Electricity-steam combined supply electricity and heat storage system and operation method

Abstract

The invention relates to the technical field of energy storage, and provides an electricity-steam combined supply electricity and heat storage system and an operation method, and the system comprises a low-temperature storage tank, a low-temperature heat storage module, a compression / expansion device, a high-temperature heat storage module and a high-temperature storage tank which are sequentially connected in the working medium flow direction; the low-temperature storage tank is used for storing low-temperature saturated liquid working media; the low-temperature heat storage module is used for heating the working medium flowing to the compression / expansion device from the low-temperature storage tank or cooling the working medium returning to the low-temperature storage tank from the compression / expansion device; the high-temperature heat storage module is used for cooling the working medium flowing from the compression / expansion device to the high-temperature storage tank or heating the working medium flowing from the high-temperature storage tank to the compression / expansion device; the high-temperature storage tank is used for storing high-temperature saturated liquid working media. Through the arrangement, the defects of complex structure, multiple thermal parts and thermal processes and low efficiency of the Carnot battery in the prior art can be effectively overcome, and the Carnot battery has the advantages of simple structure, low construction cost, few thermal processes and high operation efficiency.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, and in particular to an electric-steam combined heat and power storage system and its operation method. Background Technology

[0002] In the current industrial production sector, the temporal contradiction between energy supply and demand is becoming increasingly prominent, becoming a key factor restricting the efficient operation and cost control of energy-intensive enterprises. On the one hand, influenced by multiple factors such as the social electricity consumption structure and the pace of industrial production, the characteristics of power generation load variation and electricity consumption load variation generally exhibit a peak-valley misalignment, leading to significant price differences between peak and off-peak electricity in the electricity market. However, the core production processes of many high-energy-consuming enterprises have rigid electricity demand characteristics, and their peak electricity consumption often overlaps with the peak power supply of the grid, causing enterprises to bear high electricity costs during peak periods, greatly increasing the pressure on production and operation. On the other hand, these energy-consuming enterprises usually also have stable industrial park heating needs during their production processes, which places higher demands on the integration of energy systems. This requires not only solving the "peak-valley electricity consumption" problem to reduce electricity costs, but also achieving coordinated supply of electricity and steam to meet the diversified energy needs of enterprises.

[0003] Therefore, how to balance energy and thermal storage, high-efficiency integration, and combined power and steam supply to achieve energy conservation, cost reduction, and improved energy utilization efficiency has become a common pursuit for energy-consuming enterprises. Compared with other energy storage methods such as electrochemical energy storage, carbon dioxide / air energy storage, and pumped hydro storage, Carnot battery energy storage technology has become one of the ideal choices for enterprise-level energy storage scenarios due to its advantages such as high energy density, less susceptibility to geographical conditions, and strong operational stability.

[0004] Traditional closed-loop Carnot battery energy storage systems require two systems—a heat pump cycle and a heat engine cycle—to achieve the energy storage and release process. Patent CN119491752A represents a typical structure, but this type of Carnot battery is complex and has high construction costs. To address the drawbacks of the traditional dual-cycle structure of Carnot batteries, related fields have optimized its structure. The most representative example is patent CN116006284B, which uses a reversible screw compressor to change the dual-cycle to a single-cycle system, with an auxiliary heat accumulator for cold and heat storage. However, it still suffers from problems such as complex structure, numerous thermal components and processes, and low efficiency.

[0005] Given the above problems, how to further simplify the structure, reduce construction costs, and improve efficiency has become an important technical challenge that urgently needs to be solved. Summary of the Invention

[0006] This invention provides an electric-steam combined power storage and thermal energy storage system and its operation method, which solves the defects of the existing Carnot battery in terms of complex structure, numerous thermal components and thermal processes, and low efficiency. It has the advantages of simple structure, low construction cost, fewer thermal processes, and high operating efficiency.

[0007] This invention provides an electric and thermal energy storage system for combined power and steam generation, comprising: The cryogenic storage tank, cryogenic heat storage module, compression / expansion device, high-temperature heat storage module and high-temperature storage tank are connected sequentially in the working fluid flow direction; The cryogenic storage tank is used to store cryogenic saturated liquid working fluid; The cryogenic heat storage module is used to heat the working fluid flowing from the cryogenic storage tank to the compression / expansion device, which is either a gas-liquid two-phase or gas phase, or to cool the working fluid returning from the compression / expansion device to the cryogenic storage tank, which is a cryogenic saturated liquid. The high-temperature heat storage module is used to cool the working fluid flowing from the compression / expansion device to the high-temperature storage tank as a high-temperature saturated liquid, or to heat the working fluid flowing from the high-temperature storage tank to the compression / expansion device as a gas-liquid two-phase or gas phase. The high-temperature storage tank is used to store high-temperature saturated liquid working fluid.

[0008] According to the present invention, a combined electric and steam power energy storage and thermal energy storage system is provided, wherein the low-temperature thermal energy storage module comprises: A low-temperature latent heat accumulator contains a low-temperature latent heat storage medium for heat exchange of the working fluid during the low-temperature latent heat stage.

[0009] According to the electric-steam combined power supply and energy storage system provided by the present invention, the low-temperature thermal storage module further includes: A low-temperature sensible heat accumulator is connected between the low-temperature latent heat accumulator and the compression / expansion device; the low-temperature sensible heat accumulator contains a low-temperature sensible heat storage medium for heat exchange of the working fluid during the low-temperature sensible heat stage.

[0010] According to the present invention, a combined electric and steam power energy storage and thermal energy storage system is provided, wherein the low-temperature sensible heat storage device comprises: A low-temperature heat exchanger, having a low-temperature side and a high-temperature side; The cryogenic sensible heat medium storage tank includes a first cryogenic medium storage tank disposed on the high-temperature side of the cryogenic heat exchanger and a second cryogenic medium storage tank disposed on the low-temperature side of the cryogenic heat exchanger.

[0011] According to the present invention, a combined electric and steam power energy storage and thermal energy storage system is provided, wherein the high-temperature thermal energy storage module comprises: A high-temperature latent heat accumulator contains a high-temperature latent heat storage medium for heat exchange of the working fluid during the high-temperature latent heat stage.

[0012] According to the electric-steam combined power supply and energy storage system provided by the present invention, the high-temperature heat storage module further includes: A high-temperature sensible heat accumulator is connected between the compression / expansion device and the high-temperature latent heat accumulator; the high-temperature sensible heat accumulator contains a high-temperature sensible heat storage medium for heat exchange of the working fluid during the high-temperature sensible heat stage.

[0013] According to the present invention, a combined electric and steam power energy storage and thermal energy storage system is provided, wherein the high-temperature sensible heat storage device comprises: High-temperature heat exchangers have a low-temperature side and a high-temperature side; The high-temperature sensible heat medium storage tank includes a first high-temperature medium storage tank disposed on the high-temperature side of the high-temperature heat exchanger and a second high-temperature medium storage tank disposed on the low-temperature side of the high-temperature heat exchanger.

[0014] According to the present invention, a power-steam combined heat and power storage system is provided, wherein the low-temperature latent heat storage medium and the high-temperature latent heat storage medium are configured as solid-liquid phase change materials; and / or, The low-temperature sensible heat storage medium and the high-temperature sensible heat storage medium include pressurized water, heat transfer oil, or molten salt; and / or, The working medium includes water, ethylene glycol, methanol, or ethanol.

[0015] According to the present invention, a power-steam combined heat and power storage system further includes a heat extraction module, wherein the heat extraction module comprises: A heat exchange device, integrated into the low-temperature heat storage module, is connected to a heat extraction pipe for extracting residual heat from the low-temperature heat storage module after its operation; and / or, A low-temperature heat exchanger, connected to the low-temperature storage tank, is used to cool the working fluid inside the low-temperature storage tank; and / or, A high-temperature heat exchanger is connected to the high-temperature storage tank and is used to cool the working fluid inside the high-temperature storage tank.

[0016] According to the present invention, a power-steam combined heat and power storage system is provided, wherein the low-temperature latent heat storage medium is selected from polymer wax or aromatic compounds; The high-temperature latent heat storage medium is selected from lithium nitrate, sodium nitrate, potassium nitrate, calcium nitrate or sodium chloride, potassium chloride, calcium chloride, magnesium chloride.

[0017] According to the present invention, a power-steam combined heat and power storage system is provided, wherein the compression / expansion device includes a reversible compression / expansion device.

[0018] According to the present invention, a power-steam combined heat and power storage system is provided, wherein the compression / expansion device includes a separate compressor and an expander.

[0019] The present invention also provides an operation method for an electric power-steam combined energy storage and thermal energy storage system, used in any of the above-mentioned electric power-steam combined energy storage and thermal energy storage systems, the method comprising the following steps: During the energy storage process, the low-temperature saturated liquid working fluid is discharged from the low-temperature storage tank and enters the low-temperature heat storage module to absorb heat, obtaining a low-temperature gas-liquid two-phase working fluid or a low-temperature superheated working fluid; the low-temperature gas-liquid two-phase working fluid or the low-temperature superheated working fluid enters the compression / expansion device for compression, obtaining a high-temperature gas-liquid two-phase working fluid or a high-temperature superheated working fluid; the high-temperature gas-liquid two-phase working fluid or the high-temperature superheated working fluid enters the high-temperature heat storage module to release heat and completely liquefy, obtaining a high-temperature saturated liquid working fluid; the high-temperature saturated liquid working fluid enters the high-temperature storage tank for storage. During the energy release process, the high-temperature saturated liquid working fluid is discharged from the high-temperature storage tank and enters the high-temperature heat storage module to absorb heat, resulting in a high-temperature gas-liquid two-phase working fluid or a high-temperature superheated working fluid. The high-temperature gas-liquid two-phase working fluid or the high-temperature superheated working fluid enters the compression / expansion device to expand and generate electricity, resulting in a low-temperature gas-liquid two-phase working fluid or a low-temperature superheated working fluid. The low-temperature gas-liquid two-phase working fluid or the low-temperature superheated working fluid enters the low-temperature heat storage module to release heat and completely liquefy, resulting in a low-temperature saturated liquid working fluid. The low-temperature saturated liquid working fluid enters the low-temperature storage tank for storage. During the heat extraction process, the heat extraction module extracts heat to generate heating steam; cools the high-temperature storage tank and the low-temperature storage tank to increase the temperature difference for subsequent working fluid heat exchange; and removes excess heat from the low-temperature heat storage module to maintain the system's thermal balance.

[0020] The electric power-steam combined heat and power storage system and its operation method provided by this invention have three processes: energy storage and energy release. In the energy storage process, a low-temperature saturated liquid working fluid is discharged from a low-temperature storage tank. During the discharge process, the pressure and temperature remain stable. The saturated liquid working fluid enters a low-temperature thermal storage module to absorb heat and enters a gas-liquid two-phase or gas phase. Subsequently, the working fluid enters a compression / expansion device, which consumes electrical energy to compress the working fluid to obtain a high-temperature two-phase or gas phase working fluid. The compressed high-temperature two-phase or gas phase working fluid enters a high-temperature thermal storage module to release heat and completely liquefy, obtaining a high-temperature saturated liquid working fluid. The high-temperature saturated liquid working fluid enters a high-temperature storage tank for storage, realizing electrothermal conversion and completing the energy storage process.

[0021] In the energy release process, the high-temperature saturated liquid working fluid enters the high-temperature heat storage module to absorb heat and obtain a high-temperature two-phase or gaseous working fluid. Subsequently, the high-temperature two-phase or gaseous working fluid enters the compression / expansion device, which expands and does work to generate electricity, while simultaneously obtaining a low-temperature two-phase or gaseous working fluid. The low-temperature two-phase or gaseous working fluid enters the low-temperature heat storage module to release heat and completely liquefy, obtaining a low-temperature saturated liquid working fluid. The low-temperature saturated liquid working fluid enters the low-temperature storage tank for storage, realizing thermoelectric conversion and completing the energy release process. During the heat extraction process, the heat extraction module extracts heat to generate heating steam; cools the high-temperature storage tank and the low-temperature storage tank to increase the temperature difference for subsequent working fluid heat exchange; and removes excess heat from the low-temperature heat storage module to maintain the system's thermal balance.

[0022] Compared to related technologies, this system reduces thermal components such as throttling mechanisms and valve devices, resulting in a simpler structure and lower construction costs. By introducing cryogenic and high-temperature storage tanks to store the liquid working fluid, it breaks the internal circulation, reduces thermal processes, lowers heat loss, and improves system efficiency. Furthermore, storing the working fluid in liquid form lowers the requirements for the working volume and pressure of the storage tanks. Compared to systems storing pressure potential energy such as carbon dioxide, liquid-stored working fluid not only has a higher energy density but also effectively avoids system slippage, ensuring high-efficiency operation. In addition, excess heat during energy storage and release can be used for steam supply. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of a combined power and steam energy storage and thermal energy storage system provided in one embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the structure of a combined power and steam energy storage and thermal energy storage system provided in another embodiment of the present invention.

[0026] Figure 3 This is a schematic diagram of the temperature entropy during the operation of the combined power and steam energy storage and thermal energy storage system provided in this embodiment of the invention.

[0027] Figure label: 10. Low-temperature storage tank; 20. Low-temperature heat storage module; 21. Low-temperature latent heat accumulator; 22. Low-temperature sensible heat accumulator; 221. Low-temperature heat exchanger; 222. First low-temperature medium storage tank; 223. Second low-temperature medium storage tank; 30. Compression / expansion device; 40. High-temperature heat storage module; 41. High-temperature latent heat accumulator; 42. High-temperature sensible heat accumulator; 421. High-temperature heat exchanger; 422. First high-temperature medium storage tank; 423. Second high-temperature medium storage tank; 50. High-temperature storage tank; 61. Heat extraction pipe; 62. Low-temperature heat extraction heat exchanger; 63. High-temperature heat extraction heat exchanger. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0029] To better understand the combined power-steam energy storage and thermal energy storage system and operation method provided by this invention, we first introduce its application background. In the current industrial production field, how to balance energy storage and thermal energy storage, high-efficiency integration, and combined power-steam supply to achieve energy conservation, cost reduction, and improved energy utilization efficiency has become a common aspiration for energy-consuming enterprises. Compared with other energy storage methods such as electrochemical energy storage, carbon dioxide / air energy storage, and pumped hydro storage, Carnot battery energy storage technology, with its advantages of high energy density, less susceptibility to geographical conditions, and strong operational stability, has become one of the ideal choices for enterprise-level energy storage scenarios.

[0030] Traditional closed-loop Carnot battery energy storage systems require two systems—a heat pump cycle and a heat engine cycle—to achieve the energy storage and power generation process. Patent CN119491752A represents a typical structure, but this type of Carnot battery is complex and has high construction costs. To address the drawbacks of the traditional dual-cycle Carnot battery structure, related fields have optimized its structure. The most representative example is patent CN116006284B, which uses a reversible screw compressor to change the dual-cycle to a single-cycle system, with an auxiliary heat accumulator for cold and heat storage. However, it still suffers from problems such as complex structure, numerous thermal components and processes, and low efficiency.

[0031] In view of the above problems, embodiments of the present invention provide an electric-steam combined power storage and thermal energy storage system and its operation method, which has the advantages of simple structure, low construction cost, few thermal processes, and high operating efficiency.

[0032] The following is combined Figures 1 to 3 The present invention describes the electric power-steam combined heat and power storage system and its operation method.

[0033] Reference Figure 1 and Figure 2A combined power and steam energy storage system includes: a cryogenic storage tank 10, a cryogenic heat storage module 20, a compression / expansion device 30, a high-temperature heat storage module 40, and a high-temperature storage tank 50 connected sequentially in the working fluid flow direction; wherein, the cryogenic storage tank 10 is used to store a cryogenic saturated liquid working fluid; the cryogenic heat storage module 20 is used to heat the working fluid flowing from the cryogenic storage tank 10 to the compression / expansion device 30 as a gas-liquid two-phase or gas phase, or to cool the working fluid returning from the compression / expansion device 30 to the cryogenic storage tank 10 as a cryogenic saturated liquid; the high-temperature heat storage module 40 is used to cool the working fluid flowing from the compression / expansion device 30 to the high-temperature storage tank 50 as a high-temperature saturated liquid, or to heat the working fluid flowing from the high-temperature storage tank 50 to the compression / expansion device 30 as a gas-liquid two-phase or gas phase; the compression / expansion device 30 can switch between compression and expansion states; and the high-temperature storage tank 50 is used to store a high-temperature liquid working fluid.

[0034] It also includes a heat extraction module, which includes a heat exchange device, a low-temperature heat exchanger 62, and a high-temperature heat exchanger 63. The heat exchange device is integrated into the low-temperature heat storage module 20 and is connected to a heat extraction pipe 61 to extract the residual heat after the low-temperature heat storage module 20 has been working. The low-temperature heat exchanger 62 is connected to the low-temperature storage tank 10 to cool the working medium in the low-temperature storage tank 10. The high-temperature heat exchanger 63 is connected to the high-temperature storage tank 50 to cool the working medium in the high-temperature storage tank 50.

[0035] In a practical application scenario, the aforementioned combined electricity and steam energy storage and thermal energy storage system involves three processes: energy storage, energy release, and heat extraction. In the energy storage process, the low-temperature saturated liquid working fluid is discharged from the low-temperature storage tank 10. During the discharge process, the pressure and temperature remain stable. The saturated liquid working fluid enters the low-temperature heat storage module 20 to absorb heat and enters the gas-liquid two-phase or gas phase. Subsequently, the working fluid enters the compression / expansion device 30. The compression / expansion device 30 consumes electrical energy to compress the working fluid to obtain a high-temperature two-phase or gas phase working fluid. The compressed high-temperature two-phase or gas phase working fluid enters the high-temperature heat storage module 40 to release heat and completely liquefy, obtaining a high-temperature saturated liquid working fluid. The high-temperature saturated liquid working fluid enters the high-temperature storage tank 50 for storage, realizing electrothermal conversion and completing the energy storage process.

[0036] In the energy release process, the high-temperature saturated liquid working fluid enters the high-temperature heat storage module 40 to absorb heat and obtain a high-temperature two-phase or gaseous working fluid. Subsequently, the high-temperature two-phase or gaseous working fluid enters the compression / expansion device 30, which expands and performs work to generate electricity, while simultaneously obtaining a low-temperature two-phase or gaseous working fluid. The low-temperature two-phase or gaseous working fluid enters the low-temperature heat storage module 20 to release heat and completely liquefy, obtaining a low-temperature saturated liquid working fluid. The low-temperature saturated liquid working fluid enters the low-temperature storage tank 10 for storage, realizing thermoelectric conversion and completing the energy release process.

[0037] During the heat extraction process, the heat extraction module extracts heat to generate heating steam; it lowers the temperature of the high-temperature storage tank 50 and the low-temperature storage tank 10, increasing the temperature difference for subsequent working fluid heat exchange; and it extracts excess heat from the low-temperature heat storage module 20 to maintain the system's thermal balance.

[0038] Compared to related technologies, this system reduces thermal components such as throttling mechanisms and valve devices, resulting in a simpler structure and lower construction costs. By introducing cryogenic storage tank 10 and high-temperature storage tank 50 to store the liquid working fluid, it breaks the internal circulation, reduces thermal processes, lowers heat loss, and improves system efficiency. Furthermore, storing the working fluid in liquid form lowers the requirements for the working volume and pressure of the storage tanks. Compared to systems storing pressure potential energy such as carbon dioxide, liquid-stored working fluid not only has a higher energy density but also effectively avoids system slippage, ensuring high-efficiency operation. In addition, excess heat during energy storage and release can be used for steam supply.

[0039] It is understood that the compression / expansion device 30 can be configured as a reversible compression / expansion device, which is a device capable of performing both compression and expansion work in the same unit. The compression / expansion device 30 can also be configured as a separate compressor and expander, using the compressor to compress the working fluid and the expander to perform work. Furthermore, depending on the working principle, the compression / expansion device 30 can be configured as a screw type, axial flow type, centrifugal type, etc. The specific structural form of the compression / expansion device 30 is not specifically limited in this embodiment of the invention, and as existing mature technologies, the specific structure and working principle of each of the above devices can be referred to existing technologies, which will not be elaborated upon in this embodiment of the invention.

[0040] Furthermore, the specific structure, material, size, and other specifications of the cryogenic storage tank 10 and the high-temperature storage tank 50, as containers for storing liquid working fluids, need to be adapted to actual needs, such as the type of working fluid, temperature, pressure, thermal insulation requirements, and overall system operation requirements. No specific restrictions are imposed in this embodiment of the invention.

[0041] To elaborate further, the temperature of cryogenic storage tank 10 is between 100℃ and 200℃, depending on actual needs and the performance of the working medium; the temperature of cryogenic storage tank 50 is determined by the performance of the working medium, but is below the critical temperature of the working medium.

[0042] In some optional examples of the present invention, the specific types of working fluid include, but are not limited to, liquids with two-phase properties such as water, ethylene glycol, methanol, and ethanol.

[0043] It is understandable that during the operation of the aforementioned combined power and steam energy storage and thermal energy storage system, the working fluid undergoes three round-trip processes: compression and expansion of the working fluid both occur in the two-phase region (e.g., Figure 3 In process 2), the compression and expansion of the working fluid both occur in the superheated zone (e.g., Figure 3 In process 1-A), the compression and expansion of the working fluid occur in the two-phase region and the superheated region (e.g., ...). Figure 3 (Process 1-B in the process). The specific selection and design need to be based on the system load requirements, efficiency, and working fluid characteristics. In order to ensure that the working fluid entering the compression / expansion device 30 reaches the required phase state, the specific structural forms of the low-temperature heat storage module 20 and the high-temperature heat storage module 40 need to be designed specifically, which will be introduced one by one below.

[0044] In one example of the present invention, when a two-phase compression / expansion device 30 is used, both the compression and expansion of the working fluid occur in the two-phase region. Under the above operating conditions: The low-temperature heat storage module 20 includes a low-temperature latent heat accumulator 21, which contains a low-temperature latent heat storage medium for heat exchange of the working fluid during the low-temperature latent heat stage. The high-temperature heat storage module 40 includes a high-temperature latent heat accumulator 41, which contains a high-temperature latent heat storage medium for heat exchange of the working fluid during the high-temperature latent heat stage.

[0045] Through the above technical solution, during the energy storage process, the low-temperature saturated liquid working fluid is discharged from the low-temperature storage tank 10 and enters the low-temperature latent heat accumulator 21. During the low-temperature latent heat stage, the working fluid exchanges heat with the low-temperature latent heat storage medium to obtain a low-temperature gas-liquid two-phase working fluid. This low-temperature gas-liquid two-phase working fluid then enters the compression / expansion device 30 and is compressed into a high-temperature gas-liquid two-phase working fluid. The high-temperature gas-liquid two-phase working fluid enters the high-temperature latent heat accumulator 41, where it exchanges heat with the high-temperature latent heat storage medium during the high-temperature latent heat stage. The high-temperature latent heat storage medium absorbs and stores the latent heat of phase change of the high-temperature gas-liquid two-phase working fluid, causing it to completely liquefy into a high-temperature saturated liquid working fluid. This high-temperature saturated liquid working fluid is then stored in the high-temperature storage tank 50. This achieves electrothermal conversion.

[0046] During the energy release process, the high-temperature saturated liquid working fluid discharged from the high-temperature storage tank 50 enters the high-temperature latent heat accumulator 41 to absorb heat, obtaining a high-temperature gas-liquid two-phase working fluid. This high-temperature gas-liquid two-phase working fluid then enters the compression / expansion device 30, which performs work to generate electricity, producing a low-temperature gas-liquid two-phase working fluid. This low-temperature gas-liquid two-phase working fluid enters the low-temperature latent heat accumulator 21 and exchanges heat with the low-temperature latent heat storage medium. The low-temperature latent heat storage medium absorbs and stores the latent heat of phase change of the low-temperature gas-liquid two-phase working fluid, causing it to completely liquefy into a low-temperature saturated liquid working fluid. This low-temperature saturated liquid working fluid then enters the low-temperature storage tank 10 for storage. This achieves thermoelectric conversion.

[0047] During the heat extraction process, the heat extraction module extracts heat to generate heating steam; reduces the temperature of the high-temperature storage tank 50 and the low-temperature storage tank 10, and increases the temperature difference of subsequent working fluid heat exchange; and extracts excess heat from the low-temperature heat storage module 20 to maintain the system's thermal balance.

[0048] In detail, the low-temperature latent heat storage medium is configured as a solid-liquid phase change material.

[0049] With this configuration, during energy storage, the low-temperature saturated liquid working fluid absorbs heat upon entering the low-temperature latent heat accumulator 21, entering the gas-liquid two-phase state. Meanwhile, the low-temperature latent heat storage medium releases heat, undergoing a liquid-solid phase change, and the temperature remains stable. During energy release, the low-temperature gas-liquid two-phase working fluid releases heat upon entering the low-temperature latent heat accumulator 21, completely liquefying into a low-temperature saturated liquid working fluid. Meanwhile, the low-temperature latent heat storage medium absorbs heat, undergoing a solid-liquid phase change, and the temperature remains stable.

[0050] It is understandable that the specific type of low-temperature latent heat storage medium can be configured according to actual needs, such as the characteristics of the working fluid, including but not limited to polymer waxes, aromatic compounds, etc.

[0051] Furthermore, the high-temperature latent heat storage medium is configured as a solid-liquid phase change material.

[0052] With this configuration, during energy storage, the high-temperature gas-liquid two-phase working fluid discharged from the compression / expansion device 30 enters the high-temperature latent heat accumulator 41 and releases heat, completely liquefying into a high-temperature saturated liquid working fluid. The high-temperature latent heat storage medium absorbs heat and undergoes a solid-liquid phase change. During energy release, the high-temperature saturated liquid working fluid discharged from the high-temperature storage tank 50 enters the high-temperature latent heat accumulator 41 and absorbs heat, obtaining a high-temperature gas-liquid two-phase working fluid. The high-temperature latent heat storage medium releases heat and undergoes a liquid-solid phase change.

[0053] It is understandable that the specific type of high-temperature latent heat storage medium can be configured according to actual needs, such as the characteristics of the working fluid, including but not limited to nitrates (such as lithium nitrate, sodium nitrate, potassium nitrate, and calcium nitrate) and chlorides (such as sodium chloride, potassium chloride, calcium chloride, and magnesium chloride).

[0054] As a specific example of the above operating conditions, ethylene glycol is used as the working fluid with a flow rate of 900–1000 kg / h; the high-temperature latent heat storage medium is sodium nitrate, and the low-temperature latent heat storage medium is erythritol; the pressure of the high-temperature storage tank 50 is 1 MPa–2 MPa, the pressure of the low-temperature storage tank 10 is 0.005 MPa–0.1 MPa, and the compression / expansion device 30 adopts a reversible screw compressor. The screw compressor discharge temperature is 305℃–320℃ during energy storage and 120℃–130℃ during energy release.

[0055] The specific workflow is as follows: Energy storage process: Low-temperature saturated liquid ethylene glycol is discharged from low-temperature storage tank 10. The ethylene glycol in low-temperature storage tank 10 is in a saturated liquid state, and the pressure and temperature remain stable during the discharge process. The saturated ethylene glycol enters the low-temperature latent heat accumulator 21 to absorb heat, entering a low-temperature gas-liquid two-phase state. The low-temperature latent heat storage medium undergoes a liquid-solid phase change, and the temperature remains stable. The low-temperature gas-liquid two-phase ethylene glycol enters a reversible screw compressor, which consumes electrical energy to compress the ethylene glycol to obtain high-temperature gas-liquid two-phase ethylene glycol. The high-temperature gas-liquid two-phase ethylene glycol enters the high-temperature latent heat accumulator 41 to release heat, obtaining high-temperature saturated liquid ethylene glycol. The high-temperature latent heat storage medium undergoes a solid-liquid phase change, and the high-temperature saturated liquid ethylene glycol enters the high-temperature storage tank 50, where the pressure and temperature remain stable. Electrothermal conversion is achieved, completing the energy storage process.

[0056] Energy release process: High-temperature saturated liquid ethylene glycol is discharged from high-temperature storage tank 50. During the discharge process, the pressure and temperature remain stable. The high-temperature saturated liquid ethylene glycol enters high-temperature latent heat accumulator 41, absorbs heat, and enters a high-temperature gas-liquid two-phase state. The high-temperature latent heat storage medium undergoes a liquid-solid phase change, and the temperature remains stable. The high-temperature gas-liquid two-phase ethylene glycol enters a reversible screw compressor. The reversible screw compressor outputs mechanical work for power generation, simultaneously producing low-temperature gas-liquid two-phase ethylene glycol. The low-temperature gas-liquid two-phase ethylene glycol enters low-temperature latent heat accumulator 21, completely liquefies, and releases heat to obtain low-temperature saturated liquid ethylene glycol. The low-temperature latent heat storage medium undergoes a solid-liquid phase change, and the temperature remains stable. The low-temperature saturated liquid ethylene glycol enters low-temperature storage tank 10, where the pressure and temperature remain stable. Thermoelectric conversion is achieved, completing the energy release process.

[0057] Heat extraction process: During the energy storage and release process, 20℃~30℃ water is used to cool the low temperature storage tank 10, high temperature storage tank 50 and low temperature heat storage module 20 through the heat extraction module, which increases the temperature difference of subsequent working fluid heat exchange, maintains the system thermal balance and obtains usable steam.

[0058] In another example of the present invention, when both the compression and expansion of the working fluid occur in the superheated region, under the above operating conditions: The low-temperature heat storage module 20 also includes a low-temperature sensible heat accumulator 22, which is connected between the low-temperature latent heat accumulator 21 and the compression / expansion device 30. The low-temperature sensible heat accumulator 22 contains a low-temperature sensible heat storage medium for heat exchange of the working fluid during the low-temperature sensible heat stage. The high-temperature heat storage module 40 also includes a high-temperature sensible heat accumulator 42, which is connected between the high-temperature latent heat accumulator 41 and the compression / expansion device 30. The high-temperature sensible heat accumulator 42 contains a high-temperature sensible heat storage medium for heat exchange of the working fluid during the high-temperature sensible heat stage.

[0059] Through the above technical solution, during the energy storage process, the low-temperature saturated liquid working fluid is discharged from the low-temperature storage tank 10 and enters the low-temperature latent heat accumulator 21. During the latent heat stage, the working fluid exchanges heat with the low-temperature latent heat storage medium to obtain a low-temperature gaseous working fluid or a low-temperature gas-liquid two-phase working fluid. The low-temperature gaseous working fluid or the low-temperature gas-liquid two-phase working fluid then enters the low-temperature sensible heat accumulator 22 and exchanges heat with the low-temperature sensible heat storage medium, being heated to a low-temperature superheated working fluid. The low-temperature superheated working fluid enters the compression / expansion device 30 and is further compressed to obtain a high-temperature superheated working fluid. The high-temperature superheated working fluid enters the high-temperature sensible heat accumulator 42, where the high-temperature sensible heat storage medium absorbs and stores the heat of the high-temperature superheated working fluid, resulting in a nearly saturated high-temperature gaseous working fluid. The high-temperature gaseous working fluid enters the high-temperature latent heat accumulator 41, releasing heat and completely liquefying to obtain a high-temperature saturated liquid working fluid. The high-temperature saturated liquid working fluid then enters the high-temperature storage tank 50 for storage, completing the energy storage process.

[0060] During the energy release process, the high-temperature saturated liquid working fluid discharged from the high-temperature storage tank 50 enters the high-temperature latent heat accumulator 41 to absorb heat and obtain a high-temperature gaseous working fluid or a gas-liquid two-phase working fluid. The high-temperature gaseous working fluid or the gas-liquid two-phase working fluid enters the high-temperature sensible heat accumulator 42 and exchanges heat with the high-temperature sensible heat storage medium to obtain a high-temperature superheated working fluid. The high-temperature superheated working fluid enters the compression / expansion device 30 to do work and obtain a low-temperature superheated working fluid. The low-temperature superheated working fluid enters the low-temperature sensible heat accumulator 22 to exchange heat with the low-temperature sensible heat storage medium and is cooled into a nearly saturated low-temperature gaseous working fluid. The low-temperature gaseous working fluid enters the low-temperature latent heat accumulator 21 to release heat and completely liquefy to obtain a low-temperature saturated liquid working fluid. The low-temperature saturated liquid working fluid enters the low-temperature storage tank 10 for storage. The energy release process is completed.

[0061] Heat extraction process: During the energy storage and release process, 20℃~30℃ water is used to cool the low-temperature storage tank 10, high-temperature storage tank 50 and low-temperature latent heat accumulator 21 through the heat extraction module, thereby increasing the temperature difference of subsequent working fluid heat exchange and obtaining usable steam while maintaining the system thermal balance.

[0062] In detail, the low-temperature sensible heat accumulator 22 includes a low-temperature heat exchanger 221 and a low-temperature sensible heat medium storage tank; wherein, the low-temperature heat exchanger 221 has a low-temperature side and a high-temperature side, and the low-temperature side is relatively close to the low-temperature latent heat accumulator 21, and the high-temperature side is relatively close to the compression / expansion device 30, so as to meet the counter-current heat exchange requirements; at least two low-temperature sensible heat medium storage tanks are provided and are divided into a first low-temperature medium storage tank 222 and a second low-temperature medium storage tank 223. The first low-temperature medium storage tank 222 is connected to the high-temperature side of the low-temperature heat exchanger 221, and the second low-temperature medium storage tank 223 is connected to the low-temperature side of the low-temperature heat exchanger 221.

[0063] With this configuration, during the energy storage phase, when the low-temperature gaseous or gas-liquid two-phase working fluid discharged from the low-temperature latent heat accumulator 21 flows through the low-temperature heat exchanger 221, the sensible heat storage medium flows from the first low-temperature medium storage tank 222 to the second low-temperature medium storage tank 223, and the low-temperature gaseous or gas-liquid two-phase working fluid absorbs heat and becomes a low-temperature superheated working fluid. During the energy release phase, when the low-temperature superheated working fluid returned from the compression / expansion device 30 flows through the low-temperature heat exchanger 221, the low-temperature sensible heat storage medium flows from the second low-temperature medium storage tank 223 to the first low-temperature medium storage tank 222, and the low-temperature superheated working fluid releases heat to become a nearly saturated low-temperature gaseous working fluid.

[0064] Furthermore, the high-temperature sensible heat accumulator 42 includes a high-temperature heat exchanger 421 and a high-temperature sensible heat medium storage tank; wherein, the high-temperature heat exchanger 421 has a low-temperature side and a high-temperature side, and the low-temperature side is relatively close to the high-temperature latent heat accumulator 41, and the high-temperature side is relatively close to the compression / expansion device 30, so as to meet the counter-current heat exchange requirements; at least two high-temperature sensible heat medium storage tanks are provided and are divided into a first high-temperature medium storage tank 422 and a second high-temperature medium storage tank 423. The first high-temperature medium storage tank 422 is connected to the high-temperature side of the high-temperature heat exchanger 421, and the second high-temperature medium storage tank 423 is connected to the low-temperature side of the high-temperature heat exchanger 421.

[0065] With this configuration, during the energy storage phase, when the high-temperature superheated working fluid discharged from the compression / expansion device 30 flows through the high-temperature heat exchanger 421, the high-temperature sensible heat storage medium flows from the second high-temperature medium storage tank 423 to the first high-temperature medium storage tank 422, and the high-temperature superheated working fluid releases heat to become a nearly saturated high-temperature gaseous working fluid. During the energy release phase, when the high-temperature gaseous working fluid or gas-liquid two-phase working fluid discharged from the high-temperature latent heat accumulator 41 flows through the high-temperature heat exchanger 421, the low-temperature sensible heat storage medium flows from the first high-temperature medium storage tank 422 to the second high-temperature medium storage tank 423, and the high-temperature gaseous working fluid or gas-liquid two-phase working fluid absorbs heat to become a high-temperature superheated working fluid.

[0066] It is understandable that the specific types of low-temperature sensible heat storage media and high-temperature sensible heat storage media can be configured according to actual needs, such as the characteristics of the working fluid, including but not limited to pressurized water, heat transfer oil, molten salt, etc.

[0067] As a specific example of the above operating conditions, ethylene glycol is used as the working fluid with a flow rate of 900–1000 kg / h; the high-temperature latent heat storage medium is sodium nitrate, the low-temperature latent heat storage medium is erythritol, the high-temperature sensible heat medium is molten salt (60% NaNO3 + 40% KNO3), and the low-temperature sensible heat medium is heat transfer oil Therminol VP-1; the pressure of the high-temperature storage tank 50 is 1 MPa–2 MPa, and the temperature is 290°C–330°C; the pressure of the low-temperature storage tank 10 is 0.005 MPa–0.05 MPa, and the temperature is 120°C–140°C; the compression / expansion device 30 uses a reversible screw compressor, with a screw compressor discharge temperature of 350°C–400°C during energy storage and 140°C–170°C during energy release.

[0068] The specific workflow is as follows: Energy storage process: Low-temperature saturated liquid ethylene glycol is discharged from low-temperature storage tank 10. The ethylene glycol in low-temperature storage tank 10 is in a saturated liquid state, and the pressure and temperature remain stable during the discharge process. The saturated ethylene glycol enters the low-temperature latent heat storage device 21 to absorb heat, entering a low-temperature gas phase state or a gas-liquid two-phase state. The low-temperature latent heat storage medium undergoes a liquid-solid phase change, and the temperature remains stable. After entering the low-temperature gas phase or gas-liquid two-phase ethylene glycol, it exchanges heat with the low-temperature sensible heat storage medium in the low-temperature heat exchanger 221, resulting in a low-temperature superheated gas with a temperature of 150℃~200℃. The low-temperature sensible heat storage medium flows from the first low-temperature medium storage tank 222 to the second low-temperature medium storage tank 223. Ethylene glycol enters a reversible screw compressor, which consumes electrical energy to compress the glycol, resulting in high-temperature superheated gaseous ethylene glycol. This superheated gaseous ethylene glycol then enters a high-temperature heat exchanger 421 and exchanges heat with a high-temperature sensible heat storage medium, yielding high-temperature gaseous ethylene glycol. This high-temperature sensible heat storage medium flows from the second high-temperature medium storage tank 423 to the first high-temperature medium storage tank 422, releasing heat and becoming approximately a saturated gaseous phase. The high-temperature saturated gaseous ethylene glycol then enters a high-temperature latent heat accumulator 41, releasing heat to obtain high-temperature saturated liquid ethylene glycol. The high-temperature latent heat storage medium undergoes a solid-liquid phase transition, and the high-temperature saturated liquid glycol enters a high-temperature storage tank 50, where the pressure and temperature remain stable. This achieves electrothermal conversion and completes the energy storage process.

[0069] Energy release process: High-temperature saturated liquid ethylene glycol is discharged from high-temperature storage tank 50. During the discharge process, the pressure and temperature remain stable. The high-temperature saturated liquid ethylene glycol enters high-temperature latent heat accumulator 41 to absorb heat, resulting in high-temperature gaseous or gas-liquid two-phase ethylene glycol. The high-temperature latent heat storage medium undergoes a liquid-solid phase change, and the temperature remains stable. After entering high-temperature heat exchanger 421, the high-temperature gaseous or gas-liquid two-phase ethylene glycol exchanges heat with the high-temperature sensible heat storage medium, resulting in a high-temperature superheated gas with a temperature of 300℃~350℃. The high-temperature sensible heat storage medium flows from the first high-temperature medium storage tank 422 to the second high-temperature medium storage tank 423. The high-temperature superheated gaseous ethylene glycol enters the reversible screw compressor. The reversible screw compressor outputs mechanical work to generate electricity while simultaneously producing low-temperature superheated gaseous ethylene glycol. This superheated gaseous ethylene glycol enters a low-temperature heat exchanger 221 and exchanges heat with a low-temperature sensible heat storage medium, yielding low-temperature gaseous ethylene glycol. The low-temperature sensible heat storage medium flows from a second low-temperature medium storage tank 223 to a first low-temperature medium storage tank 222, releasing heat and becoming approximately a saturated gas phase. The low-temperature gaseous ethylene glycol enters a low-temperature latent heat storage tank 21, releasing heat to obtain low-temperature saturated liquid ethylene glycol. The low-temperature latent heat storage medium undergoes a solid-liquid phase transition, maintaining a stable temperature. The low-temperature saturated liquid ethylene glycol enters a low-temperature storage tank 10, where the pressure and temperature remain stable. This process achieves thermoelectric conversion and completes the energy release process.

[0070] Heat extraction process: During the energy storage and release process, 20℃~30℃ water is used to cool the low-temperature storage tank 10, high-temperature storage tank 50 and low-temperature latent heat accumulator 21 through the heat extraction module, thereby increasing the temperature difference of subsequent working fluid heat exchange and obtaining usable steam while maintaining the system thermal balance.

[0071] The following describes the operation method of the combined power and steam energy storage and thermal energy storage system provided by the present invention. The operation method of the combined power and steam energy storage and thermal energy storage system described below can be referred to in correspondence with the combined power and steam energy storage and thermal energy storage system described above.

[0072] An operation method for an electric power-steam combined heat and energy storage system includes the following steps: During the energy storage process, the low-temperature saturated liquid working fluid is discharged from the low-temperature storage tank 10 and enters the low-temperature heat storage module 20 to absorb heat, thus obtaining a low-temperature gas-liquid two-phase working fluid or a low-temperature superheated working fluid. The low-temperature gas-liquid two-phase working fluid or the low-temperature superheated working fluid enters the compression / expansion device 30 for compression, thus obtaining a high-temperature gas-liquid two-phase working fluid or a high-temperature superheated working fluid. The high-temperature gas-liquid two-phase working fluid or the high-temperature superheated working fluid enters the high-temperature heat storage module 40 to release heat and completely liquefy, thus obtaining a high-temperature saturated liquid working fluid. The high-temperature saturated liquid working fluid enters the high-temperature storage tank 50 for storage.

[0073] During the energy release process, the high-temperature saturated liquid working fluid is discharged from the high-temperature storage tank 50 and enters the high-temperature heat storage module 40 to absorb heat, resulting in a high-temperature gas-liquid two-phase working fluid or a high-temperature superheated working fluid. The high-temperature gas-liquid two-phase working fluid or the high-temperature superheated working fluid enters the compression / expansion device 30 to expand and generate electricity, resulting in a low-temperature gas-liquid two-phase working fluid or a low-temperature superheated working fluid. The low-temperature gas-liquid two-phase working fluid or the low-temperature superheated working fluid enters the low-temperature heat storage module 20 to release heat and completely liquefy, resulting in a low-temperature saturated liquid working fluid. The low-temperature saturated liquid working fluid enters the low-temperature storage tank 10 for storage.

[0074] Heat extraction process: During the energy storage and release process, 20℃~30℃ water is used to cool the low temperature storage tank 10, high temperature storage tank 50 and low temperature heat storage module 20 through the heat extraction module, increasing the temperature difference of subsequent working fluid heat exchange, maintaining the system thermal balance while obtaining usable steam. The electric-steam combined heat and power storage system and its operation method provided by the embodiments of the present invention reduce thermal components such as throttling mechanisms and valve devices, simplifying the structure and reducing construction costs. By introducing a low-temperature storage tank 10 and a high-temperature storage tank 50 to store the liquid working fluid, the internal circulation is broken, reducing the thermal process, reducing heat loss, and improving system efficiency. In addition, the working fluid is stored in liquid form, which reduces the requirements for the working volume and pressure of the storage tanks. Compared with systems that store pressure potential energy such as carbon dioxide, the working fluid stored in liquid form not only has a high energy density, but also effectively avoids the system's sliding pressure operation, ensuring high-efficiency operation.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A combined electricity-steam power generation and energy storage system, characterized in that, The application relates to a heat storage type heat pump system. The system comprises a low-temperature storage tank (10), a low-temperature heat storage module (20), a compression / expansion device (30), a high-temperature heat storage module (40) and a high-temperature storage tank (50) connected in sequence along the flow direction of the working medium. The low-temperature storage tank (10) is used for storing low-temperature saturated liquid working medium. The low-temperature heat storage module (20) is used for heating the working medium flowing from the low-temperature storage tank (10) to the compression / expansion device (30) into gas-liquid two-phase or gas phase, or cooling the working medium returned from the compression / expansion device (30) to the low-temperature storage tank (10) into low-temperature saturated liquid. The high-temperature heat storage module (40) is used for cooling the working medium flowing from the compression / expansion device (30) to the high-temperature storage tank (50) into high-temperature saturated liquid, or heating the working medium flowing from the high-temperature storage tank (50) to the compression / expansion device (30) into gas-liquid two-phase or gas phase. The high-temperature storage tank (50) is used for storing high-temperature saturated liquid working medium.

2. The electrical and steam co-generative electrical and thermal storage system of claim 1, wherein, The low-temperature heat storage module (20) comprises a low-temperature latent heat accumulator (21) provided with low-temperature latent heat storage medium and used for heat exchange of the working medium in a low-temperature latent heat stage. The low-temperature heat storage module (20) further comprises a low-temperature sensible heat accumulator (22) connected between the low-temperature latent heat accumulator (21) and the compression / expansion device (30), wherein the low-temperature sensible heat accumulator (22) is provided with low-temperature sensible heat storage medium and used for heat exchange of the working medium in a low-temperature sensible heat stage.

3. The electrical and steam co-generative electrical and thermal storage system of claim 2, wherein, The low-temperature sensible heat accumulator (22) comprises a low-temperature heat exchanger (221) having a low-temperature side and a high-temperature side, a first low-temperature medium storage tank (222) arranged on the high-temperature side of the low-temperature heat exchanger (221) and a second low-temperature medium storage tank (223) arranged on the low-temperature side of the low-temperature heat exchanger (221). The high-temperature heat storage module (40) comprises a high-temperature latent heat accumulator (41) provided with high-temperature latent heat storage medium and used for heat exchange of the working medium in a high-temperature latent heat stage.

4. The electrical and steam co-generative electrical and thermal storage system of claim 3, wherein, The high-temperature heat storage module (40) further comprises a high-temperature sensible heat accumulator (42) connected between the compression / expansion device (30) and the high-temperature latent heat accumulator (41), wherein the high-temperature sensible heat accumulator (42) is provided with high-temperature sensible heat storage medium and used for heat exchange of the working medium in a high-temperature sensible heat stage. The high-temperature sensible heat accumulator (42) comprises a high-temperature heat exchanger (421) having a low-temperature side and a high-temperature side, a first high-temperature medium storage tank (422) arranged on the high-temperature side of the high-temperature heat exchanger (421) and a second high-temperature medium storage tank (423) arranged on the low-temperature side of the high-temperature heat exchanger (421). The low-temperature latent heat storage medium and the high-temperature latent heat storage medium are configured as solid-liquid phase change substances; and / or 5. The electrical and steam co-generative electrical and thermal storage system of claim 3, wherein, The low-temperature sensible heat storage medium and the high-temperature sensible heat storage medium comprise pressurized water, heat-conducting oil or molten salt; and / or The working medium comprises water, ethylene glycol, methanol or ethanol; and / or 6. The electrical and steam co-generative electrical and thermal storage system of claim 5, wherein, The high-temperature latent heat storage medium is nitrate or chloride; and / or The low-temperature latent heat storage medium is organic phase change energy storage substance.

7. The electrical and steam co-generative electrical and thermal storage system of claim 6, wherein, ​ ​ ​ 8. The electrical and steam co-generative electrical and thermal storage system of claim 6, wherein, ​ ​ ​ ​ ​ 9. The electrical and steam co-generating electrical and thermal storage system of any one of claims 1 to 8, wherein, The heat extraction module comprises: a heat exchange device integrated in the low-temperature heat storage module (20), the heat exchange device being connected with a heat extraction pipe (61) for extracting the residual heat of the low-temperature heat storage module (20) after operation; and / or a low-temperature heat extraction heat exchanger (62) connected with the low-temperature storage tank (10) for cooling the working medium in the low-temperature storage tank (10); and / or a high-temperature heat extraction heat exchanger (63) connected with the high-temperature storage tank (50) for cooling the working medium in the high-temperature storage tank (50).

10. A method for operating a combined heat and power storage system, characterized in that, The power-steam combined supply energy storage and heat storage system comprises: an energy storage process, in which the low-temperature saturated liquid working medium is discharged from the low-temperature storage tank (10) and enters the low-temperature heat storage module (20) to absorb heat, so as to obtain low-temperature gas-liquid two-phase working medium or low-temperature superheated working medium; the low-temperature gas-liquid two-phase working medium or low-temperature superheated working medium enters the compression / expansion device (30) to be compressed, so as to obtain high-temperature gas-liquid two-phase working medium or high-temperature superheated working medium; the high-temperature gas-liquid two-phase working medium or high-temperature superheated working medium enters the high-temperature heat storage module (40) to release heat and be completely liquefied, so as to obtain high-temperature saturated liquid working medium; and the high-temperature saturated liquid working medium enters the high-temperature storage tank (50) for storage; an energy release process, in which the high-temperature saturated liquid working medium is discharged from the high-temperature storage tank (50) and enters the high-temperature heat storage module (40) to absorb heat, so as to obtain high-temperature gas-liquid two-phase working medium or high-temperature superheated working medium; the high-temperature gas-liquid two-phase working medium or high-temperature superheated working medium enters the compression / expansion device (30) to be expanded to generate power, so as to obtain low-temperature gas-liquid two-phase working medium or low-temperature superheated working medium; the low-temperature gas-liquid two-phase working medium or low-temperature superheated working medium enters the low-temperature heat storage module (20) to release heat and be completely liquefied, so as to obtain low-temperature saturated liquid working medium; and the low-temperature saturated liquid working medium enters the low-temperature storage tank (10) for storage; a heat extraction process, in which the heat extraction module extracts heat during the energy storage and energy release processes, so as to generate heat supply steam; the temperature of the high-temperature storage tank (50) and the low-temperature storage tank (10) is reduced, and the subsequent working medium heat exchange temperature difference is increased; the excess heat of the low-temperature heat storage module (20) is extracted, so as to maintain the system heat balance.

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