Electrothermal conversion device and thermal storage system

Abstract

To suppress facilities from being large-sized while excellently securing thermal energy to be transferred to a thermal medium.SOLUTION: An electrothermal conversion device (1) comprises an outside rotation part (21) which serves as a cylindrical flow passage formation part in which a thermal medium (H) flows, a heat generation part (10) which is arranged cylindrically extending along an extension direction of the outside rotation part in the outside rotation part, and a stirring part (20) which rotates on a center axis (C) along the extension direction of the outside rotation part. The heat generation part converts electric energy into thermal energy to heat the thermal medium. In a section crossing the center axis, the thermal medium flows between the heat generation part and stirring part in the outside rotation part.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electrothermal converter for heating a heat medium and a heat storage system. [Background technology]

[0002] Patent Document 1 discloses a heat generating device that transfers heat generated by a heat generating member to a heat medium. In Patent Document 1, a passage is formed inside the heat generating member, and a heat storage device is connected to this passage via an inlet pipe and an outlet pipe. The passage of the heat generating member, the inlet pipe, the outlet pipe, and the heat storage device form a series of paths through which the heat medium flows and circulates, and thermal energy is recovered. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6572905 Summary of the Invention [Problem to be solved by the invention]

[0004] Depending on the composition, the heat transfer medium may decompose if the temperature is too high, so a design is required to prevent the temperature from exceeding the decomposition temperature even locally. In Patent Document 1, the heat transfer medium flows through a narrow passage formed in the heat-generating component, and there is a problem that if an attempt is made to increase the amount of heat transferred to the heat transfer medium, the heat-generating component will become hotter than the decomposition temperature of the heat transfer medium. On the other hand, there is a problem that if the temperature of the heat-generating component is lowered, the amount of heat transferred from the heat-generating device to the heat transfer medium decreases, and in order to ensure a sufficient amount of heat, multiple heat-generating devices are required, making the device large-scale.

[0005] The present invention has been made in consideration of the above points, and one of its objects is to provide an electrothermal conversion device and a heat storage system that can effectively ensure the thermal energy transferred to the heat medium while preventing the equipment from becoming larger. [Means for solving the problem]

[0006] An electrothermal conversion device of one embodiment of the present invention is an electrothermal conversion device comprising: a cylindrical flow path forming portion through which a heat medium flows; a heat generating portion arranged in a cylindrical shape extending along the extension direction of the flow path forming portion within the flow path forming portion, which converts electrical energy into thermal energy to heat the heat medium; and a stirring portion which rotates around a central axis along the extension direction of the flow path forming portion to stir the heat medium, and is characterized in that the heat medium flows between the heat generating portion and the stirring portion within the flow path forming portion at a cross section intersecting the central axis.

[0007] The heat storage system of one embodiment of the present invention is characterized in that it comprises the electrothermal conversion device, a low-temperature heat storage tank that stores the heat medium and supplies the heat medium to the electrothermal conversion device, a high-temperature heat storage tank that stores the heat medium heated in the electrothermal conversion device, and a heat exchanger that exchanges heat between the heat medium supplied from the high-temperature heat storage tank to the low-temperature heat storage tank and a predetermined working fluid. Effect of the Invention

[0008] According to the present invention, the heat medium in the flow path that is cylindrical between the heat generating part and the stirring part can be spirally stirred by the stirring part while the heat medium is transferred from the heat generating part to the heat medium. This makes it possible to prevent the heat medium from becoming locally hot, while ensuring a good amount of heat transferred to the heat medium. This eliminates the need to install multiple heat generating devices, and avoids the need for large-scale equipment. [Brief description of the drawings]

[0009] [Figure 1] 1 is a configuration diagram illustrating a typical electrothermal conversion device according to an embodiment; [Diagram 2] 1 is a schematic cross-sectional view of an electrothermal conversion device according to an embodiment. [Diagram 3] FIG. 1 is an explanatory diagram of a heat storage system according to an embodiment. [Figure 4] 1. FIG. 4 is a diagram similar to FIG. 1 showing the configuration of an electrothermal converter according to a modified example. [Diagram 5] 5 is a cross-sectional view taken along line AA in FIG. 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an electrothermal converter according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the following embodiment, and can be appropriately modified within the scope of the present invention. In the following drawings, some components may be omitted for the sake of convenience.

[0011] FIG. 1 is a schematic diagram of an electrothermal converter according to an embodiment. FIG. 2 is a schematic cross-sectional view of an electrothermal converter according to an embodiment. As shown in FIGS. 1 and 2, an electrothermal converter 1 includes a heat generating section 10 and a stirring section 20, and has a shape extending in a direction along a central axis C. FIG. 2 is a diagram showing a cross section perpendicular to (intersecting) the central axis C. The electrothermal converter 1 is a device for heating a heat medium H, and the heat medium H can be, for example, a nitrate. However, the heat medium H can be appropriately selected in consideration of specific heat, viscosity, melting point, decomposition temperature, cost, etc. according to the specifications of a system using the electrothermal converter 1, and other factors. In addition to the above nitrates, a highly heat-resistant oil can be used.

[0012] The heat generating unit 10 is configured by arranging a plurality of cylindrical resistance heaters 11 in a cylindrical shape, and the central axis position of the cylinder is set to the same position as the above-mentioned central axis C. Therefore, the heat generating unit 10 also extends in the extension direction of the central axis C.

[0013] The resistance heater 11 generates Joule heat when a current flows due to the power supply, and converts the electrical energy into thermal energy to heat the heat medium H. Although not shown, depending on the voltage specifications of the resistance heater 11, a transformer may be connected between the power supply system and the resistance heater 11, or a switch may be connected for control.

[0014] The stirring unit 20 includes a cylindrical outer rotating unit 21 inside which the heat generating unit 10 is disposed, and a central rotating unit 22 disposed inside the outer rotating unit 21 and the heat generating unit 10 .

[0015] The outer rotating part 21 is provided in a cylindrical shape, and the central axis of the cylinder is located at the same position as the above-mentioned central axis C. Moreover, the central rotating part 22 is provided in a cylindrical shape, and the central axis of the cylinder is located at the same position as the above-mentioned central axis C. Therefore, the outer rotating part 21 and the central rotating part 22 are provided concentrically with the heat generating part 10 and the electrothermal converter 1, and extend along the extension direction of the central axis C. In other words, the central axis C, the heat generating part 10, and the central rotating part 22 extend along the extension direction of the outer rotating part 21.

[0016] The outer rotating part 21 functions as a flow path forming part that forms a flow path F through which the heat medium H flows, in other words, the outer rotating part 21 is formed by the flow path forming part. Inside the outer rotating part 21, the heat medium H flows between the heat generating part 10 and the inner circumferential surface of the outer rotating part 21, and the heat medium H also flows between the heat generating part 10 and the outer circumferential surface of the central rotating part 22.

[0017] In this embodiment, the outer rotating part 21 has an inlet part 21a for the heat medium H provided on the right side in Fig. 1, and an outlet part 21b for the heat medium H provided on the left side in Fig. 1. Therefore, inside the outer rotating part 21, the heat medium H flows from the right side to the left side in Fig. 1, with the right side being the upstream side in the flow direction of the heat medium H and the left side being the downstream side in the flow direction of the heat medium H.

[0018] The inlet 21a is connected to a low-temperature heat storage tank 31 which is a supply source of the low-temperature heat medium H, and the outlet 21b is connected to a high-temperature heat storage tank 32 which is a supply destination (output destination) of the heated and high-temperature heat medium H. The heat storage system including the low-temperature heat storage tank 31 and the high-temperature heat storage tank 32 will be described later.

[0019] The outer rotating part 21 and the central rotating part 22 are provided to be rotatable around the central axis C via rotating mechanisms 25, 26. Although detailed illustrations are omitted, each of the rotating mechanisms 25, 26 can be exemplified by a configuration including an electric motor such as a motor that is driven by power obtained from an external power source, and a rotational force transmission mechanism including a gear structure or pulley structure that rotates each of the rotating parts 21, 22 by the output of the electric motor.

[0020] The stirring unit 20 applies a force to the heat medium H in a direction rotating about the central axis C by the rotation of the outer rotating unit 21 and the central rotating unit 22, stirring the heat medium H in the flow path F. The inner circumferential surface of the outer rotating unit 21 and the outer circumferential surface of the central rotating unit 22, which are the surfaces with which the heat medium H comes into contact in the stirring unit 20, are formed by smooth surfaces. Since these smooth surfaces come into contact with the heat medium H, the heat medium H flows in a direction approaching the direction of rotation about the central axis C through friction therebetween, and is stirred.

[0021] Here, the term "smooth surface" refers not only to a mirror-like surface along a cylindrical surface or a circumferential surface, but also to a surface that is manufactured with the intention of forming a mirror-like surface but has some surface roughness due to processing accuracy, tolerances, etc. Therefore, the inner circumferential surface of the outer rotating part 21 and the outer circumferential surface of the central rotating part 22 are not formed with uneven shapes such as grooves and depressions intended to increase the force that causes the heat medium H to flow in the rotational direction.

[0022] Next, a method for heating the heat medium H by the electrothermal converter 1 will be described. In the electrothermal converter 1, the heat medium H is supplied into the flow path F from the inlet 21a of the outer rotating part 21. When the heat medium H flows into the flow path F by this supply, the heat medium H flows in the direction of the central axis C from the right side to the left side in FIG. 1, while receiving a force in a direction rotating the heat medium H around the central axis C due to the rotation of the outer rotating part 21 and the central rotating part 22. As a result, the heat medium H flows in a spiral shape and is agitated, while the heat of the heat generating part 10 is transferred to the heat medium H, and the heat medium H is heated.

[0023] In this embodiment, by stirring the heat medium H as described above, the distance over which the heat medium H flows within the outer rotating part 21 can be increased, and the efficiency of heat transfer between the heat generating part 10 can be improved, thereby increasing the amount of heat transferred to the heat medium H. This makes it possible to satisfactorily ensure the amount of heat transferred to the heat medium H per electrothermal converter 1.

[0024] Moreover, the heat medium H can be agitated throughout the entire flow path F in the outer rotating part 21, preventing the heat medium H from becoming locally hot and avoiding the temperature exceeding the decomposition temperature of the heat medium H. In other words, even under conditions where the heat medium H does not exceed its decomposition temperature, the amount of heat transferred to the heat medium H per electrothermal converter 1 can be satisfactorily ensured. This makes it possible to avoid an increase in the number of electrothermal converters 1 installed and suppress an increase in the size of the equipment.

[0025] In addition, the flow path F in the outer rotating part 21 is formed by a double cylindrical space on the outside and inside of the cylindrical heat generating part 10. Therefore, the heat medium H is stirred by the rotation of the outer rotating part 21 outside the heat generating part 10, and the heat medium H is stirred by the rotation of the central rotating part 22 inside the heat generating part 10. In this way, when the flow path F is viewed in cross section, the heat medium H can be stirred evenly by the outer rotating part 21 near the outer periphery of the flow path F and the central rotating part 22 near the central axis C. This also makes it possible to efficiently transfer heat from the heat generating part 10 to the heat medium H, to satisfactorily secure the amount of heat transferred to the heat medium H, and to prevent the heat medium H from becoming locally hot in any region of the flow path F.

[0026] Here, the energy (electric power) supplied to the rotation mechanisms 25, 26 for agitating the heat medium H is considerably smaller than the energy (electric power) supplied to the heat generating section 10. The energy for agitating the heat medium H corresponds to mechanical loss in the rotation mechanisms 25, 26 that obtain power, and is transferred as heat to the heat medium H. Therefore, the energy supplied to the rotation mechanisms 25, 26 does not become a loss in the electrothermal converter 1 and can be recovered.

[0027] In this embodiment, since the inner circumferential surface of the outer rotating part 21 and the outer circumferential surface of the central rotating part 22 are formed by smooth surfaces, the rotational operation resistance of each rotating part 21, 22 can be kept small, and the energy supplied to the rotating mechanisms 25, 26 can also be kept small. This makes it possible to suppress energy loss in the rotating mechanisms 25, 26 and reduce power consumption, and also reduces the power consumption required to heat the heat medium H in the electrothermal converter 1 as a whole.

[0028] Next, a heat storage system 50 using the electrothermal converter 1 will be described. Fig. 3 is an explanatory diagram of a heat storage system according to an embodiment. The heat storage system 50 has a heat storage / discharge system 30 including the electrothermal converter 1 described above, a low-temperature heat storage tank 31, and a high-temperature heat storage tank 32. The heat storage system 50 further includes a steam turbine (power generation device) 52 that generates power from steam, and a condenser (condensing device) 53 that condenses the steam to produce condensate. Here, in the heat storage system 50, the steam and condensate (water) serve as working fluids.

[0029] The heat storage and release system 30 stores and uses a heat medium H serving as a heat storage material in a low-temperature heat storage tank 31 and a high-temperature heat storage tank 32. The high-temperature heat storage tank 32 stores a heat medium H having a higher temperature than that of the low-temperature heat storage tank 31. The heat storage and release system 30 includes a heat release pipe 34 and a pump 35 for supplying the heat medium H from the high-temperature heat storage tank 32 to the low-temperature heat storage tank 31, and a heat storage pipe 36 and a pump 37 for supplying the heat medium H from the low-temperature heat storage tank 31 to the high-temperature heat storage tank 32.

[0030] Furthermore, the heat storage and release system 30 includes a heat exchanger 38 provided in the heat release piping 34. The heat exchanger 38 is provided so as to be able to exchange heat between the heat medium H passing therethrough while being supplied from the high-temperature heat storage tank 32 to the low-temperature heat storage tank 31 and the condensate passing therethrough from the condenser 53 via a piping 56. Through this heat exchange, the condensate is heated and changes phase to steam, and the heat medium H is released. The steam generated by the heat exchanger 38 is supplied to the steam turbine 52 via a piping 55.

[0031] The heat storage pipe 36 is provided with an electrothermal converter 1, and the heat medium H is supplied from the low-temperature heat storage tank 31 to the electrothermal converter 1 via the heat storage pipe 36. The electrothermal converter 1 heats the heat medium H passing through while being supplied from the low-temperature heat storage tank 31 to the high-temperature heat storage tank 32. The electrothermal converter 1 is supplied with power from a predetermined power grid E, and the power grid E may be, for example, a power system that serves as a commercial power source outside the heat storage system 50, or a power supply system within the same plant that includes the heat storage system 50.

[0032] The steam turbine 52 is supplied with steam generated in the heat exchanger 38 via a pipe 55. The steam turbine 52 absorbs the thermal energy of the steam to generate power to rotate an output shaft 52a, and discharges the cooled steam. A generator G is connected to the steam turbine 52 via the output shaft 52a, and the generator G generates electricity by the rotation of the output shaft 52a and supplies the electricity to the power grid E.

[0033] A pipe 56 is connected to the outlet side of the steam turbine 52, and a condenser 53 and a condensate pump 57 are provided in this pipe 56 from the upstream side to the downstream side in this order. The condenser 53 recovers the steam discharged from the steam turbine 52 and condenses the steam to condense it. The condensate generated by the condenser 53 is sent toward the heat exchanger 38 by the condensate pump 57.

[0034] The heat storage system 50 can be selectively operated in a heat storage operation mode and a heat release operation mode.

[0035] In the heat storage operation mode, the pump 37 provided in the heat storage pipe 36 is operated to cause the heat medium H in the low-temperature heat storage tank 31 to flow through the heat storage pipe 36 into the electrothermal converter 1. In the electrothermal converter 1, electric energy supplied from the power grid E is converted into thermal energy to heat the heat medium H. The heat medium H that has flowed into the electrothermal converter 1 and been heated is supplied to and stored in the high-temperature heat storage tank 32. As a result, thermal energy is stored in the heat medium H, and the stored heat energy of the heat storage system 50 is increased.

[0036] In the heat radiation operation mode, the pump 35 provided in the heat radiation pipe 34 is operated to cause the heat medium H in the high-temperature heat storage tank 32 to flow into the heat exchanger 38. The condensate generated in the condenser 53 flows into the heat exchanger 38 via pipe 56 due to the operation of the condensate pump 57, and the condensate is heat exchanged with the heat medium H. In this heat exchange, thermal energy is released from the heat medium H to generate steam, and the generated steam is supplied to the steam turbine 52 via pipe 55.

[0037] The thermal energy of the steam that flows into the steam turbine 52 is converted into power to rotate the output shaft 52a in the steam turbine 52, and the temperature of the steam is reduced before it is discharged. The rotational power of the output shaft 52a is used to generate electricity in the generator G, which is then supplied to a predetermined power grid E. Thus, the thermal energy of the heat medium H and the steam is converted into electrical energy via the steam turbine 52, and the thermal energy stored in the thermal storage system 50 is reduced.

[0038] The steam discharged from the steam turbine 52 is condensed in a condenser 53. The condensate is supplied to the heat exchanger 38 via a piping 56 by a condensate pump 57, in other words, returned to the heat exchanger 38 and circulated.

[0039] The heat storage operation mode and the heat dissipation operation mode may be performed independently or simultaneously in parallel. For example, when the heat storage operation mode and the heat dissipation operation mode are performed simultaneously in parallel, the amount of the heat medium H stored in the high-temperature heat storage tank 32 may be increased by heating the heat medium H in the electrothermal converter 1 while supplying steam with a small amount of heat so that the steam turbine 52 continues to operate at a low output.

[0040] As described above, in the heat storage system 50 of this embodiment, electric power is converted into heat in the electrothermal converter 1, and the heat is transferred to and stored in the heat medium H, so that electricity can be generated again at the required timing using the steam turbine 52. Furthermore, by stirring the heat medium H in the electrothermal converter 1 as described above, it is possible to prevent the electrothermal converter 1 from becoming large in size, and therefore it is possible to avoid an increase in the equipment cost of the heat storage system 50.

[0041] Furthermore, when a large number of renewable energy facilities are introduced, the amount of energy stored in the heat medium H of the high-temperature heat storage tank 32 by the electrothermal converter 1 using daytime electric power can be increased. On the other hand, at night, by controlling the release of the amount of energy stored in the heat medium H, it is possible to change the output of the steam turbine 52 according to the required load, and this can be used more effectively as regulating power.

[0042] The embodiments of the present invention are not limited to the above-mentioned embodiments, and may be modified, substituted, or altered in various ways without departing from the spirit of the technical idea of ​​the present invention. Furthermore, if the technical idea of ​​the present invention can be realized in a different way due to technological progress or other derived technology, it may be implemented using that method. Therefore, the claims cover all embodiments that may be included within the scope of the technical idea of ​​the present invention.

[0043] The stirring unit 20 is not limited to the configuration of the above embodiment, and various modifications are possible, for example, the configuration of the modified example shown in Fig. 4 and Fig. 5 may be used. Fig. 4 is a configuration diagram similar to Fig. 1 of an electrothermal converter according to the modified example. Fig. 5 is a cross-sectional view taken along line AA in Fig. 4.

[0044] 4 and 5, in the outer rotating part 21, the area of ​​the flow passage F in a cross section intersecting with the central axis C is formed in a tapered shape that gradually decreases from the right to the left in Fig. 4. In the flow passage F, the upstream side in the flow direction of the heat medium H is the right side in Fig. 4, and the downstream side in the flow direction of the heat medium H is the left side in Fig. 4, so that the area of ​​the flow passage F is smaller on the downstream side than on the upstream side in the flow direction of the heat medium H.

[0045] In the modified example, the shape of the cross section in Fig. 4 is the same as the cross section shown in Fig. 2 in the above embodiment, and Fig. 5 shows the shape of the outer rotating part 21 as viewed in cross section at the left end side in Fig. 4. As can be seen from Figs. 2 and 5, the area of ​​the flow path F is smaller in Fig. 5, which is the downstream side, than in Fig. 2, which is the upstream side in the flow direction of the heat medium H.

[0046] By forming the flow path F as in the modified example, the area of ​​the flow path F can be reduced on the downstream side of the heat medium H, and further, the flow rate of the heat medium H can be increased in accordance with the reduction. This makes it possible to agitate the heat medium H better on the downstream side in the flow direction where the temperature of the heat medium H is relatively high, and to prevent the heat medium H from exceeding its decomposition temperature.

[0047] In addition, the outer rotating part 21 and the central rotating part 22 in the stirring part 20 may rotate at the same or different rotation speeds, and furthermore, the respective rotation directions may be the same or opposite. In addition, the central rotating part 22 may be configured not to rotate, but rotating the central rotating part 22 is advantageous in that the heat medium H inside the heat generating part 10 is easily stirred.

[0048] Furthermore, the central rotating part 22 in the stirring part 20 may be formed in a cylindrical shape, or the central rotating part 22 itself may be omitted.

[0049] In addition, in the above embodiment, the outer rotating part 21 is configured to also function as a flow path forming part, but this is not limited to this. For example, a cylindrical flow path forming part may be provided separately on the outside of the above-mentioned outer rotating part 21.

[0050] Furthermore, in the above embodiment, steam or water is used as the working fluid in the heat storage system 50. However, a fluid other than steam or water, such as helium gas, may be used as the working fluid.

[0051] Furthermore, the heat storage system 50 is not limited to a configuration using the steam turbine 52, and may be another heat utilization device capable of extracting thermal energy from the working fluid supplied from the heat exchanger . [Explanation of symbols]

[0052] 1: Electrothermal conversion device 10: Heating part 20: Stirring section 21:Outer rotating part (flow path forming part) 22: Central rotating part 31: Low temperature heat storage tank 32: High temperature heat storage tank 38:Heat exchanger 50: Heat storage system C: Central axis F: Flow path H: Heat medium

Claims

1. a cylindrical flow passage forming portion through which a heat medium flows; a heat generating section that is disposed in the flow passage forming section in a cylindrical shape extending along an extension direction of the flow passage forming section and converts electrical energy into thermal energy to heat the heat medium; a stirring unit that rotates around a central axis along an extension direction of the flow path forming unit to stir the heat medium, An electrothermal conversion device, characterized in that the heat medium flows between the heat generating portion and the stirring portion within the flow passage forming portion in a cross section intersecting the central axis.

2. 2. The electrothermal converter according to claim 1, wherein the agitating section has a surface that comes into contact with the heat transfer medium and is formed as a smooth surface.

3. The stirring unit is formed in a cylindrical shape with the heat generating unit disposed inside, and includes an outer rotating unit that rotates around the central axis, The electrothermal converter according to claim 1 , wherein the outer rotating portion is formed by the flow passage forming portion.

4. 4. The electrothermal converter according to claim 3, wherein the stirring section further comprises a central rotating section that extends along the extension direction of the flow passage forming section inside the heat generating section and rotates around the central axis.

5. 2 . The electrothermal converter according to claim 1 , wherein the stirring section includes a central rotating section that extends along an extension direction of the flow passage forming section inside the heat generating section and rotates around the central axis.

6. 2. The electrothermal conversion device according to claim 1, wherein the flow path formed by the flow path forming portion has a cross-sectional area intersecting the central axis that is smaller on the downstream side in the flow direction of the heat medium than on the upstream side.

7. The electrothermal converter according to any one of claims 1 to 6, a low-temperature heat storage tank that stores the heat medium and supplies the heat medium to the electrothermal converter; a high-temperature heat storage tank that stores the heat medium heated by the electrothermal converter; a heat exchanger for exchanging heat between the heat medium supplied from the high-temperature heat storage tank to the low-temperature heat storage tank and a predetermined working fluid.

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