MICE Hydrogen System
Tom Bradshaw
Yury Ivanyushenkov
Elwyn Baynham
Meeting October 2004 – Coseners House
Baseline layout
High level vent
High level vent
Non return
valve
Vent manifold
0.1 bar
Hydrogen zone 2
Vent
outside
flame
arrester
Vent manifold
H2Detector
Extract hood
VP2
PV8
P
P1
PV7
P
PV2
Buffer
3
vessel 1 m
Hydrogen
supply
P
P
PV1
Metal Hydride
storage unit
(20m3 capacity)
1 bar
Tbed
PV3
PV4
Fill valve
P
HV1
Coolant
Out In
P2
P
0.5 bar
0.9 bar
P
P
P
P3
P
HV2
Purge valve
P
H2 Detector
Safety window
Purge valve
HV3
Absorber window
Nitrogen
supply
0.9 bar
PV6
Helium
supply
0.5 bar
VP1
P
Pressure
gauge
P
Pressure
regulator
Valve
Pressure
relief valve
Non-return
valve
Bursting disk
VP
Vacuum pump
Chiller/He
ater Unit
Hydride bed
•Tanks need to be horizontal
•Air ingress reduces capacity and oxidises material –
oxidation rate is low.
•Alloy will become flammable after activation but it
needs an ignition source.
Checked that there are
no safety issues if
there is a catastrophic
ingress of air.
Activation procedure:
a)
Pump out absorber
b)
Heat to 60-80C
c)
Add H2 to about 1.2 bar
d)
Leave to soak for 8 hours
Hydride Bed
Black lines absorbtion
Dotted lines desorbtion
Hydride Characteristics
Hydrogen Pressure
(MPa)
17℃
100
30℃
0.12MPa
10-1
10℃
-10℃
10-2
0
50
100
150
200
Hydrogen Content (cc/g)
20l liquid = 16,000 normal litres gas – will absorb this in under 4 hours
Specification for the Hydride Bed
Hydrogen Storage Capacity
Tank number/system
20 Nm3
1
Tank Description:
Heat Transfer Medium
Water
MH Weight
155kg
Tank Structure
Dimensions
Charging Gas Component
Hydrogen of 99.99% purity
Charging Gas Pressure
1.2 barA
Hydrogen Charging Rate
70NL/min (up to 90% of Storage Capacity)
Discharging Gas Pressure
1.2 barA
Hydrogen Discharging Rate
70NL/min
(up to 90% of Storage Capacity)
Shell & Tube type
φ216.3×L1600（mm）
( not include attachments )
Tank Total Weight
Operating Condition:
Utility Requirements:
Cooling Medium
Water
Below -10℃ （At 20L/min）
220 Kg
Heating Medium
Above 20℃ （At 20L/min）
Design Code
AD Merkblaetter
Certification
Declaration of Conformity to Pressure Equipment Directive
97/23/EC Certified by a Notified Body）
Buffer vol pressure rise
2
350
1.8
Effectiveness of Buffer Volume
300
1.6
Latent heat
446000
J/kg
pressure Pa
Expected boil-off
rate
1.2
200
1
150
0.8
0.6
Power into liquid
10179
W
Hydrogen boiled off
(kg/s)
0.0228
23
kg/s
100
0.4
50
0.2
0
Start mass of liquid
Liquid density
Start pressure (bar)
1.544
kg
temperature
250
1.4
0
0
5
10
15
20
tim e secs
70.288
0.5
•Assumes mixing of gas - cold from absorber + buffer volume
Rgas
dt
Buffer vol
density 300K
4157
•Temp in buffer calc on basis of constant Cv - this is optimistic for Tgas ~50K but
pretty good for Tgas >100K
0.2
1
0.08
m^3
kg/m^
3
relief valve pressure
1.60E+
05
Pa
outlet mass flow
1.20E02
kg/s
•For large outflow through relief valve the algorithm is not correct because the valve
essentially shuts
•Buffer volume gives a huge safety margin over just the pipe system with vol ~
0.1m^3 for 50m of 50mm dia pipe
•The buffer vessel will keep the gas warmer due to its thermal mass - this is not
included - it will increase the pressure rise
•Typically with 1m^3 Tgas ~100K pressure rise rate is 0.1 bar/sec valve opening time
of 0.1-0.2 sec would be OK
Pressure relief valves
Tyco (Crosby) valves – key points:
•Pilot valves – quick acting
•3% tolerance on set pressure
•Closes at 95% of set pressure
•Response time is <0.5s
•Valves re-seat on elastomers
•91&94 valves usable to 20K (although situated at
RT)
They also manufacture
bursting discs and flame
arrestors
Feel confident that we have a solution for this.
R&D Process
•Next steps are to design layouts in
the hall, pipework – test area
•Installation of venting system
Issue of the test area is
still not finalised – is it
sensible to test while other
work is going on ? May
have to make a safety case
or find somewhere else.
•Design and order cryostat and
cryocooler
•Order hydride bed
•Pressure relief valves
•Control system
We will be using a cryocooler and perform tests on
the control system,condensation rate etc…
Main issue is what will the
funding profile allow ?……
Safety Review Process
END
SourceD:\MICE\Cryogenics\HydrogenSystem\[Pressure rise buffer.xls]press buffer-2