CN111810832A - Vacuum multilayer heat-insulation low-temperature container interlayer nitrogen flushing and replacing system and method - Google Patents
Vacuum multilayer heat-insulation low-temperature container interlayer nitrogen flushing and replacing system and method Download PDFInfo
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- CN111810832A CN111810832A CN202010785999.0A CN202010785999A CN111810832A CN 111810832 A CN111810832 A CN 111810832A CN 202010785999 A CN202010785999 A CN 202010785999A CN 111810832 A CN111810832 A CN 111810832A
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 359
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 179
- 239000011229 interlayer Substances 0.000 title claims abstract description 144
- 238000011010 flushing procedure Methods 0.000 title claims abstract description 36
- 238000009413 insulation Methods 0.000 title claims abstract description 30
- 238000000034 method Methods 0.000 title claims abstract description 16
- 239000007789 gas Substances 0.000 claims abstract description 70
- 239000010410 layer Substances 0.000 claims abstract description 29
- 238000004891 communication Methods 0.000 claims abstract description 19
- 238000011049 filling Methods 0.000 claims abstract description 17
- 238000005086 pumping Methods 0.000 claims description 14
- 229910001873 dinitrogen Inorganic materials 0.000 claims 1
- 230000000694 effects Effects 0.000 abstract description 8
- 238000000605 extraction Methods 0.000 abstract 1
- 238000010438 heat treatment Methods 0.000 description 47
- 238000001035 drying Methods 0.000 description 11
- 239000007788 liquid Substances 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- 238000007789 sealing Methods 0.000 description 4
- 239000012774 insulation material Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 239000011810 insulating material Substances 0.000 description 2
- 238000010926 purge Methods 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 230000002045 lasting effect Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C3/00—Vessels not under pressure
- F17C3/02—Vessels not under pressure with provision for thermal insulation
- F17C3/08—Vessels not under pressure with provision for thermal insulation by vacuum spaces, e.g. Dewar flask
- F17C3/085—Cryostats
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/14—Production of inert gas mixtures; Use of inert gases in general
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C1/00—Pressure vessels, e.g. gas cylinder, gas tank, replaceable cartridge
- F17C1/12—Pressure vessels, e.g. gas cylinder, gas tank, replaceable cartridge with provision for thermal insulation
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C13/00—Details of vessels or of the filling or discharging of vessels
- F17C13/001—Thermal insulation specially adapted for cryogenic vessels
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C2203/00—Vessel construction, in particular walls or details thereof
- F17C2203/03—Thermal insulations
- F17C2203/0391—Thermal insulations by vacuum
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C2209/00—Vessel construction, in particular methods of manufacturing
- F17C2209/23—Manufacturing of particular parts or at special locations
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Filling Or Discharging Of Gas Storage Vessels (AREA)
Abstract
The invention discloses a system and a method for flushing and replacing interlayer nitrogen of a vacuum multilayer heat-insulation low-temperature container, wherein the system comprises a nitrogen filling device, an automatic air outlet control valve, a vacuumizing device and a control system; the nitrogen charging device, the automatic air outlet control valve and the vacuumizing device are all communicated with an interlayer of the vacuum multi-layer heat-insulation low-temperature container; the nitrogen charging device comprises a nitrogen source, a nitrogen heater and an air inlet control valve, wherein the nitrogen source is provided with an air supply valve, the air outlet end of the nitrogen source is connected with the air inlet end of the nitrogen heater, the air outlet end of the nitrogen heater is connected with the air inlet end of the air inlet control valve, and the air outlet end of the air inlet control valve is communicated with the interlayer; the air supply valve, the nitrogen heater, the air inlet control valve, the vacuumizing device and the automatic air outlet control valve are all in communication connection with the control system. By adopting the technical scheme, the interlayer gas replacement effect is good, the extraction efficiency of the replaced nitrogen is improved, and the durable high-vacuum service life can be further obtained.
Description
Technical Field
The invention belongs to the technical field of vacuumizing of vacuum multilayer heat-insulation low-temperature container interlayers, and particularly relates to a nitrogen flushing and replacing system and a nitrogen flushing and replacing method for a vacuum multilayer heat-insulation low-temperature container interlayer, which can thoroughly replace interlayer moisture and other non-condensable gas molecules and are used for replacing gas in the interlayer of the low-temperature container before vacuumizing.
Background
With the wider application range of the frozen liquefied gas, the requirement on the heat insulation performance of a device for storing and transporting the frozen liquefied gas is higher, and particularly, containers for storing and transporting cryogenic low-temperature liquid such as liquid oxygen, liquid nitrogen, liquid hydrogen, liquid argon, LNG and the like can meet the heat insulation requirement only by selecting a high-vacuum multi-layer heat insulation structure. The container has high requirement on interlayer vacuum, and the vacuum degree of the cold working interlayer in the whole interlayer vacuum life cycle (5 years) of the container is required to be superior to 0.03Pa (absolute pressure). Therefore, the interlayer vacuum is one of important indexes influencing the heat insulation performance of the low-temperature container, and is an important technical link in the manufacturing and maintenance process of the vacuum multi-layer heat insulation container.
In the case of structural solidification, the interlayer vacuum is the only index affecting the heat insulation performance of the vacuum multi-layer heat insulation cryogenic container. The traditional interlayer vacuum pumping process has the defects of large energy consumption, long consumed time, high labor consumption, short service life of the obtained vacuum and the like; in addition, the multilayer heat insulation container is covered with a multilayer heat insulation material on the inner container, the heat insulation material is formed by stacking dozens of layers or even hundreds of layers of film materials and then is wound on the inner container, and the multilayer heat insulation container has the characteristics of small heat conductivity coefficient, more layers, large surface area, tight arrangement and the like, and the characteristics cause the multilayer heat insulation material to have the problems of poor heat transfer, large adsorbed gas amount, difficult desorption of adsorbed gas and the like.
In view of the above problems, patent CN101021209A discloses a vacuum pumping method and a device thereof, comprising: a first gas delivery device having a gas outlet; the inlet of the first gas heater is communicated with the gas outlet of the first gas conveying device, and the outlet of the first gas heater is communicated with the gas inlet of the inner cylinder; the vacuumizing unit is communicated with the interlayer; a second gas delivery device having a gas outlet; and the inlet of the second gas heater is communicated with the gas outlet of the second gas conveying device, and the outlet of the second gas heater is communicated with the interlayer.
The patent No. CN102913749A discloses a vacuum pumping system and a method for a large-volume low-temperature heat insulation container, which comprises a gas supply device, a vacuum pumping device and a heating device; the heating device comprises an outer tank heating device and an inner tank heating device; the heat-insulating container to be vacuumized comprises an outer tank, an inner tank and an interlayer formed by the outer tank and the inner tank; the outer tank heating device is arranged outside the outer tank of the heat-insulating container to be vacuumized; the inner tank heating device is arranged inside the inner tank of the heat-insulating container to be vacuumized; the air supply device is communicated with the inner tank of the heat-insulating container to be vacuumized and the interlayer through pipelines respectively; the vacuumizing device is communicated with the inner tank of the heat-insulating container to be vacuumized and the interlayer through pipelines respectively.
The scheme that above-mentioned patent all need wash the gas in the intermediate layer through gas supply unit (or gas conveyor), realizes replacing the difficult gas that breaks away from in the intermediate layer, then utilizes evacuating device to take out the gas of washing usefulness, makes the intermediate layer be in the vacuum state, and then improves adiabatic performance. However, in the two technical solutions, the interlayer replacement adopts a closed inflation mode, so that an over-inflation or under-inflation phenomenon is easily generated during actual operation, the effect of the replacement mode is not ideal, the vacuum degree of the interlayer is affected, and finally the heat insulation performance of the container is deteriorated.
Disclosure of Invention
The invention aims to provide a nitrogen flushing and replacing system and a nitrogen flushing and replacing method for an interlayer of a vacuum multilayer heat-insulating low-temperature container, aiming at the problems that the interlayer is poor in vacuum degree and poor in heat-insulating performance of the container due to the fact that the phenomena of over-filling and under-filling are easy to occur when the interlayer of the vacuum multilayer heat-insulating low-temperature container in the prior art is replaced by nitrogen.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention relates to a vacuum multilayer heat insulation low-temperature container interlayer nitrogen flushing and replacing system which comprises a nitrogen filling device, an automatic air outlet control valve, a vacuumizing device and a control system, wherein the nitrogen filling device is connected with the vacuumizing device through a pipeline; the nitrogen charging device, the automatic air outlet control valve and the vacuumizing device are all communicated with an interlayer of the vacuum multi-layer heat-insulation low-temperature container; the nitrogen charging device comprises a nitrogen source, a nitrogen heater and an air inlet control valve, wherein the nitrogen source is provided with an air supply valve, the air outlet end of the nitrogen source is connected with the air inlet end of the nitrogen heater, the air outlet end of the nitrogen heater is connected with the air inlet end of the air inlet control valve, and the air outlet end of the air inlet control valve is communicated with the interlayer; the air supply valve, the nitrogen heater, the air inlet control valve, the vacuumizing device and the automatic air outlet control valve are all in communication connection with the control system.
Preferably, the nitrogen charging device further comprises a first temperature sensor and a pressure sensor, the first temperature sensor is connected between the nitrogen heater and the air inlet control valve, the pressure sensor is connected between the air inlet control valve and the interlayer, and the first temperature sensor and the pressure sensor are both in communication connection with the control system.
Preferably, the nitrogen charging device further comprises a pressure limiting valve and a flow limiting valve, the pressure limiting valve and the flow limiting valve are sequentially connected between the gas supply valve and the nitrogen heater, and the flow limiting valve is in communication connection with the control system.
Preferably, the nitrogen charging device further comprises a safety valve, and the safety valve is connected between the nitrogen heater and the first temperature sensor.
Preferably, the vacuumizing device is provided with a vacuumizing valve for controlling the opening and closing of the vacuumizing device, the vacuumizing device is connected between the air inlet control valve and the pressure sensor, the vacuumizing device and the nitrogen filling device are further connected to the same connecting port of the interlayer, and the vacuumizing valve is in communication connection with the control system.
Preferably, the vacuum pumping device further comprises an interlayer evacuation valve, and the interlayer evacuation valve is connected between the pressure sensor and the interlayer.
Preferably, the vacuum pumping device further comprises a vacuum gauge for detecting the vacuum degree of the interlayer, the vacuum gauge is connected between the air inlet control valve and the pressure sensor, and the vacuum gauge is in communication connection with the control system.
Preferably, a second temperature sensor for detecting the temperature of the gas discharged from the interlayer is further connected between the automatic gas outlet control valve and the interlayer, and the second temperature sensor is in communication connection with a control system.
The invention also relates to a nitrogen flushing and replacing method based on the vacuum multilayer heat-insulation low-temperature container interlayer nitrogen flushing and replacing system, which comprises the following steps of:
s1, setting a vacuum degree threshold value, and starting a vacuumizing device by a control system to vacuumize an interlayer;
s2, when the vacuum degree of the interlayer is lower than a vacuum degree threshold value, the control system closes the vacuumizing device, vacuumizing of the interlayer is stopped, meanwhile, the control system opens the air supply valve, the nitrogen heater and the air inlet control valve, the nitrogen source provides nitrogen, the nitrogen is heated and then filled into the interlayer, when the pressure of the interlayer reaches 110KPa, the control system further opens the automatic air outlet control valve, the nitrogen is continuously filled and exhausted, and then original gas in the interlayer is replaced;
s3, the control system closes the automatic air outlet control valve, closes the air supply valve and the air inlet control valve, and simultaneously starts the vacuumizing device to pump out nitrogen in the interlayer;
s4, repeating the steps S2 and S3 for a plurality of times until the original gas in the interlayer is removed completely and the nitrogen is completely pumped out.
Preferably, the step S2 further includes setting a nitrogen temperature range, controlling the nitrogen temperature within the nitrogen temperature range, measuring the temperature of the nitrogen filled in the interlayer by the first temperature sensor and transmitting the temperature information to the control system, and controlling the nitrogen heater to be turned on or off by the control system according to the temperature measured by the first temperature sensor.
Compared with the prior art, the technical scheme provided by the invention has the following technical effects:
the invention relates to a nitrogen flushing and replacing system for an interlayer of a vacuum multi-layer heat-insulating low-temperature container, which comprises a nitrogen filling device, an automatic air outlet control valve and a vacuumizing device, wherein when gas in the interlayer is replaced, heated nitrogen is filled, replacement gas is released, the pressure of the interlayer is controlled at micro positive pressure, the phenomenon of over-filling or under-filling is avoided, negative pressure is formed in the interlayer space relative to the interlayer of a heat-insulating material when the interlayer is vacuumized, gasified moisture and non-condensable gas absorbed by a deep heat-insulating material can be desorbed, the interlayer is flushed by flowing hot nitrogen, the moisture and non-condensable gas components desorbed by the interlayer material can be favorably wrapped and flushed out of the interlayer, the replacing effect is thorough, and the vacuum degree and the heat insulation performance of the.
Drawings
FIG. 1 is a schematic diagram of a nitrogen purge and displacement system for a vacuum multi-layer insulating cryogenic container sandwich according to an embodiment;
FIG. 2 is a schematic diagram of a nitrogen purge and displacement system for an interlayer of a second vacuum multi-layer heat-insulating cryogenic container according to an embodiment;
FIG. 3 is a structural view of a heating device for an inner container according to a second embodiment;
FIG. 4 is a schematic view showing the structure of an outer vessel heating apparatus according to the second embodiment;
FIG. 5 is a graph of the vacuum level of the jacket of a cryocontainer after flushing the jacket and evacuation using the present invention as a function of time.
Wherein: 1. a nitrogen source; 2. an air supply valve; 3. a pressure limiting valve; 4. a flow-limiting valve; 5. a nitrogen heater; 6. a safety valve; 7. a first temperature sensor; 8. an intake control valve; 9. a vacuum gauge tube; 10. a vacuum valve; 11. a pressure sensor; 12. an interlayer evacuation valve; 13. a heat insulating layer; 14. an outer container heating means; 15. an outer container; 16. an inner container; 17. a second temperature sensor; 18. an automatic air outlet control valve; 19. an inner container heating means; 20. a vacuum pumping device; 21. a control system; 22. a first circulating fan; 23. a first gas heater; 24. an inner container air inlet valve; 25. an air outlet valve of the inner container; 26. a drying room; 27. a second circulating fan 28, a second gas heater; 29. a bottom gas channel; 30. a top gas channel.
Detailed Description
For the purpose of enhancing the understanding of the present invention, the present invention will be further described in detail with reference to the following examples and the accompanying drawings, which are only used for explaining the present invention and are not to be construed as limiting the scope of the present invention.
Example one
The embodiment relates to a nitrogen flushing and replacing system for an interlayer of a vacuum multi-layer heat-insulating low-temperature container, which is used for vacuumizing the interlayer of the vacuum multi-layer heat-insulating low-temperature container, wherein the vacuum multi-layer heat-insulating low-temperature container comprises an outer container 15 and an inner container 16, the interlayer is formed between the outer container 15 and the inner container 16, a heat insulating layer 13 is arranged on the periphery of the inner container 16, and the heat insulating layer 13 is wound on an inner container 7 after being stacked by tens of layers or even hundreds of layers of film materials.
Referring to fig. 1, the nitrogen flushing and replacing system for the vacuum multi-layer heat-insulation low-temperature container interlayer comprises a nitrogen filling device, an automatic air outlet control valve, a vacuumizing device and a control system, wherein the nitrogen filling device, the automatic air outlet control valve and the vacuumizing device are all communicated with the interlayer of the vacuum multi-layer heat-insulation low-temperature container.
The nitrogen charging device comprises a nitrogen source 1, a pressure limiting valve 3, a flow limiting valve 4, a nitrogen heater 5, a safety valve 6, a first temperature sensor 7, an air inlet control valve 8 and a pressure sensor 11, wherein the nitrogen source 1 is provided with an air supply valve 2, the air outlet end of the nitrogen source 1 is connected with the air inlet end of the nitrogen heater 5, the pressure limiting valve 3 and the flow limiting valve 4 are connected between the nitrogen source 1 and the nitrogen heater 5, the pressure limiting valve 3 can limit the nitrogen pressure to be less than or equal to 0.2MPa, the flow limiting valve 4 can adjust the opening of the valve according to the size of the evacuated space to realize the function of adjusting the gas flow, the air outlet end of the nitrogen heater 5 is connected with the air inlet end of the air inlet control valve 8, and the first temperature sensor 7 is connected between the nitrogen heater and the air inlet control valve and used; the safety valve 6 is connected between the nitrogen heater 5 and the first temperature sensor 7, the setting pressure of the safety valve is less than or equal to 0.2MPa, and when the nitrogen charging device has safety problems such as blockage, the safety valve 6 is automatically opened to release nitrogen in the nitrogen charging device; the air outlet end of the air inlet control valve 8 is communicated with the interlayer, and the pressure sensor 11 is connected between the air inlet control valve 8 and the interlayer and used for measuring the air pressure of the output nitrogen.
The first temperature sensor 7 and the pressure sensor 11 are both in communication connection with the control system 21, and the measured output temperature and pressure values of the nitrogen are both transmitted to the control system 21; the gas supply valve 2, the pressure limiting valve 3, the flow limiting valve 4, the nitrogen heater 5, the safety valve 6 and the gas inlet control valve 7 are in communication connection with a control system 21, the control system 21 controls the opening and closing states of the gas supply valve 2, the nitrogen heater 5 and the gas inlet control valve 7 through the measured values of the first temperature sensor 7 and the pressure sensor 11, and the flow limiting value of the flow limiting valve 4 is adjusted through the control system 21.
The vacuumizing device 20 is provided with a vacuumizing valve 10 for controlling the opening and closing of the vacuumizing device, the vacuumizing device is connected between the air inlet control valve 8 and the pressure sensor 11, the vacuumizing device 20 and the nitrogen charging device are further connected to the same connecting port of the interlayer, the vacuumizing valve 10 is in communication connection with the control system 21, and the control system 21 controls the opening and closing state of the vacuumizing valve 10; the vacuumizing device 20 further comprises an interlayer vacuumizing valve 12, wherein the interlayer vacuumizing valve 12 is connected between the pressure sensor 11 and the interlayer, and is in communication connection with a control system; the vacuumizing device 21 further comprises a vacuum gauge pipe 9 used for detecting the interlayer vacuum degree, the vacuum gauge pipe 9 is connected between the air inlet control valve 8 and the pressure sensor 11, the vacuum gauge pipe 9 is in communication connection with the control system 21, and the detected vacuum degree is transmitted to the control system 21 to be displayed.
And a second temperature sensor 17 for detecting the temperature of the interlayer exhaust gas is connected between the automatic air outlet control valve 18 and the interlayer, the automatic air outlet control valve 18 and the second temperature sensor 17 are both in communication connection with a control system 21, the interlayer exhaust gas temperature measured by the second temperature sensor 17 is transmitted to the control system 21 for display, and the automatic air outlet control valve 18 controls the air pressure value when the air is discharged through the control system 21.
The nitrogen flushing method based on the vacuum multilayer heat insulation low-temperature container interlayer nitrogen flushing replacement system comprises the following steps of:
s1, setting a vacuum degree threshold (the value range of the vacuum degree threshold is 10-300 Pa) by using a control system 21, starting a vacuumizing device 20 by using the control system 21, specifically, opening a vacuumizing valve 10 and an interlayer vacuumizing valve 12 to vacuumize an interlayer, and detecting the vacuum degree by using a vacuum gauge 9 in the vacuumizing process;
s2, when the vacuum degree of the interlayer is lower than the vacuum degree threshold value, the control system 21 closes the vacuum pumping device 20, namely closes the vacuum pumping valve 10, stops pumping the interlayer, sets the nitrogen temperature range (the nitrogen temperature range is 100-250 ℃) through the control system 21, simultaneously opens the air supply valve 2, the nitrogen heater 5 and the air inlet control valve 8 through the control system 21, provides nitrogen through the nitrogen source 1, and the nitrogen is heated by the nitrogen heater 5 and then is filled into the interlayer; setting a pressure threshold value (such as 110KPa micro positive pressure) of the interlayer, when the pressure of the interlayer rises to reach the pressure threshold value, further opening an automatic air outlet control valve 18 by a control system 21, continuously filling nitrogen and exhausting the nitrogen for a period of time, generally lasting for 1-12 hours, so that flowing nitrogen always exists in the interlayer, and further replacing the original gas in the interlayer, wherein the temperature of the nitrogen is controlled within the temperature range of the nitrogen, the temperature of the nitrogen filled in the interlayer is measured by a first temperature sensor 7 and transmits temperature information to the control system, the temperature of the gas discharged from the interlayer is measured by a second temperature sensor 17, and the control system 21 controls the on-off of a nitrogen heater 5 according to the temperatures measured by the first temperature sensor 7 and the second temperature sensor 17, so as to control the temperature of the nitrogen in the; in the process, different opening degrees of the flow limiting valve 4 are adjusted at different stages, and when the interlayer pressure of the nitrogen charging stage does not reach a pressure threshold value, the flow limiting valve 4 is opened to a large opening degree to maintain a large flow; and in the stage of synchronously filling nitrogen and discharging nitrogen, the opening degree of the flow limiting valve 4 needs to be reduced, and the small flow is maintained.
S3, the control system 21 closes the automatic air outlet control valve 18, closes the air supply valve 2 and the air inlet control valve 8, and simultaneously, the control system 21 starts the vacuumizing device 20 to pump out nitrogen in the interlayer;
s4, setting the nitrogen flushing replacement times (the nitrogen flushing replacement times are generally 4-15 times), repeating the steps S2 and S3 until the nitrogen flushing replacement times, and completely pumping out the nitrogen until the original gas in the interlayer is completely removed.
Example two:
referring to fig. 2, the nitrogen flushing and replacing system for the vacuum multi-layer heat-insulating low-temperature container interlayer according to the present embodiment is added with an inner container heating device 19 and an outer container heating device 14 compared with the first embodiment.
In the embodiment, the structures of the nitrogen charging device, the automatic air outlet control valve 18, the vacuumizing device 20 and the control system 21 and the connection relation with the vacuum multi-layer heat-insulation low-temperature container are the same as those of the embodiment I, and the description of the embodiment is omitted; the inner container heating device 19 can provide circulating clean air or nitrogen at room temperature to 300 ℃, and is controlled by the control system 21, so that the circulating stable heat supply working condition can be realized, and the inner container is heated; the outer container heating device 14 can accommodate an evacuated container, can provide circulating clean air at room temperature to 250 ℃, is controlled by a control system, can realize circulating stable heat supply working conditions, and further heats the outer container.
Referring to fig. 3, the inner container heating device 19 includes a first circulating fan 22, a first gas heater 23, an inner container inlet valve 24 and an inner container outlet valve 25, and the inlet end and the outlet end of the inner container heating device 19 are respectively connected to the inner container inlet and outlet.
Referring to fig. 4, the outer container heating apparatus 14 comprises a drying room 26, a second circulating fan 27, and a second air heater 28, wherein the drying room 26 can accommodate the evacuated container, a bottom air passage 29 is provided inside the drying room 26 near the bottom plate, a top air passage 30 is provided inside the drying room 26 near the top plate, the air outlet ends of the second circulating fan 27 and the second air heater 28 are connected to the bottom air passage 29, and the air inlet ends of the second circulating fan 27 and the second air heater 28 are connected to the top air passage 30.
The step of flushing the interlayer by adopting the nitrogen flushing and replacing system for the vacuum multilayer heat-insulating low-temperature container interlayer related to the embodiment comprises the following steps:
s0. setting an inner circulation heating temperature range (the inner circulation heating temperature range is 100-300 ℃) and an outer circulation heating temperature range (the outer circulation heating temperature range is 100-200 ℃), starting the inner container heating device 19 to circularly heat the inner container, and controlling the temperature of the inner circulation gas in the inner circulation heating temperature range; the outer container heating device 14 is opened to circularly heat the outer container, and the temperature of the outer circulating gas is controlled within the outer circulating heating temperature range.
S1, setting an upper limit value of an internal circulation heating temperature (the upper limit value of the internal circulation heating temperature is 300 ℃), a lower limit value of the internal circulation heating (the lower limit value of the internal circulation heating is 100 ℃), an upper limit value of an external circulation heating temperature (the upper limit value of the external circulation heating temperature is 200 ℃), a lower limit value of the external circulation heating (the lower limit value of the external circulation heating is 100 ℃) and a vacuum degree threshold value (the value range of the vacuum degree threshold value is 10 Pa-300 Pa), starting a vacuumizing device 20 by a control system 21 when the outlet temperature of an inner container reaches the lower limit value of the internal circulation heating, specifically, opening a vacuumizing valve 10 and an interlayer vacuumizing valve 12 to evacuate an interlayer, detecting the vacuum degree by a vacuum gauge tube 9 in the vacuumizing device 20, stopping heating of an inner baking gas heater when the temperature of an exhaust port reaches the upper limit value of the internal circulation heating temperature, when the temperature of the gas discharged from the gas outlet of the inner container is lower than the lower limit value of the internal circulation heating, the internal drying gas heater starts heating so as to maintain the temperature of the gas discharged between the lower limit value of the internal circulation heating and the upper limit value of the internal circulation heating temperature, when the temperature of the gas in the drying room reaches the upper limit value of the external circulation heating temperature, the external drying gas heater stops heating, and when the temperature of the gas in the drying room is lower than the lower limit value of the external circulation heating, the external drying gas heater starts heating so as to maintain the temperature of the gas in the drying room between the lower limit value of the external circulation heating and the upper limit value of the external circulation heating temperature;
s2, setting a nitrogen temperature range (the nitrogen temperature range is 100-250 ℃) by using a control system, when the vacuum degree of the interlayer reaches a vacuum degree threshold value, closing the vacuumizing device 20 by using the control system 21, namely closing the vacuumizing valve 10, stopping vacuumizing the interlayer, simultaneously opening the air supply valve 2, the nitrogen heater 5 and the air inlet control valve 8 by using the control system 21, providing nitrogen by using the nitrogen source 1, and heating the nitrogen by using the nitrogen heater 5 and then filling the nitrogen into the interlayer; setting a pressure threshold value (such as 110KPa micro positive pressure) of the interlayer, when the pressure of the interlayer rises to reach the pressure threshold value, further opening an automatic air outlet control valve 18 by a control system 21, continuously filling nitrogen and exhausting the nitrogen for a period of time, generally 1-12 hours, so that flowing nitrogen always exists in the interlayer, and further replacing the original gas in the interlayer, wherein the temperature of the nitrogen is controlled within the temperature range of the nitrogen, the temperature of the nitrogen filled in the interlayer is measured by a first temperature sensor 7 and transmits temperature information to the control system, the temperature of the gas discharged from the interlayer is measured by a second temperature sensor 17, and the control system 21 controls the on-off of a nitrogen heater 5 according to the temperatures measured by the first temperature sensor 7 and the second temperature sensor 17, so as to control the temperature of the nitrogen in the interlayer; in the process, different opening degrees of the flow limiting valve 4 are adjusted at different stages, and when the interlayer pressure of the nitrogen charging stage does not reach a pressure threshold value, the flow limiting valve 4 is opened to a large opening degree to maintain a large flow; and in the stage of synchronously filling nitrogen and discharging nitrogen, the opening degree of the flow limiting valve 4 needs to be reduced, and the small flow is maintained.
S3, the control system 21 closes the automatic air outlet control valve 18, closes the air supply valve 2 and the air inlet control valve 8, and simultaneously, the control system 21 starts the vacuumizing device 20 to pump out nitrogen in the interlayer;
s4, setting the nitrogen flushing replacement times (the nitrogen flushing replacement times are generally 4-15 times), repeating the steps S2 and S3 until the nitrogen flushing replacement times, and completely pumping out the nitrogen until the original gas in the interlayer is completely removed.
Effects of the embodiment
From 2002 to 2019, a company in Lanzhou paired 36 20m stations3～32m3A novel submarine is implemented by using a low-temperature container. The effective volume of the interlayer of the vacuum multi-layer heat-insulation low-temperature container is 6-8 m3(ii) a The vacuum degree of the interlayer sealing is 1.5 multiplied by 10-4Pa～3.3×10-3Pa, the realized interlayer low-temperature pressure is 6 multiplied by 10-5Pa～3×10-4Pa. After 4-14 years, the low-temperature pressure of the interlayer is repeatedly measured without obvious change, as shown in figure 5.
Effect of embodiment two
Evacuation effect demonstration was carried out in southern Tong company in 11 months in 2017: 1 LNG container of 40 feet and vacuum interlayer effective space of 8.5m3The two parties are subjected to combined test, the effective evacuation time is 6 days, and the vacuum degree of a sealing port is 3.1E-3Pa when evacuation is finished, which is shown in table 1; after liquid nitrogen is added for thermal equilibrium, the cold state vacuum degree is 1.8E-4Pa, which is shown in Table 2; after 2 years, both parties perform interlayer vacuum degree tracking test in 2019 and 10 months, and the data are shown in table 3; the data show the 2 year interlayer vacuumWith a drop of 2E-4Pa, the interlayer vacuum can be expected to remain at E-3 level after 20 years.
Table 1: seal vacuum degree test meter
Table 2: initial cold state vacuum degree test meter
Table 3: cold state vacuum degree test meter after 2 years
Effect example III
No-Sn company, 1 LNG tank with 40 feet and vacuum interlayer effective space of 8.5m, implemented 2 months in 20193. The total time of effective replacement and evacuation is 6 days, the air outlet temperature of the inner tank is 52 ℃ when the inner tank is sealed, and the interlayer vacuum degree is 9.5 multiplied by 10-4Pa (directly measured by being arranged on a sandwich gauge pipe), the existing national standard NB/T47059-2017 requires that the sealing vacuum degree index of the products of the same type is 8 multiplied by 10 at the room temperature-2Pa, excellent sealing data, and is in no way exclusive in the industry.
Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
Claims (10)
1. The utility model provides a vacuum multilayer thermal insulation cryogenic container intermediate layer nitrogen gas washes replacement system which characterized in that: the device comprises a nitrogen charging device, an automatic air outlet control valve, a vacuumizing device and a control system; the nitrogen charging device, the automatic air outlet control valve and the vacuumizing device are all communicated with an interlayer of the vacuum multi-layer heat-insulation low-temperature container; the nitrogen charging device comprises a nitrogen source, a nitrogen heater and an air inlet control valve, wherein the nitrogen source is provided with an air supply valve, the air outlet end of the nitrogen source is connected with the air inlet end of the nitrogen heater, the air outlet end of the nitrogen heater is connected with the air inlet end of the air inlet control valve, and the air outlet end of the air inlet control valve is communicated with the interlayer; the air supply valve, the nitrogen heater, the air inlet control valve, the vacuumizing device and the automatic air outlet control valve are all in communication connection with the control system.
2. The nitrogen flushing and replacing system for the vacuum multilayer heat-insulating cryogenic container interlayer of claim 1 is characterized in that: the nitrogen charging device further comprises a first temperature sensor and a pressure sensor, the first temperature sensor is connected between the nitrogen heater and the air inlet control valve, the pressure sensor is connected between the air inlet control valve and the interlayer, and the first temperature sensor and the pressure sensor are both in communication connection with the control system.
3. The nitrogen flushing and replacing system for the vacuum multilayer heat-insulating cryogenic container interlayer as claimed in claim 2, wherein: the nitrogen charging device also comprises a pressure limiting valve and a flow limiting valve, wherein the pressure limiting valve and the flow limiting valve are sequentially connected between the gas supply valve and the nitrogen heater, and the flow limiting valve is in communication connection with the control system.
4. The nitrogen flushing and replacing system for the vacuum multilayer heat-insulating cryogenic container interlayer as claimed in claim 2, wherein: the nitrogen charging device further comprises a safety valve, and the safety valve is connected between the nitrogen heater and the first temperature sensor.
5. The nitrogen flushing and replacing system for the vacuum multilayer heat-insulating cryogenic container interlayer as claimed in claim 2, wherein: the vacuumizing device is provided with a vacuumizing valve for controlling the opening and closing of the vacuumizing device, the vacuumizing device is connected between the air inlet control valve and the pressure sensor, the vacuumizing device and the nitrogen filling device are further connected to the same connecting port of the interlayer, and the vacuumizing valve is in communication connection with the control system.
6. The nitrogen flushing and replacing system for the vacuum multilayer heat-insulating cryogenic container interlayer of claim 5 is characterized in that: the vacuum pumping device further comprises an interlayer evacuating valve, and the interlayer evacuating valve is connected between the pressure sensor and the interlayer.
7. The nitrogen flushing and replacing system for the vacuum multilayer heat-insulating cryogenic container interlayer of claim 5 is characterized in that: the vacuum pumping device further comprises a vacuum gauge pipe used for detecting the vacuum degree of the interlayer, the vacuum gauge pipe is connected between the air inlet control valve and the pressure sensor, and the vacuum gauge pipe is in communication connection with the control system.
8. The nitrogen flushing and replacing system for the vacuum multilayer heat-insulating cryogenic container interlayer of claim 1 is characterized in that: and a second temperature sensor for detecting the temperature of the gas discharged from the interlayer is also connected between the automatic gas outlet control valve and the interlayer, and the second temperature sensor is in communication connection with a control system.
9. A nitrogen flushing method based on the vacuum multilayer heat insulation cryogenic container interlayer nitrogen flushing replacement system of claim 1, characterized in that: which comprises the following steps:
s1, setting a vacuum degree threshold value, and starting a vacuumizing device by a control system to vacuumize an interlayer;
s2, when the vacuum degree of the interlayer is lower than a vacuum degree threshold value, the control system closes the vacuumizing device, vacuumizing of the interlayer is stopped, meanwhile, the control system opens the air supply valve, the nitrogen heater and the air inlet control valve, the nitrogen source provides nitrogen, the nitrogen is heated and then filled into the interlayer, when the pressure of the interlayer reaches 110KPa, the control system further opens the automatic air outlet control valve, the nitrogen is continuously filled and exhausted, and then original gas in the interlayer is replaced;
s3, the control system closes the automatic air outlet control valve, closes the air supply valve and the air inlet control valve, and simultaneously starts the vacuumizing device to pump out nitrogen in the interlayer;
s4, repeating the steps S2 and S3 for a plurality of times until the original gas in the interlayer is removed completely and the nitrogen is completely pumped out.
10. The nitrogen flushing and replacing method based on the vacuum multilayer heat-insulation cryogenic container interlayer nitrogen flushing and replacing system according to claim 9, characterized in that: the step S2 further includes setting a nitrogen temperature range, controlling the nitrogen temperature within the nitrogen temperature range, measuring the temperature of the nitrogen filled into the interlayer by the first temperature sensor, transmitting the temperature information to the control system, and controlling the nitrogen heater to be turned on or off by the control system according to the temperature measured by the first temperature sensor.
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