Rotary heating device, electric heating device, and heat storage system

Abstract

To efficiently generate heat from a liquid heat transfer medium while reducing the power required to circulate the heat transfer medium. [Solution] The rotary heating device (20) comprises a rotor (22) that rotates around a predetermined central axis (C), a container (23) that houses the rotor, and a liquid heat transfer medium (24) that flows inside the container and is heated by friction with the rotating rotor. A helical groove (27) is formed on the outer surface of the rotor, extending spirally around the central axis. The helical groove increases the surface area of ​​the rotor, expanding the contact area with the heat transfer medium, and allows a force to be applied to deliver the heat transfer medium in a direction parallel to the central axis of the rotor.

Description

Technical Field

[0001] The present invention relates to a rotary heat generator, an electrothermal conversion device, and a heat storage system that heat a heat medium by the rotation of a rotor.

Background Art

[0002] Patent Document 1 discloses a heat conversion and heat storage machine that extracts the rotational motion of a rotating shaft and rotates a rotating body in which permanent magnets are arranged so that their polarities alternate, thereby generating heat due to hysteresis loss in a magnetic body heating element opposite thereto and transferring and storing the heat in a heat storage body. The heat storage body is made of water or oil and stored in a container, and heat energy is taken out and used when necessary.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, since the rotor integrated with the rotating shaft is formed to rotate inside a magnetic body heating element having a cylindrical shape, the outer peripheral surface of the rotor is a smooth cylindrical outer peripheral surface, and the rotor is covered by the magnetic body heating element and is non-contact with the heat storage body. In a technique for heating and storing a liquid heat medium serving as a heat storage body, there is a need for a technique that can efficiently generate heat in the flowing heat medium and reduce the power for circulating the heat medium with a configuration in which the rotor directly contacts the flowing heat medium.

[0005] The present invention has been made in view of such circumstances, and an object thereof is to provide a rotary heat generator, an electrothermal conversion device, and a heat storage system that can efficiently generate heat in a liquid heat medium and reduce the power for circulating the heat medium.

Means for Solving the Problems

[0006] The rotary heating device according to the present invention comprises a rotor that rotates around a predetermined central axis, a container that houses the rotor, and a liquid heat transfer medium that flows inside the container and is heated by friction with the rotating rotor, wherein grooves extending spirally around the central axis are formed on the outer circumferential surface of the rotor.

[0007] Furthermore, the rotary heating device according to the present invention comprises a rotor that rotates around a predetermined central axis, a container housing the rotor, and a liquid heat transfer medium that flows through the inside of the container and is heated by friction with the rotating rotor, wherein the outer circumferential surface of the rotor is formed in a tapered shape that narrows from the upstream side to the downstream side in the flow direction of the heat transfer medium.

[0008] The electric heating device according to the present invention is characterized by comprising the rotary heating element and an electric motor that rotates the rotor via a shaft.

[0009] The heat storage system according to the present invention is characterized by comprising: an electric heat conversion device; a heat storage device that stores the heat transfer medium and supplies and recovers the heat transfer medium to the rotary heat generator; and a heat utilization device that utilizes the heat of the heat transfer medium supplied from the heat storage device. [Effects of the Invention]

[0010] According to the present invention, the helical grooves in the rotor increase the surface area of ​​the rotor, expanding the contact area with the heat transfer medium, and enabling efficient heating of the heat transfer medium. Furthermore, the helical grooves that rotate with the rotor can apply a force to send the heat transfer medium in a direction parallel to the rotor's central axis, thereby reducing the power required to circulate the heat transfer medium. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of the configuration of an electric heating device according to the first embodiment. [Figure 2]This is a cross-sectional view of a part of the rotary heating device according to the first embodiment. [Figure 3] Figure 2 is a schematic cross-sectional view of the rotor as seen through the line A. [Figure 4] This is a schematic diagram of the heat storage system according to the first embodiment. [Figure 5] This is a cross-sectional view similar to Figure 2 of the rotary heating device according to the second embodiment. [Modes for carrying out the invention]

[0012] Hereinafter, an electric heat conversion device, a rotary heat generator, and a heat storage system according to one embodiment of the present invention will be described in detail with reference to the attached drawings. However, the present invention is not limited to the embodiment described below, and can be implemented with appropriate modifications without changing its essence. In the following figures, some components may be omitted for the sake of clarity.

[0013] Figure 1 is a schematic diagram of the configuration of an electric heat conversion device according to the first embodiment. As shown in Figure 1, the electric heat conversion device 10 comprises an electric motor 11 and a rotary heat heater 20 connected to the electric motor 11 via a shaft 12.

[0014] The electric motor 11 may be a permanent magnet type motor or an induction motor, or it may be of another type, and can be selected considering efficiency, controllability, etc.

[0015] Figure 2 is a cross-sectional view of a part of the rotary heating device according to the first embodiment. Figure 2 shows a cross-section of the vertical plane through which the central axis C extending horizontally in the rotary heating device 20 passes.

[0016] As shown in Figure 2, the rotary heat generator 20 comprises a rotor 22 that rotates around a central axis C, a container 23 that houses the rotor 22, and a heat transfer medium 24 that flows inside the container 23. The container 23 is housed in or supported by a frame (not shown).

[0017] The rotor 22 includes a part of the shaft 12 described above and a columnar main body 26 that is fixed to the outer periphery of a part of the shaft 12 and disposed inside the container 23. The rotor 22 is rotated by the electric motor 11 via the shaft 12. Further, although not particularly limited, the rotor 22 is generally made of stainless steel.

[0018] In the main body 26 of the rotor 22, there are provided a spiral groove 27 (groove) formed in an intermediate region R1 in the extending direction of the central axis C, and concavo-convex portions 28 respectively formed in both side regions R2 sandwiching the intermediate region R1 in the extending direction of the central axis C. Therefore, in the main body 26 of the rotor 22, the spiral groove 27 is formed not entirely but partially in the extending direction of the central axis C. Also, in the main body 26 of the rotor 22, the both side regions R2 are non-formation regions of the spiral groove 27 where the spiral groove 27 is not formed.

[0019] The spiral groove 27 is formed by a groove spirally extending around the central axis C on the columnar outer peripheral surface of the intermediate region R1 of the main body 26. Therefore, the spiral groove 27 functions similarly to a screw pump due to the rotation of the rotor 22, and is provided so as to be able to send out the heat medium 24 in the direction along the central axis C (from left to right in FIG. 2). In this embodiment, one spiral groove 27 is provided, but a plurality of spiral grooves 27 may be formed.

[0020] In this embodiment, concavo-convex portions 28 having the same shape are formed in the two both side regions R2 of the rotor 22. Therefore, in the following description, the concavo-convex portion 28 on the left side in FIG. 2 will be described, and the concavo-convex portion 28 on the right side in FIG. 2 will be denoted by the same reference numeral and the description may be omitted.

[0021] The concavo-convex portions 28 formed in the both side regions R2 include a plurality of convex portions 30 arranged at a predetermined interval in the rotation direction of the rotor 22 (the circumferential direction of the columnar main body 26), and the plurality of convex portions 30 arranged in the rotation direction are also arranged in a plurality of rows (four rows in FIG. 2) in the extending direction of the central axis C. Therefore, in the concavo-convex portion 28 in one of the both side regions R2, the convex portions 30 are arranged at a plurality of positions (four positions in FIG. 2) in the extending direction of the central axis C.

[0022] The convex portions 30 arranged in the rotation direction of the rotor 22 are provided, for example, in eight numbers at equal angles in the rotation direction as shown in FIG. 3. Note that the number of the convex portions 30 arranged in the rotation direction of the rotor 22 may be changed to a plurality such as ten, six, four, etc. other than eight.

[0023] The container 23 includes a peripheral wall 32 formed in a cylindrical shape centered on the central axis C, and side walls 33 provided on both sides of the peripheral wall 32 in the direction of the central axis C, and the rotor 22 and the heat medium 24 are arranged inside. A bearing 34 for rotatably supporting the shaft 12 is provided on the side wall 33 of the container 23.

[0024] A flow path 36 through which the heat medium 24 flows is formed in the container 23. The flow path 36 is formed by a gap (void) between the inner peripheral surface of the peripheral wall 32 of the container 23 and the outer peripheral surface of the rotor 22, and extends parallel to the central axis C. In the container 23, an inlet portion 32a for supplying the heat medium 24 to the flow path 36 from the lower left side in FIG. 3 of the peripheral wall 32, and an outlet portion 32b for discharging the heat medium 24 from the upper right side in FIG. 3 of the peripheral wall 32 are provided, and the heat medium 24 flows between the heat storage device 3 described later.

[0025] In this embodiment, a nitrate-based molten salt that is chemically inert is used as the heat medium 24. As the nitrate-based molten salt, a mixed salt of NaNO3 and KNO3 can be exemplified. The heat medium 24 is heated by absorbing heat generated by the friction between the rotating rotor 22 and the heat medium 24, and a fluid other than the molten salt (for example, a viscous fluid such as oil) may be used as long as it can be stably used in a high-temperature state after heating.

[0026] The electrothermal conversion device 10 can be used in the heat storage system 1 shown in FIG. 4. FIG. 4 is a schematic configuration diagram of a heat storage system according to the first embodiment. As shown in FIG. 4, the heat storage system 1 includes, in addition to the electrothermal conversion device 10, a power generation device 2 and a heat storage device 3.

[0027] The thermal energy storage system 1 is connected to the power grid L, and receives power from the power source G via the power grid L. The power grid L is the equipment that supplies the power generated by the power source G to the consumer D. The power source G consists of a group of generators connected to the power grid L. The power source G includes various types of power sources, such as conventional power sources like thermal power plants, nuclear power plants, and hydroelectric power plants, as well as renewable energy sources such as solar power plants and wind power plants.

[0028] When surplus power is generated in the power grid L, the control unit (not shown) controls the operation of the electric heat converter 10, which heats the heat transfer medium 24 to convert electrical energy into thermal energy. The heated, high-temperature heat transfer medium 24 is stored in the heat storage device 3. When there is no surplus power in the power grid L, the system is controlled to generate electricity in the power generation device 2 using the high-temperature heat transfer medium 24 supplied from the heat storage device 3, according to the electricity demand, and supply power to the power grid L.

[0029] The power generation device 2 is a device that generates electricity using the heat of the heat transfer medium 24 supplied from the heat storage device 3, and is connected to the power grid L. The power generation device 2 can be a known device, for example, consisting of a steam turbine and a generator. In the heat storage system 1, the power generation device 2 may be changed to another heat utilization device that uses the heat of the heat transfer medium 24.

[0030] The heat storage device 3 can be exemplified by a configuration comprising a high-temperature tank 3a that contains a relatively high-temperature heat transfer medium 24 and a low-temperature tank 3b that contains a relatively low-temperature heat transfer medium 24. In the heat storage device 3, the heat transfer medium 24 from the low-temperature tank 3b is supplied to the electric heat conversion device 10 (rotary heat generator 20), and the heat transfer medium 24 that has been heated to a high temperature by the electric heat conversion device 10 (rotary heat generator 20) is recovered (sent) to the high-temperature tank 3a and stored. In addition, the heat transfer medium 24 from the high-temperature tank 3a is supplied to the power generation device 2, and the heat transfer medium 24 that has been cooled by the heat utilization of the power generation device 2 is supplied to the low-temperature tank 3b and stored. A pump (not shown) is used for supplying and recovering the heat transfer medium 24.

[0031] Next, we will explain the conversion from electrical energy to thermal energy in the electric heating device 10.

[0032] In the electric heat conversion device 10, power is supplied from the power system L to the electric motor 11, and the rotor 22 of the rotary heat generator 20 is rotated via the shaft 12, converting electrical energy into mechanical energy. At this time, the electric motor 11 is controlled by variable speed control, for example, via an inverter.

[0033] As the rotor 22 rotates, thermal energy is generated by friction with the heat transfer medium 24 flowing through the channel 36. This thermal energy is absorbed by the heat transfer medium 24, causing it to heat up (its temperature rises). In this way, the mechanical energy that rotates the rotor 22 is converted into thermal energy for the heat transfer medium 24.

[0034] The heat transfer medium 24 is pressurized via a pump (not shown) and flows from the inlet 32a through the flow path 36 to the outlet 32b in the container 23. A helical groove 27 is formed in the main body 26 of the rotor 22, so the rotation of the rotor 22 functions similarly to a screw pump, applying a force that sends the heat transfer medium 24 in the flow path 36 from left to right in Figure 2 along the direction of the central axis C.

[0035] Here, if the rated power of the heat storage system 1 is in the 100MW class, the rotary heat generator 20 will need a container 23 with a diameter of 500 to 1000 mm and a length of 1000 to 10000 mm to obtain the desired thermal energy. In such a size, it is preferable to set the width of the flow path 36 to 5 to 20 mm. Furthermore, it can be exemplified that the width W and spacing S of the protrusions 30 are set to 10 to 100 mm and the height H of the protrusions 30 are set to 10 to 100 mm in the extension direction of the central axis C.

[0036] In the first embodiment described above, by forming helical grooves 27 and uneven surfaces 28 on the rotor 22, the surface area in contact with the heat transfer medium 24 can be increased, and the heat transfer medium 24 can be efficiently heated by the rotation of the rotor 22.

[0037] Furthermore, the rotating spiral groove 27 provides a pump function that delivers the heat transfer medium 24 along the flow direction of the flow path 36, thereby suppressing an increase in the pressure loss of the heat transfer medium 24 in the flow path 36. This reduces the power required for pumps and other equipment that deliver the heat transfer medium 24.

[0038] Incidentally, if the width of the flow path 36 is set to be narrow, the amount of heat generated by the heat transfer medium 24 can be increased. However, if the output is set to a large amount, as in the heat storage system 1, the rotor 22 and container 23 become larger, and the process of ensuring the machining precision required to narrow the width of the flow path 36 becomes a factor in increasing costs. Also, if the heat transfer medium 24 is used as molten salt in a high temperature range of 300 to 600°C, thermal expansion of the rotor 22 occurs, requiring even higher machining precision.

[0039] In contrast, by forming helical grooves 27 and uneven surfaces 28 on the rotor 22 as in this embodiment, the amount of heat generated by the heat transfer medium 24 can be increased without narrowing the width of the flow path 36. Furthermore, even if the rotor 22 expands due to the high temperature of the heat transfer medium 24, the flow path 36 can be easily maintained at a width greater than a predetermined width. As a result, high processing precision is not required for the rotor 22 and other components, thereby reducing manufacturing costs.

[0040] Furthermore, the rotation of the rotor 22 stirs the heat transfer medium 24 flowing through the channel 36, preventing the rotor 22 and the heat transfer medium 24 within the channel 36 from becoming locally hot. This allows the total amount of thermal energy received by the heat transfer medium 24 to increase while avoiding temperatures high enough to cause vaporization or decomposition, and enables miniaturization compared to conventional devices using resistance heaters, etc.

[0041] Furthermore, a helical groove 27 is formed in a portion of the rotor 22 in the direction of extension of the central axis C, and an uneven surface 28 is formed in the area where the helical groove 27 is not formed. By designing the rotor to adjust the formation range of the helical groove 27 and the uneven surface 28, the pump performance for delivering the heat transfer medium 24 can be adjusted by the helical groove 27, and the amount of heat generated by the heat transfer medium 24 due to the rotation of the rotor 22 can be adjusted. In addition, since multiple protrusions 30 are formed in the uneven surface 28 in the direction of rotation of the rotor 22 and the direction of extension of the central axis C, the amount of heat generated by the heat transfer medium 24 can be adjusted by adjusting the number, width, height, etc. of the protrusions 30. By making such adjustments, it is possible to avoid localized high temperatures in the rotor 22 and the heat transfer medium 24, and to suppress their deterioration.

[0042] Furthermore, since the electric heat conversion device 10 is configured with the aforementioned rotary heat generator 20, the electrical energy supplied to the electric motor 11 can be efficiently converted into thermal energy via the mechanical energy that rotates the shaft 12.

[0043] Furthermore, since the heat storage system 1 is configured with the aforementioned rotary heat generator 20, it is possible to store surplus electricity such as renewable energy and effectively utilize the stored surplus electricity during times when electricity is insufficient.

[0044] [Second Embodiment] Next, a second embodiment of the present invention will be described with reference to Figure 5. In the following description, the same reference numerals may be used for components that are the same as or equivalent to those in the first embodiment, and their descriptions may be omitted or simplified.

[0045] Figure 5 is a cross-sectional view of the rotary heat generator according to the second embodiment, similar to Figure 2. In the second embodiment, the configuration of the rotor 22 is changed compared to the first embodiment. As shown in Figure 5, the outer circumferential surface of the main body 40 of the rotor 22 is formed in a tapered shape that narrows from the upstream side to the downstream side (from left to right in Figure 5) in the flow direction of the heat transfer medium 24. As the heat transfer medium 24 flows through the flow path 36, the amount of thermal energy it receives increases and the temperature rises, so the downstream side becomes relatively hotter than the upstream side.

[0046] In general, in a rotary heat generator 20 where the heat transfer medium 24 is heated by friction with a rotating rotor 22, if the heat transfer medium 24 is molten salt, the amount of heat transferred from the rotor 22 to the heat transfer medium 24 is proportional to the temperature difference between the rotor 22 and the heat transfer medium 24. Therefore, when the heat transfer medium 24 becomes hot, the amount of heat transferred from the rotor 22 to the heat transfer medium 24 decreases, which can cause the outer surface of the rotor 22 to overheat and deteriorate.

[0047] In this regard, in the second embodiment, since the main body 40 of the rotor 22 has a tapered shape as described above, the peripheral speed of the rotor 22 can be reduced on the downstream side where the temperature is high, thereby reducing the amount of heat generated per unit area of ​​the rotor 22 and preventing overheating. Furthermore, by reducing the peripheral speed of the rotor 22 on the downstream side where the temperature is high, the amount of frictional heat generated on the downstream side can be reduced, thereby preventing overheating of the rotor 22. Moreover, due to the tapered shape of the main body 40, the width of the flow path 36 can be increased on the downstream side compared to the upstream side, increasing the heat capacity of the heat transfer medium 24, which also helps to prevent overheating of the rotor 22.

[0048] As a result, in the second embodiment, even when the temperature downstream of the heat transfer medium 24, which becomes molten salt, reaches around 600°C, material degradation of the rotor 22 can be suppressed, eliminating the need to improve durability or select expensive materials for the rotor 22, thereby reducing costs.

[0049] Furthermore, the present invention is not limited to the embodiments described above and can be implemented with various modifications. In the embodiments described above, the size, shape, etc., shown in the accompanying drawings are not limited thereto and can be appropriately modified within the scope that allows the present invention to exert its effects. In addition, the present invention can be implemented with appropriate modifications as long as it does not deviate from the scope of the object of the present invention.

[0050] In the first embodiment described above, the formation range of the helical grooves 27 and the uneven surfaces 28 in the rotor 22 is an example, and various modifications are possible. For example, the formation range of the helical grooves 27 and the uneven surfaces 28 in the extension direction of the central axis C may be expanded or reduced, the formation of the uneven surfaces 28 in one of the side regions R2 may be omitted, or the formation range of the helical grooves 27 may be set to multiple locations in the extension direction of the central axis C.

[0051] Furthermore, in the rotor 22 of the first embodiment described above, the formation of the uneven portion 28 may be omitted.

[0052] Furthermore, the tapered main body portion 40 in the second embodiment may also be formed with the spiral groove 27 and the uneven portion 28 in the first embodiment. [Explanation of Symbols]

[0053] 1: Thermal storage system 2: Power generation equipment (heat utilization equipment) 3: Heat storage device 10: Electric heating device 11: Electric motor 12: Shaft 20: Rotary heating machine 22: Rotor 23: Container 24: Heat medium 27: Spiral groove (groove) 28: Uneven part 30: Convex part 36: Flow channel C: Central axis

Claims

1. A rotor that rotates around a predetermined central axis, A container for housing the rotor, A rotary heating device comprising a liquid heat transfer medium that flows inside the container and is heated by friction with the rotating rotor, A rotary heating device characterized in that grooves extending spirally around the central axis are formed on the outer circumferential surface of the rotor.

2. The rotary heating device according to claim 1, characterized in that the groove is formed in a part of the rotor in the direction of extension of the central axis.

3. The rotary heating device according to claim 2, characterized in that an uneven portion is formed in the region of the rotor where the groove is not formed.

4. The rotary heating device according to claim 3, characterized in that the aforementioned uneven portion comprises a plurality of protrusions arranged at predetermined intervals in the rotational direction of the rotor.

5. The rotary heating device according to claim 4, characterized in that the protrusions in the uneven portion are arranged at multiple locations in the direction of extension of the central axis.

6. A rotor that rotates around a predetermined central axis, A container for housing the rotor, A rotary heating device comprising a liquid heat transfer medium that flows inside the container and is heated by friction with the rotating rotor, The rotary heating device is characterized in that the outer circumferential surface of the rotor is formed in a tapered shape that narrows from the upstream side to the downstream side in the flow direction of the heat transfer medium.

7. An electric heating device characterized by comprising a rotary heating element according to any one of claims 1 to 6, and an electric motor that rotates the rotor via a shaft.

8. The electric heating device according to claim 7 above, A heat storage device for storing the heat transfer medium and supplying and recovering the heat transfer medium to the rotary heat generator, A heat storage system characterized by comprising a heat utilization device that utilizes the heat of the heat transfer medium supplied from the heat storage device.

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