EP1449763B1 - Method and installation of subsea effluent pollution recovery from a sunken tanker by using multiple shuttle tanks - Google Patents

Abstract

The shuttle reservoir has a collecting (2A) and a deploying (2B) form. It is repeatedly lowered to the seabed (7) in its collecting form, where it connects to an evacuation device (6) in the hull (6) of the damaged vessel and is filled and sealed shut. Integral floatation devices lift it to a surface vessel in its deployed form, where it is emptied or stored for transportation to shore : The evacuation device (6) contains a pipe and a first valve acting with an opening in the hull and/or the vessel to recover the effluents by lifting them into the evacuation device. The shuttle reservoir has at least one main internal orifice (5) which works with the evacuation device. These steps are repeated with the same shuttle reservoir until the required amount of effluent has been recovered. The shuttle reservoir has a rigid dome with an open circular base, preferably with a shell shape in vertical section, a rigid circular base and a flexible side wall which can be folded up into the filling position and unfolding as it fills to the deployed shape. The floatation elements are integral inside the dome and are preferably a syntactic mousse. The centre of buoyancy is above the apparent centre of gravity in the water. The reservoir can be moved by floating it into a submersible bridge vessel without having to lift it. The shuttle reservoir is held near the sunken vessel by an anchor cable to the seabed and a second anchor cable to the vessel. The reservoir is automatically decoupled from the sunken vessel before it rises to the surface when traction is applied matching the Archimedes force of the reservoir and its load, transmitted by the anchor cable to detach it from the vessel or break the cable at a threshold value. The speed with which the reservoir rises is controlled by a weighted cable or chain from the surface to the base of the reservoir.

Description

The present invention relates to a recovery method and installation of effluents at sea and more particularly polluting effluents contained in a ship sunken and damaged lying at the bottom of the sea.

When the tankers sank, the ship sank in general after being deeply damaged and having lost some of his cargo. When the depth of water is important, for example 100 or 200 meters, the recovery of the wreck or its refloating, is not generally considered, but the hull must be completely emptied and rinsed, so that the corrosion of the structure in the time, creating localized or generalized holes, does not lead to the release of the contents of the ship, creating pollution that may last for years or even years. decades.

Many processes and devices have been studied and used in the past to trying to recover highly polluting cargoes, but all are either not technically reliable, very difficult to implement and operations take a lot of time and in general generate secondary pollution, because the rate of recovery is far from satisfactory, and all the more so since the process must be work at great depth.

1) on descend un réceptacle comprenant un orifice inférieur à l'aide de moyens de positionnement à proximité et à la verticale d'au moins une ouverture dans la coque et/ou la cuve du navire mettant en communication l'intérieur de la cuve du navire avec l'extérieur, de manière à récupérer lesdits effluents polluants s'écoulant de ladite ouverture par remontée de ceux-ci dans ledit orifice inférieur dudit réceptacle, et

2) lorsque ledit réceptacle est rempli d'effluents polluants, on remonte ledit réceptacle à l'aide desdits moyens de positionnement jusqu'à ce que des moyens de vidange dudit réceptacle comprenant un orifice supérieur obturable dudit réceptacle et/ou une conduite d'évacuation reliée au dit orifice supérieur à la partie supérieure dudit réceptacle soient accessibles en surface, et

3) on vide ledit réceptacle dans une installation ou navire en surface à travers lesdits moyens de vidange accessibles en surface.

4) on répète les étapes 1) à 3) jusqu'à ce que la quantité voulue d'effluents soit récupérée.

In particular, it has been described in FR 2 804 935 in the name of the applicant, a method of recovering polluting effluents, lighter than water and little or not miscible with water, contained in a tank of a a sunken and / or damaged vessel lying at the bottom of the sea, which comprises the following steps in which:

1) a receptacle comprising a lower orifice is lowered by means of positioning means in the vicinity and vertically of at least one opening in the hull and / or the tank of the vessel placing in communication the interior of the vessel of the vessel; vessel with the outside, so as to recover said polluting effluents flowing from said opening by raising them in said lower orifice of said receptacle, and

2) when said receptacle is filled with polluting effluents, said receptacle is raised using said positioning means until means for emptying said receptacle comprising a closable upper orifice of said receptacle and / or an evacuation pipe; connected to said upper orifice at the upper part of said receptacle are accessible on the surface, and

3) emptying said receptacle in a facility or vessel surface through said draining means accessible on the surface.

4) steps 1) to 3) are repeated until the desired amount of effluent is recovered.

a) ledit réceptacle consiste en une cloche en forme d'entonnoir dont la grande base ouverte constitue ledit orifice inférieur et couvre une zone de fuite desdits effluents, ladite zone comprenant une ou plusieurs dites ouvertures dans la coque et/ou la cuve dudit navire, et la petite base supérieure dudit entonnoir donne accès au dit orifice supérieur, et

b) lesdits moyens de positionnement comprennent :

• des moyens d'ancrage dudit réceptacle sur le navire comprenant des câbles reliant des points d'attache fixés sur la circonférence de ladite grande base de l'entonnoir et des points d'attache sur le navire, et
• des moyens de tensionnement comprenant :
  • des flotteurs reliés à la circonférence de ladite grande base ouverte dudit réceptacle et autour de la section tubulaire en partie supérieure de la petite base dudit entonnoir, et
  • des treuils correspondants aux dits points d'attache sur le navire, et

c) lesdits moyens de vidange comprennent une dite conduite d'évacuation reliée par une extrémité au dit orifice supérieur comprenant ladite section tubulaire en partie supérieure dudit entonnoir, ladite conduite étant mise en tension sensiblement verticalement à l'aide d'un flotteur relié à l'extrémité libre de ladite conduite.

In a first variant embodiment described in FR 2 804 935:

a) said receptacle consists of a funnel-shaped bell whose large open base constitutes said lower orifice and covers a leakage zone of said effluents, said zone comprising one or more said openings in the hull and / or vessel of said vessel, and the small upper base of said funnel gives access to said upper orifice, and

b) said positioning means comprise:

• means for anchoring said receptacle on the vessel comprising cables connecting attachment points fixed on the circumference of said large base of the funnel and attachment points on the ship, and
• tensioning means comprising:
  • floats connected to the circumference of said large open base of said receptacle and around the tubular section in the upper part of the small base of said funnel, and
  • winches corresponding to said attachment points on the ship, and

c) said draining means comprise a said discharge pipe connected at one end to said upper orifice comprising said tubular section in the upper part of said funnel, said pipe being tensioned substantially vertically with the aid of a float connected to the free end of said pipe.

In this first embodiment, the implementation of said means for positioning, during successive descents and ascents of said receptacle, represents a very long operation and relatively difficult to achieve at great depth. In in addition, the pumping, through a so-called evacuation pipe, is not possible for such depth, especially when the effluent has a high viscosity and tends to freeze paraffin form. Even if we install a heating system in the zone of catchment or in the upper part of the bell during the ascent, the viscous effluent has tendency to freeze, making pumping very difficult.

• un conteneur rigide de forme sensiblement tubulaire, qui est maintenu en position verticale à l'aide de flotteurs installés au moins à l'extrémité supérieure ou à chaque extrémité supérieure et inférieure dudit conteneur, et
• lesdits orifices supérieur et inférieur dudit conteneur étant obturables de sorte que ledit réceptacle peut être remonté en surface et installé en position horizontale flottante lorsque lesdits orifices sont obturés, ledit réceptacle pouvant alors être remorqué vers une installation ou un navire de stockage desdits effluents.

In a second variant embodiment described in FR 2 804 935, said receptacle consists of:

• a substantially tubular rigid container, which is held in a vertical position by means of floats installed at least at the upper end or at each upper and lower end of said container, and
• said upper and lower ports of said container being closable so that said receptacle can be raised to the surface and installed in a floating horizontal position when said orifices are closed, said receptacle can then be towed to an installation or a storage vessel of said effluents.

These rigid containers shaped cigar called, by their size important, are difficult to descend to the bottom of the sea and, to avoid successive, a preferred embodiment has been described in which said container occupies the entire slice of water between the wreck and the surface. But, it is obvious that this second variant can not be envisaged for depths of 1000 meters or more, because it involves a receptacle much too bulky, impossible to install or go down frequently.

In practice, the various embodiments described in FR 2 804 935, do not not suitable for interventions at depths greater than 1000 meters.

The object of the present invention is to provide a method and an installation to recover the contents of the bunkers of a ship, for example a tanker, resting on the seabed, in deep water depths, especially greater than 3000 meters, or even 4000 to 5000 meters, and which do not have the disadvantages of previous methods and devices and, in particular, which are more reliable technically, easier and easier to implement.

a) on installe un dispositif d'évacuation des effluents comprenant de préférence au moins une canalisation et une première vanne, coopérant avec une ouverture de la coque et/ou de la cuve de manière à pouvoir récupérer lesdits effluents polluants s'écoulant de ladite ouverture par remontée de ceux-ci jusqu'audit dispositif d'évacuation, et

b) on récupère lesdits effluents s'écoulant de ladite ouverture de la coque et/ou de la cuve,

To this end, the present invention provides a method for recovering polluting effluents lighter than water, contained in a tank of a cast and / or damaged vessel resting at the bottom of the sea in which:

a) installing an effluent evacuation device preferably comprising at least one pipe and a first valve, cooperating with an opening of the shell and / or the tank so as to be able to recover said polluting effluents flowing from said opening by raising them up to said evacuation device, and

b) recovering said effluents flowing from said opening of the shell and / or the vessel,

1- on descend ledit réservoir navette, depuis la surface jusqu'au fond de la mer, dans sa dite position ramassée et on fait coopérer ledit orifice inférieur du réservoir navette avec ledit dispositif d'évacuation, et

2- on remplit d'effluents ledit réservoir navette, puis, une fois rempli d'effluents, dans sa dite configuration déployée, on le ferme pour le rendre étanche, et

3- on laisse ledit réservoir navette remonter à la surface, une fois rempli, en configuration déployée, ledit réservoir navette, comprenant de préférence des éléments de flottabilité, et

4- de préférence, on stocke ledit réservoir navette rempli d'effluents dans un navire en surface et on vide ledit réservoir navette dans ledit navire ou on le transporte dans un site pour y être vidé, et

5- le cas échéant, on répète les étapes 1 à 4 avec ledit réservoir navette, ou un autre réservoir navette, jusqu'à ce que la quantité voulue d'effluents soit récupérée.

According to the present invention, in step b), said effluents are recovered by means of a shuttle tank, which can adopt a picked configuration and an expanded configuration, said shuttle tank comprising at least one lower main orifice adapted to cooperate with said evacuation device, so that the steps are carried out in which:

1 - down said shuttle tank, from the surface to the bottom of the sea, in its said collected position and is made to cooperate with said lower orifice of the shuttle tank with said evacuation device, and

2- said effluent tank is filled with effluent, then, once filled with effluents, in its said deployed configuration, it is closed to make it watertight, and

3- the said shuttle reservoir is allowed to rise to the surface, once filled, in deployed configuration, the said shuttle reservoir, preferably comprising buoyancy elements, and

Preferably, said effluent-filled shuttle tank is stored in a surface vessel and said shuttle tank is emptied into said vessel or transported to a site for emptying;

If desired, steps 1-4 are repeated with said shuttle tank, or other shuttle tank, until the desired amount of effluent is recovered.

The use of a tank shuttle that can adopt a gathered configuration, that is to say, small footprint, makes it easy to descend to the bottom of the sea, and the case where appropriate, the connection with the wreck, in particular by connecting the said lower orifice of the shuttle tank with said evacuation device, in particular using a ROV. Else on the other hand, the so-called shuttle tank, because of the inherent buoyancy of oil and its possible additional buoyancy, allows the return of the effluents without the use of a bottom-surface connection pipe and / or without pumping, from the surface, of effluents to be recovered.

In a particular embodiment, said tank is filled with seawater before descending it to the bottom of the sea in deployed configuration filled with seawater. Thus, later, at the bottom of the sea, seawater will be replaced by said effluents when filling said reservoir with effluents.

a) un dôme rigide à base circulaire ouverte, de préférence avec un profil en forme d'obus en section verticale,

b) un fond rigide, de préférence plat, dont la périphérie est de préférence circulaire, et

c) une paroi périphérique latérale constituant une enveloppe souple, assurant la liaison de ladite base du dôme avec la périphérie dudit fond de sorte que :

• ladite paroi périphérique latérale peut être repliée sur elle-même, pour permettre le rapprochement dudit dôme et dudit fond, de préférence à l'aide de sangles amovibles, ledit réservoir navette étant alors en dite position ramassée et
• lesdits effluents pouvant être confinés à l'intérieur dudit réservoir navette lorsque ladite paroi latérale est dépliée, ledit réservoir navette étant alors en dite position déployée.

In a particular embodiment, said shuttle reservoir comprises:

a) a rigid dome with an open circular base, preferably with a profile in the form of a shell in vertical section,

b) a rigid bottom, preferably flat, the periphery of which is preferably circular, and

c) a lateral peripheral wall constituting a flexible envelope, ensuring the connection of said base of the dome with the periphery of said bottom so that:

• said lateral peripheral wall can be folded back on itself, to allow said dome and said bottom to be brought together, preferably by means of removable straps, said shuttle tank then being in said picked up position and
• said effluents being confined within said shuttle tank when said side wall is unfolded, said shuttle tank then being in said extended position.

Said rigid bottom of the reservoir may consist of a solid bottom comprising preferably a second port equipped with a second valve, where said rigid bottom may be constituted by an open frame, preferably annular, delimiting a said lower orifice main tank.

The lower orifice may correspond to said second valve installed in the bottom tank or at the openings of the peripheral envelope and, where appropriate, said additional flexible internal pocket delimited by said open frame to which they are connected.

Said dome, with its profile in particular in the form of a shell in vertical section, associated with said buoyancy elements facilitates the recovery to the surface of the tank shuttle once full, using the only clean buoyancy of the oil and where appropriate additional buoyancy elements.

Here we mean by shell profile: a profile in the form of an ellipsoid or paraboloid well known to those skilled in the art.

Advantageously, said buoyancy elements of said shuttle tank are incorporated within said dome, said buoyancy elements preferably consisting of in syntactic foam.

More preferably, said buoyancy elements are integrated with the interior of said dome in its upper part, so that the center of buoyancy of said shuttle tank filled with effluent is shifted upward relative to its center of apparent gravity in the water.

We install enough buoyancy and in a position high enough that the center of buoyancy, thus shifted upwards, associated with the profiled shape of the dome, allows the shuttle tank to maintain, during its natural ascent, a trajectory substantially rectilinear and vertical, then, arrived at the surface, to maintain easily in a horizontal position to be towed and then directed to a storage, preferably a submersible pontoon vessel, for the purpose of introducing shuttle tank of said vessel without having to remove said shuttle tank from the water.

In a particular embodiment, said shuttle tank is maintained at proximity of said effluent evacuation device by means of anchoring means, comprising at least one anchor cable connecting at least one first fixed attachment point in the lower part of the tank, near said bottom of the tank, preferably on the periphery of said bottom of the shuttle reservoir and at least a second point of attachment on the sunken vessel, or the seabed, for anchoring said shuttle tank on said sunken ship or on the bottom of the sea.

Said buoyancy elements associated with said shuttle tank ensure the tensioning of said cables, thus making it possible to maintain said shuttle tank in suspension near and vertically said opening of the shell and / or tank and, the where appropriate, in cooperation with said evacuation device. These anchoring means can be easily implemented using a submarine vehicle ordered at distance (ROV).

Advantageously, before step 3 of raising of the shuttle tank, one carries out a step of automatic disconnection of said anchoring means which is realized automatically when the shuttle tank has reached a fill rate predetermined, especially when the tank is full or almost full.

More particularly, at least one said anchor cable cooperates with a first automatic disconnection device on which a traction corresponding to the Archimedes thrust acting on said shuttle tank and its cargo, traction transmitted by said anchoring cable, said disconnecting device having the effect of cause disconnection of said anchor cable by disconnection of said cable anchoring with said tank or with said vessel at the bottom of the sea or by breaking the said anchoring cable, and to allow at least partial reassembly of said shuttle tank, when this traction reaches a first determined threshold value, preferably when said shuttle tank is filled with effluents.

When the reservoir fills with effluents, the buoyancy of Archimedes is exerted on the shuttle tank / cargo tank assembly increases as the the effluent, lighter than water, replaces the water inside said shuttle tank up to to reach a maximum value when full. This buoyant Archimedes on the tank and its cargo, is transmitted to the automatic disconnection device by said anchoring cable. Disconnection of the anchor cable can cause a break continuity of the cable between said shuttle tank and the ship at the bottom of the sea, and allow a release of the shuttle tank. Disconnection of the cable can be done also at its end anchored on said shell or said tank, allowing a release only partial allowing a rise of a limited distance from the shuttle tank , in particular of sufficient height to warn that the filling of the tank has reached the desired filling ratio corresponding to the said threshold value of traction. said first determined threshold value corresponds to the buoyancy of Archimedes on the tank when it is filled with a predetermined quantity of effluents and, especially preferably when it is completely filled with effluents.

More specifically, in a particular embodiment, said first device automatic disconnection comprises a connecting device preferably comprising a shear pin, and said connecting device provides the connection between two portions of said anchoring cable, and breaks when a traction corresponding to said predetermined threshold value, is exerted on one of the two portions of said anchoring cable.

In another particular embodiment, said first device for automatic disconnection comprises a connecting device, preferably comprising a shear pin, and said connecting device provides the connection between said cable anchor and a first point of attachment on the ship, said disconnection consisting of a breaking of the connection between said anchor cable and said first anchor point, then a partial release of said cable, and finally a new connection between said anchor cable and a second said point of attachment on the ship situated higher than the said first point thus allowing a rise of a distance limited to the distance between the two said attachment points on the ship when a traction corresponding to said threshold value is exerted on said anchor cable at said first attachment point on the ship.

The advantages of this embodiment are explained below. It's about mainly to warn the surface operations manager that the filling of the tank is reached.

In a preferred embodiment, the speed of descent or raising of said shuttle tank with a stabilizing device comprising at least a second cable or connecting chain, extending from the surface, preferably from a surface ship, to a lower part of the tank to which her end is connected, said second cable or said link chain having a portion lower weighted, preferably by blocks arranged in a string along said second cable or larger heavy links of said chain, so that the weight of the length of said lower portion of said cable or pendant chain below said shuttle tank, can be adjusted from the surface, preferably using a winch on board a vessel on the surface and on which the upper end of the cable or chain is unrolled or rolled, so as to control the speed of descent or respectively lift said shuttle tank.

This embodiment is very advantageous because it makes it possible to control mainly the speed of ascent of the shuttle by simply controlling the speed winding the cable or chain on the winch surface. This allows especially to interrupt the recovery of the shuttle tank if the sea is too bad and, in particular, if the swell is too strong on the surface, making it impossible to transfer the tank on board the ship on the surface.

More preferably, said blocks of said second cable or large heavy links of said link chain, in said lower portion of said second cable or chain have a shape such that when one curves said cable or said chain, two blocks adjacent or two adjacent heavy links abut against each other limiting and the local radius of curvature (Ro) of said cable or said chain.

This embodiment is advantageous because it makes it possible to avoid that the lateral wall of the tank does not hit the chain or connecting cable during operations.

Preferably, said shuttle reservoir comprises an additional internal pocket in which the said effluents are recovered, preferably consisting of mesh, able to confine said viscous effluent, said pocket having a opening adapted to cooperate, by reversible connection, with said main opening of the bottom allowing the filling of the shuttle tank.

This embodiment with an internal pocket makes it easier to empty the shuttle tank when it has arrived at its destination at the disposal site and allows to recover the flexible envelope constituting the peripheral wall of the envelope for a new round trip.

In an advantageous embodiment, at the start of step 3 of ascent of the tank, a first closure device allows the automatic closure of said first valve installed in an opening of the shell or tank when said first automatic disconnection device allows at least partial reassembly of said tank.

Preferably this closure of said first valve occurs before the closing of the tank, which can be operated by an operator, especially with an ROV or trigger automatically.

Advantageously, the closure of said first valve by said first closing device automatically triggers closure of said lower opening of the shuttle tank, preferably by said ascent of said tank a distance corresponding where appropriate to the height between the two so-called attachment points on the ship, allowing said partial ascent.

In another advantageous embodiment, closing said lower orifice of said tank is made using a second closure device comprising a cable closure forming a loop surrounding the lower end of said flexible envelope and if necessary of said internal pocket and allowing the tightening of the loop when a traction is exerted on said closure cable, preferably through a slip knot.

More preferably, said first closure device of said first valve comprises a control cable connected at one end to a said second tank closing device and at its other end to a control means closing of said first valve, and said control cable corresponds to preferably said tank closing cable forming a said loop at one end, and said control cable cooperates with a second disconnecting device automatic, the latter to separate said control cable from the said tank, said shell or said tank or to cause the rupture of said control cable after closing said first valve and closing the lower main port of the tank.

It is understood that said disconnection of said control cable occurs when the traction exerted on said control cable at said second device of disconnection reaches a second determined threshold value greater than the value necessary to actuate said control means of closing the said first valve added to that needed to close the tank.

More particularly, a said first automatic disconnection device cooperates with a said anchor cable and a second said disconnecting device automatic cooperates with a said cable closing the reservoir in a coordinated manner such that said closing cable controls the closing of said first valve and the automatic closure of said tank by raising said tank full after said first automatic disconnection of said anchor cable, and said second disconnection of said closure cable allows the complete release and recovery in surface of the shuttle tank.

According to a first variant embodiment, said device for evacuating Effluent is installed through an opening in the shell and / or the tank.

In this preferred embodiment, the shuttle tank is handled by the ROV and is installed directly on the wreck by cooperating the lower orifice of said tank shuttle and the opening created in the hull, in a sealed manner, the various elements, as well that the locking means of said elements being able to withstand the forces created by the global buoyancy of the shuttle tank full of oil, as well as all forces due to the marine currents. In this preferred embodiment, said rigid bottom of the reservoir is advantageously constituted by an open cade, preferably annular, delimiting a said lower main port.

More particularly, said open frame is part of a lower rigid structure frustoconical, a said closing cable of said tank surrounding said flexible envelope and where appropriate, said internal pocket cooperating with said structure less than one where it has a smaller diameter than the diameter of the running part of the cylindrical peripheral wall of a said shuttle tank.

In a particular embodiment, said shuttle tank comprises at the level of from its bottom solid at least a second orifice equipped with a second valve.

This complementary orifice makes it possible to fill seawater with said shuttle tank, once it is secured so as to cooperate with said evacuation device and thus allowing said shuttle tank to pass from its said configuration picked up to its said deployed configuration and subsequently allowing the evacuation of seawater during filling said shuttle tank with said effluent flowing from said device discharge.

According to a second variant embodiment, said evacuation device cooperates with with an upper orifice of a receptacle, said receptacle comprising a lower orifice positioned near and vertically at least one installed second pipe in a said opening in the shell and / or tank so as to recover said polluting effluents flowing from said opening by raising them in said orifice lower of said receptacle.

This second embodiment makes it possible to recover flowing effluents, in particular several openings in said shell.

In this second embodiment, advantageously, said reservoir shuttle includes a rigid bottom full and includes at the level of its said bottom, a second orifice equipped with a second valve.

In this second variant embodiment, a receptacle such as described in FR 2 804 935.

• des seconds moyens d'ancrage dudit réceptacle sur ledit navire ou ladite cuve ou ledit fond de la mer comprenant des seconds câbles reliant des points d'attaches fixés sur la circonférence de ladite grande base de l'entonnoir et des points d'attaches sur le navire ou dite cuve ou dit fond de la mer, et
• des moyens de tensionnement comprenant :
  • des flotteurs (reliés à la circonférence de ladite grande base ouverte dudit réceptacle et autour de la section tubulaire en partie supérieure de ladite petite base dudit entonnoir, et
  • de préférence, des treuils correspondant aux dits points d'attaches sur ledit navire ou dite cuve ou dit fond de la mer.

More particularly, said receptacle has a funnel shape whose large open base constitutes said lower orifice and covers a leakage zone of said effluents, said zone comprising one or more said openings in the hull and / or vessel of the vessel, and the small upper base of said funnel giving access to said upper orifice of said receptacle and said receptacle cooperating with positioning means comprising:

• second means for anchoring said receptacle on said vessel or said vessel or said seabed comprising second cables connecting attachment points fixed on the circumference of said large base of the funnel and points of attachment on the vessel or so-called vessel or said seabed, and
• tensioning means comprising:
  • floats (connected to the circumference of said large open base of said receptacle and around the tubular section in the upper part of said small base of said funnel, and
  • preferably, winches corresponding to said points of attachment on said vessel or said tank or said seabed.

The evacuation device may be installed on an existing opening or pre-drilled opening specially for introducing the evacuation device.

Advantageously, the evacuation device is placed in the upper part of the tank to facilitate the installation of the receptacle above the end of the pipe. However, the use of a pipe allows, if necessary, to install the device on the side walls of the tank to the extent that said pipe can be cleared from the side wall according to the shape that is made to adopt. The skirt peripheral around the lower hole allows to cap, that is to say to cover completely the said end of the pipe from above and to the sides, from in this way, the effluents rise well towards the open inner orifice and can escape.

Said receptacle is kept in suspension near the vertical of the opening through which the effluents flow so as to overcome the geometry of the ship and not be dependent on any instability of the vessel.

All the devices described in the present invention allow the recovery of immiscible or immiscible with seawater and whose density is less than 1 with respect to said seawater.

The technology is particularly applicable to hydrocarbons whose density varies from 0.75 for the lightest, to values close to 1 for the heaviest.

The present invention also relates to the installation useful in a method of recovery of polluting effluents contained in the tanks of a sunken vessel and / or damaged at the bottom of the sea according to the invention, characterized in that comprises a said shuttle reservoir as defined above and, preferably, said anchoring means, as defined above.

Preferably, said installation comprises installing a said device stabilization comprising at least one said second cable or link chain.

More preferably, said installation comprises a said first device of closing and a said first disconnecting device, and if necessary a said second closing device of the tank.

In one embodiment, said installation comprises a said receptacle and if appropriate, said anchoring means and said means for positioning and said tensioning means.

la figure 1 est une coupe en vue de côté de la cuve ou d'une épave 6 sur laquelle est installé un réservoir navette selon l'invention, en cours de remplissage,

la figure 2 est une coupe en vue de côté d'un réservoir navette 2 en position déployée (2B),

la figure 3 est une coupe en vue de côté d'un réservoir navette 2 en position complètement ramassée (2A),

la figure 4 est une coupe en vue de côté d'un réservoir navette 2 en position intermédiaire (2C) entre les positions déployée (2B) et ramassée (2A),

la figure 5 est une vue de côté d'un réservoir navette 2 en cours de remontée vers la surface, à proximité d'un navire de transport à pont submersible 10,

la figure 6 est une vue en plan d'un navire submersible 10 et de son chargement inachevé de 10 réservoirs navettes,

la figure 7 est une coupe en vue de côté d'une épave ou cuve 6 sur laquelle a été installé un réceptacle 20 de captage de fuites, prêt à recevoir un réservoir navette 2,

la figure 10 est une vue de côté d'un réservoir navette stabilisé dans sa remontée par un câble de liaison alourdi par des blocs solidaires de ce dernier et jouant aussi le rôle de limiteur de courbure,

les figures 10a représente le détail de deux blocs en contact, lorsque ledit câble est courbé,

les figures 11 et 12 représentent des états similaires à celui de la figure 10, le réservoir navette étant en phase de remontée sur la figure 11 et en descente sur la figure 12,

la figure 13 représente en coupe en vue de côté un réservoir navette maintenu à la verticale d'une dite première vanne pré-installée sur la coque de l'épave, au moyen d'un câble d'ancrage et d'un premier dispositif de déconnexion automatique,

la figure 13a illustre un exemple de déconnecteur automatique à goupille de cisaillement représenté sur la figure 13,

la figure 14 représente le réservoir navette remontant vers la surface après cisaillement de la goupille, la dite première vanne sur l'épave se fermant alors en premier après déconnexion du câble d'ancrage et avant fermeture de l'orifice inférieur du réservoir,

la figure 15 représente la séquence suivant celle de la figure 14, un câble de fermeture ,à savoir une simple corde, entourant l'extrémité inférieur de l'enveloppe souple du réservoir en passant dans un noeud coulant comme un lasso, ferme de manière quasi-étanche le réservoir navette dans sa partie basse,

la figure 15a est une coupe en vue en plan de dessous selon AA de la figure 15, illustrant le noeud coulant de fermeture de l'ouverture l'enveloppe du réservoir navette,

la figure 16 est une coupe en vue de côté d'un réservoir navette, en cours de remplissage, relié à l'épave par un dit câble d'ancrage coopérant avec un premier déconnecteur automatique à levier et à goupille de cisaillement, et un dit câble de commande de la dite première vanne faisant office de câble de fermeture du dit réservoir à son autre extrémité.

les figures 17a et 17b illustrent respectivement en vue de côté (figure 17a) et en coupe AA de la figure 17a en vue de face (figure 17b), l'accrochage d'une boucle d'extrémité du câble d'ancrage sur le levier du dit premier dispositif de déconnexion, la goupille de cisaillement étant intacte,

les figures 18a et 18b illustrent respectivement en vue de côté (figure 18a) et en coupe AA de la figure 18a en vue de face (figure 18b), lors de la remontée du réservoir navette après cisaillement de la goupille, le déplacement du câble d'ancrage vers un deuxième crochet fixe du bâti du dit premier dispositif de déconnexion automatique.

Other characteristics and advantages of the present invention will emerge more clearly on reading the following description, given in an illustrative and nonlimiting manner, with reference to the appended drawings in which:

FIG. 1 is a sectional view of the vessel or of a wreck 6 on which a shuttle tank according to the invention is being installed during filling,

FIG. 2 is a sectional side view of a shuttle reservoir 2 in the deployed position (2B),

FIG. 3 is a cross-sectional view of a shuttle tank 2 in a completely picked-up position (2A),

FIG. 4 is a sectional view of a shuttle reservoir 2 in the intermediate position (2C) between the deployed (2B) and picked up (2A) positions,

FIG. 5 is a side view of a shuttle tank 2 being raised towards the surface, near a submersible deck transport vessel 10,

FIG. 6 is a plan view of a submersible vessel 10 and its unfinished loading of 10 shuttle tanks,

FIG. 7 is a sectional view of a wreck or tank 6 on which a leak detection receptacle 20 has been installed, ready to receive a shuttle tank 2,

FIG. 10 is a side view of a shuttle tank stabilized in its ascent by a connecting cable weighed by integral blocks of the latter and also acting as a curvature limiter,

FIGS. 10a shows the detail of two blocks in contact, when said cable is bent,

FIGS. 11 and 12 represent states similar to that of FIG. 10, the shuttle reservoir being in the recovery phase in FIG. 11 and in the downward direction in FIG. 12,

FIG. 13 is a sectional view in side view of a shuttle tank maintained vertically of a said first valve pre-installed on the hull of the wreck, by means of an anchoring cable and a first automatic disconnection,

FIG. 13a illustrates an example of an automatic shear pin disconnector shown in FIG. 13,

FIG. 14 represents the shuttle tank going up to the surface after shearing of the pin, said first valve on the wreck then closing first after disconnection of the anchoring cable and before closing of the lower orifice of the tank,

FIG. 15 represents the sequence following that of FIG. 14, a closing cable, namely a simple rope, surrounding the lower end of the flexible envelope of the tank while passing in a noose like a lasso, close in a quasi -seal the shuttle tank in its lower part,

FIG. 15a is a cross-sectional view along AA of FIG. 15, illustrating the closing node of the opening of the envelope of the shuttle reservoir,

FIG. 16 is a side view section of a shuttle tank, being filled, connected to the wreck by a said anchor cable cooperating with a first lever and shear pin automatic disconnector, and a said control cable of said first valve serving as a closing cable of said tank at its other end.

FIGS. 17a and 17b respectively show in side view (FIG. 17a) and in section AA of FIG. 17a in front view (FIG. 17b), the attachment of an end loop of the anchor cable to the lever. said first disconnecting device, the shear pin being intact,

FIGS. 18a and 18b respectively show in side view (FIG. 18a) and in section AA of FIG. 18a in front view (FIG. 18b), during the ascent of the shuttle reservoir after shearing of the pin, the displacement of the cable of FIG. anchoring to a second fixed hook of the frame of said first automatic disconnection device.

In Figure 1, there is shown the hull of a wreck or a wall of tank 6 resting on the bottom of the sea 7 filled with hydrocarbon 1 whose density is less than seawater. The said hydrocarbon is confined in the top of the tank or wreck 6, the lower part is, for its part, filled with water The vessel usually has multiple closed openings hermetically at the deck, leakage may occur as soon as this tightness would be degraded by the deformation or breakage of the hull during the sinking.

Through the hull and / or the wall of the tank 6, an evacuation device 6 ₁ -6 ₄ of the effluents is installed comprising a pipe 6 ₄ equipped with a first valve 6 ₁ and a pipe 6 ₂ equipped with its end of a connecting flange 6 ₃ on which is connected a corresponding flange 5 ₃ integral with a shuttle reservoir 2, at its lower part.

The installation of an evacuation device 6 ₁ -6 ₄ effluents is for example according to the so-called "hot tap" technique, that is to say the hot stitching or charging. This technique is to fix directly on the outside of the tank, for example by welding, a short pipe length 6 ₂ equipped with a full-flow valve 6 ₁ . A special machine, not shown, is then installed in the axis of said pipe is y and sealingly connected. The machine is equipped with a drill which, by means of a tool, will reach the wall of the tank and will pierce a hole there, generally of a diameter corresponding to that of the pipe. At the end of the drilling operation, the drill is cleared, the valve closed and the machine can then be dismantled to be replaced by a pipe ₂ , rigid or flexible which will evacuate the product without any leakage. was generated.

Advantageously, the previously described evacuation device can be lowered onto the wreckage and temporarily stabilized by a dead body, a suction bell device, or a magnetic device, and then when the hole has been drilled, said evacuation device 6 ₁ -6 ₄ is permanently locked by fingers actuated by the ROV, in particular by bearing, from inside the conduit, on the internal face of the hole in the shell and firmly and sealingly plating said device on the wall of the wreck.

The drilling task will be greatly simplified by using, within said device, instead of the drill, a breaking explosive configured in a circle and the axis of fire is directed towards the wall of the wreck, the firing plan being in direct contact with said wall. The shot of the explosive carried out by the ROV realizes in the hull a substantially circular hole of precise size, allowing the transfer of crude oil to the shuttle tank.

Said shuttle reservoir 2 is shown in FIGS. 1 to 4 and consists of a flexible and watertight side wall 4, for example made of high strength reinforced plasticized fabrics, secured in the upper part of a dome 3 with a circular horizontal section and vertical section profile in the form of shells made of a strong and rigid material, preferably of composite material, and integral in the lower part of a bottom 5, flat, solid, resistant and rigid, preferably circular, also preferably of composite material, so as to represent a minimum apparent weight in water, while guaranteeing rigidity and extreme strength. Said bottom 5 is pierced at its center with a main orifice of 5 ₁ and is provided with a valve 5 _2, preferably with full flow, for example of the ball valve, the latter being equipped with a flange 5 _3. A lateral complementary orifice of smaller diameter is provided with a valve ₄ , thus allowing seawater exchanges between the inside of the shuttle tank and the marine environment, and in particular when filling the tank with oil, to sea water to escape.

The dome 3 and the bottom 5 may have a diameter of 5 to 10 m, the dome 3 a height of 2 to 5 m and the side wall 4, once unfolded, a height of 10 at 50 m.

Depending on the viscosity of the oil to be recovered, it may be necessary to consider large diameters for the main orifice 5 ₁ and its associated valve ₂ , for example 10 to 24 "or more, and one or more complementary orifices of 1 to 4 "provided with valves 5 ₄ of corresponding diameter.

The shuttle tank 2 is shown in the extended position (2B) in FIG. 2, the main valve ₂ having an integral passage being in the open position.

FIG. 3 is a sectional view in side view of the shuttle tank 2 in the final phase of preparation before use, that is to say before it is launched and its descent towards the wreck or tank. because of the flexibility of the side wall 4, creating a plurality of folds 4 ₁ Apportionment on the periphery, which reduces the shuttle tank length by bringing the base 5 of the dome 3. After pleating 4 ₁ initiates, as detailed in FIG. 4, the bottom 5 and the dome 3 are brought as close as possible to obtain a shuttle reservoir 2 in the picked-up position (2A), thus occupying a minimum of volume, which presents a considerable advantage for its handling, for its descent to the wreck or tank 6 and for its implementation on the evacuation devices 6 ₁ -6 ₄ which have been prepared on the hull of said wreck or wall of said vessel 6. In the picked up position (2A) such that detailed in FIG. 3, the shuttle tank 2 is firmly held by straps 7 connecting the bottom 5 and the dome 3 each equipped with hooks 7 ₁ at their periphery.

Is advantageously adjusts the apparent weight in water of the shuttle reservoir 2 by incorporating into the uppermost portion of the dome 3, the buoyancy, e.g., syntactic foam 3 ₁ consisting of glass microspheres embedded in epoxy resins, polyurethane or others.

Thus, the shuttle tank 2 is lowered to the wreck or tank 6 in the picked up position (2A), and has an apparent weight in the water very low and which can be adjusted in positive as in negative, which facilitates its installation directly by an ROV 30 (automatic submarine piloted from the surface and equipped with manipulator arms). Thus, the ROV manipulates the shuttle tank so as to match the flange 5 ₃ secured to the lower orifice of 5 ₁ of the bottom 5 of said shuttle tank 2, and the flange 6 _{3 The} correspondent said discharge device installed on the shell of wreck or tank wall 6, then the two flanges 5 ₃ and 6 ₃ are locked together to ensure the tightness of the connection.

In a first embodiment of the method of the invention, the shuttle tank 2 is positioned by the ROV near the wreck and above the evacuation device 6 ₁ -6 ₄ using cables 12 ₁ from winches 14 ₁ installed on the hull or wall of the tank 6 or close, and connected to the attachment lugs 13 ₁ secured to the bottom 5 of said shuttle tank 2. By acting on the winches 14 ₁ , the shuttle tank 2 of its connection point constituted by the fixed flange 6 ₃ installed on the hull of the wreck or tank wall 6, then the two flanges ₃ , 6 _{3 are} locked with the aid of the ROV.

When the connection is complete, the ROV releases the straps 7 which hold the shuttle reservoir 2 in the picked up position (2A), then the lateral complementary orifice provided with a valve ₄ is open, thus allowing water to enter, which leads to the deployed position (2B) described in Figures 1 and 2.

The main valve 5 ₁ integral passage integral with the bottom 5 of the shuttle tank 2 is then open, like the valve 6 ₁ of the discharge device located on the hull of the wreck or tank wall 6, which by simple effect of difference in density between the oil 1 and the seawater, transfers said oil 1 upwards, ie performs the complete filling of said shuttle tank. During filling, the corresponding volume of seawater escapes through the lateral complementary orifice 5 ₄ .

At the end of filling, the two valves 5 ₂ and 5 ₄ of the bottom 5 are closed, the two flanges 5 ₃ and 6 ₃ are released and the shuttle tank 2 full then has a positive buoyancy, which allows its transfer to the surface. Advantageously, allowed to shuttle tank 2 rise naturally to the surface, because the forming shell of the dome 3, combined with the buoyancy created by the syntactic foam 3 ₁ Integrated the dome 3 and the weight of the bottom 5, comprising in particular the flange 5 ₃ connection and the main ball valve 5 ₂ , shifts up the center of buoyancy and downwards the apparent center of gravity in the water, which allows the shuttle tank 2 to keep throughout the ascent substantially straight and vertical trajectory, as shown in Figure 5. The shuttle reservoir 2 arriving at the surface 11, naturally floats and can be towed, then directed to a storage vessel 10, preferably a submersible bridge vessel. Such a submersible deck vessel allows ballast to maintain the main deck under several meters of water, thus allowing the packages to be transported by floatation, then deballasting out the deck of water and carry the transport "dry" parcels. Such vessels are available from many shipowners; for example Mamoeth (Holland).

Because the shuttle reservoir 2 is completely free and uncontrollable, it can surface at any point in the area of operations, and to avoid any incident, we advantageously equip the dome of the shuttle tank of a acoustic transponder so that it can be located during the entire said shuttle tank and thus avoid any collision, by moving the where appropriate, the various vessels operating on the surface.

By thus loading the ships, as detailed on the Figures 5 and 6, it is never necessary to lift the load directly than represents the filled shuttle tank 2, load which can be considerable and can to reach 200 to 300 tons for a shuttle tank 2 of diameter 5 m and 15 m length.

As detailed in Figure 6, the shuttle tanks 2 are advantageously stored side by side on simple supports and thus secured with the deck of the carrier vessel 10. The vessel 10, when loaded, is deballasted, then directed to a port where it is reballasted to make the transfer shuttle tank to recovery units. Once released, the ship returns to site for a new load.

In the port area equipped for the final recovery, the shuttle tanks 2 are maintained in buoyancy and preferably conducted in an isolated retention pond, to be emptied of their contents, to avoid any pollution of the environment. The emptying is advantageously carried out horizontally, the shuttle tank 2 being always floating, by connecting, on the flange 5 ₃ secured to the bottom 5 of the shuttle tank 2, a pipe, preferably flexible, connected to a pumping system. The recovered oil being generally extremely viscous, it facilitates the emptying by creating a reheating of the area near the outlet orifice 5 ₁ of the shuttle reservoir 2, for example by injecting a hot fluid through the lateral complementary orifice 5 ₄ , said hot fluid is preferably crude oil heated to high temperature, that is to say at 80 to 100 ° C, which allows to fluidize the viscous oil located near the outlet. When the shuttle tank 2 has been almost emptied, it can then be placed in a vertical position, still within the retention basin, to complete its emptying and rinsing with warmed crude oil. Once the emptying is complete, the shuttle tank 2 is in the intermediate position (2C) as shown in Figure 3, then it is picked up (2A) as shown in Figure 4 and the assembly is firmly held by straps 7 connecting the bottom 5 and the dome 3. The shuttle tank 2 is again ready to be forwarded on site for a new filling cycle.

a) un réceptacle 20 consistant en une cloche en forme d'entonnoir dont la grande base ouverte constitue un orifice inférieur 19 et couvre une zone de fuite desdits effluents, ladite zone comprenant une ou plusieurs ouvertures 6₄ dans la coque et/ou la cuve 6 dudit navire, et la petite base supérieure dudit entonnoir donne accès à un orifice supérieur 18, équipé d'un dispositif d'évacuation 6₁-6₃, et

b) desdits moyens de positionnement comprenant :

• des moyens d'ancrage dudit réceptacle 20 sur le navire comprenant des câbles 12₂ reliant des points d'attache 13₂ fixés sur la circonférence de ladite grande base de l'entonnoir et des points d'attache 14₂ ou des corps morts existants ou installés sur le navire, ou à proximité dudit navire sur le fond de la mer et
• des moyens de tensionnement comprenant :
  • des flotteurs 15, 16 reliés à la circonférence de ladite grande base ouverte dudit réceptacle et autour de la section tubulaire 17 en partie supérieure de la petite base dudit entonnoir, et
  • des treuils 14₂ correspondants aux dits points d'attache sur le navire,

de manière à maintenir ledit réceptacle 20 en tension et en suspension à proximité et à la verticale desdites ouvertures 6₄.de la coque ou cuve 6.FIG. 7 shows an alternative embodiment of an installation according to the present invention in which the shuttle reservoir 2 cooperates with an evacuation device 6 ₁ -6 ₃ installed at the top of a receptacle 20 as described in FIG. FR 2 804 935. More particularly, the installation comprises:

a) a receptacle 20 consisting of a funnel-shaped bell whose large open base constitutes a lower orifice 19 and covers a leakage zone of said effluents, said zone comprising one or more openings 6 ₄ in the shell and / or the tank 6 of said vessel, and the small upper base of said funnel gives access to an upper orifice 18, equipped with an evacuation device 6 ₁ -6 ₃ , and

b) said positioning means comprising:

• anchoring means of said receptacle 20 on the vessel comprising cables 12 ₂ connecting attachment points 13 ₂ fixed on the circumference of said large base of the funnel and attachment points 14 ₂ or existing dead bodies or installed on or near the vessel on the seabed and
• tensioning means comprising:
  • floats 15, 16 connected to the circumference of said large open base of said receptacle and around the tubular section 17 in the upper part of the small base of said funnel, and
  • winches 14 ₂ corresponding to said attachment points on the ship,

so as to maintain said receptacle 20 in tension and in suspension near and vertically said openings 6 ₄ .the hull or tank 6.

Said receptacle 20 is in the form of an inverted umbrella or a funnel of circular or trapezoidal section that covers the entire area comprising several openings emitting polluting effluents.

The size of the funnel of the receptacle 20 may correspond to a diameter of about 25 to 50 m or more, and a height of about 25 to 50 m also. It consists of a rigid armature associated with a flexible membrane or a rigid structure in the form of a funnel whose upper part 17 is equipped with a discharge device 6 ₁ -6 ₃ comprising a valve 6 ₁ with a pipe 6 ₂ equipped at its upper part with a flange 6 ₃ cooperating with a corresponding flange 5 ₃ of the bottom 5 of the shuttle tank 2.

The bell 20 is held in position by a set of cables 12 ₂ connected, on the one hand, to a fastener 13 ₂ integral with the bell and, on the other hand, to a winch 14 ₂ on the tank or wreck 6 These cables, preferably 3 cables, are installed to form a pyramid, preferably equilateral triangular base. Thus, the position of said bell can be adjusted and maintained closer to the wreck, for example 50 cm or 1 m, so that the lower end of the large open base of the funnel which constitutes the peripheral skirt defining the lower opening 19 of said receptacle 20 can cover a complementary discharge device comprising a pipe 6 ₄ valve 6 ₅ installed in the wall of the vessel or wreck 6 as shown in Figure 7, and so to avoid that pollution is carried away by the current and then escapes the collector that constitutes the bell. In the event that the wreckage rests horizontally on the bottom, the entire system of conduits of the ship will interfere with the bell which can not be installed closer, but by adjusting, by means of the winches 14 ₂ , the lengths of the cables 12 ₂ . Said bell 20 will be maintained in a position to optimize the recovery effect. The winches 14 ₂ can be installed either on the wreck or on the bell or on dead bodies placed on said wreck or located in the immediate vicinity of the wreck.

Said receptacle 20 is made floating by means such as buoys 15, 16 in syntactic material resistant to bottom pressure or buoys hollow materials, such as plastics, steel or materials composites.

The receptacle is held in position by means of a peripheral float 16 surrounding the tubular upper part of the funnel and a series of floats 15 connected to the circumference of the large base of the funnel in its lower part.

Said receptacle 20 comprises means 21 for heating said effluents pollutants 1 to make them less viscous and thermal insulation means of its outer wall 22.

Indeed, in the case of light products, so low viscosity, the difference in density of the product relative to the seawater is sufficient for the product transfer upward is done naturally. On the other hand, since the product has a density close to 1 and a high viscosity, or has a tendency to congeal in the form of paraffin, an additional heating system 6 ₆ is advantageously installed in the capture zone 6 ₄ , as well as than in the upper part of the bell 20, the outside of said bell being preferably protected by a thermal insulation 22.

An assistance ship 31 provides the power necessary for reheating and the operation of the ROV 30 via an umbilical 32, as explained in Figure 7.

Preferably, as shown in the patent application FR 2 804 935, the attachment points on the wreck or tank 6 and in particular the winches 14 ₁ and 14 ₂ are advantageously fixed to the wreckage using a suction box comprising an open face at the interface with the wreck and which cooperates with the latter by a peripheral seal and a suction pipe for evacuating the inside of the box. Indeed, if out of water, such a device allows with a high vacuum, about -1 bar, to obtain a holding force of 10 t / m ² of surface at the joint plane, by depths of 100 m, the pressure difference between the vacuum and the ambient pressure will be 11 bar and the same surface will then allow a holding force of 110 tons for the area of 1 m ² .

The pipe may be in communication with a pump installed on the ROV is replaced by a pump attached to the suction box and powered by said ROV or directly from the surface assistance vessel.

In a preferred version shown in FIGS. 8 and 9, the shuttle reservoir 2 comprises a removable bottom 5 connected, for example by means of not shown bolts, to a peripheral flange ₅ secured to the lower end of the flexible side wall 4 Inside the shuttle reservoir 2, an internal bag 2 ₁ is advantageously installed, constituting, by itself, a second flexible envelope of similar or even slightly smaller dimensions than the outer envelope constituted by the entire dome 3. of the flexible side wall 4 and the bottom 5 of the shuttle reservoir 2. Said bag 2 ₁ consists of a fine mesh having a single opening downwards, the latter cooperating with a portion of conduit 5 ₆ continuity from the main opening 5 ₁ of the bottom 5 of the shuttle tank 2 inwards. Said second envelope or inner bag 2 ₁ is secured to said pipe portion 5 ₆ by a strap 5 ₇ . Thus, when filling the shuttle tank 2 with a crude oil 1 with very high viscosity, the entire product is stored inside the pocket 2 ₁ and remains confined there because of the small mesh size and the viscosity considerable intrinsic value of crude oil. When the shuttle tanks 2 have been unloaded in the salvage port site, each of the shuttle tanks is towed horizontally in the retention basin, then, still in a horizontal position, a ring 3 ₂ integral with the dome 3 is connected to a mooring point 9 secured to the edge of the basin; the fixing bolts, or the bolts of the flange 5 ₅ , connecting the flexible side wall 4 and the bottom 5 of the shuttle reservoir 2, are then released, then the entire bottom 5, secured to the inner pocket 2 ₁ , and dome 3, secured to the side wall 4, constituting an outer envelope, are separated over a few meters.

A link realized with a single rope is tightened around the orifice of the lower bag 2 ₁ at the plane A, passing through eyelets 5 _8, and then securely tightened so as to close, in leaktight manner, the pocket. The bag 2 ₁ is then separated from the bottom 5 of the shuttle tank 2 by releasing the strap ₇ , and said bottom 5 is removed. The pocket 2 ₁ is then extracted completely from the shuttle reservoir 2.

The shuttle tank is then released and, after relocation of an inner bag 2 ₁ new, cinched 5 ₇ of the bottom 5 of said shuttle reservoir 2, the latter is re-assembled by bolts on an outer casing, consisting of the dome 3 integral with the flexible side wall 4, and the assembly is then ready to be put in the picked up position (2A) as explained in FIGS. 3 and 4.

The pocket 2 ₁ once extracted, floats within the retention basin. It is then directed, still floating, to a cradle, which will then be extracted from the basin using a high capacity crane, to be transferred, after draining the residual water, to a second retention basin where the bag will be unloaded for preparation, either to be eliminated or to be treated for reuse of some of its constituents.

FIG. 10 illustrates a preferred version of the invention, in which the raising of the shuttle tank is controlled by a connecting cable 30, a portion of which of its lower part is weighed down, for example, by metal blocks 31 secured to said cable 30 by a crimping 31 ₁ in strand like beads on a cable.

These beads 31 have a cylindrical central body which is prismatic or of revolution and, frustoconical ends such as when the cable is bent, said frustoconical ends of the two adjacent beads then abut one against the other at 31 ₂ , limiting and the local radius of curvature to a value greater than R ₀ . Thus, the connecting cable 30 being hooked to the shuttle reservoir 2 on the said first attachment point 32 in the lower part of the tank, descends downwards and then deviates in an arc of radius R ₀ , to finally rise vertically or in the chain configuration at a distance of at least 2R ₀ from the side wall 4 of said shuttle reservoir, thereby avoiding any mechanical contact during the ascent, which avoids damage by friction.

In FIG. 10, the buoyancy of the hydrocarbon filled shuttle tank F _v , which corresponds to the buoyancy force acting on the tank and its cargo, is compensated by the weight of the cable up to the corresponding horizontal tangency point. to the bead 31 _i , added the weight of the beads 31g between the reservoir and the bead 31i the lowest, that is to say 8.5 beads in Figure 10, the weight of the set P _e then corresponding to a balance of the system .

By way of example to illustrate FIGS. 10, 13 and 16, the shuttle tank with a volume of 250 cubic meters of a petroleum having a density of 1011 kg / m ³ , in seawater at 3 ° C. of density 1045 kg / m ³ , has a buoyancy of about 8.5 tons.

Each of the beads of the balancing device 30-31 then has a weight in the water about 1 ton.

In FIG. 11, the upper end of the connecting cable 30, connected to a winch installed on board a surface vessel (not shown), is raised, which has the effect of bringing the bead 31 _g of FIG. 10 in low horizontal position, thereby reducing the number of beads weighing under the 6.5-pearl reservoir, the overall weight opposing the thrust Fv being reduced to P _inf . The resultant F _v + P _inf is then positive upwards and the shuttle reservoir can go up until the equilibrium of the forces of FIG. 10 is reached.

Likewise, in FIG. 12, the upper end of the connecting cable 30 is deviated, which has the effect of bringing the bead 31 _k into a low horizontal position, thereby increasing the number of beads weighing under the reservoir. 10.5 beads, the overall weight then being equal to P _sup . The resultant F _v + P _sup is then positive downwards and the shuttle reservoir can go down again until the balance of the forces of FIG. 10 is reached.

Thus, the stabilization device according to the invention has a stabilizing effect for the recovery of the shuttle tank. When the surface vessel moves excessively under the effect of the swell or deviates from the vertical position of the shuttle tank, the movements have instant effect only on the area of the beads surrounding the beads 31 _g at 31 _k , the bead 31 _i corresponding to the average value of the oscillations.

Thus, to control the raising of the shuttle tank 2, it is sufficient to wind the cable connecting the winch on board the surface vessel 31 at a speed compatible with the natural rise of said shuttle, said shuttle always seeking naturally to resuming its equilibrium position illustrated in Figure 10. In case of difficulties, it suffices to slow down or stop the winding on the winch, the shuttle tank then finding almost immediately its equilibrium position, pending a new movement of the winch.

FIG. 13 shows the sectional view from the side of a shuttle tank 2 installed vertically of a said duct 6 ₄ equipped with a first valve 6 ₁ secured to the wreck, said first valve being in the open position and letting the crude oil that is collected in the shuttle tank.

In FIGS. 13 to 18, the bottom of the reservoir comprises an annular open frame delimiting a said lower main orifice 5 ₁ .

The lower part of the envelope of the shuttle tank is held in shape by a rigid lower structure 51d forming a double cone 50a - 50b maintained in shape arranged under the bottom of the tank, constituted by circular stiffeners 51 _a - 51 _b - 51 _c connected by a lattice structure 51d, not shown in Figure 13, but shown in Figure 15. The shuttle tank is maintained above the wreckage by means of an anchoring cable 52-52 ₁ integral with the wreckage in a said second anchoring point 54 and at its upper part, a said first automatic load-limiting disconnection device 53 itself connected to the shuttle reservoir via a crow's foot 52-52 ₂

The load limiter device 53 is illustrated at 13a and comprises a lower yoke 53 ₁ connected to an upper bar 53 ₂ to which is connected, by means of a shear pin 53 ₃ of known limit load. Thus, during the loading of the shuttle tank, the buoyancy of the assembly will increase until reaching the maximum value F _v , value corresponding to the limit of resistance of the pin 53 ₃ , which breaks, will release the shuttle tank which will begin then are ascension.

During installation, a control cable 56.56.1 was advantageously connected to a lever arm 57 controlling the closing operation of said first valve 6 ₁ , the upper part of the cable is secured to the structure of the shuttle tank. Thus, at the beginning of the raising of the shuttle tank, the cable 56, 56 ₁ actuates the lever 57 and thus closes the valve 6 ₁ , as illustrated in FIG.

The upper portion 56 ₂ of the cable 56 is advantageously connected to the outer casing by a loop 58 surrounding said casing and passing through a loose looper node located in the plane AA of Figure 15, thus acting as a closure cable for the lower main port of the tank.

In Figure 15 the shuttle tank being ascended pulls on the cable of closing 56,56.2 which has the effect of tightening the loop 58 thanks to the noose, this which simply closes the lower orifice 5.1 of the shuttle tank due to the flexibility of the fabric, as shown in Figure 15a which is a section for below according to the AA plan. A wheel 59 equipped with a non-return device, no shown, prevents the noose, once firmly tightened, from loosening.

• en fin de remplissage, la goupille à cisaillement 53₃ se rompt, libérant le réservoir navette qui remonte alors naturellement,
• le câble de commande 56,56.1 actionne le levier 57, lequel ferme la dite première vanne 6₁ ,
• la boucle 58 à travers le noeud coulant se resserre, obstruant ainsi l'orifice inférieur du réservoir navette, et
• en fin de cycle, un deuxième dispositif de déconnexion automatique 60₉, par exemple à goupille de cisaillement similaire au dispositif 53 décrit précédemment, libère de manière définitive le réservoir navette qui commence alors son ascension vers la surface.

Thus the fully automated closing sequence comprises the following steps:

• at the end of filling, the shear pin 53 ₃ breaks, releasing the shuttle reservoir which then naturally rises,
• the control cable 56,56.1 actuates the lever 57, which closes said first valve 6 ₁ ,
• the loop 58 through the noose tightens, thus obstructing the lower orifice of the shuttle reservoir, and
• at the end of the cycle, a second automatic disconnection device 60 ₉ , for example a shear pin similar to the device 53 described above, finally releases the shuttle reservoir which then begins its ascent to the surface.

The shearing of the pin of said first automatic disconnection device 53 will then be adjusted to a value of about 8.5 tonnes.

Assuming a force of 100 kg required to actuate closing of the valve, and a force of 1 ton to close the noose, the second disconnection 60 will advantageously be adjusted to a said second threshold value traction 1.5 tonnes, ie more than 1 tonne but less than 8.5 tonnes, so that what the previously described sequences take place automatically in the order indicated.

In FIGS. 13 to 15, said rigid lower structure 51 d forms a double truncated cone 50a, 50b formed of two upper conical trunks 50b and lower 50a, respectively flared upwardly and downwardly, joined by their small base common at an intermediate circular frame 51b of said rigid lower structure, so that said closure loop 58 which surrounds the lower end of the flexible envelope 4 or said pocket 2 ₁ , must travel a reduced race to close the l main lower hole of the tank.

In a simplified version shown in FIGS. 16, 17 and 18, the lower end of the reservoir comprises an annular open frame 51.b delimiting the lower main opening 5 ₁ of the reservoir and to which the lower end of the envelope is connected. flexible constituting the lateral peripheral wall of the reservoir and the lower end of the inner bag 2 ₁ . In this simplified version the installation comprises a said first automatic disconnection device consists of a frame 54 secured to the wreck 6 serving as said second attachment point, having at its lower part a first hook constituting a first point attachment 54 ₁ and in its upper part a second hook constituting a second attachment point 54 ₂ located at a height of 0.5 to 1m above the first hook. Said first hook 54 ₁ is located at the end of a second lever 53 _5, hinged in 53 _6, 53 ₅ said lever being maintained in a substantially horizontal position by a shear pin 53 ₄ making it integral with the frame 54. The lower end of the anchoring cable 52 forms a loop engaged in said first hook 54 ₁ located on the underside, at the end of the lever 53 ₅ , and envelops the upper part of the frame 54 in the area of the second hook 54 ₂ , as explained in Figures 17a and 17b. Thus, when the shuttle reservoir is almost full, the vertical thrust due to the crude oil, reaches said first resistance limit value of the pin 54 ₃ , which shears and releases the retaining cable 52, by simply rotating the lever 53 ₅ on its axis 53 ₆ . The shuttle tank then rises from a height of 0.5 to 1 m, and the cable 52 is found retained in the second hook 54 ₂ , as shown in Figures 18a and 18b.

In FIG. 16, the valve 6 ₁ is in the open position, but as soon as the shuttle reservoir is released by breaking the shear pin 53 ₄ , the upward movement of the shuttle closes said first valve by means of the control and closure cable 56 integral with the lever 57 for controlling said first valve. The shuttle tank is then waiting in the safety position of FIG. 18 retained by the first hook 54 ₁ . Closing of the bag 2 ₁ is achieved by clamping the loop 58 in the noose as previously explained in FIG. 15, by means of a small winch 62 secured to the shuttle tank 2, said winch being actuated by the ROV 30. Finally, the manipulator arm of the ROV, equipped with a shear, cuts off the control and closing cable 56, as well as the anchoring cable 52, which has the effect of completely releasing the shuttle reservoir which can then be wound up to the surface. thanks to the weighted chain 30-31.

In some cases, it is advantageous to limit the automation to the disconnection system as previously described. Indeed, once the shuttle tank almost full, the pin 53 ₄ is sheared and the shuttle tank is found waiting, always open, in the position shown in Figures 18a and 18b. The operator at the surface is thus warned (via a camera embedded in the ROV) of the end of the filling and under the control of said video camera of the remote controlled underwater vehicle (ROV), it is then easy to let him fill to the maximum before closing the valve is performed by said ROV. The automatic disconnection system then plays only a role of filling control system of the shuttle tank, most of the final control, closing and release of the shuttle tank being performed directly by said ROV 30.

Automatic disconnect devices 53 having a shear pin, but it remains in the spirit of the invention to consider systems, load-sensing systems, either based on compression of a spring, on an electronic or hydraulic component giving a proportional response to the load applied and triggering the release of the retaining cable 52.

Similarly, it remains in the spirit of the invention if only part of the sequence described above is performed automatically, the other sequences being conventionally made using the ROV, for example, the clamping of the noose and the final release of the shuttle tank.

In all the descriptions of the figures of the invention, the valve 6 ₁ installed on the integral orifice of the shell of the wreck is a ball valve, but it remains in the spirit of the invention considering any other Valve type, such as guillotine valves, diaphragm valves, or other devices to prevent crude oil from escaping the shell in an uncontrolled manner.

The operating means of said valve has been described as being a lever arm 57, but it remains in the spirit of the invention using cable systems, pulley or screw, or rack systems, for closing said valve 6 ₁ .

Claims (28)

1. A method of recovering polluting effluent (1) that is lighter than water and contained in a tank (6) of a sunken and/or damaged ship resting on the sea bed (7), in which:

   a) an effluent evacuation device (6₁-6₄), preferably having at least one pipe (6₂-6₄) and a first valve (6₁) is installed to co-operate with an opening in the hull and/or the tank (6) in such a manner as to be capable of recovering said polluting effluent (1) flowing through said opening and rising to said evacuation device (6₁-6₄); and

   b) said effluent (1) flowing from said opening (6₄) in the hull and/or the tank (6) is recovered;

      the method being characterized in that in step b), said effluent is recovered using a shuttle reservoir (2) capable of taking up a compact configuration (2A) and a deployed configuration (2B), said shuttle reservoir (2) having at least one main bottom orifice (5₁) suitable for co-operating with said evacuation device (6₁-6₄) so as to perform the following steps:

   1) lowering said shuttle reservoir (2) from the surface (11) to the sea bed (7), preferably while in its said compact position (2A), and causing said bottom orifice (5₁) of the shuttle reservoir (2) to co-operate with said evacuation device (6₁-6₄);

   2) filling said shuttle reservoir (2) with effluent, and once filled with effluent (1) in its said deployed configuration (2B), closing it to make it leakproof;

   3) allowing said shuttle reservoir (2) to rise to the surface, once full, in its deployed configuration (2B), said shuttle reservoir (2) preferably including buoyancy elements (3₁);

   4) preferably, storing said reservoir filled with effluent (1) in a ship (10) on the surface and emptying said shuttle reservoir (2) in said ship (10) or transporting it to a site for emptying; and

   5) where appropriate, repeating steps 1 to 4 with the same shuttle reservoir (2) or with another shuttle reservoir (2) until the desired quantity of effluent (1) has been recovered.
2. A method according to claim 1, characterized in that said shuttle reservoir (2) comprises:

   a) a rigid dome (3) having an open circular base, preferably having a profile in vertical section that is bullet-shaped;

   b) a rigid bottom (5) of periphery that is preferably circular; and

   c) a peripheral side wall (4) constituting a flexible envelope for connecting said base of the dome (3) to the periphery of said bottom (5) in such a manner that:

   said peripheral side wall (4) can be folded concertina-like to allow said dome (3) and said bottom (5) to be moved towards each other, preferably by means of removable straps (7), said shuttle reservoir (2) then being in said compact position (2A); and

   said effluent (1) being capable of being confined inside said shuttle reservoir (2) when said side wall (4) is unfolded, said shuttle reservoir (2) then being in said deployed position (2B).
3. A method according to claim 1 or claim 2, characterized in that said buoyancy elements (3₁) of said shuttle reservoir (2) are integrated inside said dome (3), said buoyancy elements (3₁) preferably consisting in syntactic foam.
4. A method according to claim 2, characterized in that said buoyancy elements (3₁) are integrated inside the top portion of said dome (3) so that the center of flotation of said shuttle reservoir (2) filled with effluent (1) is offset upwards relative to its apparent center of gravity in water.
5. A method according to any one of claims 1 to 4, characterized in that said shuttle reservoir (2) full of effluent (1), once raised to the surface, is transferred by being floated into a ship with a submersible deck (10) without it being necessary to hoist it.
6. A method according to any one of claims 1 to 5, characterized in that said shuttle reservoir (2) is maintained close to said effluent evacuation device (6₁-6₄) using anchor means (12₁-13₁-14₁, 52-54) comprising at least one anchor cable (52, 52₁-52₂) interconnecting at least one first attachment point (13₁, 55) located in the bottom portion of the reservoir close to said bottom (5), preferably on the periphery of said bottom (5) of the shuttle reservoir, and at least one second attachment point (14₁, 54, 54₁-54₂) on the sunken ship (6) or on the sea bed (7), serving to anchor said shuttle reservoir to said sunken ship (6) or the sea bed (7).
7. A method according to claim 6, characterized in that prior to step 3) of raising the shuttle reservoir, an automatic disconnection step is performed from said anchor means, which step takes place automatically when the shuttle reservoir reaches a predetermined filling factor, in particular when the reservoir is full or nearly full.
8. A method according to claim 7, characterized in that at least one said anchor cable (52) co-operates with a first automatic disconnection device (53, 53₁-53₃, 53₄-53₆) on which traction corresponding to the buoyancy thrust acting on said shuttle reservoir and its cargo acts, which traction is transmitted by said anchor cable (52), said disconnection device (53, 53₁-53₃, 53₄-53₆) having the effect of causing said anchor cable to disconnect by separating said anchor cable from said reservoir or from said ship at the sea bed or by rupturing said anchor cable, and allowing said shuttle reservoir to rise at least in part when said traction reaches a first determined threshold value, preferably when said shuttle reservoir is full of effluent (1).
9. A method according to claim 8, characterized in that said first automatic disconnection device comprises a connection device (53₁-53₃) preferably comprising a shear pin (53₁), and said connection device interconnects two portions of said anchor cable, and breaks when traction corresponding to said predetermined threshold value acts on one of the two portions of said anchor cable (52).
10. A method according to claim 8, characterized in that said first automatic disconnection device (53) comprises a connection device (53₄-53₆) preferably comprising a shear pin (53₄), and said connection device provides the connection between said anchor cable and a first attachment point on the ship (54₁), said disconnection consisting in breaking the connection between said anchor cable and said first attachment point, followed by partial release of said cable, and finally a new connection between said attachment cable and a second anchor point on the hull or the tank (54₂) situated higher than said first attachment point (54₂), thus enabling the reservoir to rise through a distance restricted to the distance between the two attachment points (54₁-54₂) on the ship when traction corresponding to said threshold value acts on said anchor cable at said first attachment point (54₁) on the ship.
11. A method according to any one of claims 1 to 10, characterized in that the speed of descent or of ascent of said shuttle reservoir is controlled with a stabilization device comprising at least one second connection cable chain (30) extending from the surface (11), preferably from a ship (10) on the surface, to a low portion of the reservoir (51a, 51b) to which its end is connected, said second connection cable or chain having a bottom portion that is weighted, preferably by means of a string of blocks (31) disposed along said second cable or by said chain being made of large heavy links, such that the weight of the length of said bottom portion of said cable or chain hanging under said shuttle reservoir can be adjusted from the surface, preferably by means of a winch situated on board a ship on the surface with the top end of said cable or said chain being wound on and off the winch, in such a manner as to control the speed at which said shuttle reservoir (2) descends or ascends.
12. A method according to claim 11, characterized in that said blocks (31) of said second cable or said large heavy links of said connection chain, in said bottom portion of said cable or chain present a shape such that when said cable or said chain is curved, two adjacent blocks or two adjacent heavy links come into abutment against each other (31₂), thereby limiting the local radius of curvature (R₀) of said cable or of said chain.
13. A method according to any one of claims 1 to 12, characterized in that said shuttle reservoir (2) includes an additional flexible internal bag (2₁) in which said effluent is recovered, preferably constituted by a fine-mesh net, suitable for confining said viscous effluent, said bag having an opening suitable for co-operating via a reversible connection with said main orifice (5₁) in the bottom (5) enabling the shuttle reservoir (2) to be filled.
14. A method according to any one of claims 7 to 13, characterized in that on beginning step 3) of raising the reservoir, a first closure device (56-57) enables said first valve (6₁) installed in an opening of the hull or tank to be closed automatically when a said first automatic disconnection device allows said reservoir to rise, at least a little.
15. A method according to claim 14, characterized in that the closure of said first valve by said first closure device automatically triggers the closure of said bottom orifice (5₁) of the shuttle reservoir, preferably by said reservoir rising through a distance corresponding, where appropriate, to the height between the two attachment points on the ship, thereby enabling it to rise a little.
16. A method according to any one of claims 1 to 15, characterized in that the closing of said main bottom orifice of said reservoir is performed by a second closure device (56-58-59) comprising a closure cable (56₂) forming a loop (58) surrounding the bottom end of said flexible envelope (4), and where appropriate of said internal bag (2₁), and enabling the loop to be tightened (59) when traction is exerted on said closure cable, preferably by means of a slip knot.
17. A method according to claim 15 or claim 16, characterized in that said first closure device of said first valve comprises a control cable (56, 56₁) connected via one end to a said second closure device of the reservoir and via its other end to means (57) for controlling closure of said first valve (6₁), and said control cable preferably corresponds to said closure cable (56, 56₂) of the reservoir forming a said loop at one end, and said control cable (56, 56₁) co-operates with a second automatic disconnection device (60), enabling said control cable to be separated from said reservoir, said hull, or said tank, or serving to cause said control cable to break after said first valve has been closed and the main bottom orifice of the reservoir has been closed.
18. A method according to any one of claims 7 to 10 and claim 17, characterized in that a said first automatic disconnection device (54) co-operates with a said anchor cable (52), and a said second automatic disconnection device (60) co-operates with a said reservoir closure cable (56, 56₂) in coordinated manner so that said closure cable causes said first valve to close and causes said reservoir to close automatically by said full reservoir rising after said first automatic disconnection (53) of said anchor cable (52), and said second disconnection (60) of said closure cable (56) enables the shuttle reservoir to be fully released and to rise to the surface.
19. A method according to any one of claims 1 to 18, characterized in that said effluent evacuation device (6₁-6₄) is installed via an opening in the hull and/or the tank (6).
20. A method according to any one of claims 1 to 19, characterized in that said rigid bottom (5) of the reservoir is constituted by an open frame (51a, 51c) that is preferably annular, defining a said bottom orifice (5₁).
21. A method according to any one of claims 16 to 20, characterized in that said open frame (51a) forms a portion of a rigid bottom frustoconical structure (51a-51d), a said closure cable of said reservoir surrounding said flexible envelope and where appropriate said internal bag by co-operating with said bottom structure at a level where it presents a diameter that is smaller than the diameter of the main portion of the cylindrical side wall of a said shuttle reservoir.
22. A method according to any one of claims 1 to 19, characterized in that said shuttle reservoir (2) has a solid rigid bottom (5) and includes in its said bottom (5) a second orifice fitted with a second valve (5₄).
23. A method according to any one of claims 1 to 22, characterized in that said evacuation device (6₁-6₄) co-operates with a top orifice (18) of a receptacle (20), said receptacle (20) having a bottom orifice (19) positioned close to and vertically above at least one second pipe (6₄) installed in a said opening in the hull and/or tank (6) so as to be capable of recovering said polluting effluent (1) flowing through said opening by the effluent rising in said bottom orifice (19) of said receptacle (20).
24. A method according to claim 23, characterized in that:

    a) said receptacle (20) presents the form of a funnel having an open large base constituting said bottom orifice (19) and covering a leakage zone of said effluent, said zone including one or more of said openings in the hull and/or the tank (6) of the ship, and the top small base of said tunnel giving access to said top orifice (18) of said receptacle (20) and said receptacle (20) co-operating with positioning means comprising:

    second anchor means for anchoring said receptacle (20) to said ship or said tank (6) or said sea bed (7) comprising second cables (12₂) connecting attachment points (13₂) secured to the circumference of said large base of the funnel to attachment points (14₂) on the ship or said tank (6) or said sea bed (7); and

    tensioning means (15-16-14₂) comprising:

    floats (15-16) connected to the circumference of said open large base of said receptacle (20) and around the tubular section (17) at the top portion of said small base of said funnel; and

    preferably, winches (14₂) corresponding to said attachment points on said ship or said tank (6) or said sea bed (7).
25. An installation suitable for use in a method of recovering polluting effluent contained in the tanks of a sunken and/or damaged ship resting on the sea bed according to any one of claims 1 to 24, the installation being characterized in that it comprises a said shuttle reservoir (2) as defined in any one of claims 1 to 5, 13, and 20 to 22, and preferably said anchor means (12₁-13₁-14₁), and where appropriate a said first disconnection device as defined in any one of claims 6 to 10.
26. An installation according to claim 25, characterized in that it includes a said stabilization device comprising at least one said second connection cable or chain (30) as defined in any one of claims 9 to 12.
27. An installation according to claim 25 or claim 26, characterized in that it includes a said first closure device and a said first disconnection device, and where appropriate a said second closure device for closing the reservoir, as defined in any one of claims 13 to 17.
28. An installation according to any one of claims 25 to 27, characterized in that it includes a said receptacle (20) and where appropriate, said anchor means (12₁-13₁-14₁) and said positioning means (12₂-13₂-14₂) and said tensioning means (14₂-15-16) as defined in either one of claims 23 and 24.

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