Patent Grant
12038137
This application is the U.S. national stage application of International Patent Application No. PCT/EP2021/061023, filed Apr. 27, 2021, which claims the benefit under 35 U.S.C. § 119 of French Application No. 2004425, filed May 5, 2020, the disclosures of each of which are incorporated herein by reference in their entirety.
The invention relates to the field of tanks, sealed and thermally insulating, with membranes, for storing and/or transporting fluid, such as liquefied gas.
Sealed and thermally insulating tanks with membranes are used in particular for storing liquefied natural gas (LNG), which is stored, at atmospheric pressure, at approximately −162° C. These tanks can be installed on land or on a floating structure. In the case of a floating structure, the tank can be intended for transporting liquefied natural gas or for accommodating liquefied natural gas used as fuel for propelling the floating structure.
In the prior art, sealed and thermally insulating tanks for storing liquefied natural gas are known, built into a supporting structure, such as the double hull of a vessel intended for transporting liquefied natural gas. Such tanks generally include a multi-layer structure, having successively, in the direction of thickness, from the outside to the inside of the tank, a secondary thermal insulation barrier retained at the supporting structure, a secondary sealing membrane resting against the secondary thermal insulation barrier, a primary thermal insulation barrier resting against the secondary sealing membrane and a primary sealing membrane resting against the primary thermal insulation barrier and intended to be in contact with the liquefied natural gas contained in the tank.
The primary sealing membrane consists of corrugated metal plates. The metal plate, rectangular in shape, includes a first series of parallel corrugations, called low, extending along a direction y from one edge of the plate to the other and a second series of parallel corrugations, called high, extending along a direction x from one edge of the metal plate to the other. The directions x and y of the series of corrugations are perpendicular. The corrugations protrude on the side of an internal face of the metal plate, intended to be placed in contact with the fluid contained in the tank. The corrugated metal plates have flat portions between the corrugations.
The corrugations of the primary sealing membrane thus form circulation channels for a gas present in the primary thermally insulating barrier. Furthermore, one of the directions x or y is parallel to the direction of greater slope for an inclined wall.
As the primary sealing membrane is at very low temperatures and the secondary sealing membrane or the supporting structures at higher temperatures, it was found that a thermosiphon phenomenon was taking place in the inclined walls forming an angle with a horizontal direction, for example vertical walls of the tank, with circulation of a gas (or gas mixture) undergoing cooling, therefore descending with respect to the vertical direction, between the primary sealing membrane and the primary thermally insulating barrier (in the channels formed by the corrugations) and circulation of a gas undergoing heating, therefore rising with respect to the vertical direction, between the secondary sealing membrane and the secondary thermally insulating barrier or between the secondary thermally insulating barrier and the supporting wall. The circulation of gas undergoing cooling and the circulation of gas undergoing heating form a closed circuit at the ends of the wall of the tank, which assists the transfer of convective heat through the wall of the tank.
It was also found that a multitude of loops of the thermosiphon phenomenon were forming at the bottom tank wall between the different insulating panels.
This thermosiphon effect does not allow the thermally insulating barrier to fulfill its insulating role in an effective way and can therefore damage the outer structure of the tank by propagating the extreme temperatures of the tank contents to same.
The invention aims to remedy this problem.
An idea at the base of the invention is to propose a sealed and thermally insulating tank with sealing membrane including corrugations in which the phenomena of convection or thermosiphon are reduced. In particular, an idea at the base of the invention is to provide a sealed and thermally insulating tank limiting the presence of continuous circulation channels in the thermal insulation barriers so as to limit the phenomena of natural convection in said thermal insulation barriers.
According to an embodiment, the invention provides a sealed and thermally insulating tank for storing a liquefied gas, in which the tank includes a bottom wall, a ceiling wall and peripheral walls connecting the bottom wall to the ceiling wall so as to form a polyhedral tank, the peripheral walls including a sealing membrane intended to be in contact with the liquefied gas contained in the tank and at least one thermal insulation barrier arranged between the sealing membrane and a supporting wall of a supporting structure, the thermal insulation barrier including a plurality of juxtaposed insulating panels,
Thanks to these characteristics, the flow of gas situated in the circulation channels of the corrugations, which on cooling would be caused to descend in the peripheral walls, is blocked here from circulating by the filling elements with pressure loss disposed in the obstruction part of the belt of filling elements. This flow of gas is thus forced to pass through the discontinuation part or parts so as to pass through the belt of filling elements. The belt of filling elements therefore implements a singular pressure loss on this flow by suddenly reducing the passage section of the flow over the entire wall, inhibiting the thermosiphon effect from becoming established in the peripheral walls.
The expression “being inclusively disposed between two adjacent corrugations of the second series of corrugations” means that the filling elements of the obstruction part are situated in the direction x in a space formed by two adjacent corrugations of the second series of corrugations including the limits of the space. Each filling element of the obstruction part can therefore be situated at one of the corrugations of the second series of corrugations, the other corrugation of the second series of corrugations, or between these two corrugations.
According to embodiments, such a tank can include one or more of the following characteristics.
According to an embodiment, the filling elements are configured to generate a pressure loss reducing a gaseous flow passing through said circulation channel by at least 80%.
Thus, these filling elements with pressure loss therefore consist in plugs formed in the corrugations causing a pressure loss on an outflow such that the pressure loss P is greater than or equal to 80% of:
(ρ(Tf)−ρ(Tc))×g×h,
with Tc and Tf the temperatures of the hot and cold branches of the thermosiphon, ρ the density of the outflow, and h the largest dimension of the thermosiphon loop according to gravity. According to a possibility offered by the invention, the temperature of the hot branch is measured at the very top of the loop under the insulation barrier while the temperature of the cold branch is measured at the very bottom of the mouth in a circulation channel. In this case, it is the extreme temperatures of the hot branch and of the cold branch that are measured, but of course, it is possible to envisage a different measurement configuration for these two temperature measurements.
This pressure loss can be engendered by a particular geometry of the filling element, and/or a particular constituent material of the filling element, this material having a suitable coefficient of permeability.
According to an embodiment, the filling elements are made in a gas-proof material.
According to an embodiment, the filling elements of the obstruction part of the at least one belt of filling elements are aligned with each other along the direction y.
According to an embodiment, the direction y is perpendicular to the direction x.
According to an embodiment, the tank comprises a plurality of belts of filling elements spaced from each other by a pitch substantially equal to a dimension of the insulating panels in the direction x.
By multiplying the number of belts of filling elements over the height of the tank, it is therefore possible to increase the pressure loss the flow of gas encounters while descending through the circulation channels.
According to an embodiment, the at least one discontinuation part of a belt of filling elements is offset in the direction y with respect to the discontinuation parts of the belts of filling elements adjacent to said belt of filling elements, for example, an offset greater than or equal to one third of the dimension of the peripheral wall in the direction y.
According to an embodiment, the at least one discontinuation part is situated close to an edge of a said peripheral wall, the discontinuation parts of two adjacent belts of filling elements being disposed either side of the peripheral wall.
The discontinuation parts therefore form a staggered grid on the peripheral wall such as to force the flow of gas to take a route comprising a plurality of elbows, which makes it possible to increase the pressure loss.
According to an embodiment, the belts of filling elements comprise a single discontinuation part, the discontinuation parts of two adjacent belts of filling elements being situated on peripheral walls opposite each other.
The disposition of the discontinuation parts therefore makes it possible to force the flow to take a much longer route to descend along the peripheral wall and it therefore takes a diverted route in a horizontal plane with each passage of a belt of filling elements.
According to an embodiment, said discontinuation part is disposed in adjacent corrugations of the first series of corrugations situated at a single insulating panel, said adjacent corrugations being without filling elements.
According to an embodiment, said discontinuation part is situated in one to nine adjacent corrugations of the first series of corrugations, said one to nine corrugations being without filling elements.
It should be noted that an insulating panel situated under the corrugated metal plates can advantageously be of a dimension allowing from three to nine corrugations of the first series of corrugations to be accommodated according to its orientation. It is therefore envisaged that the discontinuation part is formed only on one of the insulating panels so as to simplify the construction of the tank wall but also to limit the size of the discontinuation part so that same can fulfill its pressure loss role.
According to an embodiment, the at least one discontinuation part is situated in a plurality of adjacent corrugations, preferably three to nine corrugations, the discontinuation part including a staggered grid of filling elements, the staggered grid being configured to create a fluidic communication path between the circulation channels situated below the belt of filling elements and the circulation channels situated above the belt of filling elements, said fluidic communication path including a plurality of bends.
According to an embodiment, the filling elements are made in closed cell polymer foam.
According to an embodiment, the filling elements are made in polystyrene or polyethylene foam.
According to an embodiment, the filling elements have a density between 10 and 50 kg/m3, preferably between 20 and 30 kg/m3.
According to an embodiment, the filling elements have a modulus of elasticity at ambient temperature between 1 MPa and 45 MPa in accordance with Standard ISO844, preferably between 1 MPa and 30 MPa.
According to an embodiment, the filling elements have a yield strength between 0.02 MPa and 1 MPa in accordance with Standard ISO844.
According to an embodiment, the filling elements are situated above, below or at a corrugation node in the direction of greater slope, the corrugation node being formed by an intersection between a corrugation of the first series of corrugations and a corrugation of the second series of corrugations.
The filling elements of the obstruction part of a single belt are therefore substantially aligned in the direction x while being situated between two corrugations of the second series of corrugations, including as possible positions of the filling elements the corrugation nodes formed by the intersection of said two corrugations of the second series of corrugations with the corrugation of the first corrugation series.
According to an embodiment, the filling elements of the obstruction part are situated at a corrugation node.
According to an embodiment, the filling elements of the discontinuation part are situated between two corrugation nodes.
According to an embodiment, the filling element includes a single section extending in the direction x, the section having an upper face turned towards the corrugation to close and a lower face turned towards the insulating panel, the lower face being flat so as to rest on the insulating panel, the upper face being domed and being configured to have a shape complementing the corrugation to close.
According to an embodiment, the filling element includes a single section extending in the direction y and two second sections extending in the direction x and situated either side of the first section so as to form an X-shaped filling element, the first section and the second section each having an upper face turned towards the corrugation to close and a lower face turned towards the insulating panel, the lower face being flat so as to rest on the insulating panel, the upper face being domed and being configured to have a shape complementing the corrugation to close.
According to an embodiment, on an upper face turned towards the corrugation to close, the filling elements comprise at least one beading extending in the direction y, the at least one beading being configured to be compressed during assembly so as to form a seal.
According to an embodiment, the filling elements comprise a beading on each second section and two beadings either side of the first section.
According to an embodiment, the sealing membrane is a primary sealing membrane and the thermally insulating barrier is a primary thermally insulating barrier, said juxtaposed insulating panels being primary insulating panels, the tank walls further comprising, successively in a direction of thickness, a secondary thermal insulating barrier including a plurality of juxtaposed secondary insulating panels, the secondary insulating panels being held against the supporting wall of the supporting structure, and a secondary sealing membrane supported by the secondary thermal insulating barrier and disposed between the secondary thermally insulating barrier and the primary thermally insulating barrier such that the primary insulating panels are held against the secondary sealing membrane.
According to an embodiment, the bottom wall comprises a sealing membrane intended to be in contact with the liquefied gas contained in the tank and at least one thermal insulation barrier arranged between the sealing membrane and a supporting wall of a supporting structure, the thermal insulation barrier including a plurality of juxtaposed insulating panels,
According to an embodiment, the bottom wall comprises filling elements with pressure loss, which are disposed in the corrugations of the first series of corrugations or of the second series of corrugations so as to obstruct the circulation channel of said corrugations, the filling elements being distributed over the entire bottom wall so as to form a staggered grid of filling elements in the circulation channels of the bottom wall, and the filling elements being configured to ensure a pressure loss reducing a gaseous flow passing through said circulation channel by at least 80%.
According to an embodiment, the first direction is perpendicular to the second direction.
According to an embodiment, the tank comprises filling elements with pressure loss, which are disposed in the corrugations of the first series of corrugations or of the second series of corrugations in each tank angle formed by the intersection of the bottom wall and one of the peripheral walls so as to obstruct the circulation channel of said corrugations, the filling elements forming an edge belt, the edge belt being formed all round the bottom wall at said angles.
In the event of natural convection phenomena called thermosiphon being present in the peripheral walls, the edge belt therefore makes it possible to limit the propagation of these natural convection phenomena to the bottom wall.
According to an embodiment, each corrugation of the first series of corrugations and of the second series of corrugations of the bottom wall is aligned with a corrugation of the first series of corrugations of a peripheral wall so as to form continuous circulation channels crossing the angles of the tank, the filling elements of the edge belt being disposed in each of said continuous circulation channels.
According to an embodiment, the filling elements of the edge belt are disposed at a first end and at a second end, opposite the first end, of each corrugation of the first series of corrugations and of the second series of corrugations of the bottom wall, the first end and the second end being situated close to one of the tank angles formed by the bottom wall and one of the peripheral walls.
According to an embodiment, the filling elements of the edge belt are disposed close to a tank angle formed by the bottom wall and one of the peripheral walls, alternating between an end of a corrugation of one of the series of corrugations of the bottom wall and an end of a corrugation of the first series of corrugations of a peripheral wall.
According to an embodiment, the invention provides a sealed and thermally insulating tank for storing a liquefied gas, in which the tank includes a bottom wall, a ceiling wall and peripheral walls connecting the bottom wall to the ceiling wall so as to form a polyhedral tank, the bottom wall including a sealing membrane intended to be in contact with the liquefied gas contained in the tank and at least one thermal insulation barrier arranged between the sealing membrane and a supporting wall of a supporting structure, the thermal insulation barrier including a plurality of juxtaposed insulating panels,
Such a tank can be part of a storage installation on land, for example for storing LNG or it can be installed in a floating structure, coastal or in deep water, in particular a LNG tanker, a floating storage and regasification unit (FSRU), a floating production storage and offloading unit (FPSO) and others. Such a tank can also serve as a fuel tank in any kind of vessel.
According to an embodiment, a vessel for transporting a cold liquid product includes a double hull and an aforementioned tank disposed in the double hull.
According to an embodiment, the invention also provides a system for transferring a cold liquid product, the system including the aforementioned vessel, insulated pipes arranged so as to connect the tank installed in the hull of the vessel to a floating or land storage installation and a pump for sending a flow of cold liquid product through the insulated pipes from or to the floating or land storage installation to or from the tank of the vessel.
According to an embodiment, the invention also provides a method for loading or unloading such a vessel, whereby a cold liquid product is fed through insulated pipes from or to a floating or land storage installation to or from the tank of the vessel.
The invention will be better understood, and other aims, details, characteristics and advantages of same will appear more clearly during the following description of several particular embodiments of the invention, given only as an illustration and non-limitative, with reference to the attached drawings.
The description below will describe a sealed and thermally insulating tank 71 for storing liquefied gas, comprising a bottom wall 12, a ceiling wall 13 and a plurality of peripheral walls 1 connecting the bottom wall 12 to the ceiling wall 13, walls 1, 12, 13 being fastened to a supporting structure 2. The peripheral walls are formed from vertical walls and potentially of inclined walls called chamfer walls. The particular case of a vertical wall is illustrated in
In the case of a vertical wall, the direction of greater slope of this wall is thus the vertical direction. The term “vertical” here means extending in the direction of the terrestrial gravity field. The term “horizontal” here means extending in a direction perpendicular to the vertical direction.
The liquefied gas intended to be stored in the tank 1 can in particular be a liquefied natural gas (LNG), that is to say a gaseous mixture including mostly methane and one or more other hydrocarbons. The liquefied gas can also be ethane or a liquefied petroleum gas (LPG), that is to say a mixture of hydrocarbons from oil refining including essentially propane and butane.
As shown in
In the illustrated embodiment, the thermally insulating barrier 3 includes a plurality of insulating panels 5 that are anchored to the supporting wall 2 by means of retaining means or couplers (not illustrated). The insulating panels 5 have a general parallelepiped shape and are disposed in parallel rows. The insulating blocks 5 can be made according to different structures.
An insulating panel 5 can be embodied in the form of a box including a base plate, a cover plate and supporting shells extending, in the direction of thickness of the tank wall, between the base plate and the cover plate and delimiting a plurality of compartments filled with an insulating filling, such as perlite, glass wool or rock wool. Such a general structure is described is described for example in WO2012/127141 or WO2017/103500.
An insulating panel 5 can also be embodied a base plate 7, a cover plate 6 and potentially an intermediate plate, for example made in plywood. The insulating block 5 also includes one or more layers of insulating polymer foam 8 sandwiched between the base plate 7, the cover plate 6 and the potential intermediate plate and bonded to same. The insulating polymer foam 8 can in particular be a foam based on polyurethane, optionally reinforced with fibers. Such a general structure is described for example in WO2017/006044.
The sealing membrane 4 consists of corrugated metal plates 9. These corrugated metal plates are for example in stainless steel whose thickness is approximately 1.2 mm and size 3 m by 1 m. The metal plate, rectangular in shape, includes a first series of parallel corrugations 10 extending in a direction x from one edge of the plate to the other, and a second series of parallel corrugations 11 extending in a direction y from one edge of the metal plate to the other. The directions x and y of the series of corrugations 10, 11 are perpendicular. The corrugations 10, 11 protrude for example on the side of the internal face of the metal plate, intended to be placed in contact with the fluid contained in the tank. The edges of the metal plate here are parallel to the corrugations. The corrugated metal plates include flat portions between the corrugations 10, 11. The intersection between a corrugation of the first series of corrugations 10 and a corrugation of the second series of corrugations 11 forms a corrugation node 20.
In the embodiment described above, a sealing membrane 4 and a thermally insulating barrier 3 have been illustrated and described. The tank wall 1 can therefore consist of a single sealing membrane 4 and a single thermally insulating barrier 3.
However, the tank wall 1 can also comprise a structure called structure with double membranes. In this case, the described thermally insulating barrier 3 is a primary thermally insulating barrier and the sealing membrane 4 is a primary sealing membrane. The tank wall 1 therefore also comprises a secondary thermally insulating barrier fastened to the supporting structure and a secondary sealing membrane supported by the secondary thermally insulating barrier and serving as a support for the primary thermally insulating barrier.
As explained previously, the corrugations of the first series 10 and of the second series 11 of the sealing membrane form circulating channels 14 for a gas present in the primary thermally insulating barrier. Furthermore, the channels 14 formed by the corrugations of the first series of corrugations 10 directed in the direction x, which is the direction of greater slope for an inclined wall, favor the circulation of gas by the thermosiphon effect.
So as to remedy this thermosiphon effect, in the embodiments described in the following, it is envisaged to locate, in the corrugations of the first series of corrugations 10 of the peripheral walls 1, filling elements with pressure loss 15, which are disposed in these corrugations 10 so as to obstruct the circulation channel 14 occasionally and therefore to cut off the circulation of the flow in this corrugation. So as to limit this thermosiphon effect throughout the tank, the filling elements with pressure loss 15 are disposed so as to form a plurality of belts 16 of filling elements. Each belt 16 of filling elements is embodied in a plane parallel to the bottom wall 12 and extending all round the tank 71 as visible in
As visible on
So that the discontinuation part 18 does not allow the thermosiphon effect to become established, it is advantageous to limit the number and/or the size of the discontinuation parts 18 throughout the tank. It therefore seems advantageous that a belt 16 of filling elements does not include more than one discontinuation part 18 per peripheral wall 1.
In the first embodiment of
Contrary to the first embodiment, the second embodiment envisages that a single belt 16 of filling elements includes a plurality of obstruction parts 17 and a plurality of discontinuation parts 18 all round the tank, while respecting a single discontinuation part per peripheral wall 1. Each obstruction part 17 defines an obstruction zone delimited by two discontinuation parts 18. In this embodiment, so as to maximize the route of the flow of gas and thus the pressure loss engendered on this flow, the discontinuation parts 18 of two adjacent belts 16 of filling elements are disposed either side of the peripheral wall 1, for example as illustrated on
It should be noted that an insulating panel 5 situated under the corrugated metal plates 9 has a dimension making it possible, according to its orientation, to accommodate three to nine corrugations of the first series of corrugations 10. On
In the first variant illustrated on
In the second variant illustrated on
In the third variant illustrated in
On
The fourth variant illustrated in
The filling element 15 of
The filling element 15 of
On the peripheral walls 1, only the corrugations of the first series of corrugations 10, which have continuity with the corrugations of the bottom wall 12, have been shown. The corrugations of the first series of corrugations 28 and of the second series of corrugations 29 of the bottom wall have been shown. The number of corrugations of each wall 1, 12 is purely schematic so that the illustrations are legible.
On
In the embodiments illustrated in
With reference to
In a manner known per se, loading/unloading pipes 73 disposed on the upper deck of the tanker can be connected, by means of suitable connectors, to a sea or port terminal so as to transfer an LNG cargo from or to the tank 71.
Pumps on board the tanker 70 and/or pumps equipping the installation on land 77 and/or pumps equipping the loading and unloading station 75 are used to generate the pressure needed for transferring the liquefied gas.
Although the invention has been described in connection with several particular embodiments, it is quite obvious that it is not at all limited to same and that it includes all the technical equivalents of the means described as well as combinations thereof if these enter into the framework of the invention.
The use of the verbs “include”, “comprise” or “incorporate” and their conjugated forms does not exclude the presence of other elements or other steps than those stated in a claim.
In the claims, any reference sign between brackets could not be interpreted as a limit to the claim.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004425 | May 2020 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/061023 | 4/27/2021 | WO |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2021/224071 | 11/11/2021 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3319431 | Clarke | May 1967 | A |
| 3583592 | Kerfman | Jun 1971 | A |
| 3931424 | Helf | Jan 1976 | A |
| 4050608 | Smith | Sep 1977 | A |
| 4155482 | Swaney | May 1979 | A |
| 4207827 | Gondouin | Jun 1980 | A |
| 4461398 | Argy | Jul 1984 | A |
| 6199497 | Dhellemmes | Mar 2001 | B1 |
| 8783501 | Mookerjee | Jul 2014 | B2 |
| 9291308 | Ezzarhouni | Mar 2016 | B2 |
| 9440712 | Bougault | Sep 2016 | B2 |
| 9963207 | Nikolaisen | May 2018 | B2 |
| 10267455 | Sassi | Apr 2019 | B2 |
| 10279992 | Lisin | May 2019 | B2 |
| 10578248 | Delanoe | Mar 2020 | B2 |
| 10876687 | Philippe | Dec 2020 | B2 |
| 11796130 | Durand | Oct 2023 | B2 |
| 20170138537 | Sassi | May 2017 | A1 |
| 20210062972 | Jean | Mar 2021 | A1 |
| 20220373133 | Deletre | Nov 2022 | A1 |
| Number | Date | Country |
|---|---|---|
| WO-2014125186 | Aug 2014 | WO |
| 2019043347 | Mar 2019 | WO |
| 2019102163 | May 2019 | WO |
| Entry |
|---|
| Machine translation of WO 2019102163, published May 31, 2019. |
| International Search Report, dated Jul. 9, 2021, for Application No. PCT/EP2021/061023. |
| Number | Date | Country | |
|---|---|---|---|
| 20230184383 A1 | Jun 2023 | US |
