A distributed energy storage system for combined cooling and heating and a method thereof

Abstract

The present invention belongs to the field of energy storage technology, and relates to a distributed energy storage system for combined cooling and heating and a method thereof, comprising an air compressor, an air turbine, a first heat exchanger, at least one water storage tank, a preheater; a heating heat exchanger, wherein the heating heat exchanger is connected to the user via a first circulation component, the first circulation component being used to transport the circulating medium to the heating heat exchanger in winter to exchange heat with the heat generated by the air compressor compressing the preheated air, and then transport the circulating medium to the user for heating. The present invention can store hot water in a water storage tank, making the system smaller and more compact, avoiding the need for a large-capacity gas storage device for storing high-pressure air, and improving the overall safety of the system. At the same time, the water storage tank is arranged underground, and the above-ground structure is further simplified, thereby realizing a small-scale distributed arrangement. In addition, by storing heat in summer and providing heating in winter, a single electrical energy output is avoided, thereby improving energy utilization efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage, and relates to a distributed energy storage system for combined cooling and heating and a method thereof. Background Art

[0002] The application of energy storage technology can effectively regulate the temporal and spatial distribution of electric energy in the power system, solve the problems of wind and solar power curtailment, reduce electricity costs, ensure stable and reliable output on the grid side, and at the same time assist in the absorption of renewable energy, promote the transformation of the energy structure, and improve energy utilization efficiency and system reliability.

[0003] At present, pumped storage, compressed air storage and electrochemical energy storage are commonly used in existing energy storage technologies. However, the above energy storage technologies have defects to varying degrees. First, pumped storage and compressed air storage are mainly suitable for large-scale energy storage, while electrochemical energy storage, although suitable for small-scale distributed storage, has problems such as poor safety. Second, existing energy storage technologies are mostly based on single power output and lack cogeneration capabilities, which reduces energy utilization efficiency. Summary of the Invention

[0004] The purpose of the present invention is to provide a distributed energy storage system for combined cooling and heating and a method thereof, which can perform small-scale distributed energy storage and heating at the same time, thereby improving not only the overall safety of the system but also the energy utilization efficiency.

[0005] To achieve the above objectives, the present invention provides the following technical solutions:

[0006] A distributed energy storage system for combined cooling and heating, comprising an air compressor and an air turbine, and further comprising:

[0007] a first heat exchanger, wherein the first inlet is connected to the first outlet of the air compressor, the first outlet of the first heat exchanger is connected to the first inlet of the air turbine, the second inlet of the first heat exchanger is connected to an external water source, and the first heat exchanger is used to heat water using heat generated by compressing air with the air compressor;

[0008] At least one water storage tank is disposed underground, the water storage tank is connected to the second outlet of the first heat exchanger, and the water storage tank is used to store heated water for energy storage;

[0009] a preheater, wherein a first inlet of the preheater is connected to the atmosphere, a first outlet of the preheater is connected to the inlet of the air compressor, and a second inlet of the preheater is connected to the outlet of the water storage tank, the preheater is used to preheat air by heated water, and then the preheated air is sent to the air compressor;

[0010] The heating heat exchanger has a first inlet connected to the second outlet of the air compressor, and the first outlet of the heating heat exchanger is connected to the second inlet of the air turbine. The heating heat exchanger is connected to the user through a first circulation component. The first circulation component is used to transport the circulating medium into the heating heat exchanger to exchange heat with the heat generated by the air compressor compressing the preheated air, and then transport the circulating medium to the user for heating.

[0011] The present invention is also characterized in that:

[0012] The air turbine is connected to a refrigeration heat exchanger, and the refrigeration heat exchanger is connected to the user through a second circulation component. The second circulation component is used to transport the circulating medium to the refrigeration heat exchanger in summer to exchange heat with the cold energy generated by the expansion work of the air turbine, and then transport the circulating medium to the user for cooling.

[0013] The water storage tank is set at a depth of 2.5m~3m underground.

[0014] The output shaft of the air turbine is connected to the input shaft of the air compressor.

[0015] A distributed energy storage method for combined cooling and heating comprises the following steps:

[0016] During cooling, hot air enters the air compressor for compression, and becomes high-temperature and high-pressure air after compression. The high-temperature and high-pressure air enters the first heat exchanger for heat exchange with normal-temperature water. The normal-temperature water becomes medium-temperature water and enters the water storage tank. The high-temperature and high-pressure air becomes medium-temperature and high-pressure air. The medium-temperature and high-pressure air enters the air turbine for expansion and work to become low-temperature and normal-pressure air. The low-temperature and normal-pressure air enters the refrigeration heat exchanger for heat exchange with the circulating medium delivered by the second circulation component. The circulating medium is then delivered to the user for cooling, and the low-temperature and normal-pressure air becomes normal-temperature and normal-pressure air and is discharged.

[0017] During heating, cold air enters the preheater and exchanges heat with the medium-temperature water in the water storage tank. The medium-temperature water becomes normal-temperature water and is discharged. The cold air becomes medium-temperature and normal-pressure air and enters the air compressor for compression. After compression, it becomes high-temperature and high-pressure air. The high-temperature and high-pressure air enters the heating heat exchanger and exchanges heat with the circulating medium delivered by the first circulation component. The circulating medium is then delivered to the user for heating. The high-temperature and high-pressure air becomes medium-temperature and high-pressure air. The medium-temperature and high-pressure air enters the air turbine for expansion and work, and the medium-temperature and high-pressure air becomes low-temperature and normal-pressure air and is discharged.

[0018] During cooling and heating, medium-temperature and high-pressure air enters the air turbine, expands, and the power generated is transmitted to the air compressor.

[0019] The temperature of medium-temperature water is 40℃~60℃, the temperature of high-temperature and high-pressure air is 170℃~200℃, and the pressure is 300kPa~400kPa, the temperature and pressure range of medium-temperature and high-pressure air is 60℃~80℃, and the pressure is 300kPa~400kPa, and the temperature of low-temperature and normal-pressure air is -15℃~-10℃, and the pressure is standard atmospheric pressure.

[0020] The distributed energy storage system for combined cooling and heating and the method thereof of the present invention have the following advantages:

[0021] First, through the cooperation of the air compressor, the air turbine, the first heat exchanger, at least one water storage tank, the preheater, the heating heat exchanger and the first circulation component, hot water can be stored in the water tank, making the system smaller and more compact, avoiding the need for a large-capacity gas storage device for storing high-pressure air, and improving the overall safety of the system. At the same time, the water tank is arranged underground, and the above-ground structure is further simplified, thereby realizing a small-scale distributed arrangement, which can be flexibly applied to various scenarios such as residential areas and hospitals. In addition, by storing heat in summer and heating in winter, a single electrical energy output is avoided, thereby improving energy utilization efficiency.

[0022] Second, the present invention shares a set of air compressors and air turbines in the heat storage cooling mode in summer and the heating mode in winter, which not only simplifies the system structure but also significantly reduces the system cost.

[0023] Third, the present invention can make full use of off-peak electricity. In summer, off-peak electricity can be used to store heat, and the stored heat can be used for heating in winter.

[0024] Fourth, the present invention can store heat and provide cooling for users in summer and heating for users in winter, realizing different functions in different seasons. Moreover, the water storage tank is buried underground, which has a good long-term thermal insulation effect, so that energy can be fully and efficiently utilized.

[0025] Fifth, through the setting of multiple control valves, the present invention can adjust the operating conditions of each link in real time according to the grid load, energy demand and energy storage status, and achieve precise control, which not only ensures the efficient operation of the system, but also improves the overall safety and stability.

[0026] Sixth, the present invention uses air from the atmosphere as the working medium and water as the heat storage medium. The operation of the entire system is clean and pollution-free, and the energy efficiency ratio can reach 2.6, further improving the energy utilization efficiency.

[0027] Seventh, the present invention adopts a modular design, which makes it have good scalability and transformation potential, and can flexibly expand or upgrade the system according to actual needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0029] Figure 2 It is a schematic diagram of the overall process structure of the present invention.

[0030] Reference numerals:

[0031] 1. Air compressor, 2. First heat exchanger, 3. Air turbine, 4. Refrigeration heat exchanger, 5. Water storage tank, 6. Preheater, 7. Heating heat exchanger, 8. First control valve, 9. Second control valve, 10. Third control valve, 11. Fourth control valve, 12. Fifth control valve, 13. Sixth control valve, 14. Seventh control valve, 15. Eighth control valve. DETAILED DESCRIPTION

[0032] The technical solutions in the present invention will be described clearly and in detail below with reference to the accompanying drawings. In the description of the embodiments of the present invention, unless otherwise specified, " / " means or, for example, A / B can mean A or B: "and / or" in the text is only a description of the association relationship of associated objects, indicating that there can be three relationships, such as A and / or B, which can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present invention, "multiple" refers to two or more than two. The following terms "first" and "second" are used for descriptive purposes only and cannot be understood as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0033] like Figure 1As shown, the present invention provides a distributed energy storage system for combined cooling and heating, including an air compressor 1, an air turbine 3, a first heat exchanger 2, at least one water storage tank 5, a preheater 6, a heating heat exchanger 7 and a first circulation component, the first inlet of the first heat exchanger 2 is connected to the first outlet of the air compressor 1, the first outlet of the first heat exchanger 2 is connected to the first inlet of the air turbine 3, the second inlet of the first heat exchanger 2 is connected to an external water source, the first heat exchanger 2 is used to heat water by the heat generated by compressing the air by the air compressor 1, the water storage tank 5 is set underground, the water storage tank 5 is connected to the second outlet of the first heat exchanger 2, the water storage tank 5 is used to store heated water for energy storage, the first inlet of the preheater 6 is connected to the atmosphere, the first outlet of the preheater 6 is connected to the inlet of the air compressor 1, the second inlet of the preheater 6 is connected to the outlet of the water storage tank 5, the preheater 6 is used to preheat the air with the heated water, and then the preheated air is sent to the air compressor 1, the first inlet of the heating heat exchanger 7 is connected to the air compressor 1 is connected to the second outlet of the heating heat exchanger 7, the first outlet of the heating heat exchanger 7 is connected to the second inlet of the air turbine 3, the heating heat exchanger 7 is connected to the user through the first circulation component, the first circulation component is used to transport the circulating medium to the heating heat exchanger 7 for heat exchange with the heat generated by the air compressor 1 compressing the preheated air, and then transport the circulating medium to the user for heating. The present invention cooperates with the air compressor 1, the air turbine 3, the first heat exchanger 2, at least one water storage tank 5, the preheater 6, the heating heat exchanger 7 and the first circulation component. It can store hot water in the water tank to make the system smaller and more compact, avoid the need for a large-capacity gas storage device for storing high-pressure air, and improve the overall safety of the system. At the same time, the water tank is arranged underground, and the ground structure is further simplified, thereby realizing a small-scale distributed arrangement, which can be flexibly applied to various scenarios such as residential areas and hospitals. In addition, through the form of heat storage in summer and heating in winter, a single electric energy output is avoided, and the energy utilization efficiency is improved.

[0034] like Figure 1 As shown, the air turbine 3 is connected to the refrigeration heat exchanger 4, and the refrigeration heat exchanger 4 is connected to the user through a second circulation component. The second circulation component is used to transport the circulating medium into the refrigeration heat exchanger 4 to exchange heat with the cold energy generated by the expansion work of the air turbine 3, and then transport the circulating medium to the user for cooling. It provides cooling while providing heat, further improving the energy utilization efficiency.

[0035] like Figure 1 As shown, the water storage tank 5 is set at a depth of 2.5m~3m underground.

[0036] like Figure 1 As shown, the output shaft of the air turbine 3 is connected to the input shaft of the air compressor 1, so that the power generated by the expansion work of the air turbine 3 can be delivered to the air compressor 1, providing part of the power for the air compressor 1 to reduce power consumption.

[0037] like Figure 1 As shown, the first inlet of the air compressor 1 is connected to the atmosphere, the first outlet of the air compressor 1 is connected to the first inlet of the first heat exchanger 2, the first outlet of the first heat exchanger 2 is connected to the first inlet of the air turbine 3, the second inlet of the first heat exchanger 2 is connected to the external water source, the second outlet of the first heat exchanger 2 is connected to the inlet of the water storage tank 5, the first inlet of the preheater 6 is connected to the atmosphere, the first outlet of the preheater 6 is connected to the second inlet of the air compressor 1, the second inlet of the preheater 6 is connected to the outlet of the water storage tank 5, the second outlet of the preheater 6 is connected to the atmosphere, the second outlet of the air compressor 1 is connected to the first inlet of the heating heat exchanger 7, the first outlet of the heating heat exchanger 7 is connected to the second inlet of the air turbine 3, the second inlet and second outlet of the heating heat exchanger 7 are respectively connected to the first circulation component, the first outlet of the air turbine 3 is connected to the first inlet of the refrigeration heat exchanger 4, the first outlet of the refrigeration heat exchanger 4 is connected to the atmosphere, and the second inlet and second outlet of the refrigeration heat exchanger 4 are respectively connected to the second circulation component.

[0038] like Figure 1 As shown, the first inlet of air compressor 1 is equipped with a first control valve 8, the first outlet of air compressor 1 is equipped with a second control valve 9, the first outlet of air turbine 3 is equipped with a third control valve 10, the second inlet of first heat exchanger 2 is equipped with a fourth control valve 11, the first inlet of preheater 6 is equipped with a fifth control valve 12, the second outlet of air compressor 1 is equipped with a sixth control valve 13, the second outlet of air turbine 3 is equipped with a seventh control valve 14, and the outlet of water storage tank 5 is equipped with an eighth control valve 15.

[0039] like Figure 2 As shown, the present invention also provides a distributed energy storage method for combined cooling and heating, comprising the following steps:

[0040] During cooling, external hot air enters the air compressor 1 for compression, and becomes high-temperature and high-pressure air after compression. The high-temperature and high-pressure air enters the first heat exchanger 2 for heat exchange with normal-temperature water. The normal-temperature water becomes medium-temperature water and enters the water storage tank 5. The high-temperature and high-pressure air becomes medium-temperature and high-pressure air. The medium-temperature and high-pressure air enters the air turbine 3 for expansion and work to become low-temperature and normal-pressure air. The low-temperature and normal-pressure air enters the refrigeration heat exchanger 4 for heat exchange with the circulating medium delivered by the second circulation component. The circulating medium is then delivered to users for cooling, and the low-temperature and normal-pressure air becomes normal-temperature and normal-pressure air and is discharged.

[0041] During heating in winter, cold air enters the preheater 6 and exchanges heat with the medium-temperature water in the water storage tank 5. The medium-temperature water becomes normal-temperature water and is discharged. The cold air becomes medium-temperature and normal-pressure air and enters the air compressor 1 for compression. After compression, it becomes high-temperature and high-pressure air. The high-temperature and high-pressure air enters the heating heat exchanger 7 and exchanges heat with the circulating medium delivered by the first circulation component. The circulating medium is then delivered to the user for heating. The high-temperature and high-pressure air becomes medium-temperature and high-pressure air. The medium-temperature and high-pressure air enters the air turbine 3 to expand and do work, and the medium-temperature and high-pressure air becomes low-temperature and normal-pressure air and is discharged.

[0042] During cooling and heating, medium-temperature and high-pressure air enters the air turbine 3 for expansion and work, and the power generated is transmitted to the air compressor 1.

[0043] Among them, the temperature of hot air is 25℃~30℃, the temperature of cold air is -5℃~0℃, the temperature of medium-temperature water is 40℃~60℃, the temperature of high-temperature and high-pressure air is 170℃~200℃ and the pressure is 300kPa~400kPa, the temperature and pressure range of medium-temperature and high-pressure air is 60℃~80℃ and the pressure is 300kPa~400kPa, the temperature of low-temperature and normal-pressure air is -15℃~-10℃ and the pressure is standard atmospheric pressure.

[0044] Working principle:

[0045] In the initial state, the first control valve 8 to the eighth control valve 15 are closed, and the device is in a shutdown state.

[0046] During summer, the fifth, sixth, seventh, and eighth control valves 12, 13, 14, and 15 are closed, and the first, second, third, and fourth control valves 8, 9, 10, and 11 are opened. The system enters summer heat storage and cooling mode. Off-peak electricity is used to power compressor 1. Hot air enters compressor 1 through first control valve 8 for compression, producing high-temperature, high-pressure air. This high-temperature, high-pressure air then enters heat exchanger 2 through second control valve 9. Normal-temperature water enters heat exchanger 2 through fourth control valve 11, where it undergoes heat exchange with the high-temperature, high-pressure air. After absorbing heat, the normal-temperature water becomes medium-temperature water and enters water storage tank 5 for storage. The high-temperature, high-pressure air then becomes medium-temperature, high-pressure air and enters air turbine 3 for expansion, generating work. This provides partial power for the air compressor and reduces power consumption. The medium-temperature, high-pressure air then becomes low-temperature, normal-pressure air. This low-temperature, normal-pressure air then enters refrigeration heat exchanger 4 through third control valve 10, where it absorbs heat and rises in temperature, providing cooling for the user. After heat exchange, the low-temperature, normal-pressure air becomes normal-temperature, normal-pressure air and is discharged into the atmosphere.

[0047] When it is winter, the first control valve 8, the second control valve 9, the third control valve 10, and the fourth control valve 11 are closed, and the fifth control valve 12, the sixth control valve 13, the seventh control valve 14, and the eighth control valve 15 are opened. The system is in winter heating mode, and the cold air enters the preheater 6 through the fifth control valve 12, and the medium-temperature water stored in the underground water tank 5 enters the preheater 6 through the eighth control valve 15 to provide heat for the cold air. The medium-temperature water is discharged after dissipating heat and cooling in the preheater 6. After preheating, the cold air becomes medium-temperature and normal-pressure air and is introduced into the air compressor 1 for compression to obtain high-temperature and high-pressure air. The high-temperature and high-pressure air enters the heating heat exchanger 7 through the sixth control valve 13 to dissipate heat and cool down to provide heating for users. After cooling, the high-temperature and high-pressure air becomes medium-temperature and high-pressure air and expands through the air turbine 3 to do work, providing part of the power for the air compressor and reducing power consumption. The medium-temperature and high-pressure air becomes low-temperature and normal-pressure air and is directly discharged into the atmosphere through the seventh control valve 14.

[0048] It will be understood that the present invention is described by way of some embodiments, and it will be appreciated by those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present invention are intended to be protected by the present invention.

Claims

1. A distributed energy storage system for combined cooling and heating, comprising an air compressor (1) and an air turbine (3), characterized in that: Also includes: a first heat exchanger (2), wherein a first inlet is connected to a first outlet of an air compressor (1), a first outlet of the first heat exchanger (2) is connected to a first inlet of an air turbine (3), a second inlet of the first heat exchanger (2) is connected to an external water source, and the first heat exchanger (2) is used to heat water by heat generated by air compressed by the air compressor (1); At least one water storage tank (5) is arranged underground, the water storage tank (5) is connected to the second outlet of the first heat exchanger (2), and the water storage tank (5) is used to store heated water for energy storage; A preheater (6) has a first inlet connected to the atmosphere, a first outlet connected to the inlet of the air compressor (1), and a second inlet connected to the outlet of the water storage tank (5). The preheater (6) is used to preheat air using heated water, and the preheated air is then fed into the air compressor (1); A heating heat exchanger (7), wherein a first inlet is connected to a second outlet of an air compressor (1), and a first outlet of the heating heat exchanger (7) is connected to a second inlet of an air turbine (3). The heating heat exchanger (7) is connected to a user via a first circulation component, and the first circulation component is used to transport a circulating medium into the heating heat exchanger (7) to exchange heat with heat generated by compressing preheated air in the air compressor (1), and then transport the circulating medium to the user for heating; The air turbine (3) is connected to a refrigeration heat exchanger (4), and the refrigeration heat exchanger (4) is connected to the user via a second circulation component. The second circulation component is used to transport the circulating medium into the refrigeration heat exchanger (4) to exchange heat with the cold energy generated by the expansion work of the air turbine (3), and then transport the circulating medium to the user for cooling; The water storage tank (5) is arranged underground at a depth of 2.5m to 3m.

2. A distributed energy storage system for combined cooling and heating according to claim 1, characterized in that: The output shaft of the air turbine (3) is connected to the input shaft of the air compressor (1).

3. A distributed energy storage method for combined cooling and heating, characterized in that: The system according to claim 1 comprises the following steps: During cooling, hot air enters the air compressor (1) for compression, and becomes high-temperature and high-pressure air after compression. The high-temperature and high-pressure air enters the first heat exchanger (2) for heat exchange with normal-temperature water. The normal-temperature water becomes medium-temperature water and enters the water storage tank (5). The high-temperature and high-pressure air becomes medium-temperature and high-pressure air. The medium-temperature and high-pressure air enters the air turbine (3) for expansion and work to become low-temperature and normal-pressure air. The low-temperature and normal-pressure air enters the refrigeration heat exchanger (4) for heat exchange with the circulating medium delivered by the second circulation component. The circulating medium is then delivered to the user for cooling, and the low-temperature and normal-pressure air becomes normal-temperature and normal-pressure air and is discharged. During heating, cold air enters the preheater (6) and exchanges heat with the medium-temperature water in the water storage tank (5). The medium-temperature water becomes normal-temperature water and is discharged. The cold air becomes medium-temperature and normal-pressure air and enters the air compressor (1) for compression. After compression, it becomes high-temperature and high-pressure air. The high-temperature and high-pressure air enters the heating heat exchanger (7) and exchanges heat with the circulating medium delivered by the first circulation component. The circulating medium is then delivered to the user for heating. The high-temperature and high-pressure air becomes medium-temperature and high-pressure air. The medium-temperature and high-pressure air enters the air turbine (3) for expansion and work, and the medium-temperature and high-pressure air becomes low-temperature and normal-pressure air and is discharged.

4. A distributed energy storage method for combined cooling and heating according to claim 3, characterized in that: During cooling and heating, medium-temperature and high-pressure air enters the air turbine (3) and expands to generate power which is then transferred to the air compressor (1).

5. A distributed energy storage method for combined cooling and heating according to claim 3, characterized in that: The temperature of the medium-temperature water is 40℃~60℃, the temperature of the high-temperature and high-pressure air is 170℃~200℃, and the pressure is 300kPa~400kPa, the temperature of the medium-temperature and high-pressure air is 60℃~80℃, and the pressure is 300kPa~400kPa, and the temperature of the low-temperature and normal-pressure air is -15℃~-10℃, and the pressure is standard atmospheric pressure.

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