Heat and power cogeneration system coupled with heat pump and carbon dioxide energy storage

Abstract

The utility model discloses a combined heat and power system coupled with a heat pump and carbon dioxide energy storage, which stores and releases energy through the liquefaction and vaporization of carbon dioxide, and simultaneously generates cold energy and heat energy required by the liquefaction and vaporization of carbon dioxide by using a heat pump system. As the vaporization heat of carbon dioxide is equal to the liquefaction heat, and the refrigerating capacity of the heat pump system is equal to the liquefaction heat of carbon dioxide, the heating capacity of the heat pump system is the sum of the refrigerating capacity and the acting of the compressor, and the heating capacity of the heat pump is always greater than the vaporization heat of carbon dioxide; surplus heat can be used for commercial or living heat supply during carbon dioxide vaporization, and heat and power cogeneration is achieved; meanwhile, carbon dioxide is liquefied and stored, and the evaporation heat accumulator and the condensation heat accumulator are filled with the phase change material to exchange heat with the heat exchange medium, so that the occupied space of the heat pump system is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of physical energy storage, and in particular relates to a heat and power cogeneration system coupled with a heat pump and carbon dioxide energy storage. Background Art

[0002] Despite rising electricity demand, coal remains the primary energy source, and coal-fired power generation will likely maintain a significant share for a long time to come. This poses a significant challenge to achieving both carbon peak and carbon neutrality, as the scope for carbon reduction is limited. Achieving the dual carbon goals requires building a new power system dominated by renewable energy. However, renewable energy is subject to natural constraints, exhibiting significant volatility and intermittency. Large-scale grid integration can compromise the safe and stable operation of the power grid, resulting in low utilization rates and significant development challenges.

[0003] Amid the rapid development of new energy sources, new energy storage has become a key component in building a new power system. Liquid CO2 energy storage converts electrical energy into the thermal and potential energy of CO2 for energy storage. Compared to air, CO2 is easier to liquefy, eliminating the need for underground caverns and offering greater flexibility in site selection. Furthermore, CO2 has a high specific heat capacity and excellent heat transfer properties, resulting in lower parasitic energy consumption and higher system efficiency. Therefore, liquid CO2 energy storage offers significant advantages, including ultra-long-term storage, large-scale operation, high flexibility, high efficiency, and high energy storage density, making it a promising candidate for future development.

[0004] However, the liquid carbon dioxide energy storage system requires a large amount of cooling and heat to liquefy and vaporize carbon dioxide. Currently, liquefaction is mostly achieved through throttling and cooling, which loses the pressure release energy of carbon dioxide and reduces the system's electricity-to-electricity conversion efficiency. Vaporization is mostly achieved through the use of industrial waste heat, which increases the limitations of system site selection. Summary of the Invention

[0005] The purpose of the utility model is to provide a heat and power cogeneration system coupling a heat pump and carbon dioxide energy storage.

[0006] The utility model provides a heat and power cogeneration system coupled with a heat pump and carbon dioxide energy storage, which includes a heat pump system and a low-pressure carbon dioxide storage tank, an energy storage low-pressure heat exchange component, a first compressor, an energy storage high-pressure heat exchange component, a liquefaction component, a high-pressure carbon dioxide storage tank, a vaporization component, an energy release high-pressure heat exchange component, a turbine, and an energy release low-pressure heat exchange component, which are sequentially connected to form an energy storage and release circulation loop.

[0007] The liquefaction assembly is provided with a first liquefaction heat exchange path and a second liquefaction heat exchange path; the vaporization assembly is provided with a first vaporization heat exchange path and a second vaporization heat exchange path. The first liquefaction heat exchange path of the liquefaction assembly and the first vaporization heat exchange path of the vaporization assembly are connected to the energy storage and release circulation loop. The heat pump system is connected to the second liquefaction heat exchange path of the liquefaction assembly and the second vaporization heat exchange path of the vaporization assembly, respectively.

[0008] Preferably, the heat pump system includes an evaporative heat accumulator, a second compressor, and a condensing heat accumulator; the evaporative heat accumulator is provided with a first cold storage heat exchange path and a second cold storage heat exchange path; the condensing heat accumulator is provided with a first heat storage heat exchange path and a second heat storage heat exchange path; the first cold storage heat exchange path of the evaporative heat accumulator and the second liquefaction heat exchange path of the liquefaction component are sequentially connected to form a liquefaction circulation loop; the first heat storage heat exchange path of the condensing heat accumulator and the second vaporization heat exchange path of the vaporization component are sequentially connected to form a vaporization circulation loop; the second cold storage heat exchange path of the evaporative heat accumulator, the second compressor, and the second heat storage heat exchange path of the condensing heat accumulator are sequentially connected to form a circulation loop. The evaporative heat accumulator and the condensing heat accumulator store cold and heat through the second cold storage heat exchange path and the second heat storage heat exchange path, respectively, and provide cooling and heat to the liquefaction component and the vaporization component through the liquefaction circulation loop and the vaporization circulation loop.

[0009] Preferably, the heat and power cogeneration system coupled with the heat pump and carbon dioxide energy storage further comprises a heating unit; the heating unit is connected in parallel between the two ends of the condensing heat accumulator.

[0010] Preferably, the heating unit is a heat exchanger connected to an external heating device, and the external heating device is a water heater.

[0011] Preferably, phase change materials are stored in both the evaporation heat accumulator and the condensation heat accumulator; in the evaporation heat accumulator, the cold released by the refrigerant in the cold and heat storage state is stored in the phase change material, and carbon dioxide is supplied for liquefaction during the energy storage process; in the condensation heat accumulator, the heat released by the refrigerant in the cold and heat storage state is stored in the phase change material, and carbon dioxide is supplied for vaporization during the energy release process.

[0012] Preferably, a first throttle valve is provided between the low-pressure carbon dioxide storage tank and the energy storage low-pressure heat exchange component; during the energy storage process, the liquid carbon dioxide output from the low-pressure carbon dioxide storage tank has a reduced flow cross-sectional area when passing through the first throttle valve and is converted into gas-liquid two-phase carbon dioxide; an on-off valve is provided between the low-pressure carbon dioxide storage tank and the energy release low-pressure heat exchange component.

[0013] Preferably, the energy storage low-pressure heat exchange component, the energy storage high-pressure heat exchange component, the energy release high-pressure heat exchange component and the energy release low-pressure heat exchange component each include one or multiple heat exchangers connected in sequence.

[0014] Preferably, the heat exchangers in the energy storage low-pressure heat exchange assembly correspond one-to-one with the heat exchangers in the energy release low-pressure heat exchange assembly, with a heat storage tank and a cold storage tank connected in parallel between the two corresponding heat exchangers, and connected to form a circulation loop via a heat exchange medium pipeline. The heat exchangers in the energy storage high-pressure heat exchange assembly correspond one-to-one with the heat exchangers in the energy release high-pressure heat exchange assembly, with a heat storage tank and a cold storage tank connected in parallel between the two corresponding heat exchangers, and connected to form a circulation loop via a heat exchange medium pipeline.

[0015] Preferably, a second throttle valve is provided between the input end of the second cold storage heat exchange path in the evaporating heat accumulator and the output end of the second heat storage heat exchange path in the condensing heat accumulator; the second throttle valve is used to convert the liquid refrigerant flowing through into a gas-liquid two-phase refrigerant.

[0016] Preferably, the efficient operating range of the second compressor is 20°C~40°C.

[0017] The beneficial effects of the utility model are:

[0018] 1. The present invention utilizes a heat pump system to simultaneously generate the cooling and heat required for liquefying and vaporizing carbon dioxide, so that the heating capacity of the heat pump system will always be greater than the heat of vaporization of carbon dioxide. This allows the heat pump system to have surplus heat for commercial or domestic heating when vaporizing carbon dioxide, thus realizing combined heat and power. At the same time, the heat pump system in the present invention can be in a cold and heat storage state for a long time during off-peak hours, thereby reducing the power of each component in the heat pump system and lowering costs.

[0019] 2. The utility model reduces the floor space of the heat pump system by liquefying and storing carbon dioxide and filling the evaporation heat accumulator and the condensation heat accumulator with phase change materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the utility model.

[0021] Figure numerals: 1. Low-pressure carbon dioxide storage tank; 2. Energy storage low-pressure heat exchange component; 3. First compressor; 4. Energy storage high-pressure heat exchange component; 5. Liquefaction component; 6. High-pressure carbon dioxide storage tank; 7. Vaporization component; 8. Energy release high-pressure heat exchange component; 9. Turbine; 10. Energy release low-pressure heat exchange component; 11. Heating unit; 12. First throttle valve; 13. On-off valve; 14. Evaporation heat accumulator; 15. Second compressor; 16. Condensation heat accumulator; 17. Second throttle valve. DETAILED DESCRIPTION

[0022] The present invention will be further described below with reference to the accompanying drawings.

[0023] like Figure 1As shown, a heat and power cogeneration system coupled with a heat pump and carbon dioxide energy storage includes a heat pump system, a heating unit 11, and a low-pressure carbon dioxide storage tank 1, a low-pressure energy storage heat exchange assembly 2, a first compressor 3, a high-pressure energy storage heat exchange assembly 4, a liquefaction assembly 5, a high-pressure carbon dioxide storage tank 6, a vaporization assembly 7, a high-pressure energy release heat exchange assembly 8, a turbine 9, and a low-pressure energy release heat exchange assembly 10, which are sequentially connected to form an energy storage and release cycle. The low-pressure energy storage heat exchange assembly 2 is connected to the low-pressure carbon dioxide storage tank 1 via a first throttle valve 12, which converts the liquid carbon dioxide output from the low-pressure carbon dioxide storage tank 1 into gas-liquid two-phase carbon dioxide. The low-pressure energy release heat exchange assembly 10 is connected to the low-pressure carbon dioxide storage tank 1 via an on-off valve 13. The liquefaction assembly 5 is provided with a first liquefaction heat exchange path and a second liquefaction heat exchange path. The vaporization assembly 7 is provided with a first vaporization heat exchange path and a second vaporization heat exchange path. The first liquefaction heat exchange path of the liquefaction assembly 5 and the first vaporization heat exchange path of the vaporization assembly 7 are connected to the energy storage and release cycle. The energy-releasing low-pressure heat exchange component 10 and the energy-storing low-pressure heat exchange component 2 each include two heat exchangers connected in series. The heat exchanger in the energy-releasing low-pressure heat exchange component 10 corresponds one-to-one to the heat exchanger in the energy-storing low-pressure heat exchange component 2. A heat storage tank and a cold storage tank are connected in parallel between the corresponding two heat exchangers, and are connected into a circulation loop through a heat exchange medium pipeline; the energy storage high-pressure heat exchange component 4, the heat storage tank, the energy-releasing high-pressure heat exchange component 8 and the cold storage tank are connected in sequence into a circulation loop through a heat exchange medium pipeline.

[0024] The heat pump system includes an evaporator 14, a second compressor 15, a condenser 16, and a second throttle valve 17. The evaporator 14 is provided with a first cold storage heat exchange path and a second cold storage heat exchange path. The condenser 16 is provided with a first heat storage heat exchange path and a second heat storage heat exchange path. The first cold storage heat exchange path of the evaporator 14 and the second liquefaction heat exchange path of the liquefaction module 5 are sequentially connected to form a liquefaction circulation loop. The first heat storage heat exchange path of the condenser 16 and the second vaporization heat exchange path of the vaporization module 7 are sequentially connected to form a vaporization circulation loop. The second cold storage heat exchange path of the evaporator 14, the second compressor 15, and the second heat storage heat exchange path of the condenser 16 are sequentially connected to form a circulation loop. The evaporator 14 and the condenser 16 store cold and heat through the liquefaction and vaporization of the refrigerant in the circulation loop formed by the second cold storage heat exchange path and the second heat storage heat exchange path, and provide cooling and heat to the liquefaction module 5 and the vaporization module 7 through the liquefaction circulation loop and the vaporization circulation loop. The second throttle valve 17 converts the flowing liquid refrigerant into a two-phase gas-liquid refrigerant; the second compressor 15 pressurizes and heats the gaseous refrigerant. The heating unit 11 is connected in parallel between the two ends of the condensing heat accumulator 16. This unit utilizes a heat exchanger connected to an external heating device, which is a water heater. During operation, the energy storage system switches between cold and heat storage, energy storage, and energy release.

[0025] In the energy storage state, first throttle valve 12 is open, and on-off valve 13 and second throttle valve 17 are closed. Liquid carbon dioxide in low-pressure carbon dioxide storage tank 1, under the action of a pressure differential, passes through the open first throttle valve 12, where it is converted into gas-liquid two-phase carbon dioxide under the action of throttling and vaporization, and then enters energy storage low-pressure heat exchange assembly 2. The two heat exchangers in energy storage low-pressure heat exchange assembly 2 exchange heat with the carbon dioxide through the heat transfer medium input from the corresponding heat storage tank, causing the gas-liquid two-phase carbon dioxide to gradually increase in temperature within energy storage low-pressure heat exchange assembly 2, outputting gaseous carbon dioxide. The heat transfer medium is then transported to the corresponding cold storage tank for storage. First compressor 3 consumes electrical energy to pressurize the gaseous carbon dioxide output from energy storage low-pressure heat exchange assembly 2, and then inputs it into energy storage high-pressure heat exchange assembly 4. The energy storage high-pressure heat exchange component 4 exchanges heat with the heat transfer medium input from the corresponding cold storage tank, so that the gaseous carbon dioxide is cooled in the energy storage high-pressure heat exchange component 4 and input into the liquefaction component 5, and the heat transfer medium is transported to the corresponding heat storage tank for storage; the carbon dioxide in the liquefaction component 5 exchanges heat with the phase change material in the evaporative cold storage device 13 through the heat transfer medium, so that the gaseous carbon dioxide is converted into liquid carbon dioxide in the liquefaction component 5 and transported to the high-pressure carbon dioxide storage tank 6 for storage, and the solid phase change material in the evaporative cold storage device 13 is converted into liquid phase change material.

[0026] In this embodiment, the carbon dioxide at the outlet of the first compressor 3 is a supercritical gas; the conventional high-efficiency operating range of the second compressor 15 is 20°C~40°C, which can increase the residual cooling of 20°C~25°C generated when the gaseous carbon dioxide is liquefied during the energy storage process to 40°C~50°C.

[0027] In the energy release state, the on-off valve 13 is open, and the first throttle valve 12 and the second throttle valve 17 are closed. Liquid carbon dioxide from the high-pressure carbon dioxide storage tank 6 is fed into the vaporizer assembly 7. The carbon dioxide in the vaporizer assembly 7 exchanges heat with the phase-change material in the condensation heat accumulator 16 via a heat transfer medium, converting the liquid phase-change material in the condensation heat accumulator 16 into a solid phase-change material. The liquid carbon dioxide in the vaporizer assembly 7 is converted into gaseous carbon dioxide and fed into the energy release high-pressure heat exchange assembly 8. After the liquid carbon dioxide is vaporized, the excess high-temperature heat exchange medium at the outlet of the condensation heat accumulator enters the heat supply unit 11 for heat supply. The energy release high-pressure heat exchange assembly 8 exchanges heat with the carbon dioxide through the heat transfer medium fed from the corresponding heat storage tank, causing the gaseous carbon dioxide to heat up in the energy release high-pressure heat exchange assembly 8 and be fed into the turbine 9. The heat transfer medium is then transported to the corresponding cold storage tank for storage. The turbine 9 performs work externally through the expansion of the gaseous carbon dioxide, releasing energy, and feeds the gaseous carbon dioxide into the energy release low-pressure heat exchange assembly 10. The two heat exchangers in the energy-releasing low-pressure heat exchange component 10 exchange heat with carbon dioxide through the heat transfer medium input from the corresponding cold storage tank, so that the gaseous carbon dioxide is gradually cooled in the energy-releasing low-pressure heat exchange component 10, and liquid carbon dioxide is obtained and transported to the low-pressure carbon dioxide storage tank 1 for storage through the on-off valve 13, and the heat transfer medium is transported to the corresponding heat storage tank for storage.

[0028] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments.

Claims

1. A heat and power cogeneration system coupled with a heat pump and carbon dioxide energy storage, comprising a heat pump system and a low-pressure carbon dioxide storage tank (1), an energy storage low-pressure heat exchange component (2), a first compressor (3), an energy storage high-pressure heat exchange component (4), a liquefaction component (5), a high-pressure carbon dioxide storage tank (6), a vaporization component (7), an energy release high-pressure heat exchange component (8), a turbine (9), and an energy release low-pressure heat exchange component (10), which are sequentially connected to form an energy storage and release circulation loop; Its characteristics are: The liquefaction component (5) is provided with a first liquefaction heat exchange path and a second liquefaction heat exchange path; the vaporization component (7) is provided with a first vaporization heat exchange path and a second vaporization heat exchange path; the first liquefaction heat exchange path of the liquefaction component (5) and the first vaporization heat exchange path of the vaporization component (7) are connected to the energy storage and release circulation loop; the heat pump system is respectively connected to the second liquefaction heat exchange path of the liquefaction component (5) and the second vaporization heat exchange path of the vaporization component (7).

2. The combined heat and power system coupling a heat pump and carbon dioxide energy storage according to claim 1, characterized in that: The heat pump system comprises an evaporation heat accumulator (14), a second compressor (15) and a condensation heat accumulator (16); the evaporation heat accumulator (14) is provided with a first cold storage heat exchange path and a second cold storage heat exchange path; the condensation heat accumulator (16) is provided with a first heat storage heat exchange path and a second heat storage heat exchange path; the first cold storage heat exchange path of the evaporation heat accumulator (14) and the second liquefaction heat exchange path of the liquefaction component (5) are connected in sequence to form a liquefaction circulation loop; the first heat storage heat exchange path of the condensation heat accumulator (16) and the second vaporization heat exchange path of the vaporization component (7) are connected in sequence to form a vaporization circulation loop; the second cold storage heat exchange path of the evaporation heat accumulator (14), the second compressor (15) and the second heat storage heat exchange path of the condensation heat accumulator (16) are connected in sequence to form a circulation loop.

3. The combined heat and power system coupling a heat pump and carbon dioxide energy storage according to claim 2, characterized in that: Phase change materials are stored in both the evaporation heat accumulator (14) and the condensation heat accumulator (16).

4. The combined heat and power system coupling a heat pump and carbon dioxide energy storage according to claim 2, characterized in that: A second throttle valve (17) is provided between the input end of the evaporation heat accumulator (14) and the output end of the condensation heat accumulator (16).

5. The combined heat and power system coupling a heat pump and carbon dioxide energy storage according to claim 2, characterized in that: The high-efficiency operating range of the second compressor (15) is (20)°C to (40)°C.

6. The combined heat and power system coupling a heat pump and carbon dioxide energy storage according to claim 1, characterized in that: The heat and power cogeneration system coupled with a heat pump and carbon dioxide energy storage further includes a heating unit (11); the heating unit (11) is connected in parallel between the two ends of the condensing heat accumulator (16).

7. The combined heat and power system coupling a heat pump and carbon dioxide energy storage according to claim 6, characterized in that: The heating unit (11) uses a heat exchanger connected to an external heating device.

8. The combined heat and power system coupling a heat pump and carbon dioxide energy storage according to claim 1, characterized in that: A first throttle valve (12) is provided between the low-pressure carbon dioxide storage tank (1) and the energy storage low-pressure heat exchange component (2); and an on-off valve (13) is provided between the low-pressure carbon dioxide storage tank (1) and the energy release low-pressure heat exchange component (10).

9. The combined heat and power system coupling a heat pump and carbon dioxide energy storage according to claim 1, characterized in that: The energy storage low-pressure heat exchange component (2), the energy storage high-pressure heat exchange component (4), the energy release high-pressure heat exchange component (8), and the energy release low-pressure heat exchange component (10) each include one or multiple heat exchangers connected in sequence.

10. The combined heat and power system coupling a heat pump and carbon dioxide energy storage according to claim 9, characterized in that: The energy storage low-pressure heat exchange assembly (2) corresponds to the heat exchanger in the energy release low-pressure heat exchange assembly (10) on a one-to-one basis, and a heat storage tank and a cold storage tank are connected in parallel between the two corresponding heat exchangers, and are connected to form a circulation loop through a heat exchange medium pipeline; the energy storage high-pressure heat exchange assembly (4) corresponds to the heat exchanger in the energy release high-pressure heat exchange assembly (8) on a one-to-one basis, and a heat storage tank and a cold storage tank are connected in parallel between the two corresponding heat exchangers, and are connected to form a circulation loop through a heat exchange medium pipeline.

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