MICE Hydrogen System

Tom Bradshaw

Yury Ivanyushenkov

Elwyn Baynham

Collaboration Meeting RAL October 2004

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)

If we operate at constant pressure e.g. 1 atm, start at 0C and end up at 17C

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 ）

Stillwater News - Montana

•Stillwater Mine goes for a first For the first time anywhere in the world a Hydrogen powered engine is being tested in an underground mine.

•The project was to demonstrate that hydrogen could be used safely in mining. To do this hydrogen had to be stored as a solid in what is referred to as a hydride bed. In this state, tests conducted at a US Army firing range showed that even bullets, shot through the bed, would not cause a fire or explosion.

•A water-cooled Caterpillar 3304 diesel engine was modified to use hydrogen, replacing the factory installed air-cooled engine. As a hydrogen internal combustion engine, it has spark plugs with individual coils, and an engine-driven magneto to provide spark and timing. The hydrogen gas is injected into the cylinders, much as an engine converted to run on natural gas or liquid petroleum.

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)

Loss of Vacuum

•In the event of a catastrophic loss of vacuum the sequence indicated in the previous slide takes place

•In the event of a moderate vacuum leak the system pressure will rise until 1 bar is reached when the pressure relief valve to the hydrogen bed will open and the gas will be absorbed by the hydride bed without any increase in pressure.

Metal Hydride

storage unit

(20m 3 capacity)

P

VP2

Chiller /He

ater Unit

1 bar

P

P

P1

PV1

PV7

PV8

PV2

PV3

PV4

HV1

Fill valve

Tbed

Metal Hydride

storage unit

(20m 3 capacity)

P

VP2

Chiller /He

ater Unit

1 bar

P

P

P1

PV1

PV7

PV8

PV2

PV3

PV4

HV1

Fill valve

Tbed

Prototyping

Main issue is what will the funding profile allow ?……

Aim is to duplicate the absorber/cryocooler system without the windows, possibly reduced capacity.

Using a cryocooler we will perform tests on the control system,condensation rate etc…

We are developing a prototype control system logic

•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

Conclusions

We have made good progress on the definition of the hydrogen supply system for the absorber.

The safety issues are under control.

Need to define more carefully the development plan – recent cost review.

Test area is still a slight issue. Should be possible to start work on venting in the hall.

Need to start design work to get approvals – meet design codes head on.

Many of the critical components are defined.

END

SourceD:\MICE\Cryogenics\HydrogenSystem\[Pressure rise buffer.xls]press buffer-2