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MICE Hydrogen System Implementation. Tom Bradshaw Elwyn Baynham Iouri Ivaniouchenkov Jim Rochford. Talk Contents. Design Criteria – what is the conceptual basis for the design Baseline layout Specification for the hydride beds Safety containment Pipework and implementation
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MICE Hydrogen System Implementation Tom Bradshaw Elwyn Baynham Iouri Ivaniouchenkov Jim Rochford
Talk Contents • Design Criteria – what is the conceptual basis for the design • Baseline layout • Specification for the hydride beds • Safety containment • Pipework and implementation • Thermal issues
Design Criteria • Independent systems on each of the absorbers to eliminate consequential effects • This will also ease the staging of MICE and reduce the need for extra testing • Easier to isolate faults • Smaller systems are easier to deal with
Design Criteria (2) • Minimise venting and purging • Most accidents have happened during venting operations • Sealed system is safer – we have quite a large amount of hydrogen 3 x 22 litres of liquid • Minimise amount of hydrogen
Design Criteria (3) • Must be safe in the event of a power loss or system shut-down • No surfaces below the BPt of Oxygen – this is to prevent cryopumping of oxygen on any surface that may come into contact with hydrogen in the event of a failure • Safety volumes to contain gas, relief valves to prevent back flow in case of catastrophic release • Prove a system for a neutrino factory
P P P P P H2 Detector H2 Detector H2 Detector P P P VP VP VP VP Baseline layout Metal hydride hydrogen storage unit (20 m3 capacity) Vent outside flame arrester He Purge system Chiller/ heater unit 14 K He from Cold box 18 K He to Compressor via Radiation shield P Fill valve X 2 X 2 1.7 bar H2 Gas bottle 2.1 bar Liquid level gauge Vent valve Vent outside flame arrester Vacuum Ventilation system Internal Window LH2 Absorber 70 K Safety window Vent valve LHe Heat exchanger Vent outside flame arrester Evacuated vent buffer tank Volume: Vacuum vessel Pressure relief valve Pressure regulator Non-return valve Pressure gauge Vacuum pump Valve Bursting disk
Pipe sizes Specific load (W/cm2) 3.6 Load (W) 5089.38 Safety factor x2 (W) 10178.76
Absorber properties • Liquid-hydrogen volume (at 20K), litres 21 • Hydrogen volume (at STP), litres 16548 • LH2 operating temperature, K 18 • LH2 operating pressure, bar abs 1.2 • LH2 max pressure, bar abs 1.7 • LH2 min pressure, bar abs 1.05 • Max. heat removal, W 100 • Refrigerant mass flow, g/s <2 • Refrigerant inlet (outlet) temperature, K 14 (18) • Refrigerant inlet (outlet) pressure, bar 18(14) • Absorber vacuum volume (within the module), litres 91
Hydride Bed Parameters • Preferable size <1 m3 • Environment temperature 15-25 °C • Operating pressure in the system, bar abs 1.2 • Max. pressure in the system, bar abs 1.7 • Min. pressure in the system, bar abs 1.05 • Hydrogen storage capacity (at STP), litres 20000 • Absorber filling/empting time, hours 5
Safety Containment • All external hydrogen pipes will be coaxial with an Argon jacket • Hydrides and gas handling system will be situated under a hood
Layouts – Pipework • Use co-axial lines to prevent hydrogen escaping into the hall • Storage and buffer tanks located in a vented enclosure • Hydrogen pipes are at a high level so that any flames or escaping gas does not pass any personnel
No surfaces below Bpt O2 Model run with 10 layers of MLI on inner surfaces and thermal isolation as shown Thermal models used to verify the temperatures of the outer window in normal operation.
Implementation • Absorbers will be tested prior to installation (see accompanying presentation) • When in place helium leak detection will be used to check the leak tightness of the system prior to filling with hydrogen
Implementation • Hydrogen sensors will be fitted in appropriate areas in the laboratory • Intrinsically safe electrical connections will be made to all parts of the hydrogen system • User and operating manual, procedures will be developed for the safe operation. • A training plan will be developed
Summary • We have well defined criteria for the current design of the hydrogen system • Areas of risk have been identified and removed in the design • Inherently safe system that will passively reach a stable state without operator intervention