KR102689617B1 - System of high-temperature steam electrolysis with extended life by high-temperature steam electrolysis reactor design control - Google Patents

Abstract

The present invention relates to a high-temperature water electrolysis system with improved performance by controlling the boundary area of the bus bar that meets the high-temperature box. The high-temperature water electrolysis system according to an embodiment of the present invention is formed of a high-temperature water electrolysis stack and metal, It is connected to the high-temperature water electrolysis stack, and includes a power supply unit including a portion whose cross-sectional area becomes smaller as the distance from the end connected to the high-temperature water electrolysis stack increases.

Description

High-temperature water electrolysis system with extended life through shape control of the high-temperature water electrolysis reactor {SYSTEM OF HIGH-TEMPERATURE STEAM ELECTROLYSIS WITH EXTENDED LIFE BY HIGH-TEMPERATURE STEAM ELECTROLYSIS REACTOR DESIGN CONTROL}

The present invention relates to a high-temperature water electrolysis system in which performance is improved by controlling the boundary area of the bus bar that meets the high-temperature box in the shape of the high-temperature water electrolysis reactor.

High-temperature water electrolysis stacks are generally designed and manufactured based on solid oxide fuel cell (SOFC) technology.

Since high-temperature water electrolysis (H2O → H2 + 1/2O2) is the reverse reaction of the fuel cell reaction (H2 + 1/2O2 → H2O), the solid oxide fuel cell (SOFC) stack can be used as is.

In the fuel cell mode, hydrogen and oxygen are used to generate water and current, and when changed to high-temperature water electrolysis mode, water and current are used to generate hydrogen and oxygen.

High-temperature water electrolysis (Solid Oxide Electrolysis Cell, SOEC) technology obtains hydrogen and oxygen by directly electrolyzing high-temperature steam, and is more efficient than electrolysis of room-temperature and low-temperature water. This is because the amount of electrolysis energy consumed in high-temperature steam is less than that in room temperature water, and the higher the temperature, the less electrolysis energy is consumed. Therefore, if a low-cost heat source that can raise the temperature of room temperature water is secured, high-temperature water electrolysis technology can theoretically become the most efficient hydrogen production technology.

However, high-temperature water electrolysis technology has a wider operating temperature than general water electrolysis, and high-temperature water electrolysis cells and sealing materials made of ceramics and high-temperature water electrolysis stacks made of metal have lower durability than general water electrolysis.

Therefore, there is a need for a high-temperature water electrolysis system that can be operated with extended service life despite low durability.

Japanese Patent Publication No. 2017-520685

The present invention is intended to solve the above problems and aims to provide a high-temperature water electrolysis system that can be operated efficiently so that it can be used for a longer period of time than before.

In order to achieve the above object, the present invention provides a high-temperature water electrolysis system formed as follows.

The high-temperature water electrolysis system according to an embodiment of the present invention is formed of a high-temperature water electrolysis stack and metal, and is connected to the high-temperature water electrolysis stack, wherein the cross-sectional area becomes smaller as the distance from the end connected to the high-temperature water electrolysis stack increases. It includes a power supply unit including.

It further includes a high-temperature box that surrounds the high-temperature water electrolysis stack, prevents heat exchange with the outside, and forms a predetermined space inside, wherein the power supply unit includes a high-temperature conductor that is a conductor of a flexible material, and is connected to the high-temperature conductor, The cross-sectional area becomes smaller as the distance from the part connected to the high-temperature conductor increases, and at least a portion may include a bus bar located outside the high-temperature box.

The cross-sectional area of the bus bar may change for each predetermined length, or the cross-sectional area may change in proportion to the distance from one end to the other end.

It further includes a driving unit connected to the power supply unit and a control unit that controls the driving unit, wherein the driving unit moves the bus bar closer to or away from the high-temperature water electrolysis stack, and at a point where it meets the high-temperature box. The cross section of the bus bar may decrease over time.

It further includes a displacement sensor that measures the position of a point of the bus bar, and a temperature sensor that measures the temperature of the high-temperature water electrolysis stack, and the control unit measures the displacement of the bus bar measured by the displacement sensor and the temperature sensor. By receiving the temperature of the high-temperature water electrolysis stack measured in , it can be determined whether the measured temperature increases as the measured displacement increases.

The control unit may control the driving unit so that the displacement of the bus bar measured by the displacement sensor gradually increases in proportion to the time during which the high-temperature water electrolysis stack is operated.

The control unit may control the driving unit so that the bus bar has a preset displacement when the operation time of the high-temperature water electrolysis stack elapses a preset time.

Further comprising a voltage meter for measuring the voltage of the high-temperature water electrolysis stack, wherein the control unit receives the displacement of the bus bar measured by the displacement sensor and the voltage of the high-temperature water electrolysis stack measured by the voltage meter, By measuring the average voltage of the high-temperature water electrolysis stack and comparing it to the average voltage before the cross-sectional area is controlled to become smaller, it can be determined whether the measured average voltage has decreased.

Through the above structure, the present invention can extend the lifespan by increasing the operation period of the high-temperature water electrolysis system and provide hydrogen to consumers at a relatively low cost.

Figure 1 is a perspective view of an existing high-temperature water electrolysis stack.
Figure 2 is a schematic diagram schematically showing an existing high-temperature water electrolysis stack.
Figure 3 is a conceptual diagram of a high-temperature water electrolysis system according to an embodiment of the present invention.
Figure 4 shows the shapes of various embodiments of a bus bar according to an embodiment of the present invention.
Figure 5 shows a state in which the high-temperature water electrolysis system is controlled according to an embodiment of the present invention, where (a) shows a reference state before control and (b) shows a state in which the cross-sectional area is controlled to decrease.
Figure 6 shows a flowchart of a control method for a high-temperature water electrolysis system according to an embodiment of the present invention.
Figure 7 shows a flowchart of a control method for a high-temperature water electrolysis system according to another embodiment of the present invention.
Figure 8 is a graph showing the life extension effect of the present invention, where (a) shows the lifespan in the case of a general high-temperature water electrolysis system, and (b) shows the lifespan in the case of an embodiment of the present invention.

Hereinafter, specific embodiments of the present invention will be described with reference to the attached drawings. However, the spirit of the present invention is not limited to the presented embodiments, and those skilled in the art who understand the spirit of the present invention may add, change, or delete other components within the scope of the same spirit, or create other degenerative inventions or this invention. Other embodiments that are included within the scope of the inventive idea can be easily proposed, but it will also be said that this is included within the scope of the inventive idea of the present application.

The purpose of the present invention is to optimize hydrogen production efficiency and extend the operation time of the high-temperature water electrolysis stack by controlling the temperature of the stack itself to increase according to the operating time of the high-temperature water electrolysis stack.

Figure 1 is a perspective view of an existing high-temperature water electrolysis stack, and Figure 2 shows a schematic diagram of an existing high-temperature water electrolysis stack.

The high-temperature water electrolysis stack 1 may have a plurality of cells U stacked between a lower unit and an upper unit. In addition, a plurality of pipes 11, 12, 13, and 14 may be formed so that air and water vapor can be transferred into the high-temperature water electrolysis stack 1, and the remaining water vapor, generated hydrogen, and air can be discharged. In order to supply power, a power supply unit 2 made of metal is formed in the high-temperature water electrolysis stack 1. The power supply unit 2 includes a first sub-supply unit 2a and a second sub-supply unit 2b, and the first sub-supply unit 2a and the second sub-supply unit 2b provide a high-temperature stack and a low-temperature power source. It is structured to connect.

가 될 수 있고, 이에 비하여 고온 박스(3)의 외부는 거의 상온과 가까운 온도로서 온도차가 상당할 수밖에 없다.In general, the high-temperature water electrolysis stack 1 has an internal space 31 in which a high-temperature system component can be located, and is located inside a high-temperature box 3 made of an insulating material for insulation. And, the inside of the high temperature box (3) is at a very high temperature of 600-1000

In comparison, the outside of the high temperature box 3 is almost at room temperature, so the temperature difference is bound to be significant.

Since the power supply unit 2 is connected from the inside of the high temperature box 3 to the power source outside the high temperature box 3, not only does it supply power, but large conduction occurs from the viewpoint of heat. In addition, since the power supply unit 2 is made of metal, the heat conduction coefficient is large and heat conduction occurs better than other materials.

Therefore, the temperature of the high-temperature water electrolysis stack (1) can be changed by controlling the area of the boundary (B) where the high-temperature box and the power supply unit (2) meet, which is a part where heat loss occurs significantly.

The boundary B may be formed of a boundary B1 that meets the first sub-supply unit 2a and a boundary B2 that meets the second sub-supply unit 2b.

Figure 3 shows a conceptual diagram of a high-temperature water electrolysis system according to an embodiment of the present invention. Figure 4 schematically shows a bus bar according to an embodiment of the present invention.

The high-temperature water electrolysis system according to an embodiment of the present invention includes a high-temperature water electrolysis stack (1) and a power supply unit (2).

The high-temperature water electrolysis stack (1) refers to the above-mentioned description.

The overall reaction of the high-temperature water electrolysis stack (1) is As a technology for obtaining hydrogen, the fuel electrode Hydrogen is generated through the reaction, and at the air electrode, Oxygen is generated through the reaction.

기준, 1.28V)보다 높은 전압에서 작동하는 경우 발열을 하게 된다. 고온수전해의 반응열은 흡열이나, 저항에 의한 발열이 있기 때문에 특정 조건에서 열 중립을 이루게 된다. 그리고 일반적으로 고온수전해는 발열조건에서 운전을 하게 되고, 본 발명에 있어서도 발열조건인 경우를 전제로 한다.The high-temperature water electrolysis stack (1) has a thermal neutral voltage (700

If operated at a voltage higher than the standard (1.28V), it will generate heat. The reaction heat of high-temperature water electrolysis is endothermic, but heat is generated due to resistance, so it becomes thermally neutral under certain conditions. In general, high-temperature water electrolysis is operated under exothermic conditions, and the present invention also assumes exothermic conditions.

The power supply unit 2 is made of metal, is connected to the high-temperature water electrolysis stack 1, and includes a portion whose cross-sectional area becomes smaller as the distance from the end connected to the high-temperature water electrolysis stack 1 increases.

The power supply unit 2 is made of metal and receives power from an external power source. And, one end is connected to the high-temperature water electrolysis stack (1) to supply current to the high-temperature water electrolysis stack (1).

At least a portion includes a portion whose cross-sectional area becomes smaller as it moves away from the end connected to the high-temperature water electrolysis stack 1, so that the amount of heat convected to the outside can be adjusted by adjusting the position of the portion.

The high-temperature water electrolysis stack (1) according to an embodiment of the present invention further includes a high-temperature box (3).

The high temperature box 3 surrounds the high temperature water electrolysis stack 1, prevents heat exchange with the outside, and forms a predetermined internal space 31. Therefore, parts that must be maintained at high temperatures can be located in a predetermined space.

The power supply unit 2 of the high-temperature water electrolysis stack 1 according to an embodiment of the present invention further includes a high-temperature conductor 21 and a bus-bar 22.

The high-temperature conductor 21 may include a first high-temperature conductor 21a and a second high-temperature conductor 21b connected to the high-temperature water electrolysis stack 1, and the bus bar 22 is connected to the first high-temperature conductor 21a. It may include a first bus bar (22a) connected to and a second bus bar (22b) connected to the second high-temperature conductor (22b).

The high-temperature conductor 21 is made of a material that has better efficiency when used at high temperatures and has flexible properties. One end of the high-temperature conductor 21 is connected to the high-temperature water electrolysis stack 1, and the other end is connected to the bus bar 22.

The bus bar 22 is connected to the high-temperature conductor 21 and has a smaller cross-sectional area as it moves away from the part connected to the high-temperature conductor 21, and at least part of it may be located outside the high-temperature box 3. .

Accordingly, the bus bar 22 may be partially located inside the high temperature box 3 and the remainder may be located outside the high temperature box 3.

The other end of the bus bar 22 may be directly connected to a power source, but may further include a low-temperature conductor 23.

The low-temperature conductor 23 may include a first low-temperature conductor 23a connected to the first bus bar 22a and a second low-temperature conductor 23b connected to the second bus bar 22b.

The low-temperature conductor 23 is made of a material with higher efficiency when used at low temperatures, and can be formed flexibly like the high-temperature conductor 21. One end of the low-temperature conductor 23 is connected to the bus bar 22, and the other end is connected to a power source, so that power can be supplied to the bus bar 22 through the low-temperature conductor 23.

The bus bar 22 according to an embodiment of the present invention may be formed so that its cross-sectional area changes for each predetermined length, or its cross-sectional area changes in proportion to the distance from one end to the other end.

The bus bar 22 may be formed so that its cross-sectional area changes. For example, the cross-sectional area may become smaller as the distance from the point connected to the high-temperature conductor 21 increases.

For example, the shape of the cross section is not specified, but it may be a polygonal shape such as a square cross section (Sa) or a shape such as a cylindrical cross section (Sb).

Alternatively, the cross-sectional area may change at every predetermined length, and the cross-section Sc may change in a stepwise manner after continuing for a predetermined section with a constant cross-sectional area. The number of sections and their rate of change may vary depending on the design.

Additionally, the widest cross-sectional area may be formed in the section connected to the high-temperature conductor 21, and the narrowest cross-sectional area may be formed in the section connected to the low-temperature conductor 23.

It is not limited to the above embodiment, and may include any shape in which the cross-sectional area of the bus bar 22 changes so as to obtain the effect of the present invention.

According to one embodiment of the present invention, a control unit 5 and a driving unit 4 may be further provided.

The driving unit 4 is connected to the power supply unit 2 and may be located outside the high temperature box 3. In general, the driving unit 4 may include a motor, a rotation axis, and a push bar that can move forward or backward by the rotation axis. Therefore, when power is applied to the driving unit 4, the power supply unit 2 can be connected to advance toward the inside of the high temperature box 3 or backward to the outside through the above configuration.

The control unit 5 can control the driving unit 4.

As an example, the control unit 5 causes the driving unit 4 to move the bus bar of the power supply unit 2 closer to or farther away from the high temperature water electrolysis stack 1, and at the boundary where it meets the high temperature box 3. The cross section of the bus bar 22 can be controlled to decrease over time.

The control unit 5 controls the driving unit 4, so that the driving unit 4 controls the power supply unit 2 to move forward toward the high temperature water electrolysis stack 1, thereby meeting the boundary with the high temperature box 3. The cross section of the bus bar 22 can be controlled to change with time.

The control unit 5 controls the cross-sectional area of the bus bar 22 at the boundary where it meets the high temperature box 3 to vary depending on the preset operating time of the high temperature water electrolysis stack 1, and through this, the high temperature water electrolysis stack 1 By reducing the size of conduction heat loss through the bus bar 22, the internal temperature of the high-temperature water electrolysis stack 1 can be controlled to gradually increase.

This temperature increase effect can increase the operating time of the high-temperature water electrolysis stack (1) and optimize the hydrogen production efficiency of the high-temperature water electrolysis stack (1).

According to one embodiment of the present invention, the high-temperature water electrolysis stack (1) further includes a sensor measuring unit (6), a displacement sensor (61), a temperature sensor (62), and a voltage meter (63). , the control by the control unit 5 can be precisely measured and the effect of the control can be confirmed.

Figure 5 shows the state of the bus bar measured at different times according to an embodiment of the present invention. Figure 6 is a flow chart for confirming the effect of control by measuring temperature according to an embodiment of the present invention, and Figure 7 is a flow chart for confirming control by measuring voltage according to an embodiment of the present invention.

According to one embodiment of the present invention, the high-temperature water electrolysis stack 1 further includes a displacement sensor 61 and a temperature sensor 62, and the control unit 5 controls the bus bar 22 with the displacement sensor 61. The degree of movement can be measured and recognized, and whether the high-temperature water electrolysis system has been effective can be checked using the temperature sensor 62.

The displacement sensor 61 measures the current position of the bus bar 22 based on the time before the bus bar 22 is moved. At this time, the position can be measured based on one point of the bus bar 22.

The displacement sensor 61 may be located outside the high temperature box 3 and may be configured to measure at a certain distance using a laser or the like. The displacement sensor 61 uses the position of the end of the bus bar 22 connected to the low-temperature conductor 23 before operation as a reference (x = 0), and the end of the bus bar 22 connected to the low-temperature conductor 23 is The displacement (x1) of the amount moved can be measured.

And the control unit 5 continuously controls the driving unit 4 so that the displacement of the bus bar 22 measured by the displacement sensor 61 gradually increases in proportion to the time the high-temperature water electrolysis stack 1 is operated. can do. Alternatively, the control unit 5 controls the driving unit 4 so that the bus bar 22 has a preset displacement when the operation time of the high temperature water electrolysis stack 1 exceeds a preset time, and the high temperature water electrolysis stack If (1) satisfies a certain condition, the displacement of the bus bar 22 may change non-continuously by temporarily operating the drive unit 4.

As the displacement is controlled as described above, the cross-sectional area (S1) after control becomes smaller than the cross-sectional area (S0) on the existing boundary.

After controlling the driving unit 4, the control unit 5 can check whether the control has been properly performed through changes in the high-temperature water electrolysis stack 1.

For example, the displacement of the bus bar 22 measured by the displacement sensor 61 and the temperature of the high-temperature water electrolysis stack 1 measured by the temperature sensor 62 are input, and the measured displacement increases. Accordingly, it can be confirmed whether the measured temperature increases.

If the measured temperature is greater than before, the control of the drive unit 4 is correct, so the control unit 5 maintains the current state of continuous or non-continuous control of the drive unit 4.

For example, the control unit 5 receives the displacement of the bus bar 22 measured by the displacement sensor 61 and the voltage of the high-temperature water electrolysis stack 1 measured by the voltage meter 63, By measuring the average voltage of the high-temperature water electrolysis stack 1, it is possible to check whether the measured average voltage has decreased by comparing it with the average voltage before the cross-sectional area is controlled to become smaller.

That is, the control effect of the high-temperature water electrolysis stack 1 can be known through the average voltage or the temperature of the high-temperature water electrolysis stack 1 in the high-temperature box 3.

The control unit may perform a step (S10) of recognizing a preset condition. The preset conditions are all preset conditions, such as starting control when the stack has been operated for a certain period of time, starting control when a certain voltage or temperature is reached, performing continuous control in proportion to the operation time, or performing discontinuous control. It can be included.

Then, the controller performs a step (S20) of controlling the driving unit so that the bus bar is drawn into the hot box compared to the reference point so that the displacement after control is greater than the displacement up to one end of the existing bus bar.

After that, the temperature in the stack can be measured using the sensor measurement unit 6 through a step (S31) or a voltage of the stack (S32).

Additionally, the control unit may receive the measured value and include a step of determining whether the measured temperature has increased compared to the existing temperature (S41) or whether the measured voltage has decreased compared to the existing voltage (S42). The existing value can be a value measured and stored before control, or can be determined by inputting the existing value.

After that, if it is determined that the above control has been achieved, the status quo will be maintained and control will be performed again according to the existing preset conditions. If the control is judged to be incorrect, the displacement will be controlled again, and feedback control will be performed to issue an external alarm. It may be possible. The control unit of the present invention is not limited to the above control.

Figure 8 is a graph showing the effect of extending the lifespan of the present invention, (a) showing the lifespan in the case of a general high-temperature water electrolysis system, and (b) a graph showing the lifespan in the case of an embodiment of the present invention. am.

Referring to FIG. 8, the progress of the deterioration rate can be known depending on the voltage within the high-temperature water electrolysis stack 1. When the voltage exceeds a certain level, it is generally judged that the lifespan has ended. In general, when the deterioration rate progresses to about 10%, the hydrogen production efficiency drastically decreases and it is not economical, so the lifespan of the high-temperature water electrolysis system can be considered to have ended.

When the temperature of the stack rises, even if the high-temperature water electrolysis system is electrically controlled to produce the same amount of hydrogen with the same amount of current, the average voltage of the stack decreases and therefore the amount of applied power is reduced. Therefore, hydrogen production efficiency improves.

Additionally, as the voltage increases, the high-temperature water electrolysis cell and sealing material made of ceramic and the high-temperature water electrolysis stack 1 made of metal deteriorate. Therefore, the lifespan is generally determined in proportion to the voltage.

(a) Looking at the graph, in general, when a certain point is reached in proportion to time, the voltage becomes above a certain point, and that point can be called the lifespan (T1).

However, looking at graph (b), which is a graph of the high temperature water electrolysis system according to an embodiment of the present invention, the cross-sectional area on the interface between the bus bar 22 and the high temperature box 3 at a certain point in time (t1, t2, t3) is It is controlled to be narrow, so the temperature of the high-temperature water electrolysis stack 1 itself increases, which has the effect of reducing the average voltage. Therefore, it provides the effect of extending the lifespan (T2) compared to the lifespan (T1) of the existing system.

Therefore, the present invention provides the effect of delaying deterioration and extending the lifespan by controlling the voltage to lower. As a result, the lifespan can be extended, lowering the production cost of hydrogen and providing hydrogen to consumers at a reasonable cost.

In the above, the present invention has been described focusing on the embodiments, but the present invention is not limited to the above-described embodiments, and may be modified and implemented by those skilled in the art without changing the technical spirit of the present invention as claimed in the claims. Of course.

1: High temperature water electrolysis stack 2: Power supply unit
3: High temperature box 4: Drive part
5: Control unit 6: Sensor measurement unit
11, 12, 13, 14: Piping 21: High temperature conductor
22: bus bar 23: low temperature wire
31: Internal space B: Boundary surface
U: cell

Claims (8)

High-temperature water electrolysis stack;
A power supply unit made of metal, connected to the high-temperature water electrolysis stack, and including a portion whose cross-sectional area becomes smaller as the distance from the end connected to the high-temperature water electrolysis stack increases; and
It includes a high-temperature box that surrounds the high-temperature water electrolysis stack, prevents heat exchange with the outside, and forms a predetermined space inside,
The power supply unit,
A high-temperature conductor, which is a conductor made of flexible material,
A high-temperature water electrolysis system comprising a bus bar connected to the high-temperature conductor, having a cross-sectional area that becomes smaller as the distance from the portion connected to the high-temperature conductor increases, and at least a portion of the bus bar is located outside the high-temperature box.
delete According to paragraph 1,
The bus bar is,
The cross-sectional area changes for each given length, or
A high-temperature water electrolysis system in which the cross-sectional area changes in proportion to the distance from one end to the other.
According to paragraph 3,
A driving unit connected to the power supply unit,
Further comprising a control unit that controls the driving unit,
The control unit,
The driving unit moves the bus bar closer to or farther away from the high-temperature water electrolysis stack,
A high-temperature water electrolysis system in which the cross-section of the bus bar at the point where it meets the high-temperature box decreases with time.
According to paragraph 4,
A displacement sensor that measures the position of a point on the bus bar,
It further includes a temperature sensor that measures the temperature of the high-temperature water electrolysis stack,
The control unit,
Receives the displacement of the bus bar measured by the displacement sensor and the temperature of the high-temperature water electrolysis stack measured by the temperature sensor,
A high-temperature water electrolysis system that determines whether the measured temperature increases as the measured displacement increases.
According to clause 5,
The control unit,
In proportion to the time the high temperature water electrolysis stack is operated
A high-temperature water electrolysis system that controls the driving unit so that the displacement of the bus bar measured by the displacement sensor gradually increases.
According to clause 5,
The control unit,
A high-temperature water electrolysis system that controls the driving unit so that the bus bar has a preset displacement when the operation time of the high-temperature water electrolysis stack exceeds a preset time.
According to paragraph 4,
A displacement sensor that measures the position of a point on the bus bar,
Further comprising a voltage meter that measures the voltage of the high-temperature water electrolysis stack,
The control unit,
Receives the displacement of the bus bar measured by the displacement sensor and the voltage of the high-temperature water electrolysis stack measured by the voltage meter,
A high-temperature water electrolysis system that measures the average voltage of the high-temperature water electrolysis stack and compares it with the average voltage before controlling the cross-sectional area to be smaller to determine whether the measured average voltage has decreased.

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