US3085538A

US3085538A - Ship for the transportation of a liquefied gas

Info

Publication number: US3085538A
Application number: US744164A
Authority: US
Inventors: James J Henry
Original assignee: Conch International Methane Ltd
Current assignee: Conch International Methane Ltd
Priority date: 1958-06-24
Filing date: 1958-06-24
Publication date: 1963-04-16
Anticipated expiration: 1980-04-16
Also published as: BE579698A; FR1226948A

Description

April 16, 1963 J. J. HENRY 3, 8

SHIP FOR THE; TRANSPORTATION OF A LIQUEFIED GAS Filed June 24. 1958 5 Sheets-Sheet l INVENTOR. JAMES J. HENRY ATTORNEYS April 16, 1963 SHIP FOR THE TRANSPORTATION OF A LIQUEFIED GAS Filed June 24. 1958 J. J. HENRY 5 Sheets-Sheet 2 FICI.4-

TY PICA L. INTERMEDIATE WEB FRAME TYPICAL WEB FRAME INVENTOR. JAMES J. HENRY ATTORNEYS April 16, 1963 J. J. HENRY 3,085,538

SHIP FOR THE TRANSPORTATION OF A LIQUEFIED GAS Filed June 24. 1958 3 Sheets-Sheet 3 Flq.6

INVENTOR. JAMES J. HENRY AT TORN EYS United States Patent 3,085,538 SHIP FOR THE TRANSPORTATION OF A LIQUEFIED GAS James J. Henry, New York, N.Y., assignor, by mesne assignments, to Conch International Methane Limited,

Nassau, Bahamas, a corporation of the Bahamas Filed June 24, 1958, Ser. No. 744,164 3 Claims. (Cl. 114-74) This invention relates to a ship and, more particularly, to a ship designed especially for transportation of a liquid cargo which needs to be maintained at a temperature substantially below zero.

This application is a continuation-in-part of my copending application Serial No. 582,965, entitled Ship, filed May 7, 1956, now Patent No. 3,021,808.

While a ship constructed in accordance with the concepts of this invention may be employed for the transportation ofi a wide variety of different types of liquid cargo which needs to be maintained at an extremely low temperature, the present invention will be described with reference to the transportation of liquefied natural gas in large volume at about atmospheric pressure, whereby the liquefied natural gas must be maintained at a temperature below 240 F., depending upon the amount of heavier hydrocarbons in the natural gas. Methane, which is the principal component in natural gas, boils at a temperature of 258 F. at atmospheric pressure.

Since it will be remembered that the land storage of liquefied natural gas at substantially atmospheric pressure has resulted in at least one major catastrophe due to the failure of the structure supporting the storage container, some of the problems incident to the design of a ship for the safe transportation of this same material will be appreciated. v

In hauling liquefied natural gas or methane, hereinafter, for convenience, referred to as the cargo, some of the unusual factors which arise may be enumerated as follows: The cargo should be maintained at substantially atmospheric pressure since the use of containers with walls strong enough to maintain the cargo under superatmospheric pressure of any substantial degree would so materially add to the dead weight of the ship as to make such construction economically unattractive. Means'must be provided for preventing transfer of excessive amounts of heat from the surrounding sea and atmosphere to the cargo to prevent excessive vaporization thereof. The hull of the ship should be thermally insulated from the cargo so that the latter will not cool the hull, especially when made of steel, otherwise the ship will be unsafe. The tanks or the like means in which the cargo is contained should be capable of being hydrostatically tested before assembly into the ship in order toinsure that the tanks will be structurally sound. While the tanks or containers for the cargo should be effectively insulated to minimize the transfer ofi heat, means must be provided whereby access to such tanks can be had for rapid loading and unloading. Since the individual tanks for the cargo will be subjected to severe temperature changes during loading and unloading, their arrangement in the ship must be such that they are adequately supported to prevent damage during the voyage while permitting free movement of the tanks in expansion and contraction without subjecting the ships hull to substantial stresses due to the effects of the temperature changes or temperature graclients which might exist.

By way of further factors relating to the construction of the ship, maximum utilization should be made of the hold space of the ship for the storage of the liquefied gas; means should be provided for maintaining separation between the cargo tanks and the ships hull, otherwise the liquefied gas might inadvertently come into contact with the ships hull to cause the deterioration or destruction thereof when, as is usual, the hull is formed of structural steel plate which loses its ductility at the temperature of the liquefied gas; means should be provided for ready and complete inspection of the walls of the tank and for instrumentation to detect changes in the wall temperatures and the like elements which would indicate either breakdown or failure of the insulation or of the liquid cargo tanks; means should also be provided for inspection of the components of the ship and cargo without interfering with the cargo space or the construction of the space, and it would be desirable to enable construction of the ships hull with lesser space taken up by reinforcement, thereby to make more space available for the cargo to be transported. g

It is among the principal objects of this invention to provide a ship structure which will satisfy many of the FIGURE 3 is a cross-sectional view in the crosswise 7 direction of a ship shown in FIGURE 1;

FIGURE 4 is a detailed sectional elevational view of the cross-section ofi the ship below the top deck and illustrating the construction of the ship and the hold space therein;

FIGURE 5 is a fragmentary sectional elevational view through -a bulkhead of the ship;

FIGURE 6 is a side elevational view taken along the line 66 of FIGURE 5, and

FIGURE 7 is a sectional view taken along the line 7-7 of FIGURE 4.

The concepts of this invention are embodied in a ship 7 construction formed of an outer hull 20 having a bottom 22 and vertically disposed

side walls

24 and 26 in combination with an inner hull 28 having both bottom and side walls which extend in closely spaced apart parallel relation with the corresponding walls of the outer hull throughout the major portion of the ships length which defines the hold space 30*.

The walls forming the outer hull are reinforced by frames or beams 32 which extend lengthwise along the inner surface of the outer hull in fairly closely spaced apart parallel relation and by web frames or

girders

34 and 36 which extend crosswise of the bottom and vertically along the side Walls of the ship in closely spaced apart relation. The inner and outer hulls are interconnected by stiffening and reinforcing members in the form of tie bars 36a which are secured at their outer edges to the inner face of the outerhull and at their inner. edges to the outer face of the inner hull, or to the frames fixed in the desired spaced relation to the adjacent surfaces of the hull members. It will be noted that the thickness of the walls of the outer hull and the dimensions of the beams and frames increase from the top to the bottom of the ship to compensate for the increased loads on the portion of the ship displacing water.

The space between the bulls is divided vertically into compartments or wing tanks by a series of vertically spaced apart platforms 38 secured, as are the plates or tie bars, to the inner and outer surfaces of the outer and inner hulls, respectively, or preferably to the frames, as by means of welding. The platforms are provided with openings to enable free communication between the spaced compartments.

Openings 42 are provided in the web frames for ventilation, and access openings 44 still larger in dimension are provided in the web frames in the areas immediately above the platforms to enable a person to travel in a fore and aft direction-the space between the hulls being sufficient for the passage of a person therebetween.

The space between the hulls is divided laterally by a series of plates, hereinafter referred to as bulkheads 40, which extend upwardly substantially continuously from the bottom to the top of the side Walls to subdivide the space between the inner and outer hulls into a plurality of wing tanks.

The outer surface of the inner hull is similarly stiffened and reinforced with longitudinally extending frames or beams 46 and crosswise extending ribs. The girders can be used to provide a means for attachment of the interconnecting plates or

girders

34 and 36 and interconnecting tie bars 36a, thereby to effect a rigid and fully reinforced connection between the inner and outer hulls.

As defined in the aforementioned application, the ships hold can be divided lengthwise by a plurality of cofferdams which extend crosswise between the hulls. In such crosswise extending coiferdams, it is desirable to make use of a pair of walls 50 and S2 spaced apart by a distance to enable a person to pass therebetween. The described reinforcing and stiffening beams, girders and plates can also be embodied between the walls to enable access to the space between the walls and for subdivision of the space into communicating wing tanks.

The inner surface of the inner hull 28 is lined with a relatively thick layer 54 of an insulating material of low heat conductivity and preferably characterized by having a'structural strength capable of supporting loadto enable attachment to the walls of the inner hull and to enable the cargo tanks to be carried between insulation without direct attachment to the walls of the ship. For this purpose, use can be made of panels of balsa wood or quippo, or use can be made of foamed glass or foamed plastics which are capable of standing up under the temperature conditions to which the plastic will be submitted in the presence of the cargo. The cargo tanks 56 of large dimension are adapted to be arranged in side by side relation within the insulated hold space to'provide a cluster with means harnessing the tanks at the top and operatively engaging the tanks at the bottom to hold the tanks in a predetermined relation within the insulated hold while permitting free expansion and contraction movements in the lateral and vertical directions responsive to changes or variations in temperature which might take place. Thus, the tanks are mounted relatively independently of the insulated hold space, but arranged and constructed substantially completely to fill the hold space.

The means for harnessing the cargo tanks is the subject matter of another application of Farrell, et al., Serial No. 634,571, filed January 16, 1957, now Patent No. 2,954,003, and entitled Means for Transportation of Low Temperature Liquids. The means for lining the walls of the inner hull with panels of balsa wood is also the subject matter of a still further application of Dosker, Serial No.

646,001, filed March 14, 1957, and entitled Heat Insulated Wall and Tank Construction. The means of constructing the tanks preferably of prismatic shape is the subject matter of still a further application of Farrell, et al., Serial No. 634,547, filed January 16, 1957, now Patent No. 2,982,441, and entitled Liquid Storage Tank. The means for mounting the tanks to enable expansion and contraction movements is generally described in the parent application to which reference has previously been made.

Referring now to the ships construction embodying the features of this invention, technological advancements will be found to have been incorporated with reference to its use in the transportation of a cold boiling liquefied gas, as represented by a liquid methane (natural gas) carrier. The double-walled arrangement in the hull structure of the ship with the inner wall lined on its inner surface with a thick layer of a thermal insulating material provides a desired separation between the outer hull of the ship and the ships hold to militate against any possible transmission of the cold from the cargo to the ships hull which might otherwise cause destruction of the ship. This enables the outer hull of the ship to be fabricated of steel plate ordinarily used in the construction of ships, otherwise it would be necessary to make use of special metals which would not lose their ductility when reduced to low temperature. This would result in amateria-l increase in the cost of the ship from the standpoint of the metals employed and their assembly, and it would possibly result in reduction of the stability of the ship from the standpoint of the strength of the metals employed in its construction.

The construction wtih the inner and outer hulls arranged in closely spaced apart, substantially parallel relation enables the beams extending crosswise of the ship and the girders extending lengthwise of the ship to interconnect the hulls in a manner which enables the outer hull to incorporate the inner hull as a part of its reinforcement and support. This enables increased rigidity and strength to be incorporated into the hull structure while making use of beams and girders of considerably lesser width than would otherwise be demanded. This results in lesser space being occupied by the beams and girders joined to the adjacent surfaces of the ships hulls so that more space can be made available in the ship, materially to increase the cargo-carrying capacity of the ship. This condition is not available in a construction wherein a tank is fabricated within the hold of a ship and interconnected to the hull for support, since the described parallel relation and interconnection whereby the inner hull can be tied into the outer hull to enable use of girders and beams of lesser width would not be secured. Further, the necessity to permit free expansion and contraction of the cargo tanks will militate against the rigid connection between the tanks and the hull of the ship.

In the construction with the inner hull arranged in closely spaced apart parallel relation with the outer hull and having girders and ribs in between, a fiat and substantially continuous surface is provided throughout the cargo space of the hold onto which the relaitvely rigid layers of the substantially strong insulating material can be applied thermally to insulate the entire hold space in which the cargo tanks are to be arranged. When use is made of a structurally strong insulation, such as balsa wood, for independently supporting the cargo tanks, it is desirable to enable prefabrication of the balsa wood into boards and planks which can be applied to the support, and it is also desirable to be able to incorporate the supporting structure as a backing for the insulation, whereby the insulation can rely upon its support for strength. Further, when it is desired to make use of the layer of insulation as a second line of defense to block penetration of the cold boiling liquefied gas through the insulation to the metal support, in the event of failure of the cargo tanks or in the event of spillage of the cargo, it

is desirable to be able to make use of the support as a sealing means along the outer surface of the insulation layer, whereby a vapor space will be built up upon evaporation of the liquid to prevent further penetration of the liquid through the insulation layer. This new and novel concept of an internally lined container to prevent penetration of a low boiling liquefied gas which is directly in contact with the porous insulation is more fully defined in the copending application of Morrison, Serial No. 692,388, filed October 25, 1957, and entitled Insulated Tank for Storage" and Transportation of Low Boiling Liquefied Gas. The beams and girders ordinarily present as reinforcement and stiffening members in ship construction or in tanker construction would be incapable of providing the desired surface. On the other hand, the continuous and fiat surface of the inner hull is ideal for receiving the insulation lining, thereby to make all of the space within the inner hull and between the cofferdams available as cargo space, thereby materially to increase the capacity of the ship and utilization of the ship as a liquid methane carrier.

The foregoing represents some of the more important technological advances capable of being derived from the combination of closely spaced apart inner and outer hulls, with the inner surface of the inner hull lined with a thick layer of thermal insulating material to provide an insulated hold space. The double-walled construction can extend throughout the entire length of the ship, but the important area resides along the portion spaced inwardly a short distance from the bow and aft of the ship wherein the cargo space is located. Insulated coiferdams extending crosswise of the ship can provide the desired separation and support for the insulation, and the unlined space in the bow and aft can be employed for housing the mechanism powering the ship and for the storage of other liquids and fuels or cargo which do not require the maintenance of low temperatures.

A large number of further advantages are available in a tanker construction embodying spaced inner and outer hulls with insulation lining the inner surface of the inner hull to provide an insulated hold space.

The spaced inner and outer hulls, providing a sealing relation therebetween, enable utilization of the space as wing tanks wherein water or other fluid can be used as ballast in navigation of the ship. For this purpose, the space can be divided by the bulkheads and the like into separate sections to provide separated wing tanks with individual pumping system for handling the fluid. To make most etficient utilization of the ships space, the wing tanks and the like non-cargo spaces can be used for the storage of liquid petroleum products which do not require refrigeration or maintenance at low temperature. For example, most efficient utilization can be made of the space between the walls to carry a liquid fuel or petroleum products which can be used as ballast and which can be circulated for temperature control and which can even be heated when necessary to conduct cold away from the walls.

The spaced relation between the inner and outer hulls enables one to enter the space for visual inspection of the outer walls of the inner hull for purposes of detecting deterioration in the construction in sufiicient time in advance to prevent failure which might otherwise lead to difficulties and even to the destruction of the ship. It simplifies replacement and repair of sections of the inner hull without tying up the ship in drydock or the like, and it provides space wherein additions can be made to shore up weaknesses which might develop in the construction to anticipate a dangerous situation which might otherwise develop.

Still further, the spaced relationship between the hulls enables instrumentation 160 of the ships hulls for automatically recording changes in conditions as would provide a warning sufficiently in advance of the development of a dangerous condition to enable protective measures to be taken. Such instrumentation would record temperature changes resulting from the development of cold spots possibly caused by the failure of a cargo tank or portions of the insulation in particular areas. These are desirable from the standpoint of protection of the outer hull from refrigeration to a temperature where the steels might lose their ductility and strength.

The closely spaced apart relation between the inner and outer hulls and the subdivision of the space into wing tanks permits the control of temperature in the space between the walls to make certain that safe operating conditions are maintained. In the event of failure of the insulation or in the event of the presence of liquid cargo outside of the cargo tanks in the hold space, the area between the hulls can be heated by means of steam coils and the like to maintain a desired temperature condition between the walls. This will prevent the transmission of cold to the outer hull and it will also operate to maintain the inner hull at a temperature sufficient to prevent loss of ductility and strength. It will also permit maintenance of the temperature of the inner hull at a uniform and desirable level for controlling heat loss through the insulation. Instead of making use of the confined space as a means for heating the walls, the space between the hulls can be used for the rapid circulation of water or other liquid or fluid over the adjacent surfaces of the hulls to conduct cold away from (i.e., furnish heat to) the walls and for controlling the temperature of the walls to maintain safe and controlled operating conditions.

It will be understood that changes may be made in the details of construction, arrangement and operation without departing from the spirt of the invention, especially as defined in the following claims.

I claim:

1. A ship for the transportation of a liquid cargo which needs to be maintained at a temperature far below the freezing point of water comprising the combination of an outer hull, an inner hull joined to the outer hull and spaced in parallel relation to the outer hull throughout the major portion of the ship, horizontally disposed, vertically spaced-apart stiffening and reinforcing members secured to the inner surfaces of the outer hull and the outer surfaces of the inner hull respectively, horizontally disposed vertically spaced-apart platforms extending crosswise between the inner and outer hulls and spaced apart by an amount greater than said stilfening and reinforcing members to subdivide the space between the inner and outer hulls into vertically separated compartments, vertically disposed and longitudinally spaced-apart walls extending crosswise between said inner and outer hulls to subdivide the space therebetween into longitudinally separated wing tanks, some of said walls having passages therethrough above the platforms for communication between the wing tanks, instruments mounted within the space between the bulls for indicated changes in conditions existing therein, bulkheads extending crosswise of the ship in longitudinally spaced-apart relation to subdivide the space within the inner hull into fluid-tight cargo spaces, panels of thermal insulating material mounted on the inner surface of the inner hull to line the cargo space with a thick layer of thermal insulating material, and at least one liquid cargo tank of large dimension within each of said insulated cargo spaces.

2. A ship as claimed in claim 1 in which the thick lining of thermal insulating material lining the inner surface of the inner hull comprises preformed panels of balsa wood secured at their outer surface to the inner hull to provide a substantially continuous lining thereon.

3. A ship as claimed in claim 1 in which each of the bulkheads subdividing the cargo space comprises a pair of walls in closely spaced apart parallel relation.

(References on following page) References Cited in the file of this patent 8 Henry July 28, 1959 Rupp Aug. 4, 1959 Henry Sept. 22, 1959 Howard Apr. 26, 1960 FOREIGN PATENTS Great Britain Feb. 27, 1952 OTHER REFERENCES The Oil and Gas Journal, March 22, 1954 (pages 104, 105 relied on).

Claims

1. A SHIP FOR THE TRANSPORTATION OF A LIQUID CARGO WHICH NEEDS TO BE MAINTAINED AT A TEMPERATURE FAR BELOW THE FREEZING POINT OF WATER COMPRISING THE COMBINATION OF AN OUTER HULL, AN INNER HULL JOINED TO THE OUTER HULL AND SPACED IN PARALLEL RELATION TO THE OUTER HULL THROUGHOUT THE MAJOR PORTION OF THE SHIP, HORIZONTALLY DISPOSED, VERTICALLY SPACED-APART STIFFENING AND REINFORCING MEMBERS SECURED TO THE INNER SURFACES OF THE OUTER HULL AND THE OUTER SURFACES OF THE INNER HULL RESPECTIVELY, HORIZONTALLY DISPOSED VERTICALLY SPACED-APART PLATFORMS EXTENDING CROSSWISE BETWEEN THE INNER AND OUTER HULLS AND SPACED APART BY AN AMOUNT GREATER THAN SAID STIFFENING AND REINFORCING MEMBERS TO SUBDIVIDE THE SPACE BETWEEN THE INNER AND OUTER HULLS INTO VERTICALLY SEPARATED COMPARTMENTS, VERTICALLY DISPOSED AND LONGITUDINALLY SPACED-APART WALLS EXTENDING CROSSWISE BETWEEN SAID INNER AND OUTER HULLS TO SUBDIVIDE THE SPACE THEREBETWEEN INTO LONGITUDINALLY