Post on 24-Dec-2015
MICE Hydrogen System
Tom Bradshaw
Yury Ivanyushenkov
Elwyn Baynham
Meeting October 2004 – Coseners House
Baseline layout
Pressuregauge
Non-returnvalve
-P P VP Vacuum pumpBursting diskPressure
relief valveValvePressure
CoolantOut In
Metal Hydride storage unit
(20m3 capacity)
Purge valve
0.5 bar
0.9 bar
H2 Detector
P
P
VP1
VP2
Purge valve
Chiller/Heater Unit
1 bar
PP
0.5 bar
0.9 bar Helium supply
Hydrogen supply
High level vent
Buffer vessel
Vent outsideflame arrester
Extract hoodH2Detector
PP
Nitrogen supply
PP
PP
1 m3
Hydrogen zone 2
Vent manifold Vent manifold
P1
PV1
PV7
PV8
PV2
PV3
PV4
HV1
Fill valve
Tbed
HV2
HV3
P3
P
P2
PV6
High level vent
Non returnvalve
0.1 bar
-P P VP Vacuum pumpBursting diskPressure
relief valveValvePressure
regulator
CoolantOut In
Absorber window
Metal Hydride storage unit
(20m3 capacity)
Purge valve
0.5 bar
0.9 bar
H2 DetectorH2 Detector
P
P
VP1
VP2
Purge valve
Chiller/Heater Unit
1 bar
PP
0.5 bar
0.9 bar Helium supply
Hydrogen supply
High level vent
Buffer vessel
Vent outsideflame arrester
Extract hoodH2DetectorH2Detector
PP
Nitrogen supply
PP
PP
1 m3
Hydrogen zone 2
Vent manifold Vent manifold
P1
PV1
PV7
PV8
PV2
PV3
PV4
HV1
Fill valve
Tbed
HV2
HV3
P3
P
P2
PV6
High level vent
Non returnvalve
0.1 bar
Safety window
Hydride bed
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
•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.
Hydride Bed Black lines absorbtion
Dotted lines desorbtion
20l liquid = 16,000 normal litres gas – will absorb this in under 4 hours
Hydride Characteristics
0 50 100 150 20010-2
10-1
100
17℃
10℃
0.12MPa
-10℃
30℃
Hydr
ogen
Pre
ssur
e (
MPa)
Hydrogen Content (cc/g)
Specification for the Hydride Bed
Hydrogen Storage Capacity 20 Nm3
Tank number/system 1
Tank Description:
Heat Transfer Medium Water
MH Weight 155kg
Tank Structure Shell & Tube type
Dimensions φ216.3×L1600 ( mm )
( not include attachments )
Tank Total Weight 220 Kg
Operating Condition:
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)
Utility Requirements:
Cooling Medium Water
Below -10 ℃ ( At 20L/min )
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 )
Effectiveness of Buffer Volume
•Assumes mixing of gas - cold from absorber + buffer volume
•Temp in buffer calc on basis of constant Cv - this is optimistic for Tgas ~50K but pretty good for Tgas >100K
•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
Buffer vol pressure rise
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0 5 10 15 20
time secs
pre
ssu
re P
a
0
50
100
150
200
250
300
350
tem
per
atu
reExpected boil-off rate
Latent heat 446000 J/kg
Power into liquid 10179 W
Hydrogen boiled off (kg/s)
0.022823 kg/s
Start mass of liquid 1.544 kg
Liquid density 70.288
Start pressure (bar) 0.5
Rgas 4157
dt 0.2
Buffer vol 1 m^3
density 300K 0.08kg/m^3
relief valve pressure1.60E+
05 Pa
outlet mass flow1.20E-
02 kg/s
Pressure relief valves
They also manufacture bursting discs and flame arrestors
Feel confident that we have a solution for this.
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)
R&D Process
Main issue is what will the funding profile allow ?……
We will be using a cryocooler and perform tests on the control system,condensation rate etc…
•Next steps are to design layouts in the hall, pipework – test area
•Installation of venting system
•Design and order cryostat and cryocooler
•Order hydride bed
•Pressure relief valves
•Control 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.
Safety Review Process
END
SourceD:\MICE\Cryogenics\HydrogenSystem\[Pressure rise buffer.xls]press buffer-2