High-capacity high-temperature water heat storage system

Abstract

The utility model discloses a high-capacity high-temperature water heat storage system which comprises a cold water tank (1), a water inlet pressure reducing valve (2), a drainage pump (3), a heat release heat exchanger (4), a heat storage heat exchanger (5), a hot water spherical tank group (6) and a nitrogen making system (7). The first path, the cold water tank, the drainage pump and the heat storage heat exchanger are sequentially connected through pipelines, and then the heat storage heat exchanger is connected to each spherical tank in the hot water spherical tank group through a pipeline; in the second path, the cold water tank, the water inlet pressure reducing valve and the heat release heat exchanger are sequentially connected through pipelines, and then the heat release heat exchanger is connected to each spherical tank in the hot water spherical tank group through a pipeline; and in the third path, the nitrogen making system is connected to each spherical tank of the hot water spherical tank group through a pipeline. In the system provided by the utility model, air side spaces in the cold water tank and the hot water tank are independent, the design pressure of the cold water tank is reduced, the construction cost is greatly reduced, and meanwhile, the occupied area and the regulation and control complexity of the system are reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of high-temperature water heat storage systems of large capacity, belong to hot water energy storage technical field. BACKGROUND

[0002] At present, hot water energy storage as a kind of energy storage technology with low cost, high energy storage density and high safety is widely used in compressed air energy storage, industrial waste heat utilization and power system peak shaving.

[0003] Figure 4 It is the system diagram of high-temperature water heat storage system under prior art, including heat-releasing heat exchanger 4, heat storage heat exchanger 5, hot water ball tank group 6, nitrogen making system 7 and cold water ball tank group 8.Heat storage process cold water becomes hot water after heat exchange through heat storage heat exchanger 5 from cold water ball tank group 8 and is input into hot water ball tank group 6, and heat-releasing process hot water becomes cold water after heat exchange through heat-releasing heat exchanger 4 from hot water ball tank group 6 and is input into cold water ball tank group 8.Nitrogen gas is filled in ball tank as protective gas, and hot water ball tank group 6 and cold water ball tank group 8 top are connected through nitrogen gas balance pipe and are equipped with nitrogen making system 7 to supplement nitrogen consumption.The high-temperature water storage tank system under prior art has cold tank and hot tank gas side space communication due to the existence of gas side communication pipe, so the cold tank also needs to have the same pressure-bearing capacity as the hot tank, causing the current system to have problems such as many ball tanks, large floor area and large one-time investment.At the same time, gas is transferred between two tanks through balance pipe during heat storage and heat-releasing process, and gas temperature change easily causes pressure frequent fluctuation and nitrogen loss, which affects the stability and economy of overall system operation.

[0004] Taking hot energy storage system in compressed air energy storage power station as an example, in order to improve system efficiency, high-temperature hot water heat storage mode is often used for heat absorption and release in compressed air energy storage system, and the specific mode is as follows: during energy storage process, 50-70 ℃ or so cold water absorbs compression heat released during air compression process, and cold water is heated to hot water above 160 ℃ and stored in hot tank;During energy release process, hot water releases heat to maintain the temperature required for air expansion, and becomes cold water for storage.Currently, in order to improve energy storage density, hot water heat storage temperature is generally higher than 160 ℃, in order to ensure that hot water is still liquid at high temperature, system pressure needs to be maintained higher than water saturation pressure.Therefore, the system always operates in a high pressure range during operation, which produces large nitrogen consumption, and the design pressure of cold tank and hot tank remains consistent. UTILITY MODEL CONTENTS

[0005] The utility model discloses to solve the problems of current water heat storage system, such as many spherical tanks, large occupation area, large pressure fluctuation, etc.

[0006] To solve the above technical problems, the utility model adopts the following technical scheme:

[0007] A kind of high temperature water heat storage system of large capacity, it is characterized by including cold water tank 1, water inlet pressure reducing valve 2, drainage pump 3, heat-releasing heat exchanger 4, heat storage heat exchanger 5, hot water spherical tank group 6 and nitrogen generation system 7;First road, cold water tank 1, drainage pump 3, heat storage heat exchanger 5 are sequentially connected by pipeline, then heat storage heat exchanger 5 is connected by pipeline to each spherical tank in hot water spherical tank group 6;Second road, cold water tank 1, water inlet pressure reducing valve 2, heat-releasing heat exchanger 4 are sequentially connected by pipeline, then heat-releasing heat exchanger 4 is connected by pipeline to each spherical tank in hot water spherical tank group 6;Third road, nitrogen generation system 7 is connected by pipeline to each spherical tank of hot water spherical tank group 6.

[0008] The vertical cylindrical cold water tank 1 is atmospheric water storage tank, preferably, the form of storage tank is floating roof tank storage tank or dome type cylindrical storage tank;When the form of storage tank is dome type cylindrical storage tank, the pressure in the tank is about 2-5KPa micro-positive pressure, and the gas side space in the tank is nitrogen or other protective gas.

[0009] The hot water spherical tank group 6 is spherical water storage tank, and the gas side space in the tank is nitrogen or water vapor or other protective gas, and the design pressure of the spherical tank is not less than 2MPa, which is 1.2-2 times of the water saturation pressure at the design temperature.

[0010] The medium for heat exchange with water in the heat-releasing heat exchanger 4 is gaseous or liquid heat-conducting medium with working temperature within 50-250 DEG C, preferably water, air or heat-conducting oil;The heat exchanger is preferably tube-shell heat exchanger or hairpin heat exchanger.

[0011] In the heat storage heat exchanger 5, the heat exchanger is electric heating or high-temperature medium heat transfer;Preferably, the electric heating device is electric heater, the heat transfer device is tube-shell heat exchanger or hairpin heat exchanger, and the heat exchange medium is water, air or heat-conducting oil.

[0012] The cold water tank storage capacity is generally several times of the hot water tank storage capacity, that is, one cold water tank is matched with multiple hot water tanks to form a system energy storage system;Preferably, the spherical tank volume is 1000m 3 Above, the cold water tank volume is 6000 m 3 Above, one cold water tank is matched with more than two spherical tanks.

[0013] The system preferably has a cold water temperature of 30-60 DEG C and a hot water temperature of 150-250 DEG C.

[0014] The nitrogen production system 7 is connected to each hot tank through a main nitrogen pipeline and a branch pipeline, and a valve is arranged on each branch pipeline, and the gas spaces of the hot tanks are connected through a gas pipeline.

[0015] The water in the high-pressure water heat storage system is deoxygenated salt water.

[0016] Two pipelines are arranged between the vertical cylindrical cold water tank 1 and the spherical tanks in the hot water spherical tank group 6, one pipeline is sequentially connected with the vertical cylindrical cold water tank 1, a water pressure reducing valve 2, a heat releasing heat exchanger 4 and the hot water spherical tank group 6, and the other pipeline is sequentially connected with the vertical cylindrical cold water tank 1, a drainage pump 3, a heat storage heat exchanger 5 and the hot water spherical tank group 6.

[0017] The utility model has the advantages of:

[0018] 1. The utility model discloses a cold tank and a hot tank gas side space are independent, the design pressure of the cold tank is reduced, the wall thickness of the cold tank wall is greatly reduced, and the cost is reduced.

[0019] 2. In the normal pressure or slightly positive pressure working condition, the cold tank is changed into a vertical cylindrical storage tank, a larger storage volume can be designed, and the land occupation and the system control complexity are reduced.

[0020] 3. The utility model avoids the pressure fluctuation caused by the temperature influence when the gas flows from one tank to another tank during the operation, greatly reduces the nitrogen consumption generated during the system operation, improves the system operation stability and reduces the system operation cost. DRAWINGS

[0021] Figure 1 It is a system diagram of the utility model large-capacity high-temperature water heat storage system.

[0022] Figure 2 It is a system diagram of the utility model large-capacity high-temperature water heat storage system cold tank being an arched top cylindrical storage tank.

[0023] Figure 3 It is a system diagram of the utility model large-capacity high-temperature water heat storage system cold tank being an arched top cylindrical storage tank.

[0024] Figure 4 It is a system diagram of the utility model large-capacity high-temperature water heat storage system cold tank being an arched top cylindrical storage tank.

[0025] Reference signs: cold water tank 1, water inlet pressure reducing valve 2, drainage pump 3, heat releasing heat exchanger 4, heat storage heat exchanger 5, hot water spherical tank group 6, nitrogen making system 7 and cold water spherical tank group 8. DETAILED DESCRIPTION

[0026] The advantages and features of the present application will be further illustrated in detail below in combination with the drawings and specific embodiments, so that the protection scope of the present application can be more clearly and explicitly defined.

[0027] As Figure 1 shown, it is a system diagram of a large-capacity high-temperature water heat storage system of the present application, and the system mainly consists of a vertical cylindrical cold water tank, a water inlet pressure reducing valve, a drainage pump, a heat releasing heat exchanger, a heat storage heat exchanger, a hot water spherical tank group and a nitrogen making system. The heat storage process is that cold water is pressurized by the drainage pump after passing through the vertical cylindrical cold water tank and then is introduced into the heat storage heat exchanger, and after being heated, the hot water is introduced into the hot water spherical tank group for storage; the heat releasing process is that high-temperature hot water in the hot water spherical tank group is cooled to cold water after being introduced into the heat releasing heat exchanger, and then is introduced into the vertical cylindrical cold water tank for storage after being depressurized by the pressure reducing valve. Nitrogen is filled by the nitrogen making system for nitrogen protection when the system is first operated.

[0028] As a preferred embodiment of the present application, cold water is stored in the cold tank at 30-60 DEG C, and hot water is stored in the hot tank at 150-250 DEG C. In order to ensure that the hot water is stored in the tank in the form of liquid and does not vaporize or boil, the system pressure needs to be maintained above the saturation pressure. The original heat storage system has a gas side communication pipe, so the cold and hot water tanks have the same pressure, and therefore the cold tank also needs to have the same pressure bearing capacity as the hot tank. The present application cancels the gas side communication pipe, so the cold tank only needs to maintain normal pressure to meet the operation at normal pressure or micro positive pressure 1-5 kPa, the design pressure is greatly reduced, the design wall thickness is correspondingly thinned, and the design volume can be 10000 m 3 above.

[0029] As a preferred embodiment of the present application, the water inlet and outlet pipelines and the nitrogen inlet and outlet pipelines of the spherical tanks in the hot water spherical tank group 6 are connected to the main pipeline through branch pipelines, so when a single spherical tank fails or needs to be overhauled, the spherical tank branch pipeline is cut off from the pipeline system, the spherical tank is overhauled and maintained, and the normal operation of other spherical tanks in the system is not affected.

[0030] As the preferred embodiment of the utility model, when the system stores heat, cold water flows out from the vertical cylindrical cold water tank 1, is boosted to the system pressure through the water pump 3, is introduced into the heat storage heat exchanger 5, exchanges heat with the external heat source, the cold water is heated to the design temperature of hot water, and then flows into the hot tank, the water inlet mode of the hot water ball tank can be designed to be multiple hot tanks simultaneously inletting water or sequentially inletting water according to the design requirement. The heat exchange form can be selected through electric heating or heat exchanger according to the different application scenes, so that the energy storage scene of the system is more abundant, whether the system is used for valley electricity consumption or new energy abandoned electricity recycling, the system can meet the corresponding energy storage demand.

[0031] As the preferred embodiment of the utility model, when the system releases heat, hot water flows out from the ball tank, is introduced into the heat release heat exchanger 4 and exchanges heat with the medium needing to be heated, then the temperature is reduced to the design temperature of cold water, then is depressurized to a relatively low pressure through the pressure reducing valve and is introduced into the vertical cylindrical cold water tank 1, and the heat release process is completed.

[0032] As the preferred embodiment of the utility model, the requirement for water quality in the system is deoxygenated and desalted water. The cold water tank adopts the floating roof tank form, so that nitrogen sealing is not needed, and the cold tank does not need to supplement and discharge nitrogen during operation, so that the nitrogen consumption is greatly reduced.

[0033] Figure 2 It is a system diagram that the cold tank of the utility model one kind large capacity high temperature water heat storage system is dome top cylindrical storage tank, Figure 1 Compared with the form that the cylindrical cold water tank is changed into the dome top tank form from the floating roof tank, the connecting pipeline of the cold water tank and the nitrogen making system is increased.

[0034] In a preferred embodiment of this invention, the cold water tank, in the form of a domed tank, requires nitrogen sealing to isolate it from air. During system operation, the nitrogen pressure inside the domed cold water tank fluctuates slightly positively with changes in liquid level, requiring timely venting and replenishment of nitrogen. However, due to the lower pressure within the cold water tank, nitrogen consumption during operation is significantly less than in conventional spherical tank systems. The hot water tank has higher pressure and temperature, resulting in greater water vapor evaporation. Pressure fluctuations occur during system operation. Since the hot water tank is designed to operate at 1.2-2 times the saturation pressure of water, it possesses pressure-bearing capacity, capable of handling pressure fluctuations between the saturation pressure and the maximum system pressure. Normal operation requires little or no nitrogen venting, resulting in low nitrogen consumption. For safety considerations, the spherical tank can be equipped with appropriate safety valves and exhaust valves to prevent accidental overpressure and can be configured with a nitrogen generation system for emergency replenishment or supplementation of nitrogen consumed during normal operation. The existing thermal storage system, due to the presence of gas-side connecting pipes, involves the transfer of gas between the hot and cold tanks during the heat storage and release processes. During operation, low-temperature nitrogen from the cold tank may enter the hot tank, and high-temperature gas from the hot tank may enter the cold tank. This causes temperature changes and pressure fluctuations, requiring timely nitrogen venting or replenishment based on system pressure fluctuations. However, the system itself operates at high pressure, resulting in high nitrogen density and significant nitrogen venting consumption. Furthermore, it creates temperature differences within the spherical tanks, generating thermal stress. In contrast, the gas temperature fluctuations in the hot tank of this invention are minimal, the pressure changes are more stable, nitrogen consumption during operation is very low, and operating costs are lower.

[0035] like Figure 3 The diagram shown is a simplified representation of a large-capacity high-temperature water storage and heating system of this invention, consisting of a cold tank and four hot water spherical tanks.

[0036] As a preferred embodiment of this utility model, the system diagram is shown. Figure 3 The diagram shows a combination of one cold water thermal storage system and four hot water spherical tank thermal storage systems. In actual engineering projects, one cold water thermal storage system and several hot water spherical tank thermal storage systems can be combined according to the actual needs of the project.

[0037] As a preferred embodiment of this utility model, Figure 3 The system shown is with Figure 4 A preliminary economic comparison is conducted using a simplified system diagram of the existing high-temperature water thermal energy storage system. If a conventional water thermal energy storage system is used, the system would require four cold water spherical tanks, four hot water spherical tanks, and related auxiliary equipment. Taking the parameters of a conventional hot water spherical tank in a current 300MW-class compressed air energy storage power station as an example, a preliminary economic analysis is performed. The relevant parameters are as follows: 3500m³ / s single spherical tank volume. 3Design temperature 200℃, heat storage temperature 190℃, heat release temperature 50℃, design pressure 2MPa, design life 30 years; vertical cold water tank design volume 15000m³ 3 The design temperature is 70℃, the heat release temperature is 50℃, the design pressure is 2kPa, and the design life is 30 years. If a conventional water-based thermal energy storage system is used, the cost of the spherical tank is approximately 8 million yuan, with an initial investment of approximately 64 million yuan. During operation, the water pump power consumption and nitrogen production costs are 7.2 million yuan and 120 million yuan respectively, for a total cost of approximately 190 million yuan. If the patented solution is used, the cost of the vertical cylindrical storage tank is approximately 3 million yuan, with an initial investment of approximately 35 million yuan. During operation, the water pump power consumption and nitrogen production costs are 37.5 million yuan and 18.5 million yuan respectively, for a total cost of approximately 91 million yuan. Preliminary economic analysis shows that the patented solution has significant advantages over the conventional solution. Although it increases pump power consumption, it reduces initial system investment and nitrogen loss. Therefore, overall, the patented solution remains highly economical in terms of overall investment and operating costs. Nitrogen itself does not participate in energy generation; it is only used as a protective gas to isolate the tank from air, preventing high-temperature oxygen corrosion. In practical engineering, considering factors such as technological maturity and steam source, nitrogen purging protection is still the primary method.

[0038] In summary, this utility model provides a large-capacity high-temperature water thermal storage system. By allowing the gas-side spaces of the cold tank and the hot tank to operate independently, on the one hand, the design wall thickness and design pressure of the cold tank can be reduced, and a larger design volume can be selected for the cold tank, thereby reducing the system footprint and construction costs. On the other hand, it greatly reduces the pressure fluctuations and nitrogen consumption caused by gas flow between the cold and hot tanks, improving system stability while also reducing system operating costs.

[0039] The above description is a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present utility model. These improvements and modifications are also considered to be within the protection scope of the present utility model, and the protection scope of the present utility model shall be defined by the claims.

Claims

1. A large-capacity high-temperature water heat storage system, characterized in that: it comprises a cold water tank (1), a water inlet pressure reducing valve (2), a drainage pump (3), a heat release heat exchanger (4), a heat storage heat exchanger (5), a hot water spherical tank group (6) and a nitrogen making system (7); a first path, the cold water tank (1), the drainage pump (3) and the heat storage heat exchanger (5) are connected in sequence by pipelines, and then the heat storage heat exchanger (5) is connected to each spherical tank in the hot water spherical tank group (6) by a pipeline; a second path, the cold water tank (1), the water inlet pressure reducing valve (2) and the heat release heat exchanger (4) are connected in sequence by pipelines, and then the heat release heat exchanger (4) is connected to each spherical tank in the hot water spherical tank group (6) by a pipeline; a third path, the nitrogen making system (7) is connected to each spherical tank in the hot water spherical tank group (6) by a pipeline. The cold water tank (1) is a vertical cylindrical tank, which is a normal pressure water storage tank, and the tank is in the form of a floating roof tank or an arched top cylindrical tank; when the tank is in the form of an arched top cylindrical tank, the pressure in the tank is kept at a micro-positive pressure state of 1 kPa to 5 kPa, and the gas side space in the tank is a protective gas. The hot water spherical tank group (6) is a spherical water storage tank, the gas side space in the tank is nitrogen or water vapor protective gas, and the design pressure of the spherical tank is not less than 2 MPa, which is 1.2-2 times the water saturation pressure at the design temperature. The medium for heat exchange with water in the heat release heat exchanger (4) is a gaseous or liquid heat conducting medium with a working temperature of 50-250℃; the heat exchanger is in the form of a tube-shell heat exchanger or a hairpin heat exchanger. In the heat storage heat exchanger (5), the heat exchanger is an electric heating device or a high-temperature medium heat transfer device; the electric heating device is an electric heater, the high-temperature medium heat transfer device is a tube-shell heat exchanger or a hairpin heat exchanger, and the heat exchange medium is water, air or heat conducting oil.

2. The high-temperature water storage system according to claim 1, wherein: The cold water temperature in the cold water tank is 30-60℃, and the heat storage hot water temperature in the hot water spherical tank group is 150-250℃.

3. The high-temperature water storage system according to claim 1, wherein: The nitrogen making system (7) is connected to each hot tank through a main nitrogen gas pipeline and a branch pipeline, a valve is arranged on each branch pipeline, and the gas spaces of the hot tanks are connected to each other through a gas pipeline; when the cold tank is in the form of an arched top cylindrical tank, the nitrogen making system (7) is connected to the cold tank through another pipeline.

4. The high-temperature water storage system according to claim 1, wherein: The water in the large-capacity high-temperature water heat storage system is deoxygenated water brine.

5. The high-temperature water storage system according to claim 1, wherein: ​ 6. The high-temperature water storage system according to claim 1, wherein: The cold water tank storage capacity is generally several times of the hot water tank storage capacity, that is, one cold water tank is matched with multiple hot water tanks to form a system energy storage system; the volume of a single hot water ball tank is 1000m 3 The volume of a single cold water tank is 6000m 3 One cold water tank is matched with two or more ball tanks.

7. The high-temperature water storage system according to claim 1, wherein: ​ 8. The high-temperature water storage system of claim 1, wherein: ​ 9. The high-temperature water storage system of claim 1, wherein: ​

Images