Energy utilization system and method coupling solar thermal storage and carbon dioxide energy storage

Abstract

The present invention belongs to the field of energy storage technology and discloses an energy utilization system and method that couples solar thermal storage with carbon dioxide energy storage. The energy utilization system coupled with solar thermal storage and carbon dioxide energy storage includes a carbon dioxide energy storage system, a cold storage tank, a heat storage tank, a solar collector, and cold storage ice slurry. The carbon dioxide energy storage system includes a cold storage cycle, a heat storage cycle, and an energy release cycle. In the technical solution provided by the present invention, heat is stored by collecting solar energy and used to provide the required heat for the system's energy release process. The combined action of the heat storage cycle and the cold storage cycle during the energy storage process provides the required cooling for the system's energy release process. Ultimately, the energy required by the energy utilization system can be completely self-supplied, with the advantages of high energy storage efficiency and high energy density.

Description

Technical Field

[0001] The present invention belongs to the field of energy storage technology, and in particular relates to an energy utilization system and method coupling solar thermal storage with carbon dioxide energy storage. Background Art

[0002] In recent years, energy storage technology has received increasing attention. Its application can largely address the volatility and intermittency of renewable energy generation, effectively solving the problem of peak-to-valley shifting. Traditional compressed air energy storage is considered the most widely used large-scale energy storage technology. However, its development has been limited by its low energy storage density, low efficiency, and dependence on specific geographical conditions. Compared to air, carbon dioxide has a critical point close to room temperature, offering higher stability and energy storage density. Therefore, compressed energy storage technology using carbon dioxide as a working fluid has seen significant development in recent years.

[0003] At present, traditional compressed carbon dioxide energy storage systems use excess electricity to compress carbon dioxide at room temperature and pressure to the storage pressure during the energy storage process, then condense and store it in a storage tank. During the energy release process, the compression heat generated during the energy storage process is used to heat the carbon dioxide and then expand it to generate electricity. Among them, carbon dioxide is always in a gaseous state during the energy storage and release processes. To ensure that the system has sufficient capacity, a larger gas storage chamber volume is usually required, resulting in a lower energy storage density of the system. In addition, the existing conventional solar thermal power generation system has weak energy storage function and is mostly coupled with the steam turbine Rankine cycle, which makes the system efficiency relatively low. Summary of the Invention

[0004] The present invention aims to provide an energy utilization system and method that couples solar thermal storage with carbon dioxide energy storage to address one or more of the aforementioned technical issues. The technical solution provided by the present invention collects solar energy to store heat, which is then used to provide the heat required for the system's energy release process. The combined action of the heat storage cycle and the cold storage cycle during the energy storage process provides the required cooling for the system's energy release process. Ultimately, the energy utilization system can be fully self-supplied, offering advantages such as high energy storage efficiency and high energy density.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides an energy utilization system that couples solar heat storage and carbon dioxide energy storage, comprising: a carbon dioxide energy storage system, a cold storage tank, a heat storage tank, a solar thermal collector, and cold storage ice slurry; wherein,

[0007] The carbon dioxide energy storage system includes a cold storage cycle, a heat storage cycle, and an energy release cycle; wherein, in the cold storage cycle, the outlet of the first carbon dioxide compressor is connected to the inlet of the first carbon dioxide turbine via the first heat exchange channel of the carbon dioxide heat exchanger, and the outlet of the first carbon dioxide turbine is connected to the inlet of the first carbon dioxide compressor via the first heat exchange channel of the carbon dioxide evaporator; in the heat storage cycle, the outlet of the second carbon dioxide compressor is connected to the inlet of the second carbon dioxide turbine via the first heat exchange channel of the carbon dioxide cooler, and the outlet of the second carbon dioxide turbine is connected to the inlet of the second carbon dioxide compressor via the second heat exchange channel of the carbon dioxide heat exchanger and the carbon dioxide preheater in sequence; in the energy release cycle, the outlet of the first heat exchange channel of the carbon dioxide condenser is connected to the inlet of the third carbon dioxide turbine via the carbon dioxide booster pump and the first heat exchange channel of the carbon dioxide heater in sequence, and the outlet of the third carbon dioxide turbine is connected to the inlet of the first heat exchange channel of the carbon dioxide condenser;

[0008] The outlet of the cold storage tank is divided into two paths, one path is connected to the inlet of the heat storage tank through the second heat exchange channel of the carbon dioxide cooler, and the other path is connected to the inlet of the heat storage tank through the solar collector; the outlet of the heat storage tank is connected to the inlet of the cold storage tank through the second heat exchange channel of the carbon dioxide heater;

[0009] The first outlet of the cold storage ice slurry is connected to the first inlet of the cold storage ice slurry through the second heat exchange channel of the carbon dioxide evaporator; the second outlet of the cold storage ice slurry is connected to the second inlet of the cold storage ice slurry through the second heat exchange channel of the carbon dioxide condenser.

[0010] A further improvement of the present invention is that it further comprises: a mixer; wherein,

[0011] The outlet of the cold storage tank is divided into two routes, one route is connected to the inlet of the heat storage tank through the second heat exchange channel of the carbon dioxide cooler, and the other route is connected to the inlet of the heat storage tank through the solar collector. Specifically,

[0012] The outlet of the cold storage tank is divided into two paths, one path is connected to the first inlet of the mixer through the second heat exchange channel of the carbon dioxide cooler, and the other path is connected to the second inlet of the mixer through the solar collector. The outlet of the mixer is connected to the inlet of the heat storage tank.

[0013] A further improvement of the present invention is that it further comprises: a control valve;

[0014] The outlet of the cold storage tank is connected to the inlet of the solar heat collector through the control valve.

[0015] A further improvement of the present invention is that it further comprises: a first motor and a second motor;

[0016] The first motor and the second motor are respectively used to drive a first carbon dioxide compressor and a second carbon dioxide compressor using off-peak electricity.

[0017] A further improvement of the present invention is that it further comprises: a first generator, a second generator and a third generator;

[0018] The first generator, the second generator and the third generator are used to generate electricity under the drive of the first carbon dioxide turbine, the second carbon dioxide turbine and the third carbon dioxide turbine respectively.

[0019] A further improvement of the present invention is that the cold storage ice slurry is a constant temperature cold storage ice slurry.

[0020] A further improvement of the present invention is that, in the heat storage cycle, the working fluid at the inlet of the second carbon dioxide compressor is superheated gaseous carbon dioxide, and the working fluid at the outlet of the second carbon dioxide compressor is supercritical carbon dioxide; the working fluid at the inlet of the second carbon dioxide turbine is supercritical or subcooled liquid carbon dioxide, and the working fluid at the outlet of the second carbon dioxide turbine is gas-liquid coexisting carbon dioxide. After passing through the carbon dioxide heat exchanger and absorbing heat in the cold storage cycle, the working fluid is converted into saturated gaseous carbon dioxide, and the saturated gaseous carbon dioxide enters the carbon dioxide preheater to absorb heat and be converted into superheated gaseous carbon dioxide.

[0021] A further improvement of the present invention is that, in the cold storage cycle, the working fluid at the inlet of the first carbon dioxide compressor is saturated gaseous carbon dioxide, and the working fluid at the outlet of the first carbon dioxide compressor is superheated gaseous carbon dioxide. After the heat is transferred to the cold storage cycle through the carbon dioxide heat exchanger, the working fluid is converted into saturated liquid carbon dioxide. After the saturated liquid carbon dioxide enters the first carbon dioxide turbine to expand and do work, the working fluid is converted into a gas-liquid coexistence state and enters the carbon dioxide evaporator to absorb heat and be converted into saturated gaseous carbon dioxide.

[0022] A further improvement of the present invention is that, in the energy release cycle, the inlet of the carbon dioxide booster pump is saturated liquid carbon dioxide, and the outlet of the carbon dioxide booster pump is supercooled liquid carbon dioxide; after the supercooled liquid carbon dioxide enters the carbon dioxide heater to absorb the heat stored in the heat storage cycle, the working fluid is converted into supercritical carbon dioxide and enters the carbon dioxide third turbine to expand and perform work. After the expansion and work, the working fluid is converted into superheated gaseous carbon dioxide and enters the carbon dioxide condenser to absorb the cold in the cold storage ice slurry and then converted into saturated liquid carbon dioxide.

[0023] The present invention provides an energy utilization method coupling solar thermal storage and carbon dioxide energy storage, comprising the following steps:

[0024] When the user is in a low electricity consumption period, the energy storage part of the energy utilization system starts to work. During the energy storage process, the heat storage cycle and the cold storage cycle work simultaneously; wherein, the gaseous carbon dioxide enters the first carbon dioxide compressor and is compressed by the electricity in the low-peak period so that the carbon dioxide is pressurized and heated. After the carbon dioxide is pressurized and heated, it enters the carbon dioxide heat exchanger and exchanges heat with the low-temperature carbon dioxide in the heat storage cycle to cool down. The cooled high-pressure and low-temperature carbon dioxide enters the first carbon dioxide turbine to expand and do work. The carbon dioxide at the outlet of the first carbon dioxide turbine enters the carbon dioxide evaporator to evaporate and absorb heat. The cold amount absorbed by evaporation comes from the cold storage ice slurry. The gaseous carbon dioxide after evaporation and absorption of heat enters The first carbon dioxide compressor completes the cold storage cycle; the gaseous carbon dioxide enters the second carbon dioxide compressor and is compressed using electricity during the off-peak period to increase the pressure and temperature of the carbon dioxide. After the pressure and temperature are increased, the carbon dioxide enters the carbon dioxide cooler and exchanges heat with the low-temperature medium from the cold storage tank for cooling. The high-pressure and low-temperature carbon dioxide after heat exchange and cooling enters the second carbon dioxide turbine to expand and perform work. The carbon dioxide at the outlet of the second carbon dioxide turbine enters the carbon dioxide heat exchanger to absorb heat from the cold storage cycle and evaporate. The evaporated gaseous carbon dioxide enters the carbon dioxide preheater to exchange heat with the environment for heating. The heated carbon dioxide enters the second carbon dioxide compressor, completing the heat storage cycle.

[0025] When there is sufficient sunshine, the flow rate of working fluid entering the solar thermal collector is adjusted to collect solar heat, which is eventually stored in the heat storage tank. When there is insufficient sunshine, the heat storage tank only stores the heat generated by the heat exchange in the carbon dioxide cooler.

[0026] When the user is at the peak of electricity consumption, the energy release part of the energy utilization system starts to work; wherein, the low-temperature and low-pressure carbon dioxide enters the carbon dioxide booster pump and is pressurized to the target pressure, and then enters the carbon dioxide heater and exchanges heat with the high-temperature medium from the heat storage tank to increase the temperature. The low-temperature medium generated after the heat exchange is returned to the cold storage tank for storage, and the carbon dioxide after heat exchange and temperature increase enters the carbon dioxide third turbine to expand and do external work. The carbon dioxide at the outlet of the carbon dioxide third turbine enters the carbon dioxide condenser to exchange heat with the cold storage ice slurry, and enters the carbon dioxide booster pump after being cooled and condensed by the cold storage ice slurry, completing the energy release cycle.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] In the technical solution provided by the present invention, heat is stored by collecting solar energy and used to provide the required heat for the system's energy release process; the combined action of the heat storage cycle and the cold storage cycle in the energy storage process is utilized to provide the required heat and cold for the system's energy release process; ultimately, the energy required by the energy utilization system can be completely provided by itself, with the advantages of high energy storage efficiency and high energy density. Specifically, the technical solution of the present invention is provided with a solar thermal collector, which absorbs solar heat to assist the heat storage cycle in providing heat for the carbon dioxide heater. It can store heat when solar energy is sufficient, and use solar heat when the heat generated by the heat storage cycle is insufficient. While ensuring the normal operation of the system, it can effectively improve the energy storage efficiency of the system, and effectively reduce the impact of the periodicity and volatility of solar energy on the energy storage system and the thermal power generation system; so that the energy storage system coupled with solar heat storage has the advantages of high energy storage efficiency and high energy density; in addition, the technical solution of the present invention is provided with cold storage ice slurry, and the carbon dioxide heater balances the energy exchange between the heat storage cycle and the cold storage cycle to provide sufficient cooling capacity for the cold storage ice slurry, and uses the cold storage ice slurry to balance the energy balance between the cold storage cycle and the energy release cycle, which can effectively improve the energy storage efficiency of the system and the utilization rate of the system energy while ensuring the normal operation of the system.

[0029] During energy storage, the saturated gaseous carbon dioxide stored in the heat storage cycle enters the compressor for compression. The heated and pressurized carbon dioxide transfers heat to the cold storage cycle through a heat exchanger, where it is converted into liquid carbon dioxide and then enters the turbine for expansion to produce work. The system's cooler, heat exchanger, evaporator, cold storage tank, and cold storage ice slurry work together to maintain a balance between the heat storage cycle and the cold storage cycle, ensuring that the working fluid entering the compressor remains in a gaseous state and the working fluid entering the turbine remains in a liquid or supercritical state. This "gas compression-condensation-liquid expansion" method of carbon dioxide energy storage effectively reduces compressor power consumption during the energy storage process and improves the system's energy storage efficiency. By changing the maximum pressure of the heat storage cycle or the maximum pressure of the energy release cycle to change the state of the high-temperature, high-pressure carbon dioxide entering the turbine, the energy storage efficiency and energy density of the entire energy storage system can be further optimized. Due to its simple structure and the absence of additional gas or liquid storage tanks, the present invention facilitates distributed deployment and can further improve the system's energy storage density.

[0030] In the technical solution of the present invention, the combined effect of the heat storage cycle and the cold storage cycle in the energy storage process provides the required cooling capacity for the energy release process; the energy storage system collects solar energy to store heat, providing the required heat for the energy release process, and at the same time utilizes the combined effect of the heat storage cycle and the cold storage cycle in the energy storage process to provide the required heat and cooling capacity for the energy release process, so that the energy required by the system is completely provided by itself, which can realize energy storage and release and reduce users' electricity costs.

[0031] In the technical solution of the present invention, when electricity consumption is low, the system uses the low-valley electricity to use the cold storage cycle to generate cold and uses the heat storage cycle to generate heat; when there is sufficient sunshine, the solar collector can be used to collect solar energy and store this part of the heat; when electricity consumption is peak, the stored cold and heat are provided to the energy release cycle for power generation; when the heat generated by the heat storage cycle is insufficient during the energy storage process, the solar heat can be used to ensure the normal operation of the system while effectively improving the energy storage efficiency of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below; obviously, the drawings described below are some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 is a schematic diagram of an energy utilization system coupled with solar thermal storage and transcritical carbon dioxide energy storage in an embodiment of the present invention;

[0034] The explanation of the reference numerals in the figures is as follows:

[0035] 1. Carbon dioxide first compressor; 2. Carbon dioxide heat exchanger; 3. Carbon dioxide first turbine; 4. Carbon dioxide evaporator;

[0036] 5. CO2 preheater; 6. CO2 second compressor; 7. CO2 cooler; 8. CO2 second turbine;

[0037] 9. CO2 condenser; 10. CO2 booster pump; 11. CO2 heater; 12. CO2 third turbine;

[0038] 13. Cold storage tank; 14. Solar collector; 15. Mixer; 16. Heat storage tank; 17. Cold storage ice slurry; 18. Control valve. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0040] See also Figure 1 In an embodiment of the present invention, a comprehensive energy utilization system coupling solar thermal storage and transcritical carbon dioxide energy storage is provided, comprising: a carbon dioxide energy storage system, a cold storage tank 13, a heat storage tank 16, a solar thermal collector 14 and a cold storage ice slurry 17; wherein,

[0041] The carbon dioxide energy storage system includes a cold storage cycle, a heat storage cycle, and an energy release cycle. In the cold storage cycle, the outlet of the first carbon dioxide compressor 1 is connected to the inlet of the first carbon dioxide turbine 3 via the first heat exchange channel of the carbon dioxide heat exchanger 2, and the outlet of the first carbon dioxide turbine 3 is connected to the inlet of the first carbon dioxide compressor 1 via the first heat exchange channel of the carbon dioxide evaporator 4. In the heat storage cycle, the outlet of the second carbon dioxide compressor 6 is connected to the inlet of the second carbon dioxide turbine 8 via the first heat exchange channel of the carbon dioxide cooler 7, and the outlet of the second carbon dioxide turbine 8 is connected to the inlet of the second carbon dioxide compressor 6 via the second heat exchange channel of the carbon dioxide heat exchanger 2. In the energy release cycle, the outlet of the first heat exchange channel of the carbon dioxide condenser 9 is connected to the inlet of the third carbon dioxide turbine 12 via the first heat exchange channel of the carbon dioxide heater 11, and the outlet of the third carbon dioxide turbine 12 is connected to the inlet of the first heat exchange channel of the carbon dioxide condenser 9.

[0042] The outlet of the cold storage tank 13 is divided into two paths, one path is connected to the inlet of the heat storage tank 16 through the second heat exchange channel of the carbon dioxide cooler 7, and the other path is connected to the inlet of the heat storage tank 16 through the solar collector 14; the outlet of the heat storage tank 16 is connected to the inlet of the cold storage tank 13 through the second heat exchange channel of the carbon dioxide heater 11;

[0043] The cold storage ice slurry 17 is a constant temperature cold storage ice slurry. The first outlet of the cold storage ice slurry 17 is connected to the first inlet of the cold storage ice slurry 17 through the second heat exchange channel of the carbon dioxide evaporator 4; the second outlet of the cold storage ice slurry 17 is connected to the second inlet of the cold storage ice slurry 17 through the second heat exchange channel of the carbon dioxide condenser 9.

[0044] The technical solution provided in the embodiment of the present invention provides a new improvement scheme for the deficiencies of the existing compressed carbon dioxide energy storage technology and solar thermal power generation system; wherein, in the heat storage cycle, the working fluid in the pipe connected to the compressor inlet is superheated gaseous carbon dioxide, and the working fluid in the pipe connected to the compressor outlet is supercritical carbon dioxide. According to the initial temperature of the cold storage tank set by the system, the working fluid state at the turbine inlet in the heat storage cycle is supercritical or subcooled liquid (the turbine inlet temperature is related to the cold storage tank temperature and the cooler end difference. When the cooler hot end outlet temperature (i.e., the turbine inlet temperature) is higher than 31.1°C, the working fluid state is supercritical, otherwise it is liquid). The working fluid at the turbine outlet is in a state of coexistence of gas and liquid. After passing through the heat exchanger, it absorbs heat in the cold storage cycle to convert the working fluid into saturated gas. The saturated gaseous carbon dioxide enters the preheater to absorb heat and convert into superheated gas. The carbon dioxide gas then enters the compressor for the next cycle. In the cold storage cycle, the working medium in the pipe connected to the compressor inlet is saturated gaseous carbon dioxide, and the working medium in the pipe connected to the compressor outlet is superheated gaseous carbon dioxide. After passing through the heat exchanger, the heat is transferred to the cold storage cycle to convert the working medium into a saturated liquid state. The saturated liquid carbon dioxide enters the turbine to expand and work, and the working medium is converted into a gaseous state. It enters the evaporator to absorb heat and convert it into a saturated gaseous state, and finally enters the compressor for the next cycle. In the energy release cycle, the inlet of the booster pump is saturated liquid carbon dioxide, and the outlet is supercooled liquid carbon dioxide. It then enters the heater to absorb the heat stored in the heat storage cycle and convert it into supercritical carbon dioxide. It enters the turbine to expand and work and convert it into a superheated gaseous state. The superheated gaseous carbon dioxide enters the condenser to absorb the cold in the cold storage ice slurry and convert it into a saturated liquid state. It then enters the booster pump for the next cycle. In addition, since the system of the present invention mainly operates under high pressure and low temperature conditions, it has a good energy storage effect and high thermodynamic efficiency, and does not require an additional storage container to store the working medium. Therefore, the system of the present invention can reduce the power consumption of the system while improving the energy storage density of the system.

[0045] To explain in further detail, the technical solution of the embodiment of the present invention is provided with a solar thermal collector, which absorbs solar heat to assist the heat storage cycle to provide heat for the carbon dioxide heater. The solar heat can be stored when there is sufficient solar energy, and the solar heat can be used when the heat generated by the heat storage cycle is insufficient. While ensuring the normal operation of the system, it can effectively improve the energy storage efficiency of the system and effectively reduce the impact of the periodicity and volatility of solar energy on the energy storage system and the thermal power generation system; so that the energy storage system coupled with solar heat storage has the advantages of high energy storage efficiency and high energy density.

[0046] To explain further in detail, the technical solution of the embodiment of the present invention is provided with a constant temperature cold storage ice slurry, which balances the energy exchange between the heat storage cycle and the cold storage cycle through a carbon dioxide heat exchanger, thereby providing sufficient cooling capacity for the cold storage ice slurry, and then utilizing the cold storage ice slurry to balance the energy balance between the cold storage cycle and the energy release cycle, thereby effectively improving the energy storage efficiency of the system and the utilization rate of the system energy while ensuring the normal operation of the system.

[0047] During energy storage, the saturated gaseous carbon dioxide stored in the heat storage cycle enters the compressor for compression. The heated and pressurized carbon dioxide transfers heat to the cold storage cycle through a heat exchanger, where it is converted into liquid carbon dioxide and then enters the turbine for expansion to produce work. The system's cooler, heat exchanger, evaporator, cold storage tank, and cold storage ice slurry work together to maintain a balance between the heat storage cycle and the cold storage cycle, ensuring that the working fluid entering the compressor remains in a gaseous state and the working fluid entering the turbine remains in a liquid or supercritical state. This "gas compression-condensation-liquid expansion" process for carbon dioxide energy storage effectively reduces compressor power consumption during the energy storage process and improves the system's energy storage efficiency. By varying the maximum pressure of the heat storage cycle or the maximum pressure of the energy release cycle to change the state of the high-temperature, high-pressure carbon dioxide entering the turbine, the energy storage efficiency and energy density of the entire energy storage system can be further optimized. Due to its simple structure and the absence of additional gas or liquid storage tanks, the present invention facilitates distributed deployment and can further improve the system's energy storage density.

[0048] In summary, in the technical solution provided by the embodiments of the present invention, the combined action of the heat storage cycle and the cold storage cycle during the energy storage process provides the required cooling for the energy release process. The energy storage system collects solar energy to store heat, providing the required heat for the energy release process. At the same time, the combined action of the heat storage cycle and the cold storage cycle during the energy storage process provides the required cooling for the energy release process. This allows the system to fully provide the required energy, enabling energy storage and release, and reducing user electricity costs. To further explain, during periods of low electricity consumption, the system utilizes low-peak electricity to generate cooling using the cold storage cycle and heat using the heat storage cycle. During periods of sufficient sunshine, solar energy can be collected using solar collectors and this heat can be stored. During peak electricity consumption, the stored cooling and heat are provided to the energy release cycle for power generation.

[0049] In a preferred embodiment of the present invention, in the energy release cycle, the carbon dioxide booster pump 10 may be provided on the communication pipe between the carbon dioxide condenser 9 and the carbon dioxide heater 11 .

[0050] In a preferred embodiment of the present invention, the carbon dioxide preheater 5 is provided on the communication pipe between the outlet of the second heat exchange channel of the carbon dioxide heat exchanger 2 and the inlet of the second carbon dioxide compressor 6 .

[0051] In a preferred embodiment of the present invention, the outlet of the cold storage tank 13 is divided into two paths, one path is connected to the inlet of the heat storage tank 16 through the second heat exchange channel of the carbon dioxide cooler 7, and the other path is connected to the inlet of the heat storage tank 16 through the solar collector 14. Specifically, the outlet of the cold storage tank 13 is divided into two paths, one path is connected to the first inlet of the mixer 15 through the second heat exchange channel of the carbon dioxide cooler 7, and the other path is connected to the second inlet of the mixer 15 through the solar collector 14, and the outlet of the mixer 15 is connected to the inlet of the heat storage tank 16.

[0052] In a preferred embodiment of the present invention, the outlet of the cold storage tank 13 is connected to the inlet of the solar thermal collector 14 through a control valve 18 .

[0053] In one embodiment of the present invention, the present invention further comprises: a first motor and a second motor, respectively used to drive the first carbon dioxide compressor 1 and the second carbon dioxide compressor 6 using off-peak electricity.

[0054] In one embodiment of the present invention, it further comprises: a first generator, a second generator, and a third generator, which are used to generate electricity driven by the first carbon dioxide turbine 3, the second carbon dioxide turbine 8, and the third carbon dioxide turbine 12, respectively.

[0055] In one embodiment of the present invention, the cold storage cycle, heat storage cycle, and energy release cycle in the carbon dioxide energy storage system are specifically described as follows:

[0056] The cold storage cycle includes: a first carbon dioxide compressor 1, a carbon dioxide heat exchanger 2, a first carbon dioxide turbine 3 and a carbon dioxide evaporator 4; wherein, the outlet of the first carbon dioxide compressor 1 is connected to the first inlet of the carbon dioxide heat exchanger 2, and the first outlet of the carbon dioxide heat exchanger 2 is connected to the inlet of the first carbon dioxide turbine 3; the outlet of the first carbon dioxide turbine 3 is connected to the first inlet of the carbon dioxide evaporator 4, and the first outlet of the carbon dioxide evaporator 4 is connected to the inlet of the first carbon dioxide compressor 1, completing the cold storage cycle of the system.

[0057] The heat storage cycle includes: a second carbon dioxide compressor 6, a carbon dioxide cooler 7, a second carbon dioxide turbine 8 and a carbon dioxide preheater 5; wherein, the outlet of the second carbon dioxide compressor 6 is connected to the first inlet of the carbon dioxide cooler 7, the first outlet of the carbon dioxide cooler 7 is connected to the inlet of the second carbon dioxide turbine 8, the outlet of the second carbon dioxide turbine 8 is connected to the second inlet of the carbon dioxide heat exchanger 2, the second outlet of the carbon dioxide heat exchanger 2 is connected to the first inlet of the carbon dioxide preheater 5, and the first outlet of the carbon dioxide preheater 5 is connected to the inlet of the second carbon dioxide compressor 6, completing the heat storage cycle of the system.

[0058] The energy release cycle includes: a carbon dioxide booster pump 10, a carbon dioxide heater 11, a carbon dioxide third turbine 12 and a carbon dioxide condenser 9; wherein, the first outlet of the carbon dioxide condenser 9 is connected to the inlet of the carbon dioxide booster pump 10, the outlet of the carbon dioxide booster pump 10 is connected to the first inlet of the carbon dioxide heater 11, the first outlet of the carbon dioxide heater 11 is connected to the inlet of the carbon dioxide third turbine 12, and the outlet of the carbon dioxide third turbine 12 is connected to the first inlet of the carbon dioxide condenser 9, completing the energy release cycle of the system.

[0059] In addition, it also includes: a cold storage tank 13, a solar thermal collector 14, a mixer 15, a heat storage tank 16, a cold storage ice slurry 17 and a control valve 18; wherein, the outlet of the cold storage tank 13 is connected to the second inlet of the carbon dioxide cooler 7, the second outlet of the carbon dioxide cooler 7 is connected to the first inlet of the mixer 15, the outlet of the mixer 15 is connected to the inlet of the heat storage tank 16, the outlet of the heat storage tank 16 is connected to the second inlet of the carbon dioxide heater 11, and the second outlet of the carbon dioxide heater 11 is connected to the inlet of the cold storage tank 13. The above components constitute the entire energy storage part. In addition, the cold storage ice slurry 17 provided in the embodiment of the present invention is used to provide cooling for the energy release cycle and to maintain an energy balance between the cold storage cycle and the energy release cycle. Specifically, the second outlet of the carbon dioxide evaporator 4 is connected to the first inlet of the cold storage ice slurry 17, which is in turn connected to the second inlet of the carbon dioxide evaporator 4. The second outlet of the cold storage ice slurry 17 is connected to the second inlet of the carbon dioxide condenser 9, which is in turn connected to the second inlet of the cold storage ice slurry 17, to maintain an energy balance between the cold storage cycle and the energy release cycle. The solar thermal collector 14 is provided to absorb solar heat and provide heat to the carbon dioxide heater 11. Specifically, the outlet of the cold storage tank 13 is connected to the inlet of the solar thermal collector 14 via a control valve 18, which is then connected to the second inlet of the mixer 15 to collect solar thermal energy.

[0060] In an embodiment of the present invention, a comprehensive energy utilization method coupling solar thermal storage with transcritical carbon dioxide energy storage is provided. Based on the above-mentioned comprehensive energy utilization system in an embodiment of the present invention, the method specifically includes the following steps:

[0061] In the initial state, the valve of the control valve is closed, and carbon dioxide of different properties is stored in the system pipeline as the working fluid; among them, the carbon dioxide of different properties is specifically explained as follows: in the heat storage cycle, the working fluid in the pipeline connected to the compressor inlet is superheated gaseous carbon dioxide, and the working fluid in the pipeline connected to the compressor outlet is supercritical carbon dioxide; in the heat storage cycle, the working fluid at the turbine inlet is in a supercritical state or a subcooled liquid state, and the working fluid at the turbine outlet is in a state where gas and liquid coexist. After passing through the heat exchanger, the working fluid is converted into a saturated gaseous state, and the saturated gaseous carbon dioxide enters the preheater to absorb heat and is converted into a superheated gaseous state, and then enters the compressor; in the cold storage cycle, the pipe connected to the compressor inlet is The working fluid in the pipeline is saturated gaseous carbon dioxide, and the working fluid in the pipeline connected to the compressor outlet is superheated gaseous carbon dioxide. After passing through the heat exchanger, the working fluid is converted into saturated liquid carbon dioxide and enters the turbine to expand and do work. The working fluid at the turbine outlet is in a state of coexistence of gas and liquid. It enters the evaporator to absorb heat and is converted into saturated gas, and finally enters the compressor; in the energy release cycle, the inlet of the booster pump is saturated liquid carbon dioxide, and the outlet is supercooled liquid carbon dioxide. It then enters the heater and is converted into supercritical carbon dioxide and enters the turbine to expand and do work. The working fluid at the turbine outlet is superheated gas. The superheated gaseous carbon dioxide enters the condenser to absorb the cold in the cold storage ice slurry and is converted into saturated liquid, and then enters the booster pump.

[0062] When the user is in a low electricity consumption period, the energy storage part of the integrated energy utilization system starts to work. During the energy storage process, the heat storage cycle and the cold storage cycle work simultaneously. Among them, the gaseous carbon dioxide stored in the pipeline enters the first carbon dioxide compressor and is compressed using the electricity in the low period. After the carbon dioxide is pressurized and heated, it enters the carbon dioxide heat exchanger, where it exchanges heat with the low-temperature carbon dioxide in the heat storage cycle for cooling. The cooled high-pressure and low-temperature carbon dioxide enters the first carbon dioxide turbine to expand, and the carbon dioxide at the turbine outlet enters the carbon dioxide evaporator to evaporate and absorb heat, completing heat exchange with the constant temperature cold storage ice slurry, and the cold energy is collected by the constant temperature cold storage ice slurry. The evaporated gaseous carbon dioxide continues to enter the first carbon dioxide compressor to continue circulating, completing the cold storage cycle. Similarly, the gaseous carbon dioxide stored in the pipeline enters the second carbon dioxide compressor and is compressed using electricity during the off-peak period. After the carbon dioxide is pressurized and heated, it enters the carbon dioxide cooler, where it exchanges heat with the low-temperature medium from the cold storage tank for cooling. The cooled high-pressure and low-temperature carbon dioxide enters the second carbon dioxide turbine for expansion. The carbon dioxide at the turbine outlet enters the carbon dioxide heat exchanger to absorb heat from the carbon dioxide in the cold storage cycle for evaporation. The evaporated gaseous carbon dioxide enters the carbon dioxide preheater to exchange heat with the environment for heating. The heated carbon dioxide continues to enter the second carbon dioxide compressor to continue circulating, completing the heat storage cycle.

[0063] In the embodiment of the present invention, when there is sufficient sunshine, the valve of the control valve is opened, and the flow rate of the working fluid entering the solar thermal collector is adjusted by the control valve to collect the heat of the solar energy. The working fluid then enters the mixer and is mixed with the working fluid that has been heated by the carbon dioxide cooler through heat exchange. The heat generated by the heat storage cycle and the heat generated by the collected solar energy are stored and finally stored in the heat storage tank.

[0064] In the embodiment of the present invention, when the sunshine is insufficient, the control valve is closed, and the heat storage tank only stores the heat generated by the heat exchange in the carbon dioxide cooler, thus completing the solar heat collection and heat storage in the energy storage stage.

[0065] In an embodiment of the present invention, when the user is at a peak electricity consumption, the valve of the control valve is closed, and the energy release part of the integrated energy utilization system starts to work; wherein, the low-temperature and low-pressure carbon dioxide stored in the pipeline enters the carbon dioxide booster pump and is pressurized to the target pressure, and then enters the carbon dioxide heater to exchange heat with the high-temperature medium from the heat storage tank to increase the temperature, and the low-temperature medium generated after the heat exchange is returned to the cold storage tank for storage; the heated carbon dioxide enters the carbon dioxide third turbine to expand and perform external work, and the generator is used to generate electricity; the carbon dioxide at the turbine outlet enters the carbon dioxide condenser to exchange heat with the constant temperature cold storage ice slurry, and is cooled and condensed by the constant temperature cold storage ice slurry, and then continues to enter the carbon dioxide booster pump to continue circulating, thereby completing the energy release cycle of the system.

[0066] In a preferred embodiment of the present invention, the maximum pressure of the energy release cycle and the maximum pressure of the heat storage cycle can be adjusted to achieve a liquid or supercritical state during the stage of carbon dioxide expansion and work. The method of the present invention can store energy during off-peak hours using low-peak electricity and release it during peak hours, achieving high energy storage efficiency. It can also utilize solar energy to store heat and cold storage ice slurry to collect and supply cold, achieving high energy utilization.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. An energy utilization system coupling solar thermal storage and carbon dioxide energy storage, characterized in that: include: A carbon dioxide energy storage system, a cold storage tank (13), a heat storage tank (16), a solar collector (14) and a cold storage ice slurry (17); wherein, The carbon dioxide energy storage system includes a cold storage cycle, a heat storage cycle and an energy release cycle; wherein, in the cold storage cycle, the outlet of the first carbon dioxide compressor (1) is connected to the inlet of the first carbon dioxide turbine (3) via the first heat exchange channel of the carbon dioxide heat exchanger (2), and the outlet of the first carbon dioxide turbine (3) is connected to the inlet of the first carbon dioxide compressor (1) via the first heat exchange channel of the carbon dioxide evaporator (4); in the heat storage cycle, the outlet of the second carbon dioxide compressor (6) is connected to the inlet of the second carbon dioxide turbine (8) via the first heat exchange channel of the carbon dioxide cooler (7). ), the outlet of the second carbon dioxide turbine (8) is connected to the inlet of the second carbon dioxide compressor (6) via the second heat exchange channel of the carbon dioxide heat exchanger (2) and the carbon dioxide preheater (5) in sequence; in the energy release cycle, the outlet of the first heat exchange channel of the carbon dioxide condenser (9) is connected to the inlet of the third carbon dioxide turbine (12) via the carbon dioxide booster pump (10) and the first heat exchange channel of the carbon dioxide heater (11) in sequence, and the outlet of the third carbon dioxide turbine (12) is connected to the inlet of the first heat exchange channel of the carbon dioxide condenser (9); The outlet of the cold storage tank (13) is divided into two paths, one path is connected to the inlet of the heat storage tank (16) through the second heat exchange channel of the carbon dioxide cooler (7), and the other path is connected to the inlet of the heat storage tank (16) through the solar collector (14); the outlet of the heat storage tank (16) is connected to the inlet of the cold storage tank (13) through the second heat exchange channel of the carbon dioxide heater (11); The first outlet of the cold storage ice slurry (17) is connected to the first inlet of the cold storage ice slurry (17) through the second heat exchange channel of the carbon dioxide evaporator (4); the second outlet of the cold storage ice slurry (17) is connected to the second inlet of the cold storage ice slurry (17) through the second heat exchange channel of the carbon dioxide condenser (9).

2. The energy utilization system coupled with solar thermal storage and carbon dioxide energy storage according to claim 1, characterized in that: Also included: a mixer (15); wherein, The outlet of the cold storage tank (13) is divided into two paths, one path is connected to the inlet of the heat storage tank (16) through the second heat exchange channel of the carbon dioxide cooler (7), and the other path is connected to the inlet of the heat storage tank (16) through the solar collector (14). Specifically, The outlet of the cold storage tank (13) is divided into two paths, one path is connected to the first inlet of the mixer (15) through the second heat exchange channel of the carbon dioxide cooler (7), and the other path is connected to the second inlet of the mixer (15) through the solar collector (14). The outlet of the mixer (15) is connected to the inlet of the heat storage tank (16).

3. The energy utilization system coupled with solar thermal storage and carbon dioxide energy storage according to claim 1, characterized in that: Also included: a control valve (18); The outlet of the cold storage tank (13) is connected to the inlet of the solar heat collector (14) via the control valve (18).

4. The energy utilization system coupled with solar thermal storage and carbon dioxide energy storage according to claim 1, characterized in that: Also includes: a first electric motor and a second electric motor; The first motor and the second motor are respectively used to drive a first carbon dioxide compressor (1) and a second carbon dioxide compressor (6) using off-peak electricity.

5. The energy utilization system coupled with solar thermal storage and carbon dioxide energy storage according to claim 1, characterized in that: Also includes: a first generator, a second generator, and a third generator; The first generator, the second generator and the third generator are used to generate electricity under the drive of the first carbon dioxide turbine (3), the second carbon dioxide turbine (8) and the third carbon dioxide turbine (12), respectively.

6. The energy utilization system coupled with solar thermal storage and carbon dioxide energy storage according to claim 1, characterized in that: The cold storage ice slurry (17) is a constant temperature cold storage ice slurry.

7. The energy utilization system coupled with solar thermal storage and carbon dioxide energy storage according to claim 1, characterized in that: In the heat storage cycle, the working fluid at the inlet of the second carbon dioxide compressor (6) is superheated gaseous carbon dioxide, and the working fluid at the outlet of the second carbon dioxide compressor (6) is supercritical carbon dioxide; the working fluid at the inlet of the second carbon dioxide turbine (8) is supercritical or subcooled liquid carbon dioxide, and the working fluid at the outlet of the second carbon dioxide turbine (8) is gas-liquid coexisting carbon dioxide. After passing through the carbon dioxide heat exchanger (2) and absorbing heat in the cold storage cycle, the working fluid is converted into saturated gaseous carbon dioxide, and the saturated gaseous carbon dioxide enters the carbon dioxide preheater (5) to absorb heat and be converted into superheated gaseous carbon dioxide.

8. The energy utilization system coupled with solar thermal storage and carbon dioxide energy storage according to claim 1, characterized in that: In the cold storage cycle, the working medium at the inlet of the first carbon dioxide compressor (1) is saturated gaseous carbon dioxide, and the working medium at the outlet of the first carbon dioxide compressor (1) is superheated gaseous carbon dioxide. After the working medium passes through the carbon dioxide heat exchanger (2) and transfers heat to the cold storage cycle, it is converted into saturated liquid carbon dioxide. The saturated liquid carbon dioxide enters the first carbon dioxide turbine (3) to expand and perform work, and then the working medium is converted into a gas-liquid coexistence state and enters the carbon dioxide evaporator (4) to absorb heat and be converted into saturated gaseous carbon dioxide.

9. The energy utilization system coupled with solar thermal storage and carbon dioxide energy storage according to claim 1, characterized in that: In the energy release cycle, the inlet of the carbon dioxide booster pump (10) is saturated liquid carbon dioxide, and the outlet of the carbon dioxide booster pump (10) is supercooled liquid carbon dioxide; the supercooled liquid carbon dioxide enters the carbon dioxide heater (11) to absorb the heat stored in the heat storage cycle, and then the working medium is converted into supercritical carbon dioxide and enters the carbon dioxide third turbine (12) to expand and perform work; after the expansion and performance, the working medium is converted into superheated gaseous carbon dioxide and enters the carbon dioxide condenser (9) to absorb the cold energy in the cold storage ice slurry (17) and then converted into saturated liquid carbon dioxide.

10. An energy utilization method coupling solar thermal storage and carbon dioxide energy storage, characterized in that: Based on the energy utilization system according to any one of claims 1 to 9, the energy utilization method comprises the following steps: When the user is in a low electricity consumption period, the energy storage part of the energy utilization system starts to work. During the energy storage process, the heat storage cycle and the cold storage cycle work simultaneously; wherein, the gaseous carbon dioxide enters the first carbon dioxide compressor (1) and is compressed by the electricity in the low electricity consumption period so that the carbon dioxide is pressurized and heated. After the carbon dioxide is pressurized and heated, it enters the carbon dioxide heat exchanger (2) and exchanges heat with the low-temperature carbon dioxide in the heat storage cycle to cool down. The cooled high-pressure and low-temperature carbon dioxide enters the first carbon dioxide turbine (3) to expand and do work. The carbon dioxide at the outlet of the first carbon dioxide turbine (3) enters the carbon dioxide evaporator (4) to evaporate and absorb heat. The cold energy absorbed by the evaporation comes from the cold storage ice slurry (17); the gaseous carbon dioxide after evaporation and absorption of heat enters the first carbon dioxide turbine (3) to expand and do work. A compressor (1) completes a cold storage cycle; gaseous carbon dioxide enters a second carbon dioxide compressor (6) and is compressed using electricity during a low-peak period to increase the pressure and temperature of the carbon dioxide. After the pressure and temperature are increased, the carbon dioxide enters a carbon dioxide cooler (7) and exchanges heat with a low-temperature medium from a cold storage tank (13) to reduce the temperature. The high-pressure and low-temperature carbon dioxide after heat exchange and reduction enters a second carbon dioxide turbine (8) to expand and perform work. The carbon dioxide at the outlet of the second carbon dioxide turbine (8) enters a carbon dioxide heat exchanger (2) to absorb heat from the cold storage cycle and evaporate. The evaporated gaseous carbon dioxide enters a carbon dioxide preheater (5) to exchange heat with the environment to increase the temperature. The heated carbon dioxide enters the second carbon dioxide compressor (6), completing a heat storage cycle. When there is sufficient sunshine, the flow rate of the working fluid entering the solar heat collector (14) is adjusted to collect the heat of the solar energy and finally store it in the heat storage tank (16); when there is insufficient sunshine, the heat storage tank (16) only stores the heat generated by the heat exchange in the carbon dioxide cooler (7); When the user is at the peak of electricity consumption, the energy release part of the energy utilization system starts to work; wherein, low-temperature and low-pressure carbon dioxide enters the carbon dioxide booster pump (10) and is pressurized to the target pressure, then enters the carbon dioxide heater (11) and exchanges heat with the high-temperature medium from the heat storage tank (16) to increase the temperature, and the low-temperature medium generated after the heat exchange is returned to the cold storage tank (13) for storage, and the carbon dioxide after heat exchange and temperature increase enters the carbon dioxide third turbine (12) to expand and perform external work, and the carbon dioxide at the outlet of the carbon dioxide third turbine (12) enters the carbon dioxide condenser (9) to exchange heat with the cold storage ice slurry (17), and enters the carbon dioxide booster pump (10) after being cooled and condensed by the cold storage ice slurry (17), thereby completing the energy release cycle.

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