A multi-mode carbon dioxide energy storage system and a control method thereof

Abstract

The application provides a multi-mode carbon dioxide energy storage system and a control method thereof, which comprises: an energy storage pipeline, which comprises a self-cooling pipeline suitable for expanding and cooling carbon dioxide and a cooling tower pipeline suitable for heat exchange and cooling of carbon dioxide with a cooling tower; and a control structure arranged on the energy storage pipeline and suitable for guiding carbon dioxide into the self-cooling pipeline or the cooling tower pipeline. The control structure is arranged so that the energy storage system can freely switch the carbon dioxide to flow through the self-cooling pipeline in a self-cooling mode and the cooling tower pipeline in a cooling tower cooling mode, and the self-cooling and the cooling tower cooling are respectively performed, so that the two cooling modes are reasonably selected. In a conventional case, the self-cooling mode is adopted when the requirement for the energy storage system efficiency is not high or the weather is hot, and the cooling tower cooling mode is adopted when the requirement for the energy storage system efficiency is high or the weather is cool, so that the energy storage system efficiency can be obviously improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon dioxide energy storage, in particular to a multi-mode carbon dioxide energy storage system and a control method thereof. BACKGROUND

[0002] For large-scale energy storage systems, traditional physical energy storage methods such as pumped storage and compressed gas storage are the most widely used energy storage technologies at present, but pumped storage and compressed air storage have high requirements for geographical site selection, and there are certain limitations in popularization and use. Carbon dioxide energy storage system is a potential energy storage system. From the physical properties, carbon dioxide has the advantages of good environmental performance, excellent thermal properties, high gas flow density, good thermal conductivity, low liquid viscosity, and low critical parameters, so that liquid carbon dioxide can be stored at a relatively high temperature, thereby greatly reducing the storage space of carbon dioxide and facilitating the layout and popularization of carbon dioxide energy storage system.

[0003] The carbon dioxide energy storage system in the prior art usually adopts two energy storage modes when converting gaseous carbon dioxide into liquid carbon dioxide energy storage: the first mode is to use an external cooling tower to condense carbon dioxide working medium by setting up a mechanical ventilation cooling tower and the like, which has the advantage of high energy storage system efficiency, but is greatly affected by the environment, for example, as summer approaches, the weather gradually becomes hot. The water temperature of the cooling tower is often high, which affects the condensation effect; the second mode is to use carbon dioxide self-cooling to cool the working medium by means of carbon dioxide expansion cooling, which has the advantages of no need for cooling medium, no consumption of water resources, no influence of environmental parameters, and small occupation area, but reduces the energy storage system efficiency to some extent. SUMMARY

[0004] Therefore, the technical problem to be solved by the present application is to overcome the defects that the energy storage mode using an external cooling tower in the prior art is greatly affected by the environment, and the energy storage system efficiency is low when using the carbon dioxide self-cooling energy storage mode.

[0005] To this end, the present application provides a multi-mode carbon dioxide energy storage system, comprising:

[0006] A gas storage tank and a liquid storage tank adapted to store gaseous carbon dioxide and liquid carbon dioxide, respectively;

[0007] An energy storage pipeline and an energy release pipeline respectively communicating with the gas storage tank and the liquid storage tank;

[0008] A liquefaction assembly and a gasification assembly respectively arranged on the energy storage pipeline and the energy release pipeline, the liquefaction assembly being adapted to liquefy carbon dioxide energy storage, and the gasification assembly being adapted to gasify carbon dioxide to release energy;

[0009] A cold storage tank and a hot storage tank, adapted to store cold heat exchange medium and hot heat exchange medium respectively;

[0010] A supercooling pipeline, sealingly connecting the cold storage tank and the hot storage tank, the supercooling pipeline being adapted to guide the cold heat exchange medium;

[0011] At least one first heat exchanger, being heat-exchangeably arranged between the energy storage pipeline and the supercooling pipeline;

[0012] The energy storage pipeline comprises a self-cooling pipeline adapted to cool the carbon dioxide by expansion, and a cooling tower pipeline adapted to cool the carbon dioxide by heat exchange with a cooling tower, the self-cooling pipeline and the cooling tower pipeline being respectively connected with the liquid storage tank;

[0013] A control structure, arranged on the energy storage pipeline, adapted to guide the carbon dioxide into the self-cooling pipeline or the cooling tower pipeline.

[0014] Optionally, the self-cooling pipeline comprises:

[0015] A liquefaction pipeline, connected with the liquid storage tank;

[0016] A refrigeration pipeline, connected with the gas storage tank, the refrigeration pipeline being provided with a refrigeration expander, a third heat exchanger being heat-exchangeably arranged between the liquefaction pipeline and the refrigeration pipeline.

[0017] Optionally, further comprising a cooling tower and a cooling tower loop connecting the cooling tower, a sixth heat exchanger being heat-exchangeably arranged between the cooling tower pipeline and the cooling tower loop.

[0018] Optionally, the control structure comprises:

[0019] A first flow regulating valve, arranged on the self-cooling pipeline;

[0020] A second flow regulating valve, arranged on the cooling tower pipeline.

[0021] Optionally, the control structure further comprises:

[0022] A third flow regulating valve, arranged on the liquefaction pipeline;

[0023] A fourth flow regulating valve, arranged on the refrigeration pipeline.

[0024] Optionally, further comprising:

[0025] A superheating pipeline, sealingly connecting the cold storage tank and the hot storage tank, the superheating pipeline being adapted to guide the hot heat exchange medium;

[0026] At least one second heat exchanger, being heat-exchangeably arranged between the energy releasing pipeline and the superheating pipeline.

[0027] Optionally, a fourth heat exchanger is arranged in heat exchangeable manner between the refrigeration pipeline and the superheating pipeline.

[0028] Optionally, the energy releasing pipeline comprises:

[0029] a first energy releasing pipeline, which is connected between the liquid storage tank and the gasification assembly;

[0030] a second energy releasing pipeline, which is connected between the gasification assembly and the gas storage tank, and a fifth heat exchanger is arranged in heat exchangeable manner between the first energy releasing pipeline and the second energy releasing pipeline.

[0031] The application further provides a control method of a multi-mode carbon dioxide energy storage system, which is applied to the multi-mode carbon dioxide energy storage system described in the above application scenarios and comprises the following steps of:

[0032] completely closing the second flow regulating valve, completely opening the first flow regulating valve, and opening the third flow regulating valve and the fourth flow regulating valve;

[0033] obtaining a liquid phase fraction of the first heat exchanger outlet;

[0034] adjusting the opening degree of the third flow regulating valve and the opening degree of the fourth flow regulating valve according to the size of the liquid phase fraction until the liquid phase fraction is 1;

[0035] calculating a current cooling mode reference temperature T1 according to the pressure P of the carbon dioxide gas at the liquefaction assembly outlet through formula (1);

[0036] T1 = 83.91 × P 0.142 (1)

[0037] obtaining an ambient wet-bulb temperature T2 and calculating a difference T3 between T1 and T2;

[0038] when the difference T3 is greater than 0, completely opening the second flow regulating valve, completely closing the first flow regulating valve, and switching to a cooling tower cooling mode;

[0039] when the difference T3 is less than 0, still adopting the current self-cooling mode.

[0040] Optionally, the opening degree of the third flow regulating valve is 30% and the opening degree of the fourth flow regulating valve is 70%.

[0041] when the liquid phase fraction of the first heat exchanger outlet is less than 1, gradually increasing the opening degree of the third flow regulating valve and reducing the opening degree of the fourth flow regulating valve;

[0042] when the liquid phase fraction of the first heat exchanger outlet is greater than 1, gradually reducing the opening degree of the third flow regulating valve and increasing the opening degree of the fourth flow regulating valve.

[0043] The technical scheme of the present application has the following advantages:

[0044] 1. The present application provides a multi-mode carbon dioxide energy storage system, comprising: an energy storage pipeline comprising a self-cooling pipeline adapted to expand and cool the carbon dioxide, and a cooling tower pipeline adapted to cool the carbon dioxide by heat exchange with a cooling tower, the self-cooling pipeline and the cooling tower pipeline being respectively in communication with the liquid storage tank; a control structure arranged on the energy storage pipeline and adapted to guide the carbon dioxide into the self-cooling pipeline or the cooling tower pipeline.

[0045] The present application provides a multi-mode carbon dioxide energy storage system, by arranging a control structure, the multi-mode carbon dioxide energy storage system provided by the present embodiment can freely switch the carbon dioxide to flow through the self-cooling pipeline of the self-cooling mode and the cooling tower pipeline of the cooling tower cooling mode, and respectively perform self-cooling and cooling tower cooling, so as to reasonably select the two cooling modes, in a conventional case, when the requirement for the energy storage system efficiency is not high or the weather is hot, the self-cooling mode is adopted, without cooling medium, without consuming water resources, without being affected by environmental parameters, and with small land occupation, when the requirement for the energy storage system efficiency is high or the weather is cool, the cooling tower cooling mode is adopted, and the energy storage system efficiency can be obviously improved, thereby overcoming the defects that the energy storage mode of the prior art using an external cooling tower is greatly affected by the environment, and the energy storage system efficiency is low when using the carbon dioxide self-cooling energy storage mode.

[0046] 2. The present application provides a multi-mode carbon dioxide energy storage system, the self-cooling pipeline comprising: a liquefaction pipeline in communication with the liquid storage tank; a refrigeration pipeline in communication with the gas storage tank, the refrigeration pipeline being provided with a refrigeration expander, and a third heat exchanger being heat-exchangeably arranged between the liquefaction pipeline and the refrigeration pipeline.

[0047] After the carbon dioxide is heat-exchanged by the first heat exchanger, it is divided into two streams and flows into the liquefaction pipeline and the refrigeration pipeline, the liquefaction pipeline is directly in communication with the liquid storage tank, and the carbon dioxide is further liquefied and flows into the liquid storage tank; after the carbon dioxide in the refrigeration pipeline is cooled by the refrigeration expander to form low-temperature carbon dioxide, the low-temperature carbon dioxide is heat-exchanged with the carbon dioxide in the liquefaction pipeline through the third heat exchanger, so that the carbon dioxide in the liquefaction pipeline is completely liquefied and finally enters the liquid storage tank to complete the energy storage.

[0048] 3. The present application provides a multi-mode carbon dioxide energy storage system, further comprising a cooling tower and a cooling tower loop in communication with the cooling tower, and a sixth heat exchanger being heat-exchangeably arranged between the cooling tower pipeline and the cooling tower loop.

[0049] The carbon dioxide is cooled by the first heat exchanger, and then is subjected to carbon dioxide energy storage operation in a cooling tower mode by the control structure, that is, enters a cooling tower pipeline and exchanges heat with a cooling tower loop connected with the cooling tower through a sixth heat exchanger, so that the carbon dioxide in the cooling tower pipeline is completely liquefied by heat exchange between the carbon dioxide and the heat exchange medium flowing in the cooling tower and the cooling tower loop, and finally enters a liquid storage tank to complete energy storage.

[0050] 4. The application provides a multi-mode carbon dioxide energy storage system, and the control structure comprises: a first flow regulating valve arranged on the self-cooling pipeline; and a second flow regulating valve arranged on the cooling tower pipeline.

[0051] The first flow regulating valve and the second flow regulating valve are arranged to select and control the pipeline through which the carbon dioxide in the energy storage pipeline flows subsequently, so that the multi-mode carbon dioxide energy storage system provided in the embodiment can freely switch the carbon dioxide to flow through the self-cooling pipeline in the self-cooling mode or the cooling tower pipeline in the cooling tower cooling mode.

[0052] 5. The application provides a multi-mode carbon dioxide energy storage system, and the control structure further comprises: a third flow regulating valve arranged on the liquefaction pipeline; and a fourth flow regulating valve arranged on the refrigeration pipeline.

[0053] The third flow regulating valve and the fourth flow regulating valve are arranged to control the flow of the carbon dioxide in the liquefaction pipeline and the refrigeration pipeline, so that the carbon dioxide in the liquefaction pipeline and the refrigeration pipeline is more fully exchanged, the carbon dioxide in the liquefaction pipeline is completely liquefied, and finally enters a liquid storage tank to complete energy storage.

[0054] 6. The application provides a multi-mode carbon dioxide energy storage system, and further comprises: a superheating pipeline sealingly connected with the cold storage tank and the heat storage tank, the superheating pipeline being adapted to guide the flow of the heat exchange medium; and at least one second heat exchanger arranged in heat exchangeable mode between the energy release pipeline and the superheating pipeline.

[0055] The conversion of liquid carbon dioxide into gaseous carbon dioxide requires absorption of a large amount of heat, the second heat exchanger is used to exchange heat between the heat exchange medium in the superheating pipeline and the low-temperature liquid carbon dioxide in the energy release pipeline, so that the carbon dioxide is gasified and energy is released, and the conversion device is further used to convert the released energy into subsequent energy.

[0056] 7. The application provides a multi-mode carbon dioxide energy storage system, and a fourth heat exchanger is arranged in heat exchangeable mode between the refrigeration pipeline and the superheating pipeline.

[0057] The fourth heat exchanger is arranged between the refrigeration pipeline and the superheating pipeline, and the carbon dioxide in the refrigeration pipeline exchanges heat with the hot heat exchange medium in the superheating pipeline, so that the temperature of the carbon dioxide in the refrigeration pipeline is increased to further gasify the carbon dioxide back to the gas storage tank, and the heat exchange medium entering the cold storage tank is further cooled, so that the heat exchange medium is recycled again.

[0058] 8. The application provides a multi-mode carbon dioxide energy storage system, wherein the energy releasing pipeline comprises a first energy releasing pipeline connected between the liquid storage tank and the gasification assembly, and a second energy releasing pipeline connected between the gasification assembly and the gas storage tank, and a fifth heat exchanger is arranged in heat exchangeable mode between the first energy releasing pipeline and the second energy releasing pipeline.

[0059] The temperature of the carbon dioxide in the first energy releasing pipeline is increased after the gasification and energy releasing treatment of the gasification assembly and the second heat exchanger, and the low-temperature carbon dioxide in the first energy releasing pipeline exchanges heat with the high-temperature carbon dioxide in the second energy releasing pipeline through the fifth heat exchanger, so that the carbon dioxide before entering the gasification assembly and the second heat exchanger is preheated, the initial temperature of the carbon dioxide is increased, and the heat exchange efficiency of the subsequent second heat exchanger is improved. BRIEF DESCRIPTION OF DRAWINGS

[0060] In order to more clearly illustrate the specific embodiments of the application or the technical solutions in the prior art, the drawings needed in the following specific embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0061] Figure 1 A structural schematic diagram of a multi-mode carbon dioxide energy storage system provided by the application is shown in the figure.

[0062] Explanation of reference signs:

[0063] 1, gas storage tank; 2, liquid storage tank;

[0064] 3, energy storage pipeline; 30, self-cooling pipeline; 31, liquefaction pipeline; 32, refrigeration pipeline; 33, refrigeration expander; 35, second generator; 300, cooling tower pipeline; 301, sixth heat exchanger; 302, cooling tower; 303, cooling tower loop;

[0065] 4, energy releasing pipeline; 41, first energy releasing pipeline; 42, second energy releasing pipeline;

[0066] 5, liquefaction assembly; 51, compressor; 52, electric motor;

[0067] 6, gasification assembly; 61, expander; 62, first generator;

[0068] 7, cold storage tank; 8, heat storage tank; 9, subcooling pipeline; 10, superheating pipeline; 11, first heat exchanger; 12, second heat exchanger; 13, third heat exchanger; 14, fourth heat exchanger; 15, fifth heat exchanger; 16, booster pump; 17, first flow regulating valve; 18, second flow regulating valve; 19, third flow regulating valve; 20, fourth flow regulating valve. DETAILED DESCRIPTION

[0069] The technical solutions of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0070] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0071] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0072] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0073] Embodiment 1

[0074] The multi-mode carbon dioxide energy storage system provided in the embodiment, such as Figure 1The existing carbon dioxide energy storage system in the prior art usually adopts two energy storage modes when converting gaseous carbon dioxide into liquid carbon dioxide for energy storage: first, an external cooling tower energy storage mode, which condenses carbon dioxide working medium by setting up forced ventilation cooling towers and other equipment, has the advantage of high energy storage system efficiency, but is greatly affected by the environment, for example, as summer approaches, the weather gradually becomes hot, and the water temperature of the cooling tower is often high, thereby affecting the condensation effect; second, a carbon dioxide self-cooling energy storage mode, which cools the working medium by means of carbon dioxide expansion cooling, has the advantages of not requiring a cooling medium, not consuming water resources, not being affected by environmental parameters, and small land occupation, but reduces the energy storage system efficiency to some extent.

[0075] To this end, the multi-mode carbon dioxide energy storage system provided by the embodiment includes a gas storage tank 1, a liquid storage tank 2, an energy storage pipeline 3, an energy release pipeline 4, a liquefaction assembly 5, a gasification assembly 6, a cold storage tank 7, a heat storage tank 8, a supercooling pipeline 9, a first heat exchanger 11, a self-cooling pipeline 30, a cooling tower pipeline 300, a control structure, and the like.

[0076] The gas storage tank 1 and the liquid storage tank 2 are adapted to store gaseous carbon dioxide and liquid carbon dioxide, respectively.

[0077] The energy storage pipeline 3 and the energy release pipeline 4 are in communication with the gas storage tank 1 and the liquid storage tank 2, respectively.

[0078] The liquefaction assembly 5 and the gasification assembly 6 are arranged on the energy storage pipeline 3 and the energy release pipeline 4, respectively, the liquefaction assembly 5 is adapted to liquefy carbon dioxide energy storage, and the gasification assembly 6 is adapted to gasify carbon dioxide to release energy.

[0079] Specifically, the liquefaction assembly 5 arranged on the energy storage pipeline 3 is adapted to convert gaseous carbon dioxide into liquid carbon dioxide, and the liquid carbon dioxide can be stored at a relatively high temperature, which can greatly reduce the storage space of carbon dioxide, thereby storing energy. The gasification assembly 6 arranged on the energy release pipeline 4 is adapted to convert liquid carbon dioxide into gaseous carbon dioxide, and in this conversion process, carbon dioxide releases energy, which is further converted into subsequent utilization energy by a conversion device, thereby completing the carbon dioxide energy storage and release cycle.

[0080] The cold storage tank 7 and the heat storage tank 8 are adapted to store cold heat exchange medium and hot heat exchange medium, respectively.

[0081] The supercooling pipeline 9 is in sealed communication with the cold storage tank 7 and the heat storage tank 8, and the supercooling pipeline 9 is adapted to guide the flow of cold heat exchange medium.

[0082] Specifically, the cold heat exchange medium flows through the entire supercooling pipeline 9, so that the entire supercooling pipeline 9 is in a low-temperature state, and when the heat exchange medium is high-pressure water, the temperature is 25℃.

[0083] Furthermore, since the subcooling pipe 9 is sealed and connected to the cold storage tank 7 and the heat storage tank 8, the heat exchange medium flows in a closed loop on the subcooling pipe 9 between the cold storage tank 7 and the heat storage tank 8, thus avoiding evaporation loss, splashing loss and emission loss of the heat exchange medium.

[0084] Furthermore, a booster pump 16 is installed in the subcooling pipeline 9 to guide the flow of the cold heat exchange medium.

[0085] At least one first heat exchanger 11 is heat-exchangeably disposed between the energy storage line 3 and the subcooling line 9.

[0086] Specifically, the first heat exchanger 11 liquefies the carbon dioxide in the energy storage pipeline 3, releasing a large amount of heat, which then exchanges heat with the cold heat exchange medium in the subcooled pipeline 9. This dissipates heat from the carbon dioxide, preventing the storage risks associated with excessively high liquid carbon dioxide temperatures. The temperature of the high-pressure water heat exchange medium after heat exchange is 200℃. The temperature of the carbon dioxide after heat exchange is 45℃.

[0087] Furthermore, after the cold heat exchange medium finishes its heat exchange, it is heated up and becomes a hot heat exchange medium stored in the heat storage tank 8. When carbon dioxide vaporizes and releases energy, the hot heat exchange medium can be set up through pipes and heat exchange elements to heat the carbon dioxide as a heating unit, converting liquid carbon dioxide into gaseous carbon dioxide and releasing energy. After the hot heat exchange medium cools down, it becomes a cold heat exchange medium and continues to be stored in the cold storage tank 7, thereby realizing the circulation and utilization of the heat exchange medium.

[0088] Furthermore, this embodiment does not limit the number of the first heat exchangers 11, such as... Figure 1 As shown, when there are two first heat exchangers 11, the two first heat exchangers 11 are connected in series on the energy storage pipeline 3. The subcooling pipeline 9 forms two paths that pass through the two first heat exchangers 11 respectively, thereby completing the heat exchange between the large amount of heat released by the liquefaction of carbon dioxide in the energy storage pipeline 3 and the cold heat exchange medium in the subcooling pipeline 9 through the two first heat exchangers 11. This avoids damage to the first heat exchangers 11 caused by sudden temperature rises and falls.

[0089] The energy storage pipeline 3 includes a self-cooling pipeline 30 suitable for cooling the expansion of carbon dioxide, and a cooling tower pipeline 300 suitable for cooling the carbon dioxide by exchanging heat with the cooling tower. The self-cooling pipeline 30 and the cooling tower pipeline 300 are respectively connected to the liquid storage tank 2.

[0090] Specifically, the self-cooling pipe 30 is connected to the storage tank 2. Using the expander, heat exchanger and other equipment connected to the self-cooling pipe 30, the carbon dioxide in the liquefaction pipe 31 is completely liquefied and finally enters the storage tank 2 to complete energy storage. The cooling tower pipe 300 is connected to the storage tank 2. Using the cooling tower, heat exchanger and other equipment connected to the cooling tower pipe 300, the carbon dioxide in the liquefaction pipe 31 can also be completely liquefied.

[0091] The control structure is arranged on the energy storage pipeline 3 and is suitable for guiding the carbon dioxide into the self-cooling pipeline 30 or the cooling tower pipeline 300.

[0092] Specifically, by arranging the control structure, the multi-mode carbon dioxide energy storage system provided by the embodiment can freely switch the carbon dioxide to flow through the self-cooling pipeline 30 in the self-cooling mode and the cooling tower pipeline 300 in the cooling tower cooling mode, respectively, for self-cooling and cooling tower cooling, so that the two cooling modes are reasonably selected. In general, when the efficiency requirement of the energy storage system is not high or the weather is hot, the self-cooling mode is adopted, which does not require cooling medium, does not consume water resources, is not affected by environmental parameters, and has small land occupation. When the efficiency requirement of the energy storage system is high or the weather is cool, the cooling tower cooling mode is adopted, and the efficiency of the energy storage system can be obviously improved. Thus, the defects that the efficiency of the energy storage system is low when the external cooling tower is used in the prior art and the efficiency of the energy storage system is low when the carbon dioxide self-cooling mode is used are overcome.

[0093] On the basis of the above-mentioned embodiment, as a further defined embodiment, as shown in Figure 1 The self-cooling pipeline 30 comprises a liquefaction pipeline 31 and a refrigeration pipeline.

[0094] The liquefaction pipeline 31 is in communication with the liquid storage tank 2.

[0095] The refrigeration pipeline 32 is in communication with the gas storage tank 1, and the refrigeration pipeline 32 is provided with a refrigeration expander 33. The third heat exchanger 13 is arranged in heat exchange between the liquefaction pipeline 31 and the refrigeration pipeline 32.

[0096] Specifically, as shown in Figure 1 After the carbon dioxide is subjected to heat exchange treatment by the first heat exchanger 11, the carbon dioxide is subjected to carbon dioxide energy storage operation in the self-cooling mode by the control structure, that is, the carbon dioxide is branched into the liquefaction pipeline 31 and the refrigeration pipeline 32 from the self-cooling pipeline 30. The liquefaction pipeline 31 is directly in communication with the liquid storage tank 2, and the carbon dioxide is subjected to further liquefaction treatment to flow into the liquid storage tank 2. After the carbon dioxide in the refrigeration pipeline 32 is subjected to refrigeration treatment by the refrigeration expander 33 to form low-temperature carbon dioxide with a temperature of minus 70°C, the low-temperature carbon dioxide is subjected to heat exchange with the carbon dioxide in the liquefaction pipeline 31 by the third heat exchanger 13, so that the carbon dioxide in the liquefaction pipeline 31 is completely liquefied, and finally enters the liquid storage tank 2 to complete the energy storage.

[0097] Further, as shown in Figure 1 The refrigeration expander 33 is power-connected to the second generator 35, and the refrigeration expander 33 is arranged to rotate to generate mechanical energy under the pressure of the carbon dioxide. The second generator 35 power-connected to the refrigeration expander 33 converts the mechanical energy into electrical energy, so as to recover the part of the energy to supply power to other devices of the system, thereby reducing the external input energy consumption of the system.

[0098] On the basis of the above-mentioned embodiments, as a further defined embodiment, as shown in Figure 1 The sixth heat exchanger 301 is arranged in heat exchangeable manner between the cooling tower pipeline 300 and the cooling tower loop 303.

[0099] Specifically, as shown in Figure 1 The carbon dioxide is cooled in the cooling tower mode through the control structure after heat exchange treatment by the first heat exchanger 11, that is, enters the cooling tower pipeline 300, and exchanges heat with the cooling tower loop 303 connected to the cooling tower 302 through the sixth heat exchanger 301. The heat exchange medium flowing in the cooling tower 302 and the cooling tower loop 303 exchanges heat with the carbon dioxide, so that the carbon dioxide in the cooling tower pipeline 300 is completely liquefied, and finally enters the liquid storage tank 2 to complete energy storage.

[0100] On the basis of the above-mentioned embodiments, as a further defined embodiment, as shown in Figure 1 The control structure includes: a first flow regulating valve 17 and a second flow regulating valve 18.

[0101] The first flow regulating valve 17 is arranged on the self-cooling pipeline 30.

[0102] The second flow regulating valve 18 is arranged on the cooling tower pipeline 300.

[0103] Specifically, by arranging the first flow regulating valve 17 and the second flow regulating valve 18, the subsequent pipeline through which the carbon dioxide in the energy storage pipeline 3 flows is selected and controlled, so that the multi-mode carbon dioxide energy storage system provided in the embodiment can freely switch the carbon dioxide to flow through the self-cooling pipeline 30 in the self-cooling mode and the cooling tower pipeline 300 in the cooling tower cooling mode.

[0104] Further, as an alternative embodiment, the first flow regulating valve 17 and the second flow regulating valve 18 are integrated into a three-way structure, and the three connection ports of the three-way structure are respectively connected to the energy storage pipeline 3, the self-cooling pipeline 30 and the cooling tower pipeline 300. The on-off control of each connection port of the three-way structure controls the self-cooling mode and the cooling tower cooling mode.

[0105] On the basis of the above-mentioned embodiments, as a further defined embodiment, as shown in Figure 1 The control structure further includes: a third flow regulating valve 19 and a fourth flow regulating valve 20.

[0106] The third flow regulating valve 19 is arranged on the liquefaction pipeline 31.

[0107] The fourth flow regulating valve 20 is arranged on the refrigeration pipeline 32.

[0108] Specifically, by setting the third flow regulating valve 19 and the fourth flow regulating valve 20, the carbon dioxide flow in the liquefaction pipeline 31 and the refrigeration pipeline 32 is regulated, so that the heat exchange between the carbon dioxide in the liquefaction pipeline 31 and the refrigeration pipeline 32 is more sufficient, facilitating the complete liquefaction of the carbon dioxide in the liquefaction pipeline 31, and finally entering the liquid storage tank 2 to complete energy storage.

[0109] Further, as an alternative embodiment, the third flow regulating valve 19 and the fourth flow regulating valve 20 are integrated into a three-way structure, and the three connection ports of the three-way structure are respectively connected to the self-cooling pipeline 30, the liquefaction pipeline 31 and the refrigeration pipeline 32, so as to regulate the carbon dioxide flow in the liquefaction pipeline 31 and the refrigeration pipeline 32 through the on-off of the connection ports of the three-way structure.

[0110] On the basis of the above-mentioned embodiment, as a further defined embodiment, as shown in Figure 1 The multi-mode carbon dioxide energy storage system further comprises an overheating pipeline 10, a second heat exchanger 12, etc.

[0111] The overheating pipeline 10 is in sealed communication with the cold storage tank 7 and the heat storage tank 8, and the overheating pipeline 10 is suitable for guiding the flow of the heat exchange medium.

[0112] The overheating pipeline 10 is in sealed communication with the cold storage tank 7 and the heat storage tank 8, and the overheating pipeline 10 is suitable for guiding the flow of the heat exchange medium.

[0113] Specifically, the heat exchange medium flows through the entire overheating pipeline 10, so that the entire overheating pipeline 10 is in a high-temperature state, and when the heat exchange medium is high-pressure water, the temperature is 200°C.

[0114] Further, since the overheating pipeline 10 is in sealed communication with the cold storage tank 7 and the heat storage tank 8, the heat exchange medium is closed in circulation on the overheating pipeline 10 between the cold storage tank 7 and the heat storage tank 8, avoiding evaporation loss, splashing loss and emission loss of the heat exchange medium.

[0115] Further, a booster pump 16 is arranged in the overheating pipeline 10 to guide the flow of the heat exchange medium.

[0116] Further, the supercooling pipeline 9 and the overheating pipeline 10 are respectively connected between the cold storage tank 7 and the heat storage tank 8, realizing the circulation and utilization of the cold and hot heat exchange media between the cold storage tank 7 and the heat storage tank 8.

[0117] At least one second heat exchanger 12 is arranged in heat exchangeable manner between the energy release pipeline 4 and the overheating pipeline 10.

[0118] Specifically, the liquid carbon dioxide needs to absorb a large amount of heat to be converted into gaseous carbon dioxide, and the heat exchange between the high-temperature heat exchange medium in the superheating pipeline 10 and the low-temperature liquid carbon dioxide in the energy releasing pipeline 4 is performed by using the second heat exchanger 12, so that the carbon dioxide is gasified and energy is released, and the released energy is further converted into subsequent energy by using the conversion device. The temperature of the high-pressure water heat exchange medium after heat exchange is 25°C. The temperature of the carbon dioxide after heat exchange is 25-30°C.

[0119] Further, the number of the second heat exchanger 12 is not limited in the embodiment, as shown in the figure, when the second heat exchanger 12 is two, the two second heat exchangers 12 are arranged in series on the energy releasing pipeline 4, and the superheating pipeline 10 forms two paths to pass through the two second heat exchangers 12 respectively, so that the heat exchange between the high-temperature heat exchange medium in the superheating pipeline 10 and the low-temperature liquid carbon dioxide in the energy releasing pipeline 4 is completed by the two second heat exchangers 12, so that the carbon dioxide is gasified and energy is released. Figure 1

[0120] On the basis of the above-mentioned embodiment, as a further limited embodiment, as shown in the figure, the fourth heat exchanger 14 is arranged in heat exchange between the refrigeration pipeline 32 and the superheating pipeline 10. Figure 1

[0121] Specifically, the temperature of the carbon dioxide in the refrigeration pipeline 32 after heat exchange by the third heat exchanger 13 is 15°C, and the temperature of the heat exchange medium in the superheating pipeline 10 after heat exchange by the second heat exchanger 12 is 60°C, at this time, the fourth heat exchanger 14 is arranged in heat exchange between the refrigeration pipeline 32 and the superheating pipeline 10, the carbon dioxide in the refrigeration pipeline 32 is exchanged with the heat exchange medium in the superheating pipeline 10, the temperature of the carbon dioxide in the refrigeration pipeline 32 is increased to make it further gasified to return to the gas storage tank 1, and the heat exchange medium entering the cold storage tank 7 is further cooled to the initial cold heat exchange medium temperature of 25°C, so as to facilitate the circulation of the heat exchange medium again.

[0122] On the basis of the above-mentioned embodiment, as a further limited embodiment, as shown in the figure, the energy releasing pipeline 4 includes a first energy releasing pipeline 41 and a second energy releasing pipeline 42. Figure 1

[0123] The first energy releasing pipeline 41 is connected between the liquid storage tank 2 and the gasification assembly 6.

[0124] The second energy releasing pipeline 42 is connected between the gasification assembly 6 and the gas storage tank 1, and the fifth heat exchanger 15 is arranged in heat exchange between the first energy releasing pipeline 41 and the second energy releasing pipeline 42.

[0125] ​​​Specifically, the temperature of the carbon dioxide in the first energy releasing pipeline 41 is increased after the gasification and energy releasing treatment by the gasification assembly 6 and the second heat exchanger 12. At this time, the low-temperature carbon dioxide in the first energy releasing pipeline 41 is heat-exchanged with the high-temperature carbon dioxide in the second energy releasing pipeline 42 by the fifth heat exchanger 15, i.e. the carbon dioxide before entering the gasification assembly 6 and the second heat exchanger 12 is preheated to increase the initial temperature of the carbon dioxide, thereby improving the heat exchange efficiency of the subsequent second heat exchanger 12.

[0126] On the basis of the above-mentioned embodiments, as further defined embodiments, as shown in Figure 1 The liquefaction assembly 5 comprises at least one compressor 51 driven by an external force, and the gasification assembly 6 comprises at least one expander 61.

[0127] Specifically, the gaseous carbon dioxide is compressed and liquefied by the compressor 51 to convert the gaseous carbon dioxide into liquid carbon dioxide, which can be stored at a relatively high temperature, thereby greatly reducing the storage space of the carbon dioxide. Further, the compressed carbon dioxide is cooled by the first heat exchanger 11 to store energy. The liquid carbon dioxide is expanded and gasified by the expander 61, i.e. the carbon dioxide is heated by the second heat exchanger 12 to convert the liquid carbon dioxide into gaseous carbon dioxide. In this process, the carbon dioxide releases energy, which is further converted into a subsequent energy source by the conversion device, thereby completing the carbon dioxide storage and release energy cycle.

[0128] Further, as shown in Figure 1 When multiple compressors 51 and first heat exchangers 11 are arranged on the energy storage pipeline 3, the compressors 51 and the first heat exchangers 11 are staggered, i.e. the carbon dioxide first enters the first compressor 51 to be compressed and heated, then is cooled by the first heat exchanger 11, then enters the second compressor 51 to be compressed and heated, and then is cooled by the second heat exchanger 11. In this way, the carbon dioxide is completely liquefied by the multiple-stage compression and liquefaction of the compressors 51 and the first heat exchangers 11, while avoiding the sudden temperature rise and drop that may damage the first heat exchanger 11. The expander 61 and the second heat exchanger 12 on the energy releasing pipeline 4 are arranged in the same way.

[0129] On the basis of the above-mentioned embodiments, as further defined embodiments, as shown in Figure 1 The electric motor 52 is power-connected to the compressor 51, and the expander 61 is power-connected to the first generator 62.

[0130] Specifically, the electric motor 52 powers the compressor to ensure normal operation of the carbon dioxide compression and liquefaction energy storage; the expander 61 rotates under the pressure of carbon dioxide to generate mechanical energy, and the first generator 62 connected with the expander 61 converts the mechanical energy into electrical energy, thereby completing the conversion of carbon dioxide gasification and energy release to subsequent utilization of energy.

[0131] Embodiment 2

[0132] The embodiment provides a control method of a multi-mode carbon dioxide energy storage system, and is applied to the multi-mode carbon dioxide energy storage system provided in Embodiment 1, and includes the following steps.

[0133] completely closing the second flow regulating valve 18, completely opening the first flow regulating valve 17, and opening the third flow regulating valve 19 and the fourth flow regulating valve 20;

[0134] obtaining a liquid phase fraction of the outlet of the first heat exchanger 11;

[0135] adjusting the opening degree of the third flow regulating valve 19 and the opening degree of the fourth flow regulating valve 20 according to the size of the liquid phase fraction, until the liquid phase fraction is 1;

[0136] calculating a current cooling mode reference temperature T1 according to the pressure P of the carbon dioxide gas at the outlet of the liquefaction assembly 5 through formula (1);

[0137] T1=83.91×P 0.142 (1)

[0138] obtaining an ambient wet-bulb temperature T2, and calculating a difference T3 between T1 and T2;

[0139] when the difference T3 is greater than 0, completely opening the second flow regulating valve 18 and completely closing the first flow regulating valve 17, and switching to the cooling tower cooling mode;

[0140] when the difference T3 is less than 0, still adopting the current self-cooling mode.

[0141] As a further defined embodiment on the basis of the above-mentioned embodiment, the opening degree of the third flow regulating valve 19 is 30%, and the opening degree of the fourth flow regulating valve 20 is 70%.

[0142] when the liquid phase fraction of the outlet of the first heat exchanger 11 is less than 1, gradually increasing the opening degree of the third flow regulating valve 19 and reducing the opening degree of the fourth flow regulating valve 20;

[0143] when the liquid phase fraction of the outlet of the first heat exchanger 11 is greater than 1, gradually reducing the opening degree of the third flow regulating valve 19 and increasing the opening degree of the fourth flow regulating valve 20.

[0144] Specifically, the specific adjustment steps of the two modes are as follows:

[0145] Step one: before the energy storage system starts, the self-cooling mode is adopted first. The second flow regulating valve 18 is closed, the first flow regulating valve 17 is fully opened, and the opening degrees of the third flow regulating valve 19 and the fourth flow regulating valve 20 are 30% and 70% respectively.

[0146] Step two: when the system starts, the gaseous carbon dioxide from the gas tank 1 is cooled to low-temperature high-pressure carbon dioxide gas through the multi-stage liquefaction assembly 5 and the multi-stage first heat exchanger 11, and the liquid phase fraction at the outlet of the last stage of the first heat exchanger 11 is monitored. When the liquid phase fraction at the outlet of the last stage of the first heat exchanger 11 is less than 1, the opening degree of the third flow regulating valve 19 is gradually increased, and the opening degree of the fourth flow regulating valve 20 is gradually reduced, until the liquid phase fraction at the outlet of the last stage of the first heat exchanger 11 is 1, and the actions of the third flow regulating valve 19 and the fourth flow regulating valve 20 are stopped.

[0147] Step three: the current cooling mode reference temperature T1 is calculated according to the pressure P of the low-temperature high-pressure carbon dioxide gas at the outlet of the last stage of the liquefaction assembly 5. The calculation method of T1 is shown in formula (1). At the same time, the ambient wet-bulb temperature T2 under the working condition is calculated according to the test parameters of the external cooling tower 302, and the difference T3 between T1 and T2 is calculated.

[0148] T1 = 83.91 x P 0.142 (1)

[0149] Step four: cooling mode determination, when the difference T3 is greater than 0, the cooling tower cooling mode is adopted; when the difference T3 is less than 0, the self-cooling mode is still adopted; the cooling mode determination calculation frequency is once every 1 minute.

[0150] Step five: when the cooling mode determination is the cooling tower cooling mode, the cooling mode conversion program from the self-cooling mode to the cooling tower cooling mode is started. First, the second flow regulating valve 18 is opened, the opening degree of the second flow regulating valve 18 is gradually increased and the opening degree of the first flow regulating valve 17 is gradually reduced, until the first flow regulating valve 17 is completely closed and the second flow regulating valve 18 is completely opened, and the system is switched to the cooling tower cooling mode.

[0151] Step six: when the cooling mode is determined as the self-cooling mode, the cooling mode conversion program from the cooling tower cooling mode to the self-cooling mode is started. First, the opening degrees of the third flow regulating valve 19 and the fourth flow regulating valve 20 are set according to step one, then the first flow regulating valve 17 is opened, the opening degree of the first flow regulating valve 17 is gradually increased and the opening degree of the second flow regulating valve 18 is gradually decreased until the second flow regulating valve 18 is completely closed and the first flow regulating valve 17 is completely opened; in the process of gradually increasing the opening degree of the first flow regulating valve 17, the opening degrees of the third flow regulating valve 19 and the fourth flow regulating valve 20 are adjusted in the manner of step two, and the system is switched to the self-cooling mode.

[0152] Obviously, the above embodiments are only examples for clearly illustrating but not limiting the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. All the embodiments do not need to be exhausted and the changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A multi-mode carbon dioxide energy storage system, characterized by, The application relates to a carbon dioxide energy storage and release system. The system comprises: a gas tank (1) and a liquid tank (2) adapted to store gaseous carbon dioxide and liquid carbon dioxide respectively; an energy storage pipeline (3) and an energy release pipeline (4) respectively connected to the gas tank (1) and the liquid tank (2); a liquefaction assembly (5) and a gasification assembly (6) respectively arranged on the energy storage pipeline (3) and the energy release pipeline (4), wherein the liquefaction assembly (5) is adapted to store energy by liquefying carbon dioxide, and the gasification assembly (6) is adapted to release energy by gasifying carbon dioxide; a cold storage tank (7) and a hot storage tank (8) adapted to store cold heat exchange medium and hot heat exchange medium respectively; a supercooling pipeline (9) sealingly connecting the cold storage tank (7) and the hot storage tank (8), wherein the supercooling pipeline (9) is adapted to guide the cold heat exchange medium; at least one first heat exchanger (11) heat-exchangeably arranged between the energy storage pipeline (3) and the supercooling pipeline (9); the energy storage pipeline (3) comprises a self-cooling pipeline (30) adapted to expand and cool the carbon dioxide, and a cooling tower pipeline (300) adapted to exchange heat with a cooling tower to cool the carbon dioxide, wherein the self-cooling pipeline (30) and the cooling tower pipeline (300) are respectively connected to the liquid tank (2); 2. The multi-mode carbon dioxide energy storage system of claim 1, wherein, a control structure arranged on the energy storage pipeline (3) and adapted to guide the carbon dioxide into the self-cooling pipeline (30) or the cooling tower pipeline (300). The self-cooling pipeline (30) comprises: a liquefaction pipeline (31) connected to the liquid tank (2); 3. The multi-mode carbon dioxide energy storage system of claim 2, wherein, a refrigeration pipeline (32) connected to the gas tank (1), wherein the refrigeration pipeline (32) is provided with a refrigeration expander (33), and a third heat exchanger (13) is heat-exchangeably arranged between the liquefaction pipeline (31) and the refrigeration pipeline (32).

4. The multi-mode carbon dioxide energy storage system of claim 3, wherein, The system further comprises a cooling tower (302) and a cooling tower loop (303) connected to the cooling tower (302), and a sixth heat exchanger (301) heat-exchangeably arranged between the cooling tower pipeline (300) and the cooling tower loop (303). The control structure comprises: a first flow regulating valve (17) arranged on the self-cooling pipeline (30); 5. The multi-mode carbon dioxide energy storage system of claim 4, wherein, a second flow regulating valve (18) arranged on the cooling tower pipeline (300). The control structure further comprises: a third flow regulating valve (19) arranged on the liquefaction pipeline (31); 6. The multi-mode carbon dioxide energy storage system of claim 2, wherein, a fourth flow regulating valve (20) arranged on the refrigeration pipeline (32). The system further comprises: a superheating pipeline (10) sealingly connecting the cold storage tank (7) and the hot storage tank (8), wherein the superheating pipeline (10) is adapted to guide the hot heat exchange medium; 7. The multi-mode carbon dioxide energy storage system of claim 6, wherein, at least one second heat exchanger (12) heat-exchangeably arranged between the energy release pipeline (4) and the superheating pipeline (10).

8. The multi-mode carbon dioxide energy storage system of claim 6, wherein, A fourth heat exchanger (14) is heat-exchangeably arranged between the refrigeration pipeline (32) and the superheating pipeline (10). The energy release pipeline (4) comprises: a first energy release pipeline (41) connected between the liquid tank (2) and the gasification assembly (6). A second energy releasing pipeline (42) is connected between the gasification assembly (6) and the gas storage tank (1), and a fifth heat exchanger (15) is arranged in heat exchange relationship between the first energy releasing pipeline (41) and the second energy releasing pipeline (42).

9. A control method of a multi-mode carbon dioxide energy storage system, applied to the multi-mode carbon dioxide energy storage system of any one of claims 5-8, characterized in that, Comprise: completely close the second flow regulating valve (18), completely open the first flow regulating valve (17), and open the third flow regulating valve (19) and the fourth flow regulating valve (20); acquire the liquid phase fraction of the outlet of the first heat exchanger (11); adjust the opening degree of the third flow regulating valve (19) and the opening degree of the fourth flow regulating valve (20) according to the size of the liquid phase fraction until the liquid phase fraction is 1; calculate the current cooling mode reference temperature T1 according to the pressure P of the carbon dioxide gas at the outlet of the liquefaction assembly (5) by formula (1); T1 = 83.91 x P 0.142 (1) acquire the ambient wet-bulb temperature T2 and calculate the difference T3 between T1 and T2; when the difference T3 is greater than 0, completely open the second flow regulating valve (18), completely close the first flow regulating valve (17), and switch to the cooling tower cooling mode; when the difference T3 is less than 0, still adopt the current self-cooling mode.

10. The control method of a multi-mode carbon dioxide energy storage system according to claim 9, wherein, the opening degree of the third flow regulating valve (19) is 30%, and the opening degree of the fourth flow regulating valve (20) is 70%; when the liquid phase fraction of the outlet of the first heat exchanger (11) is less than 1, gradually increase the opening degree of the third flow regulating valve (19) and reduce the opening degree of the fourth flow regulating valve (20); when the liquid phase fraction of the outlet of the first heat exchanger (11) is greater than 1, gradually reduce the opening degree of the third flow regulating valve (19) and increase the opening degree of the fourth flow regulating valve (20).

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