Zero-loss methane propellant supercooling filling system and filling method

Abstract

The invention relates to a zero-loss methane propellant supercooling filling system and method, and the system comprises a liquid nitrogen supply unit, a methane supply unit, a supercooling methane storage tank, a heat exchange pipeline unit and a temperature control unit; the heat exchange pipeline unit comprises a first heat exchanger, a second heat exchanger, a third heat exchanger and a separation and recovery module; the liquid nitrogen supply unit is connected with the cold end of the first heat exchanger. The cold ends of the first heat exchanger, the second heat exchanger and the third heat exchanger are sequentially connected in series. Methane output by the methane supply unit exchanges heat with the third heat exchanger and then is input into the supercooled methane storage tank; methane output by the exhaust end of the supercooled methane storage tank exchanges heat with the second heat exchanger and then is input into the separation and recovery module; and the separation and recovery module is connected with the supercooled methane storage tank and the methane supply unit and is used for converging the recovered methane into the supercooled methane storage tank and / or returning the recovered methane to the methane supply unit. According to the method, freezing in methane supercooling filling is effectively avoided, and lossless filling is achieved.

Description

Technical Field

[0001] This invention relates to the field of cryogenic propellant loading technology, and in particular to a zero-loss methane propellant supercooling loading system and loading method. Background Technology

[0002] Compared to ambient temperature propellants, cryogenic propellants offer advantages such as high specific impulse, non-toxicity, and no pollution, and have been widely used in next-generation launch vehicles. Liquid oxygen / liquid methane combinations have attracted significant attention in the commercial space sector due to their low cost. However, cryogenic propellants have very low boiling points and are highly susceptible to evaporation when near saturation, posing numerous challenges to engine operation and propulsion system thermal management. Using supercooled cryogenic propellants can not only effectively mitigate the evaporation problem but also reduce system mass, improve engine performance, and extend on-orbit storage time.

[0003] For supercooled refueling of methane propellant, liquid nitrogen is the most common cooling source. However, the boiling point of liquid nitrogen under standard conditions is lower than the freezing point of methane, so methane is prone to freezing during supercooling, which affects its flow in the pipeline and the normal operation of the engine. Furthermore, methane absorbs heat from the tank and vaporizes during refueling, releasing it into the atmosphere. As a greenhouse gas, methane has a greenhouse effect 21 times greater than CO2, polluting the air, affecting human health, and accelerating global warming. This released methane undoubtedly leads to propellant waste and increased costs during refueling.

[0004] Therefore, how to avoid icing during the supercooling of methane propellant and how to reduce methane emissions during the methane refueling process have become problems that urgently need to be solved by those skilled in the art. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a zero-loss methane propellant supercooling refueling system and refueling method.

[0006] To achieve the above-mentioned objectives, the present invention provides a zero-loss methane propellant subcooling refueling system, comprising: a liquid nitrogen supply unit, a methane supply unit, a subcooled methane storage tank, a heat exchange pipeline unit for connecting the liquid nitrogen supply unit, the methane supply unit and the subcooled methane storage tank, and a temperature control unit connected to the heat exchange pipeline unit; The heat exchange pipeline unit includes: a first heat exchanger, a second heat exchanger, a third heat exchanger, and a separation and recovery module; The liquid nitrogen supply unit is connected to the cold end of the first heat exchanger, and the cold ends of the first heat exchanger, the second heat exchanger, and the third heat exchanger are connected in series. The methane output from the methane supply unit is fed into the subcooled methane storage tank after exchanging heat with the third heat exchanger. The methane output from the exhaust end of the subcooled methane storage tank exchanges heat with the second heat exchanger and is then input into the separation and recovery module. The separation and recovery module is connected to the subcooled methane storage tank and the methane supply unit for collecting the recovered subcooled methane into the subcooled methane storage tank and / or returning the recovered subcooled methane to the methane supply unit.

[0007] According to one aspect of the present invention, the liquid nitrogen supply unit comprises: a liquid nitrogen storage tank and a pressurized heat exchanger; The liquid nitrogen storage tank is provided with a first storage tank port, a second storage tank port and a third storage tank port; The first tank port and the second tank port are located near the bottom of the liquid nitrogen tank; The third storage tank port is located at the top of the liquid nitrogen storage tank; The inlet end of the booster heat exchanger is connected to the first storage tank port, and the outlet end of the booster heat exchanger is connected to the third storage tank port; The second storage tank port is connected to the cold end inlet of the first heat exchanger.

[0008] According to one aspect of the present invention, the liquid nitrogen supply unit further includes: a first regulating valve, a first pressure sensor, and a first shut-off valve; The first regulating valve is installed on the pipeline between the inlet end of the booster heat exchanger and the port of the first storage tank; The first pressure sensor is connected near the top of the liquid nitrogen tank and is used to monitor the pressure inside the liquid nitrogen tank; The first pressure sensor is interlocked with the first regulating valve to adjust the opening of the first regulating valve based on the pressure inside the liquid nitrogen tank collected by the first pressure sensor, so as to ensure that the pressure inside the liquid nitrogen tank is higher than the set value. The first shut-off valve is installed on the pipeline between the second storage tank port and the cold end inlet of the first heat exchanger.

[0009] According to one aspect of the present invention, the methane supply unit includes: a methane storage tank, a booster pump, and a second shut-off valve; The methane storage tank is provided with a first methane storage tank port, a second methane storage tank port and a third methane storage tank port; The first methane storage tank port is located at the lower part of the methane storage tank, and the first methane storage tank port is connected to the booster pump; The booster pump can be installed inside or outside the methane storage tank, and the outlet end of the booster pump is connected to the hot end inlet of the third heat exchanger. The second shut-off valve is installed on the pipeline between the outlet end of the booster pump and the hot end inlet of the third heat exchanger; The second methane storage tank port is located in the middle of the methane storage tank, and the third methane storage tank port is located in the upper part of the methane storage tank. The second methane storage tank port and the third methane storage tank port are respectively connected to the separation and recovery module.

[0010] According to one aspect of the present invention, the subcooled methane storage tank is provided with a first storage tank port and a second storage tank port; The first tank port is located at the top of the subcooled methane tank, and the first tank port is connected to the hot end inlet of the second heat exchanger; The second tank port is located below the first tank port, and the second tank port is connected to the hot end outlet of the third heat exchanger; A third shut-off valve is installed on the pipeline between the second tank port and the hot end outlet of the third heat exchanger.

[0011] According to one aspect of the present invention, the separation and recovery module includes: a separation tank, a filter, a second regulating valve, a first liquid level sensor, a transfer pump, a fourth shut-off valve, and a fifth shut-off valve; The separation tank is provided with a first tank port, a second tank port and a third tank port; The first tank port is located at the top of the separation tank, the third tank port is located at the bottom of the separation tank, and the second tank port is located on the side wall of the separation tank; The first tank port is provided with an exhaust pipe, which is connected to the third methane storage tank port of the methane storage tank; The second tank port is connected to the hot end outlet of the second heat exchanger; The third tank port is connected to the inlet end of the filter, the outlet end of the filter is connected to the inlet end of the delivery pump, the outlet end of the delivery pump is connected to the inlet end of the second regulating valve, and the outlet end of the second regulating valve merges with the hot end outlet of the third heat exchanger and is then connected to the input end of the third shut-off valve. A fourth shut-off valve is installed on the pipeline between the outlet end of the second regulating valve and the hot end outlet of the third heat exchanger. The outlet end of the second regulating valve is also connected to the second methane storage tank port of the methane storage tank, and a fifth shut-off valve is provided on the pipeline between the outlet end of the second regulating valve and the second methane storage tank port. The first liquid level sensor is installed on the side wall of the separation tank; The first liquid level sensor is interlocked with the second regulating valve to control the opening degree of the second regulating valve based on the internal liquid level of the separation tank detected by the first liquid level sensor.

[0012] According to one aspect of the present invention, a third regulating valve is provided on the connecting pipeline between the cold end outlet of the second heat exchanger and the cold end inlet of the third heat exchanger; A connection bypass is provided between the cold end outlet of the first heat exchanger and the cold end outlet of the second heat exchanger, and a fourth regulating valve is provided in the connection bypass. The second heat exchanger is equipped with an interlocked temperature sensor at its hot end outlet. The interlocked temperature sensor is interlocked with the fourth regulating valve to control the opening degree of the fourth regulating valve based on the hot end outlet temperature of the second heat exchanger detected by the interlocked temperature sensor.

[0013] According to one aspect of the present invention, the temperature control unit includes: a temperature controller, a first temperature sensor, a first flow sensor, a second temperature sensor, a third temperature sensor, and a second flow sensor connected to the temperature controller; On the pipeline from the cold end outlet of the second heat exchanger to the third regulating valve, the first temperature sensor and the first flow sensor are installed in sequence. The second temperature sensor is installed on the pipeline between the hot end outlet of the third heat exchanger and the third shut-off valve, and the installation position of the second temperature sensor and the connection position of the outlet end of the second regulating valve are arranged sequentially along the direction close to the third shut-off valve. The third temperature sensor and the second flow sensor are installed on the pipeline between the second shut-off valve and the hot end inlet of the third heat exchanger.

[0014] According to one aspect of the present invention, the hot end of the first heat exchanger is used to connect to an external air source, and a fifth regulating valve is provided at the hot end inlet of the first heat exchanger. The third regulating valve and the fifth regulating valve are respectively connected to the temperature controller; The cold end outlet of the third heat exchanger is connected to the outside atmosphere.

[0015] To achieve the above-mentioned objective, this invention provides a zero-loss methane propellant supercooling refueling method, based on the aforementioned zero-loss methane propellant supercooling refueling system, comprising: S1. Liquid nitrogen is continuously supplied to the cold ends of the first heat exchanger, the second heat exchanger and the third heat exchanger in sequence based on the liquid nitrogen supply unit; S2. The methane supply unit continuously supplies liquid methane to the hot end of the third heat exchanger, and the liquid methane exchanges heat with the cold end of the third heat exchanger to be converted into subcooled methane and fed into the subcooled methane storage tank. S3. The gaseous methane in the subcooled methane storage tank is fed from the top to the hot end of the second heat exchanger, and the gaseous methane is converted into subcooled methane after heat exchange with the cold end of the second heat exchanger and fed into the separation and recovery module. S4. The subcooled methane in the separation and recovery module is combined with the subcooled methane converted after heat exchange with the third heat exchanger under controlled conditions and input into the subcooled methane storage tank (3); and / or, the subcooled methane in the separation and recovery module is returned to the methane supply unit under controlled conditions; S5. The gaseous methane in the separation and recovery module is reintroduced into the methane supply unit.

[0016] According to one aspect of the present invention, in the liquid nitrogen supply unit, the liquid nitrogen saturation temperature is raised above the freezing point of methane by pressurizing the liquid nitrogen in the liquid nitrogen storage tank, and the liquid nitrogen temperature is raised to near the saturation temperature before the liquid nitrogen cools the methane, which effectively avoids the freezing of methane and makes full use of the cooling capacity of liquid nitrogen phase change.

[0017] According to one aspect of the present invention, the temperature control unit obtains multiple temperature and flow parameters and adopts a feedforward-feedback control method to achieve precise control of liquid nitrogen temperature and subcooled methane temperature, thereby preventing icing in the system pipeline and ensuring stable system operation. According to one aspect of the present invention, by setting up a second heat exchanger and a separation tank, the methane exhaust gas in the subcooled methane storage tank is liquefied and recovered, thereby achieving lossless refueling of methane propellant and avoiding environmental problems such as propellant waste and greenhouse effect caused by methane gas emissions. According to one aspect of the present invention, the system fully utilizes the cold and hot energy of the medium. In the second heat exchanger, the methane exhaust gas from the subcooled methane storage tank is liquefied by cryogenic liquid nitrogen. The opening of the fourth regulating valve is controlled by the temperature of the hot end outlet of the second heat exchanger detected by the interlocking temperature sensor, ensuring that the methane does not solidify. At the same time, the cryogenic liquid nitrogen is heated to near the saturation temperature, thereby reducing the amount of air used in the first heat exchanger and reducing the overall energy consumption of the system.

[0018] According to one aspect of the present invention, the present invention effectively avoids icing during the supercooled refueling of methane propellant, and at the same time effectively reduces methane emissions during the methane refueling process, thereby achieving full refueling and utilization of methane. Attached Figure Description

[0019] Figure 1This is a structural diagram of a zero-loss methane propellant supercooling refueling system according to one embodiment of the present invention. Detailed Implementation

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0021] In describing embodiments of the present invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" express orientations or positional relationships based on the orientations or positional relationships shown in the relevant drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limitations on the present invention.

[0022] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described in detail here, but the embodiments of the present invention are not limited to the following embodiments.

[0023] like Figure 1 As shown, according to one embodiment of the present invention, a zero-loss methane propellant supercooling refueling system includes: a liquid nitrogen supply unit 1, a methane supply unit 2, a supercooled methane storage tank 3, a heat exchange pipeline unit 4 for connecting the liquid nitrogen supply unit 1, the methane supply unit 2, and the supercooled methane storage tank 3, and a temperature control unit 5 connected to the heat exchange pipeline unit 4; in this embodiment, the liquid nitrogen supply unit 1 uses the heat exchange pipeline unit 4 as a cold source for heat exchange, thereby cooling the methane output from the methane supply unit 2 during the refueling process to form supercooled methane which is then input into the supercooled methane storage tank 3.

[0024] like Figure 1As shown, according to one embodiment of the present invention, the heat exchange pipeline unit 4 includes: a first heat exchanger 41, a second heat exchanger 42, a third heat exchanger 43, and a separation and recovery module 44; wherein, the liquid nitrogen supply unit 1 is connected to the cold end of the first heat exchanger 41, and the cold ends of the first heat exchanger 41, the second heat exchanger 42, and the third heat exchanger 43 are connected in series. Thus, the liquid nitrogen output by the liquid nitrogen supply unit 1 first passes through the cold end of the first heat exchanger 41 to achieve heat exchange with the hot end, so as to achieve temperature regulation of the liquid nitrogen, so as to fully avoid the liquid nitrogen temperature being too low and causing the liquid methane to condense during the subsequent subcooling process. This solution ensures the purity of the subcooled methane while meeting the needs of subcooling treatment.

[0025] In this embodiment, the methane output from the methane supply unit 2 is fed into the subcooled methane storage tank 3 after exchanging heat with the third heat exchanger 43. The series connection of the heat exchangers ensures that the temperature of the liquid nitrogen, after passing through the first heat exchanger 41 and the second heat exchanger 42, is adequately controlled within the subcooling range of the liquid methane. Thus, the sequentially heated liquid nitrogen is fed into the third heat exchanger 43 and directly exchanges heat with the liquid methane. The liquid methane passing through the third heat exchanger 43 can then be directly sent to the subcooled methane storage tank 3 for storage without additional processing. This significantly accelerates the subcooling process, achieving high processing efficiency while effectively simplifying the entire filling pipeline structure from the methane supply unit 2 to the subcooled methane storage tank 3, greatly reducing the equipment complexity and cost of the subcooling process.

[0026] In this embodiment, the methane output from the exhaust end of the subcooled methane storage tank 3 is fed into the separation and recovery module 44 after heat exchange with the second heat exchanger 42; wherein, the separation and recovery module 44 is connected to the subcooled methane storage tank 3 and the methane supply unit 2, for the purpose of collecting the recovered subcooled methane into the subcooled methane storage tank 3, and / or for the purpose of returning the recovered subcooled methane to the methane supply unit 2.

[0027] Through the above settings, this scheme fully considers the gaseous methane remaining in the subcooled methane storage tank 3, realizes the recovery of gaseous methane in the subcooled methane storage tank 3 and directly realizes the subcooling treatment without introducing it into the third heat exchanger 43, and realizes the physical separation of the two subcooling treatment processes. Thus, it effectively avoids the influence between the two subcooling treatment processes and fully realizes the non-destructive subcooling refueling of methane.

[0028] Furthermore, this solution further arranges a separation and recovery module 44 to separate the subcooled methane formed after passing through the second heat exchanger 42, effectively avoiding the impact on the purity of the subcooled methane in the subcooled methane storage tank 3, thus making this solution have a better filling effect.

[0029] In addition, this solution can dynamically return the recovered gaseous methane to the methane supply unit 2 to avoid excessive storage of the recovered methane in the separation and recovery module 44, which is more beneficial to ensuring the safety and stability of the entire system.

[0030] like Figure 1 As shown, according to one embodiment of the present invention, the liquid nitrogen supply unit 1 includes: a liquid nitrogen storage tank 11 and a pressure boosting heat exchanger 12; wherein, the function of the pressure boosting heat exchanger 12 is to cyclically pressurize and exchange heat on the liquid nitrogen stored in the liquid nitrogen storage tank 11, so that the internal pressure in the liquid nitrogen storage tank 11 can always be higher than the set pressure, thereby ensuring that the liquid nitrogen supply unit 1 can stably and reliably provide a cold source to the heat exchange pipeline unit 4, so as to ensure the continuous and reliable operation of this scheme.

[0031] In this embodiment, the liquid nitrogen storage tank 11 is provided with a first storage tank port, a second storage tank port, and a third storage tank port; wherein, the first and second storage tank ports are located near the bottom of the liquid nitrogen storage tank 11; and the third storage tank port is located at the top of the liquid nitrogen storage tank 11; thereby, the inlet end of the pressurization heat exchanger 12 is connected to the first storage tank port, and the outlet end of the pressurization heat exchanger 12 is connected to the third storage tank port; furthermore, the liquid nitrogen in the liquid nitrogen storage tank 11 can be input into the pressurization heat exchanger 12 through the first storage tank port, and after pressurization and heat exchange, it is transported back to the liquid nitrogen storage tank 11.

[0032] In this embodiment, the second storage tank port is connected to the cold end inlet of the first heat exchanger 41 to realize the delivery of cold source to the subsequent heat exchange pipeline unit 4.

[0033] like Figure 1 As shown, according to one embodiment of the present invention, the liquid nitrogen supply unit 1 further includes: a first regulating valve 13, a first pressure sensor 14, and a first shut-off valve 15; wherein, the first regulating valve 13 is disposed on the pipeline between the inlet end of the booster heat exchanger 12 and the port of the first storage tank; the first pressure sensor 14 is connected near the top of the liquid nitrogen storage tank 11 and is used to monitor the pressure inside the liquid nitrogen storage tank 11; in this embodiment, the first pressure sensor 14 is connected to the first regulating valve 13 to achieve interlocking between the first pressure sensor 14 and the first regulating valve 13, and then, based on the pressure inside the liquid nitrogen storage tank 11 collected by the first pressure sensor 14, the opening of the first regulating valve 13 is adjusted to ensure dynamic circulation control of liquid nitrogen, so that the pressure inside the liquid nitrogen storage tank 11 is accurately controlled above the set value.

[0034] In this embodiment, the freezing point of methane is approximately 90.7 K. To prevent methane from solidifying during the supercooling process with liquid nitrogen, the set pressure in the liquid nitrogen storage tank 11 should be higher than 0.4 MPa. At this pressure, the saturation temperature of liquid nitrogen is 91.2 K, which is higher than the freezing point of methane, thus preventing solidification of methane during supercooling. Furthermore, when the first pressure sensor 14 in the liquid nitrogen supply unit 1 detects that the pressure in the liquid nitrogen storage tank 11 is lower than 0.4 MPa, the first regulating valve 13, which is interlocked with the first pressure sensor 14, opens. After being heated and vaporized by the booster heat exchanger 12, the liquid nitrogen is input through the third storage port at the top of the liquid nitrogen storage tank 11, maintaining the pressure inside the liquid nitrogen storage tank 11 at no lower than 0.4 MPa.

[0035] In this embodiment, the first shut-off valve 15 is installed on the pipeline between the second tank port and the cold end inlet of the first heat exchanger 41. Thus, the on / off control of the liquid nitrogen input to the first heat exchanger 41 can be achieved by opening the first shut-off valve 15.

[0036] like Figure 1 As shown, according to one embodiment of the present invention, the methane supply unit 2 includes: a methane storage tank 21, a booster pump 22, and a second shut-off valve 23; wherein, the methane storage tank 21 is used to store liquid methane for subsequent subcooling treatment. In this embodiment, the methane storage tank 21 is provided with a first methane storage tank port, a second methane storage tank port, and a third methane storage tank port; the first methane storage tank port is located at the lower part of the methane storage tank 21 and is connected to the booster pump 22; Furthermore, the booster pump 22 can be installed in or outside the methane storage tank 21, and the outlet end of the booster pump 22 is connected to the hot end inlet of the third heat exchanger 43; thus, the liquid methane stored in the methane storage tank 21 can be pumped to the third heat exchanger 43 by the action of the booster pump 22, so as to exchange heat with the cold end in the third heat exchanger 43 and cool down to become subcooled methane.

[0037] Furthermore, a second shut-off valve 23 is installed on the pipeline between the outlet end of the booster pump 22 and the hot end inlet of the third heat exchanger 43. Thus, the on / off control of the liquid methane output from the booster pump 22 can be achieved through the second shut-off valve 23.

[0038] Furthermore, the second methane storage tank port is located in the middle of the methane storage tank 21, and the third methane storage tank port is located at the top of the methane storage tank 21. The second and third methane storage tank ports are respectively connected to the separation and recovery module 44. Thus, the second and third methane storage tank ports can be connected to different structures to achieve the recovery of methane in different states, which more effectively improves the methane recovery and reuse capability of this scheme, enabling the scheme to fully achieve the function of zero-loss methane refueling.

[0039] like Figure 1 As shown, according to one embodiment of the present invention, the subcooled methane storage tank 3 is provided with a first storage tank port and a second storage tank port; wherein, the first storage tank port is located at the top of the subcooled methane storage tank 3 and is connected to the hot end inlet of the second heat exchanger 42; the second storage tank port is located below the first storage tank port and is connected to the hot end outlet of the third heat exchanger 43; in this embodiment, a third shut-off valve 31 is provided on the pipeline between the second storage tank port and the hot end outlet of the third heat exchanger 43. The third shut-off valve 31 is used to control the flow of subcooled methane into the subcooled methane storage tank 3.

[0040] like Figure 1 As shown, according to one embodiment of the present invention, the separation and recovery module 44 includes: a separation tank 441, a filter 442, a second regulating valve 443, a first liquid level sensor 444, a transfer pump 445, a fourth shut-off valve 446, and a fifth shut-off valve 447; wherein, the separation tank 441 is provided with a first tank port, a second tank port, and a third tank port; specifically, the first tank port is located at the top of the separation tank 441, the third tank port is located at the bottom of the separation tank 441, and the second tank port is located on the side wall of the separation tank 441; thereby, the first tank port is provided with an exhaust pipe to connect to the third methane storage tank port of the methane storage tank 21; wherein, the exhaust pipe is provided with a switch valve body to realize the on / off control of the exhaust pipe. Further, the second tank port is connected to the hot end outlet of the second heat exchanger 42, thereby recovering the subcooled methane obtained through heat exchange in the second heat exchanger 42 back to the separation tank 441. Furthermore, the third tank port is connected to the inlet end of filter 442, the outlet end of filter 442 is connected to the inlet end of transfer pump 445, the outlet end of transfer pump 445 is connected to the inlet end of second regulating valve 443, and the outlet end of second regulating valve 443 merges with the hot end outlet of third heat exchanger 43 and is then connected to the input end of third shut-off valve 31. In this embodiment, filter 442 is used to filter out methane solids and impurities present in the subcooled methane output from separator 441 to ensure the purity of the collected subcooled methane, so that the subcooled methane input into subcooled methane storage tank 3 meets the corresponding requirements.

[0041] In this embodiment, a fourth shut-off valve 446 is installed on the pipeline between the outlet of the second regulating valve 443 and the hot end outlet of the third heat exchanger 43. Thus, the subcooled methane after passing through the second regulating valve 443 can be further combined with another stream of subcooled methane at the inlet of the third shut-off valve 31. Furthermore, an output bypass is provided at the outlet of the second regulating valve 443 to connect to the second methane storage tank port of the methane storage tank 21, and a fifth shut-off valve 447 is installed on the pipeline between the outlet of the second regulating valve 443 and the second methane storage tank port. With the above configuration, when adding subcooled methane to the subcooled methane storage tank 3, the subcooled methane in the separator 441 can directly pass through the fourth shut-off valve 446 to the subcooled methane storage tank 3. After adding, the remaining subcooled methane in the separator 441 can return to the methane storage tank 21 through the fifth shut-off valve 447.

[0042] In this embodiment, a first liquid level sensor 444 is installed on the side wall of the separator 441. The first liquid level sensor 444 is interlocked with a second regulating valve 443 to control the opening degree of the second regulating valve 443 based on the internal liquid level of the separator 441 detected by the first liquid level sensor 444. This configuration effectively ensures the safety of the liquid level in the separator 441, thereby achieving dynamic adjustment of the subcooled methane in the separator 441.

[0043] like Figure 1 As shown, according to one embodiment of the present invention, a third regulating valve 45 is provided on the connecting pipeline between the cold end outlet of the second heat exchanger 42 and the cold end inlet of the third heat exchanger 43. Through this arrangement, the liquid nitrogen input to the third heat exchanger 43 is dynamically controlled by controlling the opening degree of the third regulating valve 45, thereby achieving dynamic control of the cooling capacity in the third heat exchanger 43. This ensures that the liquid methane input to the third heat exchanger 43 is accurately subcooled and prevents condensation of the liquid methane.

[0044] In this embodiment, a bypass is provided between the cold end outlet of the first heat exchanger 41 and the cold end outlet of the second heat exchanger 42, and a fourth regulating valve 421 is provided in the bypass. An interlocking temperature sensor 422 is provided at the hot end outlet of the second heat exchanger 42. Thus, the interlocking temperature sensor 422 is interlocked with the fourth regulating valve 421, controlling the opening degree of the fourth regulating valve 421 based on the temperature detected at the hot end outlet of the second heat exchanger 42 by the interlocking temperature sensor 422. Through the above arrangement, the constant temperature of the subsequent liquid nitrogen supply can be further effectively and sufficiently guaranteed, which is more beneficial to ensuring the reliable and stable operation of the system afterwards, and more effectively improves the adjustability and control reliability of this solution. Furthermore, the interlocking structure further ensures that the methane output from the hot end outlet of the second heat exchanger 42 is in a subcooled state, while preventing the methane from solidifying. This is beneficial for ensuring the temperature matching of the methane with other subcooled methane streams when it flows into the subcooled methane storage tank 3, for ensuring the stability of the methane state in the cold methane storage tank 3, and for suppressing the generation of gaseous methane in the cold methane storage tank 3.

[0045] In this embodiment, the cold end outlet of the third heat exchanger 43 is connected to the outside atmosphere. As a result, after the liquid nitrogen passes through the first heat exchanger 41, the second heat exchanger 42 and the third heat exchanger 43 in sequence, the temperature of the liquid nitrogen increases step by step. Then, after exchanging heat with the liquid methane output by the methane supply unit 2 in the third heat exchanger 43, it can be vaporized and discharged into the outside atmosphere.

[0046] like Figure 1 As shown, according to one embodiment of the present invention, the temperature control unit 5 includes: a temperature controller 51, a first temperature sensor 52, a first flow sensor 53, a second temperature sensor 54, a third temperature sensor 55, and a second flow sensor 56 connected to the temperature controller 51; wherein, on the pipeline from the cold end outlet of the second heat exchanger 42 to the third regulating valve 45, the first temperature sensor 52 and the first flow sensor 53 are arranged sequentially; the second temperature sensor 54 is arranged on the pipeline between the hot end outlet of the third heat exchanger 43 and the third shut-off valve 31, and along the direction close to the third shut-off valve 31, the installation position of the second temperature sensor 54 and the connection position of the outlet end of the second regulating valve 443 are arranged sequentially; furthermore, the third temperature sensor 55 and the second flow sensor 56 are arranged on the pipeline between the second shut-off valve 23 and the hot end inlet of the third heat exchanger 43.

[0047] like Figure 1 As shown, according to one embodiment of the present invention, the hot end of the first heat exchanger 41 is used to connect to an external air source, and a fifth regulating valve 411 is provided at the inlet of the hot end of the first heat exchanger 41; in this embodiment, the third regulating valve 45 and the fifth regulating valve 411 are respectively connected to the temperature controller 51.

[0048] With the above setup, the hot end of the first heat exchanger 41 is connected to an external air source, thereby directly utilizing the heat from the outside air to adjust the temperature of the liquid nitrogen input into the first heat exchanger 41. This improves the convenience of temperature control during subsequent subcooling processes and effectively ensures the subcooling effect of this solution.

[0049] Furthermore, by using an external air source as a heat source to control the temperature of liquid nitrogen in the first heat exchanger 41, the energy of the external air source can be fully utilized, making the liquid nitrogen temperature control method simpler and less costly. In addition, by flexibly controlling the opening of the fifth regulating valve 411 to match the control flow rate with the liquid nitrogen flow rate, a simple structure can achieve the effect of accurate and flexible adjustment of liquid nitrogen temperature.

[0050] Furthermore, by sequentially installing a first temperature sensor 52 and a first flow sensor 53 on the pipeline from the cold end outlet of the second heat exchanger 42 to the third regulating valve 45, interlocking and feedforward-feedback control can be achieved between the first temperature sensor 52, the first flow sensor 53, and the fifth regulating valve 411. This enables the flow rate of the external air source input, ensuring that the temperature of the liquid nitrogen output from the second heat exchanger 42 is always higher than the freezing point of methane and lower than the saturation temperature of liquid nitrogen. This fully guarantees the temperature of the liquid nitrogen input to the third heat exchanger 43, thereby ensuring the purity of the subcooled methane formed after heat exchange in the third heat exchanger 43. It also avoids the need for complex structures such as filters, achieving the advantages of simplified structure and reduced transport resistance.

[0051] Furthermore, based on the established first temperature sensor 52, first flow sensor 53, second temperature sensor 54, third temperature sensor 55, and second flow sensor 56, as well as the connection between the temperature controller 51 and the third regulating valve 45, the liquid nitrogen input at the cold end of the third heat exchanger 43, and the methane input and output at the hot end can all be monitored and controlled in real time, achieving feedforward-feedback control for the subcooling treatment of liquid methane. Specifically, the temperature controller 51 reads the methane flow rate measured by the second flow sensor 56, the methane inlet temperature measured by the third temperature sensor 55, the liquid nitrogen inlet temperature measured by the first temperature sensor 52, the liquid nitrogen flow rate measured by the first flow sensor 53, and the methane outlet temperature measured by the second temperature sensor 54. When the booster pump 22 of the methane storage tank 21 changes the methane delivery flow rate, the temperature controller 51 determines the required liquid nitrogen flow rate based on the heat exchange relationship between liquid nitrogen and methane, expressed as: m N2 =m CH4 ×(T CH4,i -T CH4,o ) / (T CH4,i -T N2 ); Where, m N2 Indicates liquid nitrogen flow rate, m N2 T represents the methane flow rate. CH4,i T represents the inlet temperature of methane. CH4,o T represents the methane outlet temperature. N2 This indicates the inlet temperature of the liquid nitrogen.

[0052] Therefore, the opening of the third regulating valve 45 can be adjusted based on the difference between the recalculated liquid nitrogen flow rate and the liquid nitrogen flow rate collected in real time by the first flow sensor 53, thereby achieving feedforward regulation of the liquid nitrogen flow rate.

[0053] In addition, to ensure that the methane entering the subcooled methane storage tank 3 is at the set temperature, the temperature controller 51 can also adjust the opening of the third regulating valve 45 according to the feedback of the methane outlet temperature measured by the second temperature sensor 54, making the control method more flexible and diverse, and further dynamically adjusting the entire separation and recovery module 44 based on the aforementioned process.

[0054] like Figure 1 As shown, according to one embodiment of the present invention, the present invention provides a zero-loss methane propellant supercooling refueling method, which is implemented based on the aforementioned zero-loss methane propellant supercooling refueling system, and includes: S1. Liquid nitrogen is continuously supplied to the cold ends of the first heat exchanger 41, the second heat exchanger 42 and the third heat exchanger 43 in sequence based on the liquid nitrogen supply unit 1; S2. The methane supply unit 2 continuously supplies liquid methane to the hot end of the third heat exchanger 43, and the liquid methane exchanges heat with the cold end of the third heat exchanger 43 to be converted into subcooled methane and input into the subcooled methane storage tank 3. S3. Gaseous methane in the subcooled methane storage tank 3 is fed from the top to the hot end of the second heat exchanger 42, and after heat exchange with the cold end of the second heat exchanger 42, the gaseous methane is converted into subcooled methane and fed into the separation and recovery module 44. S4. The subcooled methane in the separation and recovery module 44 is combined with the subcooled methane converted after heat exchange in the third heat exchanger 43 under controlled conditions and input into the subcooled methane storage tank 3; and / or, the subcooled methane in the separation and recovery module 44 is returned to the methane supply unit 2 under controlled conditions; S5. Gaseous methane in separation and recovery module 44 is reintroduced into methane supply unit 2.

[0055] like Figure 1As shown, according to one embodiment of the present invention, in step S1, in the step of continuously supplying liquid nitrogen to the cold ends of the first heat exchanger 41, the second heat exchanger 42 and the third heat exchanger 43 by the liquid nitrogen supply unit 1, the liquid nitrogen storage tank 11 of the liquid nitrogen supply unit 1 needs to be pre-filled with sufficient liquid nitrogen, and it realizes dynamic control of the internal liquid nitrogen based on the set pressurized heat exchanger 12, the first regulating valve 13 and the first pressure sensor 14. Specifically, the opening of the first regulating valve 13 is adjusted based on the pressure inside the liquid nitrogen storage tank 11 collected by the first pressure sensor 14 to ensure dynamic circulation control of liquid nitrogen, so that the pressure inside the liquid nitrogen storage tank 11 is accurately controlled above the set value.

[0056] In this embodiment, the freezing point of methane is approximately 90.7 K. To prevent methane from solidifying during the supercooling process with liquid nitrogen, the set pressure in the liquid nitrogen storage tank 11 should be higher than 0.4 MPa. At this pressure, the saturation temperature of liquid nitrogen is 91.2 K, which is higher than the freezing point of methane, thus preventing solidification of methane during supercooling. Furthermore, when the first pressure sensor 14 in the liquid nitrogen supply unit 1 detects that the pressure in the liquid nitrogen storage tank 11 is lower than 0.4 MPa, the first regulating valve 13, which is interlocked with the first pressure sensor 14, opens. After being heated and vaporized by the booster heat exchanger 12, the liquid nitrogen is input through the third storage port at the top of the liquid nitrogen storage tank 11, maintaining the pressure inside the liquid nitrogen storage tank 11 at no lower than 0.4 MPa.

[0057] like Figure 1 As shown, according to one embodiment of the present invention, in step S2, the methane supply unit 2 continuously supplies liquid methane to the hot end of the third heat exchanger 43, and the liquid methane exchanges heat with the cold end of the third heat exchanger 43 to be converted into subcooled methane and input into the subcooled methane storage tank 3. The liquid nitrogen supply unit 1 continuously supplies liquid nitrogen to the cold ends of the first heat exchanger 41, the second heat exchanger 42 and the third heat exchanger 43 connected in series. In the first heat exchanger 41, under the control of the temperature control unit 5, the opening of the fifth regulating valve 411 is controlled to dynamically adjust the heat exchange effect of the first heat exchanger 41, so that the liquid nitrogen flowing through the first heat exchanger 41 is controlled at a temperature that can subcool the methane flowing through the second heat exchanger 42. Then the liquid nitrogen further flows into the third heat exchanger 43 to subcool the methane flowing through it.

[0058] In this embodiment, the methane supply unit 2 supplies liquid methane to the third heat exchanger 43 of the aforementioned heat exchange pipeline unit 4. Then, under the control of the temperature control unit 5, the heat exchange pipeline unit 4 is in a linkage control state to achieve subcooling of the methane flowing through the third heat exchanger 43.

[0059] like Figure 1As shown, according to one embodiment of the present invention, in step S3, gaseous methane in the subcooled methane storage tank 3 is input from the top to the hot end of the second heat exchanger 42, and after heat exchange with the cold end of the second heat exchanger 42, the gaseous methane is converted into subcooled methane and input into the separation and recovery module 44. As subcooled methane flows into the subcooled methane storage tank 3, the residual gaseous methane can flow into the second heat exchanger 42 through the pipe connected to the top. After heat exchange with the cold end of the second heat exchanger 42, the gaseous methane is converted into subcooled methane and flows into the separation tank 441. In this embodiment, the first liquid level sensor 444 in the separation and recovery module 44 is interlocked with the second regulating valve 443 to control the opening of the second regulating valve 443 based on the internal liquid level of the separation tank 441 detected by the first liquid level sensor 444. Through the above settings, the safety of the liquid level in the separation tank 441 is effectively ensured, thereby realizing the dynamic adjustment of the subcooled methane in the separation tank 441.

[0060] like Figure 1 As shown, according to one embodiment of the present invention, in step S4, the subcooled methane in the separation and recovery module 44 is combined with the subcooled methane converted after heat exchange with the third heat exchanger 43 under controlled conditions and input into the subcooled methane storage tank 3. In the step, the subcooled methane flows sequentially through the bottom of the separation tank 441 through the filter 442, the transfer pump 445, the second regulating valve 443, and the fourth shut-off valve 446 and then into the inlet of the third shut-off valve 31 to achieve the combination with another stream of subcooled methane, thereby flowing into the subcooled methane storage tank 3. Alternatively, after the subcooled methane storage tank 3 is filled, the subcooled methane is recovered by flowing sequentially through the bottom of the separation tank 441 through the filter 442, the transfer pump 445, the second regulating valve 443, and the fifth shut-off valve 447 and then into the methane storage tank 21, thereby achieving smooth and reliable system operation.

[0061] like Figure 1 As shown, according to one embodiment of the present invention, in step S5, the gaseous methane in the separation and recovery module 44 is reintroduced into the methane supply unit 2, thereby achieving full recovery of the gaseous methane in the separation tank 441, thus effectively avoiding the retention of gaseous methane in the separation tank 441, which is more beneficial to improving the filling efficiency of this scheme.

[0062] The above description is merely an example of a specific solution of the present invention. For any devices and structures not described in detail herein, it should be understood that they are implemented using common devices and methods already available in the art.

[0063] The above description is merely one embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A zero-loss methane propellant subcooling refueling system, characterized in that, include: Liquid nitrogen supply unit (1), methane supply unit (2), subcooled methane storage tank (3), heat exchange pipeline unit (4) for connecting the liquid nitrogen supply unit (1), the methane supply unit (2) and the subcooled methane storage tank (3), and temperature control unit (5) connected to the heat exchange pipeline unit (4). The heat exchange pipeline unit (4) includes: a first heat exchanger (41), a second heat exchanger (42), a third heat exchanger (43), and a separation and recovery module (44). The liquid nitrogen supply unit (1) is connected to the cold end of the first heat exchanger (41), and the cold ends of the first heat exchanger (41), the second heat exchanger (42), and the third heat exchanger (43) are connected in series. The methane output from the methane supply unit (2) is fed into the subcooled methane storage tank (3) after exchanging heat with the third heat exchanger (43). The methane output from the exhaust end of the subcooled methane storage tank (3) is fed into the separation and recovery module (44) after exchanging heat with the second heat exchanger (42). The separation and recovery module (44) is connected to the supercooled methane storage tank (3) and the methane supply unit (2) for receiving the recovered supercooled methane into the supercooled methane storage tank (3) and / or for returning the recovered supercooled methane to the methane supply unit (2).

2. The zero-loss methane propellant subcooling refueling system according to claim 1, characterized in that, The liquid nitrogen supply unit (1) includes: a liquid nitrogen storage tank (11) and a pressurized heat exchanger (12). The liquid nitrogen storage tank (11) is provided with a first storage tank port, a second storage tank port and a third storage tank port; The first tank port and the second tank port are located near the bottom of the liquid nitrogen tank (11); The third storage tank port is located at the top of the liquid nitrogen storage tank (11); The inlet end of the booster heat exchanger (12) is connected to the first storage tank port, and the outlet end of the booster heat exchanger (12) is connected to the third storage tank port. The second storage tank port is connected to the cold end inlet of the first heat exchanger (41).

3. The zero-loss methane propellant subcooling refueling system according to claim 2, characterized in that, The liquid nitrogen supply unit (1) further includes: a first regulating valve (13), a first pressure sensor (14), and a first shut-off valve (15). The first regulating valve (13) is installed on the pipeline between the inlet end of the booster heat exchanger (12) and the port of the first storage tank; The first pressure sensor (14) is connected near the top of the liquid nitrogen tank (11) and is used to monitor the pressure inside the liquid nitrogen tank (11); The first pressure sensor (14) is interlocked with the first regulating valve (13) to adjust the opening of the first regulating valve (13) based on the pressure inside the liquid nitrogen tank (11) collected by the first pressure sensor (14), so as to ensure that the pressure inside the liquid nitrogen tank (11) is higher than the set value. The first shut-off valve (15) is installed on the pipeline between the second tank port and the cold end inlet of the first heat exchanger (41).

4. The zero-loss methane propellant subcooling refueling system according to claim 3, characterized in that, The methane supply unit (2) includes: a methane storage tank (21), a booster pump (22), and a second shut-off valve (23); The methane storage tank (21) is provided with a first methane storage tank port, a second methane storage tank port and a third methane storage tank port; The first methane storage tank port is located at the lower part of the methane storage tank (21), and the first methane storage tank port is connected to the booster pump (22); The booster pump (22) can be installed inside or outside the methane storage tank (21), and the outlet end of the booster pump (22) is connected to the hot end inlet of the third heat exchanger (43); The second shut-off valve (23) is installed on the pipeline between the outlet end of the booster pump (22) and the hot end inlet of the third heat exchanger (43); The second methane storage tank port is located in the middle of the methane storage tank (21), and the third methane storage tank port is located in the upper part of the methane storage tank (21). The second methane storage tank port and the third methane storage tank port are respectively connected to the separation and recovery module (44).

5. The zero-loss methane propellant subcooling refueling system according to claim 4, characterized in that, The subcooled methane storage tank (3) is provided with a first storage tank port and a second storage tank port; The first tank port is located at the top of the subcooled methane tank (3), and the first tank port is connected to the hot end inlet of the second heat exchanger (42); The second tank port is located below the first tank port, and the second tank port is connected to the hot end outlet of the third heat exchanger (43); A third shut-off valve (31) is installed on the pipeline between the second tank port and the hot end outlet of the third heat exchanger (43).

6. The zero-loss methane propellant subcooling refueling system according to claim 5, characterized in that, The separation and recovery module (44) includes: a separation tank (441), a filter (442), a second regulating valve (443), a first liquid level sensor (444), a transfer pump (445), a fourth shut-off valve (446), and a fifth shut-off valve (447). The separation tank (441) is provided with a first tank port, a second tank port and a third tank port; The first tank port is located at the top of the separation tank (441), the third tank port is located at the bottom of the separation tank (441), and the second tank port is located on the side wall of the separation tank (441). The first tank port is provided with an exhaust pipe, which is connected to the third methane storage tank port of the methane storage tank (21); The second tank port is connected to the hot end outlet of the second heat exchanger (42); The third tank port is connected to the inlet end of the filter (442), the outlet end of the filter (442) is connected to the inlet end of the delivery pump (445), the outlet end of the delivery pump (445) is connected to the inlet end of the second regulating valve (443), and the outlet end of the second regulating valve (443) is connected to the input end of the third shut-off valve (31) after merging with the hot end outlet of the third heat exchanger (43). A fourth shut-off valve (446) is provided on the pipeline between the outlet end of the second regulating valve (443) and the hot end outlet of the third heat exchanger (43). The outlet end of the second regulating valve (443) is also connected to the second methane storage tank port of the methane storage tank (21), and a fifth shut-off valve (447) is provided on the pipeline between the outlet end of the second regulating valve (443) and the second methane storage tank port. The first liquid level sensor (444) is installed on the side wall of the separation tank (441); The first liquid level sensor (444) is interlocked with the second regulating valve (443) to control the opening degree of the second regulating valve (443) based on the internal liquid level of the separation tank (441) detected by the first liquid level sensor (444).

7. The zero-loss methane propellant subcooling refueling system according to claim 6, characterized in that, A third regulating valve (45) is provided on the connecting pipe between the cold end outlet of the second heat exchanger (42) and the cold end inlet of the third heat exchanger (43). A connection bypass is provided between the cold end outlet of the first heat exchanger (41) and the cold end outlet of the second heat exchanger (42), and a fourth regulating valve (421) is provided in the connection bypass. The second heat exchanger (42) is equipped with an interlocked temperature sensor (422) at its hot end outlet. The interlocked temperature sensor (422) is interlocked with the fourth regulating valve (421) to control the opening degree of the fourth regulating valve (421) based on the hot end outlet temperature of the second heat exchanger (42) detected by the interlocked temperature sensor (422).

8. The zero-loss methane propellant subcooling refueling system according to claim 7, characterized in that, The temperature control unit (5) includes: a temperature controller (51), a first temperature sensor (52), a first flow sensor (53), a second temperature sensor (54), a third temperature sensor (55), and a second flow sensor (56) connected to the temperature controller (51). On the pipeline from the cold end outlet of the second heat exchanger (42) to the third regulating valve (45), the first temperature sensor (52) and the first flow sensor (53) are sequentially installed; The second temperature sensor (54) is installed on the pipeline between the hot end outlet of the third heat exchanger (43) and the third shut-off valve (31), and the installation position of the second temperature sensor (54) and the connection position of the outlet end of the second regulating valve (443) are arranged sequentially along the direction close to the third shut-off valve (31). The third temperature sensor (55) and the second flow sensor (56) are installed on the pipeline between the second shut-off valve (23) and the hot end inlet of the third heat exchanger (43).

9. The zero-loss methane propellant subcooling refueling system according to claim 8, characterized in that, The hot end of the first heat exchanger (41) is used to connect to an external air source, and a fifth regulating valve (411) is provided at the hot end inlet of the first heat exchanger (41). The third regulating valve (45) and the fifth regulating valve (411) are respectively connected to the temperature controller (51); The cold end outlet of the third heat exchanger (43) is connected to the outside atmosphere.

10. A method for subcooling and refueling methane propellant with zero loss, characterized in that, Based on the zero-loss methane propellant supercooling refueling system according to any one of claims 1 to 9, it comprises: S1. Liquid nitrogen is continuously supplied to the cold ends of the first heat exchanger (41), the second heat exchanger (42) and the third heat exchanger (43) in sequence based on the liquid nitrogen supply unit (1); S2. The methane supply unit (2) continuously supplies liquid methane to the hot end of the third heat exchanger (43), and the liquid methane is converted into subcooled methane after heat exchange with the cold end of the third heat exchanger (43) and input into the subcooled methane storage tank (3); S3. The gaseous methane in the subcooled methane storage tank (3) is fed from the top to the hot end of the second heat exchanger (42), and the gaseous methane is converted into subcooled methane after heat exchange with the cold end of the second heat exchanger (42) and fed into the separation and recovery module (44). S4. The supercooled methane in the separation and recovery module (44) is combined with the supercooled methane converted after heat exchange in the third heat exchanger (43) under controlled conditions and input into the supercooled methane storage tank (3); and / or, the supercooled methane in the separation and recovery module (44) is returned to the methane supply unit (2) under controlled conditions; S5. The gaseous methane in the separation and recovery module (44) is reintroduced into the methane supply unit (2).

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