US-12624797-B2 - Method for assembling and installing a liquefied gas storage tank

US12624797B2US 12624797 B2US12624797 B2US 12624797B2US-12624797-B2

Abstract

A method for assembling and installing a liquefied gas storage tank, wherein the liquefied gas storage installation includes a load-bearing structure and a sealed and thermally insulated tank arranged in the load-bearing structure, in which so-called adjacent members of a sealing membrane of a cofferdam wall of a main structure of the tank protrude partially into a liquid dome, the so-called adjacent membranes directly sealably fastened to so-called adjacent membranes of the liquid dome.

Inventors

Paul Baron
Jocelyn DESBRUGERES
Cédric FELGUEIRAS

Assignees

GAZTRANSPORT ET TECHNIGAZ

Dates

Publication Date: 20260512
Application Date: 20211001
Priority Date: 20201002

Claims (14)

1 . A liquefied gas storage installation comprising: a load-bearing structure; and a sealed and thermally insulating tank arranged in the load-bearing structure, the sealed and thermally insulating tank including a main structure made up of a plurality of tank walls connected to each other and fastened to the load-bearing structure, the main structure defining an internal storage space, the main structure comprising at least one sealing membrane and at least one thermally insulating barrier, the thermally insulating barrier being placed between the sealing membrane and the load-bearing structure; the sealing membrane, the thermally insulating barrier of the main structure and a so-called upper load-bearing wall being locally interrupted so as to define a duct forming a load-bearing wall of a chimney extending along a vertical axis to an upper end consisting of a loading/unloading opening through which liquefied gas loading/unloading pipes can pass, said duct leading to said opening defining a liquid dome of the tank including the main structure of the tank, at least one sealing membrane and at least one thermally insulating barrier, the thermally insulating barrier being placed between the sealing membrane the load-bearing wall, the liquid dome being situated at one axial end of the tank, a vertical wall of the main structure of the tank, referred to as the cofferdam wall, extends from said main structure to form, along the same plane, a wall of the duct of the liquid dome; wherein the sealing membrane of the main structure and the sealing membrane of the liquid dome are made up of a plurality of flat metal membranes, sealably fastened together, each having at least two perpendicular rows of corrugations, the shape and dimensions of these two rows of corrugations being respectively identical for all of the membranes so that these juxtaposed membranes display a repeating pattern, wherein so-called adjacent membranes of the sealing membrane of the cofferdam wall of the main structure of the tank protrude at least partially into the liquid dome, said so-called adjacent membranes being directly sealably fastened to so-called adjacent membranes of the liquid dome.
2 . The storage installation according to claim 1 , in which the flat metal membranes forming the sealing membrane of the main structure and of the liquid dome have a rectangular shape with two long sides and two short sides.
3 . The storage installation according to claim 1 , in which the flat metal membranes include a raised portion extending along two adjacent sides suitable for overlapping the adjacent side of another membrane.
4 . The storage installation according to claim 1 , in which the thermally insulating barrier of the main structure and the thermally insulating barrier of the liquid dome of the tank include metal plates to which the sealing membrane of the main structure and the sealing membrane of the liquid dome are discontinuously welded.
5 . The storage installation according to claim 2 , in which the so-called adjacent membranes of the liquid dome include a raised portion extending along a lower long side while the so-called directly adjacent membranes of the main structure of the tank include a raised portion extending along one of the two short sides of the membrane.
6 . The storage installation according to claim 1 , in which a protruding part of the so-called adjacent membranes of the sealing membrane of the cofferdam wall of the main structure of the tank protrudes by at least 30 millimetres into the liquid dome.
7 . The storage installation according to claim 1 , in which a protruding part of the so-called adjacent membranes of the sealing membrane of the cofferdam wall of the main structure of the tank protrudes by at most 60 millimetres into the liquid dome.
8 . The storage installation according to claim 1 , in which the so-called adjacent membranes of the liquid dome have a length of between 500 millimetres and 3,300 millimetres and a width of between 200 millimetres and 800 millimetres.
9 . The storage installation according to claim 1 , in which the so-called adjacent membranes of the sealing membrane of the cofferdam wall of the main structure of the tank have a length of between 500 millimetres and 3,300 millimetres and a width of between 200 millimetres and 800 millimetres.
10 . The storage installation according to claim 9 , in which the so-called adjacent membranes of the sealing membrane of the cofferdam wall of the main structure of the tank are in two rows of parallel membranes, one row of membranes having a width of between 200 and 400 millimetres and the other row of membranes having a width of between 700 and 800 millimetres.
11 . A method for assembling a storage installation according to claim 1 , the method comprising: sealably assembling and fastening the sealing membrane assembly of the cofferdam wall of the main structure of the tank; sealably assembling and fastening the sealing membrane assembly of the liquid dome, with the exception of the adjacent membranes of said liquid dome, the first and second steps being performed in any order or simultaneously; and sealably assembling and fastening the so-called adjacent membranes of said liquid dome so that the assembly of the cofferdam wall, of the main structure and of the liquid dome, is sealed.
12 . A vessel for transporting a cold liquid product, the vessel including a double hull and a storage installation according to claim 1 arranged in the double hull.
13 . A system for transferring a cold liquid product, the system comprising: a vessel according to claim 12 ; insulated pipes arranged so that they connect the tank installed in the hull of the vessel to a floating or onshore external storage installation; and a pump for conveying a stream of cold liquid product through the insulated pipes from or to the floating or onshore external storage installation to or from the tank of the vessel.
14 . A method for loading or unloading a vessel according to claim 12 , in which a cold liquid product is conveyed through insulated pipes from or to a floating or onshore external storage installation to or from the tank of the vessel.

Description

The invention relates to the field of liquefied gas storage installations comprising a sealed and thermally insulated membrane tank. In particular, the invention relates to the field of sealed and thermally insulating tanks for storing and/or transporting liquefied gas at low temperatures, such as tanks for transporting liquefied petroleum gas (also called LPG) having for example a temperature of between −50° C. and 0° C., or for transporting liquefied natural gas (LNG) at approximately −162° C. at atmospheric pressure. These tanks can be installed on shore or on a floating structure. In the case of a floating structure, the tank can be for transporting liquefied gas or receiving liquefied gas used as a fuel to propel the floating structure. FR2991430 describes a liquefied gas storage installation comprising a sealed and thermally insulating tank incorporated into a load-bearing structure consisting of the double hull of a vessel. Each wall of the tank comprises a secondary thermally insulating barrier, a secondary sealing membrane, a primary thermally insulating barrier and a metal or metal alloy primary sealing membrane. The primary sealing membrane conventionally comprises corrugations suitable for permitting thermal contractions, without failure of the membrane, these corrugations conventionally forming a network of small and large corrugations extending parallel to each other respectively so as to form a grid delimited by node zones, i.e. the generally perpendicular intersections of the small and large corrugations. In a zone situated at the top of the tank, the tank includes a chimney-shaped protruding portion. In this zone, the load-bearing structure is locally interrupted so as to define a loading/unloading opening through which fluid loading/unloading pipes can pass. This loading/unloading opening and this chimney-shaped duct, known as the liquid dome, include insulation or a thermally insulating barrier, together with an element forming a primary sealing membrane. As can be seen in the appended FIGS. 1 and 2, this liquid dome is conventionally situated at one longitudinal end of the tank so that one of the vertical walls of the liquid dome is continued or extended, in the same plane, by a vertical wall of the main structure of the tank (containing a cold fluid). When the tanks are present in a vessel for transporting cold fluid such as LNG or LPG, i.e. a liquid natural gas carrier (LNGC), this vertical wall common to the liquid dome and the main structure of the tank is known as a cofferdam wall. The tank is installed in a structure subject to very high mechanical stresses, such as a vessel, which bends and twists as a function of the conditions of its environment. As the load-bearing structure is interrupted at the liquid dome, these mechanical stresses are even more significant at that point. The walls of the main structure of the tank are mounted and assembled/fastened and the walls of the liquid dome are mounted and assembled/fastened separately, and these two parts of the storage installation are then sealably connected to each other. Due in particular to the sizes of the primary insulation membranes, the membranes are connected and the continuity of the corrugations is provided by a connecting sheet, generally with small dimensions, fastened by welding to the adjacent membranes of the liquid dome and of the main structure of the tank. This connecting sheet is not a satisfactory solution. Firstly, in order to ensure the continuity of the vertical corrugations between the liquid dome and the main structure of the tank, the operators are obliged to deform the connecting sheet in situ using striking tools, as the corrugations of the two parts—the liquid dome on the one hand and the main structure on the other—are not aligned. This operation is painstaking for the operators and typically requires several hours of work. Then, the shaping of this connecting sheet at its vertical corrugations weakens it. As mentioned above, this zone of a vessel is subject to high mechanical stresses. This is why it is unacceptable for a portion of the primary sealing membrane to be able to fail and compromise the sealing of the storage installation. After various experiments and tests, the applicant has observed that it is possible to dispense with this connecting part, or sheet portion, by proposing an assembly solution that is simpler and faster, while making it possible to make this connecting zone between the primary membranes of the main structure of the tank and those of the liquid dome more reliable in terms of both mechanical strength and sealing. The present invention thus relates to a liquefied gas storage installation comprising a load-bearing structure and a sealed and thermally insulating tank arranged in the load-bearing structure, the sealed and thermally insulating tank including a main structure made up of a plurality of tank walls connected to each other and fastened to the load-bearing structure,