Transcript MICE Hydrogen System. Preliminary HAZOP. Elwyn Baynham, Tom Bradshaw and Iouri Ivaniouchenkov, RAL MICE Absorber working group meeting @ Columbia, 13 June 2003

MICE Hydrogen System.
Preliminary HAZOP.
Elwyn Baynham, Tom Bradshaw and Iouri Ivaniouchenkov,
RAL
MICE Absorber working group meeting @ Columbia, 13 June 2003
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Hydrogen flow and safety system
Version: 09/06/2003
VP
P
P
He / N2 Purge
system
Vent outside
flame arrester
Hydrogen tank
Volume: 11 m3
Pressure > 0.1 bar
14 K He
from Cold box
18 K He
to Compressor
via Radiation shield
X2
Fill valve
P
P
X2
H2 Gas bottle
1.7 bar
P
2.1 bar
12 litre Buffer tank
Liquid level gauge
Vent valve
P
H2 Detector
Vacuum
Ventilation
system
H2 Detector
Internal Window
Vent outside
flame arrester
LH2 Absorber
H2 Detector
70 K Safety window
P
Vent valve
LHe Heat
exchanger
Vent outside
flame arrester
Evacuated vent
buffer tank
Vacuum vessel
Volume:
VP
VP
Hydrogen module enclosure (igloo)
P
Pressure
gauge
P
Pressure
regulator
Valve
Pressure
relief valve
MICE Absorber working group meeting @ Columbia, 13 June 2003
Non-return
valve
Bursting disk
VP
Vacuum pump
2
Node 1: Hydrogen tank
Intent: To keep hydrogen gas in the tank-hydrogen vessel closed system.
No
Parameter
Guide
word
Cause
Consequence
Safeguards
Recommendations
1
Pressure
Lower
1. Tank is leaking.
1. Air can leak in the
tank and in the
hydrogen vessel and
an explosive mixture
can be formed.
2. Hydrogen is
leaking out in the
experimental hall.
3. Hydrogen is
leaking into vacuum
jacket.
Pressure gauge to
trigger an alarm.
Implement an active
pressure gauge.
Hydrogen ventilation
system collects and
vents hydrogen out.
Implement ventilation
system.
Tank can brake
Pressure relief valve
to vent outside.
2. Pipe is leaking.
3. Absorber vessel is
leaking.
2
Pressure
Higher
Fill valve is
accidentally open
Tank is overheated
MICE Absorber working group meeting @ Columbia, 13 June 2003
Hydrogen detector to
trigger an alarm.
Implement an active
hydrogen detector.
Implement a pressure
relief valve.
3
Node 2: Hydrogen absorber internal vessel with hydrogen windows.
Intent: To keep hydrogen liquid inside hydrogen absorber module.
No
Parameter
Guide
word
Cause
Consequence
Safeguards
Recommendations
1
Temperature
Lower
Too much cooling
power from the He
cooling system.
1. Pressure in the
hydrogen system
drops.
2. LH2 level in
hydrogen vessel
rises.
Pressure gauge to
trigger an alarm.
Implement an active
pressure gauge.
Liquid hydrogen
level meter to trigger
an alarm.
Implement an active
liquid level meter.
2
Temperature
Higher
1. Not enough
cooling power from the
He cooling system.
2. Power cut.
1. Liquid
hydrogen
evaporates and
LH2 level goes
down.
2. Pressure rises.
Pressure gauge to
trigger an alarm.
Liquid hydrogen
level meter to trigger
an alarm.
Implement an active
pressure gauge.
Implement an active
liquid level meter.
3
Pressure
Lower
1. Window is leaking
or broken.
2. Pipe is leaking.
3. Hydrogen tanks is
leaking.
1. Hydrogen leaks
into vacuum vessel.
2. Hydrogen is
leaking out.
Hydrogen detector
to trigger an alarm.
Hydrogen ventilation
system collects and
vents hydrogen out.
Implement an active
hydrogen detector.
4
Pressure
Higher
Temperature is
increased.
Windows can
break.
Pressure relief valve
to dump hydrogen
into a buffer tank
Implement a pressure
relief valve and a
buffer tank.
4
Node 3: Hydrogen absorber vacuum jacket with safety windows.
Intent: - To insulate thermally the internal hydrogen vessel .
- To provide additional barrier for air .
No
Parameter
Guide word
Cause
Consequence
Safeguards
1
Pressure
Higher
Hydrogen window
broken
Vacuum pump
failure
Hydrogen
bursts into
vacuum jacket
Pressure relief valve to
dump hydrogen into
buffer tank
MICE Absorber working group meeting @ Columbia, 13 June 2003
Recommendations
5
Node 4: Buffer tank.
Intent: To quickly relief pressure in the absorber module in case of window burst .
No
Parameter
Guide word
Cause
1
Pressure
Higher
Hydrogen comes
from absorber module
Vacuum pump
failure
MICE Absorber working group meeting @ Columbia, 13 June 2003
Consequence
Safeguards
Recommendations
Pressure relief valve to
dump hydrogen outside
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Node 5: Hydrogen module enclosure.
Intent: To localize and vent hydrogen in case of hydrogen leak .
No
Parameter
Guide word
Cause
Consequence
Safeguards
Recommendations
1
Hydrogen
concentration
Higher
Hydrogen leaks
out absorber module
Hydrogen leaks
out hydrogen pipes
Explosive
oxygenhydrogen
mixture can be
formed
Ventilation system to
quickly vent hydrogen
out.
Hydrogen detector to
trigger an alarm and to
start a high rate mode for
the ventilation system.
Implement ventilation
system equipped with
hydrogen detector.
MICE Absorber working group meeting @ Columbia, 13 June 2003
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