CA2283008C

CA2283008C - Ship or barge based compressed gas transport system

Info

Publication number: CA2283008C
Application number: CA 2283008
Authority: CA
Inventors: P. John Fitzpatrick; David G. Stenning; James A. Cran
Original assignee: Sea NG Corp
Current assignee: Sea NG Corp
Priority date: 1999-09-22
Filing date: 1999-09-22
Publication date: 2007-09-04
Anticipated expiration: 2019-09-22
Also published as: CA2283008A1

Abstract

A marine gas storage and transport system formed of small diameter steel pipe, which is stacked horizontally in a hexagonal pattern. The system is suitable for use on top of a barge or inside the holds of a ship. The horizontal hexagonal stacking and the use of small diameter pipe permit large stacking heights to be reached without over- stressing the pipes at the bottom of the stack. The pipes are laid down in long straight lengths and are manifolded in groups of two (2) and seven (7) at their ends by a unique system that space-wise still permits the hexagonal stacking arrangement and also allows for about 33% (thirty three percent) of the system to be continuously inspected by a pig. Each group of seven can be connected to another group of seven and so also can the groups of two. Thus very large volume storage units can be constructed cheaply and efficiently. In addition when the pipes are stored within the holds of an ocean going ship a transverse watertight bulkhead is created approximately every 20 to 50 meters by infilling the spaces between the pipes with a watertight material. Since the spaces are small the force from the water head is low and the required longitudinal water-tightness can be provided by a number of materials ranging from silicone to epoxy products. This is a unique component of the invention as it precludes the expensive necessity of providing multiple penetrations through a standard watertight bulkhead.

Description

TITLE OF THE INVENTION:

Ship or Barge Based Compressed Gas Transport System NAME(S) OF INVENTOR(S):

P. John Fitzpatrick David G. Stenning James A Cran FIELD OF THE INVENTION:

This invention relates to apparatus and methods for the marine transport and storage of compressed natural gases.

BACKGROUND OF THE INVENTION:

This invention is an improvement on the technology disclosed in US patents nos.
5,839,383 and 5,803,005. The invention relates particularly to the marine gas transportation of non-liquefied compressed gas. Because of the complexity of existing marine gas transportation systems significant expenses are uncurred which render many projects uneconomic. Thus there is an ongoing need to design storage systems for compressed gas that can contain large quantities of compressed gas, simplify the system of complex manifolds and valves, and also reduce construction costs. It is an object of the present invention to do all three.

SUMMARY OF THE INVENTION:

A gas storage system, particularly adapted for the transportation of large quantities of compressed gas on board a ship (within its hold) or on board a simple barge (above or below its deck), primarily by means of simply manifolded long, straight sections of small diameter steel pipe. The pipe in general runs the length of the barge or the ship in continuous straight sections. The pipe, generally smaller than 300mm, is stacked in a hexagonal pattern to reduce stresses and is manifolded at the ends in a manner that does not interfere with the hexagonal stacking, even at the ends. Hexagonal stacking produces a hydrostatic type loading in the pipes and results in much lower bending and buckling stresses than are seen under direct or linear stacking. This combination of manifolding and stacking is a feature of the invention. Another feature of the invention relates to the easy provision of a transverse watertight barrier when the pipes are stored within the holds of a ship or barge. All ships require transverse water-tightness at discrete intervals along the ship length for safety and floatation reasons. Since the gaps between the small diameter pipes are small water-tightness can be achieved by filling these gaps at discrete intervals, normally about 20 to 50 meters depending on the ships overall size, with a product that can withstand a full head of water. This could be a silicone; epoxy or urethane based product. As such the requirement for expensive bulkhead penetrations is not required and the pipes can maintain their straightness and close hexagonal contact throughout the length of the ship.
Certain exemplary embodiments can provide a containment structure, comprising:
a cluster of seven pipes arranged side by side in a hexagonal cross-sectional pattern with a central pipe surrounded by six outer pipes, each of the outer pipes making linear contact with each of two adjacent outer pipes and the central pipe, the cluster of seven pipes having first and second ends; and a first manifold at one end of the cluster of seven pipes connecting each of the seven pipes into fluid communication with a connector pipe.
Certain other exemplary embodiments can provide a transportation storage system, comprising: a deck; plural clusters of seven pipes supported by the deck, each cluster of seven pipes being formed as defined above and supported by each other in a hexagonal stacking pattern; each of the connector pipes being interconnected to place each of the pipes in fluid communication with each other.
Still certain other exemplary embodiments can provide a containment structure, comprising: a cluster of at least three pipes arranged side by side in a triangular cross-sectional pattern, each of the pipes making linear contact with each other, the cluster of at 2a least three pipes having first and second ends; and a first manifold at one end of the cluster of at least three pipes connecting each of the at least three pipes into fluid communication with a connector pipe.
Yet another exemplary embodiment can provide a transportation storage system, comprising: a deck; plural clusters of pipes supported by the deck, each cluster of pipes being formed as defined above and supported by each other in a stacking pattern; each of the connector pipes being interconnected to place each of the pipes in fluid communication with each other.
The gas storage system of the present invention has many advantages. First, the pipe diameter is small and the severity of failure is greatly reduced. Possibly also the probability of failure is also reduced. Second, the technology for the production of long straight lengths of small diameter pipe is well known and inexpensive. Third, approximately 33%
of the system is continuously inspectable by means of an internal pig. Fourth, complicated design features are absent and the manifolds at the ends are simple in nature. Fifth, the idea of manifolding multiple units of small pipe together (approximately seven) to produce a larger type bottle unit greatly reduces the severity of failure since little energy is dissipated by the fracture of a small diameter pipe. Also the incidence of fracture of small diameter pipe in controlled environments is virtually non existent. All these features lead to great cost reductions.
Other features and advantages of the invention become apparent when viewing the drawings and upon reading the detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS:
The preferred embodiments of the invention will now be described, with reference to the drawings, by way of illustration only and not with the intention of limiting the scope of the invention, in which like numerals denote like elements and in which:
Fig. 1 shows an elevation of a typical barge with the gas storage system on top of the deck of the barge;
Fig.2 is an enlarged cross-sectional view of Fig.l;
Fig.3 is an enlarged detail showing an end elevation of the hemi-spherical manifolding system and the hexagonal stacking of the pipes;
Fig.4 is an end elevation of a group of seven pipes. Six of which are tapered or coned into the hemispherical manifold. The central pipe is not tapered;
Fig.5 is a longitudinal plan cross-section of the end system shown in Fig.4;
Fig.6 is a cross-section of an oceangoing double-hulled ship without transverse bulkheads, showing the small diameter pipes in cross-section (only a portion of the pipes is shown); and Fig.7 is an enlargement of the pipe detail showing how water-tightness can be achieved at discrete intervals along the ships length.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS:
Referring now to the drawings, where corresponding similar parts are referred to by the same numerals throughout the different figures, the preferred embodiments are now described. It is also understood that the material employed to make the pipe and its connections will be ductile and not brittle at the proposed operating temperatures. The pipe and its connections may be fabricated from normal grade steel typically X70.
Fig 1 depicts a side elevation 10 of a typically simple barge with a DWT
capacity of typically around 10,000 to 20,000 Tonnes. The CNG storage system is shown covered 12 on the deck of the barge. It is also possible to put the pipe on the deck and have it exposed to the elements as long as the CNG system is adequately protected from the corrosive effects of the elements. Also the barge may or may not be self propelled. The advantage of storing the system on the deck means that the barge does not need any unusual geometry or strengthening within it's holds and it can be easily constructed and towed to the pipe loading site. Also the deck storage permits straight lengths of pipe to be easily placed on board.
Fig. 2 is a cross-section showing the optional weather protection 12 and side retaining system. The barge 10 is of standard construction details.
Fig. 3 shows the stacking hexagonal pattern in cross-section of the pipes 18.
The pipes 18 are formed in clusters of seven pipes, with interspersed individual pipes. The pipes 18 are arranged side by side with a central pipe surrounded by six outer pipes. Each of the outer pipes makes linear contact with each of two adjacent outer pipes and the central pipe. Linear contact, that is, contact along a line parallel to the central axis of the pipe, distributes the loading of the stack of pipes evenly along the pipes.
The pattern is repetitive in that while the overall system remains hexagonal clusters of seven pipes 20 and clusters of two pipes 14,16 form sub-patterns at the ends of the pipe straight sections.
These are the end manifolds 20,14 and 16. The type A and B pipes 14, 16 simply connect back onto themselves with a pipe tube with a bend radius of one or more diameters. The group of seven pipes is connected to another group of seven by means of the central pipe, which is extended and turned through 180 degrees with a bend radius of approximately two or more diameters. In theory it is possible to interconnect every pipe together but this would be unwise since any leakage would involve the entire cargo. Typically there will likely be twenty or more separate cells. Also it is possible to prefabricate the group of seven pipes and lift them into position as a single unit rather than welding the hemi-spherical manifolds in place after placement of the pipes. At this point it can be seen that approximately 33% of the pipes are continuously inspectable by pig.
Fig. 4 shows an enlarged end view of the manifold for the group of seven pipe bundle. The manifold connects each of the seven pipes into fluid communication with a connector pipe. The pipes on the outside reduce or cone to a smaller diameter 22. This coning or diameter reduction may take place over a short or long distance depending on the motions of the barge or ship. When the pitching motion of the ship or barge is expected to be small then for drainage purposes the coning distance may be fairly large in order to encourage natural drainage of fluids into the hemispherical manifold 20 at the ends. A feature of the coning is that it permits the pipes to be manifolded and field welds to be made without interfering with the close hexagonal packing of the pipes.
The central pipe of the cluster of seven 24 is not coned or reduced in diameter.
Fig.5 is a plan cross-sectional view through the center of Fig.4. At the ends of the cones 22 and the central pipe, 24 a flat circular cover plate 28 with holes to match the 5 cone and central pipe diameters is welded on to the pipe cluster. The hemi-spherical containment shel120 is welded to the cover plate with a circular full-strength weld. The hemisphere can be welded to the cover plate 28 either before or after it has been welded to the seven pipes. Also the hemisphere may or may not contain internal strengthening diaphragms to help reduce the shell plate thickness. The transition piece 36 between he central pipe and the external connecting pipe 26 is a pipe of the same diameter as the central pipe except that it has holes in it's wall to allow the gas to communicate between the various chambers. This pipe simply serves as a guidance mechanism for the pig as it moves from one cluster to another in the central pipe.
Fig.6 shows the pipes as they might appear in an ocean going ship 18. Only a few of the pipes are shown and in reality the ship would be full virtually to the top. The ship 30 is different from other ships in that it does not possess transverse bulkheads.
Otherwise it is similar to a double-hulled tanker.
Fig 7 shows a detail of the pipes 18 as they might appear in the area of the transverse watertight seal 32. While the water head design pressure could be as high as 30 meters the actual force on the individual sealing components is quite low due to the small distance that each seal has to span. There are many materials ranging from silicone to epoxy that are more than capable of carrying the design head of water. This innovative feature allows the pipe to essentially lie the full length of the ships without having to penetrate a transverse watertight barrier. This greatly reduces the expense and complexity of the total design.
The pipes may be connected in groups of three (triangular pattern), but this complicates the design and is not preferred. In such an instance, to allow cleaning of one third of the pipes, the location of the connector pipe must be offset over one of the pipes, or a curved central connector that, inside the manifold, is curved to connect to one of the pipes in the cluster of three.

The invention has now been described with reference to the preferred embodiments. Substitution of parts and other modifications will now be apparent to persons of ordinary skill in the art. In particular, the transport system of this invention may be used to transport compressed gasses other than natural gas.
Accordingly, the invention is not intended to be limited except as provided by the appended claim.
Features of the invention thus include, in its various aspects: a barge having a deck or a ship having internal storage; a compressed gas storage system placed on top of the barge deck or in the internal holds of a ship, a plurality of straight lengths of small diameter pipe stacked in a hexagonal pattern; a unique manifolding end capping system that connects the smaller pipes and unifies groups of approximately seven (typically) and approximately two (typically) in such a fashion as to not interfere with the hexagonal stacking pattern of the small diameter pipes; and a unique method of providing a transverse water tight system when the CNG storage is within the holds of a ship.

Claims

1. A containment structure, comprising:

a cluster of seven pipes arranged side by side in a hexagonal cross-sectional pattern with a central pipe surrounded by six outer pipes, each of the outer pipes making linear contact with each of two adjacent outer pipes and the central pipe, the cluster of seven pipes having first and second ends; and a first manifold at one end of the cluster of seven pipes connecting each of the seven pipes into fluid communication with a connector pipe.

2. The containment structure of claim 1 in which the connector pipe is formed of an extension of the central pipe.

3. The containment structure of claim 2 in which the outer pipes are coned at the first end of the cluster of seven pipes.

4. The containment structure of claim 3 in which the manifold comprises:
a plate having apertures to which the coned outer pipes and central pipe are secured;
a hemispherical shell secured to the plate around an outer periphery of the plate; and the connector pipe extending from the hemispherical shell.

5. The containment structure of claim 1 in which a second manifold is provided at the second end of the cluster of seven pipes, the second manifold connecting each of the seven pipes into fluid communication with a second connector pipe.

6. A transportation storage system, comprising:
a deck;
plural clusters of seven pipes supported by the deck, each cluster of seven pipes being formed as defined in claim 1 and supported by each other in a hexagonal stacking pattern;

each of the connector pipes being interconnected to place each of the pipes in fluid communication with each other.

7. The transportation storage system of claim 6 further comprising plural pairs of pipes manifolded together and interspersed with the plural clusters of seven pipes, the plural pairs of pipes being interconnected with the connector pipes.

8. The transportation storage system of claim 6 in which the transportation system is ship based.

9. The transportation storage system of claim 7 in which the deck is in the hold of a ship.

10. The transportation storage system of claim 9 in which the pipes extend the length of the ship.

11. The transportation storage system of claim 6 in which, in each cluster, the connector pipe is formed of an extension of the central pipe.

12. The transportation storage system of claim 6 in which, in each cluster, the outer pipes are coned at the first end of the cluster of seven pipes.

13. The transportation storage system of claim 12 in which, in each cluster, the manifold comprises:
a plate having apertures to which the coned outer pipes and central pipe are secured;
a hemispherical shell secured to the plate around an outer periphery of the plate;
and the connector pipe extending from the hemispherical shell.

14. The transportation storage system of claim 6 in which a second manifold is provided at the second end of each cluster of seven pipes, each second manifold connecting each of the corresponding seven pipes into fluid communication with a corresponding second connector pipe.

15. The transportation storage system of claim 6 in which gaps between the pipes are sealed with seals at periodic intervals along the pipes to form bulkheads.

16. The transportation storage system of claim 7 in which gaps between the pipes are sealed with seals at periodic intervals along the pipes to form bulkheads.

17. A containment structure, comprising:
a cluster of at least three pipes arranged side by side in a triangular cross-sectional pattern, each of the pipes making linear contact with each other, the cluster of at least three pipes having first and second ends; and a first manifold at one end of the cluster of at least three pipes connecting each of the at least three pipes into fluid communication with a connector pipe.

18. The containment structure of claim 17 in which the pipes are coned at the first end of the cluster.

19. The containment structure of claim 17 in which the manifold comprises:
a plate having apertures to which the pipes are secured;
a hemispherical shell secured to the plate around an outer periphery of the plate;
and the connector pipe extending from the hemispherical shell.

20. A transportation storage system, comprising:
a deck;
plural clusters of pipes supported by the deck, each cluster of pipes being formed as defined in claim 17 and supported by each other in a stacking pattern;

each of the connector pipes being interconnected to place each of the pipes in fluid communication with each other.