Hydrogen generation equipment and hydrogen power generation equipment

Abstract

Rapidly increase hydrogen pressure to the target pressure. [Solution] The hydrogen generation device 2 comprises a plurality of hydrogen containers 3 each containing granular material H made of a hydrogen storage alloy with different particle sizes, a water supply device 4 configured to supply water individually to the plurality of hydrogen containers, a pressure sensor 5 for detecting the pressure of hydrogen produced by the reaction of the granular material and water, and a control unit 6 configured to control the water supply device based on the detected pressure detected by the pressure sensor. When the detected pressure rises toward a predetermined target pressure, the control unit controls the water supply device so that the hydrogen container to which water is supplied is changed according to the difference between the detected pressure and the target pressure.

Description

Technical Field

[0001] The present disclosure relates to a hydrogen generation device and a hydrogen power generation device.

Background Art

[0002] As one of the measures against global warming, it is known to use a fuel cell. A fuel cell is a device that generates electricity by chemically reacting hydrogen and oxygen existing in nature. By using a fuel cell, electricity can be generated without relying on fossil fuels, and the emission of carbon dioxide, which causes global warming, can be suppressed. In practice, power generation is performed by supplying hydrogen generated by a hydrogen generation device to a fuel cell stack.

[0003] Regarding hydrogen generation devices, those that generate hydrogen by supplying water to a granular material made of a hydrogen storage alloy and chemically reacting the granular material with water are known (see, 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] By the way, when starting the operation of a fuel cell, it is necessary to increase the pressure of hydrogen generated by a hydrogen generation device to a predetermined target pressure.

[0006] However, depending on the size of the granular material, there is a problem that the reaction rate decreases and it takes time to increase the hydrogen pressure to the target pressure.

[0007] Therefore, in view of such circumstances, the present disclosure was conceived, and its object is to provide a hydrogen generation device and a hydrogen power generation device that can rapidly increase the hydrogen pressure to the target pressure. [Means for solving the problem]

[0008] According to one aspect of this disclosure, Multiple hydrogen containers, each containing powders and granules of different particle sizes made of hydrogen storage alloys, A water supply device configured to supply water individually to multiple hydrogen containers, A pressure sensor for detecting the pressure of hydrogen produced by the reaction of powder and water, A control unit configured to control the water supply device based on the detected pressure detected by the pressure sensor, Equipped with, The control unit controls the water supply device so that when the detected pressure rises toward a predetermined target pressure, the hydrogen container to which water is supplied is changed according to the difference between the detected pressure and the target pressure. A hydrogen generation device characterized by the above is provided.

[0009] Preferably, the control unit controls the water supply device such that the greater the difference, the more water is supplied to the hydrogen container containing the finer particle size powder.

[0010] Preferably, the water supply device is provided for each hydrogen container and has a solenoid valve that controls the supply of water to the hydrogen container. The control unit changes which solenoid valve is opened according to the difference between the detected pressure and the target pressure.

[0011] Preferably, the number of hydrogen containers that contain large-grained powders is greater than the number of hydrogen containers that contain small-grained powders.

[0012] Preferably, the hydrogen storage alloy is magnesium hydride.

[0013] According to other aspects of this disclosure, The hydrogen generation apparatus and, A fuel cell stack that generates electricity using hydrogen produced by the hydrogen generation device, A hydrogen power generation device characterized by including

Advantages of the Invention

[0014] According to the present disclosure, the hydrogen pressure can be rapidly increased to the target pressure.

Brief Description of the Drawings

[0015] [Figure 1] It is a schematic diagram showing the hydrogen power generation device of the present embodiment. [Figure 2] It is a time chart showing the content of the control of the present embodiment. [Figure 3] It is a flowchart showing the content of the control of the present embodiment.

Modes for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Note that it should be noted that the present disclosure is not limited to the following embodiments.

[0017] FIG. 1 is a schematic diagram showing a hydrogen power generation device of the present embodiment. The hydrogen power generation device 100 includes a fuel cell stack 1 that substantially generates electricity (hereinafter also referred to as FC), and a hydrogen generation device 2 that generates hydrogen (specifically, hydrogen gas) supplied to the FC stack 1.

[0018] The hydrogen generation device 2 includes a plurality of hydrogen containers 3 each containing powder particles H made of a hydrogen storage alloy and having different particle sizes, a water supply device 4 configured to individually supply water to the plurality of hydrogen containers 3, a pressure sensor 5 for detecting the pressure of hydrogen generated by the reaction of the powder particles H and water, and a control unit (ECU 6) configured to control the water supply device 4 based on the detected pressure detected by the pressure sensor 5.

[0019] In this embodiment, hydrogen is generated using a hydrogen storage alloy that is easy to handle and has high safety. The hydrogen storage alloy of this embodiment is magnesium hydride (MgH₂). This hydrogen storage alloy is formed and processed into granular material H and used as a material for hydrogen generation.

[0020] In this embodiment, six hydrogen containers 3 are provided. On the other hand, three types of granular material H with large, medium, and small particle sizes are prepared. Here, a large particle size means that the average particle diameter of the granular material H is large, and the granular material H is large-grained or coarse-meshed. Similarly, a medium particle size means that the average particle diameter of the granular material H is medium, and the granular material H is medium-grained or medium-meshed. A small particle size means that the average particle diameter of the granular material H is small, and the granular material H is small-grained or fine-meshed.

[0021] In this embodiment, the hydrogen container 3 with small particle size granular material H is accommodated in one hydrogen container 3, the hydrogen container 3 with medium particle size granular material H is accommodated in one hydrogen container 3, and the hydrogen container 3 with large particle size granular material H is accommodated in four hydrogen containers 3. The six hydrogen containers 3 are numbered #1 to #6 respectively. The #1 container contains granular material H with small particle size, the #2 container contains granular material H with medium particle size, and the #3 to #6 containers contain granular material H with large particle size.

[0022] The hydrogen container 3 has a form such as a detachable and replaceable cartridge or pack. Granular material H is deposited at the lower part inside the hydrogen container 3. Water is supplied to this granular material H, and the hydrogen storage alloy is hydrolyzed to generate hydrogen gas. The space above the granular material H becomes a gas storage space for storing the generated hydrogen gas. Thus, the hydrogen container 3 has a function as a storage container for accommodating the granular material H, a function as a reaction container for reacting the granular material H and water, and a function as a gas storage container for storing the generated hydrogen gas.

[0023] The control unit consists of an electronic control unit (ECU) 6. The ECU 6 includes a CPU (Central Processing Unit) with arithmetic functions, ROM (Read Only Memory) and RAM (Random Access Memory) as storage media, input / output ports, and other storage devices besides ROM and RAM.

[0024] The water supply system 4 includes a water tank 7 for storing water, water piping 8 for distributing and supplying water from the water tank 7 to each hydrogen container 3, a water filter 9 provided at the upstream manifold 8A of the water piping 8 for purifying the water sent from the water tank 7, and solenoid valves 10 provided at each branch pipe 8C of the downstream branch 8B of the water piping 8. The water flow is indicated by a solid arrow and denoted by the symbol W.

[0025] A solenoid valve 10 is provided individually for each hydrogen container 3. The opening and closing of the solenoid valve 10 controls the supply of water to the corresponding hydrogen container 3. In this embodiment, water is supplied from the water tank 7 to the hydrogen container 3 by gravity, so a water pump is omitted. However, a water pump may be provided to forcibly supply water.

[0026] When water is supplied, the ECU 6 opens the solenoid valve 10 for a predetermined time at predetermined intervals (i.e., in a pulsed manner). The longer the solenoid valve 10 is open, the greater the amount of water supplied per valve opening. When the solenoid valve 10 is opened, water is dripped onto the granular material H in the hydrogen container 3.

[0027] Meanwhile, hydrogen piping 11 is provided to transport hydrogen from each hydrogen container 3 to the FC stack 1. The hydrogen piping 11 has an upstream branch section 11A and a downstream manifold section 11B, and the upstream branch section 11A has a plurality (6) of branch pipes 11C connected to each hydrogen container 3. The hydrogen flow is indicated by a dashed arrow and denoted by the symbol H2.

[0028] The downstream end of the downstream manifold 11B of the hydrogen piping 11 is connected to the hydrogen input section of the FC stack 1. The downstream manifold 11B is equipped with, in order from the upstream side, a hydrogen filter 12, a relief valve 13, a pressure sensor 5, a regulator 14, and a flow sensor 15.

[0029] The hydrogen filter 12 removes water vapor mixed with the hydrogen. The relief valve 13 opens to release pressure if the hydrogen pressure rises abnormally. The pressure sensor 5 detects the hydrogen pressure. The regulator 14 adjusts the hydrogen pressure to a pressure suitable for supply to the FC stack 1. The flow sensor 15 detects the flow rate of hydrogen supplied to or introduced into the FC stack 1.

[0030] As is well known, the FC stack 1 is a device that generates electricity by reacting supplied hydrogen with oxygen from the atmosphere. A capacitor 16 is connected to the output section of the FC stack 1 as an energy storage device, and the electricity generated by the FC stack 1 is stored in the capacitor 16. The flow of electricity is shown by a thick solid arrow and is denoted by the symbol E.

[0031] An electrical load 17, consisting of electrical equipment, is connected to the capacitor 16. In the diagram, three electrical loads 17 are connected, but the number of electrical loads 17 is arbitrary. For example, when the hydrogen power generation device 100 is used as an emergency generator, the electrical loads 17 can be electrical appliances, such as a washing machine, a fan, or a mobile phone charger.

[0032] The power output from the FC stack 1 may be supplied to the ECU 6 via a transformer (not shown), and the FC stack 1 may be used as the power source for the ECU 6. Similarly, the capacitor 16 may be used as the power source for the ECU 6. Naturally, the solenoid valve 10, pressure sensor 5, and flow sensor 15 are electrically connected to the ECU 6.

[0033] Now, when starting operation of the hydrogen power generation device 100 or the FC stack 1, it is necessary to raise the pressure of the hydrogen produced in the hydrogen generator 2 to a predetermined target pressure.

[0034] In other words, in order to operate the FC stack 1, the pressure of the input hydrogen must be within a predetermined input pressure range, and the regulator 14 is configured to adjust the hydrogen pressure to such an input pressure range. Therefore, the regulator 14 must be supplied with hydrogen having a pressure value equal to or greater than the upper limit of the input pressure range. When the FC stack 1 starts up, the pressure of the hydrogen supplied to the regulator 14 must be increased from zero or near zero to a predetermined target pressure equal to or greater than the upper limit of the input pressure range.

[0035] On the other hand, the reaction rate, and consequently the hydrogen generation rate, when water is supplied to granular material H changes depending on the particle size of the granular material H. When the same amount of water is supplied to the same amount of granular material H, the reaction rate tends to decrease as the particle size of the granular material H increases, because the surface area per unit volume decreases. Furthermore, since the reaction duration increases as the reaction rate decreases, the reaction duration tends to increase as the particle size of the granular material H increases.

[0036] If, for example, water is supplied to the large-particle-size powder H at the start of operation of FC stack 1, the hydrogen generation rate will be slow, resulting in a problem where it takes time for the hydrogen pressure to rise to the target pressure. Consequently, this will cause a delay in the start of operation of the hydrogen power generation device 100 or FC stack 1.

[0037] Therefore, in this embodiment, the following control is performed to solve this problem. That is, as shown in Figure 2, when the detected pressure P detected by the pressure sensor 5 rises toward a predetermined target pressure Pt, the ECU 6 controls the water supply device 4 so that the hydrogen container 3 to which water is supplied is changed according to the difference ΔP between the detected pressure P and the target pressure Pt.

[0038] This will be explained using Figure 2. The horizontal axis represents time t. The "0, 1, 2, ..." on the horizontal axis represent the times or timings t0, t1, t2, ... when water is supplied into the hydrogen container 3. The vertical axis represents the hydrogen pressure, or detected pressure P, detected by the pressure sensor 5.

[0039] Pressure thresholds (first and second pressure thresholds) Ps1 and Ps2 lower than the target pressure Pt are predefined. Ps1 < Ps2 < Pt. The difference between the target pressure Pt and the pressure threshold Ps1 is ΔPs1, and the difference between the target pressure Pt and the pressure threshold Ps2 is ΔPs2. ΔPs1 > ΔPs2.

[0040] The ECU 6 controls the water supply device 4 so that the greater the difference ΔP between the detected pressure P and the target pressure Pt, the more water is supplied to the hydrogen container 3 containing the finer granular material H.

[0041] At the start of operation of the FC stack 1, the detected pressure P begins to rise from zero or a value near zero at the initial time t0.

[0042] At this time, the detected pressure P is lower than the pressure threshold Ps1, and the pressure difference ΔPs from the target pressure Pt is greater than ΔPs1, and is large.

[0043] Therefore, at time t0, the ECU 6 supplies water to the #1 hydrogen container 3 containing the finer granular material H. Specifically, the solenoid valve 10 corresponding to the #1 hydrogen container 3 is opened for a predetermined time.

[0044] Thereby, water is supplied to the finer granular material H. Since this granular material H has a large surface area per unit volume, the reaction rate and the hydrogen generation rate are high. Therefore, the detected pressure P rises relatively rapidly. Thereby, the time to reach the target pressure Pt can be shortened.

[0045] At the next time t1 as well, since the detected pressure P is lower than the pressure threshold Ps1, the ECU 6 supplies water to the #1 hydrogen container 3. Thereby, the rising speed of the detected pressure P is maintained high.

[0046] At the next time t2, the detected pressure P exceeds the pressure threshold Ps1 but is lower than the pressure threshold Ps2. And the pressure difference ΔPs from the target pressure Pt is smaller than ΔPs1 but larger than ΔPs2, and is medium.

[0047] Therefore, at time t2, the ECU6 changes the hydrogen container 3 to which water is supplied. Specifically, it changes from hydrogen container #1 3 containing fine-grained powder H to hydrogen container #2 3 containing medium-grained powder H. Then, it opens the solenoid valve 10 corresponding to hydrogen container #2 3 for a predetermined time.

[0048] This supplies water to the granular material H within the particle size range. Since this granular material H has an intermediate surface area per unit volume, its reaction rate and hydrogen generation rate are also intermediate. Therefore, the detected pressure P rises at a moderate rate, slightly slower than before. This allows the detected pressure P to rise more gradually toward the target pressure Pt than before, and suppresses overshoot of the detected pressure P.

[0049] At the next time t3, the detected pressure P is higher than the pressure threshold Ps1 and lower than the pressure threshold Ps2, so the ECU6 supplies water to hydrogen container #2 3. This maintains a moderate rate of increase in the detected pressure P.

[0050] At the next time point t4, the detected pressure P is lower than the target pressure Pt, but above the pressure threshold Ps2. The pressure difference ΔPs from the target pressure Pt is smaller than ΔPs2, and is therefore small.

[0051] Therefore, at time t4, the ECU6 changes the hydrogen container 3 to which water is supplied. Specifically, it changes from hydrogen container #2 3, which contains medium-sized granular material H, to one of hydrogen containers #3 to #6 3, which contain coarse-sized granular material H, for example, hydrogen container #3 3. Then, it opens the solenoid valve 10 corresponding to hydrogen container #3 3 for a predetermined time.

[0052] This allows water to be supplied to the coarse-grained powder material H. Because this powder material H has a small surface area per unit volume, the reaction rate and hydrogen generation rate are slow. Therefore, the detected pressure P rises more slowly than before. This allows the detected pressure P to be increased more gradually towards the target pressure Pt, and the detected pressure P can be stably maintained near the target pressure Pt.

[0053] Subsequently, until time t9, the detected pressure P remains lower than the target pressure Pt and above the pressure threshold Ps2. The pressure difference ΔPs between the detected pressure Pt and the target pressure is small. Therefore, the ECU 6 continuously supplies water to hydrogen container 3 #3. This maintains a slow rate of increase in the detected pressure P.

[0054] At the subsequent time t10, the detected pressure P has reached the target pressure Pt. Therefore, the pressure difference ΔPs with respect to the target pressure Pt is zero, but the ECU 6 continues to supply water to hydrogen container #3 3. In this way, if the detected pressure P is higher than the pressure threshold Ps2, water is continuously supplied to any of the hydrogen containers #3 to #6 3.

[0055] After this, if the hydrogen storage alloy in hydrogen container #3, which is currently being supplied with water, is completely reacted and hydrogen production ceases, the ECU 6 will switch the water supply container to another hydrogen container 3 from #3 to #6, for example, hydrogen container #4. This allows the same hydrogen production state to be maintained.

[0056] The fine-grained and medium-grained granular materials H are mainly used only when the FC stack 1 starts up, so their usage frequency is not very high. On the other hand, the coarse-grained granular materials H are used almost constantly after the FC stack 1 starts up, so their usage frequency is high. Therefore, in this embodiment, in accordance with these usage frequencies, the number of hydrogen containers 3 that contain fine-grained granular materials H and hydrogen containers 3 that contain medium-grained granular materials H are set to be less than the number of hydrogen containers 3 that contain coarse-grained granular materials H, with one of the former and four of the latter. This increases the number of hydrogen containers 3 that are used frequently, and reduces the frequency of hydrogen container 3 replacement.

[0057] Thus, the number of hydrogen containers 3 (#3~6) that contain large-grained powder H is greater than the number of hydrogen containers 3 (#1 or #2) that contain small-grained powder H.

[0058] After the operation of the FC stack 1 starts, even if the detected pressure P falls below the pressure thresholds Ps1 and Ps2 for some reason, the hydrogen container 3 that supplies water can be immediately changed. Then, water is supplied to the granular material H with a smaller particle size, the reaction rate is increased, and the detected pressure P can be quickly restored to a pressure higher than the pressure threshold Ps2. As a result, the detected pressure P can be stably maintained near the target pressure Pt.

[0059] Figure 3 is a flowchart showing the content of the control of this embodiment. The illustrated routine is repeatedly executed by the ECU 6 at a predetermined cycle or each water supply timing.

[0060] In step S101, the ECU 6 acquires the value of the detected pressure P.

[0061] In step S102, the ECU 6 compares the value of the detected pressure P with the pressure threshold Ps1.

[0062] When the value of the detected pressure P is less than or equal to the pressure threshold Ps1 (P ≤ Ps1), the ECU 6 proceeds to step S103, opens the solenoid valve 10 corresponding to the #1 hydrogen container 3 that contains the granular material H with a small particle size, and supplies water to the #1 hydrogen container 3.

[0063] On the other hand, in step S102, when the value of the detected pressure P is greater than the pressure threshold Ps1 (P > Ps1), the ECU 6 proceeds to step S104 and determines whether the value of the detected pressure P is between the pressure thresholds Ps1 and Ps2.

[0064] That is, when the value of the detected pressure P is greater than the pressure threshold Ps1 and less than or equal to the pressure threshold Ps2 (Ps1 < P ≤ Ps2), the ECU 6 proceeds to step S105, opens the solenoid valve 10 corresponding to the #2 hydrogen container 3 that contains the granular material H with a medium particle size, and supplies water to the #2 hydrogen container 3.

[0065] On the other hand, in step S104, if the value of the detected pressure P is greater than the pressure threshold Ps2 (P>Ps2), the ECU 6 proceeds to step S106 and opens the solenoid valve 10 corresponding to one of the #3 to 6 hydrogen containers 3 (for example, #3) containing the coarse-grained powder H, and supplies water to that hydrogen container 3.

[0066] As described above, according to this embodiment, when the detected pressure P rises toward the target pressure Pt, the hydrogen container 3 to which water is supplied is changed according to the difference ΔP between the detected pressure P and the target pressure Pt. As a result, when the difference ΔP is large, water can be supplied to the powder H with a relatively small particle size, and the detected pressure P can be rapidly raised to the target pressure Pt.

[0067] In particular, according to this embodiment, the larger the difference ΔP, the more water can be supplied to the finer particle size material H, which in turn allows the detected pressure P to be rapidly raised to the target pressure Pt.

[0068] Furthermore, when starting operation of the hydrogen power generation device 100 or FC stack 1, the pressure of the generated hydrogen can be quickly raised to the target pressure Pt, shortening the preparation time or start-up time of the hydrogen power generation device 100 or FC stack 1, and enabling rapid power generation to begin.

[0069] Although embodiments of this disclosure have been described in detail above, various other embodiments and modifications of this disclosure are conceivable.

[0070] For example, in the above embodiment, three stages of particle size H (small, medium, and large) were prepared, and water was supplied to them in order. However, the number of particle size stages may be fewer, such as two stages, or more, such as four or more stages.

[0071] In the above embodiment, a capacitor 16 was used as the energy storage device, but other energy storage devices, such as a battery, may also be used.

[0072] The hydrogen power generation device 100 can be used for any purpose. For example, the hydrogen power generation device 100 may be used for a vehicle. In this case, the electrical load 17 can be a vehicle drive motor, electric auxiliary equipment, etc.

[0073] The embodiments of this disclosure are not limited to those described above, but include any variations, applications, and equivalents encompassed within the spirit of this disclosure as defined by the claims. Therefore, this disclosure should not be constrained, but can be applied to any other art that falls within the scope of the spirit of this disclosure. [Explanation of Symbols]

[0074] 1 Fuel cell stack 2. Hydrogen generator 3. Hydrogen container 4 Water supply device 5. Pressure Sensor 6. Electronic control unit 10 Solenoid valve 100 Hydrogen power generation equipment H Powder

Claims

1. Multiple hydrogen containers, each containing powders and granules of different particle sizes made of hydrogen storage alloys, A water supply device configured to supply water individually to multiple hydrogen containers, A pressure sensor for detecting the pressure of hydrogen produced by the reaction of powder and water, A control unit configured to control the water supply device based on the detected pressure detected by the pressure sensor, Equipped with, The control unit controls the water supply device so that when the detected pressure rises toward a predetermined target pressure, the hydrogen container to which water is supplied is changed according to the difference between the detected pressure and the target pressure. A hydrogen generation device characterized by the following features.

2. The control unit controls the water supply device so that the greater the difference, the more water is supplied to the hydrogen container containing the finer particle size powder. The hydrogen generation apparatus according to claim 1.

3. The water supply device is provided for each hydrogen container and has a solenoid valve that controls the supply of water to the hydrogen container. The control unit changes the solenoid valve that is opened according to the difference between the detected pressure and the target pressure. The hydrogen generation apparatus according to claim 1.

4. The number of hydrogen containers that contain large-grained powders is greater than the number of hydrogen containers that contain small-grained powders. The hydrogen generation apparatus according to claim 1.

5. The hydrogen storage alloy is magnesium hydride. The hydrogen generation apparatus according to claim 1.

6. A hydrogen generator according to claim 1, A fuel cell stack that generates electricity using hydrogen produced by the hydrogen generation device, A hydrogen power generation device characterized by being equipped with the following features.

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