Low temperature carbon dioxide storage transport method and system

Abstract

The application discloses a low-temperature carbon dioxide storage and transportation method and system, relates to the technical field of carbon dioxide storage and transportation, and comprises the following steps: loading carbon dioxide in a storage tank during loading, a filling station outputs liquid high-pressure carbon dioxide, and the liquid high-pressure carbon dioxide is input into the storage tank to be loaded after pressure reduction through throttling; then, transportation is carried out; during the transportation, part of the carbon dioxide in the storage tank is converted in state, compensates for external heat input and / or carries out energy conversion; finally, unloading is carried out; during the unloading, carbon dioxide is first introduced into the storage tank to maintain the pressure of the storage tank stable within a preset range, and after it is ensured that the solid carbon dioxide in the storage tank is completely removed, the liquid carbon dioxide in the storage tank is pumped out and transported to a receiving station. The carbon dioxide is converted in state during transportation, the influence of external thermal disturbance on the temperature and pressure state of the storage tank is compensated, and the safe, stable and energy-saving effect is achieved.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide storage and transportation technology, and particularly to methods and systems for storing and transporting cryogenic carbon dioxide. Background Technology

[0002] Large-scale carbon dioxide transportation is a crucial intermediate link in the carbon capture, utilization, and storage (CFS) system, responsible for transferring captured carbon dioxide to storage or utilization sites, playing a vital role in the operation of the entire system. The main modes of carbon dioxide transportation include road, water, rail, and pipeline transport, and the combination and complementarity of these modes achieve high-efficiency and low-cost transportation of carbon dioxide. While a carbon dioxide pipeline transportation system is a large-scale infrastructure project requiring long-term development and improvement, road, water, and rail transport methods using liquid carbon dioxide storage tanks, based on existing transportation systems and vehicles, offer more mature, faster, and more convenient development conditions.

[0003] Carbon dioxide transportation often involves risks such as large volume, long distance, and high cost. Existing liquid carbon dioxide storage tanks still have technical limitations: high-pressure tanks (3.5-4.5 MPa) can store carbon dioxide at near-ambient temperatures (0-10°C), but their construction costs are too high; medium-pressure tanks (approximately 1.9 MPa) can store carbon dioxide at -35°C, but their pressure remains high, resulting in high costs, and ensuring the tank pressure remains within a safe range and minimizing leakage is crucial; low-pressure tanks (approximately 0.5 MPa) can store carbon dioxide at -55°C, and their lower pressure helps reduce costs, but they are more susceptible to vaporization due to thermal disturbances, and gas reliquefaction is energy-intensive. Furthermore, the carbon dioxide transportation process also consumes fuel and generates emissions, necessitating compliance with energy conservation and emission reduction requirements. Therefore, there is an urgent need to develop new carbon dioxide storage and transportation technologies to make carbon dioxide storage and transportation safer, more environmentally friendly, and more energy-efficient. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for storing and transporting cryogenic carbon dioxide. This system enables low-pressure and low-temperature storage of carbon dioxide in a state where carbon dioxide exists in gas, liquid, and solid states. During transportation, the solid-liquid transformation of carbon dioxide is utilized to compensate for the impact of external thermal disturbances on the temperature and pressure of the storage tank, thereby preventing the vaporization of liquid carbon dioxide and ensuring that the storage tank is more stable and more energy-efficient.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0006] A method for storing and transporting cryogenic carbon dioxide includes the following steps: During the loading process, carbon dioxide is loaded into the storage tank. The filling station outputs high-pressure liquid carbon dioxide, which is then throttled and depressurized before being input into the storage tank to be loaded. At the same time, gaseous carbon dioxide is extracted from the top of the storage tank. The liquid carbon dioxide in the storage tank is continuously transformed into solid. After loading is completed, the carbon dioxide in the storage tank includes gaseous, liquid and solid states. Then, during transportation, the cold released by the conversion of some of the solid carbon dioxide in the storage tank into liquid carbon dioxide compensates for external thermal disturbances and / or couples the waste heat generated during the transportation process for energy conversion. Finally, unloading is carried out. During the unloading process, carbon dioxide pressure-holding gas is first introduced into the storage tank to maintain the pressure of the storage tank within the preset range and melt the solid carbon dioxide remaining in the storage tank. After the solid carbon dioxide is completely removed from the storage tank, the liquid carbon dioxide in the storage tank is sucked out and transported to the receiving station.

[0007] Furthermore, the loading process also includes extracting gaseous carbon dioxide, recompressing and cooling it, then reliquefying it, and finally combining it with the output of the filling station before inputting it into the storage tank.

[0008] Furthermore, the energy conversion includes utilizing the waste heat from the power equipment of the transportation vehicle and / or ambient heat to couple the cooling energy released when solid carbon dioxide in the storage tank is converted into liquid carbon dioxide, and converting it into mechanical work or electricity.

[0009] Furthermore, the energy conversion includes using the carbon dioxide stored in the storage tank as a working fluid to perform energy conversion through carbon dioxide circulation. The liquid carbon dioxide output from the storage tank is then pressurized, vaporized after absorbing waste heat from the power equipment of the transportation vehicle and ambient heat, and expands to do work, generating mechanical work or electricity. The gaseous carbon dioxide returns to the storage tank and absorbs the cold energy released by the solid carbon dioxide in the storage tank as it is converted into liquid carbon dioxide, and is then reliquefied.

[0010] Furthermore, the energy conversion includes outputting liquid carbon dioxide stored in the tank as a heat transfer medium to the cold end of the organic Rankine cycle, whereby the carbon dioxide vaporizes and transfers its cooling capacity to the working fluid of the organic Rankine cycle, or transferring the cooling capacity of the carbon dioxide in the tank to the working fluid of the organic Rankine cycle through heat exchange tubes in the tank, and converting the waste heat from the power equipment of the transportation vehicle into mechanical work or electricity through the organic Rankine cycle.

[0011] Furthermore, during the transportation process, liquid carbon dioxide in the storage tank is continuously or intermittently injected into the lower part of the storage tank for flushing and stirring to enhance the contact heat exchange between solid and liquid and / or gaseous carbon dioxide. Before the unloading process begins, liquid carbon dioxide in the storage tank is injected into the lower part of the storage tank for flushing and stirring to accelerate the melting of residual solid carbon dioxide.

[0012] On the other hand, the present invention also discloses a cryogenic carbon dioxide storage and transportation system, including a storage tank, a loading module and an unloading module. The storage tank is provided with a filling port and a distributor connected to the filling port at the bottom of the storage tank. The storage tank includes a liquid accumulation pool at the bottom and a gas chamber at the top. The loading module includes a vacuum pump connected to the gas chamber and a filling station connected to the filling port. The liquid accumulation pool is connected to the unloading pump. The unloading module includes a pressure-holding gas station connected to the gas chamber and a receiving station connected to the unloading pump.

[0013] Furthermore, the outlet of the vacuum pump is connected to the liquefaction module to reliquefy the gaseous carbon dioxide, and the outlet of the liquefaction module is connected to the filling port.

[0014] Furthermore, it also includes an energy conversion module, in which liquid carbon dioxide in the storage tank is introduced into the energy conversion module to provide cooling, or cooling is provided to the energy conversion module through heat exchange, and heat is provided by the waste heat from the power equipment of the transportation vehicle and / or ambient heat, and the energy conversion module outputs mechanical work or electricity.

[0015] Furthermore, the energy conversion module also includes a stirring pump, which is connected at both ends to a distributor at the bottom of the tank and below the liquid surface at the top of the tank, respectively, via pipes. The stirring pump is used to extract carbon dioxide from the top of the tank and inject it into the bottom of the tank, and then output it through the distributor, thereby stirring the carbon dioxide inside the tank as a whole.

[0016] In summary, the present invention has the following beneficial effects: The low pressure of the storage tank reduces construction costs; the tank has strong resistance to external interference, maintaining stable temperature and pressure to avoid vaporization and overpressure leakage, thus improving transportation safety; at the same time, during transportation, the cooling energy released by the solid-liquid transformation of carbon dioxide is coupled with the waste heat from the transportation vehicle and ambient heat, which is then converted into the mechanical work or electricity required by the transportation vehicle through an energy conversion device, thereby saving the power consumption of the transportation vehicle, achieving two benefits at once. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a cryogenic carbon dioxide storage and transportation system and its loading process according to the present invention; Figure 2 This is a schematic diagram of a cryogenic carbon dioxide storage and transportation system and its unloading process according to the present invention; Figure 3 This is a schematic diagram of the energy conversion and system during the transportation process in Example 1; Figure 4 This is a schematic diagram of the energy conversion and system during the transportation process in Example 2; Figure 5 This is a schematic diagram of the energy conversion and system during the transportation process in Example 3. Detailed Implementation

[0018] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. These embodiments do not constitute a limitation of the present invention. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this application.

[0019] Example 1: A cryogenic carbon dioxide storage and transportation system, such as Figure 1 As shown, it includes a transport vehicle, a storage tank, a loading module, an unloading module, and an energy conversion module. The storage tank is a cryogenic pressure vessel used to store carbon dioxide. The bottom of the storage tank is equipped with a filling port (a distributor is installed inside the storage tank at the bottom and connected to the filling port). The interior of the storage tank includes a liquid accumulation pool at the bottom and a gas chamber at the top. The loading module is detachably connected to the storage tank through valves and connecting flanges. The loading module specifically includes an air pump (inlet) connected to the gas chamber and a filling station connected to the filling port. In some embodiments, the outlet of the vacuum pump is connected to the liquefaction module to reliquefy the gaseous carbon dioxide. The outlet of the liquefaction module is connected to the outlet of the filling station, and then together they are detachably connected to the filling port at the bottom of the storage tank through valves and connecting flanges. The liquefaction module includes a compressor, a condenser, and a refrigeration unit. The outlet of the vacuum pump is connected to the inlet of the compressor, the outlet of the compressor is connected to the carbon dioxide inlet of the condenser, and the carbon dioxide outlet of the condenser is connected to the charging port (and the outlet of the filling station). The refrigeration unit can directly use the charged carbon dioxide as the working fluid, or it can use other refrigerants. The working fluid of the refrigeration unit transfers its cooling capacity to the pressurized carbon dioxide in the compressor through the condenser and liquefies it. It can also be replaced by other refrigeration components.

[0020] like Figure 2 As shown, an unloading pump is fixed on the storage tank. The inlet of the unloading pump is connected downward to the liquid accumulation tank. The unloading module is detachably connected to the storage tank and the unloading pump through valves and connecting flanges. Specifically, it includes a pressure-holding gas station connected to the gas chamber at the top of the storage tank and a receiving station connected to the outlet of the unloading pump. The pressure-holding gas station inputs carbon dioxide pressure-holding gas into the storage tank to maintain the pressure of the storage tank. The unloading pump transfers the liquid carbon dioxide in the storage tank to the receiving station. Liquid carbon dioxide in the storage tank is directly introduced into the energy conversion module to provide it with cooling, or it is provided with cooling through heat exchange. Waste heat from the power equipment of the transportation vehicle and / or ambient heat provide heat, ultimately enabling the energy conversion module to output mechanical work or electricity.

[0021] like Figure 3 As shown, the transport vehicle can be a ship or a vehicle, and the storage tank and energy conversion module are installed on the transport vehicle; the energy conversion module is detachably connected to the storage tank through devices such as valves and connecting flanges; In this embodiment, the exhaust working medium (carbon dioxide working gas) of the energy conversion module is connected to the air inlet of the storage tank (in this embodiment, the air inlet is located at the bottom of the storage tank and connected to the distributor inside the storage tank). The exhaust working medium absorbs the cold energy released by the solid-liquid transformation of carbon dioxide in the storage tank and then liquefies. The liquid carbon dioxide outlet of the storage tank (the liquid carbon dioxide outlet extends from below the liquid level of the storage tank to the outside of the storage tank through a pipe and is connected to the energy conversion module) is connected to the liquid inlet of the energy conversion module. The liquefied working medium is pressurized in the energy conversion module, absorbs the waste heat of the power equipment of the transportation vehicle and the ambient heat, and then vaporizes and expands to do work, thereby generating mechanical work or electricity. The energy conversion module specifically includes a booster pump, a regenerator, a vaporizer, a superheater, and an expander. The inlet of the booster pump is connected to a pipe inserted below the liquid surface at the top of the storage tank (liquid carbon dioxide outlet). The liquid carbon dioxide is pressurized by the booster pump. The outlet of the booster pump is connected to the cold-side inlet of the regenerator, the cold-side outlet of the regenerator is connected to the inlet of the vaporizer (the vaporizer provides heat through ambient heat), the outlet of the vaporizer is connected to the inlet of the superheater (the superheater provides heat through process waste heat), and the outlet of the superheater is connected to the inlet of the expander. The liquid carbon dioxide is pressurized by the regenerator... After being heated sequentially by the vaporizer and superheater, the carbon dioxide is converted into a high-temperature, high-pressure gaseous state. The carbon dioxide expands and does work through the expander. The outlet of the expander is connected to the hot-side inlet of the regenerator, and the hot-side outlet of the regenerator is connected to the air inlet of the storage tank. This allows the waste heat from the expander exhaust to be transferred to the working fluid at the outlet of the booster pump through the regenerator. The expander is mechanically connected to the load (or generator). The hot-side outlet of the regenerator is connected to the outlet of the stirring pump, and together they are connected to the distribution pipe at the bottom of the storage tank. The exhaust gas is input into the storage tank and absorbs the cold energy released by the solid carbon dioxide in the storage tank as it is converted into liquid carbon dioxide, and then reliquefies it.

[0022] like Figure 3 As shown, the energy conversion module also includes a stirring pump. The two ends of the stirring pump are connected to the distributor at the bottom of the tank and below the liquid surface at the top of the tank, respectively, through pipes. The stirring pump is used to extract carbon dioxide from the top of the tank and inject it into the bottom of the tank, and then output it through the distributor, thereby stirring the carbon dioxide inside the tank as a whole.

[0023] Example 2: This embodiment is the same as the loading and unloading modules in Embodiment 1, except that... like Figure 4As shown, the energy conversion module in this embodiment adopts the organic working fluid Rankine cycle (ORC cycle) energy conversion method. The ORC cycle uses the cold energy released by the solid-liquid transformation of carbon dioxide in the storage tank as the cold source, and the waste heat of the power equipment of the transportation vehicle and the ambient heat as the heat source. The liquid carbon dioxide in the storage tank is output to the cold end of the ORC cycle as the heat transfer medium. The exhaust gas of the ORC cycle is liquefied and the carbon dioxide is vaporized and returned to the air inlet of the storage tank, and then liquefied again in the storage tank. The heat released by liquefaction is absorbed by the solid-liquid transformation of carbon dioxide in the storage tank. The ORC cycle outputs mechanical work or electricity. Its energy conversion module specifically includes a circulating pump and an ORC circulating device. The inlet of the circulating pump is connected to a pipe inserted below the liquid surface at the top of the storage tank (liquid carbon dioxide outlet). The outlet of the circulating pump is connected to the cold end inlet of the ORC circulating device, and the cold end outlet of the ORC circulating device is connected to the air inlet of the storage tank. The circulating pump inputs the liquid carbon dioxide in the storage tank into the cold end of the ORC circulating device for vaporization, releases the cooling capacity, and then returns it to the storage tank. The ORC circulating device uses the waste heat of the process as a heat source. The ORC circulating device is mechanically connected to the load (or generator) so that the ORC circulating device outputs mechanical work or electricity.

[0024] Example 3: This embodiment is the same as the loading and unloading modules in Embodiment 1, except that... like Figure 5 As shown, the energy conversion module adopts the organic working fluid Rankine cycle (ORC) energy conversion method, including an ORC cycle device and heat exchange tubes. The heat exchange tubes contain organic working fluid and are placed inside the storage tank. The two ends of the heat exchange tubes are connected to the cold end inlet and cold end outlet of the ORC cycle device, respectively, so that the exhaust gas from the cold end outlet of the ORC cycle device is liquefied after passing through the heat exchange tubes and then returned to the ORC cycle device. The ORC cycle device uses the waste heat of the process as a heat source. The ORC cycle device is mechanically connected to the load (or generator) so that the ORC cycle device outputs mechanical work or electricity.

[0025] This invention also discloses a method for storing and transporting cryogenic carbon dioxide, comprising the following steps: (1) Loading process like Figure 1 As shown, during the loading process, carbon dioxide is loaded into the storage tank (completed via a loading module). The carbon dioxide includes gaseous, liquid, and solid states, achieving a coexistence of gaseous, liquid, and solid carbon dioxide within the tank. The energy used in the loading process is preferably green electricity or green low-carbon fuel. The loading process specifically includes... First, the filling station outputs high-pressure liquid carbon dioxide, which is then throttled and depressurized before being fed into the storage tank to be loaded. The carbon dioxide in the storage tank is kept in a state where gas, liquid and solid coexist. Simultaneously, a vacuum pump is activated to extract gaseous carbon dioxide from the top of the storage tank. The liquid carbon dioxide in the storage tank continuously transforms into solid and gaseous states. In some embodiments, after the gaseous carbon dioxide is extracted, it is recompressed to a high pressure, cooled by a refrigeration process, and then reliquefied into liquid carbon dioxide. The pressure of the liquid carbon dioxide is equal to that of the liquid carbon dioxide coming out of the filling station (e.g., 4 MPa). After merging with the output of the filling station, it is input into the storage tank together to replenish the liquid carbon dioxide. Finally, the tank is loaded with the rated mass of carbon dioxide, with gaseous carbon dioxide above the liquid surface and in the gas chamber. The mass of solid carbon dioxide in the tank does not exceed 80% of the rated mass, and its precise quantity can be further determined according to the needs during transportation. After the loading operation is completed, the connection between the loading module and the storage tank is disconnected, and the transportation system is ready.

[0026] (2) Transportation process During transportation, the carbon dioxide storage tank maintains a certain proportion of solid carbon dioxide at all times. The cooling released by the partial conversion of solid carbon dioxide into liquid carbon dioxide compensates for external thermal disturbances and / or couples with the residual heat generated during transportation for energy conversion. External thermal disturbances can be compensated for by the solid-liquid conversion of carbon dioxide because, when the tank is heated, some of the solid carbon dioxide in the tank converts into liquid carbon dioxide, which is an endothermic process that offsets the external heat input. The volume change caused by the solid-liquid conversion is much smaller than that caused by the liquid-gas conversion. The corresponding pressure changes can be buffered by the gaseous carbon dioxide in the tank, and when the pressure of the gaseous carbon dioxide increases, it will trigger the liquefaction of some of the carbon dioxide, thus preventing the carbon dioxide from vaporizing and maintaining the temperature and pressure in the tank in a thermodynamic state of coexistence of gas, liquid, and solid. Therefore, external thermal disturbances will not cause changes in the temperature and pressure inside the tank, avoiding the risk of over-temperature and over-pressure, and ensuring the safety and stability of the storage tank during transportation.

[0027] During transportation, the transportation system ensures that the coexistence of carbon dioxide gas, liquid, and solid states in the storage tank remains constant, and utilizes the cooling energy released during the solid-liquid transformation of carbon dioxide to achieve energy conversion and utilization. In some embodiments, the transportation system is equipped with an energy conversion module that utilizes the waste heat from the power equipment of the transportation vehicle and ambient heat, coupled with the cooling energy released during the solid-liquid transformation of carbon dioxide in the storage tank, to convert it into mechanical work or electricity that can be used by the transportation vehicle. For example, a carbon dioxide circulation method can be used, where the liquid carbon dioxide stored in the storage tank is pressurized, absorbs the waste heat from the power equipment of the transportation vehicle and ambient heat, and then vaporizes and expands to do work, thereby generating mechanical work or electricity. Alternatively, an ORC circulation method can be used, where the carbon dioxide stored in the storage tank is used as a heat transfer medium (the cooling energy is released at the cold end of the ORC circulation device and then returned to the storage tank), or an ORC circulation method can be used (the carbon dioxide in the storage tank exchanges heat with the ORC circulation working medium through heat exchange tubes, and the ORC circulation working medium obtains cooling energy), which is converted into mechanical work or electricity (the generated mechanical work can be used to drive the mechanical equipment of the transportation vehicle or drive the generator to generate electricity). Meanwhile, the heat exchange between the solid and liquid carbon dioxide in the storage tank can be enhanced by stirring. For example, by controlling the stirring pump to continuously or intermittently inject liquid carbon dioxide into the lower part of the storage tank for flushing and stirring, some solid carbon dioxide is evenly suspended in the liquid carbon dioxide, so as to enhance the contact heat exchange between solid and liquid and / or gaseous carbon dioxide. Finally, at the end of transportation, a small amount (not less than 3% of the total) of solid carbon dioxide is still retained in the liquid pool at the bottom of the storage tank to ensure that it is sufficient to maintain the temperature and pressure stability of the storage tank before reaching the destination. The stirring pump can be intermittently controlled to draw carbon dioxide from the top of the storage tank to the bottom to make the temperature of the storage tank uniform. In some embodiments, for cases where the energy conversion module still needs to operate during the return journey, a separate storage tank containing sufficient solid carbon dioxide can be retained.

[0028] (3) Uninstallation process After finally reaching the destination, unload the program, such as... Figure 2 As shown, during the unloading process, carbon dioxide pressure-holding gas is first introduced into the storage tank to maintain the pressure of the storage tank within the preset range (0.55MPa~0.6MPa). The stirring pump is then started to draw liquid carbon dioxide from the top of the storage tank to the bottom to make the temperature of the storage tank uniform. Since the condensation temperature of the carbon dioxide in the pressure-holding gas is higher than the temperature of the carbon dioxide on the liquid surface of the storage tank at this time, the pressure-holding gas liquefies and releases heat, melting the solid carbon dioxide remaining in the storage tank and preventing the regeneration of solid carbon dioxide in the storage tank. After ensuring that solid carbon dioxide is completely removed from the storage tank (to avoid clogging of unloading pipelines or equipment), start the unloading pump to draw liquid carbon dioxide from the storage tank from the sump and transport it to the receiving station. The unloading of carbon dioxide is completed through the unloading module. During the unloading process, ensure that solid carbon dioxide has been removed from the storage tank. After the carbon dioxide is unloaded, disconnect the unloading module from the pressure-holding gas station and the receiving station.

[0029] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within the scope of its essence and protection. Such modifications or equivalent substitutions should also be considered to fall within the protection scope of the present invention.

Claims

1. A method for storing and transporting low-temperature carbon dioxide, characterized in that: Includes the following steps, During the loading process, carbon dioxide is loaded into the storage tank. The filling station outputs high-pressure liquid carbon dioxide, which is then throttled and depressurized before being input into the storage tank to be loaded. At the same time, gaseous carbon dioxide is extracted from the top of the storage tank. The liquid carbon dioxide in the storage tank is continuously transformed into solid. After loading is completed, the carbon dioxide in the storage tank includes gaseous, liquid and solid states. Then, during transportation, the cold released by the conversion of some of the solid carbon dioxide in the storage tank into liquid carbon dioxide compensates for external thermal disturbances and / or couples the waste heat generated during the transportation process for energy conversion. Finally, unloading is carried out. During the unloading process, carbon dioxide pressure-holding gas is first introduced into the storage tank to maintain the pressure of the storage tank within the preset range and melt the solid carbon dioxide remaining in the storage tank. After the solid carbon dioxide is completely removed from the storage tank, the liquid carbon dioxide in the storage tank is sucked out and transported to the receiving station. During the transportation process, liquid carbon dioxide in the storage tank is continuously or intermittently injected into the lower part of the storage tank for flushing and stirring to enhance the contact heat exchange between solid and liquid and / or gaseous carbon dioxide. Before the unloading process begins, liquid carbon dioxide in the storage tank is injected into the lower part of the storage tank for flushing and stirring to accelerate the melting of residual solid carbon dioxide.

2. The method for storing and transporting cryogenic carbon dioxide according to claim 1, characterized in that: The loading process also includes extracting gaseous carbon dioxide, recompressing and cooling it, then reliquefying it, and finally merging it with the output of the filling station before inputting it into the storage tank.

3. The method for storing and transporting low-temperature carbon dioxide according to claim 1, characterized in that: The energy conversion includes utilizing the waste heat from the power equipment of the transportation vehicle and / or ambient heat, coupling the cooling energy released when solid carbon dioxide in the storage tank is converted into liquid carbon dioxide, and converting it into mechanical work or electricity.

4. The method for storing and transporting cryogenic carbon dioxide according to claim 1 or 3, characterized in that: The energy conversion includes using the carbon dioxide stored in the storage tank as the working fluid, and converting energy through carbon dioxide circulation. The liquid carbon dioxide output from the storage tank is then pressurized, vaporized and expanded after absorbing the waste heat from the power equipment of the transportation vehicle and the ambient heat, generating mechanical work or electricity. The gaseous carbon dioxide returns to the storage tank and absorbs the cold energy released by the solid carbon dioxide in the storage tank as it is converted into liquid carbon dioxide, and is then reliquefied.

5. The method for storing and transporting cryogenic carbon dioxide according to claim 1 or 3, characterized in that: The energy conversion includes outputting liquid carbon dioxide stored in the tank as a heat transfer medium to the cold end of the organic Rankine cycle, whereby the carbon dioxide vaporizes and transfers its cooling capacity to the working fluid of the organic Rankine cycle, or transferring the cooling capacity of the carbon dioxide in the tank to the working fluid of the organic Rankine cycle through heat exchange tubes in the tank, and converting the waste heat from the power equipment of the transportation vehicle into mechanical work or electricity through the organic Rankine cycle.

6. A cryogenic carbon dioxide storage and transportation system, applied to the cryogenic carbon dioxide storage and transportation method of claim 1, characterized in that: It includes a storage tank, a loading module, and an unloading module. The storage tank is equipped with a filling port and a distributor connected to the filling port at the bottom of the storage tank. The storage tank includes a liquid accumulation pool at the bottom and an air chamber at the top. The loading module includes an air pump connected to the air chamber and a filling station connected to the filling port. The liquid accumulation pool is connected to the unloading pump. The unloading module includes a pressure-holding air station connected to the air chamber and a receiving station connected to the unloading pump.

7. A cryogenic carbon dioxide storage and transportation system according to claim 6, characterized in that: The outlet of the vacuum pump is connected to the liquefaction module to reliquefy gaseous carbon dioxide, and the outlet of the liquefaction module is connected to the filling port.

8. A cryogenic carbon dioxide storage and transportation system according to claim 6, characterized in that: It also includes an energy conversion module, in which liquid carbon dioxide in the storage tank is introduced into the energy conversion module to provide cooling, or cooling is provided to the energy conversion module through heat exchange, and heat is provided by the waste heat from the power equipment of the transportation vehicle and / or ambient heat, and the energy conversion module outputs mechanical work or electricity.

9. A cryogenic carbon dioxide storage and transportation system according to claim 8, characterized in that: The energy conversion module also includes a stirring pump, which is connected at both ends to a distributor at the bottom of the tank and below the liquid level at the top of the tank via pipes. The stirring pump is used to extract carbon dioxide from the top of the tank and inject it into the bottom of the tank, and then output it through the distributor, thereby stirring the carbon dioxide inside the tank as a whole.

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