Multi-lobe cargo tank

Abstract

Multi-lobe tank for containing pressurized liquids, such as liquefied gas, for mounting into a ships hull, wherein the tank comprises at least a first longitudinally extending multi-lobe tank part having a center line and a second longitudinally extending multi-lobe tank part having a center line that are positioned behind each other resulting in a forward multi-lobe tank part and a rear multi-lobe tank part with aligned center lines, wherein the first part can tapered towards an end of the first part.

Claims

1. A multi-lobe tank for containing pressurized liquids tbr mounting into a ship's hull, wherein the multi-lobe tank comprises at least a first longitudinally extending multi-lobe tank part having a center line extending centrally and in longitudinal direction of the first longitudinally extending multi-lobe tank part and a second longitudinally extending multi-lobe tank part having a center line extending centrally and in longitudinal direction of the second longitudinally extending multi-lobe tank part, the second longitudinally extending multi-lobe tank part being positioned behind the first longitudinally extending multi-lobe tank part resulting in a forward multi-lobe tank part and a rear multi-lobe tank part with aligned center lines, wherein the forward multi-lobe tank part and rear multi-lobe tank part are joined to each other at a connection, wherein the forward multi-lobe tank part has a tank wall that is tapered constantly from the connection towards a closed end of the forward multi-lobe tank part that is opposite to an end at the connection with the rear multi-lobe tank part such that a cross-sectional area at the connection of the forward multi-lobe tank part and rear multi-lobe tank part is larger than a cross-sectional area at or near the closed end of the forward multi-lobe tank part, and further comprising a transverse web inside the multi-lobe tank and provided at the connection between the forward multi-lobe tank part and the rear multi-lobe tank part, wherein the transverse web is plate structure that extends over the entire larger cross-sectional area in a direction transverse to the longitudinal direction of the multi-lobe tank.

2. The multi-lobe tank according to claim 1, wherein the first tank part and the second tank part are approximately equally long.

3. The multi-lobe tank according to claim 1, wherein the multi-lobe tank is a tri-lobe tank having two bottom lobes and one top lobe positioned above the bottom lobes, each of the bottom and top lobes comprising first and second tank parts and having the center lines.

4. The multi-lobe tank according to claim 3, further comprising a Y-configuration longitudinal reinforcing web provided at connections between nodes of the lobes.

5. The multi-lobe tank according to claim 4, wherein the Y-configuration longitudinal reinforcing web has oblique webs, and Wherein guide openings are provided in the oblique webs to allow equipment being lowered and/or retracted to be guided therethrough.

6. The multi-lobe tank according to claim 4, wherein at nodes between lobes and/or the reinforcement web a Y-joint is provided to connect the Y-configuration longitudinal reinforcing web and lobes.

7. The multi-lobe tank according to claim 4, wherein the transverse web comprises three parts and wherein each of the three parts is positioned between legs of the Y-configuration longitudinal reinforcing web at the location of the transverse web.

8. The multi-lobe tank according to claim 3, wherein a distance between the center lines of the bottom lobes is approximately double a distance or height that the center line of the top lobe is positioned above the center lines of the bottom lobes.

9. The multi-lobe tank according to claim 1, further comprising saddle supports to support the multi-lobe tank, wherein at least one of the saddle supports is a sliding support.

10. The multi-lobe tank according to claim 9, wherein the sliding support comprises sliding wooden blocks.

Description

(1) The invention will further be elucidated on the basis of exemplary embodiments which are represented in a drawing. The exemplary embodiments are given by way of non-limitative illustration.

(2) In the drawing:

(3) FIG. 1 shows a general arrangement of a multi-lobe tank according to the invention in a vessel;

(4) FIG. 2a shows a forward view of an embodiment of a multi-lobe tank, in particular a tri-lobe tank;

(5) FIG. 2b shows a side view of the embodiment of FIG. 2a;

(6) FIG. 2c shows a top view of the embodiment of FIG. 2a;

(7) FIG. 3 shows a detail of a sump in a bottom of a lobe of the multi-lobe tank;

(8) FIG. 4 shows a schematic cross-sectional view of the multi-lobe tank, in particular a tri-lobe tank, at the position of the guide openings in the Y-shaped longitudinal reinforcing web;

(9) FIG. 5 shows a detail of a Y-joint to connect lobes to the Y-shaped reinforcing web;

(10) FIG. 6 gives a schematic representation of the transverse web between the first tank part and the second tank part;

(11) FIG. 7a gives a schematic cross-section of a fixed support;

(12) FIG. 7b gives a schematic cross-section of a sliding support;

(13) FIG. 8 a cross-sectional view of the embodiment of FIG. 2b at section B-B.

(14) It is noted that the figures are only schematic representations of embodiments of the invention that are given by way of non-limiting example. In the figures, the same or corresponding parts are designated with the same reference numerals.

(15) FIG. 1 shows a schematic representation of a general arrangement of a vessel 1 with a multi-lobe tank 2 according to the invention. In this embodiment, the multi-lobe tank is shown mounted in the hull of the vessel or the ship. In other embodiments, the multi-lobe tank can be positioned onshore for storage of liquefied gas.

(16) The multi-lobe tank 2 is mounted in a lying position in the ship's hull, in an onshore configuration, the multi-lobe tank 2 typically would be mounted in a standing position.

(17) The multi-lobe tank 2 comprises a first longitudinally extending multi-lobe tank part 2a and a second longitudinally extending multi-lobe tank part 2b. Each tank part 2a, 2b has a central axis A, B. The first tank part 2a and the second tank part 2b are positioned behind each other resulting in a forward tank part, here tank part 2a, and a rear tank part, here tank part 2b, of which the central axes A, B are aligned. The tank parts 2a, 2b are thus coincident with each other. According to the invention, the first tank part 2a is tapered towards an end thereof. Here, the first tank part 2a is the forward tank part when seen in the sailing direction of the vessel.

(18) By tapering the first tank part 2a, it fits better in the forward part of the ship comprising the bow 3 of the ship. As such, the tank 2 can be mounted lower in the cargo space of the hull of the ship 1, which may reduce the height of the center of gravity and thus may increase the stability of the ship.

(19) FIG. 2a shows schematically a front view of a multi-lobe tank 2. Here, in this embodiment, the multi-lobe tank 2 is a tri-lobe tank having two bottom lobes 4, 5 and a top lobe 6. FIG. 2b shows schematically a side view of the tri-lobe tank 2, and FIG. 2c shows schematically a top view. Each tank part 2a, 2b has two bottom lobes 4a, 5a, 4b, 5b respectively and one top lobe 6a, 6b respectively. As can be seen in the figures, the central axes A, B of the respective first tank part 2a and the second tank part 2b are in line with each other. Each tank part 2a, 2b has a closed end 7a, 7b and has an open end 8a, 8b. At the open ends 8a, 8b the tank parts 2a, 2b are joined to each other, usually by means of welding. Thus, the tank parts 2a, 2b can be manufactured separately from each other, and later be joined together to form the tank 2. This may improve the production time. Preferably, at the joining connection of the first part 2a and the second part 2b, a transverse web 9 is provided. The transverse web 9 is inside of the tank 2 and for example shown in FIG. 6. The transverse web 9 provides for reinforcement of the tank 2 and is preferably provided with holes 10 to allow liquid to move between the first tank part 2a and the second tank part 2b.

(20) In the embodiment of FIGS. 2a, 2b, 2c, the tank 2 comprises two tank parts 2a, 2b which are approximately equally long. This may be advantageous in terms of manufacturing and installation into the cargo space of the ship's hull. Also, it may be advantageous to fit better into the ship's hull. However, other embodiments can be thought of wherein the first tank part can be larger or shorter than the second tank part, for example depending on a specific hull shape. Also, in another embodiment, the tank 2 may comprise more than two tank parts, for example, a forward tank part, a rear tank part and an intermediate tank part. In a further embodiment, instead of tri-lobe tank, a quad-lobe tank may be considered or a bi-lobe tank. Many variants are possible.

(21) As can be seen in the FIGS. 2a, 2b, 2c, on top of the tank two entrances 11, 12 are provided. Via these entrances, typically e.g. a man hole, equipment such as pumps, or, when necessary, workmen can enter into the inside of the tank, for example for maintenance and/or repair, or for emptying and/or cleaning of the tank. Each entrance 11, 12 is positioned above the lowest position of the respective lobes 4, 5. Entrance opening 11 is positioned above a lowest position of lobe 5, and entrance opening 12 is positioned above a lowest position of lobe 4. This in particular advantageous when lowering a pump for emptying the tank. Then, the pumps can be lowered to the lowest position and then emptying the tank 2. In an advantageous embodiment, at the lowest position, a pump receiving recess 13, 14 can be provided. In these recesses, 13, 14, the pumps can be positioned. Then, upon pumping, they can also remove almost all last remaining liquid from the tank. FIG. 3 gives a schematical cross-sectional detail of an embodiment of the recess 13, 14.

(22) As can be seen in for example FIG. 2a, the multi-lobe tank is here a trilobe tank having two bottom lobes 4, 5 and a top lobe 6. Each lobe 4, 5, 6 has its own centerline C4, C5 and C6 respectively. The top lobe 6 is positioned above the bottom lobes 4, 5 such that the distance D1 between the centerlines C4, C5 of the bottom lobes 4, 5 is approximately double the distance D2 that the centerline C6 is above the centerlines C4, C5. As such, the center of gravity of the trilobe tank 2 can remain relatively low, while the volume of the tank 2 can be optimal, which is advantageous in optimizing carried load, i.e. the liquefied gas to be transported.

(23) Further, the trilobe tank 2 is provided with a reinforcing web 15. The reinforcing web 15 is a longitudinal web, in the front view of FIG. 2a it can be seen schematically. A cross-section is shown in FIG. 8. The Y-configuration longitudinal reinforcing web 15 extends between the nodes of the lobes in a Y-shape configuration. The three lobes 4, 5, 6 form three nodes 16, 17, 18 respectively where the lobes intersect. In a top view, bottom view or a side view, these nodes 16, 17, 18 form lines where the lobes 4, 5, 6 intersect. The Y-configuration reinforcing web 15 (FIG. 8/4) has three web-legs, two oblique webs 19, 20 and a standing web 21. Advantageously, the transverse web 9 comprises three parts wherein each part fits between web-legs of the Y-configuration reinforcing web 15 at the location of the transverse web 9.

(24) The Y-configuration reinforcing web 15 has a plate-like structure, each web-leg 19, 20, 21 of the Y-configuration is of a plate-like structure. These plate-like structures are provided with holes to allow liquid to pass through between the different lobe-compartments (FIG. 4).

(25) At certain positions in the oblique webs 19, 20 guide openings 22, 23 are provided to allow equipment being lowered and/or retracted therethrough. In particular, the guide openings 22, 23 are provided at a position approximately corresponding with the position of the openings 11, 12 and the recesses 13, 14, such that equipment being entered into the tank via the openings 11, 12 can be guided through the reinforcing web 15 via the guide openings 22, 23 towards the recesses 13, 14. In some embodiments these openings 11, 12 and guide openings 22, 23 can be sufficiently large to allow a man to pass through, i.e. the openings have minimal man-hole-size. Then, workmen can enter the tank for reparation, inspection, maintenance etc. In an advantageous embodiment, the guide openings 22, 23 have upwardly extending walls as to guide the equipment therethrough. The upwardly extending walls may be cylindrical or tubular with various cross-sections possible, e.g. circular, square, triangular. At an upper end and/or a lower end of the guide walls, outwardly flaring flanges may be provided to further guide the equipment towards the guide opening.

(26) Advantageously, the Y-configuration reinforcing web 15 is connected to the lobes 4, 5, 6 at the nodes 16, 17, 18 by means of a Y-joint 24, as can be seen in FIG. 5. By providing this Y-joint 24, complex welding operations can be omitted and the Y-joint 24 can be manufactured dedicated with respect to the forces it may be subject to. As such, the Y-joint 24, typically a forging piece, but other manufacturing methods are also possible, can be manufactured in a controlled environment, e.g. a fabrication hall and can be thoroughly inspected and controlled prior to be joined with the lobe walls and the reinforcing web. This improves the reliability and/or strength of the joint at the nodes.

(27) The tank 2 is supported by means of a fixed support 25 and a sliding support 26 to allow movement of the tank 2 due to temperature variations, loads, etc. The fixed support 25 preferably is a saddle support, an embodiment of which is shown in FIG. 7a. The fixed support 25 comprises lower part or a holder 27 fixedly mounted to an external structurethe fixed worlde.g. a bottom of the cargo space of the vessel in which the tank is to be placed. Further, the support 25 comprises an upper part 28, or block of material 28, that is fixedly mounted to the tank 2. The block of material 28 is received in the lower part or holder 27 and preferably can withstand relatively high forces, e.g. wood, or a rubber-like material, or a composite material. The block of material 28 is itself fixedly mounted to the tank 2. Here, a protrusion 29 is welded to the tank wall that is inserted into the block material 28. The block material can have any shape, depending on the shape of the holder 27. As such, the interruption of the isolation of the outer wall of the tank 2 can be limited and sufficient support can be provided.

(28) The sliding support 26 comprises a first part, or lower part, 30 that is fixedly mounted to the fixed world, and a second part or upper part 31. For the sliding support, the upper part 31 is slidingly engaged with the lower part 30. Advantageously, the upper part 31 and the lower part 30 are configured as wooden blocks. More advantageously, at the engagement surfaces of the upper part 31 and the lower part 30 a metal sheet or metal layer is provided, such that metal-on-metal or metal-on-wood contact is provided for the slidingly engaged blocks. As such, a reliable sliding connection can be obtained, while minimizing the interruption of the thermal isolation material of the tank 2, and thus reducing the thermal bridge across the support. In particular by using wooden blocks, for the sliding support 26 and/or for the fixed support 25, the thermal bridges may be reduced and thermal isolation of the tank 2 may remain effective, despite the interruption by the supports 25, 26.

(29) For the purpose of clarity and a concise description features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described. It may be understood that the embodiments shown have the same or similar components, apart from where they are described as being different.

(30) For example, in the figures the embodiment is explained by means of a trilobe tank, but all aspects described are equally well applicable to a quadlobe tank or a even a higher multi-lobe tank, e.g. a five-lobe tank. Also, all aspects are equally well applicable when the tank would be in an upwardly standing position, as it would be the case on a stationary location, such as onshore.

(31) Many variants will be apparent to the person skilled in the art. All variants are understood to be comprised within the scope of the invention defined in the following claims.