Coupled green electricity heated molten salt thermal storage system, method and power generation system

Abstract

The application belongs to the field of molten salt power generation, and relates to a molten salt heat storage system, method and power generation system coupled with green electricity heating, which can efficiently utilize green electricity, form energy storage, and make the power grid reuse the stored energy when the power consumption is high. The technical scheme comprises a first low-temperature storage tank, an electric heating module, a first high-temperature storage tank and a heater. The first low-temperature storage tank stores low-temperature molten salt. The electric heating module is electrically connected with a green electricity supply end, and a pipeline input end of the electric heating module is in communication with the first low-temperature storage tank. The first high-temperature storage tank stores high-temperature molten salt. An input end of a mixer is in communication with a pipeline output end of the electric heating module and an output end of the first high-temperature storage tank, the mixer uniformly mixes the molten salt from the electric heating module and the first high-temperature storage tank, and the uniformly mixed molten salt has a first temperature. The heater is in communication with the mixer, and is configured to receive the uniformly mixed molten salt from the mixer and heat the uniformly mixed molten salt to a second temperature.

Description

Technical Field

[0001] This invention belongs to the field of molten salt power generation, and relates to a molten salt thermal storage system, method and power generation system coupled with green electricity heating. Background Technology

[0002] Molten salt power generation is a power generation technology that uses molten salt as a heat transfer and heat storage medium. Generally, solar energy can be used to heat the molten salt, which can not only meet the normal power generation during the day when there is sufficient sunshine, but also take into account the power generation at night.

[0003] Based on the excellent thermal storage properties of molten salt, molten salt thermal storage can serve as a supplement to the power grid's energy storage, thereby compensating for the power shortage during peak electricity demand periods.

[0004] Currently, my country's green energy sector is developing rapidly, with solar and wind power being particularly prominent. In recent years, the large-scale deployment of distributed photovoltaic (PV) power stations has led to significant day-night power fluctuations in the power grid. Furthermore, the instability of solar and wind power results in large fluctuations in photovoltaic or wind power output, often requiring rectification and inversion processes before grid connection, thus wasting electricity. Summary of the Invention

[0005] To overcome the shortcomings of the aforementioned related technologies, some embodiments of the present invention propose a molten salt thermal storage system coupled with green electricity heating, which can efficiently utilize green electricity and form energy storage, enabling the reuse of stored energy when the power grid consumption is high.

[0006] The molten salt thermal storage system coupled with green electricity heating includes: a first low-temperature storage tank, an electric heating module, a first high-temperature storage tank, and a heater. The first low-temperature storage tank stores low-temperature molten salt. The power supply terminal of the electric heating module is electrically connected to the green electricity supply terminal, and the pipeline input terminal of the electric heating module is connected to the first low-temperature storage tank. The first high-temperature storage tank stores high-temperature molten salt. The input terminal of the mixer is connected to the pipeline output terminal of the electric heating module and the output terminal of the first high-temperature storage tank. The mixer mixes the molten salt from the electric heating module and the molten salt from the first high-temperature storage tank evenly, and sets the evenly mixed molten salt to a first temperature. The heater is connected to the mixer and is configured to receive the evenly mixed molten salt from the mixer and heat the evenly mixed molten salt to a second temperature.

[0007] Preferably, the molten salt thermal storage system coupled with green electric heating further includes a second high-temperature storage tank. The second high-temperature storage tank is disposed between the mixer and the heater, and is configured to: store the uniformly mixed molten salt, and stabilize the rate at which the uniformly mixed molten salt is injected into the heater.

[0008] Preferably, the molten salt thermal storage system coupled with green electric heating further includes a third high-temperature storage tank. The third high-temperature storage tank is connected to the outlet end of the heater, and the outlet end of the heater is also connected to the first high-temperature storage tank.

[0009] Preferably, the molten salt thermal storage system coupled with green electric heating further includes: a first temperature sensor, a second temperature sensor, and a variable frequency molten salt pump. The first temperature sensor is located at the outlet end of the electric heating module and is configured to monitor the real-time temperature at the outlet end of the electric heating module. The second temperature sensor is located at the outlet end of the mixer and is configured to monitor the real-time temperature at the outlet end of the mixer. The variable frequency molten salt pump is located on the pipeline between the first high-temperature storage tank and the mixer, and is configured to control the injection rate of molten salt from the first high-temperature storage tank into the mixer based on the data collected by the first temperature sensor.

[0010] Preferably, the heater comprises a gas-fired molten salt furnace. The molten salt thermal storage system coupled with green electric heating further comprises a first air preheater. The first air preheater is connected to the exhaust port of the gas-fired molten salt furnace, and is disposed between the first cryogenic storage tank and the electric heating module. The first air preheater is configured to preheat the cryogenic molten salt supplied from the first cryogenic storage tank to the electric heating module.

[0011] Preferably, the molten salt thermal storage system coupled with green electric heating further includes: a second cryogenic storage tank and a second air preheater. The second cryogenic storage tank stores cryogenic molten salt, and its outlet is connected to the inlet of the mixer. A second air preheater is disposed between the second cryogenic storage tank and the mixer, and is configured to preheat the cryogenic molten salt supplied from the second cryogenic storage tank to the mixer.

[0012] On the other hand, some embodiments of the present invention also provide a molten salt power generation system coupled with green electricity heating. The molten salt power generation system coupled with green electricity heating includes: a molten salt thermal storage system coupled with green electricity heating as described in one aspect above, a steam generation system, and a steam turbine. The inlet end of the molten salt pipeline of the steam generation system is connected to a second high-temperature storage tank of the molten salt thermal storage system coupled with green electricity heating, and the outlet end of the molten salt pipeline of the steam generation system is connected to a first low-temperature storage tank and a second low-temperature storage tank. The steam turbine is connected to the steam generation system.

[0013] In another aspect, some embodiments of the present invention also provide a molten salt thermal storage method coupled with green electric heating, applicable to the molten salt thermal storage system coupled with green electric heating described in the above aspect.

[0014] The molten salt thermal storage method coupled with green electric heating includes: transforming the green electric voltage to a safe voltage range, heating a quantitative amount of low-temperature molten salt within a unit time period to obtain electrically heated molten salt; mixing an appropriate amount of the first high-temperature molten salt and the electrically heated molten salt according to the temperature of the electrically heated molten salt and the temperature of a first high-temperature molten salt to obtain a mixed molten salt, which is maintained at a first temperature; and further heating the mixed molten salt to obtain high-temperature molten salt, which is then stored.

[0015] Preferably, the molten salt thermal storage system coupled with green electric heating further includes a second high-temperature storage tank. The method for further heating the mixed molten salt to obtain and store high-temperature molten salt comprises: storing the mixed molten salt in the second high-temperature storage tank; extracting the mixed molten salt from the second high-temperature storage tank at a stable rate; and heating the extracted mixed molten salt to obtain and store high-temperature molten salt.

[0016] The beneficial effects of this invention are as follows:

[0017] The electric heating module can adapt to voltage and current fluctuations within a safe voltage range and heat low-temperature molten salt, thereby achieving efficient utilization of electricity that fluctuates greatly and is not convenient to use directly. At the same time, combined with molten salt energy storage, it can generate electricity during peak grid demand, reduce the waste of green electricity and cooperate with the grid regulation function.

[0018] Given the instability of green electricity, there is instability in the heating power of low-temperature molten salt. By using a first high-temperature storage tank and mixing the heated low-temperature molten salt, the temperature of the molten salt entering the heater can be kept basically stable. At the same time, in conjunction with a second high-temperature storage tank, the temperature of the molten salt entering the heater can be controlled. In this way, under the premise of stable heater power, the temperature of the molten salt at the heater outlet can be ensured to meet the standard. It has the advantages of convenient control and molten salt meeting the usage requirements. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a structural diagram of the present invention;

[0021] Figure 2 This is another structural diagram of the present invention;

[0022] Figure 3 This is another structural diagram of the present invention. Detailed Implementation

[0023] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0025] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0026] In current technology, the power grid adjusts electricity prices based on electricity consumption. Within a single day, the price during peak and off-peak hours can differ by a factor of several. For businesses, blast furnace gas produced from coal coking, besides being used in steelmaking and other projects, can be used for power generation if there is surplus. However, blast furnace gas production is stable and does not match the peak and off-peak electricity prices. In other words, for businesses, the benefits of generating electricity during off-peak hours are far lower than those generated during peak hours.

[0027] Therefore, a molten salt energy storage system is implemented in parallel with power generation systems using blast furnace gas. This system converts the chemical energy of blast furnace gas into thermal energy during periods of low electricity prices and stores it in molten salt. During periods of high electricity prices, the stored thermal energy in the molten salt is released to generate electricity, thereby improving the company's efficiency.

[0028] In addition, the company also found that using green electricity to heat molten salt only requires transforming the green electricity to a safe range, without the need for complex inversion and rectification processes. On the one hand, this can reduce the occupation of substations, and on the other hand, it can reduce the waste of green electricity in the inversion and rectification process. In other words, the molten salt energy storage system can effectively utilize green electricity and has high safety.

[0029] However, the heating power of green electricity is unstable, and molten salt energy storage systems using green electricity may experience situations where the molten salt temperature after heating does not meet or exceeds the standard. In particular, when a molten salt energy storage system using green electricity is combined with a molten salt energy storage system using blast furnace gas as its energy source, it may also interfere with the normal operation of the molten salt energy storage system using blast furnace gas as its energy source.

[0030] Based on this, on the one hand, such as Figure 1 As shown, some embodiments of the present invention propose a molten salt thermal storage system coupled with green electricity heating. The molten salt thermal storage system coupled with green electricity heating includes: a first low-temperature storage tank 1, an electric heating module 2, a first high-temperature storage tank 3, and a heater 4. The first low-temperature storage tank 1 stores low-temperature molten salt. The power supply terminal of the electric heating module 2 is electrically connected to the green electricity supply terminal, and the pipeline input terminal of the electric heating module 2 is connected to the first low-temperature storage tank 1. The first high-temperature storage tank 3 stores high-temperature molten salt. The input terminal of a mixer 9 is connected to the pipeline output terminal of the electric heating module 2 and the output terminal of the first high-temperature storage tank 3. The mixer 9 mixes the molten salt from the electric heating module 2 and the molten salt from the first high-temperature storage tank 3 evenly, and sets the evenly mixed molten salt to a first temperature. The heater 4 is connected to the mixer 9 and is configured to receive the evenly mixed molten salt from the mixer 9 and heat the evenly mixed molten salt to a second temperature.

[0031] In some examples, the first cryogenic storage tank 1 stores cryogenic molten salt with a temperature greater than 150°C, for example, the temperature of the cryogenic molten salt can be 280°C to 290°C. The first cryogenic storage tank 1 is connected to the electric heating module 2. The electric heating module 2 can be an electric heating molten salt furnace or other heating structures. Specific examples of the structure of the electric heating module 2 are described below.

[0032] A cryogenic molten salt pump is installed between the first cryogenic storage tank 1 and the electric heating module 2, which can inject the cryogenic molten salt in the first cryogenic storage tank 1 into the electric heating module 2 at a constant speed. After heating, it is injected into the mixer 9 together with the high-temperature molten salt in the first high-temperature storage tank 3 for mixing.

[0033] Among them, the high-temperature molten salt can be 400~580℃, for example, the high-temperature molten salt problem can be 540℃, and the mixer 9 can be a static mixer, a pipeline mixer, etc. Currently, it is understood that the material of the mixer 9 should be able to withstand a high temperature of 580℃.

[0034] Based on the molten salt temperature and output speed output by the electric heating module 2, and the molten salt temperature to be added to the heater 4, the output speed of the high-temperature molten salt in the first high-temperature storage tank 3 can be controlled so that the first temperature of the molten salt after mixing with the high-temperature molten salt output by the electric heating module 2 is within the acceptable range of the heater 4. For example, the first temperature can be greater than 300℃ and less than 500℃, and the fluctuation range of the first temperature is less than 20℃.

[0035] Heater 4 receives and heats molten salt from mixer 9. In this application, heater 4 can be a blast furnace gas molten salt furnace. It heats the molten salt from mixer 9 from a first temperature to a second temperature, which can be 540°C. The molten salt that has reached 540°C is stored and used to generate electricity during peak electricity demand periods.

[0036] Preferably, such as Figure 2 As shown, the molten salt thermal storage system coupled with green electric heating also includes a second high-temperature storage tank 5. The second high-temperature storage tank 5 is disposed between the mixer 9 and the heater 4, and is configured to: store the uniformly mixed molten salt, and stabilize the rate at which the uniformly mixed molten salt is injected into the heater 4.

[0037] Preferably, such as Figure 3 As shown, the molten salt thermal storage system coupled with green electric heating also includes a third high-temperature storage tank 6. The third high-temperature storage tank 6 is connected to the outlet end of the heater 4, and the outlet end of the heater 4 is also connected to the first high-temperature storage tank 3.

[0038] Preferably, the molten salt thermal storage system coupled with green electric heating further includes: a first temperature sensor, a second temperature sensor, and a variable frequency molten salt pump. The first temperature sensor is located at the outlet end of the electric heating module 2 and is configured to monitor the real-time temperature at the outlet end of the electric heating module 2. The second temperature sensor is located at the outlet end of the mixer 9 and is configured to monitor the real-time temperature at the outlet end of the mixer 9. The variable frequency molten salt pump is located on the pipeline between the first high-temperature storage tank 3 and the mixer 9, and is configured to control the injection rate of molten salt from the first high-temperature storage tank 3 into the mixer 9 based on the data collected by the first temperature sensor.

[0039] Preferably, the heater 4 includes a gas-fired molten salt furnace. The molten salt thermal storage system coupled with green electric heating also includes a first air preheater. The first air preheater is connected to the exhaust port of the gas-fired molten salt furnace, and a first air preheater is provided between the first cryogenic storage tank 1 and the electric heating module 2. The first air preheater is configured to preheat the cryogenic molten salt supplied from the first cryogenic storage tank 1 to the electric heating module 2.

[0040] Preferably, the molten salt thermal storage system coupled with green electric heating further includes: a second cryogenic storage tank 7 and a second air preheater 8. The second cryogenic storage tank 7 stores cryogenic molten salt, and its outlet is connected to the inlet of the mixer 9. The second air preheater 8 is disposed between the second cryogenic storage tank 7 and the mixer 9, and is configured to preheat the cryogenic molten salt supplied from the second cryogenic storage tank 7 to the mixer 9.

[0041] On the other hand, some embodiments of the present invention also provide a molten salt power generation system coupled with green electricity heating. The molten salt power generation system coupled with green electricity heating includes: a molten salt thermal storage system coupled with green electricity heating as described in one aspect above, a steam generation system, and a steam turbine. The inlet end of the molten salt pipeline of the steam generation system is connected to the second high-temperature storage tank 5 of the molten salt thermal storage system coupled with green electricity heating, and the outlet end of the molten salt pipeline of the steam generation system is connected to the first low-temperature storage tank 1 and the second low-temperature storage tank 7. The steam turbine is connected to the steam generation system.

[0042] In another aspect, some embodiments of the present invention also provide a molten salt thermal storage method coupled with green electric heating, applicable to the molten salt thermal storage system coupled with green electric heating described in the above aspect.

[0043] The molten salt thermal storage method coupled with green electric heating includes:

[0044] S1. After the green electricity is transformed to a safe voltage range, a certain amount of low-temperature molten salt is heated within a unit time period to obtain electrically heated molten salt.

[0045] S2. Based on the temperature of the electrically heated molten salt and the temperature of the first high-temperature molten salt, a suitable amount of the first high-temperature molten salt and the electrically heated molten salt are mixed to obtain a mixed molten salt, wherein the temperature of the mixed molten salt is maintained at the first temperature.

[0046] S3. Continue heating the mixed molten salt to obtain high-temperature molten salt and store it.

[0047] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0048] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A molten salt thermal storage system coupled with green electric heating, characterized in that, include: A first cryogenic storage tank, which stores cryogenic molten salt; An electric heating module, wherein the power supply terminal of the electric heating module is electrically connected to the green electricity supply terminal, and the pipeline input terminal of the electric heating module is connected to the first low-temperature storage tank; The first high-temperature storage tank stores high-temperature molten salt. A mixer, the input end of which is connected to the pipeline output end of the electric heating module and the output end of the first high-temperature storage tank, the mixer mixes the molten salt from the electric heating module and the molten salt from the first high-temperature storage tank evenly, and sets the evenly mixed molten salt to a first temperature; A heater, connected to the mixer, configured to receive homogenized molten salt from the mixer and heat the homogenized molten salt to a second temperature; The molten salt thermal storage system coupled with green electric heating also includes a second high-temperature storage tank; The second high-temperature storage tank is disposed between the mixer and the heater, and is configured to: store the uniformly mixed molten salt, and regulate the rate at which the uniformly mixed molten salt is injected into the heater.

2. The molten salt thermal storage system coupled with green electric heating according to claim 1, characterized in that, The molten salt thermal storage system coupled with green electric heating also includes a third high-temperature storage tank; The third high-temperature storage tank is connected to the outlet end of the heater, and the outlet end of the heater is also connected to the first high-temperature storage tank.

3. The molten salt thermal storage system coupled with green electric heating according to claim 1, characterized in that, The molten salt thermal storage system coupled with green electric heating also includes: A first temperature sensor is disposed at the outlet end of the electric heating module and is configured to monitor the real-time temperature at the outlet end of the electric heating module. A second temperature sensor is disposed at the outlet end of the mixer, and the second temperature sensor cup is configured to monitor the real-time temperature at the outlet end of the mixer; A variable frequency molten salt pump is installed on the pipeline between the first high-temperature storage tank and the mixer. The variable frequency molten salt pump is configured to control the injection amount of molten salt from the first high-temperature storage tank into the mixer based on data collected by the first temperature sensor.

4. The molten salt thermal storage system coupled with green electric heating according to claim 1, characterized in that, The heater includes a gas-fired molten salt furnace; The molten salt thermal storage system coupled with green electric heating also includes a first air preheater; The first air preheater is connected to the exhaust port of the gas-fired molten salt furnace. The first air preheater is provided between the first cryogenic storage tank and the electric heating module. The first air preheater is configured to preheat the cryogenic molten salt delivered from the first cryogenic storage tank to the electric heating module.

5. The molten salt thermal storage system coupled with green electric heating according to claim 1, characterized in that, The molten salt thermal storage system coupled with green electric heating also includes: A second cryogenic storage tank is used to store cryogenic molten salt, and the outlet of the second cryogenic storage tank is connected to the inlet of the mixer. A second air preheater is provided between the second cryogenic storage tank and the mixer. The second air preheater is configured to preheat the cryogenic molten salt supplied from the second cryogenic storage tank to the mixer.

6. A molten salt power generation system coupled with green electricity heating, characterized in that, The molten salt power generation system coupled with green electricity heating includes: The molten salt thermal storage system coupled with green electric heating as described in any one of claims 1 to 5 above; A steam generating system, wherein the inlet end of the molten salt pipeline of the steam generating system is connected to the second high-temperature storage tank of the molten salt thermal storage system coupled with green electric heating, and the outlet end of the molten salt pipeline of the steam generating system is connected to the first low-temperature storage tank and the second low-temperature storage tank; A steam turbine, which is connected to the steam generation system.

7. A molten salt thermal storage method coupled with green electric heating, characterized in that, The molten salt thermal storage system coupled with green electric heating as described in any one of claims 1 to 5, wherein the molten salt thermal storage method coupled with green electric heating comprises: After the green electricity is transformed to a safe voltage range, a certain amount of low-temperature molten salt is heated within a unit time period to obtain electrically heated molten salt; Based on the temperature of the electrically heated molten salt and the temperature of the first high-temperature molten salt, an appropriate amount of the first high-temperature molten salt and the electrically heated molten salt are mixed to obtain a mixed molten salt, wherein the temperature of the mixed molten salt is maintained at the first temperature; The mixed molten salt is further heated to obtain high-temperature molten salt, which is then stored.

8. The molten salt thermal storage method coupled with green electric heating according to claim 7, characterized in that, The molten salt thermal storage system coupled with green electric heating also includes a second high-temperature storage tank; The method of further heating the mixed molten salt to obtain high-temperature molten salt and storing it: The mixed molten salt is stored in the second high-temperature storage tank; Extract the mixed molten salt from the second high-temperature storage tank at a stable rate; The extracted mixed molten salt is heated to obtain high-temperature molten salt, which is then stored.

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