Four-lobe cargo tank for transporting and / or storing liquefied gases

Abstract

A four-lobe cargo tank for transporting and / or storing liquefied gas, the tank having four main lobes, each having a cylinder sector outer shell and a main lobe axis, the four main lobe axes being axially parallel to and centered about a common main central axis, the four main lobes being joined by four web frames to four diagonally corresponding perforated bulkheads directed outward from the main central axis, the tank further comprising first and second end covers, each end cover further comprising four quarter spherical shell sections forming end portions of the cylinder sector outer shell, the quarter spherical shell sections of each of the first and second end covers being joined toward and closed by four diagonally arranged cylindrical 45-degree cut pipe sections, each of the first and second diagonally arranged cylindrical 45-degree cut pipe sections being arranged such that its axis transverses the main axis.

Description

[Technical Field]

[0001] The present invention relates to the field of transport and / or storage of liquefied gases in tanks, more particularly in four-lobe cargo tanks. While pipelines may provide feasible transportation over short distances, for longer distances the capital costs become prohibitive and therefore alternative transportation of the captured CO2 from its initial source to a use facility or long-term sequestration of the captured CO2 is required.

[0002] The present applicant has been working on developing carbon capture systems for decades, and the field lacks facilities for storing and transporting captured carbon dioxide (CO). The present invention aims to efficiently and economically transport captured CO. As an example, a carbon capture plant may be installed in South Korea, and the recipient, which uses the CO for enhanced oil recovery (EOR), may be in the United States and / or the Persian Gulf. Efficient and economical trade for such long-distance transport advantageously also includes cross-trading to utilize cargo capacity in both directions. An efficient cross-trade could be transporting CO from South Korea to the United States and / or the Persian Gulf, and transporting, for example, liquefied natural gas (LNG) on the return voyage. [Background technology]

[0003] Patent Document 1 describes a tank as a pressure tank capable of containing both liquids and gases, and more specifically, as a closed container consisting of cylindrical compartments assembled together and provided with closures at the ends. The container or tank object is particularly applicable to the storage of volatile liquids such as gasoline, butane gas, and / or propane, and is applicable to tanks in which it is desirable to prevent loss due to evaporation by maintaining the gas in a pressurized state above the liquid surface. The unique construction method of the tank object allows for considerable savings in the weight of metal used in the construction of the tank, a savings greater than that obtained when manufacturing a cylindrical tank having the same volume and capable of withstanding the same internal pressure.

[0004] Patent Document 2 describes a multi-lobe tank for containing liquefied gas, for mounting to the hull of a ship. The tank comprises at least a first longitudinally extending multi-lobe tank section having a centerline A and a second longitudinally extending multi-lobe tank section having a centerline B, which are arranged aft and aft, with the centerlines A and B aligned, providing forward and aft multi-lobe tank sections. More specifically, this patent application claims a multi-lobe tank for mounting to the hull of a ship, for containing pressurized liquid such as liquefied gas, the tank comprising at least a first longitudinally extending multi-lobe tank section having a centerline and a second longitudinally extending multi-lobe tank section having a centerline, which are arranged aft and aft, with the centerlines A and B aligned, the first section tapering toward the end of the first section. The invention of Patent Document 2 aims to increase the stability of a ship by lowering the center of gravity of a multi-lobe tank, and therefore a three-lobe cargo tank with two lobes at the tank top and one lobe above those two lobes is considered to be a preferred embodiment of the invention.

[0005] Another patent application, U.S. Patent No. 5,629,663, describes a storage tank having a generally cubic configuration. The storage tank includes four vertically oriented cylindrical walls spaced approximately 90 degrees apart from one another, with an outer support structure coupled to the exterior of the storage tank. The tank has an internal bulkhead structure between the four vertical cylinders, and an internal membrane portion configured to partially block the flow of liquid. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] French Patent Application Publication No. 1037900 [Patent Document 2] European Patent Application Publication No. 3318791 [Patent Document 3] U.S. Patent Application Publication No. 2021 / 348719 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention is generally directed to solving one of the problems associated with the prior art. [Means for solving the problem]

[0008] The present invention relates to a four-lobe cargo tank for transporting and / or storing liquefied gas, the tank comprising four main lobes, each having a cylinder sector outer shell and a main lobe axis, the four main lobes being axially parallel to and centered about a common main central axis, the four main lobes being supported by four web frames in corresponding diagonally outwardly directed directions from the main central axis. and wherein the tank is joined to four perforated bulkheads (arranged) and the tank further comprises first and second end covers, each end cover comprising four quarter spherical shell sections each forming an end portion of the cylinder sector outer shell, the quarter spherical shell sections of each of the first and second end covers being joined towards the main central axis and closed by first and second diagonally arranged four cylindrical 45 degree cut pipe sections, each of the first and second diagonally arranged four cylindrical 45 degree cut pipe sections being arranged with its axis transverse to the main axis.

[0009] In one embodiment of the present invention, the invention also relates to a method of transporting gas comprising a vessel having at least one four-lobe cargo tank, the method comprising the steps of loading liquefied natural gas (LNG) into said one or more four-lobe tanks at an LNG loading terminal under cryogenic conditions, sailing the vessel to an LNG unloading terminal and unloading the liquefied natural gas (LNG) at said unloading terminal for consumption, and, if necessary, sailing the vessel (0) to a liquefied carbon dioxide (CO2) loading terminal, loading the one or more four-lobe tanks with captured liquefied carbon dioxide (CO2), and sailing the captured liquefied carbon dioxide (CO2) to the liquefied carbon dioxide (CO2) unloading terminal for permanent storage or industrial consumption.

[0010] The advantage of this embodiment is that it solves the problem of transporting mixed cargoes, for example transporting high density pressurized cargo during one voyage and cryogenic performance up to liquefied natural gas on the return voyage, increasing ship efficiency and indirectly reducing costs.

[0011] Further embodiments of the invention are defined in the dependent claims. [Brief explanation of the drawings]

[0012] [Figure 1a] FIG. 1 is an isometric view illustrating an embodiment of a four-lobe cargo tank having four main lobes. [Figure 1b] FIG. 1 is an isometric view of an embodiment of a four-lobe cargo tank having four main lobes, viewed from the first end cover side. [Figure 1c] FIG. 10 is an end view of one embodiment of a four-lobe cargo tank second end cover. [Figure 2a] FIG. 1 is an end view of an embodiment of a first end cover for a four-lobe cargo tank. [Figure 2b] FIG. 2b is a combined front and cross-sectional view of a cross-section of an embodiment of a four-lobe cargo tank at centerline NN shown in FIG. 2a. [Figure 2c]FIG. 2b is a combined front and cross-sectional view of an embodiment of a four-lobe cargo tank at dotted line KK as shown in FIG. 2a. [Figure 2d] FIG. 2c is a combined isometric and diagonal cross-sectional view of an embodiment of a four-lobe cargo tank at the same cross-section as FIG. 2b. [Figure 3a] FIG. 1 is a side view of a four-lobe cargo tank with the main lobes arranged with stiffening ribs. [Figure 3b] 3b is an isometric view and a partial cross-sectional view taken along the plane indicated by line LL in FIG. 3a. [Figure 3c] FIG. 3b is an enlarged detail view from the dotted circle marked M from FIG. 3b. [Figure 4a] FIG. 1 illustrates the arrangement of the four-lobe cargo tanks arranged as cargo tanks shown arranged in a cross section of a vessel such as the hull of a ship. [Figure 4b] FIG. 4b is a top view showing an embodiment of a four-lobe cargo tank arranged as a cargo tank in the hull plan section PP of FIG. 4a. [Figure 5a] FIG. 4b is another view of the embodiment shown in FIG. 4a. [Figure 5b] FIG. 4c is another view of the embodiment shown in FIG. 4b. [Figure 6a] FIG. 1 illustrates an embodiment of a four-lobe cargo tank deployed as a cargo tank on a ship. [Figure 6b] FIG. 1 illustrates an embodiment of a four-lobe cargo tank deployed as a cargo tank on a ship. [Figure 6c] FIG. 1 illustrates an embodiment of a four-lobe cargo tank deployed as a cargo tank on a ship. [Figure 7a] FIG. 1 illustrates an embodiment of the present invention in which a four-lobe cargo tank is installed on a vessel. [Figure 7b] 1 illustrates an embodiment of a vessel in the section below the tank top. FIG. [Figure 8a] FIG. 1 is a centerline section view showing an embodiment of the invention in which a four-lobe cargo tank is arranged on a ship as a combination cargo tank. [Figure 8b]FIG. 1 illustrates an embodiment of the invention in which a four-lobe cargo tank and a cryogenic cargo tank are installed on a vessel as a combination cargo tank. [Figure 9a] FIG. 1 is a cross-sectional view of a ship equipped with a combination cargo tank. [Figure 9b] FIG. 1 is a cross-sectional view of a ship equipped with a combination cargo tank. DETAILED DESCRIPTION OF THE INVENTION

[0013] Embodiments of the present invention will now be described, by way of example only, with reference to the following drawings: FIG. 1a shows an isometric view of an embodiment of a four-lobe cargo tank (1) having four main lobes (11), viewed from the second end cover (13b) side to more clearly show the common main central axis (a1) and the main lobe axes (a11). As shown, the common main central axis (a1) is located at the center of the four-lobe cargo tank (1). The figure further shows that the main lobe axes (a11) are located at the center of the cylinder sector of each of the main lobes (11). Each of the four lobes (11) has its own main lobe axis (a11).

[0014] Figure 1b shows an embodiment of a four-lobe cargo tank (1) having four main lobes (11) in an isometric view from the first end cover (13a) side, which is the top cover (13a) in an upright configuration about a common main central axis (a1). Figure 1b shows the cylinder sector outer shell (12) of each main lobe (11), which retains the configuration of half a cylindrical tube and extends from the first end cover (13a) to the second end cover (13b). Figure 1b shows the first end cover (13a), - four quarter-spherical shell portions (14a); - four cylindrical 45° cut pipe sections (15a); - a first end cover (13a) with a central common pipe (20).

[0015] Figure 1c shows an end view of one embodiment of a second end cover (13b) for a four-lobe cargo tank (1). - four quarter-spherical shell sections (14b); - four cylindrical 45° cut pipe sections (15b); - a second end cover (13b) with a central common pipe (20).

[0016] Figure 2a shows an end view of an embodiment of a first end cover (13a) of a four-lobe cargo tank (1). Figure 2a shows a transverse axis (a15), indicated by the dotted line KK, extending diagonally between two of the four cylindrical 45-degree cut pipe sections (15a). The transverse axis (a15) is the diagonal centerline between the two opposing cylindrical 45-degree cut pipe sections that traverse the first end cover (13a) and the second end cover (13b). Figure 2a also shows a centerline, marked NN, that divides the first end cover (13a) of the four main lobe cargo tank (1) into two halves.

[0017] Figure 2b shows a combined front and cross-sectional view of one embodiment of a four-lobe cargo tank (1) taken along the centerline NN shown in Figure 2a, illustrating the internal structure, such as perforated bulkheads (16) and web frames (17), including a central pipe (20). As shown, the web frames (17) extend between the first and second ends of the central pipe (20), and the perforated bulkheads (16) are positioned within the area between the web frames (17) and the central pipe (20), as shown. An alternative embodiment (not shown) places the perforated bulkheads (16) between the web frames (17) and joins the perforated bulkheads (16) together at a common main central axis (a1) without the central pipe (20).

[0018] Figure 2c shows a combined front and cross-sectional view of an embodiment of a four-lobe cargo tank (1) taken along the dashed line K-K as shown in Figure 2a, with one of the transverse axes (a15) of the second end cover (13b) shown at an inclination angle α from a baseline perpendicular to the common main central axis (a1). The figure further shows that the first and second end covers (13a, 13b) comprise their quarter-spherical shell sections (14a, 14b) and cylindrical 45-degree cut-pipe sections (15a, 15b). A cross section of the center pipe (20) is also shown in the figure.

[0019] Figure 2d shows a combined isometric and diagonal cross-sectional view of an embodiment of a four-lobe cargo tank (1) at the same cross-section as Figure 2b, providing an overview of the interior space of the four-lobe cargo tank (1) and its internal structure with perforated bulkheads (16) and web frames (17), as well as a cross-section of the center pipe (20).

[0020] FIG. 3a shows a side view of a four-lobe cargo tank (1) with main lobes (11) arranged with reinforcing ribs (18). The figure further shows that web frames (17) partially protrude between the main lobes (11) at the first and second end covers (13a, 13b) near the central pipe (20) and join the cylindrical 45-degree cut pipe sections (15a, 15b) of the main lobes (11), which in turn join the quarter-spherical shell sections (14a, 14b). FIG. 3a shows an embodiment in which the reinforcing ribs extend around the cylinder sector outer shells (12). A portion of the figure (which may be the top in one embodiment) includes a dotted axial-transverse line LL to indicate the cross-sectional plane position in the isometric cross-section of the following FIG. 3b.

[0021] Figure 3b shows an isometric view and partial cross-section along the plane indicated by line LL in Figure 3a. Figure 3b shows an isometric view of one embodiment of a four-lobe cargo tank (1) at cross-section LL, showing a portion of the internal structure of all four main lobes (11). Figure 3b also shows an embodiment of the invention in which the center pipe (20) is reinforced with center pipe stiffeners (21) to prevent buckling of the center pipe (20); in other embodiments, the center pipe (20) can be manufactured with a greater wall thickness to withstand buckling forces. The perforated bulkhead (16) is also shown with bulkhead stiffeners (19) for the perforated bulkhead (16); in a preferred embodiment, these bulkhead stiffeners (19) are positioned to extend between the center pipe stiffeners (21) and the reinforcing ribs (18). The bulkhead stiffeners (19) are located primarily on one side of the perforated bulkhead (16) and are primarily directed radially outward from the central pipe stiffener (21) towards the reinforcing ribs (18). Figure 3b also shows a dotted circle marked M, which indicates a portion of the drawing that is enlarged for greater detail in Figure 3c.

[0022] Figure 3c shows an enlarged detail view from the dotted circle marked M from Figure 3b. This figure illustrates an embodiment of a four-lobe tank with the web frame (17) assembly configuration connecting two adjacent cylinder sector outer shells (12) and the web frame (17) and reinforcing rib (18) configuration (below plane LL). The figure also illustrates the arrangement of the web frame (17) and the perforated bulkhead (16), where the web frame (17) has a thickness (t1) greater than the thickness (t2) of the perforated bulkhead. Such an embodiment contributes to saving material without reducing the strength of the four-lobe cargo tank (1).

[0023] Figure 4a shows an arrangement of the four-lobe cargo tanks (1) arranged as cargo tanks shown arranged in a cross-section of a hull (2), such as the hull of a ship, with the four-lobe cargo tanks (1) arranged with their common main central axis (a1) in a vertical position (a vertical position in which the main central axis (a1) is primarily perpendicular to the hull tank top). Figure 4a shows an embodiment with two four-lobe cargo tanks (1) arranged side by side across the width of the hull (2). Figure 4 also shows a dotted line marked PP, which indicates the plane of the cross-section shown in Figure 4b.

[0024] Figure 4b shows a top view of an embodiment of four-lobe cargo tanks (1) arranged as cargo tanks in the planar cross section PP of the hull (2) of Figure 4a above. This figure shows a planar cross section of the hull (2), including a top view of two four-lobe cargo tanks (1) arranged side by side on the port and starboard sides, and arranged in three rows fore and aft, for a total of six four-lobe cargo tanks.

[0025] Figures 5a and 5b show another view of the embodiment shown in Figures 4a and 4b. Figures 6a, 6b and 6c show an embodiment of a four-lobe cargo tank (1) arranged as a cargo tank on a vessel (0). Figure 6a shows a cross section of the vessel (0) at the centreline, with the four-lobe cargo tank (1) installed vertically on the vessel tank top (3). Figure 6b shows an embodiment in which a top deck is arranged above the four-lobe cargo tank (1). Figure 6c shows a mid-section of the vessel (0), with two four-lobe cargo tanks (1) arranged with a common vertical main central axis (a1) within the hull (2).

[0026] Figure 7a shows an embodiment of the invention in which the four-lobe cargo tanks (1) are installed on a vessel (0). Figure 7a shows a plan view of 20 four-lobe cargo tanks (1) arranged in two rows across the width of the vessel (0) on the main deck. Figure 7b shows an embodiment of the vessel (0) in the section below the tank top.

[0027] Figure 8a shows an embodiment of the invention in a centerline cross section in which a four-lobe cargo tank (1) is arranged on a ship (0) as a combi cargo tank (4, 1, 30). The ship (0) equipped with a combi cargo tank (4) comprises the four-lobe cargo tank (1) and further comprises a cryogenic cargo tank (30), such as an LNG tank. Figures 8a and 8b show an embodiment in which the four-lobe cargo tank (1) is arranged horizontally on the ship (0) as a combi cargo tank (4, 1, 30), meaning that the common main central axis (a1) is primarily parallel to the ship tank top (6) of the combi cargo tank.

[0028] Figure 8b shows an embodiment of the present invention in which the four-lobe cargo tanks (1) and the cryogenic cargo tanks (30) are installed on the ship (0) as a combination cargo tank (4,1,30). Figure 8b shows a plan view of a combination cargo tank (4,1,30) in which ten four-lobe cargo tanks (1) and five cryogenic cargo tanks (30) are arranged on the main deck, seven fore and aft and two across the width, with one cryogenic cargo tank (30) located on the bow side of the ship (0).

[0029] Figure 9a shows a cross-section of a ship (0) equipped with a combi cargo tank (4), with an axis (20) passing through the cross section of two four-lobe cargo tanks (1) arranged on said ship (0) equipped with combi cargo tanks (4). The figure shows the four-lobe cargo tanks (1) installed horizontally in a longitudinal orientation on the ship tank top (6) of said combi cargo tanks within said combi cargo tank hull (5).

[0030] Figure 9b shows a cross-section of the vessel (0) with a combi cargo tank (4), showing an embodiment in which two cryogenic cargo tanks (30) are arranged on the vessel (0) in a vertical axial direction, with the combi cargo tanks (4, 1, 30) in cross-section.

[0031] MODE FOR CARRYING OUT THE INVENTION The present invention provides a four-lobe cargo tank (1) for transporting and / or storing liquefied gas, The tank (1) has four main lobes (11), each having a cylinder sector outer shell (12) and a main lobe axis (a11); the four main lobes (11) are arranged such that the four main lobe axes (a11) are axially parallel to and centered on a common main central axis (a1); The four main lobes (11) are joined by four web frames (17) to four diagonally correspondingly arranged perforated bulkheads (16) directed outward from the main central axis (a1); The tank (1) further comprises first and second end covers (13a, 13b); Each end cover (13a, 13b) comprises four quarter-spherical shell sections (14a, 14b) forming end portions of the cylinder sector outer shell (12), respectively; The quarter spherical shell portions (14a, 14b) of the first and second end covers (13a, 13b) are joined and closed toward the main central axis (a1) by first and second diagonally arranged four cylindrical 45-degree cut pipe portions (15a, 15b), each of which is arranged such that its axis (a15) intersects the main axis (a1).

[0032] The present invention provides a four-lobe cargo tank (1) for transporting liquefied CO2, for example to enhanced oil recovery and storage, based on CO2 gas injection, in a one-way journey, and in a further embodiment configured for return voyage with other types of liquefied or pressurized gas, such as LNG, LPG, or ammonia. By utilizing the tank to transport gas in both directions, the cargo tank can be utilized both ways, making the return voyage more profitable than returning empty, resulting in an economically and environmentally advantageous trade.

[0033] The advantage of a four-lobe tank (1) is that the structural characteristics of its four main lobes (11) improve its overall strength qualities over a conventional cylindrical tank. A four-lobe tank (1) with the same pressure and cargo conditions increases its volume by approximately four times over a conventional cylindrical tank with the same shell thickness. This has the advantage that a four-lobe tank (1) can accommodate more cargo than individual conventional cylindrical tanks with the same design criteria, thereby taking up less space on a ship. In other words, the footprint of a four-lobe tank (1), when installed on a vertical axis, is only 66% of the footprint of four individual cylindrical tanks with a radius equal to that of the lobes (11).

[0034] Another advantage of the four-lobe tank (1) is its internal structure joined by four web frames (17) that have a thickness greater than the four corresponding diagonally arranged perforated bulkheads (16) directed outward from the main central axis (a1), resulting in increased strength, particularly for containing cargoes that have relatively high densities and pressures during transportation, such as containing liquefied CO2, without increasing the weight of the four-lobe tank (1) relative to the use of multiple perforated bulkheads of equal thickness.

[0035] In addition to the above advantages, the assembly of the four-lobe tank (1) is more efficient and results in less material waste than other prior art four-lobe tanks available on the market. The present invention also provides a four-lobe cargo tank that is easier to manufacture and less resource-intensive, since the end cap consists of only two distinct, easily manufactured parts (i.e., a 2x4 "quarter shell section" and a 2x4 "cylindrical 45-degree cut pipe section"), which can be fabricated from two complete spherical shells and two relatively short pieces of pipe with a length equal to the radius of the quarter-spherical shells. This significantly reduces material consumption and greatly simplifies the manufacture of the end cover components. Another important feature of the present invention is that it provides a four-lobe cargo tank for liquefied gases, such as LCO2 and LNG. Of these two liquefied gases, LCO2 operates at about -50°C at about 7 barg (about 700 kilopascals (kPa)) and has a specific gravity of about 1.7, while LNG operates at about -165°C at about 0.45 barg (about 45 kPa) and has a specific gravity of about 1. This means that such tanks carrying such liquefied gases may experience undesirable reductions in material strength associated with welding, unless constructed with this in mind, as in the present invention.

[0036] Web frames are defined as oversized members that replace frames or bulkheads at specific points and are stronger than normal frames or stiffeners, either through greater thickness or better material quality (stronger material).

[0037] A perforated bulkhead is defined as a thinner deviation bulkhead, e.g., a baffle plate, primarily to prevent slamming and sloshing and free surface effects, but also to increase strength, especially against tensile forces acting radially from the main central axis.

[0038] In one embodiment of the present invention, the four-lobe cargo tank (1) further comprises a central pipe (20) arranged coaxially with the main central axis (a1), The central pipe (20) joins each of the first and second diagonally arranged four cylindrical 45-degree cut pipe sections (15a, 15b) and the four web frames (17) near either end of the central pipe (20), The four perforated bulkheads (16) extend radially outward from the central pipe (20), in other words, the four perforated bulkheads are joined by the central pipe (20).

[0039] The reason for this arrangement is to locate cargo pipes for loading and unloading liquefied gas into and from the four-lobe cargo tank 1 through the central pipe 20. Another advantage is that cables for instrumentation, power, etc. can also be extended through the central pipe 20, and when the four-lobe cargo tank 1 is constructed on a large scale, passages for manual inspection and manholes to the main lobe 11 can also be arranged through the central pipe 20. Another advantage is that the welded joints between the four diagonally arranged perforated bulkheads 16 and the four web frames 17 can be connected at the central pipe 20; the same applies to the central pipe 20 joining the first and second diagonally arranged four cylindrical 45-degree cut pipe sections 15a, 15b, which can be welded to the central pipe 20.

[0040] In one embodiment of the present invention, the four-lobe cargo tank (1) further comprises at least one circumferential stiffening ring stiffener (18) for stiffening the cylinder sector outer shell (12). The circumferential stiffening ring stiffener (18) prevents buckling of the outer shell (12). Another advantage is that the four-lobe cargo tank (1) can withstand higher internal pressures without increasing the thickness of the cylinder sector outer shell. Such a stiffening ring stiffener (18) can also be used as structural support for placement on a ship (0). The stiffening ring stiffener (18) can be placed on the outside of the four-lobe cargo tank (1) or on the inside of the four-lobe cargo tank (1) [as shown in Figures 3a-3c]. When the stiffening ring stiffener (18) is placed on the inside of the four-lobe cargo tank (1), the stiffening ring stiffener (18) becomes part of the internal structure of the four-lobe cargo tank (1).

[0041] In one embodiment of the present invention, each of the four diagonally arranged cylindrical 45° cut pipe sections (15b) having a transversely arranged axis (a15) is inclined towards the corresponding end of the central common pipe (20) so as to allow the tank liquid to drain towards and into a drain in the central common pipe (20) when installed in a vertical position. In one embodiment of the present invention, the inclination angle α is 5°.

[0042] In one embodiment of the invention, the liquefied gas comprises liquefied carbon dioxide. In another embodiment of the invention, the liquefied gas comprises liquefied natural gas, liquefied ammonia, or compressed natural gas.

[0043] In one embodiment of the invention, the four-lobe cargo tank (1) is a pressure vessel capable of handling pressures up to 12 barg (12 megapascals (MPa)). In another embodiment of the invention, the four-lobe cargo tank (1) is a pressure vessel capable of handling pressures up to 8 barg. In another embodiment of the invention, the four-lobe cargo tank (1) is a pressure vessel capable of handling pressures above 5.2 barg.

[0044] In a further embodiment of the invention, the pressure vessel is also cryogenically configured to contain liquefied carbon dioxide (CO2). In a further embodiment of the invention, the pressure vessel is also configured to contain liquefied natural gas (LNG) at atmospheric pressure.

[0045] In one embodiment of the present invention, a four-lobe cargo tank (1) is configured to be installed on board a ship (0). In one embodiment of the present invention, the four-lobe cargo tank (1) is configured to be carried on board a ship (0) as a combination cargo tank (4) together with a cryogenic cargo tank (30).

[0046] In one embodiment of the present invention, the web frame (17) protrudes between the four main lobes (11), thereby also serving as a connecting flange for the four main lobes (11) and reinforcing the four-lobe cargo tank (1). This reinforces the structure of the cargo tank (1), which is particularly useful when the cargo tank functions as a pressure vessel. This embodiment also provides advantages with regard to the welding of parts, in that overlapping weld seams are avoided.

[0047] In one embodiment of the present invention, the materials of construction of said four-lobe cargo tank (1) are qualified with enhanced mechanical properties for cryogenic use. In one embodiment of the invention, the central pipe (20) protrudes beyond each end cover (13). In a further embodiment of the invention, the protruding portions of the central pipe (20) are arranged as the main bearing points of the four-lobe cargo tank (1).

[0048] In one embodiment of the present invention, the central pipe (20) protrudes from one or more end covers (13), and the protruding portion of the central pipe (20) is configured as a lifting point for the four-lobe cargo tank (1).

[0049] In one embodiment of the present invention, the material of said four-lobe cargo tank (1) is low temperature steel, such as carbon manganese steel, nickel steel, stainless steel, etc. In one embodiment of the present invention, the material of said four-lobe cargo tank (1) comprises cryogenic materials such as nickel steel (e.g., 9% Ni), stainless steel, high manganese steel (e.g., NV-Mn400).

[0050] In one embodiment of the present invention, the material of said four lobe tank (1) is a combination of low temperature steel and cryogenic material. In one embodiment of the present invention, there is provided a method of transporting gas, comprising the steps of: using a vessel (0) according to the above; loading liquefied natural gas (LNG) into said one or more four-lobe tanks (1) at an LNG loading terminal under cryogenic conditions; Sailing the vessel (0) to an LNG unloading terminal; unloading the liquefied natural gas (LNG) for consumption at the unloading terminal; If necessary, sailing said vessel (0) to a loading terminal for liquefied carbon dioxide (CO2); loading the one or more four-lobe tanks (1) with the captured liquefied carbon dioxide (CO2); and sailing the captured liquefied carbon dioxide (CO2) to a liquefied carbon dioxide (CO2) offloading terminal for permanent storage or industrial consumption.

[0051] In another embodiment of the present invention, there is provided a method of transporting gas, comprising the steps of: using a vessel (0) according to any of the above embodiments; loading liquefied natural gas (LNG) under cryogenic conditions into one or more cryogenic cargo tanks (30) at an LNG loading terminal; Sailing the vessel (0) to an LNG unloading terminal; unloading the liquefied natural gas (LNG) at the unloading terminal for storage, further transport or consumption; If necessary, sailing the vessel (0) to a loading terminal for liquefied carbon dioxide (CO2); loading the one or more four-lobe tanks (1) with the captured liquefied carbon dioxide (CO2); and sailing the captured liquefied carbon dioxide (CO2) to a liquefied carbon dioxide (CO2) offloading terminal for permanent storage or industrial consumption. [Explanation of symbols]

[0052] α...Inclination angle of the transverse direction arrangement axis (a15) t1...thickness of the web frame (17), plate thickness, and t1>t2 t2: Thickness of perforated bulkhead (17), plate thickness 0...Ships, typically liquefied gas carriers 1...4 lobe tank a1...Common main central axis (1) 11...Main Robes (4) a11...Main lobe axis (4) 2... Hull, typically the hull of a ship 3...Ship Tank Top 4...Vessels with combined cargo tanks (0) 5...Hull of a combined cargo tank ship 6... Tank top of a combination cargo tank ship 12...Cylinder sector outer shells (4 pieces) 13a...First end cover (2 pieces) 13b...Second end cover (2 pieces) 14a...First quarter-spherical shell section (4 pieces) 14b...Second quarter-spherical shell section (4 pieces) 15a...First cylindrical 45-degree cut pipe section (4 pieces) 15b...Second cylindrical 45-degree cut pipe section (4 pieces) a15...Transverse axis (a15) of the cylindrical 45-degree cut pipe section (4) 16...Perforated bulkhead (4 pieces) 17...Web frames (4) 18...Circumferential reinforcing ring stiffener 19...Bulkhead stiffener 20...Central pipe (1) 21...Central pipe stiffener (reinforcement ring stiffener) 30...Cryogenic cargo tank, typically an LNG cargo tank

Claims

1. A four-lobe cargo tank (1) for transporting and / or storing liquefied gas, said tank (1) comprising four main lobes (11), each main lobe (11) having a cylinder sector outer shell (12) and a main lobe axis (a11); the four main lobes (11) are arranged such that the four main lobe axes (a11) are axially parallel to and centered on a common main central axis (a1); The four main lobes (11) are joined by four web frames (17) to four diagonally correspondingly arranged perforated bulkheads (16) directed outward from the main central axis (a1); The tank (1) further comprises first and second end covers (13a, 13b); each end cover (13a, 13b) comprises four quarter-spherical shell sections (14a, 14b) respectively forming end portions of said cylinder sector outer shell (12); 1. A four-lobe cargo tank (1), wherein the quarter-spherical shell sections (14a, 14b) of each of the first and second end covers (13a, 13b) are joined and closed towards the main central axis (a1) by first and second diagonally arranged four cylindrical 45-degree cut pipe sections (15a, 15b), each of which has its axis (a15) arranged transverse to the main central axis (a1).

2. Further comprising a central pipe (20) arranged coaxially with the common main central axis (a1), The central pipe (20) connects the first and second diagonally arranged four cylindrical 45-degree cut pipe sections (15a, 15b) and the four web frames (17) at either end of the central pipe (20), The four perforated bulkheads (16) extend radially outward from the central pipe (20); 2. The four-lobe cargo tank (1) according to claim 1, wherein the central pipe (20) is arranged for routing cargo pipes and cables within the main lobes (11).

3. 3. A four-lobe cargo tank (1) according to claim 2, wherein the central pipe (20) is provided with a manhole to the main lobe (11), such as a passage for manual inspection.

4. 2. The four-lobe cargo tank (1) according to claim 1, further comprising at least one circumferential reinforcing ring stiffener (18) for reinforcing the cylinder sector outer shell (12).

5. 2. A four-lobe cargo tank (1) according to claim 1, wherein the second four diagonally arranged cylindrical 45 degree cut pipe sections (15b) having transversely arranged axes (a15) are inclined towards corresponding ends of the central common pipe (20) so that when installed in a vertical position, the liquid discharge path of the tank is inclined towards and into a drain in the central common pipe (20).

6. 2. The four-lobe cargo tank (1) according to claim 1, wherein the liquefied gas comprises liquefied carbon dioxide.

7. 6. The four-lobe cargo tank (1) of claim 5, further configured such that the liquefied gas comprises liquefied natural gas, liquefied ammonia, or compressed natural gas.

8. 2. The four-lobe cargo tank (1) of claim 1, wherein the four-lobe cargo tank (1) is a pressure vessel capable of handling pressures up to 12 barg (1.2 megapascals).

9. 7. The four-lobe cargo tank (1) according to claim 6, wherein the pressure vessel is also cryogenically configured to contain liquefied carbon dioxide (CO2).

10. 10. The four-lobe cargo tank (1) of claim 1, further configured to contain liquefied natural gas (LNG) at atmospheric pressure.

11. 11. The four-lobe cargo tank (1) according to any one of claims 1 to 10, wherein the web frame (17) protrudes from between the four main lobes (11), thereby also functioning as a connecting flange for the four main lobes (11) and reinforcing the four-lobe cargo tank (1).

12. 12. The four-lobe cargo tank (1) according to any one of claims 1 to 11, wherein a central pipe (20) protrudes from one or more end covers (13), the protruding portion of the central pipe (20) being configured as a lifting point and / or a fixing point for the four-lobe cargo tank (1).

13. A ship, a liquefied gas carrier (0), comprising at least one four-lobe cargo tank (1) according to any one of claims 1 to 12.

14. 1. A method of transporting gas, comprising: Using a vessel, a liquefied gas carrier (0), according to claim 13; loading liquefied natural gas (LNG) into said one or more four-lobe tanks (1) at an LNG loading terminal under cryogenic conditions; Sailing the vessel, the liquefied gas carrier (0), to an LNG unloading terminal; unloading the liquefied natural gas (LNG) for consumption at the unloading terminal; If necessary, sailing said liquefied gas carrier (0) to a loading terminal for liquefied carbon dioxide (CO2); loading the captured liquefied carbon dioxide (CO2) into one or more four-lobe tanks (1) at said loading terminal for liquefied carbon dioxide (CO2); and sailing the vessel, a liquefied gas carrier (0), with the captured liquefied carbon dioxide (CO2) to a liquefied carbon dioxide (CO2) offloading terminal for permanent storage or industrial consumption.

15. 1. A method of transporting gas, comprising: Using a vessel, a liquefied gas carrier (0), according to claim 13; loading liquefied natural gas (LNG) under cryogenic conditions into one or more cryogenic cargo tanks (30) at an LNG loading terminal; Sailing the vessel, the liquefied gas carrier (0), to an LNG unloading terminal; unloading the liquefied natural gas (LNG) for consumption at the unloading terminal; If necessary, sailing said liquefied gas carrier (0) to a loading terminal for liquefied carbon dioxide (CO2); loading the collected liquefied carbon dioxide (CO2) into the one or more four-lobe tanks (1) at the loading terminal for liquefied carbon dioxide (CO2); and sailing the vessel, a liquefied gas carrier (0), with the captured liquefied carbon dioxide (CO2) to a liquefied carbon dioxide (CO2) offloading terminal for permanent storage or industrial consumption.

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