CN115244329A

CN115244329A - Double entry hatch for liquefied gas transport tanks

Info

Publication number: CN115244329A
Application number: CN202180020429.5A
Authority: CN
Inventors: J.库托; E.杜克洛伊
Original assignee: Gaztransport et Technigaz SA
Current assignee: Gaztransport et Technigaz SA
Priority date: 2020-01-13
Filing date: 2021-01-13
Publication date: 2022-10-25
Also published as: KR20220127853A; FR3106190A1; FR3106190B1; JP2023510861A; WO2021144531A1

Abstract

The invention relates to a wall (1) of a tank for storing and/or transporting liquefied gas, comprising a conduit (2) passing through the wall (1) in a thickness direction (E) of the wall and a closure device (3) configured to close the conduit (2), the closure device (3) comprising at least one hatch (4) configured to open into the tank interior.

Description

Double entry hatch for liquefied gas transport tanks

Technical Field

The present invention relates to the field of storage tanks, in particular tanks for storing liquefied gases. More particularly, the invention relates to devices for accessing the interior of such tanks, for example for inspection and/or maintenance operations.

Background

Liquefied gas carriers usually have a double-walled structure which delimits a tank for receiving liquefied gas. "liquefied gas" is understood to mean any object which is in the vapour state under standard pressure and temperature conditions and which is in the liquid state by lowering its temperature. The tank comprises an upper wall which is usually interrupted by openings at several locations. These openings may be protruding structures in the form of, for example, towers or chimneys, and correspond to structures known as gas domes, liquid domes or manholes. The first tower serves as an entry point for various equipment for handling goods, i.e. a filling line, an emergency pumping line, an unloading line connected to an unloading pump, a spraying line connected to a spraying pump and a supply line. The second column acts as the inlet to the vapor collection tube.

Thus, the tank may comprise a submersible pump for unloading liquefied gas. Openings are provided in the upper wall for maintenance and/or inspection of the submersible pump. The other opening, separate from the opening dedicated to the unloading pump, is provided for tank maintenance. The latter opening is thus dimensioned to allow passage of replacement parts of the structure of the can.

A first drawback of these openings at several locations of the upper wall of the tank is the increased risk of leakage at the welding points through which the membrane passes.

A second drawback of such multiple openings is that the insulation of the tank is reduced due to the resulting thermal bridges, which results in greater evaporation of the liquefied gas contained in the tank and, ultimately, in reduced transport capacity of the ship equipped with such a tank.

A third drawback of such multiple openings is that the presence of the openings increases the complexity of the design and manufacture of such tanks, in particular with respect to the arrangement of the individual insulating layers, the metal parts constituting the membrane and the mechanical constraints resulting from these openings.

Disclosure of Invention

The object of the present invention is to overcome at least one of the above drawbacks, and to bring further advantages, by proposing a new wall for a tank for transporting and/or storing liquefied gas.

Another object of the invention is to rationalise the number of openings in the wall of a tank for transporting and/or storing liquefied gas.

According to one embodiment, the invention provides a wall of a tank for storing and/or transporting liquefied gas. The wall includes a conduit passing through the wall in a thickness direction of the wall and a closing device configured to close the conduit. The closure device includes at least one hatch configured to provide access to the interior of the tank.

The invention thus makes it possible to combine two openings in the upper wall of the tank, both opening into the same internal volume of the tank. Furthermore, rather than having interruptions of the sealing membrane and the thermal insulation barrier at two separate locations of the upper wall, the only interruptions are now at a single location. Thus, the sealing of the wall and the thermal insulation of the same wall are improved.

According to one embodiment, the closure device is an assembly that incorporates a plurality of elements, such as a hatch, a cover, a second conduit, a first plug and/or a second plug. These elements will be explained in detail below.

According to one embodiment, the duct has a quadrangular cross section, seen from a plane orthogonal to the thickness direction of the wall.

According to one embodiment, the quadrilateral cross-section is a square.

According to one embodiment, one side of the square has a length between 1.3m and 1.7m, preferably between 1.4m and 1.5 m.

According to one embodiment, the conduit has a circular cross-section, seen in a plane orthogonal to the thickness direction of the wall.

According to one embodiment, the diameter of the circular cross-section is between 1.3m and 1.7m, preferably between 1.4m and 1.5 m.

According to one embodiment, the conduit comprises a first mouth configured to open to the environment outside the tank and a second mouth configured to open to the interior of the tank, and the closure device comprises a cap closing the first mouth.

According to one embodiment, the cover and the hatch each extend in a separate plane.

According to one embodiment, the extension plane of the cover is substantially parallel to the extension plane of the hatch.

According to one embodiment, the plane of extension of the closure means and the plane of extension of the lid are substantially orthogonal to the thickness direction of the wall.

According to one embodiment, the lid has an aperture leading to the tank interior, and the hatch is configured to close the aperture. Thus, the hatch may be mechanically connected to and/or placed on the cover.

According to one embodiment, the conduit is a first conduit and the closure device comprises a first plug extending at least partially in the thickness of the wall and adjacent to the interior face of the first conduit, and a second plug extending at least partially in the thickness of the wall and extending inside the first conduit, the first plug and the second plug being separated by the second conduit. It should be understood that here and in all following, the plug is a movable element that at least partially serves to close the conduit by inserting at least a portion of the plug into the conduit.

According to one embodiment, at least a portion of the second stopper has a shape complementary to the inner face of the second conduit.

According to one embodiment, the second plug and the hatch are fixed to each other. It should be understood here that the second plug and the hatch are connected to each other in such a way that the extraction or tilting of the hatch carries the second plug in this movement.

According to another embodiment, the second plug comprises a thermally insulating material.

According to one embodiment, the second plug comprises a casing delimited by the hatch and a panel connected to the hatch by at least one rod, the second plug comprising an insulating material arranged in the casing. The insulating material is arranged between the hatch and the panel, for example in the thickness direction of the wall.

According to another embodiment, the second plug comprises an insulating material attached to the lower face of the hatch and a panel fixed to the insulating material.

According to one embodiment, the insulating material extends in the second conduit for a length measured in the thickness direction of the wall which is at most equal to the length of the second conduit measured in the thickness direction of the wall.

According to one embodiment, the insulating material extends over the entire length of the second conduit measured in the thickness direction. The second plug thus has an insulating capacity at least corresponding to the wall of the tank in the region without the opening.

According to one embodiment, the insulating material comprises polyurethane foam. According to one embodiment, the polyurethane foam is reinforced with glass fibers.

According to another embodiment, the insulating material comprises polyethylene foam or polypropylene foam.

According to another embodiment, the insulating material comprises mineral wool. According to one embodiment, the mineral wool is selected from the group consisting of glass wool, rock wool and mixtures thereof.

According to one embodiment, the panel is flush with the free end of the second conduit extending to the interior of the tank.

According to one embodiment, the panel has a circular cross-section, seen in a plane orthogonal to the thickness direction of the wall.

According to one embodiment, the panel is a plywood panel, a composite panel or a metal panel.

According to one embodiment, at least a portion of the first stopper has a shape complementary to the interior face of the first conduit. Thus, the first plug may fill the space defined by the interior face of the first conduit.

According to one embodiment, the first stopper and the lid are fixed to each other. This makes it possible to extract the first stopper while removing the cap.

According to one embodiment, the first plug comprises at least one thermally insulating self-supporting panel arranged around the second conduit. It is understood here that the insulating self-supporting panel extends from the inner face of the first duct to the second duct, that is to say to the outer face of the second duct, surrounding the latter.

According to one embodiment, the first plug comprises an adhesive configured to create a mechanical connection between the insulated self-supporting panel and the lid. In other words, the insulated self-supporting panel is fixed to the lid by means of an adhesive. According to one embodiment, the adhesive is mastic. Advantageously, the mastic can compensate for the flatness defects of the hull, placing the first plug and the insulation panel on the same level along the vertical axis Z.

According to one embodiment, an insulated self-supporting panel includes a rigid polyurethane insulation block and a plywood panel having the rigid polyurethane block resting thereon. According to another embodiment, the plywood panel may be replaced by a composite panel or a metal panel, for example a panel made of stainless steel or aluminium.

According to another embodiment, the insulated self-supporting panel comprises a box formed of plywood panel and filled with mineral wool, such as glass wool and/or rock wool.

According to one embodiment, the insulated self-supporting panel is in contact with an interior face of the first conduit. Thus, there is no space between the inner face of the first conduit and the insulated self-supporting panel.

According to one embodiment, the insulated self-supporting panel is in contact with the second conduit. Thus, there is no space between the second conduit and the insulated self-supporting panel.

According to one embodiment, the first plug comprises mineral wool, such as glass wool and/or rock wool. The mineral wool makes it possible to fill possible spaces between the self-supporting panels and/or to fill spaces between the self-supporting panel(s) surrounding the second duct and the second duct itself.

According to one embodiment, the insulated self-supporting panel is flush with the free end of the second conduit extending to the interior of the tank.

According to one embodiment, the surface area of the cross-section of the second conduit is smaller than the surface area of the cross-section of the first conduit, these cross-sections being seen in a plane orthogonal to the thickness direction of the wall.

According to the invention, the cross sections of the second conduit are inscribed in the cross sections of the first conduit, these cross sections being visible in a plane orthogonal to the thickness direction of the wall.

According to one embodiment, the second duct has a circular cross-section, seen in a plane perpendicular to the thickness direction of the wall.

According to one embodiment, the diameter of the circular cross-section of the second conduit is between 0.8m and 1.2m, more particularly between 0.9m and 1.1 m.

According to another embodiment, the second duct has a triangular cross-section or a quadrangular cross-section, e.g. a square or rectangular cross-section, seen in a plane perpendicular to the thickness direction of the wall.

According to one embodiment, the second duct comprises a flange configured to cooperate with the hatch in order to close the second duct. In other words, the hatch is supported on the flange so as to cover the second duct. In other words, the hatch rests on the cover to completely close the external opening of the second duct.

According to one embodiment, the second conduit comprises a free end inside the tank, which free end extends in an extension plane parallel to the extension plane of the wall, the extension planes being separated from each other.

According to one embodiment, the flange surrounds the second duct at the first opening. In other words, the flange extends circumferentially over the contour of the first opening.

According to one embodiment, the cover and the second conduit are firmly connected to each other. The cover and the second conduit are for example welded to each other and/or held on each other by clamping with a plurality of bolts. The welding may for example be performed on an outer face of the second conduit, opposite to an inner face of the second conduit. It will be appreciated that in this case the second conduit passes through the cap via a hole it has.

According to one embodiment, the upper portion of the second conduit protrudes from the lid towards the outside of the tank in the thickness direction of the wall.

According to one embodiment, the closing means comprise a reinforcement arranged circumferentially against the second conduit, the reinforcement extending from the lid towards the outside of the tank in the thickness direction of the wall.

According to one embodiment, the wall comprises, in its thickness direction, at least one thermal insulation barrier and at least one sealing membrane intended to be in contact with the liquefied gas inside the tank, the sealing membrane facing, at least partially, the first duct in the thickness direction of the wall. In other words, a portion of the sealing membrane blocks the first duct, both during the initial manufacture of the can and after the operations that require cutting of the sealing membrane.

Thus, the thickness direction of the wall can be defined as the direction perpendicular to the development plane of the sealing membrane.

According to one embodiment, the sealing membrane has a cut-out to let a portion of the second conduit pass.

According to one embodiment, the thermal insulation barrier is a primary thermal insulation barrier, the sealing membrane is a primary sealing membrane intended to come into contact with the liquefied gas inside the tank, the wall comprises a secondary thermal insulation barrier resting on which it rests and a secondary sealing membrane resting on which it rests, the primary sealing membrane resting on the primary thermal insulation barrier.

According to one embodiment, the primary sealing membrane comprises corrugations.

According to one embodiment, the invention proposes a tank for storing and/or transporting liquefied gas, comprising at least one wall according to the invention.

According to one embodiment, the liquefied gas is a cryogenic fluid. The liquefied gas is selected from the group consisting of liquefied natural gas, liquefied petroleum gas, liquid ethane, liquid propane, liquid argon, liquid ammonia, and liquid hydrogen.

The closure device has been described in its closed position, but when it is in the open position, the second plug and/or the first plug and/or the hatch are outside the tank, the hatch being tilted, for example on a pivot, or completely detached from the closure device and therefore from the wall forming the subject of the invention. The same applies to the lid when it is detached from the tank wall.

According to one embodiment, the invention also provides a method for accessing the interior of a tank according to the invention, the method comprising: a step of removing the second plug to access the inside of the tank, that is to say from outside the tank to the inside of the tank, in order to perform maintenance operations, for example through equipment or by a person; a step of cutting a portion of the sealing membrane around the closing means; and a step of removing the closing means. Thus, it is possible to introduce larger equipment than during the first step from the outside of the tank into the inside of the tank, for example into the gussets of the primary or secondary layers of the tank.

Depending on the size of the hatch, it may also be referred to as a manhole. Depending on the size of the first conduit, it may also be referred to as an equipment hole.

According to one embodiment, the invention finally provides a closing method for closing a first conduit, obtained by the method for accessing the interior of a tank according to the invention, comprising a step of replacing the closing means on the first conduit, a step of welding the closing panel to the sealing membrane and a step of replacing the hatch.

Drawings

Further characteristics and advantages of the invention will become better apparent, on the one hand, from reading the following description, on the other hand, from a number of exemplary embodiments, given by way of non-limiting indication with reference to the accompanying drawings, in which:

fig. 1 is a perspective view of the exterior of a wall of a tank for storing and/or transporting liquefied gas according to the invention.

Fig. 2 is a cross-sectional view along the plane YZ and a perspective view of the wall shown in fig. 1.

Fig. 3 is an exploded view of the wall shown in fig. 2.

Detailed Description

It should be noted at the outset that although the drawings illustrate the present invention in a detailed manner in which it is practiced, they can, of course, be used to better define the invention where appropriate. It should also be noted that throughout the drawings, elements that are similar and/or perform the same function are referred to by the same reference numerals.

In the following description, the direction of the longitudinal axis X, the direction of the transverse axis Y and the direction of the vertical axis Z are represented in the figures by a trihedron (X, Y, Z). The horizontal plane is defined as a plane perpendicular to the vertical axis and includes the direction of the longitudinal axis X and the direction of the transverse axis Y; the longitudinal plane is defined as a plane perpendicular to the transverse axis and includes the direction of the longitudinal axis X and the direction of the longitudinal axis Z; the transverse plane is defined as a plane perpendicular to the longitudinal axis and includes the direction of the transverse axis Y and the direction of the longitudinal axis Z.

The direction of the longitudinal axis X is parallel to the longitudinal direction of the vessel comprising the tank according to the invention.

The figures are described below in the context of a support structure formed by the inner walls of a double hull of a ship for transporting liquefied gas. Such a support structure may in particular have a polyhedral geometry, for example a prismatic shape. The support structure includes longitudinal walls including a lower wall, a lateral wall, and an upper wall. The longitudinal walls extend parallel to the longitudinal direction of the vessel.

The longitudinal walls are interrupted in the longitudinal direction of the vessel by transverse walls perpendicular to the longitudinal direction of the vessel. The longitudinal and transverse walls meet at edges.

Each wall of the support structure supports a respective tank wall. In fig. 1 to 3, a wall 1 of a tank supported by an upper wall of a support structure is shown. As shown in these figures, the wall 1 comprises at least one thermal insulating barrier 7 against which a sealing membrane 8 is pressed, the sealing membrane 8 being intended to come into contact with the fluid stored in the tank, for example liquefied petroleum gas.

The insulating barrier 7 comprises an insulating material in the form of juxtaposed panels of insulating material. These panels comprise an expanded or porous synthetic resin or another natural or synthetic insulating material. Furthermore, the thermal insulation barrier 7 may comprise a filling material, such as mineral wool, for example glass wool or rock wool. The filler material is intended to be inserted between juxtaposed panels. These panels also include plywood panels. The resin is glued on a first side and the sealing membrane 8 is screwed and/or welded on a second side opposite to the first side. In an embodiment not shown, instead of glued panels, these panels comprise composite panels or metal panels, for example made of aluminum or stainless steel.

With reference to fig. 2 and 3, the wall 1 is interrupted at one location by a first conduit 2. In other words, the first conduit 2 extends through the wall 1 in the thickness direction E of the wall 1. Therefore, the thickness direction E of the wall may be defined as a direction perpendicular to the development plane of the sealing film 8. Here, the thickness direction E is parallel to the vertical axis Z.

The first duct 2 is intended to pass through an alternative part of the insulating barrier 7, such as a flat panel, a single-angled panel or a double-angled panel.

The first conduit 2 has a square cross section, seen in a plane orthogonal to the vertical axis Z. The first conduit 2 has the shape of a right cylinder with a square cross section developing along a vertical axis Z. The length of one side of the square is 1.47 meters. Here and in what follows, the term cylinder is understood to mean a conditioning surface with parallel generatrices, that is to say a surface of space consisting of parallel straight lines. Thus, it should be understood that the cross-section of the cylinder may be, for example, triangular, square, rectangular, polygonal, circular, or elliptical.

As shown in fig. 3, the first conduit 2 has a first mouth 5 open to the external environment of the tank and a second mouth 6 open to the interior of the tank. Between the first mouth 5 and the second mouth 6, the first conduit 2 comprises an inner face 70.

The first mouth 5 is surmounted by the support flange 30. The support flange 30 extends from the contour of the first mouth 5 towards the outside of the tank. The support flange 30 completely surrounds the contour of the first mouth 5. The support flange 30 therefore has a square profile in a plane orthogonal to the thickness direction E of the wall 1.

The support flange 30 is surrounded by stays 31 which are evenly arranged around the entire circumference of the flange. Brace 31 extends from the outer face 9 of the wall 1 and is mounted beneath the support flange 30 to support the flange and prevent it from sagging under loads applied to the support flange 30.

In the example shown in figures 2 and 3, the second mouth 6 is blocked by a portion 61 of the sealing membrane 8, which portion 61 is in contact with the second duct 12 extending in the first duct 2.

This portion 61 has a surface and a shape at least equal and equivalent to the surface corresponding to the projection of the first conduit 2 on a plane perpendicular to the thickness direction E of the wall 1. In other words, the surface area of the portion 61, as seen in projection on a plane perpendicular to the thickness direction E of the wall 1, is at least equal to the surface area of the first stopper 10, as will be described below. Furthermore, the portion 61 of the primary sealing film 6 has a shape at least partially equivalent to the shape of the first plug 10, seen in projection on a plane perpendicular to the thickness direction E of the wall 1. In other words, the portion 61 of the sealing membrane 8 extends until it comes into contact with the second duct 12 extending in the first duct 2, the sealing membrane 8 then partially facing the second mouth 6, thus at least partially or even completely obstructing it.

In other words, the sealing membrane 8 partially faces the second mouth 6, thus at least partially or even completely obstructing it.

Between the first mouth 5 and the second mouth 6, the inner face 70 of the first conduit 2 is delimited, for example, by at least one insulating element 71 of the insulating barrier 7. The insulating element 71 comprises glass wool or a flexible foam panel, for example made of polyurethane or melamine.

As shown in fig. 2 and 3, the first conduit 2 passes through the wall 1 in the thickness direction E of the wall 1. The wall of the first conduit 2 is delimited in the thickness direction E of the wall 1 by the support flange 30, the insulating elements 71 of the insulating barrier 7 and the sealing membrane 8.

With reference to fig. 1 to 3, according to the invention, the wall 1 comprises closing means 3 for closing the first duct 2. The closure device 3 comprises at least one cap 11, a first stopper 10 and a second conduit 12.

The cover 11 closes the first mouth 5 by resting on the support flange 30. Therefore, the cover 11 has the same shape as the support flange 30 as viewed in a plane orthogonal to the thickness direction E of the wall 1. Thus, the cover 11 has a square cross-section, as viewed in a plane orthogonal to the thickness direction E of the wall 1. Of course, this cross-sectional shape is only an example, and the cover has a shape similar to the cross-section of the first conduit.

The cover 11 extends in an extension plane perpendicular to the vertical axis Z. The lid 11 has an aperture 17, which aperture 17 provides access to the interior of the tank. The hole 17 allows the cover 11 to be passed through by the second conduit 12. The cover 11 and the second conduit 12 are fastened to each other and formed in one piece by welding. The welding is carried out on the external face of the second guide duct 12 along the circumference of the second guide duct 12, that is to say along its contour. Additionally or alternatively, the cover 11 and the second conduit 12 may be held on each other by clamping using bolts.

The second conduit 12 is intended to pass through a device for extracting the liquid or vapour phase of the liquefied gas, for example a pump, in order to discharge it from the tank.

The second conduit 12 has the shape of a right cylinder with a circular and hollow cross section, with a diameter between 0.9m and 1.2 m. Alternatively, the second conduit 12 may have a triangular or quadrangular, for example square or rectangular, cross section as seen in a plane perpendicular to the thickness direction E of the wall.

An upper portion of the second conduit 12 protrudes from an upper face of the lid 11 toward the outside of the tank in the thickness direction E of the tank. The upper portion of the second conduit 12 comprises a first mouth 15. The connecting flange 40 extends circumferentially over the contour of the first opening 15. Thus, the connecting flange 40 has a circular cross section as viewed in a plane orthogonal to the thickness direction E of the wall 1.

It should here be understood that the second conduit 12 extends in the volume defined by the first conduit 2. In other words, the second conduit 12 is inscribed in the first conduit 2. Therefore, the first opening 15 has a contour inscribed in the contour of the first mouth 5 and the second opening 16 has a contour inscribed in the contour of the second mouth 6, as viewed in a plane orthogonal to the thickness direction E of the wall 1.

On the other hand, the surface area of the first opening 15 is smaller than the surface area of the first mouthpiece 5 as viewed in a plane orthogonal to the thickness direction E of the wall 1, and the surface area of the second opening 16 is smaller than the surface area of the second mouthpiece 6 as viewed in a plane orthogonal to the thickness direction E of the wall 1.

The closing means 3 comprise a plurality of stiffeners 41, said plurality of stiffeners 41 being circumferentially arranged against the second conduit and extending from the upper face of the lid 11 towards the outside of the tank in the thickness direction E of the tank. The stiffeners 42 are evenly distributed around the upper portion of the second conduit 12. Each stiffener 41 includes a removal ring 42, the removal ring 42 extending from an upper face of the stiffener 41 in the vertical direction Z. These removal rings 42 allow the closing device 3 to be manoeuvred, for example by means of a crane.

The second conduit 12 comprises a lower portion extending along the vertical axis Z from the lower face of the lid 11 towards the inside of the tank. The free end of the lower part of the second conduit 12 comprises a second opening 16 to the interior of the tank. The second conduit 12 thus defines a passage between the first opening 15 and the second opening 16.

The first stopper 10 is arranged around the second conduit 12 and extends from the lower face of the lid 11 to near the free end of the lower part of the second conduit 12. The first stopper 10 may comprise the second conduit 12 in the sense that the extraction of the first stopper 10 results in the extraction of the second conduit 12.

The first plug 10 is fastened to the lower face of the cover 11, while leaving the periphery of the lower face for positioning the support flange 30. Thus, when the cap 11 is removed, the first stopper 10 is also removed. The first stopper 10 has a shape complementary to the internal face of the first conduit in a plane orthogonal to the thickness direction E of the wall 1. The first plug 10 has, for example, a square cross section, seen in a plane orthogonal to the thickness direction E of the wall 1.

The first plug 10 comprises an insulating self-supporting panel 13. The insulated self-supporting panel 13 is thus crossed by the second conduit 12. Seen in the direction of the vertical axis Z, the lower face of the insulated self-supporting panel 13 enters in the vicinity of the free end of the lower portion of the second duct 12.

The insulated self-supporting panel 13 comprises a block of rigid polyurethane insulation and a plywood panel on which the block of rigid polyurethane is placed. In embodiments not shown, the plywood panel may be replaced by a composite panel or a metal panel, for example made of stainless steel or aluminium. In an embodiment not shown, a rigid polyurethane insulation block is sandwiched between two plywood panels.

Alternatively, in an embodiment not shown, the thermally insulating self-supporting panel 13 comprises a box formed by a plywood panel, a composite panel or a metal panel, for example made of steel or aluminum, and filled with mineral wool, for example glass wool and/or rock wool.

The first plug 10 comprises an adhesive arranged between the insulating self-supporting panel 13 and the lower face of the lid 11. The adhesive allows adjustment of the insulating self-supporting panel 13 along the vertical axis Z and fastening of the insulating self-supporting panel 13 to the lid 11. For example, the adhesive may be mastic.

In the embodiment shown in figures 1 to 3, the first plug 10 also comprises mineral wool 14, for example glass wool and/or rock wool, arranged between the second conduit 12 and the insulating self-supporting panel 13. The mineral wool 14 ensures that the continuity of insulation is maintained between the second conduit 12 and the insulated self-supporting panel 13.

With reference to fig. 1 to 3, the closing device 3 also comprises a hatch 4 for closing the first opening 15 of the second duct 2 and, therefore, the hole 17 of the cover 11. The hatch 4 extends in a plane of extension orthogonal to the vertical axis Z as defined above, that is to say perpendicular to the thickness direction E of the wall 1. The extension plane of the hatch 4 is parallel to and spaced apart from the extension plane of the cover 11.

As shown in fig. 1, four wales 50 are arranged on the upper face of the hatch 4. The cross braces 50 serve to increase the rigidity of the hatch 4, thus preventing the hatch 4 from expanding and keeping it flat.

One of the two crossbars includes a lifting loop 51. The lifting ring 51 extends from the upper face of the wale 50 along the vertical axis Z to the outside of the tank. These lifting loops 51 make it possible to manipulate the hatch 4 with a crane, for example.

The lower face of the hatch 4, opposite to the upper face of the hatch 4, cooperates with the connecting flange 40 so as to close the first opening 15 of the second duct 12. The hatch 4 may be mechanically connected to the cover 11 and/or placed on the cover 11.

Referring to fig. 1 to 3, the closure device 3 further comprises a second plug 20. The second stopper 20 has a shape complementary to the internal face of the second conduit 12. Thus, in the example shown in the figures, the second stopper 20 is a right circular cylinder of circular cross section and this cross section may be equal to, for example, 8100cm ² 。

A second plug 20 is fixed to the lower face of the hatch 4. The periphery of the lower face of the hatch 4 is left free for the connection flange 40. Thus, when the hatch 4 is removed from the wall 1, the second plug 20 is also removed.

As shown in fig. 2 and 3, the second plug 20 includes a housing 24. The casing 24 is delimited along the vertical axis Z by the hatch 4 and by the glue panel 22, the glue panel 22 being connected to the hatch 4 by a plurality of rods 23, in particular four rods 23. The glue panel 22 has a circular cross-section as seen in a plane orthogonal to the vertical axis Z.

In an embodiment not shown, the plywood panel 22 may be replaced by a composite panel or a metal panel, for example made of stainless steel or aluminium.

An insulating material 25 is arranged in the housing 24. The insulation material 25 includes polyurethane foam. Such polyurethane foams may be reinforced with glass fibers. Alternatively, the insulating material 25 may comprise mineral wool, such as glass wool and/or rock wool.

Referring to fig. 2, the first conduit 2 is closed by a cover 11. The periphery of the lower face of the cover 11 is arranged on the support flange 30. In order to retain the cover 11 on the support flange 30, bolts (not shown) are arranged on the periphery of the support flange 30 to hold the cover 11 against the support flange 30 by clamping.

Since the first stopper 10 is fixed to the cover 11, the first stopper 10 is disposed in the first conduit 2 and blocks it. The first stopper 10 extends from the lower face of the cap 11 to the second mouth 6 of the first conduit 2. Furthermore, the first stopper 10 extends radially from the inner face of the first conduit 2 to the second conduit 12 and surrounds the second conduit 12. In other words, the first plug 10 is in contact with the inner face of the first conduit 2 through the insulating self-supporting panel 13. Thus, there is no space between the inner face of the first conduit 2 and the insulated self-supporting panel 13 of the first plug 10.

The portion of the sealing membrane 8 facing the first stopper 10 is fixed to the lower face of the insulated self-supporting panel 13 of the first stopper 10. A portion 61 of the sealing membrane 8 is opposite to the lower portion of the second duct 12. A portion of the second conduit 12 protrudes along a vertical axis Z into the interior of the tank with respect to the membrane portion 61, and this membrane portion 61 is fixed to the second conduit 12, for example by means of an attached angle iron.

In order to close the second duct 12, the periphery of the lower face of the hatch 4 is arranged on the connection flange 40. The hatch 4 is locked with the connecting flange 40 by means of bolts (not shown) which keep the hatch 4 pressed against the connecting flange 40.

As shown in fig. 2, a second plug 20 extends within the second conduit 12. Thus, the glue or metal panel 22 is flush with the second opening 16 of the second conduit 12. The insulating material 25 thus extends over the entire length of the lower portion of the second conduit 12, measured in the thickness direction E of the wall 1. Thus, the second stopper 20 is separated from the first stopper 10 by the second conduit 12.

The reference number 60 in figures 2 and 3 indicates a cutting line of the sealing membrane 8 along which the sealing membrane 8 must be cut in order to extract the first stopper 10, provided that the component to be introduced is too large to pass through the second duct 12. This mark is visible when a portion 61 of the sealing membrane 8 is re-welded to the rest of the sealing membrane 8, at which point the first duct 2 is closed after the cap 11 with the first stopper 10 has been repositioned.

The above-described technique of producing a tank with a single sealing membrane can be used for various types of vessels, for example to construct a double membrane tank for Liquefied Natural Gas (LNG) in a land-based or floating installation, such as a methane tanker or the like. Thus, a tank using the wall of the invention can be used for transporting cryogenic fluids. Alternatively or additionally, the tank according to the invention may also be a vessel containing cryogenic fluid used as fuel for the tanker's equipment.

It is believed that the sealing membrane 8 shown in fig. 1-3 is a primary sealing membrane, the thermal insulation barrier 7 is a primary thermal insulation barrier, and a secondary thermal insulation barrier and a secondary sealing membrane may be added between the wall of the support structure and the primary thermal insulation barrier. The secondary sealing membrane rests against the secondary insulating barrier, the primary insulating barrier rests against the secondary sealing membrane, and the primary sealing membrane rests against the primary insulating barrier. The primary sealing membrane 8 comprises corrugations and is thus a corrugated sealing membrane.

Thus, this technique can also be applied to tanks with multiple thermal barriers and stacked sealing membranes.

Depending on the size of the hatch 4, it may also be called a manhole. Depending on the size of the first conduit 2, it may also be referred to as a device orifice.

The liquefied gas may be liquefied natural gas, liquid ethane, liquid propane, liquid argon, liquid ammonia, and liquid hydrogen, in addition to petroleum gas. These fluids are cryogenic fluids.

A method for accessing the interior of a tank emptied of its contents, which tank comprises an upper wall constructed in accordance with the embodiment described and illustrated in figures 1 to 3, will now be described. This method may require loosening bolts (not shown) that hold the hatch 4 to the attachment flange 40. Next, the crane can lift the hatch 4 by its lifting ring 51. Assuming that the hatch 4 and the second plug 20 are fixed to each other, removing the hatch 4 makes it possible to remove the second plug 20, thus freeing the passage formed by the second conduit 12. This thus makes it possible to access the interior of the tank from outside the tank. Thus, small equipment, unloading pumps, or maintenance operations performed by a person may be passed through.

To close the second duct 12 again, the hatch 4 and the second plug 20 are put back into their initial positions by using a crane and the bolts are retightened in order to keep the hatch 4 fastened to the connection flange 40.

If it is desired to pass larger equipment, for example to replace the components of the primary or secondary sealing membrane constituting the interior of the tank, the method may comprise a step of separating the sealing membrane 8 in order to separate it from the glued panel of the insulating self-supporting panel 13 of the first stopper 10. This step consists in cutting a portion 61 of the sealing membrane 8 at the cutting line 60 and in separating this portion 61 with respect to the free end of the second conduit 12 leading to the internal volume of the tank.

After or before this step, the bolts (not shown) holding the lid 11 of the closing means 3 on the supporting flange 30 are unscrewed. The crane can then lift the cover 11 by removing the ring 41. Assuming that the cap 11 and the first stopper 10 are fixed to each other, removing the cap 11 makes it possible to remove the first stopper 10 and, consequently, the entire closure device. The first duct 2 of the wall 1 is therefore completely free and enables the introduction or extraction of the bulky component constituting the sealing membrane 8.

When the operation performed inside the tank is completed, the closing means 3 are put back into the first conduit 2, the cover 11 resting on the supporting flange 30, in order to close the first conduit 2 again. Bolts are used to lock the cover 11 to the support flange 30. Next, the portion 61 of the sealing membrane 8 is re-welded to the rest of the sealing membrane 8. Alternatively, a closure panel forming a repaired portion similar to portion 61 of sealing membrane 8 may be used. In an embodiment not shown, the closure panel may consist of a plurality of pre-assembled components, or of components which are assembled once the can is introduced.

Finally, the hatch 4 with the second plug 20 is positioned on the connecting flange 40 and fastened thereto by means of bolts.

The walls forming the subject of the invention are in no way limited by the shape, dimensions and position described. It goes without saying that the wall can be, for example, a lateral tank wall or a transverse tank wall.

Of course, the present invention is not limited to the examples just described, and various modifications may be made to these examples without departing from the scope of the present invention.

Claims

1. Wall (1) of a tank for storing and/or transporting liquefied gas, comprising a conduit (2) passing through the wall (1) in a thickness direction (E) of the wall (1), a closing device (3) configured to close the conduit (2), the closing device (3) comprising at least one hatch (4) configured to open into the interior of the tank, the conduit (2) comprising a first mouth (5) configured to open into the external environment of the tank and a second mouth (6) configured to open into the interior of the tank, the closing device (3) comprising a cover (11) closing the first mouth (5), the cover (11) having an aperture (17) opening into the interior of the tank, and the hatch (4) being configured to close the aperture (17).

2. Wall (1) according to claim 1, wherein the cover (11) and the hatch (4) each extend in a separate plane.

3. Wall (1) according to claim 1 or 2, wherein said duct (2) is a first duct and said closing means (3) comprise a first plug (10) extending at least partially in the thickness of said wall (1) and adjacent to the internal face of said first duct (2), and a second plug (20) extending at least partially in the thickness of said wall (1) and inside said first duct (2), said first plug (10) and said second plug (20) being separated by a second duct (12).

4. Wall (1) according to claim 3, wherein at least a portion of said second plug (20) has a shape complementary to the internal face of said second conduit (12).

5. Wall (1) according to claim 3 or 4, wherein said second plug (20) and said hatch (4) are fixed to each other.

6. The wall (1) according to any one of claims 3 to 5, wherein the second plug (20) comprises a thermally insulating material (25) extending in the second conduit (12) for a length measured in the thickness direction (E) of the wall (1) at most equal to the length of the second conduit measured in the thickness direction (E) of the wall (1).

7. Wall (1) according to any one of claims 3 to 6, wherein at least a portion of the first stopper (10) has a shape complementary to the internal face of the conduit (2).

8. Wall (1) according to any of the claims from 3 to 7, wherein said first plug (10) and said cover (11) are fixed to each other.

9. The wall (1) according to any one of claims 3 to 8, wherein said first plug (10) comprises at least one thermally insulating self-supporting panel (13) arranged around said second duct (12).

10. Wall (1) according to any one of claims 3 to 9, wherein said cover (11) and said second duct (12) are firmly connected to each other.

11. The wall (1) according to any of claims 3 to 10, wherein the second conduit (12) passes through the cover (11) via a hole (17) in the cover (11).

12. Wall (1) according to any one of claims 3 to 11, wherein an upper portion of the second conduit (12) projects from the cover (11) towards the outside of the tank in a thickness direction (E) of the wall (1).

13. Wall (1) according to any one of the preceding claims, wherein the wall (1) comprises, in the thickness direction, at least one thermal insulating barrier (7) and at least one sealing membrane (8), the sealing membrane (8) being intended to come into contact with the liquefied gas present inside the tank, the sealing membrane (8) facing at least partially the duct (2) in the thickness direction (E) of the wall (1).

14. Tank for storing and/or transporting liquefied gas, comprising at least one wall (1) according to any of the preceding claims.

15. Method for accessing the interior of a tank for storing and/or transporting liquefied gas, said tank comprising at least one wall (1) according to any one of claims 3 to 12 in combination with claim 13, comprising the steps of removing the second stopper (20) in order to access the interior of the tank, cutting a portion of a sealing membrane (8) around the closure means (3) and removing the closure means (3).