Vacuum exhaust device

Abstract

To provide an evacuation device that is suitable for evacuation of a vacuum insulation pipe having a double structure, compact, and highly portable.SOLUTION: An evacuation device (1) evacuates a vacuum layer (7) of a housing container (C) having a double structure for housing liquefied gas, and is provided with an evacuation pipe (15) connected to the vacuum layer (7), and an ejector (17) communicating with the vacuum layer (7) via the evacuation pipe (15). The evacuation device (1) may comprise an inert gas supply source (51) connected to the evacuation pipe (15).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vacuum pumping device. [Background technology]

[0002] It has been proposed to store liquefied gases such as liquefied natural gas and liquefied hydrogen in double-walled vacuum insulated containers. One example is the use of a double-walled vacuum insulated pipe as a piping system for transferring gas between a liquefied gas carrier and a tank on land (see, for example, Patent Document 1). This insulated pipe has a structure in which an inner pipe is covered by an outer pipe with a vacuum layer in between, so that high thermal insulation is achieved and the temperature rise of the low-temperature liquefied gas flowing inside the inner pipe can be effectively suppressed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-004382 Summary of the Invention [Problem to be solved by the invention]

[0004] In vacuum insulated pipes, the degree of vacuum in the vacuum layer may decrease due to factors such as deterioration of components. This decrease in vacuum level leads to a decrease in insulation performance, which can cause the liquefied gas transported through the vacuum insulated pipe to evaporate. To maintain the degree of vacuum in the vacuum layer, it is possible to use a vacuum pump to evacuate the air at appropriate times. However, on ships and plants where liquefied gas is typically stored or transported, it is often difficult to secure space to install large equipment such as a vacuum pump. Furthermore, evacuation is not necessarily required frequently. Therefore, a vacuum evacuation device that is smaller and more portable than conventional vacuum pumps is desired.

[0005] SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide a small, highly portable vacuum evacuation device suitable for evacuating a liquefied gas container having a double structure. [Means for solving the problem]

[0006] In order to achieve the above object, the vacuum exhaust device according to the present invention comprises: An apparatus for evacuating a vacuum from a vacuum layer of a double-structure container that contains liquefied gas, a vacuum exhaust pipe connected to the vacuum layer; an ejector having a suction port communicating with the vacuum layer via the vacuum exhaust pipe; Equipped with.

[0007] According to this configuration, the vacuum exhaust is performed by an ejector that is generally small and has a simple structure, and therefore the vacuum exhaust device can be made small and highly portable.

[0008] The liquefied gas storage facility according to the present invention comprises: a double-layered container for storing liquefied gas; the vacuum exhaust device connected to the container; Equipped with.

[0009] According to this configuration, by being equipped with the above-mentioned small and highly portable vacuum exhaust device, the vacuum layer of the highly insulating double-structure vacuum insulated pipe can be evacuated at the appropriate time, thereby effectively preventing the stored liquefied gas from evaporating. [Effects of the Invention]

[0010] As described above, according to the present invention, a vacuum exhaust device for a liquefied gas container having a double structure can be made smaller and more portable. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing the configuration of a vacuum exhaust device according to an embodiment of the present invention. [Figure 2]2 is a schematic diagram showing an example of a liquefied gas storage facility to which the vacuum exhaust device of FIG. 1 is applied. [Figure 3] 2 is a schematic diagram showing the configuration of an ejector used in the vacuum exhaust device of FIG. 1. FIG. [Figure 4] 2 is a longitudinal sectional view schematically showing an example of the configuration of a double-structure pipe to which the vacuum exhaust device of FIG. 1 is applied. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Preferred embodiments of the present invention will now be described with reference to the drawings. Fig. 1 shows a vacuum exhaust device 1 according to one embodiment of the present invention. This vacuum exhaust device 1 is applied to a liquefied gas storage facility 3 shown in Fig. 2. The liquefied gas storage facility 3 includes a double-structure pipe (hereinafter referred to as "piping") 5, which is a container C for storing liquefied gas, for transporting the liquefied gas, and the vacuum exhaust device 1 that evacuates a vacuum layer 7 of the piping 5 shown in Fig. 1.

[0013] In this embodiment, as shown in Fig. 2, a ship such as a liquefied gas carrier will be mainly described as an example of the liquefied gas storage facility 3. The liquefied gas carrier is equipped with a liquefied gas storage tank (hereinafter simply referred to as a "tank") 9, which is a container C for storing liquefied gas. However, the liquefied gas storage facility 3 is not limited to a ship as long as it is a facility having the structure and function to store liquefied gas, and may be, for example, a land-based liquefied gas storage facility or a plant that uses liquefied gas.

[0014] In this specification, the term "container for storing liquefied gas" refers to a general container having a space inside which liquefied gas can be present. Typical examples of the "container for storing liquefied gas" are the above-mentioned pipes for transferring liquefied gas and tanks for storing liquefied gas, but the "container for storing liquefied gas" is not limited to these, as long as it has a space inside which liquefied gas can be present. In the following explanation, an example in which the vacuum exhaust device 1 is applied to the pipe 5 will be described, but the vacuum exhaust device 1 can also be applied to a "container for storing liquefied gas" other than the pipe 5 that has a double structure for vacuum insulation.

[0015] The piping 5 is configured as a vacuum insulated pipe having a double structure. That is, as shown in Fig. 1, the piping 5 is configured from an inner pipe 11 through which liquefied gas passes and an outer pipe 13 that covers the inner pipe 11. A vacuum layer 7 is formed in the radial gap between the inner pipe 11 and the outer pipe 13. In this specification, the term "vacuum layer" refers to the cylindrical space between the inner pipe 11 and the outer pipe 13 in the piping 5 having a double structure, which is assumed to be maintained in a vacuum state during normal operation, and is referred to as the "vacuum layer 7" even when it is not in a vacuum state due to operating conditions, etc.

[0016] 2 is stored in the tank 9 and transferred via the piping 5, for example, liquefied petroleum gas (LPG, approximately −45° C.), liquefied ethylene gas (LEG, approximately −100° C.), liquefied natural gas (LNG, approximately −160° C.), liquefied hydrogen (LH2, approximately −250° C.), and liquefied helium (LHe, approximately −270° C.). In this embodiment, liquefied hydrogen is stored in the tank 9 and transferred via the piping 5.

[0017] In this embodiment, the tank 9 is configured as a double-walled tank having an inner tank and an outer tank. For example, a vacuum layer for vacuum insulation is formed between the inner tank and the outer tank. However, the configuration of the tank 9 is not limited to this example. For example, the tank 9 may have a vacuum insulation layer filled with a powder insulation material such as perlite, which is a granular insulation material. Alternatively, the tank 9 may be a single-walled tank 9 covered with insulation material. In this case, the insulation material may be composed of, for example, multiple vacuum insulation panels or multiple foam panels.

[0018] The vacuum exhaust device 1 according to this embodiment shown in Fig. 1 is connected to the piping 5 having the above-described structure and performs vacuum exhaust from the vacuum layer 7. The vacuum exhaust device 1 includes a vacuum exhaust pipe 15 connected to the vacuum layer 7 of the piping 5, and an ejector 17 connected to the vacuum exhaust pipe 15. The ejector 17 has a suction port 19 that communicates with the vacuum layer 7 via the vacuum exhaust pipe 15.

[0019] 3, the ejector 17 includes a nozzle section 21, a diffuser section 23 that is concentrically disposed about the nozzle section 21 and downstream of the nozzle section 21, and a main body section 25 that connects the nozzle section 21 and the diffuser section 23. The main body section 25 is provided with an inlet port 19 that opens in a direction substantially perpendicular to the axes of the nozzle section 21 and the diffuser section 23. A driving fluid F is supplied through a fluid inlet 27 of the nozzle section 21, and a gas G is sucked through the inlet port 19 by negative pressure generated by the driving fluid F flowing out from the tip of the nozzle section 21 at high speed. The sucked gas G is then discharged to the outside from an outlet port 29 of the diffuser section 23 together with the driving fluid F.

[0020] 1, the suction port 19 of the ejector 17 is connected to an ejector connecting pipe 31 that branches off from the middle of the vacuum exhaust pipe 15. The ejector connecting pipe 31 is provided with a check valve 33 that prevents fluid from flowing from the ejector 17 side to the vacuum exhaust pipe 15 side. A fluid supply pipe 35 that supplies a driving fluid F to the ejector 17 is connected to a fluid inlet 27 of the ejector 17. A discharge pipe 37 that discharges the driving fluid F and gas is connected to a discharge port 29 of the ejector 17.

[0021] In this embodiment, the vacuum exhaust pipe 15 is connected to the vacuum layer 7 via a seal-off valve 39 provided on the outer circumferential surface of the outer pipe 13. The seal-off valve 39 is provided as a device for releasing pressure to the outside when a pressure increase occurs inside the outer pipe 13. In this example, as shown in FIG. 4 , the pipe 5 is formed by connecting multiple split pipes 5a in the longitudinal direction. Each split pipe 5a is provided at both ends with partition walls 41 that close the vacuum layer 7. In addition, each split pipe 5a is provided with a gate valve 43 near both ends of the inner pipe 11. By configuring the pipe 5 using a combination of split pipes 5a having such a structure, the installation of the pipe 5 is simplified and the degree of vacuum in the vacuum layer 7 can be easily maintained and controlled.

[0022] In the example shown in FIG. 1, a water ejector 17 using water as the driving fluid F is used as the ejector 17. The fluid supply pipe 35 is connected to a water intake system 45 that takes in seawater from the periphery of the liquefied gas storage facility 3, which is a ship, via a fluid supply valve 47. By opening the fluid supply valve 47, seawater flows into the fluid supply pipe 35, and the ejector 17 is driven by this seawater as the driving fluid F. However, the driving fluid F of the ejector 17 is not limited to seawater, and fresh water or compressed air, for example, can be used as the driving fluid F. A pressure gauge 49 is provided in the fluid supply pipe 35 in the vicinity of the upstream side of the ejector 17.

[0023] In this embodiment, an inert gas supply source 51 is connected to the end of the vacuum exhaust pipe 15 opposite the piping 5. The inert gas supply source 51 is connected to the vacuum exhaust pipe 15 by branching off from the connection between the vacuum exhaust pipe 15 and the ejector 17. In the following description, the gas passage portion from the connection between the vacuum exhaust pipe 15 and the ejector 17 to the inert gas supply source 51 is referred to as an "inert gas connection path 53." A first on-off valve 55 is provided in the inert gas connection path 53. A pressure gauge 57 is provided in the inert gas connection path 53 between the first on-off valve 55 and the inert gas supply source 51.

[0024] In this way, by connecting the inert gas supply source 51 to the vacuum exhaust pipe 15, it is possible to fill the vacuum layer 7 with an inert gas and reduce the pressure by utilizing the cryogenic effect before performing evacuation by the ejector 17. Specifically, when the vacuum layer 7 is filled with an inert gas having a melting point and boiling point higher than the temperature of the liquefied gas to be transported by the piping 5, the inert gas liquefies or solidifies due to the low temperature of the liquefied gas and adheres to the outer peripheral surface of the inner pipe 11. This reduces the pressure inside the vacuum layer 7, making it easier to obtain the desired degree of vacuum by evacuation by the ejector 17.

[0025] The type of gas used as the inert gas is not particularly limited as long as it can provide the cryogenic effect described above in relation to the liquefied gas to be transferred. For example, taking into consideration cost and availability, if the gas to be transferred is hydrogen, carbon dioxide (CO2) or nitrogen (N2) can be used, and if the gas to be transferred is natural gas, water vapor or the like can be used.

[0026] In addition to those described above, various other valves and pressure measuring devices may be provided as needed in the vacuum exhaust device 1. For example, in the illustrated example, a second on-off valve 59 is provided midway in the vacuum exhaust pipe 15, and a compound pressure gauge 61 is provided closer to the ejector 17 than the second on-off valve 59.

[0027] In this embodiment, at least a portion of the vacuum exhaust pipe 15 (in this example, the portion from the first on-off valve 55 to the ejector 17 side), the ejector 17, the check valve 33, and the fluid supply pipe 35 are integrally formed. Hereinafter, this integrally formed product will be referred to as the "vacuum exhaust unit U." Herein, "integrally formed" means that the components of this vacuum exhaust unit U are connected so that they do not come apart from each other during normal operation and transportation of the vacuum exhaust unit U.

[0028] Components other than those described above may be included in the components integrally formed as the vacuum exhaust unit U. Specifically, in this example, in addition to the components described above, the pressure gauge 49 of the fluid supply pipe 35, the second on-off valve 59 of the vacuum exhaust pipe 15, and the first on-off valve 55 of the inert gas connection path 53 are integrally formed as the vacuum exhaust unit U.

[0029] In this way, by unitizing the main components of the vacuum exhaust device 1, the portability of the vacuum exhaust device 1 is increased, making it easier to use the vacuum exhaust device 1 at the necessary location in the liquefied gas storage facility 3 at the appropriate time.

[0030] Furthermore, when configuring the vacuum exhaust unit U as described above, all or part of the tubular members that configure the vacuum exhaust unit U (for example, the connection portions with other tubular members) may be formed from flexible hoses. This further increases the portability of the vacuum exhaust unit U.

[0031] The location where the vacuum exhaust device 1 is installed in the liquefied gas storage facility 3 is not particularly limited. For example, the vacuum exhaust device 1 does not need to be permanently installed around the piping 5, and may be configured to be detachable from the piping 5. If the need to evacuate the vacuum layer 7 of the piping 5 does not arise frequently, the vacuum exhaust device 1 can be connected to a necessary location (for example, if the piping 5 is configured from multiple divided pipes 5a as described above, only to a divided pipe 5a with a reduced degree of vacuum) and used only when evacuation becomes necessary.

[0032] In the liquefied gas storage facility 3, the vacuum evacuation device 1 can be installed in a hazardous location, whether it is installed temporarily as described above or permanently. Here, a "hazardous location" refers to a location where there is a risk of flammable or explosive substances being present or leaking, and where explosion-proof performance and the types of equipment that can be installed are regulated by various standards. Specifically, the vacuum evacuation device 1 according to this embodiment can be installed in a type 2 hazardous location, for example, around a tank 9 (FIG. 2).

[0033] That is, the vacuum exhaust device 1 according to this embodiment is a device that performs vacuum exhaust using an ejector 17 driven by a driving fluid F such as water or air, and does not require electrical equipment, so it is not subject to regulations regarding hazardous locations. Therefore, even in liquefied gas storage facilities 3, most of which are hazardous locations, such as ships, the vacuum exhaust device 1 can be freely installed in a location suitable for vacuum exhaust.

[0034] According to the vacuum exhaust device 1 of this embodiment described above, vacuum exhaust is performed using the ejector 17, which is generally small and has a simple structure, so the vacuum exhaust device 1 can be configured to be small and highly portable.

[0035] Although the preferred embodiments of the present invention have been described above with reference to the drawings, various additions, modifications, and omissions can be made without departing from the spirit of the present invention. Therefore, such additions, modifications, and omissions are also included within the scope of the present invention. [Explanation of symbols]

[0036] 1 Vacuum exhaust device 3 Liquefied gas storage facilities 5 Double structure pipe 7 Vacuum layer 11 Inner tube 13 Outer tube 15 Vacuum exhaust pipe 17 Ejector 51 Inert gas supply source C container

Claims

1. a double-layered container for storing liquefied gas; a vacuum exhaust device connected to the container and configured to exhaust a vacuum from a vacuum layer of the container; A liquefied gas carrier comprising: The vacuum exhaust device is a vacuum exhaust pipe connected to the vacuum layer; an ejector that communicates with the vacuum layer via the vacuum exhaust pipe and performs the vacuum exhaust; Equipped with The liquefied gas carrier, wherein the ejector utilizes seawater or compressed air as a driving fluid.

2. The liquefied gas carrier according to claim 1, further comprising: The liquefied gas carrier further comprises an inert gas supply source that is connected to the vacuum exhaust pipe and that branches off from a connection between the vacuum exhaust pipe and the ejector.

3. 3. The liquefied gas carrier according to claim 1 or 2, a check valve provided between the ejector and the vacuum exhaust pipe; a fluid supply pipe for supplying a driving fluid to the ejector; Furthermore, A liquefied gas carrier, wherein at least a portion of the vacuum exhaust pipe, the ejector, the check valve, and the fluid supply pipe are integrally formed.

4. 4. The liquefied gas carrier according to claim 1, A liquefied gas carrier, wherein the vacuum exhaust device is installed in a hazardous location.

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