Carbon dioxide energy storage system capable of reducing energy waste and control method thereof

Abstract

The present invention discloses a carbon dioxide energy storage system and a control method thereof that can reduce energy waste. The carbon dioxide energy storage system includes a first gas temporary storage unit connected between the first energy storage heat exchanger of the energy storage component and the shaft seal gas supply component, and a second gas temporary storage unit connected between the second compressor of the energy storage component and the energy release component. The first gas temporary storage unit receives and stores the carbon dioxide gas output by the first energy storage heat exchanger during the startup and shutdown stages of the energy storage component, and inputs the stored carbon dioxide gas to the shaft seal gas supply component; the second gas temporary storage unit receives and stores the carbon dioxide gas output from the second compressor during the startup and shutdown stages of the energy storage component, and inputs the stored carbon dioxide gas to the energy release component during the startup stage of the energy release component. The solution of the present invention can recycle and reuse the energy lost during the start-up and shutdown process of the compressor, thereby improving the energy utilization rate of the system and reducing operating costs.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide energy storage, and in particular to a carbon dioxide energy storage system capable of reducing energy waste and a control method thereof. Background Art

[0002] At present, energy storage technology based on the carbon dioxide gas-liquid phase change cycle compresses and condenses the gaseous carbon dioxide at room temperature and pressure in the gas storage unit into liquid carbon dioxide and stores it in the liquid storage unit by using excess electricity or clean energy during the low-power consumption period, and stores the heat energy generated during the compression process. During the peak power consumption period, the stored heat energy is used to heat the liquid carbon dioxide to gas. The gaseous carbon dioxide drives the turbine to drive the generator to generate electricity, and the gaseous carbon dioxide after work returns to the gas storage unit for recycling. It has the advantages of simple structure, flexible layout, and high energy storage efficiency, and has gradually attracted widespread attention.

[0003] The compressor in the energy storage assembly is the core component of the carbon dioxide energy storage system. During the actual operation of the carbon dioxide energy storage system, the compressor faces the challenge of frequent start-stop conditions, and its start-stop frequency is almost once a day. During the startup and shutdown process of the compressor, the pressure at the compressor outlet is lower than the pressure of the condenser, resulting in the high-temperature carbon dioxide gas at the compressor outlet being unable to smoothly enter the condenser for condensation and liquefaction and then storage. In order to ensure the safe and stable operation of the compressor during the startup and shutdown process, and to avoid faults such as surge, according to existing conventional designs, an anti-surge valve is usually connected between the outlet and inlet of the compressor. During the startup and shutdown process of the compressor, the anti-surge valve is opened, so that the high-pressure carbon dioxide gas at the outlet of the compressor is forced to flow back to the inlet of the compressor, and circulates in the loop formed by the compressor and the anti-surge valve, thereby maintaining the minimum safety flow required by the compressor, thereby ensuring that the compressor can smoothly complete the startup and shutdown process.

[0004] However, the energy carried by the CO2 gas flowing back through the anti-surge valve cannot be effectively utilized, resulting in energy waste. Furthermore, given the frequent daily start-stopping of the CO2 energy storage system's compressor, the cumulative energy loss is considerable, seriously impacting the overall operational efficiency and economic benefits of the compressed CO2 energy storage power station. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention provides a carbon dioxide energy storage system and a control method thereof that can reduce energy waste, so as to solve the problem of how to recycle the energy lost during the startup and shutdown processes of the compressor and thus reduce operating costs.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A carbon dioxide energy storage system capable of reducing energy waste comprises a gas storage unit, an energy storage assembly, a liquid storage unit, and an energy release assembly connected in a closed loop. The carbon dioxide energy storage system further comprises a shaft sealing gas supply assembly, a first gas temporary storage unit, and a second gas temporary storage unit. The energy storage assembly comprises a first compressor, a first energy storage heat exchanger, a second compressor, and a second energy storage heat exchanger connected in sequence. The first gas temporary storage unit is connected between the outlet of the first energy storage heat exchanger and the shaft sealing gas supply assembly, and the second gas temporary storage unit is connected between the outlet of the second compressor and the energy release assembly.

[0008] The first gas temporary storage unit includes a first gas storage container, a first input pipeline, and a first output pipeline. The inlet of the first gas storage container is connected to the outlet end of the first energy storage heat exchanger through the first input pipeline, and the outlet of the first gas storage container is connected to the shaft sealing gas supply assembly through the first output pipeline. A first regulating valve is provided on the first input pipeline, and a first gas supply valve is provided on the first output pipeline.

[0009] The second gas temporary storage unit includes a second gas storage container, a second input pipeline and a second output pipeline. The inlet of the second gas storage container is connected to the outlet of the second compressor through the second input pipeline. The outlet of the second gas storage container is connected to the energy release component through the second output pipeline. The second input pipeline is provided with a second regulating valve, and the second output pipeline is provided with a second gas supply valve.

[0010] The energy release assembly includes an energy release heat exchanger and a turbine connected in sequence. The energy release heat exchanger is connected to the turbine via a first connecting pipe. A third air supply valve is provided on the first connecting pipe at the outlet end of the energy release heat exchanger. A turbine intake valve is provided on the first connecting pipe at the inlet end of the turbine. A bypass pipe is connected between the inlet and outlet ends of the third air supply valve. A third regulating valve is provided on the bypass pipe. The second output pipe is connected to the first connecting pipe between the third air supply valve and the turbine intake valve.

[0011] The first gas temporary storage unit is configured to receive and store the carbon dioxide gas output from the first energy storage heat exchanger during the startup and shutdown stages of the energy storage assembly, and input the stored carbon dioxide gas into the shaft seal gas supply assembly;

[0012] The second gas temporary storage unit is configured to receive and store carbon dioxide gas output from the second compressor during the startup and shutdown stages of the energy storage component, and input the stored carbon dioxide gas into the energy release component during the startup stage of the energy release component.

[0013] In a specific solution, the outlet end of the first energy storage heat exchanger and the inlet end of the first compressor are connected to a first return pipe, and a first anti-surge valve is provided on the first return pipe.

[0014] In a specific solution, the outlet end of the second energy storage heat exchanger and the inlet end of the second compressor are connected to a second return pipe, and a second anti-surge valve is provided on the second return pipe.

[0015] In a specific solution, the second output pipeline is further provided with a first check valve that enables the carbon dioxide gas to flow from the second gas storage container toward the energy release assembly in a one-way direction.

[0016] In a specific solution, a condenser is provided on the connecting pipeline between the energy storage component and the liquid storage unit, the energy storage component is connected to the condenser through a second connecting pipeline, and the second connecting pipeline is provided with a second check valve that enables carbon dioxide gas to flow in one direction from the energy storage component toward the condenser.

[0017] In a specific solution, a liquid pump and an evaporator are sequentially provided on the connecting pipeline between the liquid storage unit and the energy release component. The evaporator is connected to the energy release component through a third connecting pipeline, and a fourth air supply valve is provided on the third connecting pipeline.

[0018] In a specific solution, a fourth connecting pipe is connected between the inlet end of the energy release component and the liquid storage unit, and a fifth air supply valve is provided on the fourth connecting pipe.

[0019] A second aspect of the present invention is to provide a control method for the carbon dioxide energy storage system as described above, the control method comprising the following steps:

[0020] S101. When the energy storage assembly starts to operate, controlling the first gas temporary storage unit to receive and store carbon dioxide gas output from the first energy storage heat exchanger, and controlling the second gas temporary storage unit to receive and store carbon dioxide gas output from the second compressor, until the energy storage assembly enters a stable operation stage;

[0021] S102, when the energy storage assembly is operating stably, controlling the first gas temporary storage unit and the second gas temporary storage unit to stop receiving carbon dioxide gas, so that all the carbon dioxide gas in the energy storage assembly is transported toward the liquid storage unit;

[0022] S103, when the energy storage assembly is shut down for load reduction, controlling the first gas temporary storage unit to receive and store carbon dioxide gas output from the first energy storage heat exchanger, and controlling the second gas temporary storage unit to receive and store carbon dioxide gas output from the second compressor, until the energy storage assembly stops operating;

[0023] S104, when the energy release component starts to operate, controlling the second gas temporary storage unit to input stored carbon dioxide gas into the energy release component, using the stored high-temperature and high-pressure carbon dioxide gas to accelerate the turbine in the energy release component, thereby shortening the startup time of the energy release component;

[0024] During the operation of the carbon dioxide energy storage system, the first gas temporary storage unit is controlled to input the stored carbon dioxide gas into the shaft sealing gas supply assembly as shaft sealing gas.

[0025] In a specific solution, step S101 specifically includes: when the energy storage component starts to operate, gradually opening the first regulating valve and the second regulating valve, and while meeting the operating flow rates of the first compressor and the second compressor, inputting the carbon dioxide gas at the outlet of the first energy storage heat exchanger into the first gas storage container for recovery and storage, and inputting the carbon dioxide gas at the outlet of the second compressor into the second gas storage container for recovery and storage, until the energy storage component enters a stable operation stage, and then closing the first regulating valve and the second regulating valve;

[0026] The step S103 specifically includes: when the energy storage component starts to reduce load and shut down, gradually opening the first regulating valve and the second regulating valve, while meeting the flow requirements when the first compressor and the second compressor are shut down, inputting the carbon dioxide gas at the outlet of the first energy storage heat exchanger into the first gas storage container for recovery and storage, and inputting the carbon dioxide gas at the outlet of the second compressor into the second gas storage container for recovery and storage, until the energy storage component completely stops operating, and then closing the first regulating valve and the second regulating valve.

[0027] In a specific scheme, the step S104 specifically includes: when the energy release component starts to start running, opening the second air supply valve and the turbine intake valve, closing the third air supply valve and the third regulating valve, and inputting the carbon dioxide gas in the second gas storage container into the turbine to drive the turbine to start and increase speed; when the pressure in the second gas storage container is insufficient, gradually opening the third regulating valve and keeping the third air supply valve closed, so that the carbon dioxide gas heated by the energy release heat exchanger is also input into the turbine to continue to start and increase speed; as the load of the turbine gradually increases, when the third regulating valve reaches a fully open state, opening the third air supply valve and closing the third regulating valve and the second air supply valve, so that the energy release component enters a stable operating state.

[0028] An embodiment of the present invention provides a carbon dioxide energy storage system and a control method thereof that can reduce energy waste. The carbon dioxide energy storage system includes a first gas temporary storage unit connected between an energy storage component and a shaft sealing gas supply component, and a second gas temporary storage unit connected between the energy storage component and an energy release component. During the startup and shutdown stages of the energy storage component, the first gas temporary storage unit receives and stores the carbon dioxide gas compressed by the first compressor and cooled by heat exchange in the first energy storage heat exchanger, and the second gas temporary storage unit receives and stores the high-temperature and high-pressure carbon dioxide gas compressed by the second compressor. This can prevent the first and second compressors in the energy storage component from entering surge conditions during the startup and shutdown stages, thereby improving the stability of the energy storage system operation; during the operation of the carbon dioxide energy storage system, the first gas temporary storage unit inputs the stored lower-temperature carbon dioxide gas into the shaft sealing gas supply component as shaft sealing gas, thereby realizing the reuse of the energy carried by this part of the gas; when the energy release component starts to start operation, the second gas temporary storage unit inputs the stored carbon dioxide gas into the energy release component, and uses the stored high-temperature and high-pressure carbon dioxide gas to accelerate the turbine, which not only realizes the reuse of the energy carried by this part of the gas, but also shortens the startup time of the energy release component, thereby improving the operating efficiency of the system. In summary, the carbon dioxide energy storage system and control method thereof applied for in the present invention can recover the energy lost by the compressor during the startup and shutdown processes (the energy carried by the carbon dioxide gas that needs to flow back to avoid compressor surge) and reuse it within the system. This not only avoids wasting energy and improves the energy utilization rate of the system to reduce operating costs, but also shortens the startup time of the energy release component and improves the operating efficiency of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural diagram of a carbon dioxide energy storage system that can reduce energy waste in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] To make the objectives, technical solutions, and advantages of the present invention more apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. Examples of these preferred embodiments are illustrated in the accompanying drawings. The embodiments of the present invention shown in and described with reference to the accompanying drawings are merely exemplary, and the present invention is not limited to these embodiments.

[0031] It should be noted that the same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", etc. indicating directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0032] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, the accompanying drawings only show structures and / or processing steps closely related to the solutions according to the present invention, while other details that are not closely related to the present invention are omitted.

[0033] The embodiment of the present invention provides a carbon dioxide energy storage system that can reduce energy waste, such as Figure 1 As shown, the carbon dioxide energy storage system mainly includes a gas storage unit 10, an energy storage assembly 20, a liquid storage unit 30, and an energy release assembly 40, which are connected in a closed loop. The gas storage unit 10 is used to store gaseous carbon dioxide at normal pressure, and the liquid storage unit 30 is used to store liquid carbon dioxide. The gaseous carbon dioxide flowing out of the gas storage unit 10 is converted into liquid carbon dioxide at a preset energy storage pressure by the energy storage assembly 20 and flows into the liquid storage unit 30, completing energy storage in this process. The liquid carbon dioxide output from the liquid storage unit 30 releases energy through the energy release assembly 40 and is converted into gaseous carbon dioxide at normal pressure, and flows into the gas storage unit 10, completing energy release and application in this process. Typically, the energy storage assembly 20 compresses and liquefies the gaseous carbon dioxide into liquid carbon dioxide during off-peak periods or by utilizing wind and solar power curtailment, and stores the liquid carbon dioxide in the liquid storage unit 30, converting the energy into compression energy and heat energy for storage. During peak periods, the energy release assembly 40 vaporizes and expands the liquid carbon dioxide to produce work, releasing the stored energy and converting it into electrical energy for use.

[0034] The specific structures of the gas storage unit 10, the energy storage assembly 20, the liquid storage unit 30, and the energy release assembly 40 can be implemented with reference to existing technologies. The gas storage unit 10 is also known in the prior art as a gas storage bin, a gas storage reservoir, a gas storage assembly, etc., and the liquid storage unit 30 is also known in the prior art as a liquid storage tank, a liquid storage container, an energy storage container, etc., such as the technical solutions disclosed in existing patent applications CN119289275A, CN116221616A, CN117628836A, and CN116857027A.

[0035] As a specific example, in this embodiment, Figure 1 As shown, the energy storage component 20 mainly includes a first compressor 21, a first energy storage heat exchanger 22, a second compressor 23, and a second energy storage heat exchanger 24 connected between the gas storage unit 10 and the liquid storage unit 30. Furthermore, a condenser 81 is provided on the connecting pipeline between the energy storage component 20 and the liquid storage unit 30. The gaseous carbon dioxide in the gas storage unit 10 is compressed by the first compressor 21, cooled by heat exchange in the first energy storage heat exchanger 22, compressed again by the second compressor 23, cooled by heat exchange in the second energy storage heat exchanger 24, and then liquefied by the condenser 81 to form liquid carbon dioxide stored in the liquid storage unit 30.

[0036] As a specific example, in this embodiment, Figure 1 As shown, the energy release assembly 40 primarily comprises an energy release heat exchanger 41 and a turbine 42 connected between the liquid storage unit 30 and the gas storage unit 10. Furthermore, a liquid pump 31 and an evaporator 32 are sequentially provided in the connecting pipeline between the liquid storage unit 30 and the energy release assembly 40. The liquid carbon dioxide in the liquid storage unit 30 is pressurized by the liquid pump 31 and then fed into the evaporator 32. After being heated and evaporated by the evaporator 32, it is fed into the energy release heat exchanger 41 for further heating and temperature increase. It is then fed into the turbine 42 to perform external work (e.g., generate electricity), releasing energy, and then converted into gaseous carbon dioxide at normal pressure, which is stored in the gas storage unit 10.

[0037] In this embodiment, Figure 1 As shown, the carbon dioxide energy storage system also includes a shaft sealing gas supply assembly 50, which is used to provide shaft sealing gas to the energy storage assembly 20 and the rotating equipment in the energy release assembly 40 during the operation of the carbon dioxide energy storage system. The rotating equipment is, for example, the compressor in the energy storage assembly 20 and the turbine in the energy release assembly 40.

[0038] The compressor in the energy storage assembly 20 is a core component of the carbon dioxide energy storage system. During the energy storage process, when the energy storage assembly 20 begins to operate, the air intake at the compressor inlet needs to be gradually increased, and the gas pressure at the compressor outlet also gradually increases. When the energy storage assembly 20 is scheduled to stop operating, the air intake at the compressor inlet needs to be gradually reduced, and the gas pressure at the compressor outlet also gradually decreases. Because the liquid storage unit 30 itself, the condenser 81 connected to the inlet of the liquid storage unit 30, and the delivery pipeline all have a certain pressure, when the gas pressure at the compressor outlet (the output end of the energy storage assembly 20) does not exceed the pressure of the condenser 81, the carbon dioxide gas output by the energy storage assembly 20 cannot be delivered to the liquid storage unit 30. Therefore, during the startup and shutdown stages of the energy storage assembly 20, the compressor in the energy storage assembly 20 is prone to surge. To prevent the compressor from entering a surge condition, an anti-surge valve is typically connected between the compressor's outlet and inlet. This forces high-pressure carbon dioxide gas at the compressor's outlet to flow back to the compressor's inlet, where it circulates within the loop formed by the compressor and the anti-surge valve. This maintains the minimum safe flow required by the compressor, ensuring smooth startup and shutdown. However, the energy carried by the carbon dioxide gas flowing back through the anti-surge valve cannot be effectively utilized, resulting in energy waste.

[0039] In order to solve the above problems, in the carbon dioxide energy storage system provided in this embodiment, refer to Figure 1 The carbon dioxide energy storage system further includes a first gas temporary storage unit 60 and a second gas temporary storage unit 70. The first gas temporary storage unit 60 is connected between the outlet of the first energy storage heat exchanger 22 and the shaft seal gas supply assembly 50, and the second gas temporary storage unit 70 is connected between the outlet of the second compressor 23 and the energy release assembly 40.

[0040] The first gas temporary storage unit 60 is configured to receive and store carbon dioxide gas output from the first energy storage heat exchanger 22 during the startup and shutdown phases of the energy storage assembly 20, and input the stored carbon dioxide gas into the shaft seal gas supply assembly 50. The second gas temporary storage unit 70 is configured to receive and store carbon dioxide gas output from the second compressor 23 during the startup and shutdown phases of the energy storage assembly 20, and input the stored carbon dioxide gas into the energy release assembly 40 during the startup phase of the energy release assembly 40.

[0041] Specifically, during the startup and shutdown phases of the energy storage assembly 20, the first gas temporary storage unit 60 receives and stores carbon dioxide gas compressed by the first compressor 21 and cooled by the first energy storage heat exchanger 22, and the second gas temporary storage unit 70 receives and stores high-temperature, high-pressure carbon dioxide gas compressed by the second compressor 23. This prevents the first and second compressors 21, 23 in the energy storage assembly 20 from entering surge conditions during the startup and shutdown phases, thereby improving the operational stability of the energy storage system. During the operation of the carbon dioxide energy storage system, the first gas temporary storage unit 60 inputs the stored relatively low-temperature carbon dioxide gas into the shaft seal gas supply assembly 50 as shaft seal gas, thereby reusing the energy carried by this portion of gas. When the energy release assembly 40 begins to start operating, the second gas temporary storage unit 70 inputs the stored carbon dioxide gas into the energy release assembly 40, utilizing the stored high-temperature, high-pressure carbon dioxide gas to accelerate the turbine 42. This not only recycles the energy carried by this portion of gas, but also shortens the startup time of the energy release assembly 40, thereby improving the operational efficiency of the system. To sum up, the carbon dioxide energy storage system of the present application can recover the energy lost by the compressor during the startup and shutdown processes. This part of energy refers to the energy carried by the carbon dioxide gas that needs to flow back to avoid compressor surge, and the recovered energy can be reused within the system. It can not only avoid wasting energy and improve the energy utilization rate of the system to reduce operating costs, but also shorten the startup time of the energy release component and improve the operating efficiency of the system.

[0042] It should be noted that the specific duration of the startup phase and shutdown phase of the energy storage component 20 needs to be specifically set according to the actual operating conditions of the energy storage component 20, so as to meet the basic requirement of preventing the compressor in the energy storage component 20 from entering a surge condition.

[0043] In specific plans, such as Figure 1As shown, the first gas temporary storage unit 60 includes a first gas storage container 61, a first input pipeline 62, and a first output pipeline 63. The inlet of the first gas storage container 61 is connected to the outlet of the first energy storage heat exchanger 22 through the first input pipeline 62, and the outlet of the first gas storage container 61 is connected to the shaft seal gas supply assembly 50 through the first output pipeline 63. A first regulating valve 64 is provided on the first input pipeline 62, and a first gas supply valve 65 is provided on the first output pipeline 63. The second gas temporary storage unit 70 includes a second gas storage container 71, a second input pipeline 72, and a second output pipeline 73. The inlet of the second gas storage container 71 is connected to the outlet of the second compressor 23 through the second input pipeline 72, and the outlet of the second gas storage container 71 is connected to the energy release assembly 40 through the second output pipeline 73. A second regulating valve 74 is provided on the second input pipeline 72, and a second gas supply valve 75 is provided on the second output pipeline 73.

[0044] Furthermore, the second output pipe 73 is further provided with a first check valve 76 that enables the carbon dioxide gas to flow from the second gas storage container 71 toward the energy release assembly 40 in a one-way manner.

[0045] When the energy storage assembly 20 begins operation, the carbon dioxide gas stored in the gas storage unit 10 enters the inlet of the first compressor 21 (low-pressure compressor), where it is pressurized and heated by the first compressor 21. After cooling by the first energy storage heat exchanger 22, the carbon dioxide gas is regulated by the first regulating valve 64 and stored in the first gas storage container 61, while meeting the operating flow rate of the first compressor 21. Energy at the outlet of the first compressor 21 is recovered. Simultaneously, the carbon dioxide gas at the outlet of the first compressor 21 enters the inlet of the second compressor 23 (high-pressure compressor), where it is pressurized and heated to high-temperature and high-pressure carbon dioxide gas. After adjustment by the second regulating valve 74, the high-temperature and high-pressure carbon dioxide gas is stored in the second gas storage container 71, while meeting the operating flow rate of the second compressor 23. Energy at the outlet of the second compressor 23 is recovered. The energy storage mode continues to load, with the first regulating valve 64 and the second regulating valve 74 controlling the flow rates of the first compressor 21 and the second compressor 23, respectively, to meet the operating load requirements. This continues until the pressure of the carbon dioxide gas at the outlet of the second compressor 23 exceeds the pressure of the condenser 81. The high-temperature, high-pressure carbon dioxide gas passes through the second energy storage heat exchanger 24 for heat exchange and cooling, then enters the condenser 81 to begin liquefaction. The liquefied carbon dioxide is then stored in the liquid storage unit 30. At this point, the first regulating valve 64 and the second regulating valve 74 are gradually closed, and the unit enters a stable energy storage mode. The low-temperature carbon dioxide gas stored in the first gas storage container 61 can be delivered to the shaft seal gas supply assembly 50 via the first gas supply valve 65 as shaft seal gas.

[0046] When the energy storage condition is unloaded and the machine is shut down, the first regulating valve 64 and the second regulating valve 74 are gradually opened. When the flow requirements of the first compressor 21 and the second compressor 23 are met when they are shut down, the low-temperature and low-pressure carbon dioxide gas at the outlet of the first compressor 21 enters the first gas storage container 61, and the high-temperature and high-pressure carbon dioxide gas at the outlet of the second compressor 23 enters the second gas storage container 71. Energy is recovered and stored during the unloading process of the energy storage condition until the first compressor 21 and the second compressor 23 completely stop running. At this time, the first regulating valve 64 and the second regulating valve 74 are closed.

[0047] When the energy storage condition ends, the energy release condition begins, that is, when the energy release component 40 starts to start operation, the second gas supply valve 75 is opened, and the high-temperature and high-pressure carbon dioxide gas stored in the second gas storage container 71 is input into the energy release component 40, driving the turbine 42 in the energy release component 40 to start and increase speed.

[0048] Furthermore, in this embodiment, if Figure 1As shown, the outlet end of the first energy storage heat exchanger 22 and the inlet end of the first compressor 21 are connected to a first return pipe 25, and a first anti-surge valve 26 is provided on the first return pipe 25. The outlet end of the second energy storage heat exchanger 24 and the inlet end of the second compressor 23 are connected to a second return pipe 27, and a second anti-surge valve 28 is provided on the second return pipe 27.

[0049] Among them, the first anti-surge valve 26 and the second anti-surge valve 28 remain in a closed state during the normal start and stop process of the energy storage component 20, and are only temporarily opened when the corresponding compressor operating flow is insufficient and deviates from the operating point or under emergency conditions to meet the safe operation requirements of the compressor.

[0050] In this embodiment, Figure 1 As shown, in the energy release assembly 40, the energy release heat exchanger 41 is connected to the turbine 42 via a first connecting pipe 43. A third air supply valve 44 is provided on the first connecting pipe 43 at the outlet end of the energy release heat exchanger 41. A turbine intake valve 45 is provided on the first connecting pipe 43 at the inlet end of the turbine 42. The second output pipe 73 is connected to the first connecting pipe 43 between the third air supply valve 44 and the turbine intake valve 45. Furthermore, a bypass pipe 46 is connected between the inlet and outlet ends of the third air supply valve 44, and a third regulating valve 47 is provided on the bypass pipe 46.

[0051] During the initial startup phase of the energy release assembly 40, the second gas supply valve 75 and the turbine inlet valve 45 are opened. The high-temperature, high-pressure carbon dioxide gas in the second gas storage container 71 is sequentially fed into the turbine 42 through the second gas supply valve 75, the first check valve 76, and the turbine inlet valve 45, driving the turbine 42 to accelerate and increase speed. When the pressure in the second gas storage container 71 becomes insufficient, the third regulating valve 47 is gradually opened (while the third gas supply valve 44 is closed), allowing the carbon dioxide gas heated by the energy release heat exchanger 41 to be fed into the turbine 42 to continue accelerating and increasing speed. Due to the presence of the first check valve 76, when the pressure in the turbine 42 inlet pipeline exceeds that of the second gas storage container 71, the second gas storage container 71 automatically stops supplying gas, closing the second gas supply valve 75. As the load of the turbine 42 gradually increases, the third regulating valve 47 reaches a fully open state. At this time, the third air supply valve 44 at the outlet of the energy-releasing heat exchanger 41 is opened, and the third regulating valve 47 is closed, and the unit enters a stable energy-releasing power generation operation state.

[0052] A third regulating valve 47 is provided in parallel with the third air supply valve 44 at the outlet of the energy-releasing heat exchanger 41, serving as a regulating device. When the air source in the inlet pipe of the turbine 42 is switched, the pressure can be maintained stable, thereby preventing speed fluctuations in the turbine 42. When the third regulating valve 47 is fully opened, the third air supply valve 44 is switched to fully open, thereby reducing throttling losses.

[0053] In this embodiment, Figure 1 As shown, the energy storage assembly 20 is connected to the condenser 81 via a second connecting pipe 82 , and the second connecting pipe 82 is provided with a second check valve 83 that enables carbon dioxide gas to flow from the energy storage assembly 20 toward the condenser 81 in one direction.

[0054] In this embodiment, Figure 1 As shown, the evaporator 32 is connected to the energy release assembly 40 via a third connecting pipe 33, which is provided with a fourth gas supply valve 34. Furthermore, a fourth connecting pipe 35 is connected between the inlet end of the energy release assembly 40 and the liquid storage unit 30, and a fifth gas supply valve 36 is provided on the fourth connecting pipe 35. The fifth gas supply valve 36 acts as a pressure-maintaining valve. During the energy release process, as the liquid storage unit 30 continuously supplies liquid carbon dioxide, the pressure decreases. At this time, carbon dioxide gas is supplied to the liquid storage unit 30 through the fifth gas supply valve 36, thereby maintaining a stable pressure in the liquid storage unit 30.

[0055] Based on the carbon dioxide energy storage system that can reduce energy waste provided in the above embodiment, an embodiment of the present invention further provides a control method for the carbon dioxide energy storage system, the control method comprising the following steps:

[0056] Step S101: When the energy storage assembly 20 starts to operate, the first gas temporary storage unit 60 is controlled to receive and store the carbon dioxide gas output from the first energy storage heat exchanger 22, and the second gas temporary storage unit 70 is controlled to receive and store the carbon dioxide gas output from the second compressor 23 until the energy storage assembly 20 enters a stable operation stage.

[0057] Step S102 : When the energy storage assembly 20 is operating stably, controlling the first gas temporary storage unit 60 and the second gas temporary storage unit 70 to stop receiving carbon dioxide gas, so that all the carbon dioxide gas in the energy storage assembly 20 is transported toward the liquid storage unit 30 .

[0058] Step S103: When the energy storage assembly 20 is shut down and operating under load reduction, the first gas temporary storage unit 60 is controlled to receive and store the carbon dioxide gas output from the first energy storage heat exchanger 22, and the second gas temporary storage unit 70 is controlled to receive and store the carbon dioxide gas output from the second compressor 23 until the energy storage assembly 20 stops operating.

[0059] Step S104: When the energy release component 40 starts to start running, control the second gas temporary storage unit 70 to input the stored carbon dioxide gas into the energy release component 40, and use the stored high-temperature and high-pressure carbon dioxide gas to accelerate the turbine 42 in the energy release component 40 to shorten the startup time of the energy release component 40.

[0060] During the operation of the carbon dioxide energy storage system, the first gas temporary storage unit 60 is controlled to input the stored carbon dioxide gas into the shaft sealing gas supply assembly 50 as shaft sealing gas.

[0061] In the specific plan, combined with Figure 1 As shown, in step S101: when the energy storage component 20 starts to start operation, the first regulating valve 64 and the second regulating valve 74 are gradually opened, and when the operating flow rates of the first compressor 21 and the second compressor 23 are met, the low-temperature carbon dioxide gas at the outlet of the first energy storage heat exchanger 22 is input into the first gas storage container 61 for recovery and storage, and the high-temperature and high-pressure carbon dioxide gas at the outlet of the second compressor 23 is input into the second gas storage container 71 for recovery and storage, until the energy storage component 20 enters the stable operation stage, and then the first regulating valve 64 and the second regulating valve 74 are closed.

[0062] In the specific plan, combined with Figure 1 As shown, in step S103: when the energy storage component 20 starts to reduce load and shut down, the first regulating valve 64 and the second regulating valve 74 are gradually opened, and under the condition that the flow requirements when the first compressor 21 and the second compressor 23 are shut down are met, the low-temperature carbon dioxide gas at the outlet of the first compressor 21 is input into the first gas storage container 61 for recovery and storage, and the high-temperature and high-pressure carbon dioxide gas at the outlet of the second compressor 23 is input into the second gas storage container 71 for recovery and storage, until the energy storage component 20 completely stops running, and then the first regulating valve 64 and the second regulating valve 74 are closed.

[0063] In the specific plan, combined with Figure 1As shown, in step S104, when the energy release assembly 40 begins to operate, the second air supply valve 75 and the turbine inlet valve 45 are opened, and the third air supply valve 44 and the third regulating valve 47 are closed. High-temperature, high-pressure carbon dioxide gas from the second gas storage container 71 is fed into the turbine 42, driving the turbine 42 to accelerate and increase speed. When the pressure in the second gas storage container 71 is insufficient, the third regulating valve 47 is gradually opened while the third air supply valve 44 remains closed, allowing the carbon dioxide gas heated by the energy release heat exchanger 41 to be fed into the turbine 42 to continue accelerating and increasing speed. As the load on the turbine 42 gradually increases, when the third regulating valve 47 reaches full open, the third air supply valve 44 is opened, and the third regulating valve 47 and the second air supply valve 75 are closed, allowing the energy release assembly 40 to enter stable operation.

[0064] In summary, the carbon dioxide energy storage system and control method provided in the above embodiments of the present invention recover the energy lost by the compressor during startup and shutdown (the energy carried by the carbon dioxide gas that needs to flow back to avoid compressor surge) and reuse it within the system. This not only avoids wasting energy and improves the energy utilization rate of the system to reduce operating costs, but also shortens the startup time of the energy release component and improves the operating efficiency of the system.

[0065] The above is only a specific implementation method of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A carbon dioxide energy storage system capable of reducing energy waste, comprising a gas storage unit, an energy storage component, a liquid storage unit, and an energy release component connected in a closed loop, characterized in that: The carbon dioxide energy storage system further includes a shaft sealing gas supply assembly, a first gas temporary storage unit, and a second gas temporary storage unit. The energy storage assembly includes a first compressor, a first energy storage heat exchanger, a second compressor, and a second energy storage heat exchanger connected in sequence. The first gas temporary storage unit is connected between the outlet end of the first energy storage heat exchanger and the shaft sealing gas supply assembly, and the second gas temporary storage unit is connected between the outlet end of the second compressor and the energy release assembly. The first gas temporary storage unit includes a first gas storage container, a first input pipeline, and a first output pipeline. The inlet of the first gas storage container is connected to the outlet end of the first energy storage heat exchanger through the first input pipeline, and the outlet of the first gas storage container is connected to the shaft sealing gas supply assembly through the first output pipeline. A first regulating valve is provided on the first input pipeline, and a first gas supply valve is provided on the first output pipeline. The second gas temporary storage unit includes a second gas storage container, a second input pipeline and a second output pipeline. The inlet of the second gas storage container is connected to the outlet of the second compressor through the second input pipeline. The outlet of the second gas storage container is connected to the energy release component through the second output pipeline. The second input pipeline is provided with a second regulating valve, and the second output pipeline is provided with a second gas supply valve. The energy release assembly includes an energy release heat exchanger and a turbine connected in sequence. The energy release heat exchanger is connected to the turbine via a first connecting pipe. A third air supply valve is provided on the first connecting pipe at the outlet end of the energy release heat exchanger. A turbine intake valve is provided on the first connecting pipe at the inlet end of the turbine. A bypass pipe is connected between the inlet and outlet ends of the third air supply valve. A third regulating valve is provided on the bypass pipe. The second output pipe is connected to the first connecting pipe between the third air supply valve and the turbine intake valve. The first gas temporary storage unit is configured to receive and store the carbon dioxide gas output from the first energy storage heat exchanger during the startup and shutdown stages of the energy storage assembly, and input the stored carbon dioxide gas into the shaft seal gas supply assembly; The second gas temporary storage unit is configured to receive and store carbon dioxide gas output from the second compressor during the startup and shutdown stages of the energy storage component, and input the stored carbon dioxide gas into the energy release component during the startup stage of the energy release component.

2. The carbon dioxide energy storage system according to claim 1, characterized in that: The outlet end of the first energy storage heat exchanger and the inlet end of the first compressor are connected to a first return pipe, and a first anti-surge valve is provided on the first return pipe.

3. The carbon dioxide energy storage system according to claim 1, characterized in that: The outlet end of the second energy storage heat exchanger and the inlet end of the second compressor are connected to a second return pipe, and a second anti-surge valve is provided on the second return pipe.

4. The carbon dioxide energy storage system according to claim 1, characterized in that: The second output pipeline is further provided with a first check valve that enables carbon dioxide gas to flow from the second gas storage container toward the energy release assembly in a one-way direction.

5. The carbon dioxide energy storage system according to any one of claims 1 to 4, characterized in that: A condenser is provided on the connecting pipeline between the energy storage assembly and the liquid storage unit. The energy storage assembly is connected to the condenser through a second connecting pipeline. The second connecting pipeline is provided with a second check valve that allows carbon dioxide gas to flow from the energy storage assembly toward the condenser in one direction.

6. The carbon dioxide energy storage system according to any one of claims 1 to 4, characterized in that: A liquid pump and an evaporator are sequentially arranged on the connecting pipeline between the liquid storage unit and the energy release component. The evaporator is connected to the energy release component through a third connecting pipeline. A fourth air supply valve is arranged on the third connecting pipeline.

7. The carbon dioxide energy storage system according to claim 6, characterized in that: A fourth connecting pipe is connected between the inlet end of the energy release component and the liquid storage unit, and a fifth air supply valve is provided on the fourth connecting pipe.

8. A control method for a carbon dioxide energy storage system capable of reducing energy waste according to any one of claims 1 to 7, characterized in that: The control method comprises the following steps: S101. When the energy storage assembly starts to operate, controlling the first gas temporary storage unit to receive and store carbon dioxide gas output from the first energy storage heat exchanger, and controlling the second gas temporary storage unit to receive and store carbon dioxide gas output from the second compressor, until the energy storage assembly enters a stable operation stage; S102, when the energy storage assembly is operating stably, controlling the first gas temporary storage unit and the second gas temporary storage unit to stop receiving carbon dioxide gas, so that all the carbon dioxide gas in the energy storage assembly is transported toward the liquid storage unit; S103, when the energy storage assembly is shut down for load reduction, controlling the first gas temporary storage unit to receive and store carbon dioxide gas output from the first energy storage heat exchanger, and controlling the second gas temporary storage unit to receive and store carbon dioxide gas output from the second compressor, until the energy storage assembly stops operating; S104, when the energy release component starts to operate, controlling the second gas temporary storage unit to input stored carbon dioxide gas into the energy release component, using the stored high-temperature and high-pressure carbon dioxide gas to accelerate the turbine in the energy release component, thereby shortening the startup time of the energy release component; During the operation of the carbon dioxide energy storage system, the first gas temporary storage unit is controlled to input the stored carbon dioxide gas into the shaft sealing gas supply assembly as shaft sealing gas.

9. The control method according to claim 8, characterized in that: The step S101 specifically includes: when the energy storage assembly starts to operate, gradually opening the first regulating valve and the second regulating valve, and while meeting the operating flow rates of the first compressor and the second compressor, inputting the carbon dioxide gas at the outlet of the first energy storage heat exchanger into the first gas storage container for recovery and storage, and inputting the carbon dioxide gas at the outlet of the second compressor into the second gas storage container for recovery and storage, until the energy storage assembly enters a stable operation stage, and then closing the first regulating valve and the second regulating valve; The step S103 specifically includes: when the energy storage component starts to reduce load and shut down, gradually opening the first regulating valve and the second regulating valve, while meeting the flow requirements when the first compressor and the second compressor are shut down, inputting the carbon dioxide gas at the outlet of the first energy storage heat exchanger into the first gas storage container for recovery and storage, and inputting the carbon dioxide gas at the outlet of the second compressor into the second gas storage container for recovery and storage, until the energy storage component completely stops operating, and then closing the first regulating valve and the second regulating valve.

10. The control method according to claim 9, characterized in that: The step S104 specifically includes: when the energy release component starts to start running, opening the second air supply valve and the turbine intake valve, closing the third air supply valve and the third regulating valve, and inputting the carbon dioxide gas in the second gas storage container into the turbine to drive the turbine to start and increase speed; when the pressure in the second gas storage container is insufficient, gradually opening the third regulating valve and keeping the third air supply valve closed, so that the carbon dioxide gas heated by the energy release heat exchanger is also input into the turbine to continue to start and increase speed; as the load of the turbine gradually increases, when the third regulating valve reaches a fully open state, opening the third air supply valve and closing the third regulating valve and the second air supply valve, so that the energy release component enters a stable operating state.

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