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

Baseline layout

P P VP Vacuum pumpBursting diskPressure relief valveValve

Pressureregulator

Pressuregauge

18 K Heto Compressorvia Radiation shield

14 K Hefrom Cold box

Liquid level gauge

LH2 Absorber

Vacuum

Vacuum vessel

LHe Heat exchanger

Internal Window

70 K Safety window

H2 Gas bottle

PPFill valve

Metal hydride hydrogen storage unit

(20 m3 capacity)

Vent outside flame arrester

He Purge system

Non-return valve

Vent outsideflame arrester

Vent valve

Vent valve

1.7 bar

2.1 bar

H2 Detector

H2 Detector

P

P

PP

Evacuated vent buffer tank

Volume:

VP

P

VP

X 2X 2

VP

H2 Detector

Ventilationsystem

Vent outsideflame arrester

Chiller/ heaterunit

Pipe sizes

0

0.5

1

1.5

2

2.5

3

3.5

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035

Pipe diameter m

Pre

ssu

re d

rop

Bar

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.

No surfaces below Bpt O2

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

END