Tower for loading and unloading liquefied gas storage tank

Abstract

To provide an assembly for loading and unloading a liquefied gas storage tank capable of restricting degradation of the tank due to deformation characteristic of a tank wall in storing cargoes and charging and cooling a liquefied gas.SOLUTION: A loading and unloading assembly (10) for a liquefied gas storage tank is provided. The loading and unloading assembly includes at least one loading tower (12), an unloading device (14), and at least one cover (16). The loading tower has a structure (18) including at least three poles (20) and a loading pipe, and the unloading device includes at least one unloading pipe (36), a suction member, and a drive assembly (42). The cover is arranged between the suction member and the drive assembly, and the unloading pipe of the unloading device is separated from the poles (20) of the structure of the loading tower and arranged outside of a perimeter delimited by the structure of the loading tower.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to the field of storage and / or cargo transportation of liquefied gases such as liquefied natural gas, liquid ammonia, and liquefied petroleum gas. More specifically, the present invention relates to an assembly for loading and unloading a liquefied gas storage tank.

Background Art

[0002] Liquefied natural gas, generally known by the initials "LNG" of Liquefied Natural Gas, is an important energy source and is composed of approximately 95% methane. More specifically, LNG is stored in a heat-insulated tank in a liquid state at around -160°C. At this temperature, LNG occupies 1 / 600 of the volume it could occupy in a gaseous state, making it easy to transport from one place to another.

[0003] Conventionally, the tank has a loading and unloading tower suspended from a cover that can close the tank. The loading and unloading tower can have a tripod structure, i.e., a tripod structure comprising three vertical poles connected to each other by cross members forming a lattice structure. The tower is guided by a support of the tank emerging from the bottom wall. The loading and unloading tower includes at least one unloading pipe and a suction member having a function of unloading the cargo from the tank. The suction member is connected to a driving device arranged outside the tank. Further, usually, the suction member is at least partially arranged in a sump (tank, drainage tank) formed in the bottom wall of the tank so as to enable optimal suction of the cargo. This ensures that the suction member is immersed in the cargo and increases the amount of cargo withdrawn by the unloading pipe, thus guaranteeing its integrity.

[0004] It is known that the discharge pipe is positioned on one of the poles of the loading / unloading tower structure. One drawback of such an arrangement in loading / unloading towers is the close proximity of the support structure that guides the tower structure to the sump formed on the opposite side of the discharge pipe. Such proximity severely restricts the deformation characteristics of the tank wall during cargo storage and when cooling the tank prior to filling with liquefied gas. These deformation characteristics are necessary to limit tank degradation. Furthermore, positioning the discharge pipe on one of the poles of the tower structure in this way complicates operator access to the discharge pipe. Thus, it is understood that such a tank structure, more specifically such a loading / unloading tower structure, reduces the strength of the tank required for liquefied gas storage while restricting access to the discharge pipe. [Overview of the project]

[0005] Accordingly, the present invention relates to an inlet / outlet assembly for a liquefied gas storage tank, the inlet / outlet assembly comprising at least one inlet tower, an outlet device, and at least one cover intended to close the storage volume portion of the tank, wherein the cover is at least partially traversed by the inlet tower and the outlet device, the inlet tower comprising a structure comprising at least three poles and an inlet pipe, the outlet device comprising at least one outlet pipe, a suction member disposed at a first end of the outlet pipe, and a drive assembly disposed at a second end of the outlet pipe, the cover disposed between the suction member and the drive assembly, and the inlet / outlet assembly characterized in that the outlet pipe of the outlet device is spaced apart from the poles of the structure of the inlet tower and is disposed outside the outer periphery defined by the structure of the inlet tower.

[0006] The storage tank may be positioned on a floating structure and comprises at least a top wall and a bottom wall connected to each other by side walls. The tank walls include at least one insulating layer covered with a corrugated sealing membrane that is deformable in response to the tank's thermal fluctuations. An opening is formed in the top wall to accommodate an loading / unloading assembly. In particular, it is understood that the cover for the loading / unloading assembly closes in a manner that seals the opening in the top wall. Furthermore, the loading tower is guided by supports, at least a portion of which penetrates the bottom wall to secure the loading tower within the tank.

[0007] The outer perimeter defined by the structure of the loading tower corresponds to the axial projection of the loading tower structure onto the bottom wall of the tank. Furthermore, the outer perimeter is defined by the outer edges of each pole, that is, by the circular portions of the poles located on the outermost side of the structure.

[0008] Therefore, the configuration in which the discharge pipe is placed outside the outer perimeter defined by the structure has the advantage of separating the discharge pipe, and by extension the sump associated with this discharge pipe, from the support structure of the loading tower. This allows the corrugated seal film placed in the loading / unloading assembly to maintain its deformation characteristics.

[0009] According to one aspect of the present invention, the discharge pipe extending between the suction member and the drive assembly is spaced apart from the pole of the structure between these two components. In other words, the discharge pipe is outside the pole from one end to the other.

[0010] According to the features of the present invention, two of the poles of the structure of the loading tower form two rear poles, a third pole of the structure forms a front pole, and the loading pipe extends from the front pole of the structure on the opposite side of either of the two rear poles. Here, it is understood that the loading pipe is in front of the front pole of the structure.

[0011] According to the features of the present invention, at least one holding device extends between the discharge pipe and one of the poles of the structure.

[0012] According to the features of the present invention, the structure defines a substantially triangular outer perimeter comprising at least one base determined by a straight line connecting the two rear poles and a front vertex determined by the front pole, and the holding device extends between the discharge pipe and the front pole of the structure which forms the front vertex of the outer perimeter of the structure.

[0013] More specifically, the substantially triangular perimeter defined by the structure of the loading tower comprises three vertices, each corresponding to one of the poles of the structure. Two vertices are involved in defining the base, corresponding to the two rear poles. The vertex corresponding to the front pole is involved in defining the front vertex.

[0014] According to the features of the present invention, the vertex of the outer periphery of the structure and the transport pipe are aligned in the height direction of the substantially triangular outer periphery of the structure. This height direction is perpendicular to the base and is a straight line passing through the front vertex.

[0015] Furthermore, the present invention relates to a tank for storing and / or transporting liquefied gas, comprising at least one loading / unloading assembly having any one of the features described above, wherein the tank comprises a bottom wall, a top wall, and side walls connecting the bottom wall to the top wall, the walls defining the storage volume portion of the liquefied gas.

[0016] According to the features of the present invention, the loading pipe extends between one of the side walls of the tank and the unloading pipe.

[0017] According to the features of the present invention, the drive assembly of the discharge device is located outside the storage volume portion of the tank, and the suction member of the discharge device is located inside the storage volume portion of the tank.

[0018] More specifically, the drive shaft connects the suction member to the drive assembly. In particular, it is understood that the drive assembly is capable of acting on the suction member by the drive shaft.

[0019] According to the features of the present invention, the discharge pipe is positioned on the opposite side of the side wall closest to the structure. The closest side wall may be, for example, the front side wall and the rear side wall of the tank.

[0020] More specifically, the front and rear of the floating structure supporting the tank are defined. The front and rear are defined relative to the standard direction of travel of the floating structure. Thus, in the tank, the discharge pipe corresponds to the foremost pipe relative to the structure and the inlet pipes.

[0021] Similarly, at least one front and rear side wall of the tank is determined according to the standard direction of travel of the floating structure. The discharge pipe is positioned on the opposite side of the rear side wall of the tank relative to the structure, especially when the structure is close to the rear wall.

[0022] Alternatively, the discharge pipe is positioned on the opposite side of the tank's front side wall relative to the structure. This is especially true when the structure is close to the front wall.

[0023] According to the features of the present invention, the tank comprises at least one sump formed in the bottom wall of the tank, and the suction member extends at least partially into the sump.

[0024] The sump, in particular, corresponds to a recess formed in the volume of the tank's bottom wall and defined by the sump wall, and the sump can optimize the removal of liquid cargo. More specifically, the sump can facilitate the suction of liquid cargo by a suction member. This is achieved by consolidating and collecting the liquid cargo in a volume smaller than the tank's storage volume.

[0025] According to the features of the present invention, the tank includes a support for the loading tower that penetrates the bottom wall, and the sample is formed such that its center is at a distance exceeding at least 2.04 m from the center of the support of the loading tower.

[0026] This distance is a straight line perpendicular to the main extension direction of the loading tower and along the straight line connecting the center of the loading tower support and the center of the sample.

[0027] According to the features of the present invention, the center of the unloading pipe is arranged at any point on a semi-circle centered on the center of the support.

[0028] It is understood that the center of the support corresponds to a point that is substantially equidistant from the centers of the three poles of the structure of the loading pipe.

[0029] According to the features of the present invention, the top wall includes an opening where the cover for closing the storage volume part of the tank is arranged.

[0030] Other features, details, and advantages of the present invention will become clearer by reading the following description provided only for the purpose of information in relation to the drawings.

Brief Description of the Drawings

[0031] <000,0101>Figure [Figure 1] is a schematic view of a ship equipped with a tank accommodating a loading and / or unloading tower according to the present invention. [Figure 2] Figure is an overall perspective view of the loading and unloading assembly of Figure [Figure 1] . [Figure 3] Figure [Figure 2] is an enlarged top view of a part of the loading and unloading assembly of Figure [Figure 1] . [Figure 4] Figure is an enlarged side view of a part of the loading and unloading assembly of Figure [Figure 1] .

Embodiments for Implementing the Invention

[0032] First, the present invention is illustrated in detail in the drawings for its implementation, but it should be noted that these drawings can, of course, be used to better define the invention as needed. It should also be noted that these drawings only illustrate exemplary embodiments of the invention.

[0033] Figure 1 shows a floating structure 1, which here corresponds to a liquefied gas transport vessel 1. To transport liquefied gas, the vessel 1 is equipped with at least one tank 2 for storing and / or transporting the liquefied gas. The tank 2 is equipped with at least one bottom wall and a top wall that are opposite each other in the vertical direction of the tank 2, which are not visible in this example. These walls are connected to each other by side walls 4. The bottom wall, top wall, and side walls 4 are, in particular, involved in defining the storage volume 6 for the liquefied gas.

[0034] To ensure optimal transport and storage of liquefied gas in tank 2, the tank wall 4 is provided with at least one insulating layer (not shown). The insulating layer is covered by a corrugated seal film 8, which can be seen in Figures 3 and 4, and is intended to be in contact with the liquefied gas. The corrugated seal film 8, in particular, has multiple undulations 8a, which allow it to withstand deformation caused by thermal fluctuations within tank 2, for example, when tank 2 is cooled prior to filling with liquefied gas.

[0035] The storage and / or transport tank 2 comprises at least one loading / unloading assembly 10 according to the present invention, which allows for the introduction or removal of liquefied gas into or from the tank 2. The loading / unloading assembly 10, as can be seen in Figures 1 and 2, comprises at least one loading tower 12, an unloading device 14, and at least one cover 16 intended to close the storage volume section 6. More specifically, the storage volume section 6 of the tank 2 is closed in a sealed manner by the top wall having an opening in which the cover 16 is placed. As can be seen from Figure 2, the cover 16 is at least partially traversed by the loading tower 12 and the unloading device 14.

[0036] In particular, the loading tower 12, which can be seen in Figure 2, is a structure 18 extending in the main direction P of the vertical extension V, and comprises a structure 18 that includes at least three poles 20, separately referred to as tripods, and loading pipes 22. More specifically, the structure 18 of the loading tower 12 comprises at least three poles 20 fixed to each other by a lattice structure 24. Each of the three poles 20 penetrates the cover 16 of the tank 2. The forward pole 20a and the two aft poles 20b of the structure 18 are determined according to the direction of travel A of the ship 1, which can be seen in Figure 1, so that under normal navigation conditions, the forward pole 20a is the pole 20 of the structure 18 furthest forward in the tank 2.

[0037] Furthermore, as can be seen particularly in Figures 3 and 4, the structure 18 of the loading tower 12 is supported by a support 26 that at least partially penetrates the bottom wall 28 of the tank 2. More specifically, the support 26 comprises at least one platform 30 fixed to each of the poles 20 of the structure 18 of the loading tower 12, and legs 32 extending from the external structure of the tank 2 (not shown) to the platform 30 by penetrating the bottom wall 28 of the tank 2.

[0038] The loading pipe 22 of the loading tower 12, as seen in Figures 1 to 4, is separate from the pole 20 of the structure 18 and extends through the cover 16 to the vicinity of the bottom wall 28. As a result, the free end 34 of the loading pipe 22 (shown as a dotted line in Figure 4, as it is behind the front pole 20a) is at a non-zero distance from the bottom wall 28 in the vertical direction V of the tank 2. This distance between the free end 34 of the loading pipe 22 extending into the storage volume section 6 and the bottom wall 28 allows the liquefied gas to flow through the free end 34.

[0039] The discharge device 14 according to the present invention comprises at least one discharge pipe 36, as can be seen in Figures 3 and 4; a suction member 38 located at the first end 40 of the discharge pipe 36; and a drive assembly 42 located at the second end 44 of the discharge pipe 36, as can be seen in Figure 2. According to one feature of the present invention, a cover 16 is located between the suction member 38 and the drive assembly 42. More specifically, the suction member 38 is located inside the storage volume 6 of the tank 2, while the drive assembly 42 is located outside the storage volume 6 of the tank 2. At least one drive shaft 46, partially visible in Figure 4, connects the suction member 38 to the drive assembly 42. More specifically, the drive shaft 46 extends into the internal volume of the discharge pipe 36 and allows the suction member 38 to be operated under the influence of the drive element 42.

[0040] According to the present invention, as can be seen particularly in Figures 2 to 4, the discharge pipe 36 of the discharge device 14 is spaced apart from the poles 20 of the structure 18 of the loading tower 12. More specifically, as can be seen in Figure 3, a schematic outer perimeter S is defined. The outer perimeter S is defined by the structure 18 of the loading tower 12 and corresponds to the axial projection of the structure 18 of the loading tower 12 onto the bottom wall 28 of the tank 2, i.e., the projection in the vertical direction V. More specifically, the outer perimeter S of the structure 18 is defined by each of the poles 20 of the structure 18. The outer perimeter S defined by the structure 18 passes through the outer edges of the poles 20 of the structure 18, i.e., the circular portion of the pole 20 that is located furthest outside the structure 18. Therefore, according to the present invention, the discharge pipe 36 extends outside the outer perimeter S defined by the structure 18 of the loading tower 12.

[0041] As can be seen from Figure 3, the outer perimeter S defined by the structure 18 has a substantially triangular shape. Each of the poles 20 forms one of the vertices of the outer perimeter S of the structure 18. Thus, the outer perimeter S comprises at least one base 48 defined by a straight line passing through the two rear poles 20b of the structure 18 as defined above, and a vertex 50 defined by the front pole 20a of the structure 18 and separately referred to as the front vertex.

[0042] The forward side wall 4a and the aft side wall 4b of the tank 2 are defined according to the direction of travel A of the ship 1 as seen in Figure 1. Under normal navigation conditions, the forward side wall 4a is defined as the foremost side wall of the tank 2, and the aft side wall 4b is defined as the aftmost side wall 4 of the tank 2. Accordingly, according to an example of the present invention, the base 48 of the outer periphery S projected onto the bottom wall 28, defined by the structure 18, is substantially parallel to one of the side walls of the tank 2. This side wall extends closest to the structure 18, and in this case is the aft side wall 4b. Thus, as can be understood from Figure 1, the discharge pipe 36 extends relative to the structure 18 on the opposite side of the aft side wall 4b.

[0043] Furthermore, according to one example of the present invention, the center C of the discharge pipe 36 is located on any point of a semicircle 52, as can be seen in Figure 1, centered on the center F of the support 26 of the structure 18. More specifically, the center F of the support 26 corresponds to a point that is equidistant, or substantially equidistant, from the centers of each of the poles 20 of the structure 18.

[0044] According to an alternative example of the present invention, which can be seen in Figure 1, the front vertex 50 of the outer perimeter S, i.e., the front pole 20a and the transport pipe 36, are substantially aligned at the height (height direction) I of the triangular outer perimeter S. The height I is understood to be a straight line that passes through the vertex 50 defined by the front pole 20a and perpendicularly cuts the base 48 of the outer perimeter S.

[0045] According to the present invention, as can be seen in Figure 3, at least one holding device 54 extends between the discharge pipe 36 and one of the poles 20 of the structure 18. The holding device 54 makes it possible to hold the discharge pipe 36 in the vertical direction V and ensures that the discharge pipe 36 is held in place in particular during the loading of the tank 2 and during the transport of liquefied gas. According to an example of the present invention, multiple holding devices 54 extend between one of the poles 20 of the structure 18 and the discharge pipe 36, along the latter, that is, between its first end 40 and the cover. According to the illustrated example, at least one holding device 54 extends between the discharge pipe 36 and the front pole 20a of the structure 18, that is, the pole 20 that forms the front apex 50 of the outer periphery S of the structure 18.

[0046] To improve the suction of liquefied gas when it is discharged from the tank 2, the tank 2 is provided with at least one sump 56 formed in its bottom wall 28, which can be seen particularly in Figures 3 and 4. The sump 56 is a volume extending in the bottom wall 28 of the tank 2, which corresponds to a volume defined by a cylindrical sump wall 56a about a rotation axis X. In particular, the sump 56 makes it possible to form a small volume that facilitates the recovery of liquefied gas by the suction member 38. This is by collecting the liquefied gas in this volume which is smaller than the storage volume 6 of the tank 2. It is understood that the suction member 38 of the discharge device 14 extends at least partially into the volume of the sump 56.

[0047] According to the features of the present invention, as can be seen particularly in Figure 4, the sump 56 is formed within the bottom wall 28 of the tank 2 such that the center X of the tank, in this case the center X located at its axis of rotation X, is at a distance D of at least 2.04 m from the center F of the support 26 of the loading tower 12. This distance is understood to be the distance between the axis of rotation X and the center F of the support 26 of the loading tower 12, which is the central axis F, along a straight line perpendicular to the axis of rotation X. It is understood that such a distance d between the sump 56 and the support 26 maintains flexibility for the corrugated seal film 8 extending in the vicinity, so that the corrugated seal film 8 can maintain its deformation characteristics, at least limiting the risk of its premature wear.

[0048] Furthermore, since the center C of the aforementioned transport pipe is positioned on any point on the semicircle 52 that can be seen in Figure 1, which is centered on the center F of the support 26 of the structure 18, it is understood that the semicircle 52 has a radius corresponding to the distance D that can be seen in Figure 3, and this radius is 2.04 m or more.

[0049] Furthermore, from the above-mentioned description of the loading / unloading assembly 10, it can be understood that, in the direction of travel A of the ship 1 as seen in Figure 1, under normal navigation conditions, the unloading pipe 36 is the element of the loading / unloading assembly 10 that is furthest forward in the tank 2.

[0050] However, the present invention as described above is not limited to the means and configurations described and illustrated exclusively, but applies to all equivalent means or configurations, and any combination thereof.

Claims

1. A loading and unloading assembly (10) for a liquefied gas storage tank (2), comprising: The loading / unloading assembly (10) comprises at least one loading tower (12), an unloading device (14) and at least one cover (16) intended to close the storage volume (6) of the tank (2), the cover (16) is traversed at least partially by the loading tower (12) and by the unloading device (14); The loading tower (12) comprises a structure (18) having at least three poles (20) and a loading pipe (22); The discharge device (14) comprises at least one discharge pipe (36), a suction member (38) arranged at a first end (40) of the discharge pipe (36), and a drive assembly (42) arranged at a second end (44) of the discharge pipe (36); The cover (16) is disposed between the suction member (38) and the drive assembly (42); The delivery / discharge assembly (10) is characterized in that the delivery pipe (36) is disposed between the suction member (38) and the drive assembly (42); The loading / unloading assembly (10) is characterized in that the loading pipe (36) of the unloading device (14) is spaced apart from the pole (20) of the structure (18) of the loading tower (12) and is positioned outside the periphery (S) defined by the structure (18) of the loading tower (12). Loading and unloading assembly (10).

2. Two of the poles (20) of the structure (18) of the loading tower (22) form two rear poles (20b), and the third pole (20) of the structure (18) forms a front pole (20a); The discharge pipe (36) extends from the front pole (20a) of the structure (18) opposite either of the two rear poles (20b). The load / unload assembly (10) of claim 1.

3. At least one holding device (54) extends between the discharge pipe (36) and one of the poles (20) of the structure (18); The loading and unloading assembly (10) of claim 2.

4. the structure (18) defines a substantially triangular perimeter (S) with at least one base (48) defined by a line connecting the two rearward poles (20b) and a forward vertex (50) defined by the forward pole (20a); the holding device (54) extends between the discharge pipe (36) and the front pole (20a) of the structure (18) forming the front vertex (50) of the outer periphery (S) of the structure (18); The load / unload assembly (10) of claim 3.

5. the forward vertex (50) of the outer periphery (S) of the structure (18) and the conveying pipe (36) are aligned in the height (I) direction of the substantially triangular outer periphery (S) of the structure (18); The loading and unloading assembly (10) of claim 4.

6. A tank (2) for storing and / or transporting liquefied gas, comprising at least one loading / unloading assembly (10) according to any one of claims 1 to 5, The tank (2) comprises a bottom wall (28), a top wall, and a side wall (4) connecting the bottom wall (28) to the top wall; The walls (4, 28) define the storage volume (6) for the liquefied gas. Storage and / or transport tank (2).

7. the drive assembly (42) of the discharge device (14) is located outside the storage volume (6) of the tank (2); the suction member (38) of the discharge device (14) is arranged in the storage volume (6) of the tank (2); A storage and / or transport tank (2) according to claim 6.

8. The conveying pipe (36) is located on the opposite side of the side wall (4) closest to the structure (18) with respect to the structure (18). A storage and / or transport tank (2) according to claim 6.

9. The storage and / or transport tank (2) comprises at least one sump (56) formed in the bottom wall (28) of the tank (2); The suction member (38) extends at least partially into the sump (56). A storage and / or transport tank (2) according to claim 6.

10. The storage and / or transport tank (2) comprises a support (26) for the loading tower (12) passing through the bottom wall (28), The sump (56) is configured so that the center (X) of the pump is at a distance (D) of at least 2.04 m from the center (F) of the support (26) of the loading tower (12). A storage and / or transport tank (2) according to claim 9.

11. The center (C) of the delivery pipe (36) is located on any point of a semicircle (52) centered on the center (F) of the support (26). A storage and / or transport tank (2) according to claim 10.

12. the top wall has an opening in which the cover (16) for closing the storage volume (6) of the tank (2) is placed; A storage and / or transport tank (2) according to claim 6.

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