CN111810834B - Vacuum obtaining system and method for interlayer of vacuum multilayer thermal insulation cryogenic container - Google Patents

Abstract

The invention discloses a vacuum obtaining system and a method for a vacuum multilayer heat insulation low-temperature container interlayer, wherein the vacuum obtaining system comprises the following steps: the inner container heating and cooling circulating system is connected with the inner container and is used for circularly heating or cooling the inner container; the outer container heating and cooling circulation system is used for circularly heating or cooling the outer container; the micro-positive pressure nitrogen flushing displacement system is connected with the interlayer and is used for displacing gas in the interlayer; the vacuumizing unit is connected with the interlayer and is used for vacuumizing the interlayer; the control system is used for controlling the inner container heating and cooling circulation system, the outer container heating and cooling circulation system, the micro-positive pressure nitrogen flushing and replacing system and the vacuumizing unit. By adopting the technical scheme, the invention has good interlayer gas replacement effect, is beneficial to improving the pumping efficiency of the replaced nitrogen and has long-lasting high-vacuum life.

Description

Vacuum obtaining system and method for interlayer of vacuum multilayer thermal insulation cryogenic container

Technical Field

The present invention belongs to the technical field of vacuuming the interlayer of a low-temperature vacuum insulated container, and in particular relates to a vacuum obtaining system and method for the interlayer of a vacuum multi-layer insulated low-temperature container, which can completely replace interlayer moisture and other non-condensable gas molecules and significantly improve the vacuum degree.

Background technique

As the application scope of refrigerated liquefied gas becomes wider and wider, the requirements for thermal insulation performance of equipment for storing and transporting refrigerated liquefied gas are also getting higher and higher, especially for containers for storing and transporting deep-cold liquids such as liquid oxygen, liquid nitrogen, liquid hydrogen, liquid argon, LNG, etc. Generally, only high-vacuum multi-layer insulation structure can meet the thermal insulation requirements. This type of container has extremely high requirements for interlayer vacuum. The cold working vacuum degree of the interlayer needs to be better than 0.03Pa (absolute pressure) during the entire interlayer vacuum life cycle of the container (the national standard requires 5 years). It can be seen that interlayer vacuum is one of the important indicators that affect the thermal insulation performance of low-temperature containers, and it is an important technical link in the manufacturing and maintenance of vacuum multi-layer insulation containers.

Under the condition of structural solidification, interlayer vacuum is the only indicator that affects the insulation performance of vacuum multilayer insulated cryogenic containers. The traditional interlayer vacuuming process has the defects of high energy consumption, long time consumption, high labor consumption, and short vacuum life; in addition, the multilayer insulated container is coated with multiple layers of insulation materials on the inner container. The insulation material is composed of dozens or even hundreds of layers of film materials stacked and wound on the inner container. It has the characteristics of low thermal conductivity, many layers, large surface area, and close arrangement. These characteristics lead to the multilayer insulation material having problems such as poor heat transfer, large amount of adsorbed gas, and difficulty in desorption of adsorbed gas.

In response to the above problems, patent CN101021209A discloses a vacuum pumping method and device, including: a first gas conveying device having an air outlet; a first gas heater, an inlet of which is connected to the air outlet of the first gas conveying device, and an outlet of which is connected to the air inlet of the inner tube; a vacuum pumping unit, which is connected to the interlayer; a second gas conveying device having an air outlet; a second gas heater, an inlet of which is connected to the air outlet of the second gas conveying device, and an outlet of which is connected to the interlayer. The solution involved in the above patent has the following problems: only the inner cylinder is heated, and it is difficult for heat to penetrate the insulating material covering the inner container, the middle and outer insulating materials cannot be effectively heated, the interlayer replacement heat efficiency is low, and the replacement is not thorough; when the interlayer is replaced with nitrogen, the nitrogen is sealed and retained, the thermal insulation effect is poor, the replacement effect is not ideal, and the replacement efficiency is low; the use of liquid nitrogen cold trap requires monitoring and adding liquid nitrogen at any time, which increases the difficulty of operation, reduces the flow conductance of the vacuum pipeline, and affects the vacuum effect; the moisture in the insulating material in the interlayer is difficult to completely remove, and the remaining moisture will continue to release water vapor after vacuum sealing, resulting in a gradual decrease in the vacuum degree of the interlayer, shortening the vacuum life and reducing the insulation performance.

Another more advanced technical solution is the vacuum system and method for a large-volume low-temperature insulated container disclosed in patent number CN102913749A, which includes an air supply device, a vacuum device and a heating device; the heating device includes an outer tank heating device and an inner tank heating device; the insulated container to be vacuumed includes 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 on the outside of the outer tank of the insulated container to be vacuumed; the inner tank heating device is arranged on the inside of the inner tank of the insulated container to be vacuumed; the air supply device is connected to the inner tank and the interlayer of the insulated container to be vacuumed through pipelines; the vacuum device is connected to the inner tank and the interlayer of the insulated container to be vacuumed through pipelines. The heating device of this technology includes an outer tank heating device and an inner tank heating device, the insulation materials of the middle and outer interlayers can be effectively heated, the interlayer has high heat displacement efficiency, and can improve the displacement effect to a certain extent. However, the interlayer replacement still uses a closed inflation method, which is prone to overcharging or undercharging during actual operation, and the replacement effect is still not ideal; in addition, the external heating uses an electric heating plate, which has high energy consumption and high cost for mass production of large-scale container production lines, and is prone to uneven heating.

Summary of the invention

The purpose of the present invention is to address the problem of poor vacuum extraction effect of the interlayer of a vacuum multi-layer insulated cryogenic container in the prior art, and to propose a vacuum obtaining system and method for the interlayer of a vacuum multi-layer insulated cryogenic container, which can completely replace the moisture and other non-condensable gas molecules in the interlayer and significantly improve the vacuum degree.

To achieve the above object, the present invention adopts the following technical solutions:

The present invention relates to a vacuum obtaining system for an interlayer of a vacuum multi-layer thermally insulated cryogenic container, wherein the vacuum multi-layer thermally insulated cryogenic container comprises an outer container and an inner container arranged inside the outer container, and the interlayer is formed between the outer container and the inner container. The vacuum obtaining system comprises:

An inner container heating and cooling circulation system connected to the inner container, used for cyclically heating or cooling the inner container;

The outer container heating and cooling circulation system is used for cyclic heating or cooling of the outer container;

A slightly positive pressure nitrogen flushing and replacement system connected to the interlayer is used to replace the gas in the interlayer;

A vacuum unit connected to the interlayer is used to evacuate the interlayer;

The control system is used to control the inner container heating and cooling circulation system, the outer container heating and cooling circulation system, the slightly positive pressure nitrogen flushing and replacement system and the vacuum pumping unit.

Preferably, the container heating and cooling circulation system includes a first circulation fan, a first gas heater and a container cooling air inlet valve, the air outlet end of the first circulation fan is connected to the air inlet end of the first gas heater, the air outlet end of the first gas heater and the air inlet end of the first circulation fan are both connected to the inner container of the vacuum multi-layer insulated low-temperature container, the inner container cooling exhaust valve is also connected to the air inlet end of the first circulation fan, an inner container air inlet valve is also connected between the first gas heater and the inner container, an inner container cooling exhaust valve and an inner container air outlet valve are also connected in sequence between the first circulation fan and the inner container, and the inner container cooling air inlet valve is equipped with a filter; the first circulation fan, the first gas heater, the inner container air inlet valve, the cooling exhaust valve, the inner container air outlet valve and the inner container cooling air inlet valve are all communicatively connected to the control system.

Preferably, the inner container heating and cooling circulation system also includes an inner container air intake temperature sensor and an inner container air outlet temperature sensor, the inner container air intake temperature sensor is connected between the inner container air intake valve and the inner container, the inner container air outlet temperature sensor is connected between the inner container and the inner container cooling exhaust valve, and the inner container air intake temperature sensor and the inner container air outlet temperature sensor are both communicatively connected to the control system.

Preferably, the outer container heating and cooling circulation system comprises a drying room, a second circulation fan, a second gas heater, a drying room cooling exhaust fan and a drying room cooling air inlet valve; a drying room bottom gas channel is provided near the bottom of the drying room, and a drying room top gas channel is provided near the top, and the drying room cooling exhaust fan and the drying room cooling air inlet valve are both fixed on the drying room and communicated with the inside of the drying room; the air outlet end of the second circulation fan is connected to the air inlet end of the second gas heater, the air outlet end of the second gas heater is connected to the drying room bottom gas channel, and the air inlet end of the second circulation fan is connected to the drying room top gas channel; the second circulation fan, the second gas heater, the drying room cooling exhaust fan and the drying room cooling air inlet valve are all communicatively connected to the control system.

Preferably, the outer container heating and cooling circulation system also includes a drying room inlet air temperature sensor, a drying room outlet air temperature sensor and a drying room temperature sensor; the drying room inlet air temperature sensor is connected between the second gas heater and the gas channel at the bottom of the drying room, the drying room outlet air temperature sensor is connected between the second circulation fan and the gas channel at the top of the drying room, and the drying room temperature sensor is arranged inside the drying room; the drying room inlet air temperature sensor, the drying room outlet air temperature sensor and the drying room temperature sensor are all communicatively connected to the control system.

Preferably, a high vacuum baffle valve, an integrated measuring chamber and an interlayer evacuation valve are connected in sequence between the vacuum pumping unit and the interlayer, a balancing valve and a vacuum sensor are provided on the integrated measuring chamber, and the high vacuum baffle valve, the interlayer evacuation valve, the balancing valve and the vacuum sensor are all communicatively connected with the control system.

Preferably, the micro-positive pressure nitrogen flushing and replacement system includes a nitrogen source, a third gas heater, an automatic gas outlet control valve and a pressure sensor; the gas inlet end of the third gas heater is connected to the nitrogen source, the gas outlet end of the third gas heater is connected to the integrated measuring chamber, an interlayer gas inlet control valve is connected between the third gas heater and the integrated measuring chamber, the automatic gas outlet control valve is connected to the outer container interlayer explosion-proof device port through a pipeline, and the pressure sensor is connected to the integrated measuring chamber; the third gas heater, the interlayer gas inlet control valve, the pressure sensor and the automatic gas outlet control valve are all connected to the control system for communication.

Preferably, the micro-positive pressure nitrogen flushing and replacement system also includes a nitrogen pressure sensor, an interlayer inlet temperature sensor, an interlayer outlet temperature sensor and an interlayer vacuum gauge for detecting the vacuum degree of the interlayer; the nitrogen pressure sensor is connected between the nitrogen source and the third gas heater, the interlayer inlet temperature sensor is connected between the third gas heater and the integrated measuring chamber, the interlayer outlet temperature sensor is connected between the interlayer and the automatic outlet control valve, and the interlayer vacuum gauge is connected to the interlayer; the nitrogen pressure sensor, interlayer inlet temperature sensor, interlayer vacuum gauge and interlayer outlet temperature sensor are all communicatively connected to the control system.

The present invention also relates to a method for obtaining vacuum by using the interlayer of the vacuum multi-layer thermal insulation cryogenic container, which comprises the following steps:

S1. The inner container is heated and cooled by a circulation system;

S2. Using an outer container heating and cooling circulation system to circulate heating of the outer container;

S3. Set the first vacuum threshold of the interlayer, start the vacuum unit to evacuate the interlayer until the vacuum of the interlayer reaches the first vacuum threshold;

S4. When the vacuum degree of the interlayer reaches the first vacuum degree threshold, a slightly positive pressure nitrogen flushing and replacement system is used to replace the gas in the interlayer. During the replacement process, the interlayer pressure is controlled at ~110KPa;

S5. Turn off the slightly positive pressure nitrogen flushing and replacement system, and start the vacuum unit again to evacuate the interlayer;

S6. Repeat S4 and S5 several times;

S7. Stop the outer container heating and cooling circulation system and the vacuum unit, and fill the interlayer with adsorbent;

S8. Start the outer container heating and cooling circulation system again to circulate heating of the outer container;

S9. Start the vacuum unit again to continue evacuating the interlayer;

S10. After reaching a predetermined vacuum degree, the inner container is cooled by the inner container heating and cooling circulation system;

S11. Using an outer container heating and cooling circulation system to cool the outer container;

S12. When the temperature of the inner container and the air temperature around the outer container return to normal temperature, stop the vacuum unit.

Preferably, in S1, the temperature of the gas output by the inner container heating and cooling circulation system is controlled between 120°C and 300°C; in S2, the temperature of the gas output by the outer container heating and cooling circulation system is controlled between 100°C and 250°C; in step S3, a control system is used to set the lower limit value and upper limit value of the inner container temperature, as well as the lower limit value and upper limit value of the drying room temperature. When the temperature of the gas discharged from the inner container heating and cooling circulation system reaches the lower limit value of the inner container temperature, the vacuum unit is started to evacuate the interlayer. During the evacuation process, the inner container heating and cooling circulation system is used to control the temperature of the inner container between the lower limit value and the upper limit value of the inner container temperature, and the outer container heating and cooling circulation system is used to control the temperature of the outer container periphery between the lower limit value and the upper limit value of the drying room temperature; in S4, the duration of each time the micro-positive pressure nitrogen flushing and replacement system is used to replace the gas in the interlayer is 1 to 12 hours.

Compared with the prior art, the technical solution provided by the present invention has the following technical effects:

1. The present invention uses a flowing nitrogen flushing and replacement system in conjunction with a vacuum pumping unit to replace the interlayer gas. The nitrogen flushing and replacement system includes a nitrogen source, a third gas heater and an automatic gas outlet control valve. During the replacement process, heated nitrogen is filled in while the replacement gas is released, and the interlayer pressure is controlled at 110KPa to 130KPa. When evacuating, a negative pressure is formed between the interlayer and the insulation material, so that the vaporized moisture and non-condensable gas of the deep insulation material can be desorbed, and reach the interlayer space after passing through the surface insulation material. The moisture and non-condensable gas components desorbed from the interlayer material are immediately entrained and carried out of the interlayer space by the flowing nitrogen after being desorbed to the interlayer space. Overcharging or undercharging will not occur, and the replacement effect is thorough.

2. The vacuum obtaining system of the interlayer of the vacuum multi-layer insulated low-temperature container involved in the present invention is provided with an inner container heating and cooling circulation system and an outer container heating and cooling circulation system, which respectively heat the inner container and the outer container synchronously and continuously, and the heat can evenly penetrate the entire insulation material, so that the temperature of each layer of insulation material is higher than 100°C, and all the moisture adsorbed by the insulation material can be gasified and desorbed. When the gas in the interlayer is further replaced by a micro-positive pressure nitrogen flushing and replacement system, the moisture and other gas molecules in the container interlayer can be completely replaced, and it is helpful to efficiently extract the replacement nitrogen from the interlayer, so that the interlayer obtains a long-lasting high vacuum life; and, compared with the traditional method of heating the outer container by an electric heating plate, the outer container is heated by the outer container heating and cooling circulation system, which has the advantages of low energy consumption, low cost, and uniform heating.

3. The present invention does not need to set up a liquid nitrogen cold trap between the vacuum pumping unit and the interlayer, which increases the flow conductance of the vacuum pumping pipeline, improves the vacuum pumping efficiency, simplifies the operation, reduces the workload, saves costs, and is green and energy-saving; after the high-temperature vacuum pumping is completed, the inner container heating and cooling circulation system and the outer container heating and cooling circulation system are used to use forced cooling measures for the inner container and the outer container, shortening the time that the product occupies the drying room, saving costs and improving efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a vacuum obtaining system for an interlayer of a vacuum multi-layer thermally insulated cryogenic container according to the present invention;

FIG2 is a schematic diagram of a container heating and cooling circulation system according to the present invention;

FIG3 is a schematic diagram of an outer container heating and cooling circulation system of the present invention;

FIG4 is a schematic diagram of a combination of a slightly positive pressure nitrogen flushing and replacement system and a vacuum pumping unit according to the present invention;

Figure 5 is a diagram showing the change in low-temperature pressure of the interlayer after repeated measurement.

Among them: 1. Drying room outlet temperature sensor; 2. Drying room cooling exhaust fan; 3. Drying room; 4. Drying room top gas channel; 5. Outer container; 6. Insulation layer; 7. Inner container; 8. Inner container inlet temperature sensor; 9. Drying room cooling inlet valve; 10. Inner container outlet temperature sensor; 11. Inner container inlet valve; 12. Inner container cooling exhaust valve; 13. First gas heater; 14. Inner container outlet valve; 15. Filter; 16. Inner container cooling inlet valve; 17. First circulation fan; 18. Control system; 19. Pressure sensor; 20. High vacuum Baffle valve; 21. Vacuum pumping unit; 22. Integrated measuring chamber; 23. Interlayer air inlet control valve; 24. Interlayer air inlet temperature sensor; 25. Balance valve; 26. Third gas heater; 27. Nitrogen pressure sensor; 28. Vacuum sensor; 29. Nitrogen source; 30. Interlayer evacuation valve; 31. Interlayer vacuum gauge; 32. Gas channel at the bottom of the drying room; 33. Drying room air inlet temperature sensor; 34. Second gas heater; 35. Second circulation fan; 36. Drying room temperature sensor; 37. Automatic air outlet control valve; 38. Interlayer air outlet temperature sensor.

Detailed ways

In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with embodiments and drawings. The embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

Referring to FIG1 , the present invention relates to a vacuum obtaining system for the interlayer of a vacuum multi-layer thermally insulated cryogenic container, which is used for evacuating the interlayer of the vacuum multi-layer thermally insulated cryogenic container. The vacuum multi-layer thermally insulated cryogenic container comprises an outer container 5 and an inner container 7. An interlayer is provided between the outer container 5 and the inner container 7. An insulating layer 6 is provided on the periphery of the inner container 7. The insulating layer 6 is composed of dozens or even hundreds of layers of thin film materials stacked and then wound on the inner container 7. The insulating layer 6 has the characteristics of a small thermal conductivity coefficient and a large number of layers, so that the thermal insulation performance of the vacuum multi-layer thermally insulated cryogenic container is better.

Referring to FIG. 1 , the vacuum obtaining system includes: an inner container heating and cooling circulation system connected to the inner container of the vacuum multi-layer insulated cryogenic container, which is used to cyclically heat or cool the inner container of the vacuum multi-layer insulated cryogenic container; an outer container heating and cooling circulation system, which is used to place the vacuum multi-layer insulated cryogenic container therein and cyclically heat or cool the outer container of the vacuum multi-layer insulated cryogenic container; a slightly positive pressure nitrogen flushing and replacement system connected to the interlayer, which is used to replace the gas in the interlayer; a vacuum pumping unit connected to the interlayer, which is used to evacuate the interlayer; a control system, which is used to control the inner container heating and cooling circulation system, the outer container heating and cooling circulation system, the slightly positive pressure nitrogen flushing and replacement system and the vacuum pumping unit.

Referring to Figures 1 and 2, the inner container heating and cooling circulation system includes a first circulation fan 17, a first gas heater 13 and an inner container cooling air inlet valve 16, the outlet end of the first circulation fan 17 is connected to the air inlet end of the first gas heater 13, the outlet end of the first gas heater 13 and the air inlet end of the first circulation fan 17 are both connected to the inner container 7 of the vacuum multi-layer insulated low-temperature container, the inner container cooling exhaust valve 15 is also connected to the air inlet end of the first circulation fan 17, an inner container air inlet valve 11 for controlling the air inlet of the inner container heating and cooling circulation system is also connected between the first circulation fan 17 and the inner container 7, and an inner container cooling exhaust valve 15 is also connected in sequence between the first circulation fan 17 and the inner container 7. 2 and an inner container outlet valve 14 for controlling the outlet of the inner container heating and cooling circulation system, the inner container cooling air inlet valve 16 is equipped with a filter 15 for filtering the inner container heating and cooling circulation system gas, and the inner container cooling exhaust valve 12 is used to discharge the hot gas in the inner container 7 during the cooling process of the inner container 7; the first circulation fan 17, the first gas heater 13, the inner container air inlet valve 11, the cooling exhaust valve 12, the inner container air outlet valve 12 and the inner container cooling air inlet valve 16 are all connected to the control system 18 for communication and driven by the control system 18. The gas transported by the above-mentioned first circulation fan 17 is nitrogen or dry air, and the first gas heater 13 can be heated by natural gas energy or electric energy.

During the circulation heating process, the inner container air inlet valve 11 and the inner container air outlet valve 14 are opened, and the inner container air outlet valve 12 is closed. The gas is recovered after heating the inner container 7 and is reused through the first circulation fan 17 and the first gas heater 13, thereby making full use of the residual temperature of the gas and reducing the energy consumption of heating the gas. During the cooling process of the inner container, the first gas heater 13 and the inner container air outlet valve 14 are closed, and the inner container cooling air inlet valve 16, the inner container air inlet valve 11 and the inner container air outlet valve 12 are opened, and normal temperature gas is input into the inner container and the high temperature gas in the inner container 7 is discharged from the inner container air outlet valve 12.

Referring to Figures 1 and 2, the inner container heating and cooling circulation system further includes an inner container inlet temperature sensor 8 and an inner container outlet temperature sensor 10. The inner container inlet temperature sensor 8 is connected between the inner container inlet valve 11 and the inner container 7, and is used to measure the temperature of the input gas of the inner container heating and cooling circulation system. The inner container outlet temperature sensor 10 is connected between the inner container 7 and the inner container cooling exhaust valve 12, and is used to measure the outlet temperature of the inner container heating and cooling circulation system. The inner container inlet temperature sensor 8 and the inner container outlet temperature sensor 10 are both connected to the control system for communication, and the temperature information is transmitted to the control system for display. During the cycle heating process, the control system turns on or off the first gas heater 13 according to the temperature measured by the inner container inlet temperature sensor 8 and the inner container outlet temperature sensor 10; during the cooling process, the container outlet temperature sensor 10 detects the temperature of the exhaust gas, and stops cooling when the detected temperature is the same as the room temperature.

1 and 3, the outer container heating and cooling circulation system includes a drying room 3, a second circulation fan 35, a second gas heater 34, a drying room cooling exhaust fan 2 and a drying room cooling air inlet valve 9; a drying room bottom gas channel 32 is provided near the bottom of the drying room 3, and a drying room top gas channel 4 is provided near the top; the drying room cooling exhaust fan 2 and the drying room cooling air inlet valve 9 are both fixed on the drying room 3 and communicated with the inside of the drying room 3; the air outlet end of the second circulation fan 35 is connected to the air inlet end of the second gas heater 34, the air outlet end of the second gas heater 34 is connected to the drying room bottom gas channel 32, and the air inlet end of the second circulation fan 35 is connected to the drying room top gas channel 4; the second circulation fan 35, the second gas heater 34, the drying room cooling exhaust fan 2 and the drying room cooling air inlet valve 9 are all connected to the control system 18 in communication and are driven to switch by the control system 18; the gas transported by the second circulation fan 35 is dry air, and the second gas heater 34 preferentially uses natural gas energy for heating.

During the process of circulating heating the outer container 5, the drying room cooling exhaust fan 2 and the drying room cooling air inlet valve 9 are closed, the second circulating fan 35 and the second gas heater 34 are opened, the second circulating fan 35 absorbs the air in the drying room 3, heats the air and re-inputs it into the drying room 3, heats the outer container 5 in the drying room 3, and recycles the air in the drying room 3, making full use of the residual heat of the air and reducing the energy consumption of the second gas heater 34; when cooling the outer container 5, the drying room cooling exhaust fan 2 and the drying room cooling air inlet valve 9 are opened, the second circulating fan 35 and the second gas heater 34 are closed, the drying room cooling air inlet valve 9 continuously inputs normal temperature air into the drying room 3 from outside the drying room, and the drying room cooling exhaust fan 2 extracts the original hot air in the drying room 3.

1 and 3, the outer container heating and cooling circulation system also includes a drying room inlet temperature sensor 33, a drying room outlet temperature sensor 1 and a drying room temperature sensor 36; the drying room inlet temperature sensor 33 is connected between the second gas heater 34 and the gas channel 32 at the bottom of the drying room, and is used to detect the temperature of the air input to the drying room; the drying room outlet temperature sensor 1 is connected between the second circulation fan 35 and the gas channel 4 at the top of the drying room, and is used to detect the air temperature output from the drying room 3; the drying room temperature sensor 36 is arranged inside the drying room, and is used to detect the temperature inside the drying room 3. The drying room inlet temperature sensor 33, the drying room outlet temperature sensor 1 and the drying room temperature sensor 36 are all connected to the control system 18 for communication, and all transmit the detected temperature to the control system 18 for display. The control system 18 switches the second gas heater 34 according to the detected temperature.

Referring to Figures 1 and 4, a high vacuum baffle valve 20, an integrated measuring chamber 22 and an interlayer evacuation valve 30 are connected in sequence between the vacuum pumping unit 21 and the interlayer, and a balancing valve 25 and a vacuum sensor 28 are provided on the integrated measuring chamber. The vacuum sensor 28 is used to detect the vacuum degree in the interlayer, and the balancing valve 25 is used to adjust the relative balance of pressure on both sides. The high vacuum baffle valve 20, the interlayer evacuation valve 30, the balancing valve 25 and the vacuum sensor 28 are all communicatively connected with the control system 18. The vacuum sensor 28 transmits the detection value to the control system 18, and the control system 18 opens or closes the high vacuum baffle valve 20 and the interlayer evacuation valve 30 according to the detection value.

Referring to Figures 1 and 4, the micro-positive pressure nitrogen flushing and replacement system includes a nitrogen source 29, a third gas heater 26, a pressure sensor 19 and an automatic gas outlet control valve 37; the gas inlet end of the third gas heater 26 is connected to the nitrogen source 29, the gas outlet end of the third gas heater 26 is connected to the integrated measuring chamber 22, and an interlayer gas inlet control valve 23 is connected between the third gas heater 26 and the integrated measuring chamber 22 to control the input of hot nitrogen into the interlayer, the automatic gas outlet control valve 38 is connected to the explosion-proof device port of the outer container interlayer through a pipeline, and the pressure sensor 19 is connected to the integrated measuring chamber 22. It is connected to the integrated measuring chamber 22 and is used to detect the air pressure in the interlayer. During the replacement process, when the air pressure in the interlayer detected by the pressure sensor 19 reaches the set value, while nitrogen is continuously filled into the interlayer, the automatic air outlet control valve 38 is opened to discharge the nitrogen and maintain the interlayer air pressure, so that the nitrogen can circulate in the interlayer, thereby increasing the replacement effect; the third gas heater 26, the interlayer air inlet control valve 23 and the automatic air outlet control valve 37 are all communicated with the control system 18 and their switches are controlled by the control system 18; the above-mentioned third gas heater 26 can be heated using natural gas energy or electric energy.

Referring to Figures 1 and 4, the micro-positive pressure nitrogen flushing and replacement system also includes a nitrogen pressure sensor 27 for detecting the nitrogen input pressure, an interlayer inlet temperature sensor 24 for detecting the temperature of the input nitrogen, an interlayer outlet temperature sensor 38 for detecting the temperature of the nitrogen output from the interlayer, and an interlayer vacuum gauge 31 for detecting the vacuum degree of the interlayer; the nitrogen pressure sensor 27 is connected between the nitrogen source 29 and the third gas heater 26, the interlayer inlet temperature sensor 24 is connected between the third gas heater 26 and the integrated measurement chamber 22, the interlayer outlet temperature sensor 38 is connected between the interlayer and the automatic outlet control valve 37, and the interlayer vacuum gauge 31 is connected to the interlayer; the nitrogen pressure sensor 27, the interlayer inlet temperature sensor 24, the interlayer vacuum gauge 31 and the interlayer outlet temperature sensor 38 are all connected to the control system 18 for communication, and the detected results are transmitted to the control system 18 and displayed.

Referring to FIG. 1 , the present invention also relates to a method for obtaining vacuum by using the interlayer of the vacuum multilayer thermal insulation cryogenic container, which comprises the following steps:

S1. Place the vacuum multilayer insulated low-temperature container in the drying room 3, and use the inner container heating and cooling circulation system to circulate and heat the inner container, specifically: use the control system to set the upper limit value of the inner container heating temperature (the upper limit value of the inner container heating temperature can be between 100°C and 200°C) and the lower limit value of the inner container heating temperature (the lower limit value of the inner container heating temperature is 100°C), open the inner container air inlet valve 11 and the inner container air outlet valve 14, open the first gas heater 13 and the first circulation fan 17, heat the gas output by the first circulation fan 17 in the first gas heater 13, wherein the gas temperature is controlled between 100°C and 300°C, and then The gas is then filled into the inner container 7 through the air inlet of the inner container 7 to heat the inner container 7, and then discharged from the exhaust port of the inner container 7 to enter the first circulation fan 17 and the first gas heater 13, so as to circulate and heat the inner container 7; when the inner container gas outlet temperature sensor 10 shows that the temperature reaches the upper limit value of the inner container heating temperature, the first gas heater 13 stops heating; when the inner container gas outlet temperature sensor 10 shows that the temperature is lower than the lower limit value of the inner container heating temperature, the first gas heater 13 starts heating to keep the temperature of the gas discharged from the inner container 7 between the lower limit value of the inner container heating temperature and the upper limit value of the inner container heating temperature.

S2. The outer container is circulated and heated by the outer container using the outer container heating and cooling circulation system, specifically: the control system is used to set the upper limit value of the outer container heating temperature (the upper limit value of the outer container heating temperature can be between 100°C and 180°C) and the lower limit value of the outer container heating temperature (the lower limit value of the outer container heating temperature is 100°C), the second gas heater 34 and the second circulation fan 35 are turned on, and the gas output by the second circulation fan 35 is heated in the second gas heater 34, wherein the gas temperature is controlled between 100°C and 250°C, and then filled into the gas channel 32 at the bottom of the drying room, and the hot gas begins to be discharged through the gas channel 32 at the bottom of the drying room, and enters the drying room 3 The outer container 5 is heated internally, and then enters the gas channel 4 on the top of the drying room through the air outlet window opened on the gas channel 4 on the top of the drying room, is discharged through the exhaust port of the drying room 3, and enters the second circulation fan 34 and the second gas heater 34, so as to circulate and heat the outer container 5; when the drying room temperature sensor 36 shows that the temperature reaches the upper limit value of the outer container heating temperature, the second gas heater 34 stops heating; when the drying room temperature sensor 36 shows that the temperature is lower than the lower limit value of the outer container heating temperature, the second gas heater 34 starts heating to keep the gas temperature of the drying room 3 between the lower limit value of the outer container heating temperature and the upper limit value of the outer container heating temperature.

S3. Use the control system to set the first vacuum threshold of the interlayer (the value range of the first vacuum threshold is 10Pa~300Pa). When the temperature of the gas discharged from the inner container heating and cooling circulation system reaches the lower limit of the inner container heating temperature, start the vacuum pumping unit 21, open the high vacuum baffle valve 20 and the interlayer evacuation valve 30, and evacuate the interlayer. When the vacuum sensor 28 on the integrated measuring chamber 22 shows that the vacuum degree reaches the set first vacuum threshold, close the high vacuum baffle valve 20, and stop the vacuum pumping unit 21 to evacuate the interlayer. During the evacuation process, the inner container heating and cooling circulation system is used to control the temperature of the inner container between the lower limit of the inner container heating temperature and the upper limit of the inner container heating temperature. The outer container heating and cooling circulation system is used to control the temperature of the gas outside the outer container between the lower limit of the outer container heating temperature and the upper limit of the outer container heating temperature.

S4. When the vacuum degree of the interlayer reaches the first vacuum degree threshold, a micro-positive pressure nitrogen flushing and replacement system is used to replace the gas in the interlayer. During the replacement process, the interlayer pressure is controlled at 110KPa~130KPa, specifically: open the nitrogen source 29 gas supply valve and the third gas heater 26, heat the nitrogen output by the nitrogen source 29, wherein the interlayer inlet temperature sensor 24 displays the nitrogen temperature, and the nitrogen temperature is controlled at 120℃~250℃; open the interlayer inlet control valve 23, and fill the hot nitrogen into the interlayer through the integrated measuring chamber 22; when the pressure sensor 19 installed in the integrated measuring chamber 22 displays a pressure ≥0.1MPa, open the automatic outlet control valve 37, release the interlayer nitrogen, and continue to outlet for a predetermined period of time, which can be 1~12h, and the nitrogen outlet temperature is displayed in the outlet temperature sensor 38, and the nitrogen outlet temperature is controlled between 100℃~180℃; the nitrogen source pressure is controlled at the nitrogen pressure sensor 27 display ≤0.2MPa;

S5. Set the vacuum threshold of the integrated measuring chamber, close the micro-positive pressure nitrogen flushing and replacement system, that is, close the automatic gas outlet control valve 37 and the interlayer gas inlet control valve 23, stop the third gas heater 26 and the nitrogen source 29 gas supply valve, and start the vacuum pumping unit again to evacuate the interlayer until the vacuum sensor 28 on the integrated measuring chamber 22 shows that the vacuum is less than the set integrated measuring chamber vacuum threshold.

S6. Use the control system to set the second vacuum threshold of the interlayer (the second vacuum threshold is set to 10Pa), repeat S4 and S5 several times until the vacuum of the interlayer is less than the second final vacuum threshold, and complete the nitrogen replacement of the interlayer. In this process, the inner container 7 and the outer container 5 are synchronously cyclically heated to allow the gas heat to efficiently penetrate the insulation layer 6, so that the moisture adsorbed by the insulation layer 6 is vaporized, and the interlayer is evacuated to form a negative pressure in the vacuum interlayer space compared to the insulation layer interlayer, which causes water vapor to entrain non-condensable gases to penetrate into the interlayer space, and is continuously entrained and carried out of the interlayer space by the slightly pressurized hot nitrogen. Repeating the operation multiple times can completely replace the moisture and non-condensable gases adsorbed by the interlayer material.

S7. Stop the outer container heating and cooling circulation system and the vacuum unit, and fill the interlayer with adsorbent.

S8. Start the outer container heating and cooling circulation system again to circulate heating on the outer container.

S9. Use the control system to set the third vacuum degree threshold of the interlayer (the third vacuum degree threshold is set to 5Pa), and start the vacuum pumping unit again to continuously evacuate the interlayer until the vacuum degree is lower than the third vacuum degree threshold, that is, the vacuum degree should meet the process setting value.

S10. After reaching the predetermined vacuum degree, the inner container is cooled by the inner container heating and cooling circulation system, that is, the first gas heater 13 is closed, the inner container cooling exhaust valve 12 and the inner container cooling air intake 16 are opened, and the inner container outlet valve 14 is closed, so that the air inlet of the first circulation fan 17 is clean room temperature air that has passed through the filter 15. The room temperature air is filled into the inner container 7 through the air inlet of the inner container 7 to cool the inner container 7, and then discharged through the inner container cooling exhaust valve 12.

S11. Use the outer container heating and cooling circulation system to cool the outer container, that is, stop the second circulation fan 35 and the second gas heater 34, open the drying room cooling exhaust fan 2 and the drying room cooling air inlet valve 9, start forced cooling of the outer container, until the drying room temperature sensor 36 shows that the temperature reaches the set temperature, close the drying room cooling exhaust fan 2 and the drying room cooling air inlet valve 9, open the drying room 3 door and the inspection door, and let the outer container 5 cool to room temperature.

S12. When the temperature of the inner container and the air temperature around the outer container return to normal temperature, stop the vacuum unit.

By using the method and system according to the present invention, the interlayer materials of the vacuum multilayer insulated container, including the insulating material, the outer surface of the inner container, and the moisture and non-condensable gas adsorbed on the inner surface of the outer container, are completely desorbed and replaced out of the interlayer, and what remains in the interlayer is high-purity nitrogen, which can be easily extracted. Therefore, when the interlayer is evacuated and vacuum sealed, the interlayer material continuously releases very few gas molecules, so that a long-lasting interlayer vacuum life can be obtained. If a reasonable adsorbent is used at the same time, the vacuum life of the interlayer of the vacuum multilayer insulated low-temperature container can reach more than 10 years, which is more than 200% higher than the vacuum life of the interlayer of conventional containers; by using the method and system according to the present invention, the vacuum acquisition time of the interlayer of the vacuum multilayer insulated container can be shortened to 3-6 days, reducing the manufacturing cycle of high-vacuum multilayer insulated storage tanks, tank boxes, and tank trucks, and reducing manufacturing costs.

Effect Example 1

From 2002 to 2019, a company in Lanzhou carried out this test on 36 cryogenic containers of a new type of submarine with a volume of 20m ³ to 32m ^3. The effective volume of the interlayer of the vacuum multilayer insulated cryogenic container is 6 to 8m ³ ; the achieved interlayer sealing vacuum degree is 1.5×10 ^-4 Pa to 3.3×10 ^-3 Pa, and the achieved interlayer cryogenic pressure is 6×10 ^-5 Pa to 3×10 ^-4 Pa. No significant change was found in the retest of the interlayer cryogenic pressure after 4 to 14 years, as shown in Figure 5.

Effect Example 2

In November 2017, a vacuum effect demonstration was carried out in a company in Nantong: a 40-foot LNG container, with an effective vacuum interlayer space of ^8.5m3 and an effective vacuum time of 6 days, was used. When the vacuum was completed, the sealing vacuum was 3.1E-3Pa, as shown in Table 1; after the liquid nitrogen was added for thermal equilibrium, the cold vacuum was 1.8E-4Pa, as shown in Table 2; 2 years later, in October 2019, the two parties conducted a tracking test on the vacuum degree of the interlayer, and the data is shown in Table 3; the data showed that the vacuum degree of the interlayer decreased by 2E-4Pa in 2 years, and it can be expected that the vacuum degree of the interlayer will still be at the E-3 level 20 years later.

Table 1: Sealing vacuum test table

Table 2: Initial cold vacuum test table

Table 3: Cold vacuum test table after 2 years

Effect Example 3

In February 2019, a company in Wuxi implemented a 40-foot LNG tank container with an effective vacuum interlayer space of 8.5m ^3. The effective replacement and evacuation took a total of 6 days. When sealing, the inner tank outlet temperature was 52°C, and the interlayer vacuum degree was 9.5×10 ^-4 Pa (directly measured by installing the interlayer gauge). The current national standard NB/T47059-2017 requires that the sealing vacuum degree index of the same type of product be 8×10 ^-2 Pa at room temperature. The sealing data is excellent and unique 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 (6)

1. The vacuum obtaining system of the vacuum multilayer heat-insulating low-temperature container interlayer comprises an outer container and an inner container arranged inside the outer container, wherein the interlayer is arranged between the outer container and the inner container, and the vacuum obtaining system is characterized in that: the vacuum acquisition system includes:

The inner container heating and cooling circulation system is connected with the inner container and is used for circularly heating or cooling the inner container, the inner container heating and cooling circulation system comprises a first circulating fan, a first gas heater and an inner container cooling air inlet valve, the air outlet end of the first circulating fan is connected with the air inlet end of the first gas heater, the air outlet end of the first gas heater and the air inlet end of the first circulating fan are both connected with the inner container of the vacuum multilayer heat insulation low-temperature container, an inner container cooling exhaust valve is also connected with the air inlet end of the first circulating fan, an inner container air inlet valve is also connected between the first gas heater and the inner container, an inner container cooling exhaust valve and an inner container air outlet valve are also connected between the first circulating fan and the inner container in sequence, and the inner container cooling air inlet valve is matched with a filter; the first circulating fan, the first gas heater, the inner container air inlet valve, the cooling exhaust valve, the inner container air outlet valve and the inner container cooling air inlet valve are all in communication connection with the control system;

The outer container heating and cooling circulation system is used for circularly heating or cooling the outer container and comprises a drying room, a second circulating fan, a second gas heater, a drying room cooling exhaust fan and a drying room cooling air inlet valve; the drying room is characterized in that a drying room bottom gas channel is arranged at a position, close to the bottom, inside the drying room, and a drying room top gas channel is arranged at a position, close to the top, of the drying room; the air outlet end of the second circulating fan is connected with the air inlet end of the second air heater, the air outlet end of the second air heater is connected with the air channel at the bottom of the drying room, and the air inlet end of the second circulating fan is connected with the air channel at the top of the drying room; the second circulating fan, the second gas heater, the drying room cooling exhaust fan and the drying room cooling air inlet valve are all in communication connection with the control system;

The micro-positive pressure nitrogen flushing and replacing system is connected with the interlayer and is used for replacing the gas in the interlayer and controlling the pressure of the interlayer to be 110 KPa-130 KPa;

the vacuumizing unit is connected with the interlayer and is used for vacuumizing the interlayer;

The control system is used for controlling the inner container heating and cooling circulation system, the outer container heating and cooling circulation system, the micro-positive pressure nitrogen flushing and replacing system and the vacuumizing unit;

The high-vacuum baffle valve, the interlayer evacuation valve, the balance valve and the vacuum sensor are all in communication connection with the control system;

The micro-positive pressure nitrogen flushing and replacing system comprises a nitrogen source, a third gas heater, an automatic gas outlet control valve and a pressure sensor; the air inlet end of the third air heater is connected with a nitrogen source, the air outlet end of the third air heater is connected to the integrated measuring chamber, an interlayer air inlet control valve is connected between the third air heater and the integrated measuring chamber, the automatic air outlet control valve is connected to an interlayer explosion-proof device port of the outer container through a pipeline, and the pressure sensor is connected to the integrated measuring chamber; the third gas heater, the interlayer gas inlet control valve, the pressure sensor and the automatic gas outlet control valve are all in communication connection with the control system.

2. The vacuum acquisition system for a vacuum multilayer insulated low temperature container interlayer according to claim 1, wherein: the inner container heating and cooling circulation system further comprises an inner container air inlet temperature sensor and an inner container air outlet temperature sensor, wherein the inner container air inlet temperature sensor is connected between an inner container air inlet valve and the inner container, the inner container air outlet temperature sensor is connected between the inner container and an inner container cooling exhaust valve, and the inner container air inlet temperature sensor and the inner container air outlet temperature sensor are both in communication connection with the control system.

3. The vacuum acquisition system for a vacuum multilayer insulated low temperature container interlayer according to claim 1, wherein: the outer container heating and cooling circulation system also comprises a drying room air inlet temperature sensor, a drying room air outlet temperature sensor and a drying room temperature sensor; the air inlet temperature sensor of the drying room is connected between the second air heater and the air channel at the bottom of the drying room, the air outlet temperature sensor of the drying room is connected between the second circulating fan and the air channel at the top of the drying room, and the temperature sensor of the drying room is arranged in the drying room; and the drying room air inlet temperature sensor, the drying room air outlet temperature sensor and the drying room temperature sensor are all in communication connection with the control system.

4. The vacuum acquisition system for a vacuum multilayer insulated low temperature container interlayer according to claim 1, wherein: the micro-positive pressure nitrogen flushing replacement system also comprises a nitrogen pressure sensor, an interlayer air inlet temperature sensor, an interlayer air outlet temperature sensor and an interlayer vacuum gauge for detecting the vacuum degree of the interlayer; the nitrogen pressure sensor is connected between the nitrogen source and the third gas heater, the interlayer air inlet temperature sensor is connected between the third gas heater and the integrated measuring chamber, the interlayer air outlet temperature sensor is connected between the interlayer and the automatic air outlet control valve, and the interlayer vacuum gauge is connected with the interlayer; the nitrogen pressure sensor, the interlayer air inlet temperature sensor, the interlayer vacuum gauge and the interlayer air outlet temperature sensor are all in communication connection with the control system.

5. A method of using the vacuum acquisition system of claim 1 for a vacuum multilayer insulated cryogenic container sandwich, characterized by: which comprises the following steps:

s1, circularly heating an inner container by adopting an inner container heating and cooling circulation system;

s2, circularly heating the outer container by adopting an outer container heating and cooling circulation system;

s3, setting a first vacuum degree threshold of the interlayer, starting a vacuumizing unit to vacuumize the interlayer until the vacuum degree of the interlayer reaches the first vacuum degree threshold;

S4, after the vacuum degree of the interlayer reaches a first vacuum degree threshold, adopting a micro-positive pressure nitrogen flushing displacement system to displace the gas in the interlayer, and controlling the pressure of the interlayer at 110 KPa-130 KPa in the displacement process;

s5, closing the micro-positive pressure nitrogen flushing replacement system, and starting the vacuumizing unit again to vacuumize the interlayer;

s6, repeating the steps S4 and S5 for a plurality of times;

S7, stopping the heating and cooling circulation system of the outer container and the vacuumizing unit, and filling the adsorbent into the interlayer;

s8, restarting the heating and cooling circulation system of the outer container to circularly heat the outer container;

S9, starting the vacuumizing unit again to continuously vacuumize the interlayer;

S10, cooling the inner container through the inner container heating and cooling circulation system after reaching a preset vacuum degree;

S11, adopting an outer container heating and cooling circulation system to cool the outer container;

S12, stopping the vacuumizing unit when the temperature of the inner container and the temperature of the air around the outer container are restored to normal temperature.

6. The method of claim 5, wherein the vacuum obtaining system comprises a vacuum multi-layer insulated low temperature container sandwich, wherein: in the step S1, the temperature of the gas output by the heating and cooling circulating system of the inner container is controlled between 100 ℃ and 300 ℃; in the step S2, the temperature of the gas output by the heating and cooling circulation system of the outer container is controlled between 100 ℃ and 250 ℃; in the step S3, a control system is adopted to set a lower limit value and an upper limit value of the temperature of the inner container, a lower limit value and an upper limit value of the temperature of the drying room, when the temperature of gas discharged by the heating and cooling circulation system of the inner container reaches the lower limit value of the temperature of the inner container, a vacuumizing unit is started to vacuumize an interlayer, and in the vacuumizing process, the temperature of the inner container is controlled between the lower limit value and the upper limit value of the temperature of the inner container by adopting the heating and cooling circulation system of the inner container, and the temperature of the peripheral gas of the outer container is controlled between the lower limit value and the upper limit value of the temperature of the drying room by adopting the heating and cooling circulation system of the outer container; in the step S4, the duration of gas in the interlayer is 1-12 hours by adopting the micro-positive pressure nitrogen flushing displacement system each time.