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