Power generation system with medium-temperature photo-thermal heat storage coupled with high-temperature electric heating

Abstract

The invention relates to the technical field of photo-thermal power generation and fused salt electric heating, and discloses a medium-temperature photo-thermal heat storage coupled high-temperature electric heating power generation system which comprises a light condensation and heat collection module, an energy storage module and a power generation module. A medium-temperature energy storage device and a high-temperature energy storage device in the energy storage module are connected with a heat exchange inlet and a heat exchange outlet of the light condensation and heat collection module respectively, and the electric heating device is connected with the high-temperature energy storage device. In the power generation module, a water treatment assembly supplies water to a steam treatment assembly, the steam treatment assembly supplies steam to a power generation assembly, an outlet of a high-temperature energy storage device is connected with a working medium inlet of the steam treatment assembly, and an inlet of a medium-temperature energy storage device is connected with a working medium outlet of the steam treatment assembly. Fused salt is heated through the light condensation and heat collection module, and the fused salt is subjected to secondary heating through the electric heating device and then exchanges heat with steam, so that the fused salt enters the power generation module. Compared with an existing groove type photo-thermal power station, the circulating efficiency is higher; compared with an existing tower type photo-thermal power station, the tower type photo-thermal power station is higher in photo-thermal conversion efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of solar thermal power generation and molten salt electric heating, and in particular to a power generation system that combines medium-temperature solar thermal heat storage with high-temperature electric heating. Background Art

[0002] As the global energy structure transforms from fossil energy to renewable energy, the proportion of renewable energy continues to increase. However, photovoltaic power generation, wind power generation, etc. are easily affected by the external natural environment, and power generation will be intermittent and volatile. This has to some extent restricted the large-scale and efficient use of renewable energy and the stable operation of the power grid.

[0003] Concentrated solar power generation (CSP) is a renewable energy generation technology that uses solar energy to generate electricity and has energy storage capabilities. It offers stable and reliable power output and superior regulation performance. It can serve as the primary generator in a power system to carry baseload loads and participate in primary and secondary frequency regulation, reducing the power system's demand for energy storage power station capacity. It primarily consists of a concentrating solar collector module, a heat storage module, and a power generation module. Its core operating process involves concentrating solar energy through the concentrating solar collector module, converting it into thermal energy and storing it in the thermal storage module. During power generation, the thermal energy stored in the thermal storage module drives the steam turbine in the power generation module, which in turn drives the generator to generate electricity.

[0004] The most common CSP plants are trough and tower CSP. Trough CSP uses parabolic trough reflectors to collect solar energy and convert it into heat. This heat is then transferred to a thermal storage module using a heat transfer medium called thermal oil. The heat then heats water to form steam, which then enters a steam turbine to generate electricity. However, the operating temperature of thermal oil is 293-393°C, and the steam pressure is approximately 10 MPa. Limited by the temperature and pressure of the thermodynamic cycle, the power cycle efficiency is low, reaching only 38.5%.

[0005] Tower-type solar thermal power plants utilize a large number of heliostats to reflect sunlight onto the top of a solar collector tower. This heat is then exchanged with molten salt, a heat transfer medium, and stored in a thermal storage module. This heat then heats water into steam, which then enters a steam turbine to generate electricity. The molten salt operates at a temperature of 290-565°C, with a steam pressure of approximately 14 MPa. While the power cycle efficiency can reach 43.1%, the high temperature significantly increases radiation, convection, and heat transfer losses in the collector tower, reducing the efficiency of the solar-to-thermal conversion process. Summary of the Invention

[0006] In view of this, the present invention provides a power generation system that combines medium-temperature solar thermal heat storage with high-temperature electric heating to solve the problems of low power cycle efficiency of existing trough-type solar thermal power stations and low solar-to-thermal conversion efficiency of tower-type solar thermal power stations.

[0007] In a first aspect, the present invention provides a power generation system combining medium-temperature solar thermal energy storage with high-temperature electric heating, comprising:

[0008] A concentrating and heat-collecting module, wherein the concentrating and heat-collecting module is a trough-type photothermal device or a tower-type photothermal device;

[0009] An energy storage module, comprising a medium-temperature energy storage device, a high-temperature energy storage device, and an electric heating device, wherein the outlet of the medium-temperature energy storage device is connected to the heat exchange inlet of the concentrating and heat collecting module, the inlet of the high-temperature energy storage device is connected to the heat exchange outlet of the concentrating and heat collecting module, and the electric heating device is connected to the high-temperature energy storage device;

[0010] A power generation module, comprising: a water treatment component, a steam treatment component, and a power generation component, wherein the outlet of the water treatment component is connected to the fluid inlet of the steam treatment component, the fluid outlet of the steam treatment component is connected to the power generation component, the outlet of the high-temperature energy storage device is connected to the working fluid inlet of the steam treatment component, and the inlet of the medium-temperature energy storage device is connected to the working fluid outlet of the steam treatment component;

[0011] The low-temperature molten salt in the medium-temperature energy storage device absorbs heat energy after heat exchange with the concentrating solar collector module to become a heated molten salt. The heated molten salt is heated by the electric heating device to become a high-temperature molten salt and then stored in the high-temperature energy storage device, and then enters the steam treatment component; or the heated molten salt is directly stored in the high-temperature energy storage device, and then heated by the electric heating device to become a high-temperature molten salt and then enters the steam treatment component. The high-temperature molten salt exchanges heat with the steam in the steam treatment component, and the high-temperature molten salt is cooled to become a low-temperature molten salt and then enters the medium-temperature energy storage device. The steam is heated and enters the power generation component.

[0012] Beneficial effects

[0013] Compared to existing trough-type CSP plants, low-temperature molten salt first exchanges heat with high-temperature thermal oil, then undergoes secondary heating via an electric heater before starting heat exchange with steam. Because the operating temperature of molten salt is higher than that of thermal oil, secondary heating via an electric heater can raise the temperature of the molten salt during heat exchange with steam, thereby improving the system's power cycle efficiency and enabling capacity expansion and efficiency enhancement of CSP plants.

[0014] Compared with the existing tower-type solar thermal power station, since an electric heating device is set up to perform secondary heating of the molten salt, the collection temperature of the concentrating solar collector module can be reduced, thereby reducing the radiation loss, convection loss and heat transfer loss of the solar collector tower, and effectively improving the photothermal conversion efficiency.

[0015] In an optional embodiment, the energy storage solar thermal power generation coupled with molten salt electric heating power generation system also includes a temperature-raising molten salt energy storage device, the inlet of the temperature-raising molten salt energy storage device is connected to the heat exchange outlet of the concentrating and thermal collection module, and its outlet is connected to the electric heating device, and the electric heating device is also connected to the inlet of the high-temperature energy storage device.

[0016] In an optional embodiment, the temperature-raising molten salt energy storage device, the electric heating device and the high-temperature energy storage device are integrated into a molten salt electric heating storage device.

[0017] Beneficial effects

[0018] The molten salt electric heating storage device is functionally equivalent to the temperature-raising molten salt energy storage device, the electric heating device and the high-temperature energy storage device. Integrating them into one helps to simplify the system structure.

[0019] In an optional embodiment, the electric heating device or the molten salt electric heating storage device is electrically connected to a wind power generation module and / or a photovoltaic power generation module.

[0020] Beneficial effects

[0021] Using clean energy such as wind power and / or photovoltaic power generation is more environmentally friendly.

[0022] In an optional embodiment, the power generation component includes: a first steam turbine, a reheater, a second steam turbine and a generator, the steam inlet of the first steam turbine is connected to the fluid outlet of the steam processing component, the fluid inlet of the reheater is connected to the steam outlet of the first steam turbine, and its fluid outlet is connected to the steam inlet of the second steam turbine, and the working fluid inlet of the reheater is connected to the outlet of the high-temperature energy storage device, and its working fluid outlet is connected to the inlet of the medium-temperature energy storage device, and the first steam turbine and the second steam turbine are also connected to the generator.

[0023] In an optional embodiment, the steam processing component includes: a preheater, an evaporator and a superheater connected in sequence, the working fluid outlet of the preheater is connected to the inlet of the medium-temperature energy storage device, the working fluid inlet of the superheater is connected to the outlet of the high-temperature energy storage device, and its fluid outlet is connected to the steam inlet of the first steam turbine.

[0024] In an optional embodiment, the steam inlet of the second steam turbine is connected to the fluid outlet of the superheater.

[0025] In an optional embodiment, the water treatment component includes: a condenser, a water pump, a heater and a deaerator connected in sequence, the condenser is connected to the steam outlet of the second steam turbine, and the outlet of the deaerator is connected to the fluid inlet of the preheater.

[0026] In an optional embodiment, the trough-type photothermal device includes: a trough-type reflector group and a heat exchanger, wherein the outlet of the trough-type reflector group is connected to the first working fluid inlet of the heat exchanger, and its inlet is connected to the first working fluid outlet of the heat exchanger, the second working fluid inlet of the heat exchanger is connected to the outlet of the medium-temperature energy storage device, and its second working fluid outlet is connected to the inlet of the high-temperature energy storage device.

[0027] In an optional embodiment, the tower-type solar thermal device includes: a heliostat group and a heat collecting tower, the heliostat group reflects sunlight to the heat collecting tower, the working fluid inlet of the heat collecting tower is connected to the outlet of the medium-temperature energy storage device, and its working fluid outlet is connected to the inlet of the high-temperature energy storage device. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 This is a schematic diagram of Example 1 of a power generation system for medium-temperature solar thermal energy storage coupled with high-temperature electric heating according to the present invention;

[0030] Figure 2 This is a schematic diagram of Example 2 of a power generation system for medium-temperature solar thermal energy storage coupled with high-temperature electric heating according to the present invention;

[0031] Figure 3 This is a schematic diagram of Example 3 of a power generation system for medium-temperature solar thermal energy storage coupled with high-temperature electric heating according to the present invention;

[0032] Figure 4 This is a schematic diagram of Example 4 of a power generation system for medium-temperature solar thermal energy storage coupled with high-temperature electric heating according to the present invention;

[0033] Figure 5 This is a schematic diagram of Example 5 of a power generation system for medium-temperature solar thermal storage coupled with high-temperature electric heating according to the present invention;

[0034] Figure 6 This is a schematic diagram of Example 6 of the power generation system of medium-temperature solar thermal heat storage coupled with high-temperature electric heating of the present invention.

[0035] Description of reference numerals:

[0036] 11. Trough reflector assembly, 12. Heat exchanger, 13. Thermal oil pump, 14. Heliostat assembly, 15. Thermal collecting tower;

[0037] 21. Medium-temperature energy storage device, 22. High-temperature energy storage device, 23. Electric heating device, 24. Heating molten salt energy storage device, 25. Molten salt electric heating storage device;

[0038] 31. Wind power generation module, 32. Photovoltaic power generation module;

[0039] 411, condenser, 412, water pump, 413, heater, 414, deaerator, 421, preheater, 422, evaporator, 423, superheater, 431, first steam turbine, 432, reheater, 433, second steam turbine, 434, generator;

[0040] 5. Three-way valve;

[0041] 6. Molten salt pump. DETAILED DESCRIPTION

[0042] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0043] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0044] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0045] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0046] Example 1

[0047] The following combination Figure 1 , describing embodiments of the present invention.

[0048] According to an embodiment of the present invention, on the one hand, a power generation system combining medium-temperature solar thermal storage with high-temperature electric heating is provided, comprising: a concentrating solar collector module, an energy storage module, and a power generation module. The concentrating solar collector module is a trough-type solar thermal device or a tower-type solar thermal device. The energy storage module comprises a medium-temperature energy storage device 21, a high-temperature energy storage device 22, and an electric heating device 23. The outlet of the medium-temperature energy storage device 21 is connected to the heat exchange inlet of the concentrating solar collector module, the inlet of the high-temperature energy storage device 22 is connected to the heat exchange outlet of the concentrating solar collector module, and the electric heating device 23 is connected to the high-temperature energy storage device 22. The power generation module comprises: a water treatment component, a steam treatment component, and a power generation component. The outlet of the water treatment component is connected to the fluid inlet of the steam treatment component, the fluid outlet of the steam treatment component is connected to the power generation component, the outlet of the high-temperature energy storage device 22 is connected to the working fluid inlet of the steam treatment component, and the inlet of the medium-temperature energy storage device 21 is connected to the working fluid outlet of the steam treatment component. The low-temperature molten salt in the medium-temperature energy storage device 21 absorbs heat energy after heat exchange with the concentrating solar collector module to become a heated molten salt. The heated molten salt is heated by the electric heating device 23 to become a high-temperature molten salt and then stored in the high-temperature energy storage device 22, and then enters the steam treatment component; or the heated molten salt is directly stored in the high-temperature energy storage device 22, and then heated by the electric heating device 23 to become a high-temperature molten salt and then enters the steam treatment component. The high-temperature molten salt exchanges heat with the steam in the steam treatment component, and the high-temperature molten salt is cooled to become a low-temperature molten salt and then enters the medium-temperature energy storage device 21. The steam is heated and enters the power generation component.

[0049] The concentrating solar collector module can be a trough-type solar thermal device or a tower-type solar thermal device. In this embodiment, a trough-type solar thermal device is used. Specifically, the trough-type solar thermal device includes a trough-type reflector assembly 11 and a heat exchanger 12. The outlet of the trough-type reflector assembly 11 is connected to the first working fluid inlet of the heat exchanger 12, and its inlet is connected to the first working fluid outlet of the heat exchanger 12. The second working fluid inlet of the heat exchanger 12 is connected to the outlet of the medium-temperature energy storage device 21, and its second working fluid outlet is connected to the inlet of the high-temperature energy storage device 22.

[0050] The first working fluid is thermal oil, operating at a temperature of 293-393°C, and the second working fluid is molten salt, operating at a temperature of 290-565°C. Trough reflector assembly 11 concentrates solar energy to heat the low-temperature thermal oil, which then enters heat exchanger 12 for heat exchange with the low-temperature molten salt. The high-temperature thermal oil cools down to low-temperature thermal oil before returning to trough reflector assembly 11, while the low-temperature molten salt is heated to warmed molten salt, which then flows out of heat exchanger 12.

[0051] The medium-temperature energy storage device 21 and the high-temperature energy storage device 22 in the energy storage module are both devices for storing molten salt. The electric heating device 23 can heat the molten salt, meaning that the molten salt is heated twice, passing through the heat exchanger 12 and the electric heating device 23. Specifically, the electric heating device 23 can be located at the inlet or outlet of the high-temperature energy storage device 22. If the electric heating device 23 is located at the inlet of the high-temperature energy storage device 22, the low-temperature molten salt in the medium-temperature energy storage device 21 is transported by the molten salt pump 6 to the heat exchanger 12, where it undergoes heat exchange with the high-temperature thermal oil to form heated molten salt. It then passes through the electric heating device 23 for secondary heating before entering the high-temperature energy storage device 22. If the electric heating device 23 is located at the outlet of the high-temperature energy storage device 22, the low-temperature molten salt in the medium-temperature energy storage device 21 is transported by the molten salt pump 6 to the heat exchanger 12, where it undergoes heat exchange with the high-temperature thermal oil to form heated molten salt. It then enters the high-temperature energy storage device 22 and undergoes secondary heating by the electric heating device 23. Both of these configurations are feasible, as long as the molten salt is heated twice before entering the steam treatment component for heat exchange with the steam.

[0052] The power generation module consists of a water treatment component, a steam treatment component, and a power generation component. The power generation component uses steam to generate electricity, using water as the raw material. The water treatment component pre-treats the water before it enters the steam treatment component. The steam treatment component has two channels: one for the working medium (molten salt) and the other for the fluid (water / steam). The water undergoes multiple heat exchanges with the high-temperature molten salt, vaporizing it into steam. This steam is then gradually heated up before entering the power generation component to generate electricity.

[0053] The working fluid used in conventional trough-type solar thermal power plants is thermal oil. Due to the inherent properties of thermal oil, its operating temperature is relatively low (293-393°C). After heat exchange with steam, the steam pressure can only reach 10MPa, resulting in a cycle efficiency of only about 38.5%. The medium-temperature solar thermal heat storage coupled with high-temperature electric heating power generation system uses two working fluids, thermal oil and molten salt. The operating temperature of the molten salt can reach 290-565°C. Although it cannot reach a higher operating temperature after heat exchange with the thermal oil of the trough-type solar thermal device, the subsequent electric heating device 23 can heat the molten salt to about 550°C, thereby increasing the effective energy of the molten salt. In this way, the molten salt temperature is higher during heat exchange with steam, the steam pressure is increased, the conversion efficiency of thermal energy to electrical energy is increased, and high-quality conversion of electrical energy is achieved. The power cycle efficiency is improved and can reach about 43.5%, thereby achieving the expansion and efficiency improvement of the solar thermal power station.

[0054] In one embodiment, the energy storage power generation system also includes a temperature-raising molten salt energy storage device 24, the inlet of the temperature-raising molten salt energy storage device 24 is connected to the heat exchange outlet of the concentrating and thermal collection module, and its outlet is connected to the electric heating device 23, and the electric heating device 23 is also connected to the inlet of the high-temperature energy storage device 22.

[0055] After heat exchange in the heat exchanger 12 , the low-temperature molten salt becomes high-temperature molten salt, which first enters the temperature-increasing molten salt energy storage device 24 , and then is heated by the electric heating device 23 before entering the high-temperature energy storage device 22 .

[0056] In order to facilitate the circulation of molten salt, molten salt pumps 6 are provided at the outlets of the medium-temperature energy storage device 21 , the temperature-raising molten salt energy storage device 24 and the high-temperature energy storage device 22 .

[0057] In one embodiment, the water treatment assembly includes: a condenser 411, a water pump 412, a heater 413 and a deaerator 414 connected in sequence, the condenser 411 is connected to the steam outlet of the second steam turbine 433, and the outlet of the deaerator 414 is connected to the fluid inlet of the preheater 421.

[0058] The steam output from the steam outlet of the second steam turbine 433 is condensed in the condenser 411 to become water. After a series of heating and evaporation processes, the water can drive the steam turbine, which means that water resources are recycled in this system. Of course, in other embodiments, the condenser 411 can be omitted, and water can be directly supplied to the heater 413 from a water source.

[0059] The water pump 412 can pump water from the condenser 411 to the heater 413, and then the heater 413 can preheat the water so that it can be easily vaporized and evaporated. The deaerator 414 can remove dissolved oxygen in the water.

[0060] In one embodiment, the steam processing component includes: a preheater 421, an evaporator 422 and a superheater 423 connected in sequence, the working fluid outlet of the preheater 421 is connected to the inlet of the medium-temperature energy storage device 21, the working fluid inlet of the superheater 423 is connected to the outlet of the high-temperature energy storage device 22, and its fluid outlet is connected to the steam inlet of the first steam turbine 431.

[0061] Preheater 421, evaporator 422, and superheater 423 all have two channels: a molten salt channel and a water / steam channel. Specifically, water enters preheater 421 from deaerator 414, where it is heated again. It then vaporizes into water vapor in evaporator 422, and then heats up in superheater 423. The water / steam flows from preheater 421 to evaporator 422 and then to superheater 423. Since the heat energy required for water / steam gradually increases as it circulates, while the high-temperature molten salt exiting high-temperature energy storage device 22 has the highest temperature and carries the most heat energy, the molten salt flows in the opposite direction to the water / steam: from superheater 423 to evaporator 422 and then to preheater 421. A three-way valve 5 is provided between the evaporator 422 and the superheater 423. After the molten salt in the reheater 432 exchanges heat with the steam, it still carries some heat energy. This molten salt can be recovered and reused through the three-way valve 5. After passing through the superheater 423, the evaporator 422, and the preheater 421, the high-temperature molten salt is converted to low-temperature molten salt and returned to the medium-temperature energy storage device 21.

[0062] In one embodiment, the power generation component includes: a first steam turbine 431, a reheater 432, a second steam turbine 433 and a generator 434, the steam inlet of the first steam turbine 431 is connected to the fluid outlet of the steam treatment component, the fluid inlet of the reheater 432 is connected to the steam outlet of the first steam turbine 431, and its fluid outlet is connected to the steam inlet of the second steam turbine 433, and the working fluid inlet of the reheater 432 is connected to the outlet of the high-temperature energy storage device 22, and its working fluid outlet is connected to the inlet of the medium-temperature energy storage device 21, and the first steam turbine 431 and the second steam turbine 433 are also connected to the generator 434.

[0063] Both the first steam turbine 431 and the second steam turbine 433 utilize steam pressure to drive the generator 434 to work, but the first steam turbine 431 is a high-pressure steam turbine and the second steam turbine 433 is a medium-pressure steam turbine. Setting up two-stage steam turbines can make full use of the steam pressure.

[0064] Furthermore, the molten salt pump 6 at the outlet of the high-temperature energy storage device 22 is connected to the three-way valve 5, and the superheater 423 and the reheater 432 are both connected to the three-way valve 5. That is to say, after the steam works in the first steam turbine 431, it enters the reheater 432 to increase the temperature and pressure again, and then enters the second steam turbine 433 to work again.

[0065] The operation process of the power generation system of medium-temperature solar thermal energy storage coupled with high-temperature electric heating provided in this embodiment is described as follows:

[0066] The low-temperature molten salt in the medium-temperature energy storage device 21 enters the heat exchanger 12 to exchange heat with the high-temperature heat transfer oil. After absorbing heat energy, it becomes heated molten salt and enters the heated molten salt energy storage device 24. Then, it is heated for the second time by the electric heating device 23 to become high-temperature molten salt and enter the high-temperature energy storage device 22.

[0067] When power generation is required, water pump 412 pumps water to heater 413, which then passes through deaerator 414 and into preheater 421. The water then passes through preheater 421, evaporator 422, and superheater 423. Simultaneously, the high-temperature molten salt in high-temperature energy storage device 22 is delivered to superheater 423 by molten salt pump 6, passing through superheater 423, evaporator 422, and preheater 421. The water / steam exchanges heat with the molten salt, and the high-temperature steam from superheater 423 enters first steam turbine 431, driving it. After being reheated in reheater 432, it enters second steam turbine 433, also driving it. The first and second steam turbines 431, 433 drive generator 434 to generate electricity.

[0068] Example 2

[0069] like Figure 2 As shown, the difference between this embodiment and embodiment 1 is that the concentrating solar collector module is a tower-type solar thermal device, and the remaining structures are the same as those of the energy storage power generation system in embodiment 1, which will not be repeated.

[0070] Furthermore, the tower-type solar thermal device includes: a heliostat group 14 and a heat collecting tower 15. The heliostat group 14 reflects sunlight to the heat collecting tower 15. The working fluid inlet of the heat collecting tower 15 is connected to the outlet of the medium-temperature energy storage device 21, and its working fluid outlet is connected to the inlet of the high-temperature energy storage device 22.

[0071] The heliostat group 14 can reflect sunlight to the heat collecting tower 15 , and the low-temperature molten salt in the medium-temperature energy storage device 21 enters the heat collecting tower 15 for heat exchange, absorbs heat energy and heats up before entering the heated molten salt energy storage device 24 for storage.

[0072] Conventional tower-type solar thermal power stations often increase the radiation loss, convection loss and heat transfer loss of the heat collecting tower 15 due to high temperature, and the light-to-heat conversion efficiency during the concentration and heat collection process is low. The medium-temperature solar thermal heat storage coupled with high-temperature electric heating power generation system uses the electric heating device 23 to heat the molten salt for a second time, so the heat collection temperature of the heat collecting tower 15 is reduced (the temperature is about 420°C). In actual implementation, if it is an already built tower-type solar thermal power station, the heat collection temperature of the heat collecting tower 15 can be reduced by increasing the flow rate of molten salt, thereby reducing the radiation loss, convection loss and heat transfer loss of the heat collecting tower 15 and improving the light-to-heat conversion efficiency; if it is a new tower-type solar thermal power station to be built, the height of the heat collecting tower 15 can be reduced, which not only improves the light-to-heat conversion efficiency but also reduces the construction cost.

[0073] Example 3

[0074] The difference between this embodiment and Example 1 is that this embodiment is provided with a molten salt electric heating storage device 25, and uses the electric energy of the wind power generation module 31 and / or the photovoltaic power generation module 32 to heat the molten salt. The remaining structures are the same as the structure of the energy storage power generation system in Example 1 and will not be repeated here.

[0075] Specifically, such as Figure 3 As shown, the temperature-raising molten salt energy storage device 24, the electric heating device 23, and the high-temperature energy storage device 22 are integrated into a molten salt electric heating storage device 25. The high-temperature molten salt output from the heat exchanger 12 directly enters the molten salt electric heating storage device 25, and the secondary electric heating of the molten salt is also carried out in the molten salt electric heating storage device 25.

[0076] Furthermore, when wind power generation module 31 and / or photovoltaic power generation module 32 generate electricity, some of the electricity generated is wasted. This wasted electricity can be supplied to molten salt electric heating storage device 25 for electrical heating, thereby meeting the electrical energy required for electrical heating. Using renewable energy for power supply is more environmentally friendly and can also be used to absorb the wasted electricity generated by renewable energy generation, thereby fully utilizing the electrical energy.

[0077] Of course, the electric heating device 23 in Example 1 can also be powered by the wind power generation module 31 and / or the photovoltaic power generation module 32 .

[0078] Example 4

[0079] like Figure 4 As shown, the difference between this embodiment and embodiment 3 is that the concentrating solar collector module is a tower-type solar thermal device, and the remaining structures are the same as those of the energy storage power generation system in embodiment 3 and will not be repeated.

[0080] Example 5

[0081] The difference between this embodiment and Embodiment 3 is that the steam inlet of the second steam turbine 433 is connected to the fluid outlet of the superheater 423 .

[0082] Specifically, such as Figure 5 As shown, the working medium outlet of the superheater 423 is connected to a three-way valve 5, which in turn connects the steam inlet of the first steam turbine 431 and the steam inlet of the second steam turbine 433. Due to the instability and fluctuation of wind power and photovoltaic power generation, when the molten salt temperature in the molten salt electric heating storage device 25 is low, the steam entering the first steam turbine 431 (high-pressure steam turbine) may be damaged due to insufficient steam temperature and low pressure. Therefore, in this operating condition, all the steam can be supplied to the second steam turbine 433 (medium-pressure steam turbine).

[0083] Example 6

[0084] like Figure 6 As shown, the difference between this embodiment and embodiment 5 is that the solar thermal collection module is a tower-type solar thermal device, and the remaining structures are the same as those of the energy storage power generation system in embodiment 5, which will not be repeated.

[0085] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A medium-temperature solar thermal energy storage coupled with high-temperature electric heating power generation system, characterized in that: include: A concentrating and heat-collecting module, wherein the concentrating and heat-collecting module is a trough-type photothermal device or a tower-type photothermal device; An energy storage module, the energy storage module comprising a medium-temperature energy storage device (21), a high-temperature energy storage device (22) and an electric heating device (23), the outlet of the medium-temperature energy storage device (21) being connected to the heat exchange inlet of the concentrating and heat collecting module, the inlet of the high-temperature energy storage device (22) being connected to the heat exchange outlet of the concentrating and heat collecting module, and the electric heating device (23) being connected to the high-temperature energy storage device (22); A power generation module, comprising: a water treatment component, a steam treatment component, and a power generation component, wherein the outlet of the water treatment component is connected to the fluid inlet of the steam treatment component, the fluid outlet of the steam treatment component is connected to the power generation component, the outlet of the high-temperature energy storage device (22) is connected to the working fluid inlet of the steam treatment component, and the inlet of the medium-temperature energy storage device (21) is connected to the working fluid outlet of the steam treatment component; The low-temperature molten salt in the medium-temperature energy storage device (21) absorbs heat energy after heat exchange with the concentrating solar collector module and becomes a heated molten salt. The heated molten salt is heated by the electric heating device (23) to become a high-temperature molten salt and then stored in the high-temperature energy storage device (22), and then enters the steam treatment component; or the heated molten salt is directly stored in the high-temperature energy storage device (22), and then heated by the electric heating device (23) to become a high-temperature molten salt and then enters the steam treatment component. The high-temperature molten salt exchanges heat with the steam in the steam treatment component, and the high-temperature molten salt is cooled to become a low-temperature molten salt and then enters the medium-temperature energy storage device (21). The steam is heated and enters the power generation component.

2. The medium-temperature solar thermal energy storage coupled with high-temperature electric heating power generation system according to claim 1 is characterized in that: It also includes a temperature-raising molten salt energy storage device (24), the inlet of the temperature-raising molten salt energy storage device (24) is connected to the heat exchange outlet of the concentrating heat collection module, and the outlet is connected to the electric heating device (23), and the electric heating device (23) is also connected to the inlet of the high-temperature energy storage device (22).

3. The medium-temperature solar thermal energy storage coupled with high-temperature electric heating power generation system according to claim 2 is characterized in that: The temperature-raising molten salt energy storage device (24), the electric heating device (23) and the high-temperature energy storage device (22) are integrated into a molten salt electric heating storage device (25).

4. The medium-temperature solar thermal energy storage coupled with high-temperature electric heating power generation system according to claim 3 is characterized in that: The electric heating device (23) or the molten salt electric heating storage device (25) is electrically connected to the wind power generation module (31) and / or the photovoltaic power generation module (32).

5. The medium-temperature solar thermal energy storage coupled with high-temperature electric heating power generation system according to claim 1 is characterized in that: The power generation component comprises: a first steam turbine (431), a reheater (432), a second steam turbine (433) and a generator (434); the steam inlet of the first steam turbine (431) is connected to the fluid outlet of the steam processing component; the fluid inlet of the reheater (432) is connected to the steam outlet of the first steam turbine (431); its fluid outlet is connected to the steam inlet of the second steam turbine (433); the working fluid inlet of the reheater (432) is connected to the outlet of the high-temperature energy storage device (22); its working fluid outlet is connected to the inlet of the medium-temperature energy storage device (21); the first steam turbine (431) and the second steam turbine (433) are also connected to the generator (434).

6. The medium-temperature solar thermal energy storage coupled with high-temperature electric heating power generation system according to claim 5 is characterized in that: The steam processing assembly comprises: a preheater (421), an evaporator (422) and a superheater (423) connected in sequence, the working fluid outlet of the preheater (421) being connected to the inlet of the medium-temperature energy storage device (21), the working fluid inlet of the superheater (423) being connected to the outlet of the high-temperature energy storage device (22), and the fluid outlet thereof being connected to the steam inlet of the first steam turbine (431).

7. The medium-temperature solar thermal energy storage coupled with high-temperature electric heating power generation system according to claim 6 is characterized in that: The steam inlet of the second steam turbine (433) is connected to the fluid outlet of the superheater (423).

8. The medium-temperature solar thermal energy storage coupled with high-temperature electric heating power generation system according to claim 6 is characterized in that: The water treatment component includes: a condenser (411), a water pump (412), a heater (413) and a deaerator (414) connected in sequence, the condenser (411) is connected to the steam outlet of the second steam turbine (433), and the outlet of the deaerator (414) is connected to the fluid inlet of the preheater (421).

9. The medium-temperature solar thermal energy storage coupled with high-temperature electric heating power generation system according to any one of claims 1 to 8, characterized in that: The trough-type photothermal device comprises: a trough-type reflector group (11) and a heat exchanger (12); the outlet of the trough-type reflector group (11) is connected to the first working fluid inlet of the heat exchanger (12); the inlet of the trough-type reflector group (11) is connected to the first working fluid outlet of the heat exchanger (12); the second working fluid inlet of the heat exchanger (12) is connected to the outlet of the medium-temperature energy storage device (21); and the second working fluid outlet of the heat exchanger (12) is connected to the inlet of the high-temperature energy storage device (22).

10. The medium-temperature solar thermal energy storage coupled with high-temperature electric heating power generation system according to any one of claims 1 to 8, characterized in that: The tower-type solar thermal device comprises: a heliostat group (14) and a heat collecting tower (15); the heliostat group (14) reflects sunlight to the heat collecting tower (15); the working fluid inlet of the heat collecting tower (15) is connected to the outlet of the medium-temperature energy storage device (21); and the working fluid outlet of the heat collecting tower (15) is connected to the inlet of the high-temperature energy storage device (22).

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