A piping pre-cooling system and method

Abstract

The application provides a pipeline BOG precooling system and method, the pipeline BOG precooling system, comprising: an oxidant system, a fuel system and a system to be pre-cooled, the oxidant system and the fuel system are provided with pipelines and valves, and the oxidant system and the fuel system are connected with the system to be pre-cooled through the pipelines.The BOG is introduced into the test pipeline to preliminarily precool the pipeline, and the temperature of the test pipeline is lowered in advance.The precooling mode is BOG preliminary precooling, long-time precooling can be carried out by maintaining the state of different valves, and a low-temperature environment is maintained.The BOG precooling process can be carried out synchronously on both sides.Using BOG precooling can effectively reduce the consumption of liquid medium.Effective use of the low-temperature characteristics of exhaust gas reduces the consumption of medium precooling.Using gas precooling can reduce the stress impact of the pipeline, slow down the stress change caused by thermal expansion and contraction in the pipeline, and avoid leakage of valves and flanges caused by temperature change.

Description

Technical Field

[0001] This invention relates to the field of precooling technology for test pipelines of liquid rocket engines, and more particularly to a pipeline precooling system and method. Background Technology

[0002] Liquid oxygen-methane rocket engines use cryogenic media and have extremely high requirements for the inlet temperature before the media pump. Before engine testing, the piping needs to be pre-cooled to meet technical requirements. Pre-cooling involves directly using the liquid media in the piping and performing segmented pre-cooling. The valves at the bottom of the test chamber typically lack opening adjustment functionality. The cryogenic media directly contacts the ambient temperature piping, creating a gas-liquid two-phase flow. Furthermore, during pre-cooling, temperature changes cause stress variations in the piping and accessories, resulting in significant impact on the piping. After the surface media vaporizes, pre-cooling efficiency decreases, and media consumption is high. During pre-cooling, the flange connections, due to the large temperature difference between the upper and lower parts of the piping, pose a risk of leakage due to thermal expansion and contraction, creating a safety hazard. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a pipeline precooling system and method to address the shortcomings of the prior art.

[0004] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a pipeline BOG precooling system, comprising: an oxidant system, a fuel system and a system to be precooled, wherein the oxidant system and the fuel system are both provided with pipelines and valves, and the oxidant system and the fuel system are both connected to the system to be precooled through pipelines.

[0005] The beneficial effects of adopting the technical solution of this invention are as follows: Utilizing the low-temperature characteristics of BOG (Bottle-Off Gas), BOG is introduced into the test pipeline for preliminary pre-cooling, lowering the pipeline temperature in advance and reducing liquid medium consumption and pipeline stress impact during pre-cooling. The pre-cooling method is BOG preliminary pre-cooling, without the participation of liquid medium. Long-term pre-cooling can be achieved by maintaining the states of different valves, maintaining the low-temperature environment. The BOG pre-cooling method for methane in the fuel system is consistent with that for oxygen in the oxidant system, and the BOG pre-cooling process can be carried out simultaneously on both sides. The emission of gas from the storage tank is a necessary procedure before commissioning, and using BOG pre-cooling can effectively reduce the consumption of liquid medium. This method effectively utilizes the low-temperature characteristics of the emitted gas while reducing the consumption of medium pre-cooling. Simultaneously, using gas pre-cooling can reduce pipeline stress impact, mitigate stress changes caused by thermal expansion and contraction within the pipeline, and prevent leaks in valves and flanges due to temperature changes.

[0006] Furthermore, the oxidant system includes: an oxygen tank, an oxygen exhaust valve, an oxygen tank bottom valve, an oxygen gas precooling valve, an oxygen main pipeline precooling and discharge valve, an oxygen shut-off valve, an oxygen pump post-precooling and discharge valve, and an oxygen recovery / discharge system. The top of the oxygen tank is connected to the oxygen exhaust valve via a pipeline, the oxygen exhaust valve is connected to the oxygen recovery / discharge system via a pipeline, the bottom of the oxygen tank is connected to the oxygen tank bottom valve via a pipeline, the oxygen tank bottom valve is connected to the oxygen shut-off valve via the oxygen main pipeline, and one end of the oxygen gas precooling valve is precooled by oxygen gas. The pipeline is connected to the pipeline between the oxygen exhaust valve and the oxygen tank. The other end of the oxygen gas precooling valve and one end of the oxygen main pipeline precooling relief valve are both connected to the oxygen main pipeline through pipelines. The other end of the oxygen main pipeline precooling relief valve and one end of the oxygen pump post-precooling relief valve are both connected to the pipeline between the oxygen exhaust valve and the oxygen recovery / discharge system. The oxygen shut-off valve is connected to the first end of the system to be precooled through a pipeline. The other end of the oxygen pump post-precooling relief valve is connected to the second end of the system to be precooled through a pipeline.

[0007] The beneficial effects of adopting the above-mentioned further technical solution are as follows: When precooling is required, the oxygen gas precooling valve and the oxygen main pipeline precooling drain valve are opened, while the oxygen exhaust valve is closed. This allows the BOG (Bottle-Off Gas) in the oxygen tank to enter the oxygen main pipeline for heat exchange and precooling. After heat exchange in the main pipeline, it enters the oxygen recovery / emission system through the oxygen main pipeline precooling drain valve. Temperature changes are monitored during the precooling process, and precooling is complete when the oxygen main pipeline reaches the required temperature. After the BOG precooling in the main pipeline is completed, the engine system is precooled. This is achieved by opening the oxygen shut-off valve and the oxygen pump post-precooling drain valve, and closing the oxygen main pipeline precooling drain valve, thus precooling the downstream pipeline and the engine system. The BOG flows through the engine connection pipeline and the engine system, and enters the oxygen recovery / emission system through the oxygen pump post-precooling drain valve. The precooling method involves initial BOG precooling without the participation of liquid media. By maintaining the states of different valves, long-term precooling can be performed to maintain a low-temperature environment.

[0008] Furthermore, the first end of the pre-cooling system is connected to the second end of the pre-cooling system via a pipeline; the oxygen recovery / discharge system includes: an oxygen recovery tank and an oxygen venting pipeline, the oxygen venting pipeline being connected to the oxygen recovery tank; the outer sides of the oxygen gas pre-cooling pipeline and the main oxygen pipeline are both covered with a heat insulation layer; an insertion-type temperature sensor is installed at the outlet of the oxygen gas pre-cooling valve and the inlet of the oxygen shut-off valve, or a wall temperature sensor is installed on the outer wall of the main oxygen pipeline.

[0009] The beneficial effects of adopting the above-mentioned further technical solutions are: The main pipeline and gas precooling pipeline are insulated, reducing heat exchange. An insertion temperature sensor is installed at the outlet of the oxygen gas precooling valve to monitor the inlet gas temperature, and an insertion temperature sensor is installed before the oxygen shut-off valve to monitor temperature changes during precooling. A wall temperature sensor installed on the outer wall of the main pipeline can also be used to determine the precooling effect.

[0010] Furthermore, the fuel system includes: a methane tank, a methane exhaust valve, a methane tank bottom valve, a methane gas precooling valve, a methane main pipeline precooling and venting valve, a methane shut-off valve, a methane pump post-pump precooling and venting valve, and a methane emission / recovery system. The top of the methane tank is connected to the methane exhaust valve via a pipeline, the methane exhaust valve is connected to the methane emission / recovery system via a pipeline, the bottom of the methane tank is connected to the methane tank bottom valve via a pipeline, the methane tank bottom valve is connected to the methane shut-off valve via the methane main pipeline, and one end of the methane gas precooling valve is connected to the methane gas... The precooling pipeline is connected to the pipeline between the methane exhaust valve and the methane tank. The other end of the methane gas precooling valve and one end of the methane main pipeline precooling vent valve are both connected to the methane main pipeline via pipelines. The other end of the methane main pipeline precooling vent valve and one end of the methane pump post-precooling vent valve are both connected to the pipeline between the methane exhaust valve and the methane emission / recovery system. The methane shut-off valve is connected to the third end of the system to be precooled via pipeline. The other end of the methane pump post-precooling vent valve is connected to the fourth end of the system to be precooled via pipeline.

[0011] The beneficial effects of adopting the above-mentioned further technical solution are as follows: When precooling is required, the methane gas precooling valve and the methane main pipeline precooling discharge valve are opened, while the methane exhaust valve is closed. This allows the BOG (Bottle-Off Gas) in the methane tank to enter the methane main pipeline for heat exchange and precooling. After heat exchange in the main pipeline, it enters the methane emission / recovery system through the methane main pipeline precooling discharge valve. Temperature changes are monitored during precooling, and precooling is complete when the methane main pipeline reaches the required temperature. After the BOG precooling in the main pipeline is completed, engine system precooling is performed. This is done by opening the methane shut-off valve and the methane pump post-precooling discharge valve, and closing the methane main pipeline precooling discharge valve, thus precooling the downstream pipeline and engine system. The BOG flows through the engine connection pipeline and engine system and enters the methane emission / recovery system through the methane pump post-precooling discharge valve. The precooling method is BOG preliminary precooling, without the participation of liquid media. By maintaining the states of different valves, long-term precooling can be performed to maintain a low-temperature environment.

[0012] Furthermore, the third end of the system to be precooled is connected to the fourth end of the system to be precooled via a pipeline; the methane emission / recovery system includes: a methane recovery tank and a methane venting pipeline, the methane venting pipeline being connected to the methane recovery tank; the outer sides of the methane gas precooling pipeline and the main methane pipeline are both covered with a heat insulation layer; an insertion-type temperature sensor is installed at the outlet of the methane gas precooling valve and the inlet of the methane shut-off valve, or a wall temperature sensor is installed on the outer wall of the main methane pipeline.

[0013] The beneficial effects of adopting the above-mentioned further technical solutions are: The main pipeline and gas precooling pipeline are insulated, reducing heat exchange. An insertion temperature sensor is installed at the outlet of the methane gas precooling valve to monitor the inlet gas temperature, and an insertion temperature sensor is installed before the methane shut-off valve to monitor temperature changes during precooling. A wall temperature sensor installed on the outer wall of the main pipeline can also be used to determine the precooling effect.

[0014] Furthermore, the pre-cooling system is a liquid oxygen-methane rocket engine system or a fueling pipeline system before the rocket body is fueled at the launch site; the pre-cooling system is equipped with a purge gas seal structure for isolating oxygen and methane.

[0015] The beneficial effects of adopting the above-mentioned further technical solution are: the methane BOG precooling of the fuel system is consistent with that of the oxidizer system, and precooling can be carried out simultaneously on both sides. During the precooling process, necessary measures such as purging gas seals need to be added to the engine end to avoid the danger of oxygen and methane coming into contact. The BOG precooling method can be used for precooling liquid oxygen methane rocket engine systems, as well as for precooling the fueling pipes before the rocket body is fueled at the launch site, thus improving its applicability.

[0016] In addition, the present invention also provides a pipeline BOG precooling method. Based on the pipeline BOG precooling system described above, the pipeline BOG precooling method includes: controlling the opening and closing of valves to introduce BOG from the oxidant system and / or fuel system into the system to be precooled for pipeline precooling.

[0017] The beneficial effects of adopting the technical solution of this invention are as follows: Utilizing the low-temperature characteristics of BOG (Bottle-Off Gas), BOG is introduced into the test pipeline for preliminary pre-cooling, lowering the pipeline temperature in advance and reducing liquid medium consumption and pipeline stress impact during pre-cooling. The pre-cooling method is BOG preliminary pre-cooling, without the participation of liquid medium. Long-term pre-cooling can be achieved by maintaining the states of different valves, maintaining the low-temperature environment. The BOG pre-cooling method for methane in the fuel system is consistent with that for oxygen in the oxidant system, and the BOG pre-cooling process can be carried out simultaneously on both sides. The emission of gas from the storage tank is a necessary procedure before commissioning, and using BOG pre-cooling can effectively reduce the consumption of liquid medium. This method effectively utilizes the low-temperature characteristics of the emitted gas while reducing the consumption of medium pre-cooling. Simultaneously, using gas pre-cooling can reduce pipeline stress impact, mitigate stress changes caused by thermal expansion and contraction within the pipeline, and prevent leaks in valves and flanges due to temperature changes.

[0018] Furthermore, the step of introducing BOG from the oxidant system into the pre-cooling system for pipeline pre-cooling by controlling the opening and closing of valves includes: when pre-cooling is required, opening the oxygen gas pre-cooling valve, the oxygen shut-off valve, and the pre-cooling discharge valve after the oxygen pump, and closing the oxygen main pipeline pre-cooling discharge valve and the oxygen exhaust valve; introducing BOG from the oxidant system into the oxygen main pipeline and the pre-cooling system for pipeline pre-cooling; the step of introducing BOG from the fuel system into the pre-cooling system for pipeline pre-cooling by controlling the opening and closing of valves includes: when pre-cooling is required, opening the methane gas pre-cooling valve, the methane shut-off valve, and the methane pump pre-cooling discharge valve, and closing the methane main pipeline pre-cooling discharge valve and the methane exhaust valve; introducing BOG from the fuel system into the methane main pipeline and the pre-cooling system for pipeline pre-cooling.

[0019] The beneficial effects of adopting the above-mentioned further technical solution are: if there are no specific requirements for the pre-cooling temperature, the oxygen shut-off valve can be opened at the beginning of pre-cooling to pre-cool the main pipeline and engine system simultaneously. This improves pre-cooling efficiency and simplifies the operation process.

[0020] Further, when precooling is required, the oxygen gas precooling valve, oxygen shut-off valve, and oxygen pump post-precooling drain valve are opened, while the oxygen main pipeline precooling drain valve and oxygen exhaust valve are closed. The steps for introducing BOG from the oxidant system into the oxygen main pipeline and the system to be precooled for pipeline precooling include: when precooling is required, opening the oxygen gas precooling valve and oxygen main pipeline precooling drain valve, closing the oxygen exhaust valve, allowing the BOG in the oxygen tank to enter the oxygen main pipeline for heat exchange precooling, and after heat exchange in the oxygen main pipeline, entering the oxygen recovery / discharge system through the oxygen main pipeline precooling drain valve; after completing the BOG precooling in the oxygen main pipeline, precooling the system to be precooled is performed by opening the oxygen shut-off valve and oxygen pump post-precooling drain valve, closing the oxygen main pipeline precooling drain valve, and precooling the downstream pipeline of the oxygen main pipeline and the system to be precooled; when precooling is required, The steps of opening the methane gas precooling valve, methane shut-off valve, and methane pump post-precooling discharge valve, and closing the methane main pipeline precooling discharge valve and methane exhaust valve; and introducing BOG from the fuel system into the methane main pipeline and the system to be precooled for pipeline precooling include: when precooling is required, opening the methane gas precooling valve and the methane main pipeline precooling discharge valve, closing the methane exhaust valve, allowing the BOG in the methane tank to enter the methane main pipeline for heat exchange precooling, and after heat exchange through the methane main pipeline, entering the methane emission / recovery system through the methane main pipeline precooling discharge valve; after completing the BOG precooling of the methane main pipeline, precooling the system to be precooled is performed by opening the methane shut-off valve and the methane pump post-precooling discharge valve, closing the methane main pipeline precooling discharge valve, and precooling the downstream pipeline of the methane main pipeline and the system to be precooled.

[0021] The beneficial effects of adopting the above-mentioned further technical solution are as follows: When precooling is required, the oxygen gas precooling valve and the oxygen main pipeline precooling vent valve are opened, while the oxygen exhaust valve is closed. This allows the BOG (Boiled Oxygen Gas) in the oxygen tank to enter the oxygen main pipeline for heat exchange and precooling. After heat exchange in the main pipeline, it enters the oxygen recovery / emission system through the oxygen main pipeline precooling vent valve. Temperature changes are monitored during the precooling process, and precooling is complete when the oxygen main pipeline reaches the required temperature. After the BOG precooling in the main pipeline is completed, the engine system is precooled. This is achieved by opening the oxygen shut-off valve and the oxygen pump post-precooling vent valve, and then closing the oxygen main pipeline precooling vent valve, thus precooling the downstream pipeline and the engine system. The BOG flows through the engine connection pipeline and the engine system, and then enters the oxygen recovery / emission system through the oxygen pump post-precooling vent valve.

[0022] Furthermore, before the step of introducing BOG from the oxidant system and / or fuel system into the pre-cooling system for pipeline pre-cooling by controlling the opening and closing of valves, the process includes: opening only the oxygen exhaust valve before pre-cooling the oxidant system, and / or opening only the methane exhaust valve before pre-cooling the fuel system; after the step of introducing BOG from the oxidant system and / or fuel system into the pre-cooling system for pipeline pre-cooling by controlling the opening and closing of valves, the process includes: when a medium is required for pre-cooling, opening the oxygen exhaust valve, and closing the oxygen gas pre-cooling valve, oxygen shut-off valve, and oxygen pump pre-cooling valve. Open the cold discharge valve, and / or open the methane exhaust valve, close the methane gas precooling valve, the methane shut-off valve, and the methane pump post-precooling discharge valve to enter the medium precooling procedure; when it is necessary to judge the precooling effect, open the oxygen exhaust valve, close the oxygen gas precooling valve and the oxygen main pipeline precooling discharge valve to ensure no gas flow in the oxygen main pipeline, and / or open the methane exhaust valve, close the methane gas precooling valve and the methane main pipeline precooling discharge valve to ensure no gas flow in the methane main pipeline; observe the temperature change. When precooling is insufficient, the temperature rise rate is faster, and when precooling is sufficient, the temperature rise is slower.

[0023] The beneficial effects of adopting the above-mentioned further technical solution are as follows: Before engine testing, the medium temperature will rise due to continuous heat exchange in the storage tank, and the medium temperature cannot meet the usage requirements using the compression filling method. By opening the oxygen exhaust valve, the latent heat of vaporization is used to lower the medium temperature to meet the testing requirements, and the BOG (Bottle-Off Gas) is used for pipeline pre-cooling for reuse. Temperature changes are monitored during pre-cooling, and pre-cooling is complete when the engine system reaches the required temperature. After pre-cooling, the current BOG pre-cooling state can be maintained while waiting for medium pre-cooling. When medium pre-cooling is required, the oxygen exhaust valve is opened, the oxygen gas pre-cooling valve is closed, the oxygen shut-off valve is closed, and the oxygen pump post-pre-cooling discharge valve is closed to initiate the medium pre-cooling procedure.

[0024] The advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of the pipeline BOG precooling system provided in an embodiment of the present invention.

[0027] Explanation of reference numerals: 1. Oxidant system; 2. Fuel system; 3. System awaiting pre-cooling; 4. Oxygen tank; 5. Oxygen exhaust valve; 6. Oxygen tank bottom valve; 7. Oxygen gas pre-cooling valve; 8. Oxygen main pipeline pre-cooling vent valve; 9. Oxygen shut-off valve; 10. Oxygen pump post-pre-cooling vent valve; 11. Oxygen recovery / discharge system; 12. Oxygen main pipeline; 13. Oxygen gas pre-cooling pipeline; 14. Oxygen recovery tank; 15. Oxygen venting pipeline; 16. Methane tank; 17. Methane exhaust valve; 18. Methane tank bottom valve; 19. Methane gas pre-cooling valve; 20. Methane main pipeline pre-cooling vent valve; 21. Methane shut-off valve; 22. Methane pump post-pre-cooling vent valve; 23. Methane discharge / recovery system; 24. Methane main pipeline; 25. Methane gas pre-cooling pipeline; 26. Methane recovery tank; 27. Methane venting pipeline. Detailed Implementation

[0028] The principles and features of the present invention are described below with reference to the accompanying drawings. The embodiments described are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0031] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0032] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use, 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, and therefore should not be construed as a limitation of the present invention.

[0033] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0034] like Figure 1 As shown, this embodiment of the invention provides a pipeline BOG precooling system, including: an oxidant system 1, a fuel system 2, and a system to be precooled 3. Both the oxidant system 1 and the fuel system 2 are provided with pipelines and valves, and both the oxidant system 1 and the fuel system 2 are connected to the system to be precooled 3 through pipelines.

[0035] The beneficial effects of adopting the technical solution of this invention are as follows: Utilizing the low-temperature characteristics of BOG (Bottle-Off Gas), BOG is introduced into the test pipeline for preliminary pre-cooling, lowering the pipeline temperature in advance and reducing liquid medium consumption and pipeline stress impact during pre-cooling. The pre-cooling method is BOG preliminary pre-cooling, without the participation of liquid medium. Long-term pre-cooling can be achieved by maintaining the states of different valves, maintaining the low-temperature environment. The BOG pre-cooling method for methane in the fuel system is consistent with that for oxygen in the oxidant system, and the BOG pre-cooling process can be carried out simultaneously on both sides. The emission of gas from the storage tank is a necessary procedure before commissioning, and using BOG pre-cooling can effectively reduce the consumption of liquid medium. This method effectively utilizes the low-temperature characteristics of the emitted gas while reducing the consumption of medium pre-cooling. Simultaneously, using gas pre-cooling can reduce pipeline stress impact, mitigate stress changes caused by thermal expansion and contraction within the pipeline, and prevent leaks in valves and flanges due to temperature changes.

[0036] The arrows in the diagram represent the direction and trajectory of gas flow.

[0037] like Figure 1As shown, the oxidant system 1 further includes: an oxygen tank 4, an oxygen exhaust valve 5, an oxygen tank bottom valve 6, an oxygen gas precooling valve 7, an oxygen main pipeline precooling discharge valve 8, an oxygen shut-off valve 9, an oxygen pump post-precooling discharge valve 10, and an oxygen recovery / discharge system 11. The top of the oxygen tank 4 is connected to the oxygen exhaust valve 5 via a pipeline, the oxygen exhaust valve 5 is connected to the oxygen recovery / discharge system 11 via a pipeline, the bottom of the oxygen tank 4 is connected to the oxygen tank bottom valve 6 via a pipeline, the oxygen tank bottom valve 6 is connected to the oxygen shut-off valve 9 via the oxygen main pipeline 12, and one end of the oxygen gas precooling valve 7 is connected to the oxygen main pipeline 12. The precooling pipeline 13 is connected to the pipeline between the oxygen exhaust valve 5 and the oxygen tank 4. The other end of the oxygen gas precooling valve 7 and one end of the oxygen main pipeline precooling discharge valve 8 are both connected to the oxygen main pipeline 12 through pipelines. The other end of the oxygen main pipeline precooling discharge valve 8 and one end of the oxygen pump post-precooling discharge valve 10 are both connected to the pipeline between the oxygen exhaust valve 5 and the oxygen recovery / discharge system 11. The oxygen shut-off valve 9 is connected to the first end of the system 3 to be precooled through a pipeline. The other end of the oxygen pump post-precooling discharge valve 10 is connected to the second end of the system 3 to be precooled through a pipeline.

[0038] The beneficial effects of adopting the above-mentioned further technical solution are as follows: When precooling is required, the oxygen gas precooling valve and the oxygen main pipeline precooling drain valve are opened, while the oxygen exhaust valve is closed. This allows the BOG (Bottle-Off Gas) in the oxygen tank to enter the oxygen main pipeline for heat exchange and precooling. After heat exchange in the main pipeline, it enters the oxygen recovery / emission system through the oxygen main pipeline precooling drain valve. Temperature changes are monitored during the precooling process, and precooling is complete when the oxygen main pipeline reaches the required temperature. After the BOG precooling in the main pipeline is completed, the engine system is precooled. This is achieved by opening the oxygen shut-off valve and the oxygen pump post-precooling drain valve, and closing the oxygen main pipeline precooling drain valve, thus precooling the downstream pipeline and the engine system. The BOG flows through the engine connection pipeline and the engine system, and enters the oxygen recovery / emission system through the oxygen pump post-precooling drain valve. The precooling method involves initial BOG precooling without the participation of liquid media. By maintaining the states of different valves, long-term precooling can be performed to maintain a low-temperature environment.

[0039] like Figure 1 As shown, further, the first end of the pre-cooling system 3 is connected to the second end of the pre-cooling system 3 via a pipeline; the oxygen recovery / emission system 11 includes: an oxygen recovery tank 14 and an oxygen venting pipeline 15, the oxygen venting pipeline 15 being connected to the oxygen recovery tank 14; the outer sides of the oxygen gas pre-cooling pipeline 13 and the main oxygen pipeline 12 are both covered with a heat insulation layer; the outlet of the oxygen gas pre-cooling valve 7 and the inlet of the oxygen shut-off valve 9 are both equipped with insertion-type temperature sensors, or, a wall temperature sensor is installed on the outer wall of the main oxygen pipeline 12.

[0040] The beneficial effects of adopting the above-mentioned further technical solutions are: The main pipeline and gas precooling pipeline are insulated, reducing heat exchange. An insertion temperature sensor is installed at the outlet of the oxygen gas precooling valve to monitor the inlet gas temperature, and an insertion temperature sensor is installed before the oxygen shut-off valve to monitor temperature changes during precooling. A wall temperature sensor installed on the outer wall of the main pipeline can also be used to determine the precooling effect.

[0041] like Figure 1 As shown, the fuel system 2 further includes: a methane tank 16, a methane exhaust valve 17, a methane tank bottom valve 18, a methane gas precooling valve 19, a methane main pipeline precooling vent valve 20, a methane shut-off valve 21, a methane pump post-pump precooling vent valve 22, and a methane emission / recovery system 23. The top of the methane tank 16 is connected to the methane exhaust valve 17 via a pipeline, the methane exhaust valve 17 is connected to the methane emission / recovery system 23 via a pipeline, the bottom of the methane tank 16 is connected to the methane tank bottom valve 18 via a pipeline, the methane tank bottom valve 18 is connected to the methane shut-off valve 21 via a methane main pipeline 24, and the methane gas precooling valve 19... The methane gas precooling pipeline 25 is connected to the pipeline between the methane exhaust valve 17 and the methane tank 16. The other end of the methane gas precooling valve 19 and one end of the methane main pipeline precooling discharge valve 20 are both connected to the methane main pipeline 24 through pipelines. The other end of the methane main pipeline precooling discharge valve 20 and one end of the methane pump post-precooling discharge valve 22 are both connected to the pipeline between the methane exhaust valve 17 and the methane emission / recovery system 23. The methane shut-off valve 21 is connected to the third end of the system 3 to be precooled through a pipeline. The other end of the methane pump post-precooling discharge valve 22 is connected to the fourth end of the system 3 to be precooled through a pipeline.

[0042] The beneficial effects of adopting the above-mentioned further technical solution are as follows: When precooling is required, the methane gas precooling valve and the methane main pipeline precooling discharge valve are opened, while the methane exhaust valve is closed. This allows the BOG (Bottle-Off Gas) in the methane tank to enter the methane main pipeline for heat exchange and precooling. After heat exchange in the main pipeline, it enters the methane emission / recovery system through the methane main pipeline precooling discharge valve. Temperature changes are monitored during precooling, and precooling is complete when the methane main pipeline reaches the required temperature. After the BOG precooling in the main pipeline is completed, engine system precooling is performed. This is done by opening the methane shut-off valve and the methane pump post-precooling discharge valve, and closing the methane main pipeline precooling discharge valve, thus precooling the downstream pipeline and engine system. The BOG flows through the engine connection pipeline and engine system and enters the methane emission / recovery system through the methane pump post-precooling discharge valve. The precooling method is BOG preliminary precooling, without the participation of liquid media. By maintaining the states of different valves, long-term precooling can be performed to maintain a low-temperature environment.

[0043] like Figure 1As shown, further, the third end of the pre-cooling system 3 is connected to the fourth end of the pre-cooling system 3 via a pipeline; the methane emission / recovery system 23 includes: a methane recovery tank 26 and a methane venting pipeline 27, the methane venting pipeline 27 being connected to the methane recovery tank 26; the outer sides of the methane gas pre-cooling pipeline 25 and the main methane pipeline 24 are both covered with a heat insulation layer; the outlet of the methane gas pre-cooling valve 19 and the inlet of the methane shut-off valve 21 are both equipped with insertion-type temperature sensors, or, a wall temperature sensor is installed on the outer wall of the main methane pipeline 24.

[0044] The beneficial effects of adopting the above-mentioned further technical solutions are: The main pipeline and gas precooling pipeline are insulated, reducing heat exchange. An insertion temperature sensor is installed at the outlet of the methane gas precooling valve to monitor the inlet gas temperature, and an insertion temperature sensor is installed before the methane shut-off valve to monitor temperature changes during precooling. A wall temperature sensor installed on the outer wall of the main pipeline can also be used to determine the precooling effect.

[0045] Furthermore, the pre-cooling system 3 is a liquid oxygen-methane rocket engine system or a refueling pipeline system before the rocket body is refueled at the launch site; the pre-cooling system is equipped with a purge gas seal structure for isolating oxygen and methane.

[0046] The beneficial effects of adopting the above-mentioned further technical solution are: the methane BOG precooling of the fuel system is consistent with that of the oxidizer system, and precooling can be carried out simultaneously on both sides. During the precooling process, necessary measures such as purging gas seals need to be added to the engine end to avoid the danger of oxygen and methane coming into contact. The BOG precooling method can be used for precooling liquid oxygen methane rocket engine systems, as well as for precooling the fueling pipes before the rocket body is fueled at the launch site, thus improving its applicability.

[0047] During storage, the storage tanks (oxygen tank 4 and methane tank 16) still exchange heat with the outside, causing the temperature to rise. Before engine testing and during refueling, the tanks need to be vented to lower the medium temperature to near its boiling point using the latent heat of vaporization. Typically, low-temperature BOG (boil-off gas) is either released at high altitude or burned in a flare, making its low-temperature characteristics unusable.

[0048] By utilizing the low-temperature characteristics of BOG, BOG is introduced into the test pipeline for preliminary pre-cooling of the pipeline, thereby reducing the temperature of the test pipeline in advance and minimizing the consumption of liquid medium and pipeline stress impact during the pre-cooling process.

[0049] like Figure 1As shown, the pipeline BOG precooling system provided in this embodiment of the invention mainly includes: oxidant system 1: oxygen tank 4, oxygen exhaust valve 5, oxygen tank bottom valve 6, oxygen gas precooling valve 7, oxygen main pipeline precooling discharge valve 8, oxygen shut-off valve 9, oxygen pump post-precooling discharge valve 10, and oxygen recovery / venting system (oxygen recovery / discharge system 11).

[0050] Fuel System 2: Methane tank 16, methane exhaust valve 17, methane tank bottom valve (methane tank bottom valve 18), methane gas precooling valve 19, methane main pipeline precooling vent valve 20, methane shut-off valve 21, methane pump post-precooling vent valve 22, methane recovery / venting system (methane emission / recovery system 23).

[0051] The schematic diagram provided in this embodiment mainly illustrates the key valves and process principles. In the actual system, there are other components such as safety valves, gate valves, flow meters, filters, temperature and pressure sensors, bellows, and pre-cooling exhaust systems.

[0052] Before the oxidant system 1 is precooled, the deoxygenation exhaust valve (oxygen exhaust valve 5) is in the open state, and all other valves are in the closed state.

[0053] When precooling is required, open the oxygen gas precooling valve (oxygen gas precooling valve 7) and the oxygen main pipeline precooling discharge valve 8, and close the oxygen exhaust valve 5. This allows the BOG in the storage tank (oxygen tank 4) to enter the main pipeline (oxygen main pipeline 12) for heat exchange and precooling. After heat exchange in the main pipeline, it enters the oxygen recovery / discharge system 11 via the oxygen main pipeline precooling discharge valve 8. Temperature changes are monitored during precooling; precooling is complete when the main pipeline (oxygen main pipeline 12) reaches the required temperature.

[0054] After the main pipeline BOG precooling is completed, the engine system is precooled. This is done by opening the oxygen shut-off valve (oxygen shut-off valve 9) and the oxygen pump post-precooling drain valve 10, and closing the main oxygen pipeline precooling drain valve 8, thus precooling the downstream pipeline and the engine system. BOG flows through the engine connection pipeline and the engine system, and enters the oxygen recovery / emission system 11 through the oxygen pump post-precooling drain valve 10. Temperature changes are monitored during precooling, and precooling is complete when the engine system reaches the required temperature. After precooling is complete, the current BOG precooling state can be maintained while waiting for medium precooling. When medium precooling is required, the medium precooling procedure is initiated by opening the oxygen exhaust valve 5, closing the oxygen gas precooling valve 7, closing the oxygen shut-off valve 9, and closing the oxygen pump post-precooling drain valve 10.

[0055] The precooling method (pipeline BOG precooling method) provided in this embodiment of the invention is a preliminary precooling of BOG without the participation of liquid medium. Long-term precooling can be carried out by maintaining the state of different valves to maintain a low temperature environment.

[0056] The pre-cooling method for methane BOG in the fuel system is the same as that for oxygen BOG in the oxidant system, and the BOG pre-cooling process can be carried out simultaneously on both sides.

[0057] The venting of tank gases (oxygen and methane) is a necessary procedure before commissioning. Using BOG precooling can effectively reduce the consumption of liquid media. This method effectively utilizes the low-temperature characteristics of the vented gases while reducing the amount of media precooling required. Simultaneously, gas precooling can reduce stress impact on pipelines, mitigate stress changes caused by thermal expansion and contraction, and prevent leaks from valves and flanges due to temperature variations.

[0058] In addition, the present invention also provides a pipeline BOG precooling method. Based on the pipeline BOG precooling system described above, the pipeline BOG precooling method includes: controlling the opening and closing of valves to introduce BOG from the oxidant system and / or fuel system into the system to be precooled for pipeline precooling.

[0059] The beneficial effects of adopting the technical solution of this invention are as follows: Utilizing the low-temperature characteristics of BOG (Bottle-Off Gas), BOG is introduced into the test pipeline for preliminary pre-cooling, lowering the pipeline temperature in advance and reducing liquid medium consumption and pipeline stress impact during pre-cooling. The pre-cooling method is BOG preliminary pre-cooling, without the participation of liquid medium. Long-term pre-cooling can be achieved by maintaining the states of different valves, maintaining the low-temperature environment. The BOG pre-cooling method for methane in the fuel system is consistent with that for oxygen in the oxidant system, and the BOG pre-cooling process can be carried out simultaneously on both sides. The emission of gas from the storage tank is a necessary procedure before commissioning, and using BOG pre-cooling can effectively reduce the consumption of liquid medium. This method effectively utilizes the low-temperature characteristics of the emitted gas while reducing the consumption of medium pre-cooling. Simultaneously, using gas pre-cooling can reduce pipeline stress impact, mitigate stress changes caused by thermal expansion and contraction within the pipeline, and prevent leaks in valves and flanges due to temperature changes.

[0060] Furthermore, the step of introducing BOG from the oxidant system into the pre-cooling system for pipeline pre-cooling by controlling the opening and closing of valves includes: when pre-cooling is required, opening the oxygen gas pre-cooling valve, the oxygen shut-off valve, and the pre-cooling discharge valve after the oxygen pump, and closing the oxygen main pipeline pre-cooling discharge valve and the oxygen exhaust valve; introducing BOG from the oxidant system into the oxygen main pipeline and the pre-cooling system for pipeline pre-cooling; the step of introducing BOG from the fuel system into the pre-cooling system for pipeline pre-cooling by controlling the opening and closing of valves includes: when pre-cooling is required, opening the methane gas pre-cooling valve, the methane shut-off valve, and the methane pump pre-cooling discharge valve, and closing the methane main pipeline pre-cooling discharge valve and the methane exhaust valve; introducing BOG from the fuel system into the methane main pipeline and the pre-cooling system for pipeline pre-cooling.

[0061] The beneficial effects of adopting the above-mentioned further technical solution are: if there are no specific requirements for the pre-cooling temperature, the oxygen shut-off valve can be opened at the beginning of pre-cooling to pre-cool the main pipeline and engine system simultaneously. This improves pre-cooling efficiency and simplifies the operation process.

[0062] Further, when precooling is required, the oxygen gas precooling valve, oxygen shut-off valve, and oxygen pump post-precooling drain valve are opened, while the oxygen main pipeline precooling drain valve and oxygen exhaust valve are closed. The steps for introducing BOG from the oxidant system into the oxygen main pipeline and the system to be precooled for pipeline precooling include: when precooling is required, opening the oxygen gas precooling valve and oxygen main pipeline precooling drain valve, closing the oxygen exhaust valve, allowing the BOG in the oxygen tank to enter the oxygen main pipeline for heat exchange precooling, and after heat exchange in the oxygen main pipeline, entering the oxygen recovery / discharge system through the oxygen main pipeline precooling drain valve; after completing the BOG precooling in the oxygen main pipeline, precooling the system to be precooled is performed by opening the oxygen shut-off valve and oxygen pump post-precooling drain valve, closing the oxygen main pipeline precooling drain valve, and precooling the downstream pipeline of the oxygen main pipeline and the system to be precooled; when precooling is required, The steps of opening the methane gas precooling valve, methane shut-off valve, and methane pump post-precooling discharge valve, and closing the methane main pipeline precooling discharge valve and methane exhaust valve; and introducing BOG from the fuel system into the methane main pipeline and the system to be precooled for pipeline precooling include: when precooling is required, opening the methane gas precooling valve and the methane main pipeline precooling discharge valve, closing the methane exhaust valve, allowing the BOG in the methane tank to enter the methane main pipeline for heat exchange precooling, and after heat exchange through the methane main pipeline, entering the methane emission / recovery system through the methane main pipeline precooling discharge valve; after completing the BOG precooling of the methane main pipeline, precooling the system to be precooled is performed by opening the methane shut-off valve and the methane pump post-precooling discharge valve, closing the methane main pipeline precooling discharge valve, and precooling the downstream pipeline of the methane main pipeline and the system to be precooled.

[0063] The beneficial effects of adopting the above-mentioned further technical solution are as follows: When precooling is required, the oxygen gas precooling valve and the oxygen main pipeline precooling vent valve are opened, while the oxygen exhaust valve is closed. This allows the BOG (Boiled Oxygen Gas) in the oxygen tank to enter the oxygen main pipeline for heat exchange and precooling. After heat exchange in the main pipeline, it enters the oxygen recovery / emission system through the oxygen main pipeline precooling vent valve. Temperature changes are monitored during the precooling process, and precooling is complete when the oxygen main pipeline reaches the required temperature. After the BOG precooling in the main pipeline is completed, the engine system is precooled. This is achieved by opening the oxygen shut-off valve and the oxygen pump post-precooling vent valve, and then closing the oxygen main pipeline precooling vent valve, thus precooling the downstream pipeline and the engine system. The BOG flows through the engine connection pipeline and the engine system, and then enters the oxygen recovery / emission system through the oxygen pump post-precooling vent valve.

[0064] Furthermore, before the step of introducing BOG from the oxidant system and / or fuel system into the pre-cooling system for pipeline pre-cooling by controlling the opening and closing of valves, the process includes: opening only the oxygen exhaust valve before pre-cooling the oxidant system, and / or opening only the methane exhaust valve before pre-cooling the fuel system; after the step of introducing BOG from the oxidant system and / or fuel system into the pre-cooling system for pipeline pre-cooling by controlling the opening and closing of valves, the process includes: when a medium is required for pre-cooling, opening the oxygen exhaust valve, and closing the oxygen gas pre-cooling valve, oxygen shut-off valve, and oxygen pump pre-cooling valve. Open the cold discharge valve, and / or open the methane exhaust valve, close the methane gas precooling valve, the methane shut-off valve, and the methane pump post-precooling discharge valve to enter the medium precooling procedure; when it is necessary to judge the precooling effect, open the oxygen exhaust valve, close the oxygen gas precooling valve and the oxygen main pipeline precooling discharge valve to ensure no gas flow in the oxygen main pipeline, and / or open the methane exhaust valve, close the methane gas precooling valve and the methane main pipeline precooling discharge valve to ensure no gas flow in the methane main pipeline; observe the temperature change. When precooling is insufficient, the temperature rise rate is faster, and when precooling is sufficient, the temperature rise is slower.

[0065] The beneficial effects of adopting the above-mentioned further technical solution are as follows: Before engine testing, the medium temperature will rise due to continuous heat exchange in the storage tank, and the medium temperature cannot meet the usage requirements using the compression filling method. By opening the oxygen exhaust valve, the latent heat of vaporization is used to lower the medium temperature to meet the testing requirements, and the BOG (Bottle-Off Gas) is used for pipeline pre-cooling for reuse. Temperature changes are monitored during pre-cooling, and pre-cooling is complete when the engine system reaches the required temperature. After pre-cooling, the current BOG pre-cooling state can be maintained while waiting for medium pre-cooling. When medium pre-cooling is required, the oxygen exhaust valve is opened, the oxygen gas pre-cooling valve is closed, the oxygen shut-off valve is closed, and the oxygen pump post-pre-cooling discharge valve is closed to initiate the medium pre-cooling procedure.

[0066] The schematic diagram provided in this embodiment mainly illustrates the key valves for achieving BOG precooling. In the actual implementation, there are also pipeline safety valves, temperature and pressure sensors, bellows, liquid medium precooling and exhaust systems, etc.

[0067] Before the engine test run, the storage tanks (oxygen tank 4 and methane tank 16) will continue to generate heat, causing the medium temperature to rise. Furthermore, the medium temperature cannot meet the usage requirements using the compression filling method. The storage tank vent valve (oxygen vent valve 5) is opened, and the latent heat of vaporization is used to lower the medium temperature to meet the test run requirements. The medium is then pre-cooled via BOG (Booster Gas) for reuse.

[0068] The BOG precooling of the oxidant system is as follows: Before precooling begins, the deoxygenation and exhaust valve (oxygen exhaust valve 5) is in the open position, and all other valves are in the closed position.

[0069] When precooling is required, the oxygen gas precooling valve (oxygen gas precooling valve 7) and the oxygen main line precooling discharge valve (oxygen main line precooling discharge valve 8) are opened, and the oxygen exhaust valve (oxygen exhaust valve 5) is closed, allowing the low-temperature BOG in the storage tank to enter the main line for heat exchange precooling. The main line (oxygen main line 12) and the gas precooling pipeline (oxygen gas precooling pipeline 13) need to be insulated to reduce heat exchange.

[0070] After passing through the heat exchanger in the main pipeline, the oxygen enters the oxygen recovery / discharge system 11 via the oxygen main pipeline pre-cooling discharge valve 8.

[0071] An insertion-type temperature sensor is installed at the outlet of the oxygen precooling valve 7 to monitor the inlet gas temperature. An insertion-type temperature sensor is also installed before the oxygen shut-off valve 9 to monitor temperature changes during precooling. To determine the precooling effect of the main pipeline, the oxygen discharge valve (oxygen exhaust valve 5) is opened, and the oxygen precooling valve 7 and the oxygen main pipeline precooling discharge valve 8 are closed, eliminating gas flow in the main pipeline. Temperature changes are then observed; insufficient precooling results in a rapid temperature rise, while sufficient precooling leads to a slow temperature rise. A wall temperature sensor installed on the outer wall of the main pipeline (oxygen main pipeline 12) can also be used to determine the precooling effect.

[0072] The precooling of the main pipeline is complete when the internal temperature of the main pipeline stabilizes and is close to the temperature of the precooled gas.

[0073] After the main pipeline gas precooling is completed, the engine system is precooled. This is done by opening the oxygen shut-off valve (oxygen shut-off valve 5) and the oxygen pump post-precooling vent valve 10, and closing the main oxygen pipeline precooling vent valve 8, thus precooling the downstream pipeline and engine system. The low-temperature gas (BOG) flows through the downstream pipeline and engine system and enters the oxygen recovery / emission system 11 through the oxygen pump post-precooling vent valve 10.

[0074] In practice, the BOG precooling time can be flexibly adjusted according to the test preparation time and ignition time requirements. The precooling temperature can also be adjusted according to the time requirements. For rapid precooling, the main pipeline temperature can be adjusted to 200K as the target temperature. If there are no specific requirements for the precooling temperature, the oxygen shut-off valve 9 can be opened at the beginning of precooling to precool the main pipeline engine system simultaneously.

[0075] When precooling with a medium is required, BOG precooling is ended by opening oxygen exhaust valve 5, closing oxygen gas precooling valve 7, closing oxygen shut-off valve 9, and opening oxygen pump post-precooling discharge valve 10.

[0076] The precooling of the methane BOG in the fuel system is consistent with that of the oxygen system (oxidant system), and precooling can be carried out simultaneously on both sides. During the precooling process, necessary measures such as purging the gas seal at the engine end are required to prevent oxygen and methane from coming into contact and causing danger.

[0077] This precooling method (pipeline BOG precooling method) is a preliminary precooling of the pipeline and cannot achieve the effect of media precooling. However, it can effectively utilize the BOG generated by the storage tank to achieve preliminary precooling of the pipeline system. No liquid media are involved in this process; the internal pressure of the pipeline is slightly greater than one atmosphere. There is no violent vaporization or large-scale media consumption. By maintaining the status of each valve, long-term precooling can be carried out to maintain a low-temperature environment, eliminating the need for frequent monitoring of the pipeline pressure.

[0078] This BOG precooling method (pipeline BOG precooling method) can also be used for precooling the fueling pipeline before fueling the rocket body at the launch site.

[0079] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pipeline precooling system, characterized in that, include: The system comprises an oxidant system, a fuel system, and a pre-cooling system. Both the oxidant and fuel systems are equipped with pipelines and valves, and are connected to the pre-cooling system via pipelines. The oxidant system includes: an oxygen tank, an oxygen exhaust valve, an oxygen tank bottom valve, an oxygen gas pre-cooling valve, a main oxygen pipeline pre-cooling discharge valve, an oxygen shut-off valve, an oxygen pump post-pre-cooling discharge valve, and an oxygen recovery / discharge system. The top of the oxygen tank is connected to the oxygen exhaust valve via a pipeline, the oxygen exhaust valve is connected to the oxygen recovery / discharge system via a pipeline, and the bottom of the oxygen tank is connected to the oxygen recovery / discharge system via a pipeline. The oxygen tank bottom valve is connected to the oxygen shut-off valve via the main oxygen pipeline. One end of the oxygen gas precooling valve is connected to the pipeline between the oxygen exhaust valve and the oxygen tank via an oxygen gas precooling pipeline. The other end of the oxygen gas precooling valve and one end of the main oxygen pipeline precooling vent valve are both connected to the main oxygen pipeline via pipelines. The other end of the main oxygen pipeline precooling vent valve and one end of the oxygen pump post-precooling vent valve are both connected to the pipeline between the oxygen exhaust valve and the oxygen recovery / discharge system. The oxygen shut-off valve is connected to the first end of the system to be precooled via a pipeline. The oxygen pump post-precooling vent valve... The other end of the outlet valve is connected to the second end of the pre-cooling system via a pipeline; the fuel system includes: a methane tank, a methane exhaust valve, a methane tank bottom valve, a methane gas pre-cooling valve, a methane main pipeline pre-cooling vent valve, a methane shut-off valve, a methane pump post-pump pre-cooling vent valve, and a methane emission / recovery system. The top of the methane tank is connected to the methane exhaust valve via a pipeline, the methane exhaust valve is connected to the methane emission / recovery system via a pipeline, the bottom of the methane tank is connected to the methane tank bottom valve via a pipeline, the methane tank bottom valve is connected to the methane shut-off valve via the methane main pipeline, and the methane gas pre-cooling... One end of the valve is connected to the pipeline between the methane exhaust valve and the methane tank via a methane gas precooling pipeline. The other end of the methane gas precooling valve and one end of the methane main pipeline precooling vent valve are both connected to the methane main pipeline via pipelines. The other end of the methane main pipeline precooling vent valve and one end of the methane pump post-precooling vent valve are both connected to the pipeline between the methane exhaust valve and the methane emission / recovery system. The methane shut-off valve is connected to the third end of the system to be precooled via a pipeline. The other end of the methane pump post-precooling vent valve is connected to the fourth end of the system to be precooled via a pipeline.

2. The pipeline precooling system according to claim 1, characterized in that, The first end of the pre-cooling system is connected to the second end of the pre-cooling system via a pipeline; the oxygen recovery / discharge system includes an oxygen recovery tank and an oxygen venting pipeline, the oxygen venting pipeline being connected to the oxygen recovery tank; the outer sides of the oxygen gas pre-cooling pipeline and the main oxygen pipeline are both covered with a heat insulation layer; the outlet of the oxygen gas pre-cooling valve and the inlet of the oxygen shut-off valve are both equipped with insertion-type temperature sensors, or, a wall temperature sensor is installed on the outer wall of the main oxygen pipeline.

3. The pipeline precooling system according to claim 1, characterized in that, The third end of the system to be precooled is connected to the fourth end of the system to be precooled via a pipeline; the methane emission / recovery system includes: a methane recovery tank and a methane venting pipeline, the methane venting pipeline being connected to the methane recovery tank; the outer sides of the methane gas precooling pipeline and the main methane pipeline are both covered with a heat insulation layer; an insertion-type temperature sensor is installed at the outlet of the methane gas precooling valve and the inlet of the methane shut-off valve, or a wall temperature sensor is installed on the outer wall of the main methane pipeline.

4. A pipeline precooling system according to claim 1, characterized in that, The system to be precooled is a liquid oxygen-methane rocket engine system; the system to be precooled is equipped with a purge gas seal structure for isolating oxygen and methane.

5. A pipeline precooling method, characterized in that, Based on any one of claims 1 to 4, the pipeline precooling method includes: By controlling the opening and closing of valves, BOG from the oxidant system and / or fuel system is introduced into the pre-cooling system for pipeline pre-cooling.

6. A pipeline precooling method according to claim 5, characterized in that, The steps for precooling the pipeline by introducing BOG from the oxidant system into the precooling system by controlling the opening and closing of the valves include: When precooling is required, open the oxygen gas precooling valve, oxygen shut-off valve, and oxygen pump precooling discharge valve, and close the oxygen main pipeline precooling discharge valve and oxygen exhaust valve; introduce BOG from the oxidant system into the oxygen main pipeline and the system to be precooled for pipeline precooling. The steps for precooling the pipeline by introducing BOG from the fuel system into the precooling system by controlling the opening and closing of valves include: When precooling is required, open the methane gas precooling valve, methane shut-off valve, and methane pump post-precooling discharge valve, and close the methane main pipeline precooling discharge valve and methane exhaust valve; introduce BOG from the fuel system into the methane main pipeline and the system to be precooled for pipeline precooling.

7. A pipeline precooling method according to claim 6, characterized in that, When precooling is required, the steps of opening the oxygen gas precooling valve, oxygen shut-off valve, and oxygen pump precooling discharge valve, and closing the oxygen main pipeline precooling discharge valve and oxygen exhaust valve, and introducing BOG from the oxidant system into the oxygen main pipeline and the system to be precooled for pipeline precooling include: When precooling is required, open the oxygen gas precooling valve and the oxygen main pipeline precooling discharge valve, close the oxygen exhaust valve, so that the BOG in the oxygen tank enters the oxygen main pipeline for heat exchange and precooling, and after heat exchange through the oxygen main pipeline, it enters the oxygen recovery / discharge system through the oxygen main pipeline precooling discharge valve. After completing the BOG precooling of the main oxygen pipeline, precool the system to be precooled. Open the oxygen shut-off valve and the oxygen pump precooling drain valve, close the main oxygen pipeline precooling drain valve, and precool the downstream pipeline of the main oxygen pipeline and the system to be precooled. When precooling is required, the steps include: opening the methane gas precooling valve, the methane shut-off valve, and the methane pump post-precooling discharge valve, and closing the methane main pipeline precooling discharge valve and the methane exhaust valve. This involves introducing BOG from the fuel system into the methane main pipeline and the system to be precooled for pipeline precooling. When precooling is required, open the methane gas precooling valve and the methane main pipeline precooling discharge valve, close the methane exhaust valve, and let the BOG in the methane tank enter the methane main pipeline for heat exchange and precooling. After heat exchange through the methane main pipeline, it enters the methane emission / recovery system through the methane main pipeline precooling discharge valve. After the BOG precooling of the main methane pipeline is completed, the system to be precooled is precooled. The methane shut-off valve and the precooling discharge valve after the methane pump are opened, and the precooling discharge valve of the main methane pipeline is closed. The downstream pipeline of the main methane pipeline and the system to be precooled are then precooled.

8. A pipeline precooling method according to claim 5, characterized in that, Before the step of introducing BOG from the oxidant system and / or fuel system into the precooling system by controlling the opening and closing of valves for pipeline precooling, the following steps are included: before precooling the oxidant system, only the oxygen exhaust valve is opened, and / or, before precooling the fuel system, only the methane exhaust valve is opened. After controlling the opening and closing of valves to introduce BOG from the oxidizer system and / or fuel system into the pre-cooling system for pipeline pre-cooling, the process includes: When precooling of the medium is required, open the oxygen exhaust valve, close the oxygen gas precooling valve, the oxygen shut-off valve, and the precooling relief valve after the oxygen pump, and / or open the methane exhaust valve, close the methane gas precooling valve, the methane shut-off valve, and the precooling relief valve after the methane pump, and enter the medium precooling procedure.

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