Water electrolysis system

Abstract

This technology enables the miniaturization of water electrolysis systems. [Solution] The water electrolysis system is a water electrolysis stack that generates hydrogen and oxygen by electrolysis of water, and comprises a water electrolysis stack having an oxygen outlet for discharging a discharge fluid which is a fluid containing water and the generated oxygen, a gas-liquid separator, an oxygen channel connecting the oxygen outlet and the gas-liquid separator, and a simple separation unit provided in the oxygen channel for separating liquid from the discharge fluid passing through it.

Description

Technical Field

[0001] The present disclosure relates to a water electrolysis system.

Background Art

[0002] A water electrolysis system including a water electrolysis stack is known. The water electrolysis device described in Patent Document 1 includes a gas-liquid separator that performs gas-liquid separation of a fluid containing oxygen and water discharged from the water electrolysis stack.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the pipe connecting the water electrolysis stack and the gas-liquid separator, there is a possibility that the mixed-phase flow of water and oxygen flowing in the pipe becomes unstable. When the mixed-phase flow becomes unstable, vibrations, noise are generated, and the efficiency of gas-liquid separation by the gas-liquid separator decreases. In order to stabilize the mixed-phase flow, it is necessary to increase the inner diameter of the pipe. Therefore, it has been difficult to miniaturize the water electrolysis system.

Means for Solving the Problems

[0005] The present disclosure has been made to solve the above problems and can be realized in the following forms.

[0006] A water electrolysis system is provided according to an embodiment of the present disclosure. This water electrolysis system is a water electrolysis stack that generates hydrogen and oxygen by electrolysis of water, and comprises a water electrolysis stack having an oxygen outlet for discharging a discharge fluid which is a fluid containing water and the generated oxygen; a gas-liquid separator; an oxygen flow path connecting the oxygen outlet and the gas-liquid separator; and a simple separation unit provided in the oxygen flow path for separating liquid from the discharge fluid passing through it. In this type of water electrolysis system, for example, a simple separation unit such as a baffle plate or cyclone separator is provided on the oxygen flow path, which promotes the separation of the fluid into gas and liquid before the gas-liquid separator. As a result, the gas-liquid separator can be made smaller, and thus the water electrolysis system can be made smaller.

[0007] Furthermore, this disclosure can be implemented in various forms, for example, in the form of this water electrolysis device. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram illustrating a water electrolysis system. [Modes for carrying out the invention]

[0009] A. First Embodiment: Figure 1 is an explanatory diagram of a water electrolysis system 100 in one embodiment of the present disclosure. The water electrolysis system 100 produces hydrogen and oxygen by electrolysis of water. The water electrolysis system 100 comprises a water electrolysis stack 10, a gas-liquid separator 20, an oxygen flow path 30, a simple separation unit 40, and a control valve 50.

[0010] The water electrolysis stack 10 performs water electrolysis by receiving water and electricity. The water electrolysis stack 10 is composed of multiple water electrolysis cells stacked on top of each other. Each water electrolysis cell comprises an electrolyte membrane, a hydrogen electrode, and an oxygen electrode. The electrolyte membrane is made of a polymer material having ion exchange groups. The electrolyte membrane is located between the hydrogen electrode and the oxygen electrode. The hydrogen electrode catalyzes the reaction that produces hydrogen from protons and electrons. The oxygen electrode catalyzes the reaction that produces oxygen, protons, and electrons from water. Known catalysts are used for the hydrogen electrode and the oxygen electrode. The catalyst for the oxygen electrode is preferably an oxide. For example, the catalyst for the hydrogen electrode is platinum, and for example, the catalyst for the oxygen electrode is iridium oxide.

[0011] The water electrolysis stack 10 has an oxygen outlet 11 for discharging a discharge fluid, which is a fluid containing water and the generated oxygen. The discharge fluid discharged from the oxygen outlet 11 of the water electrolysis stack 10 flows through the oxygen flow path 30 and then through the simple separation unit 40, the control valve 50, and the gas-liquid separator 20 in that order.

[0012] The gas-liquid separator 20 contains the discharged fluid from the oxygen outlet 11 and separates the discharged fluid into gas and water. In this embodiment, the gas-liquid separator 20 supplies the water separated from the discharged fluid to the water electrolysis stack 10 via the water channel 21. The water channel 21 connects the gas-liquid separator 20 to the channel that supplies water to the water electrolysis stack 10. The gas-liquid separator 20 also discharges the gas separated from the discharged fluid to the outside of the water electrolysis system 100 via a channel different from the water channel 21.

[0013] The oxygen channel 30 is a channel that connects the water electrolysis stack 10 and the gas-liquid separator 20. In this embodiment, the oxygen channel 30 has a first oxygen channel 30a through which gas separated from the discharge fluid by the simplified separation unit 40 (described later) flows, and a second oxygen channel 30b through which liquid separated from the discharge fluid by the simplified separation unit 40 flows. The first oxygen channel 30a and the second oxygen channel 30b are channels that connect the simplified separation unit 40 and the gas-liquid separator 20, respectively. The first oxygen channel 30a is connected to the upper part of the gas-liquid separator 20, more specifically to the part of the gas-liquid separator 20 where gas accumulates. The second oxygen channel 30b is connected to the lower part of the gas-liquid separator 20, more specifically to the part of the gas-liquid separator 20 where liquid accumulates.

[0014] The simplified separation unit 40 is provided in the oxygen flow path 30 and is a component that separates liquid from the discharge fluid passing through it. In this embodiment, the simplified separation unit 40 is a cyclone separator.

[0015] The control valve 50 is a valve provided in the second oxygen flow path 30b. The control valve 50 is a valve that adjusts the flow rate of the liquid separated from the discharge fluid by the simple separation unit 40, which flows into the gas-liquid separator 20.

[0016] As described above, the water electrolysis system 100 of this embodiment has a simplified separation unit 40 on the oxygen flow path 30, which promotes the separation of the fluid into gas and liquid before the gas-liquid separator 20. Therefore, the gas-liquid separator 20 can be miniaturized, and thus the water electrolysis system 100 can be miniaturized.

[0017] Furthermore, the oxygen channel 30 has a first oxygen channel 30a and a second oxygen channel 30b. The first oxygen channel 30a carries gas separated from the discharge fluid by the simple separation unit 40, and the second oxygen channel 30b carries liquid separated from the discharge fluid by the simple separation unit 40. Therefore, the inner diameters of the pipes for the first oxygen channel 30a and the second oxygen channel 30b can be smaller than the inner diameter of the pipe through which the discharge fluid, which is a multiphase flow of gas and liquid, flows. As a result, the water electrolysis system 100 can be miniaturized.

[0018] Further, the flow rate of the liquid separated from the discharged fluid by the simple separation unit 40 and flowing into the gas-liquid separator 20 can be adjusted by the control valve 50. Since the gas-liquid separator 20 can be miniaturized, the water electrolysis system 100 can be miniaturized.

[0019] B. Other Embodiments: (B1) In the above-described embodiment, the oxygen flow path 30 has a first oxygen flow path 30a and a second oxygen flow path 30b. However, the oxygen flow path 30 is not limited to this, and may not have the first oxygen flow path 30a and the second oxygen flow path 30b. That is, the flow path connecting the simple separation unit 40 and the gas-liquid separator 20 may be one.

[0020] (B2) In the above-described embodiment, the first oxygen flow path 30a connects the simple separation unit 40 and the gas-liquid separator 20. However, the first oxygen flow path 30a is not limited to this, and may not be connected to the gas-liquid separator 20. The first oxygen flow path 30a may be, for example, a flow path that discharges the gas separated from the discharged fluid by the simple separation unit 40 to the outside of the water electrolysis system 100.

[0021] (B3) In the above-described embodiment, in the above-described embodiment, the simple separation unit 40 is a cyclone separator. However, the simple separation unit 40 is not limited to this, and may be, for example, a baffle plate or a filter.

[0022] (B4) In the above-described embodiment, the water electrolysis system 100 includes a control valve 50. However, the water electrolysis system 100 is not limited to this, and may not include the control valve 50.

[0023] The present disclosure is not limited to the above-described embodiments, and can be realized in various configurations without departing from the gist thereof. For example, the technical features in the embodiments corresponding to the technical features in each form described in the summary of the invention can be appropriately replaced or combined in order to solve the above-described problems or to achieve some or all of the above-described effects. Further, if the technical feature is not described as essential in this specification, it can be appropriately deleted.

Explanation of Symbols

[0024] 10…Water electrolysis stack, 11…Oxygen outlet, 20…Gas-liquid separator, 21…Water flow path, 30…Oxygen flow path, 30a…First oxygen flow path, 30b…Second oxygen flow path, 40…Simple separation section, 50…Regulating valve, 100…Water electrolysis system

Claims

[Claim 1] A water electrolysis system, A water electrolysis stack that generates hydrogen and oxygen by the electrolysis of water, the water electrolysis stack having an oxygen outlet for discharging a discharge fluid which is a fluid containing water and the generated oxygen, A gas-liquid separator, An oxygen channel connecting the oxygen outlet and the gas-liquid separator, A water electrolysis system comprising a simple separation unit provided in the oxygen channel for separating liquid from the discharge fluid passing through it.

Images