Safety support system for fuel cell modules

Abstract

Described herein is a safety support system for a fuel cell module, comprising a pressure-resistant safety casing that surrounds the fuel cell module and houses a fluid, a fuel supply system arranged to transport fuel from an external source to the fuel cell module, an air supply system arranged to transport air from an external source to the fuel cell module, an exhaust system arranged to transport an exhaust fluid from the fuel cell module outside the safety casing, and a casing atmosphere system comprising an inlet into the safety casing having an inlet valve, an outlet from the safety casing having an outlet valve, means for exhausting fluid from the safety casing through the outlet, and a pressure sensor arranged to measure the pressure of the fluid inside the safety casing, wherein the casing atmosphere system is arranged to maintain the inside of the safety casing below ambient pressure. Also described herein are a method for preventing an explosive atmosphere inside the safety casing and a fuel cell system for marine applications.

Description

Technical Field

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

Background Art

[0002] A fuel cell is an electrochemical device that directly converts chemical energy generated by a reaction into electrical energy. For example, one type of fuel cell includes a proton exchange membrane (PEM), often called a polymer electrolyte membrane, which allows only protons to pass between the anode and cathode of the fuel cell. At the anode, diatomic hydrogen (fuel) reacts to produce hydrogen protons, which pass through the PEM. The electrons generated by this reaction move through a circuit outside the fuel cell, generating an electric current. At the cathode, oxygen is reduced and reacts with hydrogen protons to form water. The anode reaction and cathode reaction are described by the following equations. At the anode of the cell,

Chemical formula

Chemical formula

[0003] A single fuel cell typically generates a relatively low voltage (e.g., about 1 volt), so multiple fuel cells may be combined to form a configuration called a fuel cell stack to generate a higher voltage. The fuel cell stack may include stacked plates (e.g., graphite composite or metal plates), and each plate may be associated with two or more fuel cells in the stack. The plates may include various flow channels and orifices for routing reactants and products through the fuel cell stack, for example. Multiple PEMs (each associated with a specific fuel cell) may be distributed across the stack between the anodes and cathodes of different fuel cells.

[0004] The fuel cell stack, local control unit, and core components essential for power generation are often arranged together within a single fuel cell module. Such fuel cell modules are often formed based on the components of a fuel cell system used in automobiles. These components, which can be positioned at separated locations within a fuel cell vehicle / automobile, can be arranged within a compact module for other applications and are commercially available.

[0005] In particular, hydrogen (H2) is a very light gas and a very small molecule that is difficult to contain within any system. Leakage can easily occur, and hydrogen has a tendency to diffuse from any system in use into the surroundings.

[0006] In a fuel cell module as described above, a small amount of fuel (in some cases hydrogen) leaks into the surroundings over time. Usually, in fuel cell applications such as hydrogen vehicles, such a small amount of fuel is diluted in the ambient air before an explosive mixture with oxygen can occur. This is possible because the fuel cell module is placed within a well-ventilated compartment and the vehicle is used outdoors.

[0007] In recent years, the use of hydrogen as a fuel has become more common. The use of fuel cells is also recently considered as a step towards decarbonization in maritime transportation. However, there are still issues that need to be resolved before fuel cell technology can be widely used on ships and other ocean vessels.

[0008] One important difference between installing a fuel cell in a ship compared to in an automobile is that it may be desirable to install the fuel cell in an enclosed space below deck. As a result, leakage of a highly flammable fuel such as hydrogen can create an explosive atmosphere within the enclosed space. In the automotive industry, the safety concept for avoiding an explosive atmosphere is to flow ambient air around the outside of the fuel cell components so that hydrogen leakage diffuses before the hydrogen concentration reaches a concentration considered to be an explosive atmosphere. This concept is not as suitable for ships as it is for automobiles because shipboard systems are larger than those in automobiles (and thus tend to leak more hydrogen) and may be placed in enclosed spaces that require large-scale forced ventilation systems that reduce the overall efficiency of the system.

[0009] Similar problems exist for other types of fuel cells, and also apply to fuel cells that use hydrogen as a fuel such as PEM fuel cells, alkaline fuel cells, solid oxide fuel cells, as well as fuel cells for other types of fuels such as natural gas fuel cells, ammonia fuel cells, and methanol fuel cells.

[0010] International Publication No. 0159861 (A2) discloses a fuel cell system including a fuel cell stack, a housing that houses the fuel cell stack, and a blower. The blower is located inside the housing and is adapted to extract air from inside the housing to generate an air flow flowing through the fuel cell stack and to establish a negative pressure inside the housing with respect to the region outside the housing. The air drawn into the housing passes through a filter. The filter causes a pressure drop, which creates a negative pressure inside the housing. The negative pressure is maintained only while the blower is extracting air from the housing.

[0011] Japanese Patent Application Laid-Open No. 2005-268054 discloses a solution for suppressing an abnormal state in a fuel cell system for the purpose of providing a compact solution that can be used in a vehicle. By replacing oxygen so that the oxygen concentration becomes low enough not to cause a fire, the abnormal state is suppressed. This document teaches replacing oxygen using hydrogen or cooling water instead of supplying an inert gas to replace oxygen (which makes the system large and heavy). Hydrogen and cooling water must be available for operating the fuel cell anyway. Such a system for replacing oxygen does not add much weight or volume to the fuel cell system. Therefore, while maintaining the compactness of the fuel cell system, an abnormal state can be suppressed.

[0012] Japanese Patent Application Laid-Open No. 2009-046128 discloses a heat-insulating container provided with a surface variable mechanism for switching at least a part of the outer shell of the container between a flat surface state and a fine 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 in response to heat generation inside the container. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0013] One object of the present invention is to provide a safety support system for a standard fuel cell module that prevents the formation of an explosive atmosphere around the fuel cell module, that is, particularly when hydrogen is the fuel, prevents the formation of an explosive mixture of fuel and oxygen.

[0014] Another object of the present invention is to enhance the ability to detect leaks or abnormal conditions that may lead to the formation of an explosive atmosphere (e.g., a mixture of hydrogen and oxygen when hydrogen is the fuel and air is supplied to the fuel cell) with respect to the fuel cell.

[0015] Yet another object of the present invention is to provide a housing having a safety support system suitable for use of a standard industrial fuel cell module, which is normally intended for use in an environment where air is ventilated, on a ship (e.g., housed in an enclosed space such as an engine room below deck). This is particularly to prevent the formation of an explosive atmosphere in the above-mentioned enclosed space.

Means for Solving the Problems

[0016] The present invention, in a first aspect, relates to a safety support system for a fuel cell module. The system includes - a pressure-resistant safety casing that surrounds the fuel cell module and houses a fluid in the space between the fuel cell module; - a fuel supply system arranged to transport fuel from an external supply source outside the safety casing to the fuel cell module; - an air supply system arranged to transport air from an external supply source outside the safety casing to the fuel cell module; - a discharge system arranged to transport the discharged fluid from the fuel cell module to the outside of the safety casing, isolated from the space between the fuel cell module and the safety casing; - a casing atmosphere system, - an outlet from the safety casing having an outlet valve, - an inlet having an inlet valve for controlling the intake of fluid into the safety casing (i.e., into the space between the fuel cell module and the safety casing), - means for exhausting the fluid from the safety casing through the outlet, and - a pressure sensor arranged to measure the pressure of the fluid inside the safety casing and a casing atmosphere system comprising It includes

[0017] The casing atmosphere system is arranged to maintain the fluid inside the safety casing below ambient pressure.

[0018] In an embodiment, the fuel is hydrogen.

[0019] In an embodiment, the fluid is preferably a gas containing an inert gas. The fluid may be a liquid. The means for exhausting the fluid can be a device such as a vacuum pump, blower, or compressor. The device is arranged to suck the fluid from the atmosphere inside the safety casing, i.e., the fluid-filled (mostly gas-filled or mainly gas-filled) space between the components of the fuel cell module and the interior of the safety casing. The device can be arranged downstream of the outlet valve.

[0020] Pressure resistance means that the safety casing can maintain the pressure of the fluid located in the space between the components of the fuel cell module and the interior of the safety casing. Air and fuel flow into the components of the fluid cell module through the safety casing via pipes, and the exhaust flows out of the fluid cell module through the safety casing via pipes. These flows are isolated from the space between the components of the fuel cell module and the inner surface of the safety casing, but minor leakage and / or diffusion from the components of the fuel cell module to the above space are exceptions.

[0021] The control system can control the opening and closing of the inlet valve, outlet valve, and the means for exhausting the gas. The control system can further receive measurement values from the pressure sensor.

[0022] The pressure below ambient pressure inside the safety casing can be a pressure lower than the ambient pressure (about 1 bar), preferably 0.7 - 0.9 bar, and most preferably 0.8 bar.

[0023] One advantage of maintaining the inside of the safety casing below ambient pressure is that in the event of an explosion, the explosion starts within a casing having a lower initial pressure compared to the outside of the safety casing. Thus, compared to an explosion starting within the same safety casing having an inside pressure above ambient / outside pressure, the pressure differential with respect to the ambient / outside pressure has to rise more before reaching the burst pressure of the safety casing.

[0024] Maintaining the inside of the safety casing below ambient pressure also has the advantage that leaks can be more easily detected by a pressure sensor. All potential fluid sources have a pressure higher than the pressure of the fluid inside the safety casing below ambient pressure. Ambient air, having a higher pressure, leaks from the outside of the safety casing are detected as an increase in the pressure inside the safety casing. The same applies to fuel supply sources and air supply sources, both of which have a pressure higher than the pressure of the fluid inside the safety casing below ambient pressure.

[0025] The effect of having both an inlet and an outlet, compared to having only one opening to the inside space of the safety casing, is that the space inside the safety casing can be purged. Having only an outlet makes it possible to suck out fluid / gas and lower the pressure below ambient pressure, but effective purging of the inner volume is not easy.

[0026] Purging means removing the contents of a pipe and / or container and replacing it with another gas or liquid. For example, by opening the inlet valve and the outlet valve simultaneously, drawing a new volume of gas into the safety casing and operating means for exhausting gas from the safety casing until all gas / fluid present inside the safety casing has been exchanged.

[0027] The air supply system can preferably supply process air.

[0028] The casing atmosphere system may include an inert gas source for supplying an inert gas atmosphere inside the safety casing.

[0029] Filling the safety casing with an inert gas helps prevent the formation of an explosive atmosphere inside the safety casing. For example, if only fuel leakage occurs inside the safety casing, there is no oxygen to cause an explosive reaction.

[0030] The inert gas source may be a nitrogen gas source.

[0031] The nitrogen gas source may be a nitrogen gas generator.

[0032] The nitrogen gas generator may be in fluid communication with an inlet to the safety casing upstream of the inlet valve.

[0033] The advantages of nitrogen are that it is relatively inexpensive and is a commercially available inert gas. Since nitrogen generators are also commercially available, nitrogen can be generated where needed.

[0034] The system may include a cabinet for housing the safety casing. The cabinet can house and support the safety casing and, in some cases, may completely surround the safety casing. An inert gas source such as a nitrogen generator may be disposed inside the cabinet.

[0035] This inert gas source can be positioned either inside or outside the safety casing when the safety casing is installed inside the cabinet. This can result in a compact safety support system that is easy to transport and install.

[0036] The safety casing may include a pressure relief valve arranged to release fluid from the safety casing when the pressure inside the safety casing rises above a threshold value.

[0037] The pressure relief valve can be arranged to release fluid from the safety casing when the pressure rises significantly. This is advantageous in the event of an explosion / combustion inside the safety casing. Furthermore, even when the pump is not functioning, the safety casing can be purged. The fluid is then pushed into the inlet, and when the pressure exceeds the opening pressure of the pressure relief valve, the fluid flows out of the safety casing through the pressure relief valve.

[0038] The casing atmosphere system can be arranged to purge the inside of the safety casing. The purge can be carried out periodically.

[0039] Fuel (especially when the fuel is hydrogen gas) and air diffuse from the fuel cell module over time, accumulate inside the safety casing, and are mixed with the fluid inside the safety casing there. By this, there is a risk of generating an explosive mixture of fuel and oxygen over time, and this mixture may ignite. By periodically purging the internal volume of the safety casing (i.e., refilling, flushing, or replacing the gas filling volume), the accumulation of an explosive atmosphere is avoided. Therefore, periodically purging the safety casing has the advantage of removing this explosive atmosphere and, when an inert gas such as nitrogen is used for the purge, maintaining an inert atmosphere by the purge.

[0040] The outlet can be arranged at the top of the safety casing.

[0041] The top of the casing means the surface of the safety casing that is arranged to be at the top or uppermost when the fuel cell module is installed and the system is operable. The outlet is preferably at the upper quarter position of the safety casing and more preferably located on the upper panel of the safety casing.

[0042] Since hydrogen is lighter than other gases, it rises to the upper part inside the safety casing. Therefore, when hydrogen is used as fuel, placing the outlet at the upper part of the safety casing makes it easier to exhaust all the hydrogen from the safety casing during purging. There may be cases where other fuels are lighter than other fluids inside the safety casing. Therefore, placing the outlet at the upper part of the safety casing can also be beneficial when other light fuels are used.

[0043] In addition to having an outlet at the upper part of the safety casing, the inlet can be arranged at the bottom of the safety casing or near the bottom. The bottom is a panel of the safety casing arranged to face downward during normal operation. The inlet is preferably at the quarter position of the bottom of the safety casing, and more preferably on the bottom panel of the safety casing.

[0044] CFD simulations and tests were conducted on the purging of nitrogen in the inert gas system. The simulation shows that by supplying nitrogen at the bottom of the safety casing and extracting it at the top, the inert gas volume can be exchanged so that the concentrations of fuel (especially hydrogen) and oxygen are maintained at acceptable levels throughout the volume inside the safety casing, while ensuring that the safety casing pressure remains stable. The volume purged from the safety casing includes fluids such as nitrogen, diffused hydrogen, and diffused air.

[0045] The fuel supply system may include a fuel supply line having a throttling flow orifice, and a fuel pressure sensor may be arranged to detect the pressure inside the fuel supply line downstream of the throttling flow orifice.

[0046] The throttling orifice is the part of the line where the diameter is reduced compared to the rest of the line.

[0047] Having a throttle flow orifice upstream of a pressure sensor that measures the pressure inside the fuel supply line has the advantage that it is easier to detect leaks in the fuel supply line downstream of the flow orifice. Upstream of the throttle flow orifice, the fuel supply line is formed with a double-wall structure and can be fully welded at all connections. Inside the safety casing, the fuel supply source preferably has a single wall. Leaks in the fuel supply line after the flow orifice are easily detected by the pressure loss in that part of the fuel supply line.

[0048] The fuel cell module can be a hydrogen fuel cell module.

[0049] The hydrogen fuel cell module can use hydrogen gas (H2) as fuel. The hydrogen fuel cell module can include a PEM fuel cell, an alkaline fuel cell, or a solid oxide fuel cell.

[0050] The system can further include a cooling system arranged to transport heat from the fuel cell module to the outside of the safety casing.

[0051] The cooling system can be a closed-loop cooling system, and the fuel concentration in the closed loop can be monitored by a coolant fuel sensor. When the fuel is hydrogen, the hydrogen concentration in the closed loop can be monitored by a coolant hydrogen sensor.

[0052] The closed-loop cooling system contains a cooling fluid. Fuel (such as hydrogen) can diffuse through the walls of the closed-loop cooling system inside the fuel cell module over time 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 it can act in a timely manner if an explosive mixture of hydrogen and oxygen is formed. The coolant hydrogen sensor can be arranged at the top of an expansion tank arranged inside the closed loop of the cooling system.

[0053] The safety support system further - A temperature sensor arranged to measure the temperature inside the safety casing and transmit the measured value to a control unit, - An oxygen sensor arranged to measure the oxygen level inside the safety casing and transmit the measured value to a control unit, - A fuel sensor arranged to measure the fuel level inside the safety casing and transmit the measured value to a control unit, - A liquid level sensor arranged to measure the liquid level inside the safety casing and transmit the measured value to a control unit and comprising at least one sensor selected from the list consisting of

[0054] The fuel can be hydrogen and the fuel sensor can be a hydrogen sensor. The fuel level or hydrogen level can include the concentration of fuel or hydrogen.

[0055] The safety support system may further comprise an outlet hydrogen sensor arranged outside the safety casing for measuring the hydrogen level in a fluid line connected to the outlet. The outlet hydrogen sensor may be arranged to transmit the measured value to the control unit.

[0056] It is desirable to be able to monitor the hydrogen level inside the safety casing (i.e., within the volume between the fuel cell module and the safety casing), but there are several challenges in placing a hydrogen sensor inside the safety casing.

[0057] One challenge is that sensors placed inside the safety casing are exposed to the high temperatures inside the safety casing. The hydrogen sensor may fail or show inaccurate readings due to this high-temperature environment.

[0058] Another problem is that during normal operation of the fuel cell module, a small amount of hydrogen leaks / diffuses from the fuel cell module. The hydrogen sensor disposed inside the safety casing will always be exposed to this low but constant level / concentration of hydrogen. Some types of hydrogen sensors will deteriorate, be consumed, become inaccurate, or stop functioning when constantly exposed to such hydrogen concentrations.

[0059] Another problem is that some hydrogen sensors need to be calibrated regularly and are arranged to be calibrated automatically. In this calibration, the very low normal hydrogen concentration in the ambient air is intended to be used as a reference for low hydrogen concentration. Since the hydrogen sensor inside the safety casing is not in contact with the ambient air, the hydrogen concentration inside the safety casing is used as the low reference concentration / baseline. This will work well most of the time as long as the hydrogen leakage from the fuel cell module into the space between the safety casing and the fuel cell module does not increase slowly. In such a situation, the sensor and the associated control unit gradually increase the concentration that is assumed to be the low / baseline concentration of hydrogen for each calibration. That is, the calibration of the hydrogen sensor gradually turns off, and the slow increase in hydrogen concentration is no longer recorded.

[0060] Due to the above problems, the system may be provided with a hydrogen sensor outside the safety casing rather than inside the safety casing. This outlet hydrogen sensor measures the hydrogen concentration in the fluid exiting the safety casing, for example, each time the safety casing is purged. The increase in the hydrogen concentration inside the safety casing is revealed by the increase in the concentration of the fluid exiting the safety casing through the outlet.

[0061] The outlet hydrogen sensor can be placed anywhere downstream of the outlet valve, preferably between the outlet valve and the means for exhausting gas from the safety casing.

[0062] This arrangement may further be made to accommodate a flow of secondary fluid having an appropriate temperature and gas concentration that may be beneficial for enhancing 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 period when gas is not being drawn out from the safety casing.

[0063] In a preferred embodiment, four safety casings (each housing a fuel cell module) are arranged in a row and share a common means (which may be a vacuum pump) for exhausting gas from the safety casings. In such an embodiment, each safety casing may have an outlet valve. Thus, an advantage of such an arrangement of the outlet hydrogen sensors is that each of the safety casings can be monitored using a single hydrogen sensor. By matching the opening period of the outlet valve with the detection period, it is possible to detect from which fuel cell module a leak is occurring.

[0064] The control unit may be configured to receive measurement values from at least one sensor, and the system may - a fuel supply shut-off valve arranged to shut off the supply of fuel to the fuel cell module in response to a fuel shut-off signal from the control unit, and - an air shut-off valve arranged to shut off the supply of air to the fuel cell in response to an air shut-off signal from the control unit be provided.

[0065] The fuel shut-off valve and the air shut-off valve may be located at or near the boundary or wall of the safety casing. In this way, when the control unit receives a fuel shut-off signal or an air shut-off signal and the valve is closed, not only is the movement of additional air and / or fuel into the fuel cell prevented, but also the inflow into the safety casing is prevented, thereby preventing further accumulation of these substances within the safety casing.

[0066] The casing atmosphere system can be arranged to purge the inside of the safety casing when the level of oxygen and / or fuel inside the safety casing reaches a threshold value. For any of the embodiments described herein, the fuel can be hydrogen.

[0067] In another aspect, the present invention relates to a method for preventing an explosive atmosphere inside the safety casing of a safety support system, the system comprising an inlet to a safety casing having an inlet valve for controlling the intake of fluid into the safety casing. The method comprises - opening the inlet valve and the outlet valve; - operating means for exhausting gas from the safety casing to draw fluid through the interior of the safety casing from the inlet and out through the outlet; - closing the inlet valve; - leaving the outlet valve open and continuing to operate means for exhausting gas until the pressure inside the safety casing reaches a pressure below a desired ambient pressure; - closing the outlet valve and stopping the operation of the means for exhausting gas including performing.

[0068] An alternative method is to separate the control of the inlet valve on the one hand and the control of the outlet valve and the means for exhausting gas on the other hand, that is, - controlling the inlet valve for the purpose of maintaining the gas composition inside the safety casing, for example by opening the valve when the concentration of hydrogen or oxygen reaches a specific threshold; - controlling the outlet valve and the means for exhausting gas for the purpose of maintaining the pressure inside the safety casing, for example by opening the outlet valve and operating the means for exhausting gas when the pressure reaches a specific level.

[0069] In yet another aspect, the present invention relates to a fuel cell system for marine applications, the system comprising a safety support system according to the first aspect and a fuel cell module installed inside the safety casing of the safety support system.

[0070] At least two fuel cell systems can be arranged in a common cabinet to supply power to a ship. The cabinet can be arranged with a common interface for connecting at least two fuel cell systems to an external supply source of fuel and air mounted on the ship, and for connecting the power output parts of at least two fuel cell systems to a power consumption part mounted on the ship.

[0071] Next, embodiments of the present invention will be described by way of example only with reference to the following drawings.

Brief Description of the Drawings

[0072]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

DETAILED DESCRIPTION OF THE INVENTION

[0073] Figure 1 shows a standard fuel cell module 100. In this embodiment, the fuel cell module is a hydrogen fuel cell module where hydrogen gas is the fuel. Such modules are typically formed based on components of a fuel cell system used in hydrogen vehicles. Such a fuel cell module 100 has the ability to generate approximately 80 kW of power. The fuel cell module needs to be supplied with air (process air as a source of O2), hydrogen gas (H2), and a coolant. The fuel cell module 100 outputs process water and exhaust gas containing a small amount of hydrogen gas in addition to the electric current. Normally, a small amount of hydrogen gas also leaks and / or diffuses from the fuel cell module 100. In a well-ventilated location, these small amounts of hydrogen gas disperse into the ambient air and do not accumulate to form an explosive atmosphere.

[0074] To supply power generated from the fuel cells to a ship, since 80 kW of power is usually not sufficient in the case of a ship, in most cases, a plurality of standard fuel cell modules 100 are required. Furthermore, the typical machinery space of a ship / vessel is an enclosed space, in contrast to a vehicle where ambient air can flow through the fuel cell components.

[0075] To consider the machine space as a gas safety space, the fuel cell module 100 is enclosed within a safety casing 10 as shown in FIG. 2. In FIGS. 3 and 4, the fuel cell module 100 is disposed inside the safety casing 10.

[0076] The safety casing 10 is part of the safety support system 1, which is designed to supply fuel (hydrogen gas / H2) and air to the fuel cell module so that the machine space where the fuel cell module is installed can be reliably regarded as a gas safety space. An embodiment of the safety support system is schematically shown in FIG. 7.

[0077] The main function of the safety casing 10 is to support the fuel cell module 100 and is an airtight container that may contain an inert atmosphere. The safety casing 10 can be designed to withstand a gas explosion inside the safety casing 10 and protect the surroundings from the impact of such an explosion. The safety casing is preferably made of steel, but other materials can also be used.

[0078] The safety casing 10 may be provided with a pressure relief valve 58. The pressure relief valve is arranged to release fluid from the safety casing, for example, when the pressure rises significantly as a result of fluid leakage into the safety casing and / or an explosion / combustion inside the safety casing 10. Further, the safety casing can be purged even if the pump 55 is not functioning. The fluid is then pushed into the inlet 51, and when the pressure exceeds the opening pressure of the pressure relief valve 58, the fluid flows out of the safety casing 10 through the pressure relief valve 58.

[0079] The safety support system 1 is a modular system that can be adapted to support one or more fuel cell modules 100, each enclosed within a safety casing 10. One such safety support system 1 that supports one or more (preferably four) fuel cell modules 100 can be disposed within a cabinet 2. Inside the cabinet 2, there is an auxiliary space that can accommodate the components of the safety support system 1 that are not disposed inside the safety casing 10. The cabinet 2 is open to the flow of ambient air 83 entering and exiting the cabinet 2 (see FIG. 7).

[0080] The safety support system further comprises a fuel supply system 20, an air supply system 30, an exhaust system 40, and a casing atmosphere gas system 50. The safety support system may further comprise a control unit 60, a power distribution system 70, and sensors 11, 12, 13, 14. In FIG. 7, all of these subsystems are schematically shown.

[0081] The fuel supply system 20, the air supply system 30, the exhaust system 40, and the casing atmosphere gas system 50 can be constructed to support a plurality of fuel cell modules 100 (each enclosed within a safety casing 10 and disposed within the cabinet 2). This can be done by providing manifolds for fuel, air, and exhaust, and adding valves for each safety casing 10 inside the cabinet 2. When a plurality of fuel cell modules 100 are disposed, the safety support system 1 is arranged such that there is only one interface (one line for supplying fuel from an external source, etc.) facing the ship for each cabinet 2. Fuel supply system

[0082] The purpose of the fuel supply system 20 is to supply fuel (typically hydrogen gas / H2) to the fuel cell module 10. An important issue is to ensure that the supply meets the required conditions with respect to flow rate, pressure, and purity.

[0083] The fuel cell module preferably has an inlet pressure of 5 to 15 bar, preferably about 9 bar. To avoid the inlet pressure from an external fuel storage tank (external fuel supply source) exceeding the designed inlet pressure to the fuel cell system 200, a pressure safety valve can be arranged on the fuel supply pipeline 21 from the ship.

[0084] The fuel supply system 20 may further include a throttle flow orifice 22 in the fuel supply line 21, a fuel supply shut-off valve 24 downstream of the throttle flow orifice 22, and a fuel pressure sensor 23 arranged downstream of the fuel supply shut-off valve 24. This arrangement is such that a rupture / major leak from the fuel line 21 downstream of the throttle flow orifice 22, particularly downstream of the valve 24 where a rupture or damage to the pipe causes fuel leakage into the safety casing, ensures a distinct pressure drop after the throttle flow orifice 22. Such a distinct 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 throttle flow orifice 22. The fuel supply shut-off valve 24 can be arranged at or near the boundary of the safety casing and at the same location as the flow orifice. In this case, a large leak downstream of the flow orifice 22 usually also occurs downstream of the fuel supply shut-off valve 24 and is detected as a sudden drop in pressure by the fuel pressure sensor 23.

[0085] The fuel supply line 21 is double-walled outside the safety casing 10, that is, it remains double-walled all the way to the wall of the safety casing 10 where the fuel shut-off valve 24 is also arranged. Thus, the fuel supply line 21' upstream of the fuel shut-off valve 24 is double-walled, and a leak inside the fuel supply line 21' upstream of the fuel shut-off valve 24 is contained inside the outer wall of the double wall 25 of the fuel pipe. A leak in the fuel line 21 downstream of the fuel shut-off valve 24 leaks into the safety casing 10. A major leak from the fuel pipe / line of the fuel cell module itself is also detected by the pressure sensor 23.

[0086] Between the storage tank (external fuel source) and each cabinet 2, it is preferable to arrange a double-block bleed valve with ventilation. When a safety event occurs between these valves and the safety casing 10, the fuel cell module 100 is stopped.

[0087] The fuel supply line 21' (for example, hydrogen supply line) for each safety casing 10 is also double-walled and is completely welded to an airtight flange bolted to the safety casing 10. As a result, a continuous annular portion is formed between the inner pipe and the outer pipe all the way from the double-block bleed valve to the safety casing 10. Inside the safety casing 10, the fuel supply line 21 can be single-walled.

[0088] When a plurality of fuel cell modules 100 are arranged in the cabinet 2, the fuel can be distributed into the cabinet 2 through a manifold having separate branches to each fuel module 100. Each branch is provided with a dedicated fuel shut-off valve 24 for each fuel cell module 100 arranged to ensure a safe shut-off of the supply as required. Air supply system

[0089] The purpose of the air supply system 30 is to supply oxygen to enable the electrochemical reaction in the fuel cell module 100. An important issue for the air supply system 30 is to ensure that the supply meets the required conditions regarding flow rate, pressure, temperature, and purity.

[0090] The air supply system 30 includes an air supply line 31 and an air shut-off valve 32. When a plurality of fuel cell modules 100 are arranged in the cabinet 2, the air can be distributed into the cabinet 2 within a manifold having separate branches leading to each fuel cell module 100. Each inlet branch is provided with a dedicated air shut-off valve 32 to ensure a safe shut-off of the supply as required. The shut-off valve 32 is controlled by the control unit 60. Exhaust system

[0091] In the discharge system 40, process water and exhaust gas from the fuel cell process are separated. The discharge system 40 includes a discharge pipe 42 and a water condensation tank 41. The discharge pipe 42 and the process water condensation tank 41 can be completely welded. The exhaust gas contains a small amount of hydrogen and needs to be exhausted to the outdoors or other safe space through line 43 and sent to the vent mast according to the specifications of the ship / vessel.

[0092] When a plurality of fuel cell modules are arranged in the cabinet 2, the exhaust gas is led from each fuel cell module 100 into a manifold that communicates with the water condensation tank 41. After water separation, the exhaust gas is led to the upper part of the cabinet 2 through line 43. Casing atmosphere system

[0093] The purpose of the casing atmosphere system 50 is to establish and maintain an inert atmosphere with a pressure below ambient pressure within the safety casing 10. Since a combustible mixture (e.g., a combustible mixture of hydrogen and oxygen) is likely to ignite when it occurs, it is important to avoid such mixtures. The inert atmosphere reduces the possibility of a combustible mixture inside the safety casing 10. Nitrogen is a preferred inert gas.

[0094] The casing atmosphere gas system 50 includes an inlet 51 into the safety casing 10. The inlet valve 52 is arranged to control the flow of fluid (i.e., inert gas) into the safety casing 10. The outlet valve 54 controls the flow of gas exiting the safety casing through the outlet 53. The pump 55 (or another exhaust means) is arranged to extract air from the safety casing 10 through the outlet 53 when the outlet valve 54 is open. Refer to FIGS. 7 and 8.

[0095] The pump 55 generates a pressure below the ambient pressure within each safety casing 10 when there is one safety casing 10 or multiple ones. Due to temperature fluctuations and normal diffusion, a gradual change in the safety casing pressure is expected during normal operation. By adjusting the amount of nitrogen within the safety casing 10, an accurate pressure is maintained near the setpoint. When the pressure of the safety casing drops below a predetermined value, the inlet valve 52 of the inlet 51 opens to introduce more nitrogen. On the other hand, when the pressure of the safety casing is too high, the pump 55 starts and the outlet valve 54 of the outlet 53 opens. The operations of the pump 55 and the valves 52, 54 ensure that the volume of the safety casing 10 is periodically purged to ensure that the hydrogen concentration is always kept below the flammable level.

[0096] During the purge sequence, the outlet valve 54 opens, the pump 55 starts, and the inlet valve 52 opens. At the end of the sequence, the inlet valve 52 is closed before the outlet valve 54 is closed, and the pump 55 stops when the desired sub - atmospheric pressure is reached. The pressure inside the safety casing 10 is monitored using the pressure sensor 56, and the casing atmosphere system 50 is controlled by the control unit 60 to maintain it below the desired ambient pressure. The outlet valve 54 opens and the pump 55 starts at a high level, while the inlet valve 52 opens to increase the pressure at a low level. Cooling system

[0097] The purpose of the cooling system 90 is to ensure a stable operating temperature within the fuel cell module 100 by removing excess heat. The pump 95 controls the total coolant flow based on the power requirement, while the three - way valve is controlled to balance the flow between the bypass and the heat exchanger 92 to achieve an optimal inlet temperature at the inlet of the fuel cell module 100.

[0098] The cooling system 90 includes a closed loop 91 having a heat exchanger 92 and an expansion tank 93. When a plurality of fuel cell modules 100 are disposed within the cabinet 2, the coolant can be distributed through a manifold having parallel branches passing through each of the fuel cell modules 100, and the expansion tank 93 can be a tank common to the cabinet 2. Each of the branches can be provided with a water pump and a manual valve at both the inlet and the outlet so as to be able to individually connect / disconnect the flow through the fuel cell module 100. Leak detection principle

[0099] To detect leaks, a plurality of sensors are disposed in the safety support system 1. In addition to the pressure sensor 56 and the fuel pressure sensor 23, temperature sensors 11, oxygen sensors 12, hydrogen sensors 13 and liquid level sensors 14 are disposed to monitor the interior of the safety casing 10.

[0100] To detect and avoid the formation of an explosive mixture of hydrogen and oxygen, the following leak detection principles are implemented. · Ingress of air into the safety casing 10 (external leak): Detected by the pressure sensor 56 and the oxygen sensor 12. · Ingress of air into the safety casing 10 (from the air supply system 30): Detected by the pressure sensor 56 and the oxygen sensor 12. · Ingress of hydrogen into the safety casing 10 (minor diffusion leak): Detected by the hydrogen sensor 13. · Ingress of hydrogen into the safety casing 10 (major leak): Detected by the pressure sensor 56, the pressure sensor 23, and the hydrogen sensor 13. · Ingress of cooling water and drain water into the safety casing 10: Detected by the moisture / liquid level sensor 14 (and in the case of a major leak, further by the pressure sensor 56). · Ingress of exhaust into the safety casing 10: Detected by the pressure sensor 56, the oxygen sensor 12, and the moisture sensor / liquid level sensor 14.

[0101] In addition to, or instead of, the hydrogen sensor 13, an outlet hydrogen sensor may be disposed in an outlet line connected to the outlet 53. Then, the hydrogen concentration in the gas exiting the safety casing can be monitored to indicate leakage from within the safety casing 10.

[0102] The control unit 60 is configured to define whether the detected scenario causes the shut-off and isolation of each single safety casing separately by closing the valves 24, 32.

[0103] The safety support system 1 has been described above as being used with a hydrogen fuel cell. The hydrogen fuel cell can be a fuel cell 100 such as a PEM fuel cell, an alkaline fuel cell, or a solid oxide fuel cell. The safety support system 1 can also be used with other types of fuel cells. Examples of other such fuel cells include, but are not limited to, natural gas fuel cells, ammonia fuel cells, and methanol fuel cells.

Description of Reference Numerals

[0104] 1 Safety support system (for fuel cell) 2 Cabinet (for one or more safety casings and related safety support system) 10 Safety casing (pressure-resistant) 11 Temperature sensor 12 Oxygen sensor 13 Hydrogen sensor 14 Liquid level sensor 15 Lid for safety case 20 Fuel supply system 21 Fuel supply line 21‘ Fuel supply line (part of which is outside the safety casing) 22 Restricted flow orifice 23 Fuel pressure sensor 24 Fuel supply shut-off valve 25 Outer wall of double-walled fuel line 30 Air supply system 31 Air supply line 32 Air shut-off valve 33 Air filter 40 Exhaust system 41 Moisture separator / water condensate tank 42 Exhaust pipe 43 Line to vent mast 44 Line for process water 50 Casing atmosphere system 51 Inlet 52 Inlet valve 53 Outlet 54 Outlet valve 55 Means for exhausting gas from the safety casing (e.g., pump) 56 Pressure sensor 57 Nitrogen generator 58 Overpressure check valve / pressure relief valve for the safety casing 60 Control unit 70 Power distribution system 81 Hydrogen diffusion 82 Oxygen diffusion 83 Flow of ambient air inside and outside cabinet 2 90 Cooling system 91 Closed loop 92 Heat exchanger 93 Expansion tank 94 Coolant hydrogen sensor 95 Cooling pump 100 Fuel cell module 110 Local fuel cell control unit 120 Power output section 200 Fuel cell system (comprising fuel cell module 100 and safety support system 1)

Claims

1. A safety support system (1) for a fuel cell module (100), a pressure-resistant safety casing (10) that surrounds the fuel cell module (100) and houses a fluid in the space between the fuel cell module (100); a fuel supply system (20) arranged to transport fuel from an external supply source outside the safety casing (10) to the fuel cell module (100); an air supply system (30) arranged to transport air from an external supply source outside the safety casing (10) to the fuel cell module (100); an exhaust system (40) arranged to transport the exhaust fluid from the fuel cell module (100) outside the safety casing (10) isolated from the space between the fuel cell module (100) and the safety casing (10); a casing atmosphere system (50), an outlet (53) from the safety casing (10) having an outlet valve (54), an inlet (51) having an inlet valve (52) for controlling the intake of the fluid into the safety casing (10), means (55) for exhausting the fluid from the safety casing (10) through the outlet (53), and a pressure sensor (56) arranged to measure the pressure of the fluid inside the safety casing (10) A casing atmosphere system (50) comprising A safety support system (1) comprising The casing atmosphere system (50) is arranged to maintain the inside of the safety casing (10) at a pressure below the ambient pressure. Safety support system (1).

2. The safety support system (1) according to claim 1, wherein the casing atmosphere system (50) comprises an inert gas supply source for supplying an inert gas atmosphere inside the safety casing (10).

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

4. The safety support system (1) according to claim 3, wherein the nitrogen gas supply source is a nitrogen generator (57).

5. The safety support system (1) according to any one of claims 2 to 4, further comprising a cabinet (2) for housing the safety casing, and the inert gas supply source is arranged inside the cabinet (2).

6. The safety casing (10) includes a pressure relief valve (58) arranged to release fluid from the safety casing (10) when the pressure inside the safety casing (10) rises above a threshold value. The safety support system (1) according to any one of claims 1 to 5.

7. The casing atmosphere system (50) is arranged to purge the inside of the safety casing (10). The safety support system (1) according to any one of claims 1 to 6.

8. The outlet (53) is arranged at the upper part of the safety casing (10). The safety support system (1) according to any one of claims 1 to 7.

9. The fuel supply system (20) includes a fuel supply line (21) having a throttle flow orifice (22), and a fuel pressure sensor (23) is arranged to detect the pressure inside the fuel supply line (21) on the downstream side of the throttle flow orifice (22). The safety support system (1) according to any one of claims 1 to 8.

10. The fuel cell module (100) is a hydrogen fuel cell module. The safety support system (1) according to any one of claims 1 to 9.

11. The safety support system (1) according to claim 10 further includes a cooling system arranged to transport heat from the fuel cell module (100) to the outside of the safety casing.

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

13. A temperature sensor (11) arranged to measure the temperature inside the safety casing (10) and transmit the measured value to the control unit (60), An oxygen sensor (12) arranged to measure the oxygen level inside the safety casing (10) and transmit the measured value to the control unit (60), A hydrogen sensor (13) arranged to measure the hydrogen level inside the safety casing (10) and transmit the measured value to the control unit (60), A liquid level sensor (14) arranged to measure the liquid level inside the safety casing (10) and transmit the measured value to the control unit (60) The safety support system (1) according to any one of claims 10 to 12, further comprising at least one sensor selected from the list consisting of

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

15. The safety support system (1) according to claim 14, wherein the outlet hydrogen sensor is disposed between the outlet valve (54) and the means (55) for exhausting gas from the safety casing (10).

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

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

18. A method for preventing an explosive atmosphere inside the safety casing (10) of the safety support system (1) according to any one of claims 1 to 17, comprising opening the inlet valve (52) and the outlet valve (54); operating means (55) for exhausting gas from the safety casing (10) to suck out fluid from the inlet (51) through the interior of the safety casing (10) to the outside through the outlet (53); closing the inlet valve (52); leaving the outlet valve (54) open and continuing to operate the means (55) for exhausting gas until the pressure inside the safety casing (10) reaches a pressure less than the desired ambient pressure; closing the outlet valve (54) and stopping the operation of the means (55) for exhausting gas The method comprising performing the same.

19. A fuel cell system (200) for marine use, comprising the safety support system (1) according to any one of Claims 1 to 17, and a fuel cell module (100) installed inside the safety casing (10) of the safety support system (1).

20. The at least two fuel cell systems (200) are arranged in a common cabinet (2) for supplying power to a ship, and the cabinet (2) is for connecting the at least two fuel cell systems to an external supply source of fuel and air mounted on the ship, and for connecting the power output parts of the at least two fuel cell systems to a power consumption part mounted on the ship, and is arranged together with a common interface. The fuel cell system (200) according to Claim 19.

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