fuel cell device

Abstract

To reduce a size of a fuel cell device by making capacity smaller than conventional capacity while securing an amount of water in a thermal storage tank.SOLUTION: A plurality of areas with different heights is provided on an upper surface of a thermal storage tank 3, and a feeding flow channel 26 that feeds a heat medium to the thermal storage tank 3 is connected to a first area A1 that is tallest among the areas. The first area A1 is formed protruding from the thermal storage tank 3 and therefore, compared to a case in which an upper surface of the thermal storage tank 3 is flat, a connection position of the feeding flow channel 26 can be set at a relatively high position. In other areas, a height of the upper surface of the thermal storage tank 3 can be reduced to get closer to a water surface, so that capacity of the thermal storage tank 3 is reduced. Thus, a size of a fuel cell device can be reduced.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a fuel cell device.

Background Art

[0002] A fuel cell device that generates electricity using a fuel gas containing hydrogen and an oxygen-containing gas (air) and supplies electricity to the outside is known. Such a fuel cell device includes a heat storage tank that stores a heat medium, recovers waste heat generated by the power generation of the fuel cell in the heat medium, stores it in the heat storage tank, and uses the heat medium for hot water supply, heating, etc.

[0003] Mainly water is used as this heat medium, and a circulation flow path through which water circulates is connected to the heat storage tank. In addition, a water supply flow path for replenishing water when the water level in the tank drops and a drainage flow path for discharging water when the water level rises and reaches the upper limit are also connected to the heat storage tank (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, tanks that receive water from an external source, such as thermal storage tanks, must be equipped with a structure to prevent backflow of water. For example, installing a check valve or a negative pressure release device is one such example. In addition, there is also a method of providing a predetermined outlet space between the location where the water supply channel is connected (discharge port) and the location where the drainage channel is connected (overflow surface). However, in this case, the thermal storage tank requires height above the overflow surface equal to the outlet space, and the volume of the thermal storage tank had to be designed to be larger relative to the amount of water. However, the outlet space is a space where water cannot be placed, and there is room for improvement in the shape of the thermal storage tank in order to miniaturize fuel cell devices.

[0006] The present invention aims to solve the above problems by providing a miniaturized fuel cell device equipped with a heat storage tank that can reduce the volume compared to conventional devices while ensuring the amount of water that can be stored inside. [Means for solving the problem]

[0007] This invention relates to a fuel cell that generates electricity using a fuel gas and an oxygen-containing gas, A heat storage tank for storing a heat transfer medium to recover waste heat from the fuel cell, The heat storage tank has a supply channel for supplying the heat transfer medium, An overflow channel for discharging excess heat transfer medium from the heat storage tank, An insulating member covering the outer periphery of the heat storage tank, Equipped with, The heat storage tank has multiple areas with different upper surface heights, and the replenishment channel is the first area with the highest upper surface height among the multiple areas. Supply depot located at Connected Occasionally, The overflow channel is connected to the side of the heat storage tank outside the first area, The heat insulating member has a guide portion that guides the overflow channel, The guide portion is maintained such that the overflow channel has an upward slope at a height that does not exceed the supply port in a predetermined section from the connection point with the heat storage tank. It is a fuel cell device. [Effects of the Invention]

[0008] By configuring it as described above, the volume of the heat storage tank can be reduced compared to conventional designs while still ensuring sufficient water storage capacity, thus enabling a more compact fuel cell system. [Brief explanation of the drawing]

[0009] [Figure 1] This is a system configuration diagram of the fuel cell device of this embodiment. [Figure 2] This is a perspective view of the heat storage tank of this embodiment. [Figure 3] This is an enlarged perspective view of the upper part of the heat storage tank in this embodiment. [Figure 4] This is a structural diagram of a heater that heats a heat transfer medium. [Figure 5] This diagram shows a heater locking member that secures the heater. [Figure 6] This diagram shows the installation status of the water level sensor used to detect the water level in the heat storage tank. [Figure 7] This diagram illustrates the shape of the insulating material attached to the heat storage tank. [Modes for carrying out the invention]

[0010] A preferred embodiment of the present invention will be briefly described by illustrating its operation.

[0011] The present invention relates to a fuel cell system equipped with a heat storage tank for storing a heat transfer medium that recovers waste heat from a fuel cell. The upper surface of the heat storage tank is provided with multiple areas of different heights, and a supply channel for supplying the heat transfer medium to the heat storage tank is connected to the first area, which has the highest height among the multiple areas. Since the first area is formed protruding from the heat storage tank, the connection position of the supply channel can be placed at a relatively higher position compared to when the upper surface of the heat storage tank is flat. Furthermore, in the other areas, the height of the upper surface of the heat storage tank can be lowered to bring it closer to the water level, thereby reducing the volume of the heat storage tank and enabling a more compact fuel cell system. In addition, the materials used to construct the heat storage tank can be reduced, thereby lowering component costs.

[0012] Also, in the top view of the heat storage tank, the area of the first area is the smallest among the plurality of areas. As a result, the materials constituting the heat storage tank are further reduced, so that the component cost can be reduced.

[0013] Also, the heater for heating the heat medium is connected to the heat storage tank outside the first area. By attaching the heater at a position close to the water surface, the length of the heater can be shortened and the component cost can be reduced.

[0014] Also, the heat storage tank is made of resin, the heater is attached to the upper surface of the heat storage tank, and a heater locking member is provided for locking the wiring electrically connected to the heater at a position higher than the heat storage tank. By making the heat storage tank made of resin, weight reduction can be achieved, but when the heater runs away, there is a risk that the heat storage tank will melt and the heater will fall. On the other hand, by locking the wiring of the heater with the heater locking member, it is possible to prevent the heater from falling even if the tank melts, and the safety can be improved.

[0015] Also, the liquid level sensor for detecting the liquid level height is connected to the heat storage tank outside the first area. By attaching the liquid level sensor at a position close to the water surface, the length of the sensor can be shortened and the component cost can be reduced.

[0016] Also, the liquid level sensor is attached to the upper surface of the heat storage tank, and a sensor locking portion for restricting the upward movement of the liquid level sensor is provided on the upper surface of the heat storage tank. Thereby, the attachment of the liquid level sensor can be easily performed, and the position of the water surface can be accurately detected.

[0017] Also, the liquid level sensor has a protruding piece protruding laterally, and by rotating the liquid level sensor in the horizontal direction, the protruding piece is locked to the sensor locking portion. Since the liquid level sensor can be attached to the heat storage tank only by rotating it, screwing is not required and the workability is improved.

[0018] Furthermore, the overflow channel is connected to the side of the heat storage tank outside the first area. The difference in elevation of the area provided on the top surface of the heat storage tank makes it easy to create a difference in elevation between the replenishment channel and the overflow surface, thus preventing water from the heat storage tank from flowing back into the replenishment channel.

[0019] Furthermore, a guide section is provided in the insulating material covering the outer circumference of the heat storage tank to guide the overflow channel, and the overflow channel is maintained to have an upward slope for a predetermined section from the connection point with the heat storage tank. When steam from the heat storage tank flows into the overflow channel, it is cooled and condensation is generated. The condensation is collected in the heat storage tank by the slope provided in the channel, so a drop in the water level of the heat storage tank can be suppressed. [Examples]

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0021] Figure 1 is a system configuration diagram of the fuel cell device of this embodiment. The fuel cell device 100 includes a fuel cell module 1, and several auxiliary devices such as a first heat exchanger 2, a heat storage tank 3, a condensate tank 4, a radiator 5, an air supply device 14, a fuel supply device 15, and a reformed water supply device 16 are housed within the housing 50 to operate the fuel cell module 1. It is not necessary for all of the above-mentioned devices to be housed within the housing 50; for example, the first heat exchanger 2 and the heat storage tank 3 may be provided outside the housing 50. Furthermore, a fuel cell device in which some of the above-mentioned devices are omitted is also possible.

[0022] The fuel cell module 1 is constructed by housing a fuel cell 11 that generates electricity using fuel gas and oxygen-containing gas, and a reformer 12 that generates the fuel gas supplied to the fuel cell 11, inside a box-shaped storage container 10.

[0023] The configuration of the fuel cell 11 is not particularly limited, but for example, it may have a cell stack structure in which multiple fuel cell cells are arranged. The fuel cell 11 with a cell stack structure is constructed, for example, by fixing the lower end of each fuel cell to a manifold using an insulating bonding material such as a glass seal material.

[0024] The reformer 12 steam reforms raw fuel gases such as natural gas and LPG to produce fuel gas supplied to the fuel cell 11. The reformer 12 is connected to a fuel supply device 15 that supplies raw fuel gas and a reformed water supply device 16 that supplies reformed water. The raw fuel gas and reformed water undergo a reforming reaction in the heated reformer 12 to produce fuel gas containing hydrogen.

[0025] The fuel cell 11 is supplied with fuel gas produced in the reformer 12 and air (oxygen-containing gas) introduced by the air supply device 14. As the fuel gas passes through the fuel cell cell, it reacts with the oxygen-containing gas to generate electricity. The fuel gas and oxygen-containing gas that are not used for power generation merge and burn at the top of the fuel cell 11. This combustion of fuel gas generates high-temperature exhaust gas, which heats the reformer 12. The exhaust gas generated in this way within the fuel cell module 1 is supplied to the first heat exchanger 2.

[0026] The first heat exchanger 2 is connected to a heat storage tank 3, a heat transfer pump P1, and a radiator 5 via piping, forming a first heat transfer circulation line HC1. A heat transfer medium is introduced into this first heat transfer circulation line HC1, and heat exchange takes place between this heat transfer medium and the aforementioned exhaust gas in the first heat exchanger 2, heating the heat transfer medium. Water or other fluids can be used as the heat transfer medium, and the heat storage tank 3 stores the heat transfer medium whose temperature has risen due to heat exchange. The heat transfer medium stored in the heat storage tank 3 is sent to the radiator 5 to be cooled, and after exchanging heat with the exhaust gas again in the first heat exchanger 2, it is returned to the heat storage tank 3. As a result, the heat storage tank 3 accumulates a high-temperature heat transfer medium from the top, forming a temperature stratification. Water is used as the heat transfer medium.

[0027] Furthermore, a condensate tank 4 is connected to the first heat exchanger 2 via a condensate recovery channel 20. When the exhaust gas generated by the fuel cell module 1 is cooled by heat exchange, the water vapor contained in the exhaust gas is separated into water and gas, and the separated water is recovered into the condensate tank 4 through the condensate recovery channel 20. In the condensate tank 4, impurities are removed from the recovered water through an ion exchanger (not shown) and the like to produce pure water. The purified water is supplied to the reformer 12 by a water supply device 16 and used as reformed water. On the other hand, the gas from which the water has been removed is discharged outside the housing 50 after passing through the exhaust channel 21.

[0028] The heat storage tank 3 is connected to an overflow channel 25 and a replenishment channel 26. Drain that overflows from the heat storage tank 3 is discharged outside the housing 50 through the overflow channel 25. The replenishment channel 26 is branched off from a supply channel 27 connected to an external water supply source, and tap water is supplied to the heat storage tank 3 through the replenishment channel 26 when the fuel cell device 100 is installed or when the water level of the heat transfer medium falls below a predetermined level during operation.

[0029] The fuel supply device 15, which supplies raw fuel to the reformer 12, is equipped with auxiliary equipment such as a first solenoid valve 150, a pressure sensor 151, a desulfurizer 152, a gas flow meter 153, a fuel pump 154, and a second solenoid valve 155 on the raw fuel flow path 22 connected to the fuel supply source. The reformed water supply device 16, which supplies reformed water to the reformer 12, is equipped with auxiliary equipment such as a reformed water pump 160 on the reformed water flow path 23 connected to the condensate tank 4. The air supply device 14, which supplies oxygen-containing gas to the fuel cell module 1, is equipped with auxiliary equipment such as an air filter 140, an air flow meter 141, and a blower 142 on the oxygen-containing gas flow path 24. Note that the auxiliary equipment listed here is just an example, and other configurations with other auxiliary equipment are also possible.

[0030] Furthermore, the fuel cell device 100 is equipped with a control device 7 that controls the operation of various devices, as well as a power supply adjustment unit (power conditioner) 8 that converts the DC power generated by the fuel cell module 1 into AC power and adjusts the amount of converted electricity supplied to the external load, and a ventilation fan 17 that takes in ventilation air into the housing 50.

[0031] Furthermore, the fuel cell device 100 includes a second heat exchanger 6, a heat supply pump P2 that circulates the heat medium from the heat storage tank 3, and a second heat medium circulation line HC2 that includes piping connecting these. In the second heat medium circulation line HC2, tap water supplied from the outside via a supply channel 27 is heated in the second heat exchanger 6 using a high-temperature heat medium stored in the heat storage tank 3. The heated water can be supplied via a supply channel 28 to an external reheating device such as a water heater.

[0032] Figure 2 is a perspective view of the heat storage tank of this embodiment, and Figure 3 is an enlarged perspective view of the upper part of the heat storage tank of this embodiment. The heat storage tank 3 is made of resin and is constructed by welding together an upper tank 3a and a lower tank 3b that are molded separately. A channel for draining water from the heat storage tank 3 and a channel for flowing water into the heat storage tank 3 are connected to the side of the heat storage tank 3, and the connection ports for these channels are formed integrally with the heat storage tank 3.

[0033] The heat storage tank 3 is provided with a replenishment port 30 to which the replenishment channel 26 is connected, an overflow port 31 to which the overflow channel 25 is connected, a first inlet 32 ​​to which water flows in and a first outlet 33 to which water flows out, and a second inlet 34 to which water flows in and a second outlet 35 to which water flows out, and a second heat storage tank HC2 is connected. In this embodiment, these connection ports are provided on the same side of the heat storage tank 3, but they may be provided on different sides and can be appropriately arranged considering the arrangement of other auxiliary equipment in the fuel cell device 100.

[0034] Furthermore, a heater 40 for heating the water inside the heat storage tank 3 and a water level sensor 41 for detecting the water level are attached to the top surface of the heat storage tank 3.

[0035] The top surface of the heat storage tank 3 is not flat, but has steps. As a result, the heat storage tank 3 has multiple areas with different top surface heights. The heat storage tank of this embodiment has a first surface 36, a second surface 37, a third surface 38, and a fourth surface 39, in order of increasing top surface height. The area from the first surface 36 to the height of the second surface 37 is designated as the first area A1, the area from the second surface 37 to the height of the third surface 38 is designated as the second area A2, the area from the third surface 38 to the height of the fourth surface 39 is designated as the third area A3, and the area with the fourth surface 39 as the top is designated as the fourth area A4. The heat storage tank 3 is composed of these four areas. The dashed lines in the figure indicate the boundaries of the areas. Note that these areas are apparent divisions assigned to define the structure of the heat storage tank 3 based on the top surface height, and the inside of the tank is not physically partitioned into areas.

[0036] The heat storage tank 3 is a tank that receives water from the outside, and in such a tank, in order to prevent backflow of water, it is stipulated that a discharge port space of a predetermined height be provided between the discharge port and the overflow surface. Therefore, the replenishment port 30 is located higher than the overflow port 31 and is positioned at a predetermined distance corresponding to the discharge port space. Below the overflow port 31, a second outlet 35 and a first inlet 32 ​​are provided, and further below that, a first outlet 33 and a second inlet 34 are provided.

[0037] The refueling port 30 is located in the first area A1, one of several areas. The first area A1 is the area with the highest surface 36 of the heat storage tank 3 as its top surface, and is formed protruding from the heat storage tank 3. In other words, the refueling port 30 can be positioned at a relatively higher position compared to when the top surface of the heat storage tank 3 is flat. Furthermore, in other areas, the height of the top surface of the heat storage tank 3 can be lowered to be closer to the water surface, or in some cases, the top surface height can be lowered below the water surface, thereby reducing the volume of the heat storage tank 3. This makes the fuel cell device 100 more compact, and also reduces the materials used to make up the heat storage tank 3, thereby lowering component costs.

[0038] In this embodiment, an example is shown in which the supply port 30 is provided on the side of the first area A1, but it may also be provided on the top surface (first surface 36) of the first area A1. If it is provided on the side, it is preferable to provide it at as high a position as possible in order to avoid unnecessarily increasing the height of the first area A1.

[0039] The overflow port 31 is located in an area other than the first area A1. The overflow port 31 may be located in any area other than the first area A1, as long as there is a discharge space between it and the supply port 30. By providing it on the side of the heat storage tank 3, excess water can be quickly discharged.

[0040] Furthermore, when comparing the area of ​​each section when viewing the heat storage tank 3 from above, the area of ​​the first section A1 is the smallest among the multiple sections. This allows for a further reduction in the materials used to construct the heat storage tank 3, thereby lowering component costs.

[0041] The heater 40 is located in the second area A2 and is attached to the second surface 37, which is the upper surface of the second area A2. Figure 4 is a structural diagram of the heater that heats the heat transfer medium. The heater 40 consists of a U-shaped heater body 402 equipped with a heating element 401 and a heater mounting bracket 403 that connects the heater body 402 to the heat storage tank 3, and heats the water by immersing the heating element 401 in water. An opening (not shown) is formed in the second surface 37, and the heater 40 is attached to the heat storage tank 3 by inserting the heater body 402 through the opening and screwing the heater mounting bracket 403 to the second surface 37. The second surface 37 is closer to the water surface than the first surface 36, and by attaching the heater 40 to the surface closer to the water surface, the length of the heater body 402 can be shortened and the cost of parts can be reduced.

[0042] Figure 5 shows a heater locking member that secures the heater. While the heat storage tank 3 can be made of resin to reduce weight, if the heater 40 malfunctions, the heat could melt the resin, potentially causing the heater 40 to fall. Therefore, a heater locking member 42 is provided to prevent the heater 40 from falling in such a situation. The heater locking member 42 secures the wiring (not shown) electrically connected to the heater 40 at a position higher than the heat storage tank 3. For example, the wiring can be secured by wrapping it around a frame that constitutes the housing 50. The figure shows an example where the heater locking member 42 is attached to a frame 51 that secures the upper part of the exterior panel and the wiring is suspended from it. However, it is not limited to this, and it may also be secured to a frame to which auxiliary equipment is attached. Note that the heater locking member 42 does not come into contact with the high-temperature parts of the heater 40, so its material is not particularly limited. Its shape is also not limited; it only needs to be able to secure the wiring, and commonly used nylon bands for bundling wiring can be used.

[0043] The water level sensor 41 is installed in the third area A3 and is mounted on the third surface 38, which is the upper surface of the third area A3. Figure 6 shows the mounting state of the water level sensor for detecting the water level of the heat storage tank. The water level sensor 41 in this embodiment is an electrode-type sensor and comprises two electrode parts 411 for detecting the water level and a holding part 412 for holding these electrode parts 411. The holding part 412 is circular and has two protruding pieces 413 that project laterally from its outer circumference. An opening (not shown) is formed in the third surface 38, and the electrode parts 411 are inserted through the opening. The third surface 38 is closer to the water surface than the first surface 36, and by mounting the water level sensor 41 in a position close to the water surface, the length of the electrode parts 411 can be shortened and component costs can be reduced. Note that the detection method of the water level sensor 41 is not limited to the electrode type, but may also be a float type or an optical type.

[0044] Furthermore, the third surface 38 is provided with a sensor locking portion 43 for locking the protruding piece 413 of the water level sensor 41. The sensor locking portion 43 is located above the protruding piece 413 and restricts the upward movement of the water level sensor 41, thereby enabling accurate detection of the water level. When installing the water level sensor 41, the protruding piece 413 is locked to the sensor locking portion 43 by rotating the holding portion 412 horizontally. This allows for easy installation of the water level sensor 41.

[0045] By the way, in this embodiment, we have shown an example in which a second area A2 and a third area A3 are provided in the heat storage tank 3, with a heater 40 installed in the second area A2 and a water level sensor 41 installed in the third area A3. However, the arrangement of the heater 40 and the water level sensor 41 may be reversed, or the second area A2 and the third area A3 may be at the same height without any difference in elevation. In other words, as long as the replenishment port 30 is provided in the first area A1, which is at the highest position, and the heater 40 and the water level sensor 41 are installed outside this first area A1, the positional relationship between the heater 40 and the water level sensor 41 is not particularly limited.

[0046] A ventilation fan 17 is installed on the fourth surface 39. The fourth area A4 is an area provided to secure space for housing the duct of the ventilation fan 17. In this way, a step can be created on the upper surface of the heat storage tank 3 to create space for arranging auxiliary equipment. The space inside the housing 50 can be effectively utilized to make the fuel cell device 100 compact.

[0047] Figure 7 illustrates the shape of the insulating member attached to the heat storage tank. An insulating member 80 is attached around the heat storage tank 3 to suppress heat release from the heat storage tank 3. This insulating member 80 has irregularities formed in various places, and also serves to absorb vibrations during transportation and to hold components in place.

[0048] The heat insulating member 80 has a guide portion 81 that guides the overflow channel 25. The guide portion 81 is an uneven surface provided on the heat insulating member 80 that holds the overflow channel 25 so that it slopes upward in a predetermined section L from the connection point with the heat storage tank 3. When water vapor generated in the heat storage tank 3 flows into the overflow channel 25, it is cooled and condensation occurs. The condensation is collected in the heat storage tank 3 by the slope of the overflow channel 25, so that the water level in the heat storage tank 3 does not drop. In addition, because the outlet space is defined, the height of the overflow channel 25 must not exceed the height of the outlet space, but the height of the overflow channel 25 is also restricted by the guide portion 81, so that the outlet space can be secured. [Explanation of Symbols]

[0049] 3. Heat storage tank 11 Fuel Cell 25 Overflow channel 26 Supply routes 40 Heater 41. Water level sensor (liquid level sensor) 413 Projecting piece 42 Heater locking member 43 Sensor locking part 80 Insulation material 81 Guide section A1 Area 1

Claims

1. A fuel cell that generates electricity using fuel gas and oxygen-containing gas, A heat storage tank for storing a heat transfer medium to recover waste heat from the fuel cell, The heat storage tank has a supply channel for supplying the heat transfer medium, An overflow channel for discharging excess heat transfer medium from the heat storage tank, The heat storage tank comprises an insulating member that covers the outer periphery of the heat storage tank, The heat storage tank has multiple areas with different upper surface heights, and the supply channel is connected to a supply port located in the first area, which has the highest upper surface height among the multiple areas. The overflow channel is connected to the side of the heat storage tank outside the first area, The heat insulating member has a guide portion that guides the overflow channel, The guide portion holds the overflow channel in an upward slope at a height that does not exceed the supply port in a predetermined section from the connection point with the heat storage tank.

2. The fuel cell device according to claim 1, wherein, in a top view of the heat storage tank, the area of ​​the first area is the smallest among the plurality of areas.

3. The system further comprises a heater for heating the heat transfer medium. The fuel cell apparatus according to claim 1 or 2, wherein the heater is connected to the heat storage tank outside the first area.

4. The aforementioned heat storage tank is made of resin, The heater is mounted on the upper surface of the heat storage tank. The fuel cell apparatus according to claim 3, further comprising a heater locking member for locking wiring electrically connected to the heater at a position higher than the heat storage tank.

5. The system further includes a liquid level sensor for detecting the liquid level height of the heat transfer medium, The fuel cell apparatus according to claim 1 or 2, wherein the liquid level sensor is connected to the heat storage tank outside the first area.

6. The liquid level sensor is mounted on the upper surface of the heat storage tank. The fuel cell apparatus according to claim 5, wherein a sensor locking portion is provided on the upper surface of the heat storage tank for restricting the upward movement of the liquid level sensor.

7. The liquid level sensor has a protruding piece that extends laterally, The fuel cell apparatus according to claim 6, wherein the protruding piece is locked to the sensor locking portion by rotating the liquid level sensor in a horizontal direction.

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