RU2478868C2 - Liquefied gas tank with central sleeve in bottom structure - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: present invention proposes cryogenic tank (1) having bottom structure (10) of the tank and wall structure (11) of the tank, which is located in a circumferential direction of bottom structure (10) of the tank. Bottom structure (10) of the tank is equipped with bottom sleeve (2) of the tank, which is provided with possibility of retaining the bottom sleeve with fastener (20) on support base (23) of the tank. Fastener (20) of the sleeve provides all radially directed retaining forces for central sleeve (2) in the plane of bottom structure (10) of the tank.

EFFECT: easy installation of insulation; easy mechanical connection of the tank to the tank compartment.

22 cl, 28 dwg

Description

The global need for energy requires the transportation of large quantities of fuel from the areas in which it is found to the consumer. One of the cleanest and most widespread forms of energy for practical use today is natural gas. Major natural gas fields are usually located far from major consumer markets, and thus there is a need to transport natural gas for consumers from the fields. Pipeline transportation is one of the possibilities under consideration, nevertheless pipeline transportation is quite expensive and does not apply to transportation over long distances. Ship transportation, therefore, remains a practical solution for transporting gas, in particular transporting liquefied gas.

The present invention generally relates to liquefied gas tanks, such as LNG tanks or LPG tanks, although the generic term cryogenic tank is used in the present description. LNG is usually stored in a tank at a boiling point of about -163 ° C at atmospheric pressure, continuously evaporating methane. To reduce evaporation, you can try to reduce the thermal inflow through the wall of the tank by making an insulating layer around the walls of the tank. The walls of the tank must be maintained and stabilized, but all such structural support parts can conduct heat to the tank and, thus, lead to undesirable evaporation losses. Thus, it is desirable to reduce the total cross-section of the structural supporting parts passing through the insulating layer to reduce heat influx. The main problem of LNG tanks and other cryogenic tanks is the temperature compression that occurs during the initial cooling and filling of the tank, and the possible thermal expansion of the tank when LNG is removed from the tank due to evaporation or when the tank is empty.

LNG tanks are often refitted on previously built ships or tankers, but they can also be directly installed on facilities such as floating production, storage and unloading systems (FPSOs) and floating storage and regasification units (FSRUs). For these applications, ease of installation is critical to reduce cost, as is accessibility to deck space. In addition, there are a number of surface applications for cryogenic tanks in industrial use. Different applications present different problems that need to be addressed, and some of the main problems are temperature, volatility and gas toxicity. Several tank designs have been proposed for these applications, each of which has advantages and disadvantages.

During the cryogenic filling process, the bottom plate structure and the wall structure of the tank will shrink when the tank cools below ambient temperature. The bottom lamellar structure and the lower part of the periphery of the wall structure of the tank will be compressed first, then, due to thermal conductivity and direct contact of the liquid and vaporized gas with the wall, the wall of the tank will cool and contract when the tank is filled with liquid natural gas. In particular, for marine LNG tanks, but also for some ground tanks, it is necessary to prevent lateral movement of the tank relative to the base during cooling. For ship tanks, this lateral stability is important when sailing. Cryogenic internal tanks must be designed to withstand the thermal compression of the tank relative to the supports. This is due to the low temperature of the cryogenic liquid, which, naturally, is lower than the temperature of the tank itself and the supports to which it is attached. In addition to the compression of the tank that occurs when the tank is filled with cryogenic liquid, there will be a corresponding expansion of the tank when it is empty.

Differential thermal compression can lead to stresses in the wall of the tank lining plate, the wall support structure of the tank and in the supporting structure of the compartment. Stresses in the lining plate of the LNG tank can cause cracks that can lead to LNG leakage, which is critical due to the risk of fire and explosion and due to methane toxicity. Damage to the tank and the resulting leakage of cryogenic gas on the vessel can, in addition, lead to a catastrophic wreck of the vessel, since the metal structures of such vessels are not designed for such low temperatures.

For ships and other vessels, there is a major problem associated with fluctuations in the surface of LNG due to the impact of waves on the vessel or due to the movement of the vessel itself. Oscillation of the surface can lead to damage to the tank, and the tank must therefore be designed to withstand the effects of splashing fuel. The present invention describes a practical solution to some of the above problems.

State of the art

US Pat. No. 2,905,352 describes a previous attempt to form a stabilized reservoir system configured to be housed in a ship’s hull, the reservoir system being stationary inside the vessel, while allowing compression and expansion of the reservoir in response to a change in temperature. Under the tank, a guide device is made at the bottom of the vessel, containing longitudinally located grooves extending in the longitudinal direction of the vessel, while the reservoir, having corresponding dowels attached to its bottom, is arranged to be placed at the bottom of the vessel, and the keys of the reservoir are inserted into the grooves.

US Pat. No. 3,612,333 describes further development of the idea proposed in the aforementioned US Pat. No. 2,905,352, wherein the keys, keyways, and key supports are located at the bottom of the container, with the keys being located on lines generally corresponding to the longitudinal and transverse center lines of the tank.

US Pat. No. 4,013,030, issued to Stafford, “Support for LNG Ship Tanks,” describes a tank support system located around a circular horizontal section of a tank. The support system contains many identical support nodes located at a distance around a circular horizontal section of the tank. Each support node is connected to the tank and to the base. Each support unit has a sleeve in the bottom for supporting on a corresponding cylindrical sleeve. The bushings are located on the supporting structure of the vessel and can move in the radial direction, and not laterally relative to the tank. This allows for compression and expansion of the tank, while preventing lateral movement of the entire tank.

US Pat. No. 5,531,178 to Aeybu et al., “Support structure for a stand-alone storage tank in a liquefied gas transport vessel” describes a prismatic liquefied gas tank located in a tank compartment with bottom supports under the tank that allow the tank to expand and contract in the lateral directions. The support structure is provided with latches for longitudinal movement along the transverse line, which prevents the entire tank from moving in the longitudinal direction of the vessel, and lateral displacement locks located along the center lines of the vessel to prevent the tank from moving in the right / port side. Many support points are designed to support the tank, the design of which greatly complicates the installation of the tank. The supports will increase the weight of the structure, and in addition, the supports would be positioned asymmetrically. A lack of symmetry will result in uneven load distribution during cooling. The structure will also transmit the moment load of the vessel structure.

US Pat. No. 6,971,537 describes support structures of the semi-membrane walls of a tank, the support nodes providing vertical support for the walls of the tank, while allowing relative movement in the horizontal direction. This design will cause significant point loads on all tank walls that are undesirable. The design is complex and expensive, so it increases installation time and cost, and also complicates the conversion of older vessels into LNG carriers.

German patent 1506761 describes a method for transporting LNG, wherein the plurality of tanks are arranged as a single unit inside the ship’s hull, and this unit is supported by a plurality of struts, some of which are located on the periphery of the tank, with at least one central strut provided. The design necessitates transverse bulkheads, which can regulate the load on the top of the tanks as a result of rolling. This will increase the weight, cost and complexity of the tank structure.

German patent 1781041 “Tanker for transporting liquefied gas” describes a similar support structure for a prismatic tank, in which the longitudinal movement lock is located under the center of the tank, and the lateral movement locks are located under the central sections of the bow and stern of the tank. The distances between the section of the support structure of the clamps and the bottom structure of the reservoir of the clamps are made with the possibility of accommodating blocking gaskets that are locked in place during compression of the reservoir during the cooling process when filling the reservoir with liquefied gas. Along the right and left sides of the tank compartment, the lateral displacement locks are also provided with such locking gaskets to engage the tank with the support structure during cooling. This is an extremely complex design and requires very precise coordination to achieve the required stability. Thus, the tank will be very expensive. In addition, this design will transfer loads on the vessel structure from the tank, which are uncontrolled and somewhat unpredictable. When heated above the set tank temperature in cold operation, the blocking gaskets will disengage, and the tank will be uncontrollably susceptible to rolling on-board in the tank compartment.

US Pat. No. 3,064,612 to Gardner, “Fluid Transport Structures”, describes an LNG vehicle with prismatic tanks extending substantially completely along the beam. The patent issued to Gardner describes a liquefied gas tank with a bottom structure of a tank supporting a wall structure of the tank located on the periphery of the bottom structure of the tank, according to the restrictive part of the independent claim. Each tank is supported by the reference node of the tank, which is rigid with the structure of the vessel, while allowing relative sliding movement of each supported tank in the longitudinal direction, but fixing each tank at the center line of the vessel. In addition, each tank is provided with side support blocks located between the right and left sides of the tank and the right and left inner sides of the inner casing, respectively. The support node of the tank contains a longitudinally located kilson element along the centerline of the housing. The kilson element is equipped with U-shaped clamps to hold the bottom and side sliding elements of hetinax located along the longitudinal keel under the bottom of the tank, allowing the tank to expand and contract in the longitudinal direction.

Disclosure of invention

The present invention attempts to solve at least some of the above technical problems and proposes a liquefied gas tank with a bottom structure of the tank supporting the wall structure of the tank located on the periphery of the bottom structure of the tank, the bottom structure being provided with a central bottom sleeve of the tank configured to hold a retainer of the bottom sleeve on the supporting structural base of the tank, while the Central bottom sleeve of the tank is made capable of providing substantially all radial retention forces in directions parallel to the tank bottom structure.

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

Advantages of the Invention

The first advantage of the invention is that all the support of the liquefied gas reservoir in the lateral direction is provided by the central sleeve, thus, the lateral support of the cryogenic reservoir is not required, thus, no cold bridges are created through the insulating layer surrounding the reservoir wall, such thus, the insulation is more continuous and easier to install. In addition, if necessary, the insulation is easier to remove, for example, when inspecting the tank or compartment of the tank or during repair or modification of the tank.

A second advantage of the invention is that, due to the fact that the tank is attached to one single starting point using a central sleeve, all the compressions of the tank relative to the tank compartment during cooling of the cryogenic tank will take place mainly in the radial direction relative to this single sleeve. This assumption of radial expansion or contraction provided by the vertical retainers provided for the bottom structure of the tank thus facilitates the mechanical alignment of the cryogenic tank with the compartment of the tank and facilitates heating of the cryogenic tank to ambient temperature. No special considerations are required to align lateral supports along the walls of the cryogenic reservoir, interfering with known cryogenic reservoirs.

A third advantage of the invention, thanks to the vertical retainers located on the periphery of the bottom structure of the tank, is that the vertical forces acting on the side of the tank wall due to fluctuations in the load surface, ship pitching, pitching and even aground or collisions are directed from the bottom of the wall structures, essentially, straight down through the edge of the bottom structure and down to the vertical retainers attached to the supporting structure of the ship's tank. Thus, undesired shear forces in the bottom structure of the reservoir (and in the wall structure) arising in known reservoirs are largely eliminated.

A fourth advantage of the invention in an embodiment having vertical retainers located peripherally at the outer ends of the beams of the bottom structure of the tank is that the bottom structure of the tank may have a beam structure located on the upper part of the bottom cladding plate and provides a lowered center of gravity of the cryogenic tank in the vessel, and additionally provides an increased volume of the tank compared to tanks having an external beam structure.

Another advantage of the prismatic tank according to the invention is that the volume of the tank can be significantly increased compared to a vertical cylindrical tank. A conventional cylindrical tank can hold about 18,000 cubic meters, while a prismatic tank can be configured to use a section of the vessel and can be built along a larger area along the main axis of the ship, so a prismatic tank can usually hold about 35,000 cubic meters, limited to same section of the vessel.

Brief Description of the Drawings

The invention is illustrated in the accompanying drawings, in which:

Fig. 1a is a sketch of a cylindrical embodiment of a reservoir for a liquefied gas, hereinafter referred to as a cryogenic reservoir, according to the invention, wherein the reservoir is visible slightly from the side of the reservoir and below it is visible the bottom structure of the reservoir.

Fig. 1b is a perspective view of a prismatic embodiment of a cryogenic reservoir according to the invention, wherein the reservoir is visible slightly above and to the side of the longitudinal axis of the reservoir and the vessel.

Fig. 1c is a simplified view of a prismatic embodiment of a cryogenic reservoir according to the invention, the reservoir is seen in isometric view slightly below, showing the basic elements of the bottom structure of such a prismatic reservoir.

Fig. 2a is a simplified vertical section through the bottom structure of a tank according to the invention, the tank being located on the tank support base in the tank compartment. In this embodiment, the bottom structure of the reservoir is a so-called external mechanical structure with a bottom cladding plate located on the beams of the bottom structure.

Figa, as figa, is a simplified vertical section through the tank according to the invention, in which the facing plate of the cylindrical wall is supported by vertical supports located at the ends of the radial beams of the bottom structure of the tank, and the cylindrical wall and the bottom structure are isolated from the bottom and walls tank compartment.

Fig. 3b is a perspective view corresponding to Fig. 2b and illustrating an internal beam wall structure mounted on a so-called external bottom structure of the tank.

Figure 4 is a vertical section of the lower portion of the simplified tank according to the invention, showing radially arranged vertical retainers located to prevent the periphery of the bottom structure of the tank from rising with the supporting structure of the tank forming the bottom of the tank compartment.

Fig. 5a is a perspective view of an example of vertical retainers with consoles arranged to hold around the bottom edge of the radial beams of the bottom structure.

Fig. 5b is a corresponding perspective view of an example of vertical fixtures forming inverted U-shaped arc clamp vertical supports attached to the tank support structure and located above the outer end portions of the horizontal beams of the tank bottom structure extending beyond the perimeter of the tank wall.

Fig. 6a is a perspective view from below of a horizontal plane of an embodiment of a tank of the invention with anti-rotation retainers for a radial beam structure of the tank. Here, the rotation preventing latches are located approximately half the radius from the center of the cylindrical tank.

Fig. 6b is a similar perspective view from below the horizontal plane of another embodiment of the tank of the invention with rotation-preventive latches located at a distance almost equal to the length of the beam, in radius, if counted from the center of the cylindrical tank.

Fig. 7a is a perspective view and a cross section of a ship hull with a vertical cylindrical compartment for a tank aligned in the center of a central longitudinal bulkhead and with a cross section of an isolated cryogenic cylindrical tank according to the invention.

Fig.7b is a perspective view and a cross section of the hull with a group of compartments for prismatic reservoirs along the centerline of the vessel and with the cross section of such an isolated cryogenic prismatic reservoir according to the invention.

Fig. 8 shows shear forces that can occur in a horizontal beam in the bottom structure of a prior art reservoir if it is affected by an uncompensated lifting force acting on a wall at the end of the beam, with the bottom structure attached elsewhere along the bottom structure. Such uncompensated shear forces in the bottom structure of the tank are largely eliminated by the invention.

Figa is a close-up of the cantilever vertical fixture for the beam, this drawing corresponds to the cantilever vertical fixture shown in figa, while the beam is shown only partially in section only the bottom edge.

Fig. 9b is a close-up of the cantilever vertical fixture for the beam, this drawing corresponds to the inverted U-shaped arc clamping cantilever vertical fixtures shown in Fig. 5b, while the outer portion of the beam is shown, and part of the remaining portions is shown in dashed lines.

10 is an illustration of an anti-rotation support for a radial beam.

11 a is a simplified view of the bottom structure of a cylindrical tank according to an embodiment of the invention, showing a central sleeve in the bottom structure of the tank, radial H-shaped beams supporting the bottom facing plate of the tank, and a cylindrical wall structure extending above the proximal outer ends of the radial beams of the bottom structure moreover, the H-shaped beams passing almost around the periphery pass between the radial beams. Cantilever vertical latches are located near the outer ends and hold the horizontal beams, and several groups of cantilever vertical latches, lying at shorter radii, are located closer to the Central sleeve.

Fig. 11b is an almost similar view of the bottom structure of a cylindrical tank according to an embodiment of the invention in which inverted U-shaped arc clamp vertical clamps are used to hold the outer ends of the beams of the tank bottom structure. Such a construction is simpler and clearly demonstrates an embodiment of the invention corresponding to the embodiment illustrated in FIG. 4 and FIG. 5b. The vertical clips shown in FIGS. 11a and 11b may also play the role of rotation-preventing clips, preventing rotational moments about a vertical axis passing through the center sleeve or reservoir.

11c is a perspective view along the central radial beam and is a slightly bottom view of the bottom structure of the cryogenic reservoir of the invention. The tank is prismatic, and the bottom beam structure of the tank and the vertical latches correspond mainly to the bottom structure of the tank, illustrated in figa.

12a and 12b are perspective views of the acting forces acting on the side of the tank (white arrows) and the corresponding opposing forces on the side of the support system of the tank. The central sleeve transfers the forces acting along the beams of the bottom structure of the tank; anti-rotation retainers transmit rotational moments, and vertical retainers transmit vertical forces.

13 illustrates various translational and rotational movements of a marine vessel.

Fig. 14a is a bottom view and an enlarged side view of an embodiment of the invention showing cantilever peripheral vertical supports.

Fig. 14b is a bottom view and an enlarged side view of an embodiment of the invention, showing inverted U-shaped arc clamp peripheral vertical supports.

Fig. 15a is a simplified vertical section through the bottom structure of the tank according to a preferred embodiment of the invention with a female sleeve of the female type welded between the inner ends of the radial beams, the central sleeve being mounted on a latch of the female male of the female sleeve attached to the frame of the supporting beam structure to hold the tank .

Fig.15b is a simplified vertical section through the bottom structure of the tank according to an alternative embodiment of the invention with a central sleeve of the male type welded between the inner ends of the radial beams, the central sleeve being inserted into the latch of the central sleeve of the female type attached to the frame of the supporting beam structure to hold the tank .

Embodiments of the invention

The invention is a reservoir (1) for liquefied gases, for example, for liquefied methane (LNG), liquefied ethane, liquefied propane (LPG) or other liquefied gases. The tank (1) according to the invention is intended for use on a ship or other marine vessel. The term ship or marine vessel, as used in the present description, further includes floating and semi-submersible vessels for oil production or storage of oil. In addition, the tank in accordance with the invention can be placed on fixed offshore structures. The described reservoir is intended for use under atmospheric pressure, but reservoirs under overpressure are also taken into account. The tank in accordance with the invention is hereinafter referred to generally as a cryogenic tank (1), but the invention is not limited to the tanks used in the cryogenic temperature range, but is limited to liquefied gases such as the above. The tank (1) for liquefied gas is equipped with a bottom structure (10) of the tank and a wall structure (11) of the tank located on the periphery of the bottom structure (10) of the tank. Wall rack beams (12) are made in such a way that they form part of the wall structure (11) of the tank. The wall structure (11) of the tank will typically support the top of the tank. The bottom structure (10) of the tank is provided with a substantially centrally located bottom sleeve (2) of the tank, and the bottom sleeve (2) is arranged to hold onto the support base (23) of the tank by means of a retainer (20) of the bottom sleeve, see FIG. 1, 2 and 7. The sleeve (20) of the tank can provide support forces in directions essentially parallel to the plane of the bottom structure (10) of the tank.

The tank (1) in accordance with the invention allows the tank to be fixed by means of a single-point sleeve (2) of the tank bottom structure (10), and the sleeve (2) is fixed by the sleeve retainer (20) on the tank bottom support structure (23).

The displacement of a large vessel’s tank during temperature compression from ambient to cryogenic temperature can be significant. A significant advantage of the tank, the lateral movement of which is prevented by fixing with one central sleeve, is that during cooling during the initial filling of the tank with liquefied gas, small thermal deformations occur or do not occur at all, since the tank is held at only one point, other structures, such as the beams (3) of the bottom structure (10) of the tank are elongated or compressed in the directions passing through this central sleeve (2).

The vessel has six translational and rotational degrees of freedom: rolling, pitching and yaw are examples of rotational movements, vertical, longitudinal and transverse rolling are translational movements, see Fig. 13.

According to the invention, the sleeve (2) will thus provide support against forces acting in the lateral plane of the tank, and the sleeve (2) alone provides the necessary force in the lateral plane for the retainer (20) of the tank sleeve on the supporting base (23). This is an improvement on previous designs having a plurality of keys, keyways and the like, with each key or keyway being designed to provide support in only one direction. The sleeve (2) should be located, in general, close to the center of the bottom structure (10) of the tank in order to avoid instability of the sleeve. Another advantage of this design is that displacements due to thermal expansion / contraction occur only along half the size of the bottom structure of the tank, and not along the entire length or diameter of the bottom structure of the tank. The bottom structure (10) of the tank can be made of one solid piece of material, such as concrete, or the bottom structure (10) of the tank can preferably be made using radial beams (3), as described below.

In a preferred embodiment of the invention, the beams (3) extend horizontally and radially from the central sleeve (2) and support or hold the fluid-tight bottom facing plates (113) of the tank (1). The vertical supports (12) rise from the proximal outer ends of the radial beams (3) and support the facing plates (111) of the wall structure (11) of the tank (1). Radial beams (3) provide support for the base of the tank, and also distribute the forces acting on the tank throughout the tanker. This is important when the tank is partially filled, since significant surface vibrations can occur due to the forces acting on the tank (1), for example, due to side rolling or pitching. The problem arises, in particular, when the tank (1) is installed on a floating base, such as FPSO, or FSRU, or an LNG tanker. Surface oscillations can also occur in terrestrial cryogenic reservoirs due to seismic waves, and for terrestrial reservoirs it is imperative to provide a reservoir that can withstand forces caused by seismic activity (which can be caused by horizontal seismic accelerations of about 1 g) and the resulting surface oscillation.

The forces acting in the lateral direction due to relative accelerations between the support base (23) of the vessel of the marine vessel (30) and the load on the LNG due to side rolling, pitching, longitudinal and transverse rolling, must be partially transmitted through the wall structure (11) of the tank, and response forces from the LNG cargo side will increase due to surface fluctuations and side and keel accelerations. As indicated above, in particular, this is the problem of marine vessels. Within a wide range of side, keel, longitudinal and transverse qualities, the bottom sleeve (2), held by the sleeve retainer (20) on the tank support base (23), will hold the tank (1) in place. The bottom structure of the tank (10) will be supported in the vertical direction in a different way, using a common support structure under the tank, namely the structural support base (23) of the tank. The structural support base (23) of the tank may be formed by a longitudinal central frame baffle and lateral longitudinal frames of the vessel together with transverse baffle frames. The structural support base (23) of the tank is provided with a retainer (20) of the sleeve. The structural support base (23) of the tank must also contain a bottom cladding plate on the frame structure, the bottom cladding plate being designed to support the bottom insulating layer under the LNG tank through which the sleeve retainer (20) and the central sleeve (2) and possible other types described below, and possibly a piping system.

As shown in figa and 1b, the cryogenic tank (1) can be located in the slotted compartment for the tank with the wall (24). Although a cylindrical tank is illustrated in FIG. 1a, other configurations should be considered within the scope of the invention, for example, a prismatic configuration of any type, in particular a rectangular shape, as shown in FIGS. 1b and 1c, and in FIG. 11c. The choice of geometry is a structural issue, which, although it is the main one in the design of the vessel itself, is not the main one for the present invention. It is possible, for example, to provide a spherical tank, wherein the bottom portion of the wall structure of the tank is removed and replaced with a generally flat bottom structure of the tank, thus provided. On such a bottom structure (10) of the tank, a central sleeve (2) and possibly radially spaced beams (3) according to an embodiment of the invention can be located. Details of the location of the cryogenic reservoir (1) located in the marine vessel are shown in FIG. 2 a, and FIG. 7 a and 7 b, and FIG. 11 a, 11 b and 11 c. Fig. 2a also shows some of the elements shown in Fig. 1, such as the retainer (20) of the sleeve of the ship’s tank on the structural support base (23) of the tank groove for the tank on the vessel. 3a and 3b illustrate additional elements, such as bottom insulation (8), cylindrical wall insulation (18), and the vertical axis (9) of the tank. The structural support base (23) of the tank serves for many purposes, however, one of the main advantages of using such a system is that the tank can be prefabricated ashore and can easily be lifted and lowered in the groove for the ship’s tank onto the retainer retainer (20) in one simple action. This can greatly simplify the installation of cryogenic tanks on ships. This is a significant advantage since many FPSU and FSRU vessels are surface-modified vessels. Thus, the modification of the vessel and the construction of cryogenic reservoirs can take place simultaneously, and not sequentially. Similarly, if it becomes necessary to remove the tanks for maintenance, the cryogenic tank can simply be lifted from the vessel. This is very different from the expensive and complicated maintenance of LNG tanks known in the art.

A significant advantage of the design of the internal beams in the bottom structure of the tank, as illustrated in fig.1b, is that the bottom facing plate is located below, so the volume of the tank is increased, and the center of gravity of the tank can be omitted, providing benefits in both saving and in sustainability.

The lateral forces between the vessel and the liquefied gas, in accordance with the invention, are transmitted radially through the central sleeve (2), through the entire bottom structure (10), as well as the compression / tensile forces through the bottom structure (10), and are additionally transmitted in the form shear forces from the bottom structure (10) of the reservoir to the wall structure (11) of the reservoir, which is installed on the periphery of the bottom structure (10) of the reservoir. It is assumed that, for the construction of the tank according to the invention, the transmitted forces are better distributed over the structure of the tank and, thus, the formation of cracks is prevented, in particular at the lower peripheral transition between the tank bottom lining plate (113) and the tank wall lining plate (111). Thus, stresses due to side rolling, pitching and the resulting surface vibration can be reduced in the tank according to the invention in comparison with the prior art.

According to an embodiment of the invention, the bottom structure of the tank (10) comprises at least three, preferably four or more radial beams (3) attached with their radially inner ends to the central sleeve (2). The radial beams (3) in a preferred embodiment of the invention will support vertical supports (12) extending from the proximal outer ends of the radial beams (3). Impermeable lining plates (131, 111) preferably form an impermeable lining of the tank bottom of the tank and the wall structure (10, 11) of the tank. Facing plates are attached to beam and supporting structures (3, 12). The wall structures (10, 11) of the reservoir can be reinforced in the peripheral directions with rods, ribbons or wires, or can be provided with ring windings of wire or fiberglass, aramid fiber, carbon fiber, or the like, and the reservoir can be provided with upper periphery, corresponding lower periphery. The upper part of the tank according to the invention does not require any lateral clamp, since all translational and rotational acting - opposing transmitted forces arise in the bottom structure of the tank.

The Central sleeve (2), essentially, does not prevent the movement of the tank (1) in the vertical direction. Although such a vertical fixation with the central sleeve (2) can be imagined as illustrated in Fig. 8, such fixation would be indirect with respect to the wall structure (11) of the tank and would include the transmission of vertical forces from the wall structure (11) of the tank through undesirable vertical shear forces in the beams (3) of the bottom lamellar structure (11).

The central sleeve (2) of the tank and the corresponding retainer (20) of the tank sleeve preferably only regulate forces in the horizontal plane when the vessel is in a neutral position. According to an embodiment of the invention, the transmission of upward forces of the wall structures (11, 12) of the tank relative to the bottom (23) of the groove of the ship’s tank is carried out through the clamps (4) of the vertical forces located between the support structure (23) of the bottom of the groove and the periphery (15) of the bottom structure the reservoir, preferably, the outer sections (35) of the beams (3) of the bottom structure (10) of the reservoir. In an embodiment of the invention, the vertical force retainers (4) comprise a support plate welded or otherwise attached to the support structure (23), with fixed support plates welded to the support plate, said stationary support plates provided with consoles (41) for girth of the lower lateral edges of a flat lying H-shaped section of a beam of radial beams (3). This is illustrated in FIGS. 5a, 9a, 11a and 11c, 12a and 14a. The plates with consoles (41) can be welded in place after lowering the tank into its correct position on the clamp (20) of the sleeve in the compartment. Although H-shaped beams are shown, it can be seen that any suitable beam structure can be used.

In another embodiment, the vertical force retainers (4) comprise a support plate welded or otherwise attached to the support structure (23), with fixed support plates welded to the support plate, the fixed support plates containing inverted U-shaped bridges or arcs (42) to grasp the outer sections (35) of horizontal radial beams (3). This is illustrated in FIGS. 5b, 9b, 11b, 12b and 14b. Inverted U-shaped vertical retainer plates (42) can also be welded in place after lowering the reservoir into its correct position on the sleeve retainer (20) in the compartment.

Figures 5a and 5b illustrate that vertically directed lifting forces arising in the wall structures (11, 12) of the tank will be counteracted by vertical force retainers (4) located directly below the wall structure (11) of the tank and directed into the support structure (23) vessel. Thus, forces caused by splashing, and forces and accelerations caused by rolling on the side, which can be felt during heavy sea waves or in heel resulting from load displacement or as a result of an accident, can be counteracted at least up to a given static angle and for a full tank, for example, with a roll of up to 30 degrees to the port side or starboard side.

Until now, based on the foregoing, the reservoir of the invention can be simplified to be described as a reservoir that is held in place laterally by a central sleeve in the bottom structure, and a reservoir whose displacement from the support structure or even tipping is prevented by vertical force retainers pressing the lower edge of the cylindrical wall of the tank to the lower supporting structure of the tank, as shown in Fig.4. This will prevent damage to the tank due to ship movements due to side, keel, longitudinal and lateral rolling, including forces of action and reaction as a result of collisions and aground.

The specific construction, approximately illustrated in FIGS. 9a and 9b, allows longitudinal movement of the beams due to the radial thermal contraction of the beams (3) and can also be used to prevent unwanted relative rotational movement of the bottom structure (10) of the tank relative to the lower supporting structure (23). Such rotational accelerations can occur due to the rotation of the vessel, as well as due to waves causing yaw, i.e. rotation of the vessel around a vertical axis. Such rotational movements of the tank (1) relative to the vessel can be counteracted by using rotation-preventing locks (16), see Figs. 6a and 6b, Fig. 10 (and Figs. 11a, 11b and 11c). The various forces acting on the ship are shown in FIG. 13. The opposing forces, as well as the principle of operation of the tank are shown in figa and 12b.

The rotation-preventing latches (16) contain vertically located lateral locking plates (17) extending parallel to the radial beams (3), while the plates are designed to support the lateral surfaces of the radial beams (3) and have a lower sliding support (28) to vertically support the lower the edges (14) of the beam (3), and the sliding support (28) must additionally have heat-insulating properties.

An advantage of the embodiment illustrated in FIG. 6a is that the rotation preventing latches (16) are separated from the reservoir sleeve (2) and their roles are different: the reservoir sleeve (2) is designed to prevent any translational movement between the reservoir (1) and the retainer (20) bushings on the supporting structural base (23) of the vessel of the vessel, and rotation-preventing latches (16) are designed to prevent rotation of the vessel relative to the vessel. Such rotational forces can be caused by the rotation of the vessel, the periodic rotation of the vessel as a result of yaw caused by waves, or splashing.

An advantage of the embodiment of the invention illustrated in FIG. 6b is as follows: the position of the rotation preventing latches (16), as shown in FIG. 6a, can be moved beyond the bottom edge (15) of the tank bottom plate (13). The beam structure is internal, and thus the bottom plate can be attached by welding to the lower sections of the horizontal beams (3), thus leaving only the tank sleeve (2) forming a recess in the bottom plate. In addition, rotation-preventing latches (16) arranged as shown in FIG. 6b provide two additional advantages: firstly, they are located at the maximum radius of the tank, thus they provide maximum torque preventing rotation, and they do not have to be as rigid as the latches illustrated in FIG. 6a, which provide almost two times less torque preventing rotation; secondly, they are located at points of the structure near the end of the beams, having more or less the same main radial distance (Rmaj) from the center of the tank, and directly under the wall (11) of the tank containing vertical beams (12), which provide most of the torque of the tank . Thus, holding the torque with rotation-preventing clamps (16) near the radial ends of the radial beams (3), as shown in FIG. 6b, will result in less bending moment acting on the radial beams (3) than the location of the rotation-preventing clamps ( 16) located at a small radial distance (Rmin) near the middle of the radial beams (3), as shown in figa. Similar arguments hold true for the vertical retainers (4, 42) shown in Fig. 11b: they can withstand greater torque, in particular around the longitudinal axis of the vessel, when located at the maximum radial distance from the center of the bottom structure of the tank (i.e. 2) reservoir) than with other designs of the reservoir support or retainers located closer to the center of the reservoir. Vertical tank retainers, such as in FIG. 11b, will thus provide the same moment of force applied to the tank, essentially the same as tank retainers located higher up on either side of the tank wall, but do not have the disadvantages of such retainers located upstream wall, both from a mechanical and from a temperature point of view.

In general, the arrangement of rotation-preventing latches (16) located at a radial distance (Rmaj) outside the wall (11) of the tank and the bottom of the tank (13) can provide a lower located bottom structure of the tank and thus a larger tank volume and lowered the center of gravity and a better moment of force preventing rotation, than rotation-preventing clamps located closer to the central sleeve (2), and also provides less structural penetration through the insulating layer under the bottom of the tank. In general, rotation-preventing latches (16) will be radially opposed pairs, as shown in FIG. 6b, so no moment will arise in the reservoir sleeve (2, 20). The inverted U-shaped vertical retainers shown in FIG. 11b further lower the bottom of the tank lining plate (113) to act as the bottom structure (10) of the internal structure tank and thereby increase the volume of the tank in the same manner as described above.

Fig. 8 illustrates the need for vertical retainers to be located near the outer perimeter of the tank, so that the force arm between the vertical forces from the tank wall and the holding vertical forces acting on the bottom structure becomes short. If the shoulder of the force acting through the walls of the tank on the bottom structure of the tank is undesirably large, as illustrated, damage can occur in the bottom structure of the tank due to shear forces, with the formation of cracks and possible leakage as a result.

The above-described reservoir according to the invention should have the advantages of working at sea. Low heat transfer can be maintained due to the fact that any support blocks or retainers are required only near the bottom of the tank and the structural parts do not have to cross the insulation layer at levels above the bottom of the tank, so the insulation layer around the entire wall structure (11) can be continuous. It also simplifies the design of the cryogenic reservoir design.

Additional logistical advantages arise from the fact that one or more of the tanks of the invention, as described above, can be assembled simultaneously with the assembly of the vessel with slots for compartments arranged to receive the tanks of the invention. The reservoir (1) according to the invention can be lowered into the groove, the central sleeve (2) is designed to fall into the retainer (20) of the sleeve. Clamps (4) of vertical forces and possible rotation-preventing clamps (16) can be prepared for receiving radial beams (3) and can be provided by welding consoles (41) or inverted U-shaped jumpers to girth radial beams (3).

As an alternative to using clamps (4) of vertical forces to grip the outer sections of radial beams (3), the bottom plate structure (10) and beams (3) can be covered by a radially oriented guide (19) to interact with vertical clamps (4). Such an arrangement may allow rotational relative movement of the cryogenic reservoir; a possible configuration is illustrated in FIG.

According to an embodiment of the invention, the vertical latches (4) can be arranged in the form of wedges (43) (illustrated in FIG. 4) located in the wall (24) of the tank compartment (25), and the wedges (43) are designed to rotate into the wall (24) ) compartment and from it to block the outer ends (35) of the beams (3) of the bottom structure (10) of the tank when the tank (1) is located in place. Such wedges (43) can be adjusted from the outside around the compartment (25) of the tank, thereby facilitating the installation and removal of the tank on the vessel. In addition, this reduces the necessary space around the wall structure (11) of the tank and the periphery of the bottom structure (10) of the tank and improves the available volume of the tank of the internal structure of the tank, lowered into the groove for the tank on the vessel.

An advantage of the present invention is that the central sleeve (2) of the tank has a small length compared to the length of the bottom structure (10) of the tank. Thus, the total thermal contraction or expansion of the central sleeve (2) will be relatively small during cooling or heating compared with the significant compression or expansion that occurs with the entire bottom structure of the tank compared to the bottom of the compartment during cooling or heating of the tank. The small length of the tank sleeve (2) will allow the tank sleeve to be fixed in the single-point retainer (20) also when heated, which will allow the vessel to sail with an empty tank, which would be impossible when using the cryogenic tank according to German patent 1781041.

The reservoir according to the invention thus solves some of the problems related to thermal compression, lateral fixation, longitudinal fixation, forces causing surface oscillation, distribution of forces caused by rolling, and stability of cryogenic reservoirs.

Typically, an internal tower-type support is located in the cryogenic tank, with the tower-type support holding vertical pipes to fill and empty the LNG or other fluids into and out of the tank using internal pumps and valves. Such other fluids may be nitrogen, carbon dioxide, LPG and gas condensates. In an embodiment of the invention, the bottom sleeve (2) and the sleeve retainer (20) can themselves provide passageways for the entry and / or exit of cryogenic fluids, thereby providing an easy way to fill or empty the tank.

On figa and 14b shows a bottom view and an enlarged vertical projection of embodiments of the invention, showing enlarged peripheral vertical supports (4) located on the periphery of the tank for grasping the lower edges of the radial beams (3), which can serve as the rotation-preventing clamps described above ( 16), redundant in this case. This arrangement is easier to implement, verify and install, and it can allow for a flat bottom for the tank compartment.

On figa shows a simplified vertical section through the bottom structure of the tank according to a preferred embodiment of the invention with a central sleeve (20) of the female type, welded between the inner ends of the radial beams (3), and the Central sleeve is mounted on the Central latch (20) of the sleeve of the male type, attached to the frame of the support structure (23) to hold the reservoir (1). An advantage of the center sleeve (2) of the female type shown in FIG. 15a is that fewer bending moments occur in the bottom structure (10) of the tank than with the alternative center sleeve (2 ') of the male type illustrated in FIG. 15b below.

Fig. 15b shows a simplified vertical section through the bottom structure of the reservoir of an alternative embodiment of the male type with a central hub (2 ′) welded between the inner ends of the radial beams (3), the central hub (2 ′) being inserted into the central retainer (20 ′ ) sleeves of the female type, which is attached to the frame of the supporting structure (23) to hold the reservoir (1).

Claims (22)

1. The tank (1) for liquefied gas with a bottom structure (10) of the tank supporting the wall structure (11) of the tank, characterized in that it contains
the Central sleeve (2) in the bottom structure (10) of the tank, made with the possibility of holding the corresponding retainer (20) of the sleeve (2) on the supporting structural base (23) of the tank, and the retainer (20) of the sleeve, in General, provides essentially all radially directed holding forces for the central sleeve (2) in the plane of the bottom structure (10) of the tank. 2. The reservoir (1) according to claim 1, characterized in that the central sleeve (2) connected to the radial structural beams (3) is further configured to maintain the wall structure (11) of the reservoir. 3. The tank (1) according to claim 2, characterized in that the vertical latches (4) prevent the vertical movement of the radial beams (3). 4. The reservoir (1) according to claim 2, characterized in that the wall structure (11) of the reservoir contains supports (12) extending from the proximal outer ends of the radial beams (3), and the supports (12) are generally parallel to the vertical axis (9) of the tank. 5. The tank (1) according to claim 4, characterized in that the beams (3) support the bottom lining (131) of the tank. 6. The tank (1) according to claim 1, characterized in that the wall structure (11) of the tank extends from the periphery (15) of the bottom structure (10) of the tank and around it, and the wall structure (11) of the tank is arranged to be held from rising due to side rolling and / or pitching, from the supporting structural base (23) of the tank by means of vertically directed latches (4) located on the supporting structural base (23) of the tank. 7. The tank (1) according to claim 3, characterized in that the vertical latches (4) are additionally located with the possibility of preventing rotational movement of the tank (1) around the central sleeve (2). 8. The tank (1) according to claim 1, characterized in that the cryogenic tank (1) is surrounded by a compartment (25) of the tank having a layer of insulating material (8, 18) located between the bottom structure (10) of the tank and the bottom (23) the first compartment and located between the wall structure (11) of the tank and the wall (24) of the compartment. 9. The tank (1) according to claim 1, characterized in that the supporting structural base (23) of the tank is located inside the compartment (25) of the tank. 10. The tank (1) according to claim 1, characterized in that the supporting structural base (23) of the tank is located in the sea vessel (30). 11. The tank (1) according to claim 10, characterized in that the supporting structural base (23) is the deck of a sea vessel (30). 12. The tank (1) according to claim 10 or 11, characterized in that the sleeve retainer (20) is attached to the horizontally oriented support structural base (23) of the vessel. 13. The tank according to claim 1, characterized in that the wall structure (11) of the tank is cylindrical, while the bottom structure (10) of the tank, in General, forms a circular plane. 14. The tank according to claim 1, characterized in that the tank (1) is prismatic. 15. The tank (1) according to claim 1, characterized in that the cryogenic tank is designed to store LNG, LPG or any fluid having a low temperature. 16. The tank (1) according to claim 1, characterized in that the bottom structure (10) of the tank is provided with a bottom cladding plate (131), and the wall structure (11) of the tank is equipped with a wall cladding (111) plate. 17. The reservoir (1) according to claim 1, located on a sea vessel for the production and storage of LNG. 18. The reservoir (1) according to claim 1, located on a ship for storage and regasification of LNG. 19. The tank (1) according to claim 1, located on the vessel for transporting LNG. 20. The tank (1) according to claim 1, characterized in that the bottom sleeve (20) of the tank is made with one or more channels for filling or emptying the tank with cryogenic fluid. 21. A method of installing a reservoir (1) for liquefied gases on a vessel, characterized in that the reservoir (1) contains a bottom structure (10) of the reservoir and a wall structure (11) of the reservoir at the periphery of the bottom structure (10) of the reservoir, the bottom structure ( 10) the tank is provided with a substantially central bottom sleeve (2) of the tank configured to hold the bottom sleeve with a retainer (20) on the structural support of the tank (23). 22. The method according to item 21, further comprising raising the reservoir (1) and lowering the reservoir (1) directly onto the latch (20) of the bottom sleeve.

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