Closed conduit conventional liquid propellant handling system and method

Abstract

The present application relates to a kind of conventional liquid propellant processing system and method, specifically a kind of closed pipeline conventional liquid propellant processing system and method, to solve the technical problem that liquid rocket propellant in the closed pipeline of complex, pipe slender, existing blind cavity is difficult to be cleaned in prior art.The present application includes pressurized blowing system, including pressurized gas source, one end of pressurized pipeline connected with pressurized gas source and first displacement isolation valve connected on pressurized pipeline;Vacuum pumping system, including buffer tank, vacuum pump and vacuum gauge, the inlet of vacuum pump is connected with buffer tank by vacuum pump isolation valve, vacuum gauge is connected with buffer tank by vacuum gauge isolation valve;Buffer tank is also provided with vacuumizing isolation valve, second displacement isolation valve and buffer tank blowdown valve;Neutralization processing device, inlet is used to be connected with discharge isolation valve, or used to be simultaneously connected with the outlet of vacuum pump and buffer tank blowdown valve, outlet is used to be connected with plant exhaust port using pipeline or led to outdoor.

Description

TECHNICAL FIELD

[0001] The present application relates to a conventional liquid propellant processing system and method, in particular to a closed pipeline conventional liquid propellant processing system and method. BACKGROUND

[0002] The conventional liquid rocket propellant (hereinafter referred to as liquid propellant) generally has the characteristics of being toxic, harmful, highly corrosive, flammable and explosive, making the processing of its residual liquid more difficult than other ordinary liquids.

[0003] For a liquid rocket engine, its working principle is generally to store liquid propellant in a propellant tank, to pressurize the propellant in the tank by gas or combustion gas, to squeeze the propellant in the tank into a delivery pipeline, and to deliver it to the liquid engine inlet valve through the pipeline, and to control the engine start and shutdown by controlling the valve opening and closing. After the engine stops working, the general processing method for the liquid propellant in the pipeline is to empty the liquid propellant in the pipeline through the discharge process port, and then to blow off the residual propellant in the pipeline through the process port by nitrogen. For the liquid propellant pipeline used for testing, after blowing off, the pipeline needs to be disassembled, neutralized and cleaned with cleaning liquid, dehydrated with industrial alcohol, and then dried with nitrogen for subsequent use or storage.

[0004] Figure 1 The present application relates to a conventional liquid propellant processing system and method, in particular to a closed pipeline conventional liquid propellant processing system and method.

[0005] However, for non-removable pipelines, especially for reusable liquid power systems, after the engine stops working, on the one hand, in order to check and test before the next reuse, the propellant in the pipeline needs to be emptied; on the other hand, liquid propellant will react with air to produce excess material or cause corrosion to the engine, so it is necessary to ensure that the pipeline does not contact air.

[0006] However, the propellant delivery pipelines used in liquid engines typically have a complex three-dimensional spatial layout, containing throttling elements and numerous blind cavities. This is especially true for long, narrow, enclosed pipelines (e.g., 1mm to 10mm in diameter), where the small diameter, length, complex structure, and blind cavities make it even more difficult to clean the propellant using existing methods. Particularly for reusable liquid propulsion systems, to ensure safety during inspection and testing, it is essential to completely remove any residual propellant liquid and even vapor from the pipelines to guarantee product and personnel safety. Summary of the Invention

[0007] The purpose of this invention is to solve the technical problem that existing technologies are unable to clean liquid rocket propellants in complex, long, narrow, and blind-cavity closed pipes, and to provide a conventional liquid propellant treatment system and method for closed pipes.

[0008] The inventive concept of this invention is as follows: For liquid propellant within a closed pipeline, firstly, nitrogen positive pressure is used to purge and expel most of the residual liquid propellant from the pipeline. The purging process employs an intermittent purging method: after purging for several minutes, the pipeline is pressurized and allowed to stand for several minutes, allowing the nitrogen and propellant vapors to mix. Then, purging is repeated for several minutes to allow the nitrogen flow to carry away the residual vapors. This cycle is repeated until no liquid or significant propellant vapor remains, at which point further processing is performed. Because blind cavities exist within the pipeline, residual propellant cannot be completely emptied using only nitrogen purging. Liquid propellants all possess a certain saturated vapor pressure. Under vacuum conditions, liquid propellants will continuously evaporate until the vapor pressure reaches the saturated vapor pressure at their ambient temperature. This invention utilizes the saturated vapor pressure of liquid propellants and employs a vacuum suction method to evacuate and empty the remaining liquid propellant, thereby achieving the treatment of propellants in closed pipelines and making them reusable. By using a vacuum buffer tank and employing a cyclical treatment method of vacuum suction → nitrogen purging and replacement → vacuum suction, the efficiency of treating liquid propellants in pipelines using the evacuation suction method is greatly improved.

[0009] To achieve the above objectives and complete the above inventive concept, the technical solution adopted by this invention is as follows:

[0010] A closed-pipe conventional liquid propellant handling system, characterized in that it includes:

[0011] The pressurized purging system includes a pressurized air source, a pressurized pipeline connected to the pressurized air source at one end, and a first displacement isolation valve connected to the pressurized pipeline;

[0012] The vacuum suction system includes a buffer tank, a vacuum pump, and a vacuum gauge. The inlet of the vacuum pump is connected to the buffer tank through a vacuum pump isolation valve, and the vacuum gauge is connected to the buffer tank through a vacuum gauge isolation valve. The buffer tank is also equipped with a vacuum isolation valve, a second displacement isolation valve, and a buffer tank drain valve. The vacuum isolation valve is used to connect to the purge isolation valve at the purge process port of the treated pipeline or the discharge isolation valve at the discharge process port of the treated pipeline through a pipeline. The second displacement isolation valve is used to connect to the other end of the pressurization pipeline. The buffer tank drain valve is used to discharge the propellant in the buffer tank and to displace the buffer tank.

[0013] The neutralization treatment device has an inlet valve at the inlet and an outlet valve at the outlet. The inlet is used to connect with the discharge isolation valve, or to connect with the outlet of the vacuum pump and the drain valve of the buffer tank. The outlet is used to connect with the plant exhaust port through a pipeline or to lead to the outdoors.

[0014] Furthermore, the pressurization and purging system also includes a pressure detector and a pressure reducer; the pressure reducer and the pressure detector are connected sequentially on the pressurization pipeline along the gas supply direction; the pressure detector is a pressure gauge or a pressure sensor.

[0015] Furthermore, the pressurization and purging system also includes a heating device, which is installed on the pressurization pipeline and is used to heat the gas in the pressurization pipeline.

[0016] Furthermore, a filter is connected between the vacuum pump isolation valve and the vacuum pump;

[0017] The vacuum pump is an oil-free, dry, explosion-proof, corrosion-resistant screw vacuum pump.

[0018] The explosion-proof rating of the vacuum pump is no less than ExdII BT4.

[0019] Furthermore, the volume of the buffer tank is 10 to 30 times the volume of the pipeline being treated, or the volume of the buffer tank is 10L to 30L, for pipelines with a volume of less than 10L being treated.

[0020] Alternatively, the volume of the buffer tank is 1 to 10 times the volume of the pipeline being treated, or the volume of the buffer tank is 10L to 100L, for pipelines with a volume greater than 10L being treated.

[0021] Furthermore, the vacuum isolation valve is installed on the side wall of the buffer tank body, the vacuum gauge isolation valve, the second displacement isolation valve and the vacuum pump isolation valve are all installed on the top of the buffer tank body, and the buffer tank drain valve is installed on the bottom of the buffer tank body; the buffer tank and the second displacement isolation valve are connected through a diffuser tube; the upper end of the diffuser tube is connected to the second displacement isolation valve, the lower end of the diffuser tube is sealed and extends into the buffer tank body, and multiple through holes are provided on the outer periphery of the diffuser tube near the lower end, the through holes connecting the diffuser tube and the buffer tank.

[0022] Meanwhile, the present invention also provides a method for treating conventional liquid propellants in a closed pipeline, which employs the aforementioned conventional liquid propellant treatment system in a closed pipeline, characterized by the following steps:

[0023] S1, Pipeline connection

[0024] S1.1 Connect the other end of the pressurization pipeline of the pressurization and purging system to the purging isolation valve at the purging process port of the pipeline to be treated, and adjust the air supply pressure to the preset target value;

[0025] S1.2 Connect the inlet of the neutralization treatment device to the discharge isolation valve at the discharge process port of the treated pipeline using a pipeline, connect the outlet of the neutralization treatment device to the plant exhaust port using a pipeline or lead it outdoors, and open the exhaust valve of the neutralization treatment device to keep the neutralization treatment device ventilated.

[0026] S1.1 and S1.2 have no order of priority and can be performed simultaneously or sequentially.

[0027] S2, nitrogen replacement

[0028] Confirm that the purge isolation valve is closed;

[0029] Perform the following operation at least once: Open the first displacement isolation valve to allow nitrogen to be discharged from the first displacement isolation valve through the pressurization pipeline to displace the air in the pressurization pipeline, and close the first displacement isolation valve after a first preset time.

[0030] S3, Pipeline purging

[0031] S3.1 Open the purge isolation valve to allow purge nitrogen to enter the pipeline being treated. Then, sequentially open the discharge isolation valve and the neutralization treatment device inlet valve to allow the propellant liquid and vapor in the pipeline being treated to enter the neutralization treatment device and be discharged after neutralization reaction.

[0032] S3.2 The discharge isolation valve is repeatedly closed and opened at preset time intervals to intermittently purge the treated pipeline for a preset time, thereby completing the purging of the treated pipeline;

[0033] S3.3. Close the discharge isolation valve, purge isolation valve, neutralization treatment device inlet valve and neutralization treatment device exhaust valve in sequence, and remove the pressurization purge system and neutralization treatment device;

[0034] S4, Vacuum suction system connection

[0035] Connect the vacuum isolation valve and the purge isolation valve of the buffer tank through pipelines. Connect the buffer tank drain valve and the outlet of the vacuum pump to the inlet valve of the neutralization treatment unit through pipelines. Connect the second displacement isolation valve of the buffer tank to the other end of the pressurization pipeline of the pressurization purge system. Make the vacuum gauge isolation valve, the inlet valve of the neutralization treatment unit and the exhaust valve of the neutralization treatment unit open. Confirm that the purge isolation valve, the discharge isolation valve, the vacuum isolation valve, the second displacement isolation valve, the vacuum pump isolation valve and the buffer tank drain valve are closed. Start the vacuum pump.

[0036] S5, Vacuuming process

[0037] S5.1 Open the vacuum pump isolation valve and continue for the second preset time. Observe whether the vacuum gauge reading is less than the first preset pressure value. If yes, close the vacuum pump isolation valve and proceed to step S5.2. If no, proceed to step S5.3.

[0038] S5.2 Open the vacuum isolation valve, then open the purge isolation valve to draw the residual propellant vapor in the treated pipeline into the buffer tank. At this time, the vacuum gauge reading increases. After the third preset time, close the purge isolation valve, the vacuum isolation valve, and the vacuum gauge isolation valve. Open the second replacement isolation valve and the buffer tank drain valve. Adjust the output pressure of the pressurization pipeline and purge and replace the buffer tank with nitrogen at the second preset pressure value. After the fourth preset time, close the second replacement isolation valve and the buffer tank drain valve, open the vacuum gauge isolation valve, and execute step S5.5.

[0039] S5.3 Observe whether the vacuum gauge reading is less than the third preset pressure value. If yes, close the vacuum pump isolation valve and execute step S5.2. If no, execute step S5.4. The third preset pressure value is greater than the first preset pressure value. The third preset pressure value is used to determine whether the vacuum pump can continue to work effectively due to the strong adsorption of the liquid propellant.

[0040] S5.4 Confirm that the vacuum isolation valve is closed, close the vacuum gauge isolation valve, open the second purging isolation valve, adjust the output pressure of the booster line, and purge and purge the buffer tank and vacuum pump with nitrogen at the fourth preset pressure value. After a fifth preset time, close the second purging isolation valve, open the vacuum gauge isolation valve, and after a second preset time, observe whether the vacuum gauge reading is less than the first preset pressure value. If yes, close the vacuum pump isolation valve and execute step S5.2. If no, repeat step S5.4 until the vacuum gauge reading is less than the first preset pressure value.

[0041] S5.5 After repeating step S5.1 at least once, proceed to step S6;

[0042] S6 switches to the vacuuming position and continues vacuuming.

[0043] S6.1 Confirm that the purge isolation valve is closed, remove the vacuum system from the purge isolation valve, and connect the vacuum isolation valve of the buffer tank to the discharge isolation valve through the pipeline;

[0044] S6.2 Using the same method as step S5, the pipe being processed is evacuated to allow the residual propellant in the blind cavity near the liquid engine inlet pipe to be extracted more quickly.

[0045] S7, Pressure Holding

[0046] Open the vacuum pump isolation valve, evacuate until the vacuum gauge reading is lower than the first preset pressure value, then close the vacuum pump isolation valve, open the vacuum pump isolation valve and the discharge isolation valve, and let it stand for a sixth preset time. Observe whether the vacuum degree does not exceed the fifth preset pressure value through the vacuum gauge. If yes, close the discharge isolation valve, the neutralization device inlet valve, the neutralization device exhaust valve, the vacuum pump isolation valve, the vacuum gauge isolation valve, and the vacuum pump, remove the vacuum suction system, and then proceed to step S8; if no, close the vacuum pump isolation valve and the discharge isolation valve and return to step S6.2, or close the discharge isolation valve, the neutralization device inlet valve, the neutralization device exhaust valve, the vacuum pump isolation valve, the vacuum gauge isolation valve, and the vacuum pump, remove the vacuum suction system, and then return to step S4.

[0047] S8, Positive Pressure Seal

[0048] Connect the other end of the pressurization pipeline of the pressurization and purging system to the purging isolation valve, perform nitrogen purging using the same method as in step S2, then open the purging isolation valve to seal the pipeline being treated, so that the pressure in the pipeline being treated reaches the sixth preset pressure value, finally close the purging isolation valve, dismantle the pressurization and purging system, and complete the conventional liquid propellant treatment of the closed pipeline.

[0049] Further, in step S1, the gas supply pressure is adjusted to a preset target value by adjusting the pressure reducer, the preset target value being 0.3 to 0.5 MPa;

[0050] In step S2, it must be completed at least three times; the first preset time shall not be less than 1 minute.

[0051] Step S3.2 specifically involves repeatedly opening and closing the discharge isolation valve at time intervals of 3-5 minutes and 3-5 minutes to intermittently purge the treated pipeline for 15-30 minutes, thereby completing the purging of the treated pipeline.

[0052] In step S7, the sixth preset time is 3 minutes, and the fifth preset pressure value is 100 Pa;

[0053] In step S8, the sixth preset pressure value is 0.2 to 0.5 MPa.

[0054] Furthermore, in step S5.1, the first preset pressure value is 10 Pa, and the second preset time is 1 to 5 min;

[0055] In step S5.2, the third preset time is 1 to 3 minutes, the second preset pressure value is 0.3 to 0.5 MPa, and the fourth preset time is 1 to 3 minutes;

[0056] In step S5.3, the third preset pressure value is 50 Pa;

[0057] In step S5.4, the fourth preset pressure value is 0.05 to 0.1 MPa, and the fifth preset time is 1 to 3 minutes;

[0058] Step S5.5 specifically involves repeating step S5.1 twice, and then executing step S6.

[0059] Compared with the prior art, the present invention has the following beneficial technical effects:

[0060] 1. The conventional liquid propellant treatment system and method proposed in this invention can clean the liquid propellant in the pipeline without ensuring that the pipeline does not come into contact with air;

[0061] 2. The conventional liquid propellant treatment system and method proposed in this invention effectively improves the treatment efficiency of residual liquid propellant in pipelines by using a buffer tank;

[0062] 3. The conventional liquid propellant treatment system and method proposed in this invention can be applied to the safe treatment of liquid propellants in pipelines of various specifications;

[0063] 4. The conventional liquid propellant treatment system and method proposed in this invention can be applied to the clean treatment of pipelines in reusable liquid power systems;

[0064] 5. The conventional liquid propellant handling system proposed in this invention achieves safe handling of corrosive conventional liquid propellants by employing an explosion-proof and corrosion-resistant screw vacuum pump. Attached Figure Description

[0065] Figure 1 This is a schematic diagram of a typical propellant piping layout for an existing conventional liquid propulsion system (purge isolation valve and discharge isolation valve are not shown).

[0066] Figure 2 This is a schematic diagram illustrating the operating principle of the pressurization and purging system in an embodiment of a closed-pipe conventional liquid propellant treatment system of the present invention.

[0067] Figure 3 This is a schematic diagram of the connection between the vacuum suction system and the purge isolation valve in an embodiment of a closed-pipe conventional liquid propellant handling system of the present invention;

[0068] Figure 4 This is a schematic diagram of the connection between the vacuum suction system and the discharge isolation valve in an embodiment of a closed-pipe conventional liquid propellant handling system of the present invention;

[0069] Figure 5 This is a schematic diagram of the structure of a buffer tank in an embodiment of a closed-pipe conventional liquid propellant treatment system of the present invention;

[0070] Figure 6 for Figure 5 Enlarged view of point A in the middle;

[0071] Figure 7 This is a schematic diagram of the diffuser cross-section of a buffer tank in an embodiment of a conventional liquid propellant treatment system with a closed pipeline according to the present invention.

[0072] The annotations in the attached figures are explained as follows:

[0073] 1-Propellant tank, 2-Tank isolation valve, 3-Purge process port of the treated pipeline, 4-Discharge process port of the treated pipeline, 5-Liquid engine, 6-Purge isolation valve, 7-First displacement isolation valve, 8-Pressure detector, 9-Pressure reducer, 10-Discharge isolation valve, 11-Neutralization treatment device, 12-Neutralization treatment device inlet valve, 13-Neutralization treatment device exhaust valve, 14-Buffer tank, 141-Diffuser, 142-Through hole, 15-Vacuum isolation valve, 16-Vacuum gauge, 17-Vacuum gauge isolation valve, 18-Second displacement isolation valve, 19-Vacuum pump isolation valve, 20-Buffer tank drain valve, 21-Filter, 22-Vacuum pump. Detailed Implementation

[0074] To make the objectives, advantages and features of the present invention clearer, the following describes in further detail a closed-pipe conventional liquid propellant treatment system and method proposed by the present invention, in conjunction with the accompanying drawings and specific embodiments.

[0075] In the description of this invention, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0076] Figure 1 The diagram shows a typical propellant pipeline layout for a conventional liquid propulsion system. The propellant pipeline connects the propellant tank 1 and the liquid engine 5. A tank isolation valve 2 is installed between the propellant pipeline and the propellant tank 1. A purging process port 3 for the pipeline to be treated is installed at the end of the propellant pipeline near the tank isolation valve 2. A discharge process port 4 for the pipeline to be treated is installed at the end of the propellant pipeline near the liquid engine 5. A purging isolation valve is installed at the purging process port 3 for the pipeline to be treated, and a discharge isolation valve is installed at the discharge process port 4 for the pipeline to be treated. Both the purging isolation valve and the discharge isolation valve are closed when not in operation.

[0077] like Figure 2 and Figure 3 As shown, a closed-pipe conventional liquid propellant treatment system of this embodiment includes a pressurization purging system, a vacuum suction system, and a neutralization treatment device 11.

[0078] like Figure 2 As shown, the pressurized purging system includes a pressurized gas source, a pressurized pipeline, a pressure detector 8, a pressure reducer 9, and a first displacement isolation valve 7. The pressurized gas source is used to supply nitrogen. One end of the pressurized pipeline is connected to the pressurized gas source. The pressure reducer 9, the pressure detector 8, and the first displacement isolation valve 7 are connected sequentially to the pressurized pipeline along the gas supply direction. The pressure reducer 9 is used to adjust the output pressure of the pressurized pipeline. The pressure detector 8 is a pressure gauge.

[0079] In other embodiments, the pressure detector 8 may also be a pressure sensor.

[0080] In other embodiments, if necessary, the pressurization purging system also includes a heating device installed on the pressurization pipeline. The heating device is used to heat the gas in the pressurization pipeline. Hot nitrogen purging can increase the steam temperature in the pipeline, increase the saturated vapor pressure of the propellant, and improve the processing efficiency.

[0081] like Figure 3 and Figure 4 As shown, the vacuum suction system includes a buffer tank 14, a vacuum pump 22, and a vacuum gauge 16.

[0082] The buffer tank 14 is used for vacuum buffering of the pipeline. For pipelines with a volume of less than 10L, the volume of the buffer tank 14 is 10 to 30 times the volume of the pipeline, or the volume of the buffer tank 14 is 10L to 30L. For pipelines with a volume of more than 10L, the volume of the buffer tank 14 is 1 to 10 times the volume of the pipeline, or the volume of the buffer tank 14 is 10L to 100L.

[0083] The buffer tank 14 is equipped with a vacuum isolation valve 15, a vacuum gauge isolation valve 17, a second displacement isolation valve 18, a vacuum pump isolation valve 19, and a buffer tank drain valve 20. The vacuum pump isolation valve 19 is installed on the top of the buffer tank 14 and is used to isolate the vacuum pump 22. The inlet of the vacuum pump 22 is connected to the buffer tank 14 through the vacuum pump isolation valve 19, and a filter 21 is connected between the vacuum pump isolation valve 19 and the vacuum pump 22. The filter 21 prevents foreign matter from being sucked into the vacuum pump 22 during vacuuming, which could cause malfunctions. The vacuum gauge isolation valve 17 is installed on the top of the buffer tank 14, and the vacuum gauge 16 is connected to the buffer tank 14 through the vacuum gauge isolation valve 17. During vacuuming, the vacuum gauge isolation valve 17 opens to connect the vacuum gauge 16 to the buffer tank 14 for vacuum measurement. When the buffer tank 14 is purged with nitrogen, the vacuum gauge isolation valve 17 is closed to protect the vacuum gauge 16 from positive pressure. The vacuum isolation valve 15 is installed on the side wall of the buffer tank 14. The vacuum isolation valve 15 is used to connect to the purge isolation valve 6 at the purge process port 3 of the treated pipeline or the discharge isolation valve 10 at the discharge process port 4 of the treated pipeline through a pipeline. The vacuum isolation valve 15 is used to isolate the pumped pipeline. The second replacement isolation valve 18 is installed on the top of the buffer tank 14. The second replacement isolation valve 18 is used to connect to the other end of the pressurization pipeline. The second replacement isolation valve 18 is used to replace the buffer tank 14 with nitrogen. The buffer tank drain valve 20 is installed at the bottom of the buffer tank 14. The buffer tank drain valve 20 is used to discharge the propellant in the buffer tank 14 and to replace the buffer tank 14.

[0084] like Figure 3 , Figure 5 , Figure 6 , Figure 7 As shown, the buffer tank 14 is connected to the second displacement isolation valve 18 via a diffuser 141. The upper end of the diffuser 141 is connected to the second displacement isolation valve 18, and the lower end of the diffuser 141 is sealed and extends into the buffer tank 14. Multiple through holes 142 are provided on the outer periphery of the diffuser 141 near the lower end. The through holes 142 connect the diffuser 141 and the buffer tank 14. Specifically, four rings of through holes 142 are provided on the outer periphery of the diffuser 141 near the lower end along the axial direction of the diffuser 141. Each ring of through holes 142 includes six through holes 142. The six through holes 142 in the same ring are evenly distributed around the axis of the diffuser 141, and the axis of the through holes 142 extends along the radial direction of the diffuser 141. Propellants have a certain degree of adsorption, especially hydrazine fuels, which have strong adsorption. When gas purging is not used, they adhere to the wall of buffer tank 14 and require a longer pumping time to remove them completely. Using a diffuser tube can make the purging gas evenly blown to the inner wall of buffer tank 14, thereby improving the purging and replacement efficiency.

[0085] Vacuum pump 22 is an oil-free, dry, explosion-proof, corrosion-resistant screw vacuum pump. The explosion-proof rating of vacuum pump 22 meets the corresponding propellant explosion-proof rating, generally not lower than ExdII BT4. Screw pumps have the advantages of being adaptable to harsh working conditions, having the ability to pump condensable gases containing particulate matter, and being easy to perform anti-corrosion treatment. Oil-free dry pumps can avoid oil contamination of the pumped pipeline. Corrosion resistance can effectively prevent the propellant from corroding the parts of the pump body that come into contact with the gas, reducing pump failures and improving the reliability and safety of pump operation.

[0086] Vacuum gauge 16 is used to measure the vacuum level at buffer tank 14. Its measurement range should cover 0 Pa to 100 kPa to facilitate the detection of the vacuuming process and assist in judging the effect of residual propellant treatment.

[0087] The neutralization treatment device 11 is used to neutralize liquid propellants. It is generally a container filled with neutralizing liquid. The neutralization treatment device 11 is equipped with a neutralization treatment device inlet valve 12 at its inlet and a neutralization treatment device exhaust valve 13 at its outlet. The inlet of the neutralization treatment device 11 is used to connect with the discharge isolation valve 10, or to connect with the outlet of the vacuum pump 22 and the buffer tank drain valve 20 simultaneously. The outlet of the neutralization treatment device 11 is used to connect with the plant exhaust port through a pipe or to lead it outdoors.

[0088] This embodiment of a closed-pipe conventional liquid propellant treatment method, employing the aforementioned closed-pipe conventional liquid propellant treatment system, includes the following steps:

[0089] S1, Pipeline connection

[0090] S1.1 Connect the other end of the pressurization pipeline of the pressurization and purging system to the purging isolation valve 6 at the purging process port 3 of the pipeline to be treated, and adjust the air supply pressure to the preset target value by adjusting the pressure reducer 9. The preset target value is 0.3 to 0.5 MPa.

[0091] S1.2 Connect the inlet of the neutralization treatment device 11 to the discharge isolation valve 10 at the discharge process port 4 of the treated pipeline using a pipeline, connect the outlet of the neutralization treatment device 11 to the plant exhaust port using a pipeline or lead it to an open space outside the plant, and open the neutralization treatment device exhaust valve 13 to keep the neutralization treatment device 11 ventilated.

[0092] S1.1 and S1.2 have no order of priority and can be performed simultaneously or sequentially.

[0093] S2, nitrogen replacement

[0094] Confirm that purge isolation valve 6 is closed;

[0095] Complete the following operations at least three times: Open the first displacement isolation valve 7 to allow nitrogen to be discharged from the first displacement isolation valve 7 through the pressurization pipeline to displace the air in the pressurization pipeline; after opening the first displacement isolation valve 7 for no less than 1 minute, close the first displacement isolation valve 7.

[0096] By first purging the pressurization pipeline with nitrogen in step S2, air can be prevented from entering the pipeline being treated.

[0097] S3, Pipeline purging

[0098] S3.1 Open the purge isolation valve 6 to allow purge nitrogen to enter the pipeline being treated. Then, open the discharge isolation valve 10 and the neutralization treatment device inlet valve 12 in sequence to allow the propellant liquid and vapor in the pipeline being treated to enter the neutralization treatment device 11 and be discharged after neutralization reaction.

[0099] S3.2 Repeatedly open and close the discharge isolation valve 10 at time intervals of 3-5 minutes to intermittently purge the treated pipeline for 15-30 minutes to complete the purging of the treated pipeline;

[0100] S3.3 Close the discharge isolation valve 10, the purge isolation valve 6, the neutralization treatment device inlet valve 12 and the neutralization treatment device exhaust valve 13 in sequence, and remove the pressurization purge system and the neutralization treatment device 11;

[0101] Step S3.1 uses nitrogen positive pressure to purge the pipeline, which can remove most of the residual liquid propellant in the pipeline. In step S3.2, the discharge isolation valve 10 is closed, and the pipeline is pressurized and left to stand for several minutes. This standing allows the nitrogen and propellant vapor in the pipeline to mix, making it easier to remove the residual vapor during the subsequent purge process when the discharge isolation valve 10 is opened. In addition, the pressurized pipeline is pressurized, and when the discharge isolation valve 10 is opened, the gas flows out rapidly from the static state, easily carrying the propellant and vapor out. Step S3 can effectively remove most of the residual propellant in the pipeline.

[0102] S4, Vacuum suction system connection

[0103] Connect the vacuum isolation valve 15 of the buffer tank 14 to the purge isolation valve 6 through a pipeline. Connect the outlet of the buffer tank drain valve 20 and the vacuum pump 22 of the buffer tank 14 to the inlet valve 12 of the neutralization treatment device through pipelines. Connect the second displacement isolation valve 18 of the buffer tank 14 to the other end of the pressurization pipeline of the pressurization purge system. Make the vacuum gauge isolation valve 17, the inlet valve 12 of the neutralization treatment device and the exhaust valve 13 of the neutralization treatment device open. Confirm that the purge isolation valve 6, the discharge isolation valve 10, the vacuum isolation valve 15, the second displacement isolation valve 18, the vacuum pump isolation valve 19 and the buffer tank drain valve 20 are closed. Start the vacuum pump 22.

[0104] S5, Vacuuming process

[0105] S5.1 Open the vacuum pump isolation valve 19 and keep it open for 1 to 5 minutes. Then observe whether the reading of the vacuum gauge 16 is less than 10 Pa. If it is, close the vacuum pump isolation valve 19 and proceed to step S5.2. If not, proceed to step S5.3.

[0106] S5.2 Open the vacuum isolation valve 15, then open the purge isolation valve 6 to draw the residual propellant vapor in the treated pipeline into the buffer tank 14. At this time, the reading of the vacuum gauge 16 increases. After 1 to 3 minutes, close the purge isolation valve 6, the vacuum isolation valve 15, and the vacuum gauge isolation valve 17. Open the second replacement isolation valve 18 and the buffer tank drain valve 20. Adjust the pressure reducer 9 and purge the buffer tank 14 with nitrogen gas at 0.3 to 0.5 MPa for 1 to 3 minutes. Then close the second replacement isolation valve 18 and the buffer tank drain valve 20, open the vacuum gauge isolation valve 17, and execute step S5.5.

[0107] S5.3 Observe whether the reading of vacuum gauge 16 is less than 50Pa. If yes, close vacuum pump isolation valve 19 and proceed to step S5.2. If no, proceed to step S5.4.

[0108] S5.4 Confirm that the vacuum isolation valve 15 is closed, close the vacuum gauge isolation valve 17, open the second displacement isolation valve 18, adjust the pressure reducer 9, and purge the buffer tank 14 and vacuum pump 22 with nitrogen gas at 0.05-0.1 MPa for 1-3 minutes. Then close the second displacement isolation valve 18, open the vacuum gauge isolation valve 17, and continue for 1-5 minutes. Observe whether the reading of the vacuum gauge 16 is less than 10 Pa. If yes, close the vacuum pump isolation valve 19 and execute step S5.2. If no, repeat step S5.4 until the reading of the vacuum gauge 16 is less than 10 Pa.

[0109] S5.5 Repeat step S5.1 twice, then proceed to step S6;

[0110] The strong adsorption properties of liquid propellant can reduce the vacuum pumping efficiency of vacuum pump 22. By purging and replacing the buffer tank 14 and vacuum pump 22 in steps S5.3 and S5.4, the vacuum pumping efficiency of vacuum pump 22 can be improved. After completing step S5, there is basically no residual propellant liquid in the treated pipeline.

[0111] S6 switches to the vacuuming position and continues vacuuming.

[0112] S6.1 Confirm that the purge isolation valve 6 is closed, remove the vacuum suction system from the purge isolation valve 6, and connect the vacuum isolation valve 15 of the buffer tank 14 to the discharge isolation valve 10 through the pipeline.

[0113] S6.2 Continue vacuuming process

[0114] S6.2.1 Open the vacuum pump isolation valve 19 and keep it open for 1 to 5 minutes. Then observe whether the reading of the vacuum gauge 16 is less than 10 Pa. If yes, close the vacuum pump isolation valve 19 and proceed to step S6.2.2. If no, proceed to step S6.2.3.

[0115] S6.2.2 Open the vacuum isolation valve 15, then open the discharge isolation valve 10 to draw the residual propellant vapor in the treated pipeline into the buffer tank 14. At this time, the reading of the vacuum gauge 16 increases. After 1 to 3 minutes, close the discharge isolation valve 10, the vacuum isolation valve 15, and the vacuum gauge isolation valve 17. Open the second replacement isolation valve 18 and the buffer tank drain valve 20. Adjust the pressure reducer 9 and purge the buffer tank 14 with nitrogen gas at 0.3 to 0.5 MPa for 1 to 3 minutes. Then close the second replacement isolation valve 18 and the buffer tank drain valve 20, open the vacuum gauge isolation valve 17, and execute step S6.2.5.

[0116] S6.2.3 Observe whether the reading of vacuum gauge 16 is less than 50Pa. If yes, close vacuum pump isolation valve 19 and proceed to step S6.2.2. If no, proceed to step S6.2.4.

[0117] S6.2.4 Confirm that the vacuum isolation valve 15 is closed, close the vacuum gauge isolation valve 17, open the second displacement isolation valve 18, adjust the pressure reducer 9, and purge the buffer tank 14 and vacuum pump 22 with nitrogen gas at 0.05-0.1 MPa for 1-3 minutes. Then close the second displacement isolation valve 18, open the vacuum gauge isolation valve 17, and continue for 1-5 minutes. Observe whether the reading of the vacuum gauge 16 is less than 10 Pa. If yes, close the vacuum pump isolation valve 19 and execute step S6.2.2. If no, repeat step S6.2.4 until the reading of the vacuum gauge 16 is less than 10 Pa.

[0118] S6.2.5 Repeat step S6.2.1 twice, then proceed to step S7;

[0119] Step S6 involves vacuuming the pipe being processed to expel residual propellant from the blind cavity near the inlet pipe of the liquid engine 5 more quickly.

[0120] S7, Pressure Holding

[0121] Open the vacuum pump isolation valve 19, evacuate until the vacuum gauge 16 reading is below 10 Pa, then close the vacuum pump isolation valve 19, open the vacuum isolation valve 15 and the discharge isolation valve 10, let stand for 3 minutes, and observe through the vacuum gauge 16 whether the vacuum degree does not exceed 100 Pa. If so, and the vacuum degree rises slowly, then the pipeline being treated has been vacuumed and cleaned. Close the discharge isolation valve 10, the neutralization treatment device inlet valve 12, the neutralization treatment device exhaust valve 13, the vacuum isolation valve 15, the vacuum gauge isolation valve 17 and the vacuum pump 22, remove the vacuum suction system, and then proceed to step S8; if not, close the vacuum isolation valve 15 and the discharge isolation valve 10 and return to step S6.2, or close the discharge isolation valve 10, the neutralization treatment device inlet valve 12, the neutralization treatment device exhaust valve 13, the vacuum isolation valve 15, the vacuum gauge isolation valve 17 and the vacuum pump 22, remove the vacuum suction system, and then return to step S4;

[0122] S8, Positive Pressure Seal

[0123] Connect the other end of the pressurization pipeline of the pressurization and purging system to the purging isolation valve 6, and perform nitrogen purging using the same method as in step S2. Then, open the purging isolation valve 6 to seal the pipeline being treated, bringing the pressure inside the pipeline to 0.2–0.5 MPa. Finally, close the purging isolation valve 6, dismantle the pressurization and purging system, and complete the conventional liquid propellant treatment of the sealed pipeline. By performing positive pressure sealing on the pipeline being treated in step S8, it is possible to prevent trace amounts of air from leaking into the pipeline after the propellant pipeline has been evacuated.

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended 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 specific technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. A closed-pipe conventional liquid propellant handling system, characterized in that, include: The pressurized purging system includes a pressurized air source, a pressurized pipeline connected to the pressurized air source at one end, and a first displacement isolation valve (7) connected to the pressurized pipeline; The vacuum suction system includes a buffer tank (14), a vacuum pump (22), and a vacuum gauge (16). The inlet of the vacuum pump (22) is connected to the buffer tank (14) through a vacuum pump isolation valve (19), and the vacuum gauge (16) is connected to the buffer tank (14) through a vacuum gauge isolation valve (17). The buffer tank (14) is also equipped with a vacuum isolation valve (15), a second displacement isolation valve (18), and a buffer tank drain valve (20). The vacuum isolation valve (15) is used to connect to the purge isolation valve (6) at the purge process port (3) of the treated pipeline or the discharge isolation valve (10) at the discharge process port (4) of the treated pipeline through a pipeline. The second displacement isolation valve (18) is used to connect to the other end of the pressurization pipeline. The buffer tank drain valve (20) is used to discharge the propellant in the buffer tank (14) and to displace the buffer tank (14). The neutralization treatment device (11) is equipped with a neutralization treatment device inlet valve (12) at the inlet and a neutralization treatment device exhaust valve (13) at the outlet. The inlet is used to connect with the discharge isolation valve (10) or to connect with the outlet of the vacuum pump (22) and the buffer tank drain valve (20) at the same time. The outlet is used to connect with the plant exhaust port through a pipe or lead to the outdoors.

2. The closed-pipe conventional liquid propellant handling system according to claim 1, characterized in that: The pressurized purging system also includes a pressure detector (8) and a pressure reducer (9); The pressure reducer (9) and the pressure detector (8) are connected sequentially to the booster pipeline along the gas supply direction; The pressure detector (8) is a pressure gauge or a pressure sensor.

3. The closed-pipe conventional liquid propellant handling system according to claim 2, characterized in that: The pressurization and purging system also includes a heating device, which is installed on the pressurization pipeline and is used to heat the gas in the pressurization pipeline.

4. The closed-pipe conventional liquid propellant handling system according to claim 1, characterized in that: A filter (21) is connected between the vacuum pump isolation valve (19) and the vacuum pump (22); The vacuum pump (22) is an oil-free, dry, explosion-proof, corrosion-resistant screw vacuum pump; The explosion-proof rating of the vacuum pump (22) is not lower than ExdIIBT4.

5. The closed-pipe conventional liquid propellant handling system according to claim 1, characterized in that: The volume of the buffer tank (14) is 10 to 30 times the volume of the pipe being treated, or the volume of the buffer tank (14) is 10L to 30L, and it is used for pipes with a volume of less than 10L. Alternatively, the volume of the buffer tank (14) is 1 to 10 times the volume of the pipe being processed, or the volume of the buffer tank (14) is 10L to 100L, for pipes with a volume greater than 10L being processed.

6. The closed-pipe conventional liquid propellant handling system according to claim 1, characterized in that: The vacuum isolation valve (15) is installed on the side wall of the buffer tank (14), the vacuum gauge isolation valve (17), the second displacement isolation valve (18) and the vacuum pump isolation valve (19) are all installed on the top of the buffer tank (14), and the buffer tank drain valve (20) is installed on the bottom of the buffer tank (14). The buffer tank (14) is connected to the second displacement isolation valve (18) via a diffuser (141); The upper end of the diffuser (141) is connected to the second displacement isolation valve (18), the lower end of the diffuser (141) is blocked and extends into the buffer tank (14). Multiple through holes (142) are provided on the outer periphery of the diffuser (141) near the lower end, and the through holes (142) connect the diffuser (141) and the buffer tank (14).

7. A method for treating conventional liquid propellant in a closed pipeline, characterized in that, The closed-pipe conventional liquid propellant handling system according to any one of claims 1-6 includes the following steps: S1, Pipeline connection S1.1 Connect the other end of the pressurization pipeline of the pressurization and purging system to the purging isolation valve (6) at the purging process port (3) of the pipeline to be treated, and adjust the air supply pressure to the preset target value; S1.2 Connect the inlet of the neutralization treatment device (11) to the discharge isolation valve (10) at the discharge process port (4) of the treated pipeline using a pipeline, connect the outlet of the neutralization treatment device (11) to the plant exhaust port using a pipeline or lead it outdoors, and open the exhaust valve (13) of the neutralization treatment device to keep the neutralization treatment device (11) ventilated. S1.1 and S1.2 have no order of priority and can be performed simultaneously or sequentially. S2, nitrogen replacement Confirm that the purge isolation valve (6) is closed; Complete the following operation at least once: open the first displacement isolation valve (7) to allow nitrogen to be discharged from the first displacement isolation valve (7) through the pressurization pipeline to replace the air in the pressurization pipeline, and close the first displacement isolation valve (7) after a first preset time. S3, Pipeline purging S3.1 Open the purge isolation valve (6) to allow purge nitrogen to enter the pipeline to be treated. Then, open the discharge isolation valve (10) and the neutralization treatment device inlet valve (12) in sequence to allow the propellant liquid and vapor in the pipeline to enter the neutralization treatment device (11) and be discharged after neutralization reaction. S3.2 The discharge isolation valve (10) is repeatedly closed and opened at preset time intervals to intermittently purge the treated pipeline for a preset time, thereby completing the purging of the treated pipeline; S3.

3. Close the discharge isolation valve (10), the purge isolation valve (6), the neutralization treatment device inlet valve (12) and the neutralization treatment device exhaust valve (13) in sequence, and remove the pressurization purge system and the neutralization treatment device (11); S4, Vacuum suction system connection Connect the vacuum isolation valve (15) of the buffer tank (14) to the purge isolation valve (6) through a pipeline. Connect the outlet of the buffer tank drain valve (20) of the buffer tank (14) and the vacuum pump (22) to the inlet valve (12) of the neutralization treatment device through pipelines. Connect the second displacement isolation valve (18) of the buffer tank (14) to the other end of the pressurization pipeline of the pressurization purge system. Make the vacuum gauge isolation valve (17), the inlet valve (12) of the neutralization treatment device and the exhaust valve (13) of the neutralization treatment device open. Confirm that the purge isolation valve (6), the discharge isolation valve (10), the vacuum isolation valve (15), the second displacement isolation valve (18), the vacuum pump isolation valve (19) and the buffer tank drain valve (20) are closed. Start the vacuum pump (22). S5, Vacuuming process S5.1 Open the vacuum pump isolation valve (19), and after a second preset time, observe whether the reading of the vacuum gauge (16) is less than the first preset pressure value. If yes, close the vacuum pump isolation valve (19) and execute step S5.

2. If no, execute step S5.

3. S5.2 Open the vacuum isolation valve (15), and then open the purge isolation valve (6) to draw the residual propellant vapor in the treated pipeline into the buffer tank (14). At this time, the reading of the vacuum gauge (16) increases. After the third preset time, close the purge isolation valve (6), the vacuum isolation valve (15), and the vacuum gauge isolation valve (17). Open the second replacement isolation valve (18) and the buffer tank drain valve (20). Adjust the output pressure of the pressurization pipeline. Use nitrogen at the second preset pressure value to purge and replace the buffer tank (14) for the fourth preset time. Then close the second replacement isolation valve (18) and the buffer tank drain valve (20). Open the vacuum gauge isolation valve (17) and execute step S5.

5. S5.3 Observe whether the reading of the vacuum gauge (16) is less than the third preset pressure value. If yes, close the vacuum pump isolation valve (19) and execute step S5.

2. If no, execute step S5.

4. The third preset pressure value is greater than the first preset pressure value. The third preset pressure value is used to determine whether the vacuum pump (22) can continue to work effectively due to the strong adsorption of the liquid propellant. S5.4 Confirm that the vacuum isolation valve (15) is closed, close the vacuum gauge isolation valve (17), open the second displacement isolation valve (18), adjust the output pressure of the pressurization pipeline, and purge and replace the buffer tank (14) and vacuum pump (22) with nitrogen at the fourth preset pressure value. After the fifth preset time, close the second displacement isolation valve (18), open the vacuum gauge isolation valve (17), and after the second preset time, observe whether the vacuum gauge (16) reading is less than the first preset pressure value. If yes, close the vacuum pump isolation valve (19) and execute step S5.

2. If no, repeat step S5.4 until the vacuum gauge (16) reading is less than the first preset pressure value. S5.5 After repeating step S5.1 at least once, proceed to step S6; S6 switches to the vacuuming position and continues vacuuming. S6.1 Confirm that the purge isolation valve (6) is closed, remove the vacuum suction system from the purge isolation valve (6), and connect the vacuum isolation valve (15) of the buffer tank (14) to the discharge isolation valve (10) through the pipeline; S6.2 Using the same method as step S5, the pipe to be processed is evacuated to allow the residual propellant in the blind cavity of the inlet pipe near the liquid engine (5) to be extracted more quickly. S7, Pressure Holding Open the vacuum pump isolation valve (19), evacuate until the vacuum gauge (16) reading is lower than the first preset pressure value, close the vacuum pump isolation valve (19), open the vacuum isolation valve (15) and the discharge isolation valve (10), and let stand for a sixth preset time. Observe whether the vacuum degree does not exceed the fifth preset pressure value through the vacuum gauge (16). If yes, close the discharge isolation valve (10), the neutralization treatment device inlet valve (12), the neutralization treatment device exhaust valve (13), the vacuum isolation valve (15), the vacuum gauge isolation valve (17), and the vacuum pump (22), remove the vacuum suction system, and then execute step S8; if no, close the vacuum isolation valve (15) and the discharge isolation valve (10) and return to step S6.2, or close the discharge isolation valve (10), the neutralization treatment device inlet valve (12), the neutralization treatment device exhaust valve (13), the vacuum isolation valve (15), the vacuum gauge isolation valve (17), and the vacuum pump (22), remove the vacuum suction system, and then return to step S4; S8, Positive Pressure Seal Connect the other end of the pressurization pipeline of the pressurization and purging system to the purging isolation valve (6), perform nitrogen replacement using the same method as in step S2, then open the purging isolation valve (6) to seal the pipeline to be treated, so that the pressure in the pipeline to be treated reaches the sixth preset pressure value, and finally close the purging isolation valve (6), dismantle the pressurization and purging system, and complete the conventional liquid propellant treatment of the closed pipeline.

8. The conventional liquid propellant treatment method for closed pipelines according to claim 7, characterized in that: In step S1, the gas supply pressure is adjusted to a preset target value by adjusting the pressure reducer (9), wherein the preset target value is 0.3 to 0.5 MPa; In step S2, it shall be completed at least three times; the first preset time shall not be less than 1 minute; Step S3.2 specifically involves repeatedly opening and closing the discharge isolation valve (10) at time intervals of 3-5 minutes and 3-5 minutes to intermittently purge the treated pipeline for 15-30 minutes, thereby completing the purging of the treated pipeline. In step S7, the sixth preset time is 3 minutes, and the fifth preset pressure value is 100 Pa. In step S8, the sixth preset pressure value is 0.2 to 0.5 MPa.

9. The method for treating conventional liquid propellants in a closed pipeline according to claim 7, characterized in that: In step S5.1, the first preset pressure value is 10 Pa, and the second preset time is 1 to 5 min; In step S5.2, the third preset time is 1 to 3 minutes, the second preset pressure value is 0.3 to 0.5 MPa, and the fourth preset time is 1 to 3 minutes. In step S5.3, the third preset pressure value is 50 Pa; In step S5.4, the fourth preset pressure value is 0.05 to 0.1 MPa, and the fifth preset time is 1 to 3 minutes; Step S5.5 specifically involves repeating step S5.1 twice, and then executing step S6.

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