Single-tank multi-layer water body cross-seasonal multifunctional heat storage system and operation control method

Abstract

The invention relates to a single-tank multi-layer water body cross-seasonal multifunctional heat storage system and an operation control method, multiple layers of partition plates are arranged in a storage tank, and layered heat storage is achieved through the pressure difference of water bodies. The water pressure increases with depth, the saturation temperature increases correspondingly, and the heat storage amount increases by more than 80%. According to the scheme, the storage tank comprises a storage tank body, a layering partition plate, a one-way pressure release valve, a water replenishing valve and circulating heating equipment. The pressure, the temperature and the water quantity are dynamically balanced among the layers through one-way doors; layer-by-layer heating is achieved through an electric boiler or a steam heat exchanger, and heat energy conduction is achieved through steam phase change heat transfer; and 175 DEG C high-temperature water, 150 DEG C micro-pressure steam or 95 DEG C heating hot water can be output, and the multifunctional requirements for short-time heat storage peak regulation, long-time heat storage, ORC power generation, cross-season heat storage and the like are met. The problem that the water heat storage efficiency is reduced due to the fact that the altitude high boiling point is reduced is solved, the high-temperature water leakage risk is eliminated, and the method is suitable for urban zero-carbon heat supply, power plant peak regulation and Saggojiang new energy base matching local consumption wind power photovoltaic abandoned electricity.

Description

Technical Field

[0001] The present application relates to the field of water heat storage technology, and in particular to a single-tank, multi-layer water body, cross-seasonal multifunctional heat storage system and an operation control method. Background Art

[0002] Water heat storage technology uses water as the heat storage medium and stores and releases heat energy by heating or cooling water. It has the advantages of low technical threshold, controllable cost and high thermal efficiency. It is currently one of the most mature and widely used heat storage methods.

[0003] Water-based thermal storage technology, with its advantages of high safety, environmental compatibility, and scalable application, has become the preferred choice for large-scale thermal storage. In particular, by combining the inexhaustible supply of water in nature with the inexhaustible resources of wind and photovoltaic power through cross-seasonal energy storage, it has resolved many challenges in the development of renewable energy and become a mainstream option for energy transition. Currently, large-scale water-based thermal storage tanks all utilize thermocline technology to solve the exchange of hot and cold water. Therefore, the thermocline layer in the thermal storage tank is key to ensuring thermal storage performance.

[0004] A thermocline thermal storage tank is a device that uses the density difference between hot and cold fluids to form a thermocline layer to store and release thermal energy. Due to its mature technology, simple structure, and low cost, it is widely used. However, thermocline thermal storage tank technology has certain limitations. For example, during operation, factors such as fluid flow rate, temperature fluctuations, tank structure and size, and filling materials can easily cause the thermocline layer to diffuse, migrate, or deform, leading to increased mixing between high-temperature and low-temperature fluids and reduced thermal storage efficiency. The main shortcomings are as follows: 1. The stability of the thermocline layer is difficult to control, requiring precise control and optimization technology to maintain the stability of the thermocline layer. Improper control, excessive water inflow rate, or poor water distributor design can lead to increased or destroyed thermocline layer thickness, affecting thermal storage stability. 2. With multiple cycles of heat storage and release, the thermocline layer will continue to expand, and its thickness may increase from the initial 0.3 m to 0.5 m or even 1 m or more, resulting in a decrease in the available heat storage capacity; 3. Tank thermal stress cycle fatigue: Frequent charging and discharging causes the tank body (especially large-diameter thin-walled tanks) to experience cyclical thermal expansion and contraction, which can cause fatigue cracks in stress concentration areas such as welds and openings, leading to tank damage and medium leakage, posing a danger. 4. Applications at high altitudes are limited. Based on the physical properties of water, its boiling point is 100°C at standard atmospheric pressure (101.325 kPa). As altitude increases, atmospheric pressure decreases (the pressure drops by approximately 3 kPa for every 300 meters of altitude increase), and the boiling point of water decreases accordingly (see comparison table). This lower boiling point at high altitudes reduces the energy density of thermal water storage, impacting thermal storage efficiency. Therefore, it is urgent to develop technologies that can increase the thermal storage temperature of water suitable for high-altitude locations.

[0005] Comparison table of the relationship between altitude and water boiling point Summary of the Invention

[0006] To address the aforementioned issues with the existing technology, the present invention provides a multi-season, multifunctional, single-tank, multi-layer water heat storage system. Building on the traditional single-tank structure, the heat storage tank is divided into several layers from top to bottom. Flexible or rigid, high-temperature-resistant, thermally insulating composite materials are used to isolate the water between the layers, creating several water bodies with varying pressures. When the tank height exceeds 20 meters, the water pressure at the bottom layer is 0.2 MPa, allowing it to be heated to a saturated evaporation temperature of 120.23°C, corresponding to the pressure of that layer. This increases the water's heat storage density. When the tank height reaches 50 meters, it can capture twice the available heat of a normal-pressure water tank, achieving a higher heat storage capacity at a lower cost. This leverages the low-cost advantage of water heat storage and addresses the problem of lower heat storage temperatures at high altitudes due to the lower boiling point of water.

[0007] To achieve the above object, the present invention adopts the following technical solutions: A single-tank, multi-layer water-body, cross-seasonal, multifunctional heat storage system comprises: a storage tank body, a storage tank foundation, a thermal insulation layer, a storage tank roof, a partition, a one-way pressure relief valve, a one-way water supply valve, a tank roof exhaust valve, an inspection manhole, an inspection shaft, a water inlet, a water outlet, heating equipment, and a circulating water pump.

[0008] The tank body (referred to as the tank body) is constructed of a steel frame with steel plate enclosures and an interior coating of thermal insulation and anti-corrosion paint. Horizontal frames are installed within the tank body, spaced vertically at intervals of 5 or 10 meters from top to bottom. The tank is located above ground, underground, semi-underground, or underwater. The underground portion is lined with reinforced concrete, steel plates, and thermal insulation and anti-corrosion paint. Because the high-temperature water stored in the water body is located in the lower portion of the tank body, the safety risk of high-temperature water leakage caused by disasters such as earthquakes and accidents is eliminated for underground or semi-underground tanks.

[0009] The tank foundation (hereinafter referred to as foundation) is made of reinforced concrete, and its compressive strength should be adapted to the water pressure at the height of the tank.

[0010] The thermal insulation layer is made of thermal insulation materials. The ground storage tank is covered on the periphery of the tank steel plate with thermal insulation materials such as polyurethane and is protected by metal materials on the outside. The underground storage tank is arranged with a thick layer of low-cost and low-thermal conductivity solid waste materials (waste residue) on the periphery of reinforced concrete to reduce heat loss and reduce costs.

[0011] The tank roof (abbreviated as tank roof) is composed of steel + steel plate ( Figure 7 ), an inspection manhole 11 and a pressure relief valve 8 (including negative pressure) device are installed on it.

[0012] The baffles are made of flexible or rigid high-temperature resistant and insulating composite materials. Their function is to stratify water and transmit pressure. Installed on a horizontal frame within the tank, the baffles separate the water in the heat storage tank from top to bottom into several layers, creating water bodies of varying pressure between the layers. The pressure of the upper water layer is transmitted to the lower water layer through the baffles. Rigid baffles are provided with connecting holes to transmit pressure. The water pressure at the bottom of the lowest water layer is the pressure of the water at the total height of the tank. Taking a 50-meter tank as an example, with baffles set at 10-meter height, the bottom pressure of each layer and the corresponding saturated water temperature distribution are as follows: Distribution table of bottom water pressure and saturated water temperature of each layer:

[0013] As shown in the table above, the partitions divide the water in the storage tank into several independent water bodies with different pressures. For example, a 50-meter-tall tank is divided into five layers. The second layer, counting from the tank top, is more than 20 meters above the water surface. The water in this layer can be heated to 120.23°C, corresponding to a water pressure of 0.2 MPa. This exceeds the saturated evaporation temperature of 100°C in conventional storage tanks, thereby increasing the tank's heat storage density. When the tank height exceeds 50 meters, the heat storage capacity can be more than double that of a conventional tank.

[0014] Thermodynamic properties of saturated water and saturated water vapor

[0015]

[0016] As water pressure increases, the temperature of its saturated water and saturated water vapor rises, but the rate of increase gradually decreases, and the temperature difference tends to decrease. The temperature difference varies significantly between 0.1 and 0.4 MPa, but becomes more gradual after 0.7 MPa. Therefore, considering the ratio of increasing tank height to increasing storage capacity and the amount of engineering work required, a tank height of 50 meters is more appropriate.

[0017] The one-way pressure relief valve 6 and the one-way water supply valve 7 are installed on the partition ( Figure 4), the function of the one-way pressure relief valve is to vaporize when the temperature of the water in this layer exceeds the saturation temperature of this layer. The steam gathers at the top of this layer and generates a certain pressure. When the pressure is higher than the water pressure at the top, the one-way pressure relief valve opens and discharges the steam to the upper water body to relieve the pressure. When the water in the storage tank is circulated and heated, the volume of the lower water body increases accordingly and the pressure increases accordingly. When it exceeds the water pressure of this layer, the one-way pressure relief valve opens, and the water flows upward layer by layer to achieve water balance in the storage tank. The function of the one-way water replenishment valve is to open when the water volume of the lower layer is reduced due to extraction or evaporation, resulting in a decrease in pressure. Water is replenished from the upper layer to the lower layer to balance the pressure.

[0018] Preferably, the structure of the one-way pressure relief valve and the one-way water supply valve should meet the requirements of safe and stable operation of underground storage tanks, have simple structure, reliable operation and no need for maintenance. Figure 8 , including: valve body 6, 7, valve plate 13, hinge 14.

[0019] The valve body is constructed from a stainless steel tube. The one-way pressure relief valve consists of a DN50 stainless steel nipple extending through a baffle. A stainless steel valve plate 13 and hinge 14 are mounted at one end of the upper water layer. When the pressure in the lower layer exceeds a set value, valve plate 13 opens to release pressure. The one-way water replenishment valve is constructed from a DN50 stainless steel U-shaped tube. The long end extends through the baffle, and the short end is mounted with a stainless steel valve plate 13 and hinge 14. When the pressure in the lower layer decreases due to water withdrawal or evaporation, the one-way water replenishment valve opens, replenishing water from the upper layer to the lower layer to balance the pressure.

[0020] The valve plate is made of stainless steel, and the thickness of the valve plate is determined according to the opening pressure set for the layer.

[0021] The hinge is made of stainless steel, and a valve plate opening limit device is provided to ensure that the valve plate is reset in time.

[0022] Preferably, the one-way pressure relief valve is provided with an emergency pressure relief valve with a fixed valve plate, and the valve plate is composed of a thin plate. When the one-way pressure relief valve fails and the pressure difference between two adjacent layers of water is greater than the set value, the valve plate bursts to relieve pressure, thereby ensuring the safety of the tank structure.

[0023] The water inlet and water outlet are pipe interfaces installed on each layer of the tank body, and their function is to inject or output water to the water body of this layer when the storage tank is in operation.

[0024] The inspection manhole is a circular hole installed on the tank top (underground storage tank) and the tank wall (ground storage tank), which is closed with a blind plate for construction and maintenance personnel to enter and exit the tank for installation and maintenance work.

[0025] The maintenance shaft 12 is set for underground storage tanks ( Figure 7A circular steel drum installed at the horizontal center of the underground storage tank runs through each water level. Maintenance manholes are installed on the drum wall at the corresponding height of each water level to allow construction and maintenance personnel to enter and exit the tank levels for installation and maintenance work. The water inlet, outlet, inlet and outlet, and circulating water pipes, as well as sensors, are installed in the maintenance shaft.

[0026] The heating equipment includes an electric heater and an electric boiler. Since the heat source of the cross-seasonal heat storage system of the present invention is mainly the abandoned power of wind power and photovoltaic power and the off-peak power of the power grid, conventional electric heating equipment is used.

[0027] The circulating water pump is an electric centrifugal water pump that provides pressure to each layer of water during the heating process of the single-tank multi-layer water body inter-seasonal heat storage system and provides power during circulating heating.

[0028] The single-tank, multi-layer water body, cross-seasonal multifunctional heat storage system includes two operating conditions: heat storage condition and heat release condition, and also includes three operating time scales: short-term heat storage, long-term heat storage and cross-seasonal heat storage.

[0029] The heat storage mode involves storing waste wind and photovoltaic power, or off-peak electricity from the grid, in a tank using electric-to-heat conversion equipment. Alternatively, it involves storing excess heat generated during peak load regulation at a power plant. This includes heating with electric heaters, electric boilers, and steam.

[0030] The electric heater heating condition is to use the abandoned electricity of wind power and photovoltaic power to heat the water in the storage tank installed on the ground through the electric heater. When the storage tank is 50 meters high, the electric heater is installed on the fifth floor of the storage tank. The heating method is as follows: Initial operating conditions: Each layer of the tank is filled with low-temperature water, which is transferred downward layer by layer through a one-way water supply valve while maintaining pressure. The electric heater first heats the water in the fifth layer to 151°C, preventing it from vaporizing. Continued heating causes the water to exceed its saturation temperature and vaporize, producing steam. The steam rises and accumulates in the upper layer, where its pressure gradually increases due to volume expansion. When the pressure exceeds 0.4 MPa, the one-way pressure relief valve opens, releasing the steam to the bottom of the fourth layer. At this point, because the water temperature at the bottom of the fourth layer is lower than the evaporation temperature at the top of the fifth layer, the steam cools and transforms into water, transferring its heat energy to the fourth layer, completing the heat transfer and heating the fourth layer. This process continues in this manner, heating the fifth layer and phase change heat transfer between layers, heating each layer of the tank until the top layer reaches near saturation without vaporizing, completing the heating process for the entire tank. During the heating process, water bodies of different temperatures in each layer do not mix. When the heating is completed, the water temperature in each layer of the tank rises step by step from top to bottom (see the bottom pressure and saturated water temperature distribution table of each layer).

[0031] Reheating condition: When the water temperature of each layer drops due to heat loss during the operation of the storage tank, the electric heater is started to heat the water in the 5th layer to a temperature higher than the saturation temperature. The water temperature of each layer can be replenished and maintained through phase change heat conduction between the water and steam in each layer, and the temperature of the top layer of water is lower than the saturation temperature and no steam is generated.

[0032] The electric boiler heating mode utilizes the abandoned electricity from wind and photovoltaic power to heat the water in the underground storage tank through the electric boiler. Since underground (semi-underground) storage tanks are not convenient for installing and maintaining electric heating equipment, a pressurized water pump and electric boiler installed on the ground are used to circulate and heat the water in the storage tank. The electric boiler heating mode includes two heating modes: large circulation and small circulation.

[0033] The large-scale circulation heating method described above: Initially, the tank is filled entirely with low-temperature water. For example, using the circulation heating of the fifth layer as an example, the circulating pump draws water from the top (first) layer's outlet. After being heated by the electric boiler, it becomes high-temperature, high-pressure water (above the evaporation temperature of 151.85°C) and is then injected through the water pipe into the fifth layer's water inlet. This high-temperature water mixes with the low-temperature water from the fifth layer. Because the circulating pump's pressure exceeds the water pressure in the fifth layer, the one-way pressure relief valve on the baffle opens, allowing the mixed water to pass through the one-way pressure relief valve into the fourth layer. Similarly, water from the third layer flows into the second layer and on to the top layer, achieving water balance between the circulating pump's inlet and outlet, while maintaining the top layer water level. When the water temperature in the fifth layer reaches the set point (145°C), heating is complete. The water pipe is then switched to the fourth layer's water inlet, and the electric boiler's heating temperature is adjusted to above 143.62°C to continue heating the fourth layer. This process is repeated until each layer of the tank reaches the set point.

[0034] Reheating Condition: When the water temperature in each layer drops during tank operation due to heat conduction between the lower layer and the adjacent upper layer and heat loss from the tank body, the electric boiler is activated to heat the water in the fifth layer to a temperature above the saturation temperature. The water temperature in each layer is replenished and maintained through steam phase change, with the top layer water temperature below the saturation temperature and no steam generated.

[0035] The small cycle heating method ( Figure 6 ): Initial working condition: The tank is filled with low-temperature water. Take the circulating heating of the fifth layer as an example: the water inlet side of the circulating pump draws water from the water outlet of the fifth layer, and after being heated by the electric boiler, it becomes high-temperature and high-pressure water (set temperature 145°C) and is injected into the water inlet of the fifth layer through the water pipeline. The water in the fifth layer is circulated and heated to 145°C. Similarly, the water in each layer can be heated to the set temperature layer by layer, and finally the heating of the entire storage tank is completed. Due to the circulating heating in each layer, the low-temperature water is taken from the bottom of the layer, and the heated high-temperature and high-pressure water is injected into the upper part of the layer. The temperature difference of the water body is small, the water capacity is small, and the heating speed to the set temperature is fast. (See the table of water depth, water pressure and evaporation temperature of each layer) Table of water depth, pressure and evaporation temperature of each layer

[0036] Optimally, multiple electric boilers can be used to heat three or more layers of water simultaneously, absorbing a large amount of excess wind and photovoltaic power within a limited timeframe. This shortens the heating time of the entire storage tank and increases the capacity and frequency of peak load regulation. Using ORC for power generation contributes to grid stability.

[0037] The steam heating method utilizes excess steam from a combined heat and power (CHP) coal-fired power plant during load regulation to heat water in storage tanks, either directly or through a heat exchanger. Large, multi-layered tanks (50 meters underground and 50 meters above ground, totaling 100 meters in height) heat the water at the bottom layer to 175°C, outputting high-temperature water or steam at an average temperature of 145°C. During periods of low power demand, boiler and turbine output must be reduced. The shortfall in heat is supplemented by high-temperature water or steam supplied from the storage tanks, replacing the boilers in delivering heat directly to the heating system. During peak power demand, boiler output must be increased, reducing steam supply from the turbines. High-temperature water or steam supplied directly to the heating system from the storage tanks replaces the boilers in delivering heat directly to the heating system. This enhances the plant's top-load capacity, helps achieve heat-to-electricity decoupling, and increases the flexibility of both the thermal power units and the power grid.

[0038] The steam heating method ( Figure 9 ): In the initial working condition, the tank is filled with low-temperature water. Take the example of steam circulating through a heat exchanger to heat the fifth layer: the water inlet side of the circulating pump takes water from the water outlet of the top layer (first layer), and after being heated by the heat exchanger, it becomes high-temperature and high-pressure water, which is injected into the water injection port of the fifth layer through the water supply pipe. After the high-temperature water is injected, it mixes with the low-temperature water of the fifth layer. Since the pressure of the circulating pump is greater than the water pressure of the fifth layer, the one-way pressure relief valve on the partition opens, and the mixed water enters the fourth layer through the one-way pressure relief valve. Similarly, the water from the third layer enters the second layer to the top layer, achieving water balance at the inlet and outlet of the circulating pump, and the water level at the top layer of the tank remains unchanged; when the water temperature of the fifth layer reaches the set value (145°C), the heating is completed; the water supply pipe is switched to the water injection port of the fourth layer to continue heating the fourth layer. Repeating the operation can heat each layer of the tank to the set temperature.

[0039] Optimally, multiple heat exchangers can be used to simultaneously heat three or more layers of water. This allows for the absorption of a large amount of heat energy from the unit's exhaust within a limited timeframe, achieving deep peak load regulation. This also shortens the heating time of the entire storage tank, increasing the capacity and frequency of peak load regulation. Using ORC for power generation contributes to grid stability.

[0040] The steam heating mode described above is suitable for intraday (short-term) peak-shaving operations in cogeneration power plants. Because the water temperature in each tank layer is stable and the base temperature is high (above 120°C), it can store and release large amounts of heat over short periods of time. Through regulation of the heat storage system, the unit's thermal and electrical decoupling is achieved, improving the heating peak-shaving capacity of the cogeneration unit. Because of the short-term intraday heat storage and release, the heating process is based on the top water temperature being below the saturation temperature, eliminating steam generation. Heat losses are negligible, and supplemental heating is unnecessary.

[0041] The heat release mode releases the heat stored in the multi-layer tanks in different forms at different times to achieve energy storage. This includes short-term energy storage, long-term energy storage, and cross-seasonal energy storage. Output methods include heating hot water, high-temperature and high-pressure water, and high-temperature and low-pressure steam.

[0042] Because this technology eliminates the need for mixed hot and cold water control and inlet flow rate restrictions associated with thermocline storage tanks, it can simultaneously access water at different temperatures and output low-pressure steam, adapting to diverse scenarios and needs, including short-term, long-term, and inter-seasonal energy storage. It also enables rapid heating and high-flow heat supply, and can simultaneously heat and supply heat.

[0043] The short-term heat storage is suitable for thermal decoupling of combined heat and power coal-fired power plants. When the unit is unloaded, the thermal energy of the steam is stored in the storage tank. When the power grid is highly loaded, high-temperature and high-pressure water or steam is released to increase the power generation of the unit, which helps to increase the flexibility of the thermal power unit and the peak-shaving capacity of the power grid.

[0044] The long-term heat storage is suitable for heating by using off-peak electricity storage. Heat is stored during off-peak electricity periods (8 hours) and heat is provided during flat and peak electricity periods (16 hours), which can achieve better economic benefits.

[0045] The long-term heat storage is suitable for occasions where micro-pressure steam is supplied discontinuously. The multi-layer storage tank can output micro-pressure steam above 120°C and is used in food processing, medical sterilization, cleaning and disinfection, material drying and other processes.

[0046] This long-term thermal storage is suitable for both daily and weekly energy storage scenarios. Because this technology can output stable, low-pressure steam at 120-140°C, generating electricity through the Rankine Cycle (ORC), it is particularly useful in photovoltaic sand control projects and the "Shagohuang" new energy base, where on-site wind and photovoltaic power generation capacity needs to be significantly increased to mitigate fluctuations. It can also be used for agricultural and animal product processing and drying.

[0047] The inter-seasonal heat storage includes urban zero-carbon heating and modern agricultural and animal husbandry heating.

[0048] The cross-seasonal urban zero-carbon heating includes two operating conditions: daily regulation and cross-seasonal operation. Daily regulation uses off-peak electricity as a heat source for long-term energy storage and heating. Heat is stored during off-peak periods (8 hours) and provided during peak and off-peak periods (16 hours). This approach offers better economic benefits than thermocline tanks. For example, a 50-meter-high underground tank (30 meters below ground and 20 meters above ground) with a 10-meter diameter and a single tank capacity of 3,925 cubic meters of water has a heat storage capacity of 104 kW / m³ per unit of water, resulting in a single tank capacity of 408,200 kW, a 70% increase in heat storage compared to a thermocline tank of the same volume. This can heat an urban area of ​​63,000 square meters.

[0049] This cross-seasonal, zero-carbon urban heating system utilizes curtailed wind and photovoltaic power, as well as zero-price or negative-price electricity from power plants and the grid, as heat sources. This system can achieve large-scale, zero-cost, zero-carbon heating. Storage tanks are charged during the off-season and heat is provided during the heating season.

[0050] The cross-seasonal heating system for modern agriculture and animal husbandry is used to heat multi-span greenhouses and plant factories, contributing to the development of modern agriculture and animal husbandry. With the development of photovoltaic sand control and the construction of the "Shagehuang" new energy base in western China, insufficient heat storage facilities have become a bottleneck restricting development. This technology can achieve cross-seasonal heat storage, storing abandoned wind and photovoltaic power on-site for application in heating multi-span greenhouses and plant factories, and promoting the development of modern agriculture and animal husbandry.

[0051] The output modes include hot water for heating, high-temperature, high-pressure water, and high-temperature, low-pressure steam. Because the storage tank simultaneously receives water at different temperatures, high-temperature, high-pressure water (150°C, 0.5 MPa), high-temperature, low-pressure steam (150°C, 0.15 MPa), and medium-temperature, normal-pressure hot water for heating (95°C, 0.1 MPa) can be obtained according to different needs.

[0052] The high-temperature and high-pressure water can be obtained by pumping out the high-temperature and high-pressure water at the bottom layer with a water pump and maintaining the pressure. The same is true for other layers, with the temperature and pressure decreasing.

[0053] The high-temperature, low-pressure steam is obtained by flash evaporation by using a water pump to lead out the high-temperature, high-pressure water in the fifth layer and release the pressure. The other layers are the same, and the temperature and pressure decrease.

[0054] When heating and water (heat) extraction are carried out synchronously and the heat is balanced, high-temperature and high-pressure hot water or high-temperature and low-pressure steam can be obtained continuously.

[0055] The medium-temperature, normal-pressure heating hot water is injected into the lowest layer, and medium-temperature, normal-pressure heating hot water can be continuously taken from the first layer. The water temperature gradually increases until each layer is replaced with normal-temperature water, which can be used for cross-seasonal zero-carbon heating in the city.

[0056] A single-tank, multi-layered, multi-seasonal heat storage system requires significant water volume, making chemical water treatment impractical. To prevent scaling in pipes and heat exchangers, physical methods are required for water anti-scaling and descaling. This involves physically intervening in the crystallization of calcium and magnesium ions in the water, altering the crystal structure and preventing their deposition on the heat exchanger surface. A backup heat exchanger is installed and regularly cleaned to maintain heat transfer efficiency. Mature technologies are available both domestically and internationally. When heat release conditions involve the power plant's water supply system, water provided by the power plant must be used.

[0057] The technical effects of the present invention are (1) Large-scale on-site consumption of abandoned electricity. This technology can be used to consume on-site large-scale abandoned electricity from wind power and photovoltaic power, as well as off-peak electricity and electricity with zero or negative electricity prices from power plants and power grids, and implement cross-seasonal heat storage and zero-carbon, clean heating.

[0058] (2) The heat storage system of the present invention has the characteristics of high heat storage efficiency, high thermal energy quality, and a wide applicable temperature range. It can provide high-temperature high-pressure water (175°C, 1 MPa), high-temperature micro-pressure steam (150°C, 0.15 MPa), and medium-temperature normal-pressure heating hot water (95°C, 0.1 MPa) according to different application needs. It also has multiple functions such as short-term energy storage, long-term energy storage, and cross-season energy storage.

[0059] (3) Since this technology can output stable saturated steam at 120-140℃, it can generate electricity through the Rankine cycle (ORC) technology and realize cross-seasonal heat storage power generation.

[0060] (4) The water pressure of the tank body is used to increase the heat storage temperature, and the heat storage density of the water body is increased. The heat storage density is more than doubled under the same conditions as that of the thermocline tank.

[0061] (5) Overcome the problem of reduced energy density due to the lower boiling point of water in high altitude areas and reduce the risk of boiling and vaporization of water in storage tanks.

[0062] (6) Eliminate safety hazards. When the storage tank is located underground or semi-underground, the safety hazards caused by high-temperature water leakage in the tank are greatly reduced, especially the safety hazards caused by high-temperature water leakage caused by disasters and accidents such as earthquakes.

[0063] (7) Comparison between single-tank multi-layer water thermal storage tank and thermoclimatic storage tank Under the same conditions, the comparison between multi-layer water body cross-seasonal storage tank and thermocline storage tank is as follows:

[0064] From the analysis of the above table, we can see that under the same conditions, a 50-meter-high multi-layer water seasonal storage tank can store more than 80% more thermal energy than a thermocline storage tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 This is a schematic diagram of the layered structure of the storage tank in this patent.

[0066] Figure 2 This is a schematic diagram of the stratification and temperature distribution of the underground storage tank in this patent.

[0067] Figure 3 This is a schematic diagram of the stratification and temperature distribution of the above-ground storage tank in this patent.

[0068] Figure 4 This is a partial layout diagram of the one-way pressure relief valve and one-way water supply valve of the storage tank of this patent.

[0069] Figure 5 This is a schematic diagram of the large-cycle heating of the thermal storage tank in this patent.

[0070] Figure 6 This is a schematic diagram of the small-cycle heating of the thermal storage tank in this patent.

[0071] Figure 7 Layout diagram of underground storage tank maintenance equipment for this patent Figure 8 This is a schematic diagram of the layout of the one-way pressure relief valve and one-way water supply valve of the storage tank in this patent Figure 9 Schematic diagram of the heating working condition of the storage tank in this patent The accompanying drawings are marked as follows: 1. heat storage tank; 2. foundation; 3. thermal insulation layer; 4. tank top; 5. partition; 6. One-way pressure relief valve; 7. One-way water supply valve; 8. Exhaust valve; 9. Water inlet; 10. Water outlet; 11. Maintenance manhole; 12. Maintenance shaft; 13. Valve plate; 14. Hinge; 15. Electric boiler; 16. Circulating booster pump; 17. Heat exchanger; DETAILED DESCRIPTION

[0072] The present invention will be further described with reference to the accompanying drawings and specific embodiments: Example 1: Application in urban heating applications: regional cross-seasonal heating and year-round hot water A single-tank, multi-layer water-body, cross-seasonal multifunctional heat storage system is applied to the field of cross-seasonal urban zero-carbon heating. It uses the abandoned power of wind power and photovoltaic power, as well as the zero-price and negative-price electricity of power plants and power grids as heat sources to achieve large-scale zero-cost heat source and zero-carbon heating. With the large-scale and rapid development of wind power and photovoltaic power, a large amount of "waste electricity" has been generated and needs to be consumed locally. Due to its high frequency, short duration and large amount of electricity, especially at noon in the non-heating season, some areas have experienced zero and negative electricity prices. However, the heat supply for urban heating during the heating season is seriously insufficient. The implementation of this patented single-tank, multi-layer water-body cross-seasonal heat storage system for urban area heating can alleviate this contradiction.

[0073] The specific embodiments of the present invention are described below with reference to the accompanying drawings.

[0074] A single-tank multi-layer water body cross-season multifunctional heat storage system Figure 1 、 Figure 2 、 Figure 5 、 Figure 7 As shown, the storage tank group is placed underground or semi-underground, and the heat source is the abandoned electricity of wind power and photovoltaic power, as well as the zero-price or negative-price electricity of power plants and power grids. The water in the storage tanks installed underground is heated by circulating pumps and electric boilers. The storage tanks are charged with heat during the non-heating period and heat is supplied during the heating period to achieve cross-seasonal regulation.

[0075] Example: The tank is 50 meters high and 20 meters in diameter, with a single tank capacity of 15,700 cubic meters. With a unit water storage capacity of 104 kW / m³, a single tank can store 1,632,800 kW of heat, providing enough heat for 28,400 square meters for four months.

[0076] The underground storage tank has five independent water layers, each 10 meters high. The heating temperatures of each layer are set at 145°C, 135°C, 125°C, 115°C, and 95°C from bottom to top. Considering the step-by-step changes in water pressure and temperature differences within each layer, the set values ​​need to be adjusted based on experimental and measured data. A circulating pressure pump 16 and an electric boiler 15 installed on the ground are used to circulate and heat the water in the storage tank. Heating method: In the initial working condition, the tank is filled with low-temperature water. Take the circulating heating of the fifth layer as an example: the water inlet side of the circulating pump takes water from the water outlet 10 of the top layer (first layer), and after being heated by the electric boiler 15, it becomes high-temperature and high-pressure water (higher than the evaporation temperature of 151.85℃ and the pressure of 0.5Mpa) and is injected into the water injection port 9 of the fifth layer through the water pipeline. After the high-temperature water is injected, it mixes with the low-temperature water in the fifth layer. Since the pressure of the circulating pressure pump is greater than the water pressure of the fifth layer, the one-way pressure relief valve on the partition opens, and the mixed water enters the fourth layer through the one-way pressure relief valve. Similarly, the water in the third layer enters the second layer to the top layer. The circulating pressure pump is used to achieve water volume balance between the inlet and outlet of the fifth layer and the first layer. The water level at the top layer of the storage tank remains unchanged, and the water temperature of each layer gradually increases. When the water temperature of the fifth layer reaches the set value (145°C), the heating of this layer is completed. The water supply pipeline is switched to the water injection port of the fourth layer, and the heating and pressure of the electric boiler are adjusted to 143.62°C, which is higher than the evaporation temperature, and the pressure is 0.4Mpa. The fourth layer continues to be heated to the set temperature of 140°C. Repeating the operation can heat each layer of the storage tank to the set temperature.

[0077] The optimized method consistently injects high-temperature, high-pressure water (above the evaporation temperature of 151.85°C and at a pressure of 0.5 MPa) heated by an electric boiler 15 into the water inlet 9 of the fifth layer through the water pipeline. When the water temperature in this layer reaches the evaporation temperature of 151.85°C, it vaporizes and produces steam, which enters the fourth layer through a one-way pressure relief valve. After cooling, it transforms into water, transferring heat to the fourth layer. This process continues until the first layer reaches 95°C, completing the entire tank heating process. This heating method simplifies operation compared to the previous method, but increases energy consumption of the circulating pressure pump.

[0078] Reheating method: When heat loss causes the water temperature in each layer to drop during tank operation, the electric boiler is activated to heat the water in the fifth layer to above the saturation temperature. Steam phase change in each layer replenishes and maintains the water temperature in each layer, ensuring that the top layer's water temperature falls below the saturation temperature and no steam is generated. The overall tank temperature is maintained at the set point until heating begins. Reheating continues during the heating period.

[0079] Heating method: Before the start of the heating period, the storage tank has completed water heat storage. In the initial heating condition, each layer reaches the set heating temperature, which is 145°C, 135°C, 125°C, 115°C, and 95°C from bottom to top. The circulating pressure pump 16 and heat exchanger 17 installed on the ground are used for circulating heat; the inlet of the circulating pressure pump is connected to the water outlet 10 of the fifth layer of water body, and the outlet is connected to the inlet of the primary side of the heat exchanger 17. The outlet of the primary side of the heat exchanger 17 is connected to the inlet 10 of the first layer of water body to form a complete tank water circulation heat exchange system. The water temperature at the outlet of the primary side of the heat exchanger 17 is controlled at about 35°C through flow regulation, and the heat energy is converted to the secondary heating pipe network for regional heating.

[0080] Preferably, during the period of circulating heat supply, abandoned wind and photovoltaic power can be used to heat the storage tank. In this case, an electric boiler is connected between the outlet of the primary side of the heat exchanger 17 and the inlet 10 of the first layer of water. The return water at the heat exchanger outlet, at 35°C, is reheated by the electric boiler and then fed into the storage tank. If the water temperature in the first layer falls below 60°C, it is transferred to the next layer, and so on.

[0081] Preferably, since there is always a water layer with a temperature higher than 60° C. in the storage tank, the heat exchange of the heat exchanger can provide hot water supply throughout the year.

[0082] Example 2: Application in thermal energy storage and peak regulation of coal-fired power plants A single-tank, multi-layer water-body, cross-seasonal multifunctional heat storage system is applied to thermal storage and energy peak regulation in coal-fired power plants. Its characteristic is that in the non-heating season, the abandoned power of wind power and photovoltaic power, as well as the zero-price and negative-price electricity of power plants and power grids are used as heat sources to absorb a large amount of "waste electricity" on-site to implement cross-seasonal heat storage. In the heating season, it is used for thermal storage and energy peak regulation in power plants. At the same time, low-pressure steam is output to meet the energy storage and peak regulation needs of power plants and auxiliary steam for non-power generation processes.

[0083] During the non-heating season, the tank operates in a large, multi-layered tank with a diameter of 20 meters and a total height of 100 meters. The tank is divided into 10 layers, each 10 meters high: five layers underground, each 50 meters high, and five layers above ground, each 50 meters high. Each layer holds 3,140 cubic meters of water, with a total tank capacity of 31,400 cubic meters. This system can heat the water at the bottom layer to 175°C. During the non-heating season, this system can stably provide steam or hot water below 180°C, covering auxiliary steam needs in the plant's non-power generation processes. It replaces the exhaust from the intermediate-pressure and low-pressure cylinders, which previously required desuperheating and pressure reduction. This increases unit power generation by over 5% while maintaining the same boiler evaporation rate, resulting in significant economic benefits. Based on a 50°C temperature difference, the usable heat storage per unit of water is estimated to be 58 kWh / m3, with a tank utilization rate of 0.6, for a total usable heat storage of 1,092.72 MW.

[0084] The ORC system can also be optimized to generate electricity using high-temperature, high-pressure water. The output high-temperature water reaches a maximum of 175°C, a minimum of 135°C, and an average of 155°C. The usable water volume spans seven layers, from the fourth to the tenth, totaling 21,980 cubic meters. The usable temperature difference is 70°C (155-85°C). The heat storage capacity per unit of water is 81 kilowatt-hours per cubic meter, and the total usable heat storage capacity in the tanks is 1,780.38 MW. Assuming a 12% thermoelectric efficiency, the ORC system generates 213.65 MWh of electricity.

[0085] Heating Season Tank Operation: A single-tank, multi-layered, cross-seasonal, multifunctional heat storage system is used for thermal energy storage and peak load regulation in coal-fired power plants. This system provides the plant with "two-way" peak load regulation capabilities during the heating season, increasing both its low-load operating capacity and its peak load capacity. This decoupling of heat and electricity increases the flexibility of the thermal power units and the grid, while also generating peak load benefits. During periods of low electricity demand, boiler and steam turbine output must be reduced. The shortfall in heat is then supplied directly to the heating system via high-temperature water or steam delivered from the storage tanks, replacing the boilers. During peak electricity demand, steam from the turbines must be reduced to increase boiler output, and high-temperature water or steam delivered directly to the heating system via the storage tanks, replacing the boilers. This enhances the plant's peak load capacity. Furthermore, because high-temperature water or steam is used as the heat source, thermal energy storage offers excellent thermal economics and low operating costs, resulting in optimal technical and economic advantages for peak load regulation.

[0086] Tank operation mode: A large multi-layer storage tank is used, with a diameter of 20 meters and a total height of 100 meters. It is divided into 10 layers, each layer is 10 meters high, with 5 layers underground and 50 meters high, and 5 layers above ground and 50 meters high. The single-layer water volume is 3140 cubic meters, the total capacity of the tank is 31,400 cubic meters, and the effective capacity is 28260 (0.9); it can heat the water in the bottom layer to 175℃, output high-temperature water or steam with an average temperature of 145℃, the return water temperature is 35℃, the available temperature difference is 110℃, the heat storage capacity per unit water body is 128Kwh / m3, and the total heat storage capacity of the tank is 3617.28MW.

[0087] In heating operation mode, when the power plant units enter the peak regulation state and reduce the amount of heating steam, the single-tank multi-layer water body inter-seasonal heat storage system is started to enter the heating operation mode, and the high-temperature water or steam with an average temperature of 145°C is output through the heat exchanger for regional heating or supplementary heating; when the heat source of the heating system suffers a serious failure and causes heating interruption, the single-tank multi-layer water body inter-seasonal heat storage system can be used as an emergency heat source, becoming the main guarantee measure for the continuity of urban heating.

[0088] The heating area according to the heat required for peak load regulation and emergency heating and the duration is as follows:

[0089] Example 3: Applied to the construction of energy storage thermal centers in large-scale wind power and photovoltaic power stations already built in deserts, Gobi, and wastelands, to locally consume surplus electricity during peak hours and achieve cross-seasonal heat storage and power generation.

[0090] Heat source: Surplus electricity from large-scale wind power and photovoltaic power stations Implementation scenario: Establish modern forage plant factories near existing large-scale wind power and photovoltaic power stations in deserts, Gobi, and wastelands to produce forage continuously year-round. During the heating season, low-cost heating will be provided by energy storage thermal centers. Combined with the development of photovoltaic sheep, this will form a virtuous cycle of "photovoltaic power generation + abandoned power heat storage + forage factory" and a green ecological chain of renewable energy + modern agriculture and animal husbandry.

[0091] Implementation steps: 1. Relying on large-scale wind power and photovoltaic power stations that have been built or are under construction, set up large-scale multi-layer water body inter-seasonal heat storage tank groups and build inter-seasonal energy storage thermal centers to meet the rigid demand for heat storage capacity of wind power and photovoltaic power stations, locally consume the abandoned electricity of wind power and photovoltaic power, and provide energy guarantee for the local development of modern agriculture and animal husbandry.

[0092] 2. Combine photovoltaic sand control and photovoltaic sheep with the construction of a year-round forage plant factory, develop animal husbandry and agricultural and animal husbandry product deep processing industries, and improve the agricultural and animal husbandry ecological environment. Heat will be provided by the energy storage thermal center during the heating season.

[0093] Combined with the development of modern agriculture, multi-span greenhouses are built to grow high value-added cash crops and provide high income for farmers. In conjunction with the development of agriculture and animal husbandry, a grass-livestock recycling industrial park for agricultural and animal husbandry products will be built to carry out deep processing of agricultural and animal husbandry products.

[0094] 3. Energy storage thermal center needs to provide (1) High temperature and high pressure water (150℃, 0.5Mpa), which can be used for agricultural product processing, drying and other processes; (2) High-temperature, low-pressure steam (150°C, 0.15 MPa) can be used for ORC power generation, achieving cross-seasonal heat storage power generation; (3) Medium-temperature heating hot water (95°C, 0.1Mpa) can be used for cross-season heating in agricultural and animal husbandry plant factories and multi-span greenhouses.

[0095] In this example, an underground storage tank is 50 meters tall and 20 meters in diameter. It has five independent water layers, each 10 meters high, and a single tank holds 15,700 cubic meters of water. The heating temperatures for each layer, from bottom to top, are set at 145°C, 135°C, 125°C, 115°C, and 95°C, respectively. The average heat storage capacity per unit water volume is 104 kW / m³, and the total heat storage capacity per tank is 1,632,800 kW. A ground-mounted circulating pressure pump and electric boiler are used to circulate the water in the tank.

[0096] The single-tank, multi-layer water-based interseasonal heat storage system is used to provide heat and steam for agricultural and animal husbandry plant factories. Heating lasts five months during the heating season (November to March), with 1.5 months each during the early and late cold seasons. The heating load is 100 watts / square meter, and 130 watts / square meter during the severe cold season, for an average heating load of 112 watts / square meter. Heat is stored during the three non-heating months (August, September, and October), operating for five hours per day and storing 3,628 kilowatts of heat per hour. Continuous heating begins during the heating season, providing 1,134 kilowatts per hour, capable of supplying up to 10,120 square meters of plant factories or multi-span greenhouses. During the non-heating months of April, May, June, and July, steam is exported for agricultural and animal husbandry product processing and drying, or for ORC power generation. Operation can also be interspersed with inter-seasonal heat storage.

Claims

1. A single-tank, multi-layer water body, cross-seasonal multifunctional heat storage system, characterized in that: include: Storage tank body, storage tank foundation, thermal insulation layer, storage tank roof, partition, one-way pressure relief valve, one-way water supply valve, tank top exhaust valve, inspection manhole, inspection shaft, water injection port, water outlet, heating equipment, circulating water pump; The tank body is a steel frame structure with steel plate enclosure, an internal horizontal frame and is divided into several layers from top to bottom. The layers are isolated by partitions. Underground tanks are equipped with reinforced concrete protective layer and thermal insulation layer outside the steel plate. The partition is made of flexible or rigid high-temperature resistant thermal insulation composite material to isolate water bodies, transmit pressure and prevent water mixing between layers; One-way pressure relief valve, installed on the baffle, opens when the water pressure in the lower layer exceeds the set value, releasing water and steam to the upper layer; One-way water supply valve, installed on the partition, opens when the pressure of the lower water body decreases, and water is supplied from top to bottom; Heating equipment is used to heat each layer of water, and conduct heat layer by layer through direct heating or steam phase change; Circulating water pump, used to provide water pressurization or circulation power; The underground storage tank is equipped with a maintenance shaft that runs through each floor and is equipped with water inlets, water outlets and maintenance manholes; The tank foundation, thermal insulation layer, tank top, and tank top exhaust valve are all necessary accessories of the tank.

2. The single-tank, multi-layer water body, cross-seasonal multifunctional heat storage system according to claim 1, characterized in that: The storage tank is placed on the ground, underground, semi-underground or underwater, with a tank height of 20-100 meters. The water body partitions in the tank are layered, and the height of each layer is 5-10 meters. Taking a five-layer 10-meter-high storage tank as an example, the bottom pressures of each layer of water are 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa, and 0.5MPa from top to bottom, and the corresponding saturation temperatures are 99.53°C, 120.23, 133.54°C, 143.62°C, and 151.85°C from top to bottom. When the storage tank is in operation, the control temperature settings of each layer are 95°C, 115°C, 125°C, 135°C, and 145°C from top to bottom. Since each layer of water is relatively closed, except for the top layer, it is not affected by the lowering of the boiling point at high altitude, thereby improving the heat storage capacity of the water.

3. The single-tank, multi-layer water body, cross-seasonal multifunctional heat storage system according to claim 1, characterized in that: The partition is made of flexible or rigid high-temperature resistant and heat-insulating composite materials. The rigid material is provided with connecting holes to transmit pressure, and the flexible material transmits pressure through deformation. The partition divides the water body of the storage tank into several independent water bodies with different pressures.

4. The single-tank, multi-layer water body, cross-seasonal multifunctional heat storage system according to claim 1, characterized in that: The heating equipment includes an electric heater, an electric boiler or a steam heat exchanger, and the heat source is wind power / photovoltaic power abandonment, off-peak electricity or power plant peak load waste heat.

5. The single-tank, multi-layer water body, cross-seasonal multifunctional heat storage system according to claim 1, characterized in that: A thermal insulation layer is laid around the tank body. Ground storage tanks use insulation materials such as polyurethane and aerogel, and underground storage tanks use a low thermal conductivity solid waste material insulation layer outside the reinforced concrete protective layer.

6. An operation control method for a single-tank, multi-layer water body, cross-seasonal multifunctional heat storage system, characterized in that: Includes the following steps and working conditions: Thermal storage working condition: The bottom water body is heated to above the saturation temperature by the heating equipment to generate steam. The pressure rises, causing the steam to enter the upper water body through the one-way pressure relief valve. When it encounters cold, the steam heats up the upper water body through phase change heat transfer. And so on, the heating rises layer by layer until the top layer reaches the set temperature, completing the heating process of the entire storage tank. The heating method is a large cycle and a small cycle; Heating condition: monitor the temperature of each layer, and when the temperature drops, restart the heating equipment to enter the heat storage condition for heating; Heat release working condition: high-temperature water is extracted from the bottom layer or flash evaporated to generate steam, which is then used to supply heat through a heat exchanger or generate electricity through ORC. Low-temperature return water or condensate is then added to the top layer. The water in each layer descends layer by layer through a one-way water supply valve until each layer of the tank is filled with low-temperature water, completing the heat output process of the entire tank.

7. The operation control method of a single-tank, multi-layer water body, cross-seasonal multifunctional heat storage system according to claim 6, characterized in that: The heat storage conditions include short-term heat storage for peak shaving, long-term heat storage and cross-seasonal heat storage; The short-term heat storage peak-shaving operating condition is suitable for intraday (short-term) peak-shaving operation of a cogeneration power plant, achieving thermal and electrical decoupling of the unit. When the unit is unloaded, the thermal energy of the excess steam is stored in the storage tank. When the grid is highly loaded, high-temperature and high-pressure water or steam is released to replace the unit's heat supply, reducing air extraction and increasing the unit's power generation, thereby enhancing the flexibility of the thermal power unit. The long-term heat storage and hot water output working condition is suitable for using off-peak electricity to store energy for heating. Heat is stored during off-peak electricity periods (8 hours) and hot water is output to the system for heating during normal and peak electricity periods (16 hours). The long-term heat storage and steam output working condition is suitable for occasions where steam is supplied discontinuously. When the storage tank releases heat, the steam output above 120°C is used in food processing, medical sterilization, cleaning and disinfection, material drying and other processes. The cross-seasonal heat storage condition is suitable for zero-carbon heating in cities. It uses abandoned wind power and photovoltaic power as well as zero-price or negative-price electricity from power plants and power grids as heat sources. The storage tank is charged with heat during the non-heating season and heat is provided during the heating season, thus achieving large-scale zero-cost heat source and zero-carbon heating. The cross-seasonal heat storage operating condition is suitable for cross-seasonal heat storage and peak-shaving in coal-fired power plants. In the non-heating season, abandoned wind power and photovoltaic power are used as heat sources to implement cross-seasonal heat storage. In the heating season, the thermal power plant has "two-way" peak-shaving capabilities. That is, when the unit is operating at low load, it can replace supplementary heat supply to achieve deep peak-shaving. It can also provide heat during high load, reduce air extraction, increase the unit's top load capacity, and achieve thermal and electrical decoupling. The cross-seasonal heat storage condition is suitable for supporting heat storage in desert photovoltaic power stations. A large-scale multi-layer water cross-season multifunctional heat storage tank group is set up to solve the rigid demand for heat storage capacity of wind power and photovoltaic power stations, and locally absorb the abandoned power of wind power and photovoltaic power, and is used for cross-season heating and steam supply in agricultural and animal husbandry plant factories.

8. The operation control method of a single-tank, multi-layer water body, cross-seasonal multifunctional heat storage system according to claim 6, characterized in that: The heating mode is large cycle and small cycle; The large-circulation heating method is as follows: in the initial working condition, the tank is filled with low-temperature water. Water is taken from the top layer, heated by the electric boiler, and becomes high-temperature and high-pressure water. It is then injected into the bottom layer through the water pipeline, mixed with the bottom layer water, and enters the upper layer through the one-way pressure relief valve. The heating is completed when the bottom layer water temperature reaches the set value. By analogy, the operation can be repeated to heat each layer of the tank to the set temperature, thus completing the heating of the tank water. The small-circulation heating method described above: in the initial working condition, the tank is filled with low-temperature water. Taking the heating of the fifth layer as an example: the circulation pump draws water from the water outlet of the fifth layer, and after being heated by the electric boiler, it becomes high-temperature and high-pressure water (set temperature 145°C) and is injected into the water inlet of the fifth layer through the water pipeline, and the water body of the fifth layer is circulated and heated to 145°C. Similarly, the water body of each layer can be heated to the set temperature layer by layer to complete the heating of the entire storage tank.

9. The operation control method of a single-tank, multi-layer water body, cross-seasonal multifunctional heat storage system according to claim 1, characterized in that: The heat storage system's heat energy output modes include outputting hot water for heating, outputting high-temperature and high-pressure water, and outputting high-temperature and low-pressure steam; The above-mentioned method of outputting heating hot water is suitable for supplying medium-temperature (95°C) heating hot water. Medium-temperature normal-pressure water is extracted from the top layer and supplied to the heating system through a heat exchanger. The cooled low-temperature return water is injected into the lowest layer. The high-temperature water in each layer rises layer by layer until all layers are replaced by low-temperature water. The method of outputting high-temperature and high-pressure water is suitable for occasions where high-temperature water is used. High-temperature and high-pressure water can be obtained by pumping out the water at the bottom layer and maintaining the pressure. The method of outputting high-temperature, low-pressure steam is suitable for applications where high-temperature, low-pressure steam or ORC power generation is used. By using a water pump to draw out the high-temperature, high-pressure water in the bottom layer and releasing the pressure, high-temperature, low-pressure steam can be obtained through flash evaporation and converted into electrical energy through the ORC system. Alternatively, the low-pressure steam can be directly output for auxiliary steam use in non-power generation processes of power plants and for operations such as processing and drying of agricultural and animal husbandry products.

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