FR3073270A1 - SEALED AND THERMALLY INSULATING TANK WITH DEVICES FOR ANCHORING PRIMARY INSULATION PANELS ON SECONDARY INSULATING PANELS - Google Patents

Abstract

The invention relates to a sealed and thermally insulating vessel embedded in a vessel, each of the vessel walls comprising a secondary thermally insulating barrier, a secondary sealing membrane, a primary thermally insulating barrier and a primary sealing membrane; primary insulating panels of each ballast area wall (9, 11, 12, 13, 14) being anchored to secondary insulating panels of said ballast area wall (9, 11, 12, 13, 14) by means of first anchoring devices; primary insulating panels of each non-ballast wall (8, 10, 15, 16) being anchored to secondary insulating panels of said non-ballast wall (8, 10, 15, 16) by means of second devices anchor; wherein the first anchoring devices are each equipped with n1 resilient members; and wherein the second anchoring devices are each equipped with n2 elastic members providing elastic anchoring are arranged to provide rigid anchoring of the primary insulating panels on the secondary insulating panels, n2 being an integer greater than or equal to 0, the stiffness K2 of the second anchoring devices being less than the stiffness K1 of the first anchoring devices.

Description

Technical area

The invention relates to the field of tanks, sealed and thermally insulating, with membranes, for the storage and / or transport of a fluid, such as a cryogenic fluid.

Sealed and thermally insulating tanks with membranes are used in particular for the storage of liquefied natural gas (LNG).

Technological background

Application WO2014 / 170588 discloses a sealed and thermally insulating tank for the storage of liquefied natural gas, which is integrated in the double hull of a ship. Each tank wall has a multilayer structure and successively has, in the thickness direction, from the outside towards the inside of the tank, a secondary thermally insulating barrier retained at a support structure, a secondary sealing membrane resting against the secondary thermally insulating barrier, a primary thermally insulating barrier resting against the secondary sealing membrane and a primary sealing membrane intended to be in contact with natural gas! liquefied contained in the tank and resting against the primary thermally insulating barrier.

In the aforementioned document, the thermally insulating barrier comprises a plurality of primary insulating panels which are anchored on secondary insulating panels of the secondary thermally insulating barrier, by means of anchoring devices. All the anchoring devices are fitted with a stack of elastic washers which allows elastic anchoring of the primary insulating panels to the secondary insulating panels. Such an elastic anchoring makes it possible to hold the primary insulating panels against the secondary insulating panels while allowing slight relative displacements of the primary insulating panels relative to the secondary insulating panels. This makes it possible to limit the stresses likely to be exerted on the primary insulating panels and on the secondary insulating panels in the anchoring zones. However, such a sealed tank is not entirely satisfactory. In particular, such anchoring devices require a large number of stacking Belleville washers, which increases the cost of the tank equipped with such anchoring devices as well as the complexity of its manufacture.

summary

One idea underlying the invention consists in proposing a sealed and thermally insulating tank in which the anchoring of the insulating panels is carried out in a simpler and more economical manner.

According to one embodiment, the invention provides a sealed and thermally insulating tank on board a ship, the ship comprising a double hull comprising an internal hull which forms a support structure for the sealed and thermally insulating tank and an external hull; the double hull having, in ballast zones, ballast compartments which are intended to receive a liquid, such as sea water, and which are delimited between the internal hull and the external hull; the tank comprising tank walls which are retained at the internal shell; each of the tank walls successively comprising in a thickness direction of the tank wall at least one thermally insulating barrier which comprises insulating panels retained on the internal shell and a sealing membrane which rests against the insulating panels;

said tank walls including ballast zone walls which are retained at the inner shell in line with at least one of the ballast compartments in a thickness direction of said ballast zone wall and walls outside of ballast zone which are retained in the internal shell at the right of none of the ballast compartments in the thickness direction of said wall outside the ballast zone;

at least one of the insulating panels of the walls of the ballast area being anchored directly or indirectly to the internal shell by means of first anchoring devices;

at least one of the insulating panels of the walls outside the ballast area being anchored directly or indirectly to the internal shell by means of second anchoring devices;

in which the first anchoring devices are each equipped with n1 elastic members arranged to exert an elastic force pressing said insulating wall panel of ballast areas in the direction of the internal shell while allowing relative movement, in the thickness direction of the tank wall, of said insulating panel with respect to the supporting structure during the deformation of the internal shell; n1 being an integer greater than or equal to 1; said first anchoring device having a stiffness K1 opposing the relative displacement of said insulating panel relative to the support structure in the thickness direction of the tank wall; and in which the second anchoring devices are each fitted with n2 elastic members which are arranged to exert an elastic force pressing said insulating wall panel outside the ballast area towards the internal shell while allowing relative movement of said insulating panel relative to the supporting structure during the deformation of the internal shell; n2 is an integer greater than or equal to 0; said second anchoring devices having a stiffness K2 opposing the relative displacement of said insulating panel relative to the support structure in the thickness direction of the tank wall; the stiffness K2 being greater than K1.

It has in fact been observed that the main forces liable to generate stresses on the anchoring zones of the insulating panels come from the deformation of the internal shell in the ballast zones, when seawater is loaded in the compartments. of ballast. In fact, due to the movements of seawater inside the ballast compartments, the internal shell is deformed. This results in deformations of the insulating panels, which have the effect of generating significant forces on the anchoring zones of said insulating panels. On the contrary, in the walls outside the ballast area, the second anchoring devices are mainly subjected to the only forces due to the phenomena of thermal contraction. However, these forces are much lower than those likely to be exerted by the deformation of the internal shell in the walls of the ballast area so that the stiffness K2 of the second anchoring devices can be greater.

According to other advantageous embodiments, such a tank may have one or more of the following characteristics.

According to one embodiment, n2 is less than n1. In this case, the elastic members of the first anchoring devices and those of the second anchoring devices can be identical.

According to another embodiment, n2 is equal to n1. In this case, the elastic members of the first anchoring devices and those of the second anchoring devices are necessarily different, the stiffness of the elastic members of the first anchoring devices being lower than that of the second anchoring devices.

According to one embodiment, at least one of the insulating panels of each ballast zone wall is anchored by means of first anchoring devices.

According to one embodiment, each of the tank walls successively comprises, from the outside towards the inside of the tank, a secondary thermally insulating barrier which comprises secondary insulating panels retained at the internal shell, a secondary sealing membrane which rests against the secondary insulating panels, a primary thermally insulating barrier which comprises a plurality of primary insulating panels resting against the secondary sealing membrane and a primary sealing membrane which rests against the primary insulating panels and which is intended to be in contact with the liquefied natural gas contained in the tank.

According to one embodiment, the first anchoring devices anchor at least one of the primary insulating panels of the ballast area walls on at least one of the secondary insulating panels of said ballast area wall; and the second anchoring devices anchor at least one of the primary insulating panels of the non-ballast area walls on at least one of the secondary insulating panels of said non-ballast area wall.

In such a case, the forces liable to generate stresses on the anchoring zones of the primary insulating panels are all the more important since the primary insulating panels are arranged astride several secondary insulating panels. Also, a more elastic anchoring of at least one of the primary insulating panels on at least one of the secondary insulating panels proves advantageous in the ballast zones since a more rigid anchoring of the primary insulating panels in these zones would involve reinforcement. mechanical of these, difficult and expensive to achieve.

According to one embodiment, a majority, or even all of the primary insulating panels of each ballast zone wall is anchored on the secondary insulating panels of said ballast zone wall by means of first anchoring devices.

According to one embodiment, at least one of the primary insulating panels of each wall outside the ballast area is anchored on at least one of the secondary insulating panels of said wall outside the ballast area by means of second devices. anchorage.

According to one embodiment, a majority, or even all of the primary insulating panels of each wall outside the ballast area is anchored on the secondary insulating panels of said wall outside the ballast area by means of second anchoring devices.

According to one embodiment, the first anchoring devices anchor at least one of the secondary insulating panels of the ballast zone walls on the internal shell; and the second anchoring devices anchor at least one of the secondary insulating panels of the out-of-ballast walls on the internal shell.

According to one embodiment, a majority, or even all of the secondary insulating panels of each wall of the ballast area is anchored by means of first anchoring devices.

According to one embodiment, a majority, or even all of the primary insulating panels of each wall outside the ballast area is anchored by means of second anchoring devices.

According to one embodiment, the first anchoring devices anchor at least one of the primary insulating panels of the ballast zone walls on the internal shell and the second anchoring devices anchor at least one of the primary insulating panels of the walls outside the ballast area on the internal hull.

According to one embodiment, the first and second anchoring devices each comprise a stud which is anchored directly or indirectly to the internal shell and a retaining member which is mounted on the stud; said retaining member being retained on the stud and cooperating with a bearing surface of said insulating panel anchored by said first or second anchoring device so as to retain it towards the internal shell.

According to one embodiment, each stud is anchored on one of the secondary insulating panels.

According to one embodiment, the stud is anchored on an internal face of said secondary insulating panel, that is to say on one face of the secondary insulating panel opposite the secondary sealing membrane.

According to one embodiment, the stud has a thread cooperating with a nut which retains the retaining member towards the internal shell.

According to one embodiment, each elastic member is an elastic washer, such as a Belleville washer, which is engaged on the stud, between the nut and the retaining member, so as to ensure an elastic force pressing the member retaining against the bearing surface.

According to one embodiment, the first anchoring devices comprise a spacer sleeve which is threaded onto the respective stud and retained towards the internal shell by the nut, said spacer sleeve comprising a cylindrical portion which is fitted inside the washers elastic so as to center them and an annular flange which presses said elastic washers against the retaining member.

According to one embodiment, each second anchoring device comprises a spacer sleeve which is threaded onto the respective stud and retained towards the support structure by the nut and the spacer sleeve comprises a flange bearing against the retaining member.

According to one embodiment, the second anchoring devices are devoid of elastic members and are thus arranged to ensure a rigid anchoring.

According to one embodiment, the spacer sleeve of one of the first anchoring devices and the spacer sleeve of one of the second anchoring devices are identical, the flange of said spacer sleeves being offset from the center of the spacer sleeve so as to define a cylindrical centering portion having a length greater than half a length of the spacer sleeve, the spacer sleeve of said first anchoring device and the spacer sleeve of said second anchoring device having an inverted orientation so that the cylindrical centering portion of the first anchoring device passes through the n1 elastic washers of said first anchoring device and its cylindrical centering portion of the second anchoring device is disposed between the flange and the nut.

According to one embodiment, the collar is arranged at one end of the spacer sleeve.

According to one embodiment, the spacer sleeve of one of the first anchoring devices and the spacer sleeve of one of the second anchoring devices are identical, the flange of said spacer sleeves being offset from the center of the spacer sleeve and delimiting two cylindrical portions of different lengths, the cylindrical portion having the longest length of the spacer sleeve of the first anchoring device passing through the elastic washers of said first anchoring device while the cylindrical portion having the shortest length of the spacer sleeve of the second anchoring device passes through a bore of the retaining member.

According to one embodiment, each primary insulating panel comprises an external rigid plate and a layer of insulating polymeric foam which is fixed to the external rigid plate, the layer of insulating polymeric foam having a recess which extends in the thickness of the layer of insulating polymer foam which protects the support surface on the rigid external plate.

According to one embodiment, the external rigid plate extends beyond the layer of insulating polymeric foam at the edge of each primary insulating panel so as to provide at the edge of each primary insulating panel support surfaces which each cooperate with a retaining member of one of the first and second anchoring devices.

According to one embodiment, each primary insulating panel is placed astride at least four secondary insulating panels.

According to one embodiment, the equivalent stiffness of the elastic members of each first anchoring device is less than the equivalent stiffness of the elastic members of each second anchoring device.

According to one embodiment, said tank walls further include mixed walls which have a part to the right of none of the ballast compartments and a part to the right of at least one of the ballast compartments; and at least one of the insulating panels of the mixed walls is anchored directly or indirectly to the internal shell by means of second anchoring devices.

According to one embodiment, the tank has a generally polyhedral shape and has an upper wall, a lower wall, transverse front and rear walls extending transversely to the longitudinal direction of the vessel and side walls, the upper wall, the wall lower and the side walls extending, in the longitudinal direction of the ship and connecting the front and rear transverse walls; the front transverse wall, the rear transverse wall and the upper wall each being one of the walls outside the ballast area.

According to one embodiment, the tank comprises at least four side walls, two of said side walls being vertical side walls and two of said side walls being upper oblique side walls which each connect the upper wall to one of said vertical side walls.

According to one embodiment, said two upper oblique side walls each being one of the mixed walls. The inner shell at the upper oblique side walls is less stressed by the ballast than in the ballast walls. On the one hand, the upper oblique side walls are only partially in contact with ballast compartments. On the other hand, the hydrostatic pressure in the ballast compartments in line with said upper oblique side walls is more limited. Therefore, the upper oblique side walls can be provided with second anchoring devices such as the walls outside the ballast area.

According to one embodiment, the other tank walls, that is to say its lower wall, the vertical side walls and the lower oblique walls, are walls of ballast zones.

Such a tank can be part of a terrestrial storage installation, for example to store LNG or be installed in a floating structure, coastal or deep water, in particular an LNG tanker, a floating storage and regasification unit (FSRU) , a floating remote production and storage unit (FPSO) and others.

According to one embodiment, a vessel for transporting a fluid comprises a double hull and aforementioned tank arranged in the double hull, the double hull having an internal hull forming the carrying structure of the tank.

According to one embodiment, the invention also provides a method of loading or unloading such a ship, in which a fluid is conveyed through insulated pipes from or to a floating or land storage installation to or from the tank of the ship.

According to one embodiment, the invention also provides a transfer system for a fluid, the system comprising the aforementioned ship, isolated pipes arranged so as to connect the tank installed in its hull of the ship to a floating or land storage installation. and a pump for driving a fluid through the insulated pipes from or to the floating or land storage facility to or from the vessel of the ship.

Brief description of the figures

The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given solely by way of illustration and without limitation. , with reference to the accompanying drawings.

- Figure 1 is a cutaway perspective view of the double hull of a ship and a sealed and thermally insulating tank attached to the interior of said double hull.

- Figure 2 is a perspective view, in section, of the double hull of a ship and illustrating ballast compartments inside which seawater is received in order to stabilize the ship.

- Figure 3 is a perspective view, cut away, of a tank wall.

- Figure 4 is a partial schematic view of a sealed and thermally insulating storage tank which illustrates the ballast areas and the non-ballast areas.

- Figure 5 is a schematic view of an anchoring device for anchoring the primary insulating panels of the ballast area walls according to a first embodiment.

- Figure 6 is a detailed view of the spacer sleeve of the anchoring device of Figure 5.

- Figure 7 is a schematic view of an anchoring device for anchoring the primary insulating panels of the ballast area walls according to a second embodiment.

- Figure 8 is a schematic view of an anchoring device for anchoring the primary insulating panels of the walls outside the ballast area according to a first embodiment.

- Figure 9 is a schematic view of an anchoring device for anchoring its primary insulating panels of the walls outside the ballast area according to a second embodiment.

- Figure 10 is a schematic cutaway view of an LNG tank vessel having walls as shown in Figure 3 and a loading / unloading terminal of this tank.

- Figure 11 is a perspective view, cut away, of a wall of a tank according to another embodiment.

- Figure 12 is a schematic view of an anchoring device for anchoring the primary and secondary insulating panels of the ballast area walls according to a third embodiment.

- Figure 13 is a schematic view of an anchoring device for anchoring the primary and secondary insulating panels of the walls outside the ballast area according to a third embodiment.

Detailed description of embodiments

By convention, the terms "external" and "internal" are used to define the relative position of one element with respect to another, by reference to the interior and exterior of the tank.

In relation to Figures 1 and 2, we observe the double hull 1 of a ship. The double shell 1 comprises an external shell 2 and an internal shell 3 which forms the support structure for a sealed and thermally insulating tank 4 with membranes. The internal shell 3 has a plurality of walls defining the general shape of the tank 4, usually a polyhedral shape. The internal shell 3 and the external shell 2 are connected to each other by a plurality of metal sheets 5.

As illustrated in FIG. 2, the double shell 1 has, in its lower part, ballast zones 6 in which ballast compartments 7 are provided. The ballast compartments 7 are formed between the internal shell 3 and the external shell 2 of the double shell 1. The ballast compartments 7 are intended to receive a liquid, te! as sea water. These ballast compartments 7 are notably loaded with sea water, when the vessel (s) are (are) little filled, in order to ensure the stability of the vessel.

In FIG. 4, the general polyhedral shape of a tank 4 according to one embodiment is observed. The tank 4 has a plurality of walls 8, 9, 10, 11, 12, 13, 14, 15, 16 which are each arranged against a respective wall of the internal shell 3. The tank 4 has a top wall 8 and a wall lower 9 horizontal as well as two transverse walls, front and rear 10, horizontal. In Figure 4, the front transverse wall is not shown. The two transverse walls 10 each extend in a plane which is perpendicular to the longitudinal direction of the ship. The tank 4 also has lateral walls 11, 12, 13, 14, 15, 16. The upper walls 8, lower 9, and lateral walls 11, 12, 13, 14, 15, 16 extend in the longitudinal direction of the vessel and connect the front and rear transverse walls 10, to one another. In the embodiment shown, the transverse walls 10 are of octagonal shape. Also, the side walls include two vertical side walls 13, 14, two upper oblique side walls 15, 16 which each connect one of the vertical side walls 13, 14 to the upper wall 8 and two lower oblique side walls 11, 12 which each connect one of the vertical side walls 13, 14 to the bottom wall 9.

The vessel walls 8, 9, 10, 11, 12, 13, 14, include ballast zone walls which are retained at the inner shell 3 in the ballast zones 6 of the double shell 1, i.e. -to say to the right of the ballast compartments 7, walls outside the ballast area which are retained in the internal hull 3 outside the ballast areas 6 of the double hull 1, that is to say to the right of none of the ballast compartments 7 and mixed walls 15, 16 of which only a part is retained in the internal shell to the right of the ballast compartments 7. In FIG. 4, the walls of the ballast area are hatched while the walls outside of the ballast area are blank and the mixed walls have +. In other words, the bottom wall 9, the vertical side walls 13, 14 as well as the lower oblique side walls 11, 12 are ballast zone walls while the top wall 8, the front and rear transverse walls 10 are walls outside the ballast area. The upper oblique side walls 15, 16 are mixed walls. The walls of ballast zones are liable to undergo greater stresses than the walls outside of ballast zone, due to the deformations of the internal shell 3 in the ballast zones 6, when seawater is loaded in the compartments. of ballast 7.

In Figure 3, there is shown the multilayer structure of each of the walls of a tank according to one embodiment. Each wall successively comprises, in the thickness direction, from the outside towards the inside of the tank, a secondary thermally insulating barrier 17 retained at the internal shell 3, a secondary sealing membrane 18 resting against the thermally barrier secondary insulating 17, a primary thermally insulating barrier 19 resting against the secondary sealing membrane 18 and a primary sealing membrane 20 intended to be in contact with the liquefied natural gas contained in the tank.

The secondary thermally insulating barrier 17 comprises a plurality of secondary insulating panels 21 anchored to the internal shell 3 by means of resin cords, not shown, and / or studs, not shown, welded to the internal shell 3. The secondary insulating panels 21 have substantially the shape of a rectangular parallelepiped and are juxtaposed in parallel rows and separated from each other by interstices 22 ensuring a functional mounting clearance. The interstices 22 are filled with a heat-insulating lining such as glass wool, rock wool or flexible synthetic foam with open cells for example. The secondary insulating panels 21 each comprise a layer of insulating polymer foam 24 sandwiched between an internal rigid plate 25 and an external rigid plate 26. The rigid plates, internal 25 and external 26, are, for example, plywood plates bonded to said layer of insulating polymer foam 24. The insulating polymer foam can in particular be a polyurethane-based foam.

The secondary sealing membrane 18 comprises a plurality of corrugated metal sheets each having a substantially rectangular shape. The corrugated metal sheets are arranged offset from the secondary insulating panels 21 of the secondary thermally insulating barrier 17 so that each of said corrugated metal sheets extends jointly over four adjacent secondary insulating panels 21. The corrugations project outwards from the tank 4, that is to say towards the internal shell 3. The corrugations of the corrugated metal sheets are housed in grooves formed in the internal rigid plate 25 of the secondary insulating panels 21.

The adjacent corrugated metal sheets are welded together. In addition, the corrugated metal sheets are welded to metal plates 23 which are fixed on the internal rigid plate 25 of secondary insulating panels 21. The corrugated metal sheets have cutouts along their longitudinal edges and at their four corners allowing the passage of studs 27 which are fixed on the internal rigid plates 25 of the secondary insulating panels 21 and which are intended to ensure the fixing of the primary thermally insulating barrier 19 on the secondary thermally insulating barrier 17.

Furthermore, the primary thermally insulating barrier 19 comprises a plurality of primary insulating panels 28 of substantially rectangular rectangular shape. In the embodiment shown, the primary insulating panels 28 are offset with respect to the secondary insulating panels 21 of the secondary thermally insulating barrier 17 so that each primary insulating panel 28 extends over four secondary insulating panels 21.

Each primary insulating panel 28 has a layer of insulating polymer foam 29, for example based on polyurethane, which is sandwiched between two rigid plates, namely an external rigid plate 30 and an internal rigid plate 31. The rigid plates, external 30 and internal 31, are for example made of plywood.

The internal rigid plate 31 of each primary insulating panel 28 is equipped with metal plates 32 for anchoring the corrugated metal sheets of the primary sealing membrane 20. The primary sealing membrane 20 is obtained by assembling a plurality of corrugated metal sheets. The corrugated metal sheets each have a substantially rectangular shape. The corrugations protrude towards the inside of the tank.

In the embodiment shown, each primary insulating panel 28 has one or more recesses 33 along each of its two longitudinal edges and a recess 34 at each of its corners. Each recess 33, 34 crosses the internal rigid plate 31 and extends over the entire thickness of the layer of insulating polymer foam 29. At each of the recesses 33, 34, the external rigid plate 30 projects beyond the layer of insulating polymer foam 29 and to the internal rigid plate 31 so as to form a support zone cooperating with an anchoring device. Each recess 33 formed along an edge of one of the primary insulating panels 28 is disposed opposite a recess 33 formed in the edge opposite an adjacent primary insulating panel 28. Thus, a single anchoring device can cooperate with two support surfaces belonging respectively to one and to the other of the two adjacent primary insulating panels 28. In addition, each recess 34 formed at one of the corners of the primary insulating panels 28 opens opposite the recesses 34 formed at the adjacent corners of the three adjacent primary insulating panels 28. The four recesses 34 thus together form a cross-shaped housing. Consequently, a single anchoring device can cooperate with the four bearing surfaces of the four adjacent primary insulating panels 28.

In another embodiment not shown, the recesses are not formed at the edges of the primary insulating panels 28. In this case, the recesses are each formed by a chimney, for example cylindrical, which passes through the internal rigid plate 30 and the layer of insulating polymer foam 29. The external rigid plate 30 which constitutes the bottom of the recess is then fitted with an orifice intended for the passage of a stud 27 and is intended to form a bearing surface cooperating with a device anchor.

FIG. 5 illustrates in detail a first anchoring device 35 which anchors the primary insulating panels 28 on the secondary insulating panels 21, in the walls of the ballast area.

Each first anchoring device 35 comprises a stud 27 which is fixed to the internal rigid plate 25 of one of the secondary insulating panels 21.

In the embodiment shown, an anchor plate 36 is received in a housing formed in the internal rigid plate 25. In addition, the internal rigid plate 36 has a flange 37 which covers a portion of the anchor plate 36 of so as to retain the anchoring plate 6 against the layer of insulating polymeric foam 24. However, the anchoring plate 36 can be fixed to the internal surface of the secondary insulating panels 21 by any other means, for example by gluing.

Furthermore, the stud 27 passes through an orifice formed in the secondary sealing membrane 18, for example at the level of cutouts formed in the edges of two adjacent metal sheets of the secondary sealing membrane 18.

The stud 27 has a threaded end which cooperates with a threaded bore formed in the anchoring plate 36, so as to secure the said stud 27 to the primary insulating panel 28. The stud 27 has a shoulder 38 which bears in the direction of the internal shell 3 against the secondary sealing membrane 18 at the edge of said orifice. The secondary sealing membrane 18 is also welded sealingly to the anchoring plate around said stud 17 so as to ensure the continuity of the sealing.

Each first anchoring device 35 further comprises a retaining member 39 fixed on the stud 27. To do this, the retaining member 39 has a bore threaded on the stud 27. The retaining member 39 has lugs 40 which are each housed inside one of the recesses 34. Thus, at the corners of the primary insulating panels 28, the retaining member 39 has an x shape comprising four tabs 40 which are each housed at the inside a recess 34 of one of the four adjacent primary insulating panels 28. In the embodiment shown, the retaining member 39 is bent so that the central region of the retaining member 39 having the bore through which the stud 27 passes is not in the same plane as the legs 40.

Each tab 40 of the retaining member 39 comes to bear against one of the bearing surfaces 41, that is to say a portion of the external rigid plate 30 projecting with respect to the internal rigid plate 31 and at the layer of insulating polymer foam 29, so that each bearing surface 41 is sandwiched between one of the tabs 40 of the retaining member 39 and the secondary sealing membrane 18.

A nut 42 cooperates with a thread of the stud 27 so as to fix the retaining member 39 to the stud 27. The nut 42 is associated with a tightening washer 43, also mounted on the stud 27. In addition , the first anchoring device 35 comprises n1 elastic washers 44, such as Belleville washers, which are threaded on the stud 27, between the nut 42 and the retaining member 39, which ensures elastic anchoring primary insulating panels 28 on the secondary insulating panels 21. n1 is an integer greater than or equal to 1.

Furthermore, the first anchoring device 35 also includes an optional spacer sleeve 45, illustrated in detail in FIG. 6, which makes it possible in particular to ensure relative centering of the elastic washers 44. To do this, the spacer sleeve 45 is threaded on the stud 27 between the elastic washers 44 and the tightening washer 43. The spacer sleeve 45 has two cylindrical portions 46, 47 arranged on either side of a flange 48. The flange 48 is not centered in the middle of the spacer sleeve 45 so that said flange 48 defines two cylindrical portions 46, 47 of different length. The two cylindrical portions 46, 47 each have an external diameter which is, on the one hand, less than the internal diameter of the elastic washers 44 and, on the other hand, less than the diameter of the bore of the retaining member 39 at through which the stud 27 passes. The external diameter of the cylindrical portions 46, 47 is however greater than the internal diameter of the clamping washer 43. Furthermore, the flange 48 has an external diameter which is greater than the internal diameter of the elastic washers 44. Thus, as shown in FIG. 5, the cylindrical portion 47 of the spacer sleeve 45 is inserted inside the elastic washers 44 so as to ensure their centering. In addition, the nut 42 bears against the cylindrical portion 46 of the spacer sleeve 45 via the clamping washer 43 and the elastic washers 44 are thus compressed between the flange 48 and the retaining member 39.

FIG. 7 illustrates in detail a first anchoring device 49 which anchors the primary insulating panels 28 on the secondary insulating panels 21, in the walls of the ballast zone, according to a second embodiment. In this embodiment, the recess 51 is not provided at the edge of a primary insulating panel 28 and consists of a chimney passing through the internal rigid plate 31 and the layer of insulating polymer foam 29 of the insulating panel. primary 28. In this embodiment, the stud 27 of the anchoring device 49 passes through an orifice formed in the external rigid plate 30. The first anchoring device 49, illustrated in FIG. 7, does not differ from the anchoring device 35 described in relation to FIGS. 5 and 6 only by the shape of the retaining member 50. In fact, in this embodiment, the retaining member 50 is a washer which is threaded on the stud 27 and which is sandwiched between the elastic washers 44 and a support zone 41 of the internal rigid plate 30 of the primary insulating panel 28.

FIG. 8 illustrates in detail a second anchoring device 52 which anchors the primary insulating panels 28 on the secondary insulating panels 21, in the walls outside the ballast area, according to a first embodiment. The second anchoring device 52 differs from the first anchoring device 35 described in relation to FIGS. 5 and 6 only in that it is devoid of elastic washers 44 acting between the nut 42 and the retaining member 39. Consequently, the flange 48 of the spacer sleeve 45 is directly in abutment against the retaining member 39.

Thus, the second anchoring device 52 provides rigid anchoring of the primary insulating panels 28 on the secondary insulating panels 21. In the walls outside the ballast area, the second anchoring devices 52 are mainly subjected to the forces due to the phenomena of contraction. thermal. When the tank 4 is cooled, that is to say when liquefied natural gas is loaded in the tank 4, the primary 28 and secondary 21 insulating panels as well as the studs 27 are subjected to the phenomenon of thermal contraction . It should be noted that the amplitude of the relative movement of the legs of the retaining member 39 relative to the bearing surface 41 of the primary insulating panels 28 which would be likely to occur due to the phenomenon of thermal contraction if the second anchoring devices ensured an elastic anchoring is extremely weak. Indeed, this amplitude depends only on the difference in contraction in the direction of thickness of the tank, between, on the one hand, the portion of the stud 27 extending between the anchoring plate 37 and the member of retainer 39 and, on the other hand, the external rigid plate 40. The length of the stud portion 27 concerned as well as the thickness of the external rigid plate 40 being relatively small, the amplitude of the relative displacement due to the phenomenon of contraction thermal is of the order of a hundredth of a mm and can therefore be neglected. Thus, the presence of elastic washers is therefore not necessary to compensate for this contraction differential. A slight deformation of the external rigid plate 30 by the retaining member 39 during the installation of the anchoring device 52 proving sufficient to continue to ensure maintenance of the primary insulating panel 28 even after cooling.

FIG. 9 illustrates in detail a second anchoring device 53 which anchors the primary insulating panels 28 on the secondary insulating panels 21, in the walls outside the ballast area, according to a second embodiment. The second anchoring device 53 here aims to be disposed at a recess 53, as described in relation to FIG. 7. The second anchoring device 53 differs from the first anchoring device 49, illustrated in the figure 7, in that it does not have elastic washers. Consequently, the collar 48 of the spacer sleeve 45 is directly in abutment against the retaining member 50.

It is further observed that a spacer sleeve 45 identical to that disclosed in Figure 6 is used in this embodiment. However, the orientation of said spacer sleeve 45 is reversed with respect to its orientation in FIGS. 5 and 7. In fact, by providing a spacer sleeve 45 whose flange 48 is not centered longitudinally, the spacer sleeve 45 is reversible and can optionally be used by orienting the cylindrical portion 47 having the greatest length towards the secondary thermally insulating barrier 17 when the anchoring device is equipped with elastic washers 44 (as illustrated in FIGS. 5 and 6) or, on the contrary by orienting the cylindrical portion 46 had the shortest length towards the secondary thermally insulating barrier 17 when the anchoring device is devoid of elastic washers and when the flange 48 of the spacer sleeve 45 is directly in contact against the retaining member 39 ( as illustrated in His figure 9). Thus, this standard spacer sleeve 45 can be used whether or not the anchoring device is provided with elastic washers.

Otherwise; advantageously, insulating plugs, not illustrated; are positioned in its recesses 33, 34, 51 after the mounting of the anchoring devices 35, 49, 52, 53 so as to ensure its continuity with the primary thermally insulating barrier 19 at the level of said recesses 33, 34, 51.

In another embodiment, the second anchoring device 53 is also likely to include elastic washers. However, in all cases, the stiffness K1 of the first anchoring devices opposing the relative displacement of the respective insulating panel in the thickness direction of the tank wall is strictly less than the corresponding stiffness K2 of the second devices of anchorage.

According to one embodiment, the second anchoring device comprises n2 elastic washers with n2 an integer less than n1. Thus, the two anchoring devices are capable of using identical elastic washers, which facilitates the manufacture of the tank.

According to other embodiments, the elastic washers of the second anchoring device and those of the first anchoring device are different. In this case, the numbers n2 and n1 can also be equal.

The primary insulating panels 28 of the mixed walls, that is to say of the oblique upper side walls 15, 16 are also capable of being anchored by means of second anchoring devices, according to one of the variants described above. .

In Figure 12, there is shown the multilayer structure of a wall of a tank according to another embodiment.

The secondary thermally insulating barrier 17 comprises a plurality of juxtaposed secondary insulating panels 21. Each secondary insulating panel 21 consists of a parallelepiped box, for example of plywood, which comprises a bottom plate 54, a cover plate 55 and partitions 56 which extend in the thickness direction of the wall between the bottom plate 54 and the cover plate 55 and which defining compartments filled with an insulating lining, such as perlite for example. The bottom plates 54 project laterally on two opposite sides of the box so that in each corner of the box on this projecting part are cleats 57.

The primary thermally insulating barrier 19 also includes a plurality of juxtaposed primary insulating panels 28. The primary insulating panels 28 have a structure substantially similar to that of the secondary insulating panels 21. The primary insulating panels 28 have dimensions identical to those of the secondary insulating panels 21 except for their thickness according to the thickness direction of the tank. which is likely to be weaker than that of the secondary insulating panels 21. The bottom plates 58 of the primary insulating panels 28 project laterally on two opposite sides of the box so that in each corner of the box on this projecting part are fixed battens 59.

The secondary sealing membrane 18 comprises a continuous sheet of metal strakes with raised edges. The strakes are welded by their raised edges on parallel welding supports which are fixed in grooves made on the cover plates 55 of the secondary insulating panels 21. The primary sealing membrane 20 has a similar structure and has a continuous web of metal strakes with raised edges. The strakes are welded by their raised edges to parallel weld supports which are fixed in grooves formed on the cover plates of the primary insulating panels 28.

The metallic strakes are, for example, made of Invar®: that is to say an alloy of iron and nickel whose coefficient of expansion is typically between 1.2.10 ^-6 and 2.10 ^-6 K ^-1 .

FIG. 12 illustrates a first anchoring device 60 for anchoring the primary 28 and secondary 21 insulating panels of the walls of ballast zones. The first anchoring device 60 comprises a socket 61 which is fixed to the internal shell 3 at four corners of four adjacent primary insulating panels 21. Each douiile 61 houses a nut 62 into which the lower end of a stud 63 is screwed. The first anchoring device 60 further comprises a retaining member 64 fixed to the stud 63. To do this, the member retaining 64 has a bore which is threaded on the stud 63. The retaining member 64 is for example a metal plate. The retaining member 64 bears against the cleats 57 so as to retain the secondary insulating panels 21 against the internal shell 3. A nut 65 cooperates with a thread of the stud 63 so as to secure the retaining member 64 on the stud 63. Furthermore, the first anchoring device 60 comprises a set of n1 elastic washers 66 with n1 an integer greater than or equal to 1. The elastic washers 66 are for example Belleville washers. The elastic washers 66 are threaded onto the stud 63 between the nut 65 and the retaining member 64, which ensures elastic anchoring of the secondary insulating panels 21 on the internal shell 3.

In the embodiment shown, the nut 65 has a cylindrical centering portion 67 which is inserted inside the elastic washers 66 so as to ensure their centering. In addition, in the embodiment shown, a locking washer 68 is locally welded to the stud 63, above the nut 65, so as to fix the nut 65 on the stud 63 in position.

Furthermore, the first anchoring device 60 comprises a plate 69 which is fixed to the retaining member 64. A spacer element 82, for example, made of wood is disposed between the retaining member 64 and the plate 69 The spacer element 82 has a thickness such that the plate 69 is flush with the cover panel 55 of the secondary insulating panels 21. The spacer element 82 comprises a central housing intended to receive the upper end of the stud 63, the nut 65, the locking washer 68 and the elastic washers 66. The spacer element 82 also includes bores intended to be crossed by screws 83 which make it possible to secure the plate 69 to the retaining member 64.

Furthermore, the plate 69 has a central threaded bore which receives the threaded base of a stud 84. The stud 84 passes through a bore provided through a strake in the secondary sealing membrane 18. The stud 84 has a flange 85 which is welded at its periphery, around the bore, to seal the secondary sealing membrane 18. The stud 84 has a threaded upper end on which is aimed a nut 87 to ensure the tightening of a retaining member 86 against the battens 59 of the primary insulating panels 28. The first anchoring device 60 also comprises at least one or more elastic washers 88, such as Belleville washers, which are threaded on the stud 84 between the nut 87 and the retaining member 86 and which thus ensure elastic anchoring of the primary insulating panels 28 relative to the plate 69.

FIG. 13 illustrates a second anchoring device 89 for anchoring the primary 28 and secondary 21 insulating panels of the walls outside the ballast area. The second anchoring device 89 differs from the first anchoring device 60, illustrated in FIG. 13, in that it comprises a number n2 of elastic washers 66 between the nut 65 and the retaining member 64.

In this embodiment, the elastic washers 66, 88 of the second anchoring device 89 are identical to those of the first anchoring device 60.

Also, the number n2 of elastic washers 66 is an integer which is on the one hand greater than or equal to 0, and on the other hand less than n1 so that the stiffness K1 of the first anchoring device 60 is less than the stiffness K2 of the second anchoring device 60. Thus, the number of elastic washers 66, 88 necessary for the construction of the tank can be limited.

In other embodiments, as explained above, the elastic washers of the second anchoring device and those of the first anchoring device are different. In this case, the numbers n2 and n1 can also be equal as long as the stiffness the stiffness K1 of the first anchoring device 60 is less than the stiffness K2 of the second anchoring device 60.

Furthermore, the upper oblique side walls 15, 16 of a tank having such a multilayer structure are also capable of being anchored by means of second anchoring devices 89, according to one of the variants described above.

With reference to FIG. 10, a cutaway view of an LNG tanker 70 shows a sealed and insulated tank 71 of generally prismatic shape mounted in the double hull 72 of the ship. The wall of the tank 71 comprises a primary sealing membrane intended to be in contact with the LNG contained in the tank, a secondary sealing membrane arranged between the primary sealing membrane and the double hull 72 of the ship, and two thermally insulating barriers arranged respectively between the primary waterproofing membrane and the secondary waterproofing membrane and between the secondary waterproofing membrane and the double shell 72.

In a manner known per se, loading / unloading lines 73 arranged on the upper deck of the ship can be connected, by means of appropriate connectors, to a maritime or port terminal for transferring a cargo of LNG from or to the tank 71.

FIG. 10 shows an example of a maritime terminal comprising a loading and unloading station 75, an underwater pipe 76 and a shore installation 77. The loading and unloading station 75 is a fixed offshore installation comprising an arm mobile 74 and a tower 78 which supports the mobile arm 74. The mobile arm 74 carries a bundle of insulated flexible pipes 79 which can be connected to the loading / unloading pipes 73. The mobile arm 74 can be adjusted to suit all LNG tankers' sizes . A connection pipe, not shown, extends inside the tower 78. The loading and unloading station 75 allows the loading and unloading of the LNG carrier 70 from or to the onshore installation 77. This comprises liquefied gas storage tanks 80 and connecting pipes 81 connected by the subsea pipe 76 to the loading or unloading station 75. The subsea pipe 76 allows the transfer of the liquefied gas between the loading or unloading station 75 and the shore installation 77 over a long distance, for example 5 km, which makes it possible to keep the LNG carrier 70 at a great distance from the coast during the loading and unloading operations.

To generate the pressure necessary for the transfer of the liquefied gas, pumps on board the ship 70 and / or pumps fitted to the shore installation 77 and / or pumps fitted to the loading and unloading station 75 are used.

Although the invention has been described in connection with several particular embodiments, it is obvious that it is in no way limited thereto and that it includes all the technical equivalents of the means described as well as their combinations if these are within the scope of the invention.

The use of the verb "behave", "understand" or "include" and its conjugate forms do not exclude the presence of other elements or steps than those set out in a claim.

In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims (18)

1. Watertight and thermally insulating tank (4) on board a ship, the ship comprising a double hull (1) comprising an internal hull (3) which forms a support structure for the watertight and thermally insulating tank (4) and an external hull (2); the double hull (1) having, in ballast areas (6), ballast compartments (7) which are intended to receive a liquid, such as sea water, and which are delimited between the internal hull ( 3) and the outer shell (2); the tank (4) comprising tank walls (8, 9, 10, 11, 12, 13, 14, 15, 16) which are retained at the internal shell (3); each of the tank walls successively comprising in a thickness direction of the tank wall at least one thermally insulating barrier (17, 19) which comprises insulating panels (21, 28) retained in the internal shell and a sealing membrane (18, 20) which rests against the insulating panels (21, 28); said tank walls including ballast zone walls (9, 11, 12, 13, 14) which are retained at its internal shell (3) in line with at least one of the ballast compartments (7) in a direction d thickness of said ballast zone wall and walls outside of ballast zone (8, 10) which are retained at the internal shell (3) in line with none of the ballast compartments in the thickness direction of said wall outside ballast area; at least one of the insulating panels (28) of the ballast zone walls (9, 11, 12, 13, 14) being anchored directly or indirectly to the internal shell (3) by means of first anchoring devices (35 , 49); at least one of the insulating panels (28) of the non-ballast zone walls (8, 10, 15, 16) being anchored directly or indirectly to the internal shell (3) by means of second anchoring devices (52, 53, 89); in which the first anchoring devices (35, 49, 60) are each equipped with n1 elastic members (44, 66, 88) arranged to exert an elastic force pressing said insulating panel (28) of the wall of ballast zones in the direction of the internal shell (3) while allowing relative displacement, in the thickness direction of the tank wall, of said insulating panel (28) relative to the support structure during the deformation of the internal shell (3); n1 being an integer greater than or equal to 1; said first anchoring device having a stiffness K1 opposing the relative movement of said insulating panel (28) relative to the support structure (3) in the thickness direction of the tank wall; and in which the second anchoring devices (52, 53, 89) are each equipped with n2 elastic members (44, 66, 88) which are arranged to exert an elastic force pressing said insulating panel (28) out of area wall ballast in the direction of the inner shell (3) while allowing relative movement of said insulating panel (28) relative to the support structure during the deformation of the inner shell (3); n2 is an integer greater than or equal to 0; said second anchoring devices having a stiffness K2 opposing the relative movement of said insulating panel (28) relative to the support structure (3) in the thickness direction of the tank wall; the stiffness K2 being greater than K1. 2. Watertight and thermally insulating tank (4) according to claim 1, in which n2 is less than n1. 3. Watertight and thermally insulating tank (4) according to claim 1 or 2, in which each of the tank walls successively comprises, from the outside towards the inside of the tank, a secondary thermally insulating barrier (17) which comprises secondary insulating panels (21) retained at the inner shell, a secondary sealing membrane (18) which rests against the secondary insulating panels (21), a primary thermally insulating barrier (19) which comprises a plurality of primary insulating panels (28 ) resting against the secondary sealing membrane (18) and a primary sealing membrane (20) which rests against the primary insulating panels (28) and which is intended to be in contact with the liquefied natural gas contained in the tank ( 4). 4. Watertight and thermally insulating tank (4) according to claim 3, in which the first anchoring devices (35, 49) anchor at least one of the primary insulating panels of the walls of the ballast zone (9, 11, 12 , 13, 14) on at least one of the secondary insulating panels (21) of said ballast zone wall (9, 11, 12, 13, 14); and in which the second anchoring devices anchor at least one of the primary insulating panels (28) of the non-ballast zone walls (8, 10, 15, 16) on at least one of the secondary insulating panels (21 ) of said out-of-ballast wall (8, 10, 15, 16). 5. Watertight and thermally insulating tank (4) according to claim 3, in which the first anchoring devices (60) anchor at least one of the secondary insulating panels of the walls of the ballast area (9, 11, 12, 13 , 14) on the internal shell (3); and in which the second anchoring devices (89) anchor at least one of the secondary insulating panels of the walls outside the ballast zone (8, 10, 15, 16) on the internal shell (3). 6. Watertight and thermally insulating tank (4) according to claim 3 or 5, in which the first anchoring devices (60) anchor at least one of the primary insulating panels of the walls of the ballast zone (9, 11, 12 , 13, 14) on the internal shell (3); and in which the second anchoring devices (89) anchor at least one of the primary insulating panels of the non-ballast zone walls (8, 10, 15, 16) on the internal shell (3). 7. Watertight and thermally insulating tank (4) according to any one of claims 1 to 6, in which the first and second anchoring devices (35, 49, 52, 53, 60, 89) each comprise a stud (27 , 63, 84) which is anchored directly or indirectly to the internal shell (3) and a retaining member (39, 50, 64, 86) which is mounted on the stud (27, 63, 84); said retaining member (39, 50, 65, 86) being retained on the stud (27, 63, 84) and cooperating with a bearing surface (41, 57, 59) of said insulating panel (28) anchored by said first or second anchoring device so as to retain it towards the internal shell (3). 8. Watertight and thermally insulating tank (4) according to claim 7, in which the stud (27, 63, 84) has a thread cooperating with a nut (42, 65, 87) which retains the retaining member (39, 50, 64, 86) towards the internal shell (3) . 9. Watertight and thermally insulating tank (4) according to claim 8, in which each elastic member is an elastic washer (44, 66, 88) which is engaged on the stud (27, 63, 84), between the nut (42, 65, 87) and the retaining member ( 39, 50, 64, 86), so as to ensure an elastic force pressing the retaining member against the bearing surface (41,47, 59). 10. Watertight and thermally insulating tank (4) according to claim 9, in which the first anchoring devices (35, 49) comprise a spacer sleeve (45) which is threaded onto the respective stud (27) and retained towards the internal shell (3) by the nut (42), said spacer sleeve (45) comprising a cylindrical centering portion (47) which is fitted inside the n1 elastic washers (44) so as to center them and an annular collar (48) which presses the n1 elastic washers (44) against the retaining member (39, 50). 11. Tight and thermally insulating tank (4) according to any one of claims 7 to 10, in which n2 is equal to 0 and in which each second anchoring device (52, 53) comprises a spacer sleeve (45) which is threaded onto the respective stud (27) and is retained towards the secondary thermally insulating barrier (17) by the nut (42) and in which the spacer sleeve (45) includes a flange (48) bearing against the member restraint (39, 50). 12. Watertight and thermally insulating tank (4) according to claims 10 and 11 taken in combination, in which the spacer sleeve (45) of one of the first anchoring devices (35, 49) and the spacer sleeve (45) of one of the second anchoring devices (52, 53) are identical, the flange (48) of said spacer sleeves being offset relative to the middle of the spacer sleeve (45) so as to define a cylindrical centering portion having a length greater than half the length of the spacer sleeve, the spacer sleeve of said first anchoring device and the spacer sleeve of said second anchoring device having an inverted orientation such that the cylindrical centering portion (47) of centering of the first anchoring device anchoring (35, 49) passes through the n1 elastic washers (44) of said first anchoring device (35, 49) and that the cylindrical centering portion (47) of the second anchoring device age (52, 53) is disposed between the flange (48) and the nut (42). 13. Watertight and thermally insulating tank (4) according to any one of claims 1 to 12, in which said tank walls also include mixed walls (15, 16) which have a part in line with none of the compartments of ballast and a part to the right of at least one of the ballast compartments; and in which at least one of the insulating panels of the mixed walls (15, 16) is anchored directly or indirectly to the internal shell by means of second anchoring devices (52, 53, 89). 14. Watertight and thermally insulating tank (4) according to any one of claims 1 to 13, in which the tank (4) has a generally polyhedral shape and comprises an upper wall (8), a lower wall (9), front and rear transverse walls (10) extending transversely to the longitudinal direction of the ship and of the side walls (11, 12, 13, 14, 15, 16), the upper wall (8), the lower wall (9) and the side walls extending (11, 12, 13, 14, 15, 16), in the longitudinal direction of the ship and connecting the front and rear transverse walls (10) and in which the front transverse wall, the rear transverse wall ( 10) and the upper wall (8) are each one of the walls outside the ballast area. 15. Watertight and thermally insulating tank (4) according to claim 14 taken in combination with claim 13, wherein the tank (4) has at least four side walls (11, 12, 13, 14, 15, 16), two of said side walls being vertical side walls (13, 14) and two of said side walls being upper oblique side walls (15, 16) which each connect the upper wall (8) to one of said vertical side walls (13, 14); said two upper oblique side walls (15, 16) each being one of the mixed walls. 16. Vessel (70) for transporting a fluid, the vessel comprising a double hull (72) and a tank (71) according to any one of claims 1 to 15 disposed in the hull. 17. A method of loading or unloading a ship (70) according to claim 15, in which a fluid is conveyed through insulated pipes (73, 79, 76, 81) from or to a floating or terrestrial storage installation ( 77) to or from the vessel (71). 18. Transfer system for a fluid, the system comprising a ship (70) according to claim 16, insulated pipes (73, 79, 76, 81) arranged so as to connect the tank (71) installed in the hull of the ship to a floating or terrestrial storage installation (77) and a pump for driving a fluid through the insulated pipes from or to the floating or terrestrial storage installation to or from the vessel of the vessel.