KR20200127076A - A reliable electrolyser system - Google Patents

Abstract

Disclosed is a stable electrolysis system. The stable water electrolysis system for producing hydrogen through a water electrolysis reaction according to the present invention includes: a water electrolysis stack for producing hydrogen and oxygen, a check valve in the hydrogen discharge line, a liquid pump composed of a pressurizer, an adsorber and an oxygen discharge line, a three-way valve, an air-cooled heat exchanger, a liquid return tank, an oxygen water separator and a quantitative water pump that supplies a quantitative amount of water consumed during hydrogen production, a power supply that supplies electricity to the auxiliary water tank and the electrolysis stack, a bleed resistance part and a control device, wherein water is supplied in real-time at regular quantities upon producing hydrogen to keep the water electrolysis stack temperature constant, thereby stabilizing the hydrogen production reaction, and a constant concentration of an alkaline electrolyte solution such as anion exchange membrane water electrolysis is maintained, thereby providing constant hydrogen production. In addition, after the discharge step of discharging oxygen from the electrode of the unit cell of the water electrolysis stack, the residual voltage of the water electrolysis stack generated when the water electrolysis system is stopped, a residual voltage is removed by using the bleed resistance, so that an abnormal behavior of the electrolytic stack is prevented.

Description

A reliable electrolyser system

The present invention relates to a stable water electrolysis system, and more particularly, to maintain a constant operating temperature of a water electrolysis stack by configuring a metering pump and a pure auxiliary tank to supply water in real time as much as the amount of water consumed during hydrogen production. It is a stable water electrolysis system, and it relates to a stable water electrolysis system that can fundamentally remove the residual voltage of the water electrolysis stack that occurs when the water electrolysis system is stopped.

The conventional water electrolysis system is divided into alkaline water electrolysis, which produces hydrogen and oxygen using a water electrolysis reaction, and water electrolysis with a polymer electrolyte membrane, and water electrolysis with a polymer electrolyte membrane is again a cation exchange membrane. ) It is divided into water electrolysis and anion exchange membrane water electrolysis.

Alkaline water electrolysis uses 30 to 40 wt% of potassium hydroxide (KOH) circulating water in the electrolyte solution, and pure water is used for the cation exchange membrane water electrolysis, and the anion exchange membrane water electrolysis is typically 0.1 mol to 1 mol potassium hydroxide ( KOH) circulating water is used.

According to the Korean Patent Registration No. 10-1693826, the position of the protruding tubular protrusion and the lower end of the protruding tubular protruding toward the inside while contacting the oxygen outlet in the circulating water containing oxygen generated from the electrolysis stack. Provides a water electrolysis device that is located higher than the maximum water level of circulating water and is covered with a net.

However, Korean Patent Registration No. 10-1693826 detects the maximum water level and the minimum level of the level sensor installed in the circulating water storage tank to supply excess water for a certain period of time while supplying water consumed during hydrogen production. In addition to being able to reduce the water electrolysis performance due to a decrease in the operating temperature of the stack, there is a problem that the performance of the water electrolysis system is degraded by changing the concentration of the electrolyte (circulating water) in alkaline water electrolysis and anion exchange membrane water electrolysis. .

In addition, in the conventional Korean Patent Registration No. 10-1724060, a water electrolysis stack of an alkaline water electrolysis device, a voltage application part, a voltage removal part, and a control unit are configured, so that the water electrolysis stack in the voltage removal part is in a no-load state. A method of consuming and removing the residual voltage of the electrolytic stack by being energized with the stack is constructed. However, when the electrolytic system is stopped, oxygen in the form of microbubbles remaining in the electrode of the unit cell of the electrolytic stack is not removed. In addition, there is a problem in that a non-uniform reaction is generated in the active area of the electrolysis stack, which can have a fatal adverse effect on the durability of the electrolysis system.

Korean Patent Registration No. 10-1693826 Korean Patent Registration No. 10-1724060

Accordingly, an object of the present invention conceived to solve such a problem is to constitute a metering pump and a pure auxiliary tank that supply water as much as the amount of water consumed in the water electrolysis system, so that the water electrolysis reaction is used to produce hydrogen. It is to provide a stable water electrolysis system that maintains a constant hydrogen production rate by maintaining a constant operating temperature of the stack and a constant concentration of the electrolyte (circulating water).

In addition, after the discharge step of discharging oxygen from the electrode of the unit cell of the receiving electrolysis stack, the residual voltage generated when the electrolysis system is stopped is removed using a bleed resistor to prevent abnormal behavior of the electrolytic stack. We want to provide a way to do it.

The stable water electrolysis system according to the present invention for achieving the above object is composed of a water electrolysis stack that produces hydrogen and oxygen, a power supply, a liquid pump and an oxygen return tank, and is used in a water electrolysis system that produces hydrogen through a water electrolysis reaction. Thus, it is possible to configure a metering pump and a pure water auxiliary tank that supply water consumed during hydrogen production in real time.

In addition, by monitoring the amount of current supplied from the power supply unit, it is possible to theoretically calculate the amount of water consumed and control the operation of the metering pump supplying water in real time.

When the maximum level of the level sensor is detected, the flow rate of the metering pump is reduced for a certain period of time by using the detection of the maximum level of the level sensor and the minimum level of the oxygen return tank. It may include a method of operating the circulating water in the return tank between the minimum and maximum water levels.

In addition, when the water electrolysis system has a large capacity, oxygen and moisture cannot be completely separated by the bulkhead of the oxygen return tank, so it may include configuring a separate water separator for separating oxygen and moisture in the oxygen discharge line. .

And, in a water electrolysis system that produces hydrogen through a water electrolysis reaction, which consists of a water electrolysis stack that produces hydrogen and oxygen, a power supply unit, a liquid pump and an oxygen return tank, etc., power is supplied to the water electrolysis stack when the water electrolysis system is stopped. Stopping it; Circulating the liquid pump to remove oxygen from the unit cell electrode in the water electrolysis stack; Removing the residual voltage using the bleed resistance; By completely removing oxygen in the form of microbubbles existing in the electrode of the water electrolytic stack unit cell including, etc., and removing the residual voltage of the water electrolytic stack with bleed resistance, abnormal behavior of the electrolytic stack can be prevented.

In addition, during the step of cooling the water electrolytic stack to 40° C. or less by operating an air-cooled heat exchanger, removing oxygen from the unit cell electrodes in the water electrolytic stack; The step of removing the residual voltage using the bleed resistor may include reducing the residual voltage of the receiving electrolytic stack to a predetermined voltage by repeatedly performing it.

According to the stable water electrolysis system of the present invention described above, the water electrolysis system that produces hydrogen and oxygen through a water electrolysis reaction can prevent performance change according to the temperature of the water electrolysis stack and change in the concentration of the electrolyte (circulating water). Can ensure stable water electrolysis system performance.

In addition, by including the step of removing oxygen in the form of microbubbles present in the electrode of the water electrolysis stack unit cell when the water electrolysis system is stopped, oxygen evolution (OER) when removing the residual voltage of the water electrolysis stack using a bleed resistor is included. reaction) electrode degradation can be effectively prevented.

1 is a schematic diagram showing the configuration of a stable water electrolysis system according to a preferred embodiment of the present invention,
2 is a block diagram showing an embodiment of a water electrolysis system stop of the present invention.

Advantages and features of the present invention, and a method for achieving the same will become apparent with reference to the embodiments described below in detail together with the accompanying drawings.

However, the present invention is not limited to the embodiments disclosed below, but may be implemented in a variety of different forms, only the present embodiments make the disclosure of the present invention complete, and common knowledge in the technical field to which the present invention pertains. It is provided to completely inform the scope of the invention to those who have, and the invention is only defined by the scope of the claims. The same reference numerals refer to the same elements throughout the specification.

Thus, in some embodiments, well-known process steps, well-known structures, and well-known techniques have not been described in detail in order to avoid obscuring interpretation of the present invention.

The terms used in this specification are for describing exemplary embodiments, and are not intended to limit the present invention. In the present specification, the singular form also includes the plural form unless specifically stated in the phrase.

Comprises and/or comprising, as used in the specification, refers to the presence or addition of one or more other components, steps, actions, and/or elements other than the stated elements, steps, actions and/or elements. It is used in a sense not to exclude.

And, “and/or” includes each and every combination of one or more of the recited items.

In addition, embodiments described in the present specification will be described with reference to sectional views and/or schematic diagrams, which are ideal exemplary diagrams of the present invention.

Accordingly, embodiments of the present invention are not limited to the illustrated specific form, but include a change in form generated according to a manufacturing process.

In addition, in each of the drawings shown in the present invention, each component may be somewhat enlarged or reduced in consideration of convenience of description.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In addition, it is added that the'stable water electrolysis system' published in this specification can be implemented in various embodiments, and is not limited to the embodiments described herein.

1 is a schematic diagram showing the configuration of a stable water electrolysis system according to a preferred embodiment of the present invention.

As shown in FIG. 1, the water electrolysis stack 101 has a structure in which a plurality of unit cells and a separator are stacked in series, and produces hydrogen and oxygen through a water electrolysis reaction between electricity and water.

Since circulating water (electrolyte) circulates in the anode (OER) electrode, a pressurizer (electrolyte) is placed on the hydrogen discharge line to prevent water from flowing through the polymer electrolyte membrane from the anode electrode side to the cathode (H) 102) is configured and includes an adsorber 103 to produce high purity hydrogen of 99.99% or more and check valves 104 and 105 to prevent reverse hydrogen flow.

At the time of initial installation, it includes a purge line for nitrogen purge and an exhaust line with a solenoid valve for discharging pressurized hydrogen when the water electrolysis system is not used for a long time.

The oxygen discharge line consists of a liquid pump 106 that circulates circulating water (electrolyte), a three-way valve, and an air-cooled heat exchanger. The oxygen return tank 108 has a heater that raises the temperature of the circulating water during initial operation and the maximum of the oxygen return tank. It is composed of a level sensor that detects the water level and the lowest water level, and a partition wall structure that can separate oxygen contained in the circulating water to some extent, and a water separator 109 that separates a trace amount of circulating water transferred together with the discharged oxygen. And, although not shown in FIG. 1, the separated circulating water is connected by a pipe so that the separated circulating water can be recovered back to the oxygen return tank.

When the water electrolysis system is operated to produce hydrogen and oxygen, the amount of current from the power supply unit 112 is received from the water electrolysis system controller, and the theoretical water consumption is calculated, and based on this value, the metering pump 110 and the pure auxiliary tank 111 ), including the operation of accurately supplying water in real time as much as the amount of water consumed in the oxygen return tank 108.

When the water electrolysis system is operated for a long time, the level sensor configured in the oxygen return tank 108 is maximum Using the detection of the water level (High) and the lowest level (Low), when the maximum level of the level sensor is detected, the flow rate of the metering pump is reduced for a certain period of time, so that the circulating water (electrolyte) in the oxygen return tank operates between the minimum and maximum water levels. Characterized in that.

2 is a block diagram showing an embodiment of a water electrolysis system stop of the present invention.

In FIG. 2, the electrolysis stack 101 and the hydrogen discharge line are composed of a pressurizer 102, an adsorber 103, and check valves 104 and 105, and an exhaust line comprising a purge line and a solenoid valve for discharging pressurized hydrogen. Consists of

The oxygen discharge line consists of a liquid pump 106 that circulates circulating water (electrolyte), a three-way valve, and an air-cooled heat exchanger, and the oxygen return tank 108 includes a heater and an oxygen return tank that increase the temperature of the circulating water during initial operation. It is composed of a level sensor that detects the maximum and minimum water levels and a partition wall structure that can separate oxygen contained in the circulating water to some extent, and a water separator 109 that separates a trace amount of circulating water transferred together with the discharged oxygen. It is configured and, although not shown in FIG. 2, is connected by a pipe so that the separated circulating water can be recovered back to the oxygen return tank.

Stopping the supply of power from the power supply unit 112 to the electrolysis stack 101 when the water electrolysis system is stopped; Circulating the liquid pump 106 to remove oxygen in the form of fine bubbles in the anode electrode of the unit cell of the water electrolysis stack 101; Since it includes a step of removing the residual voltage of the water-receiving stack 101 using the bleed resistor 113, it is possible to prevent deterioration of the anode electrode and the polymer electrolyte film.

It is preferable to circulate the liquid pump 106 at a rated circulating water flow rate for 5 to 10 minutes in order to remove oxygen present in the anode electrode.

In addition, in order to suppress the electrode reaction in the active state of the water electrolytic stack at a high temperature (60°C or higher), during the step of cooling the water electrolytic stack 101 to 40°C or lower by operating an air-cooled heat exchanger, the water electrolytic stack 101 Removing oxygen from the electrode of the unit cell; The step of removing the residual voltage using the bleed resistor 113 is repeatedly performed to reduce the residual voltage of the receiving electrolytic stack below a certain voltage, and the residual voltage of the receiving electrolytic stack 101 is the theoretical potential of the anode electrode 0.4 Considering that V, the theoretical potential of the cathode electrode is -0.83V, it is preferable to reduce the residual voltage of the unit cell of the receiving electrolytic stack 101 to 0.45V or less.

In the above, the preferred embodiments of the present invention have been exemplarily described, but the scope of the present invention is not limited to such specific embodiments, and within the scope apparent to those skilled in the art who understand the spirit of the present invention, components Other embodiments may be proposed by addition, change, deletion, addition, etc. of the present invention, but this should also be construed as falling within the scope of the claims of the present invention.

101: water electrolysis stack, 102: pressurizer,
103: adsorber, 104, 105: check valve,
106: liquid pump, 107: air-cooled radiator,
108: oxygen return tank 109: oxygen water separator,
110: metering pump, 111: pure water auxiliary tank,
112: power supply, 113: bleed resistance.

Claims (6)

In a water electrolysis system that uses electricity and water to produce hydrogen, it is composed of a water electrolysis stack that produces hydrogen and oxygen, a power supply, a liquid pump, and an oxygen return tank,
A stable water electrolysis system comprising a metering pump and a pure water auxiliary tank that supply water consumed during hydrogen production in real time.
The method of claim 1,
And a metering pump operation control that monitors the amount of current supplied from the power supply and supplies water as much as consumed water in real time.
The method of claim 1,
When the maximum level of the level sensor is detected, the flow rate of the metering pump is controlled for a certain period of time by using the detection of the maximum level of the level sensor and the minimum level of the oxygen return tank. Stable water electrolysis system, characterized in that the circulating water in the return tank operates between the minimum and maximum water levels.
The method of claim 1,
Stable water electrolysis system comprising a water separator for separating oxygen and moisture in the oxygen discharge line.
In a water electrolysis system that uses electricity and water to produce hydrogen, it is composed of a water electrolysis stack that produces hydrogen and oxygen, a power supply, a liquid pump, and an oxygen return tank,
Stopping power supply to the receiving electrolysis stack when the receiving electrolysis system is stopped; Removing oxygen from the electrode of the unit cell in the water electrolysis stack; Stable water electrolysis system comprising the step of removing the residual voltage using a bleed resistance.
The method of claim 5,
Removing oxygen from the unit cell electrodes in the water electrolytic stack during the step of cooling the water electrolytic stack to 40° C. or less; Stable water electrolysis system, characterized in that the step of removing the residual voltage by using the bleed resistance comprises repeatedly performing the step of reducing the water electrolytic stack to a certain voltage below.

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