WO2013083159A1

WO2013083159A1 - Iso modal container and anchorage structure therefor

Info

Publication number: WO2013083159A1
Application number: PCT/EP2011/071795
Authority: WO
Inventors: Francesco Nettis; Giulio CARINI; Gianfranco NISO; Paolo REDONDI; Vanni Neri TOMASELLI
Original assignee: Blue Wave Co S.A.
Priority date: 2011-12-05
Filing date: 2011-12-05
Publication date: 2013-06-13
Also published as: EA201491129A1

Abstract

An ISO modal container for storage and transportation of a CNG pressure vessel comprises a main longitudinal portion and two end caps, one at each end of the main longitudinal portion. The container comprises a frame body for housing the pressure vessel inside said frame body. The frame body comprises two sides connected by longitudinally extending beams. A pair of attachments, one at each end of the pressure vessel, holds the pressure vessel suspended in place inside the frame body, with the longitudinal portion of the pressure vessel substantially parallel to the longitudinally extending beams of the frame body of the container. The pressure vessel is supported at, or in cooperation with, its end caps rather than being supported on its longitudinal main body.

Description

ISO MODAL CONTAINER AND ANCHORAGE STRUCTURE THEREFOR

The present invention relates to ISO modal containers and to an anchorage structure therefor. In particular, the present invention relates to ISO modal containers and to an anchorage structure for ISO modal containers for transporting compressed natural gas (CNG).

An ISO modal container, or "intermodal" container, is a standardised, reusable container for storage and transportation of materials or goods which can be moved from one mode of transport to another without unloading and reloading the materials or goods. For example, an ISO modal container can be unloaded from a ship and then loaded directly onto a train. From the train, the ISO modal container can then be loaded directly into a cargo airplane, etc. The ship, train and airplane are all configured for receiving and transporting the standardised ISO modal container, or more than one thereof.

Characteristics such as shapes, materials of construction, maximum dimensions, weights and stacking and interlocking features, etc., are prescribed in relevant Standards, and there can be various forms of ISO modal container each categorised according to those Standards. Standard ISO modal containers are therefore readily identified by reference to a particular Standard, which Standards provide recognisable codes of certification, such as "ISO 6346" and others.

Natural gas can be found in underwater wells. The natural gas can be extracted from its source and it can then be stored in the form of compressed natural gas (CNG) in suitable pressure vessels, and those pressure vessels can be transported on ships to shore-based processing plants. For this purpose, a suitable attachment or anchorage structure between the pressure vessels and the ship is needed. Typically this involves semi-permanent fixation of the pressure vessels within the hull of the ship.

A proposal is to use ISO modal containers, since they are already transportable on ships, and are of a size to accommodate CNG pressure vessels with a reasonable storage volume. Pressure vessels for the transport of compressed fluids presently constitute four regulatory agency approved classes or types, all of which are cylindrical with one or two domed ends: Type I. Consists of an all metal, usually aluminum or steel, construct. This type of vessel is inexpensive but is very heavy in relation to the other classes of vessels. The entire vessel is of sufficient strength to withstand the intended pressure exerted on the vessel by a contained compressed fluid and therefore does not require any manner of strength-enhancing over-wrap, including the dry filamentous over-wrap of this invention. Type I pressure vessels currently comprise a large portion of the containers used to ship compressed fluids by sea, their use in marine transport incurs very tight economic constraints.

Type II. Consists of a thinner metal cylindrical center section with standard thickness metal end domes such that only the cylindrical portion need be reinforced, currently with a composite over-wrap. The composite wrap generally constitutes glass or carbon filament impregnated with a polymer matrix. The composite is usually "hoop wrapped" around the middle of the vessel. The domes at one or both ends of the vessel are of sufficient strength to withstand the pressures developed in the vessel under normal use and are not composite wrapped. In type II pressure vessels, the metal liner carries about 50% of the stress and the composite carries about 50% of the stress resulting from the internal pressure of the contained compressed fluid. Type II vessels are lighter than type I vessels but are more expensive. Type III. Consists of a thin metal liner that comprises the entire structure, that is, the cylindrical center section and the end dome(s). Thus, the liner is currently reinforced with a filamentous composite wrap around entire vessel. The stress in Type III vessels is shifted virtually entirely to the filamentous material of the composite wrap; the liner need only withstand a small portion of the stress. Type III vessels are much lighter than type I or II vessels but are substantially more expensive.

Type IV. Consists of a polymeric, essentially gas-tight liner that comprises both the cylindrical center section and the dome(s), all of which is currently fully wrapped with a filamentous composite. The composite wrap provides the entire strength of the vessel. Type IV vessels are by far the lightest of the four approved classes of pressure vessels but are also the most expensive.

As noted above, Type II, III and IV pressure vessel currently require a composite over- wrap over a vessel liner to give them the necessary strength to withstand the intended pressure exerted by a compressed fluid contained in the vessel. It is known, however, that the polymeric matrix of the composite wrap adds little or no strength to the overwrap. Thus, this invention also can be used with novel winding arrangements using a dry filamentous material that is disposed over a pressure vessel liner in a dry state and that is remains in essentially a dry state (i.e. not bonded throughout with an impregnation of resin) for the life-time of the pressure vessel.

"Essentially" in a dry state takes into consideration that, in use, particularly for marine transport of compressed fluids, the filamentous material may inadvertently become dampened by environmental moisture and the like. That is, the dry filamentous material is intended to be disposed over the vessel dry and to be dry when the vessel is put in use. Essentially dry in this context therefore does not exclude situations where the filaments/fibres are wetted by water. Preferably just one pressure vessel is housed in each ISO modal container. The pressure vessel can thus be made as large as possible to as to maximise the amount of CNG that can be transported within the container. As a result, CNG pressure vessels can be conveniently transported from one location to the next in ISO modal containers, either on specialised CNG vehicles, including ships, trains or trucks, i.e. ones that exclusively transport CNG, or on standard ISO modal container vehicles, i.e. ones which transport other ISO modal containers as well.

For single vessel arrangements, preferably the pressure vessels are type 3, type 4 or other newer types formed with other structural wall arrangements that provide a similar or lighter weight to capacity ratio, i.e. ones involving composite materials and fibre wrapping.

Preferably the pressure vessels are neither type 1 (substantially all-steel) pressure vessels nor type 2 pressure vessels - part-wrapped steel vessels. Importantly the pressure vessels are designed to contain CNG - i.e. compressed fluids at pressures in excess of 200 bar, and possibly as high as 350 bar.

CNG pressure vessels pose a specific concern when it comes to transporting them within ISO modal containers due to the fact that the CNG within the pressure vessels is at a very high pressure - say 200bar. Other forms of pressure vessel have been incorporated into ISO modal containers, albeit for storage of ower pressure compressed fluids such as LPG or LNG (at pressures usually below 20 bar) and traditionally the internal anchorage structure comprises pairs of plates, rings or collars provided inside the containers for connecting the main body of the pressure vessels (i.e. normally their central, cylindrical part) to the containers.

If plates are used, they are generally perforated so as to make the anchorage structure lighter. This is necessary since ISO modal containers have maximum loaded weight restrictions due to the need for onward transportation on e.g. cranes or lorries. This also limits the volume of compressed fluid that can be physically carried, given that the pressure vessels are themselves heavy.

The anchorage structures can have various configurations, all of which are designed to support the cylindrical central body of the pressure vessels in place inside the ISO modal containers. For example, more than two such plates, rings, collars - or alternative brackets - can be provided along the central cylindrical part of the pressure vessels. Further, "cages" comprising a number of supporting members can be provided around the pressure vessel's central cylindrical body.

In these prior art arrangements, therefore, supporting the pressure vessel in an ISO modal container has been achieved in a similar manner to that used for transporting large pipes, i.e. supports sized to support a generally cylindrical member. Occasionally the pressure vessels may have to be removed from the containers, e.g. for maintenance operations or repairs. To do this, the pressure vessels can slide out through the plates. Otherwise, the pressure vessels remain assembled in their containers for long periods of time and for many cycles of loading and offloading, i.e. without the vessels being removed from their anchorage structures. With these prior art arrangements, the central cylindrical body of the pressure vessels is the structural part of the pressure vessels that is secured by the plates or rings. With CNG pressure vessels, however, those areas are areas that experience very high internal force loadings due to the high internal pressure of CNG. The action of the external support forces on the cylindrical bodies of the vessels due to the above plates, rings or brackets would therefore undesireably be exerted upon the pressure vessels in addition to the internal forces. This can result in excessive stresses within the cylindrical section of the pressure vessel's walls. Also this stress is usually concentrated in the most mechanically loaded portion of the pressure tank structure: the cylindrical or "hoop" section.

Furthermore, as the pressure vessels in the prior art are constrained radial- symmetrically around circumferential cross sectional portions of their longitudinal bodies, the supports of the prior art also can act as obstacles to cyclical "breathing" of the pressure vessels when they are being filled and emptied. This breathing occurs because during loading and offloading, large internal pressure gradients are present - the initial pressure is high, and the exit pressure is significantly lower than that - and those pressure gradients can drive cycles of radial expansion and contraction through a vessel's body as one or more of the vessels is loaded or unloaded.

Accordingly, the supports of the prior art are not well suited for CNG applications.

It is an objective of the present invention, therefore, to provide an alternative supporting system - one that is suitable for supporting CNG pressure vessels inside ISO modal containers.

It is also an objective of the present invention to try to reduce the risk of excessive stress increases inside the pressure vessels' cylindrical body section. It is a further objective of the present invention to provide an ISO modal container for CNG transportation which can be easily and/or conveniently and/or quickly loaded onto a ship, or unloaded from a ship. It is yet a further objective of the present invention to provide an ISO modal container for transportation of CNG that favours or facilitates operations of loading and unloading of CNG to and from a pressure vessel anchored inside the container. According to a further aspect of the present invention, therefore, there is provided an ISO modal container for storage and transportation of a CNG pressure vessel, the pressure vessel comprising a main longitudinal portion and two end caps, each at respective ends of the main longitudinal portion, the container comprising a frame body for accommodating the pressure vessel therein, said frame body comprising two ends connected by longitudinally extending members or beams, and an attachment for holding the pressure vessel in place inside the frame body, wherein the attachment is configured for supporting the pressure vessel generally at, or in cooperation with, at least one of the end caps of the pressure vessel. The longitudinal portion of the pressure vessel, once fitted within the frame body, may extend substantially parallel to the longitudinally extending beams of the frame body.

Preferably the two ends of the frame body are end sides or end frames. The present invention implements a form of "suspension" structure, with the pressure vessel suspended at at least one of its ends inside the container. This configuration allows for improved (or more freedom for) "breathing" (radial expansion and contraction) of the pressure vessel, which breathing will occur mainly along its central longitudinal body portion, which is usually cylindrical). As a result, "breathing" is advantageously less constrained by the supports of the pressure vessel by means of the present invention, as compared to the supports of the prior art.

Further, such a design of ISO modal container is likely to allow a better distribution of weight on the supports in compared to the prior art, since the (heavy) pressure vessels are likely to be better balanced, or less susceptible to longitudinal rocking, by being supported at their ends rather than along their central bodies, due to the more distant positioning of the support at the neck away from the centre of mass of the vessel.

Further, CNG pressure vessels supported in accordance with the present invention are less likely to undergo axial displacement relative to the containers, and, therefore, be less likely to be accidentally displaced during the operations of loading and unloading of CNG when external pipes are connected to the pressure vessel inside the container, or when the carrier ships pitch in rough sea. This is because the size of the cross section of the pressure vessel at the end caps is smaller than the size of the cross section of the pressure vessel at its main longitudinal body, whereby relative displacement between the support and the pressure vessel is restricted. Accordingly, if the pressure vessel is supported at least at one end, it will be more difficult or impossible for the pressure vessel axially to slide or become displaced in its supports unless the supports are damaged or disassembled.

Furthermore, since the end caps of the pressure vessel are less stressed by the action of the internal pressure forces compare to the main body, due to the lower diameter thereof, the caps are more likely than the pressure vessel's main body to have spare capacity to withstand external supporting forces, whereby the neck is a good location for at least one of the supports.

If at least one of the end frames is generally planar in shape, such as a rectangular or square end frame, the attachment may comprise an arm or a supporting membrane or web which extends from the frame body substantially parallel to said end frame of the frame body.

Further, the arm, membrane or web may extend from one of the end frames of the frame body, and lay generally coplanar with the end frame. Since a corner has a relatively high flexural rigidity, the arm or supporting membrane or web may extend from a corner of the end frame.

The arm, membrane or web might be arranges so as not to penetrate the internal space of the container. In other embodiments, the arm, supporting membrane or web may extend internally, i.e. with penetration into the internal space of the container.

The arm, supporting membrane or web supports or connects the frame body of the container with one of the end caps of the pressure vessel. Preferably, the attachment comprises an arm or a supporting membrane or web which extends into the internal space of the container, into a portion of the internal space available between the end frame of the container and the pressure vessel. This space, into which the arm or supporting membrane or web may extend, can alternatively be defined as the space that would be swept by a longitudinal projection of the container's body over an end frame of the container.

In embodiments comprising an arm, the arm may extend from the frame body to form an angle with a plane perpendicular to the longitudinal direction of the frame body, or a plane defined by one of the end frames of the frame body of the container if one of the end frames is generally planar, so that, if the frame body is seen from one side, perpendicularly with respect to its longitudinal direction, the arm extends out-of-plane from said perpendicular, reference plane. An acute angle may be formed between the arm and said reference plane. The acute angle can be in the range between 1 and 30 degrees, and preferably can be in the range between 10 and 20 degrees.

The arm may extend from a corner region of the frame body, which, because of its inherent relatively high rigidity, is particularly suited to function as an anchorage location on the frame body. In particular, the arm may extend from a corner region located on one of the end frames of the frame body.

Preferably, the arm, or at least a portion thereof, is straight or extends substantially along a straight line. The overall length of the arm may be equal to, or less than, half of the length of a notional geometrical diagonal cutting across the shape of one of the end frames of the frame body.

This is particularly appropriate when they have the geometrical shape of a rectangle or a square.

The arm may be configured to extend from the frame body to point towards a central longitudinal axis of the frame body, such as the pressure vessel's central axis. The arm may comprise a flange, or a flanged portion, and the flange or flanged portion (i.e. these rather than the arm itself) may be configured to support the pressure vessel at, or in cooperation with, the end cap of the pressure vessel (for example, the flange may have holes for bolted connections).

The flange or flanged portion may have an inner side, i.e. a side facing internally with respect to the volume defined by the container's frame body, and said arrangement or configuration to support the pressure vessel may be provided on said inner side of the flange or flanged portion.

In preferred embodiments, the inner side of the flange of the arm can be configured to be attached to an end boss of the pressure vessel (if an end boss is provided on at least one of the end caps of the pressure vessel). Such an arrangement may require a custom configuration, and such a configuration will depend on the geometry and size of the end boss provided. After all, different types of end boss can be used on CNG pressure vessels.

The flange or flanged portion may have an outer side, i.e. a side that faces outwardly with respect to the internal space of the container, and said outer side can be provided with attachment features for attachment of an external element, such as an additional flange, or flanged pipe or the like. This arrangement is useful in operations such as loading and offloading of CNG, for example when there is a need to connect a loading or offloading pipe to the pressure vessel being supported inside the frame body of the container. In these configurations, the flange effectively acts as an interface member for interfacing or facilitating a connection between, for example, a pipe and the pressure vessel.

The flange may have sealing means for establishing a fluid connection between the internal volume of the pressure vessel and the pipe.

The container may have a cover or enclosure as part of, or around, the frame body.

If the container does not have an enclosure on the end side of the container opposite the inlet of the pressure vessel, loading and offloading of CNG are facilitated. If the container is at least partially in communication with the external environment, the container will be safer because any leaking CNG is readily dispersed in the environment. However, some applications may require at least partial enclosure of the internal space of the container.

The attachment and one end frame of the frame body of the container may define an empty space generally located therebetween. That space can be used to allow insertion of a pipe into the container for loading and offloading CNG, or it can be used to provide attachment means between an external pipe network and the internal pressure vessel.

The ISO modal container may have a volume of empty space defined internally of the frame body between the plane of one of the ends and an or the attachment. This can be for the above reason or the gap or space can simply be useful for inspection purposes - there will typically be at at least one end of the each pressure vessel a sealable opening (a manhole) typically having an 18 inch, or even a 24 inch diameter. The opening is an inspection opening.

Given that a very common geometry of pressure vessels is a cylinder with dome-like end caps, the flange or flanged portion can be generally annular or ring-shaped, to mate or match with the geometry of the end cap of the pressure vessel, in order to provide a radial-symmetrical support or connection.

Preferably, the attachment comprises one or more further such arms. Multiple arms can allow the weight of the pressure vessel to be distributed between the multiple arms.

Preferably, the arms are substantially symmetrically disposed around the longitudinal axis of the frame body (and of the pressure vessel, if the pressure vessel is present). Symmetrical arrangements will typically cause the weight of the pressure vessel to be more equally distributed between the various arms.

If the attachment comprises a total of four arms (which are particularly suitable if the frame body and the container have the general shape of a cuboid or prism, e.g. with square or rectangular end frames), then each arm might be provided to extend from one respective corner of one of the end frames of the frame body.

The flange or flanged portion, which - if present - is typically the component that is to support the pressure vessel, or the component that is to be connected to the pressure vessel, can be connected to the arms to enable an interconnection between the four arms.

Alternatively, each arm can have its respective flange or flanged portion, and the separate flanges or flanged portions can be configured individually for supporting, or for connection to, the pressure vessel's end dome or end boss (if one is present).

If a further such attachment is provided, then the pressure vessel can be supported at each of its ends, i.e. at each of the end caps, by a respective one of the attachments.

According to a second aspect of the present invention, there is provided an anchorage structure for anchoring a CNG pressure vessel to an ISO modal container, the ISO modal container having a frame body as defined above, the anchorage structure comprising fastening means for fixing the anchorage structure to the frame body of the ISO modal container, and arranged so that, in use, the anchorage structure assembled to the ISO modal container forms an ISO modal container as defined above.

According to a third aspect of the present invention, there is provided a system for handling, storing and transporting CNG comprising: an ISO modal container as above defined, and a pressure vessel arranged to be supported inside the ISO modal container, and arranged for storage and transportation of CNG.

The present invention also envisions a method of transporting CNG comprising filling ISO modal containers as defined above, and loading the ISO modal containers onto a ship.

The present invention also provides a ship loaded with ISO modal containers as defined above. These and other aspects of the present invention will now be described, purely by way of example, with reference to the accompanying drawings in which:

Figure 1 is a schematic side view of an ISO modal container for transportation of CNG in pressure vessels according to an embodiment of the present invention;

Figure 2 is a schematic partial side view of an ISO modal container for transportation of CNG in pressure vessels according to another embodiment of the present invention; Figure 3 is a schematic side view of an ISO modal container for transportation of CNG in pressure vessels according to a third embodiment of the present invention;

Figure 4 is a schematic front view from side "A" of the embodiment of Figure 3; Figure 5 is a close up schematic of a further embodiment; and

Figures 6 and 7 show further views of that further embodiment.

The figures are not to scale.

Referring first of all to Figure 1 there is shown an ISO modal container 10 for storage and transportation of CNG within a CNG pressure vessel 1 1 thereof. The pressure vessel 1 1 is formed by a main longitudinal portion 19 that extends between two end caps 17, 18, which together define an internal volume of space in which the pressurized CNG is stored.

The container 10 has a structural frame 16 for supporting the pressure vessel 1 1 in the inner space defined by the structural frame 16. The frame 16 has two ends or bases (end sides or end frames) 15a, 15b opposite the end caps 17, 18 of the pressure vessel 1 1 , as shown in Figure 1 . Horizontal structural members or beams 1 16, 1 17 connect the two ends 15a, 15b of the frame 16. In this embodiment, the frame 16 has the geometrical shape of a cuboid or rectangular prism, with square or rectangular bases 15a, 15b. The frame is therefore a form of "box". The box is shown in Figure 1 to be extending horizontally, which is a common configuration for transportation of ISO modal containers 10, e.g. on boats. As such it is longer than it is tall, and likewise is can be wider than it is tall, although a square shape is also anticipated, as shown in Figure 4. The ISO modal container 10 is essentially an open structure, i.e. a "wire-frame" structure, formed of beams, such as steel girders or angle iron, and the frame is thus made of a series of structural members 15a, 15b, 1 16, 1 17 that define the shape of a prism, box or cube, in this embodiment having a pair of opposing square bases 15a, 15b. This shape is especially common for ISO modal containers. However, different shapes might be possible, within the scope of the invention, and relevant Standards will define the appropriate sizes for these variants.

The inner space defined by the frame 16 of the container 10 is not enclosed in this embodiment. This is an advantage in terms of safety and operability in CNG applications: any leaked CNG can readily disperse into the environment, and the pressure vessel 1 1 can be readily accessed for loading and offloading the CNG therein, and also to facilitate inspection or maintenance.

In alternative embodiments, however, at least some of the sides of the container might have panels, covers, screens or the like, provided to provide at least a partial "fuselage" around the container 10. These "panels" could provide a degree of protection for the pressure vessel 1 1 in applications where that was required.

The "panels" might be permanent or removeable, or could even be a temporary cover, such as a fabric sheet, for minimising direct sunlight exposure, or to minimise exposure to sea wash (i.e. spray from waves at sea).

At least one attachment 12a, 12b is provided inside the frame 16 for holding the pressure vessel 1 1 in place, i.e. to prevent or minimise relative displacement (e.g. translations or rotations) of the pressure vessel with the frame 16. Dynamic motion of the pressure vessel on its supports is preferred still to be allowed, such as vertical or axial vibrations or "bouncing" of the pressure vessel 1 1 in the frame 16, but significant movements are restricted so as to prevent the pressure vessel from moving beyond the safety areas within the ISO modal container - a space is required around the pressure vessel to ensure that damage cannot occur thereto when the ISO modal containers are stacked or loaded/unloaded from the ship.

In the embodiments illustrated in Figures 1 , 2, 3 and 4, two types of attachment 12a, 12b, 25, 35a, 35b are illustrated. They are adapted to support respective end caps 17, 18, 27, 37, 38 of the pressure vessels 1 1 , 21 , 31 illustrated. These are preferred configurations, although one end of the pressure vessel 1 1 , 21 , 31 might be supported in an alternative manner, for example in accordance with the prior art, with one perforated plate having a central opening for supporting thereon the main central body 19, 29, 39, of the pressure vessel 1 1 , 21 , 31 .

The longitudinal portion 19, 29, 39 of the pressure vessel 1 1 , 21 , 31 , as it can be seen in Figures 1 , 2, 3 and 4, is configured within the frame 16, 26, 36 to extend parallel to the primary longitudinal beams 1 16, 1 17, 126, 127, 136, 137 of the frame 16, 26, 36 of the container 10, 20, 30, i.e. the edge members thereof.

The attachments 12a, 12b, 25, 35a, 35b are configured for supporting the pressure vessel at the end caps 17, 18, 27, 37, 38 of the pressure vessel 1 1 , 21 , 31 .

In Figure 1 , the attachments 12a, 12b are provided by substantially rigid supporting members made of a metallic material, such as steel. Attachment 12a supports directly a neck portion of the left end dome 17 of the pressure vessel 1 1 . A vertical collar 13 is then provided around the neck of the vessel. The right-hand side attachment 12b is provided instead with a flange 69 for connection to the right end dome 18 of the pressure vessel 1 1 .

The flange 69 functions as an interface between the pressure vessel 1 1 and an external member 89 that can be connected via the flange 69 to the pressure vessel. In Figure 1 , the external member is represented as a bolted-on cap 89, but it could be, in other embodiments, a pipe for loading or offloading CNG. The attachment membranes 12a, 12b are generally inwardly extending, as can be seen in Figure 1 , with them defining a frame arrangement having a concavity when looked at from the outside of the frame. In other words, the membranes 12a, 12b penetrate inwardly into the inner space delimited by the outer frame 16 of the container 10. Seen from an end, however, the membranes take the form of an "X". See, for example, Figure 4.

In the embodiment shown in Figure 2, however, the attachment (again formed of one or more membrane 22) is planar. It has a collar 23 which is attached directly to an end- boss 59 of the pressure vessel 21 .

In alternative embodiments, the membrane could still be planar but it could be provided across one of the end bases 25 of the container 20. That can be imagined by translating the membrane of Figure 2 along the longitudinal direction of the container until it overlaps with the end base 25.

The attachment such as the planar membrane 22 could be integrated into an embodiment in which a panel or screen covers one end side of the container 20. In such a configuration, the end cap of the pressure vessel would reach the end frame 25 of the pressure vessel, and no space 79 would be defined between the pressure vessel 21 and the outer base 25, inside the container 20. This configuration allows an optimised use of the internal space of the frame 26 of the container 20 (more CNG transported in the given space, inside the ISO modal container). However, the end cap might be more susceptible to damage during loading and unloading of the ISO modal container onto or off the ship since the space 79 is provided to reduce the risk of such damage.

In Figure 2, the collar 23 of the membrane 22, for attachment of the end cap 27 of the pressure vessel 21 to the frame 26 of the container 20, is configured similarly to the flange 69 of Figure 1 . It is for attachment to an external CNG loading pipe 189.

In other embodiments, the membranes of Figures 1 and 2 can be replaced by alternative supporting structures, including perforated plates, brackets or the like. In preferred embodiments, the invention comprises at least one arm for supporting the pressure vessel inside the container. An embodiment of ISO modal container comprising supporting arms can be seen in Figures 3 and 4. In Figures 3 and 4, each end cap 37, 38 of the pressure vessel 31 is connected to the frame 36 of the container 30 by means of four arms (together labelled 34) extending each 34a, 34b, 34c, 34d from a corner of one of the bases 35a, 35b or end frames of the container 30. Figure 4 shows an end view of the ISO modal container showing all the supporting arms 34a, 34b, 34c, 34d connecting one of the end domes 38 of the pressure vessel 31 to one of the end frames 35b of the container 30.

Figure 3 shows the two angles a and a' that are formed by the arms with respect to vertical planes defined by the respective end bases 35a, 35b of the container's frame 36 from which the arms extend. It is not mandatory that the two angles a and a' be the same. However, in preferred embodiments said angles are closely similar to one another. When the two angles a and a' tend towards zero, the arms 34 tend to overlap, or lie within, with the plane of the end frames 35a, 35b. When the angles a and a' increase, the arms 34 tend to extend further into the internal space of the frame 36, thus deepening the concavity of the frame formed by the arms, as viewed from outside the frame.

Optimal angles for the two angles a and a' are believed to be in the range of between zero and 60 degrees. Preferred Angles a and a' may be between 10 and 45 degrees, and most preferably, particularly on containers carrying a pressure vessel with a diameter of more than 1 m, angles of perhaps between 10 and 20 degrees are useful. The angle, however, is preferably defined or chosen such that the end domes of the pressure vessel 31 are both contained inside the constraints of the frame of the container 30, and close to or adjacent to the end bases 35a, 35b of the container's frame, but preferably while still leaving enough space for any external components 189 to be attached to the pressure vessel in the available end space 79. Referring, therefore, to Figures 5 to 7, an arrangement where the angle is closer to 30^e is shown. The illustrated angle is actually about 28^e. This embodiment will be further described below. Bear in mind too that an ISO modal container might contain more than one pressure vessel, this preferably be arrangements comprising a plurality of horizontal pressure vessels (e.g. four, or eight arranged in two groups of four, end to end, or nine), each being secured by a set of arms. With this configuration, a wider or more diverse range of angles may be needed, and arms may extend from sidewalls or box edges as well as from the corners of the boxes. Further, not all arms may be of the same length, both where a single pressure vessel is contained in the ISO modal container and where multiple pressure vessels are so contained.

Further, although the arms are illustrated to be generally straight, they can instead be curved or profiled in other ways. By being straight, however, they are best adapted to resist buckling loads during the transportation of the pressure vessels.

The cross section of the arms, and other frame members, are typically L shaped, or I or H shaped or U or C shaped, since they are typically used for such frame designs - their strength properties under bending, torsion, compression and tension are well known. There may be various combinations of such shapes, as required to ensure the ISO modal container meets any required strength requirements under the relevant Standards. Figure 4 shows four arms 34a, 34b, 34c, 34d and a flange 169 forming the right-hand attachment 32b for the container 30 of the third embodiment.

Seen from an end as in Figure 4, each arm is a straight member projecting towards the central longitudinal axis of the pressure vessel 31 and of the container 30.

Geometrically, seen from one end, each arm is provided diagonally with respect to the square end base 35b from which the arms 34 project.

Each arm is attached to a corner of the end base 35b. The arms 34a, 34b, 34c, 34d are interconnected by a flange 169, which has an inner side (facing into the page) for interfacing and connecting with the pressure vessel 31 , and an outer side 40, facing out of the page, configured for connection to an external element, such as a CNG loading pipe, or a clamp therefor, by any suitable attachment means 41 .

In this embodiment, the arms and flange are integrally formed, or are welded together. For example, they might either be cut from plate-stock or be fabricated from a ring and four angle irons.

The angle β formed between each of the arms and its adjacent horizontal member of the frame base 35b, as shown in Figure 4, can vary dependent upon the design of the arms and the design of the flange, and dependent upon the overall shape of the ISO modal container. After all, the flange 169 may have a different shape to that shown in Figure 3. Likewise, the arms might not be straight, or they may have tapering sides,. Yet further, the end of the frame of the container might not be square. Accordingly, the angles β can be greater or smaller than that shown, depending on the location of the attachment of the arms 34 to the flange 40, and on the shape of the container, and on the location of the end cap relative to the container, and on the shape of the arms. In this illustrated embodiment, however, the angle β is about 45 degrees.

In this embodiment, angles β down to perhaps 20 degrees might also be desired, and that might be achieved by changing the shape of the flange 40 so as to have additional extensions, e.g. in the vertical direction. This alteration could make the concavity defined by the arms more open so that access space for making a connection of the end of the pressure vessel to a CNG load or unload pipe is more generous.

As for securing the ISO modal container to the vehicle for transporting the container between locations, standard securement points can be provided in accordance with the relevant Standards. A disclosure of those securement points is not relevant to the present invention, whereby it is not provided herein.

Referring next to Figures 5 to 7, the further embodiment is disclosed. This again has four arms 34 and a flange 40, and it is also capturing the neck area of the vessel 10. However, the vessel has an opening 150 with a plurality of bolt-holes 152 extending in a ring around the opening 150. Those bolt holes correspond with bolt holes 154 in the flange 40. There is then a washer cap 156 with bolts for strapping down the vessel relative to the flange 40 and a tube 158 fits through the arrangement to align the elements together during the connection process.

Two of the bolts 160 are shown in Figure 5.

The arms 34 in this further embodiment are straight but angled out of the plane of the end frame 162 at an angle of about 28^e. This allows the end of the vessel, when mounted, to be within the containment of the ISO modal container, so as to provide access to the end, e.g. even when the pressure vessel is loaded on a ship.

It is also clear that although specific frame arrangements are disclosed, which frame arrangements have anchorage structures for securing a pressure vessel within the ISO modal container that is illustrated, adapting existing ISO modal containers so as to have such anchorage structures extending from their sidewalls or frame corners/edges is also within the scope of the invention, i.e. so as to create further embodiments of ISO modal containers according to the present invention. Accordingly, the above description of the anchorage elements 12a, 12b, 22, 32a, 32b applies equally to equivalent anchorage elements that can be produced independently of the outer frame of the ISO modal containers, whereby they can be retro-fitted to existing ISO modal containers, e.g. as a kit of parts.

As shown in Figures 1 to 7, the pressure vessels 1 1 , 21 , 31 are suspended in the ISO modal containers 10, 20, 30 by their end caps by means of the specifically-built attachments 12a, 12b, 22, 32a, 32b. As a result, the main longitudinal bodies 19, 29, 39 of the pressure vessels have a radially unconstrained space along their lengths for allowing breathing of the pressure vessel, i.e. expansion and contraction under the action of the varying internal pressure forces during loading and unloading of CNG, and also the inevitable expansion anyway as a result of the static pressure one loading is completed - the transportation pressure for CNG is typically around 250 bar.

It will also be appreciated that the rigidity of the attachments 12a, 12b, 22, 32a, 32b will determine the extent to which the pressure vessels 1 1 , 21 , 31 can vibrate axially and/or radially in the ISO modal containers 10, 20, 30 when the containers are, for example, moved around the ships, or during transportation at sea. There is no requirement for them to be very rigid. Indeed, a degree of resilience is beneficial since it can cushion the pressure vessel in the event of adverse loading conditions (e.g. rough sea conditions, and the impacts of large waves either onboard, or against the ship's hull). However, the arrangement of the attachments 12a, 12b, 22, 32a, 32b preferably substantially restrict the amount of axial displacement achievable by the pressure vessels on their supports 12a, 12b, 22, 32a, 32b.

Axial rotation of the pressure vessels might also be resisted by the attachments/flange, although such rotation is generally not undesireable since the freedom to undertake such rotation is likely to ensure that expansion of the pressure vessel's diameter is not resisted.

Compared to the prior art, the present invention, therefore, provides at least an alternative, advantageous ISO modal container, an anchorage structure therefor and a system comprising an ISO modal container and a pressure vessel, for storing, transporting and handling CNG.

The pressure vessel typically is for CNG, but it might be for carrying a variety of gases, such as raw gas straight from a bore well, including raw natural gas, e.g. when compressed - raw CNG or RCNG, or H₂, or C0₂ or processed natural gas (methane), or raw or part processed natural gas, e.g. with C0₂ allowances of up to 14% molar, H₂S allowances of up to 1 ,000 ppm, or H₂ and C0₂ gas impurities, or other impurities or corrosive species. The preferred use, however, is CNG transportation, be that raw CNG, part processed CNG or clean CNG - processed to a standard deliverable to the end user, e.g. commercial, industrial or residential.

CNG can include various potential component parts in a variable mixture of ratios, some in their gas phase and others in a liquid phase, or a mix of both. Those component parts will typically comprise one or more of the following compounds: C₂H₆, C₃H₈, C₄H₁₀, C₅H₁₂, C₆H₁₄, C₇H₁₆, C₈H₁₈, C₉+ hydrocarbons, C0₂ and H₂S, plus potentially toluene, diesel and octane in a liquid state, and other impurities/species. The present invention has been described above purely by way of example. Modifications in detail may be made to the invention within the scope of the claims appended hereto.

Claims

CLAIMS:

1 . An ISO modal container for storage and transportation of a CNG pressure vessel, the pressure vessel comprising a main longitudinal portion and two end caps, each at respective ends of the main longitudinal portion, the container comprising a frame body for accommodating the pressure vessel therein, said frame body comprising two ends connected by longitudinally extending beams, and an attachment for holding the pressure vessel in place inside the frame body, wherein the attachment is configured for supporting the pressure vessel generally at, or in cooperation with, one of the end caps of the pressure vessel.

2. An ISO modal container according to claim 1 , wherein once the pressure vessel is fitted within the frame the attachment connects one end of the frame body to one of the end caps of the pressure vessel.

3. An ISO modal container according to claim 1 or 2, wherein one of the ends of the frame body is generally planar, and the attachment comprises at least one arm extending from the frame body substantially parallel to the end frame.

4. An ISO modal container according to claim 1 or 2, wherein the attachment comprises an arm extending from the frame body substantially out-of-plane with respect to a transversal, cross sectional plane of the container.

5. An ISO modal container according to claim 4, wherein the arm extends so as to substantially define an acute angle with respect to said transversal plane.

6. An ISO modal container according to claim 5, wherein said angle is between 10 and 20 degrees.

7. An ISO modal container according to any one of claims 3 to 6, wherein the arm extends from a corner region of the frame body.

8. An ISO modal container according to any one of claims 3 to 7, wherein the arm extends substantially along a straight line.

9. An ISO modal container according to any one of claims 3 to 8, wherein the longitudinal portion of the pressure vessel is substantially parallel to the longitudinally extending beams of the frame body of the container and wherein the arm extends from one end of the frame body substantially towards a central longitudinal axis of the frame body and of the pressure vessel.

10. An ISO modal container according to any one of claims 3 to 9, wherein the arm has a flange or flanged portion and wherein said flange or flanged portion is arranged for supporting the pressure vessel.

1 1 . An ISO modal container according to claim 10, wherein the flange or flanged portion has an inner side and an outer side and wherein the inner side is arranged for supporting the pressure vessel.

12. An ISO modal container according to claim 1 1 , wherein the outer side is arranged for attachment to an external component.

13. An ISO modal container according to claim 10, claim 1 1 or claim 12, wherein the flange or flanged portion is generally annular.

14. An ISO modal container according to claim 10, claim 1 1 , claim 12 or claim 13, wherein the flange or flanged portion is configured for attachment to an end boss of the pressure vessel.

15. An ISO modal container according to any one of claims 3 to 14, wherein the attachment comprises two or more arms.

16. An ISO modal container according to claim 15, when dependent upon any one of claims 10 to 1 14, wherein at least two arms are interconnected by the flange or flanged portion.

17. An ISO modal container according to claim 15 or claim 16, wherein the arms are substantially symmetrically disposed around a longitudinal axis of the pressure vessel.

18. An ISO modal container according to claim 15, claim 16 or claim 17, wherein the arms are substantially symmetrically disposed around a longitudinal axis of the ISO modal container.

19. An ISO modal container according to any one of claims 15 to 18, wherein at least one of the ends of the container is a quadrilateral and the attachment comprises a total of four arms.

20 An ISO modal container according to claim 19, wherein each arm extends substantially from a respective corner region of the end.

21 . An ISO modal container according to any one of the preceding claims, wherein two attachments are provided, such that each of the end caps of the pressure vessel can be supported by one of the attachments.

22. An ISO modal container according to any one of the preceding claims, wherein a volume of empty space is defined internally of the frame body between the plane of one of the ends and an or the attachment.

23. An anchorage structure for anchoring a CNG pressure vessel to an ISO modal container, the ISO container having a frame body, the anchorage structure comprising fastening means for fastening the anchorage structure to the frame body of the ISO modal container, and being arranged so that, in use, the anchorage structure, once assembled to the ISO modal container, will form an ISO modal container according to any one of the preceding claims.

24. A system for handling, storing and transporting CNG comprising: an ISO modal container according to any one of claims 1 to 22; and a pressure vessel arranged to be supported inside the ISO modal container, the pressure vessel being adapted to be suitable for storage and transportation of CNG.

25. An ISO modal container substantially as hereinbefore described with reference to the accompanying drawings.

26. An anchorage structure for an ISO modal container substantially as hereinbefore described with reference to the accompanying drawings.

27. A system for handling, storing and transporting CNG substantially as hereinbefore described with reference to the accompanying drawings.

28. A ship carrying a plurality of ISO modal containers as defined in any one of claims 1 to 22 or claim 25.