A heat pump energy storage system for cascade utilization of thermal energy

Abstract

This utility model relates to the field of energy conservation and energy storage technology, and discloses a heat pump energy storage system for cascaded utilization of thermal energy, including a primary heat pump unit, a secondary high-temperature heat pump unit and energy storage system, and a final high-temperature heat pump unit and molten salt energy storage system. The primary heat pump unit includes a waste heat tank, a first primary heat pump, a second primary heat pump, a third primary heat pump, a primary heat storage tank, and a cold storage tank. This utility model, by incorporating the primary heat pump unit, the secondary high-temperature heat pump unit and energy storage system, and the final high-temperature heat pump unit and molten salt energy storage system, utilizes the high coefficient of performance (COP) of the primary heat pump unit and the high heating temperatures of the secondary and final high-temperature heat pump units and molten salt energy storage systems. This enables the system to generate and store high-parameter thermal energy, solving the problem of low energy utilization efficiency and achieving a high COP, thus realizing energy conservation, emission reduction, and promoting the consumption of new energy sources.

Description

Technical Field

[0001] This utility model relates to the field of energy conservation and energy storage technology, specifically to a heat pump energy storage system for cascade utilization of thermal energy. Background Technology

[0002] With the continuous increase in the installed capacity of new energy, new energy represented by wind power and solar power will gradually become the main power source in my country. Since wind power and solar power are severely affected by the environment and weather, they are intermittent and unstable power sources. Configuring efficient energy storage systems is an effective way to ensure the absorption of wind power and solar power.

[0003] In energy-intensive sectors such as chemical and steel industries, utilizing low-priced electricity during off-peak hours and absorbing waste heat emitted during production processes for energy storage to produce high-grade heat energy for heating or power generation not only has good economic benefits in a market environment where the peak-valley electricity price difference continues to widen, but also reduces the environmental impact of waste heat and absorbs green electricity, thus having broad market prospects.

[0004] In existing conventional heat pump technologies, the temperature of the hot water produced is usually below 80℃, which cannot meet the high-grade process heat requirements. Ultra-high temperature heat pumps absorb heat from lower heat sources, and their coefficient of performance (COP) is usually no more than 1.5, resulting in low energy utilization efficiency. Utility Model Content

[0005] The purpose of this invention is to provide a heat pump energy storage system that utilizes thermal energy in a cascade manner, thereby solving the problems of insufficient heating quality and low energy utilization efficiency in existing heat pump technologies.

[0006] This utility model provides the following technical solution: a heat pump energy storage system for the cascade utilization of thermal energy, including a primary heat pump unit, a secondary high-temperature heat pump unit and energy storage system, and a final high-temperature heat pump unit and molten salt energy storage system. The primary heat pump unit includes a waste heat tank, a primary heat pump No. 1, a primary heat pump No. 2, a primary heat pump No. 3, a primary heat storage tank, and a cold storage tank. The secondary high-temperature heat pump unit and energy storage system include a secondary high-temperature heat exchanger, a secondary high-temperature heat pump gas compressor, a secondary high-temperature heat pump drive motor, a secondary high-temperature gas expander, an intermediate medium heater, an intermediate medium cold storage tank, and an intermediate medium heat storage tank. The final-stage high-temperature heat pump unit and molten salt energy storage system include a final-stage high-temperature heat exchanger, a final-stage high-temperature heat pump gas compressor, a final-stage high-temperature heat pump drive motor, a final-stage high-temperature gas expander, a molten salt heater, a low-temperature molten salt storage tank, and a high-temperature molten salt tank. The coefficient of performance (COP) of the primary heat pump unit, the secondary high-temperature heat pump unit and energy storage system, and the final high-temperature heat pump unit and molten salt energy storage system is defined as the ratio of system output heat to input energy: COP = Q / W; The COP of the primary heat pump unit is 3-6, the temperature of the medium stored in the waste heat tank is 20℃-80℃, the temperature of the medium stored in the primary heat storage tank is 80℃-150℃, and the temperature of the medium stored in the cold storage tank is 0℃-10℃. The COP of the secondary high-temperature heat pump unit and energy storage system is 2-4, the medium temperature of the intermediate medium cold storage tank is 120℃-200℃, and the medium temperature of the intermediate medium heat storage tank is 150℃-300℃. The COP of the final-stage high-temperature heat pump unit and molten salt energy storage system is 1.5-3, the molten salt temperature of the low-temperature molten salt storage tank is 180℃-300℃, and the molten salt temperature of the high-temperature molten salt tank is 400℃-565℃. The high-temperature molten salt tank includes a tank body, and a convenient maintenance mechanism is provided on the top of the tank body.

[0007] As a preferred embodiment of the above technical solution, the primary heat pump unit, the secondary high-temperature heat pump unit, and the energy storage system are coupled through heat exchange, the primary heat storage tank and the secondary high-temperature heat exchanger are connected by a pipeline, and the cold storage tank and the secondary high-temperature heat exchanger are connected by a pipeline.

[0008] As a preferred embodiment of the above technical solution, the secondary high-temperature heat pump unit and energy storage system, the final high-temperature heat pump unit and molten salt energy storage system are coupled through heat exchange, the intermediate medium heat storage tank is connected to the final high-temperature heat exchanger through a pipeline, and the intermediate medium cold storage tank is connected to the final high-temperature heat exchanger through a pipeline.

[0009] As a preferred embodiment of the above technical solution, the waste heat tank absorbs low-grade heat energy, raises the temperature of the medium, and stores the heat energy in the primary heat storage tank. The medium in the primary heat storage tank absorbs heat energy, raises the temperature again, and stores the heat energy in the intermediate medium heat storage tank. The final-stage high-temperature heat pump unit and molten salt energy storage system absorb heat energy from the intermediate medium heat storage tank to heat the molten salt and store it in the high-temperature molten salt tank.

[0010] As a preferred embodiment of the above technical solution, the convenient maintenance mechanism includes a top plate, which is fixedly installed on the top of the tank. A molten salt extraction pipe is fixedly connected to the top of the top plate, and a molten salt return pipe is fixedly connected to the top of the top plate. A fitting groove is formed on the top of the top plate, and a movable plate seat is movably inserted into the inner cavity of the fitting groove. A heat exchange pipe is fixedly connected to the bottom of the movable plate seat, and an air inlet pipe and an air outlet pipe are fixedly connected to the top of the movable plate seat. A support block is fixedly installed on the top of the top plate, and a sliding rod is slidably connected to the inner wall of the support block. A limit block is fixedly installed at the end of the sliding rod.

[0011] Compared with the prior art, the beneficial effects of this utility model are: This utility model incorporates a primary heat pump unit, a secondary high-temperature heat pump unit and energy storage system, and a final high-temperature heat pump unit and molten salt energy storage system. Utilizing the high coefficient of performance (COP) of the primary heat pump unit and the high heating temperatures of the secondary high-temperature heat pump unit and energy storage system, as well as the final high-temperature heat pump unit and molten salt energy storage system, this system can generate and store high-parameter thermal energy with a high COP, achieving energy conservation, emission reduction, and promoting the consumption of new energy sources. Attached Figure Description

[0012] Figure 1 A schematic diagram of a heat pump energy storage system for cascade utilization of thermal energy; Figure 2 This is a schematic diagram of the structure of the high-temperature molten salt tank of this utility model; Figure 3 This is a schematic diagram of the structure of the convenient maintenance mechanism of this utility model; Figure 4 This is a schematic diagram of the structure of the limiting block of this utility model.

[0013] In the diagram: 100, Primary heat pump unit; 101, Waste heat tank; 102, Primary heat pump No. 1; 103, Primary heat pump No. 2; 104, Primary heat pump No. 3; 105, Primary heat storage tank; 106, Cold storage tank; 200, Secondary high-temperature heat pump unit and energy storage system; 201, Secondary high-temperature heat exchanger; 202, Secondary high-temperature heat pump gas compressor; 203, Secondary high-temperature heat pump drive motor; 204, Secondary high-temperature gas expander; 205, Intermediate medium heater; 206, Intermediate medium cold storage tank; 207, Intermediate medium heat storage tank; 300, Final stage high-temperature heat pump. Unit and molten salt energy storage system; 301, final stage high-temperature heat exchanger; 302, final stage high-temperature heat pump gas compressor; 303, final stage high-temperature heat pump drive motor; 304, final stage high-temperature gas expander; 305, molten salt heater; 306, low-temperature molten salt storage tank; 307, high-temperature molten salt tank; 4, tank body; 5, convenient maintenance mechanism; 51, top plate; 52, molten salt extraction pipe; 53, molten salt return pipe; 54, fitting groove; 55, movable plate base; 56, heat exchange tube; 57, air inlet pipe; 58, exhaust pipe; 59, support block; 591, slide bar; 592, limit block. Detailed Implementation

[0014] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0015] like Figures 1-4 As shown, this utility model provides a technical solution: a heat pump energy storage system for the cascade utilization of thermal energy, including a primary heat pump unit 100, a secondary high-temperature heat pump unit and energy storage system 200, and a final high-temperature heat pump unit and molten salt energy storage system 300. The primary heat pump unit 100 includes a waste heat tank 101, a primary heat pump 102, a primary heat pump 103, a primary heat pump 104, a primary heat storage tank 105, and a cold storage tank 106. It should include at least two primary heat pumps. The primary heat pumps can be connected in series or in parallel. The working fluid of the primary heat pump unit 100 can be a gas or an organic working fluid. The secondary high-temperature heat pump unit and energy storage system 200 includes a secondary high-temperature heat exchanger 201, a secondary high-temperature heat pump gas compressor 202, a secondary high-temperature heat pump drive motor 203, a secondary high-temperature gas expander 204, an intermediate medium heater 205, an intermediate medium cold storage tank 206, and an intermediate medium heat storage tank 207. The final-stage high-temperature heat pump unit and molten salt energy storage system 300 includes a final-stage high-temperature heat exchanger 301, a final-stage high-temperature heat pump gas compressor 302, a final-stage high-temperature heat pump drive motor 303, a final-stage high-temperature gas expander 304, a molten salt heater 305, a low-temperature molten salt storage tank 306, and a high-temperature molten salt tank 307. The coefficient of performance (COP) of the primary heat pump unit 100, the secondary high-temperature heat pump unit and energy storage system 200, and the final high-temperature heat pump unit and molten salt energy storage system 300 is defined as the ratio of system output heat to input energy: COP = Q / W, where Q is the cooling or heating provided by the system (unit: kW) and W is the power consumed by the system (unit: kW). The COP of the primary heat pump unit 100 is 3-6, the temperature of the medium stored in the waste heat tank 101 is 20℃-80℃, the temperature of the medium stored in the primary heat storage tank 105 is 80℃-150℃, and the temperature of the medium stored in the cold storage tank 106 is 0℃-10℃. The COP of the secondary high-temperature heat pump unit and energy storage system 200 is 2-4, the medium temperature of the intermediate medium cold storage tank 206 is 120℃-200℃, the medium temperature of the intermediate medium heat storage tank 207 is 150℃-300℃, and the intermediate medium can be heat transfer oil, molten salt or liquid metal. The COP of the final stage high-temperature heat pump unit and molten salt energy storage system 300 is 1.5-3, the molten salt temperature of the low-temperature molten salt storage tank 306 is 180℃-300℃, the molten salt temperature of the high-temperature molten salt tank 307 is 400℃-565℃, and the molten salt can be a binary nitrate or a ternary nitrate. The high-temperature molten salt tank 307 includes a tank body 4, and a convenient maintenance mechanism 5 is provided on the top of the tank body 4; Waste heat tank 101 is connected to the primary heat pump via a pipeline; the primary heat pump is connected to the primary heat storage tank 105 via a pipeline; the secondary high-temperature heat exchanger 201 is connected to the secondary high-temperature heat pump gas compressor 202 via a pipeline; the intermediate medium heater 205 is connected to the intermediate medium heat storage tank 207 via a pipeline; the intermediate medium heater 205 is connected to the intermediate medium cold storage tank 206 via a pipeline; the secondary high-temperature heat exchanger 201 is connected to the secondary high-temperature gas expander 204 via a pipeline; the final high-temperature heat exchanger 301 is connected to the final high-temperature heat pump gas compressor 302 via a pipeline; the molten salt heater 305 is connected to the high-temperature molten salt tank 307 via a pipeline; the molten salt heater 305 is connected to the low-temperature molten salt storage tank 306 via a pipeline; the molten salt heater 305 is connected to the final high-temperature gas expander 304 via a pipeline; and the final high-temperature gas expander 304 is connected to the final high-temperature heat exchanger 301 via a pipeline.

[0016] As one implementation method in this embodiment, such as Figure 1 As shown, the primary heat pump unit 100, the secondary high-temperature heat pump unit and the energy storage system 200 are coupled through heat exchange. The primary heat storage tank 105 is connected to the secondary high-temperature heat exchanger 201 through a pipeline, and the cold storage tank 106 is connected to the secondary high-temperature heat exchanger 201 through a pipeline.

[0017] As one implementation method in this embodiment, such as Figure 1 As shown, the secondary high-temperature heat pump unit and energy storage system 200 and the final high-temperature heat pump unit and molten salt energy storage system 300 are coupled through heat exchange. The intermediate medium heat storage tank 207 is connected to the final high-temperature heat exchanger 301 through a pipeline, and the intermediate medium cold storage tank 206 is connected to the final high-temperature heat exchanger 301 through a pipeline.

[0018] As one implementation method in this embodiment, such as Figure 1 As shown, the waste heat tank 101 absorbs low-grade heat energy, raises the temperature of the medium, and stores the heat energy in the primary heat storage tank 105. The medium in the primary heat storage tank 105 absorbs heat energy, raises the temperature again, and stores the heat energy in the intermediate medium heat storage tank 207. The final high-temperature heat pump unit and molten salt energy storage system 300 absorb heat energy from the intermediate medium heat storage tank 207 to heat the molten salt and store it in the high-temperature molten salt tank 307.

[0019] As one implementation method in this embodiment, such as Figure 2 , Figure 3 , Figure 4As shown, the convenient maintenance mechanism 5 includes a top plate 51, which is fixedly installed on the top of the tank 4. A molten salt extraction pipe 52 and a molten salt return pipe 53 are fixedly connected to the top of the top plate 51. A fitting groove 54 is provided on the top of the top plate 51. A movable plate seat 55 is movably inserted into the inner cavity of the fitting groove 54. A heat exchange pipe 56 is fixedly connected to the bottom of the movable plate seat 55. An air inlet pipe 57 and an exhaust pipe 58 are fixedly connected to the top of the movable plate seat 55. A support block 59 is fixedly installed on the top of the top plate 51. A sliding rod 591 is slidably connected to the inner wall of the support block 59. A limit block 592 is fixedly installed at the end of the sliding rod 591. To facilitate the use of the heat inside the high-temperature molten salt tank 307, a heat exchanger is integrated inside it. The heat exchanger is mostly fixed in the high-temperature molten salt tank 307. On 07, maintenance after a period of use is relatively inconvenient. This problem can be solved by the overall design of the convenient maintenance mechanism 5. In the initial state, the bolts on the top of the support block 59 are tightened, locking the position of the slide rod 591 and the limiting block 592. The limiting block 592 is used to limit the moving plate seat 55 in the inner cavity of the fitting groove 54. If it is necessary to disassemble and clean the heat exchange tube 56, loosen the bolts on the top of the support block 59, and then push the limiting block 592 out from the top of the moving plate seat 55. Then the moving plate seat 55 can be removed from the inner cavity of the fitting groove 54 for maintenance. The two ends of the heat exchange tube 56 are connected to the air inlet pipe 57 and the exhaust pipe 58 respectively, so that the medium can flow through the inner cavity of the heat exchange tube 56 and carry away the heat inside the tank 4 for normal use.

[0020] Working Principle: This system stores energy during off-peak electricity hours when electricity prices are low. During the storage phase, a primary heat pump unit 100, driven by electricity, absorbs low-grade heat energy from the waste heat tank 101, raising the medium temperature and storing the heat energy in the primary heat storage tank 105. A secondary high-temperature heat pump drive motor 203 drives a secondary high-temperature heat pump unit to absorb heat energy from the medium in the primary heat storage tank 105. The secondary high-temperature heat pump gas compressor 202 compresses the working fluid to generate high temperature, which is then exchanged with the intermediate medium heater 205 and stored in the intermediate medium heater. In the intermediate medium heat storage tank 207, the final-stage high-temperature heat pump unit absorbs heat energy from the intermediate medium heat storage tank 207 and generates high temperature by compressing the working fluid through the final-stage high-temperature heat pump gas compressor 302. After exchanging heat with the low-temperature molten salt from the low-temperature molten salt storage tank 306 through the molten salt heater 305, it is stored in the high-temperature molten salt tank 307, completing the cascade heating and storage of energy. The temperature of the hot molten salt stored in the high-temperature molten salt tank 307 is 400℃-565℃, which can be used for process heating or power generation during peak electricity price periods, thereby achieving the effects of energy saving and energy storage.

[0021] The above embodiments are only used to illustrate the technical solution of this utility model, and are not intended to limit it.

Claims

1. A heat pump energy storage system for thermal cascade utilization, characterized in that It includes a primary heat pump unit (100), a secondary high-temperature heat pump unit and energy storage system (200), and a final high-temperature heat pump unit and molten salt energy storage system (300). The primary heat pump unit (100) includes a waste heat tank (101), a primary heat pump No. 1 (102), a primary heat pump No. 2 (103), a primary heat pump No. 3 (104), a primary heat storage tank (105), and a cold storage tank (106). The secondary high-temperature heat pump unit and energy storage system (200) includes a secondary high-temperature heat exchanger (201), a secondary high-temperature heat pump gas compressor (202), a secondary high-temperature heat pump drive motor (203), a secondary high-temperature gas expander (204), an intermediate medium heater (205), an intermediate medium cold storage tank (206), and an intermediate medium heat storage tank (207). The final stage high-temperature heat pump unit and molten salt energy storage system (300) includes a final stage high-temperature heat exchanger (301), a final stage high-temperature heat pump gas compressor (302), a final stage high-temperature heat pump drive motor (303), a final stage high-temperature gas expander (304), a molten salt heater (305), a low-temperature molten salt storage tank (306), and a high-temperature molten salt tank (307). The waste heat tank (101) stores a medium with a temperature of 20℃-80℃, the primary heat storage tank (105) stores a medium with a temperature of 80℃-150℃, and the cold storage tank (106) stores a medium with a temperature of 0℃-10℃. The medium temperature of the intermediate medium cold storage tank (206) is 120℃-200℃, and the medium temperature of the intermediate medium heat storage tank (207) is 150℃-300℃. The molten salt temperature of the low-temperature molten salt storage tank (306) is 180℃-300℃, and the molten salt temperature of the high-temperature molten salt tank (307) is 400℃-565℃. The high-temperature molten salt tank (307) includes a tank body (4), and a convenient maintenance mechanism (5) is provided on the top of the tank body (4).

2. The heat pump energy storage system of claim 1, wherein: The primary heat pump unit (100), the secondary high-temperature heat pump unit and the energy storage system (200) are coupled through heat exchange. The primary heat storage tank (105) and the secondary high-temperature heat exchanger (201) are connected by a pipeline. The cold storage tank (106) and the secondary high-temperature heat exchanger (201) are connected by a pipeline.

3. The heat pump energy storage system of claim 1, wherein: The secondary high-temperature heat pump unit and energy storage system (200), the final high-temperature heat pump unit and molten salt energy storage system (300) are coupled through heat exchange. The intermediate medium heat storage tank (207) is connected to the final high-temperature heat exchanger (301) through a pipeline. The intermediate medium cold storage tank (206) is connected to the final high-temperature heat exchanger (301) through a pipeline.

4. The heat pump energy storage system of claim 1, wherein: The waste heat tank (101) absorbs low-grade heat energy, raises the temperature of the medium, and stores the heat energy in the primary heat storage tank (105). The medium in the primary heat storage tank (105) absorbs heat energy, raises the temperature again, and stores the heat energy in the intermediate medium heat storage tank (207). The final-stage high-temperature heat pump unit and molten salt energy storage system (300) absorb heat energy from the intermediate medium heat storage tank (207) to heat the molten salt and store it in the high-temperature molten salt tank (307).

5. The heat pump energy storage system of claim 1, wherein: The convenient maintenance mechanism (5) includes a top plate (51), which is fixedly installed on the top of the tank (4). A molten salt extraction pipe (52) is fixedly connected to the top of the top plate (51), and a molten salt return pipe (53) is fixedly connected to the top of the top plate (51). A fitting groove (54) is provided on the top of the top plate (51), and a movable plate seat (55) is movably inserted into the inner cavity of the fitting groove (54). A heat exchange pipe (56) is fixedly connected to the bottom of the movable plate seat (55).

6. The heat pump energy storage system of claim 5, wherein: The top of the movable plate base (55) is fixedly connected to an air inlet pipe (57) and an exhaust pipe (58). The top of the top plate (51) is fixedly installed with a support block (59). A slide rod (591) is slidably connected to the inner wall of the support block (59). A limit block (592) is fixedly installed at the end of the slide rod (591).

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