A peak shaving heat supply system based on CO2 temperature swing pressure swing adsorption coupling and an operation method thereof

Abstract

The application discloses a CO2 variable-temperature and variable-pressure adsorption coupled peak regulation and heat supply system and an operation method thereof, relates to the technical field of CO2 energy storage and combined heat and power, and discloses the following technical scheme: a low-pressure adsorption heat storage unit adopts a parallel structure of a low-pressure adsorption heat storage tower group and is internally filled with heat-resistant CO2 adsorbents, stores heat energy and performs variable-temperature adsorption of CO2 in a cycle; a high-pressure adsorption pressure storage unit adopts a high-pressure adsorption pressure storage tower and is internally filled with pressure-resistant CO2 adsorbents, stores pressure potential energy and performs variable-pressure adsorption of CO2 in a cycle; a compression and work unit comprises a compressor, a compression heat exchanger, a variable-pressure adsorption storage and release heat exchanger, an expander, a regenerator and a power grid port; a heat storage and supply circuit comprises a heat storage heat pump, a heat release heat pump, a heat supply connection switch and a heat network port, and a heat conduction medium is arranged in the heat storage and supply circuit. The application deeply combines CO2 storage technology and peak regulation and heat supply, realizes efficient peak regulation and flexible heat supply, simultaneously simplifies the system structure and improves the economic efficiency of system operation.

Description

Technical Field

[0001] This invention relates to the field of CO2 energy storage and combined heat and power technology, specifically a peak-shaving heating system based on CO2 temperature and pressure swing adsorption coupling and its operation method. Background Technology

[0002] my country is currently at a critical stage of energy transition. As the proportion of renewable energy generation, such as photovoltaic and wind power, continues to increase, the inherent instability of renewable energy poses an increasingly strong challenge to grid stability, and the demand for grid peak shaving is becoming increasingly prominent. Energy storage technology refers to a technical system that stores one or more forms of energy through specific media or equipment, and releases it when needed, converting it into the required form such as electricity for utilization. It is a core technology for solving the problem of energy allocation across time, such as grid peak shaving.

[0003] Energy storage technologies include physical energy storage, chemical energy storage, electrochemical energy storage, and molten salt thermal energy storage, among which only pumped hydro storage and compressed gas energy storage are physical energy storage technologies that can be applied on a large scale. Pumped hydro storage requires a high elevation difference and has a strong geographical dependence, making it difficult to apply widely. In contrast, compressed gas energy storage only requires a high-pressure gas storage space, has a wide range of applications, and is not limited by geographical location, making it the best energy storage method for solving large-scale peak-shaving problems at present.

[0004] Compressed gas energy storage utilizes surplus electricity during off-peak hours to drive compressed gas and store it under high pressure in a sealed storage space. During peak hours, the high-pressure gas is released to drive a turbine and generate electricity, thus achieving peak shaving for the power grid. Conventional compressed gas energy storage typically uses air as the storage medium, employing pressure-resistant gas tanks or natural underground caves as storage spaces. However, the air density on the low-pressure side is extremely low, resulting in a large volume of gas required for peak shaving and extremely high system construction and maintenance costs. Addressing the significant shortcomings of compressed air energy storage, adsorption-compressed CO2 energy storage technology (such as CN115075900B and CN115306500B) leverages the adsorption properties of CO2, utilizing porous adsorbents to achieve high-density storage of low-pressure CO2, improving energy storage efficiency and density, while also enabling the sequestration and utilization of greenhouse gases.

[0005] Furthermore, compressed gas energy storage generates significant heat of compression, posing a core challenge to thermal energy storage and utilization. Traditional compressed gas energy storage employs insulated storage tanks and thermal storage materials as storage units for heat storage and release. This approach significantly increases system complexity and construction and maintenance costs, resulting in poor economic efficiency. Adsorption-compressed CO2 energy storage systems utilize a "generate-as-you-go" approach, using the heat of compression stored during off-peak electricity demand to supply the desorption heat of CO2 in the low-pressure adsorption zone and supplying the waste heat to the heating network. However, the reality is that there is a complex mismatch between thermal energy and electricity supply and demand. This approach, based solely on grid peak-shaving needs, fails to adequately consider the supply and demand relationship of the heating network, leading to insufficient heating flexibility.

[0006] In summary, coordinating the flexibility and economy of thermal energy utilization and enhancing the system's peak-shaving capability are the directions for improving existing compressed gas energy storage cogeneration and power generation technologies. Summary of the Invention

[0007] To address the shortcomings of existing compressed gas energy storage technologies, such as difficulty in balancing the flexibility and economy of thermal energy utilization, insufficient system peak-shaving capacity, poor adjustability of heating quality, and high energy consumption of adsorbent adsorption and desorption, this invention provides a peak-shaving heating system and its operation method based on CO2 temperature and pressure swing adsorption coupling. It deeply integrates CO2 storage technology with peak-shaving heating to achieve efficient peak-shaving and flexible heating, while simplifying the system structure and improving the economic efficiency of system operation.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A peak-shaving heating system based on CO2 temperature and pressure swing adsorption coupling includes a low-pressure adsorption heat storage unit, a high-pressure adsorption heat storage unit, a compression and work unit, and a heat storage and supply circuit.

[0010] The low-pressure adsorption thermal storage unit adopts a group of low-pressure adsorption thermal storage towers with a parallel structure and is filled with heat-resistant CO2 adsorbent. It stores thermal energy and adsorbs CO2 at varying temperatures during circulation.

[0011] The high-pressure adsorption and storage unit adopts a high-pressure adsorption and storage tower and is filled with pressure-resistant CO2 adsorbent. It stores pressure potential energy and performs pressure swing adsorption of CO2 during circulation.

[0012] The compression and power unit includes a compressor, a compression heat exchanger, a pressure swing adsorption heat exchanger, an expander, a regenerator, and a power grid port;

[0013] The heat storage and supply circuit includes a heat storage heat pump, a heat release heat pump, a heat supply connection switch and a heat network port, and a heat transfer medium is provided in the heat storage and supply circuit;

[0014] The low-pressure adsorption thermal storage tower group, compressor, compression heat exchanger, high-pressure adsorption thermal storage tower, pressure swing adsorption heat exchanger, expander, and regenerator are sequentially connected to form a closed CO2 loop. The heat output end of the low-pressure adsorption thermal storage tower group is divided into two paths: one path is connected to the heat network port through a heating connection switch to form an external heating branch, and the other path is connected to the pressure swing adsorption heat exchanger through a heat release heat pump to form an energy release heating branch. The heat-side outlets of the compression heat exchanger and the pressure swing adsorption heat exchanger are connected to the low-pressure adsorption thermal storage tower group through a heat storage heat pump to form a heat storage branch. The heat recovery side outlet of the regenerator is connected to the pressure swing adsorption heat exchanger to realize waste heat recycling. The expander, the grid port, and the compressor are sequentially connected to realize the transmission of electrical energy.

[0015] Furthermore, the heat-resistant CO2 adsorbent is selected from zeolite molecular sieves, which can maintain physicochemical properties and structural stability at 400℃, and can adsorb CO2 up to 6 mol / kg at normal pressure, with a heat storage density of 370 kJ / kg.

[0016] Furthermore, the pressure-resistant CO2 adsorbent is activated carbon, which can adsorb CO2 up to 18 mol / kg at a pressure of 10 bar.

[0017] Furthermore, both the compression heat exchanger and the pressure swing adsorption storage-release heat exchanger are direct contact heat exchangers.

[0018] Furthermore, the heat transfer medium in the heat storage and supply circuit is selected from heat transfer oil or CO2 gas with a boiling point higher than 400℃, and the heat storage heat transfer pump and heat release heat transfer pump under the corresponding operating conditions are oil pumps or gas pumps.

[0019] Furthermore, the low-pressure adsorption thermal storage tower group has a thermal storage temperature of 400°C and a pressure of atmospheric pressure during off-peak electricity consumption; the high-pressure adsorption thermal storage tower has a storage pressure of 10 bar after pressurization and compression, and a temperature of ambient temperature.

[0020] An operation method for a peak-shaving heating system based on CO2 temperature- and pressure-swing adsorption coupling includes the following stages:

[0021] During off-peak electricity consumption periods: The gas outlet of the low-pressure adsorption thermal storage tower group and the gas inlet of the high-pressure adsorption thermal storage tower are opened. The grid port supplies surplus electricity to the compressor to drive its operation. CO2 gas flowing out of the low-pressure adsorption thermal storage tower group is pressurized by the compressor and enters the high-pressure adsorption thermal storage tower through the compression heat exchanger to complete the pressure swing adsorption process. The compression heat generated by the compressor is transferred to the thermal storage and supply circuit through the compression heat exchanger, and the adsorption heat generated by the high-pressure adsorption thermal storage tower is transferred to the thermal storage and supply circuit through the pressure swing adsorption heat exchanger. Simultaneously, the thermal storage heat pump drives the heat transfer medium in the thermal storage and supply circuit to transport the compression heat and adsorption heat to the low-pressure adsorption thermal storage tower group to provide desorption heat for temperature-switching desorption. After the temperature-switching desorption of the low-pressure adsorption thermal storage tower group and the pressure-switching adsorption of the high-pressure adsorption thermal storage tower are completed, the gas outlet of the low-pressure adsorption thermal storage tower group and the gas inlet of the high-pressure adsorption thermal storage tower are closed, so that the pressure potential energy and CO2 are stored in the high-pressure adsorption thermal storage tower, and the thermal energy is stored in the low-pressure adsorption thermal storage tower group, thus completing the conversion and storage of electrical energy into pressure potential energy and thermal energy.

[0022] During peak electricity consumption, the gas inlet of the low-pressure adsorption thermal storage tower group and the gas outlet of the high-pressure adsorption thermal storage tower are opened. The heat release heat transfer pump drives the heat transfer medium in the heat storage and supply circuit to transfer the heat energy stored in the low-pressure adsorption thermal storage tower group to the pressure swing adsorption heat exchanger and conduct it to the high-pressure adsorption thermal storage tower. The heated CO2 gas flowing out of the high-pressure adsorption thermal storage tower enters the expander after passing through the pressure swing adsorption heat exchanger to generate electricity. The electricity generated by the expander is transmitted to the power grid through the grid port to supplement the power supply gap. The CO2 discharged after the expander does work enters the regenerator to recover waste heat and is then sent back to the pressure swing adsorption heat exchanger. After the CO2 is depressurized and heat-released by the expander and regenerator, it flows into the low-pressure adsorption thermal storage tower group for adsorption and storage, completing the release of pressure potential energy and the conversion of heat energy into electricity.

[0023] Furthermore, when there is a demand for heating around the clock, the heating connection switch is opened according to the demand for heating volume and heating quality, and the heat energy stored in the low-pressure adsorption thermal storage tower group is transported to the heating network port through the heat transfer medium to supply heat to the heating network. The heat source of the low-pressure adsorption thermal storage tower group comes from the heat energy stored during the off-peak electricity consumption period, and its heat energy quality is adjusted through the heat release process during the peak electricity consumption period.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] 1. Resolving the contradiction between flexibility and economy in heat energy supply: This invention uses CO2 adsorbent as a dual-function material for heat and mass storage, and low-pressure adsorption tower as a heat storage unit to construct a combined heat and mass storage mechanism. This overcomes the problems of system complexity and high construction and maintenance costs brought about by heat storage towers and heat storage media in heat storage systems. At the same time, it solves the problem of insufficient heat supply flexibility in the on-demand mode of non-heat storage systems, simplifies the system structure and improves the economic efficiency of operation.

[0026] 2. Improve the peak-shaving capacity and heat quality adjustability of the system: This invention utilizes stored thermal energy to heat high-pressure CO2 to enhance its work capacity, realizes the flexible conversion of high-grade thermal energy storage into electrical energy, enhances the system's peak power supply capacity, and can adjust the thermal energy storage quality through the heat release process to high-pressure CO2, thereby realizing on-demand control of heat quality.

[0027] 3. Effective utilization of in-situ thermal and pressure storage conditions: This invention utilizes in-situ energy storage conditions to effectively couple and integrate CO2 temperature swing adsorption and pressure swing adsorption, solving the energy consumption problem of adsorbent temperature swing adsorption and desorption. Based on the characteristics of pressure swing adsorption, high-pressure compression adsorption of CO2 is designed to achieve high-density CO2 storage while flexibly adjusting peak loads. The high-temperature characteristics of thermal storage are used to simultaneously achieve CO2 desorption and separation with zero additional energy consumption. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the system of the present invention.

[0029] In the diagram: 1. Low-pressure adsorption heat storage tower group; 2. Compressor; 3. Compression heat exchanger; 4. High-pressure adsorption heat storage tower; 5. Pressure swing adsorption heat storage and release heat exchanger; 6. Expander; 7. Regenerator; 8. Power grid port; 9. Heat storage heat pump; 10. Heat release heat pump; 11. Heating connection switch; 12. Heat network port. Detailed Implementation

[0030] 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. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0031] like Figure 1 As shown, a peak-shaving heating system based on CO2 temperature and pressure swing adsorption coupling includes four components: a low-pressure adsorption thermal storage unit, a high-pressure adsorption thermal storage unit, a compression and work unit, and a thermal storage and supply circuit. Specifically:

[0032] The low-pressure adsorption thermal storage unit employs a low-pressure adsorption thermal storage tower group 1, which consists of multiple low-pressure adsorption thermal storage towers connected in parallel. Each low-pressure adsorption thermal storage tower has an insulated outer layer and is filled with a heat-resistant CO2 adsorbent. During circulation, it stores thermal energy and adsorbs CO2 at varying temperatures. In one embodiment, the heat-resistant CO2 adsorbent is selected as zeolite molecular sieve, which maintains stable physicochemical properties and structure at 400℃. At atmospheric pressure, its CO2 adsorption capacity can reach 6 mol / kg, and its thermal storage density can reach 370 kJ / kg, thus possessing both CO2 adsorption and thermal storage functions, achieving combined heat and mass storage.

[0033] The high-pressure adsorption storage unit employs a high-pressure adsorption storage tower 4. The high-pressure adsorption storage tower 4 features an externally reinforced pressure storage design, capable of stably withstanding a working pressure of at least 10 bar. It is internally filled with a pressure-resistant CO2 adsorbent, storing pressure potential energy and performing pressure swing adsorption of CO2 during circulation. In one embodiment, the pressure-resistant CO2 adsorbent is activated carbon, which can adsorb up to 18 mol / kg of CO2 at 10 bar, achieving high-density adsorption and storage of CO2 under high-pressure conditions.

[0034] The compression and power unit includes a compressor 2, a compression heat exchanger 3, a pressure swing adsorption (PSA) heat exchanger 5, an expander 6, a regenerator 7, and a power grid port 8. In one embodiment, both the compression heat exchanger 3 and the PSA heat exchanger 5 are direct contact heat exchangers to improve heat exchange efficiency. Wherein:

[0035] The compressor 2 is used to pressurize and compress the high-purity CO2 desorbed from the low-pressure adsorption and thermal storage tower group 1 to the high-pressure adsorption and thermal storage tower 4 during off-peak electricity hours.

[0036] The compression heat exchanger 3 is used to transfer the compression heat released during the above process to the heat storage and supply circuit.

[0037] The pressure swing adsorption heat exchanger 5 is used to transfer the adsorption heat during the CO2 compression and adsorption process to the heat storage and supply circuit during the off-peak electricity consumption period, and to transfer the heat release of the heat storage and supply circuit to the high-pressure CO2 in front of the expander 6 during the peak electricity consumption period.

[0038] The expander 6 is used to generate electricity by expanding the CO2 stored in the high-pressure adsorption storage tower 4 during peak electricity demand.

[0039] The regenerator 7 is used to recover the waste heat of the low-pressure, high-temperature CO2 after expansion and conduct it to the high-pressure CO2 in front of the expander 6;

[0040] The power grid port 8 is used to supply the compressor 2 with surplus power from the power grid during off-peak hours and to transmit the power generated by the expander 6 to the power grid during peak hours.

[0041] The heat storage and supply circuit includes a heat storage heat pump 9, a heat release heat pump 10, a heat supply connection switch 11, and a heat network port 12. In one embodiment, the heat transfer medium in the heat storage and supply circuit is heat transfer oil with a boiling point higher than 400℃, and the corresponding operating conditions use oil pumps for the heat storage heat pump 9 and the heat release heat pump 10; in another embodiment, the heat transfer medium in the heat storage and supply circuit is CO2 gas, and the corresponding operating conditions use gas pumps for the heat storage heat pump 9 and the heat release heat pump 10. Wherein:

[0042] The heat storage and heat transfer pump 9 is used to drive the heat transfer medium in the heat storage and supply circuit during off-peak hours to transfer the compression heat of the compression heat exchanger 3 and the adsorption heat of the pressure swing adsorption heat storage and release heat exchanger 5 to the low-pressure adsorption heat storage tower group 1.

[0043] The heat release heat pump 10 is used to drive the heat transfer medium in the heat storage and supply circuit during peak electricity consumption to transfer the heat energy stored in the low-pressure adsorption heat storage tower group 1 to the high-pressure CO2 in front of the expander 6.

[0044] The heating connection switch 11 is used to flexibly control the low-pressure adsorption thermal storage tower group 1 to supply heat to the heating network according to the requirements of heat supply and heat quality.

[0045] The heating network port 12 is used to deliver heat energy to the heating network when the heating connection switch 11 is turned on.

[0046] In this system, the low-pressure adsorption thermal storage tower group 1 has a thermal storage temperature of 400℃ during off-peak electricity demand, and its heat energy grade gradually decreases with heat release during peak electricity demand, while the pressure is atmospheric pressure; the high-pressure adsorption thermal storage tower 4 has a storage pressure of 10 bar after pressurization and compression, and the temperature is ambient temperature; the temperature of the heat transfer medium in the thermal storage and supply circuit is between ambient temperature and thermal storage temperature.

[0047] The connections between the components are as follows:

[0048] The input end of compressor 2 is connected to the gas outlet of low-pressure adsorption heat storage tower group 1. The output end of compressor 2 is connected to the gas inlet of high-pressure adsorption heat storage tower 4 through compression heat exchanger 3. The gas outlet of high-pressure adsorption heat storage tower 4 is connected to the gas input end of expander 6 through pressure swing adsorption heat exchanger 5. The gas output end of expander 6 is connected to the gas inlet of low-pressure adsorption heat storage tower group 1 through regenerator 7.

[0049] The heat output end of the low-pressure adsorption thermal storage tower group 1 is divided into two paths: one path is connected to the heat network port 12 through the heating connection switch 11 to form an external heating branch; the other path is connected to the hot side inlet of the pressure swing adsorption heat exchanger 5 through the heat release heat pump 10 to form an energy release heating branch. The hot side outlet of the compression heat exchanger 3 and the hot side outlet of the pressure swing adsorption heat exchanger 5 are connected to the heat input end of the low-pressure adsorption thermal storage tower group 1 through the heat storage heat pump 9 to form a heat storage branch. In addition, the heat recovery side outlet of the regenerator 7 is connected to the hot side inlet of the pressure swing adsorption heat exchanger 5 to realize the recycling of waste heat.

[0050] The power output terminal of the power grid port 8 is connected to the power input terminal of the compressor 2, and the power input terminal of the power grid port 8 is connected to the power output terminal of the expander 6 to realize the transmission of electrical energy.

[0051] like Figure 1 As shown, an operation method for a peak-shaving heating system based on CO2 temperature- and pressure-swing adsorption coupling includes the following stages:

[0052] Energy storage during off-peak electricity demand:

[0053] During periods of low electricity demand, when the power grid has surplus power, the gas outlet of the low-pressure adsorption thermal storage tower group 1 and the gas inlet of the high-pressure adsorption thermal storage tower 4 are opened. The power grid port 8 transmits the surplus power to the compressor 2 to drive its operation. CO2 gas flows out from the low-pressure adsorption thermal storage tower group 1, is pressurized by the compressor 2, and enters the high-pressure adsorption thermal storage tower 4 through the compression heat exchanger 3. The pressure swing adsorption process is completed in the high-pressure adsorption thermal storage tower 4. The compression heat generated by the compressor 2 is conducted to the thermal storage and supply circuit through the compression heat exchanger 3, and the adsorption heat generated by the high-pressure adsorption thermal storage tower 4 is conducted to the thermal storage and supply circuit through the pressure swing adsorption thermal release heat exchanger 5. Simultaneously, the thermal storage heat pump 9 starts and drives the heat transfer medium in the thermal storage and supply circuit, delivering the heat of compression and the heat of adsorption to the low-pressure adsorption thermal storage tower group 1, providing desorption heat for the temperature-switching desorption of CO2 on the zeolite molecular sieve inside the tower; after the temperature-switching desorption of the low-pressure adsorption thermal storage tower group 1 and the pressure-switching adsorption of the high-pressure adsorption thermal storage tower 4 are completed, the gas outlet of the low-pressure adsorption thermal storage tower group 1 and the gas inlet of the high-pressure adsorption thermal storage tower 4 are closed, so that the pressure potential energy and high-purity CO2 are stored in the high-pressure adsorption thermal storage tower 4, and the remaining thermal energy is stored in the low-pressure adsorption thermal storage tower group 1, completing the conversion and storage of electrical energy into pressure potential energy and thermal energy.

[0054] Peak electricity consumption phase:

[0055] During peak electricity consumption periods, when there is a power supply shortage in the power grid, the gas inlet of the low-pressure adsorption thermal storage tower group 1 and the gas outlet of the high-pressure adsorption thermal storage tower 4 are opened. The heat release heat pump 10 starts and drives the heat transfer medium in the heat storage and supply circuit to transfer the heat energy stored in the low-pressure adsorption thermal storage tower group 1 to the pressure swing adsorption heat exchanger 5. The pressure swing adsorption heat exchanger 5 transfers the heat energy to the high-pressure adsorption thermal storage tower 4. The heated CO2 gas flows out from the high-pressure adsorption thermal storage tower 4, passes through the pressure swing adsorption heat exchanger 5, and then enters the expander 6. The expander 6 generates electricity; the electricity generated is transmitted to the power grid through the grid port 8 to supplement the power supply gap. The low-pressure, high-temperature CO2 discharged after the expander 6 has done its work enters the regenerator 7. The regenerator 7 recovers the waste heat of this part of the CO2 gas and sends it back to the pressure swing adsorption heat exchanger 5 for recycling. The high-purity, low-pressure CO2 after being depressurized and released by the expander 6 and the regenerator 7 flows into the low-pressure adsorption heat storage tower group 1 and is adsorbed and stored by zeolite molecular sieves under normal temperature and pressure conditions, completing the release of pressure potential energy and the conversion of heat energy into electrical energy.

[0056] 24-hour heating phase:

[0057] In response to the time mismatch between heat and power supply and demand, when there is a demand for heating around the clock, the heating connection switch 11 is opened according to the demand for heat supply and heat quality, and the heat energy stored in the low-pressure adsorption thermal storage tower group 1 is transported to the heat network port 12 through the heat transfer medium to supply heat to the heat network. The heat source of the low-pressure adsorption thermal storage tower group 1 comes from the heat energy stored during the off-peak electricity consumption period, and its heat energy quality can be adjusted by the heat release process during the peak electricity consumption period.

[0058] In summary, this invention replaces the high-pressure gas storage tank of conventional compressed gas energy storage systems with a high-pressure adsorption tower in the off-peak electricity energy storage stage. Based on the pressure swing adsorption characteristics of CO2, it significantly increases the CO2 storage density by utilizing the high-pressure conditions of compressed gas energy storage. A group of low-pressure adsorption towers is used for heat storage, storing the compression heat and adsorption heat generated on the high-pressure side in the low-pressure adsorption towers, saving heat storage tanks and heat storage media. The high temperature (400°C) of the heat storage is used to supply desorption heat to achieve simultaneous desorption and separation of CO2 on the low-pressure side, converting excess electricity into pressure potential energy and thermal energy storage. In the peak electricity release stage, the heat storage, adsorption heat, and expansion and reheat of the high-pressure CO2 in the low-pressure adsorption tower are used to enhance the work-making capacity and realize thermoelectric conversion. The heat storage and the heat network are controllably connected for flexible on-demand heating around the clock. The heat release from the heating of high-pressure CO2 is combined with the adjustment of the heat energy grade of the heat network supply, realizing the decoupling of thermoelectric supply and the regulation of thermoelectric energy supply.

[0059] Through the above design, this invention, based on existing compressed gas energy storage technology, deeply integrates CO2 sequestration technology with peak-shaving heating to construct an electric-thermal-pressure combined cycle. Based on the coupling of temperature-swing adsorption and pressure-swing adsorption of CO2 adsorbent, a high-pressure adsorption tower replaces the gas storage tank of a conventional compressed CO2 energy storage system. At the same time, the CO2 adsorbent is used as a dual-functional material for heat storage and mass storage, and the low-pressure adsorption tower is used as a heat storage unit to achieve efficient grid peak shaving and flexible on-demand heating. The pressure-swing characteristics of the pressure storage and release process and the high-temperature characteristics of the heat storage process are used to provide in-situ energy for the adsorbent's temperature-swing and pressure-swing adsorption-desorption cycle. During off-peak hours, surplus electricity is converted into pressure potential energy and thermal energy for storage. During peak hours, thermal energy is released to heat the working fluid to increase power output while regulating the heating quality. This simplifies the system structure, reduces construction and maintenance costs, and solves the core problem of the difficulty in balancing the flexibility and economy of thermal energy utilization in existing technologies.

[0060] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0061] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A peak-shaving heating system based on CO2 temperature- and pressure-swing adsorption coupling, characterized in that: It includes a low-pressure adsorption thermal storage unit, a high-pressure adsorption thermal storage unit, a compression and power unit, and a thermal storage and supply circuit; The low-pressure adsorption thermal storage unit adopts a low-pressure adsorption thermal storage tower group (1) with a parallel structure and is filled with heat-resistant CO2 adsorbent. It stores thermal energy and adsorbs CO2 at varying temperatures during circulation. The high-pressure adsorption storage unit adopts a high-pressure adsorption storage tower (4) and is filled with pressure-resistant CO2 adsorbent. It stores pressure potential energy and performs pressure swing adsorption of CO2 in the circulation. The compression and power unit includes a compressor (2), a compression heat exchanger (3), a pressure swing adsorption heat exchanger (5), an expander (6), a regenerator (7), and a power grid port (8). The heat storage and supply circuit includes a heat storage heat pump (9), a heat release heat pump (10), a heat supply connection switch (11), and a heat network port (12), and a heat transfer medium is provided in the heat storage and supply circuit; The low-pressure adsorption heat storage tower group (1), compressor (2), compression heat exchanger (3), high-pressure adsorption heat storage tower (4), pressure swing adsorption heat storage and release heat exchanger (5), expander (6) and regenerator (7) are sequentially connected to form a CO2 closed loop; the heat output end of the low-pressure adsorption heat storage tower group (1) is divided into two paths: one path is connected to the heat network port (12) through the heating connection switch (11) to form an external heating branch, and the other path is connected to the pressure swing adsorption heat storage and release heat exchanger (5) through the heat release heat pump (10) to form an energy release heating branch. The heat side outlet of the compression heat exchanger (3) and the pressure swing adsorption heat storage and release heat exchanger (5) are connected to the low-pressure adsorption heat storage tower group (1) through the heat storage heat pump (9) to form a heat storage branch. The heat recovery side outlet of the regenerator (7) is connected to the pressure swing adsorption heat storage and release heat exchanger (5) to realize the recycling of waste heat; the expander (6), the power grid port (8) and the compressor (2) are sequentially connected to realize the transmission of electrical energy.

2. The peak-shaving heating system based on CO2 temperature-swing-pressure-swing adsorption coupling according to claim 1, characterized in that: The heat-resistant CO2 adsorbent is selected from zeolite molecular sieves. The zeolite molecular sieves can maintain physicochemical properties and structural stability at 400℃, and the adsorption capacity of CO2 under normal pressure can reach 6 mol / kg, and the heat storage density can reach 370 kJ / kg.

3. The peak-shaving heating system based on CO2 temperature-swing-pressure-swing adsorption coupling according to claim 1, characterized in that: The pressure-resistant CO2 adsorbent is activated carbon, which can adsorb CO2 up to 18 mol / kg at a pressure of 10 bar.

4. A peak-shaving heating system based on CO2 temperature- and pressure-swing adsorption coupling according to claim 1, characterized in that: Both the compression heat exchanger (3) and the pressure swing adsorption storage and release heat exchanger (5) are direct contact heat exchangers.

5. A peak-shaving heating system based on CO2 temperature- and pressure-swing adsorption coupling according to claim 1, characterized in that: The heat transfer medium in the heat storage and supply circuit is selected from heat transfer oil or CO2 gas with a boiling point higher than 400℃. Under the corresponding operating conditions, the heat storage heat transfer pump (9) and the heat release heat transfer pump (10) are oil pumps or gas pumps.

6. A peak-shaving heating system based on CO2 temperature-swing-pressure adsorption coupling according to claim 1, characterized in that: The low-pressure adsorption heat storage tower group (1) has a heat storage temperature of 400℃ and a pressure of atmospheric pressure during off-peak electricity consumption; the high-pressure adsorption heat storage tower (4) has a storage pressure of 10 bar and a temperature of ambient temperature after pressurization and compression.

7. An operation method for a peak-shaving heating system based on CO2 temperature- and pressure-swing adsorption coupling, characterized in that: The operation method of the peak-shaving heating system based on CO2 temperature-swing-pressure adsorption coupling according to claim 1. Includes the following stages: During off-peak electricity consumption, the gas outlet of the low-pressure adsorption thermal storage tower group (1) and the gas inlet of the high-pressure adsorption thermal storage tower (4) are opened. The grid port (8) transmits surplus grid electricity to the compressor (2) to drive its operation. The CO2 gas flowing out from the low-pressure adsorption thermal storage tower group (1) is pressurized by the compressor (2) and enters the high-pressure adsorption thermal storage tower (4) through the compression heat exchanger (3) to complete the pressure swing adsorption process. The compression heat generated by the compressor (2) is conducted to the heat supply and storage circuit through the compression heat exchanger (3). The adsorption heat generated by the high-pressure adsorption thermal storage tower (4) is conducted through the pressure swing adsorption heat exchanger (5). The heat storage and heat supply circuit is connected, and the heat storage and heat transfer pump (9) drives the heat transfer medium in the heat storage and heat supply circuit to transport the compression heat and adsorption heat to the low-pressure adsorption heat storage tower group (1) to provide desorption heat for temperature-switching desorption. When the temperature-switching desorption of the low-pressure adsorption heat storage tower group (1) and the pressure-switching adsorption process of the high-pressure adsorption heat storage tower (4) are completed, the gas outlet of the low-pressure adsorption heat storage tower group (1) and the gas inlet of the high-pressure adsorption heat storage tower (4) are closed, so that the pressure potential energy and CO2 are stored in the high-pressure adsorption heat storage tower (4) and the thermal energy is stored in the low-pressure adsorption heat storage tower group (1), thus completing the conversion and storage of electrical energy into pressure potential energy and thermal energy. During the peak electricity consumption period, the gas inlet of the low-pressure adsorption thermal storage tower group (1) and the gas outlet of the high-pressure adsorption thermal storage tower (4) are opened. The heat release heat pump (10) drives the heat transfer medium in the heat storage and supply circuit to transport the heat energy stored in the low-pressure adsorption thermal storage tower group (1) to the pressure swing adsorption heat exchanger (5) and conduct it to the high-pressure adsorption thermal storage tower (4). The heated CO2 gas flowing out of the high-pressure adsorption thermal storage tower (4) enters the expander (6) after passing through the pressure swing adsorption heat exchanger (5) to generate electricity. The electrical energy generated by the expander (6) is transmitted to the power grid through the grid port (8) to supplement the power supply gap. The CO2 discharged after the expander (6) does work enters the regenerator (7) to recover the waste heat and is then transported back to the pressure swing adsorption heat exchanger (5). After the CO2 is depressurized and heated by the expander (6) and the regenerator (7), it flows into the low-pressure adsorption thermal storage tower group (1) for adsorption and storage, completing the release of pressure potential energy and the conversion of heat energy into electrical energy.

8. The operation method of a peak-shaving heating system based on CO2 temperature-swing-pressure adsorption coupling according to claim 7, characterized in that: When there is a demand for heating around the clock, the heating connection switch (11) is turned on according to the demand for heating and heating quality. The heat energy stored in the low-pressure adsorption heat storage tower group (1) is transported to the heat network port (12) through the heat transfer medium to supply heat to the heat network. The heat source of the low-pressure adsorption heat storage tower group (1) comes from the heat energy stored during the low-electricity consumption energy storage stage. Its heat energy quality is adjusted through the heat release process during the peak electricity consumption energy release stage.

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