Fuel cell system

Abstract

The present invention provides a fuel cell system that minimizes the reduction in heat recovery efficiency when recovering heat from the fuel cell stack using cooling water. [Solution] The fuel cell system 1a comprises a fuel cell stack 10, a fuel processor 20, a reformed water tank 31, and a cooling water tank 32. The fuel cell stack 10 generates electricity by reacting hydrogen and oxygen. The reformed water tank 31 and the cooling water tank 32 are formed inside a single container 30. The container 30 has an insulating structure 35. The insulating structure 35 separates the reformed water tank 31 and the cooling water tank 32.

Description

Technical Field

[0001] The present disclosure relates to a fuel cell system.

Background Art

[0002] Patent Document 1 describes a fuel cell package including a water storage tank in which a condensed water tank, a battery cooling water tank, and a pure water tank are integrally formed. Pure water accumulated in the pure water tank is supplied as reforming water to a fuel reforming system via a pump. Circulating water in the battery cooling water tank is circulated and introduced into the fuel cell main body as battery cooling water.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] The conventional technology leaves room for re-examination from the viewpoint of making it difficult to reduce heat recovery efficiency when recovering heat from the fuel cell stack through heat exchange with cooling water.

Means for Solving the Problem

[0005] The fuel cell system according to the present disclosure includes: a fuel cell stack that generates power by reacting hydrogen and oxygen; a fuel processor that generates hydrogen-containing gas through a reforming reaction between a raw material gas and water, and supplies the hydrogen-containing gas to the fuel cell stack; a reforming water tank that stores the water to be supplied to the fuel processor; a cooling water tank that stores cooling water for cooling the fuel cell stack; wherein the reforming water tank and the cooling water tank are formed inside a single container, The container has an insulating structure that separates the reformed water tank and the cooling water tank. [Effects of the Invention]

[0006] According to this disclosure, when recovering heat from the fuel cell stack by heat exchange with cooling water, it is less likely to reduce the heat recovery efficiency. [Brief explanation of the drawing]

[0007] [Figure 1] Configuration diagram of the fuel cell system in Embodiment 1 [Figure 2] Configuration diagram of the fuel cell system in Embodiment 2 [Figure 3] A flowchart showing an example of control of the fuel cell system in Embodiment 2.

[0008] (Knowledge and other information that formed the basis of this disclosure) At the time the inventors conceived of this disclosure, it was known that in a fuel cell system, a tank for storing cooling water to cool the fuel cell stack and a tank for storing reformed water for reforming the raw gas were integrated into one unit. Such an configuration simplifies the fuel cell system and allows for both reliability and economic efficiency.

[0009] Reformed water is supplied to reform the raw gas, and when the amount of reformed water stored in the tank decreases, the tank is replenished with reformed water. If the tank for storing cooling water to cool the fuel cell stack and the tank for storing reformed water for reforming the raw gas are integrated, the cooling water stored in the tank may be cooled by the reformed water when it is replenished. This can cause the temperature of the cooling water to decrease. A decrease in the temperature of the cooling water can reduce the efficiency of heat recovery when recovering heat from the fuel cell stack through heat exchange with the cooling water. Furthermore, the power required to drive the device may increase to compensate for the reduced heat recovery efficiency, potentially reducing the power generation efficiency.

[0010] The inventors focused on a structure for partitioning a tank when integrally constructing a tank for storing cooling water to cool a fuel cell stack and a tank for storing reformed water for reforming the raw material gas, and thus arrived at the subject of this disclosure.

[0011] This disclosure provides a fuel cell system that is less likely to reduce heat recovery efficiency when recovering heat from the fuel cell stack with cooling water.

[0012] The embodiments will be described in detail below with reference to the drawings. However, unnecessary details may be omitted. For example, detailed explanations of already well-known matters or redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding for those skilled in the art.

[0013] The attached drawings and the following description are provided to help the parties fully understand this disclosure and are not intended to limit the subject matter described in the claims.

[0014] (Embodiment 1) Embodiment 1 will be described below with reference to Figure 1.

[0015] [1-1. Structure] Figure 1 is a diagram of the fuel cell system in Embodiment 1. As shown in Figure 1, the fuel cell system 1a comprises a fuel cell stack 10, a fuel processor 20, a reformed water tank 31, and a cooling water tank 32. The fuel cell stack 10 generates electricity by reacting hydrogen and oxygen. The fuel cell stack 10 comprises, for example, an electrolyte membrane, an anode, and a cathode. An electrolyte membrane is placed between the anode and the cathode. The anode and cathode are each provided with a catalyst to promote the reaction of extracting electrons. A hydrogen-containing gas supply path 12 is connected to the anode. An oxygen-containing gas supply path (not shown) is connected to the cathode. Hydrogen-containing gas H is supplied to the anode through the hydrogen-containing gas supply path 12. Oxygen-containing gas is supplied to the cathode from an oxygen-containing gas supply source through the oxygen-containing gas supply path.

[0016] The fuel processor 20 generates hydrogen-containing gas H through a reforming reaction between raw material gas F and water, and supplies the hydrogen-containing gas H to the fuel cell stack 10. The raw material gas F is, for example, a gas containing hydrocarbons such as methane and propane. In the fuel processor 20, for example, steam reforming and CO modification occur in the raw material gas F, generating hydrogen-containing gas H. The fuel processor 20 is equipped with, for example, a catalyst for steam reforming of the raw material gas F and a CO modification catalyst. A hydrogen-containing gas supply path 12 extends between the fuel processor 20 and the anode of the fuel cell stack 10.

[0017] As shown in Figure 1, the reformed water tank 31 and the cooling water tank 32 are formed inside a single container 30. In other words, the reformed water tank 31 and the cooling water tank 32 are integrally constructed. The container 30 has an insulating structure 35. The insulating structure 35 separates the reformed water tank 31 and the cooling water tank 32. With this configuration, the temperature of the cooling water stored in the cooling water tank 32 is less likely to decrease due to the reformed water supplied to the reformed water tank 31.

[0018] The heat insulating structure 35 is not limited to a specific heat insulating structure. The heat insulating structure 35 has, for example, an air layer 35a. According to this configuration, the temperature of the cooling water stored in the cooling water tank 32 is less likely to be lowered by the reformed water supplied to the reformed water tank 31.

[0019] The heat insulating structure 35 includes, for example, a recess 35r. The recess 35r is in contact with the outer surface of the container 30 at the bottom of the container 30 and opens downward toward the container 30. The recess 35r includes the air layer 35a. According to this configuration, the heat insulating structure 35 can be easily manufactured by blow molding or the like.

[0020] The size of the recess 35r is not limited to a specific value. The width of the recess 35r is, for example, 0.1 mm or more and 10 mm or less.

[0021] Materials for the container 30 and the heat insulating structure 35 are not limited to specific materials. The container 30 and the heat insulating structure 35 are made of resin, for example. According to this configuration, the heat insulating structure 35 easily has high heat insulating properties.

[0022] As shown in FIG. 1, the fuel cell system 1a includes, for example, a cooling water path 32a, a reformed water introduction path 31a, a reformed water supply path 31b, a condensed water tank 36, a condensed water recovery path 36a, a condensed water supply path 36b, a deionizer 40, and a controller 50. The fuel cell system 1a further includes, for example, a heat exchanger 15, a hot water supply unit 70, and a heat medium path 70a.

[0023] The cooling water path 32a is connected to the cooling water tank 32 and the fuel cell stack 10, and extends so that the cooling water circulates between the cooling water tank 32 and the fuel cell stack 10. The heat exchanger 15 exchanges heat between the cooling water that has passed through the fuel cell stack 10 and the heat transfer medium flowing through the heat transfer medium path 70a. The heat exchanger 15 is a liquid-liquid heat exchanger, such as a double-tube heat exchanger, a shell-and-tube heat exchanger, or a plate heat exchanger. The heat exchanger 15 is configured such that, for example, the flow of cooling water and the flow of heat transfer medium are countercurrent. Part of the cooling water path 32a and part of the heat transfer medium path 70a extend inside the heat exchanger 15. The heat transfer medium is, for example, water.

[0024] The heat transfer medium path 70a is connected, for example, to the hot water storage unit 70. Cooling water that has recovered heat from the fuel cell stack 10 by passing through the fuel cell stack 10 exchanges heat with the heat transfer medium in the heat exchanger 15. This heats the heat transfer medium. The heat transfer medium that has passed through the heat exchanger 15 is supplied to and stored in the hot water storage unit. The heat transfer medium stored in the hot water storage unit is supplied to the outside of the hot water storage unit according to the hot water demand.

[0025] The condensate recovery channel 36a is connected to the condensate tank 36. Condensate generated in the fuel cell system 1a is stored in the condensate tank 36 via the condensate recovery channel 36a. Condensate is generated, for example, by the condensation of water vapor contained in the off-gas discharged from the fuel cell stack 10 and the fuel processor 20.

[0026] The condensate supply channel 36b connects the condensate tank 36 to the deionizer 40. The reformed water introduction channel 31a connects the deionizer 40 to the reformed water tank 31. Inside the deionizer 40, for example, an ion exchange resin is arranged. The condensate stored in the condensate tank 36 is supplied to the deionizer 40 through the condensate supply channel 36b. In the deionizer 40, unwanted ions are removed from the condensate, and reformed water suitable for reforming the raw material gas F is produced. The produced reformed water is supplied to the reformed water tank 31 through the reformed water introduction channel 31a and stored there.

[0027] The reformed water supply channel 31b connects the reformed water tank 31 and the fuel processor 20. The reformed water stored in the reformed water tank 31 is supplied to the fuel processor 20 through the reformed water supply channel 31b and used in the reforming reaction of the raw material gas F.

[0028] The controller 50 controls equipment such as pumps, valves, and blowers included in the fuel cell system 1a. The controller 50 is, for example, a DSP (Digital Signal Processor) that includes an arithmetic circuit and a memory circuit. An example of an arithmetic circuit is a CPU. An example of a memory circuit is a memory. The control program for the fuel cell system 1a is stored in the memory circuit.

[0029] [1-2. Operation] The operation and function of the fuel cell system 1a, configured as described above, will be explained below.

[0030] When the fuel cell system 1a is in operation, raw material gas F is supplied to the fuel processor 20, and hydrogen-containing gas H is produced by a reforming reaction between the raw material gas F and water. For this reforming reaction, reformed water stored in the reformed water tank 31 is supplied to the fuel processor 20 through the reformed water supply passage 31b. As the reforming of the raw material gas F reduces the amount of reformed water stored in the reformed water tank 31, it is necessary to replenish the reformed water tank 31. For example, condensed water stored in the condensed water tank 36 is supplied to the deionizer 40, where unwanted ions are removed from the condensed water to produce reformed water, and the produced reformed water is replenished to the reformed water tank 31.

[0031] The hydrogen-containing gas H generated in the fuel processor 20 is supplied to the anode of the fuel cell stack 10. In addition, oxygen-containing gas is supplied to the cathode of the fuel cell stack 10. As a result, hydrogen and oxygen react in the fuel cell stack 10 to generate electricity. This generates heat in the fuel cell stack 10. Cooling water stored in the cooling water tank 32 cools the fuel cell stack 10 through the cooling water path 32a so that the fuel cell stack 10 is kept within the desired temperature range. After that, the cooling water that has recovered the heat from the fuel cell stack 10 exchanges heat with the heat medium flowing through the heat medium path 70a in the heat exchanger 15. As a result, the heat contained in the cooling water is recovered by the heat medium. The cooling water whose temperature has decreased after passing through the heat exchanger 15 is returned to the cooling water tank 32.

[0032] (Embodiment 2) Embodiment 2 will be described below with reference to Figures 2 and 3.

[0033] [2-1. Structure] Figure 2 is a diagram showing the configuration of the fuel cell system 1b in Embodiment 2. As shown in Figure 2, the fuel cell system 1b is configured similarly to the fuel cell system 1a, except for parts that are not specifically described. Components of the fuel cell system 1b that are the same as or correspond to components of the fuel cell system 1a are denoted by the same reference numerals, and detailed descriptions are omitted. The description of the fuel cell system 1a also applies to the fuel cell system 1b, to the extent that it does not technically contradict the description.

[0034] As shown in Figure 2, in the fuel cell system 1b, the thermal insulation structure 35 of the container 30 is provided with a plurality of partitions 35p. The plurality of partitions 35p extend from the inner surface of the container 30 toward the top of the container 30 at the bottom of the container 30. The plurality of partitions 35p are separated from the top of the container 30. An air layer 35a is formed between the plurality of partitions 35p.

[0035] The fuel cell system 1b further includes, for example, a drain channel 35d and a drain valve 35v. The drain channel 35d communicates with the space 35s between a plurality of partitions. The drain valve 35v is located in the drain channel 35d. The drain valve 35v is, for example, an on / off valve. The drain channel 35d is connected to, for example, a condensate tank 36.

[0036] [2-2. Operation] The operation and function of the fuel cell system 1b, configured as described above, will be explained below.

[0037] Figure 3 is a flowchart illustrating an example of control of the fuel cell system in Embodiment 2. This control is performed, for example, when the fuel cell system 1b is first used.

[0038] When the fuel cell system 1b is used for the first time, the reformed water tank 31 and the cooling water tank 32 are empty. Therefore, in step S11, reformed water and cooling water are supplied from an external source. Next, in step S12, the controller 50 determines whether the supply of water to the reformed water tank 31 and the cooling water tank 32 is complete. If the determination in step S12 is positive, the controller 50 sends a control signal to the drain valve 35v and opens the drain valve 35v. Water supplied to the reformed water tank 31 and the cooling water tank 32 may unintentionally be directed into space 35s. Water that has been mistakenly directed into space 35s is discharged to the outside of the container 30 through the drain channel 35d when the drain valve 35v opens. This control may also be performed when the fuel cell system 1b is shut down after it has become operational and the water level in the cooling water tank 32 has fallen below a predetermined level. Alternatively, this control may be performed when the fuel cell system 1b is shut down when the total operating time of the fuel cell system 1b exceeds a predetermined time. In these cases, in step S11, only cooling water may be supplied from an external source.

[0039] (Other embodiments) As described above, Embodiments 1 and 2 have been explained as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited to these and can be applied to embodiments that have been modified, replaced, added, omitted, etc. Furthermore, it is possible to create new embodiments by combining the components described in the above embodiments.

[0040] For example, in Embodiment 2, the thermal insulation structure 35 may have three or more partitions 35p. In this case, multiple spaces 35s may be formed. Multiple drainage channels 35d may be formed corresponding to the multiple spaces 35s, and multiple drainage valves 35v may be formed in each of the multiple drainage channels 35d. Alternatively, through holes connecting the multiple spaces 35s may be formed near the bottom of the container 30, and the structure may be configured so that water collects in one of the multiple spaces 35s. In this case, one drainage valve 35v may be placed in one drainage channel 35d. Furthermore, the thermal insulation structure 35 may have a solid filling in the air layer 35a, or the thermal insulation structure 35 may not have an air layer 35a. For example, the thermal insulation structure 35 may be made of a solid material having a lower thermal conductivity than the thermal conductivity of the material in the parts of the container 30 other than the thermal insulation structure 35.

[0041] Since the embodiments described above are for illustrative purposes of the technology described herein, various modifications, substitutions, additions, omissions, etc., can be made within the scope of the claims or equivalents thereof.

[0042] (Note) Based on the above description of embodiments, the following technologies are disclosed.

[0043] (Technology 1) A fuel cell stack that generates electricity by reacting hydrogen and oxygen, A fuel processor that generates a hydrogen-containing gas through a reforming reaction between a raw material gas and water, and supplies the hydrogen-containing gas to the fuel cell stack, A reformed water tank for storing the water supplied to the fuel processor, The fuel cell stack is equipped with a cooling water tank for storing cooling water, The reformed water tank and the cooling water tank are formed inside a single container. The container has an insulating structure that separates the reformed water tank and the cooling water tank. Fuel cell system.

[0044] According to the fuel cell system of Technology 1, the cooling water stored in the cooling water tank is cooled by the supplied reformed water, and the decrease in the temperature of the cooling water is easily suppressed by the insulating structure of the container. As a result, the heat recovery efficiency does not tend to decrease when recovering heat from the fuel cell stack through heat exchange with the cooling water.

[0045] (Technology 2) The aforementioned thermal insulation structure has an air layer, The fuel cell system described in Technology 1.

[0046] According to the fuel cell system of Technology 2, the insulated structure is more likely to exhibit high insulation performance, and the decrease in the temperature of the cooling water stored in the cooling water tank due to the replenished reformed water is more easily suppressed.

[0047] (Technology 3) The aforementioned heat insulating structure has a recess at the bottom of the container that is in contact with the outer surface of the container and opens downward, The recess includes the air layer. The fuel cell system described in Technology 2.

[0048] According to the fuel cell system of Technology 3, the aforementioned thermal insulation structure can easily achieve high thermal insulation performance with a relatively simple configuration. Therefore, the decrease in the temperature of the cooling water stored in the cooling water tank due to the replenished reformed water is more easily suppressed. In addition, the container is easy to manufacture.

[0049] (Technology 4) The aforementioned heat insulating structure comprises a plurality of partitions at the bottom of the container, extending from the inner surface of the container toward the top of the container. The aforementioned multiple partitions are separated from the top of the container. The air layer is formed between the plurality of partitions. The fuel cell system described in Technology 2.

[0050] According to the fuel cell system of Technology 4, the aforementioned thermal insulation structure can easily achieve high thermal insulation performance with a relatively simple configuration. Therefore, the decrease in the temperature of the cooling water stored in the cooling water tank due to the replenished reformed water is more easily suppressed.

[0051] (Technology 5) It is equipped with a drainage channel that communicates with the space between the aforementioned multiple partitions, The fuel cell system described in Technology 4.

[0052] According to the fuel cell system of Technology 5, even if water is unintentionally introduced into the space between multiple partitions due to the supply of reformed water or cooling water, the water can be discharged to the outside of this space. This makes it easier for the insulated structure to exhibit high thermal insulation performance, and it is easier to suppress the decrease in the temperature of the cooling water stored in the cooling water tank due to the replenished reformed water.

[0053] (Technology 6) The drainage channel is equipped with a drain valve, The fuel cell system described in Technology 5.

[0054] According to the fuel cell system of Technology 6, even if water is unintentionally introduced into the space between multiple partitions due to the supply of reformed water or cooling water, the water can be discharged to the outside of this space at a predetermined time. As a result, the insulated structure can more easily exhibit high insulation performance, and the decrease in the temperature of the cooling water stored in the cooling water tank due to the replenished reformed water is more easily suppressed.

[0055] (Technology 7) The container and the heat insulating structure are made of resin. A fuel cell system as described in any of the technologies 1 to 6.

[0056] According to the fuel cell system of Technology 7, the insulated structure is more likely to exhibit high insulation performance, and the decrease in the temperature of the cooling water stored in the cooling water tank due to the replenished reformed water is more easily suppressed. [Industrial applicability]

[0057] The technology described herein is applicable to fuel cell systems that use reformed water and cooling water. [Explanation of Symbols]

[0058] 1a, 1b Fuel cell systems 10 Fuel Cell Stacks 20 Fuel processor 30 containers 31. Reconditioned water tank 32 Cooling water tank 35 Insulated structure 35a Air layer 35d drainage canal 35r recess 35s space 35p divider 35V drain valve

Claims

1. A fuel cell stack that generates electricity by reacting hydrogen and oxygen, A fuel processor that generates a hydrogen-containing gas through a reforming reaction between a raw material gas and water, and supplies the hydrogen-containing gas to the fuel cell stack, A reformed water tank for storing the water supplied to the fuel processor, The fuel cell stack is equipped with a cooling water tank for storing cooling water, The reformed water tank and the cooling water tank are formed inside a single container. The container has an insulating structure that separates the reformed water tank and the cooling water tank. Fuel cell system.

2. The aforementioned thermal insulation structure has an air layer, The fuel cell system according to claim 1.

3. The aforementioned heat insulating structure has a recess at the bottom of the container that is in contact with the outer surface of the container and opens downward, The recess includes the air layer. The fuel cell system according to claim 2.

4. The aforementioned heat insulating structure comprises a plurality of partitions at the bottom of the container, extending from the inner surface of the container toward the top of the container. The aforementioned multiple partitions are separated from the top of the container. The air layer is formed between the plurality of partitions. The fuel cell system according to claim 2.

5. It is equipped with a drainage channel that communicates with the space between the aforementioned multiple partitions, The fuel cell system according to claim 4.

6. The drainage channel is equipped with a drain valve, The fuel cell system according to claim 5.

7. The container and the heat insulating structure are made of resin. The fuel cell system according to claim 1.

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