Thermal storage system and thermal storage method

Abstract

To provide a thermal storage system and a thermal storage method in which, even after being left for a long period following thermal storage operation, the system still has a heat release temperature at the start of heat release operation higher or equal to the temperature required for the heat release operation.SOLUTION: A thermal storage system according to the present embodiment is a thermal storage system that uses a thermal storage tank in which, during thermal storage operation, a heat medium heated by a high-temperature heat source is circulated to store heat in a solid sensible heat storage material and, during heat release operation, the heat medium at a low temperature is circulated in the direction opposite to that in the thermal storage operation to release heat from the solid sensible heat storage material. The thermal storage operation time is divided into two periods, namely, an earlier period and a later period, such that the flow rate of the heat medium during the later period is less than the flow rate of the heat medium during the earlier period.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE An embodiment of the present invention relates to a heat storage system and a heat storage method. [Background technology]

[0002] In recent years, power generation from natural energy sources such as solar power generation and wind power generation has been increasing, and there are regions where the amount of power generation is greater than the power demand depending on the season and time of day. In addition, there are times when the power demand is high depending on the season and time of day, and the amount of power generation is less than the power demand, resulting in a power shortage. In view of this, there is a conventional technology (see Patent Document 1) that uses heat storage to adjust power, which will be described with reference to Figs. 8 and 9.

[0003] FIG. 8 is a diagram showing a configuration example of a power adjustment system 100 including a thermal storage system 200. The power adjustment system 100 is a system capable of storing heat in the thermal storage system 200 and generating power using heat dissipated from the thermal storage system 200. The thermal storage system 200 includes a thermal storage tank 1, an electric heater 2, a first fan 3, a second fan 4, valves 12 to 15, and a boiler 9 to which heat is supplied. The power adjustment system 100 includes a condensate pump 8, a steam turbine 10, a generator 10a, a condenser 11, and the thermal storage system 200. When there is a surplus of power, the power adjustment system 100 stops the condensate pump 8, the steam turbine 10, and the generator 10a. The heat storage system 200 included in the power adjustment system 100 stops the second blower 4, opens the valves 12 and 13, and closes the valves 14 and 15, and operates the electric heater 2 and the first blower 3 using the surplus power. At this time, the first blower 3 circulates air 5 between the electric heater 2 and the heat storage tank 1. The air 5 is heated by the heat generated by the electric heater 2, transports the heat to the heat storage tank 1, and heats the heat storage material in the heat storage tank 1. The heat storage material is a solid sensible heat storage material 23, such as rocks. This causes heat to be stored. The heat storage tank 1 is often arranged horizontally with a long object in the flow direction. The solid arrow indicates the air flow direction 32 during heat storage operation, and the dotted arrow indicates the air flow direction 33 during heat dissipation operation.

[0004] When there is no surplus power, the power conditioning system 100 including the thermal storage system 200 stops the electric heater 2 and the first fan 3, closes the valves 12 and 13, opens the valves 14 and 15, and operates the condensate pump 8 and the second fan 4. The second fan 4 circulates the air 5 between the thermal storage tank 1 and the boiler 9. The air 5 is heated by the thermal storage material in the thermal storage tank 1 and transports the heat to the boiler 9. In the boiler 9, the water 43 carried in by the condensate pump 8 is heated by the heat from the air 5 to produce steam 7, and the air 5 is cooled and discharged. In this way, the heat dissipation operation is performed. The steam 7 flows through the steam turbine 10 at a low temperature and low pressure, rotating the steam turbine 10, which is an impeller, and the generator 10a mechanically connected to the steam turbine 10 generates electricity. The steam discharged from the steam turbine 10 is cooled by cooling water, for example seawater, in the condenser 11 to become water 43 and circulate. As a result, steam 7 is generated using the heat stored in the heat storage material in the heat storage tank 1, and electricity is generated. In this way, power adjustment is performed by using electricity when there is a power surplus and generating electricity when there is no power surplus.

[0005] Between the end of the heat storage operation and the start of the heat dissipation operation, the heat storage tank 1 is left standing with the valves 12, 13, 14, and 15 closed. During this long period of time, heat leaks from the heat storage tank 1. Figure 9 is a diagram showing the temperature distribution in the heat storage tank 1 according to the prior art.

[0006] FIG. 9 shows the temperature distribution at the end of the heat storage operation and after being left for a long time after the heat storage operation. The horizontal axis indicates the position in the heat storage tank 1, and the left end of the graph is the heat storage tank inlet during heat storage operation (heat storage tank outlet during heat dissipation operation). The vertical axis indicates the temperature of the solid sensible heat storage material 23, and the temperature of the air 5 nearby is almost the same. The temperature at the end of heat storage is the first temperature 16, which is a constant temperature that is somewhat higher than the heat dissipation operation required temperature 21, which is the temperature required for the heat utilization destination such as the boiler 9 during heat dissipation operation. The temperature after being left for a long time is the second temperature 17, and the vicinity of the inlet during heat storage operation is cooled from the inlet side pipe L4 and the temperature is reduced. The flow direction of the air 5 during heat dissipation operation is the opposite direction to that during heat storage operation, and the outlet during heat dissipation operation is the inlet during heat storage operation, so the temperature of the air 5 flowing out of the heat storage tank 1 at the start of heat dissipation becomes the temperature of the solid sensible heat storage material 23 near the inlet during heat storage operation. Therefore, the heat radiation temperature at the start of heat radiation operation may be lower than the heat radiation operation required temperature 21.

[0007] Therefore, we want to ensure that the heat dissipation temperature at the start of heat dissipation operation does not fall below the heat dissipation operation required temperature 21.

[0008] In the heat storage system 200 according to the conventional technology, the heat radiated from the heat storage system 200 is used as a heat source for the steam turbine 10, but the present invention is not limited to this. For example, the heat radiated from the heat storage system 200 may be used for air conditioning or other purposes. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent Publication No. 2021-1597 Summary of the Invention [Problem to be solved by the invention]

[0010] There is a problem in that the heat dissipation temperature at the start of heat dissipation operation after being left unused for a long period of time following the heat storage operation must not fall below the temperature required for the heat dissipation operation.

[0011] The problem to be solved by the present invention is to provide a heat storage system and a heat storage method in which the heat dissipation temperature at the start of heat dissipation operation after being left unused for a long period of time after the heat storage operation does not fall below the temperature required for the heat dissipation operation. [Means for solving the problem]

[0012] The heat storage system of this embodiment is a heat storage system that uses a heat storage tank in which a heat medium heated by a high-temperature heat source is circulated during heat storage operation to store heat in a solid sensible heat storage material, and in which low-temperature heat medium is circulated in the opposite direction to that during heat storage operation to dissipate heat from the solid sensible heat storage material during heat dissipation operation, and the heat storage operation time is divided into two, a front side and a rear side, and the flow rate of the heat medium during the rear side time is reduced compared to the flow rate of the heat medium during the front side time. Effect of the Invention

[0013] According to this embodiment, it is possible to provide a heat storage system and a heat storage method in which the heat dissipation temperature at the start of heat dissipation operation after being left unused for a long period of time after the heat storage operation does not fall below the temperature required for the heat dissipation operation. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a diagram showing the direction of air flow in the heat storage tank 1 according to the first embodiment. [Diagram 2] FIG. 4 is a diagram showing a temperature distribution in the heat storage tank 1 according to the first and second embodiments. [Diagram 3] FIG. 11 is a diagram showing the temperature distribution in the heat storage tank 1 according to the third and fourth embodiments. [Figure 4] FIG. 11 is a diagram showing the temperature distribution in the heat storage tank 1 according to the fifth and sixth embodiments. [Diagram 5] FIG. 13 is a diagram showing the temperature distribution in the heat storage tank 1 according to the seventh and eighth embodiments. [Figure 6] FIG. 13 is a diagram showing the temperature distribution in the heat storage tank 1 according to the ninth and tenth embodiments. [Figure 7] FIG. 19 is a diagram showing a configuration example of a heat storage system according to an eleventh embodiment. [Figure 8] FIG. 1 is a diagram showing an example of the configuration of a power adjustment system including a heat storage system. [Figure 9] FIG. 1 is a diagram showing a temperature distribution in a heat storage tank 1 of a heat storage system according to a conventional technique. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] (First embodiment) A heat storage system 200 according to a first embodiment corresponding to claims 1 and 11 will be described with reference to Figs. 1, 2 and 8. Note that the same parts as those in the heat storage system 200 according to the prior art may be denoted by the same numbers and the description thereof may be omitted. As shown in Fig. 1, the heat storage system 200 according to this embodiment is used as a heat source for air conditioning, a heat source for a steam turbine 10, etc.

[0016] FIG. 1 is a diagram showing the air flow direction in a heat storage tank 1 according to the first embodiment. The heat storage tank 1 contains a heat storage material. The heat storage material is a solid sensible heat storage material 23, such as rock. A solid arrow indicates a flow direction 32 of air 5 during heat storage operation, and a dotted arrow indicates a flow direction 33 of air 5 during heat dissipation operation. A heat storage system 200 according to this embodiment includes, for example, the heat storage tank 1, an electric heater 2, a first fan 3, a second fan 4, valves 12 to 15, and a boiler 9 to which heat is supplied.

[0017] The flow of air 5 is the same as in the conventional technology, and will be described with reference to FIG. 8. During heat storage operation, the second blower 4 is stopped. Then, valves 12 and 13 are opened, and valves 14 and 15 are closed to operate the electric heater 2 and the first blower 3 using surplus power. At this time, the first blower 3 circulates air 5 between the electric heater 2 and the heat storage tank 1 through pipes L3, L4, and L5. The air 5 is heated by the heat generated by the electric heater 2, and transports the heat to the heat storage tank 1, where it heats the heat storage material in the heat storage tank 1. This causes heat to be stored in the heat storage material.

[0018] FIG. 2 is a diagram showing the temperature distribution in the heat storage tank 1 according to the first embodiment. As in FIG. 9, the horizontal axis indicates the position in the heat storage tank 1, and the vertical axis indicates the temperature. In the heat storage system 200 according to this embodiment, the heat storage operation time is divided into two parts, a front part and a rear part, and the flow rate of the air 5 in the rear part is reduced compared to the flow rate of the air 5 in the front part. For example, the flow rate of the air 5 is reduced by lowering the output of the first blower 3 (see FIG. 8) that transports the air 5, or by reducing the opening degree of at least one of the valves 12 and 13 (see FIG. 8) installed in the flow path of the air 5. At this time, the amount of heat from the electric heater 2 to the air 5 is the same.

[0019] In the front part of the time, the temperature profile is like the first temperature 16 (see FIG. 9), and the air 5 that has passed through the area where the first temperature 16 is heated by the solid sensible heat storage material 23 that exists downstream of that area. In the back part of the time, the amount of heat from the electric heater 2 to the air 5 remains the same, and the flow rate of the air 5 is reduced, so the temperature of the air 5 becomes higher and flows into the heat storage tank 1. Therefore, the solid sensible heat storage material 23 near the inlet is heated by the inflowing air 5 that is at a higher temperature. The temperature is added, resulting in a higher temperature state, and at the end of the heat storage operation, the temperature becomes the third temperature 19 in FIG. 2. At the third temperature 19, a thermocline exists between the area where the temperature is higher and the area where the temperature remains the same as in the front part of the time. When comparing the temperature profile shown in FIG. 9, which is the conventional technology, with the temperature profile according to the present embodiment shown in FIG. 2, the third temperature 19 according to the present embodiment has the temperature added near the inlet, resulting in a higher temperature state.

[0020] The temperature after being left for a long time becomes the fourth temperature 20. The third temperature 19 near the inlet during heat storage operation is cooled from the inlet side pipe L4 and the temperature drops. However, when comparing the temperature profile shown in Fig. 9 according to the conventional technology with the temperature profile according to this embodiment shown in Fig. 2, the fourth temperature 20 according to this embodiment is an added temperature, so even if the temperature drops, it does not become lower than the heat dissipation operation required temperature 21 like the second temperature 17 (see Fig. 9) according to the conventional technology.

[0021] The flow direction 33 of air 5 during heat radiation operation (see FIG. 1) is the opposite direction to that during heat storage operation, and the outlet during heat radiation operation is the inlet during heat storage operation, so the temperature of air 5 flowing out of heat storage tank 1 at the start of heat radiation operation becomes the temperature of solid sensible heat storage material 23 near the inlet during heat storage operation, but the heat radiation temperature at the start of heat radiation operation does not become lower than the heat radiation operation required temperature 21. Therefore, the temperature at the start of heat radiation is maintained at or above the heat radiation operation required temperature 21.

[0022] The start time of the latter period can be determined by counting backwards from the predicted end time of the heat storage operation, so this may be done, or a temperature sensor may be installed near the outlet of the heat storage tank 1, and the start time may be the time when the temperature reaches a predetermined temperature. If a time is secured for the temperature after being left for a long time to reach or exceed the temperature required for heat dissipation operation 21, such as the fourth temperature 20, the latter period may be short. In addition, the first blower 3 and the valves 12 and 13 may be controlled manually by an operator, or automatically using information from a sensor or a timer.

[0023] Although the high-temperature heat source fluid (heat medium) is air, it does not have to be air, and it may be liquid instead of gas. Also, the heat medium is heated by the electric heater 2, but it may be heated by heat recovered from the combustion exhaust gas. Also, in the heat storage system 200 according to this embodiment, the heat radiated from the heat storage system 200 is used as a heat source for the steam turbine 10, but this is not limiting. For example, the heat radiated from the heat storage system 200 may be used for air conditioning or other purposes.

[0024] As described above, according to this embodiment, the heat storage operation time of the heat storage tank 1 is divided into two parts, the front side and the rear side, and the flow rate of the air 5 in the rear side is reduced compared to the flow rate of the air 5 in the front side. Since the amount of heat from the electric heater 2 to the air 5 remains the same, this makes it possible to make the temperature of the air 5 (heat medium) in the rear side higher than the temperature of the air 5 (heat medium) in the front side. Therefore, the third temperature 19 at the end of the heat storage operation can be made higher by adding the temperature near the inlet of the heat storage tank 1. In this way, since the fourth temperature 20 after being left for a long time after the heat storage operation is added, even if the temperature drops, it can be prevented from falling below the heat dissipation operation necessary temperature 21.

[0025] Second embodiment The heat storage system 200 according to the first embodiment adjusts the temperature of the air 5 by the flow rate of the air 5, which is a heat medium, whereas the heat storage system 200 according to the second embodiment adjusts the temperature of the air 5 by increasing or decreasing the output of the electric heater 2, etc., thereby increasing or decreasing the amount of heat applied to the air 5. This is different from the heat storage system 200 according to the first embodiment in that the following describes the differences from the heat storage system 200 according to the first embodiment.

[0026] A second embodiment corresponding to claims 2 and 12 will be described with reference to Figs. 1 and 2. Note that the description of the parts that are the same as the heat storage system 200 according to the conventional technology and the heat storage system 200 according to the first embodiment may be omitted.

[0027] The heat storage operation time is divided into two, a front half and a rear half, and the amount of heat applied to the heat medium during the rear half is increased compared to the amount of heat applied to the heat medium during the front half. The heat medium is, for example, air 5, and the air 5 may be heated by an electric heater 2 (see FIG. 8) or by heat recovered from the combustion exhaust gas. The output of the electric heater 2 can be easily increased or decreased. At this time, the flow rate of the air 5 is kept the same.

[0028] In the front part of the time, the temperature profile is like the first temperature 16 (see FIG. 9), and the air 5 that passes through the area where the first temperature 16 is present heats the solid sensible heat storage material 23 that exists downstream of that area. In the back part of the time, the flow rate of the air 5 remains the same, but the amount of heat applied to the air 5 increases, so the temperature of the air 5 becomes higher and flows into the heat storage tank 1. Therefore, the solid sensible heat storage material 23 near the inlet is heated by the inflowing air 5 that is at a higher temperature. The temperature is added, resulting in a higher temperature state, and at the end of the heat storage operation, the temperature becomes the third temperature 19 in FIG. 2. At the third temperature 19, a thermocline exists between the area where the temperature is higher and the area where the temperature remains the same as in the front part of the time. Comparing the temperature profile in FIG. 9 according to the conventional technology and the temperature profile in FIG. 2 according to the second embodiment, the third temperature 19 according to the second embodiment has the temperature added near the inlet, resulting in a higher temperature state.

[0029] The temperature after being left for a long time becomes the fourth temperature 20. The third temperature 19 near the inlet during heat storage operation is cooled from the inlet side pipe L4 and the temperature drops. However, when comparing the temperature profile shown in Fig. 9, which is the conventional technology, with the temperature profile according to this embodiment shown in Fig. 2, the fourth temperature 20 according to this embodiment is an added temperature, so even if the temperature drops, it does not become lower than the heat dissipation operation required temperature 21 like the second temperature 17 (see Fig. 9) according to the conventional technology.

[0030] The flow direction 33 of air 5 during heat radiation operation (see FIG. 1) is the opposite direction to that during heat storage operation, and the outlet during heat radiation operation is the inlet during heat storage operation, so the temperature of air 5 flowing out of heat storage tank 1 at the start of heat radiation operation becomes the temperature of solid sensible heat storage material 23 near the inlet during heat storage operation, but the heat radiation temperature at the start of heat radiation operation does not become lower than the heat radiation operation required temperature 21. Therefore, the temperature at the start of heat radiation is maintained at or above the heat radiation operation required temperature 21.

[0031] The start time of the latter period can be determined by counting backwards from the predicted end time of the heat storage operation, so this may be done, or a temperature sensor may be installed near the outlet of the heat storage tank 1, and the start time may be the time when the temperature reaches a predetermined temperature. If it is possible to ensure that the temperature after being left unused for a long period of time reaches or exceeds the temperature required for heat dissipation operation 21, such as the fourth temperature 20, the latter period may be short. In addition, the device that heats the air 5 (for example, the electric heater 2) may be controlled manually by an operator, or automatically using information from a sensor or a timer.

[0032] Although the high-temperature heat source fluid (heat medium) is air, it does not have to be air, and it may be liquid instead of gas. In addition, in the heat storage system 200 according to the present embodiment, the heat dissipated from the heat storage system 200 is used as a heat source for the steam turbine 10, but this is not limiting. For example, the heat dissipated from the heat storage system 200 may be used for air conditioning or other purposes.

[0033] As described above, according to this embodiment, the heat storage operation time of the heat storage tank 1 is divided into two parts, the front side and the rear side, and the output of the electric heater 2 in the rear side is increased compared to the output of the electric heater 2 in the front side. That is, the amount of heat applied to the heat medium is increased. Since the flow rate of the air 5 remains the same, this makes it possible to make the temperature of the air 5 (heat medium) in the rear side higher than the temperature of the air 5 (heat medium) in the front side. Therefore, the third temperature 19 at the end of the heat storage operation can be made higher by adding the temperature near the inlet of the heat storage tank 1. In this way, since the fourth temperature 20 after being left for a long time after the thermal operation is added, even if the temperature drops, it can be prevented from falling below the heat dissipation operation necessary temperature 21.

[0034] Third embodiment The heat storage system 200 according to the third embodiment differs from the heat storage system 200 according to the first embodiment in that the action of reducing the flow rate of the air 5 is performed in multiple steps. The third embodiment corresponding to claim 3 will be described with reference to Fig. 3. Descriptions of parts that are the same as the heat storage system 200 according to the conventional technology and the heat storage system 200 according to the first and second embodiments may be omitted.

[0035] FIG. 3 is a diagram showing the temperature distribution in the heat storage tank 1 according to the third embodiment. The horizontal axis indicates the position in the heat storage tank 1, and the vertical axis indicates the temperature. In the heat storage system 200 according to the first embodiment, the heat storage operation time is divided into two parts, a front part and a rear part, and the flow rate of the air 5 during the rear part is reduced compared to the flow rate of the air 5 during the front part while the amount of heat applied to the air 5 remains the same. In the heat storage system 200 according to the third embodiment, this action of reducing the flow rate is carried out in multiple parts. In FIG. 3, it is divided into two parts, but it may be divided into any number of parts.

[0036] As shown in Fig. 3, the temperature increases each time the flow rate of air 5 decreases, so the temperature is added in two stages, and the temperature increases stepwise until the temperature reaches a fifth temperature 24 at the end of the heat storage operation. At the fifth temperature 24, there are two thermoclines between the higher temperature region and the region where the temperature remains the same as it was at the previous time.

[0037] The temperature after being left for a long time becomes the sixth temperature 25. The sixth temperature 25 is cooled from the inlet side pipe L4 (see FIG. 1) near the inlet of the heat storage tank 1 during the heat storage operation, and the temperature is reduced. However, similar to the heat storage system 200 according to the first embodiment, when comparing the temperature profile of FIG. 9 according to the conventional technology with that of FIG. 3 according to the third embodiment, the sixth temperature 25 according to the third embodiment is an added temperature, so even if the temperature is reduced, it is not lower than the heat dissipation operation required temperature 21 like the second temperature 17 (see FIG. 9) according to the conventional technology. In addition, compared with the fourth temperature 20 (see FIG. 2) according to the first embodiment, the temperature profile is closer to a constant temperature state.

[0038] The flow direction of air 5 during heat radiation operation is the opposite direction to that during heat storage operation, and the outlet during heat radiation operation is the inlet during heat storage operation, so the temperature of air 5 flowing out of heat storage tank 1 at the start of heat radiation operation becomes the temperature of solid sensible heat storage material 23 near the inlet during heat storage operation, but as in the first embodiment, the heat radiation temperature at the start of heat radiation operation does not become less than the heat radiation operation required temperature 21. Therefore, the temperature at the start of heat radiation is kept at or above the required temperature. In addition, compared to the first embodiment, the temperature after being left for a long time becomes smoother and approaches a constant value, which has the effect of making it easier to control the heat radiation operation that supplies heat.

[0039] The start time of the latter period and the time to reduce the flow rate in multiple stages can be determined by calculating backwards from the predicted end time of the heat storage operation, so this may be done, or a temperature sensor may be installed near the outlet of the heat storage tank 1, and the time when the temperature reaches each of several predetermined temperatures may be used. The latter period may be short as long as it is possible to ensure that the temperature after a long period of time becomes equal to or higher than the heat dissipation operation required temperature 21, such as the sixth temperature 25. The first blower 3 and the valves 12 and 13 may be controlled manually by an operator, or automatically using information from a sensor or a timer.

[0040] Although the high-temperature heat source fluid (heat medium) is air, it does not have to be air, and it may be liquid instead of gas. Also, the heat medium is heated by the electric heater 2, but it may be heated by heat recovered from the combustion exhaust gas. Also, in the heat storage system 200 according to this embodiment, the heat radiated from the heat storage system 200 is used as a heat source for the steam turbine 10, but this is not limiting. For example, the heat radiated from the heat storage system 200 may be used for air conditioning or other purposes.

[0041] As described above, according to this embodiment, the flow rate of air 5 is reduced in multiple steps. As a result, the temperature increases each time the flow rate of air 5 decreases, and the temperature is added in multiple stages, making it possible to achieve a higher temperature in a more stepwise manner. As a result, the heat dissipation temperature at the start of heat dissipation operation after being left unused for a long period of time does not fall below the heat dissipation operation required temperature 21, and the temperature on the inlet side of the heat storage tank 1 at the sixth temperature 25 after being left unused for a long period of time can be made to approach a constant value more smoothly. This makes it easier to control the heat dissipation operation that supplies heat.

[0042] (Fourth embodiment) The heat storage system 200 according to the fourth embodiment differs from the heat storage system 200 according to the second embodiment in that the amount of heat to be applied to the air 5 is increased in stages. The fourth embodiment corresponding to claim 4 will be described with reference to Fig. 3. Descriptions of parts that are the same as the heat storage system 200 according to the conventional technology and the heat storage systems 200 according to the first to third embodiments may be omitted.

[0043] In the heat storage system 200 according to the second embodiment, the heat storage operation time is divided into two parts, a front part and a rear part, and the amount of heat applied to the heat medium in the rear part is increased compared to the amount of heat applied to the heat medium in the front part while keeping the flow rate of the air 5 the same. The heat medium is, for example, air 5, and the air 5 may be heated by an electric heater 2 (see FIG. 8) or by heat recovered from the combustion exhaust gas. The output of the electric heater 2 can be easily increased or decreased. In the heat storage system 200 according to the fourth embodiment, the action of increasing the amount of heat is carried out in multiple parts. In FIG. 3, it is divided into two parts, but it may be divided into any number of parts.

[0044] As the heating amount increases, the temperature rises, so there are two stages of temperature build-up, and the temperature gradually increases until the end of the heat storage operation is at the fifth temperature 24 in Figure 3. At the fifth temperature 24, there are two thermoclines between the higher temperature region and the region where the temperature remains the same as it was at the previous time.

[0045] The temperature after being left for a long time becomes the sixth temperature 25. The sixth temperature 25 is cooled from the inlet side pipe L4 near the inlet during the heat storage operation, and the temperature is reduced. However, as in Example 2, when comparing the temperature profile of FIG. 9 according to the conventional technology with that of FIG. 3 according to the fourth embodiment, the sixth temperature 25 according to the fourth embodiment is an added temperature, so even if the temperature is reduced, it is not lower than the heat dissipation operation required temperature 21 like the second temperature 17 (see FIG. 9) according to the conventional technology. Moreover, compared with the fourth temperature 20 according to the second embodiment, the temperature profile is closer to a constant temperature state.

[0046] The flow direction of air 5 during heat radiation operation is the opposite direction to that during heat storage operation, and the outlet during heat radiation operation is the inlet during heat storage operation, so the temperature of air 5 flowing out of heat storage tank 1 at the start of heat radiation operation becomes the temperature of solid sensible heat storage material 23 near the inlet during heat storage operation, but as in the second embodiment, the heat radiation temperature at the start of heat radiation operation does not become less than the heat radiation operation required temperature 21. Therefore, the temperature at the start of heat radiation is kept at or above the required temperature. In addition, compared to the second embodiment, the temperature after a long period of time is smoother and approaches a constant value, which has the effect of making it easier to control the heat radiation operation that supplies heat.

[0047] The start time of the latter period and the times at which the heating amount is increased in multiple increments can be determined by calculating backwards from the predicted end time of the heat storage operation, so this may be done, or a temperature sensor may be installed near the outlet of the heat storage tank 1, and the times may be determined by the times at which the temperature reaches several predetermined temperatures. If it is possible to ensure that the temperature after being left for a long period of time reaches or exceeds the heat dissipation operation required temperature 21, such as the sixth temperature 25, the latter period may be short. In addition, the device that heats the air 5 (electric heater 2 in FIG. 3) may be controlled manually by an operator, or automatically using information from a sensor or timer.

[0048] Although the high-temperature heat source fluid (heat medium) is air, it does not have to be air, and it may be liquid instead of gas. In addition, in the heat storage system 200 according to the present embodiment, the heat dissipated from the heat storage system 200 is used as a heat source for the steam turbine 10, but this is not limiting. For example, the heat dissipated from the heat storage system 200 may be used for air conditioning or other purposes.

[0049] As described above, according to this embodiment, the action of heating the air 5 is performed in multiple steps. As a result, the temperature of the air 5 increases stepwise, and the temperature is added in multiple steps, making it possible to achieve a higher temperature in a more stepwise manner. As a result, the heat dissipation temperature at the start of the heat dissipation operation after being left unused for a long time does not fall below the heat dissipation operation required temperature 21, and the temperature on the inlet side of the heat storage tank 1 at the sixth temperature 25 after being left unused for a long time can be made to approach a constant value more smoothly. This makes it easier to control the heat dissipation operation that supplies heat.

[0050] Fifth embodiment The heat storage system 200 according to the fifth embodiment differs from the heat storage system 200 according to the third embodiment in that the flow rate of the air 5 is continuously reduced over time. The fifth embodiment corresponding to claim 5 will be described with reference to Fig. 4. Descriptions of parts that are the same as the heat storage system 200 according to the conventional technology and the heat storage systems 200 according to the first to fourth embodiments may be omitted.

[0051] In the heat storage system 200 according to the first embodiment, the heat storage operation time is divided into two, a front side and a rear side, and the flow rate of the air 5 in the rear side is reduced compared to the flow rate of the air 5 in the front side while the amount of heat from the electric heater 2 to the air 5 remains the same, while in the heat storage system 200 according to the third embodiment, this flow rate reduction is performed in multiple steps. In the heat storage system 200 according to the fifth embodiment, the flow rate of the air 5 is reduced gradually, that is, continuously with respect to time, rather than in stages.

[0052] Fig. 4 is a diagram showing the temperature distribution in the heat storage tank 1 according to the fifth embodiment. The horizontal axis indicates the position in the heat storage tank 1, and the vertical axis indicates the temperature. As shown in Fig. 4, the temperature gradually increases as the flow rate gradually decreases, so that the temperature is added continuously rather than stepwise, and the seventh temperature 26 is reached at the end of the heat storage operation. At the seventh temperature 26, there is no thermocline between the higher temperature region and the region where the temperature remains the same as at the previous time.

[0053] The temperature after being left for a long time becomes the eighth temperature 27. The eighth temperature 27 is cooled from the inlet side pipe L4 (see FIG. 1) near the inlet during the heat storage operation, and the temperature is reduced. However, as in the first and third embodiments, when comparing the temperature profile of FIG. 9 of the conventional technology with that of FIG. 4 of the fifth embodiment, the eighth temperature 27 of the fifth embodiment is added with the temperature, so even if the temperature is reduced, it is not lower than the heat dissipation operation necessary temperature 21 like the second temperature 17 (see FIG. 9) of the conventional technology. Moreover, compared with the fourth temperature 20 (see FIG. 2) of the first embodiment and the sixth temperature 25 (see FIG. 3) of the third embodiment, the temperature profile is closer to a constant temperature state.

[0054] The flow direction of air 5 during heat dissipation operation is the opposite direction to that during heat storage operation, and the outlet during heat dissipation operation is the inlet during heat storage operation, so the temperature of air 5 at the start of heat dissipation operation is the temperature of solid sensible heat storage material 23 near the inlet during heat storage operation, but similar to the first and third embodiments, the heat dissipation temperature at the start of heat dissipation operation does not become less than the heat dissipation operation required temperature 21. Therefore, the temperature at the start of heat dissipation is kept at or above the required temperature. In addition, the temperature after being left standing becomes smoother and approaches a constant value more easily than in the first and third embodiments, which has the effect of making it easier to control the heat dissipation operation that supplies heat.

[0055] In this way, the technology according to claim 5 allows the temperature profile at the end of the heat storage operation to be freely created. This allows the temperature profile at the start of the heat dissipation operation to be freely created. The technology according to claim 5 has the effect of allowing the creation of a temperature profile that makes it easy to control the heat dissipation operation.

[0056] The start time of the latter period can be determined by counting backwards from the predicted end time of the heat storage operation, so this may be done, or a temperature sensor may be installed near the outlet of the heat storage tank 1, and the start time may be the time when the temperature reaches several predetermined temperatures. If it is possible to ensure that the temperature after a long period of time becomes equal to or higher than the heat dissipation operation required temperature 21, such as the eighth temperature 27, the latter period may be short. In addition, the first blower 3 and the valves 12 and 13 may be controlled manually by an operator, or automatically using information from a sensor or a timer.

[0057] Although the high-temperature heat source fluid (heat medium) is air, it does not have to be air, and it may be liquid instead of gas. Also, the heat medium is heated by the electric heater 2, but it may be heated by heat recovered from the combustion exhaust gas. Also, in the heat storage system 200 according to this embodiment, the heat radiated from the heat storage system 200 is used as a heat source for the steam turbine 10, but this is not limiting. For example, the heat radiated from the heat storage system 200 may be used for air conditioning or other purposes.

[0058] As described above, according to this embodiment, the flow rate of the air 5 is continuously reduced with respect to time. As a result, the temperature increases each time the flow rate of the air 5 decreases, so the temperature is continuously added, and it is possible to continuously achieve a high temperature state. Therefore, by controlling the flow rate of the air 5 according to the purpose, it is possible to freely create a temperature profile in the heat storage tank 1 at the end of the heat storage operation. As a result, the heat release temperature at the start of the heat release operation after a long period of time of leaving does not become lower than the heat release operation required temperature 21, and it is possible to freely create a temperature profile on the inlet side (during heat storage) of the heat storage tank 1 at the eighth temperature 27 after a long period of time of leaving, that is, at the start of the heat release operation. Therefore, it is possible to more easily control the heat release operation in which heat is supplied.

[0059] Sixth embodiment The heat storage system 200 according to the sixth embodiment differs from the heat storage system 200 according to the fourth embodiment in that the amount of heat applied to the air 5 is continuously increased over time. The sixth embodiment corresponding to claim 6 will be described with reference to Fig. 4. Descriptions of parts that are the same as the heat storage system 200 according to the conventional technology and the heat storage systems 200 according to the first to fifth embodiments may be omitted.

[0060] In the heat storage system 200 according to the second embodiment, the heat storage operation time is divided into two parts, a front part and a rear part, and the amount of heat applied to the heat medium in the rear part is increased from the amount of heat applied to the heat medium in the front part while keeping the flow rate of the air 5 the same, while in the heat storage system 200 according to the fourth embodiment, the act of increasing the amount of heat is carried out in multiple parts. In the heat storage system 200 according to the sixth embodiment, the amount of heat is increased gradually, that is, continuously with respect to time, rather than in stages. The heat medium is air 5, and the air 5 may be heated by an electric heater 3 (see FIG. 8) or by heat recovered from the combustion exhaust gas. The output of the electric heater 3 can be easily increased or decreased.

[0061] Fig. 4 is a diagram showing the temperature distribution in the heat storage tank 1 according to the fifth embodiment. The horizontal axis indicates the position in the heat storage tank 1, and the vertical axis indicates the temperature. Since the temperature gradually increases in response to a gradually increasing amount of heating, the temperature is not increased stepwise but continuously, and the seventh temperature 26 in Fig. 4 is reached at the end of the heat storage operation. At the seventh temperature 26, there is no thermocline between the higher temperature region and the region where the temperature remains the same as at the previous time.

[0062] The temperature after being left for a long time becomes the eighth temperature 27. The eighth temperature 27 is cooled from the inlet side pipe L4 (see FIG. 1) near the inlet of the heat storage tank 1 during the heat storage operation, and the temperature is reduced. However, as in the second and fourth embodiments, when comparing the temperature profiles of FIG. 9 of the conventional technology and FIG. 7 of Example 6, the eighth temperature 27 according to the sixth embodiment is added with the temperature, so even if the temperature is reduced, it is not lower than the heat dissipation operation necessary temperature 21 like the second temperature according to the conventional technology. Moreover, compared with the fourth temperature 20 according to the second embodiment (see FIG. 2) and the sixth temperature 25 according to the fourth embodiment (see FIG. 3), the temperature profile is closer to a constant temperature state.

[0063] The flow direction of air 5 during heat radiation operation is the opposite direction to that during heat storage operation, and the outlet during heat radiation operation is the inlet during heat storage operation, so the temperature of air 5 at the start of heat radiation operation is the temperature of solid sensible heat storage material 23 near the inlet during heat storage operation, but similar to the second and fourth embodiments, the heat radiation temperature at the start of heat radiation operation does not become less than the heat radiation operation required temperature 21. Therefore, the temperature at the start of heat radiation is kept at or above the required temperature. In addition, compared to the second and fourth embodiments, the temperature after being left unused for a long time becomes smoother and approaches a constant value, which has the effect of making it easier to control the heat radiation operation that supplies heat.

[0064] In this way, the technology according to claims 5 and 6 allows the temperature profile at the end of the heat storage operation to be freely created. This allows the temperature profile at the start of the heat dissipation operation to be freely created. The technology according to claims 5 and 6 has the effect of allowing the creation of a temperature profile that makes it easy to control the heat dissipation operation.

[0065] The start time of the latter period can be determined by counting backwards from the predicted end time of the heat storage operation, so this may be done, or a temperature sensor may be installed near the outlet of the heat storage tank 1, and the start time may be the time when the temperature reaches several predetermined temperatures. If it is possible to ensure that the temperature after a long period of time becomes equal to or higher than the heat dissipation operation required temperature 21, such as the eighth temperature 27, the latter period may be short. In addition, the first blower 3 and the valves 12 and 13 may be controlled manually by an operator, or automatically using information from a sensor or a timer.

[0066] Although the high-temperature heat source fluid (heat medium) is air, it does not have to be air, and it may be liquid instead of gas. In addition, in the heat storage system 200 according to the present embodiment, the heat dissipated from the heat storage system 200 is used as a heat source for the steam turbine 10, but this is not limiting. For example, the heat dissipated from the heat storage system 200 may be used for air conditioning or other purposes.

[0067] As described above, according to this embodiment, the amount of heat applied to the air 5 is increased continuously with respect to time. This allows the temperature to be continuously increased, making it possible to achieve a higher temperature state more continuously. Therefore, by controlling the amount of heat applied to the air 5 according to the purpose, it is possible to freely create a temperature profile in the heat storage tank 1 at the end of the heat storage operation. This ensures that the heat release temperature at the start of the heat release operation after a long period of time of being left unused does not fall below the heat release operation required temperature 21, and it is possible to freely create a temperature profile on the inlet side (during heat storage) of the heat storage tank 1 at the eighth temperature 27 after a long period of time of being left unused, that is, at the start of the heat release operation. This makes it easier to control the heat release operation that supplies heat.

[0068] Seventh embodiment The heat storage system 200 according to the seventh embodiment differs from the heat storage system 200 according to the fifth embodiment in that the rate of change of the reduction in the flow rate of the air 5 is gradually changed. The seventh embodiment corresponding to claim 7 will be described with reference to Fig. 5. Descriptions of parts that are the same as the heat storage system 200 according to the conventional technology and the heat storage systems 200 according to the first to sixth embodiments may be omitted.

[0069] In the heat storage system 200 according to the first embodiment, the heat storage operation time is divided into two, a front side and a rear side, and the flow rate of the air 5 in the rear side time is reduced compared to the flow rate of the air 5 in the front side time while the amount of heat from the electric heater 2 to the air 5 remains the same, in the heat storage system 200 according to the third embodiment, the action of reducing this flow rate is carried out in multiple steps, and in the heat storage system 200 according to the fifth embodiment, the flow rate of the air 5 is reduced gradually, that is, continuously with respect to time, rather than in stages. In the heat storage system 200 according to the seventh embodiment, the rate of change of the reduction in the flow rate of the air 5 is gradually changed.

[0070] FIG. 5 is a diagram showing the temperature distribution in the heat storage tank 1 according to the seventh embodiment. The horizontal axis indicates the position in the heat storage tank 1, and the vertical axis indicates the temperature. Since the temperature gradually increases in response to the gradual decrease in the flow rate, the temperature is added continuously, not in stages. However, at the end of the heat storage operation, the temperature becomes the ninth temperature 28 in FIG. 5, which is different from the seventh temperature 26 in FIG. 4. At the ninth temperature 28, there is no thermocline between the higher temperature region and the region where the temperature remains the same as at the previous time. In FIG. 5, the rate of change of the reduction is gradually increased little by little, but the method of change may be freely determined.

[0071] The temperature after being left for a long time becomes the tenth temperature 29. The tenth temperature 29 is cooled from the inlet side pipe L4 (see FIG. 1) near the inlet of the heat storage tank 1 during the heat storage operation, and the temperature is reduced. However, as in the first, third and fifth embodiments, when comparing the temperature profile of FIG. 9 of the conventional technology with that of FIG. 5 of the seventh embodiment, the tenth temperature 29 of the seventh embodiment is added with the temperature, so even if the temperature is reduced, it is not lower than the heat dissipation operation necessary temperature 21 like the second temperature of the conventional technology. In addition, compared with the fourth temperature 20 of the first embodiment (see FIG. 2), the sixth temperature 25 of the third embodiment (see FIG. 3) and the eighth temperature 27 of the fifth embodiment (see FIG. 4), the temperature profile is closer to a constant temperature state. In FIG. 5, the temperature is constant because the change in the flow rate is determined so that the temperature becomes constant at the same temperature as the heat storage temperature after the temperature is reduced. This change can be obtained by learning by experience or by heat transfer calculation.

[0072] The flow direction of the air 5 during the heat dissipation operation is the opposite direction to that during the heat storage operation, and the outlet during the heat dissipation operation is the inlet during the heat storage operation, so the temperature of the air 5 at the start of the heat dissipation operation is the temperature of the solid sensible heat storage material 23 near the inlet during the heat storage operation. However, as in the first, third, and fifth embodiments, the heat dissipation temperature at the start of the heat dissipation operation does not become lower than the heat dissipation operation required temperature 21. Therefore, the temperature at the start of the heat dissipation is kept at or above the required temperature. In addition, the temperature after a long period of time is smoother and closer to a constant value than in the first, third, and fifth embodiments, so that the heat dissipation operation in which heat is supplied can be controlled more easily. Since the temperature is constant in FIG. 5, the heat dissipation operation in which heat is supplied can be controlled more easily.

[0073] In this way, the technology according to claims 5 to 7 allows the temperature profile at the end of the heat storage operation to be freely created. This allows the temperature profile at the start of the heat dissipation operation to be freely created. The technology according to claims 5 to 7 has the effect of allowing the creation of a temperature profile that makes it easy to control the heat dissipation operation.

[0074] The start time of the latter period and the method of reducing the flow rate relative to the time can be determined by calculating backwards from the predicted end time of the heat storage operation, so this may be done, or a temperature sensor may be installed near the outlet of the heat storage tank 1, and the time at which the temperature reaches each of several predetermined temperatures may be used. If it is possible to ensure that the temperature after a long period of time becomes equal to or higher than the heat dissipation operation required temperature 21, such as the tenth temperature 29, the latter period may be short. In addition, the first blower 3 and the valves 12 and 13 may be controlled manually by an operator, or automatically using information from a sensor or a timer.

[0075] Although the high-temperature heat source fluid (heat medium) is air, it does not have to be air, and it may be liquid instead of gas. Also, the heat medium is heated by the electric heater 2, but it may be heated by heat recovered from the combustion exhaust gas. Also, in the heat storage system 200 according to this embodiment, the heat radiated from the heat storage system 200 is used as a heat source for the steam turbine 10, but this is not limiting. For example, the heat radiated from the heat storage system 200 may be used for air conditioning or other purposes.

[0076] As described above, according to this embodiment, the time change rate of the reduction in the flow rate of the air 5 is gradually changed. Therefore, the temperature profile in the heat storage tank 1 at the end of the heat storage operation can be freely created, and can be made smoother. This makes it possible to smoothly and freely create the temperature profile on the inlet side (during heat storage) of the heat storage tank 1 at the tenth temperature 29, which is the temperature at the start of the heat dissipation operation after a long period of time of leaving, and the heat dissipation temperature at the start of the heat dissipation operation after a long period of time of leaving does not become less than the heat dissipation operation required temperature 21, and can also be made close to a constant temperature. This makes it easier to control the heat dissipation operation that supplies heat.

[0077] Eighth embodiment The heat storage system 200 according to the eighth embodiment differs from the heat storage system 200 according to the sixth embodiment in that the rate of change over time of the increase in the amount of heat applied to the air 5 is gradually changed. The eighth embodiment corresponding to claim 8 will be described with reference to Fig. 5. Descriptions of parts that are the same as the heat storage system 200 according to the conventional technology and the heat storage systems 200 according to the first to seventh embodiments may be omitted.

[0078] In the heat storage system 200 according to the second embodiment, the heat storage operation time is divided into two parts, a front part and a rear part, and the amount of heat applied to the heat medium in the rear part is increased from the amount of heat applied to the heat medium in the front part while the flow rate of the air 5 remains the same. In the heat storage system 200 according to the fourth embodiment, the act of increasing the amount of heat is performed in multiple parts. In the heat storage system 200 according to the sixth embodiment, the amount of heat is not reduced stepwise, but gradually, that is, continuously with respect to time. In the heat storage system 200 according to the eighth embodiment, the time rate of increase in the amount of heat is gradually changed. In FIG. 5, the rate of increase is gradually increased little by little, but the way of changing it may be determined freely. The heat medium is air 5, and the air 5 may be heated by an electric heater 2 (see FIG. 8) or by heat recovered from combustion exhaust gas. The output of the electric heater 2 can be easily increased or decreased.

[0079] As the amount of heating gradually decreases, the temperature gradually increases, so the temperature increase is continuous rather than gradual, but at the end of the heat storage operation, the temperature becomes ninth temperature 28 in Figure 5, unlike seventh temperature 26 in Figure 4. At ninth temperature 28, there is no thermocline between the hotter region and the region that remains at the temperature of the previous time.

[0080] The temperature after being left for a long time becomes the tenth temperature 29. The tenth temperature 29 is cooled from the inlet side pipe L4 near the inlet during the heat storage operation, and the temperature is reduced. However, as in the second, fourth and sixth embodiments, when comparing the temperature profile of FIG. 5 according to the eighth embodiment with that of FIG. 5 according to the conventional technology, the tenth temperature 29 according to the eighth embodiment is added with the temperature, so even if the temperature is reduced, it is not lower than the heat dissipation operation necessary temperature 21 like the second temperature 17 (see FIG. 9) according to the conventional technology. In addition, the temperature profile is closer to a constant temperature state than the fourth temperature 20 (see FIG. 2) according to the second embodiment, the sixth temperature 25 (see FIG. 3) according to the fourth embodiment and the eighth temperature 27 (see FIG. 5) according to the sixth embodiment. In FIG. 5, the temperature is constant because the change in the amount of heat is determined so that the temperature becomes constant at the same temperature as the heat storage temperature after the temperature is reduced. The way in which this change is made is obtained by learning by experience or heat transfer calculation.

[0081] The flow direction of the air 5 during the heat dissipation operation is the opposite direction to that during the heat storage operation, and the outlet during the heat dissipation operation is the inlet during the heat storage operation, so the temperature of the air 5 at the start of the heat dissipation operation is the temperature of the solid sensible heat storage material 23 near the inlet during the heat storage operation. However, as in the first, third, and fifth embodiments, the heat dissipation temperature at the start of the heat dissipation operation does not become lower than the heat dissipation operation required temperature 21. Therefore, the temperature at the start of the heat dissipation operation is kept at or above the required temperature. In addition, compared to the second, fourth, and sixth embodiments, the temperature after a long period of time is smoother and closer to a constant value, so that the heat dissipation operation in which heat is supplied can be easily controlled. Since the temperature is constant in FIG. 5, the effect of making it easier to control the heat dissipation operation in which heat is supplied is particularly large.

[0082] In this way, the technology according to claims 5 to 8 allows the temperature profile at the end of the heat storage operation to be freely created. This allows the temperature profile at the start of the heat dissipation operation to be freely created. The technology according to claims 5 to 8 has the effect of allowing the creation of a temperature profile that makes it easy to control the heat dissipation operation.

[0083] The start time of the latter period and the method of increasing the amount of heating relative to the time can be determined by calculating backwards from the predicted end time of the heat storage operation, so this may be done, or a temperature sensor may be installed near the outlet of the heat storage tank 1, and the time at which the temperature reaches each of several predetermined temperatures may be used. If it is possible to ensure that the temperature after being left for a long period of time reaches or exceeds the temperature required for heat dissipation operation 21, such as the tenth temperature 29, the latter period may be short. In addition, the first blower 3 and the valves 12 and 13 may be controlled manually by an operator, or automatically using information from a sensor or a timer.

[0084] Although the high-temperature heat source fluid (heat medium) is air, it does not have to be air, and it may be liquid instead of gas. In addition, in the heat storage system 200 according to the present embodiment, the heat dissipated from the heat storage system 200 is used as a heat source for the steam turbine 10, but this is not limiting. For example, the heat dissipated from the heat storage system 200 may be used for air conditioning or other purposes.

[0085] As described above, according to this embodiment, the time rate of change in the amount of heat applied to the air 5 is gradually changed. Therefore, the temperature profile in the heat storage tank 1 at the end of the heat storage operation can be freely created, and can be made smoother. This makes it possible to smoothly and freely create the temperature profile on the inlet side (during heat storage) of the heat storage tank 1 at the tenth temperature 29, which is the temperature at the start of the heat dissipation operation after a long period of time of leaving, and the heat dissipation temperature at the start of the heat dissipation operation after a long period of time of leaving does not become lower than the heat dissipation operation required temperature 21, and can also be made close to a constant temperature. This makes it easier to control the heat dissipation operation that supplies heat.

[0086] Ninth embodiment The heat storage system 200 according to the ninth embodiment differs from the heat storage system 200 according to the seventh embodiment in that the rate of change of the reduction in the flow rate of the air 5 is increased so that the heat storage temperature near the inlet during heat storage operation becomes high. Example 9 corresponding to claim 9 will be described with reference to Fig. 9. Descriptions of parts that are the same as the heat storage system 200 according to the conventional technology and the heat storage systems 200 according to the first to eighth embodiments may be omitted.

[0087] In the heat storage system 200 according to the first embodiment, the heat storage operation time is divided into two parts, a front side and a rear side, and the flow rate of the air 5 in the rear side is reduced from the flow rate of the air 5 in the front side while the amount of heat from the electric heater 2 to the air 5 remains the same. In the heat storage system 200 according to the third embodiment, the action of reducing the flow rate is performed in multiple parts. In the heat storage system 200 according to the fifth embodiment, the flow rate of the air 5 is reduced gradually, not stepwise, that is, continuously with respect to time. In the heat storage system 200 according to the seventh embodiment, the time change rate of the reduction of the flow rate of the air 5 is gradually changed. In the heat storage system 200 according to the ninth embodiment, the rate of change of the reduction is increased so that the heat storage temperature near the inlet during the heat storage operation becomes higher, compared to FIG. 8 of the seventh embodiment.

[0088] Fig. 6 is a diagram showing the temperature distribution in the heat storage tank 1 according to the ninth embodiment. The horizontal axis indicates the position in the heat storage tank 1, and the vertical axis indicates the temperature. As shown in Fig. 6, the temperature gradually increases as the flow rate gradually decreases, so the temperature is added continuously rather than stepwise. At the end of the heat storage operation, the temperature becomes the eleventh temperature 30 in Fig. 6, unlike the seventh temperature 26 in Fig. 4. At the eleventh temperature 30, there is no thermocline between the higher temperature region and the region where the temperature remains the same as at the previous time.

[0089] The temperature after being left for a long time becomes the 12th temperature 31. The 12th temperature 31 is cooled from the inlet side pipe L4 and the temperature is decreased near the inlet during the heat storage operation, as in the first, third, fifth and seventh embodiments. However, when comparing the temperature profile of FIG. 9 of the conventional technology with that of FIG. 6 of the ninth embodiment, the 12th temperature 31 of the ninth embodiment is added with the temperature, so even if the temperature is decreased, it is not lower than the heat dissipation operation necessary temperature 21 like the second temperature 17 (see FIG. 9) of the conventional technology. In addition, compared with the fourth temperature 20 (see FIG. 2) of the first embodiment and the sixth temperature 25 (see FIG. 3) of the third embodiment, the temperature profile is closer to a constant temperature state. While the eighth temperature 27 (see FIG. 4) of the fifth embodiment is a constant temperature, the heat storage temperature near the inlet during the heat storage operation is high at the 12th temperature 31. This is because the change in the flow rate is determined so that the heat storage temperature near the inlet during the heat storage operation becomes higher than the other heat storage temperatures after the temperature decrease, and the other heat storage temperatures are constant. The way in which this change occurs can be learned through experience or heat transfer calculations.

[0090] The flow direction of the air 5 during the heat dissipation operation is the opposite direction to that during the heat storage operation, and the outlet during the heat dissipation operation is the inlet during the heat storage operation, so the temperature of the air 5 at the start of the heat dissipation operation is the temperature of the solid sensible heat storage material 23 near the inlet during the heat storage operation. However, as in the first, third, fifth, and seventh embodiments, the heat dissipation temperature at the start of the heat dissipation operation does not become lower than the heat dissipation operation required temperature 21. Therefore, the temperature at the start of the heat dissipation operation is kept at or above the required temperature. Now, at the start of the heat dissipation operation, the pipe L4 (located on the inlet side during the heat storage operation and on the outlet side during the heat dissipation operation) which is the flow path of the air 5 flowing out of the heat storage tank 1 has a lower temperature than the air 5, so the temperature of the air 5 decreases while flowing until the pipe L4 is sufficiently heated by the air 5. Therefore, at the start of the heat dissipation operation, it is desirable that the temperature of the air 5 at the time of flowing out of the heat storage tank 1 is higher than the heat storage temperature. Since this is the case in FIG. 9, there is an effect that the heat dissipation operation in which heat supply is performed is particularly easy to control.

[0091] In this way, the technology according to claims 5 to 9 allows the temperature profile at the end of the heat storage operation to be freely created. This allows the temperature profile at the start of the heat dissipation operation to be freely created. The technology according to claims 5 to 9 has the effect of allowing the creation of a temperature profile that makes it easy to control the heat dissipation operation.

[0092] The start time of the latter period and the method of reducing the flow rate relative to the time can be determined by calculating backwards from the predicted end time of the heat storage operation, so this may be done, or a temperature sensor may be installed near the outlet of the heat storage tank 1, and the time at which the temperature reaches each of several predetermined temperatures may be used. If it is possible to ensure that the temperature after a long period of time becomes equal to or higher than the heat dissipation operation required temperature 21, such as the 12th temperature 31, the latter period may be short. In addition, the first blower 3 and the valves 12 and 13 may be controlled manually by an operator, or automatically using information from a sensor or a timer.

[0093] Although the high-temperature heat source fluid (heat medium) is air, it does not have to be air, and it may be liquid instead of gas. Also, the heat medium is heated by the electric heater 2, but it may be heated by heat recovered from the combustion exhaust gas. Also, in the heat storage system 200 according to this embodiment, the heat radiated from the heat storage system 200 is used as a heat source for the steam turbine 10, but this is not limiting. For example, the heat radiated from the heat storage system 200 may be used for air conditioning or other purposes.

[0094] As described above, according to this embodiment, the flow rate of the air 5 is reduced by increasing the rate of change so that the heat storage temperature near the inlet during the heat storage operation becomes higher. Therefore, it is possible to freely and smoothly create the temperature profile in the heat storage tank 1 at the end of the heat storage operation, and to increase the temperature near the inlet during the heat storage operation. This makes it possible to freely and smoothly create the temperature profile on the inlet side (during heat storage) of the heat storage tank 1 at the tenth temperature 29, which is the temperature at the start of the heat dissipation operation after a long period of time of being left unused, and it is also possible to approach a constant temperature by taking into consideration that the outflow air at the start of the heat dissipation is circulated while being cooled by the pipe L4. Therefore, it is possible to more easily control the heat dissipation operation to supply heat.

[0095] Tenth embodiment The heat storage system 200 according to the tenth embodiment differs from the heat storage system 200 according to the eighth embodiment in that the rate of change of the amount of heat applied to the air 5 is increased so that the stored heat temperature near the inlet during heat storage operation becomes high. The tenth embodiment corresponding to claim 10 will be described with reference to Fig. 6. Descriptions of parts that are the same as the heat storage system 200 according to the conventional technology and the heat storage systems 200 according to the first to ninth embodiments may be omitted.

[0096] In the heat storage system 200 according to the second embodiment, the heat storage operation time is divided into two parts, a front part and a rear part, and the amount of heat to the heat medium in the rear part is increased from the amount of heat to the heat medium in the front part while the flow rate of the air 5 remains the same. In the heat storage system 200 according to the fourth embodiment, the act of increasing the amount of heat is performed in multiple parts. In the heat storage system 200 according to the sixth embodiment, the amount of heat is not reduced stepwise, but gradually, that is, continuously with respect to time. In the heat storage system 200 according to the eighth embodiment, the time change rate of the increase in the amount of heat is gradually changed. In the heat storage system 200 according to the tenth embodiment, the rate of change of the amount of heat is increased so that the heat storage temperature near the inlet during the heat storage operation becomes higher, compared to FIG. 8 according to the eighth embodiment. The heat medium is air 5, and the air 5 may be heated by an electric heater 2 (see FIG. 8) or by heat recovered from combustion exhaust gas. The output of the electric heater 2 can be easily increased or decreased.

[0097] As the amount of heating gradually increases, the temperature gradually increases, so the temperature increase is continuous rather than stepped, but at the end of the heat storage operation, the temperature becomes eleventh temperature 30 in Figure 6, unlike seventh temperature 26 in Figure 4. At eleventh temperature 30, there is no thermocline between the higher temperature area and the area where the temperature remains the same as at the previous time.

[0098] The temperature after long-term standing becomes the 12th temperature 31. The 12th temperature 31 is cooled from the inlet side pipe L4 and the temperature is decreased near the inlet during the heat storage operation, as in the second, fourth, sixth and eighth embodiments. However, as in the second, fourth, sixth and eighth embodiments, when comparing the temperature profile of FIG. 9 of the conventional technology with that of FIG. 6 of the tenth embodiment, the 12th temperature 31 of the tenth embodiment is added with the temperature, so even if the temperature is decreased, it is not lower than the heat dissipation operation necessary temperature 21 like the second temperature 17 (see FIG. 9) of the conventional technology. In addition, the temperature profile is closer to a constant temperature state than the fourth temperature 20 (see FIG. 2) of the second embodiment, the sixth temperature 25 (see FIG. 3) of the fourth embodiment and the eighth temperature 27 (see FIG. 4) of the sixth embodiment. The tenth temperature 29 (see FIG. 5) of the eighth embodiment is a constant temperature, whereas the heat storage temperature near the inlet during the heat storage operation is high in the 12th temperature 31. This is because the change in the amount of heat is determined so that the temperature of the heat storage near the inlet during heat storage operation becomes higher than the other heat storage temperatures after the temperature drop, and the other heat storage temperatures remain constant. This change can be obtained by learning from experience or by heat transfer calculations.

[0099] The flow direction of the air 5 during the heat dissipation operation is the opposite direction to that during the heat storage operation, and the outlet during the heat dissipation operation is the inlet during the heat storage operation, so the temperature of the air 5 at the start of the heat dissipation operation is the temperature of the solid sensible heat storage material 23 near the inlet during the heat storage operation. However, as in the second, fourth, sixth, and eighth embodiments, the heat dissipation temperature at the start of the heat dissipation operation does not become lower than the heat dissipation operation required temperature 21. Therefore, the temperature at the start of the heat dissipation operation is kept at or above the required temperature. Now, at the start of the heat dissipation operation, the pipe L4 (located on the inlet side during the heat storage operation and on the outlet side during the heat dissipation operation) which is the flow path of the air 5 flowing out of the heat storage tank 1 has a lower temperature than the air 5, so the temperature of the air 5 decreases while flowing until the pipe L4 is sufficiently heated by the air 5. Therefore, at the start of the heat dissipation operation, it is desirable that the temperature of the air 5 at the time of flowing out of the heat storage tank 1 is higher than the heat storage temperature. Since this is the case in FIG. 6, there is an effect that the heat dissipation operation in which heat supply is performed is particularly easy to control.

[0100] In this way, the technology according to claims 5 to 10 allows the temperature profile at the end of the heat storage operation to be freely created. This allows the temperature profile at the start of the heat dissipation operation to be freely created. The technology according to claims 5 to 10 has the effect of allowing the creation of a temperature profile that makes it easy to control the heat dissipation operation.

[0101] The start time of the latter period and the method of increasing the amount of heating relative to the time can be determined by calculating backwards from the predicted end time of the heat storage operation, so this may be done, or a temperature sensor may be installed near the outlet of the heat storage tank 1, and the time at which the temperature reaches each of several predetermined temperatures may be used. If it is possible to ensure that the temperature after a long period of time becomes equal to or higher than the heat dissipation operation required temperature 21, such as the 12th temperature 31, the latter period may be short. In addition, the first blower 3 and the valves 12 and 13 may be controlled manually by an operator, or automatically using information from a sensor or a timer.

[0102] Although the high-temperature heat source fluid (heat medium) is air, it does not have to be air, and it may be liquid instead of gas. In addition, in the heat storage system 200 according to the present embodiment, the heat dissipated from the heat storage system 200 is used as a heat source for the steam turbine 10, but this is not limiting. For example, the heat dissipated from the heat storage system 200 may be used for air conditioning or other purposes.

[0103] As described above, according to this embodiment, the rate of change of the amount of heat applied to the air 5 is increased so that the heat storage temperature near the inlet during the heat storage operation becomes higher. Therefore, it is possible to freely and smoothly create the temperature profile in the heat storage tank 1 at the end of the heat storage operation, and to raise the temperature near the inlet during the heat storage operation. This makes it possible to freely and smoothly create the temperature profile on the inlet side (during heat storage) of the heat storage tank 1 at the 10th temperature 29, which is the temperature at the start of the heat dissipation operation after a long period of time of leaving, so that the heat dissipation temperature at the start of the heat dissipation operation after a long period of time of leaving will not fall below the heat dissipation operation required temperature 21, and it is also possible to approach a constant temperature by taking into consideration that the outflow air at the start of the heat dissipation flows while being cooled by the pipe L4. Therefore, it is possible to more easily control the heat dissipation operation to supply heat.

[0104] Eleventh embodiment The heat storage system 200 according to the eleventh embodiment differs from the heat storage systems 200 according to the first to tenth embodiments in that a control device 500 is further provided.

[0105] Fig. 7 is a diagram showing a configuration example of a heat storage system 200 according to an eleventh embodiment. As shown in Fig. 7, the heat storage system 200 according to the eleventh embodiment further includes a control device 500 and a temperature sensor 502. The temperature sensor 502 measures the temperature of the input / output end of the heat storage tank 1.

[0106] The control device 500 has an internal timer. The control device 500 can control, for example, the opening degree of the valves 12 to 14 according to the time information of the internal timer. The control device 500 can also control the increase or decrease in the output of the heater for the air 5 (the electric heater 2 in FIG. 7) according to the time information of the internal timer. The control device 500 can also control the blowing capacity of the first fan 3 according to the time information of the internal timer. As a result, the control device 500 according to this embodiment can carry out the control of the heat storage operation described with reference to FIGS. 2 to 6.

[0107] In addition, the control device 500 can control the opening degree of the valves 12 to 14, for example, according to the measurement result of the temperature sensor 502. Furthermore, the control device 500 can control the increase / decrease of the output of the heating device for the air 5 (electric heater 2 in FIG. 7) according to the measurement result of the temperature sensor 502. In addition, the control device 500 can control the blowing capacity of the first blower 3 according to the measurement result of the temperature sensor 502. Thereby, the control device 500 according to this embodiment can control the heat storage operation of the heat storage system 200 described using FIG. 2 to FIG. 6. Note that the heat storage system 200 according to this embodiment has an internal timer and a temperature sensor 502, but is not limited thereto. For example, the heat storage system 200 according to this embodiment may have only an internal timer. Or, the heat storage system 200 according to this embodiment may have only a temperature sensor 502. Furthermore, the control device 500 may be a control device that controls only one of the opening degree of the valves 12 to 14, the increase or decrease in the output of the heater for the air 5 (electric heater 2 in FIG. 7), and the blowing capacity of the first blower 3.

[0108] In this way, the control device 500 according to this embodiment can perform automatic control of the heat storage system 200 according to the first to tenth embodiments described above. [Explanation of symbols]

[0109] 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: first temperature, 17: second temperature, 19: third temperature, 20: fourth temperature, 21: temperature required for heat dissipation operation, 23: solid sensible heat storage material, 24: fifth temperature, 25: sixth temperature, 26: seventh temperature, 27: eighth temperature, 28: ninth temperature, 29: tenth temperature, 30: eleventh temperature, 31: twelfth temperature, 32: air flow direction during heat storage operation, 33: air flow direction during heat dissipation operation, 100: power adjustment system, 200: heat storage system, 500: control device, 502: temperature sensor.

Claims

1. A heat storage system using a heat storage tank in which a heat medium heated by a high-temperature heat source is circulated during a heat storage operation to store heat in a solid sensible heat storage material, and in which a low-temperature heat medium is circulated in a direction opposite to that during the heat storage operation to radiate heat from the solid sensible heat storage material during a heat dissipation operation, A heat storage system in which a heat storage operation time is divided into a front side and a rear side, and the flow rate of the heat medium in the rear side time is reduced compared to the flow rate of the heat medium in the front side time.

2. A heat storage system using a heat storage tank in which a heat medium heated by a high-temperature heat source is circulated during a heat storage operation to store heat in a solid sensible heat storage material, and in which a low-temperature heat medium is circulated in a direction opposite to that during the heat storage operation to radiate heat from the solid sensible heat storage material during a heat dissipation operation, A heat storage system in which a heat storage operation time is divided into a front side and a rear side, and the amount of heat applied to the heat medium during the rear side is increased compared to the amount of heat applied to the heat medium during the front side.

3. The heat storage system according to claim 1 , wherein the action of reducing the flow rate of the heat medium is carried out in a plurality of times.

4. The heat storage system according to claim 2 , wherein the action of increasing the amount of heat applied to the heat medium is carried out in a plurality of steps.

5. The heat storage system according to claim 1 , wherein the action of reducing the flow rate of the heat medium is performed by gradually changing a time rate of the reduction.

6. The heat storage system according to claim 2 , wherein the action of increasing the amount of heat applied to the heat medium is carried out by gradually changing a time rate of increase.

7. The heat storage system according to claim 5 , wherein a time rate of change of the reduction in the flow rate of the heat medium is changed so that a heat storage temperature distribution at the start of a heat dissipation operation of the heat storage system approaches a constant value.

8. The heat storage system according to claim 6, wherein a time rate of change of an increase in the amount of heat applied to the heat medium is changed so that a heat storage temperature distribution at the start of a heat dissipation operation of the heat storage system approaches a constant value.

9. The heat storage system according to claim 5, wherein a time rate of change of the reduction in the flow rate of the heat medium is changed so that an inlet side during a heat storage operation of the heat storage tank is higher than other regions in a heat storage temperature distribution at the start of a heat dissipation operation of the heat storage system.

10. The heat storage system according to claim 6, wherein a time rate of change of an increase in the amount of heat applied to the heat medium is changed so that an inlet side during a heat storage operation of the heat storage tank is higher than other regions in a heat storage temperature distribution at the start of a heat dissipation operation of the heat storage system.

11. A heat storage method for a heat storage system using a heat storage tank, in which a heat medium heated by a high-temperature heat source is circulated during a heat storage operation to store heat in a solid sensible heat storage material, and in which a low-temperature heat medium is circulated in a direction opposite to that during the heat storage operation to radiate heat from the solid sensible heat storage material during a heat dissipation operation, A heat storage method comprising: dividing a heat storage operation time into a front period and a rear period; and reducing the flow rate of the heat medium in the rear period below the flow rate of the heat medium in the front period.

12. A heat storage method for a heat storage system using a heat storage tank, in which a heat medium heated by a high-temperature heat source is circulated during a heat storage operation to store heat in a solid sensible heat storage material, and in which a low-temperature heat medium is circulated in a direction opposite to that during the heat storage operation to radiate heat from the solid sensible heat storage material during a heat dissipation operation, A heat storage method, comprising: dividing a heat storage operation time into a front period and a rear period; and increasing the amount of heat applied to the heat medium during the rear period compared to the amount of heat applied to the heat medium during the front period.

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