JP2021036491A - Redox flow battery system, and method for operating redox flow battery system - Google Patents

Abstract

To provide a redox flow battery system capable of efficiently heating an electrolyte solution and supplying a battery cell with the electrolyte solution which has reached a predetermined temperature.SOLUTION: A redox flow battery system comprises: a tank for pooling an electrolyte solution; a battery cell; and a circulation mechanism for circulating the electrolyte solution between the tank and the battery cell. The circulation mechanism has: an outward route for supplying the electrolyte solution in the tank to the battery cell; a return route for discharging the electrolyte solution from the battery cell to the tank; and a pump for pneumatically feeding the electrolyte solution in the tank. The circulation mechanism includes: a bypass route for connecting the outward route and the return route, or the outward route and the tank to bypass the battery cell; and a switching structure for switching between the circulation of the electrolyte solution to the battery cell and the circulation to the bypass route.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a redox flow battery system and a method of operating the redox flow battery system.

The redox flow battery of Patent Document 1 includes a cell, an electrolytic solution tank, a pipe, and a means for blowing warm air. The pipe connects the cell and the electrolyte tank, and the electrolyte flows from the electrolyte tank to the cell. The means for blowing warm air is to blow warm air from the outside of the pipe to at least a part of the pipe. The electrolytic solution warmed by the warm air is supplied to the battery cell. In addition, Patent Document 2 discloses a redox flow battery.

JP-A-2002-015762 Japanese Unexamined Patent Publication No. 2003-123808

In the above-mentioned redox flow battery, depending on the temperature of the electrolytic solution in the tank, the electrolytic solution may be supplied to the battery cell without reaching a predetermined temperature. In that case, since the viscosity of the electrolytic solution is high, the pressure loss becomes high. As a result, the charge / discharge reaction is suppressed, so that the battery efficiency is lowered and the battery performance is lowered.

Therefore, an object of the present disclosure is to provide a redox flow battery system capable of efficiently heating an electrolytic solution and supplying an electrolytic solution having reached a predetermined temperature to a battery cell, and a method of operating the redox flow battery system. Let it be one.

The redox flow battery system according to the present disclosure is
A tank for storing electrolyte and
Battery cell and
A distribution mechanism for circulating the electrolytic solution between the tank and the battery cell is provided.
The distribution mechanism
The outbound route for supplying the electrolytic solution in the tank to the battery cell, and
A return path for discharging the electrolytic solution from the battery cell to the tank, and
A redox flow battery system comprising a pump for pumping the electrolyte in the tank.
The distribution mechanism
A bypass path that connects the outward path and the return path, or the outward path and the tank, and bypasses the battery cell.
It is provided with a switching structure for switching between distribution of the electrolytic solution to the battery cell and distribution to the bypass path.

The operation method of the redox flow battery system according to the present disclosure is described.
A method of operating a redox flow battery system that circulates the electrolytic solution between a tank in which the electrolytic solution is stored and a battery cell.
When the temperature of the electrolytic solution in the tank satisfies a predetermined temperature range, the battery cell is bypassed and the electrolytic solution is circulated from the outward path to the return path of the battery cell or from the outward path to the tank.

In the operation method of the redox flow battery system according to the present disclosure and the redox flow battery system according to the present disclosure, the electrolytic solution can be efficiently heated and the electrolytic solution reaching a predetermined temperature can be supplied to the battery cell.

FIG. 1 is a configuration diagram showing an outline of a redox flow battery system according to the first embodiment. FIG. 2 is a configuration diagram showing an outline of the redox flow battery system according to the second embodiment. FIG. 3 is a configuration diagram showing an outline of the redox flow battery system according to the third embodiment. FIG. 4 is a configuration diagram showing an outline of the redox flow battery system according to the fourth embodiment. FIG. 5 is a configuration diagram showing an outline of the redox flow battery system according to the fifth embodiment. FIG. 6 is a graph showing the relationship between the temperature of the electrolytic solution and the outside air temperature when the electrolytic solution is circulated in the bypass path in the test example. FIG. 7 is a graph showing the relationship between the temperature of the electrolytic solution and the outside air temperature when the tank is heated from the outside by a heater in a test example.

<< Explanation of Embodiments of the present disclosure >>
First, embodiments of the present disclosure will be listed and described.

(1) The redox flow battery system according to one aspect of the present disclosure is
A tank for storing electrolyte and
Battery cell and
A distribution mechanism for circulating the electrolytic solution between the tank and the battery cell is provided.
The distribution mechanism
The outbound route for supplying the electrolytic solution in the tank to the battery cell, and
A return path for discharging the electrolytic solution from the battery cell to the tank, and
A redox flow battery system comprising a pump for pumping the electrolyte in the tank.
The distribution mechanism
A bypass path that connects the outward path and the return path, or the outward path and the tank, and bypasses the battery cell.
It is provided with a switching structure for switching between distribution of the electrolytic solution to the battery cell and distribution to the bypass path.

The redox flow battery system can efficiently heat the electrolytic solution and supply the electrolytic solution that has reached a predetermined temperature to the battery cell. In the following description, the redox flow battery system may be referred to as an RF battery system.

The reason why the electrolytic solution can be heated efficiently is as follows. In the RF battery system, the distribution mechanism has a bypass path and a switching structure, so that the distribution of the electrolytic solution to the battery cell and the distribution of the electrolytic solution to the bypass path can be switched. That is, the RF battery system can be discharged to the tank through the bypass path without supplying the electrolytic solution to the battery cell. The temperature of the electrolytic solution rises because it is rubbed against the rotor of the pump and the inner surface of the bypass path by driving the pump. The length of the distribution path through which the electrolytic solution flows through the bypass path is shorter than the length of the distribution path through which the electrolytic solution flows through the battery cell. Therefore, the electrolytic solution warmed by the drive of the pump can be quickly returned to the tank through the bypass path. Therefore, the temperature of the electrolytic solution is unlikely to drop in the middle of the distribution channel. That is, the warmed electrolytic solution is returned to the tank and mixed with the electrolytic solution in the tank with almost no decrease in temperature.

The reason why the electrolytic solution having reached a predetermined temperature can be supplied is as follows. As described above, the RF battery system can return the electrolytic solution warmed by the drive of the pump to the tank without supplying the battery cell via the bypass path. Therefore, it is possible to suppress the supply of the electrolytic solution before reaching a predetermined temperature to the battery cell. In other words, in the RF battery system, the electrolytic solution that has reached a predetermined temperature is circulated to the battery cell. Therefore, the RF battery system can promote the charge / discharge reaction and improve the battery efficiency, so that the battery performance can be improved.

(2) As a form of the above RF battery system,
The switching structure is
The first valve that opens and closes the bypass path,
It is mentioned that it has a portion higher than the highest position of the bypass path downstream of the outward path than the connection point between the outward path and the bypass path.

In the above configuration, the electrolytic solution can be circulated to the bypass path by opening the bypass path by the first valve. The head of the outbound route is larger than that of the bypass route because the outward route has a portion higher than the highest position of the bypass route downstream thereof. Therefore, when the bypass path is opened by the first valve, it becomes difficult for the electrolytic solution to flow downstream of the outward path, and it can be easily flowed to the bypass path. Further, in the above configuration, the electrolytic solution can be supplied to the battery cell by closing the bypass path by the first valve.

(3) As a form of the above RF battery system,
The switching structure is
The first valve that opens and closes the bypass path,
It is mentioned that it has a second valve that opens and closes the downstream side of the outward path from the connection point between the outward path and the bypass path.

In the above configuration, the bypass path is opened by the first valve, and the downstream of the outward path is closed by the second valve, so that the electrolytic solution can be circulated to the bypass path. Further, in the above configuration, the electrolytic solution can be supplied to the battery cell by closing the bypass path by the first valve and opening the downstream of the outward path by the second valve.

(4) As a form of the above RF battery system,
The switching structure is
The first valve that opens and closes the bypass path,
It can be mentioned that the cross-sectional area of the internal space in the bypass path has a portion larger than the cross-sectional area of the internal space in the outward path.

In the above configuration, the electrolytic solution can be circulated to the bypass path by opening the bypass path by the first valve. This is because the bypass path has a portion having a larger cross-sectional area in the internal space than the outward path, so that when the bypass path is opened by the first valve, the electrolytic solution easily flows to the bypass path. Further, in the above configuration, the electrolytic solution can be supplied to the battery cell by closing the bypass path by the first valve.

(5) As a form of the above RF battery system,
The switching structure may include a switching valve attached to a connection point between the outward path and the bypass path.

In the above configuration, the bypass path is opened by the switching valve and the downstream of the outward path is closed, so that the electrolytic solution can be circulated to the bypass path. Further, in the above configuration, the electrolytic solution can be supplied to the battery cell by closing the bypass path by the switching valve and opening the downstream path of the outward path.

(6) As a form of the above RF battery system,
A liquid temperature detection unit that detects the temperature of the electrolytic solution in the tank, and
An operation control unit that controls the operation of the pump and the switching operation of the switching structure based on the detection result of the liquid temperature detecting unit can be mentioned.

In the above configuration, the distribution of the electrolytic solution to the battery cell and the distribution to the bypass path can be switched according to the temperature of the electrolytic solution, so that the electrolytic solution before reaching a predetermined temperature is supplied to the battery cell. Can be suppressed, and the electrolytic solution that has reached a predetermined temperature can be circulated to the battery cell.

(7) The operation method of the RF battery system according to one aspect of the present disclosure is as follows.
A method of operating a redox flow battery system that circulates the electrolytic solution between a tank in which the electrolytic solution is stored and a battery cell.
When the temperature of the electrolytic solution in the tank satisfies a predetermined temperature range, the battery cell is bypassed and the electrolytic solution is circulated from the outward path to the return path of the battery cell or from the outward path to the tank.

In the above-mentioned operation method of the RF battery system, the electrolytic solution can be efficiently heated and the electrolytic solution having reached a predetermined temperature can be supplied to the battery cell. By bypassing the battery cells, the electrolyte warmed by the drive of the pump is quickly returned to the tank. Therefore, the temperature of the electrolytic solution is unlikely to drop in the middle of the distribution channel. That is, the warmed electrolytic solution is returned to the tank and mixed with the electrolytic solution in the tank with almost no decrease in temperature. Therefore, the operation method of the RF battery system can efficiently heat the electrolytic solution. Further, in the operation method of the RF battery system, by bypassing the battery cell, it is possible to suppress the supply of the electrolytic solution before reaching a predetermined temperature to the battery cell. In other words, in the operation method of the RF battery system, the electrolytic solution that has reached a predetermined temperature is circulated to the battery cell. Therefore, the operation method of the RF battery system can promote the charge / discharge reaction and improve the battery efficiency, so that the battery performance can be improved.

<< Details of Embodiments of the present disclosure >>
Details of the embodiments of the present disclosure will be described below. The same reference numerals in the figures indicate the same names.

<< Embodiment 1 >>
[RF battery system]
The RF battery system 1 of the first embodiment will be described with reference to FIG. The RF battery system 1 of this embodiment includes a tank 3, a battery cell 10, and a distribution mechanism 5. The tank 3 stores the electrolytic solution 4. The distribution mechanism 5 circulates the electrolytic solution 4 between the tank 3 and the battery cell 10. The distribution mechanism 5 has an outward route 51, a return route 52, and a pump 54. The outbound route 51 supplies the electrolytic solution 4 in the tank 3 to the battery cell 10. The return path 52 discharges the electrolytic solution 4 from the battery cell 10 to the tank 3. The pump 54 pumps the electrolytic solution 4 in the tank 3. One of the features of the RF battery system 1 is that the distribution mechanism 5 has a bypass path 53 and a specific switching structure 55. The bypass path 53 connects the outward path 51 with the return path 52 or the tank 3 to bypass the battery cell 10. The switching structure 55 switches between the distribution of the electrolytic solution 4 to the battery cell 10 and the distribution to the bypass path 53. The following description will be given in the order of an outline of the RF battery system 1, details of each configuration of the RF battery system 1, and an operation method of the RF battery system.

[Overview of RF battery system]
The RF battery system 1 is typically connected between the power generation unit 110 and the load 130 via the AC / DC converter 100 and the substation equipment 120 (FIG. 1). The RF battery system 1 charges and stores the electric power generated by the power generation unit 110, discharges the stored electric power, and supplies the stored electric power to the load 130. Examples of the power generation unit 110 include a solar power generation device, a wind power generation device, and other general power plants. Examples of the load 130 include electric power consumers. The RF battery system 1 uses the electrolytic solution 4 as the positive electrode electrolytic solution and the negative electrode electrolytic solution. The electrolytic solution 4 contains a metal ion whose valence changes due to redox as an active material. Charging / discharging of the RF battery system 1 is performed by utilizing the difference between the redox potential of the ions contained in the positive electrode electrolytic solution and the redox potential of the ions contained in the negative electrode electrolytic solution. Examples of the metal ion include vanadium ion, titanium ion, manganese ion and the like. Examples of the solvent of the electrolytic solution 4 include an aqueous solution containing one or more acids or acid salts selected from the group consisting of sulfuric acid, phosphoric acid, nitric acid, and hydrochloric acid. The RF battery system 1 is used, for example, for load leveling applications, applications such as instantaneous low compensation and emergency power sources, and applications for smoothing the output of natural energy such as solar power generation and wind power generation, which are being introduced in large quantities. It will be used.

[tank]
The tank 3 stores the electrolytic solution 4 distributed in the battery cell 10 (FIG. 1). FIG. 1 shows only the tank 3 for the positive electrode. Further, in FIG. 1, the flow direction of the electrolytic solution 4 is indicated by a white arrow. These points are the same in FIGS. 2 to 5 described later. In FIG. 1, the tank for the negative electrode is omitted. The configuration of the tank for the negative electrode can be the same as that of the tank 3 for the positive electrode. The size of the tank 3 can be appropriately selected according to the battery capacity.

[Battery cell]
The battery cell 10 is separated into a positive electrode cell and a negative electrode cell by a diaphragm that allows hydrogen ions to permeate. The diaphragm, the positive electrode cell, and the negative electrode cell are not shown. The positive electrode cell has a built-in positive electrode. The positive electrode electrolytic solution is circulated from the tank 3 described above to the positive electrode cell by the distribution mechanism 5 described later. The negative electrode cell has a built-in negative electrode. The negative electrode electrolytic solution is circulated from the negative electrode tank to the negative electrode cell by the distribution mechanism 5. In this embodiment, the battery cell 10 is installed at a position higher than the highest position of the tank 3, the outward path 51, and the bypass path 53. Therefore, when the operation is shifted from the operation in which charging / discharging is performed to the standby state in which charging / discharging is not performed, the electrolytic solution 4 accumulated in the battery cell 10 is passed through the outward path 51 by utilizing the height difference between the battery cell 10 and the tank 3. Easy to return to tank 3. A known battery cell 10 can be used. The battery cell 10 is usually formed inside a structure called a cell stack 20.

[Cell stack]
The cell stack 20 is composed of a laminate called a sub-stack, two end plates that sandwich the laminate from both sides, and a tightening mechanism that tightens both end plates. The illustration of the laminate, the end plate, and the tightening mechanism is omitted. The number of sub-stacks may be singular or plural. The sub-stack has a laminate in which a plurality of cell frames, positive electrodes, diaphragms, and negative electrodes are laminated in this order, and supply / discharge plates arranged at both ends of the laminate. The cell frame has a bipolar plate and a frame body surrounding the outer peripheral edge of the bipolar plate. One battery cell 10 is formed between the bipolar plates of adjacent cell frames. The positive electrode and the negative electrode of the adjacent battery cells 10 are arranged on the front and back sides of the bipolar plate. That is, a positive electrode cell and a negative electrode cell of adjacent battery cells 10 are formed on the front and back sides of the bipolar plate. The frame of the cell frame includes a liquid supply manifold and a liquid supply slit for supplying the electrolytic solution 4 inside the battery cell 10, a drainage manifold for discharging the electrolytic solution 4 to the outside of the battery cell 10, and a liquid drainage slit. Have. An annular seal member such as an O-ring or a flat packing is arranged in an annular seal groove between the frames to suppress leakage of the electrolytic solution 4 from the battery cell 10. As the cell stack 20, a known cell stack 20 can be used.

[Distribution mechanism]
The distribution mechanism 5 circulates the electrolytic solution 4 between the tank 3 and the battery cell 10. The distribution mechanism 5 has an outward path 51, a return path 52, a bypass path 53, a pump 54, and a switching structure 55. FIG. 1 shows only the distribution mechanism 5 for the positive electrode. The illustration of the distribution mechanism for the negative electrode is omitted in FIG. The configuration of the distribution mechanism for the negative electrode can be the same as that of the distribution mechanism 5 for the positive electrode.

(Outward / Inbound)
The outbound route 51 supplies the electrolytic solution 4 in the tank 3 from the tank 3 to the battery cell 10. The upstream of the outward path 51 opens into the electrolytic solution 4 in the tank 3. The downstream of the outbound route 51 is connected to the cell stack 20. One end of a bypass path 53, which will be described later, is connected in the middle of the outward path 51. The outbound route 51 has a first flow path 511 on the upstream side of the connection point 510 between the outbound route 51 and the bypass path 53, and a second flow path 512 on the downstream side of the connection point 510. The first flow path 511 and the second flow path 512 communicate with each other.

The return path 52 discharges the electrolytic solution 4 from the battery cell 10 to the tank 3. The upstream of the return path 52 is connected to the cell stack 20. In this example, the downstream side of the return path 52 opens to the gas phase in the tank 3. The other end of the bypass path 53, which will be described later, is connected in the middle of the return path 52.

The outward route 51 and the return route 52 are pulled out above the tank 3. That is, all the portions exposed from the tank 3 on the outward route 51 and the return route 52 are located above the tank 3.

The outward route 51 and the return route 52 can be composed of, for example, a resin pipe or a cladding pipe. Examples of the material of the resin tube include polyvinyl chloride. The cladding tube includes a metal tubular member and a coating layer that covers the contact portion of the tubular member with the electrolytic solution 4. As the tubular member, for example, a stainless steel pipe can be used. Examples of the material of the coating layer include resin and rubber which do not react with the electrolytic solution 4 and have excellent resistance to the electrolytic solution 4. Examples of the resin include polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE), polytetrafluoroethylene (PTFE) and the like.

The cross-sectional areas of the internal spaces of the outward path 51 and the return path 52 are the same as each other. The cross-sectional area of the internal space of the outward path 51 refers to the area of the region surrounded by the inner peripheral surface of the pipe in the cross section orthogonal to the longitudinal direction of the outward path 51. Similarly, the cross-sectional area of the internal space of the return path 52 refers to the area of the region surrounded by the inner peripheral surface of the pipe in the cross section orthogonal to the longitudinal direction of the return path 52. The longitudinal direction of the outward path 51 and the longitudinal direction of the return path 52 refer to the flow direction of the electrolytic solution 4.

(Bypass)
The bypass path 53 bypasses the battery cell 10 by connecting the middle of the outward path 51 and the middle of the return path 52, or the middle of the outward path 51 and the tank 3. In this embodiment, the bypass road 53 connects the middle of the outward road 51 and the middle of the return road 52. The mode of connecting the middle of the outward route 51 and the tank 3 will be described in the fifth embodiment. In the bypass path 53, the electrolytic solution 4 flowing through the outward path 51 is not circulated to the battery cell 10, but is circulated from the connection portion 510 in the middle of the outward path 51 to the middle of the return path 52. That is, the electrolytic solution 4 flowing through the bypass path 53 is discharged to the tank 3 without passing through the battery cell 10. The bypass path 53 is arranged above the tank 3 over the entire length in the longitudinal direction thereof. The bypass path 53 can be composed of the same resin pipe or cladding tube as the outward path 51.

The cross-sectional area of the internal space of the bypass path 53 is the same as the cross-sectional area of the internal space of the outward path 51 in this embodiment. The cross-sectional area of the internal space of the bypass path 53 may be larger than the cross-sectional area of the internal space of the outward path 51, as will be described in the third embodiment described later. The cross-sectional area of the internal space of the bypass path 53 refers to the area of the region surrounded by the inner peripheral surface of the pipe in the cross section orthogonal to the longitudinal direction of the bypass path 53, similarly to the outward path 51 and the like. The longitudinal direction of the bypass path 53 refers to the flow direction of the electrolytic solution 4.

(pump)
The pump 54 pumps the electrolytic solution 4 in the tank 3. The location where the pump 54 is installed is in the middle of the first flow path 511 of the outward path 51 in this example. That is, the installation location of the pump 54 is upstream from the connection location 510. The type of the pump 54 can be appropriately selected, and examples thereof include a self-priming pump. The pump 54 is controlled by the pump control unit 651 of the control mechanism 6 described later.

(Switching structure)
The switching structure 55 switches between the distribution of the electrolytic solution 4 to the battery cell 10 and the distribution to the bypass path 53. The switching structure 55 may be composed of a plurality of members, for example, as in the present embodiment and the second, third, and fifth embodiments described later. Further, the switching structure 55 may be composed of a single member, for example, as in the fourth embodiment described later. In this embodiment in which the switching structure 55 is composed of a plurality of members, the switching structure 55 is composed of at least a part of the first valve 551 and the second flow path 512 of the outward path 51. Further, in the second embodiment, the switching structure 55 is composed of a first valve 551 and a second valve 552 (FIG. 2). Further, in the third embodiment, the switching structure 55 is composed of a first valve 551 and at least a part of the bypass path 53 (FIG. 3). Then, in the fifth embodiment, the switching structure 55 is the same as the switching structure 55 of the first embodiment. On the other hand, in the fourth embodiment in which the switching structure 55 is composed of a single member, the switching structure 55 is composed of a switching valve 553 (FIG. 4).

<First valve>
The first valve 551 opens and closes the bypass path 53. When the bypass path 53 is opened by the first valve 551, the electrolytic solution 4 can be circulated to the bypass path 53. When the bypass path 53 is closed by the first valve 551, the flow of the electrolytic solution 4 to the bypass path 53 is prevented. The closure of the bypass path 53 by the first valve 551 enables the flow of the electrolytic solution 4 from the second flow path 512 of the outward path 51 to the battery cell 10. The location where the first valve 551 is installed is in the middle of the bypass path 53. The type of the first valve 551 can be appropriately selected. Examples of the type of the first valve 551 include a gate valve, a glove valve, a ball valve, a butterfly valve, a diaphragm valve and the like. The first valve 551 is controlled by the valve control unit 652 of the control mechanism 6 described later.

<Second flow path>
The second flow path 512 has a high position portion 513. The high position portion 513 is a portion arranged at a position higher than the highest position of the bypass path 53. That is, at least a part of the second flow path 512 is arranged at a position higher than the highest position of the bypass path 53. Therefore, the lift of the second flow path 512 is larger than that of the bypass path 53. Therefore, when the bypass path 53 is opened by the first valve 551, the flow of the electrolytic solution 4 to the second flow path 512 is restricted by the portion arranged at a position higher than the highest position of the bypass path 53. This regulation of the distribution of the electrolytic solution 4 enables the distribution of the electrolytic solution 4 to the bypass path 53. The highest position of the second flow path 512 and the bypass path 53 is the highest position of the central axis of each pipeline.

The second flow path 512 may further have a low position portion or a reference position portion 514 as long as it has a high position portion 513. The low position portion is a portion arranged at a position lower than the highest position of the bypass path 53. The reference position portion 514 is a portion arranged at the same position as the highest position of the bypass path 53. That is, a part of the second flow path 512 is arranged at a position higher than the highest position of the bypass path 53, and the other part of the second flow path 512 is lower than the highest position of the bypass path 53 or the same position as the highest position. It may be arranged in. Of course, the second flow path 512 may be composed of only a portion arranged at a position higher than the highest position of the bypass path 53. That is, all of the second flow path 512 may be arranged at a position higher than the highest position of the bypass path 53.

The second flow path 512 of the present embodiment has a high position portion 513 and a reference position portion 514. The high position portion 513 is provided on the battery cell 10 side in the second flow path 512. The reference position portion 514 is provided on the side of the first flow path 511 in the second flow path 512. Since the high position portion 513 is provided on the battery cell 10 side and the reference position portion 514 is provided on the first flow path 511 side, when the operation is shifted from the operation time to the standby state, the operation is shifted via the second flow path 512. It is easy to remove the electrolytic solution 4 accumulated in the battery cell 10.

The switching structure 55 of the RF battery system 1 of the present embodiment further preferably has a second valve 552 (FIG. 2) described in the second embodiment described later. The reason is that when the electrolytic solution 4 is circulated in the bypass path 53, the flow of the electrolytic solution 4 to the battery cell 10 can be reliably prevented.

[Control mechanism]
The control mechanism 6 controls the distribution of the electrolytic solution 4 to the battery cell 10 and the distribution of the electrolytic solution 4 to the bypass path 53 based on the temperature of the electrolytic solution 4. The control mechanism 6 of this embodiment includes a liquid temperature detecting unit 61 and an operation control unit 65.

(Liquid temperature detector)
The liquid temperature detection unit 61 detects the temperature of the electrolytic solution 4 in the tank 3. As the liquid temperature detection unit 61, for example, a liquid temperature sensor capable of directly measuring the liquid temperature can be used.

(Operation control unit)
The operation control unit 65 controls switching between the distribution of the electrolytic solution 4 to the battery cell 10 and the distribution of the electrolytic solution 4 to the bypass path 53 by the switching structure 55. In this embodiment, the operation control unit 65 includes a pump control unit 651 and a valve control unit 652. As the operation control unit 65, for example, a computer including a processor can be used.

<Pump control unit>
The pump control unit 651 controls the operation of the pump 54 based on the detection result of the liquid temperature detection unit 61. The pump control unit 651 drives and stops the pump 54. Further, the pump control unit 651 adjusts the output of the pump 54.

<Valve control unit>
The valve control unit 652 controls the operation of the first valve 551 based on the detection result of the liquid temperature detection unit 61. That is, the valve control unit 652 opens and closes the first valve 551.

[How to operate the RF battery system]
The operation method of the RF battery system according to this embodiment is as follows. The liquid temperature detection unit 61 detects the temperature of the electrolytic solution 4 in the tank 3. When the temperature of the electrolytic solution 4 in the detected tank 3 is lower than the predetermined temperature, the valve control unit 652 opens the first valve 551. By this control, the bypass path 53 is opened. The predetermined temperature of the electrolytic solution 4 is, for example, 30 ° C. or higher and 45 ° C. or lower. The pump control unit 651 operates the pump 54 at a predetermined output. The output of the pump 54 during the heating operation in which the electrolytic solution 4 is circulated in the bypass path 53 to warm it can be appropriately selected. If the output of the pump 54 during the heating operation is increased, the temperature of the electrolytic solution 4 tends to rise quickly. If the output of the pump 54 during the heating operation is reduced, the power consumption when warming the temperature of the electrolytic solution 4 is reduced. The output of the pump 54 during the heating operation can be made smaller than the output of the pump 54 during the normal operation in which the electrolytic solution 4 is circulated to the battery cell 10. This is because there is no member that serves as a distribution resistor for the electrolytic solution 4 like the battery cell 10. The output of the pump 54 during the heating operation can be, for example, 1/2 times or less the output of the pump 54 during the normal operation, and further can be 1/3 times or less. The output of the pump 54 during the heating operation is, for example, 1/5 or more of the output of the pump 54 during the normal operation from the viewpoint of heating the electrolytic solution 4. The operation control unit 65 may turn off the AC / DC converter 100 before controlling the valve control unit 652 and the pump control unit 651.

On the other hand, when the temperature of the electrolytic solution 4 in the detected tank 3 is equal to or higher than a predetermined temperature, the valve control unit 652 closes the first valve 551. This control closes the bypass path 53. The pump control unit 651 operates the pump 54 at a predetermined output. The output of the pump 54 during normal operation is usually larger than the output of the pump 54 during warming operation. This is because it is necessary to distribute the electrolytic solution 4 through a member that serves as a distribution resistor for the electrolytic solution 4, such as the battery cell 10. At the time of the operation transition from the heating operation to the normal operation, the control of the pump 54 by the pump control unit 651 may be performed after the pump 54 is temporarily stopped, or may be performed without temporarily stopping the pump 54. May be good. The operation control unit 65 may turn on the AC / DC converter 100 before controlling the valve control unit 652 and the pump control unit 651.

Regardless of whether the temperature of the electrolytic solution 4 in the detected tank 3 is lower than or higher than the predetermined temperature, the control order of the valve control unit 652 and the pump control unit 651 may be simultaneous or different. When the control order is different, either of them may be performed first, but it is preferable that the pump 54 is stopped when the first valve 551 is opened and closed. The reason is that the first valve 551 can be easily opened and closed.

[Action effect]
The RF battery system 1 of the present embodiment has a high position portion 513 in which the outward path 51 is higher than the highest position of the bypass path 53. Therefore, when the bypass path 53 is opened by the first valve 551, the electrolytic solution 4 becomes difficult to flow to the second flow path 512 of the outward path 51 and easily flows to the bypass path 53. The length of the distribution path through which the electrolytic solution 4 passes through the bypass path 53 is shorter than the length of the distribution path through which the electrolytic solution 4 passes through the battery cell 10. Therefore, the electrolytic solution 4 warmed by the drive of the pump 54 can be quickly returned to the tank 3 via the bypass path 53. Therefore, the temperature of the electrolytic solution 4 is unlikely to drop in the middle of the distribution channel. That is, the warmed electrolytic solution 4 is returned to the tank 3 and mixed with the electrolytic solution 4 in the tank 3 with almost no decrease in temperature. Therefore, the RF battery system 1 of the present embodiment can efficiently heat the electrolytic solution 4 in the tank 3.

Further, the RF battery system 1 of the present embodiment can return the electrolytic solution 4 warmed by the drive of the pump 54 to the tank 3 without supplying the battery cell 10 via the bypass path 53. Therefore, it is possible to prevent the electrolytic solution 4 from being supplied to the battery cell 10 before reaching a predetermined temperature. In other words, in the RF battery system 1 of the present embodiment, the electrolytic solution 4 that has reached a predetermined temperature is circulated to the battery cell 10. Therefore, the RF battery system 1 of the present embodiment can promote the charge / discharge reaction and improve the battery efficiency, so that the battery performance can be improved.

<< Embodiment 2 >>
[RF battery system]
The RF battery system 1 according to the second embodiment will be described with reference to FIG. The RF battery system 1 of the present embodiment is different from the first embodiment in that the switching structure 55 is mainly composed of the first valve 551 and the second valve 552. The first valve 551 is the same as that of the first embodiment. The following description will focus on the differences from the first embodiment. The description of the configuration similar to that of the first embodiment will be omitted. In FIG. 2, for convenience of explanation, the AC / DC converter 100, the power generation unit 110, the substation equipment 120, and the load 130 are omitted (see FIG. 1 for all). These points are the same in the third to fifth embodiments (FIGS. 3 to 5) described later.

[Distribution mechanism]
(Outward / Bypass)
The highest positions of the outward path 51 and the bypass path 53 are the same as each other in this embodiment. The highest position of the outward path 51 and the bypass path 53 is the highest position of the central axis of each pipeline. The highest position of the second flow path 512 and the bypass path 53 is the same height over the entire length.

(Switching structure)
<Second valve>
The second valve 552 opens and closes the second flow path 512. When the second flow path 512 is opened by the second valve 552, the electrolytic solution 4 can be circulated to the battery cell 10. When the second flow path 512 is closed by the second valve 552, the flow of the electrolytic solution 4 to the second flow path 512 is prevented. The closure of the second flow path 512 by the second valve 552 and the opening of the bypass path 53 by the first valve 551 enable the flow of the electrolytic solution 4 to the bypass path 53. The installation location of the second valve 552 is in the middle of the second flow path 512. The type of the second valve 552 can be the same as the type of the first valve 551. The second valve 552 is controlled by the valve control unit 652.

[Control mechanism]
(Operation control unit)
<Valve control unit>
The valve control unit 652 controls both the operation of the first valve 551 and the operation of the second valve 552 based on the detection result of the liquid temperature detection unit 61. That is, the valve control unit 652 opens and closes the first valve 551 and the second valve 552.

[How to operate the RF battery system]
When the temperature of the electrolytic solution 4 in the tank 3 detected by the liquid temperature detecting unit 61 is lower than a predetermined temperature, the valve control unit 652 opens the first valve 551. Further, the valve control unit 652 closes the second valve 552. By this control, the bypass path 53 is opened. In addition, the second flow path 512 is closed. The pump control unit 651 is the same as when the temperature of the electrolytic solution 4 in the first embodiment is lower than a predetermined temperature. Similar to the first embodiment, the AC / DC converter 100 may be turned off by the operation control unit 65 before being controlled by the valve control unit 652 or the pump control unit 651.

On the other hand, when the temperature of the electrolytic solution 4 in the detected tank 3 is equal to or higher than a predetermined temperature, the valve control unit 652 closes the first valve 551. Further, the valve control unit 652 opens the second valve 552. By this control, the bypass path 53 is closed. In addition, the second flow path 512 is opened. The pump control unit 651 is the same as when the temperature of the electrolytic solution 4 in the first embodiment is equal to or higher than a predetermined temperature. Similar to the first embodiment, the AC / DC converter 100 may be turned on by the operation control unit 65 before being controlled by the valve control unit 652 or the pump control unit 651.

Regardless of whether the temperature of the electrolytic solution 4 in the detected tank 3 is lower than or higher than the predetermined temperature, the opening / closing order of the first valve 551 and the second valve 552 by the valve control unit 652 may be simultaneous or different. You may be. If the opening / closing order is different, either may be performed first.

[Action effect]
Similar to the first embodiment, the RF battery system 1 of the present embodiment can efficiently heat the electrolytic solution 4 and supply the electrolytic solution 4 that has reached a predetermined temperature to the battery cell 10. In particular, in the RF battery system 1 of the present embodiment, since the switching structure 55 has the second valve 552, it is possible to reliably prevent the electrolytic solution 4 from being supplied to the battery cell 10 during the heating operation.

<< Embodiment 3 >>
[RF battery system]
The RF battery system 1 according to the third embodiment will be described with reference to FIG. The RF battery system 1 of the present embodiment is different from the first embodiment in that the switching structure 55 is composed of the first valve 551 and at least a part of the bypass path 53. The operation method of the first valve 551 and the RF battery system is the same as that of the first embodiment.

[Distribution mechanism]
(Outward)
The highest position of the outward path 51 is the same as the highest position of the bypass path 53 in this embodiment. The highest position of the outward path 51 and the bypass path 53 is the highest position of the central axis of each pipeline. The highest positions of the second flow path 512 and the bypass path 53 are the same height over the entire length.

(Switching structure)
<Bypass Road>
The bypass path 53 has a large cross-sectional area 531. The large cross-sectional area portion 531 is a portion in which the cross-sectional area of the internal space is larger than the cross-sectional area of the internal space of the second flow path 512. The bypass path 53 may have the same cross-sectional area as long as it does not have a small cross-sectional area. The small cross-sectional area is a portion where the cross-sectional area of the internal space is smaller than the cross-sectional area of the internal space of the second flow path 512. In the same cross-sectional area, the cross-sectional area of the internal space is the same as the cross-sectional area of the internal space of the second flow path 512. Since the bypass path 53 has a large cross-sectional area portion 531 and does not have a small cross-sectional area portion, the electrolytic solution 4 can be easily circulated through the bypass path 53 when the bypass path 53 is opened by the first valve 551.

The cross-sectional area of the internal space of the large cross-sectional area 531 is preferably, for example, twice or more, more preferably three times or more, and particularly preferably four times or more the cross-sectional area of the internal space of the second flow path 512. The cross-sectional area of the internal space of the large cross-sectional area 531 is, for example, 10 times or less the cross-sectional area of the internal space of the second flow path 512. The larger the ratio of the large cross-sectional area portion 531 to the total length of the bypass path 53, the easier it is for the electrolytic solution 4 to flow through the bypass path 53. If the ratio of the large cross-sectional area 531 to the total length of the bypass path 53 is 100%, that is, if the bypass path 53 is composed of the large cross-sectional area 531 over the entire length, the electrolytic solution 4 is particularly easy to flow through the bypass path 53. ..

The switching structure 55 of the RF battery system 1 of the present embodiment further preferably has a second valve 552 (FIG. 2) described in the second embodiment. The reason is that when the electrolytic solution 4 is circulated in the bypass path 53, the flow of the electrolytic solution 4 to the battery cell 10 can be reliably prevented.

[Action effect]
Similar to the first embodiment, the RF battery system 1 of the present embodiment can efficiently heat the electrolytic solution 4 and supply the electrolytic solution 4 that has reached a predetermined temperature to the battery cell 10.

<< Embodiment 4 >>
[RF battery system]
The RF battery system 1 according to the fourth embodiment will be described with reference to FIG. The RF battery system 1 of the present embodiment is different from the first embodiment in that the switching structure 55 is mainly composed of the switching valve 553.

(Switching structure)
<Switching valve>
The switching valve 553 opens and closes one of the second flow path 512 and the bypass path 53 of the outward path 51. That is, the switching valve 553 switches between the flow of the electrolytic solution 4 from the first flow path 511 of the outward path 51 to the second flow path 512 and the flow of the electrolytic solution 4 from the first flow path 511 of the outward path 51 to the bypass path 53. .. The switching valve 553 is installed at the connection point 510 between the outward path 51 and the bypass path 53. Examples of the type of switching valve 553 include a three-way valve.

(Operation control unit)
<Valve control unit>
The valve control unit 652 operates the switching valve 553 based on the detection result of the liquid amount detection unit. The valve control unit 652 operates the switching valve 553 so as to open one of the second flow path 512 and the bypass path 53 of the outward path 51 and close the other.

[How to operate the RF battery system]
When the temperature of the electrolytic solution 4 in the tank 3 detected by the liquid temperature detecting unit 61 is lower than the predetermined temperature, the valve control unit 652 switches so as to open the bypass path 53 and close the second flow path 512. Operate valve 553. The pump control unit 651 is the same as when the temperature of the electrolytic solution 4 in the first embodiment is lower than a predetermined temperature. Similar to the first embodiment, the AC / DC converter 100 may be turned off by the operation control unit 65 before being controlled by the valve control unit 652 or the pump control unit 651.

On the other hand, when the temperature of the electrolytic solution 4 in the tank 3 is equal to or higher than a predetermined temperature, the valve control unit 652 operates the switching valve 553 so as to open the second flow path 512 and close the bypass path 53. The pump control unit 651 is the same as when the temperature of the electrolytic solution 4 in the first embodiment is equal to or higher than a predetermined temperature. Similar to the first embodiment, the AC / DC converter 100 may be turned on by the operation control unit 65 before being controlled by the valve control unit 652 or the pump control unit 651.

[Action effect]
Similar to the first embodiment, the RF battery system 1 of the present embodiment can efficiently heat the electrolytic solution 4 and supply the electrolytic solution 4 that has reached a predetermined temperature to the battery cell 10. In particular, in the RF battery system 1 of the present embodiment, since the switching structure 55 has the switching valve 553, it is possible to reliably prevent the electrolytic solution 4 from being supplied to the battery cell 10 during the heating operation.

<< Embodiment 5 >>
[RF battery system]
The RF battery system 1 according to the fifth embodiment will be described with reference to FIG. The RF battery system 1 of the present embodiment is different from the first embodiment in that the bypass path 53 is connected to the middle of the outward path 51 and the tank 3 without being connected to the return path 52. The operation method of the RF battery system is the same as that of the first embodiment.

(Bypass)
In the bypass path 53, the electrolytic solution 4 flowing through the outward path 51 is not circulated to the battery cell 10, but is circulated from the connection portion 510 in the middle of the outward path 51 to the tank 3. That is, the electrolytic solution 4 flowing through the bypass path 53 does not pass through the battery cell 10 and the return path 52, and is discharged to the tank 3. The upstream of the bypass path 53 is arranged above the tank 3. The downstream side of the bypass path 53 opens to the gas phase in the tank 3.

[Action effect]
Similar to the first embodiment, the RF battery system 1 of the present embodiment can efficiently heat the electrolytic solution 4 and supply the electrolytic solution 4 that has reached a predetermined temperature to the battery cell 10. In particular, in the RF battery system 1 of the present embodiment, it is easy to shorten the distribution path through which the electrolytic solution 4 flows through the bypass path 53 and returns to the tank 3 as compared with the case where the downstream of the bypass path 53 is connected in the middle of the return path 52. .. Therefore, in the RF battery system 1 of the present embodiment, the temperature of the electrolytic solution 4 is less likely to drop in the middle of the distribution path.

<< Test example >>
In the test example, the RF battery system 1 according to the first embodiment described with reference to FIG. 1 is used, and the electrolytic solution 4 is not distributed to the battery cell 10 but is distributed to the bypass path 53, and the electrolytic solution 4 in the tank 3 is distributed. The temperature of the was measured. That is, in the test example, the first valve 551 was opened to open the bypass path 53, and the electrolytic solution 4 was pumped by the pump 54. The electrolytic solution 4 was circulated in the order of the tank 3, the first flow path 511 of the outward path 51, the bypass path 53, the return path 52, and the tank 3. The power of the pump 54 was 4.1 kW.

The temperature of the electrolytic solution 4 was measured over 24 hours from n o'clock to n + 24:00 while the electrolytic solution 4 continued to flow. The result is shown in FIG. The graph of FIG. 6 shows the temperature change of the electrolytic solution 4 and the change of the outside air temperature with the passage of time. The temperature change of the electrolytic solution 4 is shown by a solid line. Changes in outside air temperature are indicated by broken lines. The horizontal axis of FIG. 6 is Hour. The vertical axis of FIG. 6 is the temperature (° C.).

As shown in FIG. 6, the outside air temperature repeatedly increased and decreased for 24 hours. The difference between the minimum temperature and the maximum temperature of the outside air temperature was about 10 ° C. Despite the large change in the outside air temperature, the temperature of the electrolytic solution 4 could be kept within the range of 30.3 ° C. or higher and 31.2 ° C. or lower for 24 hours. The average outside air temperature was 9.5 ° C. The average temperature of the electrolytic solution 4 was 30.8 ° C. The temperature difference between the average temperature of the electrolytic solution 4 and the average temperature of the outside air was 21.3 ° C. The power consumption per temperature difference obtained from the power of the pump 54 / the temperature difference was about 0.19 kW / ° C.

For comparison, in the RF battery system 1 according to the first embodiment, the bottom of the tank 3 was heated from the outside with a heater without circulating the electrolytic solution 4, and the temperature of the electrolytic solution 4 in the tank 3 was measured. The power of the heater was 4.9 kW.

The temperature of the electrolytic solution 4 was measured over 12 hours from n o'clock to n + 12 o'clock by continuously warming the bottom of the tank 3 with a heater. The result is shown in FIG. Similar to FIG. 6, the graph of FIG. 7 shows the temperature change of the electrolytic solution 4 and the change of the outside air temperature with the passage of time. The temperature change of the electrolytic solution 4 is shown by a solid line. Changes in outside air temperature are indicated by broken lines. The horizontal axis of FIG. 7 is Hour. The vertical axis of FIG. 7 is the temperature (° C.).

As shown in FIG. 7, the outside air temperature hardly changed in the range of 12 ° C. to 15 ° C. over 12 hours. Although the outside air temperature hardly changed as described above, the temperature of the electrolytic solution 4 did not reach 30 ° C. or higher for 12 hours, and was within the range of 26.4 ° C. or higher and 27.0 ° C. or lower. The average outside air temperature was 13.1 ° C. The average temperature of the electrolytic solution 4 was 26.7 ° C. The temperature difference between the average temperature of the electrolytic solution 4 and the average temperature of the outside air was 13.6 ° C. The power consumption per temperature difference obtained from the power of the heater / the temperature difference was about 0.36 kW / ° C.

The power consumption when the electrolytic solution 4 is circulated in the bypass path 53 is about 47% lower than the power consumption when the electrolytic solution 4 is heated by a heater. Therefore, it was found that by circulating the electrolytic solution 4 through the bypass path 53, the electrolytic solution 4 can be heated with energy saving as compared with the case where the electrolytic solution 4 is heated by the heater. That is, it was found that circulating the electrolytic solution 4 through the bypass path 53 is more efficient in warming the electrolytic solution 4 than in the case of heating the electrolytic solution 4 with a heater.

The present invention is not limited to these examples, and is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims. For example, the switching structure may be composed of two or more selected from the group consisting of a high position portion of the second flow path, a large cross-sectional area portion of the bypass path, and the first valve, and the first valve. Further, the switching structure may be composed of the first valve and the second flow path of the outward path longer than the total length of the bypass path.

1 RF battery system 10 Battery cell 20 Cell stack 3 Tank 4 Electrolyte 5 Flow mechanism 51 Outward route 510 Connection point 511 First flow path 512 Second flow path 513 High position part 514 Reference position part 52 Return path 53 Bypass path 531 Large cross-sectional area 54 Pump 55 Switching structure 551 First valve 552 Second valve 553 Switching valve 6 Control mechanism 61 Liquid temperature detector 65 Operation control unit 651 Pump control unit 652 Valve control unit 100 AC / DC converter 110 Power generation unit 120 Substation equipment 130 Load

Claims (7)

A tank for storing electrolyte and
Battery cell and
A distribution mechanism for circulating the electrolytic solution between the tank and the battery cell is provided.
The distribution mechanism
The outbound route for supplying the electrolytic solution in the tank to the battery cell, and
A return path for discharging the electrolytic solution from the battery cell to the tank, and
A redox flow battery system comprising a pump for pumping the electrolyte in the tank.
The distribution mechanism
A bypass path that connects the outward path and the return path, or the outward path and the tank, and bypasses the battery cell.
A switching structure for switching between distribution of the electrolytic solution to the battery cell and distribution to the bypass path is provided.
Redox flow battery system. The switching structure is
The first valve that opens and closes the bypass path,
The redox flow battery system according to claim 1, wherein the redox flow battery system has a portion higher than the highest position of the bypass path downstream of the connection point between the outward path and the bypass path. The switching structure is
The first valve that opens and closes the bypass path,
The redox flow battery system according to claim 1 or 2, further comprising a second valve that opens and closes downstream of the outward path from the connection point between the outward path and the bypass path. The switching structure is
The first valve that opens and closes the bypass path,
The redox flow battery system according to any one of claims 1 to 3, wherein the cross-sectional area of the internal space in the bypass path is larger than the cross-sectional area of the internal space in the outward path. The redox flow battery system according to any one of claims 1 to 4, wherein the switching structure has a switching valve attached to a connection point between the outward path and the bypass path. A liquid temperature detection unit that detects the temperature of the electrolytic solution in the tank, and
The redox flow battery according to any one of claims 1 to 5, further comprising an operation control unit that controls the operation of the pump and the switching operation of the switching structure based on the detection result of the liquid temperature detection unit. system. A method of operating a redox flow battery system that circulates the electrolytic solution between a tank in which the electrolytic solution is stored and a battery cell.
When the temperature of the electrolytic solution in the tank satisfies a predetermined temperature range, the battery cell is bypassed and the electrolytic solution is circulated from the outward path to the return path of the battery cell or from the outward path to the tank.
How to operate the redox flow battery system.

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