JP7240638B2 - REDOX FLOW BATTERY SYSTEM AND METHOD OF OPERATION OF REDOX FLOW BATTERY SYSTEM - Google Patents

Description

The present disclosure relates to redox flow battery systems and methods of operating redox flow battery systems.

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

Japanese Patent Application Laid-Open No. 2002-015762 Japanese Patent Application Laid-Open No. 2003-123808

In the redox flow battery described above, depending on the temperature of the electrolyte in the tank, the electrolyte may be supplied to the battery cells before reaching a predetermined temperature. In that case, the viscosity of the electrolytic solution is high, so the pressure loss increases. As a result, the charge/discharge reaction is suppressed, resulting in a decrease in battery efficiency and a decrease in battery performance.

Therefore, an object of the present disclosure is to provide a redox flow battery system capable of efficiently warming the electrolyte solution and supplying the electrolyte solution that has reached a predetermined temperature to battery cells, and a method of operating the redox flow battery system. be one.

The redox flow battery system according to the present disclosure includes
a tank for storing an electrolytic solution;
a battery cell;
A circulation mechanism for circulating the electrolyte between the tank and the battery cell,
The distribution mechanism is
an outward route for supplying the electrolyte in the tank to the battery cell;
a return path for discharging the electrolyte from the battery cell to the tank;
A redox flow battery system comprising a pump for pumping the electrolytic solution in the tank,
The distribution mechanism is
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 is provided for switching between circulation of the electrolyte solution to the battery cell and circulation to the bypass path.

A method of operating a redox flow battery system according to the present disclosure includes:
A method of operating a redox flow battery system in which the electrolyte is circulated between a tank in which the electrolyte is stored and a battery cell,
When the temperature of the electrolyte in the tank satisfies a predetermined temperature range, the battery cell is bypassed and the electrolyte is circulated from the outward path to the return path of the battery cell, or from the outward path to the tank.

The redox flow battery system according to the present disclosure and the operating method of the redox flow battery system according to the present disclosure can efficiently warm the electrolytic solution and supply the electrolytic solution that has reached a predetermined temperature to the battery cells.

FIG. 1 is a configuration diagram showing an outline of a redox flow battery system according to Embodiment 1. FIG. FIG. 2 is a configuration diagram showing an outline of a redox flow battery system according to Embodiment 2. FIG. FIG. 3 is a configuration diagram showing an outline of a redox flow battery system according to Embodiment 3. FIG. FIG. 4 is a configuration diagram showing an outline of a redox flow battery system according to Embodiment 4. FIG. FIG. 5 is a configuration diagram showing an outline of a redox flow battery system according to Embodiment 5. FIG. 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 through the bypass 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 the test example.

<<Description of Embodiments of the Present Disclosure>>
First, the embodiments of the present disclosure are listed and described.

(1) A redox flow battery system according to one aspect of the present disclosure,
a tank for storing an electrolytic solution;
a battery cell;
A circulation mechanism for circulating the electrolyte between the tank and the battery cell,
The distribution mechanism is
an outward route for supplying the electrolyte in the tank to the battery cell;
a return path for discharging the electrolyte from the battery cell to the tank;
A redox flow battery system comprising a pump for pumping the electrolytic solution in the tank,
The distribution mechanism is
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 is provided for switching between circulation of the electrolyte solution to the battery cell and circulation to the bypass path.

The redox flow battery system can efficiently warm the electrolytic solution and supply the electrolytic solution that has reached a predetermined temperature to the battery cells. 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 efficiently warmed is as follows. In the above RF battery system, the flow mechanism has a bypass channel and a switching structure, so that the flow of the electrolytic solution to the battery cells and the flow of the electrolytic solution to the bypass channel can be switched. That is, the above RF battery system can discharge the electrolytic solution to the tank through the bypass passage without supplying the electrolytic solution to the battery cells. When the pump is driven, the electrolytic solution is rubbed against the rotor of the pump and the inner surface of the bypass, causing a temperature rise. The length of the circulation path through which the electrolyte flows through the bypass is shorter than the length of the circulation path through which the electrolyte flows through the battery cells. Therefore, the electrolytic solution warmed by driving the pump can be quickly returned to the tank via the bypass passage. Therefore, it is difficult for the temperature of the electrolytic solution to drop in the middle of the flow path. That is, the warmed electrolytic solution is returned to the tank and mixed with the electrolytic solution in the tank with little drop in temperature.

The reason why it is possible to supply an electrolytic solution that has reached a predetermined temperature is as follows. As described above, the RF battery system can return the electrolytic solution warmed by driving the pump to the tank through the bypass passage without supplying it to the battery cells. Therefore, it is possible to prevent the electrolytic solution from being supplied to the battery cells before reaching a predetermined temperature. In other words, in the RF battery system, the electrolytic solution that has reached a predetermined temperature is allowed to flow through the battery cells. Therefore, the above RF battery system can promote charge-discharge reactions and improve battery efficiency, thereby improving battery performance.

(2) As one form of the RF battery system,
The switching structure is
a first valve that opens and closes the bypass;
and a portion higher than the highest position of the bypass route on the downstream side of the outward route than the connection point between the outward route and the bypass route.

In the above configuration, opening the bypass passage by the first valve allows the electrolyte to flow through the bypass passage. Since the forward route has a portion higher than the highest position of the bypass route downstream thereof, the lift of the forward route is greater than that of the bypass route. Therefore, when the bypass passage is opened by the first valve, it becomes difficult for the electrolytic solution to flow downstream in the outward passage, and the electrolytic solution can easily flow to the bypass passage. Moreover, the above configuration can supply the electrolytic solution to the battery cell by closing the bypass passage with the first valve.

(3) As one form of the RF battery system,
The switching structure is
a first valve that opens and closes the bypass;
It may include a second valve that opens and closes the downstream of the outward path from the connection point between the outward path and the bypass.

In the above configuration, the first valve opens the bypass passage and the second valve closes the downstream side of the forward passage, thereby allowing the electrolytic solution to flow through the bypass passage. Further, in the above configuration, the electrolyte can be supplied to the battery cell by closing the bypass passage with the first valve and opening the downstream passage with the second valve.

(4) As one form of the RF battery system,
The switching structure is
a first valve that opens and closes the bypass;
and a portion in which 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.

In the above configuration, opening the bypass passage by the first valve allows the electrolyte to flow through the bypass passage. This is because the bypass path has a portion with a larger cross-sectional area of the internal space than the forward path, and thus opening the bypass path by the first valve facilitates the flow of the electrolytic solution into the bypass path. Moreover, the above configuration can supply the electrolytic solution to the battery cell by closing the bypass passage with the first valve.

(5) As one form of the RF battery system,
The switching structure may include a switching valve attached to a connecting portion between the outward route and the bypass route.

In the above configuration, the switching valve opens the bypass passage and closes the downstream side of the forward passage, thereby allowing the electrolytic solution to flow through the bypass passage. In addition, the above configuration can supply the electrolytic solution to the battery cells by closing the bypass passage with the switching valve and opening the downstream passage of the forward passage.

(6) As one form of the RF battery system,
a liquid temperature detection unit that detects the temperature of the electrolyte in the tank;
An operation control unit may be included 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.

In the above configuration, the flow of the electrolyte solution to the battery cells and the flow to the bypass can be switched according to the temperature of the electrolyte solution, so that the electrolyte solution is supplied to the battery cells before it reaches a predetermined temperature. can be suppressed, and the electrolytic solution that has reached a predetermined temperature can be circulated through the battery cells.

(7) A method for operating an RF battery system according to one aspect of the present disclosure includes:
A method of operating a redox flow battery system in which the electrolyte is circulated between a tank in which the electrolyte is stored and a battery cell,
When the temperature of the electrolyte in the tank satisfies a predetermined temperature range, the battery cell is bypassed and the electrolyte is circulated from the outward path to the return path of the battery cell, or from the outward path to the tank.

The operating method of the RF battery system described above can efficiently warm the electrolytic solution and supply the electrolytic solution that has reached a predetermined temperature to the battery cells. By bypassing the battery cells, the electrolyte heated by the pump is quickly returned to the tank. Therefore, the temperature of the electrolytic solution is less likely to drop in the middle of the flow path. That is, the warmed electrolytic solution is returned to the tank and mixed with the electrolytic solution in the tank with little drop in temperature. Thus, the method of operating the RF battery system described above effectively warms the electrolyte. In addition, in the operating method of the RF battery system described above, by bypassing the battery cells, it is possible to suppress the electrolyte from being supplied to the battery cells before reaching a predetermined temperature. In other words, in the method of operating the RF battery system described above, the electrolytic solution that has reached a predetermined temperature is allowed to flow through the battery cells. Therefore, the operating method of the RF battery system described above can promote the charging/discharging reaction and improve the battery efficiency, thereby improving the battery performance.

<<Details of the embodiment of the present disclosure>>
Details of embodiments of the present disclosure are described below. The same reference numerals in the drawings indicate the same names.

<<Embodiment 1>>
[RF battery system]
An RF battery system 1 of Embodiment 1 will be described with reference to FIG. The RF battery system 1 of this embodiment includes a tank 3 , battery cells 10 and a circulation mechanism 5 . Tank 3 stores electrolytic solution 4 . The circulation mechanism 5 circulates the electrolytic solution 4 between the tank 3 and the battery cell 10 . The circulation mechanism 5 has an outward passage 51 , a return passage 52 and a pump 54 . The forward path 51 supplies the electrolytic solution 4 in the tank 3 to the battery cell 10 . A return path 52 discharges the electrolytic solution 4 from the battery cell 10 to the tank 3 . A pump 54 pressure-feeds the electrolytic solution 4 in the tank 3 . One of the features of the RF battery system 1 is that the circulation mechanism 5 has a bypass channel 53 and a specific switching structure 55 . The bypass line 53 connects the outward line 51 and the return line 52 or the tank 3 to bypass the battery cell 10 . The switching structure 55 switches between the flow of the electrolytic solution 4 to the battery cell 10 and the flow of the bypass passage 53 . The following description will be given in 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]
RF battery system 1 is typically connected between power generation section 110 and load 130 via AC/DC converter 100 and substation equipment 120 (FIG. 1). The RF battery system 1 charges and stores the power generated by the power generation unit 110 , discharges the stored power, and supplies the load 130 with the stored power. Examples of the power generation unit 110 include a solar power generation device, a wind power generation device, and other general power plants. An example of the load 130 is an electric power consumer. The RF battery system 1 uses the electrolyte 4 as the positive electrolyte and the negative electrolyte. The electrolytic solution 4 contains, as an active material, metal ions whose valence changes due to oxidation-reduction. Charging and discharging of the RF battery system 1 is performed using the difference between the oxidation-reduction potential of ions contained in the positive electrode electrolyte and the oxidation-reduction potential of ions contained in the negative electrode electrolyte. Examples of metal ions include vanadium ions, titanium ions, and manganese ions. Solvents for the electrolytic solution 4 include, for example, aqueous solutions containing one or more acids or acid salts selected from the group consisting of sulfuric acid, phosphoric acid, nitric acid, and hydrochloric acid. For example, the RF battery system 1 is used for load leveling, momentary voltage drop compensation, emergency power supply, and output smoothing of natural energy such as solar power generation and wind power generation, which are being introduced in large quantities. used.

[tank]
The tank 3 stores the electrolytic solution 4 to be circulated in the battery cell 10 (Fig. 1). FIG. 1 shows only the tank 3 for the positive electrode. In addition, in FIG. 1, the flow direction of the electrolytic solution 4 is indicated by white arrows. These points are the same for FIGS. 2 to 5 described later. FIG. 1 omits the tank for the negative electrode. The configuration of the negative electrode tank can be the same as that of the positive electrode tank 3 . 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 pass through. Illustrations of the diaphragm, the positive electrode cell, and the negative electrode cell are omitted. A positive electrode is built into the positive electrode cell. A positive electrode electrolyte is circulated from the tank 3 described above to the positive electrode cell by a distribution mechanism 5 described later. The negative cell incorporates a negative electrode. A flow mechanism 5 circulates a negative electrode electrolyte from a negative electrode tank to the negative electrode cell. In this embodiment, the battery cell 10 is installed at a position higher than the highest positions of the tank 3 , the outward path 51 and the bypass path 53 . Therefore, when the operation shifts from the operating state 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 uses the height difference between the battery cell 10 and the tank 3 to flow through the forward path 51. It is easy to be returned to tank 3. A well-known battery cell 10 can be used. Battery cells 10 are typically formed inside a structure called a cell stack 20 .

[Cell stack]
The cell stack 20 is composed of a layered body called a substack, two end plates sandwiching the layered body from both sides, and a tightening mechanism that tightens both end plates. Illustrations of the laminate, the end plates, and the tightening mechanism are omitted. The number of substacks may be singular or plural. The sub-stack has a laminate obtained by laminating a plurality of cell frames, positive electrodes, diaphragms, and negative electrodes in this order, and supply/discharge plates arranged at both ends of the laminate. The cell frame has a bipolar plate and a frame surrounding the outer peripheral edge of the bipolar plate. One battery cell 10 is formed between the bipolar plates of adjacent cell frames. A positive electrode and a negative electrode of adjacent battery cells 10 are arranged on the front and back sides with the bipolar plate interposed therebetween. That is, the positive electrode cell and the negative electrode cell of the adjacent battery cells 10 are formed on the front and back sides with the bipolar plates interposed therebetween. The frame of the cell frame includes a liquid supply manifold and liquid supply slits for supplying the electrolyte 4 to the inside of the battery cell 10, and a drain manifold and a drain slit for discharging the electrolyte 4 to the outside of the battery cell 10. 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 . A known cell stack 20 can be used.

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

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

A 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 of return path 52 opens into the gas phase in tank 3 . The return path 52 is connected to the other end of a bypass path 53, which will be described later.

The outward path 51 and the return path 52 are drawn out above the tank 3 . That is, all the portions of the outward path 51 and the return path 52 exposed from the tank 3 are located above the tank 3 .

The outward path 51 and the return path 52 can be configured by, for example, a resin pipe or a coated pipe. Examples of the material of the resin pipe include polyvinyl chloride. The cladding tube includes a tubular member made of metal and a coating layer that covers a portion of the tubular member that contacts with the electrolytic solution 4 . The tubular member can be, for example, a stainless steel tube. Materials for the coating layer include resins and rubbers that do not react with the electrolytic solution 4 and have excellent resistance to the electrolytic solution 4 . Examples of resins include polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE), and polytetrafluoroethylene (PTFE).

The cross-sectional areas of the internal spaces of the outward path 51 and the return path 52 are the same. 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 perpendicular to the longitudinal direction of the outward path 51 . Similarly, the cross-sectional area of the inner 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 perpendicular 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 directions of the electrolytic solution 4 .

(bypass road)
The bypass path 53 connects 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 to bypass the battery cell 10 . In this embodiment, the bypass 53 connects the middle of the outward route 51 and the middle of the homeward route 52 . A mode of connecting the tank 3 to the middle of the forward path 51 will be described in a fifth embodiment. The bypass passage 53 allows the electrolytic solution 4 flowing in the outward passage 51 not to circulate to the battery cell 10 , but to flow from the connection point 510 in the middle of the outward passage 51 to the middle of the inward passage 52 . That is, the electrolyte 4 flowing through the bypass 53 is discharged to the tank 3 without passing through the battery cells 10 . The bypass 53 is arranged above the tank 3 over its entire longitudinal length. The bypass passage 53 can be configured with a resin pipe or a coated pipe similar to the outward passage 51 .

The cross-sectional area of the internal space of the bypass passage 53 is the same as the cross-sectional area of the internal space of the forward passage 51 in this embodiment. In addition, the cross-sectional area of the internal space of the bypass 53 may be larger than the cross-sectional area of the internal space of the outward path 51 as described in Embodiment 3 below. The cross-sectional area of the internal space of the bypass 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 53, as in the outward path 51 and the like. The longitudinal direction of the bypass passage 53 refers to the flow direction of the electrolytic solution 4 .

(pump)
A pump 54 pressure-feeds the electrolytic solution 4 in the tank 3 . The installation position of the pump 54 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 of the connection location 510 . The type of pump 54 can be selected as appropriate, and examples thereof include a self-priming pump. The pump 54 is controlled by a pump control section 651 of the control mechanism 6, which will be described later.

(Switching structure)
The switching structure 55 switches between the flow of the electrolytic solution 4 to the battery cell 10 and the flow of the bypass passage 53 . The switching structure 55 may be composed of a plurality of members, for example, as in the present embodiment or Embodiments 2, 3, and 5 to be described later. Also, the switching structure 55 may be composed of a single member, for example, as in Embodiment 4 to be 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 the first valve 551 and at least a part of the second flow path 512 of the outward path 51 . Moreover, in Embodiment 2, the switching structure 55 is composed of a first valve 551 and a second valve 552 (FIG. 2). Furthermore, in Embodiment 3, the switching structure 55 is composed of the first valve 551 and at least part of the bypass passage 53 (FIG. 3). And 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 Embodiment 4 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 passage 53 . When the bypass passage 53 is opened by the first valve 551 , the electrolytic solution 4 can flow through the bypass passage 53 . When the bypass passage 53 is closed by the first valve 551 , the electrolytic solution 4 is prevented from flowing to the bypass passage 53 . Closure of the bypass channel 53 by the first valve 551 allows the electrolyte solution 4 to flow from the second channel 512 of the outward channel 51 to the battery cell 10 . The installation location of the first valve 551 is in the middle of the bypass passage 53 . The type of the first valve 551 can be selected as appropriate. Types of the first valve 551 include, for example, gate valves, globe valves, ball valves, butterfly valves, diaphragm valves, and the like. The first valve 551 is controlled by a valve control section 652 of the control mechanism 6, which will be described later.

<Second flow path>
The second channel 512 has an elevated portion 513 . The high position portion 513 is a portion arranged at a position higher than the highest position of the bypass passage 53 . That is, at least part of the second flow path 512 is arranged at a position higher than the highest position of the bypass 53 . Therefore, the lift of the second channel 512 is greater than that of the bypass channel 53 . Therefore, when the first valve 551 opens the bypass 53 , the portion of the bypass 53 that is positioned higher than the highest position restricts the flow of the electrolytic solution 4 to the second flow path 512 . This regulation of circulation of the electrolytic solution 4 enables the electrolytic solution 4 to flow to the bypass passage 53 . The highest position of the second channel 512 and the bypass channel 53 is the highest point of the center axis of each pipe.

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

The second flow path 512 of this 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 of the second flow path 512 . The reference position portion 514 is provided on the first channel 511 side of the second channel 512 . 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. It is easy to drain the electrolytic solution 4 accumulated in the battery cell 10. - 特許庁

In addition, it is preferable that the switching structure 55 of the RF battery system 1 of this embodiment further includes a second valve 552 ( FIG. 2 ), which will be described later in Embodiment 2. The reason for this is that when the electrolytic solution 4 is allowed to flow through the bypass passage 53 , the electrolytic solution 4 can be reliably prevented from flowing to the battery cell 10 .

[Control mechanism]
The control mechanism 6 controls the flow of the electrolytic solution 4 to the battery cell 10 and the flow of the electrolytic solution 4 to the bypass passage 53 based on the temperature of the electrolytic solution 4 . The control mechanism 6 of this embodiment has a liquid temperature detection section 61 and an operation control section 65 .

(liquid temperature detector)
A liquid temperature detector 61 detects the temperature of the electrolytic solution 4 in the tank 3 . For example, a liquid temperature sensor that can directly measure the liquid temperature can be used as the liquid temperature detection unit 61 .

(operation control part)
The operation control unit 65 controls switching between circulation of the electrolytic solution 4 to the battery cell 10 and circulation of the electrolytic solution 4 to the bypass passage 53 by the switching structure 55 . In this embodiment, the operation control section 65 has a pump control section 651 and a valve control section 652 . A computer including a processor, for example, can be used as the operation control unit 65 .

<Pump controller>
The pump control section 651 controls the operation of the pump 54 based on the detection result of the liquid temperature detection section 61 . A pump control unit 651 drives or stops the pump 54 . Also, the pump control unit 651 adjusts the output of the pump 54 .

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

[Method of operating RF battery system]
The operation method of the RF battery system according to this embodiment is as follows. A liquid temperature detector 61 detects the temperature of the electrolyte 4 in the tank 3 . When the detected temperature of the electrolytic solution 4 in the tank 3 is lower than the predetermined temperature, the valve control section 652 opens the first valve 551 . By this control, the bypass 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 section 651 operates the pump 54 with a predetermined output. The output of the pump 54 during the heating operation in which the electrolytic solution 4 is circulated through the bypass passage 53 to be warmed 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 normal operation for circulating the electrolytic solution 4 to the battery cell 10 . This is because, unlike the battery cell 10, there is no member that serves as a flow resistor for the electrolytic solution 4. FIG. The output of the pump 54 during the heating operation can be, for example, 1/2 or less of the output of the pump 54 during the normal operation, or can be 1/3 or less. The output of the pump 54 during the heating operation is, for example, 1/5 or more times the output of the pump 54 during normal operation in order to warm the electrolytic solution 4 . The operation control unit 65 preferably turns 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 detected temperature of the electrolytic solution 4 in the tank 3 is equal to or higher than the predetermined temperature, the valve control section 652 closes the first valve 551 . By this control, the bypass 53 is closed. The pump control section 651 operates the pump 54 with a predetermined output. The output of the pump 54 during normal operation is usually greater than the output of the pump 54 during heating operation. This is because it is necessary to flow the electrolyte solution 4 through a member such as the battery cell 10 that serves as a flow resistor for the electrolyte solution 4 . When the operation is shifted from the heating operation to the normal operation, the control of the pump 54 by the pump control unit 651 may be performed after temporarily stopping the pump 54, or may be performed without stopping the pump 54 once. good too. The operation control unit 65 preferably turns on the AC/DC converter 100 before controlling the valve control unit 652 and the pump control unit 651 .

Regardless of whether the detected temperature of the electrolytic solution 4 in the tank 3 is lower than or higher than the predetermined temperature, the control order of the valve control section 652 and the pump control section 651 may be the same or different. If the control order is different, it does not matter which one is performed first, but it is preferable that the pump 54 is stopped when the first valve 551 is opened or closed. The reason for this is to facilitate the opening and closing of the first valve 551 .

[Effect]
In the RF battery system 1 of this embodiment, the forward path 51 has a high position portion 513 higher than the highest position of the bypass path 53 . Therefore, when the bypass passage 53 is opened by the first valve 551 , the electrolytic solution 4 becomes less likely to flow to the second passage 512 of the outward passage 51 and more likely to flow to the bypass passage 53 . The length of the flow path through which the electrolytic solution 4 flows through the bypass 53 is shorter than the flow route through which the electrolytic solution 4 flows through the battery cells 10 . Therefore, the electrolytic solution 4 warmed by driving the pump 54 can be quickly returned to the tank 3 via the bypass passage 53 . Therefore, the temperature of the electrolytic solution 4 is less likely to drop in the middle of the flow path. 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 temperature drop. Therefore, the RF battery system 1 of this embodiment can efficiently warm the electrolytic solution 4 in the tank 3 .

In addition, the RF battery system 1 of this embodiment can return the electrolytic solution 4 warmed by driving the pump 54 to the tank 3 through the bypass 53 without supplying it to the battery cell 10 . 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 this embodiment, the electrolytic solution 4 that has reached a predetermined temperature is allowed to flow through the battery cells 10 . Therefore, the RF battery system 1 of the present embodiment can promote charge/discharge reactions and improve battery efficiency, thereby improving battery performance.

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

[Distribution mechanism]
(Outbound/Bypass route)
The highest positions of the forward route 51 and the bypass route 53 are the same in this embodiment. The highest position of the forward line 51 and the bypass line 53 is the highest point of the central axis of each pipe line. The highest positions of the second channel 512 and the bypass channel 53 are at 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 flow 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 closing of the second flow path 512 by the second valve 552 and the opening of the bypass 53 by the first valve 551 enable the flow of the electrolytic solution 4 to the bypass 53 . The installation location of the second valve 552 is in the middle of the second flow path 512 . The type of second valve 552 can be similar to the type of first valve 551 . The second valve 552 is controlled by a valve control section 652 .

[Control mechanism]
(operation control part)
<Valve controller>
The valve control section 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 section 61 . That is, the valve control unit 652 opens and closes the first valve 551 and the second valve 552 .

[Method of operating RF battery system]
When the temperature of the electrolyte 4 in the tank 3 detected by the liquid temperature detector 61 is lower than a predetermined temperature, the valve controller 652 opens the first valve 551 . Also, the valve control unit 652 closes the second valve 552 . By this control, the bypass 53 is opened. Also, the second flow path 512 is closed. The pump controller 651 is the same as when the temperature of the electrolytic solution 4 is lower than the predetermined temperature in the first embodiment. As in the first embodiment, the operation control unit 65 preferably turns off the AC/DC converter 100 before control by the valve control unit 652 and the pump control unit 651 .

On the other hand, when the detected temperature of the electrolytic solution 4 in the tank 3 is equal to or higher than the predetermined temperature, the valve control section 652 closes the first valve 551 . Also, the valve control unit 652 opens the second valve 552 . By this control, the bypass 53 is closed. Also, the second flow path 512 is opened. The pump control unit 651 is the same as when the temperature of the electrolytic solution 4 is equal to or higher than the predetermined temperature in the first embodiment. As in the first embodiment, the operation control unit 65 preferably turns on the AC/DC converter 100 before control by the valve control unit 652 and the pump control unit 651 .

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

[Effect]
The RF battery system 1 of this embodiment can efficiently warm the electrolytic solution 4 and supply the battery cell 10 with the electrolytic solution 4 that has reached a predetermined temperature, as in the first embodiment. In particular, in the RF battery system 1 of this 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]
An RF battery system 1 according to Embodiment 3 will be described with reference to FIG. The RF battery system 1 of this embodiment differs from that of Embodiment 1 in that the switching structure 55 is composed of the first valve 551 and at least part of the bypass passage 53 . The method of operating the first valve 551 and the RF battery system is the same as in the first embodiment.

[Distribution mechanism]
(Outward)
The highest position of the outward route 51 is the same as the highest position of the bypass route 53 in this embodiment. The highest position of the forward line 51 and the bypass line 53 is the highest point of the central axis of each pipe line. The highest positions of the second channel 512 and the bypass channel 53 are at the same height over the entire length.

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

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

In addition, it is preferable that the switching structure 55 of the RF battery system 1 of the present embodiment further includes the second valve 552 (FIG. 2) described in the second embodiment. The reason for this is that when the electrolytic solution 4 is allowed to flow through the bypass passage 53 , the electrolytic solution 4 can be reliably prevented from flowing to the battery cell 10 .

[Effect]
The RF battery system 1 of this embodiment can efficiently warm the electrolytic solution 4 and supply the battery cell 10 with the electrolytic solution 4 that has reached a predetermined temperature, as in the first embodiment.

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

(Switching structure)
<Switching valve>
The switching valve 553 opens one of the second flow path 512 of the forward path 51 and the bypass path 53 and closes the other. 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 a connection point 510 between the forward line 51 and the bypass line 53 . The type of switching valve 553 is, for example, a three-way valve.

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

[Method of operating RF battery system]
When the temperature of the electrolytic solution 4 in the tank 3 detected by the liquid temperature detection unit 61 is lower than a predetermined temperature, the valve control unit 652 switches so as to open the bypass passage 53 and close the second flow passage 512. Operate valve 553 . The pump controller 651 is the same as when the temperature of the electrolytic solution 4 is lower than the predetermined temperature in the first embodiment. As in the first embodiment, the operation control unit 65 preferably turns off the AC/DC converter 100 before control by 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 tank 3 is equal to or higher than the predetermined temperature, the valve control section 652 operates the switching valve 553 so as to open the second passage 512 and close the bypass passage 53 . The pump control unit 651 is the same as when the temperature of the electrolytic solution 4 is equal to or higher than the predetermined temperature in the first embodiment. As in the first embodiment, the operation control unit 65 preferably turns on the AC/DC converter 100 before control by the valve control unit 652 and the pump control unit 651 .

[Effect]
The RF battery system 1 of this embodiment can efficiently warm the electrolytic solution 4 and supply the battery cell 10 with the electrolytic solution 4 that has reached a predetermined temperature, as in the first embodiment. In particular, in the RF battery system 1 of this 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 cells 10 during the heating operation.

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

(bypass road)
The bypass passage 53 allows the electrolytic solution 4 flowing through the outward passage 51 not to circulate to the battery cell 10 , but to flow from the connection point 510 in the middle of the outward passage 51 to the tank 3 . That is, the electrolytic solution 4 flowing through the bypass passage 53 is discharged to the tank 3 without passing through the battery cell 10 and the return passage 52 . The upstream of the bypass passage 53 is arranged above the tank 3 . The downstream of bypass 53 opens to the gas phase in tank 3 .

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

<<Test example>>
In the test example, the RF battery system 1 according to Embodiment 1 described with reference to FIG. was measured. That is, in the test example, the bypass passage 53 was opened by opening the first valve 551 , and the electrolytic solution 4 was pressure-fed by the pump 54 . The electrolytic solution 4 was circulated through 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 in this order. 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 o'clock while continuously flowing the electrolytic solution 4 . The results are shown in FIG. The graph of FIG. 6 shows changes in the temperature of the electrolytic solution 4 and changes in the outside air temperature over time. A change in temperature of the electrolytic solution 4 is indicated by a solid line. Changes in outside temperature are indicated by dashed lines. The horizontal axis of FIG. 6 is time (Hour). The vertical axis in FIG. 6 is temperature (° C.).

As shown in FIG. 6, the outside air temperature repeatedly rose and fell over 24 hours. The difference between the lowest and highest outside temperatures was about 10°C. In spite of such large changes in the outside air temperature, the temperature of the electrolytic solution 4 could be maintained within the range of 30.3° C. or more and 31.2° C. or less over 24 hours. Also, the average temperature of the 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 by 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 Embodiment 1, the temperature of the electrolyte 4 in the tank 3 was measured by warming the bottom of the tank 3 from the outside with a heater without circulating the electrolyte 4 . The heater power 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 while continuously warming the bottom of the tank 3 with a heater. The results are shown in FIG. Similar to FIG. 6, the graph of FIG. 7 shows changes in the temperature of the electrolytic solution 4 and changes in the outside air temperature over time. A change in temperature of the electrolytic solution 4 is indicated by a solid line. Changes in outside temperature are indicated by dashed lines. The horizontal axis of FIG. 7 is time (Hour). The vertical axis of FIG. 7 is temperature (° C.).

As shown in FIG. 7, the ambient temperature remained largely unchanged within the range of 12° C. to 15° C. over the 12 hours. Although the outside air temperature hardly changed, the temperature of the electrolytic solution 4 did not rise above 30°C over the 12 hours, but was within the range of 26.4°C or higher and 27.0°C or lower. Also, the average temperature of the 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 by the power of the heater/the temperature difference was about 0.36 kW/°C.

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

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

1 RF Battery System 10 Battery Cell 20 Cell Stack 3 Tank 4 Electrolyte 5 Flow Mechanism 51 Outbound Path 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 Part 54 Pump 55 Switching structure 551 First valve 552 Second valve 553 Switching valve 6 Control mechanism 61 Fluid temperature detector 65 Operation controller 651 Pump controller 652 Valve controller 100 AC/DC converter 110 Power generator 120 Substation equipment 130 Load

Claims (6)

a tank for storing an electrolytic solution;
a battery cell;
A circulation mechanism for circulating the electrolyte between the tank and the battery cell,
The distribution mechanism is
an outward route for supplying the electrolyte in the tank to the battery cell;
a return path for discharging the electrolyte from the battery cell to the tank;
A redox flow battery system comprising a pump for pumping the electrolytic solution in the tank,
The distribution mechanism is
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 circulation of the electrolytic solution to the battery cell and circulation to the bypass ,
Furthermore,
a liquid temperature detection unit that detects the temperature of the electrolyte in the tank;
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;
Redox flow battery system. The switching structure is
a first valve that opens and closes the bypass;
2 . The redox flow battery system according to claim 1 , further comprising a portion higher than the highest position of the bypass on the downstream side of the outward path than the connection point between the outward path and the bypass. The switching structure is
a first valve that opens and closes the bypass;
3. The redox flow battery system according to claim 1, further comprising a second valve that opens and closes a portion downstream of the outward path from a connection point between the outward path and the bypass. The switching structure is
a first valve that opens and closes the bypass;
The redox flow battery system according to any one of claims 1 to 3, further comprising a portion in which the cross-sectional area of the internal space in the bypass passage is larger than the cross-sectional area of the internal space in the forward passage. 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 forward path and the bypass path. A method of operating a redox flow battery system in which the electrolyte is circulated between a tank in which the electrolyte is stored and a battery cell,
When the temperature of the electrolyte in the tank satisfies a predetermined temperature range, the battery cell is bypassed and the electrolyte is circulated from the outward path to the return path of the battery cell, or from the outward path to the tank.
A method of operating a redox flow battery system.

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