WO2017051098A2

WO2017051098A2 - Device for containing a liquefied natural gas slick accidentally spilled on the surface of the water

Info

Publication number: WO2017051098A2
Application number: PCT/FR2016/052364
Authority: WO
Inventors: Arnaud Nicolas FOISSAC; Vincent BLANCHETIERE; Vincent PARADOWSKI; Benoît ACKER
Original assignee: Engie
Priority date: 2015-09-21
Filing date: 2016-09-19
Publication date: 2017-03-30
Also published as: FR3041367B1; FR3041367A1; WO2017051098A3

Abstract

The present invention relates to a device (1) for containing a liquefied natural gas slick (10) spread over a water surface. Said device (1) includes a buoyant structure (6), to which is coupled a containing means (7) having a first surface (9), to be at least partially oriented towards the liquefied natural gas (10) and comprising a protective means (8) capable of insulating the buoyant structure (6) from the liquefied natural gas (10) and withstanding temperatures between about -170°C and +70°C.

Description

Device for confining a layer of liquefied natural gas accidentally spilled on the surface of the water

TECHNICAL FIELD The present invention relates to devices which are intended to combat the spreading of a layer of liquefied natural gas (or LNG) and the dispersion of LNG vapors in the event of accidental spillage on water.

State of the art Liquefied natural gas (or LNG) is transported and stored at a temperature of about -160 ° C. Following an accidental spill, LNG can spread (or spread) on a surface and evaporate. There is then a risk of ignition of LNG vapors mixed with air for a volume concentration of between 5% and 15%. As a result, the risks of LNG leakage are taken into account when designing LNG production, transport, use, distribution or storage facilities (and in particular in LNG liquefaction plants, LNG tankers, LNG terminals). regasification, and LNG distribution stations).

The invention relates more specifically to accidental spills or leaks that may occur on water, such as the docking by a vessel of a port LNG terminal. In this case, the heat input of the water induces a strong evaporation of the LNG and thus the creation of a large cloud of flammable gas, which can sometimes reach several hundred meters long, when certain meteorological conditions are met. This flammable gas cloud can then reach neighboring installations (with GN L or non-LNG vocation) or areas potentially with a high human density (such as passenger loading / unloading areas for ferries using LNG as fuel). . In order to minimize the consequences of LNG leakage on water, many national or regional regulations impose significant safety distances between potentially LNG-leaking equipment and facilities or zones. populated neighbors. These regulations may hinder the development of internal and / or neighboring industrial activities, or may make it very difficult, if not impossible, to obtain the administrative license to operate an industrial LNG facility. To allow compliance with the safety distances imposed by the regulations, it is necessary to limit the spread of the LNG slick on the water. Indeed, without limit of confinement, the LNG will spread on the water by generating a very thin sheet. The heat input of the water will cause a strong evaporation of the LNG which will generate a very large cloud of vapors. Indeed, the larger the area occupied by LNG, the easier it is to evaporate, and therefore the greater the safety zone. To prevent the spread of an LNG slick, when the LNG facility is on the ground, it is possible to define retention ponds around the storage tanks or concrete channels below the LNG transfer pipes. . But this type of solution can not be implemented on water, and more generally there is no known effective solution today for confining LNG slick on the water.

It was also proposed to use a boom like the one called FESTOP ^® company Floch the remediation to contain an oil extended fire. These dams have floating elements made of stainless steel. These dams resist high temperatures, but the metal elements are rendered fragile by low temperatures. In addition, these dams are very expensive because entirely of metal.

Description of the invention

The invention therefore aims to improve the situation, and more specifically to allow, in case of accidental spill or leak, a reduction in the size of the LNG sheet so as to limit its evaporation.

An object of the invention relates to a device for confining a layer of liquefied natural gas spread over a surface of water, and comprising a floating structure to which is coupled a containment means having a first face, intended to be oriented, at least in part to said liquefied natural gas and having a protective means suitable for isolating the floating structure from the liquefied natural gas and withstanding temperatures of between about -170 ° C and + 70 ° C. Note that this temperature range is composed of a first cryogenic operating range extending from -170 ° C to -120 ° C and corresponding to the operation of the dam in the presence of LNG and a second operating range of - 20 to + 70 ° C corresponding to the operation of the non-LNG dam in environments such as the polar circle or the Persian Gulf. The containment device according to the invention may comprise other characteristics that can be taken separately or in combination, and in particular: in a first embodiment, its floating structure may comprise at least one foam part or at least one box filled with air to ensure a flotation;

the confinement means may comprise at least one textile main envelope defining at least one housing in which the floating structure is housed, and the protection means may be a cryo-resistant coating secured to the first face of this main envelope;

it may also comprise an auxiliary envelope made of textile, comprising a first part secured to the main envelope and a second part defining at least one housing in which is housed a weighting chain, and having an outer surface secured to a protection means arranged in the form of a cryo-resistant coating capable of isolating it from liquefied natural gas and withstanding temperatures of between about -170 ° C and + 70 ° C;

the second part of the auxiliary envelope can accommodate at least one part made of thermally insulating material and surrounding the weighting chain;

the main casing and the auxiliary casing may be made of cryopresistant materials selected from (at least) fluoropolymers, polyimide and polyamide;

in a second embodiment, the confinement means may comprise panels, possibly removable, and each provided with a first face to which the protection means are fixedly secured and a rear face to which a fastening means is fixedly secured, optionally removable, and coupled to the floating structure;

the rear face of each panel can be equipped with a float in a lower part; the panels may overlap partially or be connected to one another so as to form a continuous barrier;

the protection means may be a cryo-resistant and cryo-insulating coating;

the floating structure may be made of metallic material, and the protective means may be arranged to thermally isolate the first face in contact with the liquefied natural gas of the floating structure;

the cryo-resistant coating may, for example, be a polymer, such as for example a PCTFE; it may also comprise at least one diffusion means capable of reducing the concentration in the ambient air of the liquefied natural gas vapors, and comprising, on the one hand, a blower equipped with a first inlet capable of sucking vapors resulting from the heating of the liquefied natural gas, a second inlet for injecting a selected gas under pressure (fed by a pipe), and an outlet for delivering a mixture of vapors of liquefied natural gas and of selected gas, and on the other hand, a duct comprising an inlet communicating with the outlet of the blower and an outlet, and having a frustoconical shape capable of inducing an acceleration of the mixture intended to reach a speed much higher than a wind speed before it is ejected by this last output.

Brief description of the figures

The invention will be better understood on reading the description which follows, given solely by way of example, and with reference to the appended figures in which:

FIG. 1 schematically illustrates an example of a port facility to which a vessel carrying liquefied natural gas is moored and near which a containment device according to the invention is installed,

FIG. 2 schematically illustrates, in a sectional view, a first exemplary embodiment of a confinement device according to the invention,

FIG. 3 schematically illustrates, in a perspective view, a second exemplary embodiment of a confinement device according to the invention,

FIG. 4 schematically illustrates, in a sectional view, a part of the confinement device of FIG. 3, and

- Figure 5 illustrates schematically, in a sectional view, an exemplary embodiment of a dilution device which can be part of a containment device according to the invention.

Embodiments The object of the invention is in particular to propose a containment device 1 intended to be installed on the water to confine a layer of liquefied natural gas (or LNG) which has accidentally spilled, for example from a piece of equipment. 2.

It is important to note that the containment device 1 can be deployed either preventively on the water where an accidental LNG spill could occur, or following the occurrence of an LNG leak in an area containing water. 'water.

In what follows, it is considered, by way of non-limiting example, that the zone containing water is located in a port, at a LNG terminal. But the invention is not limited to this type of zone containing water. In fact, it concerns any zone containing water and where a production, transport, utilization, distribution, or temporary installation facility is located temporarily. or storage of LNG, such as an LNG liquefaction plant, a LNG tanker, a LNG regasification or LNG delivery terminal, or an LNG distribution station.

FIG. 1 diagrammatically shows a small part of a dock 3 of a port to which is fixedly secured a wharf 4 to which is temporarily docked a LNG carrier 5. For example, the latter (5) is in the process of transferring the LNG stored in its tanks to a storage tank placed behind the platform 3, via a pipe 2 whose access is controlled by valves.

In the nonlimiting example illustrated in FIG. 1, the confinement device 1 is installed in a preventive manner between the two opposite ends of the ship 5 and the platform 3.

As best illustrated in FIGS. 2 and 4, a confinement device 1 comprises at least one floating structure 6, a confinement means 7 and a protection means 8.

The (each) means of containment 7 is coupled to the (a) floating structure 6 and comprises a first face 9 intended to be oriented, at least in part, towards the liquefied natural gas 10 leaking equipment 2 and spreads on the water in the form of a tablecloth. This equipment 2 is for example a pipe or a valve. Note that in the nonlimiting example illustrated in Figure 1, the containment device 1 comprises two floating structures 6, one being secured to a first end of the ship 5 and a first location of the platform 3, the other being secured to a second end of the ship 5 and a second location of the platform 3. This creates a containment zone between one side of the ship 5 (facing the platform 3), the platform 3 and the two floating structures 6. But the number of floating structures 6 of the containment device 1 can take any value greater than or equal to one (1).

The aforesaid first face 9 of each confinement means 7 comprises a protection means 8 which is able to isolate the floating structure 6 from the liquefied natural gas 10 and to withstand temperatures of between about -170 ° C and + 70 ° C. Thus, the floating structure 6 is protected from very low temperatures by a cryo-resistant protection means 8.

The floating structure 6 can be realized in at least two ways.

Thus, in a first embodiment shown in non-limiting manner in FIG. 2, the (each) floating structure 6 may comprise at least one foam piece or at least one box filled with air to ensure a flotation. This foam can possibly withstand very low temperatures to increase its durability. In this case, it may, for example, be BASOTECT ^® , which is marketed by the BASF Company and which is sometimes used in tanks LNG ship against the ballot. But it could also be a more conventional product such as polyethylene (or PE) In this first embodiment, the (each) means of containment 7 can, as illustrated without limitation in FIG. less a textile main casing which defines at least one housing 11 in which is housed the foam part (or at least one chamber filled with air) 6. In this case, the protective means 8 may be a cryo-resistant coating (That is to say, resistant to temperatures between about -170 ° C and + 70 ° C) and optionally cryo-insulator, secured to the first face 9 of the associated main envelope 7. This cryo-resistant coating and optionally cryo insulation 8 may, for example, be a polymer, such as a polychlorotrifluoroethylene (PCTFE or (optionally one that is marketed under the name ^® Neoflon by Daikin)). Other coatings such as the Firetex M89 / 02 25mm (produced by Leighs Paint / sherwin) or the PittChar Xp 10mm + Insulon 15mm (produced by PPG) combine the properties of cryo-resistance and cryo-insulation. The skilled person is therefore led to choose from the available materials the one that best suits the needs of the intended application.

The (each) main envelope 7 may, for example, be made with a cryo-resistant material selected from at least fluoropolymers, polyimide and polyamide. For example, it may be woven polytetrafluoroethylene (or PTFE) fibers (possibly those marketed by Lenzing Plastics). Nevertheless, other materials than those previously mentioned and known to those skilled in the art can be used.

It will be noted that the floating structure 6 may be made of metallic material, and the protective means 8 may be arranged to thermally insulate the first face 9, in contact with the liquefied natural gas, of the floating structure 6. It will also be noted that the same main envelope 7 may comprise one or more pieces of foam (or one or more boxes filled with air) 6. Similarly, a containment device 1 may comprise a main envelope 7 or several main envelopes 7 secured to each other. other.

Furthermore, in this first embodiment, the confinement device 1 can, as illustrated without limitation in FIG. 2, also comprise an auxiliary envelope 12 made of textile, comprising first 13 and second 14 parts secured to each other. other. The first part 13 is fixedly secured to the associated main shell 7 and the second part 14 defines at least one housing in which is housed a weighting chain 15. For example, this weighting chain 15 may be made of steel (possibly stainless). It will be noted that this weighting chain 15 may be optionally protected by an envelope.

The (each) auxiliary envelope 12 then has an outer face to which is secured a protective means 16 which is arranged in the form of a cryo-resistant coating adapted to isolate it from the liquefied natural gas 10 and to withstand high temperatures. between about -170 ° C and + 70 ° C. This protection means 16 may, for example, be a polymer.

It will be noted that the second portion 14 of the auxiliary envelope 12 may possibly accommodate at least one piece 17 made of thermally insulating material and surrounding the weighting chain 15. It will be understood that this insulating piece 17 is intended to prevent stiffening of the weighting chain 15 and to increase the durability of the latter (15). For example, this insulating part 17 can be made of pearlite.

The (each) auxiliary envelope 12 is preferably made of the same material as the main envelope 7 with which it is associated. Therefore, it can, for example, be made with woven polytetrafluoroethylene (or PTFE) fibers.

In a second embodiment shown in non-limiting manner in FIGS. 3 and 4, the (each) floating structure 6 may comprise at least one main envelope 18 defining at least one housing containing air, and the confinement means 7 may comprise panels, possibly removable, and each provided with a first face 9 (front) to which the protection means 8 and a rear face 19 are fixedly secured to which a fixing means 20, possibly removable, is fixedly secured, and which is coupled to the floating structure 6 (here to the associated main envelope 18). It will be understood that the first face 9 is that which is oriented towards the LNG 10, while the rear face 19 is the one which is oriented towards the water and therefore which is opposite the first face 9. It will also be noted that all the faces each panel 7 may optionally be coated with a protection means 8.

The (each) main envelope 18 may, for example, be made of a high-strength waterproof material (such as a neoprene-hypalon, PU or PVC).

Each panel 7 is preferably made of a rigid material, such as for example a steel or a plastic or composite material (such as for example PE or glass fibers). The (each) fastening means 20, associated with a panel 7, may, for example, be in the form of a clipping lug comprising a first end securely fixed to the rear face 19 of this panel 7, and a second end of a shape adapted for coupling by clipping to the main envelope 18.

The protective means 8 may, for example, be a cryo-resistant coating, similar to that described with reference to Figure 2. Therefore, it may, for example, be a polymer, such as a polychlorotrifluoroethylene (or PCTFE).

It will be noted, as shown in non-limiting manner in FIG. 4, that in order to ensure the flotation of the panels 7 and to prevent them from tilting (7), the rear face of each panel 7 may advantageously be equipped with a float 21 in a lower part (in contact with water). Each float 21 may, for example, be a foam part supporting very low temperatures. In this case, it may, for example, be the aforementioned BASOTECT ^® .

It will also be noted, as illustrated without limitation in FIG. 3, that the panels 7 may have small dimensions and overlap partially. For example, the dimensions of each panel 7 may be between 1 m and 3 m for the length and up to 1 m for the height. This provides flexibility and deformability to each assembly consisting of a floating structure 6 and panels 7, while ensuring sealing. In addition it facilitates the storage of each aforementioned set. The sealing may be possibly reinforced by the presence of flexible flaps, cryo-resistant and fixedly secured to the panels 7 on at least some of the peripheral edges of their first face 9. The panels 7 may also be connected to each other so as to form a continuous barrier. It will also be noted, as illustrated in non-limiting manner in FIGS. 1 and 5, that it is particularly advantageous for the confinement device 1 to comprise at least one dispersing means 22 intended to reduce the size of the cloud of LNG vapors. the size of the LNG vapor cloud 10, the LNG vapors can be moved upwards. Thus, the cloud surface size is reduced and the LNG vapors are dispersed in height. This dispersing means 22 can be fixedly installed (and thus permanently) on a dock or a pier 4, or be movable to facilitate its positioning in a chosen location, such as for example in the vicinity of a device 2 subject to of a leak.

Furthermore, this dispersing means 22 comprises at least one blower (or equivalent) 23 and a duct 24. The blower 23 is provided with a first inlet 25 for sucking vapors resulting from the evaporation of the liquefied natural gas 10 ( according to the arrow 30), a second inlet 26 for injecting a selected gas under pressure (such as for example outside air or nitrogen (often available on ships and on wharves or docks)), and an output 27 clean to deliver a mixture of fumes of LNG 10 and selected gas (according to arrow 31). The first inlet 25 of the blower 23 is optionally coupled to a cryo-resistant pipe whose inlet is placed above the level of the LNG layer 10, to allow operation at low temperature. The second inlet 26 of the blower 23 is coupled to a pipe 28, possibly cryo-resistant, and which is also coupled to a selected gas container or which opens out in a zone remote from the LNG 10.

The duct 24 comprises an inlet 29 communicating with the outlet 27 of the blower 23 and an outlet 32, and has a frustoconical shape capable of inducing an acceleration of the mixture (selected LNG / gas vapors) which is intended to generate a flow velocity faster than the wind before it is ejected by the exit 32 (according to the arrow 33). This acceleration, which results mainly from a relaxation of the mixture and therefore an increase in speed to conserve energy, is for example due to a venturi effect. The speed of ejection of the mixture must be greater than the wind speed so that the ejected mixture is not immediately carried away by the wind.

By placing one or more dispersing means 22 within a confinement zone, the cloud of LNG vapors can be dispersed rapidly. In addition, the turbulence and the ejection speed generated by the ejection of the mixture (selected LNG / gas vapors) at the outlet 32 of each dispersing means 22 makes it possible to significantly accentuate the effect of dispersion of the vapors. of LNG and thus limit the spread of the LNG layer 10 and the resulting cloud.

Preferably, the blower 23 and the frustoconical duct 24 are made of stainless steel.

Such a dispersion means 22 combines the suction, the dilution of the methane with the selected gas and the high-speed ejection without mechanical part and therefore without risk of ignition of the mixture.

It will be understood from the foregoing description that in a first implementation of the invention, the entire confinement device 1 can be cryo-resistant, whereas in a second implementation of the invention, the confinement device 1 can comprise a standard part coupled to a confinement means 7 which is provided with a protection means 8 providing thermal insulation. The invention offers several advantages, among which:

a high reliability because the confinement device is passive, except for the possible dilution means, which is however very simple,

a high efficiency of the dispersion of LNG vapors in the air,

- ease of installation and use,

- Reduced maintenance due to its adaptation to aqueous media.

Claims

1. Device for confining (1) a layer of liquefied natural gas (10) spread over a surface of water, said device (1) comprising a floating structure (6) to which is coupled a means of confinement (7) having a first face (9), to be oriented, at least in part, towards said liquefied natural gas (10) and having a protective means (8) adapted to isolate said floating structure (6) from said liquefied natural gas (10) ) and withstand temperatures between about -170 ° C and + 70 ° C.

2. Device according to claim 1, wherein said floating structure (6) comprises at least one foam piece or at least one box filled with air to provide a flotation.

3. Device according to claim 2, wherein said confinement means (7) comprises at least one textile main envelope defining at least one housing (11) in which is housed said floating structure (6), and wherein said means of protection (8) is a cryo-resistant coating secured to said first face (9) of said main envelope (7).

4. Device according to claim 3, further comprising a textile auxiliary envelope (12), comprising a first portion (13) secured to said main envelope (7) and a second portion (14) defining at least one housing in which is housed a weighting chain (15), and having an outer surface secured to a protection means (16) arranged in the form of a cryo-resistant coating adapted to isolate it from said liquefied natural gas (10) and to withstand at temperatures between about -170 ° C and + 70 ° C.

5. Device according to claim 4, wherein said second portion (14) of the auxiliary casing (12) houses at least one part (17) made of thermally insulating material and surrounding said weighting chain (15).

6. Device according to one of claims 3 to 5, wherein said main envelope (7) and said auxiliary envelope (12) are made of cryo-resistant materials selected from a group comprising fluoropolymers, polyimide and polyamide .

7. Device according to one of claims 1 and 2, wherein said containment means (7) comprises panels each provided with a first face (9) which is fixedly secured to said protection means (8) and a rear face (19) to which is fixedly secured a fastening means (20) coupled to said floating structure (6).

8. Device according to claim 7, wherein said rear face (19) of each panel (7) is equipped with a float (21) in a lower part.

9. Device according to one of claims 7 and 8, wherein said panels (7) overlap partially or are connected to each other so as to form a continuous barrier.

10. Device according to one of claims 7 to 9, wherein said protective means (8) is a cryo-resistant and cryo-insulating coating.

11. Device according to one of claims 7 to 10, wherein said floating structure (6) is made of metal material, and said protective means (8) is arranged to thermally insulate said first face (9) in contact with the liquefied natural gas of said floating structure (6).

12. Device according to one of claims 1 to 11, further comprising at least one diffusion means (22) adapted to reduce the concentration in the ambient air of the liquefied natural gas vapor, and comprising, on the one hand, a blower (23) provided with a first inlet (25) adapted to suck vapors resulting from the evaporation of the liquefied natural gas (10), a second inlet (26) for injecting a selected gas under pressure, and an outlet (27) capable of delivering a mixture of vapors of liquefied natural gas (10) and of selected gas, and, on the other hand, a duct (24) comprising an inlet (29) communicating with said outlet (27) of the blower (23) and an outlet (32), and having a frustoconical shape adapted to induce an acceleration of said mixture intended to reach a speed much higher than a wind speed before it is ejected by said output ( 32).