Thermal storage system

Abstract

To provide a heat storage system that has a longer heat radiation operable time.SOLUTION: A heat storage system comprises a first heat storage tank which contains a heat storage substance and circulates a fluid horizontally to accumulate and radiate heat. The heat storage system comprises a second heat storage tank which is connected in series with the first heat storage tank, and contains a heat storage substance and circulates the fluid in a perpendicular direction to accumulate and radiate heat. In the heat storage system in heat accumulating operation, the fluid flowing out of the first heat storage tank flows into the second heat storage tank, and the second heat storage tank circulates the fluid from above to below in the perpendicular direction. In the heat storage system in heat radiating operation, the fluid flowing out of the second heat storage tank flows in the first heat storage tank, and the second heat storage tank circulates the fluid from below to above in the perpendicular direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a thermal storage system. [Background technology]

[0002] In recent years, power generation from natural energy sources such as solar power and wind power has been increasing, and there are areas where the amount of power generated exceeds the power demand depending on the season and time of day. Also, there are cases where the power demand is so high depending on the season and time of day that the amount of power generated does not meet the power demand, resulting in a power shortage.

[0003] A thermal storage system uses surplus electricity to store heat in a thermal storage material in a thermal storage tank. In addition, some power generation systems use a thermal storage system to generate steam using the stored heat during times of power shortage, which then drives a steam turbine to generate electricity.

[0004] FIG. 5 is a diagram showing the overall configuration of a heat storage system according to the first prior art.

[0005] The thermal storage system 100 in the first prior art includes a thermal storage tank 1, an electric heater 2, a first fan 3, a second fan 4, a condensate pump 8, a boiler 9, a steam turbine 10, a condenser 11, and a plurality of valves 12 to 15. Fig. 5 further shows air 5, water 6, and steam 7 circulating within the thermal storage system 100. The thermal storage tank 1 shown in Fig. 5 is arranged so that its longitudinal direction is parallel to the horizontal direction and its lateral direction is parallel to the vertical direction.

[0006] When there is surplus electricity, the thermal storage system 100 stops the condensate pump 8, steam turbine 10, and second fan 4, opens valves 12 and 13, closes valves 14 and 15, and uses the surplus electricity to operate the electric heater 2 and the first fan 3. The thermal storage system 100 circulates air 5 between the electric heater 2 and the thermal storage tank 1 using the first fan 3. The air 5 is heated by the heat generated by the electric heater 2, transports the heat to the thermal storage tank 1, and heats the thermal storage material in the thermal storage tank 1. In this way, the thermal storage system 100 performs a thermal storage operation.

[0007] When there is no surplus power, the thermal storage system 100 stops the electric heater 2 and the first fan 3, closes valves 12 and 13, opens valves 14 and 15, and operates the condensate pump 8 and the second fan 4. The thermal storage system 100 circulates air 5 between the thermal storage tank 1 and the boiler 9 using the second fan 4. The air 5 is heated by the thermal storage material in the thermal storage tank 1 and transports the heat to the boiler 9. The boiler 9 heats water 6 brought in by the condensate pump 8 using the heat from the air 5 to produce steam 7, and the air 5 flows out with its temperature reduced. In this way, the thermal storage system 100 performs a heat dissipation operation.

[0008] In the heat dissipation operation, the steam 7 produced by the thermal storage system 100 flows through the steam turbine 10 at low temperature and low pressure, thereby rotating the steam turbine 10, which is an impeller. A generator (not shown) mechanically connected to the steam turbine 10 generates electricity. The steam 7 discharged from the steam turbine 10 is cooled by the condenser 11 with cooling water such as seawater and converted into water. As a result, the thermal storage system 100 generates steam 7 using the heat stored in the thermal storage material in the thermal storage tank 1, and generates electricity.

[0009] As described above, when there is a power surplus, the thermal storage system 100 performs a thermal storage operation using the power, and when there is a power shortage, it performs a power adjustment by generating power through a heat dissipation operation.

[0010] FIG. 6 is a schematic diagram of a heat storage tank in a heat storage system according to the first prior art.

[0011] FIG. 6 shows the details of the heat storage tank 1. The heat storage system 100 of the first prior art includes one heat storage tank 1. A heat storage material is provided inside the heat storage tank 1. The heat storage material is, for example, a solid sensible heat storage material 23, which is rock in this case. During heat storage operation and heat release operation, the heat storage tank 1 opens valves 16 and 17 to allow air 5 to circulate horizontally. The solid arrow in FIG. 6 indicates the air flow direction 32 during heat storage operation, and the dashed arrow indicates the air flow direction 33 during heat release operation.

[0012] FIG. 7 shows the temperature distribution in the heat storage tank after the end of the heat storage operation in the first prior art.

[0013] FIG. 7A shows the temperature distribution in the heat storage tank immediately after the end of the heat storage operation in the first prior art.

[0014] The solid horizontal line drawn inside the heat storage tank 1 indicates the solid sensible heat storage material temperature 24, and the higher the horizontal line, the higher the temperature inside the heat storage tank 1. The dashed line in each diagram indicates the lower limit temperature for heat utilization in heat radiation operation, which will be referred to as the heat radiation operation required temperature 25. In other words, by having more high-temperature regions and suppressing the decrease in the region below the heat radiation operation required temperature 25, the heat storage system 100 can increase the heat radiation operation available time.

[0015] During heat storage operation, a thermocline 26, which shows a steep temperature gradient, is formed in the heat storage tank 1 in the direction of the air 5 flow. On the upstream side of the heat storage tank 1, the heat storage material is heated, creating high-temperature areas. On the downstream side, on either side of the thermocline 26, low-temperature areas are created. This region where the temperature is constant is called the constant high-temperature region (high-temperature region). Heat storage operation continues until the temperature of the air 5 flowing out of the heat storage tank 1 rises to the heat-resistant temperature of the second fan 4.

[0016] FIG. 7B shows the temperature distribution in the heat storage tank after being left unused for a long period of time in the first prior art.

[0017] After the heat storage operation is completed, the heat storage tank 1 is left for a long time until the heat dissipation operation starts. As time passes, the temperature distribution in the heat storage tank 1 changes, as shown in Figure 7B. The heat inside the heat storage tank 1 tries to average out the temperature, moving from higher temperatures to lower temperatures. This reduces the area of ​​the heat storage tank 1 where the temperature is constantly high. Since the heat dissipation operation can only be performed until the heat used by equipment such as the boiler 9 has dropped to the lower usable temperature, reducing the area where the temperature is constantly high reduces the time during which the heat dissipation operation is possible.

[0018] FIG. 8 is a diagram showing the overall configuration of a heat storage system according to the second prior art.

[0019] In the heat storage system 100 of the second prior art, the heat storage tank 1 is divided into three, and the divided heat storage tanks are referred to as heat storage tanks 29, 30, and 31. The heat storage system 100 is also provided with valves 12, 14, 19, 20, and 21 that control the flow of air 5 during heat storage operation and heat release operation.

[0020] During the heat storage operation and the heat dissipation operation, the heat storage system 100 causes the air 5 to circulate horizontally through the three divided heat storage tanks 29, 30 and 31 based on the opening and closing of the valves 12, 14, 19, 20 and 21.

[0021] For example, during the heat storage operation, the heat storage system 100 opens the valves 12, 19, 20, and 21, and causes the first fan 3 to circulate the air 5 between the electric heater 2 and each of the heat storage tanks 29, 30, and 31, thereby storing heat in each of the heat storage tanks 29, 30, and 31. In Fig. 8, the heat storage materials in each of the heat storage tanks 29, 30, and 31 are heated in this order.

[0022] The horizontal lines drawn in the heat storage tanks 29, 30, and 31 represent the temperatures in the respective heat storage tanks 29, 30, and 31 during heat storage operation, and for example, the horizontal line drawn in the heat storage tank 31 indicates that the temperature is relatively low and constant in the upstream and downstream directions of the air 5. In this figure, a thermocline 26 is formed in the heat storage tank 30.

[0023] During the heat storage operation, the solid sensible heat storage material 23 is heated in the heat storage tanks 29, 30, and 31, forming a thermocline 26, which moves from the upstream side to the downstream side of each of the heat storage tanks 29, 30, and 31 in the flow direction of the air 5. The heat storage operation ends when the temperature of the air 5 flowing out of the heat storage tank 31 rises to the heat resistance temperature of the second blower 4. Immediately after the end of the heat storage operation, the thermocline 26 is formed in the heat storage tank 31, which is downstream.

[0024] After the heat storage operation is completed, in the heat storage system 100, the valves 12, 14, 19, 20, and 21 are closed and the heat storage tanks 29 to 31 are left standing for a long time until the heat dissipation operation is started. In the heat storage system 100, the temperature distribution in the heat storage tank 31 changes over time. In the heat storage tank 31, the temperature tends to average out, and the area where the temperature is constantly high decreases.

[0025] FIG. 9 is a diagram showing the temperature distribution in the heat storage tank after the end of the heat storage operation in the heat storage system of the second prior art.

[0026] FIG. 9A is a diagram showing the temperature distribution in the heat storage tank immediately after the end of the heat storage operation in the heat storage system of the second prior art.

[0027] 9A, in order to explain a comparison with the configuration of the first embodiment described later, heat storage tanks 29 and 30 are collectively referred to as the "first heat storage tank 27," and heat storage tank 31 is referred to as the "second heat storage tank 28." To facilitate the comparison of the configuration, valves 12, 20, and 21 will be renumbered and referred to as "valves 16, 18, and 17." The pipe connecting the first heat storage tank 27 and the second heat storage tank 28 is referred to as the pipe 22.

[0028] As shown in FIG. 9A, immediately after the end of the heat storage operation of the heat storage system 100, a constant high temperature region is formed in the first heat storage tank 27 and a part of the second heat storage tank .

[0029] FIG. 9B is a diagram showing the temperature distribution after the first heat storage tank and the second heat storage tank have been left standing for a long period of time.

[0030] 9A, if 16 to 18 are closed and first heat storage tank 27 and second heat storage tank 28 are left standing for a long time, the heat in second heat storage tank 28, which is the most downstream heat storage tank, will tend to average out and move from higher temperatures to lower temperatures. As a result, the area of ​​constant high temperatures in first heat storage tank 27 does not decrease, as in the temperature distribution shown in FIG. 9B, but the area of ​​constant high temperatures in second heat storage tank 28 decreases.

[0031] 9B, in the second conventional technology, the first heat storage tank 27 is maintained in a constant high temperature region, and therefore the heat radiation time during which the temperature is maintained at or above the required temperature for heat radiation operation 25 is longer than in the first conventional technology. As a result, the second conventional technology has less reduction in the available time for heat radiation operation.

[0032] However, in the second heat storage tank 28, the area where the temperature is constantly high is reduced due to the temperature averaging. As this area where the temperature is constantly high is reduced, the heat storage system 100 is capable of operating for a shorter period of time during which heat dissipation is possible. [Prior art documents] [Patent documents]

[0033] [Patent Document 1] International Publication No. WO2016 / 150461 Summary of the Invention [Problem to be solved by the invention]

[0034] In the first prior art, the available heat radiation operation time was reduced when the heat storage tank 1 was left unused for a long period of time. In the second prior art, the reduction in the available heat radiation operation time for the entire heat storage tank 1 was small, but the second heat storage tank 28, which is the most downstream in the heat storage operation, experienced a reduction in the area of ​​constant high temperature due to temperature averaging when left unused for a long period of time.

[0035] Therefore, an embodiment of the present invention provides a heat storage system that can perform heat radiation operation for a longer period of time by reducing the decrease in the constant high temperature region. [Means for solving the problem]

[0036] According to one embodiment, the thermal storage system includes a first thermal storage tank containing a thermal storage material, through which a fluid flows in a horizontal direction, and stores and releases heat. The thermal storage system further includes a second thermal storage tank connected in series to the first thermal storage tank, containing a thermal storage material, through which the fluid flows in a vertical direction, and stores and releases heat. During a thermal storage operation, the thermal storage system allows the fluid flowing out of the first thermal storage tank to flow into the second thermal storage tank, and the second thermal storage tank allows the fluid to flow from above to below in the vertical direction. During a thermal release operation, the thermal storage system allows the fluid flowing out of the second thermal storage tank to flow into the first thermal storage tank, and the second thermal storage tank allows the fluid to flow from below to above in the vertical direction. [Brief explanation of the drawings]

[0037] [Figure 1] FIG. 2 is a schematic diagram of a heat storage tank in the heat storage system of the first embodiment. [Figure 2] FIG. 4 is a diagram showing the temperature distribution in the heat storage tank after the end of the heat storage operation in the heat storage system of the first embodiment. [Figure 3] FIG. 10 is a configuration diagram of a heat storage tank portion of a heat storage system according to a second embodiment. [Figure 4] FIG. 10 is a configuration diagram of a heat storage tank portion of a heat storage system according to a third embodiment. [Figure 5] FIG. 1 is an overall configuration diagram of a heat storage system according to a first prior art. [Figure 6] FIG. 1 is a schematic diagram of a heat storage tank in a heat storage system according to a first prior art. [Figure 7] 10 shows the temperature distribution in the heat storage tank after the end of the heat storage operation in the first prior art. [Figure 8] FIG. 10 is an overall configuration diagram of a heat storage system according to a second prior art. [Figure 9] FIG. 10 is a diagram showing the temperature distribution in the heat storage tank after the end of the heat storage operation in the heat storage system of the second prior art. DETAILED DESCRIPTION OF THE INVENTION

[0038] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present invention is not limited to these embodiments. The drawings are schematic or conceptual, and the proportions of the various parts are not necessarily the same as those in reality. In the specification and drawings, elements similar to those described above with reference to the previous drawings are designated by the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0039] (First embodiment) FIG. 1 is a schematic diagram of a heat storage tank in a heat storage system of the first embodiment.

[0040] The overall configuration diagram of the thermal storage system 100 is the same as that shown in FIG. 5, and therefore the description thereof will be omitted.

[0041] Figure 1 shows the X-axis, Y-axis, and Z-axis, which are perpendicular to each other. The X-axis and Y-axis correspond to the horizontal direction perpendicular to the direction of gravity, and the Z-axis corresponds to the vertical direction parallel to the direction of gravity. The +Z direction corresponds to the upward direction, and the -Z direction corresponds to the downward direction.

[0042] Compared to the heat storage tank 1 in Fig. 6, the heat storage tank 1 in this embodiment is divided in series in the flow direction of the air 5. In the following embodiments, for the sake of explanation, an example in which the tank is divided into a predetermined number of divisions is taken up, but the number of divisions is not limited to this. In the heat storage system 100, the heat storage tank 1 may be divided in series into any number of divisions in the flow direction of the air 5.

[0043] In this embodiment, an example is shown in which the heat storage tank 1 is divided into two, a first heat storage tank 27 and a second heat storage tank 28. In this embodiment, the first heat storage tank 27 is arranged so that air 5 flows horizontally within the first heat storage tank 27. In addition, the second heat storage tank 28 is arranged so that air 5 flows vertically within the second heat storage tank 28. In addition, the first heat storage tank 27 and the second heat storage tank 28 are connected in series. The air 5 is an example of a fluid.

[0044] During the heat storage operation, as shown in air flow direction 32 during the heat storage operation, first heat storage tank 27 circulates air 5 from the first side to the second side in the horizontal direction (in this figure, from the negative side to the positive side in the X direction). Air 5 flowing out of first heat storage tank 27 flows into second heat storage tank 28. Second heat storage tank 28 circulates air 5 from the upper side to the lower side in the vertical direction (in this figure, from the positive side to the negative side in the Z direction).

[0045] During heat dissipation operation, as shown in air flow direction 33 during heat dissipation operation, second heat storage tank 28 circulates air 5 from the lower side to the upper side in the vertical direction (from the positive side to the negative side in the X direction in this figure). Air 5 flowing out of second heat storage tank 28 flows into first heat storage tank 27. First heat storage tank 27 circulates air 5 from the second side to the first side in the horizontal direction (from the positive side to the negative side in the X direction in this figure).

[0046] After the heat storage operation is completed, second heat storage tank 28 is in a state where the upper side is hot and the lower side is cold. As a result, there is little natural convection in the air 5 present between solid sensible heat storage materials 23. As a result, even if second heat storage tank 28 is left unused for a long period of time, high-temperature air 5 remains at the upper side, and low-temperature air 5 remains at the lower side. The temperature of solid sensible heat storage material 23 in second heat storage tank 28 does not average out as shown in Figure 9B, and thermocline 26 does not change, or the temperature gradient between the high-temperature and low-temperature parts of thermocline 26 becomes stronger.

[0047] The number of heat storage tanks connected in series is not limited to 2. The heat storage system 100 includes a plurality of heat storage tanks, including a first heat storage tank 27 through which air 5 flows in the horizontal direction and a second heat storage tank 28 through which air 5 flows in the vertical direction, and the second heat storage tank 28 may be the most downstream heat storage tank among the plurality of heat storage tanks during heat storage operation.

[0048] The multiple heat storage tanks may include an Nth heat storage tank (N is an integer of 3 or more) different from the first heat storage tank 27 and the second heat storage tank 28. The Nth heat storage tank is configured to circulate air 5 horizontally. The Nth heat storage tank is connected in series with the first heat storage tank 27 and the second heat storage tank 28. The second heat storage tank 28 is connected as the most downstream heat storage tank among the multiple heat storage tanks during heat storage operation. Valves are connected to the inlet and outlet of each heat storage tank.

[0049] For example, when N=3, the multiple heat storage tanks included in the heat storage system 100 include a third heat storage tank (not shown) that circulates air 5 in the horizontal direction, and the third heat storage tank is connected in series with the first heat storage tank 27 and the second heat storage tank 28. Furthermore, the second heat storage tank 28 is connected as the most downstream heat storage tank among the multiple heat storage tanks during heat storage operation.

[0050] In this embodiment, the first heat storage tank 27 and the second heat storage tank are connected by a pipe 22, and valves 16, 17, and 18 are provided at the inlet and outlet of the air 5 during the heat storage or heat release operation.

[0051] The opening and closing of these valves 16 to 18 is controlled by a control unit 37, such as a PLC (Programmable Logic Controller). Control signals output from the control unit 37 are transmitted to actuators (not shown), which open and close the valves. The valves 16 to 18 may also be opened and closed manually.

[0052] Furthermore, a pipe 34 is connected to the side of the lower part of the second heat storage tank 28. The solid sensible heat storage material 23 is, for example, rock. If the pipe 34 is provided on the bottom of the second heat storage tank 28, the rocks will block the inlet and outlet of the pipe 34 if the rock particles are large, and will clog the inside of the pipe 34 if the rock particles are small. For this reason, a mesh-like rock receiving part 35 is provided inside the second heat storage tank 28 above the position of the pipe. It is desirable that the lattice size of the rock receiving part 35 is large enough to prevent rocks from slipping through and falling, but large enough to allow air 5 to escape during heat storage operation and heat release operation.

[0053] During the heat storage operation, the second heat storage tank 28 allows the air 5 to flow out from the pipe 34, and during the heat dissipation operation, the second heat storage tank 28 allows the air 5 to flow in from the pipe 34.

[0054] During operation, small rock fragments fall off the second thermal storage tank 28 due to vibrations and air circulation caused by the operation of the thermal storage system 100. Gravity causes the rock fragments and the powder of the broken rock fragments to fall below the rock receiving component 35 and gradually accumulate inside the second thermal storage tank 28. Periodic maintenance of the second thermal storage tank 28 is required to prevent abnormalities in the pipes and the first or second blowers 3 and 4. Maintenance must be performed by removing all rocks. Furthermore, it is difficult to support the large total weight of rocks in the second thermal storage tank 28 using the mesh-like rock receiving component 35 due to the strength of the second thermal storage tank 28. Therefore, in this embodiment, instead of arranging all the thermal storage tanks vertically, only the second thermal storage tank 28 is arranged vertically.

[0055] Furthermore, the piping 34 is provided below the position of the rock receiving component 35 provided in the second heat storage tank 28 so as not to impede the inflow or outflow of the air 5. As a result, even if stone chips or powder fall from the rock receiving component 35, the piping 34 will not be immediately blocked, and the heat storage system 100 can continue to operate.

[0056] In addition, in the heat storage system 100 of this embodiment, the capacity of the solid sensible heat storage material 23 in the second heat storage tank 28 is smaller than that of the first heat storage tank 27, from the standpoint of ease of removing rocks during maintenance and strength of the rock receiving component 35.

[0057] After the heat storage operation is completed, the heat storage system 100 closes the valves 16, 17, and 18 at the inlets and outlets for the air 5 of the first heat storage tank 27 and the second heat storage tank 28. This makes it difficult for heat to transfer and maintains a high temperature state even if the first and second heat storage tanks 27, 28 are left unused for a long period of time.

[0058] In the first heat storage tank 27 and the N heat storage tank of this embodiment, air 5 flows only in the ±X directions during heat storage operation and heat release operation. However, as long as the air 5 in the first heat storage tank 27 and the N heat storage tank flows mainly in the ±X directions, it may also flow in the ±Y and ±Z directions in addition to the ±X directions. For example, it is sufficient that the air 5 has a velocity component in the X direction that is greater than the velocity component in the Y direction or the velocity component in the Z direction within the solid sensible heat storage material 23 in the first heat storage tank 27 and the N heat storage tank. The flow of air 5 in this manner is also included in the flow of air 5 in the horizontal direction. This also applies to the second and third embodiments described below.

[0059] Furthermore, in the second heat storage tank 28 of this embodiment, the air 5 flows only in the ±Z direction during the heat storage operation and the heat dissipation operation, but the air 5 in the second heat storage tank 28 may flow not only in the ±Z direction but also in the ±X direction and ±Y direction as long as it flows mainly in the ±Z direction. For example, it is sufficient that the air 5 has a velocity component in the Z direction that is greater than the velocity component in the X direction or the velocity component in the Y direction within the solid sensible heat storage material 23 in the second heat storage tank 28. The flow of the air 5 in this manner is also included in the flow of the air 5 in the vertical direction. This also applies to the second and third embodiments described below.

[0060] FIG. 2 is a diagram showing the temperature distribution in the heat storage tank after the end of the heat storage operation in the heat storage system of the first embodiment.

[0061] Figure 2 shows the temperature distribution when the first and second heat storage tanks 27, 28 are left unused for a long period of time. The horizontal axis of Figure 2 indicates the position in the first heat storage tank 27 and the second heat storage tank 28, and the vertical axis indicates the solid sensible heat storage material temperature 24. Because the piping 22 does not have a heat storage function, this figure does not show the temperature distribution diagram inside the corresponding piping 22. As shown in Figure 2, even if the first and second heat storage tanks 27, 28 are left unused for a long period of time until the start of heat dissipation operation, the thermocline 26 does not change, or the temperature gradient between the high-temperature and low-temperature parts of the thermocline 26 becomes stronger. In other words, the second heat storage tank 28 has a larger area of ​​constant high temperature.

[0062] During the heat dissipation operation, the air 5 flows through the second heat storage tank 28 and then the first heat storage tank 27. When the air 5 flows from the bottom to the top of the second heat storage tank 28, it is possible to secure a large area where the temperature remains constant at a high temperature. This allows the heat storage system 100 to secure a longer period of time during which the heat dissipation operation is possible.

[0063] In the above example, the heat radiated by the thermal storage system 100 is used as a heat source for the steam turbine 10, but it may also be used for purposes such as air conditioning.

[0064] According to this embodiment, the heat storage system 100 divides the heat storage tank 1 into parts and arranges the parts so that the air 5 flows vertically, thereby reducing the decrease in the heat radiation operation available time.

[0065] Furthermore, according to this embodiment, the heat storage system 100 divides only a portion of the heat storage tank 1 and arranges it as the second heat storage tank 28 so that air 5 flows vertically. This allows the heat storage system 100 to maintain the strength to hold the solid sensible heat storage material 23 when a mesh-like rock receiving component 35 is provided in the second heat storage tank 28. Furthermore, during maintenance, the solid sensible heat storage material 23 in the second heat storage tank 28 can be removed for work, resulting in a structure that ensures maintainability.

[0066] Furthermore, according to this embodiment, an Nth heat storage tank that circulates air 5 in a horizontal direction may be connected to the first heat storage tank 27 and the second heat storage tank 28. The Nth heat storage tank is connected in series with the first heat storage tank 27 and the second heat storage tank 28. This allows the first heat storage tank 27 and the Nth heat storage tank to maintain a constant high temperature range after the heat storage operation, and also allows the second heat storage tank 28 to reduce the decrease in the available time for heat dissipation operation.

[0067] (Second embodiment) FIG. 3 is a configuration diagram of a heat storage tank portion of a heat storage system in the second embodiment.

[0068] The overall configuration diagram of the thermal storage system 100 is the same as that shown in FIG. 5, and therefore the description thereof will be omitted.

[0069] In the first embodiment, the thermal storage system 100 has one first thermal storage tank 27 and one second thermal storage tank 28 connected in series. On the other hand, in the present embodiment, the thermal storage system 100 has one first thermal storage tank 27 and one second thermal storage tank 28 connected in series to form one group, and further includes a plurality of groups having such a configuration. Furthermore, each group of thermal storage tanks is connected in parallel.

[0070] As in the first embodiment, in this embodiment, the first heat storage tank 27 is disposed so that the air 5 flows horizontally within the first heat storage tank 27. Moreover, the second heat storage tank 28 is disposed so that the air 5 flows vertically within the second heat storage tank 28.

[0071] 3, three groups of heat storage tanks are connected in parallel, and in this example, the three groups are referred to as a first group 40, a second group 41, and a third group 42, respectively.

[0072] The first heat storage tank 27 and the second heat storage tank 28 constituting each group are connected by piping 22, and valves 16, 17 and 18 are provided at the inlets and outlets for the air 5 during the heat storage or heat release operation. The direction of the arrow in this embodiment indicates the air flow direction 32 during the heat storage operation, and during the heat release operation, the air 5 flows in the opposite direction to that during the heat storage operation.

[0073] During the heat storage operation, the air 5 branches on the pipe 36 side, flows to the heat storage tanks of the first group 40, the second group 41, and the third group 42, and then joins together on the pipe 34 side. During the heat storage operation, the heat storage system 100 can circulate the air 5 to all three groups, or to only one or two of the three groups, by opening and closing the valves 16 and 17 in the heat storage tanks of the first group 40, the second group 41, and the third group 42.

[0074] Furthermore, the opening and closing of each of the above-mentioned valves 16 to 18 is controlled, for example, by the control unit 37. Furthermore, the valves 16 to 18 may be opened and closed manually.

[0075] During heat dissipation operation, the air 5 branches on the pipe 34 side, flows to the heat storage tanks of the first group 40, the second group 41, and the third group 42, and then joins together on the pipe 36 side. During heat dissipation operation, the heat storage system 100 can circulate the air 5 to all three groups, or to only one or two of the three groups, by opening and closing the valves 16 and 17 in the heat storage tanks of the first group 40, the second group 41, and the third group 42.

[0076] The number of groups made up of thermal storage tanks is not limited to three. Thermal storage system 100 includes a plurality of first thermal storage tanks 27 that circulate air 5 in the horizontal direction, and each of the first thermal storage tanks 27 may be included in one of first to K-th groups (K is an integer of 2 or more) that are connected in parallel to each other. Thermal storage system 100 also includes a plurality of second thermal storage tanks 28 that circulate air 5 in the vertical direction, and each of the second thermal storage tanks 28 may be included in one of the first to K-th groups and connected in series with the first thermal storage tank 27 of the same group.

[0077] The number of heat storage tanks constituting one group is not limited to 2. Each of the first to Kth groups in the heat storage system 100 includes a plurality of heat storage tanks including the first heat storage tank 27 and the second heat storage tank 28, and the second heat storage tank 28 in each group may be the most downstream heat storage tank during heat storage operation among the plurality of heat storage tanks in that group.

[0078] The multiple heat storage tanks in each group may include multiple Nth heat storage tanks (N is an integer of 3 or more) different from the first heat storage tank 27 and the second heat storage tank 28. Each of the multiple Nth heat storage tanks is configured to circulate air 5 horizontally. Each of the multiple Nth heat storage tanks is included in one of the first to Kth groups and is connected in series with the first heat storage tank 27 and the second heat storage tank 28 of the same group. The second heat storage tank 28 in each group is the most downstream heat storage tank among the multiple heat storage tanks in that group during heat storage operation. A valve is connected to the inlet and outlet of each heat storage tank.

[0079] For example, when K=3 and N=3, the plurality of heat storage tanks in each of the first to third groups include a plurality of third heat storage tanks (not shown) that circulate air 5 in the horizontal direction, and each of the plurality of third heat storage tanks is included in the first to third groups. Furthermore, each of the plurality of third heat storage tanks is connected in series with the first heat storage tank 27 and the second heat storage tank 28 of the same group. The second heat storage tank 28 in each group is connected as the most downstream heat storage tank among the plurality of heat storage tanks in that group during heat storage operation.

[0080] According to this embodiment, in the heat storage system 100, a part of the heat storage tanks constituting each group is provided in the vertical direction, thereby reducing the decrease in the heat radiation operation possible time.

[0081] Furthermore, according to this embodiment, the thermal storage system 100 separates only some of the thermal storage tanks that make up each group, and arranges them as second thermal storage tanks 28 so that air 5 flows vertically. This makes it possible to maintain the strength to hold the solid sensible heat storage material 23 when a mesh-like rock receiving component 35 is provided in the second thermal storage tank 28. Furthermore, during maintenance, the solid sensible heat storage material 23 can be removed from the second thermal storage tank 28, making it possible to perform maintenance work, resulting in a structure that ensures maintainability.

[0082] Furthermore, according to this embodiment, an Nth heat storage tank that circulates air 5 horizontally may be connected to each of the first heat storage tank 27 and the second heat storage tank 28. Each of the Nth heat storage tanks is included in one of the groups and is connected in series with the first heat storage tank 27 and the second heat storage tank 28 of the same group. This allows the first heat storage tank 27 and the Nth heat storage tank to maintain a constant high temperature range after the heat storage operation, and also allows the second heat storage tank 28 to reduce the decrease in the available time for heat dissipation operation.

[0083] Furthermore, according to this embodiment, the heat storage system 100 can select a group of heat storage tanks to perform heat storage operation or heat release operation by connecting the groups of heat storage tanks in parallel and opening and closing the valves 16 to 18. This improves the freedom and flexibility of operation.

[0084] (Third embodiment) FIG. 4 is a configuration diagram of a heat storage tank portion of a heat storage system according to the third embodiment.

[0085] The overall configuration diagram of the thermal storage system 100 is the same as that shown in FIG. 5, and therefore the description thereof will be omitted.

[0086] In the first embodiment, the thermal storage system 100 includes one first thermal storage tank 27 and one second thermal storage tank 28 connected in series. On the other hand, in the present embodiment, the thermal storage system 100 includes a plurality of first thermal storage tanks 27 and one or a plurality of second thermal storage tanks 28, the number of which is less than the number of the first thermal storage tanks 27. Furthermore, the first thermal storage tanks 27 are connected in parallel with each other, and the second thermal storage tanks 28 are connected in series with the first thermal storage tank 27.

[0087] As in the first embodiment, in this embodiment, the first heat storage tank 27 is disposed so that the air 5 flows horizontally within the first heat storage tank 27. Moreover, the second heat storage tank 28 is disposed so that the air 5 flows vertically within the second heat storage tank 28.

[0088] 4, the thermal storage system 100 includes three first thermal storage tanks 27 and one second thermal storage tank 28. The three first thermal storage tanks 27 are connected in parallel with one another, and the second thermal storage tank 28 is connected in series with the three first thermal storage tanks 27 that are connected in parallel with one another.

[0089] The three first heat storage tanks 27 and the one second heat storage tank 28 are connected by piping 22. Valves 16, 17, and 18 are provided at the inlets and outlets for air 5 of the three first heat storage tanks 27 and the one second heat storage tank 28. The direction of the arrows in this embodiment indicates the air flow direction 32 during heat storage operation, and during heat dissipation operation, the air 5 flows in the opposite direction to that during heat storage operation.

[0090] During the heat storage operation, the air 5 branches on the pipe 36 side, flows to each of the three first heat storage tanks 27, and then merges on the pipe 22 side. The merged high-temperature air 5 flows to the second heat storage tank 28 through the pipe 22. During the heat storage operation, the heat storage system 100 can circulate the high-temperature air 5 to all three sets, or to only one or two of the three sets, by opening and closing the valves 16 and 18 in each of the first heat storage tanks 27.

[0091] During heat dissipation operation, the air 5 branches on the pipe 22 side, flows to each of the three first heat storage tanks 27, and then joins together on the pipe 36 side. During heat dissipation operation, the heat storage system 100 can circulate the air 5 to all three sets, or to only one or two of the three sets, by opening and closing the valves 16 and 18 in each first heat storage tank 27.

[0092] The number of first heat storage tanks 27 connected in parallel is not limited to 3. The heat storage system 100 may include a plurality of heat storage tanks including a plurality of first heat storage tanks 27 that circulate air 5 in the horizontal direction, and the first heat storage tanks 27 may be connected in parallel to one another.

[0093] The number of second heat storage tanks 28 connected in series to the first heat storage tank 27 is not limited to one. The heat storage system 100 includes a plurality of first heat storage tanks 27 and one or more second heat storage tanks 28 through which air 5 circulates in the vertical direction, and it is sufficient that the one or more second heat storage tanks 28 are connected in series with the plurality of first heat storage tanks 27 that are connected in parallel to each other. Furthermore, the number of second heat storage tanks 28 is smaller than the number of first heat storage tanks 27. Furthermore, each of the one or more second heat storage tanks 28 is the most downstream heat storage tank during heat storage operation.

[0094] Additionally, valves 16, 17 and 18 may be included at the inlets and outlets of the first and second thermal storage tanks 27, 28, respectively.

[0095] When the thermal storage system 100 includes a plurality of second thermal storage tanks 28, it is possible to select a combination of the first thermal storage tanks 27 through which the air 5 is circulated based on the opening and closing of the valves 18 and the like.

[0096] The heat storage tanks included in the heat storage system 100 are not limited to the multiple first heat storage tanks 27 and one or multiple second heat storage tanks 28. The heat storage system 100 includes multiple heat storage tanks, including multiple first heat storage tanks 27 and one or multiple second heat storage tanks 28, and it is sufficient that the one or multiple second heat storage tanks 28 are connected in series with the multiple first heat storage tanks 27 that are connected in parallel to each other. Furthermore, the number of second heat storage tanks 28 is smaller than the number of first heat storage tanks 27. Furthermore, each of the one or multiple second heat storage tanks 28 is the most downstream heat storage tank during heat storage operation.

[0097] Furthermore, an Nth heat storage tank (N is an integer of 3 or more) different from the first heat storage tank 27 and the second heat storage tank 28 may be connected to each first heat storage tank 27. Each Nth heat storage tank is configured to circulate air 5 horizontally. Each Nth heat storage tank is connected in series to each first heat storage tank 27. Each of one or more second heat storage tanks 28 is connected as the most downstream heat storage tank during heat storage operation. A valve is connected to the inlet and outlet of each heat storage tank.

[0098] For example, the thermal storage system 100 includes a third thermal storage tank (not shown) that circulates air 5 in a horizontal direction, and each of the third thermal storage tanks is connected in series with each of the first thermal storage tanks 27. Furthermore, each of one or more second thermal storage tanks 28 is connected as the most downstream thermal storage tank during thermal storage operation.

[0099] According to this embodiment, the heat storage system 100 divides a part of the heat storage tank and arranges it so that the air 5 flows vertically, thereby reducing the decrease in the heat radiation operation possible time.

[0100] Furthermore, according to this embodiment, the thermal storage system 100 is arranged so that only a portion of the thermal storage tank serves as the second thermal storage tank 28 and allows air 5 to flow vertically. This makes it possible to maintain the strength to hold the solid sensible heat storage material 23 when a mesh-like rock receiving component 35 is provided in the second thermal storage tank 28. Furthermore, during maintenance, the solid sensible heat storage material 23 can be removed from the second thermal storage tank 28, making it possible to achieve a structure that ensures maintainability.

[0101] Furthermore, according to this embodiment, an Nth heat storage tank that circulates air 5 in a horizontal direction may be connected to each first heat storage tank 27. Each Nth heat storage tank is connected in series to each first heat storage tank 27. This allows the first heat storage tank 27 and the Nth heat storage tank to maintain a constant high temperature range after heat storage operation, and also allows the second heat storage tank 28 to reduce the decrease in the available time for heat dissipation operation.

[0102] Furthermore, according to this embodiment, the heat storage system 100 can select the heat storage tank that performs the heat storage operation or the heat release operation by connecting the first heat storage tanks 27 in parallel and opening and closing the valves 16 and 18. This improves the flexibility of operation.

[0103] Furthermore, in the second embodiment, if high-temperature air 5 is circulated through all of the second heat storage tanks 28 during heat storage operation, thermocline 26 will be generated in all of the second heat storage tanks 28. On the other hand, according to the present embodiment, thermocline 26 will be generated in only a smaller number of second heat storage tanks 28. In the example of Fig. 3, thermocline 26 will be generated in three second heat storage tanks 28, but in Fig. 4, thermocline 26 will be generated in only one second heat storage tank 28. Therefore, when the heat storage system 100 performs heat storage operation, the total number of regions where the temperature is equal to or higher than the heat release operation required temperature 25 will be greater than in the second embodiment.

[0104] Because the total area where the required temperature for heat dissipation operation is 25 or higher is larger, the heat storage system 100 can make more heat available for use as a heat source for the steam turbine 10 or for air conditioning during heat dissipation operation.

[0105] Although the heat storage systems 100 of the first to third embodiments are part of a power generation system that generates power using the heat storage systems 100, they may also be part of other systems. For example, the heat storage systems 100 of the first to third embodiments may also be part of an air conditioning system that performs air conditioning using the heat storage systems 100.

[0106] Although several embodiments have been described above, these embodiments are presented only as examples and are not intended to limit the scope of the invention. The novel system described in this specification can be embodied in various other forms. Furthermore, various omissions, substitutions, and modifications can be made to the system forms described in this specification without departing from the spirit of the invention. The appended claims and their equivalents are intended to cover such forms and modifications that fall within the scope and spirit of the invention. [Explanation of symbols]

[0107] 1: Heat storage tank, 2: Electric heater, 3: First blower, 4: Second blower, 5: Air, 6: Water, 7: Steam, 8: Condensate pump, 9: Boiler, 10: steam turbine, 11: condenser, 12: valve, 13: valve, 14: Valve, 15: Valve, 16: Valve, 17: Valve, 18: Valve, 19: valve, 20: valve, 21: valve, 22: piping, 23: solid sensible heat storage material, 24: Temperature of solid sensible heat storage material, 25: Temperature required for heat dissipation operation, 26: thermocline, 27: first heat storage tank, 28: second heat storage tank, 29: Heat storage tank, 30: Heat storage tank, 31: Heat storage tank, 32: Air flow direction during heat storage operation, 33: Air flow direction during heat dissipation operation, 34: Piping, 35: Rock receiving part, 36: Piping, 37: Control part, 40: Group 1, 41: Group 2, 42: Group 3

Claims

1. a first heat storage tank containing a heat storage material, through which a fluid flows in a horizontal direction, and which stores and releases heat; a second heat storage tank connected in series to the first heat storage tank, containing a heat storage material, through which the fluid flows in a vertical direction, and storing and releasing heat; During the heat storage operation, the fluid flowing out of the first heat storage tank flows into the second heat storage tank, and the second heat storage tank allows the fluid to flow from the upper side to the lower side in the vertical direction, During the heat dissipation operation, the fluid flowing out of the second heat storage tank flows into the first heat storage tank, and the second heat storage tank allows the fluid to flow from the lower side to the upper side in the vertical direction. Heat storage system.

2. the thermal storage system includes a plurality of thermal storage tanks including the first and second thermal storage tanks; The heat storage system according to claim 1 , wherein the second heat storage tank is the most downstream heat storage tank among the plurality of heat storage tanks during a heat storage operation.

3. the plurality of heat storage tanks includes an Nth heat storage tank (N is an integer of 3 or more) different from the first and second heat storage tanks, the Nth heat storage tank is connected in series with the first and second heat storage tanks, contains a heat storage material, and causes the fluid to circulate in a horizontal direction to store and release heat; The thermal storage system according to claim 2 .

4. 2. The thermal storage system according to claim 1, wherein the volume of the thermal storage material contained in the second thermal storage tank is smaller than the volume of the thermal storage material contained in the first thermal storage tank.

5. The thermal storage system according to claim 1 , wherein the second thermal storage tank is provided with a pipe for circulating the fluid on a side surface of a lower portion thereof.

6. The heat storage system according to claim 5 , wherein the second heat storage tank has therein a rock receiving component for preventing rocks contained in the heat storage material from falling.

7. The heat storage system according to claim 6 , wherein the piping is provided below a position where the rock receiving component is provided.

8. The heat storage system according to claim 1 , wherein a valve is provided at an inlet and an outlet of the first heat storage tank and the second heat storage tank, the valve opening and closing to control the flow of the fluid.

9. The heat storage system according to claim 8 , further comprising a control unit that controls opening and closing of the valve.

10. a plurality of first heat storage tanks each containing a heat storage material, allowing a fluid to circulate in a horizontal direction, and storing and releasing heat, the plurality of first heat storage tanks being included in any of first to K-th groups (K is an integer of 2 or more) connected in parallel with one another; a plurality of second heat storage tanks each containing a heat storage material, allowing the fluid to circulate in a vertical direction, and storing and releasing heat, each of the plurality of second heat storage tanks being included in one of the first to Kth groups and connected in series with a first heat storage tank of the same group; During the heat storage operation, the fluid flowing out of the first heat storage tank in each group flows into the second heat storage tank, and the second heat storage tank allows the fluid to flow from the upper side to the lower side in the vertical direction, During the heat dissipation operation, the fluid flowing out of the second heat storage tank in each group flows into the first heat storage tank, and the second heat storage tank allows the fluid to flow from the lower side to the upper side in the vertical direction. Heat storage system.

11. each of the first to K-th groups includes a plurality of heat storage tanks including the first and second heat storage tanks; The heat storage system according to claim 10 , wherein the second heat storage tank in each group is the most downstream heat storage tank among the plurality of heat storage tanks in each group during a heat storage operation.

12. the plurality of heat storage tanks in each group include an Nth heat storage tank (N is an integer of 3 or more) different from the first and second heat storage tanks, The Nth heat storage tank in each group is connected in series with the first and second heat storage tanks in the same group, contains a heat storage material, and causes the fluid to circulate in a horizontal direction to store and release heat. The thermal storage system according to claim 11.

13. a plurality of first heat storage tanks connected in parallel to each other, each containing a heat storage material, through which a fluid flows in a horizontal direction, and storing and releasing heat; one or more second heat storage tanks that contain a heat storage material, allow the fluid to circulate in a vertical direction, and store and release heat, the number of the one or more second heat storage tanks being less than the number of the plurality of first heat storage tanks, and each of the one or more second heat storage tanks being connected in series with the plurality of first heat storage tanks that are connected in parallel with each other; During the heat storage operation, the fluid flowing out of the plurality of first heat storage tanks flows into the one or more second heat storage tanks, and the one or more second heat storage tanks allow the fluid to circulate from the upper side to the lower side in the vertical direction, During the heat dissipation operation, the fluid flowing out of the one or more second heat storage tanks flows into the plurality of first heat storage tanks, and the one or more second heat storage tanks allow the fluid to flow from the lower side to the upper side in the vertical direction. Heat storage system.

14. the thermal storage system includes a plurality of thermal storage tanks including the plurality of first thermal storage tanks and the one or more second thermal storage tanks; The heat storage system according to claim 13 , wherein the one or more second heat storage tanks are the most downstream heat storage tanks among the plurality of heat storage tanks during a heat storage operation.

15. the plurality of heat storage tanks include a plurality of Nth heat storage tanks (N is an integer of 3 or more) different from the first and second heat storage tanks, the plurality of Nth heat storage tanks are connected in series with the plurality of first heat storage tanks, respectively, and are also connected in series with the one or more second heat storage tanks, contain a heat storage material, and cause the fluid to circulate in a horizontal direction to store and release heat; The thermal storage system according to claim 14.

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