EP3390887B1

EP3390887B1 - Multiple containment unit of compressed gas cylinders and marine vessel for transporting compressed gas provided with such unit

Info

Publication number: EP3390887B1
Application number: EP16825562.8A
Authority: EP
Inventors: Roberto Provera; Cristiano BATTISTI
Original assignee: Fincantieri Oil and Gas SpA
Current assignee: Fincantieri Oil and Gas SpA
Priority date: 2015-12-18
Filing date: 2016-11-30
Publication date: 2021-02-17
Anticipated expiration: 2036-11-30
Also published as: HRP20210638T1; EP3390887A1; WO2017103718A1; CN108474517A; PL3390887T3; ITUB20159685A1; ES2871030T3

Description

Field of application

This invention relates to a multiple containment unit of compressed gas cylinders and a marine vessel for transporting compressed gas provided with such unit.
The multiple containment unit according to the invention is particularly suitable for the maritime transportation of compressed gas in cylinders. In particular, this multiple containment unit can be installed in the holds of ships or on the decks of barges. This unit can also be installed on submarines or on semi-submersible or floating platforms.
The marine vessel may be of any type, for example a ship or a barge, a submarine means or a semi-submersible or floating platform. The marine vessel can be used to transport compressed natural or industrially produced gas.

State of the art

To date there are still no ships for the transport of compressed gas operating on the market, but only feasibility projects of this type of ships.
In general, these projects involve equipping the marine vessel with a plurality of modular multiple containment units, in jargon called racks. Each modular unit comprises a support structure and, within it, a plurality of pressure vessels (cylinders), fluidically connected to each other to form a single pressure container.
For reasons of structural stability, the modular multiple containment units (racks) are rigidly bound to the structure of the marine vessel. For the same reasons, the cylinders within each rack are also rigidly connected to the containment structure of the respective rack.
This means that, in the first place, the structure of the marine vessel is subjected to stresses generated by the dilations of the single pressure vessels and of the related racks and in turn participates in the deformation of the cylinders and racks, given that it constrains them with its stiffness. In turn, the racks, and thus the single cylinders are subjected to loads induced by the structure of the marine vessel and participate in the deformation of the ship beam. All this greatly affects the expected fatigue life of the pressure vessel (cylinder).
Generally, the rack support structures are realised by means of modular and repetitive elements, connected together to delimit a containment volume in which the cylinders are arranged and constrained. In particular, they are reticular structures made with metal profiles connected to each other by welding or bolted connections. Due to how they are made, i.e., rigidly connected by welding or bolted connection, these structures completely absorb the fatigue stresses of the loading and unloading cycles of the compressed gas in the cylinders bound to them and in turn transmit to the same cylinders stresses induced by the transport means, be it a truck, railway train or a marine vessel.
In particular, when these containment structures are placed inside a cargo hold of a ship, the stresses induced by wave motion and absorbed by the hull of the ship itself are transmitted to the containment unit (rack) of cylinders, with the result of discharging these stresses also on the single cylinders. In fact, as already said, for reasons of structural stability no discontinuities are provided in the chain of transmission of the forces. The racks and related cylinders are thus forced to work in solidarity with the transport means itself.
To prevent the deformations induced by the aforesaid cyclic loads from modifying the design geometry of the rack, impairing the functionality of the gas containment system, the structure of the rack is normally over-dimensioned taking into account of such cyclic loads, with increased cost and weight. Moreover, the influence of the cycles induced by the ship on the rack heavily modifies the fatigue behaviour of the rack and of the cylinders themselves, reducing the expected life of the racks and single cylinders.
A marine vessel for transporting compressed gas according to the preamble of claim 1 is disclosed in US2010/1866426A1 .

Presentation of the invention

Therefore, the purpose of this invention is to eliminate or at least mitigate the drawbacks of the prior art mentioned above, by providing a multiple containment unit of compressed gas cylinders that can be connected in a structurally stable manner to a transport means, in particular a marine vessel and that, at the same time, can translate and deform freely even when the transport means is subjected to significant deformations (as in the case of a marine vessel under unfavourable sea and wind conditions), without, however, being significantly subjected to the stresses and deformations of the transport means itself.
A further purpose of this invention is to provide a multiple containment unit of compressed gas cylinders that does not cause deformations on the cylinders in the case in which its support frame is deformed.
A further purpose of this invention is to make available a multiple containment unit of compressed gas cylinders that is simple and economical to produce.

Brief description of the drawings

The technical characteristics of the invention, according to the above-mentioned purposes, can be clearly understood from the claims listed below and its advantages will become more apparent from the detailed description that follows, made with reference to the attached drawings, which show one or more purely exemplary and non-limiting embodiments wherein:

Figure 1 shows a top perspective view of a single multiple containment unit (rack) of CNG cylinders arranged vertically, according to a preferred embodiment of the invention;
Figure 2 shows a longitudinal orthogonal side view of two multiple containment units illustrated in Figure 1, according to the arrow II indicated therein; the two multiple containment units are represented without cylinders for simplicity of representation of the drawing itself;
Figure 3 shows a simplified top plan view of a set of four multiple containment units according to the invention, as illustrated in Figure 1, with some parts not shown for simplicity of reading the drawing; the four multiple containment units are represented without cylinders for simplicity of representation of the drawing itself;
Figure 4 shows the configuration assumed by the two multiple containment units illustrated in Figure 2 due to a translational deformation of the lower part of the hold with respect to the upper part of the hold itself, on a plane m parallel to the anchoring feet of the rack;
Figure 5 shows an enlarged detail of Figure 2 relative to a support foot of the frame of the containment unit and an associated elastic joint;
Figure 6 shows an enlarged detail of Figure 2 relative to an elastically deformable spacer disposed between the side structures of two containment units according to the invention placed side-by-side;
Figure 7 shows an orthogonal side view in section of the unit illustrated in Figure 1 without support feet, according to the sectional plane S and the arrow II shown therein;
Figure 8 shows a simplified top plan view of the unit illustrated in Figure 1, according to the arrow III indicated therein;
Figures 9, 10 and 11 each show a simplified top plan view of three multiple containment units (racks) of CNG cylinders arranged vertically, according to three different embodiments of the invention;
Figures 12, 13 and 14 each show a detail view of upper connection means between rack and cylinders respectively of Figures 8, 9 and 19;
Figure 15 shows a detail view of lower connection means between the rack and cylinders, according to a preferred embodiment;
Figures 16a and 16b respectively show a simplified orthogonal view in vertical and an orthogonal top plan view of the multiple containment unit (rack) illustrated in Figure 1, when the rack is subjected to a deformation of pure translation;
Figures 17a and 17b respectively show a simplified orthogonal view in vertical and an orthogonal top plan view of the multiple containment unit (rack) illustrated in Figure 1, when the rack is subjected to a deformation of pure flexion; and
Figures 18a and 18b respectively show a simplified orthogonal view in vertical and an orthogonal top plan view of the multiple containment unit (rack) illustrated in Figure 1, when the rack is subjected to a deformation of pure torsion.
Figure 19 shows a simplified plan view of the configuration of a ship for transporting compressed with a segregation in holds, each of which contains a determined number of multiple containment units of cylinders arranged in contiguous rows; and
Figure 20 shows an enlarged plan view of a hold of the ship of Figure 19.

Detailed description

With reference to the accompanying drawings, reference number 1 indicates, in its entirety, a multiple containment unit (rack) of compressed gas cylinders according to this invention and 20 indicates the pressure vessels (cylinders) for the transport of compressed gas installed inside the containment unit. While 100 indicates, in its entirety, the marine vessel for the transport of gas compressed according to the invention, equipped with such multiple containment units 1 of cylinders.
The pressure vessels (cylinders) of the unit 1 can be destined to contain any type of compressed gas, in particular compressed natural gas (CNG).
Here and in the rest of the description and claims, reference will be made to the of multiple containment unit (rack) 1 of cylinders in condition of use. References to a lower or higher position, or a horizontal or vertical direction, should be understood in this sense.
According to a general embodiment of the invention illustrated in the accompanying Figures, the multiple containment unit (rack) 1 (in particular for maritime transport) comprises:

a support frame 10 comprising in turn a support base 11 and a plurality of side containment structures 12 that are structurally connected to the support base 11 and extend vertically from the latter delimiting an inner containment volume 13; and
a plurality of cylinders 20 for containing compressed gas that are connected to said support frame 10 in order to maintain a stable position therein.

The support base 11 of the support frame 10 has a plurality of support feet 14 designed to be rigidly anchored to a portion of a means of transport, in particular a marine vessel 100,
The support base 11 of the support frame 10 is connected to each of the aforesaid support feet 14 by means of an elastic joint 15.
The set of elastic joints 15 create a discontinuity in the transmission of the stresses and deformations between the support feet 14 and the support base 11.
Operationally, the aforesaid elastic joints 15 are dimensioned to allow relative displacements between the feet 14 and the support base 11 on a plane m parallel to the base itself, damping, however, displacements orthogonal to that plane m, as schematically depicted in Figure 4.
When the transport means - to which is connected the transport unit 1 - is subjected to external stresses, it is deformed and consequently also the anchor feet 14 of the unit 1, which are rigidly anchored to the transport means, are deformed. Functionally, the elastic joints 15 that connect the support base 11 to the feet 14 allow the frame 10 to maintain its initial geometry without integrally following the movements of its support feet. These elastic joints 15 dampen the stresses transmitted by the feet to the frame, transforming them into translation movements of the support base (and the entire frame) parallel to the plane of the base itself. Maintaining in this way unaltered, or almost, the geometry of the frame 10 of the unit 1, it is prevented the transmission of mechanical stresses from the structure of the transport means to the containment unit 1 and consequently to the cylinders contained in the unit itself.
All this is particularly significant in the case in which the transport means is constituted by a marine vessel, which in operational life is subjected to wave loads that cause significant elastic deformations of the ship structure to which the multiple containment unit 1 is connected.
Preferably, the support base 11 has a square or rectangular plan. The support base 11 is provided with four support feet 14, each disposed in proximity of one of the four vertices of the base 11.
The set of elastic joints allows the support base 11 to do a relative movement on a plane parallel to the base 11 itself with an extent not exceeding 50 mm compared to a nominal position of vertical alignment of the base 11 with the feet 14. The nominal position of alignment is illustrated in Figure 2.
The elastic joints can be of any type suitable for the purpose, provided that they allow large deformations on the plane of the base and maintain a significant stiffness to vertical deformations.
In particular, each elastic joint 15 can be constituted by an elastic structure constituted by at least two elements each having a different stiffness with respect to the other on the plane parallel to the base 11 and in a direction orthogonal to the plane itself.
More in detail, each of these two elements having a different stiffness is connected to the support base 11 at a first end portion 16' and is connected to the respective support foot 14 at a second end portion 16", opposite the first.
Preferably, each of these two elements having a different stiffness is connected to the support base 11 by means of a first rigid plate 17, rigidly connected to the base, and is connected to the respective support foot 14 by means of a second rigid plate 18, rigidly connected to the support foot 14.
Preferably, as illustrated in Figures 1 to 6, in addition to the elastic joints 15 connecting the support base 11 to the feet 14, the multiple containment unit 1 of cylinders comprises a plurality of elastically deformable spacers 19, anchored to the side structures 12 of the frame 10.
Advantageously, these elastically deformable spacers 19 are positioned to at least a different height with respect to the support base 11.
Operationally, these elastically deformable spacers 19 are suitable to prevent - during movements of said unit 1 on the plane of its support base 11 - the direct contact of said multiple containment unit 1 of compressed gas cylinders with other similar units adjacent to it and/or with structures of the means of transport adjacent to said unit 1.
Advantageously, as illustrated in Figures 2, 3 and 4, the aforesaid elastically deformable spacers 19 can mechanically connect the aforesaid multiple containment unit 1 of compressed gas cylinders to one or more other similar units 1 adjacent to it, thus creating continuity between the units 1. In this way it is possible to distribute the stresses between the units 1 themselves and reduce the amplitude of the movements to which the single multiple containment unit 1 is subjected.
In particular, these elastically deformable elements 19 that connect the units 1 to each other can be constituted by elastic joints.
In the preferred case of application on marine vessel, it has to be noted that the structure of the marine vessel (cargo hold, hull and decks) has a greater elastic stiffness than the single containment unit 1 by several orders of magnitude.
By connecting together a suitable number of units 1 as described above using the aforesaid elastic joints 19 (preferably to form longitudinal rows of units 1, as will be taken up again in the rest of the description), it is possible to create an assembly that has an elastic stiffness comparable to that of the ship's structure, able to deform in a controlled manner.
In particular, the single containment unit 1 is connected to similar units 1 adjacent to it by means of elastic joints 19 in one or more different positions, of which at least one in vertical position in the upper part of the frame 10 so as to limit the relative displacements between adjacent units.
The elastic joints 15, which are placed in connection between feet 14 and support base 11 of the frame 10, and possibly the elastically deformable spacers 19 (preferably in the form of elastic joints) constitute in their whole a mechanical system that allows significantly reducing the static and dynamic stresses from the transport vehicle to the unit 1 (in particular, from the ship's structure to the unit 1).
In particular, in the case of a marine vessel, it appears sufficient, within a range of limited values, to allow the translations of the rack along the two horizontal reference axes X and Y of the ship, possibly by connecting several racks together to ensure sufficient inertia such as to reduce the amplitude of the movements and of the related deformations.
This means realising a marine vessel for transporting compressed gas in which the structure of the vessel itself is completely unaffected by deformations of the load system and, not being structurally connected to the load system, does not influence in any way the fatigue life of the pressure vessels and other elements constituting the modular containment unit.
This invention relates to a marine vessel 100 for transporting compressed gas, comprising a plurality of cylinders 20 for containing the compressed gas grouped in single multiple containment units.
The marine vessel 100 can be of any type. Preferably, the marine vessel 100 is a ship or a barge, but it can also be a submarine or semi-submersible or floating platform.
The marine vessel 100 can be used to transport compressed natural or industrially produced gas.
In particular, the multiple containment units can be installed in the holds (in the case in which the marine vessel is a ship, as illustrated in Figures 19 and 20) or on a deck (in the case the marine vessel is a barge).
At least part of the aforesaid multiple containment units are constituted by multiple containment units 1 according to this invention and in particular as described previously.
Preferably, all the multiple containment units in which the cylinders 20 are grouped are constituted by multiple containment units 1 according to the invention.
However, embodiments can be provided for in which part of the multiple containment units are of conventional type, i.e., with the respective support frames rigidly constrained to the ship's structure without the interposition of elastic joints.
Preferably, as illustrated schematically in Figures 19 and 20, the multiple containment units 1 are arranged in rows 50. Each row 50 is composed of single multiple containment units 1 mutually aligned and juxtaposed head to head one against the other. This spatial configuration is preferably adopted in the case in which the marine vessel is a ship and the units 1 are installed in the holds 101.
Advantageously, the units 1 of each single row 50 are connected to the adjacent units 1 belonging to the same row 50 in correspondence of the respective side structures 12 by means of the already mentioned elastically deformable spacers 19, which are positioned at least at two different heights with respect to the support bases 11. In this way, continuity is created between the units 1 of a row 50 helping to reduce the deformations of the single units 1 induced by stresses transmitted to said units by the marine vessel 100.
Preferably, as illustrated in particular in Figure 20, each row 50 of multiple containment units 1 is delimited on both sides by a longitudinal corridor 51 parallel to it and ends at both ends 50' and 50" on a transverse corridor 52 orthogonal to the longitudinal corridors 51.
As illustrated in the accompanying Figures, the cylinders 20 of the single multiple containment units 1 are arranged vertically along a longitudinal extension axis X within the containment volume 13 defined by the support frame 10. The number of cylinders contained by the unit (rack) 1 can vary depending on the configuration selected for the unit itself.
As described above, the connection system between frame 1 and the transport means, realised through the aforesaid elastic joints 15, and possibly also through the elastically deformable spacers 19, allows significantly reducing the intensity and amplitude of the deformations of the frame 10, but does not allow eliminating them completely.
The cylinders 20 can be rigidly connected to the frame 10. In this case, the deformations of the frame 10 - although attenuated by the aforesaid frame/transport means connection system - can therefore be transferred to the cylinders connected to it and affect the fatigue life of the cylinders. This must necessarily be taken into account during the phase of dimensioning the cylinders themselves, with an increase in the production costs of the cylinders. In fact, the cylinders must in fact be properly dimensioned to withstand the fatigue cycles induced by the deformations caused by deformations of the frame, in addition to the fatigue cycles induced by deformations resulting from the loading and unloading cycles of the cylinders themselves.
This invention provides for combining the already described connection system of the frame 10 to the transport means (based precisely on the elastic joints 15 and possibly on the elastically deformable spacers 19) with a specific connection system between each cylinder and the frame 10 that prevents the transmission of residual deformations from the frame to the cylinders.
Such a connection system between each cylinder and the frame will be described below with the aid of Figures 7 to 18.
More in detail, as shown in particular in Figures 7 and 15, each cylinder 20 is connected to the support base 11 through a lower connection device 30 comprising:

a support element 31 in correspondence of which the cylinder 20 abuts with its own longitudinal bottom end 21; and
a spherical joint 32 that constrains the support element 31 to the support base 11, allowing the free rotation of the support element 31 and of the cylinder 20 resting on it with respect to the support base 11, but preventing translations thereof with respect to the support base 11.

Thanks to the spherical joint 32, the support element 31 can rotate in the half-space above the support base on all axes. In this rotational movement, the longitudinal extension axis X of the cylinder describes a cone with vertex on the spherical joint. Taking into account the spatial and dimensional constraints imposed by the positioning of the cylinder in the rack and with respect to the other cylinders, the rotation on the spherical joint 32 is limited. Preferably, the rotation is such that the aforesaid cone has an aperture angle of not more than 0.1°. In the case of a cylinder 24 m high, a rotation at the base with an angle of 0.1° imposes on the longitudinal extension axis X of the cylinder a deviation from the vertical, measured at the top of the cylinder in the horizontal component (translation), not more than 50 mm.
The multiple containment unit 1 also comprises a vertical support structure 40 of the cylinders 20 that:

is bound to the side structures 12 of the frame 10 at a predetermined height H from the support base 11; and
defines for each single cylinder 20 a vertical positioning seat 41.

Each cylinder 20 is free to translate axially (i.e., along its longitudinal extension axis X) inside the respective vertical positioning seat 41 with respect to the vertical support structure 40.
Operationally, the vertical support structure 40 accompanies the cylinders 20 in the movements of the side structures 12 of the frame, seconding the rotations of each cylinder 20 permitted by the respective lower connection device 30 without transmitting to them bending and/or twisting moments and, at the same time, keeping the cylinders 20 separated from each other according to a predefined positioning plan layout.
This invention therefore provides for connecting each single cylinder 20 to the support frame 10 by means of a mechanical connection system that is composed of two separate support systems, one acting on the bottom portion of the cylinders (i.e., the aforesaid lower connection device 30) and one acting on a portion placed higher up with respect to the bottom (i.e., the aforesaid vertical support structure 40).
The vertical support structure 40 can act at any height of the cylinder, provided that the connection with the cylinder is ensured in the event of the maximum expected axial sliding.
Thanks to the invention, the support frame 10 of the containment unit 1 can deform freely even with unfavourable sea and wind conditions, in the case of maritime transport, without this causing significant effects on the cylinders. In fact, thanks to the invention, the cylinders are free to move with respect to the support frame 10, although keeping themselves substantially together according to a predefined positioning plan layout. This is achieved by separating the cylinders 20 from the support frame 10, so as to prevent (or at least significantly limit) the transmission of static and dynamic stresses from the frame 10 to the cylinders 20.
Thanks to the invention, it is thus possible to prevent, over time, overloading of the most rigid element (the cylinder, with gas under pressure), when the most flexible element (the support frame) is deformed following the stresses of the transport means that contains them both.
This advantage becomes evident when the transport means, in the entire duration of its operating life, performs a number of stress cycles so high as to make an adequate dimensioning of the rigid element (cylinder) economically impractical.
The aforesaid support frame 10 of the containment unit 1 is a structure having a stiffness lower than the cylinders 20 arranged in it and is able to deform when it is subjected to dynamic loads imposed by the transport means inside which it is installed.
Preferably, the support frame 10 is a lattice-like structure made of metal sections connected to each other by welding or bolted connections.
Advantageously, as illustrated in particular in Figure 15, the support element 31 can be shaped so as to define a support seat having a shape corresponding to the shape of the bottom end of the cylinder. In particular, the support element 31 is constituted by a cradle.
Preferably, the support element 31 is made of metallic material.
Advantageously, as illustrated in Figure 15, the lower connection device 30 can comprise a mattress 33 of elastically deformable material interposed between the support element 31 and the bottom end 21 of the cylinder.
This mattress 33 is suitable to dampen any vibrations and/or vertical stresses transmitted by the support frame 10 to the cylinder 20.
Preferably, the elastically deformable material that forms the mattress 33 provides a coefficient of friction with the cylinder 20 sufficient to keep the cylinder 20 resting in the support element 31 in the event of vertical and/or side accelerations received by the cylinder itself.
According to the embodiment illustrated in Figures 7 to 18, the aforesaid vertical support structure 40 of the cylinders comprises:

a plurality of collars 42, one for each cylinder 20, each of which defines the positioning seat 41 for the respective cylinder 20; and
a plurality of spacer elements 43 which connect the collars to each other and to the side structures 12 of the frame 10 positioning the collars between them and with respect to the side structures according to a predetermined positioning plan layout.

Operationally, the aforesaid spacer elements 43 connect the collars 42 to each other and to the side structures 12 of the support frame 10, uncoupling the collars from each other and from the side structures as regards the transmission of bending and/or twisting moments.
In particular, as illustrated in Figures 12 and 13, each spacer element 43 can be constituted by a double ball joint.
As illustrated in Figures 10 and 14, each spacer element 43 can be constituted by an elastic joint equivalent to a double ball joint.
The elastic joints can be arranged in the points of minimum distance between collar and collar and between collar and frame (as shown in Figure 8), or, alternately, along a diagonal direction of maximum distance between collar and collar and between collar and frame (as shown in Figure 9). The latter configuration can be used advantageously in the case in which the space between the cylinders 20 is extremely reduced.
Advantageously, the collars and the spacer elements can be made in one piece with each other to form a single structure 45 made of elastically deformable material.
In particular, as illustrated in Figure 11, this single structure made of elastically deformable material can be constituted by a panel 45, comprising a plurality of main through-openings 46, each of which defines a vertical positioning seat for a cylinder. The edge portion of each main through opening 46 defines a collar, while the portions of panel 47 arranged between the aforesaid main through openings 46 constitute the aforesaid spacer elements.
As illustrated in Figure 11, the aforesaid panel 45 can comprise a plurality of secondary through openings 48, having in particular a lightening function, made in the portions of panel disposed between the aforesaid main openings. The spacer elements are defined by the portions of panel 47 arranged between the main openings 46 and the secondary openings 48.
Advantageously, the aforesaid vertical support structure 40 comprises, for each collar 41, an interposition structure 44 made of elastically deformable material interposed between the collar 41 and the respective cylinder 20. This structure 44 is suitable to allow displacements of the cylinder due to thermal expansion and mechanical deformation of the cylinder itself that occur in cycles of loading and unloading the cylinder. Generally, these displacements are of the order of 20-30 mm.
In particular, this interposition structure 44 is a continuous structure, which extends for the entire perimeter of the cylinder in cross-section, or a discontinuous structure, consisting of a plurality of elements distributed along the perimetric extension of the cylinder in transverse cross-section, for example in the form of slide blocks.
Advantageously, the elastically deformable material which forms aforesaid interposition structure 44 provides a coefficient of friction with the cylinder 20 sufficiently low as not to hinder the axial translations of the cylinder relative to the collar 42.
As already said above, according to the particularly preferred embodiment illustrated in Figures 7 to 18, this invention provides for connecting each single cylinder 20 to the support frame 10 by means of a mechanical connection system that is composed of two separate support systems, one acting on the bottom portion of the cylinders (i.e., the aforesaid lower connection device 30) and one acting on a portion placed higher up with respect to the bottom (i.e., the aforesaid vertical support structure 40).
Thanks to the combined action of these two connection systems 30 and 40, in all the possible mechanical deformations to which the frame 10 can be subjected, the deformation of the frame 10 does not transmit a bending or twisting moment to the cylinders 20, but only generates a rigid rotation movement of each cylinder around a point of rotation in the space located at the bottom of the cylinder itself. However, this rigid rotation movement in space does not result in any additional structural stress of the cylinders themselves.
Figures 16 a-b, 17 a-b and 18 a-b schematically illustrate some possible states of deformation of the support frame of the containment unit and the position consequently assumed by the cylinders.
In particular, Figures 16 a-b illustrate the effects of a pure translational deformation of the frame. It causes a rigid rotation of all the cylinders, and in particular a rotation of the bottom portion of each cylinder on the plane of the translation and a rotation-translation of the vertical support structure 40.
Figures 17 a-b illustrate the effects of a pure flexional deformation of the frame. It causes a rigid rotation of all the cylinders, and in particular a pure rotation of the bottom portion of each cylinder on the plane of the flexion and a rotation or rotation-translation of the vertical support structure 40.
Figures 18 a-b illustrate the effects of a pure torsional deformation of the frame. It causes a rigid rotation of all the cylinders, and in particular a pure rotation of the bottom portion of each cylinder on the plane of the torsion and a torsion-translation of the vertical support structure 40.
Any other type of deformation of the frame 10 is definable as a geometrical combination of the three types of deformation described above. Consequently, the cylinders 20 will be only subjected to corresponding rigid rotations as a combination of single deformations of the frame.
The invention allows obtaining many advantages in part already described.
The multiple containment unit 1 of compressed gas cylinders according to the invention is structured in such a way that it can be connected in a structurally stable manner to a transport means, in particular a marine vessel and that, at the same time, it can translate and deform freely even when the transport means is subjected to significant deformations (as in the case of a marine vessel under unfavourable sea and wind conditions), without, however, being significantly subjected to the stresses and deformations of the transport means itself.
As illustrated in Figures 7 to 18, the multiple containment unit 1 of compressed gas cylinders is also specifically structured in such a way that the support frame can deform freely even with unfavourable sea and wind conditions, in the case of maritime transport, without any significant effect in terms of deformations on the cylinders, which are free to move relative to the frame.
In the case of maritime transport, the cylinders can thus be dimensioned considering only the cycles of loading/unloading gas (on the order of 10^3 in 20 years) and not the wave load cycles (on the order of 10^6 in 20 years) related to the maximum wave stress sustained by the support frame of the containment unit 1.
The multiple containment unit of compressed gas cylinders according to the invention is also simple and economical to manufacture.
The connection systems between the frame and transport means and between cylinders and support frame are in fact constructively simple to make and to assemble, and do not include complex components. They are also of mechanical systems, which intervene mechanically in an automatic way without the need for a control and actuation system.
Therefore, the invention thus conceived achieves the predefined purposes.
Obviously, it may even assume, in its practical embodiment, forms and configurations different from that illustrated above without, for this reason, departing from the present scope of protection.
Moreover, all the details may be replaced by technically equivalent elements and the dimensions, forms and materials used may be any according to the needs.

Claims

Marine vessel for transporting compressed gas, comprising a plurality of cylinders (20) for containing compressed gas grouped into single multiple containment units (1), wherein at least some of said units (1) are multiple containment units (1) of compressed gas cylinders, each comprising:
- a support frame (10) comprising in turn a support base (11) and a plurality of side containment structures (12) which are structurally connected to the support base (11) and extend vertically therefrom defining an inner containment volume (13); and

- a plurality of cylinders (20) for containing compressed gas which are connected to said support frame (10) in order to maintain a stable position therein, said cylinders (20) being arranged vertically along their longitudinal extension axis (X) inside the containment volume (13) defined by the support frame (10),
wherein the support base (11) of the support frame (10) has a plurality of support feet (14) designed to be rigidly anchored to a portion of a means of transport,
wherein in each of said multiple containment units (1) of compressed gas cylinders the support base (11) of the support frame (10) is connected to each of said support feet (14) by means of an elastic joint (15), the set of elastic joints (15) creating a discontinuity in the transmission of stresses and of deformations between the support feet (14) and the support base (11), said elastic joints (15) being sized to allow relative movements between the feet (14) and the support base (11) on a plane parallel to said base, dampening shifts orthogonal to said plane,
characterised in that each cylinder (20) is connected to the support base (11) by means of a lower connection device (30) comprising:
- a support element (31) at which the cylinder (20) abuts with a longitudinal bottom end (21), and

- a spherical joint (32) which constrains said support element (31) to the support base (11), allowing the free rotation of said support element (31) and of the cylinder (20) resting on it with respect to the support base (11), but preventing translations thereof with respect to said support base (11),
and in that the multiple containment unit (1) comprises a vertical support structure (40) of the cylinders (20) which is constrained to the side structures (12) of the frame (10) at a predetermined height (H) from the support base (11) and which defines for each individual cylinder (20) a vertical positioning seat (41), each cylinder (20) being free to translate axially within its respective seat (41) with respect to said vertical support structure (40), which accompanies the cylinders (20) in the movements of the side structures (12) of the frame, following the rotations of each cylinder (20) permitted by the respective lower connecting device (30) without transmitting to them bending and/or twisting moments and while keeping the cylinders (20) separate from each other according to a predetermined positioning plan view layout.
Marine vessel according to claim 1, wherein each elastic joint (15) consists of an elastic structure composed of at least two elements having a different stiffness to each other on the plane parallel to the base (11) and in a direction orthogonal to said plane, wherein preferably each of said two elements having a different stiffness is connected to the support base (11) at a first end portion (16') and is connected to the respective support foot (14) at a second end portion (16"), opposite the first, wherein preferably each of said two elements having a different stiffness is connected to the support base (11) by means of a first rigid plate, rigidly connected to the base, and is connected to the respective support foot (14) by means of a second rigid plate (18), rigidly connected to the support foot.
Marine vessel according to one or more of the claims from 1 to 2, wherein the set of elastic joints allows the support base (11) to do a relative movement on a plane parallel to said base (11) with an extent not exceeding 50 mm compared to a nominal position of vertical alignment of the base (11) with the feet (14).
Marine vessel according to one or more of the preceding claims, comprising a plurality of elastically deformable spacers (19), anchored to the side structures (12) of the frame (10) and positioned at least at a different height from the support base(11), said elastically deformable spacers (19) being suitable to prevent - during movements of said unit (1) on the plane of its support base (11) - the direct contact of said multiple containment unit (1) of compressed gas cylinders with other similar units adjacent to it and/or with structures of the means of transport adjacent to said unit (1), wherein preferably said elastically deformable spacers (19) mechanically connect said multiple containment unit (1) of compressed gas cylinders to one or more other similar units (1) adjacent to it, creating continuity between the units (1) so as to distribute the stresses between said units (1) thereby reducing the extent of movement of said unit (1).
Marine vessel according to one or more of the preceding claims, wherein the support element (31) is shaped so as to define a support seat having a shape corresponding to the shape of the bottom end of the cylinder, preferably said support element (31) being composed of a cradle, wherein said support element (31) is preferably made of metal.
Marine vessel according to one or more of the preceding claims, wherein the lower connection device (30) comprises a mattress (33) of elastically deformable material interposed between the support element (31) and the bottom end (21) of the cylinder, said mattress (33) being suitable to dampen possible vibrations and/or vertical stresses transmitted by the frame (10) to the cylinder.
Marine vessel according to claim 6, wherein the elastically deformable material which forms the mattress (33) provides a coefficient of friction with the cylinder (20) sufficient to keep the cylinder (20) resting in the support element (31) in the event of vertical and/or side accelerations received by said cylinder.
Marine vessel according to one or more of the preceding claims, wherein said vertical support structure (40) comprises:
- a plurality of collars (42), one for each cylinder (20), each of which defines the positioning seat (41) for the respective cylinder (20); and

- a plurality of spacer elements (43) which connect the collars to each other and to the side structures (12) of the frame (10) positioning the collars between them and with respect to the side structures according to a predetermined positioning plan layout.
Marine vessel according to claim 8, wherein said spacer elements (43) connect the collars (42) to each other and to the side structures (12) uncoupling the collars from each other and from the side structures as regards the transmission of bending and/or twisting moments.
Marine vessel according to claim 8 or 9, wherein each spacer element (43) consists of a double ball joint or consists of an elastic joint equivalent to a double ball joint.
Marine vessel according to claim 8 or 9, wherein said collars and said spacer elements are made in one piece with each other to form a single structure of elastically deformable material, which preferably consists of a panel, comprising a plurality of main through openings, each of which defines a vertical positioning seat for a cylinder, the edge portion of each main through-opening defining a collar and the portions of panel positioned between said openings constituting said spacer elements, wherein preferably said panel comprises a plurality of secondary through openings made in the portions of panel positioned between said main openings, said spacer elements being defined by portions of panel positioned between the main and secondary openings.
Marine vessel according to one or more of the claims from 8 to 11, wherein said vertical support structure (40) comprises for each collar (41) an interposition structure (44) made of elastically deformable material interposed between the collar (41) and the respective cylinder (20) suitable to permit shifts of the cylinder due to the thermal expansions and mechanical deformations of said cylinder which occur in the loading and unloading cycles of the cylinder, wherein preferably said interposition structure (44) is a continuous structure, which extends for the entire perimeter of the cylinder in cross-section, or a discontinuous structure, consisting of a plurality of elements distributed along the perimetric extension of the cylinder in transverse cross-section, wherein preferably the elastically deformable material which forms said interposition structure (44) provides a coefficient of friction with the cylinder (20) sufficiently low as not to hinder the vertical translations of the cylinder relative to the collar (42).
Marine vessel according to one or more of the preceding claims, wherein said support frame (10) is a lattice structure having a stiffness lower than the cylinders arranged in it and is able to deform when it is subjected to dynamic loads imposed by the means of transport inside which it is installed.
Marine vessel according to one or more of the previous claims, wherein said multiple containment units (1) are arranged in rows (50), each row (50) being composed of individual multiple containment units (1) aligned with each other and placed alongside head to head, one against each other, the units (1) of each single row (50) being connected to the adjacent units (1) of the same row (50) at the respective side structures (12) by means of elastically deformable spacers (19), which are positioned at least at two different heights from the support bases (11), thereby creating continuity between the units (1) of a row (50) helping to reduce the movements of the individual units (1) induced by stresses transmitted to said units by the marine vessel.
Marine vessel according to claim 14, wherein each row (50) of multiple containment units (1) is delimited on both sides by a longitudinal corridor (51) parallel to it and ends at both ends (50'; 50") on a transverse corridor (52) orthogonal to the longitudinal corridors (51) .