Flammable gas recovery device

Abstract

To provide a device of recovering flammable gas, that can prevent deterioration of a facility and is excellent in safety.SOLUTION: The device of recovering flammable gas comprises a recovery chamber recovering flammable gas generated from a source of flammable gas, a flammable gas channel for sending out flammable gas present in the recovery chamber, an inert gas channel for supplying the recovery chamber with inert gas, and pressure control means of controlling the pressure of inert gas being supplied to the recovery chamber. The pressure control means controls the pressure of the inert gas so as to keep the inner pressure of the recovery chamber positive relative to the atmospheric pressure.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a flammable gas recovery device.

Background Art

[0002] In recent years, from the viewpoints of environmental protection and energy conservation, attempts have been made to effectively utilize flammable gases such as hydrogen and methane gas generated in industrial activities as resources such as fuel. For example, attempts are known to recover and utilize hydrogen, which is a flammable gas generated from an electrode, during anodizing of aluminum (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The technique disclosed in Patent Document 1 has a recovery chamber (recovery device) for recovering hydrogen, which is a flammable gas, but there is a possibility that the inside of the recovery chamber may be at a negative pressure with respect to atmospheric pressure. For example, when the amount of hydrogen generated decreases and the flow rate of a blower that conveys hydrogen to the secondary side (downstream side from the generation source) is large with respect to the amount of hydrogen generated, or when the liquid level of the electrolytic solution drops due to the insertion and removal of the electrode, etc., the above cases apply. When the inside of the recovery chamber is at a negative pressure with respect to atmospheric pressure, there is a possibility that the electrolytic solution may flow into the secondary side of the recovery chamber. In this case, there is a risk that the equipment on the secondary side may deteriorate due to the electrolytic solution. Furthermore, when the recovery chamber is not sealed, air may flow into the inside of the recovery chamber, and there is also a possibility that a mixed gas of hydrogen and air may enter the combustion range.

[0005] The present disclosure has been made in view of the above, and an object thereof is to provide a flammable gas recovery device that can prevent deterioration of equipment and is excellent in safety. [Means for solving the problem]

[0006] This disclosure relates to a combustible gas recovery apparatus comprising: a recovery chamber for recovering combustible gas generated from a source of combustible gas; a combustible gas flow path for discharging the combustible gas from the recovery chamber; an inert gas flow path for supplying an inert gas to the recovery chamber; and a pressure adjusting means for adjusting the pressure of the inert gas supplied to the recovery chamber, wherein the pressure adjusting means adjusts the pressure of the inert gas so as to maintain a positive pressure relative to atmospheric pressure inside the recovery chamber. [Brief explanation of the drawing]

[0007] [Figure 1] This is a block diagram showing a combustible gas recovery device according to the first embodiment of the present disclosure. [Figure 2] This is a schematic diagram showing the configuration of the electrolytic cell and the combustible gas recovery device of the present disclosure. [Figure 3] This is a block diagram showing a combustible gas recovery device according to a second embodiment of the present disclosure. [Modes for carrying out the invention]

[0008] <Flammable Gas Recovery System> (First Embodiment) The hydrogen recovery device 1, as a combustible gas recovery device according to this embodiment, is a device that recovers hydrogen gas as a combustible gas generated from an electrolytic cell 2, which is a source of combustible gas. In this specification, "combustible gas" means not only the hydrogen gas exemplified above, but also all gases whose mixture with air has an explosive range (combustion range). Hereinafter, the combustible gas recovery device will be described as the hydrogen recovery device 1 that recovers hydrogen as a combustible gas. On the other hand, the combustible gas may be a combustible gas other than hydrogen.

[0009] [Hydrogen recovery device] As shown in Figure 1, the hydrogen recovery device 1 is a device for recovering hydrogen generated from the electrolytic cell 2, and includes a hydrogen recovery chamber 10 as a recovery chamber, combustible gas flow paths L21 and L22 for sending the hydrogen recovered in the hydrogen recovery chamber 10 toward the firing furnace 6 which is the destination for use, inert gas flow paths L11 and L12 for supplying inert gas to the hydrogen recovery chamber 10, and valves V1a and V1b as pressure regulating means. Since the cathode penetrates the inside of the hydrogen recovery chamber 10 and electrode terminals must be provided at both ends of the cathode, it is difficult to completely seal the area around the cathode at both ends of the hydrogen recovery chamber 10.

[0010] Figure 2 is a schematic cross-sectional view of the hydrogen recovery chamber 10 and the electrolytic cell 2, viewed from the short side. As shown in Figure 2, the hydrogen recovery chamber 10 is a box-shaped body positioned to cover the electrodes. Hydrogen generated by the anodizing treatment of aluminum material A immersed in electrolyte E flows into the hydrogen recovery chamber 10.

[0011] The hydrogen recovery chamber 10 may be equipped with an overpressure relief section to release overpressure inside the hydrogen recovery chamber. The overpressure relief section has the function of releasing overpressure to the outside of the hydrogen recovery chamber 10 when overpressure exceeding a preset allowable pressure occurs inside the hydrogen recovery chamber. The allowable pressure can be set to, for example, approximately 130 [kPa]. For example, if hydrogen were to burn inside the hydrogen recovery chamber 10, the gas inside the hydrogen recovery chamber would rapidly expand, causing the overpressure. The overpressure relief section can minimize the damage that would occur if the overpressure occurred. The specific configuration of the overpressure relief section is not particularly limited, but for example, a part of the wall surface of the hydrogen recovery chamber 10 can be configured as a weaker area with lower strength than other parts. An overpressure relief section can be provided for each section of the hydrogen recovery chamber 10 partitioned by the flame propagation prevention plate described below.

[0012] The hydrogen recovery chamber 10 may be equipped with flame propagation prevention plates that divide the inside of the hydrogen recovery chamber 10 into multiple spaces. The flame propagation prevention plates have the function of suppressing flame propagation. The flame propagation prevention plates may have one or more holes or flow paths through which gas can flow. This makes it possible to have only one connection point between the hydrogen recovery chamber 10 and the flammable gas flow path L21, and the inert gas flow paths L11 and L12. The above connection points may be provided for each section of the hydrogen recovery chamber 10 that is partitioned by the flame propagation prevention plates.

[0013] Inert gas channels L11 and L12 are connected to the hydrogen recovery chamber 10 for supplying inert gas. Inert gas channel L11 is a channel that supplies inert gas to the hydrogen recovery chamber 10 in order to maintain a positive pressure relative to atmospheric pressure when the electrolytic cell 2 is in use. Inert gas channel L12 is a channel that supplies inert gas to the hydrogen recovery chamber 10 before use of the electrolytic cell 2 in order to replace any remaining air inside the hydrogen recovery chamber 10 with inert gas. In this specification, inert gas means a gas that is chemically stable and significantly less reactive than oxygen. Specific examples of inert gases include nitrogen, carbon dioxide, helium, neon, argon, krypton, and xenon. In this embodiment, nitrogen is used as the inert gas. An inert gas source 3 is connected to the upstream side of the inert gas channels L11 and L12. The inert gas source may be a gas cylinder, or nitrogen may be separated from the air and used. When using a gas cylinder, it is preferable to install the pressure reducing valve V1a and the pressure equalizing valve V1b in the flow path separately from the pressure valve installed in the gas cylinder.

[0014] The inert gas flow path L11 is provided with a pressure reducing valve V1a and a pressure equalizing valve V1b as pressure regulating means. In this embodiment, the pressure reducing valve V1a is located upstream of the pressure equalizing valve V1b, and V1b is located downstream of the pressure reducing valve V1a. The pressure reducing valve V1a and the pressure equalizing valve V1b adjust the pressure of the nitrogen supplied to the hydrogen recovery chamber 10 through the inert gas flow path L11 so that the pressure inside the hydrogen recovery chamber 10 is maintained at a positive pressure relative to atmospheric pressure. By maintaining the pressure inside the hydrogen recovery chamber 10 at a positive pressure relative to atmospheric pressure using the above pressure regulating means, it is possible to prevent the electrolyte E stored in the electrolytic cell 2 from flowing into the flammable gas flow path L21, and to prevent air from flowing into the hydrogen recovery chamber 10 from the outside and causing a mixture of hydrogen and air to enter the combustion range. Therefore, the hydrogen recovery device 1 can be made to prevent equipment deterioration and to be highly safe.

[0015] The pressure reducing valve V1a is a valve that reduces the pressure of nitrogen supplied from the inert gas source 3 to a predetermined pressure (for example, about 10 kPa) that is permissible as the primary pressure of the pressure equalizing valve V1b located downstream. The pressure equalizing valve V1b is a valve that maintains the secondary pressure at a predetermined pressure above atmospheric pressure. The pressure reducing valve V1a and the pressure equalizing valve V1b are not particularly limited, and known pressure reducing valves and pressure equalizing valves can be used. The configuration of the pressure adjustment means is not limited to the above, and for example, a pressure reducing valve may be used instead of the pressure equalizing valve V1b.

[0016] An openable / closable valve V12 is provided in the inert gas flow path L12. The upstream sides of the inert gas flow paths L11 and L12 are connected to the inert gas flow path L1. An openable / closable valve V1 is provided in the inert gas flow path L1. The upstream side of the inert gas flow path L1 is connected to the inert gas source 3. The configuration of the inert gas flow paths L11 and L12 is not limited to the above, and they may be individually connected to different inert gas sources.

[0017] The hydrogen recovered in the hydrogen recovery chamber 10 is sent to the firing furnace 6, where the hydrogen will be used, through the combustible gas flow paths L21 and L22. As shown in Figure 1, the combustible gas flow path L21 is a flow path connecting the hydrogen recovery chamber 10 and the scrubbing tower 4. The scrubbing tower 4 is a device that removes mist and other particles scattered when gas bubbles generated in the electrolyte burst at the liquid surface through a scrubbing process. The configuration of the scrubbing tower 4 can be a known scrubbing tower configuration. A combustible gas flow path L22 is provided downstream of the scrubbing tower 4. A pump device 5 is provided in the combustible gas flow path L22. The hydrogen flowing into the hydrogen recovery chamber 10 is drawn in through the combustible gas flow paths L21 and L22 by the flow rate of the pump device 5. At this time, it is difficult to make the suction force of the pump device 5 perfectly follow the amount of hydrogen generated and flowing into the hydrogen recovery chamber 10. The above-mentioned pressure adjustment means is used to prevent the hydrogen recovery chamber 10 from becoming negative pressure relative to atmospheric pressure when the suction force of the pump device 5 is greater than the amount of hydrogen generated.

[0018] To confirm whether oxygen is mixed into the gas recovered through the flammable gas flow path L22, an oxygen concentration meter (〇) may be connected to the secondary side of the pump device 5.

[0019] The firing furnace 6 hardens the electrodeposited coating formed on the surface of the aluminum material A after anodizing by applying electrodeposition coating. It is preferable to use hydrogen recovered by the hydrogen recovery device 1 in the firing furnace 6 because it allows for effective utilization of hydrogen generated within a single aluminum processing facility. On the other hand, the firing furnace 6 is not limited to the firing furnace 6 as an example of where the hydrogen recovered by the hydrogen recovery device 1 can be used, such as in furnaces that use fuel in surrounding equipment or in fuel cells. For example, the downstream side of the combustible gas flow path L22 may be connected to a tank for storing hydrogen, and the hydrogen stored in the tank may be used for various purposes.

[0020] [Electrolytic cell] The electrolytic cell 2 as a source of combustible gas is, for example, an electrolytic cell used for an anodic oxidation treatment that targets a metal material such as an aluminum material. Hereinafter, a source that generates hydrogen as a combustible gas will be described using the electrolytic cell 2 used for the above anodic oxidation treatment. On the other hand, the source of combustible gas is not limited to the above electrolytic cell 2, and it may be a methane fermentation tank or the like that generates a combustible gas other than hydrogen, such as methane gas. As a source that generates hydrogen as a combustible gas, in addition to the above electrolytic cell, for example, an etching tank that etches the surface of the object to be treated to generate hydrogen may be used.

[0021] As shown in FIG. 2, the electrolytic cell 2 is a tank in which an electrolytic solution E is stored, and has one or more cathodes 21 and an anode. The aluminum material A, which is the object to be treated and serves as the anode, and the cathode 21 that serves as the counter electrode are immersed in the electrolytic solution E stored in the electrolytic cell 2. In this state, by applying an electric current, an anodic oxide film (an alumite film) is formed on the surface of the aluminum material A, and hydrogen is generated from the cathode 21. As the electrolytic solution E, for example, an aqueous solution containing sulfuric acid is provided. The upper part of the electrolytic cell 2 is open, and a hydrogen recovery chamber 10 is arranged to cover the cathode 21 and be immersed in the electrolytic solution. The hydrogen generated by the anodic oxidation treatment flows into the hydrogen recovery chamber 10.

[0022] The cathode 21 is preferably an electrode made of aluminum or platinum, but is not limited thereto. In the present embodiment, as shown in FIG. 2, the plurality of cathodes 21 are arranged in a row (in this embodiment, four rows) with the aluminum material A, which is the object to be treated, sandwiched therebetween, and are immersed in the electrolytic solution E stored in the electrolytic cell 2. The total number of cathodes 21 and the number per row are not particularly limited. The cathode 21 is held in the electrolytic cell 2 by a cathode angle tube 21a. The cathode angle tube 21a is a member having a square tube shape made of a conductive material and is a current conduction path from a power source (not shown) to the plurality of cathodes 21.

[0023] As shown in Figure 2, the liquid level of the electrolyte E stored in the electrolytic cell 2 fluctuates up and down due to the immersion and removal of the aluminum material A from the electrolyte E. This may cause changes in the pressure inside the hydrogen recovery chamber 10. As shown in Figure 1, in the electrolytic cell 2, a terminal portion 21b is provided at the end of the cathode tube 21a. Conductor wires for power supply are connected to the terminal portion 21b. Therefore, it is difficult to completely seal the hydrogen recovery chamber 10, and if the pressure inside the hydrogen recovery chamber 10 becomes negative relative to atmospheric pressure, air may flow in from the outside. To prevent the above situation, the pressure adjustment means is used.

[0024] (Second Embodiment) The configuration of the hydrogen recovery device 1a according to the second embodiment will be described below with reference to Figure 3. Components similar to those in the first embodiment may be denoted by the same reference numerals and their description may be omitted.

[0025] The hydrogen recovery device 1a includes a pressure control valve V1c as a pressure adjustment means, a pressure sensor S, and a control unit 7. The pressure control valve V1c is a valve provided in the inert gas flow path L11, and the pressure sensor S is a sensor device capable of measuring the pressure inside the hydrogen recovery chamber 10. The control unit 7 is communicated with the pressure control valve V1c and the pressure sensor S. For example, if the pressure inside the hydrogen recovery chamber 10 measured by the pressure sensor S falls below a predetermined threshold above atmospheric pressure, the control unit 7 controls the pressure control valve V1c to increase the pressure of nitrogen supplied from the inert gas source 3. This makes it possible to maintain the pressure inside the hydrogen recovery chamber 10 at a positive pressure relative to atmospheric pressure. Similar to the first embodiment, a pressure reducing valve V1a may be provided upstream of the pressure control valve V1c. As the pressure control valve V1c, for example, a control valve that is operated by a drive source and has adjustable flow rate can be used.

[0026] The hydrogen recovery apparatus as a combustible gas recovery apparatus according to each embodiment of this disclosure has been described above. However, this disclosure is not limited to the above embodiments and can be modified as appropriate. [Explanation of Symbols]

[0027] 1, 1a Hydrogen recovery device (combustible gas recovery device), 10 Hydrogen recovery chamber (recovery chamber), 2 Electrolytic cell (source of combustible gas), L11 Inert gas flow path, L21, L22 Combustible gas flow path, V1a Pressure reducing valve (pressure regulating means), V1b Pressure equalizing valve (pressure regulating means), V1c Pressure control valve (pressure regulating means), S Pressure sensor (pressure regulating means)

Claims

1. A recovery chamber for recovering flammable gases generated from a source of flammable gases, A combustible gas flow path for discharging combustible gas from the recovery chamber, An inert gas channel for supplying inert gas to the recovery chamber, It includes a pressure adjustment means for adjusting the pressure of the inert gas supplied to the recovery chamber, The aforementioned flammable gas is generated from the liquid, The source of the aforementioned flammable gas is an electrolytic cell used in anodizing treatment. The recovery chamber is arranged such that a portion of it is immersed in the liquid. The aforementioned recovery chamber is not sealed, The pressure adjustment means adjusts the pressure of the inert gas so as to maintain a positive pressure relative to atmospheric pressure inside the recovery chamber of the flammable gas recovery device.

2. The combustible gas recovery apparatus according to claim 1, wherein the combustible gas is hydrogen.

3. The flammable gas recovery apparatus according to claim 1 or 2, wherein the pressure adjustment means comprises a pressure reducing valve provided in the inert gas flow path and either a pressure reducing valve or a pressure equalizing valve provided downstream of the pressure reducing valve.

4. The flammable gas recovery apparatus according to any one of claims 1 to 3, wherein the pressure adjustment means comprises a pressure control valve provided in the inert gas flow path and a pressure sensor capable of measuring the pressure in the recovery chamber.

5. The combustible gas recovery apparatus according to any one of claims 1 to 4, wherein the recovery chamber is provided with an overpressure relief section for releasing the overpressure inside the recovery chamber.

6. The combustible gas recovery apparatus according to any one of claims 1 to 5, wherein the recovery chamber is equipped with a flame propagation prevention plate that prevents the propagation of flames by dividing the recovery chamber into multiple spaces.

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