Safety and support system for fuel cell module

Abstract

Described herein is a safety and support system for a fuel cell module, the safety and support system comprising: a pressure-tight safety enclosure for enclosing the fuel cell module and for containing a fluid; a fuel supply system arranged to deliver fuel from an external source to the fuel cell module; an air supply system arranged to deliver air from an external source to the fuel cell module; an exhaust system arranged to deliver an exhaust fluid from the fuel cell module out of the safety enclosure; and a housing atmosphere system, the housing atmosphere system comprising: an inlet into the safety housing, the inlet having an inlet valve; an outlet from the safety housing, the outlet having an outlet valve; means for withdrawing fluid from the safety housing through the outlet; and a pressure sensor arranged to measure a pressure of the fluid inside the safety enclosure, where the enclosure atmosphere system is arranged to maintain the safety enclosure inside below ambient pressure. A method for preventing the occurrence of an explosive atmosphere inside a safety enclosure and a fuel cell system for marine applications are also described herein.

Description

Technical Field

[0001] The present invention relates to a safety and support system for a fuel cell module. In particular, the present invention relates to a safety and support system for a fuel cell module including a hydrogen fuel cell. Background of the Invention

[0003] A fuel cell is an electrochemical device that converts chemical energy produced by a reaction directly into electrical energy. For example, a fuel cell includes a proton exchange membrane (PEM), commonly called a polymer electrolyte membrane, which only allows protons to pass between the anode and cathode of the fuel cell. At the anode, diatomic hydrogen (fuel) reacts to produce hydrogen protons that pass through the PEM. The electrons produced by this reaction pass through a circuit system outside the fuel cell to provide an electric current. At the cathode, oxygen is reduced and reacts with the hydrogen protons to form water. The anode and cathode reactions are described by the following equations:

[0004] H2→2H + +2e - at the anode of the battery, and

[0005] O2+4H + +4e - → 2H2O is at the cathode of the battery.

[0006] Since a single fuel cell typically produces a relatively small voltage (e.g., about 1 volt), several fuel cells can be combined to form an arrangement called a fuel cell stack to produce a higher voltage. A fuel cell stack may include a plate (e.g., a graphite composite or metal plate) stacked one above the other, and each plate may be associated with more than one fuel cell in the stack. The plate may include various channels and orifices, for example, for guiding reactants and products through the fuel cell stack. Several PEMs (each PEM associated with a specific fuel cell) may be dispersed throughout the stack, between the anodes and cathodes of different fuel cells.

[0007] The fuel cell stack, local control unit and core components necessary for power generation are usually arranged in a fuel cell module. Such fuel cell modules are usually based on components of fuel cell systems used in automobiles. These components, which may be located at spaced locations inside a fuel cell vehicle / car, can be arranged in a compact module for other applications and are available for commercial use.

[0008] Hydrogen (H2) in particular is a very light gas and a very small molecule, making it challenging to contain inside any system. Leaks can easily occur, and hydrogen tends to diffuse from any system using it into the surrounding environment.

[0009] In a fuel cell module, such as the one described above, small amounts of fuel (in some cases hydrogen) can leak into the surroundings over time. Typically in fuel cell applications, such as in a hydrogen car, such small amounts of fuel are diluted into the ambient air, where they can form an explosive mixture with oxygen. This is possible because the fuel cell module is arranged in a well-ventilated compartment and the car is used outdoors.

[0010] The use of hydrogen as a fuel has become increasingly common in recent years. More recently, the use of fuel cells has also been seen as a step towards decarbonizing maritime transport. However, there are still some challenges that need to be addressed before fuel cell technology can be widely used on ships and other ocean-going vessels.

[0011] An important difference between installing a fuel cell on a ship and installing it in a car is that the fuel cell may need to be installed in a confined space below the deck. Therefore, any leakage of fuel (such as flammable hydrogen) may cause an explosive atmosphere in the confined space. In the automotive industry, the safety concept of avoiding explosive atmospheres is to let the surrounding air flow outside the fuel cell components so that any hydrogen leaks will diffuse before the concentration reaches an explosive atmosphere. This concept does not apply to ships, but to cars, because the systems on ships are larger (therefore, more hydrogen tends to leak out), and they may be placed in a confined space, which will require a large number of forced ventilation systems, thereby reducing the efficiency of the entire system.

[0012] Similar challenges exist in other types of fuel cells and will apply to fuel cells that use hydrogen as a fuel, such as PEM fuel cells, alkaline fuel cells, solid oxide fuel cells, and fuel cells for other types of fuels, such as natural gas fuel cells, ammonia fuel cells, and methanol fuel cells. Prior art

[0013] WO0159861A2 discloses a fuel cell system, which includes a fuel cell stack, an enclosure that accommodates the fuel cell stack, and a blower. The blower is located inside the enclosure and is suitable for extracting air from the inside of the enclosure to generate an air flow through the fuel cell stack and establish a negative pressure inside the enclosure relative to the area outside the enclosure. The air sucked into the enclosure passes through a filter. The filter introduces a pressure drop that generates a negative pressure inside the enclosure. As long as the blower draws air out of the enclosure, the negative pressure can be maintained.

[0014] JP2005268054A discloses a solution for suppressing abnormal conditions in a fuel cell system, the purpose of which is to provide a solution that is compact and can be used in vehicles. Abnormal conditions are suppressed by displacing oxygen so that the oxygen concentration is too low to prevent fire from occurring. The document states that instead of providing an inert gas to displace oxygen, which would make the system bulky and heavy, hydrogen or cooling water is used to displace oxygen. In any case, hydrogen and cooling water are necessary to fuel the battery to operate. This system for displacing oxygen does not add much weight or volume to the fuel cell system. Therefore, the fuel cell system can remain compact while being able to suppress abnormal conditions.

[0015] JP2009046128A discloses a heat-insulating container, at least a portion of the container shell of the heat-insulating container is equipped with a surface variable mechanism, which switches the surface of the container shell between a flat surface state and a slightly uneven surface state. The container can accommodate a fuel cell, and the fuel cell generates heat during operation. The amount of heat generated by the fuel cell depends on the operating load. The problem to be solved by the container is to control heat insulation and heat dissipation according to the heat generation inside the container.

[0016] Purpose of the Invention

[0017] It is an object of the present invention to provide a safety and support system for a standard fuel cell module which prevents the formation of an explosive atmosphere around the fuel cell module, ie prevents an explosive mixture of fuel and oxygen, in particular when hydrogen is used as fuel.

[0018] Another object of the present invention is to enhance the ability to detect leaks or abnormal conditions that could cause a fuel cell to develop an explosive atmosphere (e.g., a mixture of hydrogen and oxygen when hydrogen is used as the fuel and air is fed into the cell).

[0019] A further object of the present invention is to provide an enclosure with a safety and support system which makes a standard industrial fuel cell module, usually intended for use in an air-ventilated environment, suitable for use on board a ship where it is accommodated in a confined space, such as in a machinery room below deck. This will in particular be done to prevent the formation of an explosive atmosphere in said confined space. Summary of the invention

[0020] A first aspect of the present invention relates to a safety and support system for a fuel cell module. The system comprises:

[0021] a pressure-tight containment enclosure for enclosing the fuel cell module and for containing a fluid in a space between the fuel cell module and the containment enclosure,

[0022] a fuel supply system arranged to deliver fuel to the fuel cell module from an external source located outside the containment enclosure,

[0023] - an air supply system arranged to deliver air to the fuel cell module from an external source located outside the containment enclosure,

[0024] an exhaust system arranged to convey exhaust fluid from the fuel cell module out of the containment enclosure in isolation from the space between the fuel cell module and the containment enclosure, and

[0025] - a housing atmosphere system, the housing atmosphere system comprising:

[0026] - an outlet from the containment enclosure, the outlet having an outlet valve,

[0027] an inlet having an inlet valve for controlling the intake of fluid into the containment enclosure (ie into the space between the fuel cell module and the containment enclosure)

[0028] - means for extracting fluid from said containment vessel through said outlet, and

[0029] - a pressure sensor arranged to measure the pressure of the fluid inside the containment vessel,

[0030] The containment atmosphere system is arranged to maintain the fluid inside the containment enclosure at a pressure below ambient pressure.

[0031] In an embodiment, the fuel is hydrogen.

[0032] In an embodiment, the fluid is a gas, which preferably includes an inert gas. The fluid may also be a liquid. The device for extracting the fluid may be a device such as a vacuum pump, a blower or a compressor. The device is arranged to suck out the fluid from the atmosphere inside the safety enclosure (i.e., a space filled with fluid (most commonly filled with gas or mainly filled with gas) between the components of the fuel cell module and the interior of the safety enclosure). The device may be arranged downstream of the outlet valve.

[0033] "Pressure-tight" means that the containment enclosure can maintain the pressure of the fluid in the space between the components of the fuel cell module and the interior of the containment enclosure. Air and fuel flow into the components of the fluid battery module via tubes through the containment enclosure, and exhaust flows out of the fluid battery module via tubes through the containment enclosure, but these flows are isolated from the space between the components of the fuel cell module and the inner surface of the containment enclosure, except for small amounts of leakage and / or diffusion from the components of the fuel cell module into the space.

[0034] The control system can control the opening and closing of the inlet valve, the outlet valve and the device for extracting air. The control system can also receive measurement results from the pressure sensor.

[0035] The sub-ambient pressure inside the containment vessel may be a pressure below ambient pressure (approximately 1 bar), preferably 0.7 bar to 0.9 bar, and most preferably 0.8 bar.

[0036] One advantage of maintaining the interior of the containment vessel at a pressure below ambient is that if an explosion occurs, the explosion will be initiated at a lower initial pressure inside the containment vessel than outside the containment vessel. Thus, the pressure will need to increase more before the pressure differential relative to the ambient / external pressure reaches the burst pressure of the containment vessel than would be required for an explosion initiated in the same containment vessel at an internal pressure equal to or greater than the ambient / external pressure.

[0037] Maintaining a sub-ambient pressure inside the containment vessel also has the advantage that leaks can be more easily detected by pressure sensors. All potential leaking fluid sources are at a pressure higher than the sub-ambient pressure of the fluid inside the containment vessel. The pressure of the ambient air is higher, so a leak outside the containment vessel will be detected as an increase in pressure inside the containment vessel. The same is true for the fuel supply and air supply, which are both at a pressure higher than the sub-ambient pressure inside the containment vessel.

[0038] Compared with only one opening in the interior space of the containment vessel, the effect of having both an inlet and an outlet is that the space inside the containment vessel can be purged. Having only an outlet will allow the fluid / gas to be sucked out to reduce the pressure to below ambient, but effective purging of the interior volume is not easy.

[0039] Purging means removing the contents of a tube and / or container and replacing it with another gas or liquid, for example by sucking a new volume of gas into the containment by opening the inlet and outlet valves simultaneously and operating the means for extracting the gas from the containment until all the gas / fluid in the containment has been replaced.

[0040] The air supply system may preferably supply process air.

[0041] The enclosure atmosphere system may include an inert gas supply device for providing an inert gas atmosphere to the interior of the safety enclosure.

[0042] Filling the containment vessel with an inert gas helps prevent an explosive atmosphere from developing inside the containment vessel. For example, if only a fuel leak occurs inside the containment vessel, no oxygen will be present to produce an explosive reaction.

[0043] The inert gas supply device may be a nitrogen supply device.

[0044] The nitrogen supply device may be a nitrogen generator.

[0045] A nitrogen generator may be in fluid communication with the inlet of the containment enclosure upstream of the inlet valve.

[0046] The advantage of nitrogen is that it is a relatively cheap and commercially available inert gas. Nitrogen generators are also commercially available so that nitrogen can be generated where it is needed.

[0047] The system may include a cabinet for housing the containment enclosure. The cabinet may house and support the containment enclosure and in some cases may completely surround the containment enclosure. An inert gas supply, such as a nitrogen generator, may be arranged inside the cabinet.

[0048] When the inert gas supply is mounted inside a cabinet, the inert gas supply can be located inside or outside the safety enclosure. This provides a compact safety and support system that is easy to transport and install.

[0049] The containment enclosure may comprise a pressure relief valve arranged to release fluid from the containment enclosure when the pressure inside the containment enclosure increases above a threshold value.

[0050] The pressure relief valve can be arranged to bleed fluid from the containment vessel when the pressure increases significantly. This is an advantage if an explosion / fire occurs inside the containment vessel. In addition, the containment vessel can be purged even if the pump is not running. The fluid is then forced into the inlet and when the pressure exceeds the opening pressure of the pressure relief valve, the fluid will leave the containment vessel through the pressure relief valve.

[0051] The enclosure atmosphere system may be arranged to purge the interior of the containment enclosure. The purge may be performed periodically.

[0052] The fuel (especially if the fuel is hydrogen) and air may diffuse from the fuel cell module over time and accumulate inside the containment enclosure where the fuel mixes with the fluid therein. Over time, this may form an explosive mixture of fuel and oxygen that may ignite. The accumulation of an explosive atmosphere is avoided by periodically purging (i.e., refilling, flushing, or replacing the gas-filled volume) the internal volume of the containment enclosure. Thus, the advantage of periodically purging the containment enclosure is that the explosive atmosphere is removed and, if an inert gas such as nitrogen is used for the purge, the purge also maintains the inert atmosphere.

[0053] The outlet may be arranged at the top of the safety enclosure.

[0054] "Top of the enclosure" means the top or uppermost side of the containment enclosure when the fuel cell module is installed and the system is operating normally. The outlet is preferably located in the upper quarter of the containment enclosure, more preferably in the top panel of the containment enclosure.

[0055] Hydrogen is lighter than any other gas and therefore rises to the top of the interior of the containment vessel. Therefore, when using hydrogen as a fuel, by placing the outlet at the top of the containment vessel, it is easier to extract all of the hydrogen from the containment vessel when purging. Other fuels may also be lighter than other liquids inside the containment vessel. Therefore, when using other light fuels, arranging the outlet at the top of the containment vessel may also be beneficial.

[0056] In addition to having the outlet at the top of the safety enclosure, the inlet may also be arranged in or near the bottom of the safety enclosure. The bottom is a panel of the safety enclosure that is arranged to face downward during normal operation. The inlet is preferably located in the bottom quarter of the safety enclosure, more preferably in the bottom panel of the safety enclosure.

[0057] CFD simulations and tests have been performed on nitrogen purges in the inert gas system. These simulations show that supplying nitrogen at the bottom of the containment and extracting it at the top ensures that the inert gas volume can be exchanged so that the concentration of fuel (especially hydrogen) and oxygen is maintained at acceptable levels throughout the volume within the containment while the containment pressure remains stable. The purge volume in the containment will contain fluids such as nitrogen, diffused hydrogen and diffused air.

[0058] The fuel supply system may include a fuel supply line having a narrow contraction flow orifice, wherein a fuel pressure sensor may be arranged to detect a pressure inside the fuel supply line downstream of the narrow contraction flow orifice.

[0059] A constricted orifice is a section of a pipeline that has a smaller diameter relative to the rest of the pipeline.

[0060] Having the narrow vena contracta orifice upstream of the pressure sensor measuring the pressure inside the fuel supply line has the advantage that leaks in the fuel supply line downstream of the flow orifice are more easily detected. Upstream of the narrow vena contracta orifice, the fuel supply line can be double walled and fully welded at all connections. Inside the containment enclosure, the fuel supply preferably has a single wall. Leaks in the fuel supply line after the flow orifice will be easily detected by a loss of pressure in that portion of the fuel supply line.

[0061] The fuel cell module may be a hydrogen fuel cell module.

[0062] The hydrogen fuel cell module may use hydrogen (H2) as fuel. The hydrogen fuel cell module may include a PEM fuel cell, an alkaline fuel cell, or a solid oxide fuel cell.

[0063] The system may further comprise a cooling system arranged to transport heat from the fuel cell module out of the containment enclosure.

[0064] The cooling system may be a closed loop cooling system, and wherein the fuel concentration of the closed loop may be monitored by a coolant fuel sensor. When the fuel is hydrogen, the hydrogen concentration of the closed loop may be monitored by a coolant hydrogen sensor.

[0065] The closed loop cooling system includes a cooling fluid. The fuel, such as hydrogen, may diffuse over time through the walls of the closed loop cooling system inside the fuel cell module and accumulate in the cooling fluid. When the fuel is hydrogen, it is advantageous to be able to monitor the hydrogen level in the closed loop cooling system so that timely action can be taken if an explosive mixture of hydrogen and oxygen is formed. The coolant hydrogen sensor may be arranged in the top of an expansion tank arranged in the closed loop circuit of the cooling system.

[0066] Safety and support systems may also include:

[0067] At least one sensor selected from the list consisting of:

[0068] a temperature sensor arranged to measure the temperature inside the containment enclosure and to send the measurement result to the control unit,

[0069] - an oxygen sensor arranged to measure the oxygen level inside the containment enclosure and to send the measurement result to a control unit,

[0070] a fuel sensor arranged to measure the fuel level inside the containment vessel and to send the measurement result to the control unit, and

[0071] - a liquid level sensor arranged to measure the liquid level inside the containment enclosure and to send the measurement result to the control unit.

[0072] The fuel may be hydrogen and the fuel sensor may be a hydrogen sensor.The fuel or hydrogen level may include a fuel or hydrogen concentration.

[0073] The safety and support system may further comprise an outlet hydrogen sensor arranged outside the housing for measuring the hydrogen level in the fluid line connected to the outlet. The outlet hydrogen sensor may be arranged to send the measurement result to the control unit.

[0074] It is desirable to be able to monitor hydrogen levels inside the containment enclosure (ie, in the volume between the fuel cell module and the containment enclosure), but there are some challenges in placing a hydrogen sensor inside the containment enclosure.

[0075] One challenge is that the sensors placed inside the containment enclosure will be exposed to the high temperatures inside the containment enclosure. Due to this high temperature environment, the hydrogen sensors may malfunction or give inaccurate readings.

[0076] Another challenge is that during normal operation of the fuel cell module, small amounts of hydrogen will leak / diffuse from the fuel cell module. The hydrogen sensors placed inside the containment enclosure will be continuously exposed to this low but constant hydrogen level / concentration. Some types of hydrogen sensors will degrade or wear out if continuously exposed to such hydrogen concentrations, rendering them no longer accurate or functioning properly.

[0077] Another challenge is that some hydrogen sensors need to be calibrated periodically and they are arranged to do this automatically. In this calibration, the intention is to use the normal and very low hydrogen concentrations in the ambient air as a low reference for the hydrogen concentration. Since the hydrogen sensor inside the containment enclosure is not in contact with the ambient air, the hydrogen concentration inside the containment enclosure will be used as the low reference concentration / baseline. This approach will be successful in most cases, unless there is a slowly increasing hydrogen leak from the fuel cell module and into the space between the containment enclosure and the fuel cell module. In this case, the sensor and the accompanying controls will gradually increase the assumed low / baseline hydrogen concentration at each calibration. In other words, the calibration of the hydrogen sensor will gradually drift away and will not register a slow rise in hydrogen concentration.

[0078] Due to the above challenges, the system can be equipped with a hydrogen sensor that is not inside the containment enclosure but outside the containment enclosure. This outlet hydrogen sensor will measure the hydrogen concentration in the fluid leaving the containment enclosure, such as each time the containment enclosure is purged. An increase in the hydrogen concentration inside the containment enclosure will be reflected by an increase in the concentration in the fluid leaving the containment enclosure via the outlet.

[0079] The outlet hydrogen sensor may be arranged at any position downstream of the outlet valve, preferably between the outlet valve and the means for extracting gas from the containment vessel.

[0080] The arrangement may further accommodate a secondary fluid flow having an appropriate temperature and gas concentration, which may be advantageous in improving the durability and / or accuracy of the sensor. The secondary fluid flow may be, for example, an inert gas or ambient air. The secondary fluid flow may be arranged during a time period when gas is not being sucked out of the containment enclosure.

[0081] In a preferred embodiment, four safety enclosures (each containing a fuel cell module) are arranged in a column and share a common device for extracting gas from the safety enclosure (which device may be a vacuum pump). In such an embodiment, each safety enclosure may have an outlet valve. Therefore, the advantage of placing the outlet hydrogen sensor in this way is that a single hydrogen sensor can be used to monitor each safety enclosure. By matching the outlet valve opening period with the detection period, it is possible to detect which fuel cell module the leak originates from.

[0082] The control unit may be configured to receive measurements from at least one sensor, and the system may include:

[0083] a fuel supply shut-off valve arranged to stop supplying fuel to the fuel cell module in response to a fuel stop signal from the control unit, and

[0084] - an air stop valve arranged to stop the supply of air to the fuel cell in response to an air stop signal from the control unit.

[0085] The fuel and air shutoff valves may be located at or near a boundary or wall of the containment enclosure. Thus, when the valves are closed upon receipt of a fuel or air stop signal from the control unit, additional air and / or fuel is not only prevented from traveling to the fuel cell, but is also prevented from entering the containment enclosure, which prevents further accumulation of these substances therein.

[0086] The containment atmosphere system may be arranged to purge the interior of the containment enclosure when the level of oxygen and / or fuel inside the containment enclosure reaches a threshold value.For any of the embodiments described herein, the fuel may be hydrogen.

[0087] In another aspect, the invention relates to a method for preventing an explosive atmosphere inside a containment enclosure of a safety and support system, wherein the system comprises an inlet into the containment enclosure having an inlet valve for controlling the intake of a fluid into the containment enclosure. The method comprises performing the following steps:

[0088] - Open the inlet and outlet valves,

[0089] - operating the device for extracting gas from the containment vessel so as to extract fluid from the inlet through the interior of the containment vessel and out of the outlet,

[0090] - Close the inlet valve,

[0091] - keep the outlet valve open and continue to operate the means for extracting the gas until the pressure inside the containment vessel reaches the desired pressure below ambient, and

[0092] - Close the outlet valve and stop the operation of the device for extracting the gas.

[0093] An alternative approach is to separate the control of the inlet valve on the one hand and the control of the outlet valve and the device for extracting the gas on the other hand:

[0094] - Control of the inlet valves, with the aim of maintaining the gas composition inside the containment vessel, e.g. by opening the valves when the concentration of hydrogen or oxygen reaches a certain threshold

[0095] - Controlling the outlet valve and the means for extracting gas with the aim of maintaining the pressure inside the containment vessel, for example by opening the outlet valve and activating the means for extracting gas when the pressure reaches a certain level.

[0096] Yet another aspect of the invention relates to a fuel cell system for marine applications, wherein the system comprises a safety and support system according to the first aspect and a fuel cell module mounted inside a containment enclosure of the safety and support system.

[0097] At least two fuel cell systems may be arranged in a common cabinet for supplying electricity to the ship. The cabinet may be arranged with a common interface for connecting the at least two fuel cell systems to an external fuel source and an external air source on the ship, and the common interface for connecting the power outputs of the at least two fuel cell systems to electrical consumers on the ship. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] Embodiments of the present invention will now be described by way of example with reference to the following drawings, in which:

[0099] Figure 1 A standard industrial fuel cell module is shown.

[0100] Figure 2 A containment enclosure for housing a fuel cell module is shown.

[0101] Figure 3 A fuel cell module is shown placed in a containment enclosure. In this figure, the containment enclosure is not sealed.

[0102] Figure 4 A fuel cell module is shown positioned within a containment enclosure and a cover for the containment enclosure ready to be bolted to the remainder of the containment enclosure.

[0103] Figure 5 The security enclosure is shown with the cover secured to the remainder of the security enclosure. Figure 5 The containment enclosure (including the cover) and the fuel cell module are referred to as a fuel cell system (200) even though some of the components are not present or visible in the figure.

[0104] Figure 6 Four safety enclosures are shown, arranged in a vertical column, each of which houses a fuel cell module. Such a column may be mounted in a fuel cell cabinet, wherein air supply, fuel supply, cooling and exhaust systems may be arranged via a manifold to supply all four (or any other suitable number) of fuel cell modules. Other support and interface systems towards the ship may also be arranged so that there is only one common interface towards all fuel cell modules of the system on board.

[0105] Figure 7 The safety and support systems are shown schematically.

[0106] Figure 8 The enclosure atmosphere system associated with the safety enclosure is schematically shown.

[0107]

[0108]

[0109] DETAILED DESCRIPTION

[0110] Figure 1 A standard fuel cell module 100 is shown. In this embodiment, the fuel cell module is a hydrogen fuel cell module using hydrogen as fuel. Such a module is typically based on components of a fuel cell system used in a hydrogen car. Such a fuel cell module 100 is capable of generating approximately 80 kW of electricity. The fuel cell module needs to be supplied with air (process air as an O2 source), hydrogen (H2) and cooling water. In addition to electric current, the fuel cell module 100 also outputs process water and exhaust gas containing a small amount of hydrogen. A small amount of hydrogen will typically also leak and / or diffuse out of the fuel cell module 100. In well-ventilated areas, these small amounts of hydrogen will disperse into the ambient air and will not accumulate to form an explosive atmosphere.

[0111] To power a boat using electricity generated by a fuel cell, in most cases several standard fuel cell modules 100 will be needed, as 80kW of electricity is not much for a boat. In addition, the typical machinery space in a boat / ship is a limited space, in contrast to a car where ambient air can flow over the fuel cell components.

[0112] In order to regard the mechanical space as a gas-safe space, the fuel cell module 100 is enclosed in a safety enclosure 10, such as Figure 2 The safety enclosure shown in Figure 3 and Figure 4 In the embodiment, the fuel cell module 100 is placed in a safety enclosure 10 .

[0113] The safety enclosure 10 is part of a safety and support system 1 designed to provide the fuel cell module with fuel (hydrogen / H2), air and to ensure that the mechanical space in which the fuel cell module is installed can be considered a gas safe space. Figure 7 An embodiment of a safety and support system is schematically shown.

[0114] The main function of the safety enclosure 10 is to support the fuel cell module 100 and is a gas-tight container that can contain an inert atmosphere. The safety enclosure 10 can be designed to withstand a gas explosion inside the safety enclosure 10 and protect the surrounding environment from the effects of such an explosion. The safety enclosure is preferably made of steel, but other materials may also be used.

[0115] The containment vessel 10 may be equipped with a pressure relief valve 58. The pressure relief valve is arranged to release fluid from the containment vessel in the event of a significant increase in pressure, for example due to leakage of fluid into the containment vessel and / or explosion / combustion inside the containment vessel 10. In addition, the containment vessel may be purged even if the pump 55 is not running. The fluid is then forced into the inlet 51 and will leave the containment vessel 10 through the pressure relief valve 58 when the pressure exceeds the opening pressure of the pressure relief valve.

[0116] The safety and support system 1 is a modular system that can be adapted to support one or more fuel cell modules 100 each enclosed in a safety enclosure 10. Such a safety and support system 1 can be arranged in a cabinet 2, which supports one or more (preferably four) fuel cell modules 100. There is an auxiliary space inside the cabinet 2, which can accommodate the part of the safety and support system 1 that is not arranged in the safety enclosure 10. The cabinet 2 is open to allow ambient air 83 to flow into and out of the cabinet 2, see Figure 7 .

[0117] The safety and support system also includes a fuel supply system 20, an air supply system 30, an exhaust system 40, and a housing atmosphere gas system 50. The safety and support system may also include a control unit 60, a power distribution system 70, and sensors 11, 12, 13, 14. Figure 7 All of these subsystems can be seen schematically in .

[0118] The fuel supply system 20, air supply system 30, exhaust system 40 and enclosure atmosphere gas system 50 may be constructed to support a number of fuel cell modules 100, each of which is enclosed in a safety enclosure 10 and arranged in a cabinet 2. This may be achieved by providing manifolds for fuel, air and exhaust and adding valves to each safety enclosure 10 within the cabinet 2. The safety and support system 1 is arranged in the case of several fuel cell modules 100 so that each cabinet 2 has only one interface toward the ship (a line for supplying fuel from an external source, etc.).

[0119] Fuel supply system

[0120] The purpose of the fuel supply system 20 is to provide fuel (usually hydrogen / H2) to the fuel cell module 10. An important task is to ensure that the supply meets the required conditions in terms of flow, pressure and purity.

[0121] The inlet pressure of the fuel cell module is preferably between 5 bar and 15 bar, preferably about 9 bar. In order to prevent the inlet pressure from the external fuel storage tank (external fuel supply device) from exceeding the designed inlet pressure into the fuel cell system 200, a pressure safety valve can be placed on the fuel supply pipeline 21 from the ship.

[0122] The fuel supply system 20 may also include a narrow vena contracta orifice 22 in the fuel supply line 21, a fuel supply shut-off valve 24 downstream of the narrow vena contracta orifice 22, and a fuel pressure sensor 23 arranged downstream of the fuel supply shut-off valve 24. This arrangement is to ensure that a rupture / serious leak in the fuel line 21 downstream of the narrow vena contracta orifice 22, and in particular downstream of the valve 24 (where any rupture or damage to the pipeline will result in fuel leaking into the containment enclosure) results in a significant pressure drop after the narrow vena contracta orifice 22. This significant pressure drop can be detected by the fuel pressure sensor 23, which is arranged to measure the pressure inside the fuel supply line 21 downstream of the narrow vena contracta orifice 22. The fuel supply shut-off valve 24 may be co-located with the flow orifice at or near the boundary of the containment enclosure. In this case, any larger leak downstream of the flow orifice 22 will also typically be downstream of the fuel supply shut-off valve 24 and will be detected by the fuel pressure sensor 23 as a sharp drop in pressure.

[0123] The fuel supply line 21 is double-walled outside the safety enclosure 10, i.e., it extends all the way to the wall of the safety enclosure 10, where the fuel shut-off valve 24 is also arranged. Therefore, the fuel supply line 21' upstream of the fuel shut-off valve 24 is double-walled, so any leak in the fuel supply line 21' upstream of the fuel shut-off valve 24 will be contained within the outer wall of the double wall 25 of the fuel pipe. Leaks in the fuel line 21 downstream of the fuel shut-off valve 24 will leak into the safety enclosure 10. Serious leaks in the fuel pipe / line of the fuel cell module itself will also be detected by the pressure sensor 23.

[0124] Two double-blocking bleed valves with vents are preferably installed between the tank (external fuel source) and each cabinet to shut down the fuel cell module 100 in the event of a safety event between these valves and the safety enclosure 10 .

[0125] The fuel supply line 21' (e.g. hydrogen supply line) of each containment vessel 10 is also double-walled and fully welded to a gas-tight flange bolted to the containment vessel 10. This allows a continuous annular space to be formed between the inner and outer pipes from the double block and bleed valves to the containment vessel 10. Inside the containment vessel 10, the fuel supply line 21 may be single-walled.

[0126] When several fuel cell modules 100 are arranged in the cabinet 2, the fuel can be distributed to each fuel cell module 100 in the cabinet 2 through a manifold with separate branches. Each branch is equipped with a dedicated fuel shut-off valve 24 for each fuel cell module 100, which is arranged to ensure safe shut-off of the supply when necessary.

[0127] Air supply system

[0128] The purpose of the air supply system 30 is to provide oxygen to enable the electrochemical reaction in the fuel cell module 100. An important task of the air system 30 is to ensure that the supply device meets the required conditions in terms of flow, pressure, temperature and purity.

[0129] The air supply system 30 includes an air supply line 31 and an air shut-off valve 32. When several fuel cell modules 100 are arranged in the cabinet 2, air can be distributed within the cabinet 2 in a manifold with separate branches to each fuel cell module 100. Each inlet branch is equipped with a dedicated air shut-off valve 32 to ensure safe shut-off of the supply when necessary. The shut-off valve 32 is controlled by the control unit 60.

[0130] Emission system

[0131] In the exhaust system 40, process water and exhaust gas from the fuel cell process are separated. The exhaust system 40 comprises an exhaust pipe 42 and a water condensate tank 41. The exhaust pipe 42 and the process water condensate tank 41 can be completely welded. The exhaust gas contains a small amount of hydrogen and needs to be extracted to the open air or other safe space through a pipeline 43 to a ventilation mast according to the specifications of the vessel / ship.

[0132] When several fuel cell modules are arranged in the cabinet 2, exhaust gas is directed from each fuel cell module 100 to a manifold leading to a water condensation tank 41. After water separation, the exhaust gas is directed to the top of the cabinet 2 through a pipeline 43.

[0133] Shell atmosphere system

[0134] The purpose of the containment atmosphere system 50 is to establish and maintain an inert atmosphere below ambient pressure within the containment enclosure 10. It is very important to avoid flammable mixtures, such as those of hydrogen and oxygen, because if such a mixture occurs, the potential for fire is high. An inert atmosphere reduces the likelihood of a flammable mixture occurring within the containment enclosure 10. Nitrogen is the preferred inert gas.

[0135] The enclosure atmosphere gas system 50 includes an inlet 51 into the containment enclosure 10. An inlet valve 52 is arranged to control the flow of fluid (i.e., inert gas) into the containment enclosure 10. An outlet valve 54 controls the flow of gas out of the containment enclosure through an outlet 53. A pump 55 (or other air extraction device) is arranged to extract air from the containment enclosure 10 through the outlet 53 when the outlet valve 54 is open. Figure 7 and Figure 8 .

[0136] A pump 55 generates a pressure below ambient pressure in the or each containment vessel 10. The containment vessel pressure is expected to vary slowly during normal operation due to temperature fluctuations and normal diffusion. The correct pressure is maintained close to a set point by adjusting the amount of nitrogen in the containment vessel 10. When the containment vessel pressure drops below a given value, an inlet valve 52 on the inlet 51 opens to let in more nitrogen. When the containment vessel pressure is too high, the pump 55 is started and the outlet valve 54 on the outlet 53 opens. The operation of the pump 55 and valves 52, 54 ensures that the volume of the containment vessel 10 is regularly purged to ensure that the hydrogen concentration is always kept below an ignitable level.

[0137] During the purge, the outlet valve 54 is opened, the pump 55 is started, and the inlet valve 52 is opened. At the end of the sequence, the inlet valve 52 is closed, then the outlet valve 54 is closed, and when the desired sub-atmospheric pressure is reached, the pump 55 is stopped. The pressure within the containment enclosure 10 is monitored using a pressure sensor 56, and the enclosure atmosphere system 50 is controlled by a control unit 60 to maintain the desired sub-ambient pressure. The outlet valve 54 is opened, and the pump 55 is started at the high level, while the inlet valve 52 is opened to increase the pressure at the low level.

[0138] Cooling system

[0139] The purpose of the cooling system 90 is to ensure a stable operating temperature in the fuel cell module 100 by removing excess heat. The pump 95 controls the total coolant flow according to the power request, while the three-way valve is controlled to balance the flow between the bypass and the heat exchanger 92 to achieve the optimal inlet temperature on the inlet of the fuel cell module 100.

[0140] The cooling system 90 includes a closed loop 91 including a heat exchanger 92 and an expansion tank 93. When several fuel cell modules 100 are arranged in the cabinet 2, the coolant may be distributed to each fuel cell module 100 through a manifold having parallel branches, and the expansion tank 93 may be common to the cabinet 2. Each branch may be equipped with a water pump and a manual valve at the inlet and outlet so as to be able to connect / disconnect the flow through the fuel cell module 100 individually.

[0141] Leak Detection Principle

[0142] To detect leaks, several sensors are arranged in the safety and support system 1. In addition to the pressure sensor 56 and the fuel pressure sensor 23, the following sensors are arranged to monitor the interior of the containment enclosure 10: a temperature sensor 11, an oxygen sensor 12, a hydrogen sensor 13, and a liquid level sensor 14.

[0143] In order to detect and avoid the formation of explosive mixtures of hydrogen and oxygen, the following leak detection principles are implemented:

[0144] Air entering the containment enclosure 10 (external leakage): detected by the pressure sensor 56 and the oxygen sensor 12.

[0145] Air enters the containment enclosure 10 (from the air supply system 30 ): detected by the pressure sensor 56 and the oxygen sensor 12 .

[0146] Hydrogen enters the safety enclosure 10 (a small amount of diffusion leakage): detected by the hydrogen sensor 13.

[0147] Hydrogen enters the containment vessel 10 (large leak): detected by the pressure sensor 56 , the pressure sensor 23 and the hydrogen sensor 13 .

[0148] Coolant water and drain water enter the containment enclosure 10: detected by humidity / level sensor 14 (and also by pressure sensor 56 in case of large leaks).

[0149] Exhaust gas enters the containment enclosure 10 : detected by the pressure sensor 56 , the oxygen sensor 12 , and the humidity sensor / liquid level sensor 14 .

[0150] In addition to or instead of the hydrogen sensor 13, an outlet hydrogen sensor may be arranged in the outlet line connected to the outlet 53. The hydrogen concentration in the gas leaving the containment enclosure may then be monitored to detect leaks from within the containment enclosure 10.

[0151] The control unit 60 is arranged to define whether a detected situation will cause the closing and isolation of each single containment enclosure independently by closing the valves 24 and 32 .

[0152] The safety and support system 1 described above is used with a hydrogen fuel cell. The hydrogen fuel cell may be a fuel cell 100, such as a PEM fuel cell, an alkaline fuel cell, or a solid oxide fuel cell. The safety and support system 1 may also be used with other types of fuel cells. Examples of other such fuel cells may be, but are not limited to: natural gas fuel cells, ammonia fuel cells, and methanol fuel cells.

Claims

1. A safety and support system (1) for a fuel cell module (100), the safety and support system comprising: a pressure-tight safety enclosure (10) for enclosing the fuel cell module (100) and for containing a fluid in a space between the fuel cell module (100) and the safety enclosure (10), - a fuel supply system (20) arranged to deliver fuel from an external source located outside the containment enclosure (10) to the fuel cell module (100), - an air supply system (30) arranged to deliver air to the fuel cell module (100) from an external source located outside the containment enclosure (10), an exhaust system (40) arranged to convey exhaust fluid from the fuel cell module (100) out of the safety enclosure (10) while being isolated from the space between the fuel cell module (100) and the safety enclosure (10), and - a housing atmosphere system (50), the housing atmosphere system comprising: - an outlet (53) from the safety enclosure (10), the outlet having an outlet valve (54), - an inlet (51) having an inlet valve (52) for controlling the intake of fluid into the containment enclosure (10), - means (55) for extracting fluid from said containment vessel (10) through said outlet (53), and - a pressure sensor (56) arranged to measure the pressure of the fluid inside the containment vessel (10), The enclosure atmosphere system (50) is arranged to maintain the interior of the safety enclosure (10) at a pressure lower than ambient pressure.

2. The safety and support system (1) according to claim 1, wherein: The enclosure atmosphere system (50) comprises an inert gas supply device, and the inert gas supply device is used to provide an inert gas atmosphere to the interior of the safety enclosure (10).

3. The safety and support system (1) according to claim 2, wherein: The inert gas supply device is a nitrogen supply device.

4. The safety and support system (1) according to claim 3, wherein: The nitrogen supply device is a nitrogen generator (57).

5. The safety and support system (1) according to any one of claims 2 to 4, comprising a cabinet (2) for accommodating the safety enclosure, wherein: The inert gas supply device is arranged inside the cabinet (2).

6. The safety and support system (1) according to any one of the preceding claims, wherein: The containment enclosure (10) comprises a pressure relief valve (58) arranged to release fluid from the containment enclosure (10) when the pressure inside the containment enclosure (10) increases above a threshold value.

7. The safety and support system (1) according to any one of the preceding claims, wherein: The enclosure atmosphere system (50) is arranged to purge the interior of the safety enclosure (10).

8. The safety and support system (1) according to any one of the preceding claims, wherein: The outlet (53) is arranged at the top of the safety enclosure (10).

9. The safety and support system (1) according to any one of the preceding claims, wherein: The fuel supply system (20) comprises a fuel supply line (21) having a narrow contraction orifice (22), wherein a fuel pressure sensor (23) is arranged to detect the pressure inside the fuel supply line (21) downstream of the narrow contraction orifice (22).

10. The safety and support system (1) according to any one of the preceding claims, wherein: The fuel cell module (100) is a hydrogen fuel cell module.

11. The safety and support system (1) according to claim 10, wherein: The safety and support system (1) further comprises a cooling system arranged to transport heat from the fuel cell module (100) out of the safety enclosure.

12. The safety and support system (1) according to claim 11, wherein: The cooling system (90) is a closed loop (91) cooling system, and wherein the hydrogen concentration in the closed loop (91) is monitored by a coolant hydrogen sensor (94).

13. The safety and support system (1) according to any one of claims 10 to 12, wherein: The system (1) further comprises: At least one sensor selected from the list consisting of: a temperature sensor (11) arranged to measure the temperature inside the containment enclosure (10) and to send the measurement result to a control unit (60), - an oxygen sensor (12) arranged to measure the oxygen level inside the containment enclosure (10) and to send the measurement result to the control unit (60), a hydrogen sensor (13) arranged to measure the hydrogen level inside the containment enclosure (10) and to send the measurement result to the control unit (60), and - a liquid level sensor (14) arranged to measure the liquid level inside the containment enclosure (10) and to send the measurement result to the control unit (60).

14. The safety and support system (1) according to any one of claims 10 to 13, further comprising an outlet hydrogen sensor arranged outside the safety enclosure (10) for measuring the hydrogen level in a fluid line connected to the outlet (53), and wherein, The outlet hydrogen sensor is arranged to send measurement results to the control unit (60).

15. The safety and support system (1) according to claim 14, wherein: The outlet hydrogen sensor is arranged between the outlet valve (54) and the device (55) for extracting gas from the containment enclosure (10).

16. The safety and support system (1) according to any one of claims 13 to 15, wherein: - the control unit (60) is configured to receive measurements from at least one sensor (11, 12, 13, 14), and the system comprises: a fuel supply shut-off valve (24) arranged to stop supplying fuel to the fuel cell module (100) in response to a fuel stop signal from the control unit (60), and - an air stop valve (32) arranged to stop supplying air to the fuel cell in response to an air stop signal from the control unit (60).

17. The safety and support system (1) according to any one of claims 1 to 15, wherein: The enclosure atmosphere system (1) is arranged to purge the interior of the safety enclosure (10) when the level of oxygen and / or fuel inside the safety enclosure (10) reaches a threshold value.

18. A method for preventing the occurrence of an explosive atmosphere inside a safety enclosure (10) of a safety and support system (1) according to any one of claims 1 to 17, the method comprising performing the following steps: - Open the inlet valve (52) and the outlet valve (54) - operating the device (55) for extracting gas from the containment shell (10) so as to suck fluid from the inlet (51) through the interior of the containment shell (10) and out of the outlet (53), - closing the inlet valve (52), - keeping the outlet valve (54) open and continuing to operate the means (55) for extracting gas until the pressure inside the containment vessel (10) reaches the desired pressure below ambient pressure, and - Closing the outlet valve (54) and deactivating the device (55) for extracting gas.

19. A fuel cell system (200) for marine applications, wherein: The system (200) comprises a safety and support system (1) according to any one of claims 1 to 17 and a fuel cell module (100) installed inside a safety enclosure (10) of the safety and support system (1).

20. The fuel cell system (200) according to claim 19, wherein: At least two fuel cell systems (200) are arranged in a common cabinet (2) for supplying electricity to a ship, wherein the cabinet (2) is provided with a common interface for connecting the at least two fuel cell systems to an external fuel source and an external air source on the ship, and the common interface is used to connect the power output ends of the at least two fuel cell systems to electrical consumers on the ship.

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