Hydrogen production facilities

Abstract

This utility model relates to a hydrogen production apparatus, the problem of which is that the labor, costs, and equipment required for the decomposition and recycling of used nickel-metal hydride batteries that are deemed unusable are expected to increase in the future. The hydrogen production apparatus includes: a nickel-metal hydride battery whose full-charge capacity has decreased to below a predetermined value; a battery casing for housing the nickel-metal hydride battery; a water supply unit for supplying water to the battery casing; a power supply unit for supplying power to the electrodes of the nickel-metal hydride battery; and a gas discharge unit for discharging the gas generated inside the battery casing through water electrolysis to the outside of the battery casing.

Description

Technical Field

[0001] The technology disclosed in this specification relates to hydrogen production equipment. Background Technology

[0002] Patent Document 1 discloses a method for reusing a secondary battery containing a nickel-based compound as the positive electrode active material. Nickel-metal hydride batteries deteriorate due to the formation of Ni₂O₃H in the positive electrode, resulting in a decrease in full-charge capacity. Based on the aforementioned reuse method, the amount of Ni₂O₃H formed in the positive electrode of the secondary battery is estimated, and a comparison between the estimated amount and a reference amount determines whether the secondary battery should be reused for high-capacity applications, high-input-output applications, or is unreusable.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2019-46644

[0004] Used nickel-metal hydride (NiMH) batteries deemed unusable are typically dismantled and recycled on a per-resource basis. The number of used NiMH batteries is expected to increase in the future. Therefore, the increasing labor, costs, and equipment required for dismantling and recycling used NiMH batteries has become a challenge. Utility Model Content

[0005] This specification discloses a hydrogen production apparatus. The hydrogen production apparatus includes: a nickel-metal hydride battery whose full-charge capacity is reduced to below a predetermined value; a battery casing for housing the nickel-metal hydride battery; a water supply unit for supplying water into the battery casing; a power supply unit for supplying power to the electrodes of the nickel-metal hydride battery; and a gas discharge unit for discharging gas generated within the battery casing through water electrolysis to the outside of the battery casing.

[0006] According to the above structure, water and electricity are supplied through the water supply unit and the power supply unit, respectively, causing a water electrolysis reaction within the battery casing to produce a mixture of hydrogen and oxygen. This mixture is then discharged as a gas from the battery casing through the gas exhaust unit, resulting in hydrogen. At this time, the active material of the nickel-metal hydride battery functions as a catalyst for water electrolysis. In other words, by assembling nickel-metal hydride batteries whose full-charge capacity has decreased below a specified value—that is, nickel-metal hydride batteries that have been used and deteriorated—into a hydrogen production device, the options for reusing nickel-metal hydride batteries can be increased. Attached Figure Description

[0007] Figure 1 It is a partial cross-sectional view that simply represents the structure of a hydrogen production device.

[0008] Figure 2 This is a diagram that more simply shows the internal structure of the battery casing.

[0009] Figure 3 It is a simplified diagram representing two adjacent storage rooms and the structures associated with these storage rooms.

[0010] Figure 4 This is a flowchart representing the water surface position control process. Detailed Implementation

[0011] This embodiment will be described with reference to the accompanying drawings. The drawings are merely illustrative, and this embodiment is not limited to the content shown. Furthermore, since the drawings are illustrative, some parts have been omitted.

[0012] Figure 1 The structure of the hydrogen production apparatus 10 in this embodiment is simply shown in a partial cross-sectional view. The hydrogen production apparatus 10 generally includes a battery housing 20 and a power supply unit 30. Figure 2 The internal structure of the battery casing 20 is shown simplified from a top viewpoint. A nickel-metal hydride battery 11 is housed within the battery casing 20. Typically, a nickel-metal hydride battery is a secondary battery that uses nickel oxide as the positive electrode active material, a hydrogen storage alloy as the negative electrode active material, and an alkaline electrolyte.

[0013] Nickel-metal hydride battery 11 is a nickel-metal hydride battery whose full-charge capacity has decreased to below a predetermined value. That is, nickel-metal hydride battery 11 is in a state where its current full-charge capacity has deteriorated to below a predetermined percentage of its initial full-charge capacity. Nickel-metal hydride battery 11 is equivalent to a used nickel-metal hydride battery. Nickel-metal hydride battery 11 is, for example, a nickel-metal hydride battery that has been determined to be unusable as described in Patent Document 1, or a nickel-metal hydride battery that has deteriorated as described above, even if it has not been determined to be unusable.

[0014] The battery casing 20 has at least one storage compartment 21. According to... Figure 1 and Figure 2 The battery casing 20 is divided into multiple (e.g., six) storage compartments 21, each of which houses a nickel-metal hydride battery 11. A single nickel-metal hydride battery 11 is also referred to as a single cell. The electrodes of the nickel-metal hydride batteries 11 housed in each storage compartment 21 are connected in series. Furthermore, a power supply unit 30 is connected to the positive electrode 12 of one end of the series-connected nickel-metal hydride battery 11 and the negative electrode 13 of the other end of the series-connected nickel-metal hydride batteries 11. Power is supplied to the electrodes of the nickel-metal hydride batteries 11 through the power supply unit 30. That is, a voltage is applied to the series-connected nickel-metal hydride batteries 11 through the power supply unit 30.

[0015] Each combination of the storage chamber 21 and the nickel-metal hydride battery 11 can be understood as having the same structure. Therefore, the following description will use them to represent a storage chamber 21 and a nickel-metal hydride battery 11 housed within it. The storage chamber 21 is generally box-shaped and forms a closed space inside, except for the multiple tubes 40 and 50 formed on the upper wall.

[0016] A water supply pipe 40 penetrates the upper wall of the storage chamber 21. Similarly, a gas exhaust pipe 50 penetrates the upper wall of the storage chamber 21. The storage chamber 21 has one or more water supply pipes 40 and one or more gas exhaust pipes 50. The water supply pipe 40 constitutes at least a portion of a "water supply section" that supplies water from outside the battery casing 20 to inside the battery casing 20. Therefore, the nickel-metal hydride battery 11 is immersed in water inside the storage chamber 21. The gas exhaust pipe 50 constitutes at least a portion of a "gas exhaust section" that discharges the gas generated inside the battery casing 20 through water electrolysis to the outside of the battery casing 20. The holes formed in the upper wall of the storage chamber 21 to allow the water supply pipe 40 and the gas exhaust pipe 50 to pass through are sealed with adhesives, sealant, or the like to prevent water and gas leakage.

[0017] The battery receives water from the water supply pipe 40 and electricity from the power supply unit 30. Within the receiving chamber 21, an electric current flows through the water, causing water electrolysis and producing a gas, a mixture of hydrogen and oxygen. Inside the receiving chamber 21, the active material of the nickel-metal hydride battery 11 acts as a catalyst for water electrolysis, thereby promoting the reaction. The gas produced in the receiving chamber 21 is discharged to the outside of the battery casing 20 through the gas discharge pipe 50. Hydrogen is obtained by separating the gas discharged from the gas discharge pipe 50 into hydrogen and oxygen.

[0018] Figure 3 Two adjacent storage chambers 21 and the structures associated with these storage chambers 21 are simply shown. For convenience, these storage chambers 21 are sometimes referred to as storage chambers 21a and 21b for distinction. Water 80 supplied from separately provided water supply pipes 40 is stored in storage chambers 21a and 21b. In storage chamber 21, the lower ends 40a of the water supply pipes 40 and 50a of the gas exhaust pipes 50 are located below the water surface 81 and are immersed in the water 80. A resistance meter 70 is connected to the water supply pipes 40 and 50 of the gas exhaust pipes 50 in storage chamber 21a via wiring W. In this case, the water supply pipes 40 and 50 are formed of conductive components. The resistance meter 70 is capable of measuring the resistance value between the water supply pipes 40 and 50 (hereinafter referred to as the inter-pipe resistance value). The resistance meter 70 is connected to a control unit 60. The control unit 60 has a processor and a memory, and is capable of executing control according to a program stored in the memory. The control unit 60 can also perform control over the power supply unit 30.

[0019] according to Figure 3The end of the gas discharge pipe 50 outside the receiving chamber 21a is connected to a gas separator 90 capable of performing the aforementioned gas separation process. The method employed by the gas separator 90 for gas separation processing includes known methods and is not particularly limited. The gas separator 90 is only required to be a structure capable of separating hydrogen from the gas and delivering the separated hydrogen to a designated storage target. The control unit 60, the resistance meter 70, and the gas separator 90 can also be understood as part of the hydrogen production apparatus 10. The gas separator 90 can also be understood as part of the gas discharge unit.

[0020] Although not shown in the diagram, the resistance measuring device 70 can measure the resistance value between each pair of water supply pipes 40 and gas exhaust pipes 50 in each of the multiple storage chambers 21. Alternatively, the resistance measuring device 70 can be provided for each pair of water supply pipes 40 and gas exhaust pipes 50 in each of the multiple storage chambers 21. In addition, although not shown in the diagram, each gas exhaust pipe 50 in each of the multiple storage chambers 21 is connected to the gas separator 90.

[0021] Figure 4 The flowchart illustrates the water level position control process performed by the control unit 60 on a specific storage chamber 21 (e.g., storage chamber 21a). The control unit 60 can perform this water level position control process independently and in parallel on each storage chamber 21. The control unit 60 begins the water level position control process when a predetermined amount of water required for water decomposition is supplied to each storage chamber 21 from each water supply pipe 40, and the power supply unit 30 begins supplying power to the battery casing 20, thus initiating water electrolysis in each storage chamber 21. Although not shown in the flowchart, the control unit 60 can terminate the water level position control process at any time.

[0022] In step S100, the control unit 60 causes the resistance measuring device 70 to measure the inter-tube resistance value, obtaining the measured inter-tube resistance value. In step S110, the control unit 60 compares the inter-tube resistance value obtained in step S100 with a predetermined threshold. Inside the receiving chamber 21, as the water electrolysis reaction proceeds, the water level 81 decreases. To ensure a continuous and stable hydrogen production from the water electrolysis reaction, it is necessary to control the water level 81 within an appropriate range inside the receiving chamber 21.

[0023] like Figure 3As shown in the storage chamber 21a, when the water surface 81 is high and a larger portion of the water supply pipe 40 and gas exhaust pipe 50 are immersed in the water 80, the inter-pipe resistance value decreases. On the other hand, as shown in the storage chamber 21b, when the water surface 81 is low and a smaller portion of the water supply pipe 40 and gas exhaust pipe 50 are immersed in the water 80, the inter-pipe resistance value increases. Therefore, when the inter-pipe resistance value is below the threshold, the control unit 60 determines that the water surface 81 is at a sufficiently high position and proceeds from "Yes" in step S110 to step S120. On the other hand, when the inter-pipe resistance value is above the threshold, it determines that the water surface 81 is below ideal and proceeds from "No" in step S110 to step S130.

[0024] In step S120, the control unit 60 stops the water supply to the receiving chamber 21 via the water supply pipe 40. For example, if a valve (not shown) is provided on the water supply pipe 40, the control unit 60 can start or stop the water supply to the receiving chamber 21 via the water supply pipe 40 by driving the valve to open or close. The valve and the control unit 60 can also be understood as part of the water supply unit. The control unit 60 proceeds to step S100 after step S120. Furthermore, if the determination in step S110 is "yes," and the water supply to the receiving chamber 21 via the water supply pipe 40 has already stopped, the status quo is maintained, and therefore the control unit 60 skips step S120 and proceeds to step S100.

[0025] On the other hand, in step S130, the control unit 60 begins supplying water to the receiving chamber 21 via the water supply pipe 40. The control unit 60 proceeds to step S100 after step S130. If the determination in step S110 is "no," and if the water supply to the receiving chamber 21 via the water supply pipe 40 is already ongoing, then the status quo can be maintained; therefore, the control unit 60 skips step S130 and proceeds to step S100. Based on this water level position control processing, the control unit 60 can maintain the position of the water level 81 within an appropriate range for each receiving chamber 21.

[0026] In addition, according to Figure 3At a predetermined position above the lower end 50a within the range of the gas discharge pipe 50 in the receiving chamber 21, a side hole 51 is formed on the side of the gas discharge pipe 50, penetrating this side. Gas generated within the receiving chamber 21 flows into the gas discharge pipe 50 through the side hole 51 and is discharged out of the receiving chamber 21 through the gas discharge pipe 50. Therefore, it can be said that it is appropriate for the water surface 81 to be located in a position range that is higher than the lower ends 40a and 50a and lower than the side hole 51. Therefore, in step S110, a preset threshold can also be used so that when the position of the water surface 81 is lower than a predetermined height position, it can be determined as "no", and when the position of the water surface 81 is above the predetermined height position, it can be determined as "yes". The predetermined height position is a position that is higher than the lower ends 40a and 50a and lower than the side hole 51.

[0027] Thus, according to this embodiment, the hydrogen production apparatus 10 includes: a nickel-metal hydride battery 11 whose full-charge capacity is reduced to below a predetermined value; a battery casing 20 for housing the nickel-metal hydride battery 11; a water supply unit for supplying water into the battery casing 20; a power supply unit 30 for supplying power to the electrodes of the nickel-metal hydride battery 11; and a gas discharge unit for discharging the gas generated inside the battery casing 20 through water electrolysis to the outside of the battery casing 20. In other words, by assembling the deteriorated nickel-metal hydride battery 11 into the battery casing 20 of the hydrogen production apparatus 10, the options for reusing the nickel-metal hydride battery 11 can be increased. Therefore, the increase in labor, cost, equipment, etc., required for the decomposition and recycling of the nickel-metal hydride battery 11 can be suppressed.

[0028] The unit used to detect the position of the water surface 81 in the storage chamber 21 is not limited to the resistance measuring device 70 that measures the resistance value between pipes. For example, it can be a water level sensor installed in the storage chamber 21, or a weight sensor that measures the amount of water in the storage chamber 21.

[0029] The above details specific examples of the technology disclosed in this specification, but these are merely illustrative and do not limit the technical solutions. The technology described in the technical solutions includes various modifications and alterations to the specific examples illustrated above. Furthermore, the technical elements described in this specification or drawings exert their technical usefulness individually or in various combinations, and are not limited to the combinations described in the technical solutions at the time of application. Additionally, the technology illustrated in this specification or drawings simultaneously achieves multiple objectives, and achieving one of these objectives is itself technically useful.

[0030] Explanation of reference numerals in the attached figures:

[0031] 10… Hydrogen production apparatus; 11… Nickel-metal hydride battery; 12… Positive electrode; 13… Negative electrode; 20… Battery casing; 21… Storage chamber; 30… Power supply unit; 40… Water supply pipe; 50… Gas exhaust pipe; 51… Side hole; 60… Control unit; 70… Resistance measuring device; 80… Water; 81… Water surface; 90… Gas separator.

Claims

1. A hydrogen manufacturing apparatus, wherein, have: Nickel-metal hydride batteries, whose full-charge capacity is reduced to below the specified value; Battery casing for housing the nickel-metal hydride battery; The water supply unit supplies water into the battery casing; The power supply unit supplies power to the electrodes of the nickel-metal hydride battery; as well as The gas discharge section discharges the gas generated inside the battery casing through water electrolysis to the outside of the battery casing.

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