Offshore liquefied gas storage facility

Abstract

Provided is an offshore liquefied gas storage facility (S), which comprises: a floating body (1); a tank row (L) comprising a plurality of tanks (3) for storing liquefied gas, the tanks being installed side by side in a prescribed direction (X) on the floating body (1); and a vent mast (9) provided to each of the tanks (3). The offshore liquefied gas storage facility, wherein in a tank (3) disposed at one end of the tank row (L) and a tank (3) disposed at the other end, the vent masts (9) are each disposed at a position near the center of the tank row (L) in the prescribed direction (X), using the central position of each tank (3) in the prescribed direction as a reference.

Description

Offshore liquefied gas storage facility

[0001] The present disclosure relates to offshore liquefied gas storage facilities.

[0002] Offshore liquefied gas storage facilities such as liquefied gas carriers are generally equipped with vent masts for venting gas in order to maintain an appropriate pressure in the tanks storing the liquefied gas (see, for example, Patent Document 1). International regulations also require that cargo tanks be equipped with vent masts for venting gas, and that the vent masts be installed at least a specified distance away from crew accommodation and work areas.

[0003] Japanese Patent Application Laid-Open No. 2021-185056

[0004] On the other hand, it is convenient to locate the living and working areas, which are the crew's activity areas, in the bow or stern area in terms of simplifying the layout of various structures on the offshore facility and making effective use of space. Therefore, it is desirable to secure as large an area for the crew's activity as possible within the limited space on the offshore facility, while locating the bent mast at an appropriate distance from the activity area.

[0005] In order to solve the above-mentioned problems, an object of the present disclosure is to provide a vent mast arrangement configuration in an offshore liquefied gas storage facility that simplifies the arrangement structure on the facility and enables effective use of space.

[0006] In order to achieve the above-mentioned object, the offshore liquefied gas storage facility according to the present disclosure comprises a float; a tank row consisting of tanks for storing a plurality of liquefied gases, which are arranged in a predetermined direction on the float; and a vent mast provided on each tank or a tank cover covering the tank, wherein in the tank located at the front end of the tank row and the tank located at the rear end of the tank row, each vent mast is provided at a position closer to the center of the tank row in the predetermined direction, based on the center position of the tank in the predetermined direction.

[0007] Any combination of at least two features disclosed in the claims and / or the specification and / or the drawings is included in the present disclosure. In particular, any combination of two or more of the claims is included in the present disclosure.

[0008] The present disclosure will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are merely for illustration and explanation purposes and should not be used to define the scope of the present disclosure. The scope of the present disclosure is defined by the appended claims. In the accompanying drawings, the same reference numerals in multiple drawings indicate the same or corresponding parts. Figure 1 is a side view showing a schematic configuration of an offshore liquefied gas storage facility according to one embodiment of the present disclosure. Figure 2 is a plan view showing a schematic configuration of the offshore liquefied gas storage facility of Figure 1.

[0009] A preferred embodiment of the present disclosure will now be described with reference to the drawings. Figure 1 shows a liquefied gas storage vessel S, which is an example of an offshore liquefied gas storage facility according to an embodiment of the present disclosure. The liquefied gas storage vessel S includes a floating hull 1 and a plurality of tanks 3 (four in this example) installed in the hull 1 for storing liquefied gas.

[0010] In this specification, the term "liquefied gas storage vessel" refers to a vessel having the function of storing liquefied gas. In this embodiment, the liquefied gas storage vessel S is a liquefied gas carrier. In addition to liquefied gas carriers, the liquefied gas storage vessel S also includes, for example, liquefied gas fueled vessels and bunkering vessels that supply liquefied gas to other vessels.

[0011] As shown in Figure 2, the multiple tanks 3 are arranged so that their centers are aligned in a straight line in a plan view along a predetermined direction. Specifically, in this example, the multiple tanks 3 are aligned along the longitudinal direction X of the liquefied gas storage vessel S, which is the above-mentioned "predetermined direction." In this specification, a row consisting of multiple tanks 3 arranged in this manner is referred to as a "tank row L." For convenience, one end and the other end of the above-mentioned predetermined direction are referred to as the "front" and "rear," respectively, based on the direction of travel of the liquefied gas storage vessel S. Furthermore, as necessary, each of the multiple tanks 3 constituting the tank row L may be referred to as the first tank 3A, the second tank 3B, the third tank 3C, and the fourth tank 3D, starting from the front tank.

[0012] The liquefied gas stored in the tank 3 is, for example, liquefied ammonia (LNH ３ , about -33°C), liquefied petroleum gas (LPG, about -45°C), liquefied ethylene gas (LEG, about -100°C), liquefied natural gas (LNG, about -160°C), liquefied hydrogen (LH2, about -250°C), and liquefied helium (LHe, about -270°C). In this embodiment, liquefied hydrogen is stored in tank 3.

[0013] In this embodiment, the tank 3 is configured as a double-shell tank having an inner tank and an outer tank. The tank 3 is normally operated with vaporized liquefied gas sealed in the space between the inner and outer tanks, which serves as an insulating layer. However, the thermal insulation method of the tank 3 is not limited to this example, and the space between the inner and outer tanks may be a vacuum layer, for example.

[0014] The liquefied gas storage ship S according to this embodiment includes a structure 5 for crew activities (hereinafter referred to as a "crew activity structure"). In this specification, the "crew activity structure 5" refers to any structure in which crew members are expected to enter and perform some kind of activity. The "crew activity structure 5" includes not only living structures used by crew members for their daily lives on board, but also work structures such as a cargo machinery room where crew members enter to navigate and operate the liquefied gas storage ship S. In the illustrated example, the liquefied gas storage ship S includes a forward crew activity structure 5F provided in the bow area FR forward of the tank row L, and a rear crew activity structure 5R provided in the stern area RR aft of the tank row L. Specifically, in this embodiment, the forward crew activity structure 5F is configured as a living structure, and the rear crew activity structure 5R is configured as a work structure. These crew activity structures 5 are installed on the deck 7 (FIG. 1) of the liquefied gas storage ship S. In this embodiment, no crew activity structures 5 are provided midway between the tank rows L.

[0015] In addition, when a liquefied gas storage ship S is provided with a front crew activity structure 5F and a rear crew activity structure 5R, configuring the front crew activity structure 5F as a living structure and the rear crew activity structure 5R as a working structure is merely an example, and the type of crew activity structure 5 each of them can be determined arbitrarily. However, if the living structure is installed aft of the tank row L, the tanks 3 and their attached equipment may block the view from the living structure, so it is preferable to make the front crew activity structure 5F the living structure. Furthermore, if the working structure is a cargo machinery room, it is preferable to make the rear crew activity structure 5R the cargo machinery room, because locating it near the aft engine room where gas treatment equipment is usually installed shortens the gas piping.

[0016] The top of each tank 3 is covered by a tank cover 8. In this example, the tank cover has a shape corresponding to the shape of the top of each tank 3. However, the shape of the tank cover is not limited to this example, and may be, for example, a shape that covers the entire tank row L.

[0017] In this embodiment, a vent mast 9, which is a gas release tower that releases vaporized gas generated in the tank 3 into the atmosphere from a position higher than the tank 3, is provided on the tank cover 8 of each tank 3. Each tank 3 is provided with a safety valve, and when the gas pressure inside the tank 3 reaches the set pressure of the safety valve, gas is released from the vent mast 9.

[0018] When the tank cover 8 is shaped to cover multiple tanks 3 as a single unit, the vent mast 9 being provided on the tank cover 8 of each tank means that each vent mast 9 is provided in a portion of the tank cover 8 that overlaps with each tank 3 in a plan view. The vent mast 9 may also be provided directly on each tank. The tank cover 8 may also be omitted. In the following, when describing the position of the vent mast 9, for convenience, the vent mast 9 provided on the tank cover 8 of each tank 9 may be expressed as "the vent mast 9 provided on the tank 9."

[0019] In this embodiment, the vent masts 9 of the tanks 3 arranged at one end (the front end in this example) and the other end (the rear end in this example) of the tank row L, i.e., the first tank 3A and the fourth tank 3D in this example, are provided at positions closer to the center of the tank row L in the longitudinal direction X of the ship, based on the center position of the tank 3 in the longitudinal direction X. More specifically, in this embodiment, the vent masts 9 of the tanks 3 arranged forward of the center of the tank row L, i.e., the first tank 3A and the second tank 3B in this example, and the tanks 3 arranged at the rear of the tank row L, i.e., the third tank 3C and the fourth tank 3D in this example, are provided at positions closer to the center of the tank row L in the longitudinal direction X. In other words, the "position closer to the center of the tank row L in the longitudinal direction X" of each tank 3 means a rearward position for tanks 3 arranged forward of the center of the tank row L, and a forward position for tanks 3 arranged rearward of the center of the tank row L, based on the center position of the tank 3 in the longitudinal direction X of the ship. Furthermore, "the center of the tank row L" means the center position between the front end of the tank 3 located at the front end and the rear end of the tank 3 located at the rear end in the ship length direction X. In the following explanation, such a position of the bent mast 9 may be simply expressed as "a position close to the center" or the like.

[0020] More specifically, in the illustrated example, each vent mast 9 is disposed on the center line C of the tank row L, which passes through the center of each tank 3 in the width direction W. By disposing each vent mast 9 in this manner, it is possible to position each vent mast 9 closer to the center. However, the vent mast 9 may also be disposed at a position offset from the center line C of the tank row L.

[0021] For the tanks 3 other than the first tank 3A located at the front end of the tank row L and the fourth tank 3D located at the rear end, it is not essential that the vent mast 9 be located near the center of the longitudinal direction X of each tank 3. However, by locating the vent masts 9 of these tanks 3 near the center of the longitudinal direction X, they can be located as far away as possible from the bow section FR and the stern section RR. Note that, unlike the illustrated example, if the tank row L is composed of an odd number of tanks 3, the position of the vent mast 9 for the tank 3 located at the center of the tank row L is not particularly limited.

[0022] In this embodiment, the vent masts 9 provided on the tanks 3B and 3C in the tank row L other than the tanks 3A and 3D closest to the crew activity structure 5 are configured as manual vent masts 9M. That is, in the illustrated example, the vent mast 9 of the third tank 3C, which is the tank 3 other than the first tank 3A closest to the first crew activity structure 5 and the fourth tank 3D closest to the second crew activity structure 5, is configured as the manual vent mast 9M. Unlike this example, the vent mast 9 of the second tank 3B may be configured as the manual vent mast 9M. However, when a crew accommodation structure and other living spaces are provided as the crew activity structure 5 as in this embodiment, it is preferable to configure the vent mast 9 of the tank 3 closest to the crew activity structure 5, other than the tanks 3 located at both ends of the tank row L, on the front-to-rear opposite side of the crew accommodation structure, as the manual vent mast 9M.

[0023] Manual venting refers to the act of manually operating the connection valve to the vent mast 9 before automatic gas venting occurs due to the internal pressure of the tank 3 reaching the set pressure of the safety valve. In this specification, "configured as a manual vent mast 9M" refers to, for example, connecting a manual vent pipe 11 equipped with the above-mentioned connection valve from the tank 3 to enable manual venting. Such manual vent pipes 11 may extend from each of the multiple tanks 3 to the manual vent mast 9M, or, if common pipes 13 and 15 (described below) are provided, they may extend from the common pipes 13 and 15 to the manual vent mast 9M. In the case of the double-shell tank 3 exemplified in this embodiment, manual venting between the inner tank and the inner and outer tanks can be performed from the manual vent vent mast 9M.

[0024] Various pipes are connected to each tank 3. In this embodiment, each tank 3 is provided with multiple individual pipes connected to different portions thereof. FIG. 2 shows, as examples of the multiple individual pipes, a first individual pipe 17 connected to the first portion 3a of the tank 3 and a second individual pipe 19 connected to the second portion 3b. In the tank 3 according to this embodiment, which is configured as a double-shell tank as described above, for example, the first individual pipe 17 is a pipe connected to the space within the inner tank, and the second individual pipe 19 is a pipe connected to the space between the inner and outer tanks. The multiple first individual pipes 17 are connected to the first common pipe 13, and the multiple second individual pipes 19 are connected to the second common pipe 15. In the illustrated example, each individual pipe 17, 19 extends from each tank 3 in a direction substantially perpendicular to the longitudinal direction X of the ship. The common pipes 13, 15 extend in a direction substantially parallel to the longitudinal direction X of the ship. In this example, the manual vent pipe 11 is connected to the first common pipe 13.

[0025] As shown in the figure, in this embodiment, the arrangement order of the multiple individual pipes 17, 19 in each tank 3 is symmetrical with respect to the center of the tank row L in the longitudinal direction X. That is, in each tank 3 arranged forward of the center of the tank row L in the longitudinal direction X, in this example the first tank 3A and the second tank 3B, the first individual pipe 17 and the second individual pipe 19 are arranged in this order from the front along the longitudinal direction X, whereas in each tank 3 arranged rearward of the center of the tank row L in the longitudinal direction X, in this example the third tank 3C and the fourth tank 3D, the first individual pipe 17 and the second individual pipe 19 are arranged in this order from the rear along the longitudinal direction X.

[0026] By arranging multiple individual pipes in this manner in each tank 3 of the tank row L, the overall piping structure is simplified and the piping design work can be made more efficient. Note that the connection portions 3a, 3b and number of the individual pipes in the tank 3 described above are merely examples, and the individual pipes may be connected to portions different from this example depending on the structure of the tank 3, and the number of individual pipes may be three or more. Furthermore, it is not essential that the arrangement order of the individual pipes 17, 19 be symmetrical with respect to the center of the tank row L in the longitudinal direction X.

[0027] Although FIG. 1 shows an example of the tank 3 as an independent tank 3 formed independently from the hull 21, the configuration of the tank 3 is not limited to this example and may be any type of tank. For example, the tank 3 may be a tank formed integrally with the hull. Furthermore, the thermal insulation structure of the tank 3 is not limited to the double structure shown in the example, but may be a single structure or a triple or more multi-layer structure. Furthermore, the shape of the tank 3 is not limited to the spherical shape shown in FIG. 1. The number of tanks 3 constituting the tank row L may be two or more, and is not limited to the four shown in the example.

[0028] In the above embodiment, a liquefied gas storage vessel S has been described as an example of an "offshore liquefied gas storage facility," but the term "offshore liquefied gas storage facility" generally refers to offshore facilities that have the function of storing liquefied gas, and includes not only liquefied gas storage vessels but also offshore facilities that do not have a propulsion device. The shape of the offshore liquefied gas storage facility is not particularly limited, but the configuration of this embodiment is preferably applied to facilities that have an elongated shape in a plan view, such as the example ship. When the configuration of this embodiment is applied to offshore facilities other than ships, the "bow" and "stern" of a ship correspond to the ends of the facility on an extension line from both ends of the tank row L along the arrangement direction of the tank row L.

[0029] According to the offshore liquefied gas storage facility of this embodiment described above, the vent masts 9 are located toward the center of the tank row L for the tanks 3 located at both ends of the tank row L, so that a wide area for crew activity can be secured at the bow and stern while maintaining an appropriate distance from the vent mast 9. This allows for a simplified onboard layout and effective use of space in the liquefied gas storage ship S.

[0030] The offshore liquefied gas storage facility according to this embodiment may further include a front crew activity structure 5F provided in front of the tank row L and a rear crew activity structure 5R provided in the rear of the tank row L. With this configuration, the crew activity area on the ship can be secured at a position that maintains an appropriate distance from the vent mast 9. Furthermore, by consolidating the crew activity areas into the bow area FR and the stern area RR, it is possible to simplify the layout structure on the ship and make effective use of space.

[0031] In the offshore liquefied gas storage facility according to this embodiment, the vent masts 9 provided on the tanks 3 other than the front-end tank 3 and the rear-end tank 3 in the tank row L may be configured as manual vent masts 9M. With this configuration, the manual vent mast 9, which is used more frequently than the other vent masts 9, can be positioned at an appropriate distance from both the bow zone FR and the stern zone RR.

[0032] In the offshore liquefied gas storage facility according to this embodiment, the vent masts 9 of the tanks 3 located forward of the center of the tank row L and the tanks 3 located aft may be provided at positions closer to the center in the longitudinal direction X. With this configuration, the vent masts 9 of the tanks 3 other than the front and rear tanks 3 can also be positioned as far away as possible from the bow zone FR and the stern zone RR.

[0033] The offshore liquefied gas storage facility according to this embodiment may further include a plurality of individual pipes connected to different portions of each tank 3, and the arrangement order of the plurality of individual pipes in each tank 3 may be symmetrical with respect to the center of the tank row L in the ship's length direction X. This configuration simplifies the overall piping structure and improves the efficiency of piping design work.

[0034] As described above, the preferred embodiments of the present disclosure have been described with reference to the drawings, but various additions, modifications, and deletions can be made without departing from the spirit of the present disclosure. Therefore, such additions, modifications, and deletions are also included in the scope of the present disclosure.

[0035] DESCRIPTION OF SYMBOLS 1 Hull (floating body) 3 Tank 5F Forward crew activity structure (first crew activity structure) 5R Aft crew activity structure (second crew activity structure) 8 Tank cover 9 Vent mast 9M Vent mast for manual vent 17 First individual piping (individual piping) 19 Second individual piping (individual piping) L Tank row S Liquefied gas storage vessel X Longitudinal direction (predetermined direction)

Claims

1. A floating body, A tank row including a plurality of tanks for storing liquefied gas, the tanks being arranged in a predetermined direction on the floating body; A vent mast provided on each tank or a tank cover covering the tank; Equipped with In the tank arranged at one end of the tank row and the tank arranged at the other end, each vent mast is provided at a position closer to the center of the tank row in the predetermined direction based on a center position of the tank in the predetermined direction. Offshore liquefied gas storage facility.

2. The offshore liquefied gas storage facility according to claim 1, further comprising: A first crew activity structure provided in the area on the one end side of the offshore liquefied gas facility; A second crew activity structure provided in the area on the other end side of the offshore liquefied gas facility; An offshore liquefied gas storage facility equipped with:

3. The offshore liquefied gas storage facility according to claim 1 or 2, The vent mast provided on a tank other than the tank arranged at one end and the tank arranged at the other end in the tank row or on a tank cover covering the tank is configured as a vent mast for manual vent. Offshore liquefied gas storage facility.

4. The offshore liquefied gas storage facility according to claim 1 or 2, In the tank arranged on the one end side of the tank row from the center thereof and the tank arranged on the other end side thereof, each vent mast is provided at a position closer to the center of the tank row in the predetermined direction, based on a center position of the tank in the predetermined direction. Offshore liquefied gas storage facility.

5. The offshore liquefied gas storage facility according to claim 4, further comprising: With multiple individual pipes connected to different parts of each tank, The arrangement order of the plurality of individual pipes in each tank is symmetrical with respect to the center of the tank row in the predetermined direction. Offshore liquefied gas storage facility.