14. Helium Empty 1 The helium empty sequence is used to empty the absorber of liquid helium after a helium fill sequence. The sequence opens the vent line and slowly heats up the absorber pot, controlling pressure using the control valve. Once all the liquid helium has boiled off, the vent line is closed. The Absorber volume will contain LHe following a Helium Fill. If the vacuum pumps are running and PV20 is open, the following two steps can be skipped. With cryostat valve (PV20) closed, turbo pump (VP2a) and backing pump (VP2b) are switched on until pump outlet vacuum gauge (VG6) reads < 5 mbar. Cryostat valve (PV20) is opened until cryostat vacuum gauge (VG3) and pump outlet vacuum gauge (VG6) both read < 5 mbar. The system is prepared by opening H2 buffer-tank valve (PV03) and vent-line valve (PV17). The control valve (CV04) is closed. The valves to the hydride bed, H2 system, relief line, various bypass lines, hydrogen bottle, helium bottle and purge pump (PV01; PV02; PV05; PV07; PV08; PV11; PV14; PV18; PV19) are all closed. The PID pressure control loop between control valve (CV04) and buffer-tank pressure-gauge (PG2) is initiated to maintain a tank pressure between 1.1 and 1.3 bar. The cryocooler is switched off.

  15. Helium Empty 2 When buffer tank pressure gauge (PG2) reads < 1.3 bar, and control valve (CV04) has fully opened, absorber heater (HTR1) control loop is initialised, again using buffer tank pressure gauge (PG2) and absorber temperature sensor (TS3). When the absorber temperature sensor (TS7) reads > 25K, signifying that all liquid helium has been boiled off, both the cryocooler and absorber heater (HTR1) control loop are stopped. The pressure control loop using CV04 under PID control is reinstated. When TS7> 270K, control valve (CV04) and vent line valve (PV17) are closed. The turbo pump (VP2a) and backing pump (VP2b) are switched off.

  16. Hydride BedPreparation for Service 1 The hydride bed is supplied from the manufacturer filled with argon at 4 bar(a). Initial connection of the bed to the hydrogen system must safely vent this argon, ensuring no air enters the bed, in preparation for filling with hydrogen. Note: this sequence assumes that it is possible to pull a vacuum on the regulator (PR29) without drawing air into the system. It is proposed to confirm this assumption with a dedicated test before connecting the bed. The system will be clean and pressurised with helium to 1.1 bar, following a Helium Purge sequence. The hydride bed connections are made at IF01GP and IF02GP Initially all valves will be closed, apart from PV02, and helium regulator set to 1.3bara Purge pump (VP01) is started, and allowed to run until vacuum gauge VG05 reads < 5mbar. PV01 is then opened to mix the air in the hydride-bed lines with the helium in the supply lines PV18 is then opened to pressurise the supply lines to 1.2 bara (PG7) PV18 is then closed to isolate the helium bottle, and PV19 opened to evacuate the supply lines until VG5 reads < 5mbar, after which PV19 is closed to isolate the pump The helium and vacuum purges are then repeated twice more

  17. Hydride BedPreparation for Service 2 PV18 is then opened to pressurise the supply lines to 1.2bara (PG7), after which PV18 is closed to isolate the helium bottle PV03 and CV04 are opened to equalise pressures in the system The hydride-bed hand-valve is then gradually opened, ensuring that the system pressure remains limited to 1.2 bar max via regulator PR29 to release the argon into the buffer tank and rest of the system When the flow-meter (FM2) reads zero, CV04 and PV01 are closed to isolate the buffer tank and hydride bed PV19 is then opened to pump out the supply lines until VG5 reads < 5mbar Control valve CV04 is ramped open to perform a controlled evacuation of the rest of the system, and Pump down until VG5 < 5mbar Close PV19 to isolate the pump

  18. Hydride BedCharging with Hydrogen 1 The hydrid bed charge sequence charges the cooled hydride bed with pressurised hydrogen from bottles. Prerequisite: System clean and pressurised with helium to 1.3 bar as per conclusion of H2 Line Purge Sequence (and Standard Helium Purge If required) Hydrogen Permit & PV14 Key Issued. All PV valves, CV04 and HV24 are closed, and all hand valves opened (N2 flow rate FM05 > minimum (TBD)) except HV24, and hydrogen bottle regulator set to 1.3 bar. The Heater / Chiller HC-01 is started, with a temperature set-point of -10Deg C (TBD) When TS01 & TS02 = -10Deg C (TBD), the H2 System Pump (HX-VP01), and when VG01 reads < 5 mbar, PV19 & PV02 are opened When VG01 < 5 mbar and PG01 < 500mBar, the hydrogen bottle valves are opened, the regulator pressure checked, and HV24 gently opened. Hydrogen supply valve (PV14) is opened, pressurising the supply lines, then hydride-bed valve (PV01) is opened, releasing pressurised hydrogen through the non-return valve and into the hydride bed

  19. Hydride BedCharging with Hydrogen 2 The bed is charged for 8 hours (TBD) or until 2 bottles of hydrogen have been emptied into the system, then PV14 is closed to isolate the system When hydrogen system pressure gauge (PG1) reads < 1.1 bar, hydride bed valve (PV01) is closed A purge sequence is initiated The hydrogen bottle valves and HV24 are closed, and the bottles removed from the MICE Hall It is estimated that two 50L, 200bar bottles will be required to charge the bed with sufficient hydrogen to fill an absorber.

  20. Hydrogen Fill 1 The hydrogen fill sequence is used to fill the absorber with hydrogen for testing purposes. The pipework and cryostat insulating volume are evacuated, then the system is pressurised with gaseous hydrogen from the hydride bed using the heater-chiller system. The hydrogen is then liquefied using a gravity-feed cryogenic circuit. Prior to filling with hydrogen, the system will have been cleaned and under vacuum as per the Helium Purge sequence With cryostat valve (PV20) closed, the turbo pump (VP2a) and backing pump (VP2b) are switched on until pump outlet vacuum gauge (VG6) reads < 5 mbar. Cryostat valve (PV20) is then opened until the cryostat vacuum gauge (VG3) and pump outlet vacuum gauge (VG6) both read < 5 mbar. The system is prepared by opening hydride bed valve (PV01), and closing all other system valves. The hydride-bed heater-chiller temperature sensor (TS1) set point is set to 50°C (TBC) The hydride bed pressure control loop is then initiated, using the hydride bed temperature sensor (TS1) and hydrogen system pressure gauge (PG1). The cryocooler is switched on with the balancing heaters (HTR2) under PID control to keep TS6 at 15K.

  21. Hydrogen Fill 2 The hydrogen system valve (PV02) and buffer tank valve (PV03) are opened, after which control valve (CV04) is gradually opened, allowing hydrogen to enter the buffer tank. When the absorber pot level sensor (LS1) reaches its set point, the hydrogen system, buffer tank and control valves (PV02; PV03; PV04) are closed. The hydride bed pressure control loop is then stopped, and the hydride bed heater-chiller temperature sensor (TS1) set point is set to -10°C (TBC) The hydrogen system relief valve (PV05) is then opened to allow any boil-off to return to the hydride bed.

  22. Hydrogen Empty The hydrogen empty sequence is used to empty the absorber of liquid hydrogen following a hydrogen fill sequence, and normal operations. The sequence opens the bypass line to the hydride bed and slowly heats up the absorber pot, allowing boiled-off hydrogen to return to the bed. Once all the liquid hydrogen has boiled off, the hydride bed is isolated. The Absorber will be filled with LH2, and in normal operation, following a Hydrogen Fill sequence The hydride-bed heater-chiller temperature sensor (TS1) set point is set to -10°C (TBC) The hydrogen system bypass valve (PV07) is opened. The cryocooler temperature increases until the absorber pot temperature sensor (TS3) reads 20K (TBC). When the absorber pot level sensor (LS1) reaches its lower set point, the cryocooler temperature increases again. The absorber heater pressure control loop is initiated to maintain the buffer tank pressure gauge (PG2) between 1 bar and 1.3 bar. When the absorber temperature sensor (TS3) reaches > 30K, the cryocooler and absorber heater control loop are stopped. When the buffer tank pressure gauge (PG2) reads less than 0.1 bar and the absorber temperature sensor (TS3) reads greater than 100K, the hydride bed valve (PV01) is closed.

  23. System Safe State The system has a ‘safe state’ which it will default to under power or air supply failure to the valves. In this state only PV01 and PV05 are open to allow any hydrogen that is boiling off to return the hydride bed. HV15 stays open to keep the vent lines purged. If power remains on, the Heater/Chiller is set to cool the hydride bed so that it can absorb any hydrogen in the system.

  24. Procedure for dealing with a leak while the mains power is on The aim would be to lock as much hydrogen in the bed before purging and pumping out any that remained. The Gas Panel Enclosure could then be opened and the leak investigated. Note that if the PLC is stopped it will give 0mA control signal to LH50 Heater / Chiller setting it to chill

  25. Procedure for dealing with a leak following a power failure It should be noted that coincidence of a power failure with the detection of a leak can be considered highly unlikely.  If no leak is detected, the system idles with the passive relief devices taking care of any temperature – and associated pressure – rise. If a leak is detected, the hydrogen is relieved through the high level vents using either the heaters or the vacuum poisoning system. In either case, as soon as power returns a purge sequence would be run, after which the source of the leak could be investigated.

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