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Funded by FCH JU (Grant agreement No. 256823) 1 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 1.

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Presentation on theme: "Funded by FCH JU (Grant agreement No. 256823) 1 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 1."— Presentation transcript:

1 Funded by FCH JU (Grant agreement No ) 1 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 1

2 Funded by FCH JU (Grant agreement No ) 2 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 2 Hydrogen can be produced either by water electrolysis using electricity or by steam reforming of natural gas. After purification and compression, hydrogen is then delivered by pipe or in transportable containers or trailers if not directly produced on site. Electrolysers are systems producing hydrogen from water and electricity. The hydrogen gas produced using electrolysis technology can then be utilized immediately or stored for later use. As of today, electrolysers are most often used in industrial applications; most of them have small to medium capacities (production of hydrogen smaller than 500 Nm 3 /h), but also very large installations exist, producing more than m3/h. Electrolysers can be easily regulated and do not emit anything else than O 2 and H 2. They can produce very pure hydrogen at elevated pressures. Reformers are systems producing hydrogen from natural gas, from steam and heat. They are most often used in industrial applications; their capacity ranges from a few hundred to more than Nm 3 /h. Reformers are operated 24/7 at constant load and do emit CO 2. The produced hydrogen is not very clean and at atmospheric pressure.

3 Funded by FCH JU (Grant agreement No ) 3 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 3 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.

4 Funded by FCH JU (Grant agreement No ) 4 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 4 Alkaline electrolysis : it is the technology which is most often used in industrial applications. The electrolyte is a potassium hydroxide solution. The operating temperature ranges from 60 to 100°C and the operating pressure ranges from 1 to 30 bar. As their operating pressure is low, alkaline electrolysers take a lot of space. Their efficiency is around 65%. Figure 128: Electrolyser developed by Norsk Hydro

5 Funded by FCH JU (Grant agreement No ) 5 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 5 The key component of the electrolysers is its membrane – electrode system. The membrane is made of polymer, and the electrodes use catalysts madeof porous precious metals. At the anode, the water feed is broken down in oxygen, electrons and protons. Protons migrate through the membrane to the cathode, where they are reduced in hydrogen molecules, while electrons migrate via the external circuit to the cathode where they combine with protons. Membranes show good chemical stability, mechanical resistance, protons conductivity, and gas separation. The main advantage of PEM electrolysers is that they can operate under load changes conditions and under high resistance). On the other hand, the costs of the electrolyte and of the electro catalysts are high. Figure 129: PEM electrolyser

6 Funded by FCH JU (Grant agreement No ) 6 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 6 Hazardous situations Prevention or mitigation measures Loss of segregation within system of H 2 and O 2 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 O 2 in H 2 Formation of flammable mixture in container due to a H 2 leak Permanent ventilation and H 2 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 leaksQuality of assembly, periodic inspection

7 Funded by FCH JU (Grant agreement No ) 7 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 7 ISO :2008 Hydrogen generators using water electrolysis process Part 1: Industrial and commercial applications, Edition 1 ISO Hydrogen generators using water electrolysis process Part 2: Residential applications, Edition 1

8 Funded by FCH JU (Grant agreement No ) 8 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 8 In a first step, about 2% of hydrogen is added in the natural gas. This process gas is then pre-heated to 350°C. As the natural gas contains sulphurated impurities, a desulphurization step is required. The desulphurated process gas is then mixed with steam and pre-heated to about 500°C. The reformer is a cylindrical vertical oven. The process gas flows down the oven through the reforming tubes filled with catalyst. Catalytic reactions produce syngas (mix of hydrogen, carbon monoxide, carbon dioxide; some water and methane from the process gas remain in the syngas). The reactions producing hydrogen are: CH 4 + H 2 O → CO + 3H 2 CO + H 2 O → CO 2 + H 2 Steam methane reforming reaction is very endothermic. The syngas flowing out the reforming tubes at the bottom of the oven has a temperature of about 850°C. It is then cooled down to about 350°C, and flows through a carbon monoxide converter where a catalytic reaction produces hydrogen and carbon dioxide from water and carbon monoxide. The gas is cooled down to 35°C ; remaining steam is condensed. The gas leaving the cooling device contains mostly hydrogen (more than 70%), and some impurities (mostly carbon dioxide) which are removed in a purification unit.

9 Funded by FCH JU (Grant agreement No ) 9 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 9 Figure 131: Steam methane reforming

10 Funded by FCH JU (Grant agreement No ) 10 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 10 The main elements which should be considered when assessing the safety of reformer units are the burner, its flame and the combustion quality, the reforming tubes and the steam production unit. The main hazards for the burner, its flame and the combustion quality are :  An explosive atmosphere might be ignited by the burner  An increase of the flame temperature and thus an increase of the temperature of the gases would damage the materials of the oven and of the reforming tubes.  An incomplete combustion of gases in the combustion chamber would lead to the formation of deposits in the exchangers, and the composition of the flue gases would not be in compliance with the composition specified in the standards. The main hazard for the reforming tubes is the formation of a leak on these tubes because of an early ageing of the reforming tubes. This could be caused by an inhomogeneous distribution of the process gas and of the heat between the reforming tubes, which would lead to an inhomogeneous distribution of the temperatures on these tubes and thus to their early ageing. The main hazard for the steam production unit is an abnormal pressure increase.

11 Funded by FCH JU (Grant agreement No ) 11 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 11 ISO :2007 Hydrogen generators using fuel processing technologies Part 1: Safety, Edition 1 Scope: packaged, self-contained or factory matched hydrogen generation systems with a capacity of less than 400 m3/h at 0 °C and 101,325 kPa This part of ISO is applicable to stationary hydrogen generators intended for indoor and outdoor commercial, industrial, light industrial and residential use. It 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. NOTE A list of significant hazards and hazardous situations dealt with in this part of ISO is found in Annex A. This part of ISO is a product safety standard suitable for conformity assessment as stated in IEC Guide 104, ISO/IEC Guide 51 and ISO/IEC Guide 7.

12 Funded by FCH JU (Grant agreement No ) 12 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 12 Hydrogen tranport by pipelines has been used for many years for supply to very large consumers, such as refineries. Compressed hydrogen is fed in metallic pipelines, which are either above-ground piping systems or underground piping systems. In the case of underground piping systems, hydrogen pipe is run in an open trench covered by a grating. Most of the pipes used in hydrogen installations are made of stainless steel. Pipes are not made of plastic, or of any metallic material which is not resistant to high temperatures. Figure 132: Hydrogen pipeline network of Air Liquide in Northern Europe

13 Funded by FCH JU (Grant agreement No ) 13 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 13 HazardSafety 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. 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 avoided. 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

14 Funded by FCH JU (Grant agreement No ) 14 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 14 For consumptions of up to a 200 Nm 3 /h, hydrogen is transported in pressurized or liquid form in transportable containers or trailers. For larger consumptions, hydrogen is produced at the site of use (by electrolysis or steam reforming). Compressed gaseous hydrogen is transported by tube trailers which consist of steel tubes or cylinders at 200 to 250 bar. A typical tube trailer has a capacity of 400 kg. This capacity can be largely increased by use of composite materials. Figure 133: Examples of compressed hydrogen tube trailers

15 Funded by FCH JU (Grant agreement No ) 15 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 15 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 timeis challenging because of its rapid evaporation in case of parasitic heat input. Tankersare insulated, and they may have large capacities exceeding L. Figure 134: Liquid hydrogen tanker

16 Funded by FCH JU (Grant agreement No ) 16 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 16 The following safety devices are used in trailers or tankers:  Safety relief valves and rupture bursting discs protect the vessels and pipes from an excessive pressure which might cause their rupture.  Safety relief valves start to open at their set pressure. They re-set when the pressure is at 90% of the set pressure.  Rupture bursting 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 vaccum interspace (between the inner vessel and the outer jacket).  Anti tow-away devices can be used to prevent the vehicle from moving when the road transport equipment control cabinet doors are open OR when a product transfer and / or vent hose is connected to the road transport equipment pipework coupling.

17 Funded by FCH JU (Grant agreement No ) 17 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 17 Road Vehicle Emergency and Recovery, IGC Doc 81/06/E, Revision of Doc 81/01, European Industrial Gases Association AISBL ISO This International Standard specifies the requirements for the design, construction, testing and initial inspection of a transportable cylinder bundle. It is applicable to cylinder bundles containing compressed gas, liquefied gas and mixtures thereof. It is also applicable to cylinder bundles for acetylene Trailers EN This European Standard specifies the requirements for the design, manufacture, identification and testing of a battery vehicle. It is applicable to battery vehicles containing compressed gas, liquefied gas and mixtures thereof. It is also applicable to battery vehicles for dissolved acetylene. This European Standard does not apply to the vehicle chassis or motive unit or to multi-element gas containers (MEGC's), pressure drums and tanks. This standard is primarily for industrial gases other than Liquefied Petroleum Gases (LPG) but may also be used for LPG. However for dedicated LPG cylinders, see standards prepared by CEN/TC 286 Liquefied petroleum gas equipment and accessories.

18 Funded by FCH JU (Grant agreement No ) 18 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 18 Hydrogen installations are usually designed to perform two functions: (i)storage of hydrogen delivered by road and (ii)(ii) distribution of hydrogen to point of use in the required condition of pressure and temperature. The storage function is typically performed in one of the following two ways: 1.Even exchange of containers : delivery and storage performed by means of transportable hydrogen containers: these are either bundles of cylinders unloaded for small hydrogen consumptions, or trailers for large hydrogen consumptions. In order to ensure continuity of supply, two hydrogen containers are connected at all times to the distribution system. The latter includes a device which switches automatically supply to the second container when the first one is depleted (i.e. when source pressure falls below a specified threshold). The supplier is informed of this switch- over and delivers a full container well before depletion of the container in use. When this occurs, the installation switches automatically to the newly delivered container and a new delivery takes place to replace the newly depleted container, and so on.

19 Funded by FCH JU (Grant agreement No ) 19 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 19 Figure 135: Block diagram for hydrogen supply from two hydrogen trailers

20 Funded by FCH JU (Grant agreement No ) 20 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE Product transfer : Hydrogen is transferred by pressure difference from the delivery trailer to a stationary hydrogen storage tank. With this mode of supply, the on-site storage pressure needs to be significantly lower than the pressure in the delivery trailer (e.g. 50 bar vs 200 bar), in order to be able to take sufficient advantage of the trailer capacity. See below for an example of flow diagram of gas transfer. Figure 136: Flow diagram for gas transfer

21 Funded by FCH JU (Grant agreement No ) 21 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 21 The main risk associated with hydrogen supply is that of tearing the high pressure flexible hoses as a consequence of moving a container that is still connected to the fixed installation. Also the flexible hose is a limited lifetime component hence requiring preventive replacement at fixed time intervals. The following safety measures are implemented:  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

22 Funded by FCH JU (Grant agreement No ) 22 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 22 H 2 supply system Installation: ISO/DIS 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 : Gaseous hydrogen. Cylinders and tubes for stationary storage


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