KR20100102139A - A liquefied gas tank with a central hub in the bottom structure - Google Patents

Abstract

The present invention comprises a tank for liquefied gases or a so-called cryogenic tank (1) with a tank bottom structure (10) and a tank wall structure (11) arranged around a circumference of said tank bottom structure (10), said tank bottom structure (10) provided with a tank bottom hub (2) adapted for being held by a bottom hub retainer (20) on a tank support structural floor (23). The tank is simple to install, cheap in production and handles in an improved manner forces acting on it.

Description

A LIQUEFIED GAS TANK WITH A CENTRAL HUB IN THE BOTTOM STRUCTURE}

Global energy demand requires that large amounts of fuel be transported to consumers from the areas where they are found. One of the cleanest and most abundant energy forms currently in use is natural gas. Since the main gas producer is usually located far from the main consumer market, there is a need to transport gas from the producer to the consumer. Pipeline transportation is one of the possibilities that can be considered, but it is very expensive to install piping and not suitable for long range transportation. Therefore, ship transport is a practical solution for gas delivery applications, in particular for the delivery of liquefied gas.

Although the term cryogenic tank is commonly used herein, the present invention relates generally to liquefied gas tanks, such as LNG tanks or LPG tanks. LNG is maintained in the tank at a boiling point of about -163 ° C at atmospheric pressure and constantly evaporates methane. To reduce evaporation, it is possible to reduce heat ingress through the tank wall by placing an insulating layer around the tank wall. The tank walls must be structurally supported and stabilized, but all of these structural support components can induce unwanted evaporation by introducing heat into the tank. Thus, it is desirable to reduce the total cross section of the structural support component extending through the insulating layer to reduce heat entry. Common problems with LNG tanks and other cryogenic tanks are the heat shrinkage that occurs during initial cooling and tank filling, and the possibility of thermal expansion of the tank when LNG is removed from the tank by evaporation or withdrawal.

LNG tanks are often retrofitted on pre-made vessels or tanks, but equipment such as floating production and storage units (FPSOs) and floating storage and regasification units (FSRUs). It can also be installed directly on the. In these applications, simple installation is required to save costs, and deck space may be used. In addition, many cryogenic tank applications on land are used in industry. Various applications represent various problems to be solved, some of which are related to gas temperature, volatility and toxicity. Many tank designs have been proposed for these applications, all of which have advantages and disadvantages.

When performing the cryogenic filling process, the bottom plate structure and tank wall structure of the tank will shrink when the tank is cooled from ambient temperature. The lower part around the bottom plate structure and the tank wall structure will first shrink, and then through the heat conduction and contact with the liquid and the evaporated gas directly with the wall while the tank is filled with liquid natural gas, the tank wall Will cool and shrink. Especially in some marine tanks, as well as in LNG ship tanks, there is a need to prevent lateral movement of the tank with respect to the substrate during cooling. In marine tanks, this lateral stability during navigation is important. The cryogenic inner tank needs to be designed to withstand the heat shrinkage of the tank relative to the support. This occurs due to the low temperature of the cryogenic fluid which naturally lowers the temperature of the tank itself and of the support on which it is fixed. In addition to the shrinkage of the tank that occurs while filling the tank with cryogenic fluid, there is a corresponding expansion of the tank when the tank is empty.

Various heat shrinks can induce deformation in tank wall liner plates, tank wall girder structures, and support compartment structures. Deformation of the LNG tank liner plate can result in cracks that can cause fatal LNG leakage due to the risk of fire and explosion and the toxicity of methane. In addition, tank breakage and the resulting leakage of cryogenic gas in vessels can cause serious losses to ships because the structural steel of such ships is not designed to be exposed to such low temperatures.

In ships and other ships, there are important problems associated with the rocking of LNG due to the action of waves on the ship or the movement of the ship itself. Slump can induce the destruction of the tank, so the tank must be designed to withstand the effects of slump. The present invention discloses a practical solution to some of the problems described above.

U.S. Patent 2905352 describes an early attempt to form a stable tank system arranged to be placed in the hull, which is fixed inside the vessel while also allowing the tank to contract and expand in response to temperature changes. Under the tank, a tank is arranged on the ship floor, with a guide disposed on the ship floor, including a longitudinally arranged slot extending in the longitudinal direction of the ship, and having a corresponding key fixed to the tank bottom plate and fitted in the slot. Positioned to be positioned.

 U. S. Patent No. 3612333 discloses further advances in the principles shown in U. S. Patent No. 2905352, described above, wherein a key, keyway and bearer support are located at the bottom of the vessel and the key is a tank. Is located on a line corresponding mainly to the longitudinal and transverse centerlines of the.

 “Support for LNG ship tanks” in US Pat. No. 4013030, issued to stafford, describes a tank support system located around a circular horizontal cross section of the tank. The support system comprises a number of identical support units spaced around the circular horizontal cross section of the tank. Each support unit is coupled to the tank and also to the base. Each support unit has a bottom hub disposed on the corresponding cylindrical sleeve. The sleeve is disposed on the ship's undercarriage to allow radial movement relative to the tank but no lateral movement. This allows the tank to contract and expand, preventing the entire tank from moving laterally.

U.S. Pat.No.5531178, entitled "Support Structure for Self-Storage Tanks in Liquefied Gas Transporters," to Abe et al. Discloses a prismatic tank for liquefied gas, the tank being a tank. Is arranged in a tank compartment having a bottom support below the tank that causes it to expand and contract laterally. The support structure includes a longitudinal movement limiter along the transverse line that prevents the entire tank from moving in the bow and bow direction of the ship, and a lateral line arranged along the centerline of the ship to prevent the tank from moving in the transverse direction. Lateral movement limiters are provided. There are a number of support points arranged to support the tank, which design greatly complicates the installation of the tank. It is believed that the support increases the design weight and that the support is arranged in an asymmetrical manner. This lack of symmetry will result in non-uniform stress distribution during cooling. In addition, this design will transfer moment loads to the ship structure.

U. S. Patent No. 6971537 discloses a support device for a semi-membrane tank wall, wherein the support assembly provides vertical support for the tank wall while allowing relative movement in the horizontal direction. This design will result in significant point loads in all undesirable tank walls. The design is complex and expensive, increasing installation time and cost and increasing the difficulty of converting older ships to LNG carriers.

German patent 1506761 discloses a method for transporting LNG, wherein a plurality of tanks are arranged as a single unit in the hull, the unit being supported by a plurality of column bases, some of the column bases being It is arranged around the periphery of the tank and there is at least one central column base. This design requires a bulkhead across the hull capable of handling the roll load at the top of the tank. This increases weight and cost and complicates the structure of the tank.

German patent no.1781041, entitled "Tank Vessel for Transporting Liquefied Gas", is a columnar tank in which the longitudinal movement limiter is arranged below the center of the tank and the lateral movement limiter is arranged below the fore and aft center of the tank. A support structure for a is disclosed in a similar manner. The space between the support structure portion of the restrictors and the tank bottom structure of the restrictors is configured to receive a locking pad, which is locked in place while the tank is retracted during the cooling process when filled with liquefied gas. There is also a lateral movement limiter provided with such a locking pad along the side and side sides of the tank compartment when it is cooled to engage the tank with the support structure. This is a very complex design and requires very precise machining to achieve the required tolerances. Thus, the tank will be very expensive. In addition, this design will deliver uncontrollable and somewhat unpredictable loads from the tank to the vessel structure.

The present invention is directed to solving at least some of the above technical problems, comprising a tank for liquefied gas having a tank bottom structure, the tank bottom structure supporting a tank wall structure arranged around the periphery of the tank bottom structure, The bottom structure is provided with a central tank bottom hub configured to be held by a bottom hub retainer on a tank support structure floor, the central tank bottom hub to provide radial support in a direction parallel to the tank bottom structure. Are arranged.

Other embodiments of the invention are given in the dependent claims.

The first advantage of the present invention is that all supports of the liquefied gas tank in the lateral direction are guided through the central hub, so that the lateral supports of the cryogenic tank are not needed and thus "cold" through an insulating layer surrounding the tank wall. bridge) ", so that the insulation is more continuous and easier to install. In addition, the insulation is more easily removed if necessary for reasons such as repair or modification of the tank or inspection of the tank compartment or tank.

A second advantage of the present invention is that during the cooling of the cryogenic tank all shrinkage of the tank to the tank compartment will occur generally radially for this single hub since the tank is fixed at only one origin via the central hub. Radial expansion or contraction is allowed by a vertical retainer arranged for the tank bottom structure, which facilitates the mechanical adaptation of the cryogenic tank to the tank compartment and the heating of the cryogenic tank to ambient temperature. No particular consideration is needed to construct the lateral support along the cryogenic tank wall, which makes the cryogenic tank of the prior art difficult.

A third advantage of the present invention due to the vertical retainers arranged along the periphery of the tank bottom structure is that the tanks due to the sloshing of the cargo, rolling, pitching and even grounding or crashing of the cargo The vertical force from the wall is directed downward from the lower part of the wall structure, generally straight down through the rim of the bottom plate structure, into a vertical retainer fixed to the tank support substructure of the ship. Thus, undesirable shear forces in tank bottom structures (and wall structures) generated in prior art tanks are greatly dissipated.

A fourth advantage of the invention is that in an embodiment having a vertical retainer arranged circumferentially at the outer ends of the beam of the tank bottom structure, the tank bottom structure may have a beam structure arranged on top of the bottom liner plate, and the ship It is possible to provide a lower center of gravity of the cryogenic tank in the interior, and also to provide an expanded tank volume compared to a tank with an external beam structure.

Another advantage of the columnar tank according to the invention is that the tank volume can be significantly increased compared to the vertical cylindrical tank. Typical cylindrical tanks can hold about 18000 m ³ , while prismatic tanks can be designed to utilize the vessel cross section and can also be made along a larger portion along the main axis of the vessel so that the prismatic tanks It is limited to the same cross section but can be generally manufactured to hold about 35000m ³ .

The invention is illustrated in the accompanying drawings.
1A is a schematic illustration of a cylindrical embodiment of a tank for liquefied gas, according to the present invention, hereinafter referred to as cryogenic tank, showing the tank slightly below the tank bottom structure from the side of the tank.
1B is a perspective view of a columnar embodiment of a cryogenic tank according to the invention, showing the tank to the side slightly above the tank and the longitudinal axis of the vessel.
1C is a schematic illustration of a columnar embodiment of a cryogenic tank according to the present invention, in which the tank is shown in an isometric view from below slightly showing the main elements of the bottom plate structure of this columnar tank.
2a is a schematic vertical cross section through the bottom structure of a tank according to the invention with the tank resting on a tank support structure floor in a tank compartment; In this embodiment, the bottom tank structure is a so-called external mechanical structure with a bottom liner plate disposed on the top end of the beams of the bottom structure.
FIG. 3A is a schematic vertical cross-sectional view through a tank of the invention where the cylindrical wall liner plate is supported by a vertical girder disposed on the ends of the radial beams of the tank bottom structure, as in FIG. 2A, wherein the cylindrical wall and bottom wall structures It is insulated from the tank compartment bottom and walls.
FIG. 3b is a perspective view corresponding to FIG. 2 and shows the so-called inner beam wall structure standing up on the outer structure tank bottom structure. FIG.
4 is a vertical sectional view of the lower part of the simplified tank according to the invention, illustrating a vertical retainer disposed radially to prevent the periphery of the tank bottom structure from rising from the tank support structure forming the bottom of the tank compartment; do.
5A is a perspective view of an exemplary vertical retainer with arms arranged for retention on the lower flange of the radial beam of the floor structure.
5B illustrates an inverted “U” shaped bridle clamp vertical support attached to the tank support substructure and disposed over the outer end portions of the horizontal beam of the tank bottom structure, and a corresponding perspective view of the exemplary vertical retainer. And the end portions extend beyond the outer surface of the tank wall.
6a is a perspective view from below the horizontal plane of an embodiment of a tank according to the invention with an anti-rotation retainer for the radial beam structure of the tank; Here, the anti-rotation retainer is disposed approximately halfway in the radial direction from the center of the cylindrical tank.
6b is a similar perspective view from below the horizontal plane of another embodiment of a tank according to the invention with an anti-rotation retainer disposed near the maximum beam length as calculated radially from the cylindrical tank center.
7A is a perspective and cross-sectional view of the hull of a ship showing a cross section of an insulated cryogenic cylindrical tank according to the invention and a vertical cylindrical tank compartment centered on a central longitudinal bulkhead.
FIG. 7B is a perspective and sectional view of the hull of a ship, showing a series of columnar tank compartments along the centerline of the ship and an insulated cryogenic columnar tank according to the present invention;
8 illustrates shear forces that may occur in horizontal beams in prior art tank bottom structures when the bottom structure is secured in position along the bottom structure and is subjected to an uncorrected lifting force acting on a wall standing up on the end of the beam. Illustrated. This uncorrected shear force in the tank bottom structure is greatly eliminated through the present invention.
9A is an enlarged view of the armed vertical retainer for the beam, which corresponds to the armed vertical retainer of FIG. 5A, with the beam only partially shown in cross section of the lower flange.
FIG. 9B is an enlarged view of the armed vertical retainer for the beam, which corresponds to the inverted “U” shaped bridal clamp vertical retainer of FIG. 5B, with the outside of the beam shown, with a portion of the rest as dashed lines. FIG. Is shown.
10 is an illustration of an anti-rotation support of a radial beam.
11A is a simplified design diagram of the bottom structure of a cylindrical tank according to an embodiment of the present invention showing a central hub of the tank bottom structure, the radial H-beams supporting the bottom liner plate of the tank, and the cylindrical wall structure An H-beam extending upwards near the outer end of the radial beam of the bottom structure and extending almost circumferentially spans between the radial beams. The armed vertical retainers are arranged near the outer end to hold horizontal beams, and several series of such armed vertical retainers of shorter radial positions are arranged closer to the central hub.
11B is an almost similar design diagram of the bottom structure of a cylindrical tank according to an embodiment of the present invention using only an inverted “U” shaped bridal clamp vertical retainer to maintain the outer end of the beam of the tank bottom structure. This design is a simpler and clearer embodiment of the present invention corresponding to that illustrated in FIGS. 4 and 5B. The vertical retainers of FIGS. 11A and 11B may also serve as anti-rotation retainers for rotational moments about a vertical axis passing through a central hub or tank.
11c is a perspective view from below of the bottom structure of the cryogenic tank according to the invention and along a central radial beam. The tank is columnar but the tank bottom beam structure and the vertical retainer correspond greatly to the tank bottom structure shown in FIG. 11A.
12A and 12B are perspective views of the action force (white arrow) acting from the tank and the corresponding reaction force from the tank support system. The central hub transmits the force acting along the beam of the tank bottom structure, the anti-rotation retainer transmits the rotation moment, and the vertical retainer transmits the vertical force.
13 illustrates various translational and rotational movements of the ship.
FIG. 14A shows an enlarged side and bottom view of an embodiment of the present invention showing an armed peripheral vertical support. FIG.
14B shows an enlarged side and bottom view of an embodiment of the present invention showing an inverted " U " shaped bridal clamp peripheral vertical support.
FIG. 15A shows a simplified vertical through section of a tank bottom structure according to a preferred embodiment of the present invention with a female central hub welded between the inner ends of the radial beam, with the central hub supporting the beam to hold the tank. It enters onto a male central hub that is secured within the framework of the structure.
FIG. 15B shows a simplified vertical through section of a tank bottom structure of an alternative embodiment of the present invention having a male central hub welded between the inner ends of the radial beam, with the central hub having a support beam structure to hold the tank. It enters into the female central hub retainer, which is secured within the framework of the body.

The present invention includes a tank 1 for liquefied gas, such as liquefied methane (LNG), liquefied ethane, liquefied propane (LPG) or other liquefied gas. The tank 1 according to the invention is for use on a ship or other ship. The term vessel or vessel as used herein further includes floating or semi-immersed crude oil production or storage vessels. The tank according to the invention can also be arranged on a stationary offshore structure. While the disclosed tanks are designed for use under atmospheric pressure, pressurized tanks may also be considered. The tank according to the invention is hereinafter generally referred to as cryogenic tank 1, but the invention is not limited to tanks for cryogenic temperature ranges, but to liquefied gases such as those described above. The tank 1 for liquefied gas has a tank bottom structure 10 and a tank wall structure 11 arranged around the periphery 15 of the tank bottom structure 10. The wall column beam 12 is arranged to constitute part of the tank wall structure 11. The tank wall structure 11 generally supports the tank top end. The tank bottom structure 10 has a tank bottom hub 20 generally arranged in the center, the bottom hub 2 being configured to be held by the bottom hub retainer 20 on the tank support structure floor 23 ( 1, 2 and 7). Tank hub 20 may provide support in directions generally parallel to the plane of tank bottom structure 10.

The tank 1 according to the invention allows the tank to be held via a single point hub 2 of the tank bottom structure 10, which hub 2 is a hub retainer 20 on the tank bottom support structure 23. Is held by).

Heat shrinkage movement of large vessel tanks from ambient temperature to cryogenic temperatures can be of significant size. The inherent advantage of the tank, which prevents lateral movement through lateral fixation through one central hub, is that the tank is held only at one point and the rest of the structure, such as the beam 3 of the tank bottom structure 10, Since it expands or contracts in directions extending through the hub 2, it is a fact that during deformation the tank is initially filled with liquefied gas, there is little or no thermal strain accumulated during cooling.

Ships are affected by six translation and rotational degrees of freedom: rolls, pitch and yaw for rotational movements, heaves, surges and gears for translational movements. (See Figure 13).

According to the invention, the hub 2 provides support for forces acting on the lateral plane on the tank, which hub 2 alone is the side required for the tank hub retainer 20 on the tank support structure 23. Provide directional plane force. This is an improvement over previous designs having a plurality of keys, slots and the like and each key or slot is arranged to provide support in only a single direction. The hub 2 should be arranged generally close to the center of the tank bottom structure 10 to avoid unbalance of the hub. Another advantage of this design is that thermal expansion / contraction translation is at most along half the dimensions of the tank bottom structure and does not occur along the entire length or diameter of the tank bottom structure. The tank bottom structure 10 may consist of one dense piece of material, such as concrete, or the tank bottom structure 10 may preferably be constructed using a radial beam 3 as described below.

In a preferred embodiment of the invention, the beam 3 supports or holds the fluid sealing bottom liner plate 113 of the tank 1 and extends horizontally and radially from the central hub 2. The vertical girders 12 are raised from near the outer end of the radial beam 3 and support the liner plate 111 of the tank wall structure 11 of the tank 1. The radial beam 3 distributes the forces acting on the tank throughout the tank vessel and provides support for the tank floor. This is important because there is considerable slack due to forces acting on the tank 1 such as rolling and pitch when the tank is in a partially filled state. This is especially a problem when the tank 1 is mounted on a floating vessel or LNG carrier such as FPSO or FSRU. Slump can also occur due to seismic events in land-based cryogenic tanks, and it is desirable to provide a tank that can withstand seismic induction forces (which may be due to horizontal seismic acceleration close to 1 g) and the resulting slump. It is important.

Lateral forces between the tank support floor 23 of the ship 30 and the LNG fluid load due to relative acceleration due to rolls, pitches, surges and gears must be transmitted in particular through the tank wall structure 11, Reaction forces from LNG cargoes will occur due to roll and pitch acceleration. As mentioned above, this is especially a problem in the case of ships. Within a wide range of rolls, pitches, surges and gears, the bottom hub 2 held by the hub retainer 20 on the tank support structure 23 holds the tank 1 in place. In other words, the tank bottom structure 10 is supported in the vertical direction by the general structure under the tank, ie the tank support bottom 23. The support bottom 23 can be constituted by the longitudinal center frame bulkhead and the lateral arrangement of the ship's lateral frame, together with the transverse bulkhead frame. Compartment bottom 23 includes the tank hub retainer 20. The compartment bottom 23 also includes a bottom liner plate on the framework, the bottom liner plate for supporting the bottom insulation layer below the LNG tank, the insulation layer being provided by the hub retainer 20 and the central hub, and It is possibly penetrated by other types of retainers described below, and possibly by piping.

As shown in FIGS. 1A and 1B, the cryogenic tank 1 may be arranged in a tank slot compartment having a wall 24. Although a cylindrical tank is illustrated in FIG. 1A, other shapes, in particular, such as any kind of footnote shape, consisting of a rectangular shape as illustrated in FIGS. 1B, 1C and 11C are contemplated within the scope of the present invention. The choice of shape is a design issue, although it focuses on the design of the ship itself and not on the present invention. By way of example, one may consider a spherical tank provided where the bottom portion of the tank wall structure has been removed and mainly replaced by a flat tank bottom structure. This tank bottom structure 10 can be arranged in the central hub 2 and possibly in a radially arranged beam 3 according to an embodiment of the invention. Details of the arrangement of the cryogenic tank 1 arranged in the ship are shown in FIGS. 2A, 7A and 7B and 11A, 11B and 11C. FIG. 2A further illustrates some of the details shown in FIG. 1, such as the tank hub retainer 20 of the vessel on the vessel tank bottom 23 of the tank slot in the vessel. 3 illustrates further details such as bottom insulation 8, cylindrical wall insulation 18 and vertical tank axis 9. The vessel tank slot bottom 23 functions for a variety of purposes, however, one of the main advantages of using this system is that the tank is prefabricated onshore and simply lifted up in one operation to ship onto the hub retainer 20. Can be lowered into the tank slot. This greatly facilitates the installation of cryogenic tanks in ships. There are significant advantages when many FPSU and FSRU vessels are modified surface vessels. Thus, changes in the structure of the vessel and the cryogenic tank can be made simultaneously but not sequentially. In the same way, if the tank needs to be removed for maintenance, the cryogenic tank can simply be lifted off the ship. This is in stark contrast to expensive and difficult maintenance of LNG tanks as is known in the background.

A significant advantage of the inner beam structure of the tank bottom structure as illustrated in FIG. 1B is that the bottom liner plate is at the bottom, thus increasing the tank volume while keeping the center of gravity of the tank low, providing both economic and safety advantages. will be.

Lateral forces between the vessel and the liquefied gas are radially transmitted by the present invention through the central hub 2, through the entire bottom structure 10, as compression and / or tensile forces through the bottom plate structure, and further, It is transmitted as shear force from the tank bottom structure 10 into the tank wall structure 11 which is standing upright around the periphery of the bottom plate structure 10. The force transmission for the tank structure according to the invention is estimated to be better distributed throughout the tank structure, and therefore, especially at the lower peripheral transition between the tank bottom liner plate 113 and the tank wall liner plate 111. Prevents the formation of cracks; Thus, in particular the deformation due to rolling, pitching and consequent rolling can be reduced in the tank according to the invention compared to the prior art.

According to one embodiment of the invention, the tank bottom structure 10 comprises a radial beam 3 having radially inner ends attached to at least three, preferably four or more said central hubs 2. . The radial beam 3 supports in the preferred embodiment of the present invention a vertical girder 12 extending from near the outer end of the radial beam 3. The impervious liner plates 131, 111 preferably form an impermeable tank liner of the tank bottom and tank wall structures 10, 11. Liner plates are attached to the beam and girder 3, 12 structures. The tank wall structures 11 and 12 may be reinforced in a circumferential direction by a bar, strip or wire, or may be provided with hoop windings such as wire or glass fiber, aramid fiber, carbon fiber, etc., and the tank corresponds to the bottom circumference. It may be provided with an upper end having a peripheral edge. The upper end of the tank according to the invention does not require any lateral retainers since all translational and rotational action-reaction forces are transmitted through the bottom plate structure.

The central hub 2 is essentially not arranged to hold the tank 1 from moving in the vertical axial direction. Although this vertical retaining function through the central hub 2 can be considered as illustrated in FIG. 8, this retaining function is indirect with respect to the tank wall structure 11 and the beam of the bottom plate structure 11. It involves the transfer of normal forces from the tank wall structure 11 via unintentional vertical shear forces in (3).

The center tank hub 2 and its corresponding tank hub retainer 20 preferably only handle forces in the horizontal plane at the neutral position of the vessel. According to one embodiment of the invention, the transfer of upward force on the tank wall structures 11, 12 to the tank recess bottom 23 of the ship is carried out by the tank support recess bottom support structure 23 and the tank bottom structure. It is carried out via a vertical force retainer 4 arranged between the periphery 15, preferably the outer portion 35 of the beam 3 of the tank bottom structure 10. In one embodiment of the invention, the vertical force retainer 4 comprises a base plate welded or otherwise attached to the lower structure 23, the standing support plate is welded on the base plate, the standing support plate being the An arm 41 is provided for reinforcing the lower lateral flange of the flatly arranged H-beam cross section of the radial beam 3. This is illustrated in Figures 5A, 9A, 11A and 11C, 12A and 14A. The plate with the arm 41 can be welded in place after the tank is lowered to its correct position on the hub retainer 20 in the compartment. Although H-beams are shown, it is clear that any suitable beam structure can be used.

In another embodiment of the invention, the vertical force retainer 4 comprises a base welded or otherwise attached to the lower structure 23, the standing support plate being welded on the base plate, the standing support plate being horizontal radial An inverted “U” shaped bridge or arc 42 for reinforcing the outer portion 35 of the beam 3. This is illustrated in Figures 5B, 9B, 11B, 12B and 14B. The inverted " U " shaped vertical retainer plate 42 can also be welded in place after the tank is lowered to its correct position on the hub retainer 20 in the compartment.

5a and 5b show that the vertically directed flotation force occurring in the tank wall structures 11, 12 is offset by a vertical force retainer 4 arranged just below the tank wall structure 11, and the support structure of the ship. (23) illustrates that it is guided. Thus, forces such as rocking forces, roll forces and roll accelerations, which can be severe in the rough, or due to accidents or from tilting resulting from load movement, are at least up to a predefined static angle, and a full tank For example, it is offset by an inclination of up to 30 ° with respect to the side of the porthole.

Based on the above, in short, the tank according to the invention is held in place laterally through the use of a central hub in the bottom plate structure, as shown in FIG. 4, and the cylindrical tank towards the lower tank support structure. It can be described that it is prevented from leaving or collapsing the lower structure by a vertical force retainer that suppresses the lower rim of the wall. This will prevent the tank from being damaged by the roll, pitch, surge and gear movements of the ship, including actions and reactions due to collisions and groundings.

The specific structure shown schematically in FIG. 9 will allow the longitudinal movement of the beam due to the radial heat shrinkage of the beam 3 and the unwanted of the tank bottom structure 10 relative to the underlying supporting undercarriage 23. It can also be used to prevent relative rotational movement. Such rotational acceleration may increase due to the ship's turning and yaw, ie waves that increase the ship's rotation about its vertical axis. Such rotational movement of the tank 1 relative to the vessel can be counteracted through the application of the anti-rotation retainer 16 (see FIGS. 6, 10, (FIGS. 11A, 11B, and 11C)). Various forces acting on the ship are shown in FIG. 13. The principle of how the tank functions as well as the offset force is also shown in FIG. 12.

The anti-rotation retainer 16 comprises vertically arranged lateral retainer surface plates 17 extending parallel to the radial beam 3, which surface plates lie on the lateral surface of the radial beam 3, It has a bottom slide support 28 for vertically supporting the lower flange 14 of the beam 3, the slide support 28 must also have thermal insulation properties.

An advantage of the embodiment shown in FIG. 6A is that the anti-rotation retainers 16 are separated from the tank hub 2 and their roles are separate. The tank hub 2 prevents any translational movement between the tank 1 and the hub retainer 20 on the vessel's structural tank support floor 23, and the anti-rotation retainer 16 rotates the tank relative to the vessel. Prevent it. Such rotational force can be induced by turning the ship, intermittently turning the ship through the yaw motion caused by the waves of the ocean, or through rocking.

The embodiment of the invention shown in FIG. 6B has the following advantages. The position of the anti-rotation retainer 16 as shown in FIG. 6A can be moved beyond the lower rim 15 of the tank bottom plate 13. The beam structure is internal, so that the bottom plate can be arranged welded to the lower part of the horizontal beam 3, leaving only the tank hub 2 forming a notch in the bottom plate.

In addition, the anti-rotation retainers 16 arranged as shown in FIG. 6B provide two additional advantages. First, they are arranged at the maximum radius of the tank, so they do not need to be as rigidly designed as the retainer shown in FIG. Secondly, they are arranged at points in the structure near the end of the beam having a generally equal major radial distance Rmaj from the center of the tank, and are vertical beams that provide most of the rotational moment of the tank just below the tank wall 11. And (12). Thus, the retention of the rotational moment through the anti-rotation retainer 16 near the radial end of the radial beam 3 as shown in FIG. 6B is similar to the middle of the radial beam 3 as shown in FIG. 6A. It will cause the radial beam 3 to have a smaller bending moment than the arrangement of the anti-rotation retainers 16 arranged at the minor radial distance Rmin. The same discussion is valid for the vertical retainers 4, 42 shown in FIG. 11B. They are located at the maximum radial distance from the center of the tank bottom structure (ie tank hub 2), especially in relation to the longitudinal axis of the ship, than with other tank supports or retainer structures arranged closer to the tank center. It can withstand greater rotation moments. Vertical tank retainers, such as those shown in FIG. 11B, provide the tank with the same moment of force as the tank retainers arranged higher on both sides of the tank wall, while the mechanical and thermal considerations of such retainers Has no disadvantages

In general, the arrangement of the anti-rotation retainer 16 located at the radial distance Rmaj beyond the tank wall 11 and the tank bottom 13 provides a lower array tank bottom plate structure, thus providing a larger tank volume and lower It can provide better anti-rotation force moments than anti-rotation retainers arranged closer to the weight and center hub 2, and also provide less structural penetration of the thermal insulation layer below the tank bottom. In general, the anti-rotation retainer 16 constitutes a radially opposite pair with respect to that shown in FIG. 6B, so that no moment will be induced in the tank hubs 2, 20. The inverted “U” shaped vertical retainer of FIG. 11B also provides an internal structural bottom plate structure 10 and thus provides a lowering of the tank bottom liner plate 113 to increase the tank volume in the same manner as described above. .

8 shows why it is necessary to arrange the vertical retainer near the periphery of the tank so that the moment arm between the vertical force from the tank wall and the retaining vertical force acting on the bottom structure is shortened. If the moment arm acting on the tank bottom structure through the tank wall as shown is undesirably large, shear forces may cause breakage of the tank bottom, resulting in cracks and leakage.

The above mentioned tanks according to the invention should have operational advantages at sea. The heat transfer is kept low due to the fact that any support block or retainer is required only near the bottom plate of the tank, and no structural parts need to cross the insulation layer at a higher level than the bottom plate of the tank, so that the entire wall structure 11 The surrounding thermal insulation layer may be continuous. This also simplifies the structural design of the cryogenic tank.

An additional logistical advantage arises from the fact that it is possible to build one or more tanks according to the invention as described above, while at the same time constructing a vessel with a compartment recess arranged to receive a tank according to the invention. The tank 1 according to the invention can be lowered into the recess and the central hub 2 is introduced onto the hub retainer 20. The vertical force retainer 4 and the possible anti-rotational retainer 16 may be prepared to receive the radial beam 3 and inverted “U” shaped bridles to surround the radial beam 3. It can be completed by welding "U" -shaped bridles or arms 41.

As an alternative to using the vertical force retainer 4 to surround the outer portion of the radial beam 3, the bottom plate structure 10 and the beam 3 are oriented radially to be joined by the vertical retainer 4. It can be surrounded by a rail 19. This arrangement may enable relative rotational movement of the cryogenic tank, the possible structure of which is shown in FIG. 4.

According to one embodiment of the invention, the vertical retainer 4 may be arranged in the form of a wedge 42 arranged on the wall 24 of the tank compartment 25 (shown in FIG. 4) and the wedge 43 ) Pivots in and out of the compartment wall 24 to block the outer end 35 of the beam 3 of the tank bottom structure 10 when the tank 1 is in place. Such wedges 42 can be controlled from the outer space around the tank compartment 25 to facilitate installation and removal of the tank on the vessel. This further reduces the requirement for the space around the tank bottom structure 10 and the periphery of the tank bottom structure 10 and can be improved so that the available tank volume of the internal structure tank is lowered into the tank slot in the vessel.

An advantage of the present invention is that the central hub 2 of the tank is in a small range compared to the range of the tank bottom structure 10. Thus, the overall thermal contraction or expansion during the cooling or heating of the central hub 2 is relatively negligible when compared to the widespread contraction or expansion caused by the entire tank bottom structure as compared to the compartment bottom when the tank is cooled or heated. something to do. The small range of the tank hub 2 will allow the tank hub to be retained in the single point retainer 20 even when it is heated, allowing the vessel to sail in an empty tank, which is cryogenic according to DE 1781041. Operation that may not be possible in tanks.

Thus, the tank according to the present invention solves some problems related to thermal contraction, lateral retaining, longitudinal retaining, sloshing load force, dispersion of forces induced by rolling, and the safety of cryogenic tanks. do.

Usually, an inner tower is arranged in a cryogenic tank, the tower uses vertical pumps and valves to support vertical pipes for filling and discharging LNG or other liquid into and out of the tank. Such other liquids may be nitrogen, carbon dioxide, LPG, and gas condensate. In the embodiment of the present invention, the bottom hub 2 and the hub retainer 20 themselves may provide a passageway for the inlet and / or outlet of the cryogenic liquid, thereby providing an easy way for the tank to be filled or emptied.

14a and 14b show, in a bottom view and in an enlarged view, an embodiment of the invention showing an enlarged peripheral vertical support 4 arranged along the periphery of the tank to surround the lower flange of the radial beam 3. One anti-rotation retainer 16 may not be necessary. This arrangement will be easy to manufacture, inspect, and install and may allow for a flat bottom of the tank compartment.

15a shows a simplified vertical cross section of a tank bottom structure according to a preferred embodiment of the invention with a female central hub 20 welded between the inner ends of the radial beam 3, the central hub being a tank 1. ) Is introduced onto the male central hub retainer 20 fixed to the framework supporting the beam substructure 23. The advantage of the female central hub 2 of FIG. 15A is that a smaller bending moment is induced in the tank bottom structure 10 than the other male central hub 2 'shown in FIG. 15B below.

FIG. 15B shows a simplified vertical cross section of a tank bottom structure of another embodiment of the invention with a male central hub 2 ′ welded between the inner ends of the radial beam 3, the central hub 2 ′ being It enters into the female central hub retainer 20 'which is fixed to the framework supporting the beam substructure 23 to support the tank 1.

Claims (23)

In the tank (1) for liquefied gas having a tank bottom structure (10) supporting the tank wall structure (11),
A central hub 2 in the tank bottom structure 10, the central hub 2 being configured to be held by a corresponding hub retainer 20 on the tank support structure floor 23, the hub retainer 20 ) Is characterized by generally providing a force directed radially relative to the central hub 2 in the plane of the tank bottom structure 10.
Tank for liquefied gas. The method of claim 1,
The central hub 2 is coupled to a radially structured beam 3 which is further arranged to support the tank wall structure 11.
Tank for liquefied gas. The method of claim 2,
The radial beam 3 is prevented from vertical movement by the vertical retainer 4.
Tank for liquefied gas. The method of claim 2,
The tank wall structure 11 comprises a girder 12 extending from near the outer end of the radial beam 3, the girder 12 being oriented generally parallel to the vertical tank axis 9.
Tank for liquefied gas. The method of claim 4, wherein
The beam 3 supports the tank bottom liner 131.
Tank for liquefied gas. The method of claim 1,
The tank wall structure 11 extends from and around the periphery of the tank bottom structure 10 and the tank wall structure 11 is arranged in a vertical direction disposed on the tank support structure floor 23. Arranged to prevent lifting by rolling and / or pitching movements away from the tank support structure floor 23 by retainers 4
Tank for liquefied gas. The method of claim 3,
The vertical retainer 4 is further arranged to prevent rotational movement of the tank about the central hub 2.
Tank for liquefied gas. The method of claim 1,
The cryogenic tank 1 is disposed between the tank bottom structure 10 and the first compartment bottom 23 and an insulating material 8 arranged between the tank wall structure 11 and the compartment wall 24. Enclosed in a tank compartment 25 having a layer of 18
Tank for liquefied gas. The method of claim 1,
The tank support structure floor 23 is in the tank compartment 25
Tank for liquefied gas. The method of claim 1,
The tank support structure floor 23 is disposed in the ship 30
Tank for liquefied gas. The method of claim 10,
The tank support structure floor 23 is the deck of the ship 30
Tank for liquefied gas. The method according to claim 10 or 11, wherein
The hub retainer 20 is secured on a horizontally oriented vessel tank support structure floor 23.
Tank for liquefied gas. The method of claim 1,
The tank wall structure 11 is cylindrical and the tank bottom structure 10 forms a generally circular plane.
Tank for liquefied gas. The method of claim 1,
The tank 1 is a columnar
Tank for liquefied gas. The method of claim 1,
The cryogenic tank is arranged to contain LNG, LPG or any low temperature fluid.
Tank for liquefied gas. The method of claim 1,
The tank bottom structure 10 has a bottom liner plate 131 and the tank wall structure 11 has a wall liner plate 111.
Tank for liquefied gas. In a ship for the production and storage of LNG comprising a tank (1) for LNG, having a tank bottom structure (10) supporting a tank wall structure (11),
The tank bottom structure 10 has a central hub 2 coupled to a radial structure beam 3 arranged to support the tank wall structure 11,
The central hub 2 is configured to be held by a corresponding hub retainer 20 on the tank support structure floor 23 in the vessel, the hub retainer 20 being in the plane of the tank bottom structure 10. Characterized by generally providing a centrally directed hub with a radially directed holding force
Ship. In the ship for the storage and regasification of LNG, including a tank (1) for LNG, having a tank bottom structure (10) and a tank wall structure (11) disposed on the tank bottom structure (10),
The tank bottom structure 10 has a central hub 2 coupled to a radial structure beam 3 arranged to support the tank wall structure 11,
The central hub 2 is configured to be held by a corresponding hub retainer 20 on the tank support structure floor 23 in the vessel, the hub retainer 20 being in the plane of the tank bottom structure 10. Characterized by generally providing a centrally directed hub with a radially directed holding force
Ship. No content No content A ship for transporting LNG, including a tank 1 for LNG, having a generally vertical tank shaft 9 and a tank bottom structure 10 and a tank wall structure 11 disposed on the tank bottom structure 10. To
The tank bottom structure 10 has a central hub 2 coupled to a radial structure beam 3 arranged to support the tank wall structure 11,
The central hub 2 is configured to be held by a corresponding hub retainer 20 on the tank support structure floor 23 in the vessel, the hub retainer 20 being in the plane of the tank bottom structure 10. Characterized by generally providing a centrally directed hub with a radially directed holding force
Transport ship. The method of claim 1,
The tank bottom hub 20 is provided with one or more channels arranged to fill or empty the tank with cryogenic fluid.
Tank for liquefied gas. It is a method of installing the liquefied gas tank (1) in the ship,
The tank 1 comprises a tank bottom structure 10 and a tank wall structure 11 on the periphery of the tank bottom structure 10,
The tank bottom structure 10 is formed with a generally central tank bottom hub 2 configured to be held by a bottom hub retainer 20 on the tank support structure floor 23 and
The method includes lifting the tank 1 and lowering the tank 1 directly onto the bottom hub retainer 20.
How to install a tank for liquefied gas.

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