MX2011003688A

MX2011003688A - Vessel with a reinforced corrugated membrane.

Info

Publication number: MX2011003688A
Application number: MX2011003688A
Authority: MX
Inventors: Mokrane Yataghene; Bruno Deletre; Gery Canler
Original assignee: Gaztransp Et Technigaz
Priority date: 2008-10-08
Filing date: 2009-06-30
Publication date: 2011-05-02
Also published as: JP2012144298A; AU2009301016B2; CN102588732A; KR20120031313A; JP5379258B2; KR20160027222A; MY154077A; MY174853A; ES2821391T3; JP5379234B2; EP2453159A3; KR20220003163A; RU2012107912A; CN102588733A; EP2453159B1; JP2012505125A; EP2455650B1; ES2767975T3; RU2505737C2; EP2337984A1

Abstract

The invention relates to a sealed and thermally insulated vessel having at least one wall including a sealed membrane to be in contact with the product contained in the vessel, and a thermally insulating layer adjacent to said membrane, wherein the membrane includes at least one plate (1) having at least one corrugation (2, 3), characterised in that the vessel includes a reinforcing member (5) inserted under the corrugation between the membrane and the thermally insulating layer.

Description

STORAGE TANK WITH REINFORCED ONDULATED MEMBRANE Field of the Invention The present invention relates to a hermetic storage tank. In particular, the present invention relates to a hermetically sealed and thermally insulated storage tank, intended for the transport of liquefied natural gas (LNG) by ship.

Background of the Invention Document FR 2 781 557 describes a storage tank integrated in the structure of a ship, which allows the transport of LNG. The walls of the storage tank successively comprise, from the inside of the storage tank towards the outside, a primary hermetic barrier, a thermally insulating primary barrier, a secondary hermetic barrier and a secondary thermally insulating barrier. The primary hermetic barrier is a membrane made of corrugated metal plates, made of stainless steel. More precisely, each plate has a series of waves parallel to the axis of the ship and another series of waves perpendicular to the axis of the ship.

In operation, mechanical stresses are generated in the membrane. These voltages have several sources: the thermal retraction at the time of storage tank cooling, the effect of the ship's beam, the REF.219158 hydrostatic pressure due to the load, as well as the dynamic pressure due to the movement of the load, especially due to the swell.

The waves provided on the metal plates of the membrane are intended to allow the membrane to deform to limit the restrictions engendered by thermal retraction and the effect of the beam of the ship.

It has been found that dynamic pressure could cause plastic deformations of the probes. Or, at the time of use, such deformations can lead to degrading the flexibility of the plates and damaging the membrane tightness, especially at the level of the joints between the plates.

In order to increase the pressure resistance of the membrane and limit the plastic deformations, FR 2861 060 proposes to provide reinforcing ribs on the waves.

However, it may be interesting to still increase the pressure resistance of the membrane.

Brief Description of the Invention A problem that the present invention proposes to solve is that of providing a storage tank that presents only at least certain of the drawbacks mentioned in the prior art. In particular, an object of the invention is to improve the resistance of the pressure of the membrane, to avoid or limit plastic deformations.

The solution proposed by the invention is a hermetic storage tank, in which at least one wall comprises a hermetic membrane intended to be in contact with the product contained in the storage tank and a support adjacent to the membrane, in which the The membrane comprises at least one plate having at least one wave, characterized in that it comprises a reinforcing element inserted over the wave between the membrane and the support.

It has been found that one of such reinforcing elements makes it possible to limit the stresses generated in the membrane. Of course, the membrane may comprise several plates, the plate may have several waves, and a reinforcement element may be equipped under one or several waves of one or more plates. The support can be for example a thermally insulating layer, and more precisely a plywood panel of a thermally insulating layer.

According to one embodiment, the reinforcing element has an internal passage that allows the gas to circulate between the wave and the support through the reinforcement element.

According to one embodiment, an external passage allows the gas to circulate between the wave and the support surrounding the reinforcing element.

Advantageously, the reinforcement element is made of a material chosen from: the backing, the polyethylene, the polycarbonate, the polycarbonate reinforced with glass fibers, the polyether imide and the expanded polystyrene.

According to one embodiment, the reinforcing element comprises an outer envelope whose shape corresponds substantially to the shape of the wave.

Preferably, the reinforcing element comprises at least one reinforcing layer inside the envelope.

Selling, in the absence of the product contained in the storage tank, the minimum distance between the reinforcing element and the wave is between 0% and 5% of the height of the wave.

Preferably, the plate has a first series of parallel waves between them, and a second series of waves parallel to each other and transverse to the waves of the first series, the reinforcement element is inserted under a wave of the first series. Of course, several reinforcement elements can be inserted under several waves of the first series.

According to one embodiment, the reinforcing element has a length corresponding to the distance between the two waves of the second series. In a variant, this length may be smaller or larger.

Advantageously, the reinforcing element is inserted under the wave in a sliding manner with respect to the membrane and the support. In this case, the manufacture of the storage tank does not need the step of fixing the reinforcing element.

In a variant, the reinforcing element is fixed to the membrane or the support. This makes it possible to ensure that the reinforcement element remains positioned in the cantilevered position.

According to one embodiment, the membrane has a counter-layer, the reinforcement element is press-fitted to, or imprisoned in, the undercut.

In one embodiment, at least two reinforcing elements are respectively fitted under the two adjacent waves of the membrane, one of the two elements forming a stop for the other of the two reinforcing elements. Thus, one reinforcing element remains imprisoned by the other and thus is held in place.

Advantageously, the reinforcing element has at least one reduced point capable of being deformed or broken if it is subjected to a tension greater than a predetermined threshold.

This allows to know, by the controlled plastic deformations of the membrane, the pressures suffered by the membrane and to identify the possible risks of damage to the underlying support.

Preferably, at a distance from the wave, the membrane is in contact with the support.

The invention also provides a floating construction comprising a storage tank according to the invention mentioned above. It can be a ship or another type of floating installation.

Brief Description of the Figures The invention will be better understood, and other objects, characteristic details and advantages thereof will appear more clearly in the course of the following description of a particular embodiment of the invention, given only in illustrative and non-limiting quality, with reference to the annexed figures. In the figures: Figure 1 is a perspective view of a corrugated plate of a storage tank according to an embodiment of the invention, Figure 2 is a perspective and sectional view of a wave of the corrugated plate of Figure 1, and of a reinforcement element according to a first variant, Figure 3, Figure 4, Figure 5, Figure 6, Figure 7, Figure 8, and Figure 9 represent, in perspective, different variants of the reinforcement element, and Figure 10 and Figure 11, represent in section, other variants of the reinforcement element, Figure 12 shows a top view of the plate of figure 1, at the level of a crossing of the waves, as well as a perspective view and in partial section of a reinforcement element fixed by simple encastration under a wave, Figure 13 represents a reinforcement element intended to be equipped simultaneously under several waves, and Figure 14 represents, in an exploded perspective, two reinforcing elements cooperating therebetween.

Detailed description of the invention A storage tank according to one embodiment of the invention can have a multi-layer structure in a similar way to the storage tanks of the documents FR 2 781 557 and FR 2 861 060 mentioned in the introduction. In particular, the storage tank has a primary sealed membrane made with corrugated metal plates resting on a plywood panel of a thermally insulating primary layer. Aspects of this multi-layer structure are already known, the characteristics of the storage tank according to one embodiment of the invention are described below.

The plate 1 shown on FIG. 1 is a corrugated plate made of stainless steel, generally rectangular in shape. The primary hermetic membrane of the storage tank is made by welding edge to edge several of the plates of this type.

As shown in Figure 1, the plate 1 comprises three large waves 2 that extend over the length of the plate 1, and nine of the small waves 3 extend over the width of the plate 1. There is talk of large waves 2 and of small waves 3 because the height of the large waves 2 is greater than that of the small waves 3.

In a variant, the plate 1 could have a different number of large waves 2 and / or small waves 3. Also in a variant, the waves of the plate 1 could present reinforcing ribs as described in FR 2 861 060. waves of the plate 1 could also present other configurations, for example, as in documents FR 2 735 847 or KR-10-2005-0050170.

In figure 2, it is observed that the plate 1 rests on the counter plate 4 of the underlying thermally insulating layer. In a variant, plate 1 could rest on another type of support. It is also observed on this figure that a reinforcing element 5 is equipped under the large wave 2, between the plate 1 and the counter plate 4. In the frame of the present invention, "under" means that the reinforcing element 5 is covered by the wave, but does not necessarily mean that it is lower. Indeed, on the vertical walls of the storage tank, the reinforcement element 5 is located in the horizontal of the wave that covers it.

In the example of figure 2, the length of the reinforcing element 5 corresponds to the distance between the two small waves 3.

Several reinforcing elements 5 can be equipped, each under a large wave 2 between two small sheets 3. The number and distribution of the reinforcing elements 5 can be determined as a function of the distribution of the stresses expected in the operation in the membrane of the storage tank.

In a variant, the length of the reinforcement element 5 can be less than the distance between the two small waves 3 or, if the geometry of the crossing between the waves allows it, greater than this distance. Also in a variant, the reinforcing elements 5 can be provided under the small waves 3.

The reinforcement element 5 is put into place as shown on FIG. 2, without being fixed to the plate 1 or the backing plate 4. It can also be slid in this way under the large wave 2. The production of the storage tank is not Thus, it is necessary to fix the reinforcing elements 5. In a variant, the reinforcing element 5 can be fixed to the membrane or the backing plate 4.

Numerous shapes may be suitable for the reinforcing element 5. Figures 3 to 11 represent different shapes that may be convenient. The views of figures 3 to 9 are perspective views of a section of the reinforcement element 5, whose length can be larger than that shown. The views of Figures 10 and 11 are sectional views. On these different figures, the same reference signs are used to designate similar elements.

The reinforcement element 5 of figure 3 presents a flat section. Its two lateral faces 6 are curved and corresponding to that of the wave 2. However, the lateral faces 6 do not extend more than up to the crest of the wave 2 and the reinforcing element 5 has a flat upper face 7. The gas can circulate between the crest of wave 2 and the upper face 7.

The reinforcing element 5 of FIG. 4 has a casing 8 whose external shape corresponds to the shape of the wave 2. A circular passage 9 allows the gas to pass through the reinforcement element 5. In the variant of FIG. 5, the passage 9 has a shape corresponding to the outer shape of the envelope 8, so as to offer a larger passage surface.

The reinforcing element 5 of FIG. 6 also has a casing 8 whose outer shape corresponds to the shape of the wave 2 and a passage 9. To improve the mechanical strength of the reinforcement element 5, the inner layers 10 pass through the passage 9. Figures 7 to 9 represent alternative configurations of the layers 10.

The reinforcement elements of FIGS. 3 to 9 can be made, for example, from one of the following materials: polyethylene, polycarbonate, polycarbonate reinforced with glass fiber, polyether imide, and expanded polystyrene. They can be manufactured by another appropriate technique (injection, molding, extrusion, machining, ...).

The reinforcing elements 5 of figures 10 and 11 have a flat section. The side faces 6 each have two flat bands. As for the reinforcing element of Figure 3, the gas can pass between the front surface 7 and the crest of the wave. The reinforcing elements 5 of figures 10 and 11 can be made, for example, plywood, by machining.

The reinforcement element 5 of FIG. 11 has a tongue 22 fixed to its lower face 23. The tongue 23 makes it possible to fix the reinforcement element 5 to the backing plate 4, for example at the level of function between the two plates of the backing sheet.

Figure 12 shows, on the left side, the geometry of the waves at the level of a junction between a large wave 2 and a small wave 3. It can be seen that the membrane presents at this level one against despula 20. The right part of Figure 12 shows that the reinforcement element 5 fitted under the large wave 2 has, at the level of its end, the legs 21 that allow the reinforcement element 5 to be fixed to the membrane, by simple recessing at the level of the backstop 20. In a variant, the legs 21 could be imprisoned.

Figure 13 represents in perspective a reinforcing element 5 that is intended to be equipped simultaneously under several large waves 2 and small waves 3. Its shape corresponds to those of the waves, and comprises at the same level crosses. The internal passages 9 are provided both in the parts located under the small waves 3 and under the large waves 2.

Figure 14 shows two reinforcement elements 5, one which is intended to be equipped under a large wave 2 and the other under a small wave 3, crossing at the level of the wave junction. At this level, the reinforcement elements 5 each having a layer 24 allow them to be placed one with respect to the others. As in the view on this figure, the reinforcing elements 5 have a rectangular section.

The different shapes of the reinforcing elements 5 proposed above allow the waves to deform in the case of thermal contraction, and offer a support for the waves in the case of deformation due to the hydrostatic and dynamic pressures. To achieve this effect, it can be foreseen that, when the storage tank is empty (in the case of the absence of the thermal load and of the hydrostatic or dynamic pressure) the minimum distance between the reinforcement element 5 and the wave under the which is either comprised between 0% and 5% of the height of the wave.

The different shapes of the reinforcement element 5 each have particular properties: cost and ease of manufacture, mechanical strength, quantity of material, ... Depending on the applications, the most appropriate form can be chosen.

Numerical simulations have been carried out to verify the effect of a reinforcement element 5 on the stresses generated in the membrane, by comparison with a membrane without the reinforcement element. These simulations have shown that: - in the case of the thermal load (contraction of the membrane due to cold), the presence of a reinforcing element 5 does not introduce undesirable tensions in the membrane, - in the case of the thermal load and the uniform pressure load (which corresponds to the hydrostatic pressure of the load), the presence of a reinforcing element 5 reduces the stresses in the membrane, and - in the case of a thermal load and an asymmetric pressure load (which corresponds to the dynamic pressure of the load) the presence of a reinforcing element 5 makes it possible to reduce the restrictions on the membrane.

Although the invention has been described in relation to a particular embodiment, it is very evident that it is never limited and that it comprises all the technical equivalents of the described means as well as their combinations, if they fall within the scope of the invention.

It is noted that in relation to this date the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. An airtight storage tank, wherein at least one wall comprises a sealed membrane intended to be in contact with a product contained in the storage tank and a support adjacent to the membrane, wherein the membrane comprises at least one plate that presents at least one wave, characterized in that it comprises a reinforcing element inserted under the wave, between the membrane and the support.

2. The storage tank according to claim 1, characterized in that the reinforcing element has an internal passage that allows the gas to circulate between the wave and the support through the reinforcing element.

3. The storage tank according to one of the preceding claims, characterized in that an external passage allows the gas to circulate between the wave and the support in the contour of the reinforcing element.

4. The storage tank according to one of the preceding claims, characterized in that the reinforcement element is made of a material selected from: a backing, polyethylene, polycarbonate, polycarbonate reinforced with glass fiber, polyether imide and expanded polystyrene.

5. The storage tank according to one of the preceding claims, characterized in that the reinforcement element comprises an external envelope whose shape corresponds substantially to the shape of the wave.

6. The storage tank according to claim 5, characterized in that the reinforcing element comprises at least one reinforcing layer inside the envelope.

7. The storage tank according to any of the preceding claims, characterized in that in the absence of the product contained in the storage tank, the minimum distance between the reinforcing element and the wave is comprised between 0 and 5% of the height of the wave

8. The storage tank according to any of the preceding claims, characterized in that the plate has a first series of waves parallel to each other, and a second series of waves parallel to each other transverse to the waves of the first series, the reinforcement element is inserted under a wave of the first series.

9. The storage tank according to claim 8, characterized in that the reinforcing element has a length corresponding to the distance between the two waves of the second series.

10. The storage tank according to any of the preceding claims, characterized in that the reinforcing element is inserted under the wave in a sliding manner with respect to the membrane and the support.

11. The storage tank according to one of claims 1 to 9, characterized in that the reinforcing element is fixed to the membrane or to the support.

12. The storage tank according to claim 11, characterized in that the membrane has a counter-layer, the reinforcement element is encased to, or is clamped in, the counter-layer.

13. The storage tank according to any of the preceding claims, characterized in that at least two reinforcing elements are equipped respectively under two adjacent waves of the membrane, one of the two reinforcing elements forms a stop for the other of the two elements of reinforcement. reinforcement.

14. The storage tank according to any of the preceding claims, characterized in that the reinforcing element has at least one weak point capable of being deformed or broken if it is subjected to a voltage greater than a certain threshold.

15. The storage tank according to any of the preceding claims, characterized in that at the distance of the wave, the membrane is in contact with the support.

16. A floating construction, characterized in that it comprises a storage tank according to any of the preceding claims.