Multi-stage heat storage carbon dioxide adsorption and compression energy storage system and operation method

Abstract

The invention provides a multi-stage heat storage carbon dioxide adsorption and compression energy storage system and an operation method, and belongs to the field of compressed carbon dioxide energy storage. The invention aims to solve the problems of low gas storage density and high energy consumption in compressed carbon dioxide energy storage in the prior art. The system comprises a low-pressure gas storage unit, a compression unit, an expansion unit and a waste heat utilization unit, a first hot tank and a first cold tank in the low-pressure gas storage unit are connected with a low-pressure adsorption storage tank through a heat exchanger; the compression unit comprises three compressors and three coolers for compressing CO2 to a high-pressure state; the expansion unit comprises three expansion machines and three heaters which are used for converting high-pressure CO2 energy into energy in other forms; the waste heat utilization unit comprises a second hot tank, a second cold tank, a third hot tank and a waste heat utilization device, and final-stage compression heat can be reasonably utilized. The mode of combining temperature swing adsorption and heat storage is adopted, high-density storage of low-pressure CO2 can be achieved without introduction of external heat, and high efficiency and energy conservation are achieved.

Description

Technical Field

[0001] The present invention relates to the field of compressed carbon dioxide energy storage, and particularly to an adsorption compressed carbon dioxide energy storage system with multi-stage heat storage and an operation method thereof. Background Art

[0002] In recent years, the global energy structure has been undergoing profound changes. Renewable energy has achieved rapid development due to its clean and sustainable advantages. The matching energy storage technology, as a key support for ensuring the stable access and efficient utilization of renewable energy, has become a crucial part of the national energy strategic layout.

[0003] Among various energy storage technologies, compressed gas energy storage technology has shown strong development potential and has developed rapidly due to its significant advantages such as large capacity, long cycle life, and fast response speed. Among them, compressed air energy storage technology, as a relatively mature branch, has successfully entered the commercial application stage, providing a feasible solution for large-scale energy storage.

[0004] At the same time, compressed carbon dioxide energy storage technology has gradually emerged and become a research hotspot in the energy storage field. This is because the critical point of carbon dioxide (7.39 MPa, 31.4 °C) is easier to reach compared to air (3.77 MPa, -140.5 °C), making the operation of carbon dioxide in the energy storage system more convenient. In addition, carbon dioxide in the supercritical state has excellent thermodynamic properties, such as low viscosity, high density, good thermal conductivity, etc., and also has the characteristics of non-toxic and non-flammable. It is a very potential energy storage working medium. Using carbon dioxide as the energy storage working medium can significantly improve the energy storage density and operation efficiency of the energy storage system, opening up a new path for the development of energy storage technology.

[0005] Compressed carbon dioxide energy storage systems usually adopt a closed cycle. In this system, gas storage operations are required on both the high-pressure side and the low-pressure side, and the choice of gas storage form is directly related to the feasibility and economy of the entire system. Currently, common gas storage methods include atmospheric gaseous, liquid, and solid adsorption, etc. However, these gas storage methods all have certain limitations: The atmospheric gaseous gas storage method is simple to operate, but has a low storage density and requires a large amount of space; The liquid gas storage method has a relatively high storage density, but has high energy consumption, increasing the operating cost; The adsorption gas storage method can achieve a relatively high gas storage density, but requires the introduction of a high-temperature heat source, which to a certain extent limits the expansion of its application scenarios.

[0006] In addition, in some compressed carbon dioxide energy storage systems, the waste heat generated at the end stage of the compressor is not fully and effectively utilized, resulting in energy waste and further reducing the overall efficiency of the system.

[0007] In summary, there are still many problems to be solved urgently in the existing compressed carbon dioxide energy storage technology in aspects such as gas storage method and waste heat utilization. There is an urgent need for further improvement and innovation to promote its development towards a more efficient, economical and practical direction. Summary of the Invention

[0008] A brief overview of the present invention is given below in order to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to identify the key or important parts of the present invention, nor is it intended to limit the scope of the present invention. Its purpose is only to present certain concepts in a simplified form as a prelude to the more detailed description to be discussed later.

[0009] In view of this, in order to solve the problems of low gas storage density and high energy consumption in compressed carbon dioxide energy storage in the prior art, the present invention provides a multi-stage heat storage adsorption compressed carbon dioxide energy storage system and an operation method.

[0010] Solution 1: A multi-stage heat storage adsorption compressed carbon dioxide energy storage system, comprising a low-pressure gas storage unit, a compression unit, an expansion unit, a waste heat utilization unit and a high-pressure storage tank;

[0011] The low-pressure gas storage unit includes a first hot tank, a first cold tank, a heat exchanger and a low-pressure adsorption storage tank. The first hot tank and the first cold tank are connected to the low-pressure adsorption storage tank through the heat exchanger;

[0012] The compression unit includes a first compressor, a second compressor, a third compressor, a first cooler, a second cooler and a third cooler; the first compressor, the first cooler, the second compressor, the second cooler, the third compressor and the third cooler are connected in sequence; the inlet end of the first compressor is connected to the low-pressure adsorption storage tank, and the outlet end of the third cooler is connected to the high-pressure storage tank;

[0013] The expansion unit includes a first heater, a second heater, a third heater, a first expander, a second expander and a third expander; the first heater, the first expander, the second heater, the second expander, the third heater and the third expander are connected in sequence; the outlet end of the high-pressure storage tank is connected to the first heater, and the outlet end of the third expander is connected to the low-pressure adsorption storage tank;

[0014] The waste heat utilization unit includes a second hot tank, a second cold tank, a third hot tank, and a waste heat utilization device; the inlet end of the second hot tank is connected to the first cooler and the second cooler, and the outlet end of the second hot tank is connected to the first heater, the second heater, and the third heater; the inlet end of the second cold tank is connected to the first heater, the second heater, the third heater, and the waste heat utilization device, and the outlet end of the second cold tank is connected to the first cooler, the second cooler, and the third cooler; the inlet end of the third hot tank is connected to the third cooler, and the outlet end is connected to the waste heat utilization device.

[0015] Further, the first compressor, the second compressor, the second expander, and the third expander operate at a constant pressure, and the outlet temperatures of the first compressor and the second compressor are equal.

[0016] Further, the third compressor and the first expander operate at a sliding pressure, and the outlet pressure of the third compressor and the inlet pressure of the first expander vary with the pressure of the high-pressure storage tank.

[0017] Solution 2. An operation method of a multi-stage heat storage adsorption compression carbon dioxide energy storage system specifically includes the following steps:

[0018] S1. At the beginning of the energy storage stage, a desorption process occurs in the low-pressure adsorption storage tank. The heat storage medium flows from the first hot tank through the heat exchanger to the first cold tank. After the adsorbent in the low-pressure adsorption storage tank absorbs the heat from the first hot tank, CO 2 gas desorbs from the adsorbent, and low-pressure CO 2 working medium is released from the low-pressure adsorption storage tank and flows to the compression unit;

[0019] S2. The low-pressure CO 2 working medium enters the compression unit, and CO 2 successively passes through the first compressor, the first cooler, the second compressor, the second cooler, the third compressor, and the third cooler and then enters the high-pressure storage tank. The compression heat of the first compressor and the second compressor is stored in the second hot tank, and the compression heat of the third compressor is stored in the third hot tank;

[0020] S3. As the CO 2 gas is filled, the pressure in the high-pressure storage tank gradually increases, and the energy storage process ends when the target pressure is reached;

[0021] S4. At the beginning of the energy release stage, the high-pressure storage tank slowly releases the CO 2 working medium into the expansion unit, and the pressure in the high-pressure storage tank gradually decreases;

[0022] S5. The CO 2 working medium successively passes through the first heater, the first expander, the second heater, the second expander, the third heater, and the third expander to perform expansion work, and CO 2The working fluid enters the low-pressure adsorption storage tank after passing through the third expansion machine. The compressed heat stored in the second hot tank provides heat for the first heater, the second heater, and the third heater, increasing the temperature of the working fluid at the inlet ends of the first expansion machine, the second expansion machine, and the third expansion machine; 2 The temperature of the working fluid;

[0023] S6.CO 2 After the working fluid enters the low-pressure adsorption storage tank, the adsorption process begins. After the heat storage medium enters the first hot tank from the first cold tank through the heat exchanger, the energy release stage ends;

[0024] S7. The compressed heat stored in the third hot tank can be used for local heat supplementation within the system or supplied to the living area through the waste heat utilization device.

[0025] Furthermore, the outlet temperature ranges of the first compressor and the second compressor are 150 - 250 °C, and the corresponding temperature of the second hot tank is 130 - 230 °C; the outlet temperature range of the third compressor is 70 - 150 °C, and the corresponding temperature of the third hot tank is 60 - 100 °C; the temperature of the second cold tank is 40 - 50 °C.

[0026] Furthermore, the working pressure range of the high-pressure storage tank is 6.5 - 15 MPa.

[0027] The present invention has the following beneficial effects compared with the prior art:

[0028] 1. The present invention adopts the combination of variable-temperature adsorption and heat storage, realizing the heat self-sustainment of the adsorbent adsorption and desorption process. Without introducing external heat, high-density storage of low-pressure CO can be achieved, which is both efficient and energy-saving; 2 The high-density storage of CO is both efficient and energy-saving;

[0029] 2. In the present invention, hierarchical heat storage is carried out according to the operating temperature, reducing heat transfer losses while improving the system flexibility, effectively utilizing the final-stage compressed heat, and improving the overall heat utilization efficiency of the energy storage system;

[0030] 3. The present invention has a wide range of applicable scenarios, does not require special geographical conditions, can be used for energy storage matching of new energy such as wind and light, and can also be used in independent energy storage scenarios;

[0031] 4. The present invention can achieve combined heat and power generation, not only having an energy storage function, but also providing hot water or heating water required for the life of the plant where the system is located. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0033] Figure 1It is a schematic diagram of an adsorption compression carbon dioxide energy storage system with multi-stage heat storage.

[0034] In the figure: 1 - First heat storage tank, 2 - First cold storage tank, 3 - Heat exchanger, 4 - Low-pressure adsorption storage tank, 5 - First compressor, 6 - Second compressor, 7 - Third compressor, 8 - First cooler, 9 - Second cooler, 10 - Third cooler, 11 - High-pressure storage tank, 12 - Second heat storage tank, 13 - Second cold storage tank, 14 - Third heat storage tank, 15 - Waste heat utilization device, 16 - First heater, 17 - Second heater, 18 - Third heater, 19 - First expander, 20 - Second expander, 21 - Third expander. Specific implementation mode

[0035] In order to make the technical solutions and advantages in the embodiments of the present invention clearer and more understandable, the following further details the exemplary embodiments of the present invention with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than an exhaustive list of all embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0036] Example 1. Refer to Figure 1 This embodiment is described. An adsorption compression carbon dioxide energy storage system with multi-stage heat storage includes a low-pressure gas storage unit, a compression unit, an expansion unit, a waste heat utilization unit, and a high-pressure storage tank 11;

[0037] The low-pressure gas storage unit includes a first heat storage tank 1, a first cold storage tank 2, a heat exchanger 3, and a low-pressure adsorption storage tank 4. The first heat storage tank 1 and the first cold storage tank 2 are connected to the low-pressure adsorption storage tank 4 through the heat exchanger 3;

[0038] The compression unit includes a first compressor 5, a second compressor 6, a third compressor 7, a first cooler 8, a second cooler 9, and a third cooler 10. The first compressor 5, the first cooler 8, the second compressor 6, the second cooler 9, the third compressor 7, and the third cooler 10 are connected in sequence. The inlet end of the first compressor 5 is connected to the low-pressure adsorption storage tank 4, and the outlet end of the third cooler 10 is connected to the high-pressure storage tank 11;

[0039] The expansion unit includes a first heater 16, a second heater 17, a third heater 18, a first expander 19, a second expander 20, and a third expander 21. The first heater 16, the first expander 19, the second heater 17, the second expander 20, the third heater 18, and the third expander 21 are connected in sequence. The outlet end of the high-pressure storage tank 11 is connected to the first heater 16, and the outlet end of the third expander 21 is connected to the low-pressure adsorption storage tank 4;

[0040] The waste heat utilization unit includes a second hot tank 12, a second cold tank 13, a third hot tank 14, and a waste heat utilization device 15; the inlet end of the second hot tank 12 is connected to the first cooler 8 and the second cooler 9, and the outlet end of the second hot tank 12 is connected to the first heater 16, the second heater 17, and the third heater 18; the inlet end of the second cold tank 13 is connected to the first heater 16, the second heater 17, the third heater 18, and the waste heat utilization device 15, and the outlet end of the second cold tank 13 is connected to the first cooler 8, the second cooler 9, and the third cooler 10; the inlet end of the third hot tank 14 is connected to the third cooler 10, and the outlet end is connected to the waste heat utilization device 15.

[0041] Further, the first compressor 5, the second compressor 6, the second expander 20, and the third expander 21 operate at a constant pressure, and the outlet temperatures of the first compressor 5 and the second compressor 6 are equal.

[0042] Further, the third compressor 7 and the first expander 19 operate at a sliding pressure, and the outlet pressure of the third compressor 7 and the inlet pressure of the first expander 19 change with the pressure of the high-pressure storage tank 11.

[0043] Embodiment 2. A method for operating a multi-stage heat storage adsorption compression carbon dioxide energy storage system specifically includes the following steps:

[0044] S1. At the beginning of the energy storage stage, the desorption process occurs in the low-pressure adsorption storage tank 4, and the heat storage medium flows from the first hot tank 1 through the heat exchanger 3 to the first cold tank 2. After the adsorbent in the low-pressure adsorption storage tank 4 absorbs the heat from the first hot tank 1, CO 2 gas desorbs from the adsorbent, and low-pressure CO 2 working medium is released from the low-pressure adsorption storage tank 4 and flows to the compression unit;

[0045] S2. The low-pressure CO 2 working medium enters the compression unit, and CO 2 successively passes through the first compressor 5, the first cooler 8, the second compressor 6, the second cooler 9, the third compressor 7, and the third cooler 10 and then enters the high-pressure storage tank 11. The compression heat of the first compressor 5 and the second compressor 6 is stored in the second hot tank 12, and the compression heat of the third compressor 7 is stored in the third hot tank 14;

[0046] S3. As the CO 2 gas is filled, the pressure in the high-pressure storage tank 11 gradually increases, and the energy storage process ends when the target pressure is reached;

[0047] S4. At the beginning of the energy release stage, the high-pressure storage tank 11 slowly releases CO 2 working medium into the expansion unit, and the pressure in the high-pressure storage tank 11 gradually decreases;

[0048] S5. CO2 The working fluid successively passes through the first heater 16, the first expander 19, the second heater 17, the second expander 20, the third heater 18 and the third expander 21 to perform expansion work, and CO 2 After the working fluid passes through the third expander 21, it enters the low-pressure adsorption storage tank 4. The compressed heat stored in the second hot tank 12 provides heat for the first heater 16, the second heater 17, and the third heater 18, and increases the CO at the inlet ends of the first expander 19, the second expander 20, and the third expander 21 2 working fluid temperature;

[0049] S6.CO 2 After the working fluid enters the low-pressure adsorption storage tank 4, the adsorption process starts. After the heat storage medium enters the first hot tank 1 from the first cold tank 2 through the heat exchanger 3, the energy release stage ends;

[0050] S7. The compressed heat stored in the third hot tank 14 can be used for local heat compensation in the system or supplied to the living area through the waste heat utilization device 15.

[0051] Furthermore, the outlet temperature range of the first compressor 5 and the second compressor 6 is 150 - 250 °C, and the corresponding temperature of the second hot tank 12 is 130 - 230 °C; the outlet temperature range of the third compressor 7 is 70 - 150 °C, and the corresponding temperature of the third hot tank 14 is 60 - 100 °C; the temperature of the second cold tank 13 is 40 - 50 °C.

[0052] Furthermore, the working pressure range of the high-pressure storage tank 11 is 6.5 - 15 MPa.

[0053] Through the form of combining variable-temperature adsorption and heat storage adopted in the present invention, the heat self-sustainment of the adsorbent adsorption and desorption process is realized. Without introducing external heat, high-density storage of low-pressure CO can be achieved 2 which is both efficient and energy-saving; heat is stored in stages according to the operating temperature, reducing heat transfer losses while improving the system flexibility, effectively utilizing the final-stage compressed heat, and improving the overall heat utilization efficiency of the energy storage system;

[0054] Through the present invention, combined heat and power generation can be realized. It not only has an energy storage function, but also can provide hot water or heating water required for the life of the plant where the system is located; the present invention has a wide range of application scenarios, does not require special geographical conditions, can be used for energy storage matching of new energy such as wind and light, and can also be used for independent energy storage scenarios.

[0055] Although the present invention has been described in terms of a limited number of embodiments, those skilled in the art, having the benefit of the foregoing description, will appreciate that other embodiments can be contemplated within the scope of the invention as thus described. In addition, it should be noted that the language used in this specification has been principally selected for readability and instructional purposes and not to limit or define the inventive subject matter. Accordingly, many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the appended claims. For the scope of the present invention, the disclosure herein is illustrative and not restrictive, and the scope of the invention is defined by the appended claims.

Claims

1. A multi-stage heat storage adsorption compressed carbon dioxide energy storage system, characterized in that: It comprises a low-pressure gas storage unit, a compression unit, an expansion unit, a waste heat utilization unit and a high-pressure storage tank (11); The low-pressure gas storage unit comprises a first hot tank (1), a first cold tank (2), a heat exchanger (3), and a low-pressure adsorption storage tank (4); the first hot tank (1) and the first cold tank (2) are connected to the low-pressure adsorption storage tank (4) via the heat exchanger (3); The compression unit comprises a first compressor (5), a second compressor (6), a third compressor (7), a first cooler (8), a second cooler (9) and a third cooler (10); the first compressor (5), the first cooler (8), the second compressor (6), the second cooler (9), the third compressor (7) and the third cooler (10) are connected in sequence; the inlet end of the first compressor (5) is connected to the low-pressure adsorption storage tank (4), and the outlet end of the third cooler (10) is connected to the high-pressure storage tank (11); The expansion unit comprises a first heater (16), a second heater (17), a third heater (18), a first expander (19), a second expander (20) and a third expander (21); the first heater (16), the first expander (19), the second heater (17), the second expander (20), the third heater (18) and the third expander (21) are connected in sequence; the outlet end of the high-pressure storage tank (11) is connected to the first heater (16), and the outlet end of the third expander (21) is connected to the low-pressure adsorption storage tank (4); The waste heat utilization unit comprises a second hot tank (12), a second cold tank (13), a third hot tank (14) and a waste heat utilization device (15); the inlet end of the second hot tank (12) is connected to the first cooler (8) and the second cooler (9), and the outlet end of the second hot tank (12) is connected to the first heater (16), the second heater (17) and the third heater (18); the inlet end of the second cold tank (13) is connected to the first heater (16), the second heater (17), the third heater (18) and the waste heat utilization device (15), and the outlet end of the second cold tank (13) is connected to the first cooler (8), the second cooler (9) and the third cooler (10); the inlet end of the third hot tank (14) is connected to the third cooler (10), and the outlet end is connected to the waste heat utilization device (15).

2. The multi-stage heat storage adsorption compressed carbon dioxide energy storage system according to claim 1, characterized in that: The first compressor (5), the second compressor (6), the second expander (20) and the third expander (21) are operated at a constant pressure, and the outlet temperatures of the first compressor (5) and the second compressor (6) are equal.

3. The multi-stage heat storage adsorption compressed carbon dioxide energy storage system according to claim 1, characterized in that: The third compressor (7) and the first expander (19) are in sliding pressure operation, and the outlet pressure of the third compressor (7) and the inlet pressure of the first expander (19) vary with the pressure of the high-pressure storage tank (11).

4. An operating method of a multi-stage heat storage adsorption compression carbon dioxide energy storage system, characterized in that: The specific steps include: S1. At the beginning of the energy storage stage, a desorption process is carried out in the low-pressure adsorption storage tank (4), and the heat storage medium flows from the first hot tank (1) to the first cold tank (2) via the heat exchanger (3). After the adsorbent in the low-pressure adsorption storage tank (4) absorbs the heat from the first hot tank (1), the CO2 gas is desorbed from the adsorbent, and the low-pressure CO2 working medium is released from the low-pressure adsorption storage tank (4) and flows to the compression unit; S2. The low-pressure CO2 working medium enters the compression unit, and the CO2 passes through the first compressor (5), the first cooler (8), the second compressor (6), the second cooler (9), the third compressor (7) and the third cooler (10) in sequence before entering the high-pressure storage tank (11). The compression heat of the first compressor (5) and the second compressor (6) is stored in the second heat tank (12), and the compression heat of the third compressor (7) is stored in the third heat tank (14); S3. As CO2 gas is charged, the pressure in the high-pressure storage tank (11) gradually increases, and the energy storage process ends when the target pressure is reached; S4. At the beginning of the energy release phase, the high-pressure storage tank (11) slowly releases the CO2 working fluid into the expansion unit, and the pressure in the high-pressure storage tank (11) gradually decreases; S5. The CO2 working medium is sequentially passed through the first heater (16), the first expander (19), the second heater (17), the second expander (20), the third heater (18) and the third expander (21) to expand and perform work. The CO2 working medium enters the low-pressure adsorption storage tank (4) after passing through the third expander (21). The compression heat stored in the second heat tank (12) provides heat for the first heater (16), the second heater (17) and the third heater (18), thereby increasing the CO2 working medium temperature at the inlet end of the first expander (19), the second expander (20) and the third expander (21); S6. After the CO2 working fluid enters the low-pressure adsorption storage tank (4), the adsorption process begins. After the heat storage medium enters the first hot tank (1) from the first cold tank (2) through the heat exchanger (3), the energy release stage ends; S7. The compression heat stored in the third heat tank (14) can be used for local heat supplementation in the system or for supplying living areas via the waste heat utilization device (15).

5. The operating method of the multi-stage heat storage adsorption compression carbon dioxide energy storage system according to claim 4 is characterized in that: The outlet temperature range of the first compressor (5) and the second compressor (6) is 150-250°C, corresponding to the temperature of the second hot tank (12) of 130-230°C; the outlet temperature range of the third compressor (7) is 70-150°C, corresponding to the temperature of the third hot tank (14) of 60-100°C; the temperature of the second cold tank (13) is 40-50°C.

6. The operating method of the multi-stage heat storage adsorption compression carbon dioxide energy storage system according to claim 4 is characterized in that: The working pressure range of the high-pressure storage tank (11) is 6.5-15 MPa.

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