funded by fch ju (grant agreement no. 256823)...2014/06/11 · iso 16110-1:2007 hydrogen generators...

Funded by FCH JU (Grant agreement No. 256823)

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© HyFacts Project 2012/13

CONFIDENTIAL – NOT FOR PUBLIC USE

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Hydrogen can be produced by

- water electrolysis using electricity

- steam reforming of natural gas

Delivery by

- transportable containers

- trailers

- pipeline

Electrolyser

Electricity (e-)

Water (H2O)

Hydrogen (H2)

Oxygen (O2)

Reformer

Natural Gas (CH4)

Steam (H2O)

Hydrogen (H2)

Carbon Dioxide (CO2)


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Electrolysers:

- producing hydrogen and oxygen from water and (green) electricity

- for immediate or later use

- most often used in industrial applications

- scalable size (0,1 to 20.000 m3/h)

- can be easily regulated from 0 to 100 %

- relatively short start up time (minutes)

- produce very pure hydrogen at elevated pressures (1 to 30 bar)


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Reformers:

- producing hydrogen from natural gas, steam and heat.


- capacity ranges from a few hundred to more than 100 000 Nm3/h

- operated 24/7 at constant load

- relatively long start up time (days)

- emit CO2

- produced hydrogen is not very clean and at atmospheric pressure


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In an electrolyser cell, electricity causes dissociation of water into hydrogen and oxygen

molecules. An electric current is passed between two electrodes separated by a conductive

electrolyte or “ion transport medium”, producing hydrogen at the negative electrode (cathode)

and oxygen at the positive electrode (anode).

Two main technologies of electrolysers exist:

electrolysers based on the

- Alkaline electrolysis process and electrolysers based on the

- PEM (Proton Exchange Membrane) electrolysis process.

Their technical maturities, their operating temperatures and their electrolytes are different.


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Alkaline electrolysis:


- electrolyte is a potassium hydroxide solution (KOH)

- operating temperature ranges from 60 to 100°C

- operating pressure ranges from 1 to 30 bar

- relatively bulky systems

- efficiency is around 65%.

Figure 128: Electrolyser developed by Norsk Hydro


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PEM electrolysis:

- key component is the membrane (polymer) – electrode (catalyst) system

- anode: water is broken down in oxygen, electrons and protons

- protons: migrate through the membrane

- cathode: protons are reduced in hydrogen molecules

- electrons: migrate via the external circuit to the cathode

- membrane: good chemical stability, mechanical resistance, protons conductivity, gas separation

- advantages of PEM electrolysers: load changes don’t have much influence on lifetime, high pressure

- disadvantage: high costs of the electrolyte and electro catalysts

- still at development stage

Figure 129: PEM electrolyser


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Hazardous situations

Prevention or mitigation

measures Loss of segregation within system of H2 and O2 produced –

process pressure is an aggravating factor as this increases

amount of reactants in the system and burst pressure of

equipment

Process reliability and detection

of O2 in H2

Formation of flammable mixture in container due to a H2 leak

Permanent ventilation and H2

detection Fire due to failure/overheating of high current electrical

components

Electrical safety, fire detection

In case of liquid electrolyte: short circuit from electrolyte leaks

Quality of assembly, periodic

inspection In case of liquid electrolyte: corrosive electrolyte leaks

Quality of assembly, periodic

inspection


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9 ISO 22734-1:2008 Hydrogen generators using water electrolysis process

Part 1: Industrial and commercial applications, Edition 1

ISO 22734-2 Hydrogen generators using water electrolysis process

Part 2: Residential applications, Edition 1


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- 2% of hydrogen is added in the natural gas

- pre-heating to 350°C

- desulphurization

- process gas is mixed with steam

- pre-heating to about 500°C

- process gas flows through the reforming tubes filled with catalyst

- Catalytic reactions produces syngas (H2, CO, CO2, H2O, CH4).

The reactions producing hydrogen are: CH4 + H2O → CO + 3H2

CO + H2O → CO2 + H2

- steam methane reforming reaction is very endothermic

- syngas has a temperature of 850°C

- then cooled down to about 350°C

- flows through a CO converter

- catalytic reaction produces H2 and CO2 from H2O and CO

- cooling down to 35°C

- condensation of remaining steam

- raw hydrogen concentration is more than 70% with some impurities (mostly CO2)

- removal of impurities in a purification unit


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Figure 131: Steam methane reforming


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Units to be considered during safety assessment:

burner, its flame and the combustion quality, the reforming tubes and steam production unit.

explosive atmosphere might be ignited by the burner

increase of flame and gas temperature would damage materials of the reforming tubes.

incomplete combustion of gases leads to formation of deposits in the exchangers

Main hazard for the reforming tubes is the formation of a leak on these tubes because

of an early ageing of the reforming tubes.

The main hazard for the steam production unit is an abnormal pressure increase.


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ISO 16110-1:2007 Hydrogen generators using fuel processing technologies

Part 1: Safety, Edition 1

Applicable to stationary hydrogen generators intended for indoor and outdoor commercial,

industrial, light industrial and residential use with a capacity of less than 400 m3/h .

Aims to cover all significant hazards, hazardous situations and events relevant to

hydrogen generators, with the exception of those associated with environmental compatibility

(installation conditions), when they are used as intended and under the conditions foreseen

by the manufacturer.

A list of significant hazards and hazardous situations dealt with in this part of ISO 16110

is found in Annex A.

This part of ISO 16110 is a product safety standard suitable for conformity assessment as

stated in IEC Guide 104, ISO/IEC Guide 51 and ISO/IEC Guide 7.


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Hydrogen transport to / from refineries.

Compressed hydrogen transport in metallic pipelines.

Above-ground piping systems or

underground piping systems (open trench and/or cathodic protection).

Material: stainless steel

12 networks worldwide

F/Be/NL: 810 km (100 bar)

Germany : 240 km (200 bar)

Rotterdam

Dordrecht

RheinbergMarl

Dortmund

Herne

Düsseldorf

Leverkussen

Germany

Duisburg

Krefeld

Geelen

Genk

Antwerp

Zeebrugge

Ghent

LilleMons

Brussels

Charleroi

Liège

Maubeuge

Dunkerque

France

Belgium

Netherlands

Hydrogen Pipelines

Figure 132: Hydrogen

pipeline network of

Air Liquide in

Northern Europe


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Hazard

Safety measures

Rupture of pipes and fittings because

of hydrogen embrittlement

Hydrogen compatible materials should be chosen.

Corrosion for underground piping

Piping must be externally coated to an approved specification, to protect against

soil corrosion by cathodic protection. Rupture of the pipe material due to

lightning strikes or ground fault

conditions

Electrical continuity between underground hydrogen piping and above ground

piping, or other metal structures, should be adhered.

All above-ground pipelines shall have electrical continuity across all connections,

except insulating flanges, and shall be earthed at suitable intervals to protect

against the effects of lightning and static electricity Rupture due to external forces

Piping should not be exposed to external forces which can cause a failure or

dangerous situation. The main cause of pipe rupture is attack by external

operation (e.g. when a mechanical digger knocks on a pipe). Hazards specific to underground

piping

It is preferable to have no flanged or other mechanical joints underground.

Only gaseous hydrogen pipes with welded joints may be buried.

Table 41: Safety measures for pipes


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Consumptions of up to a 200 Nm3/h:

CGH2 in transportable containers or trailers

Larger consumptions: hydrogen production at the site of use

Figure 133: Examples of compressed hydrogen tube trailers


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In order to increase its density, hydrogen may be liquefied and transported by

liquid hydrogen tankers. However, storing liquid hydrogen over a long period

of time is challenging because of its rapid evaporation in case of parasitic heat input.

Tankers are insulated, and they may have large capacities exceeding 60 000L.

Figure 134: Liquid hydrogen tanker


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Safety devices of trailers or tankers:

Safety relief valves and burst discs protect the vessels from an excessive pressure

Safety relief valves start to open at their set pressure.

They re-set when the pressure is at 90% of the set pressure.

burst discs are metal foil discs which are designed to rupture at a set

pressure. They do not re-set once they have burst.

Emergency valves prevent any loss of hydrogen in case of pipes failures, or in case of an accident

during the trailer / tanker filling or discharge.

Vacuum safety devices protect the outer jacket from bursting and / or the inner vessel from

collapsing in the case of a product leak into the vacuum interspace

Anti tow-away devices to prevent the vehicle from moving when the cabin’s doors are open OR

when a product transfer and / or vent hose is connected to the road transport equipment pipework

coupling.


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IGC Doc 81/06/E: Road Vehicle Emergency and Recovery, Revision of Doc 81/01,

European Industrial Gases Association AISBL

ISO 10961 specifies the requirements for the design, construction, testing and initial inspection

of a transportable cylinder bundle.

Trailers EN 13807

This European Standard specifies the requirements for the design, manufacture, identification

and testing of a battery vehicle.

ADR: Accord European Relatif au Transport International du Merchandis Dangereuses par Route

European Agreement concerning the International Carriage of Dangerous Goods by Road


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Hydrogen installations usually

(i) store hydrogen delivered by road

(ii) distribute hydrogen to point of use

The storage function is typically performed in one of the following two ways:

1.Even exchange of containers:

delivery and storage in transportable hydrogen containers

To ensure continuity of supply, two hydrogen containers are connected (Fig. 135)

2. Product transfer:

Hydrogen is transferred by pressure difference from the delivery trailer to a stationary hydrogen

storage tank (Fig. 136).


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Figure 135: Block diagram for hydrogen supply from two hydrogen trailers


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Figure 136: Flow diagram for gas transfer


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Main risk:

tearing the high pressure flexible hoses by moving a container still connected to the

fixed installation.

Preventive measures:

Prevention of movement of trailers that are connected to the installation,

e.g. by locking the trailer’s brakes when the high pressure hose is connected to the trailer.

Isolation valve on the trailer located on the forward side. In case of high pressure hose

rupture, the trailer can be safely isolated in order to prevent it from being emptied


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H2 supply system Installation:

ISO/DIS 20100 clause 5.2 Gaseous hydrogen supply by tube trailers and Multi

Cylinder Packs (MCPs) and 14 Separation distances

List of all the standards of TC 58 and TC 197 relative to vessels/tanks

ISO 15399: Gaseous hydrogen. Cylinders and tubes for stationary storage

funded by fch ju (grant agreement no. 256823)...2014/06/11 · iso 16110-1:2007 hydrogen generators...

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