Energy storage system and power generation system

Abstract

The utility model relates to the technical field of energy recovery, in particular to an energy storage system and a power generation system, the energy storage system comprises a low-temperature energy storage tank and a high-temperature energy storage tank, a first heat storage passage and a second heat storage passage are formed between the low-temperature energy storage tank and the high-temperature energy storage tank, and the first heat storage passage and the second heat storage passage are arranged in parallel; the first heat storage channel is provided with a first heater, the second heat storage channel is sequentially provided with a first heat exchanger, a medium-temperature energy storage tank and a second heater in series, and the first heat exchanger is used for heat exchange between a heat exchange medium and an energy storage medium. According to the utility model, available waste heat in the heat exchange medium is stored through the medium-temperature energy storage tank, so that the problem of energy waste in the prior art is solved; and each heat storage passage is provided with a heater, so that the temperature of the energy storage medium in each heat storage passage can be accurately controlled by adjusting the power of the heaters, and the accuracy and the stability of temperature control of the energy storage system are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of energy recovery, in particular to an energy storage system and a power generation system. Background Art

[0002] With the acceleration of energy transformation, the renewable energy power system is developing continuously. It has become a trend for renewable energy to rely on thermal power generation to jointly supply social electricity. However, due to the intermittent, volatile and random characteristics of renewable energy generation, the flexibility of peak load regulation of the power generation system is limited. How to effectively integrate renewable energy generation and thermal power generation to achieve the purpose of peak load reduction and valley load filling is a technical problem that needs to be faced at present.

[0003] Energy storage technology is widely used in the consumption of renewable energy, such as molten salt heat storage, water heat storage, high-temperature phase change heat storage and other technologies that have been applied. Such systems are usually used to consume high-grade electricity or low-grade industrial heat alone, but cannot consume high-grade electricity and low-grade industrial heat simultaneously. For example, in industrial production, it may be necessary to consume high-grade new energy surplus electricity and low-grade industrial waste heat simultaneously. Utility Model Content

[0004] The embodiments of the utility model provide an energy storage system and a power generation system to solve the problem that the existing energy storage technology cannot simultaneously absorb energy of different grades, thus causing energy waste.

[0005] The embodiment of the utility model provides an energy storage system, comprising a low-temperature energy storage tank for storing a low-temperature energy storage medium and a high-temperature energy storage tank for storing a high-temperature energy storage medium, wherein a first heat storage passage and a second heat storage passage are formed between the outlet of the low-temperature energy storage tank and the inlet of the high-temperature energy storage tank, and the first heat storage passage and the second heat storage passage are arranged in parallel; the first heat storage passage is provided with a first heater, the inlet of the first heater is communicated with the outlet of the low-temperature energy storage tank, and the outlet of the first heater is communicated with the inlet of the high-temperature energy storage tank; the second heat storage passage is sequentially provided with a first heat exchanger, a medium-temperature energy storage tank and a second heater in series, the inlet of the first heat exchanger is communicated with the outlet of the low-temperature energy storage tank, the outlet of the second heater is communicated with the inlet of the high-temperature energy storage tank, the first heat exchanger is used for heat exchange between a heat exchange medium and an energy storage medium, and the medium-temperature energy storage tank is used for storing a medium-temperature energy storage medium whose temperature is between the low-temperature energy storage medium and the high-temperature energy storage medium.

[0006] Optionally, there are at least two second heat storage pathways, at least two of which are arranged in parallel, and each of the second heat storage pathways is provided with the first heat exchanger, the medium-temperature energy storage tank and the second heater in series.

[0007] Optionally, at least one of the second heat storage passages is provided with at least two medium-temperature energy storage tanks having different storage temperatures in series, the first heat exchanger is provided between the low-temperature energy storage tank and the medium-temperature energy storage tank adjacent to the low-temperature energy storage tank, and the first heat exchanger is provided between two adjacent medium-temperature energy storage tanks.

[0008] Optionally, the first heat storage passage is provided with a first delivery pump, and the first delivery pump is located between the outlet of the low-temperature energy storage tank and the inlet of the first heater.

[0009] Optionally, the second heat storage passage is provided with a second delivery pump, and the second delivery pump is located between the outlet of the low-temperature energy storage tank and the inlet of the first heat exchanger.

[0010] Optionally, the second heat storage path further includes a third delivery pump, and the third delivery pump is located between the outlet of the medium-temperature energy storage tank and the inlet of the second heater.

[0011] Optionally, the first heater and / or the second heater is an electric heater.

[0012] Optionally, a photovoltaic power station and / or a wind power station are further included, and the first heater and / or the second heater are electrically connected to at least one of the photovoltaic power station and the wind power station.

[0013] Optionally, the first heater and / or the second heater is a solar thermal collector; the solar thermal collector directly heats the energy storage medium; or the solar thermal collector indirectly heats the energy storage medium via a heat-conducting medium.

[0014] Optionally, a heat release passage is formed between the outlet of the high-temperature energy storage tank and the inlet of the low-temperature energy storage tank, and the heat release passage is provided with at least one second heat exchanger, the inlet of the second heat exchanger is connected to the outlet of the high-temperature energy storage tank, and the outlet of the second heat exchanger is connected to the inlet of the low-temperature energy storage tank, and the second heat exchanger is used for exchanging heat between water and energy storage medium and outputting superheated steam.

[0015] Optionally, there are two second heat exchangers, which are arranged in series in the heat release passage; the second heat exchanger close to the low-temperature energy storage tank is used for heat exchange between water and the energy storage medium and outputs saturated steam, and the second heat exchanger close to the high-temperature energy storage tank is used for heat exchange between the saturated steam and the energy storage medium and outputs superheated steam.

[0016] Optionally, there are three second heat exchangers, and the three second heat exchangers are arranged in series in the heat release passage.

[0017] Optionally, the heat release passage is provided with a fourth delivery pump, and the fourth delivery pump is located between the outlet of the high-temperature energy storage tank and the inlet of the second heat exchanger.

[0018] Optionally, the heat of the heat exchange medium comes from industrial waste heat.

[0019] Optionally, it further comprises a synthetic ammonia system, and the heat exchange medium is the medium-temperature synthesis gas produced by the synthetic ammonia system.

[0020] Optionally, at least one of the low-temperature energy storage tank, the medium-temperature energy storage tank and the high-temperature energy storage tank is provided with a heat preservation structure.

[0021] Optionally, the heat preservation structure is provided inside the energy storage tank and / or outside the energy storage tank.

[0022] Optionally, the thermal insulation structure is a thermal insulation pipe.

[0023] Optionally, the insulation medium in the insulation pipe includes at least one of saturated steam, superheated steam and medium-temperature synthesis gas.

[0024] The utility model also provides a power generation system, comprising a steam turbine generator set and the above energy storage system, wherein the superheated steam outputted by the energy storage system in the heat release stage drives the steam turbine generator set to generate electricity.

[0025] Compared with the prior art, the utility model has the following advantages:

[0026] In the embodiment of the utility model, during the heat storage process of the energy storage system, the heat exchange medium exchanges heat with the low-temperature energy storage medium through the first heat exchanger, thereby heating the low-temperature energy storage medium into a medium-temperature energy storage medium and storing it in the medium-temperature energy storage tank. The medium-temperature energy storage medium is then heated by the second heater to become a high-temperature energy storage medium and stored in the high-temperature energy storage tank.

[0027] First, the utility model can respectively absorb energy from different grades of energy through medium-temperature energy storage tanks and high-temperature energy storage tanks, so as to solve the problem that the existing energy storage technology cannot simultaneously absorb energy of different grades, thus causing energy waste.

[0028] Secondly, the utility model utilizes the energy of different grades of energy absorbed by the heat storage passage to heat water through the heat release passage to obtain superheated steam, and utilizes the superheated steam to drive the turbine generator set to generate electricity, thereby realizing energy recovery and utilization.

[0029] Third, the utility model is provided with a heater in each heat storage passage, so that the temperature of the energy storage medium in each heat storage passage can be precisely controlled by adjusting the power of the heater, so as to improve the accuracy and stability of the temperature control of the energy storage system.

[0030] Fourthly, the utility model provides a plurality of second heat storage passages, or provides a plurality of medium-temperature energy storage tanks and a first heat exchanger in series on the second heat storage passages to recover industrial waste heat of different temperatures, thereby broadening the application scope of the energy storage system.

[0031] Fifth, the utility model combines power systems such as photovoltaic power stations and wind power stations with energy storage systems, and uses industrial waste heat to heat low-temperature energy storage media, so that the energy storage system can simultaneously consume high-grade waste electricity and low-grade industrial waste heat, and use the absorbed energy for power generation, so as to achieve peak load regulation of the power system and recovery of industrial waste heat.

[0032] Sixth, industrial equipment usually needs to continue to operate after it is turned on, so industrial waste heat is usually continuously generated. The utility model absorbs industrial waste heat through a medium-temperature energy storage tank, which is not affected by the volatility of renewable energy. For example, a photovoltaic power station heats the energy storage medium through a heat storage channel during the day. When the photovoltaic power station stops working at night, it cannot continuously store heat, but industrial waste heat is still continuously generated at night. Therefore, the industrial waste heat can be absorbed through a medium-temperature energy storage tank, so that the heat storage and heat release processes are carried out simultaneously, thereby broadening the applicability of the system.

[0033] The above description is only an overview of the technical solution of the utility model. In order to more clearly understand the technical means of the utility model, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the utility model more obvious and easy to understand, the specific implementation methods of the utility model are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for describing the embodiments are briefly introduced below.

[0035] Figure 1 A schematic diagram of the operation of an energy storage system provided in an embodiment of the utility model. Description of the drawings:

[0037] 1- low temperature energy storage tank, 2- medium temperature energy storage tank, 3- high temperature energy storage tank, 4- first delivery pump, 5- second delivery pump, 6- third delivery pump, 7- fourth delivery pump, 8- first heat exchanger, 9- superheater, 10- evaporator, 11- preheater, 12- first heater, 13- second heater. DETAILED DESCRIPTION

[0038] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can also be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0039] Reference Figure 1 The energy storage system provided by the embodiment of the utility model can be applied to the fields of industrial heating, steam power generation, deep peak regulation of thermal power units, photovoltaic power generation and wind power generation, etc., and comprises a low-temperature energy storage tank 1 for storing low-temperature energy storage medium and a high-temperature energy storage tank 3 for storing high-temperature energy storage medium. A first heat storage passage and a second heat storage passage are formed between the outlet of the low-temperature energy storage tank 1 and the inlet of the high-temperature energy storage tank 3, and the first heat storage passage and the second heat storage passage are arranged in parallel; the first heat storage passage is provided with a first heater 12, and the inlet of the first heater 12 is connected to the low-temperature energy storage tank 1. The outlet of the first heater 12 is connected to the inlet of the high-temperature energy storage tank 3; the second heat storage passage is sequentially provided with a first heat exchanger 8, a medium-temperature energy storage tank 2 and a second heater 13 in series, the inlet of the first heat exchanger 8 is connected to the outlet of the low-temperature energy storage tank 1, the outlet of the second heater 13 is connected to the inlet of the high-temperature energy storage tank 3, the first heat exchanger 8 is used for heat exchange between heat exchange medium and energy storage medium, and the medium-temperature energy storage tank 2 is used for storing medium-temperature energy storage medium whose temperature is between the low-temperature energy storage medium and the high-temperature energy storage medium.

[0040] Specifically, molten salt is a commonly used energy storage medium in production. In order to clearly describe the technical solution of this application, the energy storage medium in the following text is molten salt. However, it should be understood that in addition to molten salt, energy storage media such as heat transfer oil that meet the working temperature requirements can be used as the energy storage medium in this utility model.

[0041] In addition, the heat exchange medium in the embodiment of the present application can be any one of liquid, solid or gas, or a mixture of liquid, solid or gas. The embodiment of the present application does not limit the source of the heat exchange medium, as long as it contains usable waste heat.

[0042] The number of second heat storage paths can be flexibly set according to the number of types of heat exchange media at different temperatures; for example, when it is necessary to recover waste heat in two heat exchange media at different temperatures, two second heat storage paths can be set, and the two second heat storage paths are arranged in parallel. A first heat exchanger 8, a medium-temperature energy storage tank 2 and a second heater 13 are arranged in series on each second heat storage path. The heat exchange medium and the low-temperature molten salt are exchanged with the help of the first heat exchanger 8, and the low-temperature molten salt is heated and stored in the medium-temperature energy storage tank 2 on the corresponding path. Then, the molten salt discharged from the medium-temperature energy storage tank 2 is heated by the second heater 13 and stored in the high-temperature energy storage tank 3, thereby realizing the storage of usable waste heat.

[0043] In this embodiment, the low-grade industrial waste heat can come from the field of chemical synthesis ammonia. In the process of chemical synthesis ammonia, medium-temperature synthesis gas will be generated. The temperature of the medium-temperature synthesis gas is generally between 400°C and 450°C, while the temperature of high-temperature molten salt in the energy storage system is generally between 550°C and 580°C, and the temperature of low-temperature molten salt is generally between 250°C and 300°C. Therefore, the temperature of the usable waste heat in the medium-temperature synthesis gas is between that of high-temperature molten salt and that of low-temperature molten salt.

[0044] Figure 1 An operation schematic diagram of an energy storage system provided for an embodiment of the present application, wherein the heat exchange medium is medium-temperature synthesis gas; in this embodiment, there is one second heat storage path, on which a first heat exchanger 8, a medium-temperature energy storage tank 2 and a second heater 13 are arranged, the inlet of the first heat exchanger 8 is connected to the outlet of the low-temperature energy storage tank 1, the outlet of the first heat exchanger 8 is connected to the inlet of the medium-temperature energy storage tank 2, the inlet of the second heater 13 is connected to the outlet of the medium-temperature energy storage tank 2, and the outlet of the second heater 13 is connected to the inlet of the high-temperature energy storage tank 3; the working energy of the first heater 12 and the second heater 13 can be derived from other grades of energy, such as high-grade electricity from wind power stations, photovoltaic power stations or thermal power stations.

[0045] When storing heat, the operation process of the energy storage system is as follows: Figure 1 As shown by the solid line in , the low-temperature molten salt in the low-temperature energy storage tank 1 is discharged in two ways, one of which directly enters the first heater 12, is directly heated into high-temperature molten salt in the first heater 12 and is stored in the high-temperature energy storage tank 3; the other low-temperature molten salt first enters the first heat exchanger 8, and the medium-temperature synthesis gas in the first heat exchanger 8 exchanges heat with the low-temperature molten salt, and the low-temperature molten salt is heated into medium-temperature molten salt and stored in the medium-temperature energy storage tank 2, and the cooled synthesis gas is discharged from the first heat exchanger 8 and returned to the chemical area, and then the second heater 13 is used to heat the medium-temperature molten salt in the medium-temperature energy storage tank 2 into high-temperature molten salt and store it in the high-temperature energy storage tank 3; since the medium-temperature synthesis gas will be continuously generated during the process of chemical synthesis of ammonia, the first heat exchanger 8 can be operated continuously, so that the usable waste heat in the medium-temperature synthesis gas is stored in the medium-temperature energy storage tank 2.

[0046] When releasing heat, the energy storage system operates as follows: Figure 1 As shown by the middle dotted line, when releasing heat, the high-temperature molten salt passes through the second heat exchanger to heat the water into superheated steam, and the superheated steam is then sent to the steam turbine generator set to generate electricity, thereby providing electricity for the chemical area or other plant areas.

[0047] The utility model absorbs low-grade industrial waste heat through a medium-temperature energy storage tank and absorbs high-grade electric energy through a high-temperature energy storage tank, thereby realizing the simultaneous absorption of energy from energy sources of different grades, so as to solve the problem that the existing energy storage technology cannot simultaneously absorb energy of different grades, thereby causing energy waste; in addition, a heater is provided in each heat storage passage, so that the temperature of the energy storage medium in each heat storage passage can be accurately controlled by adjusting the power of the heater, so as to improve the accuracy and stability of temperature control of the energy storage system.

[0048] Optionally, there are at least two second heat storage pathways, and at least two second heat storage pathways are arranged in parallel. Each of the second heat storage pathways is provided with the first heat exchanger 8 , the medium-temperature energy storage tank 2 and the second heater 13 .

[0049] Specifically, when there are two or more second heat storage pathways, the two or more second heat storage pathways are arranged in parallel with each other, and each second heat storage pathway is provided with a first heat exchanger 8, a medium-temperature energy storage tank 2 and a second heater 13 in series, and the inlet of the second heater 13 is connected to the outlet of the medium-temperature energy storage tank 2, and the outlet of the second heater 13 is connected to the inlet of the high-temperature energy storage tank 3.

[0050] In this embodiment, the energy storage system is provided with a plurality of second heat storage pathways, so that one or more second heat storage pathways can be selected as needed to recover industrial waste heat of different temperatures, thereby broadening the application scope of the energy storage system.

[0051] Optionally, at least one of the second heat storage passages is provided in series with at least two medium-temperature energy storage tanks 2 having different storage temperatures, the first heat exchanger 8 is provided between the low-temperature energy storage tank 1 and the medium-temperature energy storage tank 2 adjacent to the low-temperature energy storage tank 1, and the first heat exchanger 8 is provided between two adjacent medium-temperature energy storage tanks 2.

[0052] Specifically, the number of medium-temperature energy storage tanks 2 on each second heat storage path can be flexibly selected according to the types and number of heat exchange media at different temperatures. The storage temperatures of multiple medium-temperature energy storage tanks 2 are different. The storage temperature of the medium-temperature energy storage tank 2 adjacent to the low-temperature energy storage tank 1 is the lowest, and the storage temperature of the medium-temperature energy storage tank 2 close to the high-temperature energy storage tank 3 is the highest. The storage temperatures of the remaining medium-temperature energy storage tanks 2 increase one by one along the flow direction of the molten salt.

[0053] For example, when a second heat storage passage is used to recover industrial waste heat of two different temperatures, two medium-temperature energy storage tanks 2 with different storage temperatures can be arranged on the second heat storage passage. The two medium-temperature energy storage tanks 2 are arranged in series on the second heat storage passage. The storage temperature of the medium-temperature energy storage tank 2 adjacent to the low-temperature energy storage tank 1 is lower, while the storage temperature of the medium-temperature energy storage tank 2 close to the high-temperature energy storage tank 3 is higher. A first heat exchanger 8 is arranged between the low-temperature energy storage tank 1 and the medium-temperature energy storage tank 2 adjacent to the low-temperature energy storage tank 1, a first heat exchanger 8 is also arranged between the two medium-temperature energy storage tanks 2, and a second heater 13 is arranged between the medium-temperature energy storage tank 2 close to the high-temperature energy storage tank 3 and the high-temperature energy storage tank 3.

[0054] During heat storage, the heat exchange medium with a lower temperature is passed into the first heat exchanger 8 close to the low-temperature energy storage tank 1, and the heat exchange medium with a higher temperature is passed into another first heat exchanger 8; the low-temperature molten salt first passes through the first first heat exchanger 8, is heated to a medium-temperature molten salt with a lower temperature in the first first heat exchanger 8 and is stored in the medium-temperature energy storage tank 2, and then the molten salt discharged from the medium-temperature energy storage tank 2 is heated by the heat exchange medium with a higher temperature in the second first heat exchanger 8, and then is stored in the medium-temperature energy storage tank 2 close to the high-temperature energy storage tank 3, and then the second heater 13 is used to heat the molten salt in the medium-temperature energy storage tank 2 and store it in the high-temperature energy storage tank 3.

[0055] The embodiment of the present application recovers waste heat in heat exchange media of various temperatures by serially arranging a plurality of medium-temperature energy storage tanks 2 and a first heat exchanger 8 on a second heat storage path, thereby realizing cascade utilization of energy and expanding the scope of application of the energy storage system.

[0056] Optionally, refer to Figure 1 The first heat storage passage is provided with a first delivery pump 4 , and the first delivery pump 4 is located between the outlet of the low-temperature energy storage tank 1 and the inlet of the first heater 12 .

[0057] Specifically, the first delivery pump 4 is located between the outlet of the low-temperature energy storage tank 1 and the inlet of the first heater 12. By adjusting the first delivery pump 4, the on-off of the first heat storage path and the flow rate of the molten salt can be controlled, thereby controlling the energy storage efficiency of the entire energy storage system.

[0058] Optionally, refer to Figure 1 The second heat storage passage is provided with a second delivery pump 5 , and the second delivery pump 5 is located between the outlet of the low-temperature energy storage tank 1 and the inlet of the first heat exchanger 8 .

[0059] Specifically, the second delivery pump 5 is located between the outlet of the low-temperature energy storage tank 1 and the inlet of the first heat exchanger 8. By adjusting the second delivery pump 5, the on-off of the second heat storage path and the flow rate of the molten salt can be controlled, thereby controlling the energy storage efficiency of the entire energy storage system.

[0060] Optionally, refer to Figure 1 The second heat storage passage is provided with a third delivery pump 6 , and the third delivery pump 6 is located between the outlet of the medium-temperature energy storage tank 2 and the inlet of the second heater 13 .

[0061] Specifically, the third delivery pump 6 is located between the outlet of the medium-temperature energy storage tank 2 and the inlet of the second heater 13. By adjusting the third delivery pump 6, the on-off of the second heat storage path and the flow rate of the molten salt can be controlled, thereby controlling the energy storage efficiency of the entire energy storage system.

[0062] Optionally, the first heater 12 and / or the second heater 13 is an electric heater.

[0063] Specifically, at least one of the first heater 12 and the second heater 13 is configured as an electric heater, so that electric energy is directly used to provide working energy for the first heater 12 or the second heater 13 to absorb high-quality surplus electricity.

[0064] Optionally, the energy storage system further includes a photovoltaic power station and / or a wind power station, and the first heater 12 and / or the second heater 13 is electrically connected to at least one of the photovoltaic power station and the wind power station.

[0065] Specifically, when the first heater 12 is an electric heater, the first heater 12 may be provided with electric energy required for operation by a photovoltaic power station or a wind power station, or may be provided with electric energy by both the photovoltaic power station and the wind power station.

[0066] When the second heater 13 is an electric heater, the second heater 13 may be provided with electric energy required for operation by a photovoltaic power station or a wind power station, or may be provided with electric energy by both the photovoltaic power station and the wind power station.

[0067] When the first heater 12 and the second heater 13 are both electric heaters, one of the heaters can be provided with the required electric energy for operation only by the photovoltaic power station, while the other heater can be provided with the required electric energy for operation only by the wind power station; in addition, at least one of the photovoltaic power station and the wind power station can also provide the required electric energy for operation of both heaters at the same time.

[0068] The embodiment of the present application combines a photovoltaic power station or a wind power station with an energy storage system, and uses the excess electricity produced by the photovoltaic power station or the wind power station to heat the molten salt to achieve energy storage and utilization, thereby playing the role of peak shaving and valley filling and system frequency regulation, providing flexibility for power supply.

[0069] Taking the combination of a photovoltaic power station and an energy storage system as an example, the first heater 12 and the second heater 13 are electric heaters, and the photovoltaic power station provides the first heater 12 and the second heater 13 with the required electric energy; when storing heat during the day, the operation process of the energy storage system is as follows Figure 1As shown by the solid line in , the low-temperature molten salt is discharged in two ways, one of which is directly discharged into the first heater 12 and heated into high-temperature molten salt, and then stored in the high-temperature energy storage tank 3; the other low-temperature molten salt is discharged into the first heat exchanger 8 and heated by the medium-temperature synthesis gas, the synthesis gas with reduced temperature returns to the chemical area, and the medium-temperature molten salt generated after heating is stored in the medium-temperature energy storage tank 2, and then the medium-temperature molten salt is directly heated into high-temperature molten salt through the second heater 13, and then stored in the high-temperature energy storage tank 3; at night, since the photovoltaic power station stops operating, the energy storage system executes Figure 1 In the heat release process shown by the middle dotted line, the high-temperature molten salt passes through the second heat exchanger to heat the water into superheated steam, and the superheated steam is then sent to the steam turbine generator set to generate electricity, thereby providing electricity for the chemical area or other plant areas.

[0070] It should be noted that when combining the photovoltaic power station and the energy storage system, in order to ensure that the molten salt in each energy storage tank is sufficient for the system to operate continuously and to avoid the molten salt being exhausted, the following conditions must be met: within a diurnal charging and discharging cycle, the initial total amount of molten salt in the low-temperature energy storage tank 1 is greater than or equal to the sum of the total amount of molten salt entering the medium-temperature energy storage tank 2 and the total amount of molten salt passing through the first heater 12 during daytime operation; the amount of molten salt extracted from the high-temperature energy storage tank 3 and returned to the low-temperature energy storage tank 1 at night is equal to the amount of molten salt entering the high-temperature energy storage tank 3 during the day; the total amount of molten salt heated by the first heat exchanger 8 is equal to the total amount of molten salt extracted by the third delivery pump 6 during the day.

[0071] In addition, the wind power station can also be combined with the energy storage system, and the wind power station provides the required electric energy for the first heater 12 and the second heater 13; at this time, since the wind power station can also generate electricity at night, the heat storage process can also be performed at night, that is, the usable waste heat in the medium-temperature synthesis gas can be stored in the medium-temperature energy storage tank 2 through the first heat exchanger 8, and then the low-temperature molten salt and the medium-temperature molten salt are heated to high-temperature molten salt through the heater, thereby realizing energy storage.

[0072] This embodiment combines a photovoltaic power station or a wind power station with an energy storage system, and can convert the excess electricity generated by the photovoltaic power station during the day or the excess electricity generated by the wind power station into heat and store it in the high-temperature energy storage tank 3. At night or other times when electricity is used, the high-temperature molten salt and water are exchanged to generate superheated steam to drive the turbine generator set to generate electricity, thereby achieving the effects of peak shaving and valley filling and system frequency modulation, and providing flexibility for power supply. In addition, in addition to using a photovoltaic power station or a wind power station to provide the heater with electricity for heating the molten salt, valley electricity from a thermal power station or other power system can also be used to provide electricity for the heater.

[0073] Optionally, the first heater 12 and / or the second heater 13 is a solar thermal collector; the solar thermal collector directly heats the energy storage medium; or the solar thermal collector indirectly heats the energy storage medium via a heat-conducting medium.

[0074] Specifically, at least one of the first heater 12 and the second heater 13 is a solar collector, and the molten salt can be directly heated by the solar collector. The solar collector can also be used to heat a heat transfer medium such as thermal oil, and the molten salt is heated by the heat transfer medium to absorb the low-grade energy produced by the solar collector.

[0075] Optionally, refer to Figure 1 A heat release passage is formed between the outlet of the high-temperature energy storage tank 3 and the inlet of the low-temperature energy storage tank 1. The heat release passage is provided with at least one second heat exchanger. The inlet of the second heat exchanger is communicated with the outlet of the high-temperature energy storage tank 3, and the outlet of the second heat exchanger is communicated with the inlet of the low-temperature energy storage tank 1. The second heat exchanger is used for exchanging heat between water and energy storage medium and outputting superheated steam.

[0076] Specifically, the inlet of the second heat exchanger is connected to the outlet of the high-temperature energy storage tank 3, and the outlet of the second heat exchanger is connected to the inlet of the low-temperature energy storage tank 1. In the heat release stage, the high-temperature molten salt enters the second heat exchanger to exchange heat with water, thereby heating the water into superheated steam, and then the superheated steam is supplied to the steam turbine generator set to generate electricity, while the high-temperature molten salt is cooled to low-temperature molten salt and flows back to the low-temperature energy storage tank 1 for storage.

[0077] In the embodiment of the present application, power generation is achieved by utilizing the heat in the high-temperature molten salt, thereby realizing energy recovery and utilization.

[0078] Optionally, there are two second heat exchangers, which are arranged in series in the heat release passage; the second heat exchanger close to the low-temperature energy storage tank 1 is used for heat exchange between water and the energy storage medium and outputs saturated steam, and the second heat exchanger close to the high-temperature energy storage tank 3 is used for heat exchange between the saturated steam and the high-temperature energy storage medium and outputs superheated steam.

[0079] Specifically, there are two second heat exchangers, which are a water and molten salt heat exchanger and a saturated steam and molten salt heat exchanger respectively; wherein the water and molten salt heat exchanger is arranged close to the low-temperature energy storage tank 1, while the saturated steam and molten salt heat exchanger is arranged close to the high-temperature energy storage tank 3; when releasing heat, the high-temperature molten salt first enters the saturated steam and molten salt heat exchanger to heat the saturated steam into superheated steam, and then the molten salt with reduced temperature enters the water and molten salt heat exchanger to exchange heat with the water to heat the water into saturated steam; in this embodiment, the two second heat exchangers are used to realize the step-by-step utilization of energy, thereby improving the utilization efficiency of energy and reducing the waste of energy.

[0080] Optionally, refer to Figure 1 There are three second heat exchangers, and the three second heat exchangers are arranged in series in the heat release passage.

[0081] Specifically, there are three second heat exchangers, namely, a superheater 9, an evaporator 10 and a preheater 11, wherein the molten salt inlet of the superheater 9 is connected to the molten salt outlet of the high-temperature energy storage tank 3, the molten salt inlet of the evaporator 10 is connected to the molten salt outlet of the superheater 9, the molten salt outlet of the evaporator 10 is connected to the molten salt inlet of the preheater 11, and the molten salt outlet of the preheater 11 is connected to the molten salt inlet of the low-temperature energy storage tank 1.

[0082] When releasing heat, the high-temperature molten salt first enters the superheater 9, and the high-temperature molten salt heats the saturated steam into superheated steam. The molten salt with reduced temperature then enters the evaporator 10 to exchange heat with water, and the molten salt with reduced temperature heats the water into saturated steam. Then the molten salt with reduced temperature again enters the preheater 11 to preheat the cold water entering the preheater 11.

[0083] This embodiment realizes the cascade utilization of energy through three second heat exchangers, thereby improving the energy utilization efficiency and reducing energy waste.

[0084] Optionally, the heat release passage is provided with a fourth delivery pump 7, and the fourth delivery pump 7 is located between the outlet of the high-temperature energy storage tank 3 and the inlet of the second heat exchanger.

[0085] Specifically, the fourth delivery pump 7 is located between the outlet of the high-temperature energy storage tank 3 and the molten salt inlet of the superheater 9. By adjusting the fourth delivery pump 7, the on-off of the heat release passage and the flow rate of the molten salt can be controlled, thereby controlling the heat release efficiency of the entire energy storage system.

[0086] Optionally, the heat in the heat exchange medium comes from industrial waste heat.

[0087] Specifically, the heat exchange medium can be various substances containing usable waste heat produced in industry, and its specific state can be liquid, gaseous or solid, or a gas-liquid or solid-liquid mixture, which is not limited in the embodiments of the present application; in the industrial production process, industrial substances with usable waste heat are exchanged with low-temperature molten salt, and the low-temperature molten salt is heated to medium-temperature molten salt, so that the usable waste heat is stored in the medium-temperature molten salt and utilized to reduce energy waste.

[0088] Optionally, it further comprises a synthetic ammonia system, and the heat exchange medium is the medium-temperature synthesis gas produced by the synthetic ammonia system.

[0089] Specifically, in the industrial field, a variety of synthesis gases with temperatures between low-temperature molten salt and high-temperature molten salt will be produced; for example, in the process of chemical synthesis of ammonia, medium-temperature synthesis gas will be produced, and the temperature of the usable waste heat in the medium-temperature synthesis gas is between that of the low-temperature molten salt and the high-temperature molten salt; the medium-temperature synthesis gas is passed into the first heat exchanger 8, the medium-temperature synthesis gas exchanges heat with the low-temperature molten salt, the low-temperature molten salt is heated into medium-temperature molten salt and stored in the medium-temperature energy storage tank 2, and the synthesis gas with reduced temperature is discharged from the first heat exchanger 8 and returned to the chemical area.

[0090] This embodiment stores the usable waste heat in the medium-temperature synthesis gas in the medium-temperature molten salt and uses it for subsequent power generation, thereby realizing energy recovery and reducing energy waste.

[0091] Optionally, at least one of the low-temperature energy storage tank 1 , the medium-temperature energy storage tank 2 and the high-temperature energy storage tank 3 is provided with a heat preservation structure.

[0092] Specifically, in low temperature or cold conditions, the energy storage tank will be exposed to the external environment for a long time, which will cause the heat inside the energy storage tank to be lost. Therefore, a thermal insulation structure can be set on the energy storage tank to reduce the heat loss inside the energy storage tank.

[0093] Optionally, the heat preservation structure is provided inside the energy storage tank and / or outside the energy storage tank.

[0094] Specifically, a thermal insulation structure may be provided on the outside of the energy storage tank or on the inside of the energy storage tank. To improve the thermal insulation effect, a thermal insulation structure may be provided on both the outside and the inside of the energy storage tank. For example, a thermal insulation structure similar to a heating pipe may be provided on the inner or outer wall of the energy storage tank, and a high-temperature thermal insulation medium may be passed into the heating pipe to reduce heat loss inside the energy storage tank. In addition, a thermal insulation structure similar to a thermal insulation layer may be coated on the inner or outer wall of the energy storage tank, and an electric heating wire may be provided on the inner or outer wall of the energy storage tank to reduce heat loss inside the energy storage tank.

[0095] Optionally, the thermal insulation structure is a thermal insulation pipe.

[0096] Specifically, an insulation pipe is wound around the outer wall of the energy storage tank, or an insulation pipe is wound around the inner wall of the energy storage tank, and an insulation medium is introduced into the insulation pipe. The insulation medium is used to maintain the temperature of the molten salt in the energy storage tank to reduce heat loss inside the energy storage tank.

[0097] Optionally, the insulation medium in the insulation pipe includes at least one of saturated steam, superheated steam and medium-temperature synthesis gas.

[0098] Specifically, the insulation medium in the insulation pipe can be one of the saturated steam, superheated steam or medium-temperature synthesis gas in the aforementioned embodiments, or a mixture of saturated steam, superheated steam or medium-temperature synthesis gas, wherein the medium-temperature synthesis gas can come from the synthetic ammonia section; the insulation medium containing usable waste heat is passed into the insulation pipe to reduce heat loss inside the energy storage tank.

[0099] It should be noted that in addition to the medium-temperature synthesis gas, saturated steam and superheated steam generated in the heat release stage, which can be used as the insulation medium in the insulation pipe, the synthesis gas with reduced temperature can also be passed into the insulation pipe as the insulation medium, which not only reduces the heat loss inside the energy storage tank, but also realizes the full utilization of the energy in the energy storage system.

[0100] The utility model also provides a power generation system, which comprises a steam turbine generator set and the above energy storage system, wherein the superheated steam outputted by the above energy storage system in the heat release stage drives the steam turbine generator set to generate electricity.

[0101] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0102] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. An energy storage system, characterized in that: The invention comprises a low-temperature energy storage tank for storing a low-temperature energy storage medium and a high-temperature energy storage tank for storing a high-temperature energy storage medium, wherein a first heat storage passage and a second heat storage passage are formed between an outlet of the low-temperature energy storage tank and an inlet of the high-temperature energy storage tank, and the first heat storage passage and the second heat storage passage are arranged in parallel; The first heat storage passage is provided with a first heater, the inlet of the first heater is communicated with the outlet of the low-temperature energy storage tank, and the outlet of the first heater is communicated with the inlet of the high-temperature energy storage tank; The second heat storage passage is sequentially provided with a first heat exchanger, a medium-temperature energy storage tank and a second heater in series, the inlet of the first heat exchanger is communicated with the outlet of the low-temperature energy storage tank, the outlet of the second heater is communicated with the inlet of the high-temperature energy storage tank, the first heat exchanger is used for heat exchange between a heat exchange medium and an energy storage medium, and the medium-temperature energy storage tank is used for storing a medium-temperature energy storage medium whose temperature is between the low-temperature energy storage medium and the high-temperature energy storage medium.

2. The energy storage system according to claim 1, characterized in that: There are at least two second heat storage pathways, and at least two of the second heat storage pathways are arranged in parallel. Each of the second heat storage pathways is provided with the first heat exchanger, the medium-temperature energy storage tank and the second heater in series.

3. The energy storage system according to claim 1 or 2, characterized in that: At least one of the second heat storage passages is provided with at least two medium-temperature energy storage tanks having different storage temperatures in series, the first heat exchanger is provided between the low-temperature energy storage tank and the medium-temperature energy storage tank adjacent to the low-temperature energy storage tank, and the first heat exchanger is provided between two adjacent medium-temperature energy storage tanks.

4. The energy storage system according to claim 1 or 2, characterized in that: The first heat storage passage is provided with a first delivery pump, and the first delivery pump is located between the outlet of the low-temperature energy storage tank and the inlet of the first heater.

5. The energy storage system according to claim 1 or 2, characterized in that: The second heat storage passage is provided with a second delivery pump, and the second delivery pump is located between the outlet of the low-temperature energy storage tank and the inlet of the first heat exchanger.

6. The energy storage system according to claim 1 or 2, characterized in that: The second heat storage passage is provided with a third delivery pump, and the third delivery pump is located between the outlet of the medium-temperature energy storage tank and the inlet of the second heater.

7. The energy storage system according to claim 1 or 2, characterized in that: The first heater And / or the second heater is an electric heater.

8. The energy storage system according to claim 7, characterized in that: The system further comprises a photovoltaic power station and / or a wind power station, wherein the first heater and / or the second heater is electrically connected to at least one of the photovoltaic power station and the wind power station.

9. The energy storage system according to claim 1 or 2, characterized in that: The first heater and / or the second heater is a solar thermal collector; The solar thermal collector directly heats the energy storage medium; or, The solar thermal collector indirectly heats the energy storage medium via a heat transfer medium.

10. The energy storage system according to claim 1 or 2, characterized in that: A heat release passage is formed between the outlet of the high-temperature energy storage tank and the inlet of the low-temperature energy storage tank. The heat release passage is provided with at least one second heat exchanger. The inlet of the second heat exchanger is communicated with the outlet of the high-temperature energy storage tank. The outlet of the second heat exchanger is communicated with the inlet of the low-temperature energy storage tank. The second heat exchanger is used for exchanging heat between water and energy storage medium and outputting superheated steam.

11. The energy storage system according to claim 10, characterized in that: There are two second heat exchangers, and the two second heat exchangers are arranged in series in the heat release passage; The second heat exchanger close to the low-temperature energy storage tank is used for heat exchange between water and the energy storage medium and outputting saturated steam, and the second heat exchanger close to the high-temperature energy storage tank is used for heat exchange between the saturated steam and the energy storage medium and outputting superheated steam.

12. The energy storage system according to claim 10, characterized in that: There are three second heat exchangers, and the three second heat exchangers are arranged in series in the heat release passage.

13. The energy storage system according to claim 10, characterized in that: The heat release passage is provided with a fourth delivery pump, and the fourth delivery pump is located between the outlet of the high-temperature energy storage tank and the inlet of the second heat exchanger.

14. The energy storage system according to claim 1 or 2, characterized in that: The heat of the heat exchange medium comes from industrial waste heat.

15. The energy storage system according to claim 14, characterized in that: It also includes a synthetic ammonia system, and the heat exchange medium is the medium-temperature synthesis gas produced by the synthetic ammonia system.

16. The energy storage system according to claim 1 or 2, characterized in that: Among the low-temperature energy storage tank, the medium-temperature energy storage tank and the high-temperature energy storage tank, at least one of the energy storage tanks is provided with a heat preservation structure.

17. The energy storage system according to claim 16, characterized in that: The heat preservation structure is arranged inside the energy storage tank and / or outside the energy storage tank.

18. The energy storage system according to claim 17, characterized in that: The thermal insulation structure is a thermal insulation pipe.

19. The energy storage system according to claim 18, characterized in that: The heat preservation medium in the heat preservation tube includes at least one of saturated steam, superheated steam and medium-temperature synthesis gas.

20. A power generation system, comprising a steam turbine generator set and an energy storage system according to any one of claims 1 to 19, characterized in that: The superheated steam outputted by the energy storage system during the heat release phase drives the steam turbine generator set to generate electricity.

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