Low-temperature liquid storage tank vacuumizing system and method based on powder heat insulation

Abstract

The invention provides a low-temperature liquid storage tank vacuumizing system and method based on powder heat insulation. The vacuumizing system comprises a vacuumizing assembly. The vacuumizing assembly comprises an internal air extractor, a filter, a vacuum valve and a vacuum pump; during use, the internal air extractor extends into an interlayer formed by an outer shell and an inner shell of the powder heat insulation low-temperature liquid storage tank; the internal air extractor comprises an evacuation pipeline, and the first end of the evacuation pipeline is connected with a vacuum pump through a vacuum valve and a filter in sequence; a pipeline opening in the second end of the evacuation pipeline is connected with a supporting frame, and the periphery of the supporting frame is wrapped with a silk screen. The vacuumizing system can effectively solve the problems that the interlayer filled with the powder heat insulation material is too large in flow resistance and difficult to vacuumize.

Description

Technical Field

[0001] The invention belongs to the field of chemical industry and relates to a cryogenic liquid storage tank, and in particular to a vacuum pumping system and method for a cryogenic liquid storage tank based on powder insulation. Background Art

[0002] Large storage tanks are one of the important equipment for large-scale storage of cryogenic liquids (such as liquid hydrogen and liquid oxygen). Due to the low temperature and small latent heat of vaporization of cryogenic liquids, storage tanks are usually designed as double-layer structures. The interlayer formed by the double-layer structure is evacuated to isolate heat leakage from the environment.

[0003] The Chinese patent application with publication number CN117267602A discloses a high vacuum equipment for tank trucks and its operating process, which heats the outer layer and inner layer of the tank respectively through a drying room and a closed-loop heating system in the drying room, and performs vacuum operation by alternating evacuation and nitrogen filling. However, if powder insulation materials (such as hollow glass microspheres and pearlescent sand) are filled in the interlayer of the tank, the flow resistance will increase, the vacuum effect will be reduced, and the powder insulation materials will be easily extracted. And when the vacuum degree of the interlayer is high (such as 10 Pa and above), the powder insulation materials can exert the best insulation performance. Therefore, the above-mentioned high vacuum equipment is not suitable for vacuuming storage tanks filled with powder insulation materials in the interlayer. Summary of the invention

[0004] In order to solve the above problems of the prior art, the present invention provides a vacuum pumping system and method for a cryogenic liquid storage tank based on powder insulation, which can effectively solve the problem of excessive flow resistance of the interlayer filled with powder insulation material and difficulty in vacuuming.

[0005] The present invention is achieved through the following technical solutions: The present invention provides a vacuum pumping system for a cryogenic liquid storage tank based on powder insulation, comprising a vacuum pumping component; the vacuum pumping component comprises an internal air pumping device, a filter, a vacuum valve and a vacuum pump; when in use, the internal air pumping device extends into a sandwich formed by an outer shell and an inner shell of a powder insulation cryogenic liquid storage tank; the internal air pumping device comprises an air pumping pipe, a first end of the air pumping pipe is connected to the vacuum pump via a vacuum valve and a filter in sequence; a support frame is connected to a pipe opening at the second end of the air pumping pipe, and the outer periphery of the support frame is covered with a wire mesh.

[0006] Preferably, the periphery of the wire mesh wrapped around the periphery of the supporting frame is wrapped with wire cloth.

[0007] Preferably, the second end pipe opening of the evacuation pipe is covered with a wire mesh perpendicular to the axis of the evacuation pipe.

[0008] Preferably, the support frame is Z-shaped steel.

[0009] Preferably, the vacuum pump comprises a main pump and a front-stage pump; the filter is connected to the main pump via a high vacuum baffle valve, and the main pump is connected to the front-stage pump via an electromagnetic vacuum valve.

[0010] Preferably, it also includes an external heating device and an internal heating device, wherein the external heating device is used to heat the outer shell of the powder insulated cryogenic liquid storage tank, and the internal heating device is used to heat the inner shell of the powder insulated cryogenic liquid storage tank.

[0011] Preferably, it also includes a nitrogen hot flushing device, which includes a charging valve, a first heater, a vaporizer, a cryogenic shut-off valve, and a liquid nitrogen storage tank; the outlet of the liquid nitrogen storage tank is connected to the inlet of the vaporizer via the cryogenic shut-off valve, the outlet of the vaporizer is connected to the inlet of the first heater, and the outlet of the first heater is connected to the end of the filter away from the evacuation pipe via the charging valve.

[0012] The present invention provides a method for evacuating a cryogenic liquid storage tank based on powder insulation, which is based on the above-mentioned cryogenic liquid storage tank evacuation system based on powder insulation, comprising: extending an internal vacuum device into the interlayer of the powder-insulated cryogenic liquid storage tank, opening a vacuum valve and a vacuum pump to evacuate to a designed vacuum degree.

[0013] The present invention provides another method for evacuating a cryogenic liquid storage tank based on powder insulation, which is based on the cryogenic liquid storage tank evacuation system based on powder insulation as described above, and includes: extending an internal vacuum device into the interlayer of the powder insulated cryogenic liquid storage tank, using an internal heating device to heat the inner shell to a preset temperature of the inner shell, using an external heating device to heat the outer shell to a preset temperature of the outer shell, and then opening a vacuum valve and a vacuum pump to evacuate to a designed vacuum degree.

[0014] The present invention provides another method for vacuuming a cryogenic liquid storage tank based on powder insulation, based on the above-mentioned cryogenic liquid storage tank vacuuming system based on powder insulation, comprising: The internal air extraction device extends into the interlayer of the powder-insulated cryogenic liquid storage tank; Vacuuming: Open the vacuum valve and the vacuum pump to evacuate to the first preset vacuum degree; Filling with nitrogen: turn off the vacuum pump, open the charging valve, low-temperature stop valve, first heater, and vaporizer, and fill the interlayer with high-temperature and high-pressure nitrogen to the preset pressure; close the charging valve, low-temperature stop valve, first heater, and vaporizer; Vacuuming: Turn on the vacuum pump to evacuate to the second preset vacuum degree; Filling with nitrogen: turn off the vacuum pump, open the charging valve, low-temperature stop valve, first heater, and vaporizer, and fill the interlayer with high-temperature and high-pressure nitrogen to the preset pressure; close the charging valve, low-temperature stop valve, first heater, and vaporizer; According to the above method, the vacuuming step and the nitrogen filling step are cyclically performed alternately, wherein the preset vacuum degree of the latter vacuuming step is higher than the preset vacuum degree of the previous vacuuming step; until the vacuum degree in the interlayer reaches the designed vacuum degree.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The powder-insulated cryogenic liquid storage tank vacuum pumping system of the present invention has a special arrangement for the vacuum pumping pipe extending into the tank interlayer, specifically, a support frame is arranged at the pipe opening of the vacuum pumping pipe. Because the side of the support frame is not a closed structure, the gas in the interlayer can not only flow into the interior of the support frame from its end face, but also flow in from its side, and finally be extracted through the vacuum pumping pipe, thereby greatly reducing the flow resistance of the gas, improving the vacuum pumping effect, shortening the vacuum pumping time, and reducing the vacuum pumping cost. At the same time, the arrangement of the support frame allows the gas in the interlayer to be evenly extracted, improving the thermal insulation performance of the powder insulation material. In order to prevent the powder from being extracted, the present invention covers the periphery of the support frame (including the side and end faces) with a wire mesh to prevent the powder from being extracted through the vacuum pumping pipe during the vacuum pumping process.

[0016] Furthermore, in the present invention, the outer periphery of the wire mesh is coated with a wire cloth, and the size of the holes on the wire cloth is smaller than that of the wire mesh. Therefore, it can play a better role in blocking the powder and further reduce the risk of the powder being extracted.

[0017] Furthermore, the present invention covers the pipe opening of the evacuated pipe with a wire mesh to block the powder again and improve the blocking effect.

[0018] Furthermore, the vacuum pump of the present invention comprises a main pump and a front-stage pump. The arrangement of the two-stage pump can improve the air extraction capacity and reduce the vacuum extraction time.

[0019] Furthermore, the present invention provides an external heating device and an internal heating device, which are respectively used to heat the outer shell and the inner shell of the storage tank, thereby accelerating the degassing of the metal materials of the outer shell and the inner shell, which can effectively eliminate the impact of the degassing of the metal materials on the vacuum life of the interlayer and prevent the vacuum degree from rebounding.

[0020] Furthermore, the present invention is provided with a nitrogen hot flushing device, and the heated high-temperature nitrogen enters the tank interlayer to replace the air and water vapor in the interlayer, which can effectively eliminate the influence of factors such as residual air and water vapor in the interlayer on the vacuum life and prevent vacuum rebound. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a schematic diagram of a vacuum pumping system for a large cryogenic liquid storage tank based on powder insulation of the present invention; Figure 2 Schematic diagram of the internal exhaust device.

[0023] Figure 3 The present invention is a vacuuming process of a cryogenic liquid storage tank based on powder insulation in an embodiment of the present invention.

[0024] In the figure: 1-external heating belt; 2-outer shell; 3-internal exhaust device; 4-inner shell; 5-high vacuum plug valve; 6-first vacuum gauge; 7-second vacuum gauge; 8-filter; 9-high vacuum baffle valve; 10-main pump; 11-electromagnetic vacuum valve; 12-fore pump; 13-charging valve; 14-first thermometer; 15-first pressure gauge; 16-first heater; 17-vaporizer; 18-low temperature stop valve; 19-liquid nitrogen storage tank; 20-second thermometer; 21-second heater; 22-blower; 23-third thermometer; 24-support frame; 25-wire mesh; 26-wire cloth; 27-evacuation pipeline. DETAILED DESCRIPTION

[0025] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0026] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0027] It should be noted that the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to define the scope of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the present invention without substantially changing the technical content.

[0028] In addition, it should be noted that the terms "first", "second", etc. of the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. The orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention; in addition, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements.

[0029] The powder-insulated cryogenic liquid storage tank vacuum pumping system of the present invention is used to vacuumize the interlayer of the powder-insulated cryogenic liquid storage tank after filling the interlayer with powder. The powder-insulated cryogenic liquid storage tank comprises an outer shell 2 and an inner shell 4, and the interlayer ( Figure 1 ).

[0030] like Figure 1 and Figure 2 As shown, the vacuum pumping system for cryogenic liquid storage tank based on powder insulation includes a vacuum pumping component, and the vacuum pumping component includes: an internal vacuum pumping device 3, a filter 8, a vacuum valve and a vacuum pump; when in use, the internal vacuum pumping device 3 extends into the interlayer of the powder insulated cryogenic liquid storage tank; the internal vacuum pumping device 3 includes a vacuum pumping pipe 27, and the first end of the vacuum pumping pipe 27 is connected to the vacuum pump via the vacuum valve and the filter 8 in sequence; a support frame 24 is connected to the pipe opening at the second end of the vacuum pumping pipe 27, and the outer periphery of the support frame 24 is covered with a wire mesh 25.

[0031] The support frame 24 of the present invention can prevent the interlayer filled with powder from having too large flow resistance, which causes difficulty and unevenness in evacuation. At the same time, the wire mesh 25 is coated on the periphery of the support frame 24 to prevent the powder from being evacuated through the evacuation pipe 27 during the evacuation process.

[0032] As a further preferred embodiment, the wire mesh 25 wrapped around the outer periphery of the support frame 24 of the present invention is also wrapped around a wire cloth 26. In addition, the number of layers of the wire mesh 25 can be one layer, two layers, or more layers. The more layers, the better the effect of blocking powder. At the same time, the wire cloth 26 can also be one layer, two layers or more layers, which can be selected according to actual needs and actual effects.

[0033] At this time, the gas in the interlayer of the powder insulation cryogenic liquid storage tank can enter the evacuation pipeline through the support frame 24 and be evacuated by the vacuum pump, and the powder in the interlayer is blocked by the wire mesh 25 and the wire cloth 26. This device weakens the influence of the flow resistance of the powder on the evacuation, shortens the evacuation time, and can achieve a uniform evacuation effect.

[0034] The present invention can also cover the pipe opening at the second end of the evacuation pipe 27 with a wire mesh 25 that is perpendicular to the axis of the evacuation pipe 27 to further reduce the risk of powder being evacuated.

[0035] In some specific embodiments of the present invention, the support frame 24 is a Z-shaped steel. When in use, the support frame 24 extends all the way to the middle and upper part of the interlayer of the powder insulated cryogenic liquid storage tank.

[0036] In some specific embodiments of the present invention, the wire mesh 25 is a stainless steel wire mesh, and the wire cloth 26 is a glass wire cloth.

[0037] Specifically, in a preferred embodiment of the present invention, the vacuum valve is a high vacuum gate valve 5. The vacuum pump includes a main pump 10 and a front pump 12, the filter 8 is connected to the main pump 10 via a high vacuum baffle valve 9, and the main pump 10 is connected to the front pump 12 via an electromagnetic vacuum valve 11. When the interlayer of the powder insulated cryogenic liquid storage tank is evacuated, the high vacuum gate valve, the high vacuum baffle valve 9, and the electromagnetic vacuum valve 11 are first opened, and the front pump 12 is started to evacuate the interlayer and the main pump 10 is started after the starting pressure of the main pump 10 is met, until the vacuum is evacuated to the required vacuum degree. A first vacuum gauge 6 and a second vacuum gauge 7 are provided on the connecting pipe between the high vacuum gate valve 5 and the filter 8.

[0038] In order to further improve the vacuuming effect, the powder-insulated cryogenic liquid storage tank vacuuming system of the present invention also includes an external heating device and an internal heating device. The external heating device is used to heat the outer shell 2 of the powder-insulated cryogenic liquid storage tank, and the internal heating device is used to heat the inner shell 4 of the powder-insulated cryogenic liquid storage tank, thereby accelerating the degassing of the metal materials of the outer shell 2 and the inner shell 4, which can effectively eliminate the influence of the degassing of the metal materials on the vacuum life of the interlayer and prevent the vacuum degree from rebounding.

[0039] In a specific embodiment of the present invention, the external heating device is an external heating belt 1 , and the external heating belt 1 covers and is wound around the outer surface of the outer shell 2 .

[0040] In a specific embodiment of the present invention, the internal heating device includes a second thermometer 20, a second heater 21, a blower 22, a third thermometer 23, an air inlet duct, and an air outlet duct. The air outlet of the blower 22 is connected to the air inlet of the second heater 21, and the air outlet of the second heater 21 is connected to the air inlet duct. The other end of the air inlet duct extends into the inner shell 4. The second thermometer 20 is arranged on the air inlet duct. One end of the air outlet duct extends into the inner shell 4, and the other end extends out of the outer shell 2. The blower 22 blows air into the second heater 21 to heat it, and then sends it into the inner shell 4, heats the inner shell 4, and accelerates the degassing of the metal material. During this period, the second thermometer 20 and the third thermometer 23 are used to monitor the inlet and outlet air temperatures.

[0041] In order to further reduce the residual air and water vapor in the interlayer, the present invention is also provided with a nitrogen hot flushing device. The nitrogen hot flushing device includes a charging valve 13, a first thermometer 14, a first pressure gauge 15, a first heater 16, a vaporizer 17, a low-temperature stop valve 18, and a liquid nitrogen storage tank 19. The outlet of the liquid nitrogen storage tank 19 is connected to the inlet of the vaporizer 17 through the low-temperature stop valve 18, the outlet of the vaporizer 17 is connected to the inlet of the first heater 16, and the outlet of the first heater 16 is connected to the inlet of the high vacuum baffle valve 9 through the charging valve 13. The first thermometer 14 and the first pressure gauge 15 are arranged on the connecting pipe between the first heater 16 and the charging valve 13.

[0042] The liquid nitrogen provided by the liquid nitrogen storage tank 19 is vaporized into nitrogen after passing through the vaporizer 17, and is heated into high-temperature and high-pressure nitrogen by the first heater 16, and enters the tank interlayer to replace the air and water vapor in the interlayer. During this period, the first thermometer 14 and the first pressure gauge 15 are used to monitor the temperature and pressure of the nitrogen entering the interlayer.

[0043] The nitrogen hot flushing device can effectively eliminate the influence of residual air and water vapor in the interlayer on the vacuum life and prevent vacuum rebound.

[0044] In order to fully replace the interlayer air and water vapor and prevent the vacuum rebound, a progressive evacuation method can be used. For example: it takes 4 days to reduce the interlayer pressure to 100 Pa, and then the nitrogen is re-pressurized to 80 kPa and maintained within 1 day, and the cycle is repeated 4 times; it takes 6 days to reduce the interlayer pressure to 50 Pa, and the nitrogen is re-pressurized to 80 kPa and maintained within 1 day, and the cycle is repeated 2 times; it takes 9 days to reduce the interlayer pressure to 10 Pa, and the nitrogen is re-pressurized to 80 kPa and maintained within 1 day; it takes 16 days to reduce the interlayer pressure to 1 Pa, and then the interlayer is vacuum sealed, and the evacuation process is completed.

[0045] In order to reduce manual operation and avoid errors caused by manual operation, the vacuum pump, nitrogen hot flushing device, internal heating device and external heating device can be automatically controlled. The staff can perform real-time pressure and temperature detection on the evacuation system and make dynamic adjustments according to the evacuation process and requirements.

[0046] The method for evacuating a powder-insulated cryogenic liquid storage tank using the powder-insulated cryogenic liquid storage tank vacuum pumping system is specifically as follows: extending the internal vacuum device 3 into the interlayer of the powder-insulated cryogenic liquid storage tank, and extending the support frame 24 all the way to the middle and upper part of the interlayer of the powder-insulated cryogenic liquid storage tank; opening the vacuum valve and the vacuum pump to evacuate to the designed vacuum degree.

[0047] When the powder insulation-based low-temperature liquid storage tank vacuum pumping system includes an internal heating device and an external heating device, the internal heating device is used to heat the inner shell to a preset temperature of the inner shell, and the external heating device is used to heat the outer shell to a preset temperature of the outer shell, and then the vacuum valve and the vacuum pump are opened to perform vacuum pumping to a designed vacuum degree.

[0048] When the powder insulation-based cryogenic liquid storage tank vacuum pumping system includes a nitrogen thermal flushing device, the vacuum pumping steps are: Open the vacuum valve and the vacuum pump to evacuate to a first preset vacuum degree; Turn off the vacuum pump, open the charging valve 13, the low-temperature stop valve 18, the first heater 16, and the vaporizer 17, and fill the interlayer with high-temperature and high-pressure nitrogen to a preset pressure; close the charging valve 13, the low-temperature stop valve 18, the first heater 16, and the vaporizer 17; Turn on the vacuum pump to evacuate to a second preset vacuum degree; Turn off the vacuum pump, open the charging valve 13, the low-temperature stop valve 18, the first heater 16, and the vaporizer 17, and fill the interlayer with high-temperature and high-pressure nitrogen to a preset pressure; close the charging valve 13, the low-temperature stop valve 18, the first heater 16, and the vaporizer 17; The vacuuming step and the nitrogen filling step are repeated repeatedly until the vacuum degree in the interlayer reaches the designed vacuum degree.

[0049] Example 1 The powder-insulated low-temperature liquid storage tank vacuum pumping system of the present invention comprises: a vacuum pumping component, an external heating device, an internal heating device, and a nitrogen thermal flushing device.

[0050] The vacuum pumping assembly includes an internal vacuum device 3, a high vacuum gate valve 5, a filter 8, a high vacuum baffle valve 9, a main pump 10, an electromagnetic vacuum valve 11 and a front pump 12, which are connected in sequence. A first vacuum gauge 6 and a second vacuum gauge 7 are arranged on the connecting pipeline between the high vacuum gate valve 5 and the filter 8.

[0051] The internal exhaust device 3 includes an evacuation pipe 27, the first end of which is connected to the high vacuum gate valve 5; the second end of the evacuation pipe 27 is covered with a wire mesh 25 perpendicular to the axis of the evacuation pipe 27, and a support frame 24 is connected to the second end of the evacuation pipe 27, and the outer periphery of the support frame 24 is sequentially covered with two layers of wire mesh 25 and two layers of wire cloth 26. The wire mesh 25 is a stainless steel wire mesh, and the wire cloth 26 is a glass wire cloth. The support frame 24 is Z-shaped steel.

[0052] The external heating device is an external heating belt, which is covered and wound around the outer surface of the shell 2 and is used to heat the shell 2.

[0053] The inner heating device is used to heat the inner shell 3, and includes a second thermometer 20, a second heater 21, a blower 22, a third thermometer 23, an air inlet duct, and an air outlet duct. The air outlet of the blower 22 is connected to the air inlet of the second heater 21, and the air outlet of the second heater 21 is connected to the air inlet duct. The other end of the air inlet duct extends into the inner shell 4. The second thermometer 20 is arranged on the air inlet duct. One end of the air outlet duct extends into the inner shell 4, and the other end extends out of the outer shell 2. The blower 22 blows air into the second heater 21 for heating, and then sends it into the inner shell 4, so as to heat the inner shell 4 and accelerate the degassing of the metal material. During this period, the second thermometer 20 and the third thermometer 23 are used to monitor the inlet and outlet air temperatures.

[0054] The nitrogen hot flushing device includes a charging valve 13, a first thermometer 14, a first pressure gauge 15, a first heater 16, a vaporizer 17, a low-temperature stop valve 18, and a liquid nitrogen storage tank 19. The outlet of the liquid nitrogen storage tank 19 is connected to the inlet of the vaporizer 17 via the low-temperature stop valve 18, the outlet of the vaporizer 17 is connected to the inlet of the first heater 16, and the outlet of the first heater 16 is connected to the inlet of the high vacuum baffle valve 9 via the charging valve 13. The first thermometer 14 and the first pressure gauge 15 are arranged on the connecting pipe between the first heater 16 and the charging valve 13.

[0055] The liquid nitrogen provided by the liquid nitrogen storage tank 19 is vaporized into nitrogen after passing through the vaporizer 17, and is heated into high-temperature and high-pressure nitrogen by the first heater 16, and enters the interlayer to replace the air and water vapor in the interlayer. During this period, the first thermometer 14 and the first pressure gauge 15 are used to monitor the temperature and pressure of the nitrogen entering the interlayer.

[0056] With a 2000 m 3 Taking the vacuum process of the spherical tank as an example, the volume of the interlayer is about 977m 3 , the vacuum degree of the interlayer seal is 8 Pa, and the vacuum life is 5 years. Two sets of the above vacuum pumping systems should be used. The main pump can be a Roots pump of ZJ-300, and the front pump can be a 2X-70A rotary vane pump. The high vacuum gate valve 5 model can be GC-150, the first vacuum gauge 6 can be a ZJ-52T resistance vacuum gauge, the second vacuum gauge 7 can be a TPG362 film vacuum gauge, the high vacuum baffle valve 9 can be GD-J150, and the electromagnetic vacuum valve 11 can be DDC-80JQ. The total vacuum time is used Calculate, where t is the pumping time, s; K q It is the correction factor related to the tank interlayer vacuum termination pressure; V is the interlayer volume, L; S p The nominal pumping speed of the main pump or the foreline pump, L / s; p i is the pressure when the tank interlayer starts to be evacuated, Pa; p It is the pressure at the end of tank interlayer evacuation, Pa.

[0057] 2000 m 3 Taking a spherical tank as an example, the vacuuming process of the vacuuming system of a cryogenic liquid storage tank based on powder insulation in this embodiment is specifically as follows: The internal exhaust device 3 is extended into the interlayer of the powder-insulated cryogenic liquid storage tank, and the support frame 24 is extended to the middle and upper part of the interlayer of the powder-insulated cryogenic liquid storage tank; The outer shell 2 is heated to 150°C by an external heating belt. At the same time, the blower 22 is turned on to blow air into the second heater 21 to heat the air and then send it into the inner shell 4 to heat the inner shell 4 to 200°C.

[0058] like Figure 3As shown, the vacuum valve and the vacuum pump are opened for vacuuming, and it takes 4 days to reduce the pressure of the interlayer to 100 Pa, then the vacuum pump is closed, the charging valve 13, the low-temperature stop valve 18, the first heater 16, and the vaporizer 17 are opened, and the high-temperature and high-pressure nitrogen is filled into the interlayer. The nitrogen is re-pressurized to 80 kPa within 1 day and maintained, the charging valve 13, the low-temperature stop valve 18, the first heater 16, and the vaporizer 17 are closed, and the cycle is repeated 4 times; the vacuum pump is opened for vacuuming, and it takes 6 days to reduce the pressure of the interlayer to 50 Pa, then the vacuum pump is closed, the charging valve 13, the low-temperature stop valve 18, the first heater 16, and the vaporizer 17 are opened, and the high-temperature and high-pressure nitrogen is filled into the interlayer. The nitrogen is re-pressurized to 80 kPa within 1 day and maintained, the charging valve 13, the low-temperature stop valve 18, the first heater 16, and the vaporizer 17 are closed, and the cycle is repeated 2 times; the vacuum pump is opened for vacuuming, and it takes 9 days to reduce the pressure of the interlayer to 10 Pa, then close the vacuum pump, open the charging valve 13, the low-temperature stop valve 18, the first heater 16, and the vaporizer 17, fill the interlayer with high-temperature and high-pressure nitrogen, and re-pressurize the nitrogen to 80 kPa within 1 day and maintain it, close the charging valve 13, the low-temperature stop valve 18, the first heater 16, and the vaporizer 17; open the vacuum pump for vacuum extraction, and it takes 16 days to reduce the interlayer pressure to 1 Pa, and then vacuum seal the interlayer, and the evacuation process is completed.

[0059] The invention discloses a low-temperature liquid storage tank vacuum pumping system based on powder insulation, which has the advantages of fast and uniform vacuum pumping, long vacuum life and the like.

Claims

1. A vacuum pumping system for cryogenic liquid storage tanks based on powder insulation, characterized in that: The invention comprises a vacuum pumping assembly; the vacuum pumping assembly comprises an internal air pumping device (3), a filter (8), a vacuum valve and a vacuum pump; when in use, the internal air pumping device (3) extends into a sandwich formed by an outer shell (2) and an inner shell (4) of a powder insulated cryogenic liquid storage tank; the internal air pumping device (3) comprises an air pumping pipe (27), a first end of which is connected to the vacuum pump via the vacuum valve and the filter (8) in sequence; a support frame (24) is connected to the pipe opening at the second end of the air pumping pipe (27), and the outer periphery of the support frame (24) is covered with a wire mesh (25).

2. The cryogenic liquid storage tank vacuum pumping system based on powder insulation according to claim 1 is characterized in that: The periphery of the wire mesh (25) wrapped around the periphery of the support frame (24) is covered with a wire cloth (26).

3. The cryogenic liquid storage tank vacuum pumping system based on powder insulation according to claim 1 is characterized in that: The second end pipe opening of the evacuation pipe (27) is covered with a wire mesh (25) perpendicular to the axis of the evacuation pipe (27).

4. The cryogenic liquid storage tank vacuum pumping system based on powder insulation according to claim 1 is characterized in that: The support frame (24) is Z-shaped steel.

5. The cryogenic liquid storage tank vacuum pumping system based on powder insulation according to claim 1 is characterized in that: The vacuum pump comprises a main pump (10) and a front-stage pump (12); the filter (8) is connected to the main pump (10) via a high vacuum baffle valve (9), and the main pump (10) is connected to the front-stage pump (12) via an electromagnetic vacuum valve (11).

6. The cryogenic liquid storage tank vacuum pumping system based on powder insulation according to claim 1 is characterized in that: It also comprises an external heating device and an internal heating device, wherein the external heating device is used to heat the outer shell (2) of the powder insulated cryogenic liquid storage tank, and the internal heating device is used to heat the inner shell (4) of the powder insulated cryogenic liquid storage tank.

7. The cryogenic liquid storage tank vacuum pumping system based on powder insulation according to claim 1 is characterized in that: The invention also comprises a nitrogen hot flushing device, which comprises a charging valve (13), a first heater (16), a vaporizer (17), a cryogenic shut-off valve (18), and a liquid nitrogen storage tank (19); the outlet of the liquid nitrogen storage tank (19) is connected to the inlet of the vaporizer (17) via the cryogenic shut-off valve (18), the outlet of the vaporizer (17) is connected to the inlet of the first heater (16), and the outlet of the first heater (16) is connected to an end of the filter (8) away from the evacuation pipe (27) via the charging valve (13).

8. A method for vacuuming a cryogenic liquid storage tank based on powder insulation, characterized in that: The powder-insulated cryogenic liquid storage tank vacuum pumping system according to any one of claims 1 to 5 comprises: extending an internal vacuum pumping device (3) into the interlayer of the powder-insulated cryogenic liquid storage tank, opening a vacuum valve and a vacuum pump to perform vacuum pumping to a designed vacuum degree.

9. A method for vacuuming a cryogenic liquid storage tank based on powder insulation, characterized in that: The powder-insulated cryogenic liquid storage tank vacuum pumping system according to claim 6 comprises: extending an internal vacuum pumping device (3) into the interlayer of the powder-insulated cryogenic liquid storage tank, heating the inner shell to a preset temperature of the inner shell by an internal heating device, heating the outer shell to a preset temperature of the outer shell by an external heating device, and then opening a vacuum valve and a vacuum pump to perform vacuum pumping to a designed vacuum degree.

10. A method for vacuuming a cryogenic liquid storage tank based on powder insulation, characterized in that: The cryogenic liquid storage tank vacuum pumping system based on powder insulation according to claim 7 comprises: The internal exhaust device (3) extends into the interlayer of the powder-insulated cryogenic liquid storage tank; Vacuuming: Open the vacuum valve and the vacuum pump to evacuate to the first preset vacuum degree; Filling with nitrogen: turning off the vacuum pump, opening the charging valve (13), the cryogenic stop valve (18), the first heater (16), and the vaporizer (17), and filling the interlayer with high-temperature and high-pressure nitrogen to a preset pressure; and closing the charging valve (13), the cryogenic stop valve (18), the first heater (16), and the vaporizer (17); Vacuuming: Turn on the vacuum pump to evacuate to the second preset vacuum degree; Filling with nitrogen: turning off the vacuum pump, opening the charging valve (13), the cryogenic stop valve (18), the first heater (16), and the vaporizer (17), and filling the interlayer with high-temperature and high-pressure nitrogen to a preset pressure; and closing the charging valve (13), the cryogenic stop valve (18), the first heater (16), and the vaporizer (17); According to the above method, the vacuuming step and the nitrogen filling step are cyclically performed alternately, wherein the preset vacuum degree of the latter vacuuming step is higher than the preset vacuum degree of the previous vacuuming step; until the vacuum degree in the interlayer reaches the designed vacuum degree.

Images